X-Git-Url: https://git.tcpdump.org/libpcap/blobdiff_plain/b11ddf8a9b0d30bf759abf01afcf2894e79857b1..6de2dedb10df2f18db55e41f59b47824de314279:/pcap-linux.c diff --git a/pcap-linux.c b/pcap-linux.c index e1ff4d10..de14a7ec 100644 --- a/pcap-linux.c +++ b/pcap-linux.c @@ -1,331 +1,4354 @@ /* - * Copyright (c) 1996, 1997 - * The Regents of the University of California. All rights reserved. + * pcap-linux.c: Packet capture interface to the Linux kernel + * + * Copyright (c) 2000 Torsten Landschoff + * Sebastian Krahmer + * + * License: BSD + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in + * the documentation and/or other materials provided with the + * distribution. + * 3. The names of the authors may not be used to endorse or promote + * products derived from this software without specific prior + * written permission. + * + * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED + * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. + * + * Modifications: Added PACKET_MMAP support + * Paolo Abeni + * + * based on previous works of: + * Simon Patarin + * Phil Wood + * + * Monitor-mode support for mac80211 includes code taken from the iw + * command; the copyright notice for that code is + * + * Copyright (c) 2007, 2008 Johannes Berg + * Copyright (c) 2007 Andy Lutomirski + * Copyright (c) 2007 Mike Kershaw + * Copyright (c) 2008 Gábor Stefanik + * + * All rights reserved. * * Redistribution and use in source and binary forms, with or without - * modification, are permitted provided that: (1) source code distributions - * retain the above copyright notice and this paragraph in its entirety, (2) - * distributions including binary code include the above copyright notice and - * this paragraph in its entirety in the documentation or other materials - * provided with the distribution, and (3) all advertising materials mentioning - * features or use of this software display the following acknowledgement: - * ``This product includes software developed by the University of California, - * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of - * the University nor the names of its contributors may be used to endorse - * or promote products derived from this software without specific prior - * written permission. - * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED - * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF - * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. The name of the author may not be used to endorse or promote products + * derived from this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, + * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; + * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED + * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, + * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. */ + #ifndef lint -static const char rcsid[] = - "@(#) $Header: /tcpdump/master/libpcap/pcap-linux.c,v 1.15 1999-10-07 23:46:40 mcr Exp $ (LBL)"; +static const char rcsid[] _U_ = + "@(#) $Header: /tcpdump/master/libpcap/pcap-linux.c,v 1.164 2008-12-14 22:00:57 guy Exp $ (LBL)"; +#endif + +/* + * Known problems with 2.0[.x] kernels: + * + * - The loopback device gives every packet twice; on 2.2[.x] kernels, + * if we use PF_PACKET, we can filter out the transmitted version + * of the packet by using data in the "sockaddr_ll" returned by + * "recvfrom()", but, on 2.0[.x] kernels, we have to use + * PF_INET/SOCK_PACKET, which means "recvfrom()" supplies a + * "sockaddr_pkt" which doesn't give us enough information to let + * us do that. + * + * - We have to set the interface's IFF_PROMISC flag ourselves, if + * we're to run in promiscuous mode, which means we have to turn + * it off ourselves when we're done; the kernel doesn't keep track + * of how many sockets are listening promiscuously, which means + * it won't get turned off automatically when no sockets are + * listening promiscuously. We catch "pcap_close()" and, for + * interfaces we put into promiscuous mode, take them out of + * promiscuous mode - which isn't necessarily the right thing to + * do, if another socket also requested promiscuous mode between + * the time when we opened the socket and the time when we close + * the socket. + * + * - MSG_TRUNC isn't supported, so you can't specify that "recvfrom()" + * return the amount of data that you could have read, rather than + * the amount that was returned, so we can't just allocate a buffer + * whose size is the snapshot length and pass the snapshot length + * as the byte count, and also pass MSG_TRUNC, so that the return + * value tells us how long the packet was on the wire. + * + * This means that, if we want to get the actual size of the packet, + * so we can return it in the "len" field of the packet header, + * we have to read the entire packet, not just the part that fits + * within the snapshot length, and thus waste CPU time copying data + * from the kernel that our caller won't see. + * + * We have to get the actual size, and supply it in "len", because + * otherwise, the IP dissector in tcpdump, for example, will complain + * about "truncated-ip", as the packet will appear to have been + * shorter, on the wire, than the IP header said it should have been. + */ + + +#define _GNU_SOURCE + +#ifdef HAVE_CONFIG_H +#include "config.h" +#endif + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +/* + * Got Wireless Extensions? + */ +#ifdef HAVE_LINUX_WIRELESS_H +#include +#endif /* HAVE_LINUX_WIRELESS_H */ + +/* + * Got libnl? + */ +#ifdef HAVE_LIBNL +#include + +#include +#include +#include +#include +#include +#endif /* HAVE_LIBNL */ + +#include "pcap-int.h" +#include "pcap/sll.h" +#include "pcap/vlan.h" + +#ifdef HAVE_DAG_API +#include "pcap-dag.h" +#endif /* HAVE_DAG_API */ + +#ifdef HAVE_SEPTEL_API +#include "pcap-septel.h" +#endif /* HAVE_SEPTEL_API */ + +#ifdef PCAP_SUPPORT_USB +#include "pcap-usb-linux.h" +#endif + +#ifdef PCAP_SUPPORT_BT +#include "pcap-bt-linux.h" +#endif + +/* + * If PF_PACKET is defined, we can use {SOCK_RAW,SOCK_DGRAM}/PF_PACKET + * sockets rather than SOCK_PACKET sockets. + * + * To use them, we include rather than + * ; we do so because + * + * some Linux distributions (e.g., Slackware 4.0) have 2.2 or + * later kernels and libc5, and don't provide a + * file; + * + * not all versions of glibc2 have a file + * that defines stuff needed for some of the 2.4-or-later-kernel + * features, so if the system has a 2.4 or later kernel, we + * still can't use those features. + * + * We're already including a number of other headers, and + * this code is Linux-specific (no other OS has PF_PACKET sockets as + * a raw packet capture mechanism), so it's not as if you gain any + * useful portability by using + * + * XXX - should we just include even if PF_PACKET + * isn't defined? It only defines one data structure in 2.0.x, so + * it shouldn't cause any problems. + */ +#ifdef PF_PACKET +# include + + /* + * On at least some Linux distributions (for example, Red Hat 5.2), + * there's no file, but PF_PACKET is defined if + * you include , but doesn't define + * any of the PF_PACKET stuff such as "struct sockaddr_ll" or any of + * the PACKET_xxx stuff. + * + * So we check whether PACKET_HOST is defined, and assume that we have + * PF_PACKET sockets only if it is defined. + */ +# ifdef PACKET_HOST +# define HAVE_PF_PACKET_SOCKETS +# ifdef PACKET_AUXDATA +# define HAVE_PACKET_AUXDATA +# endif /* PACKET_AUXDATA */ +# endif /* PACKET_HOST */ + + + /* check for memory mapped access avaibility. We assume every needed + * struct is defined if the macro TPACKET_HDRLEN is defined, because it + * uses many ring related structs and macros */ +# ifdef TPACKET_HDRLEN +# define HAVE_PACKET_RING +# ifdef TPACKET2_HDRLEN +# define HAVE_TPACKET2 +# else +# define TPACKET_V1 0 +# endif /* TPACKET2_HDRLEN */ +# endif /* TPACKET_HDRLEN */ +#endif /* PF_PACKET */ + +#ifdef SO_ATTACH_FILTER +#include +#include +#endif + +#ifndef HAVE_SOCKLEN_T +typedef int socklen_t; +#endif + +#ifndef MSG_TRUNC +/* + * This is being compiled on a system that lacks MSG_TRUNC; define it + * with the value it has in the 2.2 and later kernels, so that, on + * those kernels, when we pass it in the flags argument to "recvfrom()" + * we're passing the right value and thus get the MSG_TRUNC behavior + * we want. (We don't get that behavior on 2.0[.x] kernels, because + * they didn't support MSG_TRUNC.) + */ +#define MSG_TRUNC 0x20 +#endif + +#ifndef SOL_PACKET +/* + * This is being compiled on a system that lacks SOL_PACKET; define it + * with the value it has in the 2.2 and later kernels, so that we can + * set promiscuous mode in the good modern way rather than the old + * 2.0-kernel crappy way. + */ +#define SOL_PACKET 263 +#endif + +#define MAX_LINKHEADER_SIZE 256 + +/* + * When capturing on all interfaces we use this as the buffer size. + * Should be bigger then all MTUs that occur in real life. + * 64kB should be enough for now. + */ +#define BIGGER_THAN_ALL_MTUS (64*1024) + +/* + * Prototypes for internal functions and methods. + */ +static void map_arphrd_to_dlt(pcap_t *, int, int); +#ifdef HAVE_PF_PACKET_SOCKETS +static short int map_packet_type_to_sll_type(short int); +#endif +static int pcap_activate_linux(pcap_t *); +static int activate_old(pcap_t *); +static int activate_new(pcap_t *); +static int activate_mmap(pcap_t *); +static int pcap_can_set_rfmon_linux(pcap_t *); +static int pcap_read_linux(pcap_t *, int, pcap_handler, u_char *); +static int pcap_read_packet(pcap_t *, pcap_handler, u_char *); +static int pcap_inject_linux(pcap_t *, const void *, size_t); +static int pcap_stats_linux(pcap_t *, struct pcap_stat *); +static int pcap_setfilter_linux(pcap_t *, struct bpf_program *); +static int pcap_setdirection_linux(pcap_t *, pcap_direction_t); +static void pcap_cleanup_linux(pcap_t *); + +union thdr { + struct tpacket_hdr *h1; + struct tpacket2_hdr *h2; + void *raw; +}; + +#ifdef HAVE_PACKET_RING +#define RING_GET_FRAME(h) (((union thdr **)h->buffer)[h->offset]) + +static void destroy_ring(pcap_t *handle); +static int create_ring(pcap_t *handle); +static int prepare_tpacket_socket(pcap_t *handle); +static void pcap_cleanup_linux_mmap(pcap_t *); +static int pcap_read_linux_mmap(pcap_t *, int, pcap_handler , u_char *); +static int pcap_setfilter_linux_mmap(pcap_t *, struct bpf_program *); +static int pcap_setnonblock_mmap(pcap_t *p, int nonblock, char *errbuf); +static int pcap_getnonblock_mmap(pcap_t *p, char *errbuf); +static void pcap_oneshot_mmap(u_char *user, const struct pcap_pkthdr *h, + const u_char *bytes); +#endif + +/* + * Wrap some ioctl calls + */ +#ifdef HAVE_PF_PACKET_SOCKETS +static int iface_get_id(int fd, const char *device, char *ebuf); +#endif +static int iface_get_mtu(int fd, const char *device, char *ebuf); +static int iface_get_arptype(int fd, const char *device, char *ebuf); +#ifdef HAVE_PF_PACKET_SOCKETS +static int iface_bind(int fd, int ifindex, char *ebuf); +#ifdef IW_MODE_MONITOR +static int has_wext(int sock_fd, const char *device, char *ebuf); +#endif /* IW_MODE_MONITOR */ +static int enter_rfmon_mode(pcap_t *handle, int sock_fd, + const char *device); +#endif /* HAVE_PF_PACKET_SOCKETS */ +static int iface_bind_old(int fd, const char *device, char *ebuf); + +#ifdef SO_ATTACH_FILTER +static int fix_program(pcap_t *handle, struct sock_fprog *fcode, + int is_mapped); +static int fix_offset(struct bpf_insn *p); +static int set_kernel_filter(pcap_t *handle, struct sock_fprog *fcode); +static int reset_kernel_filter(pcap_t *handle); + +static struct sock_filter total_insn + = BPF_STMT(BPF_RET | BPF_K, 0); +static struct sock_fprog total_fcode + = { 1, &total_insn }; +#endif + +pcap_t * +pcap_create(const char *device, char *ebuf) +{ + pcap_t *handle; + + /* + * A null device name is equivalent to the "any" device. + */ + if (device == NULL) + device = "any"; + +#ifdef HAVE_DAG_API + if (strstr(device, "dag")) { + return dag_create(device, ebuf); + } +#endif /* HAVE_DAG_API */ + +#ifdef HAVE_SEPTEL_API + if (strstr(device, "septel")) { + return septel_create(device, ebuf); + } +#endif /* HAVE_SEPTEL_API */ + +#ifdef PCAP_SUPPORT_BT + if (strstr(device, "bluetooth")) { + return bt_create(device, ebuf); + } +#endif + +#ifdef PCAP_SUPPORT_USB + if (strstr(device, "usbmon")) { + return usb_create(device, ebuf); + } +#endif + + handle = pcap_create_common(device, ebuf); + if (handle == NULL) + return NULL; + + handle->activate_op = pcap_activate_linux; + handle->can_set_rfmon_op = pcap_can_set_rfmon_linux; + return handle; +} + +#ifdef HAVE_LIBNL +/* + * + * If interface {if} is a mac80211 driver, the file + * /sys/class/net/{if}/phy80211 is a symlink to + * /sys/class/ieee80211/{phydev}, for some {phydev}. + * + * On Fedora 9, with a 2.6.26.3-29 kernel, my Zydas stick, at + * least, has a "wmaster0" device and a "wlan0" device; the + * latter is the one with the IP address. Both show up in + * "tcpdump -D" output. Capturing on the wmaster0 device + * captures with 802.11 headers. + * + * airmon-ng searches through /sys/class/net for devices named + * monN, starting with mon0; as soon as one *doesn't* exist, + * it chooses that as the monitor device name. If the "iw" + * command exists, it does "iw dev {if} interface add {monif} + * type monitor", where {monif} is the monitor device. It + * then (sigh) sleeps .1 second, and then configures the + * device up. Otherwise, if /sys/class/ieee80211/{phydev}/add_iface + * is a file, it writes {mondev}, without a newline, to that file, + * and again (sigh) sleeps .1 second, and then iwconfig's that + * device into monitor mode and configures it up. Otherwise, + * you can't do monitor mode. + * + * All these devices are "glued" together by having the + * /sys/class/net/{device}/phy80211 links pointing to the same + * place, so, given a wmaster, wlan, or mon device, you can + * find the other devices by looking for devices with + * the same phy80211 link. + * + * To turn monitor mode off, delete the monitor interface, + * either with "iw dev {monif} interface del" or by sending + * {monif}, with no NL, down /sys/class/ieee80211/{phydev}/remove_iface + * + * Note: if you try to create a monitor device named "monN", and + * there's already a "monN" device, it fails, as least with + * the netlink interface (which is what iw uses), with a return + * value of -ENFILE. (Return values are negative errnos.) We + * could probably use that to find an unused device. + * + * Yes, you can have multiple monitor devices for a given + * physical device. +*/ + +/* + * Is this a mac80211 device? If so, fill in the physical device path and + * return 1; if not, return 0. On an error, fill in handle->errbuf and + * return PCAP_ERROR. + */ +static int +get_mac80211_phydev(pcap_t *handle, const char *device, char *phydev_path, + size_t phydev_max_pathlen) +{ + char *pathstr; + ssize_t bytes_read; + + /* + * Generate the path string for the symlink to the physical device. + */ + if (asprintf(&pathstr, "/sys/class/net/%s/phy80211", device) == -1) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: Can't generate path name string for /sys/class/net device", + device); + return PCAP_ERROR; + } + bytes_read = readlink(pathstr, phydev_path, phydev_max_pathlen); + if (bytes_read == -1) { + if (errno == ENOENT || errno == EINVAL) { + /* + * Doesn't exist, or not a symlink; assume that + * means it's not a mac80211 device. + */ + free(pathstr); + return 0; + } + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: Can't readlink %s: %s", device, pathstr, + strerror(errno)); + free(pathstr); + return PCAP_ERROR; + } + free(pathstr); + phydev_path[bytes_read] = '\0'; + return 1; +} + +struct nl80211_state { + struct nl_handle *nl_handle; + struct nl_cache *nl_cache; + struct genl_family *nl80211; +}; + +static int +nl80211_init(pcap_t *handle, struct nl80211_state *state, const char *device) +{ + state->nl_handle = nl_handle_alloc(); + if (!state->nl_handle) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: failed to allocate netlink handle", device); + return PCAP_ERROR; + } + + if (genl_connect(state->nl_handle)) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: failed to connect to generic netlink", device); + goto out_handle_destroy; + } + + state->nl_cache = genl_ctrl_alloc_cache(state->nl_handle); + if (!state->nl_cache) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: failed to allocate generic netlink cache", device); + goto out_handle_destroy; + } + + state->nl80211 = genl_ctrl_search_by_name(state->nl_cache, "nl80211"); + if (!state->nl80211) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: nl80211 not found", device); + goto out_cache_free; + } + + return 0; + +out_cache_free: + nl_cache_free(state->nl_cache); +out_handle_destroy: + nl_handle_destroy(state->nl_handle); + return PCAP_ERROR; +} + +static void +nl80211_cleanup(struct nl80211_state *state) +{ + genl_family_put(state->nl80211); + nl_cache_free(state->nl_cache); + nl_handle_destroy(state->nl_handle); +} + +static int +add_mon_if(pcap_t *handle, int sock_fd, struct nl80211_state *state, + const char *device, const char *mondevice) +{ + int ifindex; + struct nl_msg *msg; + int err; + + ifindex = iface_get_id(sock_fd, device, handle->errbuf); + if (ifindex == -1) + return PCAP_ERROR; + + msg = nlmsg_alloc(); + if (!msg) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: failed to allocate netlink msg", device); + return PCAP_ERROR; + } + + genlmsg_put(msg, 0, 0, genl_family_get_id(state->nl80211), 0, + 0, NL80211_CMD_NEW_INTERFACE, 0); + NLA_PUT_U32(msg, NL80211_ATTR_IFINDEX, ifindex); + NLA_PUT_STRING(msg, NL80211_ATTR_IFNAME, mondevice); + NLA_PUT_U32(msg, NL80211_ATTR_IFTYPE, NL80211_IFTYPE_MONITOR); + + err = nl_send_auto_complete(state->nl_handle, msg); + if (err < 0) { + if (err == -ENFILE) { + /* + * Device not available; our caller should just + * keep trying. + */ + nlmsg_free(msg); + return 0; + } else { + /* + * Real failure, not just "that device is not + * available. + */ + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: nl_send_auto_complete failed adding %s interface: %s", + device, mondevice, strerror(-err)); + nlmsg_free(msg); + return PCAP_ERROR; + } + } + err = nl_wait_for_ack(state->nl_handle); + if (err < 0) { + if (err == -ENFILE) { + /* + * Device not available; our caller should just + * keep trying. + */ + nlmsg_free(msg); + return 0; + } else { + /* + * Real failure, not just "that device is not + * available. + */ + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: nl_wait_for_ack failed adding %s interface: %s", + device, mondevice, strerror(-err)); + nlmsg_free(msg); + return PCAP_ERROR; + } + } + + /* + * Success. + */ + nlmsg_free(msg); + return 1; + +nla_put_failure: + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: nl_put failed adding %s interface", + device, mondevice); + nlmsg_free(msg); + return PCAP_ERROR; +} + +static int +del_mon_if(pcap_t *handle, int sock_fd, struct nl80211_state *state, + const char *device, const char *mondevice) +{ + int ifindex; + struct nl_msg *msg; + int err; + + ifindex = iface_get_id(sock_fd, mondevice, handle->errbuf); + if (ifindex == -1) + return PCAP_ERROR; + + msg = nlmsg_alloc(); + if (!msg) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: failed to allocate netlink msg", device); + return PCAP_ERROR; + } + + genlmsg_put(msg, 0, 0, genl_family_get_id(state->nl80211), 0, + 0, NL80211_CMD_DEL_INTERFACE, 0); + NLA_PUT_U32(msg, NL80211_ATTR_IFINDEX, ifindex); + + err = nl_send_auto_complete(state->nl_handle, msg); + if (err < 0) { + if (err == -ENFILE) { + /* + * Device not available; our caller should just + * keep trying. + */ + nlmsg_free(msg); + return 0; + } else { + /* + * Real failure, not just "that device is not + * available. + */ + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: nl_send_auto_complete failed deleting %s interface: %s", + device, mondevice, strerror(-err)); + nlmsg_free(msg); + return PCAP_ERROR; + } + } + err = nl_wait_for_ack(state->nl_handle); + if (err < 0) { + if (err == -ENFILE) { + /* + * Device not available; our caller should just + * keep trying. + */ + nlmsg_free(msg); + return 0; + } else { + /* + * Real failure, not just "that device is not + * available. + */ + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: nl_wait_for_ack failed adding %s interface: %s", + device, mondevice, strerror(-err)); + nlmsg_free(msg); + return PCAP_ERROR; + } + } + + /* + * Success. + */ + nlmsg_free(msg); + return 1; + +nla_put_failure: + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: nl_put failed deleting %s interface", + device, mondevice); + nlmsg_free(msg); + return PCAP_ERROR; +} + +static int +enter_rfmon_mode_mac80211(pcap_t *handle, int sock_fd, const char *device) +{ + int ret; + char phydev_path[PATH_MAX+1]; + struct nl80211_state nlstate; + struct ifreq ifr; + u_int n; + + /* + * Is this a mac80211 device? + */ + ret = get_mac80211_phydev(handle, device, phydev_path, PATH_MAX); + if (ret < 0) + return ret; /* error */ + if (ret == 0) + return 0; /* no error, but not mac80211 device */ + + /* + * XXX - is this already a monN device? + * If so, we're done. + * Is that determined by old Wireless Extensions ioctls? + */ + + /* + * OK, it's apparently a mac80211 device. + * Try to find an unused monN device for it. + */ + ret = nl80211_init(handle, &nlstate, device); + if (ret != 0) + return ret; + for (n = 0; n < UINT_MAX; n++) { + /* + * Try mon{n}. + */ + char mondevice[3+10+1]; /* mon{UINT_MAX}\0 */ + + snprintf(mondevice, sizeof mondevice, "mon%u", n); + ret = add_mon_if(handle, sock_fd, &nlstate, device, mondevice); + if (ret == 1) { + handle->md.mondevice = strdup(mondevice); + goto added; + } + if (ret < 0) { + /* + * Hard failure. Just return ret; handle->errbuf + * has already been set. + */ + nl80211_cleanup(&nlstate); + return ret; + } + } + + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: No free monN interfaces", device); + nl80211_cleanup(&nlstate); + return PCAP_ERROR; + +added: + +#if 0 + /* + * Sleep for .1 seconds. + */ + delay.tv_sec = 0; + delay.tv_nsec = 500000000; + nanosleep(&delay, NULL); +#endif + + /* + * Now configure the monitor interface up. + */ + memset(&ifr, 0, sizeof(ifr)); + strncpy(ifr.ifr_name, handle->md.mondevice, sizeof(ifr.ifr_name)); + if (ioctl(sock_fd, SIOCGIFFLAGS, &ifr) == -1) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: Can't get flags for %s: %s", device, + handle->md.mondevice, strerror(errno)); + del_mon_if(handle, sock_fd, &nlstate, device, + handle->md.mondevice); + nl80211_cleanup(&nlstate); + return PCAP_ERROR; + } + ifr.ifr_flags |= IFF_UP|IFF_RUNNING; + if (ioctl(sock_fd, SIOCSIFFLAGS, &ifr) == -1) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: Can't set flags for %s: %s", device, + handle->md.mondevice, strerror(errno)); + del_mon_if(handle, sock_fd, &nlstate, device, + handle->md.mondevice); + nl80211_cleanup(&nlstate); + return PCAP_ERROR; + } + + /* + * Success. Clean up the libnl state. + */ + nl80211_cleanup(&nlstate); + + /* + * Note that we have to delete the monitor device when we close + * the handle. + */ + handle->md.must_do_on_close |= MUST_DELETE_MONIF; + + /* + * Add this to the list of pcaps to close when we exit. + */ + pcap_add_to_pcaps_to_close(handle); + + return 1; +} +#endif /* HAVE_LIBNL */ + +static int +pcap_can_set_rfmon_linux(pcap_t *handle) +{ +#ifdef HAVE_LIBNL + char phydev_path[PATH_MAX+1]; + int ret; +#endif +#ifdef IW_MODE_MONITOR + int sock_fd; + struct iwreq ireq; +#endif + + if (strcmp(handle->opt.source, "any") == 0) { + /* + * Monitor mode makes no sense on the "any" device. + */ + return 0; + } + +#ifdef HAVE_LIBNL + /* + * Bleah. There doesn't seem to be a way to ask a mac80211 + * device, through libnl, whether it supports monitor mode; + * we'll just check whether the device appears to be a + * mac80211 device and, if so, assume the device supports + * monitor mode. + * + * wmaster devices don't appear to support the Wireless + * Extensions, but we can create a mon device for a + * wmaster device, so we don't bother checking whether + * a mac80211 device supports the Wireless Extensions. + */ + ret = get_mac80211_phydev(handle, handle->opt.source, phydev_path, + PATH_MAX); + if (ret < 0) + return ret; /* error */ + if (ret == 1) + return 1; /* mac80211 device */ +#endif + +#ifdef IW_MODE_MONITOR + /* + * Bleah. There doesn't appear to be an ioctl to use to ask + * whether a device supports monitor mode; we'll just do + * SIOCGIWMODE and, if it succeeds, assume the device supports + * monitor mode. + * + * Open a socket on which to attempt to get the mode. + * (We assume that if we have Wireless Extensions support + * we also have PF_PACKET support.) + */ + sock_fd = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL)); + if (sock_fd == -1) { + (void)snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "socket: %s", pcap_strerror(errno)); + return PCAP_ERROR; + } + + /* + * Attempt to get the current mode. + */ + strncpy(ireq.ifr_ifrn.ifrn_name, handle->opt.source, + sizeof ireq.ifr_ifrn.ifrn_name); + ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; + if (ioctl(sock_fd, SIOCGIWMODE, &ireq) != -1) { + /* + * Well, we got the mode; assume we can set it. + */ + close(sock_fd); + return 1; + } + if (errno == ENODEV) { + /* The device doesn't even exist. */ + close(sock_fd); + return PCAP_ERROR_NO_SUCH_DEVICE; + } + close(sock_fd); +#endif + return 0; +} + +/* + * With older kernels promiscuous mode is kind of interesting because we + * have to reset the interface before exiting. The problem can't really + * be solved without some daemon taking care of managing usage counts. + * If we put the interface into promiscuous mode, we set a flag indicating + * that we must take it out of that mode when the interface is closed, + * and, when closing the interface, if that flag is set we take it out + * of promiscuous mode. + * + * Even with newer kernels, we have the same issue with rfmon mode. + */ + +static void pcap_cleanup_linux( pcap_t *handle ) +{ + struct ifreq ifr; +#ifdef HAVE_LIBNL + struct nl80211_state nlstate; + int ret; +#endif /* HAVE_LIBNL */ +#ifdef IW_MODE_MONITOR + struct iwreq ireq; +#endif /* IW_MODE_MONITOR */ + + if (handle->md.must_do_on_close != 0) { + /* + * There's something we have to do when closing this + * pcap_t. + */ + if (handle->md.must_do_on_close & MUST_CLEAR_PROMISC) { + /* + * We put the interface into promiscuous mode; + * take it out of promiscuous mode. + * + * XXX - if somebody else wants it in promiscuous + * mode, this code cannot know that, so it'll take + * it out of promiscuous mode. That's not fixable + * in 2.0[.x] kernels. + */ + memset(&ifr, 0, sizeof(ifr)); + strncpy(ifr.ifr_name, handle->md.device, + sizeof(ifr.ifr_name)); + if (ioctl(handle->fd, SIOCGIFFLAGS, &ifr) == -1) { + fprintf(stderr, + "Can't restore interface flags (SIOCGIFFLAGS failed: %s).\n" + "Please adjust manually.\n" + "Hint: This can't happen with Linux >= 2.2.0.\n", + strerror(errno)); + } else { + if (ifr.ifr_flags & IFF_PROMISC) { + /* + * Promiscuous mode is currently on; + * turn it off. + */ + ifr.ifr_flags &= ~IFF_PROMISC; + if (ioctl(handle->fd, SIOCSIFFLAGS, + &ifr) == -1) { + fprintf(stderr, + "Can't restore interface flags (SIOCSIFFLAGS failed: %s).\n" + "Please adjust manually.\n" + "Hint: This can't happen with Linux >= 2.2.0.\n", + strerror(errno)); + } + } + } + } + +#ifdef HAVE_LIBNL + if (handle->md.must_do_on_close & MUST_DELETE_MONIF) { + ret = nl80211_init(handle, &nlstate, handle->md.device); + if (ret >= 0) { + ret = del_mon_if(handle, handle->fd, &nlstate, + handle->md.device, handle->md.mondevice); + nl80211_cleanup(&nlstate); + } + if (ret < 0) { + fprintf(stderr, + "Can't delete monitor interface %s (%s).\n" + "Please delete manually.\n", + handle->md.mondevice, handle->errbuf); + } + } +#endif /* HAVE_LIBNL */ + +#ifdef IW_MODE_MONITOR + if (handle->md.must_do_on_close & MUST_CLEAR_RFMON) { + /* + * We put the interface into rfmon mode; + * take it out of rfmon mode. + * + * XXX - if somebody else wants it in rfmon + * mode, this code cannot know that, so it'll take + * it out of rfmon mode. + */ + strncpy(ireq.ifr_ifrn.ifrn_name, handle->md.device, + sizeof ireq.ifr_ifrn.ifrn_name); + ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] + = 0; + ireq.u.mode = handle->md.oldmode; + if (ioctl(handle->fd, SIOCSIWMODE, &ireq) == -1) { + /* + * Scientist, you've failed. + */ + fprintf(stderr, + "Can't restore interface wireless mode (SIOCSIWMODE failed: %s).\n" + "Please adjust manually.\n", + strerror(errno)); + } + } +#endif /* IW_MODE_MONITOR */ + + /* + * Take this pcap out of the list of pcaps for which we + * have to take the interface out of some mode. + */ + pcap_remove_from_pcaps_to_close(handle); + } + + if (handle->md.mondevice != NULL) { + free(handle->md.mondevice); + handle->md.mondevice = NULL; + } + if (handle->md.device != NULL) { + free(handle->md.device); + handle->md.device = NULL; + } + pcap_cleanup_live_common(handle); +} + +/* + * Get a handle for a live capture from the given device. You can + * pass NULL as device to get all packages (without link level + * information of course). If you pass 1 as promisc the interface + * will be set to promiscous mode (XXX: I think this usage should + * be deprecated and functions be added to select that later allow + * modification of that values -- Torsten). + */ +static int +pcap_activate_linux(pcap_t *handle) +{ + const char *device; + int status = 0; + + device = handle->opt.source; + + handle->inject_op = pcap_inject_linux; + handle->setfilter_op = pcap_setfilter_linux; + handle->setdirection_op = pcap_setdirection_linux; + handle->set_datalink_op = NULL; /* can't change data link type */ + handle->getnonblock_op = pcap_getnonblock_fd; + handle->setnonblock_op = pcap_setnonblock_fd; + handle->cleanup_op = pcap_cleanup_linux; + handle->read_op = pcap_read_linux; + handle->stats_op = pcap_stats_linux; + + /* + * The "any" device is a special device which causes us not + * to bind to a particular device and thus to look at all + * devices. + */ + if (strcmp(device, "any") == 0) { + if (handle->opt.promisc) { + handle->opt.promisc = 0; + /* Just a warning. */ + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "Promiscuous mode not supported on the \"any\" device"); + status = PCAP_WARNING_PROMISC_NOTSUP; + } + } + + handle->md.device = strdup(device); + if (handle->md.device == NULL) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "strdup: %s", + pcap_strerror(errno) ); + return PCAP_ERROR; + } + + /* + * Current Linux kernels use the protocol family PF_PACKET to + * allow direct access to all packets on the network while + * older kernels had a special socket type SOCK_PACKET to + * implement this feature. + * While this old implementation is kind of obsolete we need + * to be compatible with older kernels for a while so we are + * trying both methods with the newer method preferred. + */ + + if ((status = activate_new(handle)) == 1) { + /* + * Success. + * Try to use memory-mapped access. + */ + switch (activate_mmap(handle)) { + + case 1: + /* we succeeded; nothing more to do */ + return 0; + + case 0: + /* + * Kernel doesn't support it - just continue + * with non-memory-mapped access. + */ + status = 0; + break; + + case -1: + /* + * We failed to set up to use it, or kernel + * supports it, but we failed to enable it; + * return an error. handle->errbuf contains + * an error message. + */ + status = PCAP_ERROR; + goto fail; + } + } + else if (status == 0) { + /* Non-fatal error; try old way */ + if ((status = activate_old(handle)) != 1) { + /* + * Both methods to open the packet socket failed. + * Tidy up and report our failure (handle->errbuf + * is expected to be set by the functions above). + */ + goto fail; + } + } else { + /* + * Fatal error with the new way; just fail. + * status has the error return; if it's PCAP_ERROR, + * handle->errbuf has been set appropriately. + */ + goto fail; + } + + /* + * We set up the socket, but not with memory-mapped access. + */ + if (handle->opt.buffer_size != 0) { + /* + * Set the socket buffer size to the specified value. + */ + if (setsockopt(handle->fd, SOL_SOCKET, SO_RCVBUF, + &handle->opt.buffer_size, + sizeof(handle->opt.buffer_size)) == -1) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "SO_RCVBUF: %s", pcap_strerror(errno)); + status = PCAP_ERROR; + goto fail; + } + } + + /* Allocate the buffer */ + + handle->buffer = malloc(handle->bufsize + handle->offset); + if (!handle->buffer) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "malloc: %s", pcap_strerror(errno)); + status = PCAP_ERROR; + goto fail; + } + + /* + * "handle->fd" is a socket, so "select()" and "poll()" + * should work on it. + */ + handle->selectable_fd = handle->fd; + + return status; + +fail: + pcap_cleanup_linux(handle); + return status; +} + +/* + * Read at most max_packets from the capture stream and call the callback + * for each of them. Returns the number of packets handled or -1 if an + * error occured. + */ +static int +pcap_read_linux(pcap_t *handle, int max_packets, pcap_handler callback, u_char *user) +{ + /* + * Currently, on Linux only one packet is delivered per read, + * so we don't loop. + */ + return pcap_read_packet(handle, callback, user); +} + +/* + * Read a packet from the socket calling the handler provided by + * the user. Returns the number of packets received or -1 if an + * error occured. + */ +static int +pcap_read_packet(pcap_t *handle, pcap_handler callback, u_char *userdata) +{ + u_char *bp; + int offset; +#ifdef HAVE_PF_PACKET_SOCKETS + struct sockaddr_ll from; + struct sll_header *hdrp; +#else + struct sockaddr from; +#endif +#if defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) + struct iovec iov; + struct msghdr msg; + struct cmsghdr *cmsg; + union { + struct cmsghdr cmsg; + char buf[CMSG_SPACE(sizeof(struct tpacket_auxdata))]; + } cmsg_buf; +#else /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) */ + socklen_t fromlen; +#endif /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) */ + int packet_len, caplen; + struct pcap_pkthdr pcap_header; + +#ifdef HAVE_PF_PACKET_SOCKETS + /* + * If this is a cooked device, leave extra room for a + * fake packet header. + */ + if (handle->md.cooked) + offset = SLL_HDR_LEN; + else + offset = 0; +#else + /* + * This system doesn't have PF_PACKET sockets, so it doesn't + * support cooked devices. + */ + offset = 0; +#endif + + /* + * Receive a single packet from the kernel. + * We ignore EINTR, as that might just be due to a signal + * being delivered - if the signal should interrupt the + * loop, the signal handler should call pcap_breakloop() + * to set handle->break_loop (we ignore it on other + * platforms as well). + * We also ignore ENETDOWN, so that we can continue to + * capture traffic if the interface goes down and comes + * back up again; comments in the kernel indicate that + * we'll just block waiting for packets if we try to + * receive from a socket that delivered ENETDOWN, and, + * if we're using a memory-mapped buffer, we won't even + * get notified of "network down" events. + */ + bp = handle->buffer + handle->offset; + +#if defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) + msg.msg_name = &from; + msg.msg_namelen = sizeof(from); + msg.msg_iov = &iov; + msg.msg_iovlen = 1; + msg.msg_control = &cmsg_buf; + msg.msg_controllen = sizeof(cmsg_buf); + msg.msg_flags = 0; + + iov.iov_len = handle->bufsize - offset; + iov.iov_base = bp + offset; +#endif /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) */ + + do { + /* + * Has "pcap_breakloop()" been called? + */ + if (handle->break_loop) { + /* + * Yes - clear the flag that indicates that it + * has, and return -2 as an indication that we + * were told to break out of the loop. + */ + handle->break_loop = 0; + return -2; + } + +#if defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) + packet_len = recvmsg(handle->fd, &msg, MSG_TRUNC); +#else /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) */ + fromlen = sizeof(from); + packet_len = recvfrom( + handle->fd, bp + offset, + handle->bufsize - offset, MSG_TRUNC, + (struct sockaddr *) &from, &fromlen); +#endif /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) */ + } while (packet_len == -1 && (errno == EINTR || errno == ENETDOWN)); + + /* Check if an error occured */ + + if (packet_len == -1) { + if (errno == EAGAIN) + return 0; /* no packet there */ + else { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "recvfrom: %s", pcap_strerror(errno)); + return -1; + } + } + +#ifdef HAVE_PF_PACKET_SOCKETS + if (!handle->md.sock_packet) { + /* + * Unfortunately, there is a window between socket() and + * bind() where the kernel may queue packets from any + * interface. If we're bound to a particular interface, + * discard packets not from that interface. + * + * (If socket filters are supported, we could do the + * same thing we do when changing the filter; however, + * that won't handle packet sockets without socket + * filter support, and it's a bit more complicated. + * It would save some instructions per packet, however.) + */ + if (handle->md.ifindex != -1 && + from.sll_ifindex != handle->md.ifindex) + return 0; + + /* + * Do checks based on packet direction. + * We can only do this if we're using PF_PACKET; the + * address returned for SOCK_PACKET is a "sockaddr_pkt" + * which lacks the relevant packet type information. + */ + if (from.sll_pkttype == PACKET_OUTGOING) { + /* + * Outgoing packet. + * If this is from the loopback device, reject it; + * we'll see the packet as an incoming packet as well, + * and we don't want to see it twice. + */ + if (from.sll_ifindex == handle->md.lo_ifindex) + return 0; + + /* + * If the user only wants incoming packets, reject it. + */ + if (handle->direction == PCAP_D_IN) + return 0; + } else { + /* + * Incoming packet. + * If the user only wants outgoing packets, reject it. + */ + if (handle->direction == PCAP_D_OUT) + return 0; + } + } +#endif + +#ifdef HAVE_PF_PACKET_SOCKETS + /* + * If this is a cooked device, fill in the fake packet header. + */ + if (handle->md.cooked) { + /* + * Add the length of the fake header to the length + * of packet data we read. + */ + packet_len += SLL_HDR_LEN; + + hdrp = (struct sll_header *)bp; + hdrp->sll_pkttype = map_packet_type_to_sll_type(from.sll_pkttype); + hdrp->sll_hatype = htons(from.sll_hatype); + hdrp->sll_halen = htons(from.sll_halen); + memcpy(hdrp->sll_addr, from.sll_addr, + (from.sll_halen > SLL_ADDRLEN) ? + SLL_ADDRLEN : + from.sll_halen); + hdrp->sll_protocol = from.sll_protocol; + } + +#if defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) + for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) { + struct tpacket_auxdata *aux; + unsigned int len; + struct vlan_tag *tag; + + if (cmsg->cmsg_len < CMSG_LEN(sizeof(struct tpacket_auxdata)) || + cmsg->cmsg_level != SOL_PACKET || + cmsg->cmsg_type != PACKET_AUXDATA) + continue; + + aux = (struct tpacket_auxdata *)CMSG_DATA(cmsg); + if (aux->tp_vlan_tci == 0) + continue; + + len = packet_len > iov.iov_len ? iov.iov_len : packet_len; + if (len < 2 * ETH_ALEN) + break; + + bp -= VLAN_TAG_LEN; + memmove(bp, bp + VLAN_TAG_LEN, 2 * ETH_ALEN); + + tag = (struct vlan_tag *)(bp + 2 * ETH_ALEN); + tag->vlan_tpid = htons(ETH_P_8021Q); + tag->vlan_tci = htons(aux->tp_vlan_tci); + + packet_len += VLAN_TAG_LEN; + } +#endif /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) */ +#endif /* HAVE_PF_PACKET_SOCKETS */ + + /* + * XXX: According to the kernel source we should get the real + * packet len if calling recvfrom with MSG_TRUNC set. It does + * not seem to work here :(, but it is supported by this code + * anyway. + * To be honest the code RELIES on that feature so this is really + * broken with 2.2.x kernels. + * I spend a day to figure out what's going on and I found out + * that the following is happening: + * + * The packet comes from a random interface and the packet_rcv + * hook is called with a clone of the packet. That code inserts + * the packet into the receive queue of the packet socket. + * If a filter is attached to that socket that filter is run + * first - and there lies the problem. The default filter always + * cuts the packet at the snaplen: + * + * # tcpdump -d + * (000) ret #68 + * + * So the packet filter cuts down the packet. The recvfrom call + * says "hey, it's only 68 bytes, it fits into the buffer" with + * the result that we don't get the real packet length. This + * is valid at least until kernel 2.2.17pre6. + * + * We currently handle this by making a copy of the filter + * program, fixing all "ret" instructions with non-zero + * operands to have an operand of 65535 so that the filter + * doesn't truncate the packet, and supplying that modified + * filter to the kernel. + */ + + caplen = packet_len; + if (caplen > handle->snapshot) + caplen = handle->snapshot; + + /* Run the packet filter if not using kernel filter */ + if (!handle->md.use_bpf && handle->fcode.bf_insns) { + if (bpf_filter(handle->fcode.bf_insns, bp, + packet_len, caplen) == 0) + { + /* rejected by filter */ + return 0; + } + } + + /* Fill in our own header data */ + + if (ioctl(handle->fd, SIOCGSTAMP, &pcap_header.ts) == -1) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "SIOCGSTAMP: %s", pcap_strerror(errno)); + return -1; + } + pcap_header.caplen = caplen; + pcap_header.len = packet_len; + + /* + * Count the packet. + * + * Arguably, we should count them before we check the filter, + * as on many other platforms "ps_recv" counts packets + * handed to the filter rather than packets that passed + * the filter, but if filtering is done in the kernel, we + * can't get a count of packets that passed the filter, + * and that would mean the meaning of "ps_recv" wouldn't + * be the same on all Linux systems. + * + * XXX - it's not the same on all systems in any case; + * ideally, we should have a "get the statistics" call + * that supplies more counts and indicates which of them + * it supplies, so that we supply a count of packets + * handed to the filter only on platforms where that + * information is available. + * + * We count them here even if we can get the packet count + * from the kernel, as we can only determine at run time + * whether we'll be able to get it from the kernel (if + * HAVE_TPACKET_STATS isn't defined, we can't get it from + * the kernel, but if it is defined, the library might + * have been built with a 2.4 or later kernel, but we + * might be running on a 2.2[.x] kernel without Alexey + * Kuznetzov's turbopacket patches, and thus the kernel + * might not be able to supply those statistics). We + * could, I guess, try, when opening the socket, to get + * the statistics, and if we can not increment the count + * here, but it's not clear that always incrementing + * the count is more expensive than always testing a flag + * in memory. + * + * We keep the count in "md.packets_read", and use that for + * "ps_recv" if we can't get the statistics from the kernel. + * We do that because, if we *can* get the statistics from + * the kernel, we use "md.stat.ps_recv" and "md.stat.ps_drop" + * as running counts, as reading the statistics from the + * kernel resets the kernel statistics, and if we directly + * increment "md.stat.ps_recv" here, that means it will + * count packets *twice* on systems where we can get kernel + * statistics - once here, and once in pcap_stats_linux(). + */ + handle->md.packets_read++; + + /* Call the user supplied callback function */ + callback(userdata, &pcap_header, bp); + + return 1; +} + +static int +pcap_inject_linux(pcap_t *handle, const void *buf, size_t size) +{ + int ret; + +#ifdef HAVE_PF_PACKET_SOCKETS + if (!handle->md.sock_packet) { + /* PF_PACKET socket */ + if (handle->md.ifindex == -1) { + /* + * We don't support sending on the "any" device. + */ + strlcpy(handle->errbuf, + "Sending packets isn't supported on the \"any\" device", + PCAP_ERRBUF_SIZE); + return (-1); + } + + if (handle->md.cooked) { + /* + * We don't support sending on the "any" device. + * + * XXX - how do you send on a bound cooked-mode + * socket? + * Is a "sendto()" required there? + */ + strlcpy(handle->errbuf, + "Sending packets isn't supported in cooked mode", + PCAP_ERRBUF_SIZE); + return (-1); + } + } +#endif + + ret = send(handle->fd, buf, size, 0); + if (ret == -1) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "send: %s", + pcap_strerror(errno)); + return (-1); + } + return (ret); +} + +/* + * Get the statistics for the given packet capture handle. + * Reports the number of dropped packets iff the kernel supports + * the PACKET_STATISTICS "getsockopt()" argument (2.4 and later + * kernels, and 2.2[.x] kernels with Alexey Kuznetzov's turbopacket + * patches); otherwise, that information isn't available, and we lie + * and report 0 as the count of dropped packets. + */ +static int +pcap_stats_linux(pcap_t *handle, struct pcap_stat *stats) +{ +#ifdef HAVE_TPACKET_STATS + struct tpacket_stats kstats; + socklen_t len = sizeof (struct tpacket_stats); +#endif + +#ifdef HAVE_TPACKET_STATS + /* + * Try to get the packet counts from the kernel. + */ + if (getsockopt(handle->fd, SOL_PACKET, PACKET_STATISTICS, + &kstats, &len) > -1) { + /* + * On systems where the PACKET_STATISTICS "getsockopt()" + * argument is supported on PF_PACKET sockets: + * + * "ps_recv" counts only packets that *passed* the + * filter, not packets that didn't pass the filter. + * This includes packets later dropped because we + * ran out of buffer space. + * + * "ps_drop" counts packets dropped because we ran + * out of buffer space. It doesn't count packets + * dropped by the interface driver. It counts only + * packets that passed the filter. + * + * Both statistics include packets not yet read from + * the kernel by libpcap, and thus not yet seen by + * the application. + * + * In "linux/net/packet/af_packet.c", at least in the + * 2.4.9 kernel, "tp_packets" is incremented for every + * packet that passes the packet filter *and* is + * successfully queued on the socket; "tp_drops" is + * incremented for every packet dropped because there's + * not enough free space in the socket buffer. + * + * When the statistics are returned for a PACKET_STATISTICS + * "getsockopt()" call, "tp_drops" is added to "tp_packets", + * so that "tp_packets" counts all packets handed to + * the PF_PACKET socket, including packets dropped because + * there wasn't room on the socket buffer - but not + * including packets that didn't pass the filter. + * + * In the BSD BPF, the count of received packets is + * incremented for every packet handed to BPF, regardless + * of whether it passed the filter. + * + * We can't make "pcap_stats()" work the same on both + * platforms, but the best approximation is to return + * "tp_packets" as the count of packets and "tp_drops" + * as the count of drops. + * + * Keep a running total because each call to + * getsockopt(handle->fd, SOL_PACKET, PACKET_STATISTICS, .... + * resets the counters to zero. + */ + handle->md.stat.ps_recv += kstats.tp_packets; + handle->md.stat.ps_drop += kstats.tp_drops; + *stats = handle->md.stat; + return 0; + } + else + { + /* + * If the error was EOPNOTSUPP, fall through, so that + * if you build the library on a system with + * "struct tpacket_stats" and run it on a system + * that doesn't, it works as it does if the library + * is built on a system without "struct tpacket_stats". + */ + if (errno != EOPNOTSUPP) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "pcap_stats: %s", pcap_strerror(errno)); + return -1; + } + } +#endif + /* + * On systems where the PACKET_STATISTICS "getsockopt()" argument + * is not supported on PF_PACKET sockets: + * + * "ps_recv" counts only packets that *passed* the filter, + * not packets that didn't pass the filter. It does not + * count packets dropped because we ran out of buffer + * space. + * + * "ps_drop" is not supported. + * + * "ps_recv" doesn't include packets not yet read from + * the kernel by libpcap. + * + * We maintain the count of packets processed by libpcap in + * "md.packets_read", for reasons described in the comment + * at the end of pcap_read_packet(). We have no idea how many + * packets were dropped. + */ + stats->ps_recv = handle->md.packets_read; + stats->ps_drop = 0; + return 0; +} + +/* + * Description string for the "any" device. + */ +static const char any_descr[] = "Pseudo-device that captures on all interfaces"; + +int +pcap_platform_finddevs(pcap_if_t **alldevsp, char *errbuf) +{ + if (pcap_add_if(alldevsp, "any", 0, any_descr, errbuf) < 0) + return (-1); + +#ifdef HAVE_DAG_API + if (dag_platform_finddevs(alldevsp, errbuf) < 0) + return (-1); +#endif /* HAVE_DAG_API */ + +#ifdef HAVE_SEPTEL_API + if (septel_platform_finddevs(alldevsp, errbuf) < 0) + return (-1); +#endif /* HAVE_SEPTEL_API */ + +#ifdef PCAP_SUPPORT_BT + if (bt_platform_finddevs(alldevsp, errbuf) < 0) + return (-1); +#endif + +#ifdef PCAP_SUPPORT_USB + if (usb_platform_finddevs(alldevsp, errbuf) < 0) + return (-1); +#endif + + return (0); +} + +/* + * Attach the given BPF code to the packet capture device. + */ +static int +pcap_setfilter_linux_common(pcap_t *handle, struct bpf_program *filter, + int is_mmapped) +{ +#ifdef SO_ATTACH_FILTER + struct sock_fprog fcode; + int can_filter_in_kernel; + int err = 0; +#endif + + if (!handle) + return -1; + if (!filter) { + strncpy(handle->errbuf, "setfilter: No filter specified", + PCAP_ERRBUF_SIZE); + return -1; + } + + /* Make our private copy of the filter */ + + if (install_bpf_program(handle, filter) < 0) + /* install_bpf_program() filled in errbuf */ + return -1; + + /* + * Run user level packet filter by default. Will be overriden if + * installing a kernel filter succeeds. + */ + handle->md.use_bpf = 0; + + /* Install kernel level filter if possible */ + +#ifdef SO_ATTACH_FILTER +#ifdef USHRT_MAX + if (handle->fcode.bf_len > USHRT_MAX) { + /* + * fcode.len is an unsigned short for current kernel. + * I have yet to see BPF-Code with that much + * instructions but still it is possible. So for the + * sake of correctness I added this check. + */ + fprintf(stderr, "Warning: Filter too complex for kernel\n"); + fcode.len = 0; + fcode.filter = NULL; + can_filter_in_kernel = 0; + } else +#endif /* USHRT_MAX */ + { + /* + * Oh joy, the Linux kernel uses struct sock_fprog instead + * of struct bpf_program and of course the length field is + * of different size. Pointed out by Sebastian + * + * Oh, and we also need to fix it up so that all "ret" + * instructions with non-zero operands have 65535 as the + * operand if we're not capturing in memory-mapped modee, + * and so that, if we're in cooked mode, all memory-reference + * instructions use special magic offsets in references to + * the link-layer header and assume that the link-layer + * payload begins at 0; "fix_program()" will do that. + */ + switch (fix_program(handle, &fcode, is_mmapped)) { + + case -1: + default: + /* + * Fatal error; just quit. + * (The "default" case shouldn't happen; we + * return -1 for that reason.) + */ + return -1; + + case 0: + /* + * The program performed checks that we can't make + * work in the kernel. + */ + can_filter_in_kernel = 0; + break; + + case 1: + /* + * We have a filter that'll work in the kernel. + */ + can_filter_in_kernel = 1; + break; + } + } + + if (can_filter_in_kernel) { + if ((err = set_kernel_filter(handle, &fcode)) == 0) + { + /* Installation succeded - using kernel filter. */ + handle->md.use_bpf = 1; + } + else if (err == -1) /* Non-fatal error */ + { + /* + * Print a warning if we weren't able to install + * the filter for a reason other than "this kernel + * isn't configured to support socket filters. + */ + if (errno != ENOPROTOOPT && errno != EOPNOTSUPP) { + fprintf(stderr, + "Warning: Kernel filter failed: %s\n", + pcap_strerror(errno)); + } + } + } + + /* + * If we're not using the kernel filter, get rid of any kernel + * filter that might've been there before, e.g. because the + * previous filter could work in the kernel, or because some other + * code attached a filter to the socket by some means other than + * calling "pcap_setfilter()". Otherwise, the kernel filter may + * filter out packets that would pass the new userland filter. + */ + if (!handle->md.use_bpf) + reset_kernel_filter(handle); + + /* + * Free up the copy of the filter that was made by "fix_program()". + */ + if (fcode.filter != NULL) + free(fcode.filter); + + if (err == -2) + /* Fatal error */ + return -1; +#endif /* SO_ATTACH_FILTER */ + + return 0; +} + +static int +pcap_setfilter_linux(pcap_t *handle, struct bpf_program *filter) +{ + return pcap_setfilter_linux_common(handle, filter, 0); +} + + +/* + * Set direction flag: Which packets do we accept on a forwarding + * single device? IN, OUT or both? + */ +static int +pcap_setdirection_linux(pcap_t *handle, pcap_direction_t d) +{ +#ifdef HAVE_PF_PACKET_SOCKETS + if (!handle->md.sock_packet) { + handle->direction = d; + return 0; + } +#endif + /* + * We're not using PF_PACKET sockets, so we can't determine + * the direction of the packet. + */ + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "Setting direction is not supported on SOCK_PACKET sockets"); + return -1; +} + + +#ifdef HAVE_PF_PACKET_SOCKETS +/* + * Map the PACKET_ value to a LINUX_SLL_ value; we + * want the same numerical value to be used in + * the link-layer header even if the numerical values + * for the PACKET_ #defines change, so that programs + * that look at the packet type field will always be + * able to handle DLT_LINUX_SLL captures. + */ +static short int +map_packet_type_to_sll_type(short int sll_pkttype) +{ + switch (sll_pkttype) { + + case PACKET_HOST: + return htons(LINUX_SLL_HOST); + + case PACKET_BROADCAST: + return htons(LINUX_SLL_BROADCAST); + + case PACKET_MULTICAST: + return htons(LINUX_SLL_MULTICAST); + + case PACKET_OTHERHOST: + return htons(LINUX_SLL_OTHERHOST); + + case PACKET_OUTGOING: + return htons(LINUX_SLL_OUTGOING); + + default: + return -1; + } +} +#endif + +/* + * Linux uses the ARP hardware type to identify the type of an + * interface. pcap uses the DLT_xxx constants for this. This + * function takes a pointer to a "pcap_t", and an ARPHRD_xxx + * constant, as arguments, and sets "handle->linktype" to the + * appropriate DLT_XXX constant and sets "handle->offset" to + * the appropriate value (to make "handle->offset" plus link-layer + * header length be a multiple of 4, so that the link-layer payload + * will be aligned on a 4-byte boundary when capturing packets). + * (If the offset isn't set here, it'll be 0; add code as appropriate + * for cases where it shouldn't be 0.) + * + * If "cooked_ok" is non-zero, we can use DLT_LINUX_SLL and capture + * in cooked mode; otherwise, we can't use cooked mode, so we have + * to pick some type that works in raw mode, or fail. + * + * Sets the link type to -1 if unable to map the type. + */ +static void map_arphrd_to_dlt(pcap_t *handle, int arptype, int cooked_ok) +{ + switch (arptype) { + + case ARPHRD_ETHER: + /* + * This is (presumably) a real Ethernet capture; give it a + * link-layer-type list with DLT_EN10MB and DLT_DOCSIS, so + * that an application can let you choose it, in case you're + * capturing DOCSIS traffic that a Cisco Cable Modem + * Termination System is putting out onto an Ethernet (it + * doesn't put an Ethernet header onto the wire, it puts raw + * DOCSIS frames out on the wire inside the low-level + * Ethernet framing). + * + * XXX - are there any sorts of "fake Ethernet" that have + * ARPHRD_ETHER but that *shouldn't offer DLT_DOCSIS as + * a Cisco CMTS won't put traffic onto it or get traffic + * bridged onto it? ISDN is handled in "activate_new()", + * as we fall back on cooked mode there; are there any + * others? + */ + handle->dlt_list = (u_int *) malloc(sizeof(u_int) * 2); + /* + * If that fails, just leave the list empty. + */ + if (handle->dlt_list != NULL) { + handle->dlt_list[0] = DLT_EN10MB; + handle->dlt_list[1] = DLT_DOCSIS; + handle->dlt_count = 2; + } + /* FALLTHROUGH */ + + case ARPHRD_METRICOM: + case ARPHRD_LOOPBACK: + handle->linktype = DLT_EN10MB; + handle->offset = 2; + break; + + case ARPHRD_EETHER: + handle->linktype = DLT_EN3MB; + break; + + case ARPHRD_AX25: + handle->linktype = DLT_AX25_KISS; + break; + + case ARPHRD_PRONET: + handle->linktype = DLT_PRONET; + break; + + case ARPHRD_CHAOS: + handle->linktype = DLT_CHAOS; + break; + +#ifndef ARPHRD_IEEE802_TR +#define ARPHRD_IEEE802_TR 800 /* From Linux 2.4 */ +#endif + case ARPHRD_IEEE802_TR: + case ARPHRD_IEEE802: + handle->linktype = DLT_IEEE802; + handle->offset = 2; + break; + + case ARPHRD_ARCNET: + handle->linktype = DLT_ARCNET_LINUX; + break; + +#ifndef ARPHRD_FDDI /* From Linux 2.2.13 */ +#define ARPHRD_FDDI 774 +#endif + case ARPHRD_FDDI: + handle->linktype = DLT_FDDI; + handle->offset = 3; + break; + +#ifndef ARPHRD_ATM /* FIXME: How to #include this? */ +#define ARPHRD_ATM 19 +#endif + case ARPHRD_ATM: + /* + * The Classical IP implementation in ATM for Linux + * supports both what RFC 1483 calls "LLC Encapsulation", + * in which each packet has an LLC header, possibly + * with a SNAP header as well, prepended to it, and + * what RFC 1483 calls "VC Based Multiplexing", in which + * different virtual circuits carry different network + * layer protocols, and no header is prepended to packets. + * + * They both have an ARPHRD_ type of ARPHRD_ATM, so + * you can't use the ARPHRD_ type to find out whether + * captured packets will have an LLC header, and, + * while there's a socket ioctl to *set* the encapsulation + * type, there's no ioctl to *get* the encapsulation type. + * + * This means that + * + * programs that dissect Linux Classical IP frames + * would have to check for an LLC header and, + * depending on whether they see one or not, dissect + * the frame as LLC-encapsulated or as raw IP (I + * don't know whether there's any traffic other than + * IP that would show up on the socket, or whether + * there's any support for IPv6 in the Linux + * Classical IP code); + * + * filter expressions would have to compile into + * code that checks for an LLC header and does + * the right thing. + * + * Both of those are a nuisance - and, at least on systems + * that support PF_PACKET sockets, we don't have to put + * up with those nuisances; instead, we can just capture + * in cooked mode. That's what we'll do, if we can. + * Otherwise, we'll just fail. + */ + if (cooked_ok) + handle->linktype = DLT_LINUX_SLL; + else + handle->linktype = -1; + break; + +#ifndef ARPHRD_IEEE80211 /* From Linux 2.4.6 */ +#define ARPHRD_IEEE80211 801 +#endif + case ARPHRD_IEEE80211: + handle->linktype = DLT_IEEE802_11; + break; + +#ifndef ARPHRD_IEEE80211_PRISM /* From Linux 2.4.18 */ +#define ARPHRD_IEEE80211_PRISM 802 +#endif + case ARPHRD_IEEE80211_PRISM: + handle->linktype = DLT_PRISM_HEADER; + break; + +#ifndef ARPHRD_IEEE80211_RADIOTAP /* new */ +#define ARPHRD_IEEE80211_RADIOTAP 803 +#endif + case ARPHRD_IEEE80211_RADIOTAP: + handle->linktype = DLT_IEEE802_11_RADIO; + break; + + case ARPHRD_PPP: + /* + * Some PPP code in the kernel supplies no link-layer + * header whatsoever to PF_PACKET sockets; other PPP + * code supplies PPP link-layer headers ("syncppp.c"); + * some PPP code might supply random link-layer + * headers (PPP over ISDN - there's code in Ethereal, + * for example, to cope with PPP-over-ISDN captures + * with which the Ethereal developers have had to cope, + * heuristically trying to determine which of the + * oddball link-layer headers particular packets have). + * + * As such, we just punt, and run all PPP interfaces + * in cooked mode, if we can; otherwise, we just treat + * it as DLT_RAW, for now - if somebody needs to capture, + * on a 2.0[.x] kernel, on PPP devices that supply a + * link-layer header, they'll have to add code here to + * map to the appropriate DLT_ type (possibly adding a + * new DLT_ type, if necessary). + */ + if (cooked_ok) + handle->linktype = DLT_LINUX_SLL; + else { + /* + * XXX - handle ISDN types here? We can't fall + * back on cooked sockets, so we'd have to + * figure out from the device name what type of + * link-layer encapsulation it's using, and map + * that to an appropriate DLT_ value, meaning + * we'd map "isdnN" devices to DLT_RAW (they + * supply raw IP packets with no link-layer + * header) and "isdY" devices to a new DLT_I4L_IP + * type that has only an Ethernet packet type as + * a link-layer header. + * + * But sometimes we seem to get random crap + * in the link-layer header when capturing on + * ISDN devices.... + */ + handle->linktype = DLT_RAW; + } + break; + +#ifndef ARPHRD_CISCO +#define ARPHRD_CISCO 513 /* previously ARPHRD_HDLC */ +#endif + case ARPHRD_CISCO: + handle->linktype = DLT_C_HDLC; + break; + + /* Not sure if this is correct for all tunnels, but it + * works for CIPE */ + case ARPHRD_TUNNEL: +#ifndef ARPHRD_SIT +#define ARPHRD_SIT 776 /* From Linux 2.2.13 */ +#endif + case ARPHRD_SIT: + case ARPHRD_CSLIP: + case ARPHRD_SLIP6: + case ARPHRD_CSLIP6: + case ARPHRD_ADAPT: + case ARPHRD_SLIP: +#ifndef ARPHRD_RAWHDLC +#define ARPHRD_RAWHDLC 518 +#endif + case ARPHRD_RAWHDLC: +#ifndef ARPHRD_DLCI +#define ARPHRD_DLCI 15 +#endif + case ARPHRD_DLCI: + /* + * XXX - should some of those be mapped to DLT_LINUX_SLL + * instead? Should we just map all of them to DLT_LINUX_SLL? + */ + handle->linktype = DLT_RAW; + break; + +#ifndef ARPHRD_FRAD +#define ARPHRD_FRAD 770 +#endif + case ARPHRD_FRAD: + handle->linktype = DLT_FRELAY; + break; + + case ARPHRD_LOCALTLK: + handle->linktype = DLT_LTALK; + break; + +#ifndef ARPHRD_FCPP +#define ARPHRD_FCPP 784 +#endif + case ARPHRD_FCPP: +#ifndef ARPHRD_FCAL +#define ARPHRD_FCAL 785 +#endif + case ARPHRD_FCAL: +#ifndef ARPHRD_FCPL +#define ARPHRD_FCPL 786 +#endif + case ARPHRD_FCPL: +#ifndef ARPHRD_FCFABRIC +#define ARPHRD_FCFABRIC 787 +#endif + case ARPHRD_FCFABRIC: + /* + * We assume that those all mean RFC 2625 IP-over- + * Fibre Channel, with the RFC 2625 header at + * the beginning of the packet. + */ + handle->linktype = DLT_IP_OVER_FC; + break; + +#ifndef ARPHRD_IRDA +#define ARPHRD_IRDA 783 +#endif + case ARPHRD_IRDA: + /* Don't expect IP packet out of this interfaces... */ + handle->linktype = DLT_LINUX_IRDA; + /* We need to save packet direction for IrDA decoding, + * so let's use "Linux-cooked" mode. Jean II */ + //handle->md.cooked = 1; + break; + + /* ARPHRD_LAPD is unofficial and randomly allocated, if reallocation + * is needed, please report it to */ +#ifndef ARPHRD_LAPD +#define ARPHRD_LAPD 8445 +#endif + case ARPHRD_LAPD: + /* Don't expect IP packet out of this interfaces... */ + handle->linktype = DLT_LINUX_LAPD; + break; + +#ifndef ARPHRD_NONE +#define ARPHRD_NONE 0xFFFE +#endif + case ARPHRD_NONE: + /* + * No link-layer header; packets are just IP + * packets, so use DLT_RAW. + */ + handle->linktype = DLT_RAW; + break; + + default: + handle->linktype = -1; + break; + } +} + +/* ===== Functions to interface to the newer kernels ================== */ + +/* + * Try to open a packet socket using the new kernel PF_PACKET interface. + * Returns 1 on success, 0 on an error that means the new interface isn't + * present (so the old SOCK_PACKET interface should be tried), and a + * PCAP_ERROR_ value on an error that means that the old mechanism won't + * work either (so it shouldn't be tried). + */ +static int +activate_new(pcap_t *handle) +{ +#ifdef HAVE_PF_PACKET_SOCKETS + const char *device = handle->opt.source; + int is_any_device = (strcmp(device, "any") == 0); + int sock_fd = -1, arptype; +#ifdef HAVE_PACKET_AUXDATA + int val; +#endif + int err = 0; + struct packet_mreq mr; + + /* + * Open a socket with protocol family packet. If the + * "any" device was specified, we open a SOCK_DGRAM + * socket for the cooked interface, otherwise we first + * try a SOCK_RAW socket for the raw interface. + */ + sock_fd = is_any_device ? + socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_ALL)) : + socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL)); + + if (sock_fd == -1) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "socket: %s", + pcap_strerror(errno) ); + return 0; /* try old mechanism */ + } + + /* It seems the kernel supports the new interface. */ + handle->md.sock_packet = 0; + + /* + * Get the interface index of the loopback device. + * If the attempt fails, don't fail, just set the + * "md.lo_ifindex" to -1. + * + * XXX - can there be more than one device that loops + * packets back, i.e. devices other than "lo"? If so, + * we'd need to find them all, and have an array of + * indices for them, and check all of them in + * "pcap_read_packet()". + */ + handle->md.lo_ifindex = iface_get_id(sock_fd, "lo", handle->errbuf); + + /* + * Default value for offset to align link-layer payload + * on a 4-byte boundary. + */ + handle->offset = 0; + + /* + * What kind of frames do we have to deal with? Fall back + * to cooked mode if we have an unknown interface type + * or a type we know doesn't work well in raw mode. + */ + if (!is_any_device) { + /* Assume for now we don't need cooked mode. */ + handle->md.cooked = 0; + + if (handle->opt.rfmon) { + /* + * We were asked to turn on monitor mode. + * Do so before we get the link-layer type, + * because entering monitor mode could change + * the link-layer type. + */ + err = enter_rfmon_mode(handle, sock_fd, device); + if (err < 0) { + /* Hard failure */ + close(sock_fd); + return err; + } + if (err == 0) { + /* + * Nothing worked for turning monitor mode + * on. + */ + close(sock_fd); + return PCAP_ERROR_RFMON_NOTSUP; + } + + /* + * Either monitor mode has been turned on for + * the device, or we've been given a different + * device to open for monitor mode. If we've + * been given a different device, use it. + */ + if (handle->md.mondevice != NULL) + device = handle->md.mondevice; + } + arptype = iface_get_arptype(sock_fd, device, handle->errbuf); + if (arptype < 0) { + close(sock_fd); + return arptype; + } + map_arphrd_to_dlt(handle, arptype, 1); + if (handle->linktype == -1 || + handle->linktype == DLT_LINUX_SLL || + handle->linktype == DLT_LINUX_IRDA || + handle->linktype == DLT_LINUX_LAPD || + (handle->linktype == DLT_EN10MB && + (strncmp("isdn", device, 4) == 0 || + strncmp("isdY", device, 4) == 0))) { + /* + * Unknown interface type (-1), or a + * device we explicitly chose to run + * in cooked mode (e.g., PPP devices), + * or an ISDN device (whose link-layer + * type we can only determine by using + * APIs that may be different on different + * kernels) - reopen in cooked mode. + */ + if (close(sock_fd) == -1) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "close: %s", pcap_strerror(errno)); + return PCAP_ERROR; + } + sock_fd = socket(PF_PACKET, SOCK_DGRAM, + htons(ETH_P_ALL)); + if (sock_fd == -1) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "socket: %s", pcap_strerror(errno)); + return PCAP_ERROR; + } + handle->md.cooked = 1; + + /* + * Get rid of any link-layer type list + * we allocated - this only supports cooked + * capture. + */ + if (handle->dlt_list != NULL) { + free(handle->dlt_list); + handle->dlt_list = NULL; + handle->dlt_count = 0; + } + + if (handle->linktype == -1) { + /* + * Warn that we're falling back on + * cooked mode; we may want to + * update "map_arphrd_to_dlt()" + * to handle the new type. + */ + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "arptype %d not " + "supported by libpcap - " + "falling back to cooked " + "socket", + arptype); + } + + /* + * IrDA capture is not a real "cooked" capture, + * it's IrLAP frames, not IP packets. The + * same applies to LAPD capture. + */ + if (handle->linktype != DLT_LINUX_IRDA && + handle->linktype != DLT_LINUX_LAPD) + handle->linktype = DLT_LINUX_SLL; + } + + handle->md.ifindex = iface_get_id(sock_fd, device, + handle->errbuf); + if (handle->md.ifindex == -1) { + close(sock_fd); + return PCAP_ERROR; + } + + if ((err = iface_bind(sock_fd, handle->md.ifindex, + handle->errbuf)) != 1) { + close(sock_fd); + if (err < 0) + return err; + else + return 0; /* try old mechanism */ + } + } else { + /* + * The "any" device. + */ + if (handle->opt.rfmon) { + /* + * It doesn't support monitor mode. + */ + return PCAP_ERROR_RFMON_NOTSUP; + } + + /* + * It uses cooked mode. + */ + handle->md.cooked = 1; + handle->linktype = DLT_LINUX_SLL; + + /* + * We're not bound to a device. + * For now, we're using this as an indication + * that we can't transmit; stop doing that only + * if we figure out how to transmit in cooked + * mode. + */ + handle->md.ifindex = -1; + } + + /* + * Select promiscuous mode on if "promisc" is set. + * + * Do not turn allmulti mode on if we don't select + * promiscuous mode - on some devices (e.g., Orinoco + * wireless interfaces), allmulti mode isn't supported + * and the driver implements it by turning promiscuous + * mode on, and that screws up the operation of the + * card as a normal networking interface, and on no + * other platform I know of does starting a non- + * promiscuous capture affect which multicast packets + * are received by the interface. + */ + + /* + * Hmm, how can we set promiscuous mode on all interfaces? + * I am not sure if that is possible at all. For now, we + * silently ignore attempts to turn promiscuous mode on + * for the "any" device (so you don't have to explicitly + * disable it in programs such as tcpdump). + */ + + if (!is_any_device && handle->opt.promisc) { + memset(&mr, 0, sizeof(mr)); + mr.mr_ifindex = handle->md.ifindex; + mr.mr_type = PACKET_MR_PROMISC; + if (setsockopt(sock_fd, SOL_PACKET, PACKET_ADD_MEMBERSHIP, + &mr, sizeof(mr)) == -1) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "setsockopt: %s", pcap_strerror(errno)); + close(sock_fd); + return PCAP_ERROR; + } + } + + /* Enable auxillary data if supported and reserve room for + * reconstructing VLAN headers. */ +#ifdef HAVE_PACKET_AUXDATA + val = 1; + if (setsockopt(sock_fd, SOL_PACKET, PACKET_AUXDATA, &val, + sizeof(val)) == -1 && errno != ENOPROTOOPT) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "setsockopt: %s", pcap_strerror(errno)); + close(sock_fd); + return PCAP_ERROR; + } + handle->offset += VLAN_TAG_LEN; +#endif /* HAVE_PACKET_AUXDATA */ + + /* + * This is a 2.2[.x] or later kernel (we know that + * because we're not using a SOCK_PACKET socket - + * PF_PACKET is supported only in 2.2 and later + * kernels). + * + * We can safely pass "recvfrom()" a byte count + * based on the snapshot length. + * + * If we're in cooked mode, make the snapshot length + * large enough to hold a "cooked mode" header plus + * 1 byte of packet data (so we don't pass a byte + * count of 0 to "recvfrom()"). + */ + if (handle->md.cooked) { + if (handle->snapshot < SLL_HDR_LEN + 1) + handle->snapshot = SLL_HDR_LEN + 1; + } + handle->bufsize = handle->snapshot; + + /* Save the socket FD in the pcap structure */ + handle->fd = sock_fd; + + return 1; +#else + strncpy(ebuf, + "New packet capturing interface not supported by build " + "environment", PCAP_ERRBUF_SIZE); + return 0; +#endif +} + +static int +activate_mmap(pcap_t *handle) +{ +#ifdef HAVE_PACKET_RING + int ret; + + /* + * Attempt to allocate a buffer to hold the contents of one + * packet, for use by the oneshot callback. + */ + handle->md.oneshot_buffer = malloc(handle->snapshot); + if (handle->md.oneshot_buffer == NULL) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "can't allocate oneshot buffer: %s", + pcap_strerror(errno)); + return PCAP_ERROR; + } + + if (handle->opt.buffer_size == 0) { + /* by default request 2M for the ring buffer */ + handle->opt.buffer_size = 2*1024*1024; + } + ret = prepare_tpacket_socket(handle); + if (ret != 1) { + free(handle->md.oneshot_buffer); + return ret; + } + ret = create_ring(handle); + if (ret != 1) { + free(handle->md.oneshot_buffer); + return ret; + } + + /* override some defaults and inherit the other fields from + * activate_new + * handle->offset is used to get the current position into the rx ring + * handle->cc is used to store the ring size */ + handle->read_op = pcap_read_linux_mmap; + handle->cleanup_op = pcap_cleanup_linux_mmap; + handle->setfilter_op = pcap_setfilter_linux_mmap; + handle->setnonblock_op = pcap_setnonblock_mmap; + handle->getnonblock_op = pcap_getnonblock_mmap; + handle->oneshot_callback = pcap_oneshot_mmap; + handle->selectable_fd = handle->fd; + return 1; +#else /* HAVE_PACKET_RING */ + return 0; +#endif /* HAVE_PACKET_RING */ +} + +#ifdef HAVE_PACKET_RING +static int +prepare_tpacket_socket(pcap_t *handle) +{ +#ifdef HAVE_TPACKET2 + socklen_t len; + int val; +#endif + + handle->md.tp_version = TPACKET_V1; + handle->md.tp_hdrlen = sizeof(struct tpacket_hdr); + +#ifdef HAVE_TPACKET2 + /* Probe whether kernel supports TPACKET_V2 */ + val = TPACKET_V2; + len = sizeof(val); + if (getsockopt(handle->fd, SOL_PACKET, PACKET_HDRLEN, &val, &len) < 0) { + if (errno == ENOPROTOOPT) + return 1; /* no - just drive on */ + + /* Yes - treat as a failure. */ + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "can't get TPACKET_V2 header len on packet socket: %s", + pcap_strerror(errno)); + return -1; + } + handle->md.tp_hdrlen = val; + + val = TPACKET_V2; + if (setsockopt(handle->fd, SOL_PACKET, PACKET_VERSION, &val, + sizeof(val)) < 0) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "can't activate TPACKET_V2 on packet socket: %s", + pcap_strerror(errno)); + return -1; + } + handle->md.tp_version = TPACKET_V2; + + /* Reserve space for VLAN tag reconstruction */ + val = VLAN_TAG_LEN; + if (setsockopt(handle->fd, SOL_PACKET, PACKET_RESERVE, &val, + sizeof(val)) < 0) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "can't set up reserve on packet socket: %s", + pcap_strerror(errno)); + return -1; + } + +#endif /* HAVE_TPACKET2 */ + return 1; +} + +static int +create_ring(pcap_t *handle) +{ + unsigned i, j, frames_per_block; + struct tpacket_req req; + + /* Note that with large snapshot (say 64K) only a few frames + * will be available in the ring even with pretty large ring size + * (and a lot of memory will be unused). + * The snap len should be carefully chosen to achive best + * performance */ + req.tp_frame_size = TPACKET_ALIGN(handle->snapshot + + TPACKET_ALIGN(handle->md.tp_hdrlen) + + sizeof(struct sockaddr_ll)); + req.tp_frame_nr = handle->opt.buffer_size/req.tp_frame_size; + + /* compute the minumum block size that will handle this frame. + * The block has to be page size aligned. + * The max block size allowed by the kernel is arch-dependent and + * it's not explicitly checked here. */ + req.tp_block_size = getpagesize(); + while (req.tp_block_size < req.tp_frame_size) + req.tp_block_size <<= 1; + + frames_per_block = req.tp_block_size/req.tp_frame_size; + + /* ask the kernel to create the ring */ +retry: + req.tp_block_nr = req.tp_frame_nr / frames_per_block; + + /* req.tp_frame_nr is requested to match frames_per_block*req.tp_block_nr */ + req.tp_frame_nr = req.tp_block_nr * frames_per_block; + + if (setsockopt(handle->fd, SOL_PACKET, PACKET_RX_RING, + (void *) &req, sizeof(req))) { + if ((errno == ENOMEM) && (req.tp_block_nr > 1)) { + /* + * Memory failure; try to reduce the requested ring + * size. + * + * We used to reduce this by half -- do 5% instead. + * That may result in more iterations and a longer + * startup, but the user will be much happier with + * the resulting buffer size. + */ + if (req.tp_frame_nr < 20) + req.tp_frame_nr -= 1; + else + req.tp_frame_nr -= req.tp_frame_nr/20; + goto retry; + } + if (errno == ENOPROTOOPT) { + /* + * We don't have ring buffer support in this kernel. + */ + return 0; + } + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "can't create rx ring on packet socket: %s", + pcap_strerror(errno)); + return -1; + } + + /* memory map the rx ring */ + handle->md.mmapbuflen = req.tp_block_nr * req.tp_block_size; + handle->md.mmapbuf = mmap(0, handle->md.mmapbuflen, + PROT_READ|PROT_WRITE, MAP_SHARED, handle->fd, 0); + if (handle->md.mmapbuf == MAP_FAILED) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "can't mmap rx ring: %s", pcap_strerror(errno)); + + /* clear the allocated ring on error*/ + destroy_ring(handle); + return -1; + } + + /* allocate a ring for each frame header pointer*/ + handle->cc = req.tp_frame_nr; + handle->buffer = malloc(handle->cc * sizeof(union thdr *)); + if (!handle->buffer) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "can't allocate ring of frame headers: %s", + pcap_strerror(errno)); + + destroy_ring(handle); + return -1; + } + + /* fill the header ring with proper frame ptr*/ + handle->offset = 0; + for (i=0; imd.mmapbuf[i*req.tp_block_size]; + for (j=0; joffset) { + RING_GET_FRAME(handle) = base; + base += req.tp_frame_size; + } + } + + handle->bufsize = req.tp_frame_size; + handle->offset = 0; + return 1; +} + +/* free all ring related resources*/ +static void +destroy_ring(pcap_t *handle) +{ + /* tell the kernel to destroy the ring*/ + struct tpacket_req req; + memset(&req, 0, sizeof(req)); + setsockopt(handle->fd, SOL_PACKET, PACKET_RX_RING, + (void *) &req, sizeof(req)); + + /* if ring is mapped, unmap it*/ + if (handle->md.mmapbuf) { + /* do not test for mmap failure, as we can't recover from any error */ + munmap(handle->md.mmapbuf, handle->md.mmapbuflen); + handle->md.mmapbuf = NULL; + } +} + +/* + * Special one-shot callback, used for pcap_next() and pcap_next_ex(), + * for Linux mmapped capture. + * + * The problem is that pcap_next() and pcap_next_ex() expect the packet + * data handed to the callback to be valid after the callback returns, + * but pcap_read_linux_mmap() has to release that packet as soon as + * the callback returns (otherwise, the kernel thinks there's still + * at least one unprocessed packet available in the ring, so a select() + * will immediately return indicating that there's data to process), so, + * in the callback, we have to make a copy of the packet. + * + * Yes, this means that, if the capture is using the ring buffer, using + * pcap_next() or pcap_next_ex() requires more copies than using + * pcap_loop() or pcap_dispatch(). If that bothers you, don't use + * pcap_next() or pcap_next_ex(). + */ +static void +pcap_oneshot_mmap(u_char *user, const struct pcap_pkthdr *h, + const u_char *bytes) +{ + struct pkt_for_oneshot *sp = (struct pkt_for_oneshot *)user; + bpf_u_int32 copylen; + + *sp->hdr = *h; + memcpy(sp->pd->md.oneshot_buffer, bytes, h->caplen); + *sp->pkt = sp->pd->md.oneshot_buffer; +} + +static void +pcap_cleanup_linux_mmap( pcap_t *handle ) +{ + destroy_ring(handle); + if (handle->md.oneshot_buffer != NULL) { + free(handle->md.oneshot_buffer); + handle->md.oneshot_buffer = NULL; + } + pcap_cleanup_linux(handle); +} + + +static int +pcap_getnonblock_mmap(pcap_t *p, char *errbuf) +{ + /* use negative value of timeout to indicate non blocking ops */ + return (p->md.timeout<0); +} + +static int +pcap_setnonblock_mmap(pcap_t *p, int nonblock, char *errbuf) +{ + /* map each value to the corresponding 2's complement, to + * preserve the timeout value provided with pcap_set_timeout */ + if (nonblock) { + if (p->md.timeout >= 0) { + /* + * Timeout is non-negative, so we're not already + * in non-blocking mode; set it to the 2's + * complement, to make it negative, as an + * indication that we're in non-blocking mode. + */ + p->md.timeout = p->md.timeout*-1 - 1; + } + } else { + if (p->md.timeout < 0) { + /* + * Timeout is negative, so we're not already + * in blocking mode; reverse the previous + * operation, to make the timeout non-negative + * again. + */ + p->md.timeout = (p->md.timeout+1)*-1; + } + } + return 0; +} + +static inline union thdr * +pcap_get_ring_frame(pcap_t *handle, int status) +{ + union thdr h; + + h.raw = RING_GET_FRAME(handle); + switch (handle->md.tp_version) { + case TPACKET_V1: + if (status != (h.h1->tp_status ? TP_STATUS_USER : + TP_STATUS_KERNEL)) + return NULL; + break; +#ifdef HAVE_TPACKET2 + case TPACKET_V2: + if (status != (h.h2->tp_status ? TP_STATUS_USER : + TP_STATUS_KERNEL)) + return NULL; + break; #endif + } + return h.raw; +} -#include -#include -#include -#include +static int +pcap_read_linux_mmap(pcap_t *handle, int max_packets, pcap_handler callback, + u_char *user) +{ + int pkts = 0; -#include -#ifdef HAVE_NET_IF_ARP_H -#include -#else -#include + /* wait for frames availability.*/ + if ((handle->md.timeout >= 0) && + !pcap_get_ring_frame(handle, TP_STATUS_USER)) { + struct pollfd pollinfo; + int ret; + + pollinfo.fd = handle->fd; + pollinfo.events = POLLIN; + + do { + /* poll() requires a negative timeout to wait forever */ + ret = poll(&pollinfo, 1, (handle->md.timeout > 0)? + handle->md.timeout: -1); + if ((ret < 0) && (errno != EINTR)) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "can't poll on packet socket fd %d: %d-%s", + handle->fd, errno, pcap_strerror(errno)); + return -1; + } + /* check for break loop condition on interrupted syscall*/ + if (handle->break_loop) { + handle->break_loop = 0; + return -2; + } + } while (ret < 0); + } + + /* non-positive values of max_packets are used to require all + * packets currently available in the ring */ + while ((pkts < max_packets) || (max_packets <= 0)) { + int run_bpf; + struct sockaddr_ll *sll; + struct pcap_pkthdr pcaphdr; + unsigned char *bp; + union thdr h; + unsigned int tp_len; + unsigned int tp_mac; + unsigned int tp_snaplen; + unsigned int tp_sec; + unsigned int tp_usec; + + h.raw = pcap_get_ring_frame(handle, TP_STATUS_USER); + if (!h.raw) + break; + + switch (handle->md.tp_version) { + case TPACKET_V1: + tp_len = h.h1->tp_len; + tp_mac = h.h1->tp_mac; + tp_snaplen = h.h1->tp_snaplen; + tp_sec = h.h1->tp_sec; + tp_usec = h.h1->tp_usec; + break; +#ifdef HAVE_TPACKET2 + case TPACKET_V2: + tp_len = h.h2->tp_len; + tp_mac = h.h2->tp_mac; + tp_snaplen = h.h2->tp_snaplen; + tp_sec = h.h2->tp_sec; + tp_usec = h.h2->tp_nsec / 1000; + break; #endif -#include + default: + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "unsupported tpacket version %d", + handle->md.tp_version); + return -1; + } + /* perform sanity check on internal offset. */ + if (tp_mac + tp_snaplen > handle->bufsize) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "corrupted frame on kernel ring mac " + "offset %d + caplen %d > frame len %d", + tp_mac, tp_snaplen, handle->bufsize); + return -1; + } -#include + /* run filter on received packet + * If the kernel filtering is enabled we need to run the + * filter until all the frames present into the ring + * at filter creation time are processed. + * In such case md.use_bpf is used as a counter for the + * packet we need to filter. + * Note: alternatively it could be possible to stop applying + * the filter when the ring became empty, but it can possibly + * happen a lot later... */ + bp = (unsigned char*)h.raw + tp_mac; + run_bpf = (!handle->md.use_bpf) || + ((handle->md.use_bpf>1) && handle->md.use_bpf--); + if (run_bpf && handle->fcode.bf_insns && + (bpf_filter(handle->fcode.bf_insns, bp, + tp_len, tp_snaplen) == 0)) + goto skip; -#include -#include -#include -#include -#include -#include + /* + * Do checks based on packet direction. + */ + sll = (void *)h.raw + TPACKET_ALIGN(handle->md.tp_hdrlen); + if (sll->sll_pkttype == PACKET_OUTGOING) { + /* + * Outgoing packet. + * If this is from the loopback device, reject it; + * we'll see the packet as an incoming packet as well, + * and we don't want to see it twice. + */ + if (sll->sll_ifindex == handle->md.lo_ifindex) + goto skip; + + /* + * If the user only wants incoming packets, reject it. + */ + if (handle->direction == PCAP_D_IN) + goto skip; + } else { + /* + * Incoming packet. + * If the user only wants outgoing packets, reject it. + */ + if (handle->direction == PCAP_D_OUT) + goto skip; + } -static struct ifreq saved_ifr; + /* get required packet info from ring header */ + pcaphdr.ts.tv_sec = tp_sec; + pcaphdr.ts.tv_usec = tp_usec; + pcaphdr.caplen = tp_snaplen; + pcaphdr.len = tp_len; -#include "pcap-int.h" + /* if required build in place the sll header*/ + if (handle->md.cooked) { + struct sll_header *hdrp; + + /* + * The kernel should have left us with enough + * space for an sll header; back up the packet + * data pointer into that space, as that'll be + * the beginning of the packet we pass to the + * callback. + */ + bp -= SLL_HDR_LEN; + + /* + * Let's make sure that's past the end of + * the tpacket header, i.e. >= + * ((u_char *)thdr + TPACKET_HDRLEN), so we + * don't step on the header when we construct + * the sll header. + */ + if (bp < (u_char *)h.raw + + TPACKET_ALIGN(handle->md.tp_hdrlen) + + sizeof(struct sockaddr_ll)) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "cooked-mode frame doesn't have room for sll header"); + return -1; + } + + /* + * OK, that worked; construct the sll header. + */ + hdrp = (struct sll_header *)bp; + hdrp->sll_pkttype = map_packet_type_to_sll_type( + sll->sll_pkttype); + hdrp->sll_hatype = htons(sll->sll_hatype); + hdrp->sll_halen = htons(sll->sll_halen); + memcpy(hdrp->sll_addr, sll->sll_addr, SLL_ADDRLEN); + hdrp->sll_protocol = sll->sll_protocol; -#include "gnuc.h" -#ifdef HAVE_OS_PROTO_H -#include "os-proto.h" + /* update packet len */ + pcaphdr.caplen += SLL_HDR_LEN; + pcaphdr.len += SLL_HDR_LEN; + } + +#ifdef HAVE_TPACKET2 + if (handle->md.tp_version == TPACKET_V2 && h.h2->tp_vlan_tci && + tp_snaplen >= 2 * ETH_ALEN) { + struct vlan_tag *tag; + + bp -= VLAN_TAG_LEN; + memmove(bp, bp + VLAN_TAG_LEN, 2 * ETH_ALEN); + + tag = (struct vlan_tag *)(bp + 2 * ETH_ALEN); + tag->vlan_tpid = htons(ETH_P_8021Q); + tag->vlan_tci = htons(h.h2->tp_vlan_tci); + + pcaphdr.caplen += VLAN_TAG_LEN; + pcaphdr.len += VLAN_TAG_LEN; + } #endif -void linux_restore_ifr(void); + /* + * The only way to tell the kernel to cut off the + * packet at a snapshot length is with a filter program; + * if there's no filter program, the kernel won't cut + * the packet off. + * + * Trim the snapshot length to be no longer than the + * specified snapshot length. + */ + if (pcaphdr.caplen > handle->snapshot) + pcaphdr.caplen = handle->snapshot; -int -pcap_stats(pcap_t *p, struct pcap_stat *ps) -{ + /* pass the packet to the user */ + pkts++; + callback(user, &pcaphdr, bp); + handle->md.packets_read++; - *ps = p->md.stat; - return (0); +skip: + /* next packet */ + switch (handle->md.tp_version) { + case TPACKET_V1: + h.h1->tp_status = TP_STATUS_KERNEL; + break; +#ifdef HAVE_TPACKET2 + case TPACKET_V2: + h.h2->tp_status = TP_STATUS_KERNEL; + break; +#endif + } + if (++handle->offset >= handle->cc) + handle->offset = 0; + + /* check for break loop condition*/ + if (handle->break_loop) { + handle->break_loop = 0; + return -2; + } + } + return pkts; } -int -pcap_read(pcap_t *p, int cnt, pcap_handler callback, u_char *user) +static int +pcap_setfilter_linux_mmap(pcap_t *handle, struct bpf_program *filter) { - register int cc; - register int bufsize; - register int caplen; - register u_char *bp; - struct sockaddr from; - int fromlen; + int n, offset; + int ret; + + /* + * Don't rewrite "ret" instructions; we don't need to, as + * we're not reading packets with recvmsg(), and we don't + * want to, as, by not rewriting them, the kernel can avoid + * copying extra data. + */ + ret = pcap_setfilter_linux_common(handle, filter, 1); + if (ret < 0) + return ret; - bp = p->buffer + p->offset; - bufsize = p->bufsize; - if (p->md.pad > 0) { - memset(bp, 0, p->md.pad); - bp += p->md.pad; - bufsize -= p->md.pad; + /* if the kernel filter is enabled, we need to apply the filter on + * all packets present into the ring. Get an upper bound of their number + */ + if (!handle->md.use_bpf) + return ret; + + /* walk the ring backward and count the free slot */ + offset = handle->offset; + if (--handle->offset < 0) + handle->offset = handle->cc - 1; + for (n=0; n < handle->cc; ++n) { + if (--handle->offset < 0) + handle->offset = handle->cc - 1; + if (!pcap_get_ring_frame(handle, TP_STATUS_KERNEL)) + break; } -again: - do { - fromlen = sizeof(from); - cc = recvfrom(p->fd, bp, bufsize, 0, &from, &fromlen); - if (cc < 0) { - /* Don't choke when we get ptraced */ - switch (errno) { + /* be careful to not change current ring position */ + handle->offset = offset; + + /* store the number of packets currently present in the ring */ + handle->md.use_bpf = 1 + (handle->cc - n); + return ret; +} - case EINTR: - goto again; +#endif /* HAVE_PACKET_RING */ - case EWOULDBLOCK: - return (0); /* XXX */ - } - sprintf(p->errbuf, "read: %s", pcap_strerror(errno)); - return (-1); - } - } while (strcmp(p->md.device, from.sa_data)); - /* If we need have leading zero bytes, adjust count */ - cc += p->md.pad; - bp = p->buffer + p->offset; +#ifdef HAVE_PF_PACKET_SOCKETS +/* + * Return the index of the given device name. Fill ebuf and return + * -1 on failure. + */ +static int +iface_get_id(int fd, const char *device, char *ebuf) +{ + struct ifreq ifr; + + memset(&ifr, 0, sizeof(ifr)); + strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name)); - /* If we need to step over leading junk, adjust count and pointer */ - cc -= p->md.skip; - bp += p->md.skip; + if (ioctl(fd, SIOCGIFINDEX, &ifr) == -1) { + snprintf(ebuf, PCAP_ERRBUF_SIZE, + "SIOCGIFINDEX: %s", pcap_strerror(errno)); + return -1; + } - /* Captured length can't exceed our read buffer size */ - caplen = cc; - if (caplen > bufsize) - caplen = bufsize; + return ifr.ifr_ifindex; +} - /* Captured length can't exceed the snapshot length */ - if (caplen > p->snapshot) - caplen = p->snapshot; +/* + * Bind the socket associated with FD to the given device. + * Return 1 on success, 0 if we should try a SOCK_PACKET socket, + * or a PCAP_ERROR_ value on a hard error. + */ +static int +iface_bind(int fd, int ifindex, char *ebuf) +{ + struct sockaddr_ll sll; + int err; + socklen_t errlen = sizeof(err); - if (p->fcode.bf_insns == NULL || - bpf_filter(p->fcode.bf_insns, bp, cc, caplen)) { - struct pcap_pkthdr h; + memset(&sll, 0, sizeof(sll)); + sll.sll_family = AF_PACKET; + sll.sll_ifindex = ifindex; + sll.sll_protocol = htons(ETH_P_ALL); - ++p->md.stat.ps_recv; - /* Get timestamp */ - if (ioctl(p->fd, SIOCGSTAMP, &h.ts) < 0) { - sprintf(p->errbuf, "SIOCGSTAMP: %s", - pcap_strerror(errno)); - return (-1); + if (bind(fd, (struct sockaddr *) &sll, sizeof(sll)) == -1) { + if (errno == ENETDOWN) { + /* + * Return a "network down" indication, so that + * the application can report that rather than + * saying we had a mysterious failure and + * suggest that they report a problem to the + * libpcap developers. + */ + return PCAP_ERROR_IFACE_NOT_UP; + } else { + snprintf(ebuf, PCAP_ERRBUF_SIZE, + "bind: %s", pcap_strerror(errno)); + return PCAP_ERROR; } - h.len = cc; - h.caplen = caplen; - (*callback)(user, &h, bp); - return (1); } - return (0); + + /* Any pending errors, e.g., network is down? */ + + if (getsockopt(fd, SOL_SOCKET, SO_ERROR, &err, &errlen) == -1) { + snprintf(ebuf, PCAP_ERRBUF_SIZE, + "getsockopt: %s", pcap_strerror(errno)); + return 0; + } + + if (err == ENETDOWN) { + /* + * Return a "network down" indication, so that + * the application can report that rather than + * saying we had a mysterious failure and + * suggest that they report a problem to the + * libpcap developers. + */ + return PCAP_ERROR_IFACE_NOT_UP; + } else if (err > 0) { + snprintf(ebuf, PCAP_ERRBUF_SIZE, + "bind: %s", pcap_strerror(err)); + return 0; + } + + return 1; } -pcap_t * -pcap_open_live(char *device, int snaplen, int promisc, int to_ms, char *ebuf) +#ifdef IW_MODE_MONITOR +/* + * Check whether the device supports the Wireless Extensions. + * Returns 1 if it does, 0 if it doesn't, PCAP_ERROR_NO_SUCH_DEVICE + * if the device doesn't even exist. + */ +static int +has_wext(int sock_fd, const char *device, char *ebuf) { - register int fd, broadcast; - register pcap_t *p; - struct ifreq ifr; - struct sockaddr sa; + struct iwreq ireq; + + strncpy(ireq.ifr_ifrn.ifrn_name, device, + sizeof ireq.ifr_ifrn.ifrn_name); + ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; + if (ioctl(sock_fd, SIOCGIWNAME, &ireq) >= 0) + return 1; /* yes */ + snprintf(ebuf, PCAP_ERRBUF_SIZE, + "%s: SIOCGIWPRIV: %s", device, pcap_strerror(errno)); + if (errno == ENODEV) + return PCAP_ERROR_NO_SUCH_DEVICE; + return 0; +} + +/* + * Per me si va ne la citta dolente, + * Per me si va ne l'etterno dolore, + * ... + * Lasciate ogne speranza, voi ch'intrate. + * + * XXX - airmon-ng does special stuff with the Orinoco driver and the + * wlan-ng driver. + */ +typedef enum { + MONITOR_WEXT, + MONITOR_HOSTAP, + MONITOR_PRISM, + MONITOR_PRISM54, + MONITOR_ACX100, + MONITOR_RT2500, + MONITOR_RT2570, + MONITOR_RT73, + MONITOR_RTL8XXX +} monitor_type; + +/* + * Use the Wireless Extensions, if we have them, to try to turn monitor mode + * on if it's not already on. + * + * Returns 1 on success, 0 if we don't support the Wireless Extensions + * on this device, or a PCAP_ERROR_ value if we do support them but + * we weren't able to turn monitor mode on. + */ +static int +enter_rfmon_mode_wext(pcap_t *handle, int sock_fd, const char *device) +{ + /* + * XXX - at least some adapters require non-Wireless Extensions + * mechanisms to turn monitor mode on. + * + * Atheros cards might require that a separate "monitor virtual access + * point" be created, with later versions of the madwifi driver. + * airmon-ng does "wlanconfig ath create wlandev {if} wlanmode + * monitor -bssid", which apparently spits out a line "athN" + * where "athN" is the monitor mode device. To leave monitor + * mode, it destroys the monitor mode device. + * + * Some Intel Centrino adapters might require private ioctls to get + * radio headers; the ipw2200 and ipw3945 drivers allow you to + * configure a separate "rtapN" interface to capture in monitor + * mode without preventing the adapter from operating normally. + * (airmon-ng doesn't appear to use that, though.) + * + * It would be Truly Wonderful if mac80211 and nl80211 cleaned this + * up, and if all drivers were converted to mac80211 drivers. + * + * If interface {if} is a mac80211 driver, the file + * /sys/class/net/{if}/phy80211 is a symlink to + * /sys/class/ieee80211/{phydev}, for some {phydev}. + * + * On Fedora 9, with a 2.6.26.3-29 kernel, my Zydas stick, at + * least, has a "wmaster0" device and a "wlan0" device; the + * latter is the one with the IP address. Both show up in + * "tcpdump -D" output. Capturing on the wmaster0 device + * captures with 802.11 headers. + * + * airmon-ng searches through /sys/class/net for devices named + * monN, starting with mon0; as soon as one *doesn't* exist, + * it chooses that as the monitor device name. If the "iw" + * command exists, it does "iw dev {if} interface add {monif} + * type monitor", where {monif} is the monitor device. It + * then (sigh) sleeps .1 second, and then configures the + * device up. Otherwise, if /sys/class/ieee80211/{phydev}/add_iface + * is a file, it writes {mondev}, without a newline, to that file, + * and again (sigh) sleeps .1 second, and then iwconfig's that + * device into monitor mode and configures it up. Otherwise, + * you can't do monitor mode. + * + * All these devices are "glued" together by having the + * /sys/class/net/{device}/phy80211 links pointing to the same + * place, so, given a wmaster, wlan, or mon device, you can + * find the other devices by looking for devices with + * the same phy80211 link. + * + * To turn monitor mode off, delete the monitor interface, + * either with "iw dev {monif} interface del" or by sending + * {monif}, with no NL, down /sys/class/ieee80211/{phydev}/remove_iface + * + * Note: if you try to create a monitor device named "monN", and + * there's already a "monN" device, it fails, as least with + * the netlink interface (which is what iw uses), with a return + * value of -ENFILE. (Return values are negative errnos.) We + * could probably use that to find an unused device. + */ + int err; + struct iwreq ireq; + struct iw_priv_args *priv; + monitor_type montype; + int i; + __u32 cmd; + int args[2]; + int channel; + + /* + * Does this device *support* the Wireless Extensions? + */ + err = has_wext(sock_fd, device, handle->errbuf); + if (err <= 0) + return err; /* either it doesn't or the device doesn't even exist */ + /* + * Try to get all the Wireless Extensions private ioctls + * supported by this device. + * + * First, get the size of the buffer we need, by supplying no + * buffer and a length of 0. If the device supports private + * ioctls, it should return E2BIG, with ireq.u.data.length set + * to the length we need. If it doesn't support them, it should + * return EOPNOTSUPP. + */ + memset(&ireq, 0, sizeof ireq); + strncpy(ireq.ifr_ifrn.ifrn_name, device, + sizeof ireq.ifr_ifrn.ifrn_name); + ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; + ireq.u.data.pointer = (void *)args; + ireq.u.data.length = 0; + ireq.u.data.flags = 0; + if (ioctl(sock_fd, SIOCGIWPRIV, &ireq) != -1) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: SIOCGIWPRIV with a zero-length buffer didn't fail!", + device); + return PCAP_ERROR; + } + if (errno == EOPNOTSUPP) { + /* + * No private ioctls, so we assume that there's only one + * DLT_ for monitor mode. + */ + return 0; + } + if (errno != E2BIG) { + /* + * Failed. + */ + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: SIOCGIWPRIV: %s", device, pcap_strerror(errno)); + return PCAP_ERROR; + } + priv = malloc(ireq.u.data.length * sizeof (struct iw_priv_args)); + if (priv == NULL) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "malloc: %s", pcap_strerror(errno)); + return PCAP_ERROR; + } + ireq.u.data.pointer = (void *)priv; + if (ioctl(sock_fd, SIOCGIWPRIV, &ireq) == -1) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: SIOCGIWPRIV: %s", device, pcap_strerror(errno)); + free(priv); + return PCAP_ERROR; + } + + /* + * Look for private ioctls to turn monitor mode on or, if + * monitor mode is on, to set the header type. + */ + montype = MONITOR_WEXT; + cmd = 0; + for (i = 0; i < ireq.u.data.length; i++) { + if (strcmp(priv[i].name, "monitor_type") == 0) { + /* + * Hostap driver, use this one. + * Set monitor mode first. + * You can set it to 0 to get DLT_IEEE80211, + * 1 to get DLT_PRISM, 2 to get + * DLT_IEEE80211_RADIO_AVS, and, with more + * recent versions of the driver, 3 to get + * DLT_IEEE80211_RADIO. + */ + if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_INT) + break; + if (!(priv[i].set_args & IW_PRIV_SIZE_FIXED)) + break; + if ((priv[i].set_args & IW_PRIV_SIZE_MASK) != 1) + break; + montype = MONITOR_HOSTAP; + cmd = priv[i].cmd; + break; + } + if (strcmp(priv[i].name, "set_prismhdr") == 0) { + /* + * Prism54 driver, use this one. + * Set monitor mode first. + * You can set it to 2 to get DLT_IEEE80211 + * or 3 or get DLT_PRISM. + */ + if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_INT) + break; + if (!(priv[i].set_args & IW_PRIV_SIZE_FIXED)) + break; + if ((priv[i].set_args & IW_PRIV_SIZE_MASK) != 1) + break; + montype = MONITOR_PRISM54; + cmd = priv[i].cmd; + break; + } + if (strcmp(priv[i].name, "forceprismheader") == 0) { + /* + * RT2570 driver, use this one. + * Do this after turning monitor mode on. + * You can set it to 1 to get DLT_PRISM or 2 + * to get DLT_IEEE80211. + */ + if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_INT) + break; + if (!(priv[i].set_args & IW_PRIV_SIZE_FIXED)) + break; + if ((priv[i].set_args & IW_PRIV_SIZE_MASK) != 1) + break; + montype = MONITOR_RT2570; + cmd = priv[i].cmd; + break; + } + if (strcmp(priv[i].name, "forceprism") == 0) { + /* + * RT73 driver, use this one. + * Do this after turning monitor mode on. + * Its argument is a *string*; you can + * set it to "1" to get DLT_PRISM or "2" + * to get DLT_IEEE80211. + */ + if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_CHAR) + break; + if (priv[i].set_args & IW_PRIV_SIZE_FIXED) + break; + montype = MONITOR_RT73; + cmd = priv[i].cmd; + break; + } + if (strcmp(priv[i].name, "prismhdr") == 0) { + /* + * One of the RTL8xxx drivers, use this one. + * It can only be done after monitor mode + * has been turned on. You can set it to 1 + * to get DLT_PRISM or 0 to get DLT_IEEE80211. + */ + if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_INT) + break; + if (!(priv[i].set_args & IW_PRIV_SIZE_FIXED)) + break; + if ((priv[i].set_args & IW_PRIV_SIZE_MASK) != 1) + break; + montype = MONITOR_RTL8XXX; + cmd = priv[i].cmd; + break; + } + if (strcmp(priv[i].name, "rfmontx") == 0) { + /* + * RT2500 or RT61 driver, use this one. + * It has one one-byte parameter; set + * u.data.length to 1 and u.data.pointer to + * point to the parameter. + * It doesn't itself turn monitor mode on. + * You can set it to 1 to allow transmitting + * in monitor mode(?) and get DLT_IEEE80211, + * or set it to 0 to disallow transmitting in + * monitor mode(?) and get DLT_PRISM. + */ + if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_INT) + break; + if ((priv[i].set_args & IW_PRIV_SIZE_MASK) != 2) + break; + montype = MONITOR_RT2500; + cmd = priv[i].cmd; + break; + } + if (strcmp(priv[i].name, "monitor") == 0) { + /* + * Either ACX100 or hostap, use this one. + * It turns monitor mode on. + * If it takes two arguments, it's ACX100; + * the first argument is 1 for DLT_PRISM + * or 2 for DLT_IEEE80211, and the second + * argument is the channel on which to + * run. If it takes one argument, it's + * HostAP, and the argument is 2 for + * DLT_IEEE80211 and 3 for DLT_PRISM. + * + * If we see this, we don't quit, as this + * might be a version of the hostap driver + * that also supports "monitor_type". + */ + if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_INT) + break; + if (!(priv[i].set_args & IW_PRIV_SIZE_FIXED)) + break; + switch (priv[i].set_args & IW_PRIV_SIZE_MASK) { - p = (pcap_t *)malloc(sizeof(*p)); - if (p == NULL) { - sprintf(ebuf, "malloc: %s", pcap_strerror(errno)); - return (NULL); + case 1: + montype = MONITOR_PRISM; + cmd = priv[i].cmd; + break; + + case 2: + montype = MONITOR_ACX100; + cmd = priv[i].cmd; + break; + + default: + break; + } + } } - memset(p, 0, sizeof(*p)); - fd = -1; + free(priv); - fd = socket(PF_INET, SOCK_PACKET, htons(ETH_P_ALL)); - if (fd < 0) { - sprintf(ebuf, "socket: %s", pcap_strerror(errno)); - goto bad; + /* + * XXX - ipw3945? islism? + */ + + /* + * Get the old mode. + */ + strncpy(ireq.ifr_ifrn.ifrn_name, device, + sizeof ireq.ifr_ifrn.ifrn_name); + ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; + if (ioctl(sock_fd, SIOCGIWMODE, &ireq) == -1) { + /* + * We probably won't be able to set the mode, either. + */ + return PCAP_ERROR_RFMON_NOTSUP; } - p->fd = fd; - /* Bind to the interface name */ - memset(&sa, 0, sizeof(sa)); - sa.sa_family = AF_INET; - (void)strncpy(sa.sa_data, device, sizeof(sa.sa_data)); - if (bind(p->fd, &sa, sizeof(sa))) { - sprintf(ebuf, "bind: %s: %s", device, pcap_strerror(errno)); - goto bad; + /* + * Is it currently in monitor mode? + */ + if (ireq.u.mode == IW_MODE_MONITOR) { + /* + * Yes. Just leave things as they are. + * We don't offer multiple link-layer types, as + * changing the link-layer type out from under + * somebody else capturing in monitor mode would + * be considered rude. + */ + return 1; } + /* + * No. We have to put the adapter into rfmon mode. + */ - memset(&ifr, 0, sizeof(ifr)); - strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name)); - if (ioctl(p->fd, SIOCGIFHWADDR, &ifr) < 0 ) { - sprintf(ebuf, "SIOCGIFHWADDR: %s", pcap_strerror(errno)); - goto bad; + /* + * If we haven't already done so, arrange to have + * "pcap_close_all()" called when we exit. + */ + if (!pcap_do_addexit(handle)) { + /* + * "atexit()" failed; don't put the interface + * in rfmon mode, just give up. + */ + return PCAP_ERROR_RFMON_NOTSUP; } - broadcast = 0; - switch (ifr.ifr_hwaddr.sa_family) { - case ARPHRD_ETHER: - case ARPHRD_METRICOM: - p->linktype = DLT_EN10MB; - p->offset = 2; - ++broadcast; - break; + /* + * Save the old mode. + */ + handle->md.oldmode = ireq.u.mode; - case ARPHRD_EETHER: - p->linktype = DLT_EN3MB; - ++broadcast; + /* + * Put the adapter in rfmon mode. How we do this depends + * on whether we have a special private ioctl or not. + */ + if (montype == MONITOR_PRISM) { + /* + * We have the "monitor" private ioctl, but none of + * the other private ioctls. Use this, and select + * the Prism header. + * + * If it fails, just fall back on SIOCSIWMODE. + */ + memset(&ireq, 0, sizeof ireq); + strncpy(ireq.ifr_ifrn.ifrn_name, device, + sizeof ireq.ifr_ifrn.ifrn_name); + ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; + ireq.u.data.length = 1; /* 1 argument */ + args[0] = 3; /* request Prism header */ + memcpy(ireq.u.name, args, IFNAMSIZ); + if (ioctl(sock_fd, cmd, &ireq) != -1) { + /* + * Success. + * Note that we have to put the old mode back + * when we close the device. + */ + handle->md.must_do_on_close |= MUST_CLEAR_RFMON; + + /* + * Add this to the list of pcaps to close + * when we exit. + */ + pcap_add_to_pcaps_to_close(handle); + + return 1; + } + + /* + * Failure. Fall back on SIOCSIWMODE. + */ + } + + /* + * First, turn monitor mode on. + */ + strncpy(ireq.ifr_ifrn.ifrn_name, device, + sizeof ireq.ifr_ifrn.ifrn_name); + ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; + ireq.u.mode = IW_MODE_MONITOR; + if (ioctl(sock_fd, SIOCSIWMODE, &ireq) == -1) { + /* + * Scientist, you've failed. + */ + return PCAP_ERROR_RFMON_NOTSUP; + } + + /* + * XXX - airmon-ng does "iwconfig {if} key off" after setting + * monitor mode and setting the channel, and then does + * "iwconfig up". + */ + + /* + * Now select the appropriate radio header. + */ + switch (montype) { + + case MONITOR_WEXT: + /* + * We don't have any private ioctl to set the header. + */ break; - case ARPHRD_AX25: - p->linktype = DLT_AX25; - ++broadcast; + case MONITOR_HOSTAP: + /* + * Try to select the radiotap header. + */ + memset(&ireq, 0, sizeof ireq); + strncpy(ireq.ifr_ifrn.ifrn_name, device, + sizeof ireq.ifr_ifrn.ifrn_name); + ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; + args[0] = 3; /* request radiotap header */ + memcpy(ireq.u.name, args, sizeof (int)); + if (ioctl(sock_fd, cmd, &ireq) != -1) + break; /* success */ + + /* + * That failed. Try to select the AVS header. + */ + memset(&ireq, 0, sizeof ireq); + strncpy(ireq.ifr_ifrn.ifrn_name, device, + sizeof ireq.ifr_ifrn.ifrn_name); + ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; + args[0] = 2; /* request AVS header */ + memcpy(ireq.u.name, args, sizeof (int)); + if (ioctl(sock_fd, cmd, &ireq) != -1) + break; /* success */ + + /* + * That failed. Try to select the Prism header. + */ + memset(&ireq, 0, sizeof ireq); + strncpy(ireq.ifr_ifrn.ifrn_name, device, + sizeof ireq.ifr_ifrn.ifrn_name); + ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; + args[0] = 1; /* request Prism header */ + memcpy(ireq.u.name, args, sizeof (int)); + ioctl(sock_fd, cmd, &ireq); break; - case ARPHRD_PRONET: - p->linktype = DLT_PRONET; + case MONITOR_PRISM: + /* + * The private ioctl failed. + */ break; - case ARPHRD_CHAOS: - p->linktype = DLT_CHAOS; + case MONITOR_PRISM54: + /* + * Select the Prism header. + */ + memset(&ireq, 0, sizeof ireq); + strncpy(ireq.ifr_ifrn.ifrn_name, device, + sizeof ireq.ifr_ifrn.ifrn_name); + ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; + args[0] = 3; /* request Prism header */ + memcpy(ireq.u.name, args, sizeof (int)); + ioctl(sock_fd, cmd, &ireq); break; - case ARPHRD_IEEE802: - p->linktype = DLT_IEEE802; - ++broadcast; + case MONITOR_ACX100: + /* + * Get the current channel. + */ + memset(&ireq, 0, sizeof ireq); + strncpy(ireq.ifr_ifrn.ifrn_name, device, + sizeof ireq.ifr_ifrn.ifrn_name); + ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; + if (ioctl(sock_fd, SIOCGIWFREQ, &ireq) == -1) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: SIOCGIWFREQ: %s", device, + pcap_strerror(errno)); + return PCAP_ERROR; + } + channel = ireq.u.freq.m; + + /* + * Select the Prism header, and set the channel to the + * current value. + */ + memset(&ireq, 0, sizeof ireq); + strncpy(ireq.ifr_ifrn.ifrn_name, device, + sizeof ireq.ifr_ifrn.ifrn_name); + ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; + args[0] = 1; /* request Prism header */ + args[1] = channel; /* set channel */ + memcpy(ireq.u.name, args, 2*sizeof (int)); + ioctl(sock_fd, cmd, &ireq); break; - case ARPHRD_ARCNET: - p->linktype = DLT_ARCNET; - ++broadcast; + case MONITOR_RT2500: + /* + * Disallow transmission - that turns on the + * Prism header. + */ + memset(&ireq, 0, sizeof ireq); + strncpy(ireq.ifr_ifrn.ifrn_name, device, + sizeof ireq.ifr_ifrn.ifrn_name); + ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; + args[0] = 0; /* disallow transmitting */ + memcpy(ireq.u.name, args, sizeof (int)); + ioctl(sock_fd, cmd, &ireq); break; - case ARPHRD_SLIP: - case ARPHRD_CSLIP: - case ARPHRD_SLIP6: - case ARPHRD_CSLIP6: - case ARPHRD_PPP: - p->linktype = DLT_RAW; + case MONITOR_RT2570: + /* + * Force the Prism header. + */ + memset(&ireq, 0, sizeof ireq); + strncpy(ireq.ifr_ifrn.ifrn_name, device, + sizeof ireq.ifr_ifrn.ifrn_name); + ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; + args[0] = 1; /* request Prism header */ + memcpy(ireq.u.name, args, sizeof (int)); + ioctl(sock_fd, cmd, &ireq); break; - case ARPHRD_LOOPBACK: - p->linktype = DLT_NULL; - p->md.pad = 2; - p->md.skip = 12; + case MONITOR_RT73: + /* + * Force the Prism header. + */ + memset(&ireq, 0, sizeof ireq); + strncpy(ireq.ifr_ifrn.ifrn_name, device, + sizeof ireq.ifr_ifrn.ifrn_name); + ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; + ireq.u.data.length = 1; /* 1 argument */ + ireq.u.data.pointer = "1"; + ireq.u.data.flags = 0; + ioctl(sock_fd, cmd, &ireq); break; -#ifdef ARPHRD_FDDI - /* Not all versions of the kernel has this define */ - case ARPHRD_FDDI: - p->linktype = DLT_FDDI; - ++broadcast; + case MONITOR_RTL8XXX: + /* + * Force the Prism header. + */ + memset(&ireq, 0, sizeof ireq); + strncpy(ireq.ifr_ifrn.ifrn_name, device, + sizeof ireq.ifr_ifrn.ifrn_name); + ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; + args[0] = 1; /* request Prism header */ + memcpy(ireq.u.name, args, sizeof (int)); + ioctl(sock_fd, cmd, &ireq); break; -#endif + } -#ifdef notdef - case ARPHRD_LOCALTLK: - case ARPHRD_NETROM: - case ARPHRD_APPLETLK: - case ARPHRD_DLCI: - case ARPHRD_RSRVD: - case ARPHRD_ADAPT: - case ARPHRD_TUNNEL: - case ARPHRD_TUNNEL6: - case ARPHRD_FRAD: - case ARPHRD_SKIP: - /* XXX currently do not know what to do with these... */ - abort(); + /* + * Note that we have to put the old mode back when we + * close the device. + */ + handle->md.must_do_on_close |= MUST_CLEAR_RFMON; + + /* + * Add this to the list of pcaps to close when we exit. + */ + pcap_add_to_pcaps_to_close(handle); + + return 1; +} +#endif /* IW_MODE_MONITOR */ + +/* + * Try various mechanisms to enter monitor mode. + */ +static int +enter_rfmon_mode(pcap_t *handle, int sock_fd, const char *device) +{ +#if defined(HAVE_LIBNL) || defined(IW_MODE_MONITOR) + int ret; #endif - default: - sprintf(ebuf, "unknown physical layer type 0x%x", - ifr.ifr_hwaddr.sa_family); - goto bad; +#ifdef HAVE_LIBNL + ret = enter_rfmon_mode_mac80211(handle, sock_fd, device); + if (ret < 0) + return ret; /* error attempting to do so */ + if (ret == 1) + return 1; /* success */ +#endif /* HAVE_LIBNL */ + +#ifdef IW_MODE_MONITOR + ret = enter_rfmon_mode_wext(handle, sock_fd, device); + if (ret < 0) + return ret; /* error attempting to do so */ + if (ret == 1) + return 1; /* success */ +#endif /* IW_MODE_MONITOR */ + + /* + * Either none of the mechanisms we know about work or none + * of those mechanisms are available, so we can't do monitor + * mode. + */ + return 0; +} + +#endif /* HAVE_PF_PACKET_SOCKETS */ + +/* ===== Functions to interface to the older kernels ================== */ + +/* + * Try to open a packet socket using the old kernel interface. + * Returns 1 on success and a PCAP_ERROR_ value on an error. + */ +static int +activate_old(pcap_t *handle) +{ + int arptype; + struct ifreq ifr; + const char *device = handle->opt.source; + struct utsname utsname; + int mtu; + + /* Open the socket */ + + handle->fd = socket(PF_INET, SOCK_PACKET, htons(ETH_P_ALL)); + if (handle->fd == -1) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "socket: %s", pcap_strerror(errno)); + return PCAP_ERROR_PERM_DENIED; } - /* Base the buffer size on the interface MTU */ - memset(&ifr, 0, sizeof(ifr)); - strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name)); - if (ioctl(p->fd, SIOCGIFMTU, &ifr) < 0 ) { - sprintf(ebuf, "SIOCGIFMTU: %s", pcap_strerror(errno)); - goto bad; + /* It worked - we are using the old interface */ + handle->md.sock_packet = 1; + + /* ...which means we get the link-layer header. */ + handle->md.cooked = 0; + + /* Bind to the given device */ + + if (strcmp(device, "any") == 0) { + strncpy(handle->errbuf, "pcap_activate: The \"any\" device isn't supported on 2.0[.x]-kernel systems", + PCAP_ERRBUF_SIZE); + return PCAP_ERROR; } + if (iface_bind_old(handle->fd, device, handle->errbuf) == -1) + return PCAP_ERROR; - /* Leave room for link header (which is never large under linux...) */ - p->bufsize = ifr.ifr_mtu + 64; + /* + * Try to get the link-layer type. + */ + arptype = iface_get_arptype(handle->fd, device, handle->errbuf); + if (arptype < 0) + return PCAP_ERROR; - p->buffer = (u_char *)malloc(p->bufsize + p->offset); - if (p->buffer == NULL) { - sprintf(ebuf, "malloc: %s", pcap_strerror(errno)); - goto bad; + /* + * Try to find the DLT_ type corresponding to that + * link-layer type. + */ + map_arphrd_to_dlt(handle, arptype, 0); + if (handle->linktype == -1) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "unknown arptype %d", arptype); + return PCAP_ERROR; } - /* XXX */ - if (promisc && broadcast) { + /* Go to promisc mode if requested */ + + if (handle->opt.promisc) { memset(&ifr, 0, sizeof(ifr)); - strcpy(ifr.ifr_name, device); - if (ioctl(p->fd, SIOCGIFFLAGS, &ifr) < 0 ) { - sprintf(ebuf, "SIOCGIFFLAGS: %s", pcap_strerror(errno)); - goto bad; + strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name)); + if (ioctl(handle->fd, SIOCGIFFLAGS, &ifr) == -1) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "SIOCGIFFLAGS: %s", pcap_strerror(errno)); + return PCAP_ERROR; } - saved_ifr = ifr; - ifr.ifr_flags |= IFF_PROMISC; - if (ioctl(p->fd, SIOCSIFFLAGS, &ifr) < 0 ) { - sprintf(ebuf, "SIOCSIFFLAGS: %s", pcap_strerror(errno)); - goto bad; + if ((ifr.ifr_flags & IFF_PROMISC) == 0) { + /* + * Promiscuous mode isn't currently on, + * so turn it on, and remember that + * we should turn it off when the + * pcap_t is closed. + */ + + /* + * If we haven't already done so, arrange + * to have "pcap_close_all()" called when + * we exit. + */ + if (!pcap_do_addexit(handle)) { + /* + * "atexit()" failed; don't put + * the interface in promiscuous + * mode, just give up. + */ + return PCAP_ERROR; + } + + ifr.ifr_flags |= IFF_PROMISC; + if (ioctl(handle->fd, SIOCSIFFLAGS, &ifr) == -1) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "SIOCSIFFLAGS: %s", + pcap_strerror(errno)); + return PCAP_ERROR; + } + handle->md.must_do_on_close |= MUST_CLEAR_PROMISC; + + /* + * Add this to the list of pcaps + * to close when we exit. + */ + pcap_add_to_pcaps_to_close(handle); } - ifr.ifr_flags &= ~IFF_PROMISC; - atexit(linux_restore_ifr); } - p->md.device = strdup(device); - if (p->md.device == NULL) { - sprintf(ebuf, "malloc: %s", pcap_strerror(errno)); - goto bad; + /* + * Compute the buffer size. + * + * We're using SOCK_PACKET, so this might be a 2.0[.x] + * kernel, and might require special handling - check. + */ + if (uname(&utsname) < 0 || + strncmp(utsname.release, "2.0", 3) == 0) { + /* + * Either we couldn't find out what kernel release + * this is, or it's a 2.0[.x] kernel. + * + * In the 2.0[.x] kernel, a "recvfrom()" on + * a SOCK_PACKET socket, with MSG_TRUNC set, will + * return the number of bytes read, so if we pass + * a length based on the snapshot length, it'll + * return the number of bytes from the packet + * copied to userland, not the actual length + * of the packet. + * + * This means that, for example, the IP dissector + * in tcpdump will get handed a packet length less + * than the length in the IP header, and will + * complain about "truncated-ip". + * + * So we don't bother trying to copy from the + * kernel only the bytes in which we're interested, + * but instead copy them all, just as the older + * versions of libpcap for Linux did. + * + * The buffer therefore needs to be big enough to + * hold the largest packet we can get from this + * device. Unfortunately, we can't get the MRU + * of the network; we can only get the MTU. The + * MTU may be too small, in which case a packet larger + * than the buffer size will be truncated *and* we + * won't get the actual packet size. + * + * However, if the snapshot length is larger than + * the buffer size based on the MTU, we use the + * snapshot length as the buffer size, instead; + * this means that with a sufficiently large snapshot + * length we won't artificially truncate packets + * to the MTU-based size. + * + * This mess just one of many problems with packet + * capture on 2.0[.x] kernels; you really want a + * 2.2[.x] or later kernel if you want packet capture + * to work well. + */ + mtu = iface_get_mtu(handle->fd, device, handle->errbuf); + if (mtu == -1) + return PCAP_ERROR; + handle->bufsize = MAX_LINKHEADER_SIZE + mtu; + if (handle->bufsize < handle->snapshot) + handle->bufsize = handle->snapshot; + } else { + /* + * This is a 2.2[.x] or later kernel. + * + * We can safely pass "recvfrom()" a byte count + * based on the snapshot length. + */ + handle->bufsize = handle->snapshot; } - p->snapshot = snaplen; - return (p); -bad: - if (fd >= 0) - (void)close(fd); - if (p->buffer != NULL) - free(p->buffer); - if (p->md.device != NULL) - free(p->md.device); - free(p); - return (NULL); + /* + * Default value for offset to align link-layer payload + * on a 4-byte boundary. + */ + handle->offset = 0; + + return 1; } -int -pcap_setfilter(pcap_t *p, struct bpf_program *fp) +/* + * Bind the socket associated with FD to the given device using the + * interface of the old kernels. + */ +static int +iface_bind_old(int fd, const char *device, char *ebuf) { + struct sockaddr saddr; + int err; + socklen_t errlen = sizeof(err); - p->fcode = *fp; - return (0); + memset(&saddr, 0, sizeof(saddr)); + strncpy(saddr.sa_data, device, sizeof(saddr.sa_data)); + if (bind(fd, &saddr, sizeof(saddr)) == -1) { + snprintf(ebuf, PCAP_ERRBUF_SIZE, + "bind: %s", pcap_strerror(errno)); + return -1; + } + + /* Any pending errors, e.g., network is down? */ + + if (getsockopt(fd, SOL_SOCKET, SO_ERROR, &err, &errlen) == -1) { + snprintf(ebuf, PCAP_ERRBUF_SIZE, + "getsockopt: %s", pcap_strerror(errno)); + return -1; + } + + if (err > 0) { + snprintf(ebuf, PCAP_ERRBUF_SIZE, + "bind: %s", pcap_strerror(err)); + return -1; + } + + return 0; +} + + +/* ===== System calls available on all supported kernels ============== */ + +/* + * Query the kernel for the MTU of the given interface. + */ +static int +iface_get_mtu(int fd, const char *device, char *ebuf) +{ + struct ifreq ifr; + + if (!device) + return BIGGER_THAN_ALL_MTUS; + + memset(&ifr, 0, sizeof(ifr)); + strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name)); + + if (ioctl(fd, SIOCGIFMTU, &ifr) == -1) { + snprintf(ebuf, PCAP_ERRBUF_SIZE, + "SIOCGIFMTU: %s", pcap_strerror(errno)); + return -1; + } + + return ifr.ifr_mtu; +} + +/* + * Get the hardware type of the given interface as ARPHRD_xxx constant. + */ +static int +iface_get_arptype(int fd, const char *device, char *ebuf) +{ + struct ifreq ifr; + + memset(&ifr, 0, sizeof(ifr)); + strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name)); + + if (ioctl(fd, SIOCGIFHWADDR, &ifr) == -1) { + snprintf(ebuf, PCAP_ERRBUF_SIZE, + "SIOCGIFHWADDR: %s", pcap_strerror(errno)); + if (errno == ENODEV) { + /* + * No such device. + */ + return PCAP_ERROR_NO_SUCH_DEVICE; + } + return PCAP_ERROR; + } + + return ifr.ifr_hwaddr.sa_family; +} + +#ifdef SO_ATTACH_FILTER +static int +fix_program(pcap_t *handle, struct sock_fprog *fcode, int is_mmapped) +{ + size_t prog_size; + register int i; + register struct bpf_insn *p; + struct bpf_insn *f; + int len; + + /* + * Make a copy of the filter, and modify that copy if + * necessary. + */ + prog_size = sizeof(*handle->fcode.bf_insns) * handle->fcode.bf_len; + len = handle->fcode.bf_len; + f = (struct bpf_insn *)malloc(prog_size); + if (f == NULL) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "malloc: %s", pcap_strerror(errno)); + return -1; + } + memcpy(f, handle->fcode.bf_insns, prog_size); + fcode->len = len; + fcode->filter = (struct sock_filter *) f; + + for (i = 0; i < len; ++i) { + p = &f[i]; + /* + * What type of instruction is this? + */ + switch (BPF_CLASS(p->code)) { + + case BPF_RET: + /* + * It's a return instruction; are we capturing + * in memory-mapped mode? + */ + if (!is_mmapped) { + /* + * No; is the snapshot length a constant, + * rather than the contents of the + * accumulator? + */ + if (BPF_MODE(p->code) == BPF_K) { + /* + * Yes - if the value to be returned, + * i.e. the snapshot length, is + * anything other than 0, make it + * 65535, so that the packet is + * truncated by "recvfrom()", + * not by the filter. + * + * XXX - there's nothing we can + * easily do if it's getting the + * value from the accumulator; we'd + * have to insert code to force + * non-zero values to be 65535. + */ + if (p->k != 0) + p->k = 65535; + } + } + break; + + case BPF_LD: + case BPF_LDX: + /* + * It's a load instruction; is it loading + * from the packet? + */ + switch (BPF_MODE(p->code)) { + + case BPF_ABS: + case BPF_IND: + case BPF_MSH: + /* + * Yes; are we in cooked mode? + */ + if (handle->md.cooked) { + /* + * Yes, so we need to fix this + * instruction. + */ + if (fix_offset(p) < 0) { + /* + * We failed to do so. + * Return 0, so our caller + * knows to punt to userland. + */ + return 0; + } + } + break; + } + break; + } + } + return 1; /* we succeeded */ +} + +static int +fix_offset(struct bpf_insn *p) +{ + /* + * What's the offset? + */ + if (p->k >= SLL_HDR_LEN) { + /* + * It's within the link-layer payload; that starts at an + * offset of 0, as far as the kernel packet filter is + * concerned, so subtract the length of the link-layer + * header. + */ + p->k -= SLL_HDR_LEN; + } else if (p->k == 14) { + /* + * It's the protocol field; map it to the special magic + * kernel offset for that field. + */ + p->k = SKF_AD_OFF + SKF_AD_PROTOCOL; + } else { + /* + * It's within the header, but it's not one of those + * fields; we can't do that in the kernel, so punt + * to userland. + */ + return -1; + } + return 0; +} + +static int +set_kernel_filter(pcap_t *handle, struct sock_fprog *fcode) +{ + int total_filter_on = 0; + int save_mode; + int ret; + int save_errno; + + /* + * The socket filter code doesn't discard all packets queued + * up on the socket when the filter is changed; this means + * that packets that don't match the new filter may show up + * after the new filter is put onto the socket, if those + * packets haven't yet been read. + * + * This means, for example, that if you do a tcpdump capture + * with a filter, the first few packets in the capture might + * be packets that wouldn't have passed the filter. + * + * We therefore discard all packets queued up on the socket + * when setting a kernel filter. (This isn't an issue for + * userland filters, as the userland filtering is done after + * packets are queued up.) + * + * To flush those packets, we put the socket in read-only mode, + * and read packets from the socket until there are no more to + * read. + * + * In order to keep that from being an infinite loop - i.e., + * to keep more packets from arriving while we're draining + * the queue - we put the "total filter", which is a filter + * that rejects all packets, onto the socket before draining + * the queue. + * + * This code deliberately ignores any errors, so that you may + * get bogus packets if an error occurs, rather than having + * the filtering done in userland even if it could have been + * done in the kernel. + */ + if (setsockopt(handle->fd, SOL_SOCKET, SO_ATTACH_FILTER, + &total_fcode, sizeof(total_fcode)) == 0) { + char drain[1]; + + /* + * Note that we've put the total filter onto the socket. + */ + total_filter_on = 1; + + /* + * Save the socket's current mode, and put it in + * non-blocking mode; we drain it by reading packets + * until we get an error (which is normally a + * "nothing more to be read" error). + */ + save_mode = fcntl(handle->fd, F_GETFL, 0); + if (save_mode != -1 && + fcntl(handle->fd, F_SETFL, save_mode | O_NONBLOCK) >= 0) { + while (recv(handle->fd, &drain, sizeof drain, + MSG_TRUNC) >= 0) + ; + save_errno = errno; + fcntl(handle->fd, F_SETFL, save_mode); + if (save_errno != EAGAIN) { + /* Fatal error */ + reset_kernel_filter(handle); + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "recv: %s", pcap_strerror(save_errno)); + return -2; + } + } + } + + /* + * Now attach the new filter. + */ + ret = setsockopt(handle->fd, SOL_SOCKET, SO_ATTACH_FILTER, + fcode, sizeof(*fcode)); + if (ret == -1 && total_filter_on) { + /* + * Well, we couldn't set that filter on the socket, + * but we could set the total filter on the socket. + * + * This could, for example, mean that the filter was + * too big to put into the kernel, so we'll have to + * filter in userland; in any case, we'll be doing + * filtering in userland, so we need to remove the + * total filter so we see packets. + */ + save_errno = errno; + + /* + * XXX - if this fails, we're really screwed; + * we have the total filter on the socket, + * and it won't come off. What do we do then? + */ + reset_kernel_filter(handle); + + errno = save_errno; + } + return ret; } -void -linux_restore_ifr(void) +static int +reset_kernel_filter(pcap_t *handle) { - register int fd; + /* + * setsockopt() barfs unless it get a dummy parameter. + * valgrind whines unless the value is initialized, + * as it has no idea that setsockopt() ignores its + * parameter. + */ + int dummy = 0; - fd = socket(PF_INET, SOCK_PACKET, htons(0x0003)); - if (fd < 0) - fprintf(stderr, "linux socket: %s", pcap_strerror(errno)); - else if (ioctl(fd, SIOCSIFFLAGS, &saved_ifr) < 0) - fprintf(stderr, "linux SIOCSIFFLAGS: %s", pcap_strerror(errno)); + return setsockopt(handle->fd, SOL_SOCKET, SO_DETACH_FILTER, + &dummy, sizeof(dummy)); } +#endif