*
- *
+ *
* 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
* 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.
*/
+
#ifndef lint
-static const char rcsid[] =
- "@(#) $Header: /tcpdump/master/libpcap/pcap-linux.c,v 1.61 2001-07-29 18:25:47 guy Exp $ (LBL)";
+static const char rcsid[] _U_ =
+ "@(#) $Header: /tcpdump/master/libpcap/pcap-linux.c,v 1.110 2004-10-19 07:06:12 guy Exp $ (LBL)";
#endif
/*
* 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.
*/
#include "pcap-int.h"
#include "sll.h"
+#ifdef HAVE_DAG_API
+#include "pcap-dag.h"
+#endif /* HAVE_DAG_API */
+
#include <errno.h>
#include <stdlib.h>
#include <unistd.h>
* isn't defined? It only defines one data structure in 2.0.x, so
* it shouldn't cause any problems.
*/
-#ifdef PF_PACKET
+#ifdef PF_PACKET
# include <linux/if_packet.h>
/*
#endif
#ifndef MSG_TRUNC
-#define MSG_TRUNC 0
+/*
+ * 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.
+/*
+ * 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.
*/
/*
* Prototypes for internal functions
*/
-static int map_arphrd_to_dlt(pcap_t *, int);
-static int live_open_old(pcap_t *, char *, int, int, char *);
-static int live_open_new(pcap_t *, char *, int, int, char *);
+static void map_arphrd_to_dlt(pcap_t *, int, int);
+static int live_open_old(pcap_t *, const char *, int, int, char *);
+static int live_open_new(pcap_t *, const char *, int, int, char *);
+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 void pcap_close_linux(pcap_t *);
/*
* Wrap some ioctl calls
#ifdef SO_ATTACH_FILTER
static int fix_program(pcap_t *handle, struct sock_fprog *fcode);
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
/*
- * Get a handle for a live capture from the given device. You can
- * pass NULL as device to get all packages (without link level
+ * 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
+ * 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).
- *
+ *
* See also pcap(3).
*/
pcap_t *
-pcap_open_live(char *device, int snaplen, int promisc, int to_ms, char *ebuf)
+pcap_open_live(const char *device, int snaplen, int promisc, int to_ms,
+ char *ebuf)
{
+ pcap_t *handle;
+ int mtu;
+ int err;
+ int live_open_ok = 0;
+ struct utsname utsname;
+
+#ifdef HAVE_DAG_API
+ if (strstr(device, "dag")) {
+ return dag_open_live(device, snaplen, promisc, to_ms, ebuf);
+ }
+#endif /* HAVE_DAG_API */
+
/* Allocate a handle for this session. */
- pcap_t *handle = malloc(sizeof(*handle));
+ handle = malloc(sizeof(*handle));
if (handle == NULL) {
snprintf(ebuf, PCAP_ERRBUF_SIZE, "malloc: %s",
pcap_strerror(errno));
handle->md.timeout = to_ms;
/*
- * NULL and "any" are special devices which give us the hint to
+ * NULL and "any" are special devices which give us the hint to
* monitor all devices.
*/
if (!device || strcmp(device, "any") == 0) {
device = NULL;
handle->md.device = strdup("any");
+ if (promisc) {
+ promisc = 0;
+ /* Just a warning. */
+ snprintf(ebuf, PCAP_ERRBUF_SIZE,
+ "Promiscuous mode not supported on the \"any\" device");
+ }
+
} else
handle->md.device = strdup(device);
return NULL;
}
- /*
- * 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
+ /*
+ * 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
+ * to be compatible with older kernels for a while so we are
* trying both methods with the newer method preferred.
*/
- if (! (live_open_new(handle, device, promisc, to_ms, ebuf) ||
- live_open_old(handle, device, promisc, to_ms, ebuf)) )
- {
- /*
+ if ((err = live_open_new(handle, device, promisc, to_ms, ebuf)) == 1)
+ live_open_ok = 1;
+ else if (err == 0) {
+ /* Non-fatal error; try old way */
+ if (live_open_old(handle, device, promisc, to_ms, ebuf))
+ live_open_ok = 1;
+ }
+ if (!live_open_ok) {
+ /*
* Both methods to open the packet socket failed. Tidy
* up and report our failure (ebuf is expected to be
- * set by the functions above).
+ * set by the functions above).
*/
- free(handle->md.device);
+ if (handle->md.device != NULL)
+ free(handle->md.device);
free(handle);
return NULL;
}
+ /*
+ * Compute the buffer size.
+ *
+ * If we're using SOCK_PACKET, this might be a 2.0[.x] kernel,
+ * and might require special handling - check.
+ */
+ if (handle->md.sock_packet && (uname(&utsname) < 0 ||
+ strncmp(utsname.release, "2.0", 3) == 0)) {
+ /*
+ * We're using a SOCK_PACKET structure, and 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, ebuf);
+ if (mtu == -1) {
+ pcap_close_linux(handle);
+ free(handle);
+ return NULL;
+ }
+ 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 know that
+ * either because we're not using a SOCK_PACKET
+ * socket - PF_PACKET is supported only in 2.2
+ * and later kernels - or because we checked the
+ * kernel version).
+ *
+ * We can safely pass "recvfrom()" a byte count
+ * based on the snapshot length.
+ */
+ handle->bufsize = handle->snapshot;
+ }
+
+ /* Allocate the buffer */
+
+ handle->buffer = malloc(handle->bufsize + handle->offset);
+ if (!handle->buffer) {
+ snprintf(ebuf, PCAP_ERRBUF_SIZE,
+ "malloc: %s", pcap_strerror(errno));
+ pcap_close_linux(handle);
+ free(handle);
+ return NULL;
+ }
+
+ /*
+ * "handle->fd" is a socket, so "select()" and "poll()"
+ * should work on it.
+ */
+ handle->selectable_fd = handle->fd;
+
+ handle->read_op = pcap_read_linux;
+ handle->inject_op = pcap_inject_linux;
+ handle->setfilter_op = pcap_setfilter_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->stats_op = pcap_stats_linux;
+ handle->close_op = pcap_close_linux;
+
return handle;
}
/*
* 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.
+ * error occured.
*/
-int
-pcap_read(pcap_t *handle, int max_packets, pcap_handler callback, u_char *user)
+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,
}
/*
- * Read a packet from the socket calling the handler provided by
+ * 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;
/* Receive a single packet from the kernel */
+ bp = handle->buffer + handle->offset;
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;
+ }
fromlen = sizeof(from);
- packet_len = recvfrom(
- handle->fd, handle->buffer + offset + handle->offset,
- handle->md.readlen - offset, MSG_TRUNC,
+ packet_len = recvfrom(
+ handle->fd, bp + offset,
+ handle->bufsize - offset, MSG_TRUNC,
(struct sockaddr *) &from, &fromlen);
} while (packet_len == -1 && errno == EINTR);
*/
packet_len += SLL_HDR_LEN;
- hdrp = (struct sll_header *)handle->buffer;
+ hdrp = (struct sll_header *)bp;
/*
* Map the PACKET_ value to a LINUX_SLL_ value; we
#endif
/*
- * XXX: According to the kernel source we should get the real
- * packet len if calling recvfrom with MSG_TRUNC set. It does
+ * 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.
+ * 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:
+ * that the following is happening:
*
- * The packet comes from a random interface and the packet_rcv
+ * 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
* # tcpdump -d
* (000) ret #68
*
- * So the packet filter cuts down the packet. The recvfrom call
+ * 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.
+ * 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
/* 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, handle->buffer,
+ if (bpf_filter(handle->fcode.bf_insns, bp,
packet_len, caplen) == 0)
{
/* rejected by filter */
handle->md.stat.ps_recv++;
/* Call the user supplied callback function */
- callback(userdata, &pcap_header, handle->buffer + handle->offset);
+ 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
* patches); otherwise, that information isn't available, and we lie
* and report 0 as the count of dropped packets.
*/
-int
-pcap_stats(pcap_t *handle, struct pcap_stat *stats)
+static int
+pcap_stats_linux(pcap_t *handle, struct pcap_stat *stats)
{
#ifdef HAVE_TPACKET_STATS
struct tpacket_stats kstats;
- socklen_t len;
+ 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) {
- handle->md.stat.ps_recv = (kstats.tp_packets - kstats.tp_drops);
- handle->md.stat.ps_drop = kstats.tp_drops;
+ /*
+ * 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;
+ }
+ 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
/*
- * "ps_recv" counts only packets that passed the filter.
+ * 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.
*
- * "ps_drop" is maintained only on systems that support
- * the PACKET_STATISTICS "getsockopt()" argument.
+ * Both statistics include packets not yet read from the
+ * kernel by libpcap, and thus not yet seen by the application.
+ *
+ * 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.
*/
*stats = handle->md.stat;
return 0;
}
/*
- * Attach the given BPF code to the packet capture device.
+ * Description string for the "any" device.
*/
+static const char any_descr[] = "Pseudo-device that captures on all interfaces";
+
int
-pcap_setfilter(pcap_t *handle, struct bpf_program *filter)
+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 */
+
+ return (0);
+}
+
+/*
+ * Attach the given BPF code to the packet capture device.
+ */
+static int
+pcap_setfilter_linux(pcap_t *handle, struct bpf_program *filter)
{
#ifdef SO_ATTACH_FILTER
struct sock_fprog fcode;
int can_filter_in_kernel;
+ int err = 0;
#endif
if (!handle)
/* Make our private copy of the filter */
- if (install_bpf_program(handle, filter) < 0) {
- snprintf(handle->errbuf, sizeof(handle->errbuf),
- "malloc: %s", pcap_strerror(errno));
+ 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;
/*
- * If we're reading from a savefile, don't try to install
- * a kernel filter.
+ * Run user level packet filter by default. Will be overriden if
+ * installing a kernel filter succeeds.
*/
- if (handle->sf.rfile != NULL)
- return 0;
+ handle->md.use_bpf = 0;
/* Install kernel level filter if possible */
#ifdef USHRT_MAX
if (handle->fcode.bf_len > USHRT_MAX) {
/*
- * fcode.len is an unsigned short for current kernel.
+ * 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.
}
if (can_filter_in_kernel) {
- if (setsockopt(handle->fd, SOL_SOCKET, SO_ATTACH_FILTER,
- &fcode, sizeof(fcode)) == 0)
+ if ((err = set_kernel_filter(handle, &fcode)) == 0)
{
/* Installation succeded - using kernel filter. */
handle->md.use_bpf = 1;
}
- else
+ 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",
+ "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;
}
/*
- * Linux uses the ARP hardware type to identify the type of an
- * interface. pcap uses the DLT_xxx constants for this. This
+ * 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
* 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.)
- *
- * Returns -1 if unable to map the type; we print a message and,
- * if we're using PF_PACKET/SOCK_RAW rather than PF_INET/SOCK_PACKET,
- * we fall back on using PF_PACKET/SOCK_DGRAM.
+ *
+ * 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 int map_arphrd_to_dlt(pcap_t *handle, int arptype)
+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 "live_open_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;
break;
case ARPHRD_ARCNET:
- handle->linktype = DLT_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;
#define ARPHRD_ATM 19
#endif
case ARPHRD_ATM:
- handle->linktype = DLT_ATM_CLIP;
+ /*
+ * 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 */
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;
+
case ARPHRD_PPP:
/*
* Some PPP code in the kernel supplies no link-layer
* oddball link-layer headers particular packets have).
*
* As such, we just punt, and run all PPP interfaces
- * in cooked mode.
+ * 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).
*/
- handle->linktype = DLT_LINUX_SLL;
+ 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;
- case ARPHRD_HDLC:
+#ifndef ARPHRD_CISCO
+#define ARPHRD_CISCO 513 /* previously ARPHRD_HDLC */
+#endif
+ case ARPHRD_CISCO:
handle->linktype = DLT_C_HDLC;
break;
* works for CIPE */
case ARPHRD_TUNNEL:
#ifndef ARPHRD_SIT
-#define ARPHRD_SIT 776 /* From Linux 2.2.14 */
+#define ARPHRD_SIT 776 /* From Linux 2.2.13 */
#endif
case ARPHRD_SIT:
case ARPHRD_CSLIP:
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;
+
default:
- return -1;
+ handle->linktype = -1;
+ break;
}
- return 0;
}
/* ===== Functions to interface to the newer kernels ================== */
* FIXME: 0 uses to mean success (Sebastian)
*/
static int
-live_open_new(pcap_t *handle, char *device, int promisc,
+live_open_new(pcap_t *handle, const char *device, int promisc,
int to_ms, char *ebuf)
{
#ifdef HAVE_PF_PACKET_SOCKETS
- int sock_fd = -1, device_id, mtu, arptype;
+ int sock_fd = -1, arptype;
+ int err;
+ int fatal_err = 0;
struct packet_mreq mr;
/* One shot loop used for error handling - bail out with break */
do {
/*
* Open a socket with protocol family packet. If a device is
- * given we try to open it in raw mode otherwise we use
- * the cooked interface.
+ * given we try to open it in raw mode otherwise we use
+ * the cooked interface.
*/
- sock_fd = device ?
+ sock_fd = device ?
socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL))
: socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_ALL));
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.
+ * What kind of frames do we have to deal with? Fall back
+ * to cooked mode if we have an unknown interface type.
*/
if (device) {
handle->md.cooked = 0;
arptype = iface_get_arptype(sock_fd, device, ebuf);
- if (arptype == -1)
+ if (arptype == -1) {
+ fatal_err = 1;
break;
- if (map_arphrd_to_dlt(handle, arptype) == -1 ||
+ }
+ map_arphrd_to_dlt(handle, arptype, 1);
+ if (handle->linktype == -1 ||
handle->linktype == DLT_LINUX_SLL ||
+ handle->linktype == DLT_LINUX_IRDA ||
(handle->linktype == DLT_EN10MB &&
(strncmp("isdn", device, 4) == 0 ||
strncmp("isdY", device, 4) == 0))) {
"close: %s", pcap_strerror(errno));
break;
}
- sock_fd = socket(PF_PACKET, SOCK_DGRAM,
+ sock_fd = socket(PF_PACKET, SOCK_DGRAM,
htons(ETH_P_ALL));
if (sock_fd == -1) {
snprintf(ebuf, PCAP_ERRBUF_SIZE,
}
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
* update "map_arphrd_to_dlt()"
* to handle the new type.
*/
- fprintf(stderr,
- "Warning: arptype %d not "
+ snprintf(ebuf, PCAP_ERRBUF_SIZE,
+ "arptype %d not "
"supported by libpcap - "
"falling back to cooked "
- "socket\n",
+ "socket",
arptype);
}
- handle->linktype = DLT_LINUX_SLL;
+ /* IrDA capture is not a real "cooked" capture,
+ * it's IrLAP frames, not IP packets. */
+ if (handle->linktype != DLT_LINUX_IRDA)
+ handle->linktype = DLT_LINUX_SLL;
}
- device_id = iface_get_id(sock_fd, device, ebuf);
- if (device_id == -1)
+ handle->md.ifindex = iface_get_id(sock_fd, device, ebuf);
+ if (handle->md.ifindex == -1)
break;
- if (iface_bind(sock_fd, device_id, ebuf) == -1)
+ if ((err = iface_bind(sock_fd, handle->md.ifindex,
+ ebuf)) < 0) {
+ if (err == -2)
+ fatal_err = 1;
break;
+ }
} else {
/*
* This is cooked mode.
handle->linktype = DLT_LINUX_SLL;
/*
- * XXX - squelch GCC complaints about
- * uninitialized variables; if we can't
- * select promiscuous mode on all interfaces,
- * we should move the code below into the
- * "if (device)" branch of the "if" and
- * get rid of the next statement.
+ * We're not bound to a device.
+ * XXX - true? Or true only if we're using
+ * the "any" 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.
*/
- device_id = -1;
+ handle->md.ifindex = -1;
}
- /* Select promiscuous mode on/off */
+ /*
+ * 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.
+ */
-#ifdef SOL_PACKET
- /*
+ /*
* Hmm, how can we set promiscuous mode on all interfaces?
* I am not sure if that is possible at all.
*/
- if (device) {
+ if (device && promisc) {
memset(&mr, 0, sizeof(mr));
- mr.mr_ifindex = device_id;
- mr.mr_type = promisc ?
- PACKET_MR_PROMISC : PACKET_MR_ALLMULTI;
- if (setsockopt(sock_fd, SOL_PACKET,
+ 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(ebuf, PCAP_ERRBUF_SIZE,
+ snprintf(ebuf, PCAP_ERRBUF_SIZE,
"setsockopt: %s", pcap_strerror(errno));
break;
}
}
-#endif
-
- /* Compute the buffersize */
-
- mtu = iface_get_mtu(sock_fd, device, ebuf);
- if (mtu == -1)
- break;
- handle->bufsize = MAX_LINKHEADER_SIZE + mtu;
- /* Fill in the pcap structure */
+ /* Save the socket FD in the pcap structure */
handle->fd = sock_fd;
- handle->buffer = malloc(handle->bufsize + handle->offset);
- if (!handle->buffer) {
- snprintf(ebuf, PCAP_ERRBUF_SIZE,
- "malloc: %s", pcap_strerror(errno));
- break;
- }
-
- /*
- * This is a 2.2 or later kernel, as it has PF_PACKET;
- * "recvfrom()", when passed the MSG_TRUNC flag, will
- * return the actual length of the packet, not the
- * number of bytes from the packet copied to userland,
- * so we can safely pass it a byte count based on the
- * snapshot length.
- */
- handle->md.readlen = handle->snapshot;
return 1;
} while(0);
if (sock_fd != -1)
close(sock_fd);
- return 0;
+
+ if (fatal_err) {
+ /*
+ * Get rid of any link-layer type list we allocated.
+ */
+ if (handle->dlt_list != NULL)
+ free(handle->dlt_list);
+ return -2;
+ } else
+ return 0;
#else
- strncpy(ebuf,
- "New packet capturing interface not supported by build "
+ strncpy(ebuf,
+ "New packet capturing interface not supported by build "
"environment", PCAP_ERRBUF_SIZE);
return 0;
#endif
#ifdef HAVE_PF_PACKET_SOCKETS
/*
- * Return the index of the given device name. Fill ebuf and return
+ * Return the index of the given device name. Fill ebuf and return
* -1 on failure.
*/
static int
}
/*
- * Bind the socket associated with FD to the given device.
+ * Bind the socket associated with FD to the given device.
*/
static int
iface_bind(int fd, int ifindex, char *ebuf)
{
struct sockaddr_ll sll;
+ int err;
+ socklen_t errlen = sizeof(err);
memset(&sll, 0, sizeof(sll));
sll.sll_family = AF_PACKET;
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 -2;
+ }
+
+ if (err > 0) {
+ snprintf(ebuf, PCAP_ERRBUF_SIZE,
+ "bind: %s", pcap_strerror(err));
+ return -2;
+ }
+
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.
+ * 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
pcap_close(handle);
}
-void pcap_close_linux( pcap_t *handle )
+static void pcap_close_linux( pcap_t *handle )
{
struct pcap *p, *prevp;
struct ifreq ifr;
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,
+ 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",
*/
ifr.ifr_flags &= ~IFF_PROMISC;
if (ioctl(handle->fd, SIOCSIFFLAGS, &ifr) == -1) {
- fprintf(stderr,
+ 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",
}
}
}
+
if (handle->md.device != NULL)
free(handle->md.device);
+ handle->md.device = NULL;
+ pcap_close_common(handle);
}
/*
* FIXME: 0 uses to mean success (Sebastian)
*/
static int
-live_open_old(pcap_t *handle, char *device, int promisc,
+live_open_old(pcap_t *handle, const char *device, int promisc,
int to_ms, char *ebuf)
{
- int sock_fd = -1, mtu, arptype;
- struct utsname utsname;
+ int arptype;
struct ifreq ifr;
do {
/* Open the socket */
- sock_fd = socket(PF_INET, SOCK_PACKET, htons(ETH_P_ALL));
- if (sock_fd == -1) {
+ handle->fd = socket(PF_INET, SOCK_PACKET, htons(ETH_P_ALL));
+ if (handle->fd == -1) {
snprintf(ebuf, PCAP_ERRBUF_SIZE,
"socket: %s", pcap_strerror(errno));
break;
PCAP_ERRBUF_SIZE);
break;
}
- if (iface_bind_old(sock_fd, device, ebuf) == -1)
+ if (iface_bind_old(handle->fd, device, ebuf) == -1)
+ break;
+
+ /*
+ * Try to get the link-layer type.
+ */
+ arptype = iface_get_arptype(handle->fd, device, ebuf);
+ if (arptype == -1)
break;
- /* Go to promisc mode */
+ /*
+ * Try to find the DLT_ type corresponding to that
+ * link-layer type.
+ */
+ map_arphrd_to_dlt(handle, arptype, 0);
+ if (handle->linktype == -1) {
+ snprintf(ebuf, PCAP_ERRBUF_SIZE,
+ "unknown arptype %d", arptype);
+ break;
+ }
+
+ /* Go to promisc mode if requested */
+
if (promisc) {
memset(&ifr, 0, sizeof(ifr));
strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
- if (ioctl(sock_fd, SIOCGIFFLAGS, &ifr) == -1) {
+ if (ioctl(handle->fd, SIOCGIFFLAGS, &ifr) == -1) {
snprintf(ebuf, PCAP_ERRBUF_SIZE,
"ioctl: %s", pcap_strerror(errno));
break;
PCAP_ERRBUF_SIZE);
break;
}
+ did_atexit = 1;
}
ifr.ifr_flags |= IFF_PROMISC;
- if (ioctl(sock_fd, SIOCSIFFLAGS, &ifr) == -1) {
+ if (ioctl(handle->fd, SIOCSIFFLAGS, &ifr) == -1) {
snprintf(ebuf, PCAP_ERRBUF_SIZE,
"ioctl: %s",
pcap_strerror(errno));
}
}
- /* Compute the buffersize */
-
- mtu = iface_get_mtu(sock_fd, device, ebuf);
- if (mtu == -1)
- break;
- handle->bufsize = MAX_LINKHEADER_SIZE + mtu;
- if (handle->bufsize < handle->snapshot)
- handle->bufsize = handle->snapshot;
-
- /* All done - fill in the pcap handle */
-
- arptype = iface_get_arptype(sock_fd, device, ebuf);
- if (arptype == -1)
- break;
-
/*
* Default value for offset to align link-layer payload
* on a 4-byte boundary.
*/
handle->offset = 0;
- handle->fd = sock_fd;
-
- /*
- * 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.
- */
- if (map_arphrd_to_dlt(handle, arptype) == -1) {
- snprintf(ebuf, PCAP_ERRBUF_SIZE,
- "interface type of %s not supported", device);
- break;
- }
- handle->buffer = malloc(handle->bufsize + handle->offset);
- if (!handle->buffer) {
- snprintf(ebuf, PCAP_ERRBUF_SIZE,
- "malloc: %s", pcap_strerror(errno));
- break;
- }
-
- /*
- * This might be a 2.0[.x] kernel - 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.
- *
- * 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.
- */
- handle->md.readlen = handle->bufsize;
- } else {
- /*
- * This is a 2.2[.x] or later kernel (although
- * why we're using SOCK_PACKET on such a system
- * is unknown to me).
- *
- * We can safely pass "recvfrom()" a byte count
- * based on the snapshot length.
- */
- handle->md.readlen = handle->snapshot;
- }
return 1;
} while (0);
- if (sock_fd != -1)
- close(sock_fd);
+ pcap_close_linux(handle);
return 0;
}
/*
- * Bind the socket associated with FD to the given device using the
+ * 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);
memset(&saddr, 0, sizeof(saddr));
strncpy(saddr.sa_data, device, sizeof(saddr.sa_data));
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.
+ * Query the kernel for the MTU of the given interface.
*/
static int
iface_get_mtu(int fd, const char *device, char *ebuf)
return ifr.ifr_hwaddr.sa_family;
}
-#ifdef HAVE_PF_PACKET_SOCKETS
+#ifdef SO_ATTACH_FILTER
static int
fix_program(pcap_t *handle, struct sock_fprog *fcode)
{
}
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, sizeof(handle->errbuf),
+ "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;
+}
+
+static int
+reset_kernel_filter(pcap_t *handle)
+{
+ /* setsockopt() barfs unless it get a dummy parameter */
+ int dummy;
+
+ return setsockopt(handle->fd, SOL_SOCKET, SO_DETACH_FILTER,
+ &dummy, sizeof(dummy));
+}
#endif
projects / libpcap / blobdiff