The Tcpdump Group git mirrors - libpcap/blob - pcap-snoop.c

   1 /*
   2  * Copyright (c) 1993, 1994, 1995, 1996, 1997
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that: (1) source code distributions
   7  * retain the above copyright notice and this paragraph in its entirety, (2)
   8  * distributions including binary code include the above copyright notice and
   9  * this paragraph in its entirety in the documentation or other materials
  10  * provided with the distribution, and (3) all advertising materials mentioning
  11  * features or use of this software display the following acknowledgement:
  12  * ``This product includes software developed by the University of California,
  13  * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
  14  * the University nor the names of its contributors may be used to endorse
  15  * or promote products derived from this software without specific prior
  16  * written permission.
  17  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
  18  * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
  19  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  20  */
  21 #ifndef lint
  22 static const char rcsid[] _U_ =
  23     "@(#) $Header: /tcpdump/master/libpcap/pcap-snoop.c,v 1.50 2003-12-18 23:32:33 guy Exp $ (LBL)";
  24 #endif
  25
  26 #ifdef HAVE_CONFIG_H
  27 #include "config.h"
  28 #endif
  29
  30 #include <sys/param.h>
  31 #include <sys/file.h>
  32 #include <sys/ioctl.h>
  33 #include <sys/socket.h>
  34 #include <sys/time.h>
  35
  36 #include <net/raw.h>
  37 #include <net/if.h>
  38
  39 #include <netinet/in.h>
  40 #include <netinet/in_systm.h>
  41 #include <netinet/ip.h>
  42 #include <netinet/if_ether.h>
  43 #include <netinet/ip_var.h>
  44 #include <netinet/udp.h>
  45 #include <netinet/udp_var.h>
  46 #include <netinet/tcp.h>
  47 #include <netinet/tcpip.h>
  48
  49 #include <errno.h>
  50 #include <stdio.h>
  51 #include <stdlib.h>
  52 #include <string.h>
  53 #include <unistd.h>
  54
  55 #include "pcap-int.h"
  56
  57 #ifdef HAVE_OS_PROTO_H
  58 #include "os-proto.h"
  59 #endif
  60
  61 static int
  62 pcap_read_snoop(pcap_t *p, int cnt, pcap_handler callback, u_char *user)
  63 {
  64         int cc;
  65         register struct snoopheader *sh;
  66         register int datalen;
  67         register int caplen;
  68         register u_char *cp;
  69
  70 again:
  71         /*
  72          * Has "pcap_breakloop()" been called?
  73          */
  74         if (p->break_loop) {
  75                 /*
  76                  * Yes - clear the flag that indicates that it
  77                  * has, and return -2 to indicate that we were
  78                  * told to break out of the loop.
  79                  */
  80                 p->break_loop = 0;
  81                 return (-2);
  82         }
  83         cc = read(p->fd, (char *)p->buffer, p->bufsize);
  84         if (cc < 0) {
  85                 /* Don't choke when we get ptraced */
  86                 switch (errno) {
  87
  88                 case EINTR:
  89                         goto again;
  90
  91                 case EWOULDBLOCK:
  92                         return (0);                     /* XXX */
  93                 }
  94                 snprintf(p->errbuf, sizeof(p->errbuf),
  95                     "read: %s", pcap_strerror(errno));
  96                 return (-1);
  97         }
  98         sh = (struct snoopheader *)p->buffer;
  99         datalen = sh->snoop_packetlen;
 100         caplen = (datalen < p->snapshot) ? datalen : p->snapshot;
 101         cp = (u_char *)(sh + 1) + p->offset;            /* XXX */
 102
 103         /*
 104          * XXX unfortunately snoop loopback isn't exactly like
 105          * BSD's.  The address family is encoded in the first 2
 106          * bytes rather than the first 4 bytes!  Luckily the last
 107          * two snoop loopback bytes are zeroed.
 108          */
 109         if (p->linktype == DLT_NULL && *((short *)(cp + 2)) == 0) {
 110                 u_int *uip = (u_int *)cp;
 111                 *uip >>= 16;
 112         }
 113
 114         if (p->fcode.bf_insns == NULL ||
 115             bpf_filter(p->fcode.bf_insns, cp, datalen, caplen)) {
 116                 struct pcap_pkthdr h;
 117                 ++p->md.stat.ps_recv;
 118                 h.ts.tv_sec = sh->snoop_timestamp.tv_sec;
 119                 h.ts.tv_usec = sh->snoop_timestamp.tv_usec;
 120                 h.len = datalen;
 121                 h.caplen = caplen;
 122                 (*callback)(user, &h, cp);
 123                 return (1);
 124         }
 125         return (0);
 126 }
 127
 128 static int
 129 pcap_stats_snoop(pcap_t *p, struct pcap_stat *ps)
 130 {
 131         register struct rawstats *rs;
 132         struct rawstats rawstats;
 133
 134         rs = &rawstats;
 135         memset(rs, 0, sizeof(*rs));
 136         if (ioctl(p->fd, SIOCRAWSTATS, (char *)rs) < 0) {
 137                 snprintf(p->errbuf, sizeof(p->errbuf),
 138                     "SIOCRAWSTATS: %s", pcap_strerror(errno));
 139                 return (-1);
 140         }
 141
 142         /*
 143          * "ifdrops" are those dropped by the network interface
 144          * due to resource shortages or hardware errors.
 145          *
 146          * "sbdrops" are those dropped due to socket buffer limits.
 147          *
 148          * As filter is done in userland, "sbdrops" counts packets
 149          * regardless of whether they would've passed the filter.
 150          *
 151          * XXX - does this count *all* Snoop or Drain sockets,
 152          * rather than just this socket?  If not, why does it have
 153          * both Snoop and Drain statistics?
 154          */
 155         p->md.stat.ps_drop =
 156             rs->rs_snoop.ss_ifdrops + rs->rs_snoop.ss_sbdrops +
 157             rs->rs_drain.ds_ifdrops + rs->rs_drain.ds_sbdrops;
 158
 159         /*
 160          * "ps_recv" counts only packets that passed the filter.
 161          * As filtering is done in userland, this does not include
 162          * packets dropped because we ran out of buffer space.
 163          */
 164         *ps = p->md.stat;
 165         return (0);
 166 }
 167
 168 static void
 169 pcap_close_snoop(pcap_t *p)
 170 {
 171         if (p->buffer != NULL)
 172                 free(p->buffer);
 173         if (p->fd >= 0)
 174                 close(p->fd);
 175 }
 176
 177 /* XXX can't disable promiscuous */
 178 pcap_t *
 179 pcap_open_live(const char *device, int snaplen, int promisc, int to_ms,
 180     char *ebuf)
 181 {
 182         int fd;
 183         struct sockaddr_raw sr;
 184         struct snoopfilter sf;
 185         u_int v;
 186         int ll_hdrlen;
 187         int snooplen;
 188         pcap_t *p;
 189         struct ifreq ifr;
 190
 191         p = (pcap_t *)malloc(sizeof(*p));
 192         if (p == NULL) {
 193                 snprintf(ebuf, PCAP_ERRBUF_SIZE, "malloc: %s",
 194                     pcap_strerror(errno));
 195                 return (NULL);
 196         }
 197         memset(p, 0, sizeof(*p));
 198         fd = socket(PF_RAW, SOCK_RAW, RAWPROTO_SNOOP);
 199         if (fd < 0) {
 200                 snprintf(ebuf, PCAP_ERRBUF_SIZE, "snoop socket: %s",
 201                     pcap_strerror(errno));
 202                 goto bad;
 203         }
 204         p->fd = fd;
 205         memset(&sr, 0, sizeof(sr));
 206         sr.sr_family = AF_RAW;
 207         (void)strncpy(sr.sr_ifname, device, sizeof(sr.sr_ifname));
 208         if (bind(fd, (struct sockaddr *)&sr, sizeof(sr))) {
 209                 snprintf(ebuf, PCAP_ERRBUF_SIZE, "snoop bind: %s",
 210                     pcap_strerror(errno));
 211                 goto bad;
 212         }
 213         memset(&sf, 0, sizeof(sf));
 214         if (ioctl(fd, SIOCADDSNOOP, &sf) < 0) {
 215                 snprintf(ebuf, PCAP_ERRBUF_SIZE, "SIOCADDSNOOP: %s",
 216                     pcap_strerror(errno));
 217                 goto bad;
 218         }
 219         v = 64 * 1024;
 220         (void)setsockopt(fd, SOL_SOCKET, SO_RCVBUF, (char *)&v, sizeof(v));
 221         /*
 222          * XXX hack - map device name to link layer type
 223          */
 224         if (strncmp("et", device, 2) == 0 ||    /* Challenge 10 Mbit */
 225             strncmp("ec", device, 2) == 0 ||    /* Indigo/Indy 10 Mbit,
 226                                                    O2 10/100 */
 227             strncmp("ef", device, 2) == 0 ||    /* O200/2000 10/100 Mbit */
 228             strncmp("eg", device, 2) == 0 ||    /* Octane/O2xxx/O3xxx Gigabit */
 229             strncmp("gfe", device, 3) == 0 ||   /* GIO 100 Mbit */
 230             strncmp("fxp", device, 3) == 0 ||   /* Challenge VME Enet */
 231             strncmp("ep", device, 2) == 0 ||    /* Challenge 8x10 Mbit EPLEX */
 232             strncmp("vfe", device, 3) == 0 ||   /* Challenge VME 100Mbit */
 233             strncmp("fa", device, 2) == 0 ||
 234             strncmp("qaa", device, 3) == 0 ||
 235             strncmp("cip", device, 3) == 0 ||
 236             strncmp("el", device, 2) == 0) {
 237                 p->linktype = DLT_EN10MB;
 238                 p->offset = RAW_HDRPAD(sizeof(struct ether_header));
 239                 ll_hdrlen = sizeof(struct ether_header);
 240                 /*
 241                  * This is (presumably) a real Ethernet capture; give it a
 242                  * link-layer-type list with DLT_EN10MB and DLT_DOCSIS, so
 243                  * that an application can let you choose it, in case you're
 244                  * capturing DOCSIS traffic that a Cisco Cable Modem
 245                  * Termination System is putting out onto an Ethernet (it
 246                  * doesn't put an Ethernet header onto the wire, it puts raw
 247                  * DOCSIS frames out on the wire inside the low-level
 248                  * Ethernet framing).
 249                  *
 250                  * XXX - are there any sorts of "fake Ethernet" that have
 251                  * Ethernet link-layer headers but that *shouldn't offer
 252                  * DLT_DOCSIS as a Cisco CMTS won't put traffic onto it
 253                  * or get traffic bridged onto it?  "el" is for ATM LANE
 254                  * Ethernet devices, so that might be the case for them;
 255                  * the same applies for "qaa" classical IP devices.  If
 256                  * "fa" devices are for FORE SPANS, that'd apply to them
 257                  * as well; what are "cip" devices - some other ATM
 258                  * Classical IP devices?
 259                  */
 260                 handle->dlt_list = (u_int *) malloc(sizeof(u_int) * 2);
 261                 /*
 262                  * If that fails, just leave the list empty.
 263                  */
 264                 if (handle->dlt_list != NULL) {
 265                         handle->dlt_list[0] = DLT_EN10MB;
 266                         handle->dlt_list[1] = DLT_DOCSIS;
 267                         handle->dlt_count = 2;
 268                 }
 269         } else if (strncmp("ipg", device, 3) == 0 ||
 270                    strncmp("rns", device, 3) == 0 ||    /* O2/200/2000 FDDI */
 271                    strncmp("xpi", device, 3) == 0) {
 272                 p->linktype = DLT_FDDI;
 273                 p->offset = 3;                          /* XXX yeah? */
 274                 ll_hdrlen = 13;
 275         } else if (strncmp("ppp", device, 3) == 0) {
 276                 p->linktype = DLT_RAW;
 277                 ll_hdrlen = 0;  /* DLT_RAW meaning "no PPP header, just the IP packet"? */
 278         } else if (strncmp("qfa", device, 3) == 0) {
 279                 p->linktype = DLT_IP_OVER_FC;
 280                 ll_hdrlen = 24;
 281         } else if (strncmp("pl", device, 2) == 0) {
 282                 p->linktype = DLT_RAW;
 283                 ll_hdrlen = 0;  /* Cray UNICOS/mp pseudo link */
 284         } else if (strncmp("lo", device, 2) == 0) {
 285                 p->linktype = DLT_NULL;
 286                 ll_hdrlen = 4;
 287         } else {
 288                 snprintf(ebuf, PCAP_ERRBUF_SIZE,
 289                     "snoop: unknown physical layer type");
 290                 goto bad;
 291         }
 292 #ifdef SIOCGIFMTU
 293         /*
 294          * XXX - IRIX appears to give you an error if you try to set the
 295          * capture length to be greater than the MTU, so let's try to get
 296          * the MTU first and, if that succeeds, trim the snap length
 297          * to be no greater than the MTU.
 298          */
 299         (void)strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
 300         if (ioctl(fd, SIOCGIFMTU, (char *)&ifr) < 0) {
 301                 snprintf(ebuf, PCAP_ERRBUF_SIZE, "SIOCGIFMTU: %s",
 302                     pcap_strerror(errno));
 303                 goto bad;
 304         }
 305         /*
 306          * OK, we got it.
 307          *
 308          * XXX - some versions of IRIX 6.5 define "ifr_mtu" and have an
 309          * "ifru_metric" member of the "ifr_ifru" union in an "ifreq"
 310          * structure, others don't.
 311          *
 312          * I've no idea what's going on, so, if "ifr_mtu" isn't defined,
 313          * we define it as "ifr_metric", as using that field appears to
 314          * work on the versions that lack "ifr_mtu" (and, on those that
 315          * don't lack it, "ifru_metric" and "ifru_mtu" are both "int"
 316          * members of the "ifr_ifru" union, which suggests that they
 317          * may be interchangeable in this case).
 318          */
 319 #ifndef ifr_mtu
 320 #define ifr_mtu ifr_metric
 321 #endif
 322         if (snaplen > ifr.ifr_mtu + ll_hdrlen)
 323                 snaplen = ifr.ifr_mtu + ll_hdrlen;
 324 #endif
 325
 326         /*
 327          * The argument to SIOCSNOOPLEN is the number of link-layer
 328          * payload bytes to capture - it doesn't count link-layer
 329          * header bytes.
 330          */
 331         snooplen = snaplen - ll_hdrlen;
 332         if (snooplen < 0)
 333                 snooplen = 0;
 334         if (ioctl(fd, SIOCSNOOPLEN, &snooplen) < 0) {
 335                 snprintf(ebuf, PCAP_ERRBUF_SIZE, "SIOCSNOOPLEN: %s",
 336                     pcap_strerror(errno));
 337                 goto bad;
 338         }
 339         p->snapshot = snaplen;
 340         v = 1;
 341         if (ioctl(fd, SIOCSNOOPING, &v) < 0) {
 342                 snprintf(ebuf, PCAP_ERRBUF_SIZE, "SIOCSNOOPING: %s",
 343                     pcap_strerror(errno));
 344                 goto bad;
 345         }
 346
 347         p->bufsize = 4096;                              /* XXX */
 348         p->buffer = (u_char *)malloc(p->bufsize);
 349         if (p->buffer == NULL) {
 350                 snprintf(ebuf, PCAP_ERRBUF_SIZE, "malloc: %s",
 351                     pcap_strerror(errno));
 352                 goto bad;
 353         }
 354
 355         /*
 356          * "handle->fd" is a socket, so "select()" should work on it.
 357          */
 358         p->selectable_fd = p->fd;
 359
 360         p->read_op = pcap_read_snoop;
 361         p->setfilter_op = install_bpf_program;  /* no kernel filtering */
 362         p->set_datalink_op = NULL;      /* can't change data link type */
 363         p->getnonblock_op = pcap_getnonblock_fd;
 364         p->setnonblock_op = pcap_setnonblock_fd;
 365         p->stats_op = pcap_stats_snoop;
 366         p->close_op = pcap_close_snoop;
 367
 368         return (p);
 369  bad:
 370         (void)close(fd);
 371         /*
 372          * Get rid of any link-layer type list we allocated.
 373          */
 374         if (p->dlt_list != NULL)
 375                 free(p->dlt_list);
 376         free(p);
 377         return (NULL);
 378 }
 379
 380 int
 381 pcap_platform_finddevs(pcap_if_t **alldevsp, char *errbuf)
 382 {
 383         return (0);
 384 }