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

   1 /*
   2  * Copyright (c) 1993, 1994, 1995, 1996, 1997, 1998
   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 the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the Computer Systems
  16  *      Engineering Group at Lawrence Berkeley Laboratory.
  17  * 4. Neither the name of the University nor of the Laboratory may be used
  18  *    to endorse or promote products derived from this software without
  19  *    specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 #ifndef lint
  35 static const char rcsid[] =
  36     "@(#) $Header: /tcpdump/master/libpcap/pcap.c,v 1.38 2001-12-29 21:55:32 guy Exp $ (LBL)";
  37 #endif
  38
  39 #ifdef HAVE_CONFIG_H
  40 #include "config.h"
  41 #endif
  42
  43 #include <sys/types.h>
  44
  45 #include <stdio.h>
  46 #include <stdlib.h>
  47 #include <string.h>
  48 #include <unistd.h>
  49 #include <fcntl.h>
  50 #include <errno.h>
  51
  52 #ifdef HAVE_OS_PROTO_H
  53 #include "os-proto.h"
  54 #endif
  55
  56 #include "pcap-int.h"
  57
  58 int
  59 pcap_dispatch(pcap_t *p, int cnt, pcap_handler callback, u_char *user)
  60 {
  61
  62         if (p->sf.rfile != NULL)
  63                 return (pcap_offline_read(p, cnt, callback, user));
  64         return (pcap_read(p, cnt, callback, user));
  65 }
  66
  67 int
  68 pcap_loop(pcap_t *p, int cnt, pcap_handler callback, u_char *user)
  69 {
  70         register int n;
  71
  72         for (;;) {
  73                 if (p->sf.rfile != NULL)
  74                         n = pcap_offline_read(p, cnt, callback, user);
  75                 else {
  76                         /*
  77                          * XXX keep reading until we get something
  78                          * (or an error occurs)
  79                          */
  80                         do {
  81                                 n = pcap_read(p, cnt, callback, user);
  82                         } while (n == 0);
  83                 }
  84                 if (n <= 0)
  85                         return (n);
  86                 if (cnt > 0) {
  87                         cnt -= n;
  88                         if (cnt <= 0)
  89                                 return (0);
  90                 }
  91         }
  92 }
  93
  94 struct singleton {
  95         struct pcap_pkthdr *hdr;
  96         const u_char *pkt;
  97 };
  98
  99
 100 static void
 101 pcap_oneshot(u_char *userData, const struct pcap_pkthdr *h, const u_char *pkt)
 102 {
 103         struct singleton *sp = (struct singleton *)userData;
 104         *sp->hdr = *h;
 105         sp->pkt = pkt;
 106 }
 107
 108 const u_char *
 109 pcap_next(pcap_t *p, struct pcap_pkthdr *h)
 110 {
 111         struct singleton s;
 112
 113         s.hdr = h;
 114         if (pcap_dispatch(p, 1, pcap_oneshot, (u_char*)&s) <= 0)
 115                 return (0);
 116         return (s.pkt);
 117 }
 118
 119 int
 120 pcap_datalink(pcap_t *p)
 121 {
 122         return (p->linktype);
 123 }
 124
 125 int
 126 pcap_snapshot(pcap_t *p)
 127 {
 128         return (p->snapshot);
 129 }
 130
 131 int
 132 pcap_is_swapped(pcap_t *p)
 133 {
 134         return (p->sf.swapped);
 135 }
 136
 137 int
 138 pcap_major_version(pcap_t *p)
 139 {
 140         return (p->sf.version_major);
 141 }
 142
 143 int
 144 pcap_minor_version(pcap_t *p)
 145 {
 146         return (p->sf.version_minor);
 147 }
 148
 149 FILE *
 150 pcap_file(pcap_t *p)
 151 {
 152         return (p->sf.rfile);
 153 }
 154
 155 int
 156 pcap_fileno(pcap_t *p)
 157 {
 158         return (p->fd);
 159 }
 160
 161 void
 162 pcap_perror(pcap_t *p, char *prefix)
 163 {
 164         fprintf(stderr, "%s: %s\n", prefix, p->errbuf);
 165 }
 166
 167 char *
 168 pcap_geterr(pcap_t *p)
 169 {
 170         return (p->errbuf);
 171 }
 172
 173 /*
 174  * NOTE: in the future, these may need to call platform-dependent routines,
 175  * e.g. on platforms with memory-mapped packet-capture mechanisms where
 176  * "pcap_read()" uses "select()" or "poll()" to wait for packets to arrive.
 177  */
 178 int
 179 pcap_getnonblock(pcap_t *p, char *errbuf)
 180 {
 181         int fdflags;
 182
 183         if (p->sf.rfile != NULL) {
 184                 /*
 185                  * This is a savefile, not a live capture file, so
 186                  * never say it's in non-blocking mode.
 187                  */
 188                 return (0);
 189         }
 190         fdflags = fcntl(p->fd, F_GETFL, 0);
 191         if (fdflags == -1) {
 192                 snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "F_GETFL: %s",
 193                     pcap_strerror(errno));
 194                 return (-1);
 195         }
 196         if (fdflags & O_NONBLOCK)
 197                 return (1);
 198         else
 199                 return (0);
 200 }
 201
 202 int
 203 pcap_setnonblock(pcap_t *p, int nonblock, char *errbuf)
 204 {
 205         int fdflags;
 206
 207         if (p->sf.rfile != NULL) {
 208                 /*
 209                  * This is a savefile, not a live capture file, so
 210                  * ignore requests to put it in non-blocking mode.
 211                  */
 212                 return (0);
 213         }
 214         fdflags = fcntl(p->fd, F_GETFL, 0);
 215         if (fdflags == -1) {
 216                 snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "F_GETFL: %s",
 217                     pcap_strerror(errno));
 218                 return (-1);
 219         }
 220         if (nonblock)
 221                 fdflags |= O_NONBLOCK;
 222         else
 223                 fdflags &= ~O_NONBLOCK;
 224         if (fcntl(p->fd, F_SETFL, fdflags) == -1) {
 225                 snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "F_SETFL: %s",
 226                     pcap_strerror(errno));
 227                 return (-1);
 228         }
 229         return (0);
 230 }
 231
 232 /*
 233  * Not all systems have strerror().
 234  */
 235 char *
 236 pcap_strerror(int errnum)
 237 {
 238 #ifdef HAVE_STRERROR
 239         return (strerror(errnum));
 240 #else
 241         extern int sys_nerr;
 242         extern const char *const sys_errlist[];
 243         static char ebuf[20];
 244
 245         if ((unsigned int)errnum < sys_nerr)
 246                 return ((char *)sys_errlist[errnum]);
 247         (void)snprintf(ebuf, sizeof ebuf, "Unknown error: %d", errnum);
 248         return(ebuf);
 249 #endif
 250 }
 251
 252 pcap_t *
 253 pcap_open_dead(int linktype, int snaplen)
 254 {
 255         pcap_t *p;
 256
 257         p = malloc(sizeof(*p));
 258         if (p == NULL)
 259                 return NULL;
 260         memset (p, 0, sizeof(*p));
 261         p->fd = -1;
 262         p->snapshot = snaplen;
 263         p->linktype = linktype;
 264         return p;
 265 }
 266
 267 void
 268 pcap_close(pcap_t *p)
 269 {
 270         /*XXX*/
 271         if (p->fd >= 0) {
 272 #ifdef linux
 273                 pcap_close_linux(p);
 274 #endif
 275                 close(p->fd);
 276         }
 277         if (p->sf.rfile != NULL) {
 278                 if (p->sf.rfile != stdin)
 279                         (void)fclose(p->sf.rfile);
 280                 if (p->sf.base != NULL)
 281                         free(p->sf.base);
 282         } else if (p->buffer != NULL)
 283                 free(p->buffer);
 284
 285         pcap_freecode(&p->fcode);
 286         free(p);
 287 }