src/replay.c

   1 /*
   2  * Copyright (C) 2009, 2010  Daniel Borkmann <daniel@netsniff-ng.org> and
   3  *                           Emmanuel Roullit <emmanuel@netsniff-ng.org>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or (at
   8  * your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  12  * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
  13  * for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin St, Fifth Floor, Boston, MA 02110, USA
  18  */
  19
  20 #include <stdio.h>
  21 #include <stdint.h>
  22 #include <stdlib.h>
  23 #include <unistd.h>
  24 #include <assert.h>
  25 #include <errno.h>
  26 #include <fcntl.h>
  27
  28 #include <sys/types.h>
  29
  30 #include <linux/if_packet.h>
  31 #include <linux/if_ether.h>
  32
  33 #include "pcap.h"
  34 #include "replay.h"
  35 #include "macros.h"
  36
  37 int pcap_has_packets(int fd)
  38 {
  39         off_t pos;
  40         struct pcap_sf_pkthdr sf_hdr;
  41
  42         if (fd < 0) {
  43                 warn("Can't open file.\n");
  44                 exit(EXIT_FAILURE);
  45         }
  46
  47         if ((pos = lseek(fd, (off_t) 0, SEEK_CUR)) < 0) {
  48                 err("Cannot seek offset of pcap file");
  49                 close(fd);
  50                 exit(EXIT_FAILURE);
  51         }
  52
  53         /* Test pcap header */
  54         if (read(fd, (char *)&sf_hdr, sizeof(sf_hdr)) != sizeof(sf_hdr)) {
  55                 return 0;       /* EOF */
  56         }
  57
  58         /* Test payload */
  59         if (lseek(fd, pos + sf_hdr.len, SEEK_SET) < 0) {
  60                 return 0;       /* EOF */
  61         }
  62
  63         /* Rewind the offset */
  64         if (lseek(fd, pos, SEEK_SET) < 0) {
  65                 err("Cannot rewind pcap file");
  66                 close(fd);
  67                 exit(EXIT_FAILURE);
  68         }
  69
  70         return 1;
  71 }
  72
  73 int pcap_validate_header(int fd)
  74 {
  75         struct pcap_file_header hdr;
  76
  77         if (fd < 0) {
  78                 warn("Can't open file.\n");
  79                 exit(EXIT_FAILURE);
  80         }
  81
  82         if (read(fd, (char *)&hdr, sizeof(hdr)) != sizeof(hdr)) {
  83                 err("Error reading dump file");
  84                 return -EIO;
  85         }
  86
  87         if (hdr.magic != TCPDUMP_MAGIC
  88             || hdr.version_major != PCAP_VERSION_MAJOR
  89             || hdr.version_minor != PCAP_VERSION_MINOR
  90             || hdr.linktype != LINKTYPE_EN10MB) {
  91                 errno = EINVAL;
  92                 err("This file is certainly not a valid pcap");
  93                 return -EIO;
  94         }
  95
  96         return 0;
  97 }
  98
  99 size_t pcap_fetch_next_packet(int fd, struct tpacket_hdr * tp_h,
 100                               struct ethhdr * sp)
 101 {
 102         struct pcap_sf_pkthdr sf_hdr;
 103
 104         assert(fd > 0);
 105
 106         if (tp_h == NULL || sp == NULL) {
 107                 errno = EINVAL;
 108                 err("Can't access packet header");
 109                 return (0);
 110         }
 111
 112         if (read(fd, (char *)&sf_hdr, sizeof(sf_hdr)) != sizeof(sf_hdr)) {
 113                 return (0);
 114         }
 115
 116         tp_h->tp_sec = sf_hdr.ts.tv_sec;
 117         tp_h->tp_usec = sf_hdr.ts.tv_usec;
 118         tp_h->tp_snaplen = sf_hdr.caplen;
 119         tp_h->tp_len = sf_hdr.len;
 120
 121         if (read(fd, (char *)sp, sf_hdr.len) != sf_hdr.len) {
 122                 return (0);
 123         }
 124
 125         return (sf_hdr.len);
 126 }