sjero.net Git - strip6in4/blob - strip6in4.c

   1 /******************************************************************************
   2 Utility to create a pcap file of a 6in4 stream present in an origin pcap file
   3
   4 Copyright (C) 2013  Samuel Jero <sj323707@ohio.edu>
   5
   6 This program is free software: you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation, either version 3 of the License, or
   9 (at your option) any later version.
  10
  11 This program is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 GNU General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18
  19 Author: Samuel Jero <sj323707@ohio.edu>
  20 Date: 03/2013
  21 ******************************************************************************/
  22 #include "strip6in4.h"
  23
  24
  25 #define STRIP6IN4_VERSION 0.1
  26 #define COPYRIGHT_YEAR 2013
  27
  28
  29 pcap_t*                 in;                     /*libpcap input file discriptor*/
  30 pcap_dumper_t   *out;           /*libpcap output file discriptor*/
  31
  32
  33 void handle_packet(u_char *user, const struct pcap_pkthdr *h, const u_char *bytes);
  34 void version();
  35 void usage();
  36
  37 int debug = 0;
  38
  39
  40 /*Parse commandline options and open files*/
  41 int main(int argc, char *argv[])
  42 {
  43         char ebuf[200];
  44         char *erbuffer=ebuf;
  45         char *sfile=NULL;
  46         char *dfile=NULL;
  47         pcap_t* tmp;
  48
  49         /*parse commandline options*/
  50         if(argc > 9){
  51                 usage();
  52         }
  53
  54         /*loop through commandline options*/
  55         for(int i=1; i < argc; i++){
  56                 if(argv[i][0]!='-' || (argv[i][0]=='-' && strlen(argv[i])==1)){
  57                         if(sfile==NULL  || argv[i][0]=='-'){
  58                                 /*assign first non-dash (or only dash) argument to the input file*/
  59                                 sfile=argv[i];
  60                         }else{
  61                                 if(dfile==NULL){
  62                                         dfile=argv[i]; /*assign second non-dash argument to the output file*/
  63                                 }else{
  64                                         usage();
  65                                 }
  66                         }
  67                 }else{
  68                         if(argv[i][1]=='V' && strlen(argv[i])==2){ /* -V */
  69                                 version();
  70                         }else if(argv[i][1]=='h' && strlen(argv[i])==2){ /*-h*/
  71                                 usage();
  72                         }else if(argv[i][1]=='v' && strlen(argv[i])==2){ /*-v*/
  73                                 debug++;
  74                         }else{
  75                                 usage();
  76                         }
  77                 }
  78         }
  79
  80         if(sfile==NULL || dfile==NULL){
  81                 usage();
  82         }
  83
  84         /*all options validated*/
  85
  86         if(debug){
  87                 dbgprintf(1,"Input file: %s\n", sfile);
  88                 dbgprintf(1,"Output file: %s\n", dfile);
  89         }
  90
  91         /*attempt to open input file*/
  92         in=pcap_open_offline(sfile, erbuffer);
  93         if(in==NULL){
  94                 dbgprintf(0,"Error opening input file\n");
  95                 exit(1);
  96         }
  97
  98         /*attempt to open output file*/
  99         tmp=pcap_open_dead(DLT_RAW,65535);
 100         out=pcap_dump_open(tmp,dfile);
 101         if(out==NULL){
 102                 dbgprintf(0,"Error opening output file\n");
 103                 exit(1);
 104         }
 105
 106         /*process packets*/
 107         u_char *user=(u_char*)out;
 108         pcap_loop(in, -1, handle_packet, user);
 109
 110         /*close files*/
 111         pcap_close(in);
 112         pcap_close(tmp);
 113         pcap_dump_close(out);
 114 return 0;
 115 }
 116
 117
 118 /*call back function for pcap_loop--do basic packet handling*/
 119 void handle_packet(u_char *user, const struct pcap_pkthdr *h, const u_char *bytes)
 120 {
 121         int                                     link_type;
 122         struct const_packet     old;
 123
 124         /*Determine the link type for this packet*/
 125         link_type=pcap_datalink(in);
 126
 127         /*Setup packet struct*/
 128         old.h=h;
 129         old.length=h->caplen;
 130         old.data=bytes;
 131         old.private=user;
 132
 133         /*do all the fancy conversions*/
 134         if(!do_encap(link_type, &old)){
 135                 return;
 136         }
 137 return;
 138 }
 139
 140 /*de-encapsulate packet*/
 141 int decap_packet(const struct const_packet* old)
 142 {
 143         struct pcap_pkthdr h;
 144
 145         if(!old || !old->data || !old->h){
 146                 dbgprintf(0,"Error: decap_packet() given bad data!\n");
 147                 return 0;
 148         }
 149
 150         h.ts=old->h->ts;
 151         h.caplen=old->length;
 152         h.len=old->length;
 153
 154         pcap_dump((u_char*)old->private, &h, old->data);
 155 return 0;
 156 }
 157
 158 void version()
 159 {
 160         dbgprintf(0, "strip6in4 version %.1f\n",STRIP6IN4_VERSION);
 161         dbgprintf(0, "Copyright (C) %i Samuel Jero <sj323707@ohio.edu>\n",COPYRIGHT_YEAR);
 162         dbgprintf(0, "This program comes with ABSOLUTELY NO WARRANTY.\n");
 163         dbgprintf(0, "This is free software, and you are welcome to\n");
 164         dbgprintf(0, "redistribute it under certain conditions.\n");
 165         exit(0);
 166 }
 167
 168 /*Usage information for program*/
 169 void usage()
 170 {
 171         dbgprintf(0,"Usage: strip6in4 [-v] [-h] [-V] input_file output_file\n");
 172         dbgprintf(0, "          -v   verbose. May be repeated for additional verbosity.\n");
 173         dbgprintf(0, "          -V   Version information\n");
 174         dbgprintf(0, "          -h   Help\n");
 175         exit(0);
 176 }
 177
 178 /*Debug Printf*/
 179 void dbgprintf(int level, const char *fmt, ...)
 180 {
 181     va_list args;
 182     if(debug>=level){
 183         va_start(args, fmt);
 184         vfprintf(stderr, fmt, args);
 185         va_end(args);
 186     }
 187 }