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
  48         /*parse commandline options*/
  49         if(argc > 9){
  50                 usage();
  51         }
  52
  53         /*loop through commandline options*/
  54         for(int i=1; i < argc; i++){
  55                 if(argv[i][0]!='-' || (argv[i][0]=='-' && strlen(argv[i])==1)){
  56                         if(sfile==NULL  || argv[i][0]=='-'){
  57                                 /*assign first non-dash (or only dash) argument to the input file*/
  58                                 sfile=argv[i];
  59                         }else{
  60                                 if(dfile==NULL){
  61                                         dfile=argv[i]; /*assign second non-dash argument to the output file*/
  62                                 }else{
  63                                         usage();
  64                                 }
  65                         }
  66                 }else{
  67                         if(argv[i][1]=='V' && strlen(argv[i])==2){ /* -V */
  68                                 version();
  69                         }else if(argv[i][1]=='h' && strlen(argv[i])==2){ /*-h*/
  70                                 usage();
  71                         }else if(argv[i][1]=='v' && strlen(argv[i])==2){ /*-v*/
  72                                 debug++;
  73                         }else{
  74                                 usage();
  75                         }
  76                 }
  77         }
  78
  79         if(sfile==NULL || dfile==NULL){
  80                 usage();
  81         }
  82
  83         /*all options validated*/
  84
  85         if(debug){
  86                 dbgprintf(1,"Input file: %s\n", sfile);
  87                 dbgprintf(1,"Output file: %s\n", dfile);
  88         }
  89
  90         /*attempt to open input file*/
  91         in=pcap_open_offline(dfile, erbuffer);
  92         if(in==NULL){
  93                 dbgprintf(0,"Error opening input file\n");
  94                 exit(1);
  95         }
  96
  97         /*attempt to open output file*/
  98         out=pcap_dump_open(in,dfile);
  99         if(out==NULL){
 100                 dbgprintf(0,"Error opening output file\n");
 101                 exit(1);
 102         }
 103
 104         /*process packets*/
 105         u_char *user=(u_char*)out;
 106         pcap_loop(in, -1, handle_packet, user);
 107
 108         /*close files*/
 109         pcap_close(in);
 110         pcap_dump_close(out);
 111 return 0;
 112 }
 113
 114
 115 /*call back function for pcap_loop--do basic packet handling*/
 116 void handle_packet(u_char *user, const struct pcap_pkthdr *h, const u_char *bytes)
 117 {
 118         int                                     link_type;
 119         struct const_packet     old;
 120
 121         /*Determine the link type for this packet*/
 122         link_type=pcap_datalink(in);
 123
 124         /*Setup packet struct*/
 125         old.h=h;
 126         old.length=h->caplen;
 127         old.data=bytes;
 128         old.private=user;
 129
 130         /*do all the fancy conversions*/
 131         if(!do_encap(link_type, &old)){
 132                 return;
 133         }
 134 return;
 135 }
 136
 137 /*de-encapsulate packet*/
 138 int decap_packet(const struct const_packet* old)
 139 {
 140         struct pcap_pkthdr h;
 141
 142         if(!old || !old->data || !old->h){
 143                 dbgprintf(0,"Error: decap_packet() given bad data!\n");
 144                 return 0;
 145         }
 146
 147         h.ts=old->h->ts;
 148         h.caplen=old->length;
 149         h.len=old->length;
 150
 151         pcap_dump((u_char*)old->private, &h, old->data);
 152 return 0;
 153 }
 154
 155 void version()
 156 {
 157         dbgprintf(0, "strip6in4 version %.1f\n",STRIP6IN4_VERSION);
 158         dbgprintf(0, "Copyright (C) %i Samuel Jero <sj323707@ohio.edu>\n",COPYRIGHT_YEAR);
 159         dbgprintf(0, "This program comes with ABSOLUTELY NO WARRANTY.\n");
 160         dbgprintf(0, "This is free software, and you are welcome to\n");
 161         dbgprintf(0, "redistribute it under certain conditions.\n");
 162         exit(0);
 163 }
 164
 165 /*Usage information for program*/
 166 void usage()
 167 {
 168         dbgprintf(0,"Usage: strip6in4 [-v] [-h] [-V] input_file output_file\n");
 169         dbgprintf(0, "          -v   verbose. May be repeated for additional verbosity.\n");
 170         dbgprintf(0, "          -V   Version information\n");
 171         dbgprintf(0, "          -h   Help\n");
 172         exit(0);
 173 }
 174
 175 /*Debug Printf*/
 176 void dbgprintf(int level, const char *fmt, ...)
 177 {
 178     va_list args;
 179     if(debug>=level){
 180         va_start(args, fmt);
 181         vfprintf(stderr, fmt, args);
 182         va_end(args);
 183     }
 184 }