Projects/Software/TunTapIO/pcap.c

/**********************************************************************
 * rsfio - filtered raw socket to stdin/out proxy                     *
 * Written by: Ivo Smits                              *
 * Compile using: gcc pcap.c -o lpcio -lpcap                          *
 * Many thanks to:                                                    *
 * - http://www.blug.linux.no/rfc1149/                               *
 * - http://linux.about.com/od/commands/l/blcmdl2_select.htm         *
 * - http://www.linuxjournal.com/article/4659                        *
 * - http://www.tcpdump.org/pcap.htm                                 *
 * - http://www.winpcap.org/docs/man/html/                           *
 * - http://www.tcpdump.org/lists/workers/2005/06/msg00102.html      *
 * - http://www.winpcap.org/docs/man/html/                           *
 * - http://www.tcpdump.org/lists/workers/2005/06/msg00102.html      *

#include 
 * 1) include 
 * 2) include 
 * 3) include 
 * 4) include 
 * 5) ifndef HAVE_NETINET_IN_H
 * 1) endif


 * 1) include 


 * 1) include 
 * 2) include 


 * 1) include 
 * 2) include 
 * 3) include 
 * 4) include 
 * 5) include 
 * 6) include 
 * 7) include 
 * 8) include <linux/types.h>
 * 9) include <linux/filter.h>
 * 10) include <linux/if_ether.h>


 * 1) include <pcap.h>

int DumpStats = 1; int IncludePLen = 1;

void got_packet(u_char *args, const struct pcap_pkthdr *header, const u_char *packet);

// The main program, this is where all the magic happens int main(int argc, char** argv) {

//Parse command line arguments if (argc > 1) { if (strcmp(argv[1], "-h") == 0 || strcmp(argv[1], "--help") == 0) { fprintf(stderr, "rsio - raw socket to stdio proxy\n"); fprintf(stderr, "Usage: %s INTF [CLEN] [FILTR]\n", argv[0]); fprintf(stderr, " INTF:  the name of the network interface to connect to\n"); fprintf(stderr, " CLEN:  capture size (should be the same as the mtu, default: %d)\n", ETH_FRAME_LEN); fprintf(stderr, " FILTR: tcpdump style filter expression (man tcpdump)\n"); fprintf(stderr, "Note that the arguments should be in exactly THIS order.\n"); fprintf(stderr, "Report bugs to <Ivo@UFO-Net.nl>\n"); exit(0); }	} else { //Application won't run without arguments //fprintf(stderr, "Try: %s -h\n", argv[0]); //exit(1); }

int CaptureLen = ETH_FRAME_LEN; //Different capture length? if (argc > 2) CaptureLen = atoi(argv[2]); if (CaptureLen < 1) { fprintf(stderr, "Capture length %d invalid!\n", CaptureLen); exit(1); }	fprintf(stderr, "Max packet length: %d\n", CaptureLen);

char *dev, errbuf[PCAP_ERRBUF_SIZE];

if (argc > 1) { dev = argv[1]; } else { if ((dev = pcap_lookupdev(errbuf)) == NULL) { fprintf(stderr, "Couldn't find default device: %s\n", errbuf); exit(1); }	}	fprintf(stderr, "Device: %s\n", dev);

pcap_t *pcap; if ((pcap = pcap_open_live(dev, CaptureLen, 1, 0, errbuf)) == NULL) { fprintf(stderr, "Couldn't open device: %s\n", errbuf); exit(1); }

if (argc > 3) { fprintf(stderr, "Filter: %s\n", argv[3]); struct bpf_program *bpfprog; if (pcap_compile(pcap, &bpfprog, argv[3], 0, 0) == -1) { fprintf(stderr, "Couldn't compile filter: %s\n", pcap_geterr(pcap)); exit(1); }		if (pcap_setfilter(pcap, &bpfprog) == -1) { fprintf(stderr, "Couldn't install filter: %s\n", pcap_geterr(pcap)); exit(1); }	}

fprintf(stderr, "Starting capture!\n"); pcap_loop(pcap, -1, got_packet, NULL);

fprintf(stderr, "PCap finished: shutting down!\n"); pcap_close(pcap); }

void got_packet(u_char *args, const struct pcap_pkthdr *header, const u_char *packet) { if (DumpStats != 0) fprintf(stderr, "R: %d\n", header->caplen); if (IncludePLen == 1) write(1, &header->caplen, 4); write(1, packet, header->caplen); }