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# basic_dump.c

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    00001 #include "pcap.h"
    00002
    00003 /* prototype of the packet handler */
    00004 void packet_handler(u_char *param, const struct pcap_pkthdr *header, const u_char *pkt_data);
    00005
    00006 main()
    00007 {
    00008 pcap_if_t *alldevs;
    00009 pcap_if_t *d;
    00010 int inum;
    00011 int i=0;
    00012 pcap_t *adhandle;
    00013 char errbuf[PCAP_ERRBUF_SIZE];
    00014
    00015     /* Retrieve the device list on the local machine */
    00016     if (pcap_findalldevs_ex(PCAP_SRC_IF_STRING, NULL, &alldevs, errbuf) == -1)
    00017     {
    00018         fprintf(stderr,"Error in pcap_findalldevs: %s\n", errbuf);
    00019         exit(1);
    00020     }
    00021
    00022     /* Print the list */
    00023     for(d=alldevs; d; d=d->next)
    00024     {
    00025         printf("%d. %s", ++i, d->name);
    00026         if (d->description)
    00027             printf(" (%s)\n", d->description);
    00028         else
    00029             printf(" (No description available)\n");
    00030     }
    00031
    00032     if(i==0)
    00033     {
    00034         printf("\nNo interfaces found! Make sure WinPcap is installed.\n");
    00035         return -1;
    00036     }
    00037
    00038     printf("Enter the interface number (1-%d):",i);
    00039     scanf("%d", &inum);
    00040
    00041     if(inum < 1 || inum > i)
    00042     {
    00043         printf("\nInterface number out of range.\n");
    00044         /* Free the device list */
    00045         pcap_freealldevs(alldevs);
    00046         return -1;
    00047     }
    00048
    00049     /* Jump to the selected adapter */
    00050     for(d=alldevs, i=0; i< inum-1 ;d=d->next, i++);
    00051
    00052     /* Open the device */
    00053     if ( (adhandle= pcap_open(d->name,          // name of the device
    00054                               65536,            // portion of the packet to capture
    00055                                                 // 65536 guarantees that the whole packet will be captured on all the link layers
    00056                               PCAP_OPENFLAG_PROMISCUOUS,    // promiscuous mode
    00057                               1000,             // read timeout
    00058                               NULL,             // authentication on the remote machine
    00059                               errbuf            // error buffer
    00060                               ) ) == NULL)
    00061     {
    00062         fprintf(stderr,"\nUnable to open the adapter. %s is not supported by WinPcap\n", d->name);
    00063         /* Free the device list */
    00064         pcap_freealldevs(alldevs);
    00065         return -1;
    00066     }
    00067
    00068     printf("\nlistening on %s...\n", d->description);
    00069
    00070     /* At this point, we don't need any more the device list. Free it */
    00071     pcap_freealldevs(alldevs);
    00072
    00073     /* start the capture */
    00074     pcap_loop(adhandle, 0, packet_handler, NULL);
    00075
    00076     return 0;
    00077 }
    00078
    00079
    00080 /* Callback function invoked by libpcap for every incoming packet */
    00081 void packet_handler(u_char *param, const struct pcap_pkthdr *header, const u_char *pkt_data)
    00082 {
    00083     struct tm *ltime;
    00084     char timestr[16];
    00085
    00086     /* convert the timestamp to readable format */
    00087     ltime=localtime(&header->ts.tv_sec);
    00088     strftime( timestr, sizeof timestr, "%H:%M:%S", ltime);
    00089
    00090     printf("%s,%.6d len:%d\n", timestr, header->ts.tv_usec, header->len);
    00091
    00092 }

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