The Tcpdump Group git mirrors - tcpdump/blob - print-cip.c

   1 /*
   2  * Marko Kiiskila carnil@cs.tut.fi
   3  *
   4  * Tampere University of Technology - Telecommunications Laboratory
   5  *
   6  * Permission to use, copy, modify and distribute this
   7  * software and its documentation is hereby granted,
   8  * provided that both the copyright notice and this
   9  * permission notice appear in all copies of the software,
  10  * derivative works or modified versions, and any portions
  11  * thereof, that both notices appear in supporting
  12  * documentation, and that the use of this software is
  13  * acknowledged in any publications resulting from using
  14  * the software.
  15  *
  16  * TUT ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
  17  * CONDITION AND DISCLAIMS ANY LIABILITY OF ANY KIND FOR
  18  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS
  19  * SOFTWARE.
  20  *
  21  */
  22
  23 /* \summary: Linux Classical IP over ATM printer */
  24
  25 #include <config.h>
  26
  27 #include <string.h>
  28
  29 #include "netdissect-stdinc.h"
  30
  31 #define ND_LONGJMP_FROM_TCHECK
  32 #include "netdissect.h"
  33 #include "addrtoname.h"
  34
  35 static const unsigned char rfcllc[] = {
  36         0xaa,   /* DSAP: non-ISO */
  37         0xaa,   /* SSAP: non-ISO */
  38         0x03,   /* Ctrl: Unnumbered Information Command PDU */
  39         0x00,   /* OUI: EtherType */
  40         0x00,
  41         0x00 };
  42
  43 /*
  44  * This is the top level routine of the printer.  'p' points
  45  * to the LLC/SNAP or raw header of the packet, 'h->ts' is the timestamp,
  46  * 'h->len' is the length of the packet off the wire, and 'h->caplen'
  47  * is the number of bytes actually captured.
  48  */
  49 void
  50 cip_if_print(netdissect_options *ndo, const struct pcap_pkthdr *h, const u_char *p)
  51 {
  52         u_int caplen = h->caplen;
  53         u_int length = h->len;
  54         int llc_hdrlen;
  55
  56         ndo->ndo_protocol = "cip";
  57
  58         if (ndo->ndo_eflag)
  59                 /*
  60                  * There is no MAC-layer header, so just print the length.
  61                  */
  62                 ND_PRINT("%u: ", length);
  63
  64         ND_TCHECK_LEN(p, sizeof(rfcllc));
  65         if (memcmp(rfcllc, p, sizeof(rfcllc)) == 0) {
  66                 /*
  67                  * LLC header is present.  Try to print it & higher layers.
  68                  */
  69                 llc_hdrlen = llc_print(ndo, p, length, caplen, NULL, NULL);
  70                 if (llc_hdrlen < 0) {
  71                         /* packet type not known, print raw packet */
  72                         if (!ndo->ndo_suppress_default_print)
  73                                 ND_DEFAULTPRINT(p, caplen);
  74                         llc_hdrlen = -llc_hdrlen;
  75                 }
  76         } else {
  77                 /*
  78                  * LLC header is absent; treat it as just IP.
  79                  */
  80                 llc_hdrlen = 0;
  81                 ip_print(ndo, p, length);
  82         }
  83
  84         ndo->ndo_ll_hdr_len += llc_hdrlen;
  85 }