wiretap/atm.c

   1 /* atm.c
   2  *
   3  * $Id$
   4  *
   5  * Wiretap Library
   6  * Copyright (c) 1998 by Gilbert Ramirez <gram@alumni.rice.edu>
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public License
  10  * as published by the Free Software Foundation; either version 2
  11  * of the License, or (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  21  */
  22
  23 #include "config.h"
  24 #include "wtap-int.h"
  25 #include "atm.h"
  26
  27 /*
  28  * Routines to use with ATM capture file types that don't include information
  29  * about the *type* of ATM traffic (or, at least, where we haven't found
  30  * that information).
  31  *
  32  * We assume the traffic is AAL5, unless it's VPI 0/VCI 5, in which case
  33  * we assume it's the signalling AAL.
  34  */
  35
  36 void
  37 atm_guess_traffic_type(const guint8 *pd, guint32 len,
  38     union wtap_pseudo_header *pseudo_header)
  39 {
  40         /*
  41          * Start out assuming nothing other than that it's AAL5.
  42          */
  43         pseudo_header->atm.aal = AAL_5;
  44         pseudo_header->atm.type = TRAF_UNKNOWN;
  45         pseudo_header->atm.subtype = TRAF_ST_UNKNOWN;
  46
  47         if (pseudo_header->atm.vpi == 0) {
  48                 /*
  49                  * Traffic on some PVCs with a VPI of 0 and certain
  50                  * VCIs is of particular types.
  51                  */
  52                 switch (pseudo_header->atm.vci) {
  53
  54                 case 5:
  55                         /*
  56                          * Signalling AAL.
  57                          */
  58                         pseudo_header->atm.aal = AAL_SIGNALLING;
  59                         return;
  60
  61                 case 16:
  62                         /*
  63                          * ILMI.
  64                          */
  65                         pseudo_header->atm.type = TRAF_ILMI;
  66                         return;
  67                 }
  68         }
  69
  70         /*
  71          * OK, we can't tell what it is based on the VPI/VCI; try
  72          * guessing based on the contents, if we have enough data
  73          * to guess.
  74          */
  75
  76         if (len >= 3) {
  77                 if (pd[0] == 0xaa && pd[1] == 0xaa && pd[2] == 0x03) {
  78                         /*
  79                          * Looks like a SNAP header; assume it's LLC
  80                          * multiplexed RFC 1483 traffic.
  81                          */
  82                         pseudo_header->atm.type = TRAF_LLCMX;
  83                 } else if ((pseudo_header->atm.aal5t_len &&
  84                         pseudo_header->atm.aal5t_len < 16) || len<16) {
  85                         /*
  86                          * As this cannot be a LANE Ethernet frame (less
  87                          * than 2 bytes of LANE header + 14 bytes of
  88                          * Ethernet header) we can try it as a SSCOP frame.
  89                          */
  90                         pseudo_header->atm.aal = AAL_SIGNALLING;
  91                 } else if (pd[0] == 0x83 || pd[0] == 0x81) {
  92                         /*
  93                          * MTP3b headers often encapsulate
  94                          * a SCCP or MTN in the 3G network.
  95                          * This should cause 0x83 or 0x81
  96                          * in the first byte.
  97                          */
  98                         pseudo_header->atm.aal = AAL_SIGNALLING;
  99                 } else {
 100                         /*
 101                          * Assume it's LANE.
 102                          */
 103                         pseudo_header->atm.type = TRAF_LANE;
 104                         atm_guess_lane_type(pd, len, pseudo_header);
 105                 }
 106         } else {
 107                /*
 108                 * Not only VCI 5 is used for signaling. It might be
 109                 * one of these VCIs.
 110                 */
 111                pseudo_header->atm.aal = AAL_SIGNALLING;
 112         }
 113 }
 114
 115 void
 116 atm_guess_lane_type(const guint8 *pd, guint32 len,
 117     union wtap_pseudo_header *pseudo_header)
 118 {
 119         if (len >= 2) {
 120                 if (pd[0] == 0xff && pd[1] == 0x00) {
 121                         /*
 122                          * Looks like LE Control traffic.
 123                          */
 124                         pseudo_header->atm.subtype = TRAF_ST_LANE_LE_CTRL;
 125                 } else {
 126                         /*
 127                          * XXX - Ethernet, or Token Ring?
 128                          * Assume Ethernet for now; if we see earlier
 129                          * LANE traffic, we may be able to figure out
 130                          * the traffic type from that, but there may
 131                          * still be situations where the user has to
 132                          * tell us.
 133                          */
 134                         pseudo_header->atm.subtype = TRAF_ST_LANE_802_3;
 135                 }
 136         }
 137 }