epan/dissectors/packet-ipars.c

   1 /* packet-ipars.c
   2  * Routines for IPARS/ALC (International Passenger Airline Reservation System/Airline Link Control) WAN protocol dissection
   3  * Copyright 2007, Fulko Hew, SITA INC Canada, Inc.
   4  *
   5  * Wireshark - Network traffic analyzer
   6  * By Gerald Combs <gerald@wireshark.org>
   7  * Copyright 1998 Gerald Combs
   8  *
   9  * SPDX-License-Identifier: GPL-2.0-or-later
  10  */
  11
  12 /* NOTE:    This should be rewritten to be more in line with how packet-uts.c is
  13  *          written so that there are filterable fields available for IPARS too.
  14  */
  15
  16 #include "config.h"
  17
  18 #include <epan/packet.h>
  19 #include <wsutil/str_util.h>
  20 void proto_register_ipars(void);
  21
  22 static int      proto_ipars;
  23 static int      ett_ipars;
  24
  25 #define S1      (0x00)
  26 #define S2      (0x20)
  27 #define GA      (0x03)
  28 #define EOMpb   (0x10)
  29 #define EOMc    (0x11)
  30 #define EOMu    (0x12)
  31 #define EOMi    (0x13)
  32
  33 #define MAX_EOM_MSG_SIZE    (24)            /* max size of an EOMx indicator string */
  34
  35 static int
  36 dissect_ipars(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
  37 {
  38     int       bytes;
  39     uint8_t   ia     = 0, ta = 0, cmd = 0, la = 0;
  40     tvbuff_t *next_tvb;
  41     int       offset = 0;
  42     char     *eom_msg;
  43     uint8_t   ipars_eomtype;
  44
  45     eom_msg    = (char *)wmem_alloc(pinfo->pool, MAX_EOM_MSG_SIZE);
  46     eom_msg[0] = 0;
  47
  48     col_clear(pinfo->cinfo, COL_INFO);
  49
  50     col_set_str(pinfo->cinfo, COL_PROTOCOL, "IPARS");
  51
  52     if (tvb_captured_length_remaining(tvb, 0) >= 2 ) {
  53         ia = tvb_get_uint8(tvb, 0) & 0x3f;
  54         ta = tvb_get_uint8(tvb, 1) & 0x3f;
  55         if (ia == S1 && ta == S2) { /* if the first two bytes are S1/S2 skip over them */
  56             offset = 2;
  57         }
  58     }
  59     if (tvb_captured_length_remaining(tvb, offset) >= 1) ia = tvb_get_uint8(tvb, offset + 0);
  60     if (tvb_captured_length_remaining(tvb, offset) >= 2) ta = tvb_get_uint8(tvb, offset + 1);
  61
  62     if (ia == 0x83 || ia == 0x43 || ia == GA) { /* if it's an FPGA or 'corresponsdance code' 'go ahead'... */
  63         if (tvb_captured_length_remaining(tvb, offset) > 2) { /* if the msg is long, it must have been a 'poll' */
  64             col_add_fstr(pinfo->cinfo, COL_INFO, "Poll IA: %2.2X", ta);
  65         } else { /* if it's short, then it was a 'no traffic' response */
  66             if (tvb_captured_length_remaining(tvb, offset) >= 2 ) {
  67                 col_add_fstr(pinfo->cinfo, COL_INFO, "GoAhead NextIA (0x%2.2X)", ta);
  68             } else {
  69                 col_set_str(pinfo->cinfo, COL_INFO, "GoAhead NextIA");
  70             }
  71         }
  72     } else { /* if it's not a 'go ahead'... it must be some kind of data message */
  73         ia &= 0x3f;
  74         ta &= 0x3f;
  75         if (ta == 0x20) {
  76             col_add_fstr(pinfo->cinfo, COL_INFO, "Reset IA: %2.2X", ia); /* the TA character was the 'reset' command */
  77         }
  78         if (tvb_captured_length_remaining(tvb, offset) >= 3) cmd = tvb_get_uint8(tvb, offset + 2) & 0x3f;   /* get the first two bytes of the data message */
  79         if (tvb_captured_length_remaining(tvb, offset) >= 4) la  = tvb_get_uint8(tvb, offset + 3) & 0x3f;
  80         if (cmd == 0x1f && la == 0x38) {
  81             col_add_fstr(pinfo->cinfo, COL_INFO, "Please Resend - IA: %2.2X TA: %2.2X", ia, ta); /* light the resend indicator */
  82         } else if (cmd == 0x2a && la == 0x05) {
  83             col_add_fstr(pinfo->cinfo, COL_INFO, "Unsolicited Msg Indicator - IA: %2.2X TA: %2.2X", ia, ta);    /* light the unsolicited msg indicator */
  84         } else {
  85             col_add_fstr(pinfo->cinfo, COL_INFO, "Data Msg - IA: %2.2X TA: %2.2X", ia, ta); /* it was a data message (display or printer */
  86         }
  87     }
  88
  89     bytes = tvb_captured_length_remaining(tvb, 0);
  90     if (bytes > 0) {
  91         proto_tree  *ipars_tree;
  92         proto_item  *ti;
  93
  94         ia = tvb_get_uint8(tvb, 0) & 0x3f;
  95
  96         ti = proto_tree_add_protocol_format(tree, proto_ipars, tvb, 0, -1, "Ipars");
  97         ipars_tree = proto_item_add_subtree(ti, ett_ipars);
  98
  99         if (ia == 0x03) {
 100             proto_tree_add_protocol_format(ipars_tree, proto_ipars, tvb, 0, 1, "GoAhead Next IA");
 101             col_set_str(pinfo->cinfo, COL_INFO, "GoAhead");
 102             return tvb_captured_length(tvb);
 103         } else if (ia != S1) {
 104             proto_tree_add_protocol_format(ipars_tree, proto_ipars, tvb,
 105                 0,
 106                 bytes, "Unknown format - Data (%d byte%s)", bytes,
 107                 plurality(bytes, "", "s"));
 108             return tvb_captured_length(tvb);
 109         }
 110         proto_tree_add_protocol_format(ipars_tree, proto_ipars, tvb, 0, 1, "S1");
 111         ia = tvb_get_uint8(tvb, 1) & 0x3f;
 112         if (ia != S2) {
 113             proto_tree_add_protocol_format(ipars_tree, proto_ipars, tvb,
 114                 0,
 115                 bytes, "Unknown format - Data (%d byte%s)", bytes,
 116                 plurality(bytes, "", "s"));
 117                 return tvb_captured_length(tvb);
 118         }
 119         proto_tree_add_protocol_format(ipars_tree, proto_ipars, tvb, 1, 1, "S2");
 120         ia = tvb_get_uint8(tvb, 2) & 0x3f;
 121         if (ia == GA) {
 122             ia = tvb_get_uint8(tvb, 3) & 0x3f;
 123             proto_tree_add_protocol_format(ipars_tree, proto_ipars, tvb, 2, 2, "GoAhead IA: %2.2X", ia);
 124             ipars_eomtype = tvb_get_uint8(tvb, 4) & 0x3f;
 125             switch (ipars_eomtype) {
 126                 case EOMc:  snprintf(eom_msg, MAX_EOM_MSG_SIZE, "EOMc");                              break;
 127                 case EOMi:  snprintf(eom_msg, MAX_EOM_MSG_SIZE, "EOMi");                              break;
 128                 case EOMu:  snprintf(eom_msg, MAX_EOM_MSG_SIZE, "EOMu");                              break;
 129                 case EOMpb: snprintf(eom_msg, MAX_EOM_MSG_SIZE, "EOMpb");                             break;
 130                 default:    snprintf(eom_msg, MAX_EOM_MSG_SIZE, "Unknown EOM type (0x%2.2X)", ia);    break;
 131             }
 132             proto_tree_add_protocol_format(ipars_tree, proto_ipars, tvb, 4, 1, "%s", eom_msg);
 133             proto_tree_add_protocol_format(ipars_tree, proto_ipars, tvb, 5, 1, "Good BCC");
 134         } else {
 135             next_tvb = tvb_new_subset_remaining(tvb, 3);
 136             proto_tree_add_protocol_format(ipars_tree, proto_ipars, next_tvb,
 137                 0,
 138                 bytes, "Data (%d byte%s)", bytes,
 139                 plurality(bytes, "", "s"));
 140             return tvb_captured_length(tvb);
 141         }
 142     }
 143     return tvb_captured_length(tvb);
 144 }
 145
 146 void
 147 proto_register_ipars(void)
 148 {
 149     static int *ett[] = {
 150         &ett_ipars,
 151     };
 152
 153     proto_ipars = proto_register_protocol("International Passenger Airline Reservation System", "IPARS", "ipars");
 154     proto_register_subtree_array(ett, array_length(ett));
 155
 156     register_dissector("ipars", dissect_ipars, proto_ipars);
 157 }
 158
 159 /*
 160  * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 161  *
 162  * Local variables:
 163  * c-basic-offset: 4
 164  * tab-width: 8
 165  * indent-tabs-mode: nil
 166  * End:
 167  *
 168  * vi: set shiftwidth=4 tabstop=8 expandtab:
 169  * :indentSize=4:tabSize=8:noTabs=true:
 170  */