epan/dissectors/packet-clip.c

   1 /* packet-clip.c
   2  * Routines for clip packet disassembly
   3  *
   4  * Wireshark - Network traffic analyzer
   5  * By Gerald Combs <gerald@wireshark.org>
   6  *
   7  * This file created by Thierry Andry <Thierry.Andry@advalvas.be>
   8  * from nearly-the-same packet-raw.c created by Mike Hall <mlh@io.com>
   9  * Copyright 1999
  10  *
  11  * SPDX-License-Identifier: GPL-2.0-or-later
  12  */
  13
  14 #include "config.h"
  15
  16 #include <epan/packet.h>
  17 #include <epan/expert.h>
  18 #include <wiretap/wtap.h>
  19
  20 #include "packet-ip.h"
  21
  22 void proto_register_clip(void);
  23 void proto_reg_handoff_clip(void);
  24
  25 static int proto_clip;
  26
  27 static int ett_clip;
  28
  29 static expert_field ei_no_link_info;
  30
  31 static dissector_handle_t clip_handle;
  32 static dissector_handle_t ip_handle;
  33
  34 static int
  35 dissect_clip(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
  36 {
  37   proto_item *fh_item;
  38
  39   /* load the top pane info. This should be overwritten by
  40      the next protocol in the stack */
  41   col_set_str(pinfo->cinfo, COL_RES_DL_SRC, "N/A");
  42   col_set_str(pinfo->cinfo, COL_RES_DL_DST, "N/A");
  43   col_set_str(pinfo->cinfo, COL_PROTOCOL, "CLIP");
  44   col_set_str(pinfo->cinfo, COL_INFO, "Classical IP frame");
  45
  46   /* populate a tree in the second pane with the status of the link
  47      layer (ie none)
  48
  49      XXX - the Linux Classical IP code supports both LLC Encapsulation,
  50      which puts an LLC header and possibly a SNAP header in front of
  51      the network-layer header, and VC Based Multiplexing, which puts
  52      no headers in front of the network-layer header.
  53
  54      The ATM on Linux code includes a patch to "tcpdump"
  55      that compares the first few bytes of the packet with the
  56      LLC header that Classical IP frames may have and, if there's
  57      a SNAP LLC header at the beginning of the packet, it gets
  58      the packet type from that header and uses that, otherwise
  59      it treats the packet as being raw IP with no link-level
  60      header, in order to handle both of those.
  61
  62      This code, however, won't handle LLC Encapsulation.  We've
  63      not yet seen a capture taken on a machine using LLC Encapsulation,
  64      however.  If we see one, we can modify the code.
  65
  66      A future version of libpcap, however, will probably use DLT_LINUX_SLL
  67      for both of those cases, to avoid the headache of having to
  68      generate capture-filter code to handle both of those cases. */
  69   fh_item = proto_tree_add_item(tree, proto_clip, tvb, 0, 0, ENC_NA);
  70   expert_add_info(pinfo, fh_item, &ei_no_link_info);
  71
  72   call_dissector(ip_handle, tvb, pinfo, tree);
  73   return tvb_captured_length(tvb);
  74 }
  75
  76 void
  77 proto_register_clip(void)
  78 {
  79   static int *ett[] = {
  80     &ett_clip,
  81   };
  82
  83   static ei_register_info ei[] = {
  84     { &ei_no_link_info, { "clip.no_link_info", PI_PROTOCOL, PI_NOTE, "No link information available", EXPFILL }},
  85   };
  86
  87   expert_module_t* expert_clip;
  88
  89   proto_clip = proto_register_protocol("Classical IP frame", "CLIP", "clip");
  90
  91   proto_register_subtree_array(ett, array_length(ett));
  92   expert_clip = expert_register_protocol(proto_clip);
  93   expert_register_field_array(expert_clip, ei, array_length(ei));
  94
  95   clip_handle = register_dissector("clip", dissect_clip, proto_clip);
  96 }
  97
  98 void
  99 proto_reg_handoff_clip(void)
 100 {
 101
 102   /*
 103    * Get a handle for the IP dissector.
 104    */
 105   ip_handle = find_dissector_add_dependency("ip", proto_clip);
 106
 107       /* XXX - no protocol, can't be disabled */
 108   dissector_add_uint("wtap_encap", WTAP_ENCAP_LINUX_ATM_CLIP, clip_handle);
 109 }
 110
 111 /*
 112  * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 113  *
 114  * Local Variables:
 115  * c-basic-offset: 2
 116  * tab-width: 8
 117  * indent-tabs-mode: nil
 118  * End:
 119  *
 120  * ex: set shiftwidth=2 tabstop=8 expandtab:
 121  * :indentSize=2:tabSize=8:noTabs=true:
 122  */