epan/dissectors/packet-media.c

   1 /* packet-media.c
   2  * Routines for displaying an undissected media type (default case),
   3  * based on the generic "data" dissector.
   4  *
   5  * (C) Olivier Biot, 2004
   6  *
   7  * Refer to the AUTHORS file or the AUTHORS section in the man page
   8  * for contacting the author(s) of this file.
   9  *
  10  * Wireshark - Network traffic analyzer
  11  * By Gerald Combs <gerald@wireshark.org>
  12  * Copyright 1998 Gerald Combs
  13  *
  14  * SPDX-License-Identifier: GPL-2.0-or-later
  15  */
  16
  17 #include "config.h"
  18
  19 #include <epan/packet.h>
  20
  21 #include <wsutil/str_util.h>
  22
  23 #include "packet-media-type.h"
  24
  25 void proto_register_media(void);
  26
  27 static int proto_media;
  28 static int hf_media_type;
  29 static int ett_media;
  30 static heur_dissector_list_t heur_subdissector_list;
  31 static dissector_table_t media_type_suffix_table;
  32
  33 static int
  34 dissect_media(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data)
  35 {
  36     int bytes;
  37     proto_item *ti;
  38     proto_tree *media_tree = 0;
  39     media_content_info_t *content_info = (media_content_info_t *)data;
  40     heur_dtbl_entry_t *hdtbl_entry;
  41     char* suffix;
  42
  43     /* XXX - Should we move the other media_type table here, and have
  44      * dissectors always call this dissector instead of invoking the table,
  45      * similar to the Ethertype dissector?
  46      * It would make Decode As with Media Types easier.
  47      */
  48
  49     /*
  50      * RFC 6838 4.2 Naming Requirements
  51      * "Characters after last plus always specify a structured syntax suffix"
  52      */
  53     if (pinfo->match_string &&
  54         (suffix = strrchr(pinfo->match_string, '+'))) {
  55
  56         if ((bytes = dissector_try_string_new(media_type_suffix_table,
  57                 suffix + 1, tvb, pinfo, tree, true, data)) > 0) {
  58             return bytes;
  59         }
  60     }
  61
  62     if (dissector_try_heuristic(heur_subdissector_list, tvb, pinfo, tree, &hdtbl_entry, data)) {
  63         return tvb_reported_length(tvb);
  64     }
  65
  66     /* Add media type to the INFO column if it is visible */
  67     col_append_fstr(pinfo->cinfo, COL_INFO, " (%s)", (pinfo->match_string) ? pinfo->match_string : "");
  68
  69     if (tree) {
  70         if ( (bytes = tvb_reported_length(tvb)) > 0 )
  71         {
  72             ti = proto_tree_add_item(tree, proto_media, tvb, 0, -1, ENC_NA);
  73             media_tree = proto_item_add_subtree(ti, ett_media);
  74
  75             if (content_info != NULL && content_info->media_str != NULL) {
  76                 /* The media type has parameters */
  77
  78                 proto_tree_add_bytes_format_value(media_tree, hf_media_type, tvb, 0, bytes,
  79                     NULL, "%s; %s (%d byte%s)",
  80                     pinfo->match_string, content_info->media_str,
  81                     bytes, plurality(bytes, "", "s"));
  82             } else {
  83                 /* The media type has no parameters */
  84                 proto_tree_add_bytes_format_value(media_tree, hf_media_type, tvb, 0, bytes,
  85                     NULL, "%s (%d byte%s)",
  86                     pinfo->match_string ? pinfo->match_string : "",
  87                     bytes, plurality(bytes, "", "s"));
  88             }
  89         }
  90     }
  91
  92     return tvb_reported_length(tvb);
  93 }
  94
  95 void
  96 proto_register_media(void)
  97 {
  98     static hf_register_info hf[] = {
  99       { &hf_media_type,
 100         { "Media type", "media.type",
 101           FT_BYTES, BASE_NONE, NULL, 0,
 102           NULL, HFILL }},
 103     };
 104     static int *ett[] = {
 105         &ett_media
 106     };
 107
 108     proto_media = proto_register_protocol (
 109         "Media Type",   /* name */
 110         "Media",        /* short name */
 111         "media"         /* abbrev */
 112         );
 113     register_dissector("media", dissect_media, proto_media);
 114     heur_subdissector_list = register_heur_dissector_list_with_description("media", "Media type", proto_media);
 115     proto_register_field_array(proto_media, hf, array_length(hf));
 116     proto_register_subtree_array(ett, array_length(ett));
 117
 118     /*
 119      * "Media" is used to dissect something whose normal dissector
 120      * is disabled, so it cannot itself be disabled.
 121      */
 122     proto_set_cant_toggle(proto_media);
 123
 124     /*
 125      * https://www.iana.org/assignments/media-type-structured-suffix/media-type-structured-suffix.xhtml
 126      * Structured Suffixes ("zzz" in "xxx/yyy+zzz") can be used as fallback
 127      * when the exact media type is not registered.
 128      */
 129     media_type_suffix_table = register_dissector_table("media_type.suffix",
 130         "Internet media type structured suffix",
 131         proto_media, FT_STRING, STRING_CASE_INSENSITIVE);
 132 }
 133
 134 /*
 135  * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 136  *
 137  * Local variables:
 138  * c-basic-offset: 4
 139  * tab-width: 8
 140  * indent-tabs-mode: nil
 141  * End:
 142  *
 143  * vi: set shiftwidth=4 tabstop=8 expandtab:
 144  * :indentSize=4:tabSize=8:noTabs=true:
 145  */