Revert "Revert "create audio-specific part of the usb conversation""

This reverts commit 22e10bea0cbd2b29d6e7b82a3ead3910d71988a2.

Now that the fuzz failures are fixed, we can re-enable the
audio-specific extensions.

Change-Id: Id788e10aaa3dbf289df364f7da9ef01e24ba47f9
Reviewed-on: https://code.wireshark.org/review/3728
Reviewed-by: Martin Kaiser <wireshark@kaiser.cx>
Tested-by: Martin Kaiser <wireshark@kaiser.cx>

1 files changed, 59 insertions, 3 deletions

diff --git a/epan/dissectors/packet-usb-audio.c b/epan/dissectors/packet-usb-audio.c
index 7ce684a1bb..9bee878197 100644
--- a/epan/dissectors/packet-usb-audio.c
+++ b/epan/dissectors/packet-usb-audio.c
@@ -48,6 +48,9 @@ static int hf_ac_if_hdr_total_len = -1;
 static int hf_ac_if_hdr_bInCollection = -1;
 static int hf_ac_if_hdr_if_num = -1;
 static int hf_as_if_desc_subtype = -1;
+static int hf_as_if_gen_term_id = -1;
+static int hf_as_if_gen_delay = -1;
+static int hf_as_if_gen_format = -1;
 static int hf_as_ep_desc_subtype = -1;
 
 static reassembly_table midi_data_reassembly_table;
@@ -136,6 +139,11 @@ static const value_string as_subtype_vals[] = {
 static value_string_ext as_subtype_vals_ext =
     VALUE_STRING_EXT_INIT(as_subtype_vals);
 
+typedef struct _audio_conv_info_t {
+    /* the major version of the USB audio class specification,
+       taken from the AC header descriptor */
+    guint8 ver_major;
+} audio_conv_info_t;
 
 static int hf_sysex_msg_fragments = -1;
 static int hf_sysex_msg_fragment = -1;
@@ -294,13 +302,14 @@ dissect_usb_midi_event(tvbuff_t *tvb, packet_info *pinfo,
    body's length) */
 static gint
 dissect_ac_if_hdr_body(tvbuff_t *tvb, gint offset, packet_info *pinfo _U_,
-        proto_tree *tree, usb_conv_info_t *usb_conv_info _U_)
+        proto_tree *tree, usb_conv_info_t *usb_conv_info)
 {
     gint     offset_start;
     guint16  bcdADC;
     guint8   ver_major;
     double   ver;
     guint8   if_in_collection, i;
+    audio_conv_info_t *audio_conv_info;
 
 
     offset_start = offset;
@@ -311,8 +320,14 @@ dissect_ac_if_hdr_body(tvbuff_t *tvb, gint offset, packet_info *pinfo _U_,
 
     proto_tree_add_double_format_value(tree, hf_ac_if_hdr_ver,
             tvb, offset, 2, ver, "%2.2f", ver);
-    /* XXX - create an audio-specific conversation struct,
-             store the major version there */
+    audio_conv_info = (audio_conv_info_t *)usb_conv_info->class_data;
+    if(!audio_conv_info) {
+        audio_conv_info = wmem_new(wmem_file_scope(), audio_conv_info_t);
+        usb_conv_info->class_data = audio_conv_info;
+        /* XXX - set reasonable default values for all components
+           that are not filled in by this function */
+    }
+    audio_conv_info->ver_major = ver_major;
     offset += 2;
 
     /* version 1 refers to the Basic Audio Device specification,
@@ -338,6 +353,36 @@ dissect_ac_if_hdr_body(tvbuff_t *tvb, gint offset, packet_info *pinfo _U_,
 
 
 static gint
+dissect_as_if_general_body(tvbuff_t *tvb, gint offset, packet_info *pinfo _U_,
+        proto_tree *tree, usb_conv_info_t *usb_conv_info)
+{
+    audio_conv_info_t *audio_conv_info;
+    gint               offset_start;
+
+    /* the caller has already checked that usb_conv_info!=NULL */
+    audio_conv_info = (audio_conv_info_t *)usb_conv_info->class_data;
+    if (!audio_conv_info)
+        return 0;
+
+    offset_start = offset;
+
+    if (audio_conv_info->ver_major==1) {
+        proto_tree_add_item(tree, hf_as_if_gen_term_id,
+                tvb, offset, 1, ENC_LITTLE_ENDIAN);
+        offset++;
+        proto_tree_add_item(tree, hf_as_if_gen_delay,
+                tvb, offset, 1, ENC_LITTLE_ENDIAN);
+        offset++;
+        proto_tree_add_item(tree, hf_as_if_gen_format,
+                tvb, offset, 2, ENC_LITTLE_ENDIAN);
+        offset += 2;
+    }
+
+    return offset-offset_start;
+}
+
+
+static gint
 dissect_usb_audio_descriptor(tvbuff_t *tvb, packet_info *pinfo,
         proto_tree *tree, void *data)
 {
@@ -410,6 +455,8 @@ dissect_usb_audio_descriptor(tvbuff_t *tvb, packet_info *pinfo,
 
         switch(desc_subtype) {
             case AS_SUBTYPE_GENERAL:
+                dissect_as_if_general_body(tvb, offset, pinfo,
+                        desc_tree, usb_conv_info);
                 break;
             default:
                 break;
@@ -521,6 +568,15 @@ proto_register_usb_audio(void)
         { &hf_as_if_desc_subtype,
             { "Subtype", "usbaudio.as_if_subtype", FT_UINT8, BASE_HEX|BASE_EXT_STRING,
                 &as_subtype_vals_ext, 0x00, "bDescriptorSubtype", HFILL }},
+        { &hf_as_if_gen_term_id,
+            { "Terminal ID", "usbaudio.as_if_gen.bTerminalLink",
+              FT_UINT8, BASE_DEC, NULL, 0x00, "bTerminalLink", HFILL }},
+        { &hf_as_if_gen_delay,
+            { "Interface delay in frames", "usbaudio.as_if_gen.bDelay",
+              FT_UINT8, BASE_DEC, NULL, 0x00, "bDelay", HFILL }},
+        { &hf_as_if_gen_format,
+            { "Format", "usbaudio.as_if_gen.wFormatTag",
+              FT_UINT16, BASE_HEX, NULL, 0x00, "wFormatTag", HFILL }},
         { &hf_as_ep_desc_subtype,
             { "Subtype", "usbaudio.as_ep_subtype", FT_UINT8,
                 BASE_HEX, NULL, 0x00, "bDescriptorSubtype", HFILL }},