Documentation updates

Change-Id: I6bd7fa40726fe7ffd68b9341c640874f2a0f1c7c
Reviewed-on: https://code.wireshark.org/review/314
Reviewed-by: Alexis La Goutte <alexis.lagoutte@gmail.com>
Reviewed-by: Christopher Maynard <Christopher.Maynard@gtech.com>
Reviewed-by: Evan Huus <eapache@gmail.com>

2 files changed, 15 insertions, 38 deletions

diff --git a/doc/README.dissector b/doc/README.dissector
index 59b0900b48..2bc2d638cf 100644
--- a/doc/README.dissector
+++ b/doc/README.dissector
@@ -1959,6 +1959,10 @@ The syntax for creating a new TVBUFF_SUBSET is:
 
 next_tvb = tvb_new_subset(tvb, offset, length, reported_length)
 
+or, in the common case where it should just run to the end of the packet,
+
+next_tvb = tvb_new_subset_remaining(tvb, offset)
+
 Where:
     tvb is the tvbuff that the dissector has been working on. It
     can be a tvbuff of any type.
@@ -1977,36 +1981,6 @@ Where:
     the protocol doesn't say anything about the size of its payload.
 
 
-An example from packet-ipx.c -
-
-void
-dissect_ipx(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
-{
-        tvbuff_t        *next_tvb;
-        int             reported_length, available_length;
-
-
-        /* Make the next tvbuff */
-
-/* IPX does have a length value in the header, so calculate report_length */
-   Set this to -1 if there isn't any length information in the protocol
-*/
-        reported_length = ipx_length - IPX_HEADER_LEN;
-
-/* Calculate the available data in the packet,
-   set this to -1 to use all the data in the tv_buffer
-*/
-        available_length = tvb_captured_length(tvb) - IPX_HEADER_LEN;
-
-/* Create the tvbuffer for the next dissector */
-        next_tvb = tvb_new_subset(tvb, IPX_HEADER_LEN,
-                        MIN(available_length, reported_length),
-                        reported_length);
-
-/* call the next dissector */
-    dissector_next( next_tvb, pinfo, tree);
-
-
 1.8 Editing Makefile.common and CMakeLists.txt to add your dissector.
 
 To arrange that your dissector will be built as part of Wireshark, you
diff --git a/doc/packet-PROTOABBREV.c b/doc/packet-PROTOABBREV.c
index c1aaba8d36..b1fedfec41 100644
--- a/doc/packet-PROTOABBREV.c
+++ b/doc/packet-PROTOABBREV.c
@@ -96,17 +96,20 @@ dissect_PROTOABBREV(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree,
      * For example:
      */
 
-    /* Check that there's enough data */
+    /* Check that the packet is long enough for it to belong to us */
     if (tvb_reported_length(tvb) < PROTOABBREV_MIN_LENGTH)
         return 0;
 
-    /* Fetch some values from the packet header using tvb_get_*(). If these
-     * values are not valid/possible in your protocol then return 0 to give
-     * some other dissector a chance to dissect it.
-     */
-    if ( TEST_HEURISTICS )
-         /* these values are not possible in PROTONAME */
-        return 0;
+    /* Check that there's enough data present to run the heuristics */
+    if (tvb_captured_length(tvb) > SOME_HEURISTIC_VALUE) {
+        /* Fetch some values from the packet header using tvb_get_*(). If these
+         * values are not valid/possible in your protocol then return 0 to give
+         * some other dissector a chance to dissect it.
+         */
+        if ( TEST_HEURISTICS )
+            /* these values are not possible in PROTONAME */
+            return 0;
+    }
 
     /*** COLUMN DATA ***/