from Jaap Keuter:

[obnox/wireshark/wip.git] / docbook / edg_src / EDG_chapter_dissection.xml

diff --git a/docbook/edg_src/EDG_chapter_dissection.xml b/docbook/edg_src/EDG_chapter_dissection.xml
index 47e70c9879a6e1ba6e6f640da5e4ec3add78850b..5e77f6a2fa1842c01b4e4a6b010fc93f21338093 100644 (file)
--- a/docbook/edg_src/EDG_chapter_dissection.xml
+++ b/docbook/edg_src/EDG_chapter_dissection.xml
@@ -743,17 +743,31 @@ dissect_foo(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
                </para>
                <para>
                To deal with such streams, we need several things to trigger
-               from. We need to know that this is packet is part of a multi-packet 
+               from. We need to know that this packet is part of a multi-packet 
                sequence. We need to know how many packets are in the sequence.
-               We need to also know when we have all the packets.
+               We also need to know when we have all the packets.
                </para>
                <para>
                For this example we'll assume there is a simple in-protocol
                signaling mechanism to give details. A flag byte that signals
-               the presence of a multi-packet and also the last packet, 
-               followed by an ID of the sequence,
-               a packet sequence number.
+               the presence of a multi-packet sequence and also the last packet, 
+               followed by an ID of the sequence and a packet sequence number.
                </para>
+                <programlisting>
+<![CDATA[
+msg_pkt ::= SEQUENCE {
+       .....
+       flags ::= SEQUENCE {
+               fragment        BOOLEAN,
+               last_fragment   BOOLEAN,
+       .....
+       }
+       msg_id  INTEGER(0..65535),
+       frag_id INTEGER(0..65565),
+       .....
+}
+]]>
+                </programlisting>
           <example><title>Reassembling fragments - Part 1</title>
    <programlisting>
    <![CDATA[
@@ -761,7 +775,7 @@ dissect_foo(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
    ...
 save_fragmented = pinfo->fragmented;
 flags = tvb_get_guint8(tvb, offset); offset++;
-if (flags & FL_FRAGMENT) { // fragmented
+if (flags & FL_FRAGMENT) { /* fragmented */
        tvbuff_t* new_tvb = NULL;
        fragment_data *frag_msg = NULL;
        guint16 msg_seqid = tvb_get_ntohs(tvb, offset); offset += 2;
@@ -769,11 +783,11 @@ if (flags & FL_FRAGMENT) { // fragmented
 
        pinfo->fragmented = TRUE;
        frag_msg = fragment_add_seq_check (tvb, offset, pinfo,
-               msg_seqid, /* guint32 ID for fragments belonging together */
+               msg_seqid, /* ID for fragments belonging together */
                msg_fragment_table, /* list of message fragments */
                msg_reassembled_table, /* list of reassembled messages */
-               msg_num, /* guint32 fragment sequence number */
-               -1, /* guint32 fragment length - to the end */
+               msg_num, /* fragment sequence number */
+               -1, /* fragment length - to the end */
                flags & FL_FRAG_LAST); /* More fragments? */
 ]]>
    </programlisting></example>
@@ -833,14 +847,15 @@ if (flags & FL_FRAGMENT) { // fragmented
                        col_append_fstr (pinfo->cinfo, COL_INFO,
                        " (Message fragment %u)", msg_num);
        }
-       if (new_tvb) { // take it all
+
+       if (new_tvb) { /* take it all */
                next_tvb = new_tvb;
+       } else { /* make a new subset */
+               next_tvb = tvb_new_subset(tvb, offset, -1, -1);
        }
-       else  // make a new subset
-               next_tvb = tvb_new_subset(next_tvb, offset, -1, -1);
 }
-else {
-       next_tvb = tvb_new_subset(next_tvb, offset, -1, -1);
+else { /* Not fragmented */
+       next_tvb = tvb_new_subset(tvb, offset, -1, -1);
 }
 
 offset = 0;
@@ -893,6 +908,19 @@ msg_init_protocol(void)
           <example><title>Reassembling fragments - Data</title>
           <programlisting>
           <![CDATA[
+...
+static int hf_msg_fragments = -1;
+static int hf_msg_fragment = -1;
+static int hf_msg_fragment_overlap = -1;
+static int hf_msg_fragment_overlap_conflicts = -1;
+static int hf_msg_fragment_multiple_tails = -1;
+static int hf_msg_fragment_too_long_fragment = -1;
+static int hf_msg_fragment_error = -1;
+static int hf_msg_reassembled_in = -1;
+...
+static gint ett_msg_fragment = -1;
+static gint ett_msg_fragments = -1;
+...
 static const fragment_items msg_frag_items = {
        /* Fragment subtrees */
        &ett_msg_fragment,
@@ -911,6 +939,9 @@ static const fragment_items msg_frag_items = {
        "Message fragments"
 };
 ...
+static hf_register_info hf[] = 
+{
+...
 {&hf_msg_fragments,
        {"Message fragments", "msg.fragments",
        FT_NONE, BASE_NONE, NULL, 0x00, NULL, HFILL } },
@@ -937,6 +968,13 @@ static const fragment_items msg_frag_items = {
 {&hf_msg_reassembled_in,
        {"Reassembled in", "msg.reassembled.in",
        FT_FRAMENUM, BASE_NONE, NULL, 0x00, NULL, HFILL } },
+...
+static gint *ett[] = 
+{
+...
+&ett_msg_fragment,
+&ett_msg_fragments
+...
 ]]>
    </programlisting></example>
    <para>