Hej,
I´ve written a dissector for a multiplexer-protocol. The payload of these multiplexer packets could be PPP packets, most of these packets will be splitted to several mux packets.
I´ve tried to reassemble these PPP packets (reading that article 9.4.1. How to reassemble split UDP packets), but it doesn´t work...
To get the necessary data I´ve added a new header to my multiplexer packet so I have the information about the fragments.
What am I doing wrong?
//Check if there is a PPP packet inside
if (sizeMuxPPPHeader > 0){
guint16 tmpOffset = 1;
guint16 tmpOffsetBegin = 1;
guint16 tmpOffsetEnd = 1;
//There could be more than one PPP packet in the multiplexer packet
for (i = 0; i < sizeMuxPPPHeader/7; i++){
tvbuff_t* new_tvb = NULL;
fragment_data *frag_msg = NULL;
guint16 msg_seqid; //ID of the message
guint16 msg_num; //Sequence number
guint8 msg_start; //Start position of PPP packet
guint8 msg_end; //End of PPP packet
guint8 msg_flag; //Flag of packet
tmpOffset = i * tmpOffset+1;
//Get the necessary data
msg_seqid = tvb_get_ntohs(tvb, tmpOffset); tmpOffset += 2;
msg_num = tvb_get_ntohs(tvb, tmpOffset); tmpOffset += 2;
msg_start = tvb_get_guint8(tvb, tmpOffset); tmpOffset += 1;
msg_end = tvb_get_guint8(tvb, tmpOffset); tmpOffset += 1;
msg_flag = tvb_get_guint8(tvb, tmpOffset); tmpOffset += 1;
//Calculate the offset
tmpOffsetBegin = sizeMuxPPPHeader + 1 + msg_start;
tmpOffsetEnd = sizeMuxPPPHeader + 1 + msg_end;
pinfo->fragmented = TRUE;
frag_msg = fragment_add_seq_check(tvb, tmpOffsetBegin, pinfo,
msg_seqid, /* ID for fragments belonging together */
msg_fragment_table, /* list of message fragments */
msg_reassembled_table, /* list of reassembled messages */
msg_num, /* fragment sequence number */
tmpOffsetEnd, /* fragment length - to the end */
msg_flag); /* More fragments? */
new_tvb = process_reassembled_data(tvb, tmpOffsetBegin, pinfo,
"Reassembled Message", frag_msg, &msg_frag_items,
NULL, mux27010_tree);
if (frag_msg) { /* Reassembled */
if (check_col(pinfo->cinfo, COL_INFO))
col_append_str(pinfo->cinfo, COL_INFO,
" (Message Reassembled)");
} else { /* Not last packet of reassembled Short Message */
if (check_col(pinfo->cinfo, COL_INFO))
col_append_fstr(pinfo->cinfo, COL_INFO,
" (Message fragment %u)", msg_num);
}
if (new_tvb) { /* take it all */
next_tvb = new_tvb;
} else { /* make a new subset */
next_tvb = tvb_new_subset(tvb, tmpOffsetBegin, -1, -1);
}
Regards, Chris
