Title: Help with desegmentation issue
I have a dissector that uses tcp_dissect_pdus that does not seem to be doing the job. Please help.
I have a dump that contains 4 TCP packets that are all related to the same message (a total of 4428 bytes).
The first 3 packets are a length of 1460 bytes and the last 48 bytes => 1460 * 3 + 48 = 4428
When dissection takes place, the desegmentation does not seem to properly occur.
Under the TCP portion of the dissection it properly says:
[PDU Size: 4428]
But the data available for dissection is only the size of the first packet (1460)
What I am doing wrong? Thanks for any help.
Below are excerpts from my dissector:
#define FRAME_HEADER_LEN 4
static void
dissect_myproto_message(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
/* Check that there's enough data */
total_len = tvb_length(tvb);
printf("Total_len = %u\n", total_len); // THIS prints 1460
.
// Dissect my data
.
}
static guint
get_myproto_message_len(packet_info *pinfo, tvbuff_t *tvb, int offset)
{
guint length = 0;
// myproto message (length is 2 bytes starting at offset 0 * 4)
length = (guint) ( tvb_get_ntohs( tvb, offset ) * 4 ); // Get the length
printf("TOTAL of mesage = %u\n", length); // This prints 4428
return length;
}
/* Code to actually dissect the packets */
static void
dissect_myproto(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
tcp_dissect_pdus(tvb, pinfo, tree, TRUE, FRAME_HEADER_LEN,
get_myproto_message_len, dissect_myproto_message);
}
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