/**
* dissect_messageid is a utility function which
* calculates the ID of the message.
*
* @see dissect_packetid()
* @see dissect_reliable_message_index_base()
* @see dissect_content_length()
* @see dissect_reliable_message_number()
* @see dissect_payload()
* @param buffer the buffer to the data
* @param offset the offset where to start reading the data
* @param tree the parent tree where the dissected data is going to be inserted
* @return int returns the messageid
*
*/
static int
dissect_messageid(tvbuff_t *buffer, int *offset, proto_tree *tree, packet_info *pinfo, gboolean separator)
{
gint messageid_length;
guint8 messageid;
gboolean col_write;
messageid = tvb_get_guint8(buffer, (*offset));
switch(messageid)
{
case DISCONNECT:
case DISCONNECTACK:
case CONNECTSYN:
case CONNECTSYNACK:
case CONNECTACK:
messageid_length = 4;
break;
default:
messageid_length = 1;
break;
}
proto_tree_add_uint_format_value(tree, hf_knet_messageid, buffer, *offset, messageid_length, messageid,
"%s (%d)", val_to_str_const(messageid, packettypenames, "AppData or Malformed Message ID"), messageid);
/* XXX - TCP reassembly disables writing columns which prevents populating COL_INFO if multiple KNET messages
appear in a single packet that needed to be reassembled.
Force making columns writable.
*/
if (separator)
{
col_write = col_get_writable(pinfo->cinfo);
col_set_writable(pinfo->cinfo, TRUE);
col_append_sep_fstr(pinfo->cinfo, COL_INFO, ", ", "%s (%d)", val_to_str_const(messageid, packettypenames, "AppData"), messageid);
col_set_writable(pinfo->cinfo, col_write);
}
else
{
col_append_fstr(pinfo->cinfo, COL_INFO, "%s (%d)", val_to_str_const(messageid, packettypenames, "AppData"), messageid);
}
*offset += messageid_length;
return messageid;
}
/* Parse Short Message, only if UDH present
* (otherwise this function is not called).
* Call WSP dissector if port matches WSP traffic.
*/
static void
parse_gsm_sms_ud_message(proto_tree *sm_tree, tvbuff_t *tvb, packet_info *pinfo,
proto_tree *top_tree)
{
tvbuff_t *sm_tvb = NULL;
proto_item *subtree, *tree;
guint8 udh_len, udh, len;
guint sm_len = tvb_reported_length (tvb);
guint sm_data_len;
guint32 i = 0;
/* Multiple Messages UDH */
gboolean is_fragmented = FALSE;
fragment_data *fd_sm = NULL;
guint16 sm_id = 0, frags = 0, frag = 0;
gboolean save_fragmented = FALSE, try_gsm_sms_ud_reassemble = FALSE;
/* SMS Message reassembly */
gboolean reassembled = FALSE;
guint32 reassembled_in = 0;
/* Port Number UDH */
guint16 p_src = 0, p_dst = 0;
gboolean ports_available = FALSE;
udh_len = tvb_get_guint8(tvb, i++);
tree = proto_tree_add_uint(sm_tree, hf_gsm_sms_udh_length, tvb, 0, 1, udh_len);
tree = proto_item_add_subtree(tree, ett_udh);
while (i < udh_len) {
udh = tvb_get_guint8(tvb, i++);
len = tvb_get_guint8(tvb, i++);
subtree = proto_tree_add_uint(tree, hf_gsm_sms_udh_iei,
tvb, i-2, 2+len, udh);
switch (udh) {
case 0x00: /* Multiple messages - 8-bit message ID */
if (len == 3) {
sm_id = tvb_get_guint8(tvb, i++);
frags = tvb_get_guint8(tvb, i++);
frag = tvb_get_guint8(tvb, i++);
if (frags > 1)
is_fragmented = TRUE;
proto_item_append_text(subtree,
": message %u, part %u of %u", sm_id, frag, frags);
subtree = proto_item_add_subtree(subtree,
ett_udh_ie);
proto_tree_add_uint (subtree,
hf_gsm_sms_udh_multiple_messages_msg_id,
tvb, i-3, 1, sm_id);
proto_tree_add_uint (subtree,
hf_gsm_sms_udh_multiple_messages_msg_parts,
tvb, i-2, 1, frags);
proto_tree_add_uint (subtree,
hf_gsm_sms_udh_multiple_messages_msg_part,
tvb, i-1, 1, frag);
} else {
proto_item_append_text(subtree, " - Invalid format!");
i += len;
}
break;
case 0x08: /* Multiple messages - 16-bit message ID */
if (len == 4) {
sm_id = tvb_get_ntohs(tvb, i); i += 2;
frags = tvb_get_guint8(tvb, i++);
frag = tvb_get_guint8(tvb, i++);
if (frags > 1)
is_fragmented = TRUE;
proto_item_append_text(subtree,
": message %u, part %u of %u", sm_id, frag, frags);
subtree = proto_item_add_subtree(subtree,
ett_udh_ie);
proto_tree_add_uint (subtree,
hf_gsm_sms_udh_multiple_messages_msg_id,
tvb, i-4, 2, sm_id);
proto_tree_add_uint (subtree,
hf_gsm_sms_udh_multiple_messages_msg_parts,
tvb, i-2, 1, frags);
proto_tree_add_uint (subtree,
hf_gsm_sms_udh_multiple_messages_msg_part,
tvb, i-1, 1, frag);
} else {
proto_item_append_text(subtree, " - Invalid format!");
i += len;
}
break;
case 0x04: /* Port Number UDH - 8-bit address */
if (len == 2) { /* Port fields */
p_dst = tvb_get_guint8(tvb, i++);
p_src = tvb_get_guint8(tvb, i++);
proto_item_append_text(subtree,
": source port %u, destination port %u",
p_src, p_dst);
subtree = proto_item_add_subtree(subtree, ett_udh_ie);
proto_tree_add_uint (subtree, hf_gsm_sms_udh_ports_dst,
tvb, i-2, 1, p_dst);
proto_tree_add_uint (subtree, hf_gsm_sms_udh_ports_src,
tvb, i-1, 1, p_src);
ports_available = TRUE;
} else {
proto_item_append_text(subtree, " - Invalid format!");
i += len;
}
break;
case 0x05: /* Port Number UDH - 16-bit address */
if (len == 4) { /* Port fields */
p_dst = tvb_get_ntohs(tvb, i); i += 2;
p_src = tvb_get_ntohs(tvb, i); i += 2;
proto_item_append_text(subtree,
": source port %u, destination port %u",
p_src, p_dst);
subtree = proto_item_add_subtree(subtree, ett_udh_ie);
proto_tree_add_uint (subtree, hf_gsm_sms_udh_ports_dst,
tvb, i-4, 2, p_dst);
proto_tree_add_uint (subtree, hf_gsm_sms_udh_ports_src,
tvb, i-2, 2, p_src);
ports_available = TRUE;
} else {
proto_item_append_text(subtree, " - Invalid format!");
i += len;
}
break;
default:
i += len;
break;
}
}
if (tvb_reported_length_remaining(tvb, i) <= 0)
return; /* No more data */
/*
* XXX - where does the "1" come from? If it weren't there,
* "sm_data_len" would, I think, be the same as
* "tvb_reported_length_remaining(tvb, i)".
*
* I think that the above check ensures that "sm_len" won't
* be less than or equal to "udh_len", so it ensures that
* "sm_len" won't be less than "1 + udh_len", so we don't
* have to worry about "sm_data_len" being negative.
*/
sm_data_len = sm_len - (1 + udh_len);
if (sm_data_len == 0)
return; /* no more data */
/*
* Try reassembling the packets.
* XXX - fragment numbers are 1-origin, but the fragment number
* field could be 0.
* Should we flag a fragmented message with a fragment number field
* of 0?
* What if the fragment count is 0? Should we flag that as well?
*/
if ( is_fragmented && frag != 0 && frags != 0 &&
tvb_bytes_exist (tvb, i, sm_data_len) ) {
try_gsm_sms_ud_reassemble = TRUE;
save_fragmented = pinfo->fragmented;
pinfo->fragmented = TRUE;
fd_sm = fragment_add_seq_check (tvb, i, pinfo,
sm_id, /* guint32 ID for fragments belonging together */
sm_fragment_table, /* list of message fragments */
sm_reassembled_table, /* list of reassembled messages */
frag-1, /* guint32 fragment sequence number */
sm_data_len, /* guint32 fragment length */
(frag != frags)); /* More fragments? */
if (fd_sm) {
reassembled = TRUE;
reassembled_in = fd_sm->reassembled_in;
}
sm_tvb = process_reassembled_data(tvb, i, pinfo,
"Reassembled Short Message", fd_sm, &sm_frag_items,
NULL, sm_tree);
if (reassembled) { /* Reassembled */
col_append_str (pinfo->cinfo, COL_INFO,
" (Short Message Reassembled)");
} else {
/* Not last packet of reassembled Short Message */
col_append_fstr (pinfo->cinfo, COL_INFO,
" (Short Message fragment %u of %u)", frag, frags);
}
} /* Else: not fragmented */
if (! sm_tvb) /* One single Short Message, or not reassembled */
sm_tvb = tvb_new_subset_remaining (tvb, i);
/* Try calling a subdissector */
if (sm_tvb) {
if ((reassembled && pinfo->fd->num == reassembled_in)
|| frag==0 || (frag==1 && try_dissect_1st_frag)) {
/* Try calling a subdissector only if:
* - the Short Message is reassembled in this very packet,
* - the Short Message consists of only one "fragment",
* - the preference "Always Try Dissection for 1st SM fragment"
* is switched on, and this is the SM's 1st fragment. */
if ( ports_available ) {
gboolean disallow_write = FALSE; /* TRUE if we changed writability
of the columns of the summary */
if ( prevent_subdissectors_changing_columns && col_get_writable(pinfo->cinfo) ) {
disallow_write = TRUE;
col_set_writable(pinfo->cinfo, FALSE);
}
if ( port_number_udh_means_wsp ) {
call_dissector (wsp_handle, sm_tvb, pinfo, top_tree);
} else {
if (! dissector_try_port(gsm_sms_dissector_table, p_src,
sm_tvb, pinfo, top_tree)) {
if (! dissector_try_port(gsm_sms_dissector_table, p_dst,
sm_tvb, pinfo, top_tree)) {
if (sm_tree) { /* Only display if needed */
proto_tree_add_text (sm_tree, sm_tvb, 0, -1,
"Short Message body");
}
}
}
}
if ( disallow_write )
col_set_writable(pinfo->cinfo, TRUE);
} else { /* No ports IE */
proto_tree_add_text (sm_tree, sm_tvb, 0, -1,
"Short Message body");
}
} else {
/* The packet is not reassembled,
* or it is reassembled in another packet */
proto_tree_add_text (sm_tree, sm_tvb, 0, -1,
"Unreassembled Short Message fragment %u of %u",
frag, frags);
}
}
if (try_gsm_sms_ud_reassemble) /* Clean up defragmentation */
pinfo->fragmented = save_fragmented;
return;
}
