/* Code to actually dissect the packets
*/
static void
dissect_sndcp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
guint8 addr_field, comp_field, npdu_field1, nsapi, dcomp=0, pcomp=0;
guint16 offset=0, npdu=0, segment=0, npdu_field2;
tvbuff_t *next_tvb, *npdu_tvb;
gint len;
gboolean first, more_frags, unack;
/* Set up structures needed to add the protocol subtree and manage it
*/
proto_item *ti, *address_field_item, *compression_field_item, *npdu_field_item;
proto_tree *sndcp_tree = NULL, *address_field_tree, *compression_field_tree, *npdu_field_tree;
/* Make entries in Protocol column and clear Info column on summary display
*/
col_set_str(pinfo->cinfo, COL_PROTOCOL, "SNDCP");
col_clear(pinfo->cinfo, COL_INFO);
/* create display subtree for the protocol
*/
if (tree) {
ti = proto_tree_add_item(tree, proto_sndcp, tvb, 0, -1, FALSE);
sndcp_tree = proto_item_add_subtree(ti, ett_sndcp);
}
/* get address field from next byte
*/
addr_field = tvb_get_guint8(tvb,offset);
nsapi = addr_field & 0xF;
first = addr_field & MASK_F;
more_frags = addr_field & MASK_M;
unack = addr_field & MASK_T;
/* add subtree for the address field
*/
if (tree) {
address_field_item = proto_tree_add_uint_format(sndcp_tree,hf_sndcp_nsapi,
tvb, offset,1, nsapi,
"Address field NSAPI: %d", nsapi );
address_field_tree = proto_item_add_subtree(address_field_item, ett_sndcp_address_field);
proto_tree_add_boolean(address_field_tree, hf_sndcp_x, tvb,offset,1, addr_field );
proto_tree_add_boolean(address_field_tree, hf_sndcp_f, tvb,offset,1, addr_field );
proto_tree_add_boolean(address_field_tree, hf_sndcp_t, tvb,offset,1, addr_field );
proto_tree_add_boolean(address_field_tree, hf_sndcp_m, tvb,offset,1, addr_field );
proto_tree_add_uint(address_field_tree, hf_sndcp_nsapib, tvb, offset, 1, addr_field );
}
offset++;
/* get compression pointers from next byte if this is the first segment
*/
if (first) {
comp_field = tvb_get_guint8(tvb,offset);
dcomp = comp_field & 0xF0;
pcomp = comp_field & 0x0F;
/* add subtree for the compression field
*/
if (tree) {
if (!pcomp) {
if (!dcomp) {
compression_field_item = proto_tree_add_text(sndcp_tree, tvb, offset,1, "No compression");
}
else {
compression_field_item = proto_tree_add_text(sndcp_tree, tvb, offset,1, "Data compression");
}
}
else {
if (!dcomp) {
compression_field_item = proto_tree_add_text(sndcp_tree, tvb, offset,1, "Protocol compression");
}
else {
compression_field_item = proto_tree_add_text(sndcp_tree, tvb, offset,1, "Data and Protocol compression");
}
}
compression_field_tree = proto_item_add_subtree(compression_field_item, ett_sndcp_compression_field);
proto_tree_add_uint(compression_field_tree, hf_sndcp_dcomp, tvb, offset, 1, comp_field );
proto_tree_add_uint(compression_field_tree, hf_sndcp_pcomp, tvb, offset, 1, comp_field );
}
offset++;
/* get N-PDU number from next byte for acknowledged mode (only for first segment)
*/
if (!unack) {
npdu = npdu_field1 = tvb_get_guint8(tvb,offset);
if (check_col(pinfo->cinfo, COL_INFO))
col_add_fstr(pinfo->cinfo, COL_INFO, "SN-DATA N-PDU %d", npdu_field1);
if (tree) {
npdu_field_item = proto_tree_add_text(sndcp_tree, tvb, offset,1, "Acknowledged mode, N-PDU %d", npdu_field1 );
npdu_field_tree = proto_item_add_subtree(npdu_field_item, ett_sndcp_npdu_field);
proto_tree_add_uint(npdu_field_tree, hf_sndcp_npdu1, tvb, offset, 1, npdu_field1 );
}
offset++;
}
}
/* get segment and N-PDU number from next two bytes for unacknowledged mode
*/
if (unack) {
npdu_field2 = tvb_get_ntohs(tvb, offset);
segment = (npdu_field2 & 0xF000) >> 12;
npdu = (npdu_field2 & 0x0FFF);
if (check_col(pinfo->cinfo, COL_INFO))
col_add_fstr(pinfo->cinfo, COL_INFO, "SN-UNITDATA N-PDU %d (segment %d)", npdu, segment);
if (tree) {
npdu_field_item = proto_tree_add_text(sndcp_tree, tvb, offset,2, "Unacknowledged mode, N-PDU %d (segment %d)", npdu, segment );
npdu_field_tree = proto_item_add_subtree(npdu_field_item, ett_sndcp_npdu_field);
proto_tree_add_uint(npdu_field_tree, hf_sndcp_segment, tvb, offset, 2, npdu_field2 );
proto_tree_add_uint(npdu_field_tree, hf_sndcp_npdu2, tvb, offset, 2, npdu_field2 );
}
offset += 2;
}
/* handle N-PDU data, reassemble if necessary
*/
if (first && !more_frags) {
next_tvb = tvb_new_subset_remaining (tvb, offset);
if (!dcomp && !pcomp) {
call_dissector(ip_handle, next_tvb, pinfo, tree);
}
else {
call_dissector(data_handle, next_tvb, pinfo, tree);
}
}
else {
/* Try reassembling fragments
*/
fragment_data *fd_npdu = NULL;
guint32 reassembled_in = 0;
gboolean save_fragmented = pinfo->fragmented;
len = tvb_length_remaining(tvb, offset);
if(len<=0){
return;
}
pinfo->fragmented = TRUE;
if (unack)
fd_npdu = fragment_add_seq_check(tvb, offset, pinfo, npdu,
npdu_fragment_table, sndcp_reassembled_table, segment, len, more_frags);
else
fd_npdu = fragment_add(tvb, offset, pinfo, npdu,
npdu_fragment_table, offset, len, more_frags);
npdu_tvb = process_reassembled_data(tvb, offset, pinfo,
"Reassembled N-PDU", fd_npdu, &npdu_frag_items,
NULL, sndcp_tree);
if (fd_npdu) {
/* Reassembled
*/
reassembled_in = fd_npdu->reassembled_in;
if (pinfo->fd->num == reassembled_in) {
/* Reassembled in this very packet:
* We can safely hand the tvb to the IP dissector
*/
call_dissector(ip_handle, npdu_tvb, pinfo, tree);
}
else {
/* Not reassembled in this packet
*/
if (check_col(pinfo->cinfo, COL_INFO)) {
col_append_fstr(pinfo->cinfo, COL_INFO,
" (N-PDU payload reassembled in packet %u)",
fd_npdu->reassembled_in);
}
if (tree) {
proto_tree_add_text(sndcp_tree, tvb, offset, -1, "Payload");
}
}
} else {
/* Not reassembled yet, or not reassembled at all
*/
if (check_col(pinfo->cinfo, COL_INFO)) {
if (unack)
col_append_fstr(pinfo->cinfo, COL_INFO, " (Unreassembled fragment %u)", segment);
else
col_append_str(pinfo->cinfo, COL_INFO, " (Unreassembled fragment)");
}
if (tree) {
proto_tree_add_text(sndcp_tree, tvb, offset, -1, "Payload");
}
}
/* Now reset fragmentation information in pinfo
*/
pinfo->fragmented = save_fragmented;
}
}
static int
dissect_gssapi_work(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree,
gboolean is_verifier)
{
proto_item *volatile item;
proto_tree *volatile subtree;
volatile int return_offset = 0;
gssapi_conv_info_t *volatile gss_info;
gssapi_oid_value *oidvalue;
dissector_handle_t handle;
conversation_t *conversation;
tvbuff_t *oid_tvb;
int len, start_offset, oid_start_offset;
volatile int offset;
gint8 appclass;
gboolean pc, ind_field;
gint32 tag;
guint32 len1;
const char *oid;
fragment_data *fd_head=NULL;
gssapi_frag_info_t *fi;
tvbuff_t *volatile gss_tvb=NULL;
asn1_ctx_t asn1_ctx;
void *pd_save;
start_offset=0;
offset=0;
asn1_ctx_init(&asn1_ctx, ASN1_ENC_BER, TRUE, pinfo);
/*
* We don't know whether the data is encrypted, so say it's
* not, for now. The subdissector must set gssapi_data_encrypted
* if it is.
*/
pinfo->gssapi_data_encrypted = FALSE;
/*
* We need a conversation for later
*/
conversation = find_or_create_conversation(pinfo);
gss_info = (gssapi_conv_info_t *)conversation_get_proto_data(conversation, proto_gssapi);
if (!gss_info) {
gss_info = se_new(gssapi_conv_info_t);
gss_info->oid=NULL;
gss_info->do_reassembly=FALSE;
gss_info->frags=se_tree_create_non_persistent(EMEM_TREE_TYPE_RED_BLACK, "gssapi_frags");
conversation_add_proto_data(conversation, proto_gssapi, gss_info);
}
item = proto_tree_add_item(
tree, proto_gssapi, tvb, offset, -1, ENC_NA);
subtree = proto_item_add_subtree(item, ett_gssapi);
/*
* Catch the ReportedBoundsError exception; the stuff we've been
* handed doesn't necessarily run to the end of the packet, it's
* an item inside a packet, so if it happens to be malformed (or
* we, or a dissector we call, has a bug), so that an exception
* is thrown, we want to report the error, but return and let
* our caller dissect the rest of the packet.
*
* If it gets a BoundsError, we can stop, as there's nothing more
* in the packet after our blob to see, so we just re-throw the
* exception.
*/
pd_save = pinfo->private_data;
TRY {
gss_tvb=tvb;
/* First of all, if it's the first time we see this packet
* then check whether we are in the middle of reassembly or not
*/
if( (!pinfo->fd->flags.visited)
&& (gss_info->do_reassembly)
&& (gssapi_reassembly) ){
fi=(gssapi_frag_info_t *)se_tree_lookup32(gss_info->frags, gss_info->first_frame);
if(!fi){
goto done;
}
se_tree_insert32(gss_info->frags, pinfo->fd->num, fi);
fd_head=fragment_add(&gssapi_reassembly_table,
tvb, 0, pinfo, fi->first_frame, NULL,
gss_info->frag_offset,
tvb_length(tvb), TRUE);
gss_info->frag_offset+=tvb_length(tvb);
/* we need more fragments */
if(!fd_head){
goto done;
}
/* this blob is now fully reassembled */
gss_info->do_reassembly=FALSE;
fi->reassembled_in=pinfo->fd->num;
gss_tvb=tvb_new_child_real_data(tvb, fd_head->data, fd_head->datalen, fd_head->datalen);
add_new_data_source(pinfo, gss_tvb, "Reassembled GSSAPI");
}
/* We have seen this packet before.
* Is this blob part of reassembly or a normal blob ?
*/
if( (pinfo->fd->flags.visited)
&& (gssapi_reassembly) ){
fi=(gssapi_frag_info_t *)se_tree_lookup32(gss_info->frags, pinfo->fd->num);
if(fi){
fd_head=fragment_get(&gssapi_reassembly_table,
pinfo, fi->first_frame, NULL);
if(fd_head && (fd_head->flags&FD_DEFRAGMENTED)){
if(pinfo->fd->num==fi->reassembled_in){
proto_item *frag_tree_item;
gss_tvb=tvb_new_child_real_data(tvb, fd_head->data, fd_head->datalen, fd_head->datalen);
add_new_data_source(pinfo, gss_tvb, "Reassembled GSSAPI");
show_fragment_tree(fd_head, &gssapi_frag_items, tree, pinfo, tvb, &frag_tree_item);
} else {
proto_item *it;
it=proto_tree_add_uint(tree, hf_gssapi_reassembled_in, tvb, 0, 0, fi->reassembled_in);
PROTO_ITEM_SET_GENERATED(it);
goto done;
}
}
}
}
/* Read header */
offset = get_ber_identifier(gss_tvb, offset, &appclass, &pc, &tag);
offset = get_ber_length(gss_tvb, offset, &len1, &ind_field);
if (!(appclass == BER_CLASS_APP && pc && tag == 0)) {
/* It could be NTLMSSP, with no OID. This can happen
for anything that microsoft calls 'Negotiate' or GSS-SPNEGO */
if ((tvb_length_remaining(gss_tvb, start_offset)>7) && (tvb_strneql(gss_tvb, start_offset, "NTLMSSP", 7) == 0)) {
return_offset = call_dissector(ntlmssp_handle,
tvb_new_subset_remaining(gss_tvb, start_offset),
pinfo, subtree);
goto done;
}
/* Maybe it's new NTLMSSP payload */
if ((tvb_length_remaining(gss_tvb, start_offset)>16) &&
((tvb_memeql(gss_tvb, start_offset, "\x01\x00\x00\x00", 4) == 0))) {
return_offset = call_dissector(ntlmssp_payload_handle,
tvb_new_subset_remaining(gss_tvb, start_offset),
pinfo, subtree);
pinfo->gssapi_data_encrypted = TRUE;
goto done;
}
if ((tvb_length_remaining(gss_tvb, start_offset)==16) &&
((tvb_memeql(gss_tvb, start_offset, "\x01\x00\x00\x00", 4) == 0))) {
if( is_verifier ) {
return_offset = call_dissector(ntlmssp_verf_handle,
tvb_new_subset_remaining(gss_tvb, start_offset),
pinfo, subtree);
}
else if( pinfo->gssapi_encrypted_tvb ) {
return_offset = call_dissector(ntlmssp_data_only_handle,
tvb_new_subset_remaining(pinfo->gssapi_encrypted_tvb, 0),
pinfo, subtree);
pinfo->gssapi_data_encrypted = TRUE;
}
goto done;
}
/* Maybe it's new GSSKRB5 CFX Wrapping */
if ((tvb_length_remaining(gss_tvb, start_offset)>2) &&
((tvb_memeql(gss_tvb, start_offset, "\04\x04", 2) == 0) ||
(tvb_memeql(gss_tvb, start_offset, "\05\x04", 2) == 0))) {
return_offset = call_dissector(spnego_krb5_wrap_handle,
tvb_new_subset_remaining(gss_tvb, start_offset),
pinfo, subtree);
goto done;
}
/*
* If we do not recognise an Application class,
* then we are probably dealing with an inner context
* token or a wrap token, and we should retrieve the
* gssapi_oid_value pointer from the per-frame data or,
* if there is no per-frame data (as would be the case
* the first time we dissect this frame), from the
* conversation that exists or that we created from
* pinfo (and then make it per-frame data).
* We need to make it per-frame data as there can be
* more than one GSS-API negotiation in a conversation.
*
* Note! We "cheat". Since we only need the pointer,
* we store that as the data. (That's not really
* "cheating" - the per-frame data and per-conversation
* data code doesn't care what you supply as a data
* pointer; it just treats it as an opaque pointer, it
* doesn't dereference it or free what it points to.)
*/
oidvalue = (gssapi_oid_value *)p_get_proto_data(pinfo->fd, proto_gssapi, 0);
if (!oidvalue && !pinfo->fd->flags.visited)
{
/* No handle attached to this frame, but it's the first */
/* pass, so it'd be attached to the conversation. */
oidvalue = gss_info->oid;
if (gss_info->oid)
p_add_proto_data(pinfo->fd, proto_gssapi, 0, gss_info->oid);
}
if (!oidvalue)
{
proto_tree_add_text(subtree, gss_tvb, start_offset, 0,
"Unknown header (class=%d, pc=%d, tag=%d)",
appclass, pc, tag);
return_offset = tvb_length(gss_tvb);
goto done;
} else {
tvbuff_t *oid_tvb_local;
oid_tvb_local = tvb_new_subset_remaining(gss_tvb, start_offset);
if (is_verifier)
handle = oidvalue->wrap_handle;
else
handle = oidvalue->handle;
len = call_dissector(handle, oid_tvb_local, pinfo, subtree);
if (len == 0)
return_offset = tvb_length(gss_tvb);
else
return_offset = start_offset + len;
goto done; /* We are finished here */
}
}
/* Read oid */
oid_start_offset=offset;
offset=dissect_ber_object_identifier_str(FALSE, &asn1_ctx, subtree, gss_tvb, offset, hf_gssapi_oid, &oid);
oidvalue = gssapi_lookup_oid_str(oid);
/* Check if we need reassembly of this blob.
* Only try reassembly for OIDs we recognize
* and when we have the entire tvb
*
* SMB will sometimes split one large GSSAPI blob
* across multiple SMB/SessionSetup commands.
* While we should look at the uid returned in the response
* to the first SessionSetup and use that as a key
* instead for simplicity we assume there will not be several
* such authentication at once on a single tcp session
*/
if( (!pinfo->fd->flags.visited)
&& (oidvalue)
&& (tvb_length(gss_tvb)==tvb_reported_length(gss_tvb))
&& (len1>(guint32)tvb_length_remaining(gss_tvb, oid_start_offset))
&& (gssapi_reassembly) ){
fi=se_new(gssapi_frag_info_t);
fi->first_frame=pinfo->fd->num;
fi->reassembled_in=0;
se_tree_insert32(gss_info->frags, pinfo->fd->num, fi);
fragment_add(&gssapi_reassembly_table,
gss_tvb, 0, pinfo, pinfo->fd->num, NULL,
0, tvb_length(gss_tvb), TRUE);
fragment_set_tot_len(&gssapi_reassembly_table,
pinfo, pinfo->fd->num, NULL, len1+oid_start_offset);
gss_info->do_reassembly=TRUE;
gss_info->first_frame=pinfo->fd->num;
gss_info->frag_offset=tvb_length(gss_tvb);
goto done;
}
/*
* Hand off to subdissector.
*/
if ((oidvalue == NULL) ||
!proto_is_protocol_enabled(oidvalue->proto)) {
/* No dissector for this oid */
proto_tree_add_text(subtree, gss_tvb, oid_start_offset, -1,
"Token object");
return_offset = tvb_length(gss_tvb);
goto done;
}
/* Save a pointer to the data for the OID for the
* GSSAPI protocol for this conversation.
*/
/*
* Now add the proto data ...
* but only if it is not already there.
*/
if(!gss_info->oid){
gss_info->oid=oidvalue;
}
if (is_verifier) {
handle = oidvalue->wrap_handle;
if (handle != NULL) {
oid_tvb = tvb_new_subset_remaining(gss_tvb, offset);
len = call_dissector(handle, oid_tvb, pinfo,
subtree);
if (len == 0)
return_offset = tvb_length(gss_tvb);
else
return_offset = offset + len;
} else {
proto_tree_add_text(subtree, gss_tvb, offset, -1,
"Authentication verifier");
return_offset = tvb_length(gss_tvb);
}
} else {
handle = oidvalue->handle;
if (handle != NULL) {
oid_tvb = tvb_new_subset_remaining(gss_tvb, offset);
len = call_dissector(handle, oid_tvb, pinfo,
subtree);
if (len == 0)
return_offset = tvb_length(gss_tvb);
else
return_offset = offset + len;
} else {
proto_tree_add_text(subtree, gss_tvb, offset, -1,
"Authentication credentials");
return_offset = tvb_length(gss_tvb);
}
}
done:
;
} CATCH_NONFATAL_ERRORS {
/*
* Somebody threw an exception that means that there
* was a problem dissecting the payload; that means
* that a dissector was found, so we don't need to
* dissect the payload as data or update the protocol
* or info columns.
*
* Just show the exception and then drive on to show
* the trailer, after noting that a dissector was found
* and restoring the protocol value that was in effect
* before we called the subdissector.
*
* Restore the private_data structure in case one of the
* called dissectors modified it (and, due to the exception,
* was unable to restore it).
*/
pinfo->private_data = pd_save;
show_exception(gss_tvb, pinfo, tree, EXCEPT_CODE, GET_MESSAGE);
} ENDTRY;
proto_item_set_len(item, return_offset);
return return_offset;
}
