Catch exceptions thrown while dissecting the GSS-API stuff, so that we
don't abort dissection of the entire packet if we get a ReportedBoundsError while dissecting an authentication blob - the authentication blob might be in the middle of a packet, and if it's too short, that doesn't mean that the stuff *after* it shouldn't be dissected. svn path=/trunk/; revision=6160
This commit is contained in:
Guy Harris
parent
f9a17c0db3
commit
e9e4881caa
288
packet-gssapi.c
288
packet-gssapi.c
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@ -2,7 +2,7 @@
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* Dissector for GSS-API tokens as described in rfc2078, section 3.1
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* Copyright 2002, Tim Potter <tpot@samba.org>
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*
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* $Id: packet-gssapi.c,v 1.11 2002/08/29 17:58:22 sharpe Exp $
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* $Id: packet-gssapi.c,v 1.12 2002/08/31 20:09:26 guy Exp $
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*
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* Ethereal - Network traffic analyzer
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* By Gerald Combs <gerald@ethereal.com>
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@ -37,6 +37,7 @@
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#include "asn1.h"
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#include "format-oid.h"
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#include "packet-gssapi.h"
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#include "packet-frame.h"
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#include "epan/conversation.h"
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static int proto_gssapi = -1;
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@ -120,10 +121,10 @@ dissect_gssapi(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
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int len;
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unsigned int i;
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gchar *p;
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dissector_handle_t handle = NULL;
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volatile dissector_handle_t handle = NULL;
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/* proto_item *sub_item;
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proto_tree *oid_subtree;*/
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conversation_t *conversation;
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conversation_t *volatile conversation;
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/*
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* We need this later, so lets get it now ...
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@ -138,150 +139,169 @@ dissect_gssapi(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
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subtree = proto_item_add_subtree(item, ett_gssapi);
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/* Read header */
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asn1_open(&hnd, tvb, offset);
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ret = asn1_header_decode(&hnd, &cls, &con, &tag, &def, &len1);
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if (ret != ASN1_ERR_NOERROR) {
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dissect_parse_error(tvb, offset, pinfo, subtree,
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"GSS-API header", ret);
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goto done;
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}
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if (!(cls == ASN1_APL && con == ASN1_CON && tag == 0)) {
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/*
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* If we do not recognise an Application class, then
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* then we are probably dealing with an inner context
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* token, and we should retrieve the dissector from
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* the conversation that exists or we created from pinfo
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*
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* Note! We cheat. Since we only need the dissector handle,
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* We store that as the conversation data ... after type casting.
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*/
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if (conversation &&
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!(handle = conversation_get_proto_data(conversation,
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proto_gssapi))){
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proto_tree_add_text(
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subtree, tvb, offset, 0,
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"Unknown header (cls=%d, con=%d, tag=%d)",
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cls, con, tag);
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goto done;
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}
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else
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{
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tvbuff_t *oid_tvb;
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/* Naughty ... no way to reset the offset */
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/* Account for the fact we have consumed part if the ASN.1 */
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/* and we want to get it back */
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hnd.offset = offset;
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oid_tvb = tvb_new_subset(tvb, offset, -1, -1);
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call_dissector(handle, oid_tvb, pinfo, subtree);
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}
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}
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offset = hnd.offset;
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/* Read oid */
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ret = asn1_oid_decode(&hnd, &oid, &oid_len, &nbytes);
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if (ret != ASN1_ERR_NOERROR) {
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dissect_parse_error(tvb, offset, pinfo, subtree,
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"GSS-API token", ret);
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goto done;
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}
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oid_string = format_oid(oid, oid_len);
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proto_tree_add_text(subtree, tvb, offset, nbytes, "OID: %s",
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oid_string);
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offset += nbytes;
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g_free(oid_string);
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/*
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* Hand off to subdissector.
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* We can't use "oid_string", as it might contain an
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* interpretation of the OID after the raw string, so
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* we generate our own string for it.
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* Catch the ReportedBoundsError exception; the stuff we've been
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* handed doesn't necessarily run to the end of the packet, it's
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* an item inside a packet, so if it happens to be malformed (or
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* we, or a dissector we call, has a bug), so that an exception
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* is thrown, we want to report the error, but return and let
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* our caller dissect the rest of the packet.
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*
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* If it gets a BoundsError, we can stop, as there's nothing more
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* in the packet after our blob to see, so we just re-throw the
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* exception.
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*/
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oid_string = g_malloc(oid_len * 22 + 1);
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p = oid_string;
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len = sprintf(p, "%lu", (unsigned long)oid[0]);
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p += len;
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for (i = 1; i < oid_len;i++) {
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len = sprintf(p, ".%lu", (unsigned long)oid[i]);
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p += len;
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}
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TRY {
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/* Read header */
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if (((value = g_hash_table_lookup(gssapi_oids, oid_string)) == NULL) ||
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!proto_is_protocol_enabled(value->proto)) {
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asn1_open(&hnd, tvb, offset);
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ret = asn1_header_decode(&hnd, &cls, &con, &tag, &def, &len1);
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if (ret != ASN1_ERR_NOERROR) {
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dissect_parse_error(tvb, offset, pinfo, subtree,
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"GSS-API header", ret);
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goto done;
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}
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if (!(cls == ASN1_APL && con == ASN1_CON && tag == 0)) {
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/*
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* If we do not recognise an Application class, then
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* then we are probably dealing with an inner context
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* token, and we should retrieve the dissector from
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* the conversation that exists or we created from pinfo
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*
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* Note! We cheat. Since we only need the dissector handle,
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* We store that as the conversation data ... after type
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* casting.
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*/
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if (conversation &&
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!(handle = conversation_get_proto_data(conversation,
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proto_gssapi))){
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proto_tree_add_text(
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subtree, tvb, offset, 0,
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"Unknown header (cls=%d, con=%d, tag=%d)",
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cls, con, tag);
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goto done;
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}
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else
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{
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tvbuff_t *oid_tvb;
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/* Naughty ... no way to reset the offset */
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/* Account for the fact we have consumed part of the */
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/* ASN.1 and we want to get it back */
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hnd.offset = offset;
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oid_tvb = tvb_new_subset(tvb, offset, -1, -1);
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call_dissector(handle, oid_tvb, pinfo, subtree);
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}
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}
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offset = hnd.offset;
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/* Read oid */
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ret = asn1_oid_decode(&hnd, &oid, &oid_len, &nbytes);
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if (ret != ASN1_ERR_NOERROR) {
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dissect_parse_error(tvb, offset, pinfo, subtree,
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"GSS-API token", ret);
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goto done;
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}
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oid_string = format_oid(oid, oid_len);
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proto_tree_add_text(subtree, tvb, offset, nbytes, "OID: %s",
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oid_string);
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offset += nbytes;
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g_free(oid_string);
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/* No dissector for this oid */
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proto_tree_add_text(
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subtree, tvb, offset,
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tvb_length_remaining(tvb, offset), "Token object");
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goto done;
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}
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g_free(oid_string);
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/*
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* This is not needed, as the sub-dissector adds a tree
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sub_item = proto_tree_add_item(subtree, value->proto, tvb, offset,
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-1, FALSE);
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oid_subtree = proto_item_add_subtree(sub_item, value->ett);
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*/
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handle = find_dissector(value->name);
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if (handle) {
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tvbuff_t *oid_tvb;
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/*
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* Here we should create a conversation if needed and
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* save the OID and dissector handle in it for the
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* GSSAPI protocol.
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/*
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* Hand off to subdissector.
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* We can't use "oid_string", as it might contain an
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* interpretation of the OID after the raw string, so
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* we generate our own string for it.
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*/
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if (!conversation) { /* Create one */
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conversation = conversation_new(&pinfo->src, &pinfo->dst,
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pinfo->ptype,
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pinfo->srcport,
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pinfo->destport, 0);
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oid_string = g_malloc(oid_len * 22 + 1);
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p = oid_string;
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len = sprintf(p, "%lu", (unsigned long)oid[0]);
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p += len;
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for (i = 1; i < oid_len;i++) {
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len = sprintf(p, ".%lu", (unsigned long)oid[i]);
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p += len;
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}
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if (((value = g_hash_table_lookup(gssapi_oids, oid_string)) == NULL) ||
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!proto_is_protocol_enabled(value->proto)) {
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g_free(oid_string);
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/* No dissector for this oid */
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proto_tree_add_text(subtree, tvb, offset, -1,
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"Token object");
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goto done;
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}
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g_free(oid_string);
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/*
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* Now add the proto data ...
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* but only if it is not already there.
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*/
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* This is not needed, as the sub-dissector adds a tree
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sub_item = proto_tree_add_item(subtree, value->proto, tvb,
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offset, -1, FALSE);
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oid_subtree = proto_item_add_subtree(sub_item, value->ett);
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*/
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handle = find_dissector(value->name);
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if (handle) {
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tvbuff_t *oid_tvb;
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/*
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* Here we should create a conversation if needed and
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* save the OID and dissector handle in it for the
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* GSSAPI protocol.
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*/
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if (!conversation) { /* Create one */
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conversation = conversation_new(&pinfo->src,
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&pinfo->dst,
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pinfo->ptype,
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pinfo->srcport,
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pinfo->destport, 0);
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}
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/*
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* Now add the proto data ...
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* but only if it is not already there.
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*/
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if (!conversation_get_proto_data(conversation,
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proto_gssapi)) {
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conversation_add_proto_data(conversation,
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proto_gssapi, handle);
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}
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oid_tvb = tvb_new_subset(tvb, offset, -1, -1);
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call_dissector(handle, oid_tvb, pinfo, subtree);
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}
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else { /* FIXME, do something if handle not found */
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if (!conversation_get_proto_data(conversation, proto_gssapi)) {
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conversation_add_proto_data(conversation, proto_gssapi,
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handle);
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}
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oid_tvb = tvb_new_subset(tvb, offset, -1, -1);
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call_dissector(handle, oid_tvb, pinfo, subtree);
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}
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else { /* FIXME, do something if handle not found */
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}
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done:
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asn1_close(&hnd, &offset);
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done:
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asn1_close(&hnd, &offset);
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} CATCH(BoundsError) {
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RETHROW;
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} CATCH(ReportedBoundsError) {
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show_reported_bounds_error(tvb, pinfo, tree);
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} ENDTRY;
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}
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void
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