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make SNMP over UDP a new style dissector and add some heuristics to check if this is SNMP or not, 

svn path=/trunk/; revision=14339
This commit is contained in:
Ronnie Sahlberg 2005-05-10 08:49:27 +00:00
parent c64e5e59f6
commit 39e517a9b3
1 changed files with 38 additions and 3 deletions
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41
epan/dissectors/packet-snmp.c
View File

@ -1,3 +1,4 @@
/* TODO: this dissector should be upgraded to use packet-ber */
/* packet-snmp.c
* Routines for SNMP (simple network management protocol)
* Copyright (C) 1998 Didier Jorand
@ -57,6 +58,7 @@
#include "packet-ipx.h"
#include "packet-hpext.h"
#include "packet-frame.h"
#include "packet-ber.h"
#ifdef HAVE_SOME_SNMP
@ -2300,10 +2302,43 @@ dissect_smux_pdu(tvbuff_t *tvb, int offset, packet_info *pinfo,
dissect_common_pdu(tvb, offset, pinfo, smux_tree, tree, &asn1, pdu_type, start);
}
static void
static gint
dissect_snmp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
conversation_t *conversation;
int offset;
gint8 tmp_class;
gboolean tmp_pc;
gint32 tmp_tag;
guint32 tmp_length;
gboolean tmp_ind;
/*
* See if this looks like SNMP or not. if not, return 0 so
* ethereal can try som other dissector instead.
*/
/* All SNMP packets are BER encoded and consist of a SEQUENCE
* that spans the entire PDU. The first item is an INTEGER that
* has the values 0-2 (version 1-3).
* if not it is not snmp.
*/
/* SNMP starts with a SEQUENCE */
offset = get_ber_identifier(tvb, 0, &tmp_class, &tmp_pc, &tmp_tag);
if((tmp_class!=BER_CLASS_UNI)||(tmp_tag!=BER_UNI_TAG_SEQUENCE)){
return 0;
}
/* then comes a length which spans the rest of the tvb */
offset = get_ber_length(NULL, tvb, offset, &tmp_length, &tmp_ind);
if(tmp_length!=(guint32)tvb_reported_length_remaining(tvb, offset)){
return 0;
}
/* then comes an INTEGER (version)*/
offset = get_ber_identifier(tvb, offset, &tmp_class, &tmp_pc, &tmp_tag);
if((tmp_class!=BER_CLASS_UNI)||(tmp_tag!=BER_UNI_TAG_INTEGER)){
return 0;
}
/* do we need to test that version is 0 - 2 (version1-3) ? */
/*
* The first SNMP packet goes to the SNMP port; the second one
@ -2333,7 +2368,7 @@ dissect_snmp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
}
}
dissect_snmp_pdu(tvb, 0, pinfo, tree, proto_snmp, ett_snmp, FALSE);
return dissect_snmp_pdu(tvb, 0, pinfo, tree, proto_snmp, ett_snmp, FALSE);
}
static void
@ -2509,7 +2544,7 @@ proto_register_snmp(void)
"SNMP", "snmp");
proto_register_field_array(proto_snmp, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
register_dissector("snmp", dissect_snmp, proto_snmp);
new_register_dissector("snmp", dissect_snmp, proto_snmp);
/* Register configuration preferences */
snmp_module = prefs_register_protocol(proto_snmp, process_prefs);