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KNX/IP: Handle multiple PDUs per TCP segment / UDP datagram 

Handle multiple PDUs per TCP segment or UDP datagram. Add
preference for handling PDUs that span multiple TCP segments.
Fix nested depth handling so as not to clear COL_INFO in the
second PDU of a segment (and also make dissect_knxip have the
standard signature.) Fix #17545.
This commit is contained in:
John Thacker 2021-08-30 19:30:02 -04:00 committed by Wireshark GitLab Utility
parent e0f7940d29
commit d900777d68
1 changed files with 31 additions and 13 deletions
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44
epan/dissectors/packet-knxip.c
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@ -26,14 +26,19 @@
#include <epan/proto.h>
#include <epan/ipproto.h>
#include <epan/prefs.h>
#include <epan/proto_data.h>
#include <epan/tvbuff.h>
#include <epan/strutil.h>
#include "packet-tcp.h"
#include "packet-udp.h"
#include "packet-knxip.h"
#include "packet-knxip_decrypt.h"
#define ECDH_PUBLIC_VALUE_SIZE 32
#define KIP_HDR_LEN 6
/* The following service families are defined for the
version 1.0 KNXnet/IP implementation of the eFCP protocol
*/
@ -478,6 +483,7 @@ guint8 knxip_host_protocol;
expert_field ei_knxip_error = EI_INIT;
expert_field ei_knxip_warning = EI_INIT;
static gboolean pref_desegment = TRUE;
static const gchar* pref_key_texts[ MAX_KNX_DECRYPTION_KEYS ];
//static const gchar* authentication_code_text;
//static const gchar* password_hash_text;
@ -492,7 +498,7 @@ guint8 knx_decryption_key_count;
/* Forward declarations
*/
static void dissect_knxip( guint8 level, tvbuff_t* tvb, packet_info* pinfo, proto_tree* tree );
static gint dissect_knxip( tvbuff_t* tvb, packet_info* pinfo, proto_tree* tree, void* data _U_ );
void proto_reg_handoff_knxip( void );
void proto_register_knxip( void );
@ -2790,7 +2796,7 @@ static guint8 dissect_secure_wrapper( guint8 header_length, tvbuff_t* tvb, packe
/* Dissect embedded KIP packet */
{
tvbuff_t* tvb3 = tvb_new_subset_length( tvb2, 0, size2 );
dissect_knxip( 1, tvb3, pinfo, root );
dissect_knxip( tvb3, pinfo, root, NULL );
}
}
}
@ -3721,7 +3727,13 @@ static void dissect_knxip_data( guint8 header_length, guint8 protocol_version _U
}
}
static void dissect_knxip( guint8 level, tvbuff_t* tvb, packet_info* pinfo, proto_tree* tree )
static guint
get_knxip_pdu_len(packet_info *pinfo _U_, tvbuff_t *tvb, int offset, void *data _U_)
{
return tvb_get_ntohs( tvb, offset+4 );
}
static gint dissect_knxip( tvbuff_t* tvb, packet_info* pinfo, proto_tree* tree, void* data _U_ )
{
gint offset = 0;
guint remaining_len = tvb_captured_length( tvb );
@ -3745,6 +3757,7 @@ static void dissect_knxip( guint8 level, tvbuff_t* tvb, packet_info* pinfo, prot
gchar version_info[ 16 ];
unsigned level = p_get_proto_depth(pinfo, proto_knxip);
if( level == 0 )
{
knxip_error = 0;
@ -3755,6 +3768,7 @@ static void dissect_knxip( guint8 level, tvbuff_t* tvb, packet_info* pinfo, prot
{
col_append_str( cinfo, COL_INFO, " " );
}
p_set_proto_depth(pinfo, proto_knxip, level+1);
kip_item = proto_tree_add_item( tree, proto_knxip, tvb, offset, (remaining_len <= 0) ? 0 : -1, ENC_BIG_ENDIAN );
kip_tree = proto_item_add_subtree( kip_item, ett_kip );
@ -3795,7 +3809,7 @@ static void dissect_knxip( guint8 level, tvbuff_t* tvb, packet_info* pinfo, prot
error = 1;
header_len = (guint8) remaining_len;
}
else if( header_len != 0x06 )
else if( header_len != KIP_HDR_LEN )
{
proto_item_prepend_text( header_len_item, "? " );
expert_add_info_format( pinfo, header_len_item, KIP_ERROR, "Expected: 6 bytes" );
@ -3846,7 +3860,7 @@ static void dissect_knxip( guint8 level, tvbuff_t* tvb, packet_info* pinfo, prot
offset += 2;
if( header_len >= 6 )
if( header_len >= KIP_HDR_LEN )
{
/* 2 bytes Total Length */
total_len = tvb_get_ntohs( tvb, 4 );
@ -3907,19 +3921,21 @@ static void dissect_knxip( guint8 level, tvbuff_t* tvb, packet_info* pinfo, prot
dissect_knxip_data( header_len, protocol_version, service_id, tvb, pinfo, tree, kip_item, kip_tree );
}
}
static gint dissect_tcp_knxip( tvbuff_t* tvb, packet_info* pinfo, proto_tree* tree, void* udata _U_ )
{
knxip_host_protocol = IP_PROTO_TCP;
dissect_knxip( 0, tvb, pinfo, tree );
return tvb_captured_length( tvb );
}
static gint dissect_udp_knxip( tvbuff_t* tvb, packet_info* pinfo, proto_tree* tree, void* udata _U_ )
static gint dissect_tcp_knxip( tvbuff_t* tvb, packet_info* pinfo, proto_tree* tree, void* udata )
{
knxip_host_protocol = IP_PROTO_TCP;
tcp_dissect_pdus(tvb, pinfo, tree, pref_desegment, KIP_HDR_LEN, get_knxip_pdu_len, dissect_knxip, udata);
return tvb_captured_length( tvb );
}
static gint dissect_udp_knxip( tvbuff_t* tvb, packet_info* pinfo, proto_tree* tree, void* udata )
{
knxip_host_protocol = IP_PROTO_UDP;
dissect_knxip( 0, tvb, pinfo, tree );
udp_dissect_pdus( tvb, pinfo, tree, KIP_HDR_LEN, NULL, get_knxip_pdu_len, dissect_knxip, udata );
return tvb_captured_length( tvb );
}
@ -4058,6 +4074,8 @@ void proto_register_knxip( void )
"KNX decryption key (format: 16 bytes as hex; example: A0 A1 A2 A3 A4 A5 A6 A7 A8 A9 AA AB AC AD AE AF)",
&pref_key_texts[ x - 1 ] );
}
prefs_register_bool_preference(knxip_module, "desegment", "Reassemble KNX/IP messages spanning multiple TCP segments.", "Whether the KNX/IP dissector should reassemble messages spanning multiple TCP segments. To use this option, you must also enable \"Allow subdissectors to reassemble TCP streams\" in the TCP protocol settings.", &pref_desegment);
}
void proto_reg_handoff_knxip( void )