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/*
ettercap -- dissector BGP 4 -- TCP 179
Copyright (C) ALoR & NaGA
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
/*
*
* BPG version 4 RFC 1771
*
* 0 1 2 3
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* 0 | |
* + +
* 4 | |
* + Marker +
* 8 | |
* + +
* 12 | |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* 16 | Length | Type | Version |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* 20 | My Autonomous System | Hold Time |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* 24 | BGP Identifier |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* 28 | Opt Parm Len | |
* +-+-+-+-+-+-+-+-+ Optional Parameters |
* 32 | |
* | |
* ~ ~
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*
* 0 1
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...
* | Parm. Type | Parm. Length | Parameter Value (variable)
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...
*
*
* a) Authentication Information (Parameter Type 1):
*
* This optional parameter may be used to authenticate a BGP
* peer. The Parameter Value field contains a 1-octet
* Authentication Code followed by a variable length
* Authentication Data.
*
* 0 1 2 3 4 5 6 7 8
* +-+-+-+-+-+-+-+-+
* | Auth. Code |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | |
* | Authentication Data |
* | |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*
* Authentication Code:
*
* This 1-octet unsigned integer indicates the
* authentication mechanism being used. Whenever an
* authentication mechanism is specified for use within
* BGP, three things must be included in the
* specification:
*
* - the value of the Authentication Code which indicates
* use of the mechanism,
* - the form and meaning of the Authentication Data, and
* - the algorithm for computing values of Marker fields.
*
* Note that a separate authentication mechanism may be
* used in establishing the transport level connection.
*
* Authentication Data:
*
* The form and meaning of this field is a variable-
* length field depend on the Authentication Code.
*
*/
#include <ec.h>
#include <ec_decode.h>
#include <ec_dissect.h>
/* protos */
FUNC_DECODER(dissector_bgp);
void bgp_init(void);
/************************************************/
/*
* this function is the initializer.
* it adds the entry in the table of registered decoder
*/
void __init bgp_init(void)
{
dissect_add("bgp", APP_LAYER_TCP, 179, dissector_bgp);
}
FUNC_DECODER(dissector_bgp)
{
DECLARE_DISP_PTR_END(ptr, end);
char tmp[MAX_ASCII_ADDR_LEN];
u_char *parameters;
u_char param_length;
u_int32 i;
u_char BGP_MARKER[] = {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};
/* don't complain about unused var */
(void)end;
(void) DECODE_DATA;
(void) DECODE_DATALEN;
(void) DECODED_LEN;
/* skip packets that don't have enough data */
if (PACKET->DATA.len < 30)
return NULL;
/* not the right version (4) */
if ( ptr[19] != 4 )
return 0;
/* not an OPEN message */
if ( ptr[18] != 1 )
return 0;
/* BGP marker has to be FFFFFF... */
if ( memcmp(ptr, BGP_MARKER, 16) )
return 0;
/* no optional parameter */
if ( (param_length = ptr[28]) == 0 )
return 0;
/* skip to parameters */
parameters = ptr + 29;
if ((ptr + param_length) > end)
return 0;
DEBUG_MSG("BGP --> TCP dissector_bgp");
/* move through the param list */
for ( i = 0; i <= param_length; i += (parameters[i + 1] + 2) ) {
/* the parameter is an authentication type (1) */
if (parameters[i] == 1) {
char *str_ptr;
u_int32 j;
u_int32 length = parameters[i + 1];
DEBUG_MSG("\tDissector_BGP 4 AUTH");
PACKET->DISSECTOR.user = strdup("BGP4");
SAFE_CALLOC(PACKET->DISSECTOR.pass, length * 3 + 10, sizeof(char));
SAFE_CALLOC(PACKET->DISSECTOR.info, 32, sizeof(char));
/* Get authentication type */
snprintf(PACKET->DISSECTOR.info, 32, "AUTH TYPE [0x%02x]", parameters[i+2]);
/* Get authentication data */
if (length > 1) {
snprintf(PACKET->DISSECTOR.pass, 4, "Hex(");
str_ptr = PACKET->DISSECTOR.pass + strlen(PACKET->DISSECTOR.pass);
for (j = 0; j < (length-1); j++) {
//u_int32 k = j+3;
u_char *temp = parameters + i + j + 3;
size_t temp_len = strlen((char *)temp) + 2;
snprintf(str_ptr + (j * 3), temp_len, " %.2x", *temp);
}
strcat(str_ptr, " )");
}
DISSECT_MSG("BGP : %s:%d -> %s %s\n", ip_addr_ntoa(&PACKET->L3.dst, tmp),
ntohs(PACKET->L4.dst),
PACKET->DISSECTOR.info,
PACKET->DISSECTOR.pass);
return NULL;
}
}
return NULL;
}
/* EOF */
// vim:ts=3:expandtab
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