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/*
* snmp.c
*
* Copyright (C) 2009-2011 by ipoque GmbH
* Copyright (C) 2011-15 - ntop.org
*
* This file is part of nDPI, an open source deep packet inspection
* library based on the OpenDPI and PACE technology by ipoque GmbH
*
* nDPI is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* nDPI 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with nDPI. If not, see <http://www.gnu.org/licenses/>.
*
*/
#include "ndpi_protocol_ids.h"
#ifdef NDPI_PROTOCOL_SNMP
#define NDPI_CURRENT_PROTO NDPI_PROTOCOL_SNMP
#include "ndpi_api.h"
static void ndpi_int_snmp_add_connection(struct ndpi_detection_module_struct
*ndpi_struct, struct ndpi_flow_struct *flow)
{
ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_SNMP, NDPI_PROTOCOL_UNKNOWN);
}
void ndpi_search_snmp(struct ndpi_detection_module_struct *ndpi_struct, struct ndpi_flow_struct *flow)
{
struct ndpi_packet_struct *packet = &flow->packet;
NDPI_LOG_DBG(ndpi_struct, "search SNMP\n");
if (packet->payload_packet_len > 32 && packet->payload[0] == 0x30) {
int offset;
u_int16_t u16;
switch (packet->payload[1]) {
case 0x81:
offset = 3;
break;
case 0x82:
offset = 4;
break;
default:
if (packet->payload[1] > 0x82) {
NDPI_LOG_DBG2(ndpi_struct, "SNMP excluded, second byte is > 0x82\n");
goto excl;
}
offset = 2;
}
u16 = ntohs(get_u_int16_t(packet->payload, offset));
if((u16 != 0x0201) && (u16 != 0x0204)) {
NDPI_LOG_DBG2(ndpi_struct, "SNMP excluded, 0x0201/0x0204 pattern not found\n");
goto excl;
}
if (packet->payload[offset + 2] >= 0x04) {
NDPI_LOG_DBG2(ndpi_struct, "SNMP excluded, version > 3\n");
goto excl;
}
if (flow->l4.udp.snmp_stage == 0) {
if (packet->udp->dest == htons(161) || packet->udp->dest == htons(162)) {
NDPI_LOG_INFO(ndpi_struct, "found SNMP by port\n");
ndpi_int_snmp_add_connection(ndpi_struct, flow);
return;
}
NDPI_LOG_DBG2(ndpi_struct, "SNMP stage 0\n");
if (packet->payload[offset + 2] == 3) {
flow->l4.udp.snmp_msg_id = ntohs(get_u_int32_t(packet->payload, offset + 8));
} else if (packet->payload[offset + 2] == 0) {
flow->l4.udp.snmp_msg_id = get_u_int8_t(packet->payload, offset + 15);
} else {
flow->l4.udp.snmp_msg_id = ntohs(get_u_int16_t(packet->payload, offset + 15));
}
flow->l4.udp.snmp_stage = 1 + packet->packet_direction;
return;
} else if (flow->l4.udp.snmp_stage == 1 + packet->packet_direction) {
if (packet->payload[offset + 2] == 0) {
if (flow->l4.udp.snmp_msg_id != get_u_int8_t(packet->payload, offset + 15) - 1) {
NDPI_LOG_DBG2(ndpi_struct,
"SNMP v1 excluded, message ID doesn't match\n");
goto excl;
}
}
} else if (flow->l4.udp.snmp_stage == 2 - packet->packet_direction) {
NDPI_LOG_DBG2(ndpi_struct, "SNMP stage 1-2\n");
if (packet->payload[offset + 2] == 3) {
if (flow->l4.udp.snmp_msg_id != ntohs(get_u_int32_t(packet->payload, offset + 8))) {
NDPI_LOG_DBG2(ndpi_struct,
"SNMP v3 excluded, message ID doesn't match\n");
goto excl;
}
} else if (packet->payload[offset + 2] == 0) {
if (flow->l4.udp.snmp_msg_id != get_u_int8_t(packet->payload, offset + 15)) {
NDPI_LOG_DBG2(ndpi_struct,
"SNMP v1 excluded, message ID doesn't match\n");
goto excl;
}
} else {
if (flow->l4.udp.snmp_msg_id != ntohs(get_u_int16_t(packet->payload, offset + 15))) {
NDPI_LOG_DBG2(ndpi_struct,
"SNMP v2 excluded, message ID doesn't match\n");
goto excl;
}
}
NDPI_LOG_INFO(ndpi_struct, "found SNMP\n");
ndpi_int_snmp_add_connection(ndpi_struct, flow);
return;
}
}
excl:
NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
}
void init_snmp_dissector(struct ndpi_detection_module_struct *ndpi_struct, u_int32_t *id, NDPI_PROTOCOL_BITMASK *detection_bitmask)
{
ndpi_set_bitmask_protocol_detection("SNMP", ndpi_struct, detection_bitmask, *id,
NDPI_PROTOCOL_SNMP,
ndpi_search_snmp,
NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_UDP_WITH_PAYLOAD,
SAVE_DETECTION_BITMASK_AS_UNKNOWN,
ADD_TO_DETECTION_BITMASK);
*id += 1;
}
#endif
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