/* * socks4.c * * Copyright (C) 2016 - ntop.org * Copyright (C) 2014 Tomasz Bujlow * * The signature is based on the Libprotoident library. * * 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 . * */ #include "ndpi_api.h" #ifdef NDPI_PROTOCOL_SOCKS static void ndpi_int_socks_add_connection(struct ndpi_detection_module_struct *ndpi_struct, struct ndpi_flow_struct *flow) { ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_SOCKS, NDPI_PROTOCOL_UNKNOWN); } static void ndpi_check_socks4(struct ndpi_detection_module_struct *ndpi_struct, struct ndpi_flow_struct *flow) { struct ndpi_packet_struct *packet = &flow->packet; u_int32_t payload_len = packet->payload_packet_len; /* Break after 20 packets. */ if(flow->packet_counter > 20) { NDPI_LOG(NDPI_PROTOCOL_SOCKS, ndpi_struct, NDPI_LOG_DEBUG, "Exclude SOCKS4.\n"); NDPI_ADD_PROTOCOL_TO_BITMASK(flow->excluded_protocol_bitmask, NDPI_PROTOCOL_SOCKS); return; } /* Check if we so far detected the protocol in the request or not. */ if(flow->socks4_stage == 0) { NDPI_LOG(NDPI_PROTOCOL_SOCKS, ndpi_struct, NDPI_LOG_DEBUG, "SOCKS4 stage 0: \n"); /*Octets 3 and 4 contain the port number, port 80 and 25 for now. */ if((payload_len == 9) && (((packet->payload[0] == 0x04) && (packet->payload[1] == 0x01) && (packet->payload[2] == 0x00) && (packet->payload[3] == 0x50)) || ((packet->payload[0] == 0x04) && (packet->payload[1] == 0x01) && (packet->payload[2] == 0x00) && (packet->payload[3] == 0x19)))) { NDPI_LOG(NDPI_PROTOCOL_SOCKS, ndpi_struct, NDPI_LOG_DEBUG, "Possible SOCKS4 request detected, we will look further for the response...\n"); /* Encode the direction of the packet in the stage, so we will know when we need to look for the response packet. */ flow->socks4_stage = packet->packet_direction + 1; } } else { NDPI_LOG(NDPI_PROTOCOL_SOCKS, ndpi_struct, NDPI_LOG_DEBUG, "SOCKS4 stage %u: \n", flow->socks4_stage); /* At first check, if this is for sure a response packet (in another direction. If not, do nothing now and return. */ if((flow->socks4_stage - packet->packet_direction) == 1) { return; } /* This is a packet in another direction. Check if we find the proper response. */ if(payload_len == 0) { NDPI_LOG(NDPI_PROTOCOL_SOCKS, ndpi_struct, NDPI_LOG_DEBUG, "Found SOCKS4.\n"); ndpi_int_socks_add_connection(ndpi_struct, flow); } else { NDPI_LOG(NDPI_PROTOCOL_SOCKS, ndpi_struct, NDPI_LOG_DEBUG, "The reply did not seem to belong to SOCKS4, resetting the stage to 0...\n"); flow->socks4_stage = 0; } } } static void ndpi_check_socks5(struct ndpi_detection_module_struct *ndpi_struct, struct ndpi_flow_struct *flow) { struct ndpi_packet_struct *packet = &flow->packet; u_int32_t payload_len = packet->payload_packet_len; /* Break after 20 packets. */ if(flow->packet_counter > 20) { NDPI_LOG(NDPI_PROTOCOL_SOCKS, ndpi_struct, NDPI_LOG_DEBUG, "Exclude SOCKS5.\n"); NDPI_ADD_PROTOCOL_TO_BITMASK(flow->excluded_protocol_bitmask, NDPI_PROTOCOL_SOCKS); return; } /* Check if we so far detected the protocol in the request or not. */ if(flow->socks5_stage == 0) { NDPI_LOG(NDPI_PROTOCOL_SOCKS, ndpi_struct, NDPI_LOG_DEBUG, "SOCKS5 stage 0: \n"); if((payload_len == 3) && (packet->payload[0] == 0x05) && (packet->payload[1] == 0x01) && (packet->payload[2] == 0x00)) { NDPI_LOG(NDPI_PROTOCOL_SOCKS, ndpi_struct, NDPI_LOG_DEBUG, "Possible SOCKS5 request detected, we will look further for the response...\n"); /* Encode the direction of the packet in the stage, so we will know when we need to look for the response packet. */ flow->socks5_stage = packet->packet_direction + 1; } } else { NDPI_LOG(NDPI_PROTOCOL_SOCKS, ndpi_struct, NDPI_LOG_DEBUG, "SOCKS5 stage %u: \n", flow->socks5_stage); /* At first check, if this is for sure a response packet (in another direction. If not, do nothing now and return. */ if((flow->socks5_stage - packet->packet_direction) == 1) { return; } /* This is a packet in another direction. Check if we find the proper response. */ if((payload_len == 0) || ((payload_len == 2) && (packet->payload[0] == 0x05) && (packet->payload[1] == 0x00))) { NDPI_LOG(NDPI_PROTOCOL_SOCKS, ndpi_struct, NDPI_LOG_DEBUG, "Found SOCKS5.\n"); ndpi_int_socks_add_connection(ndpi_struct, flow); } else { NDPI_LOG(NDPI_PROTOCOL_SOCKS, ndpi_struct, NDPI_LOG_DEBUG, "The reply did not seem to belong to SOCKS5, resetting the stage to 0...\n"); flow->socks5_stage = 0; } } } void ndpi_search_socks(struct ndpi_detection_module_struct *ndpi_struct, struct ndpi_flow_struct *flow) { struct ndpi_packet_struct *packet = &flow->packet; NDPI_LOG(NDPI_PROTOCOL_SOCKS, ndpi_struct, NDPI_LOG_DEBUG, "SOCKS detection...\n"); /* skip marked packets */ if(packet->detected_protocol_stack[0] != NDPI_PROTOCOL_SOCKS) { if(packet->tcp_retransmission == 0) { ndpi_check_socks4(ndpi_struct, flow); if(packet->detected_protocol_stack[0] != NDPI_PROTOCOL_SOCKS) ndpi_check_socks5(ndpi_struct, flow); } } } void init_socks_dissector(struct ndpi_detection_module_struct *ndpi_struct, u_int32_t *id, NDPI_PROTOCOL_BITMASK *detection_bitmask) { ndpi_set_bitmask_protocol_detection("SOCKS", ndpi_struct, detection_bitmask, *id, NDPI_PROTOCOL_SOCKS, ndpi_search_socks, NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_TCP_WITH_PAYLOAD_WITHOUT_RETRANSMISSION, SAVE_DETECTION_BITMASK_AS_UNKNOWN, ADD_TO_DETECTION_BITMASK); *id += 1; } #endif