/* * rx.c * * Copyright (C) 2012-21 - ntop.org * * Giovanni Mascellani * * 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_protocol_ids.h" #define NDPI_CURRENT_PROTO NDPI_PROTOCOL_RX #include "ndpi_api.h" /* See http://web.mit.edu/kolya/afs/rx/rx-spec for protocol description. */ /* The should be no need for explicit packing, but just in case... */ PACK_ON struct ndpi_rx_header { u_int32_t conn_epoch; u_int32_t conn_id; u_int32_t call_number; u_int32_t sequence_number; u_int32_t serial_number; u_int8_t type; u_int8_t flags; u_int8_t status; u_int8_t security; u_int16_t checksum; u_int16_t service_id; } PACK_OFF; /* Type values */ #define DATA 1 #define ACK 2 #define BUSY 3 #define ABORT 4 #define ACKALL 5 #define CHALLENGE 6 #define RESPONSE 7 #define DEBUG 8 #define PARAM_1 9 #define PARAM_2 10 #define PARAM_3 11 #define PARAMS_4 12 #define VERS 13 /* Flags values */ #define EMPTY 0 #define CLIENT_INIT_1 1 #define REQ_ACK 2 #define PLUS_0 3 #define LAST_PKT 4 #define PLUS_1 5 #define PLUS_2 6 #define MORE_1 9 #define CLIENT_INIT_2 33 void ndpi_check_rx(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; NDPI_LOG_DBG2(ndpi_struct, "RX: pck: %d, dir[0]: %d, dir[1]: %d\n", flow->packet_counter, flow->packet_direction_counter[0], flow->packet_direction_counter[1]); /* Check that packet is long enough */ if (payload_len < sizeof(struct ndpi_rx_header)) { NDPI_EXCLUDE_PROTO(ndpi_struct, flow); return; } struct ndpi_rx_header *header = (struct ndpi_rx_header*) packet->payload; /** * Useless check: a session could be detected also after it starts * and this check limit the correct detection for -d option (disable guess) * TODO - maybe to improve **/ /* Check whether the packet has counters beginning from one; the Sequence Number can be zero if the packet is just an ACK. */ /* if ((ntohl(header->sequence_number) | 1) != 1 || ntohl(header->serial_number) != 1) */ /** * Check the TYPE and FLAGS fields of an RX packet header. * This check is necessary because we could detect an RX session already begun **/ /* TYPE field */ if((header->type < DATA) || (header->type > VERS)) { NDPI_EXCLUDE_PROTO(ndpi_struct, flow); return; } /* FLAGS fields */ if(header->flags == EMPTY || header->flags == LAST_PKT || header->flags == PLUS_0 || header->flags == PLUS_1 || header->flags == PLUS_2 || header->flags == REQ_ACK || header->flags == MORE_1 || header->flags == CLIENT_INIT_1 || header->flags == CLIENT_INIT_2) { /* TYPE and FLAGS combo */ switch(header->type) { case DATA: if(header->flags == LAST_PKT || header->flags == EMPTY || header->flags == PLUS_0 || header->flags == PLUS_1 || header->flags == PLUS_2 || header->flags == REQ_ACK || header->flags == MORE_1) goto security; /* Fall-through */ case ACK: if(header->flags == CLIENT_INIT_1 || header->flags == CLIENT_INIT_2 || header->flags == EMPTY) goto security; /* Fall-through */ case CHALLENGE: if(header->flags == EMPTY || header->call_number == 0) goto security; /* Fall-through */ case RESPONSE: if(header->flags == EMPTY || header->call_number == 0) goto security; /* Fall-through */ case ACKALL: if(header->flags == EMPTY) goto security; /* Fall-through */ case BUSY: goto security; case ABORT: goto security; case DEBUG: goto security; case PARAM_1: goto security; case PARAM_2: goto security; case PARAM_3: goto security; case VERS: goto security; default: NDPI_EXCLUDE_PROTO(ndpi_struct, flow); return; } // switch } else { // FLAG NDPI_EXCLUDE_PROTO(ndpi_struct, flow); return; } security: /* SECURITY field */ if(header->security > 3) { NDPI_EXCLUDE_PROTO(ndpi_struct, flow); return; } /* If we have already seen one packet in the other direction, then the two must have matching connection numbers. Otherwise store them. */ if(flow->packet_direction_counter[!packet->packet_direction] != 0) { if (flow->l4.udp.rx_conn_epoch == header->conn_epoch && flow->l4.udp.rx_conn_id == header->conn_id) { NDPI_LOG_INFO(ndpi_struct, "found RX\n"); ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_RX, NDPI_PROTOCOL_UNKNOWN); } /* https://www.central.org/frameless/numbers/rxservice.html. */ else { NDPI_EXCLUDE_PROTO(ndpi_struct, flow); return; } } else { flow->l4.udp.rx_conn_epoch = header->conn_epoch; flow->l4.udp.rx_conn_id = header->conn_id; { NDPI_LOG_INFO(ndpi_struct, "found RX\n"); ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_RX, NDPI_PROTOCOL_UNKNOWN); } } } void ndpi_search_rx(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 RX\n"); if (packet->detected_protocol_stack[0] != NDPI_PROTOCOL_RX) { ndpi_check_rx(ndpi_struct, flow); } } void init_rx_dissector(struct ndpi_detection_module_struct *ndpi_struct, u_int32_t *id, NDPI_PROTOCOL_BITMASK *detection_bitmask) { ndpi_set_bitmask_protocol_detection("RX", ndpi_struct, detection_bitmask, *id, NDPI_PROTOCOL_RX, ndpi_search_rx, NDPI_SELECTION_BITMASK_PROTOCOL_UDP_WITH_PAYLOAD, SAVE_DETECTION_BITMASK_AS_UNKNOWN, ADD_TO_DETECTION_BITMASK); *id += 1; }