diff options
Diffstat (limited to 'src/lib/protocols/rx.c')
| -rw-r--r-- | src/lib/protocols/rx.c | 130 |
1 files changed, 130 insertions, 0 deletions
diff --git a/src/lib/protocols/rx.c b/src/lib/protocols/rx.c new file mode 100644 index 000000000..07d4b5985 --- /dev/null +++ b/src/lib/protocols/rx.c @@ -0,0 +1,130 @@ +/* + * rx.c + * + * Copyright (C) 2012-16 - ntop.org + * + * Giovanni Mascellani <gio@debian.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_api.h" + +#ifdef NDPI_PROTOCOL_RX + +/* See http://web.mit.edu/kolya/afs/rx/rx-spec for procotol description. */ + +/* The should be no need for explicit packing, but just in case... */ +struct __attribute__((__packed__)) 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; +}; + +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; + int exclude = 0; + int found = 0; + + NDPI_LOG(NDPI_PROTOCOL_RX, ndpi_struct, NDPI_LOG_DEBUG, "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_LOG(NDPI_PROTOCOL_RX, ndpi_struct, NDPI_LOG_DEBUG, "short packet\n"); + exclude = 1; + goto end; + } + + /* Check whether the packet has counters beginning from one; the + Sequence Number can be zero if the packet is just an ACK. */ + struct ndpi_rx_header *header = (struct ndpi_rx_header*) packet->payload; + if ((ntohl(header->sequence_number) | 1) != 1 || ntohl(header->serial_number) != 1) { + NDPI_LOG(NDPI_PROTOCOL_RX, ndpi_struct, NDPI_LOG_DEBUG, "wrong counters\n"); + exclude = 1; + goto end; + } + + /* 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) { + found = 1; + /* In theory we could inspect the service_id field of the header + to know exactly which service is being used; see + https://www.central.org/frameless/numbers/rxservice.html. */ + } else { + NDPI_LOG(NDPI_PROTOCOL_RX, ndpi_struct, NDPI_LOG_DEBUG, "IDs not matching\n"); + exclude = 1; + } + goto end; + } else { + flow->l4.udp.rx_conn_epoch = header->conn_epoch; + flow->l4.udp.rx_conn_id = header->conn_id; + } + + end: + if (found) { + NDPI_LOG(NDPI_PROTOCOL_RX, ndpi_struct, NDPI_LOG_DEBUG, "found RX\n"); + ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_RX, NDPI_PROTOCOL_UNKNOWN); + } + else if (exclude) { + NDPI_LOG(NDPI_PROTOCOL_RX, ndpi_struct, NDPI_LOG_DEBUG, "excluding RX\n"); + NDPI_ADD_PROTOCOL_TO_BITMASK(flow->excluded_protocol_bitmask, NDPI_PROTOCOL_RX); + } +} + +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(NDPI_PROTOCOL_RX, ndpi_struct, NDPI_LOG_DEBUG, "entering RX search\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; +} + +#endif |