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Diffstat (limited to 'contrib/impcap/llc_parser.c')
| -rw-r--r-- | contrib/impcap/llc_parser.c | 109 |
1 files changed, 109 insertions, 0 deletions
diff --git a/contrib/impcap/llc_parser.c b/contrib/impcap/llc_parser.c new file mode 100644 index 0000000..fca4568 --- /dev/null +++ b/contrib/impcap/llc_parser.c @@ -0,0 +1,109 @@ +/* llc_parser.c + * + * This file contains functions to parse llc headers. + * + * File begun on 2018-11-13 + * + * Created by: + * - Théo Bertin (theo.bertin@advens.fr) + * + * With: + * - François Bernard (francois.bernard@isen.yncrea.fr) + * - Tianyu Geng (tianyu.geng@isen.yncrea.fr) + * + * This file is part of rsyslog. + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * -or- + * see COPYING.ASL20 in the source distribution + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +#include "config.h" +#include "parsers.h" + +/* + * This function parses the bytes in the received packet to extract LLC metadata. + * + * its parameters are: + * - a pointer on the list of bytes representing the packet + * the first byte must be the beginning of the LLC header + * - the size of the list passed as first parameter + * - a pointer on a json_object, containing all the metadata recovered so far + * this is also where LLC metadata will be added + * + * This function returns a structure containing the data unprocessed by this parser + * or the ones after (as a list of bytes), and the length of this data. +*/ +data_ret_t *llc_parse(const uchar *packet, int pktSize, struct json_object *jparent) { + DBGPRINTF("entered llc_parse\n"); + DBGPRINTF("packet size %d\n", pktSize); + + if (pktSize < 3) { /* too short for llc header */ + DBGPRINTF("LLC packet too small : %d\n", pktSize); + RETURN_DATA_AFTER(0) + } + + uint8_t dsapField, dsap, ssapField, ssap; + uint16_t ctrl; + uint8_t headerLen; + + dsapField = (uint8_t)packet[0]; + ssapField = (uint8_t)packet[1]; + DBGPRINTF("dsapField : %02X\n", dsapField); + DBGPRINTF("ssapField : %02X\n", ssapField); + + if (dsapField == 0xff && ssapField == 0xff) { + /* this is an IPX packet, without LLC */ + return ipx_parse(packet, pktSize, jparent); + } + + if ((packet[2] & 0x03) == 3) { + /* U frame: LLC control is 8 bits */ + ctrl = (uint8_t)packet[2]; + headerLen = 3; + } else { + /* I and S data frames: LLC control is 16 bits */ + ctrl = ntohs((uint16_t)packet[2]); + headerLen = 4; + } + + /* don't take last bit into account */ + dsap = dsapField & 0xfe; + ssap = ssapField & 0xfe; + + json_object_object_add(jparent, "LLC_dsap", json_object_new_int(dsap)); + json_object_object_add(jparent, "LLC_ssap", json_object_new_int(ssap)); + json_object_object_add(jparent, "LLC_ctrl", json_object_new_int(ctrl)); + + if (dsap == 0xaa && ssap == 0xaa && ctrl == 0x03) { + /* SNAP header */ + uint32_t orgCode = packet[headerLen] << 16 | + packet[headerLen + 1] << 8 | + packet[headerLen + 2]; + uint16_t ethType = packet[headerLen + 3] << 8 | + packet[headerLen + 4]; + json_object_object_add(jparent, "SNAP_oui", json_object_new_int(orgCode)); + json_object_object_add(jparent, "SNAP_ethType", json_object_new_int(ethType)); + return eth_proto_parse(ethType, packet + headerLen, pktSize - headerLen, jparent); + } + if (dsap == 0x06 && ssap == 0x06 && ctrl == 0x03) { + /* IPv4 header */ + return ipv4_parse(packet + headerLen, pktSize - headerLen, jparent); + } + if (dsap == 0xe0 && ssap == 0xe0 && ctrl == 0x03) { + /* IPX packet with LLC */ + return ipx_parse(packet + headerLen, pktSize - headerLen, jparent); + } + + RETURN_DATA_AFTER(headerLen) +} |