diff options
Diffstat (limited to 'contrib/impcap/tcp_parser.c')
| -rw-r--r-- | contrib/impcap/tcp_parser.c | 121 |
1 files changed, 121 insertions, 0 deletions
diff --git a/contrib/impcap/tcp_parser.c b/contrib/impcap/tcp_parser.c new file mode 100644 index 0000000..b96c1f3 --- /dev/null +++ b/contrib/impcap/tcp_parser.c @@ -0,0 +1,121 @@ +/* tcp_parser.c + * + * This file contains functions to parse TCP 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" + +#define SMB_PORT 445 +#define HTTP_PORT 80 +#define HTTP_PORT_ALT 8080 +#define FTP_PORT 21 +#define FTP_PORT_DATA 20 + +struct tcp_header_s { + uint16_t srcPort; + uint16_t dstPort; + uint32_t seq; + uint32_t ack; + uint8_t dor; + uint8_t flags; + uint16_t windowSize; + uint16_t checksum; + uint16_t urgPointer; + uint8_t options[]; +}; + +typedef struct tcp_header_s tcp_header_t; + +static char flagCodes[10] = "FSRPAUECN"; + +/* + * This function parses the bytes in the received packet to extract TCP metadata. + * + * its parameters are: + * - a pointer on the list of bytes representing the packet + * the first byte must be the beginning of the TCP 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 TCP 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 *tcp_parse(const uchar *packet, int pktSize, struct json_object *jparent) { + DBGPRINTF("tcp_parse\n"); + DBGPRINTF("packet size %d\n", pktSize); + + if (pktSize < 20) { + DBGPRINTF("TCP packet too small : %d\n", pktSize); + RETURN_DATA_AFTER(0) + } + + /* Union to prevent cast from uchar to tcp_header_t */ + union { + const uchar *pck; + tcp_header_t *hdr; + } tcp_header_to_char; + + tcp_header_to_char.pck = packet; + tcp_header_t *tcp_header = tcp_header_to_char.hdr; + + uint8_t i, pos = 0; + char flags[10] = {0}; + + for (i = 0; i < 8; ++i) { + if (tcp_header->flags & (0x01 << i)) + flags[pos++] = flagCodes[i]; + } + if (tcp_header->dor & 0x01) + flags[pos++] = flagCodes[9]; + + uint16_t srcPort = ntohs(tcp_header->srcPort); + uint16_t dstPort = ntohs(tcp_header->dstPort); + + uint8_t headerLength = (tcp_header->dor & 0xF0) >> 2; //>>4 to offset but <<2 to get offset as bytes + + json_object_object_add(jparent, "net_src_port", json_object_new_int(srcPort)); + json_object_object_add(jparent, "net_dst_port", json_object_new_int(dstPort)); + json_object_object_add(jparent, "TCP_seq_number", json_object_new_int64(ntohl(tcp_header->seq))); + json_object_object_add(jparent, "TCP_ack_number", json_object_new_int64(ntohl(tcp_header->ack))); + json_object_object_add(jparent, "net_flags", json_object_new_string(flags)); + + if (srcPort == SMB_PORT || dstPort == SMB_PORT) { + return smb_parse(packet + headerLength, pktSize - headerLength, jparent); + } + if (srcPort == FTP_PORT || dstPort == FTP_PORT || srcPort == FTP_PORT_DATA || dstPort == FTP_PORT_DATA) { + return ftp_parse(packet + headerLength, pktSize - headerLength, jparent); + } + if (srcPort == HTTP_PORT || dstPort == HTTP_PORT || + srcPort == HTTP_PORT_ALT || dstPort == HTTP_PORT_ALT) { + return http_parse(packet + headerLength, pktSize - headerLength, jparent); + } + DBGPRINTF("tcp return after header length (%u)\n", headerLength); + RETURN_DATA_AFTER(headerLength) +} |