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Diffstat (limited to 'contrib/impcap/udp_parser.c')
| -rw-r--r-- | contrib/impcap/udp_parser.c | 90 |
1 files changed, 90 insertions, 0 deletions
diff --git a/contrib/impcap/udp_parser.c b/contrib/impcap/udp_parser.c new file mode 100644 index 0000000..a9b7dca --- /dev/null +++ b/contrib/impcap/udp_parser.c @@ -0,0 +1,90 @@ +/* udp_parser.c + * + * This file contains functions to parse UDP 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 DNS_PORT 53 + +struct udp_header_s { + uint16_t srcPort; + uint16_t dstPort; + uint16_t totalLength; + uint16_t checksum; +}; + +typedef struct udp_header_s udp_header_t; + +/* + * This function parses the bytes in the received packet to extract UDP metadata. + * + * its parameters are: + * - a pointer on the list of bytes representing the packet + * the first byte must be the beginning of the UDP 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 UDP 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 *udp_parse(const uchar *packet, int pktSize, struct json_object *jparent) { + DBGPRINTF("udp_parse\n"); + DBGPRINTF("packet size %d\n", pktSize); + + if (pktSize < 8) { + DBGPRINTF("UDP packet too small : %d\n", pktSize); + RETURN_DATA_AFTER(0) + } + + /* Union to prevent cast from uchar to udp_header_t */ + union { + const uchar *pck; + udp_header_t *hdr; + } udp_header_to_char; + + udp_header_to_char.pck = packet; + udp_header_t *udp_header = udp_header_to_char.hdr; + + // Prevent endianness issue + unsigned short int src_port = ntohs(udp_header->srcPort); + unsigned short int dst_port = ntohs(udp_header->dstPort); + + json_object_object_add(jparent, "net_src_port", json_object_new_int(src_port)); + json_object_object_add(jparent, "net_dst_port", json_object_new_int(dst_port)); + json_object_object_add(jparent, "UDP_Length", json_object_new_int(ntohs(udp_header->totalLength))); + json_object_object_add(jparent, "UDP_Checksum", json_object_new_int(ntohs(udp_header->checksum))); + + if (src_port == DNS_PORT || dst_port == DNS_PORT) { + return dns_parse(packet + sizeof(udp_header_t), pktSize - sizeof(udp_header_t), jparent); + } + + RETURN_DATA_AFTER(8) +} |