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/* icmp_parser.c
*
* This file contains functions to parse ICMP 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"
struct icmp_header_s {
uint8_t type;
uint8_t code;
uint16_t checksum;
uint8_t data[];
};
typedef struct icmp_header_s icmp_header_t;
/*
* This function parses the bytes in the received packet to extract ICMP metadata.
*
* its parameters are:
* - a pointer on the list of bytes representing the packet
* the first byte must be the beginning of the ICMP 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 ICMP 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 *icmp_parse(const uchar *packet, int pktSize, struct json_object *jparent) {
DBGPRINTF("icmp_parse\n");
DBGPRINTF("packet size %d\n", pktSize);
if (pktSize < 8) {
DBGPRINTF("ICMP packet too small : %d\n", pktSize);
RETURN_DATA_AFTER(0);
}
/* Union to prevent cast from uchar to icmp_header_t */
union {
const uchar *pck;
icmp_header_t *hdr;
} icmp_header_to_char;
icmp_header_to_char.pck = packet;
icmp_header_t *icmp_header = icmp_header_to_char.hdr;
json_object_object_add(jparent, "net_icmp_type", json_object_new_int(icmp_header->type));
json_object_object_add(jparent, "net_icmp_code", json_object_new_int(icmp_header->code));
json_object_object_add(jparent, "icmp_checksum", json_object_new_int(ntohs(icmp_header->checksum)));
RETURN_DATA_AFTER(8)
}
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