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/* ipv4_parser.c
*
* This file contains functions to parse IP 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 ipv4_header_s {
/*#if __BYTE_ORDER == __BIG_ENDIAN
unsigned char version:4;
unsigned char ihl:4;
#else*/
unsigned char ihl:4;
unsigned char version:4;
//#endif
uint8_t service;
uint16_t totLen;
uint16_t id;
uint16_t frag;
uint8_t ttl;
uint8_t proto;
uint16_t hdrChksum;
uint8_t addrSrc[4];
uint8_t addrDst[4];
uint8_t pOptions[];
};
typedef struct ipv4_header_s ipv4_header_t;
/*
* This function parses the bytes in the received packet to extract IP metadata.
*
* its parameters are:
* - a pointer on the list of bytes representing the packet
* the first byte must be the beginning of the IP 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 IP 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 *ipv4_parse(const uchar *packet, int pktSize, struct json_object *jparent) {
DBGPRINTF("ipv4_parse\n");
DBGPRINTF("packet size %d\n", pktSize);
if (pktSize < 20) { /* too small for IPv4 header + data (header might be longer)*/
DBGPRINTF("IPv4 packet too small : %d\n", pktSize);
RETURN_DATA_AFTER(0)
}
/* Union to prevent cast from uchar to ipv4_header_t */
union {
const uchar *pck;
ipv4_header_t *hdr;
} ipv4_header_to_char;
ipv4_header_to_char.pck = packet;
ipv4_header_t *ipv4_header = ipv4_header_to_char.hdr;
char addrSrc[20], addrDst[20];
uint8_t hdrLen = 4 * ipv4_header->ihl; /* 4 x length in words */
inet_ntop(AF_INET, (void *)&ipv4_header->addrSrc, addrSrc, 20);
inet_ntop(AF_INET, (void *)&ipv4_header->addrDst, addrDst, 20);
json_object_object_add(jparent, "net_dst_ip", json_object_new_string((char *)addrDst));
json_object_object_add(jparent, "net_src_ip", json_object_new_string((char *)addrSrc));
json_object_object_add(jparent, "IP_ihl", json_object_new_int(ipv4_header->ihl));
json_object_object_add(jparent, "net_ttl", json_object_new_int(ipv4_header->ttl));
json_object_object_add(jparent, "IP_proto", json_object_new_int(ipv4_header->proto));
return ip_proto_parse(ipv4_header->proto, (packet + hdrLen), (pktSize - hdrLen), jparent);
}
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