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Diffstat (limited to 'contrib/impcap/arp_parser.c')
| -rw-r--r-- | contrib/impcap/arp_parser.c | 163 |
1 files changed, 163 insertions, 0 deletions
diff --git a/contrib/impcap/arp_parser.c b/contrib/impcap/arp_parser.c new file mode 100644 index 0000000..5d8ce6e --- /dev/null +++ b/contrib/impcap/arp_parser.c @@ -0,0 +1,163 @@ +/* arp_parser.c + * + * This file contains functions to parse ARP and RARP 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 arp_header_s { + uint16_t hwType; + uint16_t pType; + uint8_t hwAddrLen; + uint8_t pAddrLen; + uint16_t opCode; + uint8_t pAddr[]; +}; + +typedef struct arp_header_s arp_header_t; + +/* + * This function parses the bytes in the received packet to extract ARP metadata. + * + * its parameters are: + * - a pointer on the list of bytes representing the packet + * the first byte must be the beginning of the ARP 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 ARP 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 *arp_parse(const uchar *packet, int pktSize, struct json_object *jparent) { + DBGPRINTF("arp_parse\n"); + DBGPRINTF("packet size %d\n", pktSize); + + if (pktSize < 28) { /* too small for ARP header*/ + DBGPRINTF("ARP packet too small : %d\n", pktSize); + RETURN_DATA_AFTER(0); + } + + /* Union to prevent cast from uchar to arp_header_t */ + union { + const uchar *pck; + arp_header_t *hdr; + } arp_header_to_char; + + arp_header_to_char.pck = packet; + arp_header_t *arp_header = arp_header_to_char.hdr; + + char pAddrSrc[20], pAddrDst[20]; + + json_object_object_add(jparent, "ARP_hwType", json_object_new_int(ntohs(arp_header->hwType))); + json_object_object_add(jparent, "ARP_pType", json_object_new_int(ntohs(arp_header->pType))); + json_object_object_add(jparent, "ARP_op", json_object_new_int(ntohs(arp_header->opCode))); + + if (ntohs(arp_header->hwType) == 1) { /* ethernet addresses */ + char hwAddrSrc[20], hwAddrDst[20]; + + ether_ntoa_r((struct ether_addr *)arp_header->pAddr, hwAddrSrc); + ether_ntoa_r((struct ether_addr *)(arp_header->pAddr + arp_header->hwAddrLen + arp_header->pAddrLen), + hwAddrDst); + + json_object_object_add(jparent, "ARP_hwSrc", json_object_new_string((char *)hwAddrSrc)); + json_object_object_add(jparent, "ARP_hwDst", json_object_new_string((char *)hwAddrDst)); + } + + if (ntohs(arp_header->pType) == ETHERTYPE_IP) { + inet_ntop(AF_INET, (void *)(arp_header->pAddr + arp_header->hwAddrLen), pAddrSrc, 20); + inet_ntop(AF_INET, (void *)(arp_header->pAddr + 2 * arp_header->hwAddrLen + arp_header->pAddrLen), + pAddrDst, 20); + + json_object_object_add(jparent, "ARP_pSrc", json_object_new_string((char *)pAddrSrc)); + json_object_object_add(jparent, "ARP_pDst", json_object_new_string((char *)pAddrDst)); + } + + RETURN_DATA_AFTER(28); +} + +/* + * This function parses the bytes in the received packet to extract RARP metadata. + * This is a copy of ARP handler, as structure is the same but protocol code and name are different + * + * its parameters are: + * - a pointer on the list of bytes representing the packet + * the first byte must be the beginning of the RARP 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 RARP 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 *rarp_parse(const uchar *packet, int pktSize, struct json_object *jparent) { + DBGPRINTF("rarp_parse\n"); + DBGPRINTF("packet size %d\n", pktSize); + + if (pktSize < 28) { /* too small for RARP header*/ + DBGPRINTF("RARP packet too small : %d\n", pktSize); + RETURN_DATA_AFTER(0); + } + + /* Union to prevent cast from uchar to arp_header_t */ + union { + const uchar *pck; + arp_header_t *hdr; + } arp_header_to_char; + + arp_header_to_char.pck = packet; + arp_header_t *rarp_header = arp_header_to_char.hdr; + + char pAddrSrc[20], pAddrDst[20]; + + json_object_object_add(jparent, "RARP_hwType", json_object_new_int(ntohs(rarp_header->hwType))); + json_object_object_add(jparent, "RARP_pType", json_object_new_int(ntohs(rarp_header->pType))); + json_object_object_add(jparent, "RARP_op", json_object_new_int(ntohs(rarp_header->opCode))); + + if (ntohs(rarp_header->hwType) == 1) { /* ethernet addresses */ + char *hwAddrSrc = ether_ntoa((struct ether_addr *)rarp_header->pAddr); + char *hwAddrDst = ether_ntoa((struct ether_addr *)(rarp_header->pAddr + + rarp_header->hwAddrLen + + rarp_header->pAddrLen)); + + json_object_object_add(jparent, "RARP_hwSrc", json_object_new_string((char *)hwAddrSrc)); + json_object_object_add(jparent, "RARP_hwDst", json_object_new_string((char *)hwAddrDst)); + } + + if (ntohs(rarp_header->pType) == ETHERTYPE_IP) { + inet_ntop(AF_INET, (void *)(rarp_header->pAddr + rarp_header->hwAddrLen), pAddrSrc, 20); + inet_ntop(AF_INET, (void *)(rarp_header->pAddr + 2 * rarp_header->hwAddrLen + rarp_header->pAddrLen), + pAddrDst, 20); + + json_object_object_add(jparent, "RARP_pSrc", json_object_new_string((char *)pAddrSrc)); + json_object_object_add(jparent, "RARP_pDst", json_object_new_string((char *)pAddrDst)); + } + + RETURN_DATA_AFTER(28); +} |