mirror of
https://code.semirocket.science/wrapsix
synced 2024-09-19 23:11:04 +03:00
93 lines
2.5 KiB
C
93 lines
2.5 KiB
C
/*
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* WrapSix
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* Copyright (C) 2008-2012 Michal Zima <xhire@mujmalysvet.cz>
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <net/ethernet.h> /* ETHERTYPE_* */
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#include <netinet/in.h> /* htons */
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#include <stdlib.h> /* malloc */
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#include <string.h> /* memcmp, memset */
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#include "arp.h"
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#include "log.h"
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#include "transmitter.h"
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#include "wrapper.h"
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/**
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* Process ARP packets and reply to them.
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*
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* @param ethq Ethernet header of the packet
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* @param payload Data of the packet
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*
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* @return 0 for success
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* @return 1 for failure
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*/
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int arp(struct s_ethernet *ethq, char *payload)
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{
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struct s_arp *arpq, *arpr; /* request and reply */
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struct s_ethernet *ethr;
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unsigned char *packet;
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arpq = (struct s_arp *) payload;
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/* process only requests */
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if (htons(arpq->opcode) != ARP_OP_REQUEST) {
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/* not an ARP request */
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return 1;
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}
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/* test if this packet belongs to us */
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if (memcmp(&wrapsix_ipv4_addr, &arpq->ip_dest, 4)) {
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log_debug("This is unfamiliar ARP packet");
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return 1;
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}
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/* compute the packet size */
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#define ARP_PACKET_SIZE sizeof(struct s_ethernet) + sizeof(struct s_arp)
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/* allocate enough memory */
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if ((packet = (unsigned char *) malloc(ARP_PACKET_SIZE)) == NULL) {
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log_error("Lack of free memory");
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return 1;
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}
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memset(packet, 0x0, ARP_PACKET_SIZE);
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/* define ethernet header and ARP offsets */
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ethr = (struct s_ethernet *) packet;
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arpr = (struct s_arp *) (packet + sizeof(struct s_ethernet));
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/* assemble the ethernet header */
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ethr->dest = ethq->src;
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ethr->src = mac;
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ethr->type = htons(ETHERTYPE_ARP);
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/* assemble the ARP reply part */
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arpr->hw = htons(ARP_HDR_ETHER);
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arpr->proto = htons(ETHERTYPE_IP);
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arpr->hw_len = 0x06;
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arpr->proto_len = 0x04;
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arpr->opcode = htons(ARP_OP_REPLY);
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arpr->mac_src = ethr->src;
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arpr->mac_dest = ethr->dest;
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arpr->ip_src = wrapsix_ipv4_addr;
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arpr->ip_dest = arpq->ip_src;
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/* send ARP reply */
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transmit_raw(packet, ARP_PACKET_SIZE);
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return 0;
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}
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