| 1 | /*
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| 2 | * arpping.c
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| 3 | *
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| 4 | * Mostly stolen from: dhcpcd - DHCP client daemon
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| 5 | * by Yoichi Hariguchi <yoichi@fore.com>
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| 6 | */
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| 7 |
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| 8 | #include <time.h>
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| 9 | #include <sys/socket.h>
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| 10 | #include <netinet/if_ether.h>
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| 11 | #include <net/if_arp.h>
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| 12 | #include <netinet/in.h>
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| 13 | #include <string.h>
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| 14 | #include <unistd.h>
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| 15 | #include <errno.h>
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| 16 |
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| 17 | #include "dhcpd.h"
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| 18 | #include "arpping.h"
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| 19 | #include "common.h"
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| 20 |
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| 21 | /* args: yiaddr - what IP to ping
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| 22 | * ip - our ip
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| 23 | * mac - our arp address
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| 24 | * interface - interface to use
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| 25 | * retn: 1 addr free
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| 26 | * 0 addr used
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| 27 | * -1 error
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| 28 | */
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| 29 |
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| 30 | /* FIXME: match response against chaddr */
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| 31 | int arpping(uint32_t yiaddr, uint32_t ip, uint8_t *mac, char *interface)
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| 32 | {
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| 33 |
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| 34 | int timeout = 2;
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| 35 | int optval = 1;
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| 36 | int s; /* socket */
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| 37 | int rv = 1; /* return value */
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| 38 | struct sockaddr addr; /* for interface name */
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| 39 | struct arpMsg arp;
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| 40 | fd_set fdset;
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| 41 | struct timeval tm;
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| 42 | time_t prevTime;
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| 43 |
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| 44 |
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| 45 | if ((s = socket (PF_PACKET, SOCK_PACKET, htons(ETH_P_ARP))) == -1) {
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| 46 | #ifdef IN_BUSYBOX
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| 47 | LOG(LOG_ERR, bb_msg_can_not_create_raw_socket);
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| 48 | #else
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| 49 | LOG(LOG_ERR, "Could not open raw socket");
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| 50 | #endif
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| 51 | return -1;
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| 52 | }
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| 53 |
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| 54 | if (setsockopt(s, SOL_SOCKET, SO_BROADCAST, &optval, sizeof(optval)) == -1) {
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| 55 | LOG(LOG_ERR, "Could not setsocketopt on raw socket");
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| 56 | close(s);
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| 57 | return -1;
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| 58 | }
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| 59 |
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| 60 | /* send arp request */
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| 61 | memset(&arp, 0, sizeof(arp));
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| 62 | memcpy(arp.h_dest, MAC_BCAST_ADDR, 6); /* MAC DA */
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| 63 | memcpy(arp.h_source, mac, 6); /* MAC SA */
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| 64 | arp.h_proto = htons(ETH_P_ARP); /* protocol type (Ethernet) */
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| 65 | arp.htype = htons(ARPHRD_ETHER); /* hardware type */
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| 66 | arp.ptype = htons(ETH_P_IP); /* protocol type (ARP message) */
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| 67 | arp.hlen = 6; /* hardware address length */
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| 68 | arp.plen = 4; /* protocol address length */
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| 69 | arp.operation = htons(ARPOP_REQUEST); /* ARP op code */
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| 70 | memcpy(arp.sInaddr, &ip, sizeof(ip)); /* source IP address */
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| 71 | memcpy(arp.sHaddr, mac, 6); /* source hardware address */
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| 72 | memcpy(arp.tInaddr, &yiaddr, sizeof(yiaddr)); /* target IP address */
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| 73 |
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| 74 | memset(&addr, 0, sizeof(addr));
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| 75 | strcpy(addr.sa_data, interface);
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| 76 | if (sendto(s, &arp, sizeof(arp), 0, &addr, sizeof(addr)) < 0)
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| 77 | rv = 0;
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| 78 |
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| 79 | /* wait arp reply, and check it */
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| 80 | tm.tv_usec = 0;
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| 81 | prevTime = uptime();
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| 82 | while (timeout > 0) {
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| 83 | FD_ZERO(&fdset);
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| 84 | FD_SET(s, &fdset);
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| 85 | tm.tv_sec = timeout;
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| 86 | if (select(s + 1, &fdset, (fd_set *) NULL, (fd_set *) NULL, &tm) < 0) {
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| 87 | DEBUG(LOG_ERR, "Error on ARPING request: %m");
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| 88 | if (errno != EINTR) rv = 0;
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| 89 | } else if (FD_ISSET(s, &fdset)) {
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| 90 | if (recv(s, &arp, sizeof(arp), 0) < 0 ) rv = 0;
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| 91 | if (arp.operation == htons(ARPOP_REPLY) &&
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| 92 | memcmp(arp.tHaddr, mac, 6) == 0 &&
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| 93 | *((uint32_t *) arp.sInaddr) == yiaddr) {
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| 94 | DEBUG(LOG_INFO, "Valid arp reply receved for this address");
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| 95 | rv = 0;
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| 96 | break;
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| 97 | }
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| 98 | }
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| 99 | timeout -= uptime() - prevTime;
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| 100 | prevTime = uptime();
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| 101 | }
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| 102 | close(s);
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| 103 | DEBUG(LOG_INFO, "%salid arp replies for this address", rv ? "No v" : "V");
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| 104 | return rv;
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| 105 | }
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