/* vi: set sw=4 ts=4: */
/*
- * arpping.c
- *
* Mostly stolen from: dhcpcd - DHCP client daemon
* by Yoichi Hariguchi <yoichi@fore.com>
+ *
+ * Licensed under GPLv2, see file LICENSE in this tarball for details.
*/
-
-#include <time.h>
-#include <sys/socket.h>
#include <netinet/if_ether.h>
#include <net/if_arp.h>
-#include <netinet/in.h>
-#include <string.h>
-#include <unistd.h>
-#include <errno.h>
-#include "dhcpd.h"
-#include "arpping.h"
#include "common.h"
+#include "dhcpd.h"
-/* args: yiaddr - what IP to ping
- * ip - our ip
- * mac - our arp address
- * interface - interface to use
- * retn: 1 addr free
- * 0 addr used
- * -1 error
- */
+struct arpMsg {
+ /* Ethernet header */
+ uint8_t h_dest[6]; /* 00 destination ether addr */
+ uint8_t h_source[6]; /* 06 source ether addr */
+ uint16_t h_proto; /* 0c packet type ID field */
-/* FIXME: match response against chaddr */
-int arpping(uint32_t yiaddr, uint32_t ip, uint8_t *mac, char *interface)
-{
+ /* ARP packet */
+ uint16_t htype; /* 0e hardware type (must be ARPHRD_ETHER) */
+ uint16_t ptype; /* 10 protocol type (must be ETH_P_IP) */
+ uint8_t hlen; /* 12 hardware address length (must be 6) */
+ uint8_t plen; /* 13 protocol address length (must be 4) */
+ uint16_t operation; /* 14 ARP opcode */
+ uint8_t sHaddr[6]; /* 16 sender's hardware address */
+ uint8_t sInaddr[4]; /* 1c sender's IP address */
+ uint8_t tHaddr[6]; /* 20 target's hardware address */
+ uint8_t tInaddr[4]; /* 26 target's IP address */
+ uint8_t pad[18]; /* 2a pad for min. ethernet payload (60 bytes) */
+} PACKED;
- int timeout = 2;
- int optval = 1;
- int s; /* socket */
- int rv = 1; /* return value */
- struct sockaddr addr; /* for interface name */
- struct arpMsg arp;
- fd_set fdset;
- struct timeval tm;
- time_t prevTime;
+enum {
+ ARP_MSG_SIZE = 0x2a
+};
+/* Returns 1 if no reply received */
+int FAST_FUNC arpping(uint32_t test_nip,
+ const uint8_t *safe_mac,
+ uint32_t from_ip,
+ uint8_t *from_mac,
+ const char *interface)
+{
+ int timeout_ms;
+ struct pollfd pfd[1];
+#define s (pfd[0].fd) /* socket */
+ int rv = 1; /* "no reply received" yet */
+ struct sockaddr addr; /* for interface name */
+ struct arpMsg arp;
- if ((s = socket(PF_PACKET, SOCK_PACKET, htons(ETH_P_ARP))) == -1) {
+ s = socket(PF_PACKET, SOCK_PACKET, htons(ETH_P_ARP));
+ if (s == -1) {
bb_perror_msg(bb_msg_can_not_create_raw_socket);
return -1;
}
- if (setsockopt(s, SOL_SOCKET, SO_BROADCAST, &optval, sizeof(optval)) == -1) {
- bb_perror_msg("cannot setsocketopt on raw socket");
- close(s);
- return -1;
+ if (setsockopt_broadcast(s) == -1) {
+ bb_perror_msg("can't enable bcast on raw socket");
+ goto ret;
}
/* send arp request */
memset(&arp, 0, sizeof(arp));
- memcpy(arp.h_dest, MAC_BCAST_ADDR, 6); /* MAC DA */
- memcpy(arp.h_source, mac, 6); /* MAC SA */
- arp.h_proto = htons(ETH_P_ARP); /* protocol type (Ethernet) */
- arp.htype = htons(ARPHRD_ETHER); /* hardware type */
- arp.ptype = htons(ETH_P_IP); /* protocol type (ARP message) */
- arp.hlen = 6; /* hardware address length */
- arp.plen = 4; /* protocol address length */
- arp.operation = htons(ARPOP_REQUEST); /* ARP op code */
- memcpy(arp.sInaddr, &ip, sizeof(ip)); /* source IP address */
- memcpy(arp.sHaddr, mac, 6); /* source hardware address */
- memcpy(arp.tInaddr, &yiaddr, sizeof(yiaddr)); /* target IP address */
+ memset(arp.h_dest, 0xff, 6); /* MAC DA */
+ memcpy(arp.h_source, from_mac, 6); /* MAC SA */
+ arp.h_proto = htons(ETH_P_ARP); /* protocol type (Ethernet) */
+ arp.htype = htons(ARPHRD_ETHER); /* hardware type */
+ arp.ptype = htons(ETH_P_IP); /* protocol type (ARP message) */
+ arp.hlen = 6; /* hardware address length */
+ arp.plen = 4; /* protocol address length */
+ arp.operation = htons(ARPOP_REQUEST); /* ARP op code */
+ memcpy(arp.sHaddr, from_mac, 6); /* source hardware address */
+ memcpy(arp.sInaddr, &from_ip, sizeof(from_ip)); /* source IP address */
+ /* tHaddr is zero-filled */ /* target hardware address */
+ memcpy(arp.tInaddr, &test_nip, sizeof(test_nip));/* target IP address */
memset(&addr, 0, sizeof(addr));
- strcpy(addr.sa_data, interface);
- if (sendto(s, &arp, sizeof(arp), 0, &addr, sizeof(addr)) < 0)
- rv = 0;
+ safe_strncpy(addr.sa_data, interface, sizeof(addr.sa_data));
+ if (sendto(s, &arp, sizeof(arp), 0, &addr, sizeof(addr)) < 0) {
+ // TODO: error message? caller didn't expect us to fail,
+ // just returning 1 "no reply received" misleads it.
+ goto ret;
+ }
+
+ /* wait for arp reply, and check it */
+ timeout_ms = 2000;
+ do {
+ typedef uint32_t aliased_uint32_t FIX_ALIASING;
+ int r;
+ unsigned prevTime = monotonic_ms();
+
+ pfd[0].events = POLLIN;
+ r = safe_poll(pfd, 1, timeout_ms);
+ if (r < 0)
+ break;
+ if (r) {
+ r = safe_read(s, &arp, sizeof(arp));
+ if (r < 0)
+ break;
+
+ //log3("sHaddr %02x:%02x:%02x:%02x:%02x:%02x",
+ // arp.sHaddr[0], arp.sHaddr[1], arp.sHaddr[2],
+ // arp.sHaddr[3], arp.sHaddr[4], arp.sHaddr[5]);
- /* wait arp reply, and check it */
- tm.tv_usec = 0;
- prevTime = uptime();
- while (timeout > 0) {
- FD_ZERO(&fdset);
- FD_SET(s, &fdset);
- tm.tv_sec = timeout;
- if (select(s + 1, &fdset, (fd_set *) NULL, (fd_set *) NULL, &tm) < 0) {
- bb_perror_msg("Error on ARPING request");
- if (errno != EINTR) rv = 0;
- } else if (FD_ISSET(s, &fdset)) {
- if (recv(s, &arp, sizeof(arp), 0) < 0 ) rv = 0;
- if (arp.operation == htons(ARPOP_REPLY) &&
- memcmp(arp.tHaddr, mac, 6) == 0 &&
- *((uint32_t *) arp.sInaddr) == yiaddr) {
- DEBUG("Valid arp reply received for this address");
- rv = 0;
+ if (r >= ARP_MSG_SIZE
+ && arp.operation == htons(ARPOP_REPLY)
+ /* don't check it: Linux doesn't return proper tHaddr (fixed in 2.6.24?) */
+ /* && memcmp(arp.tHaddr, from_mac, 6) == 0 */
+ && *(aliased_uint32_t*)arp.sInaddr == test_nip
+ ) {
+ /* if ARP source MAC matches safe_mac
+ * (which is client's MAC), then it's not a conflict
+ * (client simply already has this IP and replies to ARPs!)
+ */
+ if (!safe_mac || memcmp(safe_mac, arp.sHaddr, 6) != 0)
+ rv = 0;
+ //else log2("sHaddr == safe_mac");
break;
}
}
- timeout -= uptime() - prevTime;
- prevTime = uptime();
- }
+ timeout_ms -= (unsigned)monotonic_ms() - prevTime;
+ } while (timeout_ms > 0);
+
+ ret:
close(s);
- DEBUG("%salid arp replies for this address", rv ? "No v" : "V");
+ log1("%srp reply received for this address", rv ? "No a" : "A");
return rv;
}
projects / oweals / busybox.git / blobdiff