aboutsummaryrefslogtreecommitdiffstats
path: root/arp.c
diff options
context:
space:
mode:
Diffstat (limited to 'arp.c')
-rw-r--r--arp.c308
1 files changed, 308 insertions, 0 deletions
diff --git a/arp.c b/arp.c
new file mode 100644
index 0000000..89d63fe
--- /dev/null
+++ b/arp.c
@@ -0,0 +1,308 @@
+/*
+ * dhcpcd - DHCP client daemon
+ * Copyright (c) 2006-2008 Roy Marples <roy@marples.name>
+ * All rights reserved
+
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <errno.h>
+#include <signal.h>
+#include <stdlib.h>
+#include <string.h>
+#include <syslog.h>
+#include <unistd.h>
+
+#include "arp.h"
+#include "bind.h"
+#include "common.h"
+#include "dhcpcd.h"
+#include "eloop.h"
+#include "if-options.h"
+#include "ipv4ll.h"
+#include "net.h"
+
+#define ARP_LEN \
+ (sizeof(struct arphdr) + (2 * sizeof(uint32_t)) + (2 * HWADDR_LEN))
+
+static int
+send_arp(const struct interface *iface, int op, in_addr_t sip, in_addr_t tip)
+{
+ uint8_t arp_buffer[ARP_LEN];
+ struct arphdr ar;
+ size_t len;
+ uint8_t *p;
+ int retval;
+
+ ar.ar_hrd = htons(iface->family);
+ ar.ar_pro = htons(ETHERTYPE_IP);
+ ar.ar_hln = iface->hwlen;
+ ar.ar_pln = sizeof(sip);
+ ar.ar_op = htons(op);
+ memcpy(arp_buffer, &ar, sizeof(ar));
+ p = arp_buffer + sizeof(ar);
+ memcpy(p, iface->hwaddr, iface->hwlen);
+ p += iface->hwlen;
+ memcpy(p, &sip, sizeof(sip));
+ p += sizeof(sip);
+ /* ARP requests should ignore this */
+ retval = iface->hwlen;
+ while (retval--)
+ *p++ = '\0';
+ memcpy(p, &tip, sizeof(tip));
+ p += sizeof(tip);
+ len = p - arp_buffer;
+ retval = send_raw_packet(iface, ETHERTYPE_ARP, arp_buffer, len);
+ return retval;
+}
+
+static void
+handle_arp_failure(struct interface *iface)
+{
+
+ /* If we failed without a magic cookie then we need to try
+ * and defend our IPv4LL address. */
+ if ((iface->state->offer != NULL &&
+ iface->state->offer->cookie != htonl(MAGIC_COOKIE)) ||
+ (iface->state->new != NULL &&
+ iface->state->new->cookie != htonl(MAGIC_COOKIE)))
+ {
+ handle_ipv4ll_failure(iface);
+ return;
+ }
+
+ unlink(iface->leasefile);
+ if (!iface->state->lease.frominfo)
+ send_decline(iface);
+ close_sockets(iface);
+ delete_timeout(NULL, iface);
+ if (iface->state->lease.frominfo)
+ start_interface(iface);
+ else
+ add_timeout_sec(DHCP_ARP_FAIL, start_interface, iface);
+}
+
+static void
+handle_arp_packet(void *arg)
+{
+ struct interface *iface = arg;
+ uint8_t arp_buffer[ARP_LEN];
+ struct arphdr ar;
+ uint32_t reply_s;
+ uint32_t reply_t;
+ uint8_t *hw_s, *hw_t;
+ ssize_t bytes;
+ struct if_state *state = iface->state;
+ struct if_options *opts = state->options;
+ const char *hwaddr;
+ struct in_addr ina;
+
+ state->fail.s_addr = 0;
+ for(;;) {
+ bytes = get_raw_packet(iface, ETHERTYPE_ARP,
+ arp_buffer, sizeof(arp_buffer));
+ if (bytes == 0 || bytes == -1)
+ return;
+ /* We must have a full ARP header */
+ if ((size_t)bytes < sizeof(ar))
+ continue;
+ memcpy(&ar, arp_buffer, sizeof(ar));
+ /* Protocol must be IP. */
+ if (ar.ar_pro != htons(ETHERTYPE_IP))
+ continue;
+ if (ar.ar_pln != sizeof(reply_s))
+ continue;
+ /* Only these types are recognised */
+ if (ar.ar_op != htons(ARPOP_REPLY) &&
+ ar.ar_op != htons(ARPOP_REQUEST))
+ continue;
+
+ /* Get pointers to the hardware addreses */
+ hw_s = arp_buffer + sizeof(ar);
+ hw_t = hw_s + ar.ar_hln + ar.ar_pln;
+ /* Ensure we got all the data */
+ if ((hw_t + ar.ar_hln + ar.ar_pln) - arp_buffer > bytes)
+ continue;
+ /* Ignore messages from ourself */
+ if (ar.ar_hln == iface->hwlen &&
+ memcmp(hw_s, iface->hwaddr, iface->hwlen) == 0)
+ continue;
+ /* Copy out the IP addresses */
+ memcpy(&reply_s, hw_s + ar.ar_hln, ar.ar_pln);
+ memcpy(&reply_t, hw_t + ar.ar_hln, ar.ar_pln);
+
+ /* Check for arping */
+ if (state->arping_index &&
+ state->arping_index <= opts->arping_len &&
+ (reply_s == opts->arping[state->arping_index - 1] ||
+ (reply_s == 0 &&
+ reply_t == opts->arping[state->arping_index - 1])))
+ {
+ ina.s_addr = reply_s;
+ hwaddr = hwaddr_ntoa((unsigned char *)hw_s,
+ (size_t)ar.ar_hln);
+ syslog(LOG_INFO,
+ "%s: found %s on hardware address %s",
+ iface->name, inet_ntoa(ina), hwaddr);
+ if (select_profile(iface, hwaddr) == -1 &&
+ errno == ENOENT)
+ select_profile(iface, inet_ntoa(ina));
+ close_sockets(iface);
+ delete_timeout(NULL, iface);
+ start_interface(iface);
+ return;
+ }
+
+ /* Check for conflict */
+ if (state->offer &&
+ (reply_s == state->offer->yiaddr ||
+ (reply_s == 0 && reply_t == state->offer->yiaddr)))
+ state->fail.s_addr = state->offer->yiaddr;
+
+ /* Handle IPv4LL conflicts */
+ if (IN_LINKLOCAL(htonl(iface->addr.s_addr)) &&
+ (reply_s == iface->addr.s_addr ||
+ (reply_s == 0 && reply_t == iface->addr.s_addr)))
+ state->fail.s_addr = iface->addr.s_addr;
+
+ if (state->fail.s_addr) {
+ syslog(LOG_ERR, "%s: hardware address %s claims %s",
+ iface->name,
+ hwaddr_ntoa((unsigned char *)hw_s,
+ (size_t)ar.ar_hln),
+ inet_ntoa(state->fail));
+ errno = EEXIST;
+ handle_arp_failure(iface);
+ return;
+ }
+ }
+}
+
+void
+send_arp_announce(void *arg)
+{
+ struct interface *iface = arg;
+ struct if_state *state = iface->state;
+ struct timeval tv;
+
+ if (iface->arp_fd == -1) {
+ open_socket(iface, ETHERTYPE_ARP);
+ add_event(iface->arp_fd, handle_arp_packet, iface);
+ }
+ if (++state->claims < ANNOUNCE_NUM)
+ syslog(LOG_DEBUG,
+ "%s: sending ARP announce (%d of %d), "
+ "next in %d.00 seconds",
+ iface->name, state->claims, ANNOUNCE_NUM, ANNOUNCE_WAIT);
+ else
+ syslog(LOG_DEBUG,
+ "%s: sending ARP announce (%d of %d)",
+ iface->name, state->claims, ANNOUNCE_NUM);
+ if (send_arp(iface, ARPOP_REQUEST,
+ state->new->yiaddr, state->new->yiaddr) == -1)
+ syslog(LOG_ERR, "send_arp: %m");
+ if (state->claims < ANNOUNCE_NUM) {
+ add_timeout_sec(ANNOUNCE_WAIT, send_arp_announce, iface);
+ return;
+ }
+ if (state->new->cookie != htonl(MAGIC_COOKIE)) {
+ /* We should pretend to be at the end
+ * of the DHCP negotation cycle unless we rebooted */
+ if (state->interval != 0)
+ state->interval = 64;
+ state->probes = 0;
+ state->claims = 0;
+ tv.tv_sec = state->interval - DHCP_RAND_MIN;
+ tv.tv_usec = arc4random() % (DHCP_RAND_MAX_U - DHCP_RAND_MIN_U);
+ timernorm(&tv);
+ add_timeout_tv(&tv, start_discover, iface);
+ } else {
+ delete_event(iface->arp_fd);
+ close(iface->arp_fd);
+ iface->arp_fd = -1;
+ }
+}
+
+void
+send_arp_probe(void *arg)
+{
+ struct interface *iface = arg;
+ struct if_state *state = iface->state;
+ struct in_addr addr;
+ struct timeval tv;
+ int arping = 0;
+
+ if (state->arping_index < state->options->arping_len) {
+ addr.s_addr = state->options->arping[state->arping_index];
+ arping = 1;
+ } else if (state->offer) {
+ if (state->offer->yiaddr)
+ addr.s_addr = state->offer->yiaddr;
+ else
+ addr.s_addr = state->offer->ciaddr;
+ } else
+ addr.s_addr = iface->addr.s_addr;
+
+ if (iface->arp_fd == -1) {
+ open_socket(iface, ETHERTYPE_ARP);
+ add_event(iface->arp_fd, handle_arp_packet, iface);
+ }
+ if (state->probes == 0) {
+ if (arping)
+ syslog(LOG_INFO, "%s: searching for %s",
+ iface->name, inet_ntoa(addr));
+ else
+ syslog(LOG_INFO, "%s: checking for %s",
+ iface->name, inet_ntoa(addr));
+ }
+ if (++state->probes < PROBE_NUM) {
+ tv.tv_sec = PROBE_MIN;
+ tv.tv_usec = arc4random() % (PROBE_MAX_U - PROBE_MIN_U);
+ timernorm(&tv);
+ add_timeout_tv(&tv, send_arp_probe, iface);
+ } else {
+ tv.tv_sec = ANNOUNCE_WAIT;
+ tv.tv_usec = 0;
+ if (arping) {
+ state->probes = 0;
+ if (++state->arping_index < state->options->arping_len)
+ add_timeout_tv(&tv, send_arp_probe, iface);
+ else
+ add_timeout_tv(&tv, start_interface, iface);
+ } else
+ add_timeout_tv(&tv, bind_interface, iface);
+ }
+ syslog(LOG_DEBUG,
+ "%s: sending ARP probe (%d of %d), next in %0.2f seconds",
+ iface->name, state->probes ? state->probes : PROBE_NUM, PROBE_NUM,
+ timeval_to_double(&tv));
+ if (send_arp(iface, ARPOP_REQUEST, 0, addr.s_addr) == -1)
+ syslog(LOG_ERR, "send_arp: %m");
+}
+
+void
+start_arping(struct interface *iface)
+{
+ iface->state->probes = 0;
+ iface->state->arping_index = 0;
+ send_arp_probe(iface);
+}