/*
* dhcpcd - DHCP client daemon
* Copyright (c) 2006-2014 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 "config.h"
#include "arp.h"
#include "ipv4.h"
#include "common.h"
#include "dhcp.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
arp_send(const struct interface *ifp, 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;
ar.ar_hrd = htons(ifp->family);
ar.ar_pro = htons(ETHERTYPE_IP);
ar.ar_hln = ifp->hwlen;
ar.ar_pln = sizeof(sip);
ar.ar_op = htons(op);
p = arp_buffer;
len = sizeof(arp_buffer);
#define CHECK(fun, b, l) \
do { \
if (len < (l)) \
goto eexit; \
fun(p, (b), (l)); \
p += (l); \
len -= (l); \
} while (/* CONSTCOND */ 0)
#define APPEND(b, l) CHECK(memcpy, b, l)
#define ZERO(l) CHECK(memset, 0, l)
APPEND(&ar, sizeof(ar));
APPEND(ifp->hwaddr, ifp->hwlen);
APPEND(&sip, sizeof(sip));
ZERO(ifp->hwlen);
APPEND(&tip, sizeof(tip));
len = p - arp_buffer;
return ipv4_sendrawpacket(ifp, ETHERTYPE_ARP, arp_buffer, len);
eexit:
errno = ENOBUFS;
return -1;
}
static void
arp_failure(struct interface *ifp)
{
const struct dhcp_state *state = D_CSTATE(ifp);
/* If we failed without a magic cookie then we need to try
* and defend our IPv4LL address. */
if ((state->offer != NULL &&
state->offer->cookie != htonl(MAGIC_COOKIE)) ||
(state->new != NULL &&
state->new->cookie != htonl(MAGIC_COOKIE)))
{
ipv4ll_handle_failure(ifp);
return;
}
unlink(state->leasefile);
if (!state->lease.frominfo)
dhcp_decline(ifp);
dhcp_close(ifp);
eloop_timeout_delete(NULL, ifp);
if (state->lease.frominfo)
start_interface(ifp);
else
eloop_timeout_add_sec(DHCP_ARP_FAIL, start_interface, ifp);
}
static void
arp_packet(void *arg)
{
struct interface *ifp = 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 dhcp_state *state;
struct if_options *opts = ifp->options;
const char *hwaddr;
struct in_addr ina;
state = D_STATE(ifp);
state->fail.s_addr = 0;
for(;;) {
bytes = ipv4_getrawpacket(ifp, ETHERTYPE_ARP,
arp_buffer, sizeof(arp_buffer), NULL);
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 == ifp->hwlen &&
memcmp(hw_s, ifp->hwaddr, ifp->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",
ifp->name, inet_ntoa(ina), hwaddr);
if (select_profile(ifp, hwaddr) == -1 &&
errno == ENOENT)
select_profile(ifp, inet_ntoa(ina));
dhcp_close(ifp);
eloop_timeout_delete(NULL, ifp);
start_interface(ifp);
return;
}
/* RFC 2131 3.1.5, Client-server interaction
* RFC 3927 2.2.1, Probe Conflict Detection */
if (state->offer &&
(reply_s == state->offer->yiaddr ||
(reply_s == 0 && reply_t == state->offer->yiaddr)))
state->fail.s_addr = state->offer->yiaddr;
/* RFC 3927 2.5, Conflict Defense */
if (IN_LINKLOCAL(htonl(state->addr.s_addr)) &&
reply_s == state->addr.s_addr)
state->fail.s_addr = state->addr.s_addr;
if (state->fail.s_addr) {
syslog(LOG_ERR, "%s: hardware address %s claims %s",
ifp->name,
hwaddr_ntoa((unsigned char *)hw_s,
(size_t)ar.ar_hln),
inet_ntoa(state->fail));
errno = EEXIST;
arp_failure(ifp);
return;
}
}
}
void
arp_announce(void *arg)
{
struct interface *ifp = arg;
struct dhcp_state *state = D_STATE(ifp);
struct timeval tv;
if (state->new == NULL)
return;
if (state->arp_fd == -1) {
state->arp_fd = ipv4_opensocket(ifp, ETHERTYPE_ARP);
if (state->arp_fd == -1) {
syslog(LOG_ERR, "%s: %s: %m", __func__, ifp->name);
return;
}
eloop_event_add(state->arp_fd, arp_packet, ifp);
}
if (++state->claims < ANNOUNCE_NUM)
syslog(LOG_DEBUG,
"%s: sending ARP announce (%d of %d), "
"next in %d.0 seconds",
ifp->name, state->claims, ANNOUNCE_NUM, ANNOUNCE_WAIT);
else
syslog(LOG_DEBUG,
"%s: sending ARP announce (%d of %d)",
ifp->name, state->claims, ANNOUNCE_NUM);
if (arp_send(ifp, ARPOP_REQUEST,
state->new->yiaddr, state->new->yiaddr) == -1)
syslog(LOG_ERR, "send_arp: %m");
if (state->claims < ANNOUNCE_NUM) {
eloop_timeout_add_sec(ANNOUNCE_WAIT, arp_announce, ifp);
return;
}
if (state->new->cookie != htonl(MAGIC_COOKIE)) {
/* Check if doing DHCP */
if (!(ifp->options->options & DHCPCD_DHCP))
return;
/* 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);
eloop_timeout_add_tv(&tv, dhcp_discover, ifp);
} else {
eloop_event_delete(state->arp_fd);
close(state->arp_fd);
state->arp_fd = -1;
}
}
void
arp_probe(void *arg)
{
struct interface *ifp = arg;
struct dhcp_state *state = D_STATE(ifp);
struct in_addr addr;
struct timeval tv;
int arping = 0;
if (state->arp_fd == -1) {
state->arp_fd = ipv4_opensocket(ifp, ETHERTYPE_ARP);
if (state->arp_fd == -1) {
syslog(LOG_ERR, "%s: %s: %m", __func__, ifp->name);
return;
}
eloop_event_add(state->arp_fd, arp_packet, ifp);
}
if (state->arping_index < ifp->options->arping_len) {
addr.s_addr = ifp->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 = state->addr.s_addr;
if (state->probes == 0) {
if (arping)
syslog(LOG_DEBUG, "%s: searching for %s",
ifp->name, inet_ntoa(addr));
else
syslog(LOG_DEBUG, "%s: checking for %s",
ifp->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);
eloop_timeout_add_tv(&tv, arp_probe, ifp);
} else {
tv.tv_sec = ANNOUNCE_WAIT;
tv.tv_usec = 0;
if (arping) {
state->probes = 0;
if (++state->arping_index < ifp->options->arping_len)
eloop_timeout_add_tv(&tv, arp_probe, ifp);
else
eloop_timeout_add_tv(&tv, start_interface, ifp);
} else
eloop_timeout_add_tv(&tv, dhcp_bind, ifp);
}
syslog(LOG_DEBUG,
"%s: sending ARP probe (%d of %d), next in %0.1f seconds",
ifp->name, state->probes ? state->probes : PROBE_NUM, PROBE_NUM,
timeval_to_double(&tv));
if (arp_send(ifp, ARPOP_REQUEST, 0, addr.s_addr) == -1)
syslog(LOG_ERR, "send_arp: %m");
}
void
arp_start(struct interface *ifp)
{
struct dhcp_state *state = D_STATE(ifp);
state->probes = 0;
state->arping_index = 0;
arp_probe(ifp);
}
