source: rtems-libbsd/dhcpcd/ipv4ll.c @ 1f7037d

/*
 * 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 "common.h"
#include "dhcp.h"
#include "eloop.h"
#include "if-options.h"
#include "ipv4ll.h"
#include "net.h"

static struct dhcp_message *
ipv4ll_make_lease(uint32_t addr)
{
        uint32_t u32;
        struct dhcp_message *dhcp;
        uint8_t *p;

        dhcp = calloc(1, sizeof(*dhcp));
        if (dhcp == NULL)
                return NULL;
        /* Put some LL options in */
        dhcp->yiaddr = addr;
        p = dhcp->options;
        *p++ = DHO_SUBNETMASK;
        *p++ = sizeof(u32);
        u32 = htonl(LINKLOCAL_MASK);
        memcpy(p, &u32, sizeof(u32));
        p += sizeof(u32);
        *p++ = DHO_BROADCAST;
        *p++ = sizeof(u32);
        u32 = htonl(LINKLOCAL_BRDC);
        memcpy(p, &u32, sizeof(u32));
        p += sizeof(u32);
        *p++ = DHO_END;

        return dhcp;
}

static struct dhcp_message *
ipv4ll_find_lease(uint32_t old_addr)
{
        uint32_t addr;

        for (;;) {
                addr = htonl(LINKLOCAL_ADDR |
                    (((uint32_t)abs((int)arc4random())
                        % 0xFD00) + 0x0100));
                if (addr != old_addr &&
                    IN_LINKLOCAL(ntohl(addr)))
                        break;
        }
        return ipv4ll_make_lease(addr);
}

void
ipv4ll_start(void *arg)
{
        struct interface *ifp = arg;
        struct dhcp_state *state = D_STATE(ifp);
        uint32_t addr;

        eloop_timeout_delete(NULL, ifp);
        state->probes = 0;
        state->claims = 0;
        if (state->addr.s_addr) {
                state->conflicts = 0;
                if (IN_LINKLOCAL(htonl(state->addr.s_addr))) {
                        arp_announce(ifp);
                        return;
                }
        }

        if (state->offer == NULL)
                addr = 0;
        else {
                addr = state->offer->yiaddr;
                free(state->offer);
        }
        /* We maybe rebooting an IPv4LL address. */
        if (!IN_LINKLOCAL(htonl(addr))) {
                syslog(LOG_INFO, "%s: probing for an IPv4LL address",
                    ifp->name);
                addr = 0;
        }
        if (addr == 0)
                state->offer = ipv4ll_find_lease(addr);
        else
                state->offer = ipv4ll_make_lease(addr);
        if (state->offer == NULL)
                syslog(LOG_ERR, "%s: %m", __func__);
        else {
                state->lease.frominfo = 0;
                arp_probe(ifp);
        }
}

void
ipv4ll_handle_failure(void *arg)
{
        struct interface *ifp = arg;
        struct dhcp_state *state = D_STATE(ifp);
        time_t up;

        if (state->fail.s_addr == state->addr.s_addr) {
                /* RFC 3927 Section 2.5 */
                up = uptime();
                if (state->defend + DEFEND_INTERVAL > up) {
                        syslog(LOG_WARNING,
                            "%s: IPv4LL %d second defence failed",
                            ifp->name, DEFEND_INTERVAL);
                        dhcp_drop(ifp, "EXPIRE");
                        state->conflicts = -1;
                } else {
                        syslog(LOG_DEBUG, "%s: defended IPv4LL address",
                            ifp->name);
                        state->defend = up;
                        return;
                }
        }

        dhcp_close(ifp);
        free(state->offer);
        state->offer = NULL;
        eloop_timeout_delete(NULL, ifp);
        if (++state->conflicts > MAX_CONFLICTS) {
                syslog(LOG_ERR, "%s: failed to acquire an IPv4LL address",
                    ifp->name);
                if (ifp->options->options & DHCPCD_DHCP) {
                        state->interval = RATE_LIMIT_INTERVAL / 2;
                        dhcp_discover(ifp);
                } else
                        eloop_timeout_add_sec(RATE_LIMIT_INTERVAL,
                            ipv4ll_start, ifp);
        } else {
                eloop_timeout_add_sec(PROBE_WAIT, ipv4ll_start, ifp);
        }
}