347 lines
8.4 KiB
C
347 lines
8.4 KiB
C
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/*
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* RFC3927 ZeroConf IPv4 Link-Local addressing
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* (see <http://www.zeroconf.org/>)
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*
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* Copied from BusyBox - networking/zcip.c
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*
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* Copyright (C) 2003 by Arthur van Hoff (avh@strangeberry.com)
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* Copyright (C) 2004 by David Brownell
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* Copyright (C) 2010 by Joe Hershberger
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*
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* Licensed under the GPL v2 or later
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*/
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#include <common.h>
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#include <net.h>
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#include "arp.h"
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#include "net_rand.h"
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/* We don't need more than 32 bits of the counter */
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#define MONOTONIC_MS() ((unsigned)get_timer(0) * (1000 / CONFIG_SYS_HZ))
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enum {
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/* 169.254.0.0 */
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LINKLOCAL_ADDR = 0xa9fe0000,
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IN_CLASSB_NET = 0xffff0000,
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IN_CLASSB_HOST = 0x0000ffff,
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/* protocol timeout parameters, specified in seconds */
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PROBE_WAIT = 1,
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PROBE_MIN = 1,
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PROBE_MAX = 2,
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PROBE_NUM = 3,
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MAX_CONFLICTS = 10,
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RATE_LIMIT_INTERVAL = 60,
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ANNOUNCE_WAIT = 2,
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ANNOUNCE_NUM = 2,
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ANNOUNCE_INTERVAL = 2,
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DEFEND_INTERVAL = 10
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};
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/* States during the configuration process. */
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static enum ll_state_t {
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PROBE = 0,
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RATE_LIMIT_PROBE,
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ANNOUNCE,
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MONITOR,
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DEFEND,
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DISABLED
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} state = DISABLED;
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static struct in_addr ip;
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static int timeout_ms = -1;
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static unsigned deadline_ms;
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static unsigned conflicts;
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static unsigned nprobes;
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static unsigned nclaims;
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static int ready;
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static unsigned int seed;
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static void link_local_timeout(void);
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/**
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* Pick a random link local IP address on 169.254/16, except that
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* the first and last 256 addresses are reserved.
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*/
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static struct in_addr pick(void)
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{
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unsigned tmp;
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struct in_addr ip;
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do {
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tmp = rand_r(&seed) & IN_CLASSB_HOST;
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} while (tmp > (IN_CLASSB_HOST - 0x0200));
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ip.s_addr = htonl((LINKLOCAL_ADDR + 0x0100) + tmp);
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return ip;
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}
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/**
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* Return milliseconds of random delay, up to "secs" seconds.
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*/
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static inline unsigned random_delay_ms(unsigned secs)
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{
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return rand_r(&seed) % (secs * 1000);
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}
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static void configure_wait(void)
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{
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if (timeout_ms == -1)
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return;
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/* poll, being ready to adjust current timeout */
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if (!timeout_ms)
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timeout_ms = random_delay_ms(PROBE_WAIT);
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/* set deadline_ms to the point in time when we timeout */
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deadline_ms = MONOTONIC_MS() + timeout_ms;
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debug_cond(DEBUG_DEV_PKT, "...wait %d %s nprobes=%u, nclaims=%u\n",
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timeout_ms, eth_get_name(), nprobes, nclaims);
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net_set_timeout_handler(timeout_ms, link_local_timeout);
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}
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void link_local_start(void)
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{
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ip = env_get_ip("llipaddr");
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if (ip.s_addr != 0 &&
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(ntohl(ip.s_addr) & IN_CLASSB_NET) != LINKLOCAL_ADDR) {
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puts("invalid link address");
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net_set_state(NETLOOP_FAIL);
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return;
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}
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net_netmask.s_addr = htonl(IN_CLASSB_NET);
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seed = seed_mac();
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if (ip.s_addr == 0)
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ip = pick();
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state = PROBE;
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timeout_ms = 0;
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conflicts = 0;
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nprobes = 0;
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nclaims = 0;
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ready = 0;
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configure_wait();
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}
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static void link_local_timeout(void)
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{
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switch (state) {
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case PROBE:
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/* timeouts in the PROBE state mean no conflicting ARP packets
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have been received, so we can progress through the states */
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if (nprobes < PROBE_NUM) {
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struct in_addr zero_ip = {.s_addr = 0};
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nprobes++;
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debug_cond(DEBUG_LL_STATE, "probe/%u %s@%pI4\n",
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nprobes, eth_get_name(), &ip);
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arp_raw_request(zero_ip, net_null_ethaddr, ip);
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timeout_ms = PROBE_MIN * 1000;
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timeout_ms += random_delay_ms(PROBE_MAX - PROBE_MIN);
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} else {
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/* Switch to announce state */
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state = ANNOUNCE;
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nclaims = 0;
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debug_cond(DEBUG_LL_STATE, "announce/%u %s@%pI4\n",
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nclaims, eth_get_name(), &ip);
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arp_raw_request(ip, net_ethaddr, ip);
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timeout_ms = ANNOUNCE_INTERVAL * 1000;
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}
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break;
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case RATE_LIMIT_PROBE:
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/* timeouts in the RATE_LIMIT_PROBE state mean no conflicting
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ARP packets have been received, so we can move immediately
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to the announce state */
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state = ANNOUNCE;
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nclaims = 0;
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debug_cond(DEBUG_LL_STATE, "announce/%u %s@%pI4\n",
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nclaims, eth_get_name(), &ip);
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arp_raw_request(ip, net_ethaddr, ip);
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timeout_ms = ANNOUNCE_INTERVAL * 1000;
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break;
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case ANNOUNCE:
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/* timeouts in the ANNOUNCE state mean no conflicting ARP
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packets have been received, so we can progress through
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the states */
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if (nclaims < ANNOUNCE_NUM) {
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nclaims++;
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debug_cond(DEBUG_LL_STATE, "announce/%u %s@%pI4\n",
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nclaims, eth_get_name(), &ip);
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arp_raw_request(ip, net_ethaddr, ip);
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timeout_ms = ANNOUNCE_INTERVAL * 1000;
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} else {
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/* Switch to monitor state */
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state = MONITOR;
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printf("Successfully assigned %pI4\n", &ip);
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net_copy_ip(&net_ip, &ip);
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ready = 1;
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conflicts = 0;
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timeout_ms = -1;
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/* Never timeout in the monitor state */
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net_set_timeout_handler(0, NULL);
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/* NOTE: all other exit paths should deconfig ... */
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net_set_state(NETLOOP_SUCCESS);
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return;
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}
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break;
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case DEFEND:
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/* We won! No ARP replies, so just go back to monitor */
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state = MONITOR;
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timeout_ms = -1;
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conflicts = 0;
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break;
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default:
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/* Invalid, should never happen. Restart the whole protocol */
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state = PROBE;
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ip = pick();
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timeout_ms = 0;
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nprobes = 0;
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nclaims = 0;
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break;
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}
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configure_wait();
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}
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void link_local_receive_arp(struct arp_hdr *arp, int len)
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{
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int source_ip_conflict;
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int target_ip_conflict;
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struct in_addr null_ip = {.s_addr = 0};
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if (state == DISABLED)
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return;
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/* We need to adjust the timeout in case we didn't receive a
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conflicting packet. */
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if (timeout_ms > 0) {
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unsigned diff = deadline_ms - MONOTONIC_MS();
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if ((int)(diff) < 0) {
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/* Current time is greater than the expected timeout
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time. This should never happen */
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debug_cond(DEBUG_LL_STATE,
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"missed an expected timeout\n");
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timeout_ms = 0;
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} else {
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debug_cond(DEBUG_INT_STATE, "adjusting timeout\n");
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timeout_ms = diff | 1; /* never 0 */
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}
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}
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#if 0
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/* XXX Don't bother with ethernet link just yet */
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if ((fds[0].revents & POLLIN) == 0) {
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if (fds[0].revents & POLLERR) {
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/*
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* FIXME: links routinely go down;
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*/
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bb_error_msg("iface %s is down", eth_get_name());
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if (ready)
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run(argv, "deconfig", &ip);
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return EXIT_FAILURE;
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}
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continue;
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}
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#endif
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debug_cond(DEBUG_INT_STATE, "%s recv arp type=%d, op=%d,\n",
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eth_get_name(), ntohs(arp->ar_pro),
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ntohs(arp->ar_op));
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debug_cond(DEBUG_INT_STATE, "\tsource=%pM %pI4\n",
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&arp->ar_sha,
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&arp->ar_spa);
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debug_cond(DEBUG_INT_STATE, "\ttarget=%pM %pI4\n",
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&arp->ar_tha,
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&arp->ar_tpa);
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if (arp->ar_op != htons(ARPOP_REQUEST) &&
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arp->ar_op != htons(ARPOP_REPLY)) {
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configure_wait();
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return;
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}
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source_ip_conflict = 0;
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target_ip_conflict = 0;
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if (memcmp(&arp->ar_spa, &ip, ARP_PLEN) == 0 &&
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memcmp(&arp->ar_sha, net_ethaddr, ARP_HLEN) != 0)
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source_ip_conflict = 1;
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/*
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* According to RFC 3927, section 2.2.1:
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* Check if packet is an ARP probe by checking for a null source IP
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* then check that target IP is equal to ours and source hw addr
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* is not equal to ours. This condition should cause a conflict only
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* during probe.
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*/
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if (arp->ar_op == htons(ARPOP_REQUEST) &&
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memcmp(&arp->ar_spa, &null_ip, ARP_PLEN) == 0 &&
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memcmp(&arp->ar_tpa, &ip, ARP_PLEN) == 0 &&
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memcmp(&arp->ar_sha, net_ethaddr, ARP_HLEN) != 0) {
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target_ip_conflict = 1;
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}
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debug_cond(DEBUG_NET_PKT,
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"state = %d, source ip conflict = %d, target ip conflict = "
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"%d\n", state, source_ip_conflict, target_ip_conflict);
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switch (state) {
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case PROBE:
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case ANNOUNCE:
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/* When probing or announcing, check for source IP conflicts
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and other hosts doing ARP probes (target IP conflicts). */
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if (source_ip_conflict || target_ip_conflict) {
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conflicts++;
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state = PROBE;
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if (conflicts >= MAX_CONFLICTS) {
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debug("%s ratelimit\n", eth_get_name());
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timeout_ms = RATE_LIMIT_INTERVAL * 1000;
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state = RATE_LIMIT_PROBE;
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}
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/* restart the whole protocol */
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ip = pick();
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timeout_ms = 0;
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nprobes = 0;
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nclaims = 0;
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}
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break;
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case MONITOR:
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/* If a conflict, we try to defend with a single ARP probe */
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if (source_ip_conflict) {
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debug("monitor conflict -- defending\n");
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state = DEFEND;
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timeout_ms = DEFEND_INTERVAL * 1000;
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arp_raw_request(ip, net_ethaddr, ip);
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}
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break;
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case DEFEND:
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/* Well, we tried. Start over (on conflict) */
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if (source_ip_conflict) {
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state = PROBE;
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debug("defend conflict -- starting over\n");
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ready = 0;
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net_ip.s_addr = 0;
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/* restart the whole protocol */
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ip = pick();
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timeout_ms = 0;
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nprobes = 0;
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nclaims = 0;
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}
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break;
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default:
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/* Invalid, should never happen. Restart the whole protocol */
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debug("invalid state -- starting over\n");
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state = PROBE;
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ip = pick();
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timeout_ms = 0;
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nprobes = 0;
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nclaims = 0;
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break;
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}
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configure_wait();
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}
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