Refactor the ARP code to be similar to the dhcp code -- timeout functions and
packet response functions are handled by an array of function pointers indexed by ARP state. Split arp_retransmit() apart into simpler functions. Fix a typo in renewing_timeout() that would result in too-short timeouts that would soak cpu. Call handle_arp_timeout() from the timeout_action() function rather than having explicit hooks in various <dhcpstate>_timeout() functions. Make the function pointer arrays static const.
This commit is contained in:
parent
8beb1d12d1
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1e71f82f3a
198
ndhc/arp.c
198
ndhc/arp.c
@ -1,5 +1,5 @@
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/* arp.c - arp ping checking
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* Time-stamp: <2011-07-06 11:39:23 njk>
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* Time-stamp: <2011-07-09 17:34:29 njk>
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*
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* Copyright 2010-2011 Nicholas J. Kain <njkain@gmail.com>
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*
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@ -524,8 +524,7 @@ static int arp_gen_probe_wait(void)
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return PROBE_MIN + rand() % (PROBE_MAX - PROBE_MIN);
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}
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// Perform retransmission if necessary.
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void arp_retransmit(struct client_state_t *cs)
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static void arp_defense_timeout(struct client_state_t *cs)
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{
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if (pending_def_ts) {
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log_line("arp: Defending our lease IP.");
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@ -537,42 +536,48 @@ void arp_retransmit(struct client_state_t *cs)
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def_old_oldTimeout = 0;
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}
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}
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if (arpState == AS_GW_CHECK || arpState == AS_GW_QUERY) {
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if (arpState == AS_GW_CHECK && act_if_arp_gw_failed(cs))
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return;
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long long cms = curms();
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long long rtts = arp_send_stats[ASEND_GW_PING].ts + ARP_RETRANS_DELAY;
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if (cms < rtts) {
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cs->timeout = rtts - cms;
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return;
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}
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log_line(arpState == AS_GW_CHECK ?
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"arp: Still waiting for gateway to reply to arp ping..." :
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"arp: Still looking for gateway hardware address...");
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if (arp_ping(cs, cs->routerAddr) == -1)
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log_warning("arp: Failed to send ARP ping in retransmission.");
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cs->timeout = ARP_RETRANS_DELAY;
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}
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static void arp_check_timeout(struct client_state_t *cs)
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{
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arp_defense_timeout(cs);
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if (arpState == AS_GW_CHECK && act_if_arp_gw_failed(cs))
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return;
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long long cms = curms();
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long long rtts = arp_send_stats[ASEND_GW_PING].ts + ARP_RETRANS_DELAY;
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if (cms < rtts) {
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cs->timeout = rtts - cms;
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return;
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}
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if (arpState == AS_COLLISION_CHECK) {
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long long cms = curms();
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if (cms >= collision_check_init_ts + ANNOUNCE_WAIT ||
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arp_send_stats[ASEND_COLLISION_CHECK].count >= PROBE_NUM) {
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arp_success(cs);
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return;
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}
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long long rtts = arp_send_stats[ASEND_COLLISION_CHECK].ts +
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probe_wait_time;
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if (cms < rtts) {
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cs->timeout = rtts - cms;
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return;
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}
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log_line("arp: Probing for hosts that may conflict with our lease...");
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if (arp_ip_anon_ping(cs, arp_dhcp_packet.yiaddr) == -1)
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log_warning("arp: Failed to send ARP ping in retransmission.");
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cs->timeout = probe_wait_time = arp_gen_probe_wait();
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log_line(arpState == AS_GW_CHECK ?
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"arp: Still waiting for gateway to reply to arp ping..." :
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"arp: Still looking for gateway hardware address...");
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if (arp_ping(cs, cs->routerAddr) == -1)
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log_warning("arp: Failed to send ARP ping in retransmission.");
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cs->timeout = ARP_RETRANS_DELAY;
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}
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static void arp_collision_timeout(struct client_state_t *cs)
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{
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arp_defense_timeout(cs);
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long long cms = curms();
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if (cms >= collision_check_init_ts + ANNOUNCE_WAIT ||
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arp_send_stats[ASEND_COLLISION_CHECK].count >= PROBE_NUM) {
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arp_success(cs);
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return;
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}
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long long rtts = arp_send_stats[ASEND_COLLISION_CHECK].ts +
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probe_wait_time;
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if (cms < rtts) {
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cs->timeout = rtts - cms;
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return;
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}
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log_line("arp: Probing for hosts that may conflict with our lease...");
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if (arp_ip_anon_ping(cs, arp_dhcp_packet.yiaddr) == -1)
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log_warning("arp: Failed to send ARP ping in retransmission.");
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cs->timeout = probe_wait_time = arp_gen_probe_wait();
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}
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static void arp_do_defense(struct client_state_t *cs)
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@ -600,6 +605,72 @@ static void arp_do_defense(struct client_state_t *cs)
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last_conflict_ts = cur_conflict_ts;
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}
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static void arp_do_gw_query(struct client_state_t *cs)
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{
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if (arp_is_query_reply(&arpreply) &&
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!memcmp(arpreply.sip4, &cs->routerAddr, 4)) {
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cs->timeout = cs->oldTimeout;
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memcpy(cs->routerArp, arpreply.smac, 6);
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log_line("arp: Gateway hardware address %02x:%02x:%02x:%02x:%02x:%02x",
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cs->routerArp[0], cs->routerArp[1],
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cs->routerArp[2], cs->routerArp[3],
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cs->routerArp[4], cs->routerArp[5]);
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arp_switch_state(cs, AS_DEFENSE);
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arp_announcement(cs); // Do a second announcement.
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return;
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}
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if (!arp_validate_bpf_defense(cs, &arpreply))
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return;
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arp_do_defense(cs);
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}
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static void arp_do_collision_check(struct client_state_t *cs)
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{
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if (!arp_is_query_reply(&arpreply))
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return;
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// If this packet was sent from our lease IP, and does not have a
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// MAC address matching our own (the latter check guards against stupid
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// hubs or repeaters), then it's a conflict and thus a failure.
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if (!memcmp(arpreply.sip4, &arp_dhcp_packet.yiaddr, 4) &&
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!memcmp(client_config.arp, arpreply.smac, 6)) {
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total_conflicts++;
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arp_failed(cs);
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}
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}
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static void arp_do_gw_check(struct client_state_t *cs)
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{
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if (!arp_is_query_reply(&arpreply))
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return;
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if (!memcmp(arpreply.sip4, &cs->routerAddr, 4)) {
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// Success only if the router/gw MAC matches stored value
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if (!memcmp(cs->routerArp, arpreply.smac, 6))
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arp_gw_success(cs);
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else
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arp_gw_failed(cs);
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}
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}
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static void arp_do_invalid(struct client_state_t *cs)
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{
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log_error("handle_arp_response: called in invalid state %u", arpState);
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arp_close_fd(cs);
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}
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typedef struct {
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void (*packet_fn)(struct client_state_t *cs);
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void (*timeout_fn)(struct client_state_t *cs);
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} arp_state_fn_t;
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static const arp_state_fn_t arp_states[] = {
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{ arp_do_invalid, 0 }, // AS_NONE
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{ arp_do_collision_check, arp_collision_timeout }, // AS_COLLISION_CHECK
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{ arp_do_gw_check, arp_check_timeout }, // AS_GW_CHECK
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{ arp_do_gw_query, arp_check_timeout }, // AS_GW_QUERY
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{ arp_do_defense, arp_defense_timeout }, // AS_DEFENSE
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{ arp_do_invalid, 0 }, // AS_MAX
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};
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void handle_arp_response(struct client_state_t *cs)
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{
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int r = 0;
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@ -620,7 +691,7 @@ void handle_arp_response(struct client_state_t *cs)
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}
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if (r <= 0) {
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arp_retransmit(cs);
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handle_arp_timeout(cs);
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return;
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}
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@ -635,51 +706,14 @@ void handle_arp_response(struct client_state_t *cs)
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return;
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}
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switch (arpState) {
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case AS_COLLISION_CHECK:
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if (!arp_is_query_reply(&arpreply))
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break;
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// If this packet was sent from our lease IP, and does not have a
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// MAC address matching our own (the latter check guards against stupid
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// hubs or repeaters), then it's a conflict and thus a failure.
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if (!memcmp(arpreply.sip4, &arp_dhcp_packet.yiaddr, 4) &&
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!memcmp(client_config.arp, arpreply.smac, 6)) {
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total_conflicts++;
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arp_failed(cs);
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}
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break;
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case AS_GW_CHECK:
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if (!arp_is_query_reply(&arpreply))
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break;
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if (!memcmp(arpreply.sip4, &cs->routerAddr, 4)) {
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// Success only if the router/gw MAC matches stored value
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if (!memcmp(cs->routerArp, arpreply.smac, 6))
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arp_gw_success(cs);
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else
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arp_gw_failed(cs);
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}
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break;
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case AS_GW_QUERY:
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if (arp_is_query_reply(&arpreply) &&
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!memcmp(arpreply.sip4, &cs->routerAddr, 4)) {
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cs->timeout = cs->oldTimeout;
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memcpy(cs->routerArp, arpreply.smac, 6);
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log_line("arp: Gateway hardware address %02x:%02x:%02x:%02x:%02x:%02x",
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cs->routerArp[0], cs->routerArp[1],
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cs->routerArp[2], cs->routerArp[3],
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cs->routerArp[4], cs->routerArp[5]);
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arp_switch_state(cs, AS_DEFENSE);
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arp_announcement(cs); // Do a second announcement.
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break;
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}
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if (!arp_validate_bpf_defense(cs, &arpreply))
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break;
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case AS_DEFENSE:
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arp_do_defense(cs);
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break;
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default:
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log_error("handle_arp_response: called in invalid state %u", arpState);
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arp_close_fd(cs);
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}
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if (arp_states[arpState].packet_fn)
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arp_states[arpState].packet_fn(cs);
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arpreply_clear();
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}
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// Perform retransmission if necessary.
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void handle_arp_timeout(struct client_state_t *cs)
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{
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if (arp_states[arpState].timeout_fn)
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arp_states[arpState].timeout_fn(cs);
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}
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@ -1,5 +1,5 @@
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/* arp.h - functions to call the interface change daemon
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* Time-stamp: <2011-07-06 11:39:42 njk>
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* Time-stamp: <2011-07-09 15:39:46 njk>
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*
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* Copyright 2010-2011 Nicholas J. Kain <njkain@gmail.com>
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*
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@ -53,7 +53,7 @@ int arp_check(struct client_state_t *cs, struct dhcpmsg *packet);
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int arp_gw_check(struct client_state_t *cs);
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void arp_set_defense_mode(struct client_state_t *cs);
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void arp_success(struct client_state_t *cs);
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void arp_retransmit(struct client_state_t *cs);
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void handle_arp_response(struct client_state_t *cs);
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void handle_arp_timeout(struct client_state_t *cs);
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#endif /* ARP_H_ */
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23
ndhc/state.c
23
ndhc/state.c
@ -22,8 +22,6 @@ static void bound_timeout(struct client_state_t *cs);
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static void renewing_timeout(struct client_state_t *cs);
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static void rebinding_timeout(struct client_state_t *cs);
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static void released_timeout(struct client_state_t *cs);
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static void collision_check_timeout(struct client_state_t *cs);
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static void bound_gw_check_timeout(struct client_state_t *cs);
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static void xmit_release(struct client_state_t *cs);
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static void print_release(struct client_state_t *cs);
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static void frenew(struct client_state_t *cs);
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@ -36,14 +34,14 @@ typedef struct {
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void (*force_release_fn)(struct client_state_t *cs);
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} dhcp_state_t;
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dhcp_state_t dhcp_states[] = {
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static const dhcp_state_t dhcp_states[] = {
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{ selecting_packet, selecting_timeout, 0, print_release}, // SELECTING
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{ an_packet, requesting_timeout, 0, print_release}, // REQUESTING
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{ 0, bound_timeout, frenew, xmit_release}, // BOUND
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{ an_packet, renewing_timeout, 0, xmit_release}, // RENEWING
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{ an_packet, rebinding_timeout, 0, xmit_release}, // REBINDING
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{ 0, bound_gw_check_timeout, 0, xmit_release}, // BOUND_GW_CHECK
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{ 0, collision_check_timeout, 0, xmit_release}, // COLLISION_CHECK
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{ 0, 0, 0, xmit_release}, // BOUND_GW_CHECK
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{ 0, 0, 0, xmit_release}, // COLLISION_CHECK
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{ 0, released_timeout, frenew, 0}, // RELEASED
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{ 0, 0, 0, 0}, // NUM_STATES
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};
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@ -101,8 +99,6 @@ static void requesting_timeout(struct client_state_t *cs)
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// total time, and it is time to renew the lease so that it is not lost.
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static void bound_timeout(struct client_state_t *cs)
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{
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arp_retransmit(cs);
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if (curms() < cs->leaseStartTime + cs->renewTime * 1000)
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return;
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cs->dhcpState = DS_RENEWING;
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@ -139,7 +135,7 @@ static void renewing_timeout(struct client_state_t *cs)
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long long elt = cs->leaseStartTime + cs->lease * 1000;
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if (ct < elt) {
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cs->dhcpState = DS_REBINDING;
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cs->timeout = elt - ct / 2;
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cs->timeout = (elt - ct) / 2;
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log_line("Entering rebinding state.");
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} else
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lease_timedout(cs);
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@ -169,16 +165,6 @@ static void released_timeout(struct client_state_t *cs)
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cs->timeout = -1;
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}
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static void collision_check_timeout(struct client_state_t *cs)
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{
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arp_retransmit(cs);
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}
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static void bound_gw_check_timeout(struct client_state_t *cs)
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{
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arp_retransmit(cs);
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}
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// Can transition to DS_BOUND or DS_SELECTING.
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static void an_packet(struct client_state_t *cs, struct dhcpmsg *packet,
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uint8_t *message)
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@ -332,6 +318,7 @@ void packet_action(struct client_state_t *cs, struct dhcpmsg *packet,
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void timeout_action(struct client_state_t *cs)
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{
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handle_arp_timeout(cs);
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if (dhcp_states[cs->dhcpState].timeout_fn)
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dhcp_states[cs->dhcpState].timeout_fn(cs);
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}
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