From a4d564ad7c24df2da1d8e03a7dd016f0a3d5edbd Mon Sep 17 00:00:00 2001 From: Ken Sharp Date: Sun, 20 Jul 2014 14:01:49 +0200 Subject: zcip: fix link-local IP conflict detection During link-local IP resolution, if a regular ARP request is received during the ARP probe period, it will incorrectly cause a target IP conflict. This then leads to a new IP being picked unnecessarily. Per RFC 3927, section 2.2.1, we should flag a target IP conflict only if the source IP is null, the target IP matches our IP, and the source hw addr does not match our hw addr. function old new delta zcip_main 1354 1322 -32 Signed-off-by: Ken Sharp Signed-off-by: Ben Shelton Signed-off-by: Denys Vlasenko --- networking/zcip.c | 38 ++++++++++++++++++++++---------------- 1 file changed, 22 insertions(+), 16 deletions(-) (limited to 'networking') diff --git a/networking/zcip.c b/networking/zcip.c index 7314ff8db..45d1f7c1c 100644 --- a/networking/zcip.c +++ b/networking/zcip.c @@ -366,11 +366,11 @@ int zcip_main(int argc UNUSED_PARAM, char **argv) nprobes++; VDBG("probe/%u %s@%s\n", nprobes, argv_intf, inet_ntoa(ip)); + timeout_ms = PROBE_MIN * 1000; + timeout_ms += random_delay_ms(PROBE_MAX - PROBE_MIN); arp(/* ARPOP_REQUEST, */ /* ð_addr, */ null_ip, &null_addr, ip); - timeout_ms = PROBE_MIN * 1000; - timeout_ms += random_delay_ms(PROBE_MAX - PROBE_MIN); } else { // Switch to announce state. @@ -378,10 +378,10 @@ int zcip_main(int argc UNUSED_PARAM, char **argv) nclaims = 0; VDBG("announce/%u %s@%s\n", nclaims, argv_intf, inet_ntoa(ip)); + timeout_ms = ANNOUNCE_INTERVAL * 1000; arp(/* ARPOP_REQUEST, */ /* ð_addr, */ ip, ð_addr, ip); - timeout_ms = ANNOUNCE_INTERVAL * 1000; } break; case RATE_LIMIT_PROBE: @@ -391,10 +391,10 @@ int zcip_main(int argc UNUSED_PARAM, char **argv) nclaims = 0; VDBG("announce/%u %s@%s\n", nclaims, argv_intf, inet_ntoa(ip)); + timeout_ms = ANNOUNCE_INTERVAL * 1000; arp(/* ARPOP_REQUEST, */ /* ð_addr, */ ip, ð_addr, ip); - timeout_ms = ANNOUNCE_INTERVAL * 1000; break; case ANNOUNCE: // timeouts in the ANNOUNCE state mean no conflicting ARP packets @@ -403,10 +403,10 @@ int zcip_main(int argc UNUSED_PARAM, char **argv) nclaims++; VDBG("announce/%u %s@%s\n", nclaims, argv_intf, inet_ntoa(ip)); + timeout_ms = ANNOUNCE_INTERVAL * 1000; arp(/* ARPOP_REQUEST, */ /* ð_addr, */ ip, ð_addr, ip); - timeout_ms = ANNOUNCE_INTERVAL * 1000; } else { // Switch to monitor state. @@ -495,22 +495,28 @@ int zcip_main(int argc UNUSED_PARAM, char **argv) } #endif if (p.arp.arp_op != htons(ARPOP_REQUEST) - && p.arp.arp_op != htons(ARPOP_REPLY)) + && p.arp.arp_op != htons(ARPOP_REPLY) + ) { continue; + } source_ip_conflict = 0; target_ip_conflict = 0; - if (memcmp(p.arp.arp_spa, &ip.s_addr, sizeof(struct in_addr)) == 0 - && memcmp(&p.arp.arp_sha, ð_addr, ETH_ALEN) != 0 - ) { - source_ip_conflict = 1; - } - if (p.arp.arp_op == htons(ARPOP_REQUEST) - && memcmp(p.arp.arp_tpa, &ip.s_addr, sizeof(struct in_addr)) == 0 - && memcmp(&p.arp.arp_tha, ð_addr, ETH_ALEN) != 0 - ) { - target_ip_conflict = 1; + if (memcmp(&p.arp.arp_sha, ð_addr, ETH_ALEN) != 0) { + if (memcmp(p.arp.arp_spa, &ip.s_addr, sizeof(struct in_addr))) { + /* A probe or reply with source_ip == chosen ip */ + source_ip_conflict = 1; + } + if (p.arp.arp_op == htons(ARPOP_REQUEST) + && memcmp(p.arp.arp_spa, &null_ip, sizeof(struct in_addr)) == 0 + && memcmp(p.arp.arp_tpa, &ip.s_addr, sizeof(struct in_addr)) == 0 + ) { + /* A probe with source_ip == 0.0.0.0, target_ip == chosen ip: + * another host trying to claim this ip! + */ + target_ip_conflict = 1; + } } VDBG("state = %d, source ip conflict = %d, target ip conflict = %d\n", -- cgit v1.2.3