diff --git a/networking/zcip.c b/networking/zcip.c index 69644b230..5877a8317 100644 --- a/networking/zcip.c +++ b/networking/zcip.c @@ -215,19 +215,17 @@ int zcip_main(int argc UNUSED_PARAM, char **argv) const struct ether_addr null_addr; struct ifreq ifr; uint32_t chosen_nip; - int timeout_ms; /* must be signed */ + int timeout_ms; // must be signed unsigned conflicts; - unsigned nprobes; - unsigned nclaims; + unsigned nsent; int verbose; } L; #define null_addr (L.null_addr ) -#define chosen_nip (L.chosen_nip) #define ifr (L.ifr ) +#define chosen_nip (L.chosen_nip) #define timeout_ms (L.timeout_ms) #define conflicts (L.conflicts ) -#define nprobes (L.nprobes ) -#define nclaims (L.nclaims ) +#define nsent (L.nsent ) #define verbose (L.verbose ) memset(&L, 0, sizeof(L)); @@ -351,8 +349,7 @@ int zcip_main(int argc UNUSED_PARAM, char **argv) struct pollfd fds[1]; unsigned deadline_us; struct arp_packet p; - int source_ip_conflict; - int target_ip_conflict; + int ip_conflict; fds[0].fd = sock_fd; fds[0].events = POLLIN; @@ -368,8 +365,8 @@ int zcip_main(int argc UNUSED_PARAM, char **argv) // set deadline_us to the point in time when we timeout deadline_us = MONOTONIC_US() + timeout_ms * 1000; - VDBG("...wait %d %s nprobes=%u, nclaims=%u\n", - timeout_ms, argv_intf, nprobes, nclaims); + VDBG("...wait %d %s nsent=%u\n", + timeout_ms, argv_intf, nsent); switch (safe_poll(fds, 1, timeout_ms)) { @@ -384,10 +381,10 @@ int zcip_main(int argc UNUSED_PARAM, char **argv) case PROBE: // timeouts in the PROBE state mean no conflicting ARP packets // have been received, so we can progress through the states - if (nprobes < PROBE_NUM) { - nprobes++; + if (nsent < PROBE_NUM) { + nsent++; VDBG("probe/%u %s@%s\n", - nprobes, argv_intf, nip_to_a(chosen_nip)); + nsent, argv_intf, nip_to_a(chosen_nip)); timeout_ms = PROBE_MIN * 1000; timeout_ms += random_delay_ms(PROBE_MAX - PROBE_MIN); arp(/* ARPOP_REQUEST, */ @@ -395,25 +392,25 @@ int zcip_main(int argc UNUSED_PARAM, char **argv) &null_addr, chosen_nip); break; } - // Switch to announce state. - nclaims = 0; + // Switch to announce state + nsent = 0; state = ANNOUNCE; goto send_announce; case ANNOUNCE: // timeouts in the ANNOUNCE state mean no conflicting ARP packets // have been received, so we can progress through the states - if (nclaims < ANNOUNCE_NUM) { + if (nsent < ANNOUNCE_NUM) { send_announce: - nclaims++; + nsent++; VDBG("announce/%u %s@%s\n", - nclaims, argv_intf, nip_to_a(chosen_nip)); + nsent, argv_intf, nip_to_a(chosen_nip)); timeout_ms = ANNOUNCE_INTERVAL * 1000; arp(/* ARPOP_REQUEST, */ /* &G.eth_addr, */ chosen_nip, &G.eth_addr, chosen_nip); break; } - // Switch to monitor state. + // Switch to monitor state // FIXME update filters run(argv, "config", chosen_nip); // NOTE: all other exit paths should deconfig... @@ -424,7 +421,7 @@ int zcip_main(int argc UNUSED_PARAM, char **argv) state = MONITOR; break; case DEFEND: - // Defend period ended with no ARP replies - we won. + // Defend period ended with no ARP replies - we won conflicts = 0; timeout_ms = -1; state = MONITOR; @@ -443,7 +440,7 @@ int zcip_main(int argc UNUSED_PARAM, char **argv) diff = 0; } VDBG("adjusting timeout\n"); - timeout_ms = (diff / 1000) | 1; /* never 0 */ + timeout_ms = (diff / 1000) | 1; // never 0 } if ((fds[0].revents & POLLIN) == 0) { @@ -452,7 +449,7 @@ int zcip_main(int argc UNUSED_PARAM, char **argv) // this shouldn't necessarily exit. bb_error_msg("iface %s is down", argv_intf); if (state >= MONITOR) { - /* only if we are in MONITOR or DEFEND */ + // only if we are in MONITOR or DEFEND run(argv, "deconfig", chosen_nip); } return EXIT_FAILURE; @@ -478,81 +475,65 @@ int zcip_main(int argc UNUSED_PARAM, char **argv) struct ether_addr *tha = (struct ether_addr *) p.arp.arp_tha; struct in_addr *spa = (struct in_addr *) p.arp.arp_spa; struct in_addr *tpa = (struct in_addr *) p.arp.arp_tpa; - VDBG("%s recv arp type=%d, op=%d,\n", - argv_intf, ntohs(p.eth.ether_type), - ntohs(p.arp.arp_op)); - VDBG("\tsource=%s %s\n", - ether_ntoa(sha), - inet_ntoa(*spa)); - VDBG("\ttarget=%s %s\n", - ether_ntoa(tha), - inet_ntoa(*tpa)); + VDBG("source=%s %s\n", ether_ntoa(sha), inet_ntoa(*spa)); + VDBG("target=%s %s\n", ether_ntoa(tha), inet_ntoa(*tpa)); } #endif - source_ip_conflict = 0; - target_ip_conflict = 0; - + ip_conflict = 0; if (memcmp(&p.arp.arp_sha, &G.eth_addr, ETH_ALEN) != 0) { if (memcmp(p.arp.arp_spa, &chosen_nip, 4) == 0) { - /* A probe or reply with source_ip == chosen ip */ - source_ip_conflict = 1; + // A probe or reply with source_ip == chosen ip + ip_conflict = 1; } if (p.arp.arp_op == htons(ARPOP_REQUEST) && memcmp(p.arp.arp_spa, &const_int_0, 4) == 0 && memcmp(p.arp.arp_tpa, &chosen_nip, 4) == 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; + // A probe with source_ip == 0.0.0.0, target_ip == chosen ip: + // another host trying to claim this ip! + ip_conflict |= 2; } } - - VDBG("state = %d, source ip conflict = %d, target ip conflict = %d\n", - state, source_ip_conflict, target_ip_conflict); - switch (state) { - case PROBE: - case ANNOUNCE: - // When probing or announcing, check for source IP conflicts - // and other hosts doing ARP probes (target IP conflicts). - if (source_ip_conflict || target_ip_conflict) { - conflicts++; - timeout_ms = PROBE_MIN * 1000 - + CONFLICT_MULTIPLIER * random_delay_ms(conflicts); - chosen_nip = pick_nip(); - nprobes = 0; - nclaims = 0; - state = PROBE; - } + VDBG("state:%d ip_conflict:%d\n", state, ip_conflict); + if (!ip_conflict) break; - case MONITOR: - // If a conflict, we try to defend with a single ARP probe. - if (source_ip_conflict) { - VDBG("monitor conflict -- defending\n"); + + // Either src or target IP conflict exists + if (state <= ANNOUNCE) { + // PROBE or ANNOUNCE + conflicts++; + timeout_ms = PROBE_MIN * 1000 + + CONFLICT_MULTIPLIER * random_delay_ms(conflicts); + chosen_nip = pick_nip(); + nsent = 0; + state = PROBE; + break; + } + // MONITOR or DEFEND: only src IP conflict is a problem + if (ip_conflict & 1) { + if (state == MONITOR) { + // Src IP conflict, defend with a single ARP probe + VDBG("monitor conflict - defending\n"); timeout_ms = DEFEND_INTERVAL * 1000; state = DEFEND; arp(/* ARPOP_REQUEST, */ /* &G.eth_addr, */ chosen_nip, &G.eth_addr, chosen_nip); + break; } - break; - case DEFEND: - // Well, we tried. Start over (on conflict). - if (source_ip_conflict) { - VDBG("defend conflict -- starting over\n"); - run(argv, "deconfig", chosen_nip); + // state == DEFEND + // Another src IP conflict, start over + VDBG("defend conflict - starting over\n"); + run(argv, "deconfig", chosen_nip); - // restart the whole protocol - timeout_ms = 0; - chosen_nip = pick_nip(); - nprobes = 0; - nclaims = 0; - state = PROBE; - } - break; - } // switch state - break; // case 1 (packets arriving) - } // switch poll + // restart the whole protocol + timeout_ms = 0; + chosen_nip = pick_nip(); + nsent = 0; + state = PROBE; + } + break; // case 1 (packet arrived) + } // switch (poll) } // while (1) #undef argv_intf }