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));
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;
// 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)) {
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, */
&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...
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;
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) {
// 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;
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 ip_conflict:%d\n", state, ip_conflict);
+ if (!ip_conflict)
+ break;
- 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;
- }
+ // 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;
- case MONITOR:
- // If a conflict, we try to defend with a single ARP probe.
- if (source_ip_conflict) {
- VDBG("monitor conflict -- defending\n");
+ }
+ // 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);
-
- // 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
+ // 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();
+ nsent = 0;
+ state = PROBE;
+ }
+ break; // case 1 (packet arrived)
+ } // switch (poll)
} // while (1)
#undef argv_intf
}
projects / oweals / busybox.git / commitdiff