99e30be38 — BusyBox

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zcip: code shrink

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Architecture & Compiler Flags

Architecture: x86_64-linux-gnu Compiler: gcc (Ubuntu 11.4.0-1ubuntu1~22.04.3) 11.4.0

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networking/zcip.c +59 -78

networking/zcip.c+59 -78

@@ -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 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
	}