1303 files changed, 32187 insertions, 57138 deletions
diff --git a/networking/zcip.c b/networking/zcip.c index 7314ff8..9122bd6 100644 --- a/networking/zcip.c +++ b/networking/zcip.c @@ -14,6 +14,22 @@ * routed at the IP level, though various proxies or bridges can * certainly be used. Its naming is built over multicast DNS. */ +//config:config ZCIP +//config: bool "zcip" +//config: default y +//config: select PLATFORM_LINUX +//config: select FEATURE_SYSLOG +//config: help +//config: ZCIP provides ZeroConf IPv4 address selection, according to RFC 3927. +//config: It's a daemon that allocates and defends a dynamically assigned +//config: address on the 169.254/16 network, requiring no system administrator. +//config: +//config: See http://www.zeroconf.org for further details, and "zcip.script" +//config: in the busybox examples. + +//applet:IF_ZCIP(APPLET(zcip, BB_DIR_SBIN, BB_SUID_DROP)) + +//kbuild:lib-$(CONFIG_ZCIP) += zcip.o //#define DEBUG @@ -30,12 +46,17 @@ //usage: "\n -f Run in foreground" //usage: "\n -q Quit after obtaining address" //usage: "\n -r 169.254.x.x Request this address first" +//usage: "\n -l x.x.0.0 Use this range instead of 169.254" //usage: "\n -v Verbose" //usage: "\n" +//usage: "\n$LOGGING=none Suppress logging" +//usage: "\n$LOGGING=syslog Log to syslog" +//usage: "\n" //usage: "\nWith no -q, runs continuously monitoring for ARP conflicts," //usage: "\nexits only on I/O errors (link down etc)" #include "libbb.h" +#include "common_bufsiz.h" #include <netinet/ether.h> #include <net/if.h> #include <net/if_arp.h> @@ -52,26 +73,23 @@ struct arp_packet { } PACKED; enum { -/* 169.254.0.0 */ - LINKLOCAL_ADDR = 0xa9fe0000, - -/* protocol timeout parameters, specified in seconds */ + /* 0-1 seconds before sending 1st probe */ PROBE_WAIT = 1, + /* 1-2 seconds between probes */ PROBE_MIN = 1, PROBE_MAX = 2, - PROBE_NUM = 3, - MAX_CONFLICTS = 10, - RATE_LIMIT_INTERVAL = 60, - ANNOUNCE_WAIT = 2, - ANNOUNCE_NUM = 2, - ANNOUNCE_INTERVAL = 2, - DEFEND_INTERVAL = 10 + PROBE_NUM = 3, /* total probes to send */ + ANNOUNCE_INTERVAL = 2, /* 2 seconds between announces */ + ANNOUNCE_NUM = 3, /* announces to send */ + /* if probe/announce sees a conflict, multiply RANDOM(NUM_CONFLICT) by... */ + CONFLICT_MULTIPLIER = 2, + /* if we monitor and see a conflict, how long is defend state? */ + DEFEND_INTERVAL = 10, }; /* States during the configuration process. */ enum { PROBE = 0, - RATE_LIMIT_PROBE, ANNOUNCE, MONITOR, DEFEND @@ -85,40 +103,46 @@ enum { }; struct globals { - struct sockaddr saddr; - struct ether_addr eth_addr; + struct sockaddr iface_sockaddr; + struct ether_addr our_ethaddr; + uint32_t localnet_ip; } FIX_ALIASING; -#define G (*(struct globals*)&bb_common_bufsiz1) -#define saddr (G.saddr ) -#define eth_addr (G.eth_addr) -#define INIT_G() do { } while (0) +#define G (*(struct globals*)bb_common_bufsiz1) +#define INIT_G() do { setup_common_bufsiz(); } while (0) /** * Pick a random link local IP address on 169.254/16, except that * the first and last 256 addresses are reserved. */ -static uint32_t pick(void) +static uint32_t pick_nip(void) { unsigned tmp; do { tmp = rand() & IN_CLASSB_HOST; } while (tmp > (IN_CLASSB_HOST - 0x0200)); - return htonl((LINKLOCAL_ADDR + 0x0100) + tmp); + return htonl((G.localnet_ip + 0x0100) + tmp); +} + +static const char *nip_to_a(uint32_t nip) +{ + struct in_addr in; + in.s_addr = nip; + return inet_ntoa(in); } /** * Broadcast an ARP packet. */ -static void arp( +static void send_arp_request( /* int op, - always ARPOP_REQUEST */ - /* const struct ether_addr *source_eth, - always ð_addr */ - struct in_addr source_ip, - const struct ether_addr *target_eth, struct in_addr target_ip) + /* const struct ether_addr *source_eth, - always &G.our_ethaddr */ + uint32_t source_nip, + const struct ether_addr *target_eth, uint32_t target_nip) { enum { op = ARPOP_REQUEST }; -#define source_eth (ð_addr) +#define source_eth (&G.our_ethaddr) struct arp_packet p; memset(&p, 0, sizeof(p)); @@ -135,18 +159,18 @@ static void arp( p.arp.arp_pln = 4; p.arp.arp_op = htons(op); memcpy(&p.arp.arp_sha, source_eth, ETH_ALEN); - memcpy(&p.arp.arp_spa, &source_ip, sizeof(p.arp.arp_spa)); + memcpy(&p.arp.arp_spa, &source_nip, 4); memcpy(&p.arp.arp_tha, target_eth, ETH_ALEN); - memcpy(&p.arp.arp_tpa, &target_ip, sizeof(p.arp.arp_tpa)); + memcpy(&p.arp.arp_tpa, &target_nip, 4); // send it - // Even though sock_fd is already bound to saddr, just send() + // Even though sock_fd is already bound to G.iface_sockaddr, just send() // won't work, because "socket is not connected" // (and connect() won't fix that, "operation not supported"). - // Thus we sendto() to saddr. I wonder which sockaddr + // Thus we sendto() to G.iface_sockaddr. I wonder which sockaddr // (from bind() or from sendto()?) kernel actually uses // to determine iface to emit the packet from... - xsendto(sock_fd, &p, sizeof(p), &saddr, sizeof(saddr)); + xsendto(sock_fd, &p, sizeof(p), &G.iface_sockaddr, sizeof(G.iface_sockaddr)); #undef source_eth } @@ -154,22 +178,22 @@ static void arp( * Run a script. * argv[0]:intf argv[1]:script_name argv[2]:junk argv[3]:NULL */ -static int run(char *argv[3], const char *param, struct in_addr *ip) +static int run(char *argv[3], const char *param, uint32_t nip) { int status; - char *addr = addr; /* for gcc */ + const char *addr = addr; /* for gcc */ const char *fmt = "%s %s %s" + 3; argv[2] = (char*)param; VDBG("%s run %s %s\n", argv[0], argv[1], argv[2]); - if (ip) { - addr = inet_ntoa(*ip); + if (nip != 0) { + addr = nip_to_a(nip); xsetenv("ip", addr); fmt -= 3; } - bb_info_msg(fmt, argv[2], argv[0], addr); + bb_error_msg(fmt, argv[2], argv[0], addr); status = spawn_and_wait(argv + 1); if (status < 0) { @@ -186,7 +210,7 @@ static int run(char *argv[3], const char *param, struct in_addr *ip) */ static ALWAYS_INLINE unsigned random_delay_ms(unsigned secs) { - return rand() % (secs * 1000); + return (unsigned)rand() % (secs * 1000); } /** @@ -195,49 +219,43 @@ static ALWAYS_INLINE unsigned random_delay_ms(unsigned secs) int zcip_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; int zcip_main(int argc UNUSED_PARAM, char **argv) { - int state; char *r_opt; + const char *l_opt = "169.254.0.0"; + int state; + int nsent; unsigned opts; - // ugly trick, but I want these zeroed in one go + // Ugly trick, but I want these zeroed in one go struct { - const struct in_addr null_ip; - const struct ether_addr null_addr; - struct in_addr ip; + const struct ether_addr null_ethaddr; struct ifreq ifr; - int timeout_ms; /* must be signed */ - unsigned conflicts; - unsigned nprobes; - unsigned nclaims; - int ready; + uint32_t chosen_nip; + int conflicts; + int timeout_ms; // must be signed int verbose; } L; -#define null_ip (L.null_ip ) -#define null_addr (L.null_addr ) -#define ip (L.ip ) -#define ifr (L.ifr ) -#define timeout_ms (L.timeout_ms) -#define conflicts (L.conflicts ) -#define nprobes (L.nprobes ) -#define nclaims (L.nclaims ) -#define ready (L.ready ) -#define verbose (L.verbose ) +#define null_ethaddr (L.null_ethaddr) +#define ifr (L.ifr ) +#define chosen_nip (L.chosen_nip ) +#define conflicts (L.conflicts ) +#define timeout_ms (L.timeout_ms ) +#define verbose (L.verbose ) memset(&L, 0, sizeof(L)); INIT_G(); #define FOREGROUND (opts & 1) #define QUIT (opts & 2) - // parse commandline: prog [options] ifname script + // Parse commandline: prog [options] ifname script // exactly 2 args; -v accumulates and implies -f opt_complementary = "=2:vv:vf"; - opts = getopt32(argv, "fqr:v", &r_opt, &verbose); + opts = getopt32(argv, "fqr:l:v", &r_opt, &l_opt, &verbose); #if !BB_MMU // on NOMMU reexec early (or else we will rerun things twice) if (!FOREGROUND) bb_daemonize_or_rexec(0 /*was: DAEMON_CHDIR_ROOT*/, argv); #endif - // open an ARP socket + // Open an ARP socket // (need to do it before openlog to prevent openlog from taking // fd 3 (sock_fd==3)) xmove_fd(xsocket(AF_PACKET, SOCK_PACKET, htons(ETH_P_ARP)), sock_fd); @@ -246,12 +264,25 @@ int zcip_main(int argc UNUSED_PARAM, char **argv) openlog(applet_name, 0, LOG_DAEMON); logmode |= LOGMODE_SYSLOG; } + bb_logenv_override(); + + { // -l n.n.n.n + struct in_addr net; + if (inet_aton(l_opt, &net) == 0 + || (net.s_addr & htonl(IN_CLASSB_NET)) != net.s_addr + ) { + bb_error_msg_and_die("invalid network address"); + } + G.localnet_ip = ntohl(net.s_addr); + } if (opts & 4) { // -r n.n.n.n + struct in_addr ip; if (inet_aton(r_opt, &ip) == 0 - || (ntohl(ip.s_addr) & IN_CLASSB_NET) != LINKLOCAL_ADDR + || (ntohl(ip.s_addr) & IN_CLASSB_NET) != G.localnet_ip ) { bb_error_msg_and_die("invalid link address"); } + chosen_nip = ip.s_addr; } argv += optind - 1; @@ -264,26 +295,26 @@ int zcip_main(int argc UNUSED_PARAM, char **argv) xsetenv("interface", argv_intf); - // initialize the interface (modprobe, ifup, etc) - if (run(argv, "init", NULL)) + // Initialize the interface (modprobe, ifup, etc) + if (run(argv, "init", 0)) return EXIT_FAILURE; - // initialize saddr - // saddr is: { u16 sa_family; u8 sa_data[14]; } - //memset(&saddr, 0, sizeof(saddr)); + // Initialize G.iface_sockaddr + // G.iface_sockaddr is: { u16 sa_family; u8 sa_data[14]; } + //memset(&G.iface_sockaddr, 0, sizeof(G.iface_sockaddr)); //TODO: are we leaving sa_family == 0 (AF_UNSPEC)?! - safe_strncpy(saddr.sa_data, argv_intf, sizeof(saddr.sa_data)); + safe_strncpy(G.iface_sockaddr.sa_data, argv_intf, sizeof(G.iface_sockaddr.sa_data)); - // bind to the interface's ARP socket - xbind(sock_fd, &saddr, sizeof(saddr)); + // Bind to the interface's ARP socket + xbind(sock_fd, &G.iface_sockaddr, sizeof(G.iface_sockaddr)); - // get the interface's ethernet address + // Get the interface's ethernet address //memset(&ifr, 0, sizeof(ifr)); strncpy_IFNAMSIZ(ifr.ifr_name, argv_intf); xioctl(sock_fd, SIOCGIFHWADDR, &ifr); - memcpy(ð_addr, &ifr.ifr_hwaddr.sa_data, ETH_ALEN); + memcpy(&G.our_ethaddr, &ifr.ifr_hwaddr.sa_data, ETH_ALEN); - // start with some stable ip address, either a function of + // Start with some stable ip address, either a function of // the hardware address or else the last address we used. // we are taking low-order four bytes, as top-order ones // aren't random enough. @@ -291,30 +322,29 @@ int zcip_main(int argc UNUSED_PARAM, char **argv) // depending on when we detect conflicts. { uint32_t t; - move_from_unaligned32(t, ((char *)ð_addr + 2)); + move_from_unaligned32(t, ((char *)&G.our_ethaddr + 2)); srand(t); } - if (ip.s_addr == 0) - ip.s_addr = pick(); - // FIXME cases to handle: // - zcip already running! // - link already has local address... just defend/update - // daemonize now; don't delay system startup + // Daemonize now; don't delay system startup if (!FOREGROUND) { #if BB_MMU bb_daemonize(0 /*was: DAEMON_CHDIR_ROOT*/); #endif - bb_info_msg("start, interface %s", argv_intf); + bb_error_msg("start, interface %s", argv_intf); } - // run the dynamic address negotiation protocol, + // Run the dynamic address negotiation protocol, // restarting after address conflicts: // - start with some address we want to try // - short random delay // - arp probes to see if another host uses it + // 00:04:e2:64:23:c2 > ff:ff:ff:ff:ff:ff arp who-has 169.254.194.171 tell 0.0.0.0 // - arp announcements that we're claiming it + // 00:04:e2:64:23:c2 > ff:ff:ff:ff:ff:ff arp who-has 169.254.194.171 (00:04:e2:64:23:c2) tell 169.254.194.171 // - use it // - defend it, within limits // exit if: @@ -322,257 +352,193 @@ int zcip_main(int argc UNUSED_PARAM, char **argv) // run "<script> config", then exit with exitcode 0 // - poll error (when does this happen?) // - read error (when does this happen?) - // - sendto error (in arp()) (when does this happen?) + // - sendto error (in send_arp_request()) (when does this happen?) // - revents & POLLERR (link down). run "<script> deconfig" first + if (chosen_nip == 0) { + new_nip_and_PROBE: + chosen_nip = pick_nip(); + } + nsent = 0; state = PROBE; while (1) { struct pollfd fds[1]; - unsigned deadline_us; + unsigned deadline_us = deadline_us; struct arp_packet p; - int source_ip_conflict; - int target_ip_conflict; + int ip_conflict; + int n; fds[0].fd = sock_fd; fds[0].events = POLLIN; fds[0].revents = 0; - // poll, being ready to adjust current timeout + // Poll, being ready to adjust current timeout if (!timeout_ms) { timeout_ms = random_delay_ms(PROBE_WAIT); // FIXME setsockopt(sock_fd, SO_ATTACH_FILTER, ...) to // make the kernel filter out all packets except // ones we'd care about. } - // 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); + if (timeout_ms >= 0) { + // Set deadline_us to the point in time when we timeout + deadline_us = MONOTONIC_US() + timeout_ms * 1000; + } - switch (safe_poll(fds, 1, timeout_ms)) { + VDBG("...wait %d %s nsent=%u\n", + timeout_ms, argv_intf, nsent); - default: + n = safe_poll(fds, 1, timeout_ms); + if (n < 0) { //bb_perror_msg("poll"); - done in safe_poll return EXIT_FAILURE; - - // timeout - case 0: - VDBG("state = %d\n", state); + } + if (n == 0) { // timed out? + VDBG("state:%d\n", state); switch (state) { 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++; + // No conflicting ARP packets were seen: + // we can progress through the states + if (nsent < PROBE_NUM) { + nsent++; VDBG("probe/%u %s@%s\n", - nprobes, argv_intf, inet_ntoa(ip)); - arp(/* ARPOP_REQUEST, */ - /* ð_addr, */ null_ip, - &null_addr, ip); + nsent, argv_intf, nip_to_a(chosen_nip)); timeout_ms = PROBE_MIN * 1000; timeout_ms += random_delay_ms(PROBE_MAX - PROBE_MIN); + send_arp_request(0, &null_ethaddr, chosen_nip); + continue; } - else { - // Switch to announce state. - state = ANNOUNCE; - nclaims = 0; - VDBG("announce/%u %s@%s\n", - nclaims, argv_intf, inet_ntoa(ip)); - arp(/* ARPOP_REQUEST, */ - /* ð_addr, */ ip, - ð_addr, ip); - timeout_ms = ANNOUNCE_INTERVAL * 1000; - } - break; - case RATE_LIMIT_PROBE: - // timeouts in the RATE_LIMIT_PROBE state mean no conflicting ARP packets - // have been received, so we can move immediately to the announce state + // Switch to announce state + nsent = 0; state = ANNOUNCE; - nclaims = 0; - VDBG("announce/%u %s@%s\n", - nclaims, argv_intf, inet_ntoa(ip)); - arp(/* ARPOP_REQUEST, */ - /* ð_addr, */ ip, - ð_addr, ip); - timeout_ms = ANNOUNCE_INTERVAL * 1000; - break; + 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) { - nclaims++; + // No conflicting ARP packets were seen: + // we can progress through the states + if (nsent < ANNOUNCE_NUM) { + send_announce: + nsent++; VDBG("announce/%u %s@%s\n", - nclaims, argv_intf, inet_ntoa(ip)); - arp(/* ARPOP_REQUEST, */ - /* ð_addr, */ ip, - ð_addr, ip); + nsent, argv_intf, nip_to_a(chosen_nip)); timeout_ms = ANNOUNCE_INTERVAL * 1000; + send_arp_request(chosen_nip, &G.our_ethaddr, chosen_nip); + continue; } - else { - // Switch to monitor state. - state = MONITOR; - // link is ok to use earlier - // FIXME update filters - run(argv, "config", &ip); - ready = 1; - conflicts = 0; - timeout_ms = -1; // Never timeout in the monitor state. - - // NOTE: all other exit paths - // should deconfig ... - if (QUIT) - return EXIT_SUCCESS; - } - break; - case DEFEND: - // We won! No ARP replies, so just go back to monitor. - state = MONITOR; - timeout_ms = -1; - conflicts = 0; - break; + // Switch to monitor state + // FIXME update filters + run(argv, "config", chosen_nip); + // NOTE: all other exit paths should deconfig... + if (QUIT) + return EXIT_SUCCESS; + // fall through: switch to MONITOR default: - // Invalid, should never happen. Restart the whole protocol. - state = PROBE; - ip.s_addr = pick(); - timeout_ms = 0; - nprobes = 0; - nclaims = 0; - break; - } // switch (state) - break; // case 0 (timeout) - - // packets arriving, or link went down - case 1: - // We need to adjust the timeout in case we didn't receive - // a conflicting packet. - if (timeout_ms > 0) { - unsigned diff = deadline_us - MONOTONIC_US(); - if ((int)(diff) < 0) { - // Current time is greater than the expected timeout time. - // Should never happen. - VDBG("missed an expected timeout\n"); - timeout_ms = 0; - } else { - VDBG("adjusting timeout\n"); - timeout_ms = (diff / 1000) | 1; /* never 0 */ - } - } - - if ((fds[0].revents & POLLIN) == 0) { - if (fds[0].revents & POLLERR) { - // FIXME: links routinely go down; - // this shouldn't necessarily exit. - bb_error_msg("iface %s is down", argv_intf); - if (ready) { - run(argv, "deconfig", &ip); - } - return EXIT_FAILURE; - } + // case DEFEND: + // case MONITOR: (shouldn't happen, MONITOR timeout is infinite) + // Defend period ended with no ARP replies - we won + timeout_ms = -1; // never timeout in monitor state + state = MONITOR; continue; } + } - // read ARP packet - if (safe_read(sock_fd, &p, sizeof(p)) < 0) { - bb_perror_msg_and_die(bb_msg_read_error); + // Packet arrived, or link went down. + // We need to adjust the timeout in case we didn't receive + // a conflicting packet. + if (timeout_ms > 0) { + unsigned diff = deadline_us - MONOTONIC_US(); + if ((int)(diff) < 0) { + // Current time is greater than the expected timeout time. + diff = 0; } - if (p.eth.ether_type != htons(ETHERTYPE_ARP)) - continue; -#ifdef DEBUG - { - struct ether_addr *sha = (struct ether_addr *) p.arp.arp_sha; - 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("adjusting timeout\n"); + timeout_ms = (diff / 1000) | 1; // never 0 + } + + if ((fds[0].revents & POLLIN) == 0) { + if (fds[0].revents & POLLERR) { + // FIXME: links routinely go down; + // 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 + run(argv, "deconfig", chosen_nip); + } + return EXIT_FAILURE; } -#endif - if (p.arp.arp_op != htons(ARPOP_REQUEST) - && p.arp.arp_op != htons(ARPOP_REPLY)) - continue; + continue; + } - source_ip_conflict = 0; - target_ip_conflict = 0; + // Read ARP packet + if (safe_read(sock_fd, &p, sizeof(p)) < 0) { + bb_perror_msg_and_die(bb_msg_read_error); + } - 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.eth.ether_type != htons(ETHERTYPE_ARP)) + continue; + if (p.arp.arp_op != htons(ARPOP_REQUEST) + && p.arp.arp_op != htons(ARPOP_REPLY) + ) { + continue; + } +#ifdef DEBUG + { + struct ether_addr *sha = (struct ether_addr *) p.arp.arp_sha; + 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("source=%s %s\n", ether_ntoa(sha), inet_ntoa(*spa)); + VDBG("target=%s %s\n", ether_ntoa(tha), inet_ntoa(*tpa)); + } +#endif + ip_conflict = 0; + if (memcmp(&p.arp.arp_sha, &G.our_ethaddr, ETH_ALEN) != 0) { + if (memcmp(p.arp.arp_spa, &chosen_nip, 4) == 0) { + // A probe or reply with source_ip == chosen ip + 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 + && memcmp(p.arp.arp_spa, &const_int_0, 4) == 0 + && memcmp(p.arp.arp_tpa, &chosen_nip, 4) == 0 ) { - 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) + continue; + + // 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); + goto new_nip_and_PROBE; + } - 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++; - if (conflicts >= MAX_CONFLICTS) { - VDBG("%s ratelimit\n", argv_intf); - timeout_ms = RATE_LIMIT_INTERVAL * 1000; - state = RATE_LIMIT_PROBE; - } - - // restart the whole protocol - ip.s_addr = pick(); - timeout_ms = 0; - nprobes = 0; - nclaims = 0; - } - break; - case MONITOR: - // If a conflict, we try to defend with a single ARP probe. - if (source_ip_conflict) { - VDBG("monitor conflict -- defending\n"); - state = DEFEND; - timeout_ms = DEFEND_INTERVAL * 1000; - arp(/* ARPOP_REQUEST, */ - /* ð_addr, */ ip, - ð_addr, ip); - } - break; - case DEFEND: - // Well, we tried. Start over (on conflict). - if (source_ip_conflict) { - state = PROBE; - VDBG("defend conflict -- starting over\n"); - ready = 0; - run(argv, "deconfig", &ip); - - // restart the whole protocol - ip.s_addr = pick(); - timeout_ms = 0; - nprobes = 0; - nclaims = 0; - } - break; - default: - // Invalid, should never happen. Restart the whole protocol. - VDBG("invalid state -- starting over\n"); - state = PROBE; - ip.s_addr = pick(); - timeout_ms = 0; - nprobes = 0; - nclaims = 0; - break; - } // switch state - break; // case 1 (packets arriving) - } // switch poll + // 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; + send_arp_request(chosen_nip, &G.our_ethaddr, chosen_nip); + continue; + } + // state == DEFEND + // Another src IP conflict, start over + VDBG("defend conflict - starting over\n"); + run(argv, "deconfig", chosen_nip); + conflicts = 0; + timeout_ms = 0; + goto new_nip_and_PROBE; + } + // Note: if we only have a target IP conflict here (ip_conflict & 2), + // IOW: if we just saw this sort of ARP packet: + // aa:bb:cc:dd:ee:ff > xx:xx:xx:xx:xx:xx arp who-has <chosen_nip> tell 0.0.0.0 + // we expect _kernel_ to respond to that, because <chosen_nip> + // is (expected to be) configured on this iface. } // while (1) #undef argv_intf } |