+/* vi: set sw=4 ts=4: */
/*
* RFC3927 ZeroConf IPv4 Link-Local addressing
* (see <http://www.zeroconf.org/>)
* Copyright (C) 2003 by Arthur van Hoff (avh@strangeberry.com)
* Copyright (C) 2004 by David Brownell
*
- * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
+ * Licensed under GPLv2 or later, see file LICENSE in this source tree.
*/
/*
- * This can build as part of BusyBox or by itself:
- *
- * $(CROSS_COMPILE)cc -Os -Wall -DNO_BUSYBOX -DDEBUG -o zcip zcip.c
- *
* ZCIP just manages the 169.254.*.* addresses. That network is not
* routed at the IP level, though various proxies or bridges can
* certainly be used. Its naming is built over multicast DNS.
*/
-// #define DEBUG
+//#define DEBUG
// TODO:
// - more real-world usage/testing, especially daemon mode
// - avoid silent script failures, especially under load...
// - link status monitoring (restart on link-up; stop on link-down)
-#include <errno.h>
-#include <stdlib.h>
-#include <stdio.h>
-#include <string.h>
-#include <syslog.h>
-#include <poll.h>
-#include <time.h>
-#include <unistd.h>
-
-#include <sys/ioctl.h>
-#include <sys/types.h>
-#include <sys/wait.h>
-#include <sys/time.h>
-#include <sys/socket.h>
-
-#include <arpa/inet.h>
-#include <netinet/in.h>
+//usage:#define zcip_trivial_usage
+//usage: "[OPTIONS] IFACE SCRIPT"
+//usage:#define zcip_full_usage "\n\n"
+//usage: "Manage a ZeroConf IPv4 link-local address\n"
+//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 -v Verbose"
+//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 <netinet/ether.h>
-#include <net/ethernet.h>
#include <net/if.h>
#include <net/if_arp.h>
-
-#include <linux/if_packet.h>
#include <linux/sockios.h>
+#include <syslog.h>
+
+/* We don't need more than 32 bits of the counter */
+#define MONOTONIC_US() ((unsigned)monotonic_us())
struct arp_packet {
- struct ether_header hdr;
- // FIXME this part is netinet/if_ether.h "struct ether_arp"
- struct arphdr arp;
- struct ether_addr source_addr;
- struct in_addr source_ip;
- struct ether_addr target_addr;
- struct in_addr target_ip;
-} ATTRIBUTE_PACKED;
+ struct ether_header eth;
+ struct ether_arp arp;
+} PACKED;
+enum {
/* 169.254.0.0 */
-static const uint32_t LINKLOCAL_ADDR = 0xa9fe0000;
+ LINKLOCAL_ADDR = 0xa9fe0000,
/* protocol timeout parameters, specified in seconds */
-static const unsigned PROBE_WAIT = 1;
-static const unsigned PROBE_MIN = 1;
-static const unsigned PROBE_MAX = 2;
-static const unsigned PROBE_NUM = 3;
-static const unsigned MAX_CONFLICTS = 10;
-static const unsigned RATE_LIMIT_INTERVAL = 60;
-static const unsigned ANNOUNCE_WAIT = 2;
-static const unsigned ANNOUNCE_NUM = 2;
-static const unsigned ANNOUNCE_INTERVAL = 2;
-static const time_t DEFEND_INTERVAL = 10;
-
-static const unsigned char ZCIP_VERSION[] = "0.75 (18 April 2005)";
-static char *prog;
-
-static const struct in_addr null_ip = { 0 };
-static const struct ether_addr null_addr = { {0, 0, 0, 0, 0, 0} };
-
-static int verbose = 0;
-
-#ifdef DEBUG
-
-#define DBG(fmt,args...) \
- fprintf(stderr, "%s: " fmt , prog , ## args)
-#define VDBG(fmt,args...) do { \
- if (verbose) fprintf(stderr, "%s: " fmt , prog ,## args); \
- } while (0)
-#else
+ PROBE_WAIT = 1,
+ 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
+};
+
+/* States during the configuration process. */
+enum {
+ PROBE = 0,
+ RATE_LIMIT_PROBE,
+ ANNOUNCE,
+ MONITOR,
+ DEFEND
+};
+
+#define VDBG(...) do { } while (0)
+
+
+enum {
+ sock_fd = 3
+};
+
+struct globals {
+ struct sockaddr saddr;
+ struct ether_addr eth_addr;
+} 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 DBG(fmt,args...) \
- do { } while (0)
-#define VDBG DBG
-#endif /* DEBUG */
/**
* Pick a random link local IP address on 169.254/16, except that
* the first and last 256 addresses are reserved.
*/
-static void
-pick(struct in_addr *ip)
+static uint32_t pick(void)
{
- unsigned tmp;
+ unsigned tmp;
- /* use cheaper math than lrand48() mod N */
do {
- tmp = (lrand48() >> 16) & IN_CLASSB_HOST;
+ tmp = rand() & IN_CLASSB_HOST;
} while (tmp > (IN_CLASSB_HOST - 0x0200));
- ip->s_addr = htonl((LINKLOCAL_ADDR + 0x0100) + tmp);
+ return htonl((LINKLOCAL_ADDR + 0x0100) + tmp);
}
/**
* Broadcast an ARP packet.
*/
-static int
-arp(int fd, struct sockaddr *saddr, int op,
- const struct ether_addr *source_addr, struct in_addr source_ip,
- const struct ether_addr *target_addr, struct in_addr target_ip)
+static void arp(
+ /* 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)
{
+ enum { op = ARPOP_REQUEST };
+#define source_eth (ð_addr)
+
struct arp_packet p;
+ memset(&p, 0, sizeof(p));
// ether header
- p.hdr.ether_type = htons(ETHERTYPE_ARP);
- memcpy(p.hdr.ether_shost, source_addr, ETH_ALEN);
- memset(p.hdr.ether_dhost, 0xff, ETH_ALEN);
+ p.eth.ether_type = htons(ETHERTYPE_ARP);
+ memcpy(p.eth.ether_shost, source_eth, ETH_ALEN);
+ memset(p.eth.ether_dhost, 0xff, ETH_ALEN);
// arp request
- p.arp.ar_hrd = htons(ARPHRD_ETHER);
- p.arp.ar_pro = htons(ETHERTYPE_IP);
- p.arp.ar_hln = ETH_ALEN;
- p.arp.ar_pln = 4;
- p.arp.ar_op = htons(op);
- memcpy(&p.source_addr, source_addr, ETH_ALEN);
- memcpy(&p.source_ip, &source_ip, sizeof (p.source_ip));
- memcpy(&p.target_addr, target_addr, ETH_ALEN);
- memcpy(&p.target_ip, &target_ip, sizeof (p.target_ip));
+ p.arp.arp_hrd = htons(ARPHRD_ETHER);
+ p.arp.arp_pro = htons(ETHERTYPE_IP);
+ p.arp.arp_hln = ETH_ALEN;
+ 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_tha, target_eth, ETH_ALEN);
+ memcpy(&p.arp.arp_tpa, &target_ip, sizeof(p.arp.arp_tpa));
// send it
- if (sendto(fd, &p, sizeof (p), 0, saddr, sizeof (*saddr)) < 0) {
- perror("sendto");
- return -errno;
- }
- return 0;
+ // Even though sock_fd is already bound to saddr, 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
+ // (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));
+#undef source_eth
}
/**
* Run a script.
+ * argv[0]:intf argv[1]:script_name argv[2]:junk argv[3]:NULL
*/
-static int
-run(char *script, char *arg, char *intf, struct in_addr *ip)
+static int run(char *argv[3], const char *param, struct in_addr *ip)
{
- int pid, status;
- char *why;
-
- if (script != NULL) {
- VDBG("%s run %s %s\n", intf, script, arg);
- if (ip != NULL) {
- char *addr = inet_ntoa(*ip);
- setenv("ip", addr, 1);
- syslog(LOG_INFO, "%s %s %s", arg, intf, addr);
- }
+ int status;
+ char *addr = addr; /* for gcc */
+ const char *fmt = "%s %s %s" + 3;
- pid = vfork();
- if (pid < 0) { // error
- why = "vfork";
- goto bad;
- } else if (pid == 0) { // child
- execl(script, script, arg, NULL);
- perror("execl");
- _exit(EXIT_FAILURE);
- }
+ argv[2] = (char*)param;
- if (waitpid(pid, &status, 0) <= 0) {
- why = "waitpid";
- goto bad;
- }
- if (WEXITSTATUS(status) != 0) {
- fprintf(stderr, "%s: script %s failed, exit=%d\n",
- prog, script, WEXITSTATUS(status));
- return -errno;
- }
- }
- return 0;
-bad:
- status = -errno;
- syslog(LOG_ERR, "%s %s, %s error: %s",
- arg, intf, why, strerror(errno));
- return status;
-}
+ VDBG("%s run %s %s\n", argv[0], argv[1], argv[2]);
-#ifndef NO_BUSYBOX
-#include "busybox.h"
-#endif
+ if (ip) {
+ addr = inet_ntoa(*ip);
+ xsetenv("ip", addr);
+ fmt -= 3;
+ }
+ bb_info_msg(fmt, argv[2], argv[0], addr);
-/**
- * Print usage information.
- */
-static void ATTRIBUTE_NORETURN
-zcip_usage(const char *msg)
-{
- fprintf(stderr, "%s: %s\n", prog, msg);
-#ifdef NO_BUSYBOX
- fprintf(stderr, "Usage: %s [OPTIONS] ifname script\n"
- "\t-f foreground mode (implied by -v)\n"
- "\t-q quit after address (no daemon)\n"
- "\t-r 169.254.x.x request this address first\n"
- "\t-v verbose; show version\n",
- prog);
- exit(0);
-#else
- bb_show_usage();
-#endif
+ status = spawn_and_wait(argv + 1);
+ if (status < 0) {
+ bb_perror_msg("%s %s %s" + 3, argv[2], argv[0]);
+ return -errno;
+ }
+ if (status != 0)
+ bb_error_msg("script %s %s failed, exitcode=%d", argv[1], argv[2], status & 0xff);
+ return status;
}
/**
* Return milliseconds of random delay, up to "secs" seconds.
*/
-static inline unsigned
-ms_rdelay(unsigned secs)
+static ALWAYS_INLINE unsigned random_delay_ms(unsigned secs)
{
- return lrand48() % (secs * 1000);
+ return rand() % (secs * 1000);
}
/**
* main program
*/
-
-#ifdef NO_BUSYBOX
-int
-main(int argc, char *argv[])
- __attribute__ ((weak, alias ("zcip_main")));
-#endif
-
-int zcip_main(int argc, char *argv[])
+int zcip_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int zcip_main(int argc UNUSED_PARAM, char **argv)
{
- char *intf = NULL;
- char *script = NULL;
- int quit = 0;
- int foreground = 0;
-
- char *why;
- struct sockaddr saddr;
- struct ether_addr addr;
- struct in_addr ip = { 0 };
- int fd;
- int ready = 0;
- suseconds_t timeout = 0; // milliseconds
- time_t defend = 0;
- unsigned conflicts = 0;
- unsigned nprobes = 0;
- unsigned nclaims = 0;
- int t;
-
+ int state;
+ char *r_opt;
+ unsigned opts;
+
+ // 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;
+ struct ifreq ifr;
+ int timeout_ms; /* must be signed */
+ unsigned conflicts;
+ unsigned nprobes;
+ unsigned nclaims;
+ int ready;
+ 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 )
+
+ memset(&L, 0, sizeof(L));
+ INIT_G();
+
+#define FOREGROUND (opts & 1)
+#define QUIT (opts & 2)
// parse commandline: prog [options] ifname script
- prog = argv[0];
- while ((t = getopt(argc, argv, "fqr:v")) != EOF) {
- switch (t) {
- case 'f':
- foreground = 1;
- continue;
- case 'q':
- quit = 1;
- continue;
- case 'r':
- if (inet_aton(optarg, &ip) == 0
- || (ntohl(ip.s_addr) & IN_CLASSB_NET)
- != LINKLOCAL_ADDR) {
- zcip_usage("invalid link address");
- }
- continue;
- case 'v':
- if (!verbose)
- printf("%s: version %s\n", prog, ZCIP_VERSION);
- verbose++;
- foreground = 1;
- continue;
- default:
- zcip_usage("bad option");
- }
+ // exactly 2 args; -v accumulates and implies -f
+ opt_complementary = "=2:vv:vf";
+ opts = getopt32(argv, "fqr:v", &r_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
+ // (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);
+ if (!FOREGROUND) {
+ // do it before all bb_xx_msg calls
+ openlog(applet_name, 0, LOG_DAEMON);
+ logmode |= LOGMODE_SYSLOG;
}
- if (optind < argc - 1) {
- intf = argv[optind++];
- setenv("interface", intf, 1);
- script = argv[optind++];
+ if (opts & 4) { // -r n.n.n.n
+ if (inet_aton(r_opt, &ip) == 0
+ || (ntohl(ip.s_addr) & IN_CLASSB_NET) != LINKLOCAL_ADDR
+ ) {
+ bb_error_msg_and_die("invalid link address");
+ }
}
- if (optind != argc || !intf)
- zcip_usage("wrong number of arguments");
- openlog(prog, 0, LOG_DAEMON);
+ argv += optind - 1;
+
+ /* Now: argv[0]:junk argv[1]:intf argv[2]:script argv[3]:NULL */
+ /* We need to make space for script argument: */
+ argv[0] = argv[1];
+ argv[1] = argv[2];
+ /* Now: argv[0]:intf argv[1]:script argv[2]:junk argv[3]:NULL */
+#define argv_intf (argv[0])
+
+ xsetenv("interface", argv_intf);
// initialize the interface (modprobe, ifup, etc)
- if (run(script, "init", intf, NULL) < 0)
+ if (run(argv, "init", NULL))
return EXIT_FAILURE;
// initialize saddr
- memset(&saddr, 0, sizeof (saddr));
- strncpy(saddr.sa_data, intf, sizeof (saddr.sa_data));
+ // saddr is: { u16 sa_family; u8 sa_data[14]; }
+ //memset(&saddr, 0, sizeof(saddr));
+ //TODO: are we leaving sa_family == 0 (AF_UNSPEC)?!
+ safe_strncpy(saddr.sa_data, argv_intf, sizeof(saddr.sa_data));
- // open an ARP socket
- if ((fd = socket(PF_PACKET, SOCK_PACKET, htons(ETH_P_ARP))) < 0) {
- why = "open";
-fail:
- foreground = 1;
- goto bad;
- }
// bind to the interface's ARP socket
- if (bind(fd, &saddr, sizeof (saddr)) < 0) {
- why = "bind";
- goto fail;
- } else {
- struct ifreq ifr;
- short seed[3];
-
- // get the interface's ethernet address
- memset(&ifr, 0, sizeof (ifr));
- strncpy(ifr.ifr_name, intf, sizeof (ifr.ifr_name));
- if (ioctl(fd, SIOCGIFHWADDR, &ifr) < 0) {
- why = "get ethernet address";
- goto fail;
- }
- memcpy(&addr, &ifr.ifr_hwaddr.sa_data, ETH_ALEN);
-
- // start with some stable ip address, either a function of
- // the hardware address or else the last address we used.
- // NOTE: the sequence of addresses we try changes only
- // depending on when we detect conflicts.
- memcpy(seed, &ifr.ifr_hwaddr.sa_data, ETH_ALEN);
- seed48(seed);
- if (ip.s_addr == 0)
- pick(&ip);
+ xbind(sock_fd, &saddr, sizeof(saddr));
+
+ // 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);
+
+ // 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.
+ // NOTE: the sequence of addresses we try changes only
+ // depending on when we detect conflicts.
+ {
+ uint32_t t;
+ move_from_unaligned32(t, ((char *)ð_addr + 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
- if (!foreground) {
- if (daemon(0, verbose) < 0) {
- why = "daemon";
- goto bad;
- }
- syslog(LOG_INFO, "start, interface %s", intf);
+ if (!FOREGROUND) {
+#if BB_MMU
+ bb_daemonize(0 /*was: DAEMON_CHDIR_ROOT*/);
+#endif
+ bb_info_msg("start, interface %s", argv_intf);
}
// 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 else uses it
+ // - arp probes to see if another host uses it
// - arp announcements that we're claiming it
// - use it
// - defend it, within limits
+ // exit if:
+ // - address is successfully obtained and -q was given:
+ // 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?)
+ // - revents & POLLERR (link down). run "<script> deconfig" first
+ state = PROBE;
while (1) {
struct pollfd fds[1];
- struct timeval tv1;
+ unsigned deadline_us;
struct arp_packet p;
+ int source_ip_conflict;
+ int target_ip_conflict;
- fds[0].fd = fd;
+ fds[0].fd = sock_fd;
fds[0].events = POLLIN;
fds[0].revents = 0;
// poll, being ready to adjust current timeout
- if (timeout > 0) {
- gettimeofday(&tv1, NULL);
- tv1.tv_usec += (timeout % 1000) * 1000;
- while (tv1.tv_usec > 1000000) {
- tv1.tv_usec -= 1000000;
- tv1.tv_sec++;
- }
- tv1.tv_sec += timeout / 1000;
- } else if (timeout == 0) {
- timeout = ms_rdelay(PROBE_WAIT);
- // FIXME setsockopt(fd, SO_ATTACH_FILTER, ...) to
+ 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.
}
- VDBG("...wait %ld %s nprobes=%d, nclaims=%d\n",
- timeout, intf, nprobes, nclaims);
- switch (poll(fds, 1, timeout)) {
+ // 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);
+
+ switch (safe_poll(fds, 1, timeout_ms)) {
- // timeouts trigger protocol transitions
+ default:
+ //bb_perror_msg("poll"); - done in safe_poll
+ return EXIT_FAILURE;
+
+ // timeout
case 0:
- // probes
- if (nprobes < PROBE_NUM) {
- nprobes++;
- VDBG("probe/%d %s@%s\n",
- nprobes, intf, inet_ntoa(ip));
- (void)arp(fd, &saddr, ARPOP_REQUEST,
- &addr, null_ip,
- &null_addr, ip);
+ 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) {
- timeout = PROBE_MIN * 1000;
- timeout += ms_rdelay(PROBE_MAX
- - PROBE_MIN);
- } else
- timeout = ANNOUNCE_WAIT * 1000;
- }
- // then announcements
- else if (nclaims < ANNOUNCE_NUM) {
- nclaims++;
- VDBG("announce/%d %s@%s\n",
- nclaims, intf, inet_ntoa(ip));
- (void)arp(fd, &saddr, ARPOP_REQUEST,
- &addr, ip,
- &addr, ip);
+ 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);
+ }
+ else {
+ // Switch to announce state.
+ state = ANNOUNCE;
+ 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);
+ }
+ 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
+ state = ANNOUNCE;
+ 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);
+ break;
+ 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) {
- timeout = ANNOUNCE_INTERVAL * 1000;
- } else {
+ 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);
+ }
+ else {
+ // Switch to monitor state.
+ state = MONITOR;
// link is ok to use earlier
- run(script, "config", intf, &ip);
+ // FIXME update filters
+ run(argv, "config", &ip);
ready = 1;
conflicts = 0;
- timeout = -1;
+ timeout_ms = -1; // Never timeout in the monitor state.
- // NOTE: all other exit paths
+ // NOTE: all other exit paths
// should deconfig ...
- if (quit)
+ if (QUIT)
return EXIT_SUCCESS;
- // FIXME update filters
}
- }
- break;
+ break;
+ case DEFEND:
+ // We won! No ARP replies, so just go back to monitor.
+ state = MONITOR;
+ timeout_ms = -1;
+ conflicts = 0;
+ break;
+ 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
+ // packets arriving, or link went down
case 1:
- // maybe adjust timeout
- if (timeout > 0) {
- struct timeval tv2;
-
- gettimeofday(&tv2, NULL);
- if (timercmp(&tv1, &tv2, <)) {
- timeout = -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 {
- timersub(&tv1, &tv2, &tv1);
- timeout = 1000 * tv1.tv_sec
- + tv1.tv_usec / 1000;
+ 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.
- fprintf(stderr, "%s %s: poll error\n",
- prog, intf);
+ bb_error_msg("iface %s is down", argv_intf);
if (ready) {
- run(script, "deconfig",
- intf, &ip);
+ run(argv, "deconfig", &ip);
}
return EXIT_FAILURE;
}
continue;
}
+
// read ARP packet
- if (recv(fd, &p, sizeof (p), 0) < 0) {
- why = "recv";
- goto bad;
+ if (safe_read(sock_fd, &p, sizeof(p)) < 0) {
+ bb_perror_msg_and_die(bb_msg_read_error);
}
- if (p.hdr.ether_type != htons(ETHERTYPE_ARP))
+ if (p.eth.ether_type != htons(ETHERTYPE_ARP))
continue;
-
- VDBG("%s recv arp type=%d, op=%d,\n",
- intf, ntohs(p.hdr.ether_type),
- ntohs(p.arp.ar_op));
- VDBG("\tsource=%s %s\n",
- ether_ntoa(&p.source_addr),
- inet_ntoa(p.source_ip));
- VDBG("\ttarget=%s %s\n",
- ether_ntoa(&p.target_addr),
- inet_ntoa(p.target_ip));
- if (p.arp.ar_op != htons(ARPOP_REQUEST)
- && p.arp.ar_op != htons(ARPOP_REPLY))
+#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));
+ }
+#endif
+ if (p.arp.arp_op != htons(ARPOP_REQUEST)
+ && p.arp.arp_op != htons(ARPOP_REPLY)
+ ) {
continue;
+ }
+
+ source_ip_conflict = 0;
+ target_ip_conflict = 0;
+
+ 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;
+ }
+ }
- // some cases are always conflicts
- if ((p.source_ip.s_addr == ip.s_addr)
- && (memcmp(&addr, &p.source_addr,
- ETH_ALEN) != 0)) {
-collision:
- VDBG("%s ARP conflict from %s\n", intf,
- ether_ntoa(&p.source_addr));
- if (ready) {
- time_t now = time(0);
-
- if ((defend + DEFEND_INTERVAL)
- < now) {
- defend = now;
- (void)arp(fd, &saddr,
- ARPOP_REQUEST,
- &addr, ip,
- &addr, ip);
- VDBG("%s defend\n", intf);
- timeout = -1;
- continue;
+ 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;
}
- defend = now;
- ready = 0;
- run(script, "deconfig", intf, &ip);
- // FIXME rm filters: setsockopt(fd,
- // SO_DETACH_FILTER, ...)
+
+ // 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);
}
- conflicts++;
- if (conflicts >= MAX_CONFLICTS) {
- VDBG("%s ratelimit\n", intf);
- sleep(RATE_LIMIT_INTERVAL);
+ 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;
}
- // restart the whole protocol
- pick(&ip);
- timeout = 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;
- }
- // two hosts probing one address is a collision too
- else if (p.target_ip.s_addr == ip.s_addr
- && nclaims == 0
- && p.arp.ar_op == htons(ARPOP_REQUEST)
- && memcmp(&addr, &p.target_addr,
- ETH_ALEN) != 0) {
- goto collision;
- }
- break;
-
- default:
- why = "poll";
- goto bad;
- }
- }
-bad:
- if (foreground)
- perror(why);
- else
- syslog(LOG_ERR, "%s %s, %s error: %s",
- prog, intf, why, strerror(errno));
- return EXIT_FAILURE;
+ break;
+ } // switch state
+ break; // case 1 (packets arriving)
+ } // switch poll
+ } // while (1)
+#undef argv_intf
}
projects / oweals / busybox.git / blobdiff