+/* vi: set sw=4 ts=4: */
/*
* RFC3927 ZeroConf IPv4 Link-Local addressing
* (see <http://www.zeroconf.org/>)
* certainly be used. Its naming is built over multicast DNS.
*/
-// #define DEBUG
+//#define DEBUG
// TODO:
// - more real-world usage/testing, especially daemon mode
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;
+ struct ether_arp arp;
} ATTRIBUTE_PACKED;
enum {
DEFEND_INTERVAL = 10
};
-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;
+/* States during the configuration process. */
+enum {
+ PROBE = 0,
+ RATE_LIMIT_PROBE,
+ ANNOUNCE,
+ MONITOR,
+ DEFEND
+};
-#define DBG(fmt,args...) \
+#define VDBG(fmt,args...) \
do { } while (0)
-#define VDBG DBG
+
+static unsigned opts;
+#define FOREGROUND (opts & 1)
+#define QUIT (opts & 2)
/**
* Pick a random link local IP address on 169.254/16, except that
*/
static void pick(struct in_addr *ip)
{
- unsigned tmp;
+ unsigned tmp;
/* use cheaper math than lrand48() mod N */
do {
ip->s_addr = htonl((LINKLOCAL_ADDR + 0x0100) + tmp);
}
+/* TODO: we need a flag to direct bb_[p]error_msg output to stderr. */
+
/**
* Broadcast an ARP packet.
*/
-static int arp(int fd, struct sockaddr *saddr, int op,
+static void 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)
{
struct arp_packet p;
+ memset(&p, 0, sizeof(p));
// ether header
p.hdr.ether_type = htons(ETHERTYPE_ARP);
memset(p.hdr.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_addr, ETH_ALEN);
+ memcpy(&p.arp.arp_spa, &source_ip, sizeof (p.arp.arp_spa));
+ memcpy(&p.arp.arp_tha, target_addr, 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;
+ bb_perror_msg("sendto");
+ //return -errno;
}
- return 0;
+ // Currently all callers ignore errors, that's why returns are
+ // commented out...
+ //return 0;
}
/**
int pid, status;
char *why;
- if (script != NULL) {
+ if(1) { //always true: 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);
+ bb_info_msg("%s %s %s", arg, intf, addr);
}
pid = vfork();
goto bad;
} else if (pid == 0) { // child
execl(script, script, arg, NULL);
- perror("execl");
+ bb_perror_msg("execl");
_exit(EXIT_FAILURE);
}
goto bad;
}
if (WEXITSTATUS(status) != 0) {
- bb_error_msg("script %s failed, exit=%d\n",
- script, WEXITSTATUS(status));
+ bb_error_msg("script %s failed, exit=%d",
+ script, WEXITSTATUS(status));
return -errno;
}
}
return 0;
bad:
status = -errno;
- syslog(LOG_ERR, "%s %s, %s error: %s",
- arg, intf, why, strerror(errno));
+ bb_perror_msg("%s %s, %s", arg, intf, why);
return status;
}
/**
* Return milliseconds of random delay, up to "secs" seconds.
*/
-static inline unsigned ms_rdelay(unsigned secs)
+static unsigned ATTRIBUTE_ALWAYS_INLINE ms_rdelay(unsigned secs)
{
return lrand48() % (secs * 1000);
}
* main program
*/
+/* Used to be auto variables on main() stack, but
+ * most of them were zero-inited. Moving them to bss
+ * is more space-efficient.
+ */
+static const struct in_addr null_ip; // = { 0 };
+static const struct ether_addr null_addr; // = { {0, 0, 0, 0, 0, 0} };
+
+static struct sockaddr saddr; // memset(0);
+static struct in_addr ip; // = { 0 };
+static struct ifreq ifr; //memset(0);
+
+static char *intf; // = NULL;
+static char *script; // = NULL;
+static suseconds_t timeout; // = 0; // milliseconds
+static unsigned conflicts; // = 0;
+static unsigned nprobes; // = 0;
+static unsigned nclaims; // = 0;
+static int ready; // = 0;
+static int verbose; // = 0;
+static int state = PROBE;
+
int zcip_main(int argc, char *argv[])
{
- char *intf = NULL;
- char *script = NULL;
- int quit = 0;
- int foreground = 0;
-
+ struct ether_addr eth_addr;
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;
// parse commandline: prog [options] ifname script
- 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) {
- bb_error_msg_and_die("invalid link address");
- }
- continue;
- case 'v':
- verbose++;
- foreground = 1;
- continue;
- default:
- bb_error_msg_and_die("bad option");
- }
+ char *r_opt;
+ opt_complementary = "vv:vf"; // -v accumulates and implies -f
+ opts = getopt32(argc, argv, "fqr:v", &r_opt, &verbose);
+ if (!FOREGROUND) {
+ /* Do it early, before all bb_xx_msg calls */
+ logmode = LOGMODE_SYSLOG;
+ openlog(bb_applet_name, 0, LOG_DAEMON);
}
- 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)
+ argc -= optind;
+ argv += optind;
+ if (argc != 2)
bb_show_usage();
- openlog(bb_applet_name, 0, LOG_DAEMON);
+ intf = argv[0];
+ script = argv[1];
+ setenv("interface", intf, 1);
// initialize the interface (modprobe, ifup, etc)
if (run(script, "init", intf, NULL) < 0)
return EXIT_FAILURE;
// initialize saddr
- memset(&saddr, 0, sizeof (saddr));
+ //memset(&saddr, 0, sizeof (saddr));
safe_strncpy(saddr.sa_data, 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;
- }
+ fd = xsocket(PF_PACKET, SOCK_PACKET, htons(ETH_P_ARP));
// bind to the interface's ARP socket
- if (bind(fd, &saddr, sizeof (saddr)) < 0) {
- why = "bind";
- goto fail;
- } else {
- struct ifreq ifr;
- unsigned 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(fd, &saddr, sizeof (saddr));
+
+ // 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) {
+ bb_perror_msg_and_die("get ethernet address");
}
+ 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.
+ // NOTE: the sequence of addresses we try changes only
+ // depending on when we detect conflicts.
+ // (SVID 3 bogon: who says that "short" is always 16 bits?)
+ seed48( (unsigned short*)&ifr.ifr_hwaddr.sa_data );
+ if (ip.s_addr == 0)
+ pick(&ip);
// 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) {
+ setsid();
+ xdaemon(0, 0);
+ bb_info_msg("start, interface %s", intf);
}
// run the dynamic address negotiation protocol,
struct timeval tv1;
struct arp_packet p;
+ int source_ip_conflict = 0;
+ int target_ip_conflict = 0;
+
fds[0].fd = 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) {
+ if (!timeout) {
timeout = ms_rdelay(PROBE_WAIT);
// FIXME setsockopt(fd, SO_ATTACH_FILTER, ...) to
// make the kernel filter out all packets except
// ones we'd care about.
}
+ // set tv1 to the point in time when we timeout
+ 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;
+
VDBG("...wait %ld %s nprobes=%d, nclaims=%d\n",
timeout, intf, nprobes, nclaims);
switch (poll(fds, 1, timeout)) {
- // timeouts trigger protocol transitions
+ // 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) {
+ nprobes++;
+ VDBG("probe/%d %s@%s\n",
+ nprobes, intf, inet_ntoa(ip));
+ arp(fd, &saddr, ARPOP_REQUEST,
+ ð_addr, null_ip,
+ &null_addr, ip);
timeout = PROBE_MIN * 1000;
timeout += ms_rdelay(PROBE_MAX
- PROBE_MIN);
- } else
- timeout = ANNOUNCE_WAIT * 1000;
- }
- // then announcements
- else if (nclaims < ANNOUNCE_NUM) {
- nclaims++;
+ }
+ else {
+ // Switch to announce state.
+ state = ANNOUNCE;
+ nclaims = 0;
+ VDBG("announce/%d %s@%s\n",
+ nclaims, intf, inet_ntoa(ip));
+ arp(fd, &saddr, ARPOP_REQUEST,
+ ð_addr, ip,
+ ð_addr, ip);
+ timeout = 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
+ state = ANNOUNCE;
+ nclaims = 0;
VDBG("announce/%d %s@%s\n",
nclaims, intf, inet_ntoa(ip));
- (void)arp(fd, &saddr, ARPOP_REQUEST,
- &addr, ip,
- &addr, ip);
+ arp(fd, &saddr, ARPOP_REQUEST,
+ ð_addr, ip,
+ ð_addr, ip);
+ timeout = ANNOUNCE_INTERVAL * 1000;
+ 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) {
+ nclaims++;
+ VDBG("announce/%d %s@%s\n",
+ nclaims, intf, inet_ntoa(ip));
+ arp(fd, &saddr, ARPOP_REQUEST,
+ ð_addr, ip,
+ ð_addr, ip);
timeout = ANNOUNCE_INTERVAL * 1000;
- } else {
+ }
+ else {
+ // Switch to monitor state.
+ state = MONITOR;
// link is ok to use earlier
+ // FIXME update filters
run(script, "config", intf, &ip);
ready = 1;
conflicts = 0;
- timeout = -1;
+ timeout = -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 = -1;
+ conflicts = 0;
+ break;
+ default:
+ // Invalid, should never happen. Restart the whole protocol.
+ state = PROBE;
+ pick(&ip);
+ timeout = 0;
+ nprobes = 0;
+ nclaims = 0;
+ break;
+ } // switch (state)
+ break; // case 0 (timeout)
// packets arriving
case 1:
- // maybe adjust timeout
+ // We need to adjust the timeout in case we didn't receive
+ // a conflicting packet.
if (timeout > 0) {
struct timeval tv2;
gettimeofday(&tv2, NULL);
if (timercmp(&tv1, &tv2, <)) {
+ // Current time is greater than the expected timeout time.
+ // Should never happen.
+ VDBG("missed an expected timeout\n");
timeout = 0;
} else {
+ VDBG("adjusting timeout\n");
timersub(&tv1, &tv2, &tv1);
timeout = 1000 * tv1.tv_sec
+ tv1.tv_usec / 1000;
}
}
+
if ((fds[0].revents & POLLIN) == 0) {
if (fds[0].revents & POLLERR) {
// FIXME: links routinely go down;
// this shouldn't necessarily exit.
- bb_error_msg("%s: poll error\n", intf);
+ bb_error_msg("%s: poll error", intf);
if (ready) {
run(script, "deconfig",
intf, &ip);
}
continue;
}
+
// read ARP packet
if (recv(fd, &p, sizeof (p), 0) < 0) {
why = "recv";
if (p.hdr.ether_type != htons(ETHERTYPE_ARP))
continue;
- VDBG("%s recv arp type=%d, op=%d,\n",
+#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",
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))
+ 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;
- // 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;
+ if (memcmp(p.arp.arp_spa, &ip.s_addr, sizeof(struct in_addr)) == 0 &&
+ memcmp(ð_addr, &p.arp.arp_sha, ETH_ALEN) != 0) {
+ source_ip_conflict = 1;
+ }
+ if (memcmp(p.arp.arp_tpa, &ip.s_addr, sizeof(struct in_addr)) == 0 &&
+ p.arp.arp_op == htons(ARPOP_REQUEST) &&
+ memcmp(ð_addr, &p.arp.arp_tha, ETH_ALEN) != 0) {
+ target_ip_conflict = 1;
+ }
+
+ 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", intf);
+ timeout = RATE_LIMIT_INTERVAL * 1000;
+ state = RATE_LIMIT_PROBE;
}
- defend = now;
+
+ // restart the whole protocol
+ pick(&ip);
+ timeout = 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 = DEFEND_INTERVAL * 1000;
+ arp(fd, &saddr,
+ 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(script, "deconfig", intf, &ip);
- // FIXME rm filters: setsockopt(fd,
- // SO_DETACH_FILTER, ...)
- }
- conflicts++;
- if (conflicts >= MAX_CONFLICTS) {
- VDBG("%s ratelimit\n", intf);
- sleep(RATE_LIMIT_INTERVAL);
+
+ // restart the whole protocol
+ pick(&ip);
+ timeout = 0;
+ nprobes = 0;
+ nclaims = 0;
}
- // restart the whole protocol
+ break;
+ default:
+ // Invalid, should never happen. Restart the whole protocol.
+ VDBG("invalid state -- starting over\n");
+ state = PROBE;
pick(&ip);
timeout = 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;
+ break;
+ } // switch state
+ break; // case 1 (packets arriving)
default:
why = "poll";
goto bad;
- }
+ } // switch poll
}
bad:
- if (foreground)
- perror(why);
- else
- syslog(LOG_ERR, "%s %s, %s error: %s",
- bb_applet_name, intf, why, strerror(errno));
+ bb_perror_msg("%s, %s", intf, why);
return EXIT_FAILURE;
}
projects / oweals / busybox.git / blobdiff