* 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.
*/
/*
// - avoid silent script failures, especially under load...
// - link status monitoring (restart on link-up; stop on link-down)
-#include <syslog.h>
-#include <poll.h>
-#include <sys/wait.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 -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 <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 "libbb.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;
+ struct ether_header eth;
struct ether_arp arp;
-} ATTRIBUTE_PACKED;
+} 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
};
-#define VDBG(fmt,args...) \
- do { } while (0)
+#define VDBG(...) do { } while (0)
+
+
+enum {
+ sock_fd = 3
+};
+
+struct globals {
+ struct sockaddr iface_sockaddr;
+ struct ether_addr our_ethaddr;
+ uint32_t localnet_ip;
+} FIX_ALIASING;
+#define G (*(struct globals*)&bb_common_bufsiz1)
+#define INIT_G() do { } while (0)
+
/**
* 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_nip(void)
{
unsigned tmp;
do {
tmp = rand() & IN_CLASSB_HOST;
} while (tmp > (IN_CLASSB_HOST - 0x0200));
- ip->s_addr = 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(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 send_arp_request(
+ /* int op, - always ARPOP_REQUEST */
+ /* 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 (&G.our_ethaddr)
+
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.arp_hrd = htons(ARPHRD_ETHER);
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));
+ memcpy(&p.arp.arp_sha, source_eth, ETH_ALEN);
+ memcpy(&p.arp.arp_spa, &source_nip, 4);
+ memcpy(&p.arp.arp_tha, target_eth, ETH_ALEN);
+ memcpy(&p.arp.arp_tpa, &target_nip, 4);
// send it
- xsendto(fd, &p, sizeof(p), saddr, sizeof(*saddr));
-
- // Currently all callers ignore errors, that's why returns are
- // commented out...
- //return 0;
+ // 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 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), &G.iface_sockaddr, sizeof(G.iface_sockaddr));
+#undef source_eth
}
/**
- * Run a script. argv[2] is already NULL.
+ * Run a script.
+ * argv[0]:intf argv[1]:script_name argv[2]:junk argv[3]:NULL
*/
-static int run(char *argv[3], const char *intf, struct in_addr *ip)
+static int run(char *argv[3], const char *param, uint32_t nip)
{
int status;
+ const char *addr = addr; /* for gcc */
+ const char *fmt = "%s %s %s" + 3;
- VDBG("%s run %s %s\n", intf, argv[0], argv[1]);
+ argv[2] = (char*)param;
- if (ip) {
- char *addr = inet_ntoa(*ip);
- setenv("ip", addr, 1);
- bb_info_msg("%s %s %s", argv[1], intf, addr);
+ VDBG("%s run %s %s\n", argv[0], argv[1], argv[2]);
+
+ if (nip != 0) {
+ addr = nip_to_a(nip);
+ xsetenv("ip", addr);
+ fmt -= 3;
}
+ bb_error_msg(fmt, argv[2], argv[0], addr);
- status = wait4pid(spawn(argv));
+ status = spawn_and_wait(argv + 1);
if (status < 0) {
- bb_perror_msg("%s %s", argv[1], intf);
+ 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[0], argv[1], status);
+ 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 unsigned ALWAYS_INLINE ms_rdelay(unsigned secs)
+static ALWAYS_INLINE unsigned random_delay_ms(unsigned secs)
{
- return rand() % (secs * 1000);
+ return (unsigned)rand() % (secs * 1000);
}
/**
* main program
*/
-int zcip_main(int argc, char **argv);
-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)
{
- int state = PROBE;
- struct ether_addr eth_addr;
- const char *why;
- int fd;
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 sockaddr saddr;
- struct in_addr ip;
+ const struct ether_addr null_ethaddr;
struct ifreq ifr;
- char *intf;
- char *script_av[3];
- 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 saddr (L.saddr )
-#define ip (L.ip )
-#define ifr (L.ifr )
-#define intf (L.intf )
-#define script_av (L.script_av )
-#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));
-
- srand(MONOTONIC_US());
+ 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(argc, 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
+ // (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 early, before all bb_xx_msg calls */
+ // do it before all bb_xx_msg calls
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;
}
- // On NOMMU reexec early (or else we will rerun things twice)
-#if !BB_MMU
- if (!FOREGROUND)
- bb_daemonize_or_rexec(DAEMON_CHDIR_ROOT, argv);
-#endif
- argc -= optind;
- argv += optind;
+ argv += optind - 1;
- intf = argv[0];
- script_av[0] = argv[1];
- setenv("interface", intf, 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])
- // initialize the interface (modprobe, ifup, etc)
- script_av[1] = (char*)"init";
- if (run(script_av, intf, NULL))
+ xsetenv("interface", argv_intf);
+
+ // Initialize the interface (modprobe, ifup, etc)
+ if (run(argv, "init", 0))
return EXIT_FAILURE;
- // initialize saddr
- //memset(&saddr, 0, sizeof(saddr));
- safe_strncpy(saddr.sa_data, intf, sizeof(saddr.sa_data));
+ // 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(G.iface_sockaddr.sa_data, argv_intf, sizeof(G.iface_sockaddr.sa_data));
- // open an ARP socket
- fd = xsocket(PF_PACKET, SOCK_PACKET, htons(ETH_P_ARP));
- // bind to the interface's ARP socket
- xbind(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(ifr.ifr_name, intf, sizeof(ifr.ifr_name));
- xioctl(fd, SIOCGIFHWADDR, &ifr);
- memcpy(ð_addr, &ifr.ifr_hwaddr.sa_data, ETH_ALEN);
+ strncpy_IFNAMSIZ(ifr.ifr_name, argv_intf);
+ xioctl(sock_fd, SIOCGIFHWADDR, &ifr);
+ 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.
// 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);
-
+ {
+ uint32_t t;
+ move_from_unaligned32(t, ((char *)&G.our_ethaddr + 2));
+ srand(t);
+ }
// 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(DAEMON_CHDIR_ROOT);
+ bb_daemonize(0 /*was: DAEMON_CHDIR_ROOT*/);
#endif
- bb_info_msg("start, interface %s", 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 else uses it
+ // - 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:
+ // - 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 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 ip_conflict;
+ int n;
- int source_ip_conflict = 0;
- int target_ip_conflict = 0;
-
- fds[0].fd = fd;
+ 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 = ms_rdelay(PROBE_WAIT);
- // FIXME setsockopt(fd, SO_ATTACH_FILTER, ...) to
+ 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;
+ if (timeout_ms >= 0) {
+ // 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, intf, nprobes, nclaims);
- switch (poll(fds, 1, timeout_ms)) {
+ VDBG("...wait %d %s nsent=%u\n",
+ timeout_ms, argv_intf, nsent);
- // timeout
- case 0:
- VDBG("state = %d\n", state);
+ n = safe_poll(fds, 1, timeout_ms);
+ if (n < 0) {
+ //bb_perror_msg("poll"); - done in safe_poll
+ return EXIT_FAILURE;
+ }
+ 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, intf, inet_ntoa(ip));
- arp(fd, &saddr, ARPOP_REQUEST,
- ð_addr, null_ip,
- &null_addr, ip);
+ nsent, argv_intf, nip_to_a(chosen_nip));
timeout_ms = PROBE_MIN * 1000;
- timeout_ms += ms_rdelay(PROBE_MAX - PROBE_MIN);
+ 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, intf, inet_ntoa(ip));
- arp(fd, &saddr, 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, intf, inet_ntoa(ip));
- arp(fd, &saddr, 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, intf, inet_ntoa(ip));
- arp(fd, &saddr, 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
- script_av[1] = (char*)"config";
- run(script_av, intf, &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;
- pick(&ip);
- timeout_ms = 0;
- nprobes = 0;
- nclaims = 0;
- break;
- } // switch (state)
- break; // case 0 (timeout)
- // packets arriving
- 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;
- if (!timeout_ms) timeout_ms = 1;
- }
+ // 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;
}
+ }
- 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", intf);
- if (ready) {
- script_av[1] = (char*)"deconfig";
- run(script_av, intf, &ip);
- }
- return EXIT_FAILURE;
- }
- continue;
+ // 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;
}
+ VDBG("adjusting timeout\n");
+ timeout_ms = (diff / 1000) | 1; // never 0
+ }
- // read ARP packet
- if (recv(fd, &p, sizeof(p), 0) < 0) {
- why = "recv";
- goto bad;
+ 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;
}
- if (p.hdr.ether_type != htons(ETHERTYPE_ARP))
- continue;
+ continue;
+ }
+
+ // Read ARP packet
+ if (safe_read(sock_fd, &p, sizeof(p)) < 0) {
+ bb_perror_msg_and_die(bb_msg_read_error);
+ }
+ 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("%s recv arp type=%d, op=%d,\n",
- intf, ntohs(p.hdr.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));
- }
+ {
+ 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
- if (p.arp.arp_op != htons(ARPOP_REQUEST)
- && p.arp.arp_op != htons(ARPOP_REPLY))
- 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;
+ 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 (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;
+ 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!
+ 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", intf);
- timeout_ms = RATE_LIMIT_INTERVAL * 1000;
- state = RATE_LIMIT_PROBE;
- }
-
- // restart the whole protocol
- pick(&ip);
- 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(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;
- script_av[1] = (char*)"deconfig";
- run(script_av, intf, &ip);
-
- // restart the whole protocol
- pick(&ip);
- 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;
- pick(&ip);
- timeout_ms = 0;
- nprobes = 0;
- nclaims = 0;
- break;
- } // switch state
-
- break; // case 1 (packets arriving)
- default:
- why = "poll";
- goto bad;
- } // switch poll
- }
- bad:
- bb_perror_msg("%s, %s", intf, why);
- return EXIT_FAILURE;
+ // 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
}
projects / oweals / busybox.git / blobdiff