* 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 -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 "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 */
DEFEND
};
-#define VDBG(fmt,args...) \
- do { } while (0)
+#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)
+
/**
* 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;
do {
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 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 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.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_sha, source_eth, 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_tha, target_eth, ETH_ALEN);
memcpy(&p.arp.arp_tpa, &target_ip, sizeof(p.arp.arp_tpa));
// 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 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[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, struct in_addr *ip)
{
int status;
+ char *addr = addr; /* for gcc */
+ const char *fmt = "%s %s %s" + 3;
+
+ argv[2] = (char*)param;
- VDBG("%s run %s %s\n", intf, argv[0], argv[1]);
+ VDBG("%s run %s %s\n", argv[0], argv[1], argv[2]);
if (ip) {
- char *addr = inet_ntoa(*ip);
- setenv("ip", addr, 1);
- bb_info_msg("%s %s %s", argv[1], intf, addr);
+ addr = inet_ntoa(*ip);
+ xsetenv("ip", addr);
+ fmt -= 3;
}
+ bb_info_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);
}
/**
* 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;
+ int state;
char *r_opt;
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;
struct ifreq ifr;
- char *intf;
- char *script_av[3];
int timeout_ms; /* must be signed */
unsigned conflicts;
unsigned nprobes;
} 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 verbose (L.verbose )
memset(&L, 0, sizeof(L));
+ INIT_G();
#define FOREGROUND (opts & 1)
#define QUIT (opts & 2)
// 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: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 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_error_msg_and_die("invalid link address");
}
}
- // 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;
+
+ /* 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])
- intf = argv[0];
- script_av[0] = argv[1];
- setenv("interface", intf, 1);
+ xsetenv("interface", argv_intf);
// initialize the interface (modprobe, ifup, etc)
- script_av[1] = (char*)"init";
- if (run(script_av, intf, NULL))
+ if (run(argv, "init", NULL))
return EXIT_FAILURE;
// initialize saddr
+ // saddr is: { u16 sa_family; u8 sa_data[14]; }
//memset(&saddr, 0, sizeof(saddr));
- safe_strncpy(saddr.sa_data, intf, sizeof(saddr.sa_data));
+ //TODO: are we leaving sa_family == 0 (AF_UNSPEC)?!
+ safe_strncpy(saddr.sa_data, argv_intf, sizeof(saddr.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));
+ xbind(sock_fd, &saddr, sizeof(saddr));
// get the interface's ethernet address
//memset(&ifr, 0, sizeof(ifr));
- strncpy(ifr.ifr_name, intf, sizeof(ifr.ifr_name));
- xioctl(fd, SIOCGIFHWADDR, &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.
- srand(*(unsigned*)&ifr.ifr_hwaddr.sa_data);
+ {
+ uint32_t t;
+ move_from_unaligned32(t, ((char *)ð_addr + 2));
+ srand(t);
+ }
if (ip.s_addr == 0)
- pick(&ip);
+ ip.s_addr = pick();
// FIXME cases to handle:
// - zcip already running!
// 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_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];
unsigned deadline_us;
struct arp_packet p;
+ int source_ip_conflict;
+ int target_ip_conflict;
- 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
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.
}
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)) {
+ timeout_ms, argv_intf, nprobes, nclaims);
+
+ switch (safe_poll(fds, 1, timeout_ms)) {
+
+ default:
+ //bb_perror_msg("poll"); - done in safe_poll
+ return EXIT_FAILURE;
// timeout
case 0:
if (nprobes < PROBE_NUM) {
nprobes++;
VDBG("probe/%u %s@%s\n",
- nprobes, intf, inet_ntoa(ip));
- arp(fd, &saddr, ARPOP_REQUEST,
- ð_addr, null_ip,
- &null_addr, ip);
+ nprobes, argv_intf, inet_ntoa(ip));
timeout_ms = PROBE_MIN * 1000;
- timeout_ms += ms_rdelay(PROBE_MAX - PROBE_MIN);
+ 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, intf, inet_ntoa(ip));
- arp(fd, &saddr, ARPOP_REQUEST,
- ð_addr, ip,
- ð_addr, ip);
+ 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:
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);
+ 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
if (nclaims < ANNOUNCE_NUM) {
nclaims++;
VDBG("announce/%u %s@%s\n",
- nclaims, intf, inet_ntoa(ip));
- arp(fd, &saddr, ARPOP_REQUEST,
- ð_addr, ip,
- ð_addr, ip);
+ 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
// FIXME update filters
- script_av[1] = (char*)"config";
- run(script_av, intf, &ip);
+ run(argv, "config", &ip);
ready = 1;
conflicts = 0;
timeout_ms = -1; // Never timeout in the monitor state.
default:
// Invalid, should never happen. Restart the whole protocol.
state = PROBE;
- pick(&ip);
+ 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:
// We need to adjust the timeout in case we didn't receive
// a conflicting packet.
timeout_ms = 0;
} else {
VDBG("adjusting timeout\n");
- timeout_ms = diff / 1000;
- if (!timeout_ms) timeout_ms = 1;
+ timeout_ms = (diff / 1000) | 1; /* never 0 */
}
}
if (fds[0].revents & POLLERR) {
// FIXME: links routinely go down;
// this shouldn't necessarily exit.
- bb_error_msg("%s: poll error", intf);
+ bb_error_msg("iface %s is down", argv_intf);
if (ready) {
- script_av[1] = (char*)"deconfig";
- run(script_av, intf, &ip);
+ run(argv, "deconfig", &ip);
}
return EXIT_FAILURE;
}
}
// 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;
-
#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;
+ 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),
+ argv_intf, ntohs(p.eth.ether_type),
ntohs(p.arp.arp_op));
VDBG("\tsource=%s %s\n",
ether_ntoa(sha),
}
#endif
if (p.arp.arp_op != htons(ARPOP_REQUEST)
- && p.arp.arp_op != htons(ARPOP_REPLY))
+ && 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;
}
- 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;
+
+ 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;
+ }
}
VDBG("state = %d, source ip conflict = %d, target ip conflict = %d\n",
if (source_ip_conflict || target_ip_conflict) {
conflicts++;
if (conflicts >= MAX_CONFLICTS) {
- VDBG("%s ratelimit\n", intf);
+ VDBG("%s ratelimit\n", argv_intf);
timeout_ms = RATE_LIMIT_INTERVAL * 1000;
state = RATE_LIMIT_PROBE;
}
// restart the whole protocol
- pick(&ip);
+ ip.s_addr = pick();
timeout_ms = 0;
nprobes = 0;
nclaims = 0;
VDBG("monitor conflict -- defending\n");
state = DEFEND;
timeout_ms = DEFEND_INTERVAL * 1000;
- arp(fd, &saddr,
- ARPOP_REQUEST,
- ð_addr, ip,
- ð_addr, ip);
+ arp(/* ARPOP_REQUEST, */
+ /* ð_addr, */ ip,
+ ð_addr, ip);
}
break;
case DEFEND:
state = PROBE;
VDBG("defend conflict -- starting over\n");
ready = 0;
- script_av[1] = (char*)"deconfig";
- run(script_av, intf, &ip);
+ run(argv, "deconfig", &ip);
// restart the whole protocol
- pick(&ip);
+ ip.s_addr = pick();
timeout_ms = 0;
nprobes = 0;
nclaims = 0;
// Invalid, should never happen. Restart the whole protocol.
VDBG("invalid state -- starting over\n");
state = PROBE;
- pick(&ip);
+ ip.s_addr = pick();
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;
+ } // while (1)
+#undef argv_intf
}
projects / oweals / busybox.git / blobdiff