[BusyBox] ZeroConf IP (ZCIP) for BusyBox
Pantelis Antoniou
panto at intracom.gr
Mon Oct 25 06:55:12 UTC 2004
David Brownell wrote:
>Hi,
>
>There's an IETF working group that's been working on how IP networks would
>work with "zero configuration" effort required. Summary: use 169.254/16
>and multicast DNS, and your devices can be "network admins R optional"
>(within certain constraints). Also, see Apple's "Rendezvous" stuff.
>
>I know several folk have wanted embeddable versions of the IP addressing
>code, so here's a version that fits in less than 3KB code on ARM, as part
>of BusyBox. Add multicast DNS (one person said 38KB on XScale) and
>your system can start to offer some interesting capabilities ...
>
>Drop a line if you find this code useful, especially if you have patches.
>The code is a bit young for my taste, I expect it'll need some tweaks
>to work better on busy networks (with lots of ARP traffic).
>
>Tested on Linux 2.6.recent, on ARM and (standalone, no BusyBox) x86.
>
>- Dave
>
>
>
>
>
>
>------------------------------------------------------------------------
>
>This patch adds ZeroConf IP address allocation support to BusyBox, adding
>less than 3KB ARM code. Run by
>
> zcip eth0 /etc/zcip.script
>
>A sample script is included.
>
>It's a pretty close match to draft-ietf-zeroconf-ipv4-linklocal-17.txt (the
>July 2004 version) but this version has only had light testing so far: no
>busy networks, in particular. For now, avoid large deployments relying on
>this implementation without additional testing.
>
>
>
>--- busybox-1.00/docs/busybox_header.pod 2004-08-16 03:29:29.000000000 -0700
>+++ busybox/docs/busybox_header.pod 2004-10-18 15:33:42.000000000 -0700
>@@ -102,7 +102,7 @@
> touch, tr, traceroute, true, tty, udhcpc, udhcpd, umount, uname,
> uncompress, uniq, unix2dos, unzip, uptime, usleep, uudecode, uuencode,
> vconfig, vi, vlock, watch, watchdog, wc, wget, which, who, whoami, xargs,
>- yes, zcat
>+ yes, zcat, zcip
>
> =head1 COMMAND DESCRIPTIONS
>
>--- busybox-1.00/examples/zcip.script 1969-12-31 16:00:00.000000000 -0800
>+++ busybox/examples/zcip.script 2004-10-18 15:33:42.000000000 -0700
>@@ -0,0 +1,34 @@
>+#!/bin/sh
>+
>+# only for use as a "zcip" callback script
>+if [ "x$interface" = x ]
>+then
>+ exit 1
>+fi
>+
>+# zcip should start on boot/resume and various media changes
>+case "$1" in
>+init)
>+ # for now, zcip requires the link to be already up,
>+ # and it drops links when they go down. that may
>+ # not be the most robust model.
>+ exit 0
>+ ;;
>+config)
>+ if [ x$ip = x ]
>+ then
>+ exit 1
>+ fi
>+ # FIXME remember $ip for $interface, to use on restart
>+ exec ip address add dev $interface \
>+ scope link local $ip/16 broadcast +
>+ ;;
>+deconfig)
>+ if [ x$ip = x ]
>+ then
>+ exit 1
>+ fi
>+ exec ip address del dev $interface local $ip
>+ ;;
>+esac
>+exit 1
>--- busybox-1.00/include/applets.h 2004-08-26 16:01:34.000000000 -0700
>+++ busybox/include/applets.h 2004-10-18 15:33:42.000000000 -0700
>@@ -670,6 +670,9 @@
> #ifdef CONFIG_GUNZIP
> APPLET(zcat, gunzip_main, _BB_DIR_BIN, _BB_SUID_NEVER)
> #endif
>+#ifdef CONFIG_ZCIP
>+ APPLET(zcip, zcip_main, _BB_DIR_SBIN, _BB_SUID_NEVER)
>+#endif
>
> #if !defined(PROTOTYPES) && !defined(MAKE_USAGE)
> { 0,NULL,0 }
>--- busybox-1.00/include/usage.h 2004-09-14 09:23:56.000000000 -0700
>+++ busybox/include/usage.h 2004-10-18 15:33:42.000000000 -0700
>@@ -2882,4 +2882,14 @@
> #define zcat_full_usage \
> "Uncompress to stdout."
>
>+#define zcip_trivial_usage \
>+ "[OPTIONS] ifname script"
>+#define zcip_full_usage \
>+ "zcip manages a ZeroConf IPv4 link-local address.\n" \
>+ "Options:\n" \
>+ "\t-f foreground mode\n" \
>+ "\t-q quit after address (no daemon)\n" \
>+ "\t-r 169.254.x.x request this address first\n" \
>+ "\t-v verbose; show version\n"
>+
> #endif /* __BB_USAGE_H__ */
>--- busybox-1.00/networking/Config.in 2004-09-23 13:08:46.000000000 -0700
>+++ busybox/networking/Config.in 2004-10-18 15:33:42.000000000 -0700
>@@ -630,5 +630,14 @@
>
> source networking/udhcp/Config.in
>
>+config CONFIG_ZCIP
>+ bool "zcip"
>+ default n
>+ help
>+ zcip supports ZeroConf IPv4 address selection:
>+ it manages an address on the 169.254/16 network.
>+
>+ See http://www.zeroconf.org for further details.
>+
> endmenu
>
>--- busybox-1.00/networking/Makefile.in 2004-10-08 00:45:43.000000000 -0700
>+++ busybox/networking/Makefile.in 2004-10-20 01:48:43.504468768 -0700
>@@ -50,6 +50,7 @@
> NETWORKING-$(CONFIG_TRACEROUTE) += traceroute.o
> NETWORKING-$(CONFIG_VCONFIG) += vconfig.o
> NETWORKING-$(CONFIG_WGET) += wget.o
>+NETWORKING-$(CONFIG_ZCIP) += zcip.o
>
> libraries-y+=$(NETWORKING_DIR)$(NETWORKING_AR)
>
>--- busybox-1.00/networking/zcip.c 1969-12-31 16:00:00.000000000 -0800
>+++ busybox/networking/zcip.c 2004-10-20 02:18:13.390405208 -0700
>@@ -0,0 +1,558 @@
>+/*
>+ * ZeroConf IPv4 Link-Local addressing (see <http://www.zeroconf.org/>)
>+ *
>+ * Copyright (C) 2003 by Arthur van Hoff (avh at strangeberry.com)
>+ * Copyright (C) 2004 by David Brownell
>+ *
>+ * This program is free software; you can redistribute it and/or modify
>+ * it under the terms of the GNU General Public License as published by
>+ * the Free Software Foundation; either version 2 of the License, or
>+ * (at your option) any later version.
>+ *
>+ * This program is distributed in the hope that it will be useful,
>+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
>+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
>+ * General Public License for more details.
>+ *
>+ * You should have received a copy of the GNU General Public License
>+ * along with this program; if not, write to the Free Software
>+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
>+ * 02111-1307 USA
>+ */
>+
>+/*
>+ * This is a user-mode implementation that's a pretty close match to
>+ * draft-ietf-zeroconf-ipv4-linklocal-17.txt (the July 2004 version).
>+ * It can build as part of BusyBox or by itself:
>+ *
>+ * cc -Os -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
>+
>+ // TODO:
>+ // - more real-world usage/testing, especially daemon mode
>+ // - kernel packet filters to reduce scheduling noise
>+ // - avoid silent scripts failures, especially under load...
>+ // - implement some syslog option '-s'
>+ // - link status monitoring
>+
>+#include <errno.h>
>+#include <stdlib.h>
>+#include <stdio.h>
>+#include <string.h>
>+#include <time.h>
>+#include <unistd.h>
>+
>+#include <sys/ioctl.h>
>+#include <sys/types.h>
>+#include <sys/poll.h>
>+#include <sys/wait.h>
>+#include <sys/time.h>
>+
>+#include <arpa/inet.h>
>+#include <netinet/in.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>
>+
>+
>+struct arp_packet {
>+ struct ether_header hdr;
>+ struct arphdr arp;
>+ struct ether_addr source_addr;
>+ struct in_addr source_ip;
>+ struct ether_addr target_addr;
>+ struct in_addr target_ip;
>+ unsigned char pad[18];
>+} __attribute__ ((__packed__));
>+
>+/* 169.254.0.0 */
>+static uint32_t LINKLOCAL_ADDR = 0xa9fe0000;
>+static uint32_t LINKLOCAL_MASK = 0xFFFF0000;
>+
>+/* 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_COLLISIONS = 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 unsigned DEFEND_INTERVAL = 10;
>+
>+static const unsigned char ZCIP_VERSION[] = "0.7 (20 October 2004)";
>+static char *prog;
>+
>+static struct in_addr null_ip = { 0 };
>+static 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)
>+
>+/**
>+ * Convert an ethernet address to a printable string.
>+ */
>+static char *
>+ether2str(const struct ether_addr *addr)
>+{
>+ static char str[32];
>+
>+ snprintf(str, sizeof (str), "%02x:%02x:%02x:%02x:%02x:%02x",
>+ addr->ether_addr_octet[0], addr->ether_addr_octet[1],
>+ addr->ether_addr_octet[2], addr->ether_addr_octet[3],
>+ addr->ether_addr_octet[4], addr->ether_addr_octet[5]);
>+ return str;
>+}
>+
>+#else
>+
>+#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)
>+{
>+ ip->s_addr = htonl(LINKLOCAL_ADDR |
>+ ((abs(lrand48()) % 0xFD00) + 0x0100));
>+}
>+
>+/**
>+ * Broadcast an ARP packet.
>+ */
>+static int
>+arp(int fd, struct sockaddr *saddr, int op,
>+ struct ether_addr *source_addr, struct in_addr source_ip,
>+ 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);
>+ memcpy(p.hdr.ether_shost, source_addr, ETH_ALEN);
>+ 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));
>+
>+ // send it
>+ if (sendto(fd, &p, sizeof (p), 0, saddr, sizeof (*saddr)) < 0) {
>+ perror("sendto");
>+ return -errno;
>+ }
>+ return 0;
>+}
>+
>+/**
>+ * Run a script.
>+ */
>+int
>+run(char *script, char *arg, char *intf, struct in_addr *ip)
>+{
>+ int pid, status;
>+ char *why;
>+
>+ if (script != NULL) {
>+ VDBG("%s run %s %s\n", intf, script, arg);
>+#ifdef __uClinux__
>+#error need to use vfork/execle
>+#else
>+ pid = fork();
>+ if (pid < 0) {
>+ why = "fork";
>+ goto bad;
>+ }
>+ if (pid == 0) {
>+ // child process
>+ setenv("interface", intf, 1);
>+ if (ip != NULL) {
>+ setenv("ip", inet_ntoa(*ip), 1);
>+// FIXME syslog these calls
>+ }
>+ execl(script, script, arg, NULL);
>+ why = "execl";
>+ goto bad;
>+ }
>+#endif
>+ 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:
>+// FIXME syslog errors here
>+ perror(why);
>+ return -errno;
>+}
>+
>+#ifndef NO_BUSYBOX
>+#include "busybox.h"
>+#define main zcip_main
>+#endif
>+
>+/**
>+ * Print usage information.
>+ */
>+static void __attribute__ ((noreturn))
>+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\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
>+}
>+
>+/**
>+ * Return milliseconds of random delay, up to "secs" seconds.
>+ */
>+static inline unsigned
>+ms_rdelay(unsigned secs)
>+{
>+ return lrand48() % (secs * 1000);
>+}
>+
>+/**
>+ * main program
>+ */
>+int
>+main(int argc, char *argv[])
>+{
>+ char *intf = NULL;
>+ char *script = NULL;
>+ char *why;
>+ struct sockaddr saddr;
>+ struct arp_packet p;
>+ struct ether_addr addr;
>+ struct in_addr ip = { 0 };
>+ int fd;
>+ int quit = 0;
>+ int ready = 0;
>+ int foreground = 0;
>+ suseconds_t timeout = 0; // milliseconds
>+ time_t defend = 0;
>+ int collisions = 0;
>+ int nprobes = 0;
>+ int nclaims = 0;
>+ int t;
>+
>+ // 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) & LINKLOCAL_MASK)
>+ != LINKLOCAL_ADDR) {
>+ usage("invalid link address");
>+ }
>+ continue;
>+ case 'v':
>+ if (!verbose)
>+ printf("%s: version %s\n", prog, ZCIP_VERSION);
>+ verbose++;
>+ continue;
>+ default:
>+ usage("bad option");
>+ }
>+ }
>+ if (optind < argc - 1) {
>+ intf = argv[optind++];
>+ script = argv[optind++];
>+ }
>+ if (optind != argc || !intf)
>+ usage("wrong number of arguments");
>+
>+ // initialize the interface (modprobe, ifup, etc)
>+ if (run(script, "init", intf, NULL) < 0)
>+ return EXIT_FAILURE;
>+
>+ // initialize saddr
>+ memset(&saddr, 0, sizeof (saddr));
>+ 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";
>+ goto bad;
>+ }
>+ // bind to the interface's ARP socket
>+ if (bind(fd, &saddr, sizeof (saddr)) < 0) {
>+ why = "bind";
>+ goto bad;
>+ } 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 bad;
>+ }
>+ memcpy(&addr, &ifr.ifr_hwaddr.sa_data, ETHER_ADDR_LEN);
>+
>+ // start with some stable ip address, either a function of
>+ // the hardware address or else the last address we used.
>+ // retry timers and new addresses shouldn't be predictable.
>+ memcpy(seed, &ifr.ifr_hwaddr.sa_data, ETHER_ADDR_LEN);
>+ if (ip.s_addr == 0) {
>+ seed48(seed);
>+ pick(&ip);
>+ }
>+ t = time(0);
>+ seed[0] ^= t;
>+ seed[1] ^= t >> 16;
>+ seed48(seed);
>+ }
>+
>+ // 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;
>+ }
>+ }
>+
>+ // run the dynamic address negotiation protocol,
>+ // restarting after address collisions:
>+ // - start with some address we want to try
>+ // - short random delay
>+ // - arp probes to see if another host else uses it
>+ // - arp announcements that we're claiming it
>+ // - use it
>+ // - defend it, within limits
>+ while (1) {
>+ struct pollfd fds[1];
>+ struct timeval tv1;
>+
>+ fds[0].fd = fd;
>+ fds[0].events = POLLIN | POLLERR;
>+ fds[0].revents = 0;
>+
>+ // poll, being ready to adjust current timeout
>+ if (timeout > 0) {
>+ gettimeofday(&tv1, NULL);
>+ tv1.tv_usec += (timeout % 1000) * 1000;
>+ if (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
>+ // 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)) {
>+
>+ // timeouts trigger protocol transitions
>+ 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);
>+ 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);
>+ if (nclaims < ANNOUNCE_NUM) {
>+ timeout = ANNOUNCE_INTERVAL * 1000;
>+ } else {
>+ // link is ok to use earlier
>+ run(script, "config", intf, &ip);
>+ ready = 1;
>+ collisions = 0;
>+ timeout = -1;
>+
>+ // NOTE: all other exit paths
>+ // should deconfig ...
>+ if (quit)
>+ return EXIT_SUCCESS;
>+ // FIXME update filters
>+ }
>+ }
>+ break;
>+
>+ // packets arriving
>+ case 1:
>+ // maybe adjust timeout
>+ if (timeout > 0) {
>+ struct timeval tv2;
>+
>+ gettimeofday(&tv2, NULL);
>+ if (timercmp(&tv1, &tv2, <)) {
>+ timeout = -1;
>+ } else {
>+ 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.
>+ fprintf(stderr, "%s %s: poll error\n",
>+ prog, intf);
>+ if (ready) {
>+ run(script, "deconfig",
>+ intf, &ip);
>+ }
>+ return EXIT_FAILURE;
>+ }
>+ continue;
>+ }
>+ // read ARP packet
>+ if (recv(fd, &p, sizeof (p), 0) < 0) {
>+// FIXME stderr may be bad here (syslog)
>+ why = "recv";
>+ goto bad;
>+ }
>+ if (p.hdr.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",
>+ ether2str(&p.source_addr),
>+ inet_ntoa(p.source_ip));
>+ VDBG("\ttarget=%s %s\n",
>+ ether2str(&p.target_addr),
>+ inet_ntoa(p.target_ip));
>+ if (p.arp.ar_op != htons(ARPOP_REQUEST)
>+ && p.arp.ar_op != htons(ARPOP_REPLY))
>+ continue;
>+
>+ // some cases are always collisions
>+ 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,
>+ ether2str(&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;
>+ }
>+ defend = now;
>+ ready = 0;
>+ run(script, "deconfig", intf, &ip);
>+ // FIXME rm filters: setsockopt(fd,
>+ // SO_DETACH_FILTER, ...)
>+ }
>+ collisions++;
>+ if (collisions >= MAX_COLLISIONS) {
>+ VDBG("%s ratelimit\n", intf);
>+ sleep(RATE_LIMIT_INTERVAL);
>+ }
>+ // restart the whole protocol
>+ 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;
>+
>+ default:
>+// FIXME stderr may be bad here (syslog)
>+ why = "poll";
>+ goto bad;
>+ }
>+ }
>+bad:
>+ perror(why);
>+ return EXIT_FAILURE;
>+}
>
>
>------------------------------------------------------------------------
>
>#!/bin/sh
>
>PATH=$PATH
>ZCIP=/sbin/zcip
>IFNAME=eth0
>SCRIPT=/etc/zcip.script
>
># SHOULD use "-r 169.254.x.x" to reclaim the last value
># it should have been saved away somewhere by $SCRIPT
>FLAGS=""
>
>case "$1" in
>start|restart)
> ip link set $IFNAME up
> exec $ZCIP $FLAGS $IFNAME $SCRIPT
> ;;
>stop)
> # FIXME should probably save and use daemon's PID
> ;;
>status)
> ;;
>*)
> echo "Usage: $0 {start|stop|status|restart}"
> exit 1
> ;;
>esac
>
>
>------------------------------------------------------------------------
>
>_______________________________________________
>busybox mailing list
>busybox at mail.busybox.net
>http://busybox.net/mailman/listinfo/busybox
>
>
Hi David.
This sure is interesting.
Will get back to you when I test it on my ppc based board.
Regards
Pantelis
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