David Brownell submitted a new applet, zcip, based on RFC 3927. This is
authorlandley <landley@69ca8d6d-28ef-0310-b511-8ec308f3f277>
Sat, 30 Apr 2005 03:49:37 +0000 (03:49 +0000)
committerlandley <landley@69ca8d6d-28ef-0310-b511-8ec308f3f277>
Sat, 30 Apr 2005 03:49:37 +0000 (03:49 +0000)
version 0418b.  It compiled.

git-svn-id: svn://busybox.net/trunk/busybox@10206 69ca8d6d-28ef-0310-b511-8ec308f3f277

examples/zcip.script [new file with mode: 0644]
include/applets.h
include/usage.h
networking/Config.in
networking/Makefile.in
networking/zcip.c [new file with mode: 0644]

diff --git a/examples/zcip.script b/examples/zcip.script
new file mode 100644 (file)
index 0000000..988e542
--- /dev/null
@@ -0,0 +1,38 @@
+#!/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 "$1" in
+init)
+       # for now, zcip requires the link to be already up,
+       # and it drops links when they go down.  that isn't
+       # the most robust model...
+       exit 0
+       ;;
+config)
+       if [ "x$ip" = x ]
+       then
+               exit 1
+       fi
+       # remember $ip for $interface, to use on restart
+       if [ "x$IP" != x -a -w "$IP.$interface" ]
+       then
+               echo $ip > "$IP.$interface"
+       fi
+       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
index 755eb01..7f6f758 100644 (file)
 #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 }
index 04d6ff4..b57644b 100644 (file)
 #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__ */
index cf2f1dc..418ef4b 100644 (file)
@@ -637,5 +637,16 @@ config CONFIG_FEATURE_WGET_IP6_LITERAL
 
 source networking/udhcp/Config.in
 
+config CONFIG_ZCIP
+       bool "zcip"
+       default n
+       help
+         ZCIP provides ZeroConf IPv4 address selection, according to RFC 3927.
+         It's a daemon that allocates and defends a dynamically assigned
+         address on the 169.254/16 network, requiring no system administrator.
+
+         See http://www.zeroconf.org for further details, and "zcip.script"
+         in the busybox examples.
+
 endmenu
 
index 4e27dbc..778d0ba 100644 (file)
@@ -51,6 +51,7 @@ NETWORKING-$(CONFIG_TFTP)     += tftp.o
 NETWORKING-$(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)
 
diff --git a/networking/zcip.c b/networking/zcip.c
new file mode 100644 (file)
index 0000000..ccf399b
--- /dev/null
@@ -0,0 +1,550 @@
+/*
+ * 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
+ *
+ * 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 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
+
+// TODO:
+// - more real-world usage/testing, especially daemon mode
+// - kernel packet filters to reduce scheduling noise
+// - 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>
+#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;
+       // 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__));
+
+/* 169.254.0.0 */
+static const uint32_t 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
+
+#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)
+{
+       unsigned        tmp;
+
+       /* use cheaper math than lrand48() mod N */
+       do {
+               tmp = (lrand48() >> 16) & IN_CLASSB_HOST;
+       } while (tmp > (IN_CLASSB_HOST - 0x0200));
+       ip->s_addr = 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)
+{
+       struct arp_packet 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.
+ */
+static 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);
+               if (ip != NULL) {
+                       char *addr = inet_ntoa(*ip);
+                       setenv("ip", addr, 1);
+                       syslog(LOG_INFO, "%s %s %s", arg, intf, addr);
+               }
+
+               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);
+               } 
+
+               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;
+}
+
+#ifndef        NO_BUSYBOX
+#include "busybox.h"
+#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 (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
+}
+
+/**
+ * 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[])
+       __attribute__ ((weak, alias ("zcip_main")));
+
+int zcip_main(int argc, 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;
+
+       // 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) {
+                               usage("invalid link address");
+                       }
+                       continue;
+               case 'v':
+                       if (!verbose)
+                               printf("%s: version %s\n", prog, ZCIP_VERSION);
+                       verbose++;
+                       foreground = 1;
+                       continue;
+               default:
+                       usage("bad option");
+               }
+       }
+       if (optind < argc - 1) {
+               intf = argv[optind++];
+               setenv("interface", intf, 1);
+               script = argv[optind++];
+       }
+       if (optind != argc || !intf)
+               usage("wrong number of arguments");
+       openlog(prog, 0, LOG_DAEMON);
+
+       // 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";
+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);
+       }
+
+       // 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);
+       }
+
+       // 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 announcements that we're claiming it
+       //  - use it
+       //  - defend it, within limits
+       while (1) {
+               struct pollfd fds[1];
+               struct timeval tv1;
+               struct arp_packet p;
+
+               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) {
+                       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;
+                                       conflicts = 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) {
+                               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",
+                                       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))
+                               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;
+                                       }
+                                       defend = now;
+                                       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;
+                       }
+                       // 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;
+}