/*** This file is part of avahi. avahi is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. avahi 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 Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with avahi; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA. ***/ #ifdef HAVE_CONFIG_H #include #endif #include #include #include #include #include #include #ifdef __FreeBSD__ #include #endif #ifdef __linux__ #include #endif #include #include #ifdef __FreeBSD__ #include #include #endif #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifndef __linux__ #include /* Old versions of PCAP defined it as D_IN */ #ifndef PCAP_D_IN #define PCAP_D_IN D_IN #endif #endif #include "avahi-common/avahi-malloc.h" #include #include #include #include #include #include #include #include "main.h" #include "iface.h" /* An implementation of RFC 3927 */ /* Constants from the RFC */ #define PROBE_WAIT 1 #define PROBE_NUM 3 #define PROBE_MIN 1 #define PROBE_MAX 2 #define ANNOUNCE_WAIT 2 #define ANNOUNCE_NUM 2 #define ANNOUNCE_INTERVAL 2 #define MAX_CONFLICTS 10 #define RATE_LIMIT_INTERVAL 60 #define DEFEND_INTERVAL 10 #define IPV4LL_NETWORK 0xA9FE0000L #define IPV4LL_NETMASK 0xFFFF0000L #define IPV4LL_HOSTMASK 0x0000FFFFL #define IPV4LL_BROADCAST 0xA9FEFFFFL #define ETHER_ADDRLEN 6 #define ETHER_HDR_SIZE (2+2*ETHER_ADDRLEN) #define ARP_PACKET_SIZE (8+4+4+2*ETHER_ADDRLEN) typedef enum ArpOperation { ARP_REQUEST = 1, ARP_RESPONSE = 2 } ArpOperation; typedef struct ArpPacketInfo { ArpOperation operation; uint32_t sender_ip_address, target_ip_address; uint8_t sender_hw_address[ETHER_ADDRLEN], target_hw_address[ETHER_ADDRLEN]; } ArpPacketInfo; typedef struct ArpPacket { uint8_t *ether_header; uint8_t *ether_payload; } ArpPacket; static State state = STATE_START; static int n_iteration = 0; static int n_conflict = 0; static char *interface_name = NULL; static char *pid_file_name = NULL; static uint32_t start_address = 0; static char *argv0 = NULL; static int daemonize = 0; static int wait_for_address = 0; static int use_syslog = 0; static int debug = 0; static int modify_proc_title = 1; static int force_bind = 0; #ifdef HAVE_CHROOT static int no_chroot = 0; #endif static int no_drop_root = 0; static int wrote_pid_file = 0; static char *action_script = NULL; static enum { DAEMON_RUN, DAEMON_KILL, DAEMON_REFRESH, DAEMON_VERSION, DAEMON_HELP, DAEMON_CHECK } command = DAEMON_RUN; typedef enum CalloutEvent { CALLOUT_BIND, CALLOUT_CONFLICT, CALLOUT_UNBIND, CALLOUT_STOP, CALLOUT_MAX } CalloutEvent; static const char * const callout_event_table[CALLOUT_MAX] = { [CALLOUT_BIND] = "BIND", [CALLOUT_CONFLICT] = "CONFLICT", [CALLOUT_UNBIND] = "UNBIND", [CALLOUT_STOP] = "STOP" }; typedef struct CalloutEventInfo { CalloutEvent event; uint32_t address; int ifindex; } CalloutEventInfo; #define RANDOM_DEVICE "/dev/urandom" #define DEBUG(x) \ do { \ if (debug) { \ x; \ } \ } while (0) static void init_rand_seed(void) { int fd; unsigned seed = 0; /* Try to initialize seed from /dev/urandom, to make it a little * less predictable, and to make sure that multiple machines * booted at the same time choose different random seeds. */ if ((fd = open(RANDOM_DEVICE, O_RDONLY)) >= 0) { read(fd, &seed, sizeof(seed)); close(fd); } /* If the initialization failed by some reason, we add the time to the seed */ seed ^= (unsigned) time(NULL); srand(seed); } static uint32_t pick_addr(uint32_t old_addr) { uint32_t addr; do { unsigned r = (unsigned) rand(); /* Reduce to 16 bits */ while (r > 0xFFFF) r = (r >> 16) ^ (r & 0xFFFF); addr = htonl(IPV4LL_NETWORK | (uint32_t) r); } while (addr == old_addr || !is_ll_address(addr)); return addr; } static int load_address(const char *fn, uint32_t *addr) { FILE *f; unsigned a, b, c, d; assert(fn); assert(addr); if (!(f = fopen(fn, "r"))) { if (errno == ENOENT) { *addr = 0; return 0; } daemon_log(LOG_ERR, "fopen() failed: %s", strerror(errno)); goto fail; } if (fscanf(f, "%u.%u.%u.%u\n", &a, &b, &c, &d) != 4) { daemon_log(LOG_ERR, "Parse failure"); goto fail; } fclose(f); *addr = htonl((a << 24) | (b << 16) | (c << 8) | d); return 0; fail: if (f) fclose(f); return -1; } static int save_address(const char *fn, uint32_t addr) { FILE *f; char buf[32]; mode_t u; assert(fn); u = umask(0033); if (!(f = fopen(fn, "w"))) { daemon_log(LOG_ERR, "fopen() failed: %s", strerror(errno)); goto fail; } umask(u); fprintf(f, "%s\n", inet_ntop(AF_INET, &addr, buf, sizeof (buf))); fclose(f); return 0; fail: if (f) fclose(f); umask(u); return -1; } /* * Allocate a buffer with two pointers in front, one of which is * guaranteed to point ETHER_HDR_SIZE bytes into it. */ static ArpPacket* packet_new(size_t packet_len) { ArpPacket *p; uint8_t *b; assert(packet_len > 0); #ifdef __linux__ b = avahi_new0(uint8_t, sizeof(struct ArpPacket) + packet_len); p = (ArpPacket*) b; p->ether_header = NULL; p->ether_payload = b + sizeof(struct ArpPacket); #else b = avahi_new0(uint8_t, sizeof(struct ArpPacket) + ETHER_HDR_SIZE + packet_len); p = (ArpPacket*) b; p->ether_header = b + sizeof(struct ArpPacket); p->ether_payload = b + sizeof(struct ArpPacket) + ETHER_HDR_SIZE; #endif return p; } static ArpPacket* packet_new_with_info(const ArpPacketInfo *info, size_t *packet_len) { ArpPacket *p = NULL; uint8_t *r; assert(info); assert(info->operation == ARP_REQUEST || info->operation == ARP_RESPONSE); assert(packet_len != NULL); *packet_len = ARP_PACKET_SIZE; p = packet_new(*packet_len); r = p->ether_payload; r[1] = 1; /* HTYPE */ r[2] = 8; /* PTYPE */ r[4] = ETHER_ADDRLEN; /* HLEN */ r[5] = 4; /* PLEN */ r[7] = (uint8_t) info->operation; memcpy(r+8, info->sender_hw_address, ETHER_ADDRLEN); memcpy(r+14, &info->sender_ip_address, 4); memcpy(r+18, info->target_hw_address, ETHER_ADDRLEN); memcpy(r+24, &info->target_ip_address, 4); return p; } static ArpPacket *packet_new_probe(uint32_t ip_address, const uint8_t*hw_address, size_t *packet_len) { ArpPacketInfo info; memset(&info, 0, sizeof(info)); info.operation = ARP_REQUEST; memcpy(info.sender_hw_address, hw_address, ETHER_ADDRLEN); info.target_ip_address = ip_address; return packet_new_with_info(&info, packet_len); } static ArpPacket *packet_new_announcement(uint32_t ip_address, const uint8_t* hw_address, size_t *packet_len) { ArpPacketInfo info; memset(&info, 0, sizeof(info)); info.operation = ARP_REQUEST; memcpy(info.sender_hw_address, hw_address, ETHER_ADDRLEN); info.target_ip_address = ip_address; info.sender_ip_address = ip_address; return packet_new_with_info(&info, packet_len); } static int packet_parse(const ArpPacket *packet, size_t packet_len, ArpPacketInfo *info) { const uint8_t *p; assert(packet); p = (uint8_t *)packet->ether_payload; assert(p); if (packet_len < ARP_PACKET_SIZE) return -1; /* Check HTYPE and PTYPE */ if (p[0] != 0 || p[1] != 1 || p[2] != 8 || p[3] != 0) return -1; /* Check HLEN, PLEN, OPERATION */ if (p[4] != ETHER_ADDRLEN || p[5] != 4 || p[6] != 0 || (p[7] != 1 && p[7] != 2)) return -1; info->operation = p[7]; memcpy(info->sender_hw_address, p+8, ETHER_ADDRLEN); memcpy(&info->sender_ip_address, p+14, 4); memcpy(info->target_hw_address, p+18, ETHER_ADDRLEN); memcpy(&info->target_ip_address, p+24, 4); return 0; } static void set_state(State st, int reset_counter, uint32_t address) { static const char* const state_table[] = { [STATE_START] = "START", [STATE_WAITING_PROBE] = "WAITING_PROBE", [STATE_PROBING] = "PROBING", [STATE_WAITING_ANNOUNCE] = "WAITING_ANNOUNCE", [STATE_ANNOUNCING] = "ANNOUNCING", [STATE_RUNNING] = "RUNNING", [STATE_SLEEPING] = "SLEEPING" }; char buf[64]; assert(st < STATE_MAX); if (st == state && !reset_counter) { n_iteration++; DEBUG(daemon_log(LOG_DEBUG, "State iteration %s-%i", state_table[state], n_iteration)); } else { DEBUG(daemon_log(LOG_DEBUG, "State transition %s-%i -> %s-0", state_table[state], n_iteration, state_table[st])); state = st; n_iteration = 0; } if (state == STATE_SLEEPING) avahi_set_proc_title(argv0, "%s: [%s] sleeping", argv0, interface_name); else if (state == STATE_ANNOUNCING) avahi_set_proc_title(argv0, "%s: [%s] announcing %s", argv0, interface_name, inet_ntop(AF_INET, &address, buf, sizeof(buf))); else if (state == STATE_RUNNING) avahi_set_proc_title(argv0, "%s: [%s] bound %s", argv0, interface_name, inet_ntop(AF_INET, &address, buf, sizeof(buf))); else avahi_set_proc_title(argv0, "%s: [%s] probing %s", argv0, interface_name, inet_ntop(AF_INET, &address, buf, sizeof(buf))); } static int interface_up(int iface) { int fd = -1; struct ifreq ifreq; if ((fd = socket(PF_INET, SOCK_DGRAM, 0)) < 0) { daemon_log(LOG_ERR, "socket() failed: %s", strerror(errno)); goto fail; } memset(&ifreq, 0, sizeof(ifreq)); if (!if_indextoname(iface, ifreq.ifr_name)) { daemon_log(LOG_ERR, "if_indextoname() failed: %s", strerror(errno)); goto fail; } if (ioctl(fd, SIOCGIFFLAGS, &ifreq) < 0) { daemon_log(LOG_ERR, "SIOCGIFFLAGS failed: %s", strerror(errno)); goto fail; } ifreq.ifr_flags |= IFF_UP; if (ioctl(fd, SIOCSIFFLAGS, &ifreq) < 0) { daemon_log(LOG_ERR, "SIOCSIFFLAGS failed: %s", strerror(errno)); goto fail; } close(fd); return 0; fail: if (fd >= 0) close(fd); return -1; } #ifdef __linux__ /* Linux 'packet socket' specific implementation */ static int open_socket(int iface, uint8_t *hw_address) { int fd = -1; struct sockaddr_ll sa; socklen_t sa_len; if (interface_up(iface) < 0) goto fail; if ((fd = socket(PF_PACKET, SOCK_DGRAM, 0)) < 0) { daemon_log(LOG_ERR, "socket() failed: %s", strerror(errno)); goto fail; } memset(&sa, 0, sizeof(sa)); sa.sll_family = AF_PACKET; sa.sll_protocol = htons(ETH_P_ARP); sa.sll_ifindex = iface; if (bind(fd, (struct sockaddr*) &sa, sizeof(sa)) < 0) { daemon_log(LOG_ERR, "bind() failed: %s", strerror(errno)); goto fail; } sa_len = sizeof(sa); if (getsockname(fd, (struct sockaddr*) &sa, &sa_len) < 0) { daemon_log(LOG_ERR, "getsockname() failed: %s", strerror(errno)); goto fail; } if (sa.sll_halen != ETHER_ADDRLEN) { daemon_log(LOG_ERR, "getsockname() returned invalid hardware address."); goto fail; } memcpy(hw_address, sa.sll_addr, ETHER_ADDRLEN); return fd; fail: if (fd >= 0) close(fd); return -1; } static int send_packet(int fd, int iface, ArpPacket *packet, size_t packet_len) { struct sockaddr_ll sa; assert(fd >= 0); assert(packet); assert(packet_len > 0); memset(&sa, 0, sizeof(sa)); sa.sll_family = AF_PACKET; sa.sll_protocol = htons(ETH_P_ARP); sa.sll_ifindex = iface; sa.sll_halen = ETHER_ADDRLEN; memset(sa.sll_addr, 0xFF, ETHER_ADDRLEN); if (sendto(fd, packet->ether_payload, packet_len, 0, (struct sockaddr*) &sa, sizeof(sa)) < 0) { daemon_log(LOG_ERR, "sendto() failed: %s", strerror(errno)); return -1; } return 0; } static int recv_packet(int fd, ArpPacket **packet, size_t *packet_len) { int s; struct sockaddr_ll sa; socklen_t sa_len; ssize_t r; assert(fd >= 0); assert(packet); assert(packet_len); *packet = NULL; if (ioctl(fd, FIONREAD, &s) < 0) { daemon_log(LOG_ERR, "FIONREAD failed: %s", strerror(errno)); goto fail; } if (s <= 0) s = 4096; *packet = packet_new(s); sa_len = sizeof(sa); if ((r = recvfrom(fd, (*packet)->ether_payload, s, 0, (struct sockaddr*) &sa, &sa_len)) < 0) { daemon_log(LOG_ERR, "recvfrom() failed: %s", strerror(errno)); goto fail; } *packet_len = (size_t) r; return 0; fail: if (*packet) { avahi_free(*packet); *packet = NULL; } return -1; } static void close_socket(int fd) { close(fd); } #else /* !__linux__ */ /* PCAP-based implementation */ static pcap_t *__pp; static char __pcap_errbuf[PCAP_ERRBUF_SIZE]; static uint8_t __lladdr[ETHER_ADDRLEN]; #ifndef elementsof #define elementsof(array) (sizeof(array)/sizeof(array[0])) #endif static int __get_ether_addr(int ifindex, u_char *lladdr) { int mib[6]; char *buf; struct if_msghdr *ifm; char *lim; char *next; struct sockaddr_dl *sdl; size_t len; mib[0] = CTL_NET; mib[1] = PF_ROUTE; mib[2] = 0; mib[3] = 0; mib[4] = NET_RT_IFLIST; mib[5] = ifindex; if (sysctl(mib, elementsof(mib), NULL, &len, NULL, 0) != 0) { daemon_log(LOG_ERR, "sysctl(NET_RT_IFLIST): %s", strerror(errno)); return -1; } buf = avahi_malloc(len); if (sysctl(mib, elementsof(mib), buf, &len, NULL, 0) != 0) { daemon_log(LOG_ERR, "sysctl(NET_RT_IFLIST): %s", strerror(errno)); free(buf); return -1; } lim = buf + len; for (next = buf; next < lim; next += ifm->ifm_msglen) { ifm = (struct if_msghdr *)next; if (ifm->ifm_type == RTM_IFINFO) { sdl = (struct sockaddr_dl *)(ifm + 1); memcpy(lladdr, LLADDR(sdl), ETHER_ADDRLEN); } } avahi_free(buf); return 0; } #define PCAP_TIMEOUT 500 /* 0.5s */ static int open_socket(int iface, uint8_t *hw_address) { struct bpf_program bpf; char *filter; char ifname[IFNAMSIZ]; pcap_t *pp; int err; int fd; assert(__pp == NULL); if (interface_up(iface) < 0) return -1; if (__get_ether_addr(iface, __lladdr) == -1) return -1; if (if_indextoname(iface, ifname) == NULL) return -1; /* * Using a timeout for BPF is fairly portable across BSDs. On most * modern versions, using the timeout/nonblock/poll method results in * fairly sane behavior, with the timeout only coming into play during * the next_ex() call itself (so, for us, that's only when there's * data). On older versions, it may result in a PCAP_TIMEOUT busy-wait * on some versions, though, as the poll() may terminate at the * PCAP_TIMEOUT instead of the poll() timeout. */ pp = pcap_open_live(ifname, 1500, 0, PCAP_TIMEOUT, __pcap_errbuf); if (pp == NULL) { return (-1); } err = pcap_set_datalink(pp, DLT_EN10MB); if (err == -1) { daemon_log(LOG_ERR, "pcap_set_datalink: %s", pcap_geterr(pp)); pcap_close(pp); return (-1); } err = pcap_setdirection(pp, PCAP_D_IN); if (err == -1) { daemon_log(LOG_ERR, "pcap_setdirection: %s", pcap_geterr(pp)); pcap_close(pp); return (-1); } fd = pcap_get_selectable_fd(pp); if (fd == -1) { pcap_close(pp); return (-1); } /* * Using setnonblock is a portability stop-gap. Using the timeout in * combination with setnonblock will ensure on most BSDs that the * next_ex call returns in a timely fashion. */ err = pcap_setnonblock(pp, 1, __pcap_errbuf); if (err == -1) { pcap_close(pp); return (-1); } filter = avahi_strdup_printf("arp and (ether dst ff:ff:ff:ff:ff:ff or " "%02x:%02x:%02x:%02x:%02x:%02x)", __lladdr[0], __lladdr[1], __lladdr[2], __lladdr[3], __lladdr[4], __lladdr[5]); DEBUG(daemon_log(LOG_DEBUG, "Using pcap filter '%s'", filter)); err = pcap_compile(pp, &bpf, filter, 1, 0); avahi_free(filter); if (err == -1) { daemon_log(LOG_ERR, "pcap_compile: %s", pcap_geterr(pp)); pcap_close(pp); return (-1); } err = pcap_setfilter(pp, &bpf); if (err == -1) { daemon_log(LOG_ERR, "pcap_setfilter: %s", pcap_geterr(pp)); pcap_close(pp); return (-1); } pcap_freecode(&bpf); /* Stash pcap-specific context away. */ memcpy(hw_address, __lladdr, ETHER_ADDRLEN); __pp = pp; return (fd); } static void close_socket(int fd AVAHI_GCC_UNUSED) { assert(__pp != NULL); pcap_close(__pp); __pp = NULL; } /* * We trick avahi into allocating sizeof(packet) + sizeof(ether_header), * and prepend the required ethernet header information before sending. */ static int send_packet(int fd AVAHI_GCC_UNUSED, int iface AVAHI_GCC_UNUSED, ArpPacket *packet, size_t packet_len) { struct ether_header *eh; assert(__pp != NULL); assert(packet != NULL); eh = (struct ether_header *)packet->ether_header; memset(eh->ether_dhost, 0xFF, ETHER_ADDRLEN); memcpy(eh->ether_shost, __lladdr, ETHER_ADDRLEN); eh->ether_type = htons(0x0806); return (pcap_inject(__pp, (void *)eh, packet_len + sizeof(*eh))); } static int recv_packet(int fd AVAHI_GCC_UNUSED, ArpPacket **packet, size_t *packet_len) { struct pcap_pkthdr *ph; u_char *pd; ArpPacket *ap; int err; int retval; assert(__pp != NULL); assert(packet != NULL); assert(packet_len != NULL); *packet = NULL; *packet_len = 0; retval = -1; err = pcap_next_ex(__pp, &ph, (const u_char **)&pd); if (err == 1 && ph->caplen <= ph->len) { ap = packet_new(ph->caplen); memcpy(ap->ether_header, pd, ph->caplen); *packet = ap; *packet_len = (ph->caplen - sizeof(struct ether_header)); retval = 0; } else if (err >= 0) { /* * err == 1: Just drop bogus packets (>1500 for an arp packet!?) * on the floor. * * err == 0: We might have had traffic on the pcap fd that * didn't match the filter, in which case we'll get 0 packets. */ retval = 0; } else daemon_log(LOG_ERR, "pcap_next_ex(%d): %s", err, pcap_geterr(__pp)); return (retval); } #endif /* __linux__ */ int is_ll_address(uint32_t addr) { return ((ntohl(addr) & IPV4LL_NETMASK) == IPV4LL_NETWORK) && ((ntohl(addr) & 0x0000FF00) != 0x0000) && ((ntohl(addr) & 0x0000FF00) != 0xFF00); } static struct timeval *elapse_time(struct timeval *tv, unsigned msec, unsigned jitter) { assert(tv); gettimeofday(tv, NULL); if (msec) avahi_timeval_add(tv, (AvahiUsec) msec*1000); if (jitter) avahi_timeval_add(tv, (AvahiUsec) (jitter*1000.0*rand()/(RAND_MAX+1.0))); return tv; } static FILE* fork_dispatcher(void) { FILE *ret; int fds[2]; pid_t pid; if (pipe(fds) < 0) { daemon_log(LOG_ERR, "pipe() failed: %s", strerror(errno)); goto fail; } if ((pid = fork()) < 0) goto fail; else if (pid == 0) { FILE *f = NULL; int r = 1; /* Please note that the signal pipe is not closed at this * point, signals will thus be dispatched in the main * process. */ daemon_retval_done(); avahi_set_proc_title(argv0, "%s: [%s] callout dispatcher", argv0, interface_name); close(fds[1]); if (!(f = fdopen(fds[0], "r"))) { daemon_log(LOG_ERR, "fdopen() failed: %s", strerror(errno)); goto dispatcher_fail; } for (;;) { CalloutEventInfo info; char name[IFNAMSIZ], buf[64]; int k; if (fread(&info, sizeof(info), 1, f) != 1) { if (feof(f)) break; daemon_log(LOG_ERR, "fread() failed: %s", strerror(errno)); goto dispatcher_fail; } assert(info.event <= CALLOUT_MAX); if (!if_indextoname(info.ifindex, name)) { daemon_log(LOG_ERR, "if_indextoname() failed: %s", strerror(errno)); continue; } if (daemon_exec("/", &k, action_script, action_script, callout_event_table[info.event], name, inet_ntop(AF_INET, &info.address, buf, sizeof(buf)), NULL) < 0) { daemon_log(LOG_ERR, "Failed to run script: %s", strerror(errno)); continue; } if (k != 0) daemon_log(LOG_WARNING, "Script execution failed with return value %i", k); } r = 0; dispatcher_fail: if (f) fclose(f); #ifdef HAVE_CHROOT /* If the main process is trapped inside a chroot() we have to * remove the PID file for it */ if (!no_chroot && wrote_pid_file) daemon_pid_file_remove(); #endif _exit(r); } /* parent */ close(fds[0]); fds[0] = -1; if (!(ret = fdopen(fds[1], "w"))) { daemon_log(LOG_ERR, "fdopen() failed: %s", strerror(errno)); goto fail; } return ret; fail: if (fds[0] >= 0) close(fds[0]); if (fds[1] >= 0) close(fds[1]); return NULL; } static int do_callout(FILE *f, CalloutEvent event, int iface, uint32_t addr) { CalloutEventInfo info; char buf[64], ifname[IFNAMSIZ]; daemon_log(LOG_INFO, "Callout %s, address %s on interface %s", callout_event_table[event], inet_ntop(AF_INET, &addr, buf, sizeof(buf)), if_indextoname(iface, ifname)); info.event = event; info.ifindex = iface; info.address = addr; if (fwrite(&info, sizeof(info), 1, f) != 1 || fflush(f) != 0) { daemon_log(LOG_ERR, "Failed to write callout event: %s", strerror(errno)); return -1; } return 0; } #define set_env(key, value) putenv(avahi_strdup_printf("%s=%s", (key), (value))) static int drop_privs(void) { struct passwd *pw; struct group * gr; int r; mode_t u; pw = NULL; gr = NULL; /* Get user/group ID */ if (!no_drop_root) { if (!(pw = getpwnam(AVAHI_AUTOIPD_USER))) { daemon_log(LOG_ERR, "Failed to find user '"AVAHI_AUTOIPD_USER"'."); return -1; } if (!(gr = getgrnam(AVAHI_AUTOIPD_GROUP))) { daemon_log(LOG_ERR, "Failed to find group '"AVAHI_AUTOIPD_GROUP"'."); return -1; } daemon_log(LOG_INFO, "Found user '"AVAHI_AUTOIPD_USER"' (UID %lu) and group '"AVAHI_AUTOIPD_GROUP"' (GID %lu).", (unsigned long) pw->pw_uid, (unsigned long) gr->gr_gid); } /* Create directory */ u = umask(0000); r = mkdir(AVAHI_IPDATA_DIR, 0755); umask(u); if (r < 0 && errno != EEXIST) { daemon_log(LOG_ERR, "mkdir(\""AVAHI_IPDATA_DIR"\"): %s", strerror(errno)); return -1; } /* Convey working directory */ if (!no_drop_root) { struct stat st; chown(AVAHI_IPDATA_DIR, pw->pw_uid, gr->gr_gid); if (stat(AVAHI_IPDATA_DIR, &st) < 0) { daemon_log(LOG_ERR, "stat(): %s\n", strerror(errno)); return -1; } if (!S_ISDIR(st.st_mode) || st.st_uid != pw->pw_uid || st.st_gid != gr->gr_gid) { daemon_log(LOG_ERR, "Failed to create runtime directory "AVAHI_IPDATA_DIR"."); return -1; } } #ifdef HAVE_CHROOT if (!no_chroot) { if (chroot(AVAHI_IPDATA_DIR) < 0) { daemon_log(LOG_ERR, "Failed to chroot(): %s", strerror(errno)); return -1; } daemon_log(LOG_INFO, "Successfully called chroot()."); chdir("/"); /* Since we are now trapped inside a chroot we cannot remove * the pid file anymore, the helper process will do that for us. */ wrote_pid_file = 0; } #endif if (!no_drop_root) { if (initgroups(AVAHI_AUTOIPD_USER, gr->gr_gid) != 0) { daemon_log(LOG_ERR, "Failed to change group list: %s", strerror(errno)); return -1; } #if defined(HAVE_SETRESGID) r = setresgid(gr->gr_gid, gr->gr_gid, gr->gr_gid); #elif defined(HAVE_SETEGID) if ((r = setgid(gr->gr_gid)) >= 0) r = setegid(gr->gr_gid); #elif defined(HAVE_SETREGID) r = setregid(gr->gr_gid, gr->gr_gid); #else #error "No API to drop privileges" #endif if (r < 0) { daemon_log(LOG_ERR, "Failed to change GID: %s", strerror(errno)); return -1; } #if defined(HAVE_SETRESUID) r = setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid); #elif defined(HAVE_SETEUID) if ((r = setuid(pw->pw_uid)) >= 0) r = seteuid(pw->pw_uid); #elif defined(HAVE_SETREUID) r = setreuid(pw->pw_uid, pw->pw_uid); #else #error "No API to drop privileges" #endif if (r < 0) { daemon_log(LOG_ERR, "Failed to change UID: %s", strerror(errno)); return -1; } set_env("USER", pw->pw_name); set_env("LOGNAME", pw->pw_name); set_env("HOME", pw->pw_dir); daemon_log(LOG_INFO, "Successfully dropped root privileges."); } return 0; } static int loop(int iface, uint32_t addr) { enum { FD_ARP, FD_IFACE, FD_SIGNAL, FD_MAX }; int fd = -1, ret = -1; struct timeval next_wakeup; int next_wakeup_valid = 0; char buf[64]; ArpPacket *in_packet = NULL; size_t in_packet_len = 0; ArpPacket *out_packet = NULL; size_t out_packet_len; uint8_t hw_address[ETHER_ADDRLEN]; struct pollfd pollfds[FD_MAX]; int iface_fd = -1; Event event = EVENT_NULL; int retval_sent = !daemonize; State st; FILE *dispatcher = NULL; char *address_fn = NULL; const char *p; daemon_signal_init(SIGINT, SIGTERM, SIGCHLD, SIGHUP, 0); if (!(dispatcher = fork_dispatcher())) goto fail; if ((fd = open_socket(iface, hw_address)) < 0) goto fail; if ((iface_fd = iface_init(iface)) < 0) goto fail; if (drop_privs() < 0) goto fail; if (force_bind) st = STATE_START; else if (iface_get_initial_state(&st) < 0) goto fail; #ifdef HAVE_CHROOT if (!no_chroot) p = ""; else #endif p = AVAHI_IPDATA_DIR; address_fn = avahi_strdup_printf( "%s/%02x:%02x:%02x:%02x:%02x:%02x", p, hw_address[0], hw_address[1], hw_address[2], hw_address[3], hw_address[4], hw_address[5]); if (!addr) load_address(address_fn, &addr); if (addr && !is_ll_address(addr)) { daemon_log(LOG_WARNING, "Requested address %s is not from IPv4LL range 169.254/16 or a reserved address, ignoring.", inet_ntop(AF_INET, &addr, buf, sizeof(buf))); addr = 0; } if (!addr) { int i; uint32_t a = 1; for (i = 0; i < ETHER_ADDRLEN; i++) a += hw_address[i]*i; a = (a % 0xFE00) + 0x0100; addr = htonl(IPV4LL_NETWORK | (uint32_t) a); } assert(is_ll_address(addr)); set_state(st, 1, addr); daemon_log(LOG_INFO, "Starting with address %s", inet_ntop(AF_INET, &addr, buf, sizeof(buf))); if (state == STATE_SLEEPING) daemon_log(LOG_INFO, "Routable address already assigned, sleeping."); if (!retval_sent && (!wait_for_address || state == STATE_SLEEPING)) { daemon_retval_send(0); retval_sent = 1; } memset(pollfds, 0, sizeof(pollfds)); pollfds[FD_ARP].fd = fd; pollfds[FD_ARP].events = POLLIN; pollfds[FD_IFACE].fd = iface_fd; pollfds[FD_IFACE].events = POLLIN; pollfds[FD_SIGNAL].fd = daemon_signal_fd(); pollfds[FD_SIGNAL].events = POLLIN; for (;;) { int r, timeout; AvahiUsec usec; if (state == STATE_START) { /* First, wait a random time */ set_state(STATE_WAITING_PROBE, 1, addr); elapse_time(&next_wakeup, 0, PROBE_WAIT*1000); next_wakeup_valid = 1; } else if ((state == STATE_WAITING_PROBE && event == EVENT_TIMEOUT) || (state == STATE_PROBING && event == EVENT_TIMEOUT && n_iteration < PROBE_NUM-2)) { /* Send a probe */ out_packet = packet_new_probe(addr, hw_address, &out_packet_len); set_state(STATE_PROBING, 0, addr); elapse_time(&next_wakeup, PROBE_MIN*1000, (PROBE_MAX-PROBE_MIN)*1000); next_wakeup_valid = 1; } else if (state == STATE_PROBING && event == EVENT_TIMEOUT && n_iteration >= PROBE_NUM-2) { /* Send the last probe */ out_packet = packet_new_probe(addr, hw_address, &out_packet_len); set_state(STATE_WAITING_ANNOUNCE, 1, addr); elapse_time(&next_wakeup, ANNOUNCE_WAIT*1000, 0); next_wakeup_valid = 1; } else if ((state == STATE_WAITING_ANNOUNCE && event == EVENT_TIMEOUT) || (state == STATE_ANNOUNCING && event == EVENT_TIMEOUT && n_iteration < ANNOUNCE_NUM-1)) { /* Send announcement packet */ out_packet = packet_new_announcement(addr, hw_address, &out_packet_len); set_state(STATE_ANNOUNCING, 0, addr); elapse_time(&next_wakeup, ANNOUNCE_INTERVAL*1000, 0); next_wakeup_valid = 1; if (n_iteration == 0) { if (do_callout(dispatcher, CALLOUT_BIND, iface, addr) < 0) goto fail; n_conflict = 0; } } else if ((state == STATE_ANNOUNCING && event == EVENT_TIMEOUT && n_iteration >= ANNOUNCE_NUM-1)) { daemon_log(LOG_INFO, "Successfully claimed IP address %s", inet_ntop(AF_INET, &addr, buf, sizeof(buf))); set_state(STATE_RUNNING, 0, addr); next_wakeup_valid = 0; save_address(address_fn, addr); if (!retval_sent) { daemon_retval_send(0); retval_sent = 1; } } else if (event == EVENT_PACKET) { ArpPacketInfo info; assert(in_packet); if (packet_parse(in_packet, in_packet_len, &info) < 0) daemon_log(LOG_WARNING, "Failed to parse incoming ARP packet."); else { int conflict = 0; if (info.sender_ip_address == addr) { if (memcmp(hw_address, info.sender_hw_address, ETHER_ADDRLEN)) { /* Normal conflict */ conflict = 1; daemon_log(LOG_INFO, "Received conflicting normal ARP packet."); } else daemon_log(LOG_DEBUG, "Received ARP packet back on source interface. Ignoring."); } else if (state == STATE_WAITING_PROBE || state == STATE_PROBING || state == STATE_WAITING_ANNOUNCE) { /* Probe conflict */ conflict = info.target_ip_address == addr && memcmp(hw_address, info.sender_hw_address, ETHER_ADDRLEN); if (conflict) daemon_log(LOG_INFO, "Received conflicting probe ARP packet."); } if (conflict) { if (state == STATE_RUNNING || state == STATE_ANNOUNCING) if (do_callout(dispatcher, CALLOUT_CONFLICT, iface, addr) < 0) goto fail; /* Pick a new address */ addr = pick_addr(addr); daemon_log(LOG_INFO, "Trying address %s", inet_ntop(AF_INET, &addr, buf, sizeof(buf))); n_conflict++; set_state(STATE_WAITING_PROBE, 1, addr); if (n_conflict >= MAX_CONFLICTS) { daemon_log(LOG_WARNING, "Got too many conflicts, rate limiting new probes."); elapse_time(&next_wakeup, RATE_LIMIT_INTERVAL*1000, PROBE_WAIT*1000); } else elapse_time(&next_wakeup, 0, PROBE_WAIT*1000); next_wakeup_valid = 1; } else DEBUG(daemon_log(LOG_DEBUG, "Ignoring irrelevant ARP packet.")); } } else if (event == EVENT_ROUTABLE_ADDR_CONFIGURED && !force_bind) { daemon_log(LOG_INFO, "A routable address has been configured."); if (state == STATE_RUNNING || state == STATE_ANNOUNCING) if (do_callout(dispatcher, CALLOUT_UNBIND, iface, addr) < 0) goto fail; if (!retval_sent) { daemon_retval_send(0); retval_sent = 1; } set_state(STATE_SLEEPING, 1, addr); next_wakeup_valid = 0; } else if (event == EVENT_ROUTABLE_ADDR_UNCONFIGURED && state == STATE_SLEEPING && !force_bind) { daemon_log(LOG_INFO, "No longer a routable address configured, restarting probe process."); set_state(STATE_WAITING_PROBE, 1, addr); elapse_time(&next_wakeup, 0, PROBE_WAIT*1000); next_wakeup_valid = 1; } else if (event == EVENT_REFRESH_REQUEST && state == STATE_RUNNING) { /* The user requested a reannouncing of the address by a SIGHUP */ daemon_log(LOG_INFO, "Reannouncing address."); /* Send announcement packet */ out_packet = packet_new_announcement(addr, hw_address, &out_packet_len); set_state(STATE_ANNOUNCING, 1, addr); elapse_time(&next_wakeup, ANNOUNCE_INTERVAL*1000, 0); next_wakeup_valid = 1; } if (out_packet) { DEBUG(daemon_log(LOG_DEBUG, "sending...")); if (send_packet(fd, iface, out_packet, out_packet_len) < 0) goto fail; avahi_free(out_packet); out_packet = NULL; } if (in_packet) { avahi_free(in_packet); in_packet = NULL; } event = EVENT_NULL; timeout = -1; if (next_wakeup_valid) { usec = avahi_age(&next_wakeup); timeout = usec < 0 ? (int) (-usec/1000) : 0; } DEBUG(daemon_log(LOG_DEBUG, "sleeping %ims", timeout)); while ((r = poll(pollfds, FD_MAX, timeout)) < 0 && errno == EINTR) ; if (r < 0) { daemon_log(LOG_ERR, "poll() failed: %s", strerror(r)); goto fail; } else if (r == 0) { event = EVENT_TIMEOUT; next_wakeup_valid = 0; } else { if (pollfds[FD_ARP].revents) { if (pollfds[FD_ARP].revents == POLLERR) { /* The interface is probably down, let's recreate our socket */ close_socket(fd); if ((fd = open_socket(iface, hw_address)) < 0) goto fail; pollfds[FD_ARP].fd = fd; } else { assert(pollfds[FD_ARP].revents == POLLIN); if (recv_packet(fd, &in_packet, &in_packet_len) < 0) goto fail; if (in_packet) event = EVENT_PACKET; } } if (event == EVENT_NULL && pollfds[FD_IFACE].revents) { assert(pollfds[FD_IFACE].revents == POLLIN); if (iface_process(&event) < 0) goto fail; } if (event == EVENT_NULL && pollfds[FD_SIGNAL].revents) { int sig; assert(pollfds[FD_SIGNAL].revents == POLLIN); if ((sig = daemon_signal_next()) <= 0) { daemon_log(LOG_ERR, "daemon_signal_next() failed"); goto fail; } switch(sig) { case SIGINT: case SIGTERM: daemon_log(LOG_INFO, "Got %s, quitting.", sig == SIGINT ? "SIGINT" : "SIGTERM"); ret = 0; goto fail; case SIGCHLD: waitpid(-1, NULL, WNOHANG); break; case SIGHUP: event = EVENT_REFRESH_REQUEST; break; } } } } ret = 0; fail: if (state == STATE_RUNNING || state == STATE_ANNOUNCING) do_callout(dispatcher, CALLOUT_STOP, iface, addr); avahi_free(out_packet); avahi_free(in_packet); if (fd >= 0) close_socket(fd); if (iface_fd >= 0) iface_done(); if (daemonize && !retval_sent) daemon_retval_send(ret); if (dispatcher) fclose(dispatcher); if (address_fn) avahi_free(address_fn); return ret; } static void help(FILE *f, const char *a0) { fprintf(f, "%s [options] INTERFACE\n" " -h --help Show this help\n" " -D --daemonize Daemonize after startup\n" " -s --syslog Write log messages to syslog(3) instead of STDERR\n" " -k --kill Kill a running daemon\n" " -r --refresh Request a running daemon refresh its IP address\n" " -c --check Return 0 if a daemon is already running\n" " -V --version Show version\n" " -S --start=ADDRESS Start with this address from the IPv4LL range\n" " 169.254.0.0/16\n" " -t --script=script Action script to run (defaults to\n" " "AVAHI_IPCONF_SCRIPT")\n" " -w --wait Wait until an address has been acquired before\n" " daemonizing\n" " --force-bind Assign an IPv4LL address even if a routable address\n" " is already assigned\n" " --no-drop-root Don't drop privileges\n" #ifdef HAVE_CHROOT " --no-chroot Don't chroot()\n" #endif " --no-proc-title Don't modify process title\n" " --debug Increase verbosity\n", a0); } static int parse_command_line(int argc, char *argv[]) { int c; enum { OPTION_NO_PROC_TITLE = 256, OPTION_FORCE_BIND, OPTION_DEBUG, OPTION_NO_DROP_ROOT, #ifdef HAVE_CHROOT OPTION_NO_CHROOT #endif }; static const struct option long_options[] = { { "help", no_argument, NULL, 'h' }, { "daemonize", no_argument, NULL, 'D' }, { "syslog", no_argument, NULL, 's' }, { "kill", no_argument, NULL, 'k' }, { "refresh", no_argument, NULL, 'r' }, { "check", no_argument, NULL, 'c' }, { "version", no_argument, NULL, 'V' }, { "start", required_argument, NULL, 'S' }, { "script", required_argument, NULL, 't' }, { "wait", no_argument, NULL, 'w' }, { "force-bind", no_argument, NULL, OPTION_FORCE_BIND }, { "no-drop-root", no_argument, NULL, OPTION_NO_DROP_ROOT }, #ifdef HAVE_CHROOT { "no-chroot", no_argument, NULL, OPTION_NO_CHROOT }, #endif { "no-proc-title", no_argument, NULL, OPTION_NO_PROC_TITLE }, { "debug", no_argument, NULL, OPTION_DEBUG }, { NULL, 0, NULL, 0 } }; while ((c = getopt_long(argc, argv, "hDskrcVS:t:w", long_options, NULL)) >= 0) { switch(c) { case 's': use_syslog = 1; break; case 'h': command = DAEMON_HELP; break; case 'D': daemonize = 1; break; case 'k': command = DAEMON_KILL; break; case 'V': command = DAEMON_VERSION; break; case 'r': command = DAEMON_REFRESH; break; case 'c': command = DAEMON_CHECK; break; case 'S': if ((start_address = inet_addr(optarg)) == (uint32_t) -1) { fprintf(stderr, "Failed to parse IP address '%s'.", optarg); return -1; } break; case 't': avahi_free(action_script); action_script = avahi_strdup(optarg); break; case 'w': wait_for_address = 1; break; case OPTION_NO_PROC_TITLE: modify_proc_title = 0; break; case OPTION_DEBUG: debug = 1; break; case OPTION_FORCE_BIND: force_bind = 1; break; case OPTION_NO_DROP_ROOT: no_drop_root = 1; break; #ifdef HAVE_CHROOT case OPTION_NO_CHROOT: no_chroot = 1; break; #endif default: return -1; } } if (command == DAEMON_RUN || command == DAEMON_KILL || command == DAEMON_REFRESH || command == DAEMON_CHECK) { if (optind >= argc) { fprintf(stderr, "Missing interface name.\n"); return -1; } interface_name = avahi_strdup(argv[optind++]); } if (optind != argc) { fprintf(stderr, "Too many arguments\n"); return -1; } if (!action_script) action_script = avahi_strdup(AVAHI_IPCONF_SCRIPT); return 0; } static const char* pid_file_proc(void) { return pid_file_name; } int main(int argc, char*argv[]) { int r = 1; char *log_ident = NULL; signal(SIGPIPE, SIG_IGN); if ((argv0 = strrchr(argv[0], '/'))) argv0 = avahi_strdup(argv0 + 1); else argv0 = avahi_strdup(argv[0]); daemon_log_ident = argv0; if (parse_command_line(argc, argv) < 0) goto finish; if (modify_proc_title) avahi_init_proc_title(argc, argv); daemon_log_ident = log_ident = avahi_strdup_printf("%s(%s)", argv0, interface_name); daemon_pid_file_proc = pid_file_proc; pid_file_name = avahi_strdup_printf(AVAHI_RUNTIME_DIR"/avahi-autoipd.%s.pid", interface_name); if (command == DAEMON_RUN) { pid_t pid; int ifindex; init_rand_seed(); if ((ifindex = if_nametoindex(interface_name)) <= 0) { daemon_log(LOG_ERR, "Failed to get index for interface name '%s': %s", interface_name, strerror(errno)); goto finish; } if (getuid() != 0) { daemon_log(LOG_ERR, "This program is intended to be run as root."); goto finish; } if ((pid = daemon_pid_file_is_running()) >= 0) { daemon_log(LOG_ERR, "Daemon already running on PID %u", pid); goto finish; } if (daemonize) { daemon_retval_init(); if ((pid = daemon_fork()) < 0) goto finish; else if (pid != 0) { int ret; /** Parent **/ if ((ret = daemon_retval_wait(20)) < 0) { daemon_log(LOG_ERR, "Could not receive return value from daemon process."); goto finish; } r = ret; goto finish; } /* Child */ } if (use_syslog || daemonize) daemon_log_use = DAEMON_LOG_SYSLOG; chdir("/"); if (daemon_pid_file_create() < 0) { daemon_log(LOG_ERR, "Failed to create PID file: %s", strerror(errno)); if (daemonize) daemon_retval_send(1); goto finish; } else wrote_pid_file = 1; avahi_set_proc_title(argv0, "%s: [%s] starting up", argv0, interface_name); if (loop(ifindex, start_address) < 0) goto finish; r = 0; } else if (command == DAEMON_HELP) { help(stdout, argv0); r = 0; } else if (command == DAEMON_VERSION) { printf("%s "PACKAGE_VERSION"\n", argv0); r = 0; } else if (command == DAEMON_KILL) { if (daemon_pid_file_kill_wait(SIGTERM, 5) < 0) { daemon_log(LOG_WARNING, "Failed to kill daemon: %s", strerror(errno)); goto finish; } r = 0; } else if (command == DAEMON_REFRESH) { if (daemon_pid_file_kill(SIGHUP) < 0) { daemon_log(LOG_WARNING, "Failed to kill daemon: %s", strerror(errno)); goto finish; } r = 0; } else if (command == DAEMON_CHECK) r = (daemon_pid_file_is_running() >= 0) ? 0 : 1; finish: if (daemonize) daemon_retval_done(); if (wrote_pid_file) daemon_pid_file_remove(); avahi_free(log_ident); avahi_free(pid_file_name); avahi_free(argv0); avahi_free(interface_name); avahi_free(action_script); return r; }