/** * Copyright (C) 2012-2013 Steven Barth * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License v2 as published by * the Free Software Foundation. * * 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. * */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "odhcpd.h" static int ioctl_sock; static int urandom_fd = -1; static void sighandler(_unused int signal) { uloop_end(); } static void print_usage(const char *app) { printf( "== %s Usage ==\n\n" " -h, --help Print this help\n" " -l level Specify log level 0..7 (default %d)\n", app, config.log_level ); } static bool ipv6_enabled(void) { int fd = socket(AF_INET6, SOCK_DGRAM, 0); if (fd < 0) return false; close(fd); return true; } int main(int argc, char **argv) { openlog("odhcpd", LOG_PERROR | LOG_PID, LOG_DAEMON); int opt; while ((opt = getopt(argc, argv, "hl:")) != -1) { switch (opt) { case 'h': print_usage(argv[0]); return 0; case 'l': config.log_level = (atoi(optarg) & LOG_PRIMASK); fprintf(stderr, "Log level set to %d\n", config.log_level); break; } } setlogmask(LOG_UPTO(config.log_level)); uloop_init(); if (getuid() != 0) { syslog(LOG_ERR, "Must be run as root!"); return 2; } ioctl_sock = socket(AF_INET, SOCK_DGRAM | SOCK_CLOEXEC, 0); if (ioctl_sock < 0) return 4; if ((urandom_fd = open("/dev/urandom", O_RDONLY | O_CLOEXEC)) < 0) return 4; signal(SIGUSR1, SIG_IGN); signal(SIGINT, sighandler); signal(SIGTERM, sighandler); if (netlink_init()) return 4; if (ipv6_enabled()) { if (router_init()) return 4; if (dhcpv6_init()) return 4; if (ndp_init()) return 4; } #ifndef DHCPV4_SUPPORT else return 4; #else if (dhcpv4_init()) return 4; #endif odhcpd_run(); return 0; } /* Read IPv6 MTU for interface */ int odhcpd_get_interface_config(const char *ifname, const char *what) { char buf[64]; const char *sysctl_pattern = "/proc/sys/net/ipv6/conf/%s/%s"; snprintf(buf, sizeof(buf), sysctl_pattern, ifname, what); int fd = open(buf, O_RDONLY); if (fd < 0) return -1; ssize_t len = read(fd, buf, sizeof(buf) - 1); close(fd); if (len < 0) return -1; buf[len] = 0; return atoi(buf); } /* Read IPv6 MAC for interface */ int odhcpd_get_mac(const struct interface *iface, uint8_t mac[6]) { struct ifreq ifr; memset(&ifr, 0, sizeof(ifr)); strncpy(ifr.ifr_name, iface->ifname, sizeof(ifr.ifr_name) - 1); if (ioctl(ioctl_sock, SIOCGIFHWADDR, &ifr) < 0) return -1; memcpy(mac, ifr.ifr_hwaddr.sa_data, 6); return 0; } /* Forwards a packet on a specific interface */ ssize_t odhcpd_send(int socket, struct sockaddr_in6 *dest, struct iovec *iov, size_t iov_len, const struct interface *iface) { /* Construct headers */ uint8_t cmsg_buf[CMSG_SPACE(sizeof(struct in6_pktinfo))] = {0}; struct msghdr msg = { .msg_name = (void *) dest, .msg_namelen = sizeof(*dest), .msg_iov = iov, .msg_iovlen = iov_len, .msg_control = cmsg_buf, .msg_controllen = sizeof(cmsg_buf), .msg_flags = 0 }; /* Set control data (define destination interface) */ struct cmsghdr *chdr = CMSG_FIRSTHDR(&msg); chdr->cmsg_level = IPPROTO_IPV6; chdr->cmsg_type = IPV6_PKTINFO; chdr->cmsg_len = CMSG_LEN(sizeof(struct in6_pktinfo)); struct in6_pktinfo *pktinfo = (struct in6_pktinfo*)CMSG_DATA(chdr); pktinfo->ipi6_ifindex = iface->ifindex; /* Also set scope ID if link-local */ if (IN6_IS_ADDR_LINKLOCAL(&dest->sin6_addr) || IN6_IS_ADDR_MC_LINKLOCAL(&dest->sin6_addr)) dest->sin6_scope_id = iface->ifindex; char ipbuf[INET6_ADDRSTRLEN]; inet_ntop(AF_INET6, &dest->sin6_addr, ipbuf, sizeof(ipbuf)); ssize_t sent = sendmsg(socket, &msg, MSG_DONTWAIT); if (sent < 0) syslog(LOG_NOTICE, "Failed to send to %s%%%s@%s (%m)", ipbuf, iface->name, iface->ifname); else syslog(LOG_DEBUG, "Sent %zd bytes to %s%%%s@%s", sent, ipbuf, iface->name, iface->ifname); return sent; } static int odhcpd_get_linklocal_interface_address(int ifindex, struct in6_addr *lladdr) { int ret = -1; struct sockaddr_in6 addr; socklen_t alen = sizeof(addr); int sock = socket(AF_INET6, SOCK_RAW, IPPROTO_ICMPV6); if (sock < 0) return -1; memset(&addr, 0, sizeof(addr)); addr.sin6_family = AF_INET6; inet_pton(AF_INET6, ALL_IPV6_ROUTERS, &addr.sin6_addr); addr.sin6_scope_id = ifindex; if (!connect(sock, (struct sockaddr*)&addr, sizeof(addr)) && !getsockname(sock, (struct sockaddr*)&addr, &alen)) { *lladdr = addr.sin6_addr; ret = 0; } close(sock); return ret; } /* * DNS address selection criteria order : * - use IPv6 address with valid lifetime if none is yet selected * - use IPv6 address with a preferred lifetime if the already selected IPv6 address is deprecated * - use an IPv6 ULA address if the already selected IPv6 address is not an ULA address * - use the IPv6 address with the longest preferred lifetime */ int odhcpd_get_interface_dns_addr(const struct interface *iface, struct in6_addr *addr) { time_t now = odhcpd_time(); ssize_t m = -1; for (size_t i = 0; i < iface->addr6_len; ++i) { if (iface->addr6[i].valid <= (uint32_t)now) continue; if (m < 0) { m = i; continue; } if (iface->addr6[m].preferred >= (uint32_t)now && iface->addr6[i].preferred < (uint32_t)now) continue; if (IN6_IS_ADDR_ULA(&iface->addr6[i].addr.in6)) { if (!IN6_IS_ADDR_ULA(&iface->addr6[m].addr.in6)) { m = i; continue; } } else if (IN6_IS_ADDR_ULA(&iface->addr6[m].addr.in6)) continue; if (iface->addr6[i].preferred > iface->addr6[m].preferred) m = i; } if (m >= 0) { *addr = iface->addr6[m].addr.in6; return 0; } return odhcpd_get_linklocal_interface_address(iface->ifindex, addr); } struct interface* odhcpd_get_interface_by_index(int ifindex) { struct interface *iface; avl_for_each_element(&interfaces, iface, avl) { if (iface->ifindex == ifindex) return iface; } return NULL; } struct interface* odhcpd_get_interface_by_name(const char *name) { struct interface *iface; avl_for_each_element(&interfaces, iface, avl) { if (!strcmp(iface->ifname, name)) return iface; } return NULL; } struct interface* odhcpd_get_master_interface(void) { struct interface *iface; avl_for_each_element(&interfaces, iface, avl) { if (iface->master) return iface; } return NULL; } /* Convenience function to receive and do basic validation of packets */ static void odhcpd_receive_packets(struct uloop_fd *u, _unused unsigned int events) { struct odhcpd_event *e = container_of(u, struct odhcpd_event, uloop); uint8_t data_buf[8192], cmsg_buf[128]; union { struct sockaddr_in6 in6; struct sockaddr_in in; struct sockaddr_ll ll; struct sockaddr_nl nl; } addr; if (u->error) { int ret = -1; socklen_t ret_len = sizeof(ret); u->error = false; if (e->handle_error && getsockopt(u->fd, SOL_SOCKET, SO_ERROR, &ret, &ret_len) == 0) e->handle_error(e, ret); } if (e->recv_msgs) { e->recv_msgs(e); return; } while (true) { struct iovec iov = {data_buf, sizeof(data_buf)}; struct msghdr msg = { .msg_name = (void *) &addr, .msg_namelen = sizeof(addr), .msg_iov = &iov, .msg_iovlen = 1, .msg_control = cmsg_buf, .msg_controllen = sizeof(cmsg_buf), .msg_flags = 0 }; ssize_t len = recvmsg(u->fd, &msg, MSG_DONTWAIT); if (len < 0) { if (errno == EAGAIN) break; else continue; } /* Extract destination interface */ int destiface = 0; int *hlim = NULL; void *dest = NULL; struct in6_pktinfo *pktinfo; struct in_pktinfo *pkt4info; for (struct cmsghdr *ch = CMSG_FIRSTHDR(&msg); ch != NULL; ch = CMSG_NXTHDR(&msg, ch)) { if (ch->cmsg_level == IPPROTO_IPV6 && ch->cmsg_type == IPV6_PKTINFO) { pktinfo = (struct in6_pktinfo*)CMSG_DATA(ch); destiface = pktinfo->ipi6_ifindex; dest = &pktinfo->ipi6_addr; } else if (ch->cmsg_level == IPPROTO_IP && ch->cmsg_type == IP_PKTINFO) { pkt4info = (struct in_pktinfo*)CMSG_DATA(ch); destiface = pkt4info->ipi_ifindex; dest = &pkt4info->ipi_addr; } else if (ch->cmsg_level == IPPROTO_IPV6 && ch->cmsg_type == IPV6_HOPLIMIT) { hlim = (int*)CMSG_DATA(ch); } } /* Check hoplimit if received */ if (hlim && *hlim != 255) continue; /* Detect interface for packet sockets */ if (addr.ll.sll_family == AF_PACKET) destiface = addr.ll.sll_ifindex; char ipbuf[INET6_ADDRSTRLEN] = "kernel"; if (addr.ll.sll_family == AF_PACKET && len >= (ssize_t)sizeof(struct ip6_hdr)) inet_ntop(AF_INET6, &data_buf[8], ipbuf, sizeof(ipbuf)); else if (addr.in6.sin6_family == AF_INET6) inet_ntop(AF_INET6, &addr.in6.sin6_addr, ipbuf, sizeof(ipbuf)); else if (addr.in.sin_family == AF_INET) inet_ntop(AF_INET, &addr.in.sin_addr, ipbuf, sizeof(ipbuf)); /* From netlink */ if (addr.nl.nl_family == AF_NETLINK) { syslog(LOG_DEBUG, "Received %zd Bytes from %s%%netlink", len, ipbuf); e->handle_dgram(&addr, data_buf, len, NULL, dest); return; } else if (destiface != 0) { struct interface *iface; avl_for_each_element(&interfaces, iface, avl) { if (iface->ifindex != destiface) continue; syslog(LOG_DEBUG, "Received %zd Bytes from %s%%%s@%s", len, ipbuf, iface->name, iface->ifname); e->handle_dgram(&addr, data_buf, len, iface, dest); } } } } /* Register events for the multiplexer */ int odhcpd_register(struct odhcpd_event *event) { event->uloop.cb = odhcpd_receive_packets; return uloop_fd_add(&event->uloop, ULOOP_READ | ((event->handle_error) ? ULOOP_ERROR_CB : 0)); } int odhcpd_deregister(struct odhcpd_event *event) { event->uloop.cb = NULL; return uloop_fd_delete(&event->uloop); } void odhcpd_process(struct odhcpd_event *event) { odhcpd_receive_packets(&event->uloop, 0); } int odhcpd_urandom(void *data, size_t len) { return read(urandom_fd, data, len); } time_t odhcpd_time(void) { struct timespec ts; syscall(SYS_clock_gettime, CLOCK_MONOTONIC, &ts); return ts.tv_sec; } static const char hexdigits[] = "0123456789abcdef"; static const int8_t hexvals[] = { -1, -1, -1, -1, -1, -1, -1, -1, -1, -2, -2, -1, -1, -2, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -2, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, -1, -1, -1, -1, -1, -1, -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, }; ssize_t odhcpd_unhexlify(uint8_t *dst, size_t len, const char *src) { size_t c; for (c = 0; c < len && src[0] && src[1]; ++c) { int8_t x = (int8_t)*src++; int8_t y = (int8_t)*src++; if (x < 0 || (x = hexvals[x]) < 0 || y < 0 || (y = hexvals[y]) < 0) return -1; dst[c] = x << 4 | y; while (((int8_t)*src) < 0 || (*src && hexvals[(uint8_t)*src] < 0)) src++; } return c; } void odhcpd_hexlify(char *dst, const uint8_t *src, size_t len) { for (size_t i = 0; i < len; ++i) { *dst++ = hexdigits[src[i] >> 4]; *dst++ = hexdigits[src[i] & 0x0f]; } *dst = 0; } const char *odhcpd_print_mac(const uint8_t *mac, const size_t len) { static char buf[32]; snprintf(buf, sizeof(buf), "%02x", mac[0]); for (size_t i = 1, j = 2; i < len && j < sizeof(buf); i++, j += 3) snprintf(buf + j, sizeof(buf) - j, ":%02x", mac[i]); return buf; } int odhcpd_bmemcmp(const void *av, const void *bv, size_t bits) { const uint8_t *a = av, *b = bv; size_t bytes = bits / 8; bits %= 8; int res = memcmp(a, b, bytes); if (res == 0 && bits > 0) res = (a[bytes] >> (8 - bits)) - (b[bytes] >> (8 - bits)); return res; } void odhcpd_bmemcpy(void *av, const void *bv, size_t bits) { uint8_t *a = av; const uint8_t *b = bv; size_t bytes = bits / 8; bits %= 8; memcpy(a, b, bytes); if (bits > 0) { uint8_t mask = (1 << (8 - bits)) - 1; a[bytes] = (a[bytes] & mask) | ((~mask) & b[bytes]); } } int odhcpd_netmask2bitlen(bool inet6, void *mask) { int bits; struct in_addr *v4; struct in6_addr *v6; if (inet6) for (bits = 0, v6 = mask; bits < 128 && (v6->s6_addr[bits / 8] << (bits % 8)) & 128; bits++); else for (bits = 0, v4 = mask; bits < 32 && (ntohl(v4->s_addr) << bits) & 0x80000000; bits++); return bits; } bool odhcpd_bitlen2netmask(bool inet6, unsigned int bits, void *mask) { uint8_t b; struct in_addr *v4; struct in6_addr *v6; if (inet6) { if (bits > 128) return false; v6 = mask; for (unsigned int i = 0; i < sizeof(v6->s6_addr); i++) { b = (bits > 8) ? 8 : bits; v6->s6_addr[i] = (uint8_t)(0xFF << (8 - b)); bits -= b; } } else { if (bits > 32) return false; v4 = mask; v4->s_addr = bits ? htonl(~((1 << (32 - bits)) - 1)) : 0; } return true; } bool odhcpd_valid_hostname(const char *name) { #define MAX_LABEL 63 const char *c, *label, *label_end; int label_sz = 0; for (c = name, label_sz = 0, label = name, label_end = name + strcspn(name, ".") - 1; *c && label_sz <= MAX_LABEL; c++) { if ((*c >= '0' && *c <= '9') || (*c >= 'A' && *c <= 'Z') || (*c >= 'a' && *c <= 'z')) { label_sz++; continue; } if ((*c == '_' || *c == '-') && c != label && c != label_end) { label_sz++; continue; } if (*c == '.') { if (*(c + 1)) { label = c + 1; label_end = label + strcspn(label, ".") - 1; label_sz = 0; } continue; } return false; } return (label_sz && label_sz <= MAX_LABEL ? true : false); }