/** * Copyright (C) 2012-2013 Steven Barth * Copyright (C) 2016 Hans Dedecker * * 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 "odhcpd.h" #include "dhcpv4.h" #include "dhcpv6.h" #define PACKET_SIZE(start, end) (((uint8_t *)end - (uint8_t *)start) < DHCPV4_MIN_PACKET_SIZE ? \ DHCPV4_MIN_PACKET_SIZE : (uint8_t *)end - (uint8_t *)start) static void dhcpv4_netevent_cb(unsigned long event, struct netevent_handler_info *info); static int setup_dhcpv4_addresses(struct interface *iface); static bool addr_is_fr_ip(struct interface *iface, struct in_addr *addr); static void valid_until_cb(struct uloop_timeout *event); static void handle_addrlist_change(struct interface *iface); static void dhcpv4_fr_start(struct dhcp_assignment *a); static void dhcpv4_fr_rand_delay(struct dhcp_assignment *a); static void dhcpv4_fr_stop(struct dhcp_assignment *a); static void handle_dhcpv4(void *addr, void *data, size_t len, struct interface *iface, void *dest_addr); static struct dhcp_assignment* dhcpv4_lease(struct interface *iface, enum dhcpv4_msg msg, const uint8_t *mac, const uint32_t reqaddr, uint32_t *leasetime, const char *hostname, const size_t hostname_len, const bool accept_fr_nonce, bool *incl_fr_opt, uint32_t *fr_serverid, const char *reqopts, const size_t reqopts_len); static struct netevent_handler dhcpv4_netevent_handler = { .cb = dhcpv4_netevent_cb, }; static struct uloop_timeout valid_until_timeout = {.cb = valid_until_cb}; static uint32_t serial = 0; struct odhcpd_ref_ip { struct list_head head; int ref_cnt; struct odhcpd_ipaddr addr; }; /* Create socket and register events */ int dhcpv4_init(void) { uloop_timeout_set(&valid_until_timeout, 1000); netlink_add_netevent_handler(&dhcpv4_netevent_handler); return 0; } int dhcpv4_setup_interface(struct interface *iface, bool enable) { int ret = 0; enable = enable && (iface->dhcpv4 != MODE_DISABLED); if (iface->dhcpv4_event.uloop.fd >= 0) { uloop_fd_delete(&iface->dhcpv4_event.uloop); close(iface->dhcpv4_event.uloop.fd); iface->dhcpv4_event.uloop.fd = -1; } if (enable) { struct sockaddr_in bind_addr = {AF_INET, htons(DHCPV4_SERVER_PORT), {INADDR_ANY}, {0}}; int val = 1; iface->dhcpv4_event.uloop.fd = socket(AF_INET, SOCK_DGRAM | SOCK_CLOEXEC, IPPROTO_UDP); if (iface->dhcpv4_event.uloop.fd < 0) { syslog(LOG_ERR, "socket(AF_INET): %m"); ret = -1; goto out; } /* Basic IPv4 configuration */ if (setsockopt(iface->dhcpv4_event.uloop.fd, SOL_SOCKET, SO_REUSEADDR, &val, sizeof(val)) < 0) { syslog(LOG_ERR, "setsockopt(SO_REUSEADDR): %m"); ret = -1; goto out; } if (setsockopt(iface->dhcpv4_event.uloop.fd, SOL_SOCKET, SO_BROADCAST, &val, sizeof(val)) < 0) { syslog(LOG_ERR, "setsockopt(SO_BROADCAST): %m"); ret = -1; goto out; } if (setsockopt(iface->dhcpv4_event.uloop.fd, IPPROTO_IP, IP_PKTINFO, &val, sizeof(val)) < 0) { syslog(LOG_ERR, "setsockopt(IP_PKTINFO): %m"); ret = -1; goto out; } val = IPTOS_PREC_INTERNETCONTROL; if (setsockopt(iface->dhcpv4_event.uloop.fd, IPPROTO_IP, IP_TOS, &val, sizeof(val)) < 0) { syslog(LOG_ERR, "setsockopt(IP_TOS): %m"); ret = -1; goto out; } val = IP_PMTUDISC_DONT; if (setsockopt(iface->dhcpv4_event.uloop.fd, IPPROTO_IP, IP_MTU_DISCOVER, &val, sizeof(val)) < 0) { syslog(LOG_ERR, "setsockopt(IP_MTU_DISCOVER): %m"); ret = -1; goto out; } if (setsockopt(iface->dhcpv4_event.uloop.fd, SOL_SOCKET, SO_BINDTODEVICE, iface->ifname, strlen(iface->ifname)) < 0) { syslog(LOG_ERR, "setsockopt(SO_BINDTODEVICE): %m"); ret = -1; goto out; } if (bind(iface->dhcpv4_event.uloop.fd, (struct sockaddr*)&bind_addr, sizeof(bind_addr)) < 0) { syslog(LOG_ERR, "bind(): %m"); ret = -1; goto out; } if (setup_dhcpv4_addresses(iface) < 0) { ret = -1; goto out; } iface->dhcpv4_event.handle_dgram = handle_dhcpv4; odhcpd_register(&iface->dhcpv4_event); } else { while (!list_empty(&iface->dhcpv4_assignments)) free_assignment(list_first_entry(&iface->dhcpv4_assignments, struct dhcp_assignment, head)); } out: if (ret < 0 && iface->dhcpv4_event.uloop.fd >= 0) { close(iface->dhcpv4_event.uloop.fd); iface->dhcpv4_event.uloop.fd = -1; } return ret; } static void dhcpv4_netevent_cb(unsigned long event, struct netevent_handler_info *info) { struct interface *iface = info->iface; if (!iface || iface->dhcpv4 == MODE_DISABLED) return; switch (event) { case NETEV_IFINDEX_CHANGE: dhcpv4_setup_interface(iface, true); break; case NETEV_ADDRLIST_CHANGE: handle_addrlist_change(iface); break; default: break; } } static struct dhcp_assignment *find_assignment_by_hwaddr(struct interface *iface, const uint8_t *hwaddr) { struct dhcp_assignment *a; list_for_each_entry(a, &iface->dhcpv4_assignments, head) if (!memcmp(a->hwaddr, hwaddr, 6)) return a; return NULL; } static int setup_dhcpv4_addresses(struct interface *iface) { iface->dhcpv4_start_ip.s_addr = INADDR_ANY; iface->dhcpv4_end_ip.s_addr = INADDR_ANY; iface->dhcpv4_local.s_addr = INADDR_ANY; iface->dhcpv4_bcast.s_addr = INADDR_ANY; iface->dhcpv4_mask.s_addr = INADDR_ANY; /* Sanity checks */ if (iface->dhcpv4_start.s_addr & htonl(0xffff0000) || iface->dhcpv4_end.s_addr & htonl(0xffff0000) || ntohl(iface->dhcpv4_start.s_addr) > ntohl(iface->dhcpv4_end.s_addr)) { syslog(LOG_WARNING, "Invalid DHCP range for %s", iface->name); return -1; } if (!iface->addr4_len) { syslog(LOG_WARNING, "No network(s) available on %s", iface->name); return -1; } uint32_t start = ntohl(iface->dhcpv4_start.s_addr); uint32_t end = ntohl(iface->dhcpv4_end.s_addr); for (size_t i = 0; i < iface->addr4_len && start && end; i++) { struct in_addr *addr = &iface->addr4[i].addr.in; struct in_addr mask; if (addr_is_fr_ip(iface, addr)) continue; odhcpd_bitlen2netmask(false, iface->addr4[i].prefix, &mask); if ((start & ntohl(~mask.s_addr)) == start && (end & ntohl(~mask.s_addr)) == end && end < ntohl(~mask.s_addr)) { /* Exclude broadcast address */ iface->dhcpv4_start_ip.s_addr = htonl(start) | (addr->s_addr & mask.s_addr); iface->dhcpv4_end_ip.s_addr = htonl(end) | (addr->s_addr & mask.s_addr); iface->dhcpv4_local = *addr; iface->dhcpv4_bcast = iface->addr4[i].broadcast; iface->dhcpv4_mask = mask; return 0; } } /* Don't allocate IP range for subnets bigger than 28 */ if (iface->addr4[0].prefix > 28) { syslog(LOG_WARNING, "Auto allocation of DHCP range fails on %s", iface->name); return -1; } iface->dhcpv4_local = iface->addr4[0].addr.in; iface->dhcpv4_bcast = iface->addr4[0].broadcast; odhcpd_bitlen2netmask(false, iface->addr4[0].prefix, &iface->dhcpv4_mask); end = start = iface->dhcpv4_local.s_addr & iface->dhcpv4_mask.s_addr; /* Auto allocate ranges */ if (ntohl(iface->dhcpv4_mask.s_addr) <= 0xffffff00) { /* /24, 150 of 256, [100..249] */ iface->dhcpv4_start_ip.s_addr = start | htonl(100); iface->dhcpv4_end_ip.s_addr = end | htonl(100 + 150 - 1); } else if (ntohl(iface->dhcpv4_mask.s_addr) <= 0xffffff80) { /* /25, 100 of 128, [20..119] */ iface->dhcpv4_start_ip.s_addr = start | htonl(20); iface->dhcpv4_end_ip.s_addr = end | htonl(20 + 100 - 1); } else if (ntohl(iface->dhcpv4_mask.s_addr) <= 0xffffffc0) { /* /26, 50 of 64, [10..59] */ iface->dhcpv4_start_ip.s_addr = start | htonl(10); iface->dhcpv4_end_ip.s_addr = end | htonl(10 + 50 - 1); } else if (ntohl(iface->dhcpv4_mask.s_addr) <= 0xffffffe0) { /* /27, 20 of 32, [10..29] */ iface->dhcpv4_start_ip.s_addr = start | htonl(10); iface->dhcpv4_end_ip.s_addr = end | htonl(10 + 20 - 1); } else { /* /28, 10 of 16, [3..12] */ iface->dhcpv4_start_ip.s_addr = start | htonl(3); iface->dhcpv4_end_ip.s_addr = end | htonl(3 + 10 - 1); } return 0; } static void inc_ref_cnt_ip(struct odhcpd_ref_ip **ptr, struct odhcpd_ref_ip *ip) { *ptr = ip; ip->ref_cnt++; } static void decr_ref_cnt_ip(struct odhcpd_ref_ip **ptr, struct interface *iface) { struct odhcpd_ref_ip *ip = *ptr; if (--ip->ref_cnt == 0) { netlink_setup_addr(&ip->addr, iface->ifindex, false, false); list_del(&ip->head); free(ip); } *ptr = NULL; } static bool addr_is_fr_ip(struct interface *iface, struct in_addr *addr) { struct odhcpd_ref_ip *p; list_for_each_entry(p, &iface->dhcpv4_fr_ips, head) { if (addr->s_addr == p->addr.addr.in.s_addr) return true; } return false; } static bool leases_require_fr(struct interface *iface, struct odhcpd_ipaddr *addr, uint32_t mask) { struct dhcp_assignment *a = NULL; struct odhcpd_ref_ip *fr_ip = NULL; list_for_each_entry(a, &iface->dhcpv4_assignments, head) { if ((a->accept_fr_nonce || iface->dhcpv4_forcereconf) && !a->fr_ip && ((a->addr & mask) == (addr->addr.in.s_addr & mask))) { if (!fr_ip) { fr_ip = calloc(1, sizeof(*fr_ip)); if (!fr_ip) break; list_add(&fr_ip->head, &iface->dhcpv4_fr_ips); fr_ip->addr = *addr; } inc_ref_cnt_ip(&a->fr_ip, fr_ip); } } return fr_ip ? true : false; } static void valid_until_cb(struct uloop_timeout *event) { struct interface *iface; time_t now = odhcpd_time(); avl_for_each_element(&interfaces, iface, avl) { struct dhcp_assignment *a, *n; if (iface->dhcpv4 != MODE_SERVER) continue; list_for_each_entry_safe(a, n, &iface->dhcpv4_assignments, head) { if (!INFINITE_VALID(a->valid_until) && a->valid_until < now) free_assignment(a); } } uloop_timeout_set(event, 1000); } static void handle_addrlist_change(struct interface *iface) { struct odhcpd_ipaddr ip; struct odhcpd_ref_ip *a; struct dhcp_assignment *c; uint32_t mask = iface->dhcpv4_mask.s_addr; memset(&ip, 0, sizeof(ip)); ip.addr.in = iface->dhcpv4_local; ip.prefix = odhcpd_netmask2bitlen(false, &iface->dhcpv4_mask); ip.broadcast = iface->dhcpv4_bcast; setup_dhcpv4_addresses(iface); if ((ip.addr.in.s_addr & mask) == (iface->dhcpv4_local.s_addr & iface->dhcpv4_mask.s_addr)) return; if (ip.addr.in.s_addr && !leases_require_fr(iface, &ip, mask)) return; if (iface->dhcpv4_local.s_addr == INADDR_ANY || list_empty(&iface->dhcpv4_fr_ips)) return; a = list_first_entry(&iface->dhcpv4_fr_ips, struct odhcpd_ref_ip, head); if (netlink_setup_addr(&a->addr, iface->ifindex, false, true)) { syslog(LOG_WARNING, "Failed to add ip address on %s", iface->name); return; } list_for_each_entry(c, &iface->dhcpv4_assignments, head) { if ((c->flags & OAF_BOUND) && c->fr_ip && !c->fr_cnt) { if (c->accept_fr_nonce || iface->dhcpv4_forcereconf) dhcpv4_fr_rand_delay(c); else dhcpv4_fr_stop(c); } } } static char *dhcpv4_msg_to_string(uint8_t reqmsg) { switch (reqmsg) { case (DHCPV4_MSG_DISCOVER): return "DHCPV4_MSG_DISCOVER"; case (DHCPV4_MSG_OFFER): return "DHCPV4_MSG_OFFER"; case (DHCPV4_MSG_REQUEST): return "DHCPV4_MSG_REQUEST"; case (DHCPV4_MSG_DECLINE): return "DHCPV4_MSG_DECLINE"; case (DHCPV4_MSG_ACK): return "DHCPV4_MSG_ACK"; case (DHCPV4_MSG_NAK): return "DHCPV4_MSG_NAK"; case (DHCPV4_MSG_RELEASE): return "DHCPV4_MSG_RELEASE"; case (DHCPV4_MSG_INFORM): return "DHCPV4_MSG_INFORM"; case (DHCPV4_MSG_FORCERENEW): return "DHCPV4_MSG_FORCERENEW"; default: return "UNKNOWN"; } } static void dhcpv4_free_assignment(struct dhcp_assignment *a) { if (a->fr_ip) dhcpv4_fr_stop(a); } static void dhcpv4_put(struct dhcpv4_message *msg, uint8_t **cookie, uint8_t type, uint8_t len, const void *data) { uint8_t *c = *cookie; uint8_t *end = (uint8_t *)msg + sizeof(*msg); bool tag_only = type == DHCPV4_OPT_PAD || type == DHCPV4_OPT_END; int total_len = tag_only ? 1 : 2 + len; if (*cookie + total_len > end) return; *cookie += total_len; *c++ = type; if (tag_only) return; *c++ = len; memcpy(c, data, len); } static void dhcpv4_fr_send(struct dhcp_assignment *a) { struct dhcpv4_message fr_msg = { .op = DHCPV4_BOOTREPLY, .htype = 1, .hlen = 6, .hops = 0, .secs = 0, .flags = 0, .ciaddr = {INADDR_ANY}, .yiaddr = {INADDR_ANY}, .siaddr = {INADDR_ANY}, .giaddr = {INADDR_ANY}, .chaddr = {0}, .sname = {0}, .file = {0}, }; struct dhcpv4_auth_forcerenew *auth_o, auth = { .protocol = 3, .algorithm = 1, .rdm = 0, .replay = {htonl(time(NULL)), htonl(++serial)}, .type = 2, .key = {0}, }; struct interface *iface = a->iface; odhcpd_urandom(&fr_msg.xid, sizeof(fr_msg.xid)); memcpy(fr_msg.chaddr, a->hwaddr, fr_msg.hlen); fr_msg.options[0] = 0x63; fr_msg.options[1] = 0x82; fr_msg.options[2] = 0x53; fr_msg.options[3] = 0x63; uint8_t *cookie = &fr_msg.options[4]; uint8_t msg = DHCPV4_MSG_FORCERENEW; dhcpv4_put(&fr_msg, &cookie, DHCPV4_OPT_MESSAGE, 1, &msg); if (a->accept_fr_nonce) { dhcpv4_put(&fr_msg, &cookie, DHCPV4_OPT_AUTHENTICATION, sizeof(auth), &auth); auth_o = (struct dhcpv4_auth_forcerenew *)(cookie - sizeof(auth)); dhcpv4_put(&fr_msg, &cookie, DHCPV4_OPT_END, 0, NULL); md5_ctx_t md5; uint8_t secretbytes[64]; memset(secretbytes, 0, sizeof(secretbytes)); memcpy(secretbytes, a->key, sizeof(a->key)); for (size_t i = 0; i < sizeof(secretbytes); ++i) secretbytes[i] ^= 0x36; md5_begin(&md5); md5_hash(secretbytes, sizeof(secretbytes), &md5); md5_hash(&fr_msg, sizeof(fr_msg), &md5); md5_end(auth_o->key, &md5); for (size_t i = 0; i < sizeof(secretbytes); ++i) { secretbytes[i] ^= 0x36; secretbytes[i] ^= 0x5c; } md5_begin(&md5); md5_hash(secretbytes, sizeof(secretbytes), &md5); md5_hash(auth_o->key, sizeof(auth_o->key), &md5); md5_end(auth_o->key, &md5); } else { dhcpv4_put(&fr_msg, &cookie, DHCPV4_OPT_SERVERID, 4, &a->fr_ip->addr.addr.in.s_addr); dhcpv4_put(&fr_msg, &cookie, DHCPV4_OPT_END, 0, NULL); } struct sockaddr_in dest; memset(&dest, 0, sizeof(dest)); dest.sin_family = AF_INET; dest.sin_port = htons(DHCPV4_CLIENT_PORT); dest.sin_addr.s_addr = a->addr; if (sendto(iface->dhcpv4_event.uloop.fd, &fr_msg, PACKET_SIZE(&fr_msg, cookie), MSG_DONTWAIT, (struct sockaddr*)&dest, sizeof(dest)) < 0) syslog(LOG_ERR, "Failed to send %s to %s - %s: %m", dhcpv4_msg_to_string(msg), odhcpd_print_mac(a->hwaddr, sizeof(a->hwaddr)), inet_ntoa(dest.sin_addr)); else syslog(LOG_DEBUG, "Sent %s to %s - %s", dhcpv4_msg_to_string(msg), odhcpd_print_mac(a->hwaddr, sizeof(a->hwaddr)), inet_ntoa(dest.sin_addr)); } static void dhcpv4_fr_timer(struct uloop_timeout *event) { struct dhcp_assignment *a = container_of(event, struct dhcp_assignment, fr_timer); if (a->fr_cnt > 0 && a->fr_cnt < 8) { dhcpv4_fr_send(a); uloop_timeout_set(&a->fr_timer, 1000 << a->fr_cnt); a->fr_cnt++; } else dhcpv4_fr_stop(a); } static void dhcpv4_fr_start(struct dhcp_assignment *a) { uloop_timeout_set(&a->fr_timer, 1000 << a->fr_cnt); a->fr_timer.cb = dhcpv4_fr_timer; a->fr_cnt++; dhcpv4_fr_send(a); } static void dhcpv4_fr_delay_timer(struct uloop_timeout *event) { struct dhcp_assignment *a = container_of(event, struct dhcp_assignment, fr_timer); struct interface *iface = a->iface; (iface->dhcpv4_event.uloop.fd == -1 ? dhcpv4_fr_rand_delay(a) : dhcpv4_fr_start(a)); } static void dhcpv4_fr_rand_delay(struct dhcp_assignment *a) { #define MIN_DELAY 500 #define MAX_FUZZ 500 int msecs; odhcpd_urandom(&msecs, sizeof(msecs)); msecs = labs(msecs)%MAX_FUZZ + MIN_DELAY; uloop_timeout_set(&a->fr_timer, msecs); a->fr_timer.cb = dhcpv4_fr_delay_timer; } static void dhcpv4_fr_stop(struct dhcp_assignment *a) { uloop_timeout_cancel(&a->fr_timer); decr_ref_cnt_ip(&a->fr_ip, a->iface); a->fr_cnt = 0; a->fr_timer.cb = NULL; } static int dhcpv4_send_reply(const void *buf, size_t len, const struct sockaddr *dest, socklen_t dest_len, void *opaque) { int *sock = opaque; return sendto(*sock, buf, len, MSG_DONTWAIT, dest, dest_len); } /* Handler for DHCPv4 messages */ static void handle_dhcpv4(void *addr, void *data, size_t len, struct interface *iface, _unused void *dest_addr) { int sock = iface->dhcpv4_event.uloop.fd; dhcpv4_handle_msg(addr, data, len, iface, dest_addr, dhcpv4_send_reply, &sock); } void dhcpv4_handle_msg(void *addr, void *data, size_t len, struct interface *iface, _unused void *dest_addr, send_reply_cb_t send_reply, void *opaque) { struct dhcpv4_message *req = data; if (iface->dhcpv4 == MODE_DISABLED) return; if (len < offsetof(struct dhcpv4_message, options) + 4 || req->op != DHCPV4_BOOTREQUEST || req->hlen != 6) return; syslog(LOG_DEBUG, "Got DHCPv4 request on %s", iface->name); if (!iface->dhcpv4_start_ip.s_addr && !iface->dhcpv4_end_ip.s_addr) { syslog(LOG_WARNING, "No DHCP range available on %s", iface->name); return; } int sock = iface->dhcpv4_event.uloop.fd; struct dhcpv4_message reply = { .op = DHCPV4_BOOTREPLY, .htype = req->htype, .hlen = req->hlen, .hops = 0, .xid = req->xid, .secs = 0, .flags = req->flags, .ciaddr = {INADDR_ANY}, .giaddr = req->giaddr, .siaddr = iface->dhcpv4_local, }; memcpy(reply.chaddr, req->chaddr, sizeof(reply.chaddr)); reply.options[0] = 0x63; reply.options[1] = 0x82; reply.options[2] = 0x53; reply.options[3] = 0x63; uint8_t *cookie = &reply.options[4]; uint8_t reqmsg = DHCPV4_MSG_REQUEST; uint8_t msg = DHCPV4_MSG_ACK; uint32_t reqaddr = INADDR_ANY; uint32_t leasetime = 0; size_t hostname_len = 0; size_t reqopts_len = 0; char hostname[256]; char reqopts[256]; bool accept_fr_nonce = false; bool incl_fr_opt = false; uint8_t *start = &req->options[4]; uint8_t *end = ((uint8_t*)data) + len; struct dhcpv4_option *opt; dhcpv4_for_each_option(start, end, opt) { if (opt->type == DHCPV4_OPT_MESSAGE && opt->len == 1) reqmsg = opt->data[0]; else if (opt->type == DHCPV4_OPT_REQOPTS && opt->len > 0) { reqopts_len = opt->len; memcpy(reqopts, opt->data, reqopts_len); reqopts[reqopts_len] = 0; } else if (opt->type == DHCPV4_OPT_HOSTNAME && opt->len > 0) { hostname_len = opt->len; memcpy(hostname, opt->data, hostname_len); hostname[hostname_len] = 0; } else if (opt->type == DHCPV4_OPT_IPADDRESS && opt->len == 4) memcpy(&reqaddr, opt->data, 4); else if (opt->type == DHCPV4_OPT_SERVERID && opt->len == 4) { if (memcmp(opt->data, &iface->dhcpv4_local, 4)) return; } else if (iface->filter_class && opt->type == DHCPV4_OPT_USER_CLASS) { uint8_t *c = opt->data, *cend = &opt->data[opt->len]; for (; c < cend && &c[*c] < cend; c = &c[1 + *c]) { size_t elen = strlen(iface->filter_class); if (*c == elen && !memcmp(&c[1], iface->filter_class, elen)) return; // Ignore from homenet } } else if (opt->type == DHCPV4_OPT_LEASETIME && opt->len == 4) memcpy(&leasetime, opt->data, 4); else if (opt->type == DHCPV4_OPT_FORCERENEW_NONCE_CAPABLE && opt->len > 0) { for (uint8_t i = 0; i < opt->len; i++) { if (opt->data[i] == 1) { accept_fr_nonce = true; break; } } } } if (reqmsg != DHCPV4_MSG_DISCOVER && reqmsg != DHCPV4_MSG_REQUEST && reqmsg != DHCPV4_MSG_INFORM && reqmsg != DHCPV4_MSG_DECLINE && reqmsg != DHCPV4_MSG_RELEASE) return; struct dhcp_assignment *a = NULL; uint32_t serverid = iface->dhcpv4_local.s_addr; uint32_t fr_serverid = INADDR_ANY; if (reqmsg != DHCPV4_MSG_INFORM) a = dhcpv4_lease(iface, reqmsg, req->chaddr, reqaddr, &leasetime, hostname, hostname_len, accept_fr_nonce, &incl_fr_opt, &fr_serverid, reqopts, reqopts_len); if (!a) { if (reqmsg == DHCPV4_MSG_REQUEST) msg = DHCPV4_MSG_NAK; else if (reqmsg == DHCPV4_MSG_DISCOVER) return; } else if (reqmsg == DHCPV4_MSG_DISCOVER) msg = DHCPV4_MSG_OFFER; else if (reqmsg == DHCPV4_MSG_REQUEST && ((reqaddr && reqaddr != a->addr) || (req->ciaddr.s_addr && req->ciaddr.s_addr != a->addr))) { msg = DHCPV4_MSG_NAK; /* * DHCP client requested an IP which we can't offer to him. Probably the * client changed the network or the network has been changed. The reply * type is set to DHCPV4_MSG_NAK, because the client should not use that IP. * * For modern devices we build an answer that includes a valid IP, like * a DHCPV4_MSG_ACK. The client will use that IP and doesn't need to * perform additional DHCP round trips. * */ /* * * Buggy clients do serverid checking in nack messages; therefore set the * serverid in nack messages triggered by a previous force renew equal to * the server id in use at that time by the server * */ if (fr_serverid) serverid = fr_serverid; if (req->ciaddr.s_addr && ((iface->dhcpv4_start_ip.s_addr & iface->dhcpv4_mask.s_addr) != (req->ciaddr.s_addr & iface->dhcpv4_mask.s_addr))) req->ciaddr.s_addr = INADDR_ANY; } syslog(LOG_INFO, "Received %s from %s on %s", dhcpv4_msg_to_string(reqmsg), odhcpd_print_mac(req->chaddr, req->hlen), iface->name); #ifdef WITH_UBUS if (reqmsg == DHCPV4_MSG_RELEASE) ubus_bcast_dhcp_event("dhcp.release", req->chaddr, req->hlen, &req->ciaddr, a ? a->hostname : NULL, iface->ifname); #endif if (reqmsg == DHCPV4_MSG_DECLINE || reqmsg == DHCPV4_MSG_RELEASE) return; dhcpv4_put(&reply, &cookie, DHCPV4_OPT_MESSAGE, 1, &msg); dhcpv4_put(&reply, &cookie, DHCPV4_OPT_SERVERID, 4, &serverid); if (a) { uint32_t val; reply.yiaddr.s_addr = a->addr; val = htonl(leasetime); dhcpv4_put(&reply, &cookie, DHCPV4_OPT_LEASETIME, 4, &val); if (leasetime != UINT32_MAX) { val = htonl(500 * leasetime / 1000); dhcpv4_put(&reply, &cookie, DHCPV4_OPT_RENEW, 4, &val); val = htonl(875 * leasetime / 1000); dhcpv4_put(&reply, &cookie, DHCPV4_OPT_REBIND, 4, &val); } dhcpv4_put(&reply, &cookie, DHCPV4_OPT_NETMASK, 4, &iface->dhcpv4_mask.s_addr); if (a->hostname) dhcpv4_put(&reply, &cookie, DHCPV4_OPT_HOSTNAME, strlen(a->hostname), a->hostname); if (iface->dhcpv4_bcast.s_addr != INADDR_ANY) dhcpv4_put(&reply, &cookie, DHCPV4_OPT_BROADCAST, 4, &iface->dhcpv4_bcast); if (incl_fr_opt) { if (reqmsg == DHCPV4_MSG_REQUEST) { struct dhcpv4_auth_forcerenew auth = { .protocol = 3, .algorithm = 1, .rdm = 0, .replay = {htonl(time(NULL)), htonl(++serial)}, .type = 1, .key = {0}, }; memcpy(auth.key, a->key, sizeof(auth.key)); dhcpv4_put(&reply, &cookie, DHCPV4_OPT_AUTHENTICATION, sizeof(auth), &auth); } else { uint8_t one = 1; dhcpv4_put(&reply, &cookie, DHCPV4_OPT_FORCERENEW_NONCE_CAPABLE, sizeof(one), &one); } } } struct ifreq ifr; memset(&ifr, 0, sizeof(ifr)); strncpy(ifr.ifr_name, iface->ifname, sizeof(ifr.ifr_name) - 1); if (!ioctl(sock, SIOCGIFMTU, &ifr)) { uint16_t mtu = htons(ifr.ifr_mtu); dhcpv4_put(&reply, &cookie, DHCPV4_OPT_MTU, 2, &mtu); } if (iface->search && iface->search_len <= 255) dhcpv4_put(&reply, &cookie, DHCPV4_OPT_SEARCH_DOMAIN, iface->search_len, iface->search); else if (!res_init() && _res.dnsrch[0] && _res.dnsrch[0][0]) { uint8_t search_buf[256]; int len = dn_comp(_res.dnsrch[0], search_buf, sizeof(search_buf), NULL, NULL); if (len > 0) dhcpv4_put(&reply, &cookie, DHCPV4_OPT_SEARCH_DOMAIN, len, search_buf); } if (iface->dhcpv4_router_cnt == 0) dhcpv4_put(&reply, &cookie, DHCPV4_OPT_ROUTER, 4, &iface->dhcpv4_local); else dhcpv4_put(&reply, &cookie, DHCPV4_OPT_ROUTER, 4 * iface->dhcpv4_router_cnt, iface->dhcpv4_router); if (iface->dhcpv4_dns_cnt == 0) { if (iface->dns_service) dhcpv4_put(&reply, &cookie, DHCPV4_OPT_DNSSERVER, 4, &iface->dhcpv4_local); } else dhcpv4_put(&reply, &cookie, DHCPV4_OPT_DNSSERVER, 4 * iface->dhcpv4_dns_cnt, iface->dhcpv4_dns); dhcpv4_put(&reply, &cookie, DHCPV4_OPT_END, 0, NULL); struct sockaddr_in dest = *((struct sockaddr_in*)addr); if (req->giaddr.s_addr) { /* * relay agent is configured, send reply to the agent */ dest.sin_addr = req->giaddr; dest.sin_port = htons(DHCPV4_SERVER_PORT); } else if (req->ciaddr.s_addr && req->ciaddr.s_addr != dest.sin_addr.s_addr) { /* * client has existing configuration (ciaddr is set) AND this address is * not the address it used for the dhcp message */ dest.sin_addr = req->ciaddr; dest.sin_port = htons(DHCPV4_CLIENT_PORT); } else if ((ntohs(req->flags) & DHCPV4_FLAG_BROADCAST) || req->hlen != reply.hlen || !reply.yiaddr.s_addr) { /* * client requests a broadcast reply OR we can't offer an IP */ dest.sin_addr.s_addr = INADDR_BROADCAST; dest.sin_port = htons(DHCPV4_CLIENT_PORT); } else if (!req->ciaddr.s_addr && msg == DHCPV4_MSG_NAK) { /* * client has no previous configuration -> no IP, so we need to reply * with a broadcast packet */ dest.sin_addr.s_addr = INADDR_BROADCAST; dest.sin_port = htons(DHCPV4_CLIENT_PORT); } else { struct arpreq arp = {.arp_flags = ATF_COM}; /* * send reply to the newly (in this proccess) allocated IP */ dest.sin_addr = reply.yiaddr; dest.sin_port = htons(DHCPV4_CLIENT_PORT); memcpy(arp.arp_ha.sa_data, req->chaddr, 6); memcpy(&arp.arp_pa, &dest, sizeof(arp.arp_pa)); memcpy(arp.arp_dev, iface->ifname, sizeof(arp.arp_dev)); if (ioctl(sock, SIOCSARP, &arp) < 0) syslog(LOG_ERR, "ioctl(SIOCSARP): %m"); } if (send_reply(&reply, PACKET_SIZE(&reply, cookie), (struct sockaddr*)&dest, sizeof(dest), opaque) < 0) syslog(LOG_ERR, "Failed to send %s to %s - %s: %m", dhcpv4_msg_to_string(msg), dest.sin_addr.s_addr == INADDR_BROADCAST ? "ff:ff:ff:ff:ff:ff": odhcpd_print_mac(req->chaddr, req->hlen), inet_ntoa(dest.sin_addr)); else syslog(LOG_DEBUG, "Sent %s to %s - %s", dhcpv4_msg_to_string(msg), dest.sin_addr.s_addr == INADDR_BROADCAST ? "ff:ff:ff:ff:ff:ff": odhcpd_print_mac(req->chaddr, req->hlen), inet_ntoa(dest.sin_addr)); #ifdef WITH_UBUS if (msg == DHCPV4_MSG_ACK) ubus_bcast_dhcp_event("dhcp.ack", req->chaddr, req->hlen, &reply.yiaddr, a ? a->hostname : NULL, iface->ifname); #endif if (msg == DHCPV4_MSG_ACK) { dns_update_rr(a ? a->hostname : NULL, AF_INET, &reply.yiaddr); dns_update_finish(); } } static bool dhcpv4_insert_assignment(struct list_head *list, struct dhcp_assignment *a, uint32_t addr) { uint32_t h_addr = ntohl(addr); struct dhcp_assignment *c; list_for_each_entry(c, list, head) { uint32_t c_addr = ntohl(c->addr); if (c_addr == h_addr) return false; if (c_addr > h_addr) break; } /* Insert new node before c (might match list head) */ a->addr = addr; list_add_tail(&a->head, &c->head); return true; } static char* ip4toa(uint32_t addr) { static char buf[16]; snprintf(buf, sizeof(buf), "%u.%u.%u.%u", ((uint8_t *)&addr)[0], ((uint8_t *)&addr)[1], ((uint8_t *)&addr)[2], ((uint8_t *)&addr)[3]); return buf; } static bool dhcpv4_assign(struct interface *iface, struct dhcp_assignment *a, uint32_t raddr) { uint32_t start = ntohl(iface->dhcpv4_start_ip.s_addr); uint32_t end = ntohl(iface->dhcpv4_end_ip.s_addr); uint32_t count = end - start + 1; uint32_t seed = 0; bool assigned; /* Preconfigured IP address by static lease */ if (a->addr) { assigned = dhcpv4_insert_assignment(&iface->dhcpv4_assignments, a, a->addr); if (assigned) syslog(LOG_DEBUG, "Assigning static IP: %s", ip4toa(a->addr)); return assigned; } /* try to assign the IP the client asked for */ if (start <= ntohl(raddr) && ntohl(raddr) <= end && !config_find_lease_by_ipaddr(raddr)) { assigned = dhcpv4_insert_assignment(&iface->dhcpv4_assignments, a, raddr); if (assigned) { syslog(LOG_DEBUG, "Assigning the IP the client asked for: %s", ip4toa(a->addr)); return true; } } /* Seed RNG with checksum of hwaddress */ for (size_t i = 0; i < sizeof(a->hwaddr); ++i) { /* Knuth's multiplicative method */ uint8_t o = a->hwaddr[i]; seed += (o*2654435761) % UINT32_MAX; } srand(seed); for (uint32_t i = 0, try = (((uint32_t)rand()) % count) + start; i < count; ++i, try = (((try - start) + 1) % count) + start) { uint32_t n_try = htonl(try); if (config_find_lease_by_ipaddr(n_try)) continue; assigned = dhcpv4_insert_assignment(&iface->dhcpv4_assignments, a, n_try); if (assigned) { syslog(LOG_DEBUG, "Assigning mapped IP: %s (try %u of %u)", ip4toa(a->addr), i + 1, count); return true; } } syslog(LOG_NOTICE, "Can't assign any IP address -> address space is full"); return false; } static struct dhcp_assignment* dhcpv4_lease(struct interface *iface, enum dhcpv4_msg msg, const uint8_t *mac, const uint32_t reqaddr, uint32_t *leasetime, const char *hostname, const size_t hostname_len, const bool accept_fr_nonce, bool *incl_fr_opt, uint32_t *fr_serverid, const char* reqopts, const size_t reqopts_len) { struct dhcp_assignment *a = find_assignment_by_hwaddr(iface, mac); struct lease *l = config_find_lease_by_mac(mac); time_t now = odhcpd_time(); if (l && a && a->lease != l) { free_assignment(a); a = NULL; } if (a && (a->flags & OAF_BOUND) && a->fr_ip) { *fr_serverid = a->fr_ip->addr.addr.in.s_addr; dhcpv4_fr_stop(a); } if (msg == DHCPV4_MSG_DISCOVER || msg == DHCPV4_MSG_REQUEST) { bool assigned = !!a; if (!a) { if (!iface->no_dynamic_dhcp || l) { /* Create new binding */ a = alloc_assignment(0); if (!a) { syslog(LOG_WARNING, "Failed to alloc assignment on interface %s", iface->ifname); return NULL; } memcpy(a->hwaddr, mac, sizeof(a->hwaddr)); /* Set valid time to 0 for static lease indicating */ /* infinite lifetime otherwise current time */ a->valid_until = l ? 0 : now; a->dhcp_free_cb = dhcpv4_free_assignment; a->iface = iface; a->flags = OAF_DHCPV4; a->addr = l ? l->ipaddr : INADDR_ANY; assigned = dhcpv4_assign(iface, a, reqaddr); if (l) { a->flags |= OAF_STATIC; if (l->hostname) a->hostname = strdup(l->hostname); if (l->leasetime) a->leasetime = l->leasetime; list_add(&a->lease_list, &l->assignments); a->lease = l; } } } else if (((a->addr & iface->dhcpv4_mask.s_addr) != (iface->dhcpv4_start_ip.s_addr & iface->dhcpv4_mask.s_addr)) && !(a->flags & OAF_STATIC)) { list_del_init(&a->head); a->addr = INADDR_ANY; assigned = dhcpv4_assign(iface, a, reqaddr); } if (assigned) { uint32_t my_leasetime; if (a->leasetime) my_leasetime = a->leasetime; else my_leasetime = iface->dhcp_leasetime; if ((*leasetime == 0) || (my_leasetime < *leasetime)) *leasetime = my_leasetime; if (msg == DHCPV4_MSG_DISCOVER) { a->flags &= ~OAF_BOUND; *incl_fr_opt = accept_fr_nonce; a->valid_until = now; } else { if ((!(a->flags & OAF_STATIC) || !a->hostname) && hostname_len > 0) { a->hostname = realloc(a->hostname, hostname_len + 1); if (a->hostname) { memcpy(a->hostname, hostname, hostname_len); a->hostname[hostname_len] = 0; if (odhcpd_valid_hostname(a->hostname)) a->flags &= ~OAF_BROKEN_HOSTNAME; else a->flags |= OAF_BROKEN_HOSTNAME; } } if (reqopts_len > 0) { a->reqopts = realloc(a->reqopts, reqopts_len + 1); if (a->reqopts) { memcpy(a->reqopts, reqopts, reqopts_len); a->reqopts[reqopts_len] = 0; } } if (!(a->flags & OAF_BOUND)) { a->accept_fr_nonce = accept_fr_nonce; *incl_fr_opt = accept_fr_nonce; odhcpd_urandom(a->key, sizeof(a->key)); a->flags |= OAF_BOUND; } else *incl_fr_opt = false; a->valid_until = ((*leasetime == UINT32_MAX) ? 0 : (time_t)(now + *leasetime)); } } else if (!assigned && a) { /* Cleanup failed assignment */ free_assignment(a); a = NULL; } } else if (msg == DHCPV4_MSG_RELEASE && a) { a->flags &= ~OAF_BOUND; a->valid_until = now - 1; } else if (msg == DHCPV4_MSG_DECLINE && a) { a->flags &= ~OAF_BOUND; if (!(a->flags & OAF_STATIC) || a->lease->ipaddr != a->addr) { memset(a->hwaddr, 0, sizeof(a->hwaddr)); a->valid_until = now + 3600; /* Block address for 1h */ } else a->valid_until = now - 1; } dhcpv6_ia_write_statefile(); return a; }