/** * 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 "odhcpd.h" #include "dhcpv6.h" static void relay_client_request(struct sockaddr_in6 *source, const void *data, size_t len, struct interface *iface); static void relay_server_response(uint8_t *data, size_t len); static void handle_dhcpv6(void *addr, void *data, size_t len, struct interface *iface, void *dest); static void handle_client_request(void *addr, void *data, size_t len, struct interface *iface, void *dest_addr); // Create socket and register events int dhcpv6_init(void) { dhcpv6_ia_init(); return 0; } int dhcpv6_setup_interface(struct interface *iface, bool enable) { if (iface->dhcpv6_event.uloop.fd > 0) { uloop_fd_delete(&iface->dhcpv6_event.uloop); close(iface->dhcpv6_event.uloop.fd); iface->dhcpv6_event.uloop.fd = -1; } // Configure multicast settings if (enable && iface->dhcpv6) { int sock = socket(AF_INET6, SOCK_DGRAM | SOCK_CLOEXEC, IPPROTO_UDP); if (sock < 0) { syslog(LOG_ERR, "Failed to create DHCPv6 server socket: %m"); return -1; } // Basic IPv6 configuration setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE, iface->ifname, strlen(iface->ifname)); int val = 1; setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, &val, sizeof(val)); setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &val, sizeof(val)); setsockopt(sock, IPPROTO_IPV6, IPV6_RECVPKTINFO, &val, sizeof(val)); val = DHCPV6_HOP_COUNT_LIMIT; setsockopt(sock, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &val, sizeof(val)); val = 0; setsockopt(sock, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &val, sizeof(val)); struct sockaddr_in6 bind_addr = {AF_INET6, htons(DHCPV6_SERVER_PORT), 0, IN6ADDR_ANY_INIT, 0}; if (bind(sock, (struct sockaddr*)&bind_addr, sizeof(bind_addr))) { syslog(LOG_ERR, "Failed to open DHCPv6 server socket: %m"); return -1; } struct ipv6_mreq relay = {ALL_DHCPV6_RELAYS, iface->ifindex}; struct ipv6_mreq server = {ALL_DHCPV6_SERVERS, iface->ifindex}; setsockopt(sock, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP, &relay, sizeof(relay)); if (iface->dhcpv6 == MODE_SERVER) setsockopt(sock, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP, &server, sizeof(server)); iface->dhcpv6_event.uloop.fd = sock; iface->dhcpv6_event.handle_dgram = handle_dhcpv6; odhcpd_register(&iface->dhcpv6_event); } return dhcpv6_setup_ia_interface(iface, enable); } enum { IOV_NESTED = 0, IOV_DEST, IOV_MAXRT, #define IOV_STAT IOV_MAXRT IOV_DNS, IOV_DNS_ADDR, IOV_SEARCH, IOV_SEARCH_DOMAIN, IOV_PDBUF, #define IOV_REFRESH IOV_PDBUF IOV_CERID, IOV_DHCPV6_RAW, IOV_RELAY_MSG, IOV_TOTAL }; static void handle_nested_message(uint8_t *data, size_t len, uint8_t **opts, uint8_t **end, struct iovec iov[IOV_TOTAL - 1]) { struct dhcpv6_relay_header *hdr = (struct dhcpv6_relay_header*)data; if (iov[IOV_NESTED].iov_base == NULL) { iov[IOV_NESTED].iov_base = data; iov[IOV_NESTED].iov_len = len; } if (len < sizeof(struct dhcpv6_client_header)) return; if (hdr->msg_type != DHCPV6_MSG_RELAY_FORW) { iov[IOV_NESTED].iov_len = data - (uint8_t*)iov[IOV_NESTED].iov_base; struct dhcpv6_client_header *hdr = (void*)data; *opts = (uint8_t*)&hdr[1]; *end = data + len; return; } uint16_t otype, olen; uint8_t *odata; dhcpv6_for_each_option(hdr->options, data + len, otype, olen, odata) { if (otype == DHCPV6_OPT_RELAY_MSG) { iov[IOV_RELAY_MSG].iov_base = odata + olen; iov[IOV_RELAY_MSG].iov_len = (((uint8_t*)iov[IOV_NESTED].iov_base) + iov[IOV_NESTED].iov_len) - (odata + olen); handle_nested_message(odata, olen, opts, end, iov); return; } } } static void update_nested_message(uint8_t *data, size_t len, ssize_t pdiff) { struct dhcpv6_relay_header *hdr = (struct dhcpv6_relay_header*)data; if (hdr->msg_type != DHCPV6_MSG_RELAY_FORW) return; hdr->msg_type = DHCPV6_MSG_RELAY_REPL; uint16_t otype, olen; uint8_t *odata; dhcpv6_for_each_option(hdr->options, data + len, otype, olen, odata) { if (otype == DHCPV6_OPT_RELAY_MSG) { olen += pdiff; odata[-2] = (olen >> 8) & 0xff; odata[-1] = olen & 0xff; update_nested_message(odata, olen - pdiff, pdiff); return; } } } // Simple DHCPv6-server for information requests static void handle_client_request(void *addr, void *data, size_t len, struct interface *iface, void *dest_addr) { struct dhcpv6_client_header *hdr = data; if (len < sizeof(*hdr)) return; syslog(LOG_NOTICE, "Got DHCPv6 request"); // Construct reply message struct __attribute__((packed)) { uint8_t msg_type; uint8_t tr_id[3]; uint16_t serverid_type; uint16_t serverid_length; uint16_t duid_type; uint16_t hardware_type; uint8_t mac[6]; uint16_t clientid_type; uint16_t clientid_length; uint8_t clientid_buf[130]; } dest = { .msg_type = DHCPV6_MSG_REPLY, .serverid_type = htons(DHCPV6_OPT_SERVERID), .serverid_length = htons(10), .duid_type = htons(3), .hardware_type = htons(1), .clientid_type = htons(DHCPV6_OPT_CLIENTID), .clientid_buf = {0} }; odhcpd_get_mac(iface, dest.mac); struct __attribute__((packed)) { uint16_t type; uint16_t len; uint32_t value; } maxrt = {htons(DHCPV6_OPT_SOL_MAX_RT), htons(sizeof(maxrt) - 4), htonl(60)}; struct __attribute__((packed)) { uint16_t type; uint16_t len; uint16_t value; } stat = {htons(DHCPV6_OPT_STATUS), htons(sizeof(stat) - 4), htons(DHCPV6_STATUS_USEMULTICAST)}; struct __attribute__((packed)) { uint16_t type; uint16_t len; uint32_t value; } refresh = {htons(DHCPV6_OPT_INFO_REFRESH), htons(sizeof(uint32_t)), htonl(600)}; struct in6_addr dns_addr, *dns_addr_ptr = iface->dns; size_t dns_cnt = iface->dns_cnt; if ((dns_cnt == 0) && !odhcpd_get_interface_dns_addr(iface, &dns_addr)) { dns_addr_ptr = &dns_addr; dns_cnt = 1; } struct { uint16_t type; uint16_t len; } dns = {htons(DHCPV6_OPT_DNS_SERVERS), htons(dns_cnt * sizeof(*dns_addr_ptr))}; // DNS Search options uint8_t search_buf[256], *search_domain = iface->search; size_t search_len = iface->search_len; if (!search_domain && !res_init() && _res.dnsrch[0] && _res.dnsrch[0][0]) { int len = dn_comp(_res.dnsrch[0], search_buf, sizeof(search_buf), NULL, NULL); if (len > 0) { search_domain = search_buf; search_len = len; } } struct { uint16_t type; uint16_t len; } search = {htons(DHCPV6_OPT_DNS_DOMAIN), htons(search_len)}; struct dhcpv6_cer_id cerid = { #ifdef EXT_CER_ID .type = htons(EXT_CER_ID), #endif .len = htons(36), .addr = iface->dhcpv6_pd_cer, }; uint8_t pdbuf[512]; struct iovec iov[IOV_TOTAL] = { [IOV_NESTED] = {NULL, 0}, [IOV_DEST] = {&dest, (uint8_t*)&dest.clientid_type - (uint8_t*)&dest}, [IOV_MAXRT] = {&maxrt, sizeof(maxrt)}, [IOV_DNS] = {&dns, (dns_cnt) ? sizeof(dns) : 0}, [IOV_DNS_ADDR] = {dns_addr_ptr, dns_cnt * sizeof(*dns_addr_ptr)}, [IOV_SEARCH] = {&search, (search_len) ? sizeof(search) : 0}, [IOV_SEARCH_DOMAIN] = {search_domain, search_len}, [IOV_PDBUF] = {pdbuf, 0}, [IOV_CERID] = {&cerid, 0}, [IOV_DHCPV6_RAW] = {iface->dhcpv6_raw, iface->dhcpv6_raw_len}, [IOV_RELAY_MSG] = {NULL, 0} }; uint8_t *opts = (uint8_t*)&hdr[1], *opts_end = (uint8_t*)data + len; if (hdr->msg_type == DHCPV6_MSG_RELAY_FORW) handle_nested_message(data, len, &opts, &opts_end, iov); memcpy(dest.tr_id, &opts[-3], sizeof(dest.tr_id)); if (opts[-4] == DHCPV6_MSG_ADVERTISE || opts[-4] == DHCPV6_MSG_REPLY || opts[-4] == DHCPV6_MSG_RELAY_REPL) return; if (!IN6_IS_ADDR_MULTICAST((struct in6_addr *)dest_addr) && iov[IOV_NESTED].iov_len == 0 && (opts[-4] == DHCPV6_MSG_SOLICIT || opts[-4] == DHCPV6_MSG_CONFIRM || opts[-4] == DHCPV6_MSG_REBIND || opts[-4] == DHCPV6_MSG_INFORMATION_REQUEST)) return; if (opts[-4] == DHCPV6_MSG_SOLICIT) { dest.msg_type = DHCPV6_MSG_ADVERTISE; } else if (opts[-4] == DHCPV6_MSG_INFORMATION_REQUEST) { iov[IOV_REFRESH].iov_base = &refresh; iov[IOV_REFRESH].iov_len = sizeof(refresh); // Return inf max rt option in reply to information request maxrt.type = htons(DHCPV6_OPT_INF_MAX_RT); } // Go through options and find what we need uint16_t otype, olen; uint8_t *odata; dhcpv6_for_each_option(opts, opts_end, otype, olen, odata) { if (otype == DHCPV6_OPT_CLIENTID && olen <= 130) { dest.clientid_length = htons(olen); memcpy(dest.clientid_buf, odata, olen); iov[IOV_DEST].iov_len += 4 + olen; } else if (otype == DHCPV6_OPT_SERVERID) { if (olen != ntohs(dest.serverid_length) || memcmp(odata, &dest.duid_type, olen)) return; // Not for us } else if (iface->filter_class && otype == DHCPV6_OPT_USER_CLASS) { uint8_t *c = odata, *cend = &odata[olen]; for (; &c[2] <= cend && &c[2 + (c[0] << 8) + c[1]] <= cend; c = &c[2 + (c[0] << 8) + c[1]]) { size_t elen = strlen(iface->filter_class); if (((((size_t)c[0]) << 8) | c[1]) == elen && !memcmp(&c[2], iface->filter_class, elen)) return; // Ignore from homenet } } else if (otype == DHCPV6_OPT_IA_PD) { #ifdef EXT_CER_ID iov[IOV_CERID].iov_len = sizeof(cerid); if (IN6_IS_ADDR_UNSPECIFIED(&cerid.addr)) { struct odhcpd_ipaddr *addrs; ssize_t len = netlink_get_interface_addrs(0, true, &addrs); for (ssize_t i = 0; i < len; ++i) if (IN6_IS_ADDR_UNSPECIFIED(&cerid.addr) || memcmp(&addrs[i].addr, &cerid.addr, sizeof(cerid.addr)) < 0) cerid.addr = addrs[i].addr.in6; free(addrs); } #endif } } if (!IN6_IS_ADDR_MULTICAST((struct in6_addr *)dest_addr) && iov[IOV_NESTED].iov_len == 0 && (opts[-4] == DHCPV6_MSG_REQUEST || opts[-4] == DHCPV6_MSG_RENEW || opts[-4] == DHCPV6_MSG_RELEASE || opts[-4] == DHCPV6_MSG_DECLINE)) { iov[IOV_STAT].iov_base = &stat; iov[IOV_STAT].iov_len = sizeof(stat); for (ssize_t i = IOV_STAT + 1; i < IOV_TOTAL; ++i) iov[i].iov_len = 0; odhcpd_send(iface->dhcpv6_event.uloop.fd, addr, iov, ARRAY_SIZE(iov), iface); return; } if (opts[-4] != DHCPV6_MSG_INFORMATION_REQUEST) { ssize_t ialen = dhcpv6_handle_ia(pdbuf, sizeof(pdbuf), iface, addr, &opts[-4], opts_end); iov[IOV_PDBUF].iov_len = ialen; if (ialen < 0 || (ialen == 0 && (opts[-4] == DHCPV6_MSG_REBIND || opts[-4] == DHCPV6_MSG_CONFIRM))) return; } if (iov[IOV_NESTED].iov_len > 0) // Update length update_nested_message(data, len, iov[IOV_DEST].iov_len + iov[IOV_MAXRT].iov_len + iov[IOV_DNS].iov_len + iov[IOV_DNS_ADDR].iov_len + iov[IOV_SEARCH].iov_len + iov[IOV_SEARCH_DOMAIN].iov_len + iov[IOV_PDBUF].iov_len + iov[IOV_CERID].iov_len + iov[IOV_DHCPV6_RAW].iov_len - (4 + opts_end - opts)); odhcpd_send(iface->dhcpv6_event.uloop.fd, addr, iov, ARRAY_SIZE(iov), iface); } // Central DHCPv6-relay handler static void handle_dhcpv6(void *addr, void *data, size_t len, struct interface *iface, void *dest_addr) { if (iface->dhcpv6 == MODE_SERVER) { handle_client_request(addr, data, len, iface, dest_addr); } else if (iface->dhcpv6 == MODE_RELAY) { if (iface->master) relay_server_response(data, len); else relay_client_request(addr, data, len, iface); } } // Relay server response (regular relay server handling) static void relay_server_response(uint8_t *data, size_t len) { // Information we need to gather uint8_t *payload_data = NULL; size_t payload_len = 0; int32_t ifaceidx = 0; struct sockaddr_in6 target = {AF_INET6, htons(DHCPV6_CLIENT_PORT), 0, IN6ADDR_ANY_INIT, 0}; syslog(LOG_NOTICE, "Got a DHCPv6-reply"); int otype, olen; uint8_t *odata, *end = data + len; // Relay DHCPv6 reply from server to client struct dhcpv6_relay_header *h = (void*)data; if (len < sizeof(*h) || h->msg_type != DHCPV6_MSG_RELAY_REPL) return; memcpy(&target.sin6_addr, &h->peer_address, sizeof(struct in6_addr)); // Go through options and find what we need dhcpv6_for_each_option(h->options, end, otype, olen, odata) { if (otype == DHCPV6_OPT_INTERFACE_ID && olen == sizeof(ifaceidx)) { memcpy(&ifaceidx, odata, sizeof(ifaceidx)); } else if (otype == DHCPV6_OPT_RELAY_MSG) { payload_data = odata; payload_len = olen; } } // Invalid interface-id or basic payload struct interface *iface = odhcpd_get_interface_by_index(ifaceidx); if (!iface || iface->master || !payload_data || payload_len < 4) return; bool is_authenticated = false; struct in6_addr *dns_ptr = NULL; size_t dns_count = 0; // If the payload is relay-reply we have to send to the server port if (payload_data[0] == DHCPV6_MSG_RELAY_REPL) { target.sin6_port = htons(DHCPV6_SERVER_PORT); } else { // Go through the payload data struct dhcpv6_client_header *h = (void*)payload_data; end = payload_data + payload_len; dhcpv6_for_each_option(&h[1], end, otype, olen, odata) { if (otype == DHCPV6_OPT_DNS_SERVERS && olen >= 16) { dns_ptr = (struct in6_addr*)odata; dns_count = olen / 16; } else if (otype == DHCPV6_OPT_AUTH) { is_authenticated = true; } } } // Rewrite DNS servers if requested if (iface->always_rewrite_dns && dns_ptr && dns_count > 0) { if (is_authenticated) return; // Impossible to rewrite const struct in6_addr *rewrite = iface->dns; struct in6_addr addr; size_t rewrite_cnt = iface->dns_cnt; if (rewrite_cnt == 0) { if (odhcpd_get_interface_dns_addr(iface, &addr)) return; // Unable to get interface address rewrite = &addr; rewrite_cnt = 1; } // Copy over any other addresses for (size_t i = 0; i < dns_count; ++i) { size_t j = (i < rewrite_cnt) ? i : rewrite_cnt - 1; memcpy(&dns_ptr[i], &rewrite[j], sizeof(*rewrite)); } } struct iovec iov = {payload_data, payload_len}; odhcpd_send(iface->dhcpv6_event.uloop.fd, &target, &iov, 1, iface); } static struct odhcpd_ipaddr *relay_link_address(struct interface *iface) { struct odhcpd_ipaddr *addr = NULL; time_t now = odhcpd_time(); for (size_t i = 0; i < iface->addr6_len; i++) { if (iface->addr6[i].valid <= (uint32_t)now) continue; if (iface->addr6[i].preferred > (uint32_t)now) { addr = &iface->addr6[i]; break; } if (!addr || (iface->addr6[i].valid > addr->valid)) addr = &iface->addr6[i]; } return addr; } // Relay client request (regular DHCPv6-relay) static void relay_client_request(struct sockaddr_in6 *source, const void *data, size_t len, struct interface *iface) { struct interface *master = odhcpd_get_master_interface(); const struct dhcpv6_relay_header *h = data; if (!master || master->dhcpv6 != MODE_RELAY || h->msg_type == DHCPV6_MSG_RELAY_REPL || h->msg_type == DHCPV6_MSG_RECONFIGURE || h->msg_type == DHCPV6_MSG_REPLY || h->msg_type == DHCPV6_MSG_ADVERTISE) return; // Invalid message types for client syslog(LOG_NOTICE, "Got a DHCPv6-request"); // Construct our forwarding envelope struct dhcpv6_relay_forward_envelope hdr = { .msg_type = DHCPV6_MSG_RELAY_FORW, .hop_count = 0, .interface_id_type = htons(DHCPV6_OPT_INTERFACE_ID), .interface_id_len = htons(sizeof(uint32_t)), .relay_message_type = htons(DHCPV6_OPT_RELAY_MSG), .relay_message_len = htons(len), }; if (h->msg_type == DHCPV6_MSG_RELAY_FORW) { // handle relay-forward if (h->hop_count >= DHCPV6_HOP_COUNT_LIMIT) return; // Invalid hop count else hdr.hop_count = h->hop_count + 1; } // use memcpy here as the destination fields are unaligned uint32_t ifindex = iface->ifindex; memcpy(&hdr.peer_address, &source->sin6_addr, sizeof(struct in6_addr)); memcpy(&hdr.interface_id_data, &ifindex, sizeof(ifindex)); // Detect public IP of slave interface to use as link-address struct odhcpd_ipaddr *ip = relay_link_address(iface); if (!ip) { // No suitable address! Is the slave not configured yet? // Detect public IP of master interface and use it instead // This is WRONG and probably violates the RFC. However // otherwise we have a hen and egg problem because the // slave-interface cannot be auto-configured. ip = relay_link_address(master); if (!ip) return; // Could not obtain a suitable address } memcpy(&hdr.link_address, &ip->addr.in6, sizeof(hdr.link_address)); struct sockaddr_in6 dhcpv6_servers = {AF_INET6, htons(DHCPV6_SERVER_PORT), 0, ALL_DHCPV6_SERVERS, 0}; struct iovec iov[2] = {{&hdr, sizeof(hdr)}, {(void*)data, len}}; odhcpd_send(master->dhcpv6_event.uloop.fd, &dhcpv6_servers, iov, 2, master); }