/*** This file is part of systemd. Copyright (C) 2013 Intel Corporation. All rights reserved. systemd 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. systemd 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 systemd; If not, see <http://www.gnu.org/licenses/>. ***/ #include <stdlib.h> #include <errno.h> #include <string.h> #include <stdio.h> #include <net/ethernet.h> #include "util.h" #include "list.h" #include "dhcp-protocol.h" #include "dhcp-internal.h" #include "sd-dhcp-client.h" #define DHCP_CLIENT_MIN_OPTIONS_SIZE 312 struct DHCPLease { uint32_t t1; uint32_t t2; uint32_t lifetime; uint32_t address; uint32_t server_address; uint32_t subnet_mask; uint32_t router; }; typedef struct DHCPLease DHCPLease; struct sd_dhcp_client { DHCPState state; sd_event *event; sd_event_source *timeout_resend; int index; int fd; union sockaddr_union link; sd_event_source *receive_message; uint8_t *req_opts; size_t req_opts_size; uint32_t last_addr; struct ether_addr mac_addr; uint32_t xid; usec_t start_time; unsigned int attempt; usec_t request_sent; sd_event_source *timeout_t1; sd_event_source *timeout_t2; sd_event_source *timeout_expire; sd_dhcp_client_cb_t cb; void *userdata; DHCPLease *lease; }; static const uint8_t default_req_opts[] = { DHCP_OPTION_SUBNET_MASK, DHCP_OPTION_ROUTER, DHCP_OPTION_HOST_NAME, DHCP_OPTION_DOMAIN_NAME, DHCP_OPTION_DOMAIN_NAME_SERVER, DHCP_OPTION_NTP_SERVER, }; int sd_dhcp_client_set_callback(sd_dhcp_client *client, sd_dhcp_client_cb_t cb, void *userdata) { assert_return(client, -EINVAL); client->cb = cb; client->userdata = userdata; return 0; } int sd_dhcp_client_set_request_option(sd_dhcp_client *client, uint8_t option) { size_t i; assert_return(client, -EINVAL); assert_return (client->state == DHCP_STATE_INIT, -EBUSY); switch(option) { case DHCP_OPTION_PAD: case DHCP_OPTION_OVERLOAD: case DHCP_OPTION_MESSAGE_TYPE: case DHCP_OPTION_PARAMETER_REQUEST_LIST: case DHCP_OPTION_END: return -EINVAL; default: break; } for (i = 0; i < client->req_opts_size; i++) if (client->req_opts[i] == option) return -EEXIST; if (!GREEDY_REALLOC(client->req_opts, client->req_opts_size, client->req_opts_size + 1)) return -ENOMEM; client->req_opts[client->req_opts_size - 1] = option; return 0; } int sd_dhcp_client_set_request_address(sd_dhcp_client *client, const struct in_addr *last_addr) { assert_return(client, -EINVAL); assert_return(client->state == DHCP_STATE_INIT, -EBUSY); if (last_addr) client->last_addr = last_addr->s_addr; else client->last_addr = INADDR_ANY; return 0; } int sd_dhcp_client_set_index(sd_dhcp_client *client, int interface_index) { assert_return(client, -EINVAL); assert_return(client->state == DHCP_STATE_INIT, -EBUSY); assert_return(interface_index >= -1, -EINVAL); client->index = interface_index; return 0; } int sd_dhcp_client_set_mac(sd_dhcp_client *client, const struct ether_addr *addr) { assert_return(client, -EINVAL); assert_return(client->state == DHCP_STATE_INIT, -EBUSY); memcpy(&client->mac_addr, addr, ETH_ALEN); return 0; } int sd_dhcp_client_get_address(sd_dhcp_client *client, struct in_addr *addr) { assert_return(client, -EINVAL); assert_return(addr, -EINVAL); switch (client->state) { case DHCP_STATE_INIT: case DHCP_STATE_SELECTING: case DHCP_STATE_INIT_REBOOT: case DHCP_STATE_REBOOTING: case DHCP_STATE_REQUESTING: return -EADDRNOTAVAIL; case DHCP_STATE_BOUND: case DHCP_STATE_RENEWING: case DHCP_STATE_REBINDING: addr->s_addr = client->lease->address; break; } return 0; } int sd_dhcp_client_get_netmask(sd_dhcp_client *client, struct in_addr *addr) { assert_return(client, -EINVAL); assert_return(addr, -EINVAL); switch (client->state) { case DHCP_STATE_INIT: case DHCP_STATE_SELECTING: case DHCP_STATE_INIT_REBOOT: case DHCP_STATE_REBOOTING: case DHCP_STATE_REQUESTING: return -EADDRNOTAVAIL; case DHCP_STATE_BOUND: case DHCP_STATE_RENEWING: case DHCP_STATE_REBINDING: addr->s_addr = client->lease->subnet_mask; break; } return 0; } int sd_dhcp_client_prefixlen(const struct in_addr *addr) { int len = 0; uint32_t mask; assert_return(addr, -EADDRNOTAVAIL); mask = be32toh(addr->s_addr); while (mask) { len++; mask = mask << 1; } return len; } int sd_dhcp_client_get_router(sd_dhcp_client *client, struct in_addr *addr) { assert_return(client, -EINVAL); assert_return(addr, -EINVAL); switch (client->state) { case DHCP_STATE_INIT: case DHCP_STATE_SELECTING: case DHCP_STATE_INIT_REBOOT: case DHCP_STATE_REBOOTING: case DHCP_STATE_REQUESTING: return -EADDRNOTAVAIL; case DHCP_STATE_BOUND: case DHCP_STATE_RENEWING: case DHCP_STATE_REBINDING: addr->s_addr = client->lease->router; break; } return 0; } static int client_notify(sd_dhcp_client *client, int event) { if (client->cb) client->cb(client, event, client->userdata); return 0; } static int client_stop(sd_dhcp_client *client, int error) { assert_return(client, -EINVAL); assert_return(client->state != DHCP_STATE_INIT && client->state != DHCP_STATE_INIT_REBOOT, -EALREADY); client->receive_message = sd_event_source_unref(client->receive_message); if (client->fd >= 0) close(client->fd); client->fd = -1; client->timeout_resend = sd_event_source_unref(client->timeout_resend); client->timeout_t1 = sd_event_source_unref(client->timeout_t1); client->timeout_t2 = sd_event_source_unref(client->timeout_t2); client->timeout_expire = sd_event_source_unref(client->timeout_expire); client->attempt = 1; client_notify(client, error); switch (client->state) { case DHCP_STATE_INIT: case DHCP_STATE_SELECTING: case DHCP_STATE_REQUESTING: case DHCP_STATE_BOUND: client->start_time = 0; client->state = DHCP_STATE_INIT; break; case DHCP_STATE_INIT_REBOOT: case DHCP_STATE_REBOOTING: case DHCP_STATE_RENEWING: case DHCP_STATE_REBINDING: break; } if (client->lease) { free(client->lease); client->lease = NULL; } return 0; } static int client_packet_init(sd_dhcp_client *client, uint8_t type, DHCPMessage *message, uint16_t secs, uint8_t **opt, size_t *optlen) { int err; be16_t max_size; *opt = (uint8_t *)(message + 1); if (*optlen < 4) return -ENOBUFS; *optlen -= 4; message->op = BOOTREQUEST; message->htype = 1; message->hlen = ETHER_ADDR_LEN; message->xid = htobe32(client->xid); /* Although 'secs' field is a SHOULD in RFC 2131, certain DHCP servers refuse to issue an DHCP lease if 'secs' is set to zero */ message->secs = htobe16(secs); memcpy(&message->chaddr, &client->mac_addr, ETH_ALEN); (*opt)[0] = 0x63; (*opt)[1] = 0x82; (*opt)[2] = 0x53; (*opt)[3] = 0x63; *opt += 4; err = dhcp_option_append(opt, optlen, DHCP_OPTION_MESSAGE_TYPE, 1, &type); if (err < 0) return err; /* Some DHCP servers will refuse to issue an DHCP lease if the Cliient Identifier option is not set */ err = dhcp_option_append(opt, optlen, DHCP_OPTION_CLIENT_IDENTIFIER, ETH_ALEN, &client->mac_addr); if (err < 0) return err; if (type == DHCP_DISCOVER || type == DHCP_REQUEST) { err = dhcp_option_append(opt, optlen, DHCP_OPTION_PARAMETER_REQUEST_LIST, client->req_opts_size, client->req_opts); if (err < 0) return err; /* Some DHCP servers will send bigger DHCP packets than the defined default size unless the Maximum Messge Size option is explicitely set */ max_size = htobe16(DHCP_IP_UDP_SIZE + DHCP_MESSAGE_SIZE + DHCP_CLIENT_MIN_OPTIONS_SIZE); err = dhcp_option_append(opt, optlen, DHCP_OPTION_MAXIMUM_MESSAGE_SIZE, 2, &max_size); if (err < 0) return err; } return 0; } static uint16_t client_checksum(void *buf, int len) { uint32_t sum; uint16_t *check; int i; uint8_t *odd; sum = 0; check = buf; for (i = 0; i < len / 2 ; i++) sum += check[i]; if (len & 0x01) { odd = buf; sum += odd[len]; } return ~((sum & 0xffff) + (sum >> 16)); } static void client_append_ip_headers(DHCPPacket *packet, uint16_t len) { packet->ip.version = IPVERSION; packet->ip.ihl = DHCP_IP_SIZE / 4; packet->ip.tot_len = htobe16(len); packet->ip.protocol = IPPROTO_UDP; packet->ip.saddr = INADDR_ANY; packet->ip.daddr = INADDR_BROADCAST; packet->udp.source = htobe16(DHCP_PORT_CLIENT); packet->udp.dest = htobe16(DHCP_PORT_SERVER); packet->udp.len = htobe16(len - DHCP_IP_SIZE); packet->ip.check = packet->udp.len; packet->udp.check = client_checksum(&packet->ip.ttl, len - 8); packet->ip.ttl = IPDEFTTL; packet->ip.check = 0; packet->ip.check = client_checksum(&packet->ip, DHCP_IP_SIZE); } static int client_send_discover(sd_dhcp_client *client, uint16_t secs) { int err = 0; _cleanup_free_ DHCPPacket *discover; size_t optlen, len; uint8_t *opt; optlen = DHCP_CLIENT_MIN_OPTIONS_SIZE; len = sizeof(DHCPPacket) + optlen; discover = malloc0(len); if (!discover) return -ENOMEM; err = client_packet_init(client, DHCP_DISCOVER, &discover->dhcp, secs, &opt, &optlen); if (err < 0) return err; if (client->last_addr != INADDR_ANY) { err = dhcp_option_append(&opt, &optlen, DHCP_OPTION_REQUESTED_IP_ADDRESS, 4, &client->last_addr); if (err < 0) return err; } err = dhcp_option_append(&opt, &optlen, DHCP_OPTION_END, 0, NULL); if (err < 0) return err; client_append_ip_headers(discover, len); err = dhcp_network_send_raw_socket(client->fd, &client->link, discover, len); return err; } static int client_send_request(sd_dhcp_client *client, uint16_t secs) { _cleanup_free_ DHCPPacket *request; size_t optlen, len; int err; uint8_t *opt; optlen = DHCP_CLIENT_MIN_OPTIONS_SIZE; len = DHCP_MESSAGE_SIZE + optlen; request = malloc0(len); if (!request) return -ENOMEM; err = client_packet_init(client, DHCP_REQUEST, &request->dhcp, secs, &opt, &optlen); if (err < 0) return err; if (client->state == DHCP_STATE_REQUESTING) { err = dhcp_option_append(&opt, &optlen, DHCP_OPTION_REQUESTED_IP_ADDRESS, 4, &client->lease->address); if (err < 0) return err; err = dhcp_option_append(&opt, &optlen, DHCP_OPTION_SERVER_IDENTIFIER, 4, &client->lease->server_address); if (err < 0) return err; } err = dhcp_option_append(&opt, &optlen, DHCP_OPTION_END, 0, NULL); if (err < 0) return err; client_append_ip_headers(request, len); err = dhcp_network_send_raw_socket(client->fd, &client->link, request, len); return err; } static int client_timeout_resend(sd_event_source *s, uint64_t usec, void *userdata) { sd_dhcp_client *client = userdata; usec_t next_timeout; uint16_t secs; int err = 0; secs = (usec - client->start_time) / USEC_PER_SEC; if (client->attempt < 64) client->attempt *= 2; next_timeout = usec + (client->attempt - 1) * USEC_PER_SEC + (random_u() & 0x1fffff); err = sd_event_add_monotonic(client->event, next_timeout, 10 * USEC_PER_MSEC, client_timeout_resend, client, &client->timeout_resend); if (err < 0) goto error; switch (client->state) { case DHCP_STATE_INIT: err = client_send_discover(client, secs); if (err >= 0) { client->state = DHCP_STATE_SELECTING; client->attempt = 1; } else { if (client->attempt >= 64) goto error; } break; case DHCP_STATE_SELECTING: err = client_send_discover(client, secs); if (err < 0 && client->attempt >= 64) goto error; break; case DHCP_STATE_REQUESTING: err = client_send_request(client, secs); if (err < 0 && client->attempt >= 64) goto error; client->request_sent = usec; break; case DHCP_STATE_INIT_REBOOT: case DHCP_STATE_REBOOTING: case DHCP_STATE_BOUND: case DHCP_STATE_RENEWING: case DHCP_STATE_REBINDING: break; } return 0; error: client_stop(client, err); /* Errors were dealt with when stopping the client, don't spill errors into the event loop handler */ return 0; } static int client_timeout_expire(sd_event_source *s, uint64_t usec, void *userdata) { sd_dhcp_client *client = userdata; client_stop(client, DHCP_EVENT_EXPIRED); return 0; } static int client_timeout_t2(sd_event_source *s, uint64_t usec, void *userdata) { return 0; } static int client_timeout_t1(sd_event_source *s, uint64_t usec, void *userdata) { return 0; } static int client_parse_offer(uint8_t code, uint8_t len, const uint8_t *option, void *user_data) { DHCPLease *lease = user_data; be32_t val; switch(code) { case DHCP_OPTION_IP_ADDRESS_LEASE_TIME: if (len == 4) { memcpy(&val, option, 4); lease->lifetime = be32toh(val); } break; case DHCP_OPTION_SERVER_IDENTIFIER: if (len >= 4) memcpy(&lease->server_address, option, 4); break; case DHCP_OPTION_SUBNET_MASK: if (len >= 4) memcpy(&lease->subnet_mask, option, 4); break; case DHCP_OPTION_ROUTER: if (len >= 4) memcpy(&lease->router, option, 4); break; case DHCP_OPTION_RENEWAL_T1_TIME: if (len == 4) { memcpy(&val, option, 4); lease->t1 = be32toh(val); } break; case DHCP_OPTION_REBINDING_T2_TIME: if (len == 4) { memcpy(&val, option, 4); lease->t2 = be32toh(val); } break; } return 0; } static int client_verify_headers(sd_dhcp_client *client, DHCPPacket *message, size_t len) { size_t hdrlen; if (len < (DHCP_IP_UDP_SIZE + DHCP_MESSAGE_SIZE)) return -EINVAL; hdrlen = message->ip.ihl * 4; if (hdrlen < 20 || hdrlen > len || client_checksum(&message->ip, hdrlen)) return -EINVAL; message->ip.check = message->udp.len; message->ip.ttl = 0; if (hdrlen + be16toh(message->udp.len) > len || client_checksum(&message->ip.ttl, be16toh(message->udp.len) + 12)) return -EINVAL; if (be16toh(message->udp.source) != DHCP_PORT_SERVER || be16toh(message->udp.dest) != DHCP_PORT_CLIENT) return -EINVAL; if (message->dhcp.op != BOOTREPLY) return -EINVAL; if (be32toh(message->dhcp.xid) != client->xid) return -EINVAL; if (memcmp(&message->dhcp.chaddr[0], &client->mac_addr.ether_addr_octet, ETHER_ADDR_LEN)) return -EINVAL; return 0; } static int client_receive_offer(sd_dhcp_client *client, DHCPPacket *offer, size_t len) { int err; DHCPLease *lease; err = client_verify_headers(client, offer, len); if (err < 0) return err; lease = new0(DHCPLease, 1); if (!lease) return -ENOMEM; len = len - DHCP_IP_UDP_SIZE; if (dhcp_option_parse(&offer->dhcp, len, client_parse_offer, lease) != DHCP_OFFER) goto error; lease->address = offer->dhcp.yiaddr; if (lease->address == INADDR_ANY || lease->server_address == INADDR_ANY || lease->subnet_mask == INADDR_ANY || lease->lifetime == 0) goto error; client->lease = lease; return 0; error: free(lease); return -ENOMSG; } static int client_receive_ack(sd_dhcp_client *client, DHCPPacket *offer, size_t len) { int r; DHCPLease *lease; r = client_verify_headers(client, offer, len); if (r < 0) return r; lease = new0(DHCPLease, 1); if (!lease) return -ENOBUFS; len = len - DHCP_IP_UDP_SIZE; r = dhcp_option_parse(&offer->dhcp, len, client_parse_offer, lease); if (r != DHCP_ACK) goto error; lease->address = offer->dhcp.yiaddr; if (lease->address == INADDR_ANY || lease->server_address == INADDR_ANY || lease->subnet_mask == INADDR_ANY || lease->lifetime == 0) { r = -ENOMSG; goto error; } r = DHCP_EVENT_IP_ACQUIRE; if (client->lease) { if (client->lease->address != lease->address || client->lease->subnet_mask != lease->subnet_mask || client->lease->router != lease->router) { r = DHCP_EVENT_IP_CHANGE; } free(client->lease); } client->lease = lease; return r; error: free(lease); return r; } static uint64_t client_compute_timeout(uint64_t request_sent, uint32_t lifetime) { return request_sent + (lifetime - 3) * USEC_PER_SEC + + (random_u() & 0x1fffff); } static int client_set_lease_timeouts(sd_dhcp_client *client, uint64_t usec) { int err; uint64_t next_timeout; if (client->lease->lifetime < 10) return -EINVAL; if (!client->lease->t1) client->lease->t1 = client->lease->lifetime / 2; next_timeout = client_compute_timeout(client->request_sent, client->lease->t1); if (next_timeout < usec) return -EINVAL; err = sd_event_add_monotonic(client->event, next_timeout, 10 * USEC_PER_MSEC, client_timeout_t1, client, &client->timeout_t1); if (err < 0) return err; if (!client->lease->t2) client->lease->t2 = client->lease->lifetime * 7 / 8; if (client->lease->t2 < client->lease->t1) return -EINVAL; if (client->lease->lifetime < client->lease->t2) return -EINVAL; next_timeout = client_compute_timeout(client->request_sent, client->lease->t2); if (next_timeout < usec) return -EINVAL; err = sd_event_add_monotonic(client->event, next_timeout, 10 * USEC_PER_MSEC, client_timeout_t2, client, &client->timeout_t2); if (err < 0) return err; next_timeout = client_compute_timeout(client->request_sent, client->lease->lifetime); if (next_timeout < usec) return -EINVAL; err = sd_event_add_monotonic(client->event, next_timeout, 10 * USEC_PER_MSEC, client_timeout_expire, client, &client->timeout_expire); if (err < 0) return err; return 0; } static int client_receive_raw_message(sd_event_source *s, int fd, uint32_t revents, void *userdata) { sd_dhcp_client *client = userdata; uint8_t buf[sizeof(DHCPPacket) + DHCP_CLIENT_MIN_OPTIONS_SIZE]; int buflen = sizeof(buf); int len, r = 0; DHCPPacket *message; usec_t time_now; len = read(fd, &buf, buflen); if (len < 0) return 0; r = sd_event_get_now_monotonic(client->event, &time_now); if (r < 0) goto error; message = (DHCPPacket *)&buf; switch (client->state) { case DHCP_STATE_SELECTING: if (client_receive_offer(client, message, len) >= 0) { client->timeout_resend = sd_event_source_unref(client->timeout_resend); client->state = DHCP_STATE_REQUESTING; client->attempt = 1; r = sd_event_add_monotonic(client->event, time_now, 0, client_timeout_resend, client, &client->timeout_resend); if (r < 0) goto error; } break; case DHCP_STATE_REQUESTING: r = client_receive_ack(client, message, len); if (r == DHCP_EVENT_NO_LEASE) goto error; if (r >= 0) { client->timeout_resend = sd_event_source_unref(client->timeout_resend); client->state = DHCP_STATE_BOUND; client->attempt = 1; client->last_addr = client->lease->address; r = client_set_lease_timeouts(client, time_now); if (r < 0 ) goto error; client_notify(client, DHCP_EVENT_IP_ACQUIRE); close(client->fd); client->fd = -1; client->receive_message = sd_event_source_unref(client->receive_message); } break; case DHCP_STATE_INIT: case DHCP_STATE_INIT_REBOOT: case DHCP_STATE_REBOOTING: case DHCP_STATE_BOUND: case DHCP_STATE_RENEWING: case DHCP_STATE_REBINDING: break; } error: if (r < 0) return client_stop(client, r); return 0; } int sd_dhcp_client_start(sd_dhcp_client *client) { int err; assert_return(client, -EINVAL); assert_return(client->index >= 0, -EINVAL); assert_return(client->state == DHCP_STATE_INIT || client->state == DHCP_STATE_INIT_REBOOT, -EBUSY); client->xid = random_u(); client->fd = dhcp_network_bind_raw_socket(client->index, &client->link); if (client->fd < 0) { err = client->fd; goto error; } err = sd_event_add_io(client->event, client->fd, EPOLLIN, client_receive_raw_message, client, &client->receive_message); if (err < 0) goto error; client->start_time = now(CLOCK_MONOTONIC); err = sd_event_add_monotonic(client->event, client->start_time, 0, client_timeout_resend, client, &client->timeout_resend); if (err < 0) goto error; return 0; error: client_stop(client, err); return err; } int sd_dhcp_client_stop(sd_dhcp_client *client) { return client_stop(client, DHCP_EVENT_STOP); } sd_dhcp_client *sd_dhcp_client_free(sd_dhcp_client *client) { assert_return(client, NULL); sd_dhcp_client_stop(client); sd_event_unref(client->event); free(client->req_opts); free(client); return NULL; } sd_dhcp_client *sd_dhcp_client_new(sd_event *event) { sd_dhcp_client *client; assert_return(event, NULL); client = new0(sd_dhcp_client, 1); if (!client) return NULL; client->event = sd_event_ref(event); client->state = DHCP_STATE_INIT; client->index = -1; client->fd = -1; client->attempt = 1; client->req_opts_size = ELEMENTSOF(default_req_opts); client->req_opts = memdup(default_req_opts, client->req_opts_size); if (!client->req_opts) { free(client); return NULL; } return client; }