X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=src%2Flibsystemd-dhcp%2Fdhcp-client.c;h=fe410676003541fdf36611defb1ab17d5c87e880;hp=85c8040da4123169a01c0481603d8c2268a1e268;hb=3b349af69aab440a625fedb21377e2bdc461098e;hpb=011feef852de96a1adaba476037ce01b5efefc35 diff --git a/src/libsystemd-dhcp/dhcp-client.c b/src/libsystemd-dhcp/dhcp-client.c index 85c8040da..fe4106760 100644 --- a/src/libsystemd-dhcp/dhcp-client.c +++ b/src/libsystemd-dhcp/dhcp-client.c @@ -21,19 +21,51 @@ #include #include #include +#include #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; + be32_t address; + be32_t server_address; + be32_t subnet_mask; + be32_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; + be32_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[] = { @@ -45,6 +77,17 @@ static const uint8_t default_req_opts[] = { 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; @@ -102,16 +145,853 @@ int sd_dhcp_client_set_index(sd_dhcp_client *client, int interface_index) return 0; } -sd_dhcp_client *sd_dhcp_client_new(void) +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); + } + + r = 0; + + 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 || r == DHCP_EVENT_NO_LEASE) + 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);