diff options
Diffstat (limited to 'src/libsystemd-network/sd-dhcp-client.c')
| -rw-r--r-- | src/libsystemd-network/sd-dhcp-client.c | 1945 |
1 files changed, 1945 insertions, 0 deletions
diff --git a/src/libsystemd-network/sd-dhcp-client.c b/src/libsystemd-network/sd-dhcp-client.c new file mode 100644 index 0000000..35fc88e --- /dev/null +++ b/src/libsystemd-network/sd-dhcp-client.c @@ -0,0 +1,1945 @@ +/* SPDX-License-Identifier: LGPL-2.1+ */ +/*** + Copyright © 2013 Intel Corporation. All rights reserved. +***/ + +#include <errno.h> +#include <net/ethernet.h> +#include <net/if_arp.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <sys/ioctl.h> +#include <linux/if_infiniband.h> + +#include "sd-dhcp-client.h" + +#include "alloc-util.h" +#include "async.h" +#include "dhcp-identifier.h" +#include "dhcp-internal.h" +#include "dhcp-lease-internal.h" +#include "dhcp-protocol.h" +#include "dns-domain.h" +#include "event-util.h" +#include "hostname-util.h" +#include "io-util.h" +#include "random-util.h" +#include "string-util.h" +#include "strv.h" +#include "util.h" + +#define MAX_CLIENT_ID_LEN (sizeof(uint32_t) + MAX_DUID_LEN) /* Arbitrary limit */ +#define MAX_MAC_ADDR_LEN CONST_MAX(INFINIBAND_ALEN, ETH_ALEN) + +#define RESTART_AFTER_NAK_MIN_USEC (1 * USEC_PER_SEC) +#define RESTART_AFTER_NAK_MAX_USEC (30 * USEC_PER_MINUTE) + +struct sd_dhcp_client { + unsigned n_ref; + + DHCPState state; + sd_event *event; + int event_priority; + sd_event_source *timeout_resend; + int ifindex; + int fd; + uint16_t port; + union sockaddr_union link; + sd_event_source *receive_message; + bool request_broadcast; + uint8_t *req_opts; + size_t req_opts_allocated; + size_t req_opts_size; + bool anonymize; + be32_t last_addr; + uint8_t mac_addr[MAX_MAC_ADDR_LEN]; + size_t mac_addr_len; + uint16_t arp_type; + struct { + uint8_t type; + union { + struct { + /* 0: Generic (non-LL) (RFC 2132) */ + uint8_t data[MAX_CLIENT_ID_LEN]; + } _packed_ gen; + struct { + /* 1: Ethernet Link-Layer (RFC 2132) */ + uint8_t haddr[ETH_ALEN]; + } _packed_ eth; + struct { + /* 2 - 254: ARP/Link-Layer (RFC 2132) */ + uint8_t haddr[0]; + } _packed_ ll; + struct { + /* 255: Node-specific (RFC 4361) */ + be32_t iaid; + struct duid duid; + } _packed_ ns; + struct { + uint8_t data[MAX_CLIENT_ID_LEN]; + } _packed_ raw; + }; + } _packed_ client_id; + size_t client_id_len; + char *hostname; + char *vendor_class_identifier; + char **user_class; + uint32_t mtu; + uint32_t xid; + usec_t start_time; + unsigned attempt; + usec_t request_sent; + sd_event_source *timeout_t1; + sd_event_source *timeout_t2; + sd_event_source *timeout_expire; + sd_dhcp_client_callback_t callback; + void *userdata; + sd_dhcp_lease *lease; + usec_t start_delay; +}; + +static const uint8_t default_req_opts[] = { + SD_DHCP_OPTION_SUBNET_MASK, + SD_DHCP_OPTION_ROUTER, + SD_DHCP_OPTION_HOST_NAME, + SD_DHCP_OPTION_DOMAIN_NAME, + SD_DHCP_OPTION_DOMAIN_NAME_SERVER, +}; + +/* RFC7844 section 3: + MAY contain the Parameter Request List option. + RFC7844 section 3.6: + The client intending to protect its privacy SHOULD only request a + minimal number of options in the PRL and SHOULD also randomly shuffle + the ordering of option codes in the PRL. If this random ordering + cannot be implemented, the client MAY order the option codes in the + PRL by option code number (lowest to highest). +*/ +/* NOTE: using PRL options that Windows 10 RFC7844 implementation uses */ +static const uint8_t default_req_opts_anonymize[] = { + SD_DHCP_OPTION_SUBNET_MASK, /* 1 */ + SD_DHCP_OPTION_ROUTER, /* 3 */ + SD_DHCP_OPTION_DOMAIN_NAME_SERVER, /* 6 */ + SD_DHCP_OPTION_DOMAIN_NAME, /* 15 */ + SD_DHCP_OPTION_ROUTER_DISCOVER, /* 31 */ + SD_DHCP_OPTION_STATIC_ROUTE, /* 33 */ + SD_DHCP_OPTION_VENDOR_SPECIFIC, /* 43 */ + SD_DHCP_OPTION_NETBIOS_NAMESERVER, /* 44 */ + SD_DHCP_OPTION_NETBIOS_NODETYPE, /* 46 */ + SD_DHCP_OPTION_NETBIOS_SCOPE, /* 47 */ + SD_DHCP_OPTION_CLASSLESS_STATIC_ROUTE, /* 121 */ + SD_DHCP_OPTION_PRIVATE_CLASSLESS_STATIC_ROUTE, /* 249 */ + SD_DHCP_OPTION_PRIVATE_PROXY_AUTODISCOVERY, /* 252 */ +}; + +static int client_receive_message_raw( + sd_event_source *s, + int fd, + uint32_t revents, + void *userdata); +static int client_receive_message_udp( + sd_event_source *s, + int fd, + uint32_t revents, + void *userdata); +static void client_stop(sd_dhcp_client *client, int error); + +int sd_dhcp_client_set_callback( + sd_dhcp_client *client, + sd_dhcp_client_callback_t cb, + void *userdata) { + + assert_return(client, -EINVAL); + + client->callback = cb; + client->userdata = userdata; + + return 0; +} + +int sd_dhcp_client_set_request_broadcast(sd_dhcp_client *client, int broadcast) { + assert_return(client, -EINVAL); + + client->request_broadcast = !!broadcast; + + 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(IN_SET(client->state, DHCP_STATE_INIT, DHCP_STATE_STOPPED), -EBUSY); + + switch(option) { + + case SD_DHCP_OPTION_PAD: + case SD_DHCP_OPTION_OVERLOAD: + case SD_DHCP_OPTION_MESSAGE_TYPE: + case SD_DHCP_OPTION_PARAMETER_REQUEST_LIST: + case SD_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_allocated, + client->req_opts_size + 1)) + return -ENOMEM; + + client->req_opts[client->req_opts_size++] = 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(IN_SET(client->state, DHCP_STATE_INIT, DHCP_STATE_STOPPED), -EBUSY); + + if (last_addr) + client->last_addr = last_addr->s_addr; + else + client->last_addr = INADDR_ANY; + + return 0; +} + +int sd_dhcp_client_set_ifindex(sd_dhcp_client *client, int ifindex) { + + assert_return(client, -EINVAL); + assert_return(IN_SET(client->state, DHCP_STATE_INIT, DHCP_STATE_STOPPED), -EBUSY); + assert_return(ifindex > 0, -EINVAL); + + client->ifindex = ifindex; + return 0; +} + +int sd_dhcp_client_set_mac( + sd_dhcp_client *client, + const uint8_t *addr, + size_t addr_len, + uint16_t arp_type) { + + DHCP_CLIENT_DONT_DESTROY(client); + bool need_restart = false; + + assert_return(client, -EINVAL); + assert_return(addr, -EINVAL); + assert_return(addr_len > 0 && addr_len <= MAX_MAC_ADDR_LEN, -EINVAL); + assert_return(arp_type > 0, -EINVAL); + + if (arp_type == ARPHRD_ETHER) + assert_return(addr_len == ETH_ALEN, -EINVAL); + else if (arp_type == ARPHRD_INFINIBAND) + assert_return(addr_len == INFINIBAND_ALEN, -EINVAL); + else + return -EINVAL; + + if (client->mac_addr_len == addr_len && + memcmp(&client->mac_addr, addr, addr_len) == 0) + return 0; + + if (!IN_SET(client->state, DHCP_STATE_INIT, DHCP_STATE_STOPPED)) { + log_dhcp_client(client, "Changing MAC address on running DHCP client, restarting"); + need_restart = true; + client_stop(client, SD_DHCP_CLIENT_EVENT_STOP); + } + + memcpy(&client->mac_addr, addr, addr_len); + client->mac_addr_len = addr_len; + client->arp_type = arp_type; + + if (need_restart && client->state != DHCP_STATE_STOPPED) + sd_dhcp_client_start(client); + + return 0; +} + +int sd_dhcp_client_get_client_id( + sd_dhcp_client *client, + uint8_t *type, + const uint8_t **data, + size_t *data_len) { + + assert_return(client, -EINVAL); + assert_return(type, -EINVAL); + assert_return(data, -EINVAL); + assert_return(data_len, -EINVAL); + + *type = 0; + *data = NULL; + *data_len = 0; + if (client->client_id_len) { + *type = client->client_id.type; + *data = client->client_id.raw.data; + *data_len = client->client_id_len - sizeof(client->client_id.type); + } + + return 0; +} + +int sd_dhcp_client_set_client_id( + sd_dhcp_client *client, + uint8_t type, + const uint8_t *data, + size_t data_len) { + + DHCP_CLIENT_DONT_DESTROY(client); + bool need_restart = false; + + assert_return(client, -EINVAL); + assert_return(data, -EINVAL); + assert_return(data_len > 0 && data_len <= MAX_CLIENT_ID_LEN, -EINVAL); + + if (client->client_id_len == data_len + sizeof(client->client_id.type) && + client->client_id.type == type && + memcmp(&client->client_id.raw.data, data, data_len) == 0) + return 0; + + /* For hardware types, log debug message about unexpected data length. + * + * Note that infiniband's INFINIBAND_ALEN is 20 bytes long, but only + * last last 8 bytes of the address are stable and suitable to put into + * the client-id. The caller is advised to account for that. */ + if ((type == ARPHRD_ETHER && data_len != ETH_ALEN) || + (type == ARPHRD_INFINIBAND && data_len != 8)) + log_dhcp_client(client, "Changing client ID to hardware type %u with " + "unexpected address length %zu", + type, data_len); + + if (!IN_SET(client->state, DHCP_STATE_INIT, DHCP_STATE_STOPPED)) { + log_dhcp_client(client, "Changing client ID on running DHCP " + "client, restarting"); + need_restart = true; + client_stop(client, SD_DHCP_CLIENT_EVENT_STOP); + } + + client->client_id.type = type; + memcpy(&client->client_id.raw.data, data, data_len); + client->client_id_len = data_len + sizeof (client->client_id.type); + + if (need_restart && client->state != DHCP_STATE_STOPPED) + sd_dhcp_client_start(client); + + return 0; +} + +/** + * Sets IAID and DUID. If duid is non-null, the DUID is set to duid_type + duid + * without further modification. Otherwise, if duid_type is supported, DUID + * is set based on that type. Otherwise, an error is returned. + */ +static int dhcp_client_set_iaid_duid_internal( + sd_dhcp_client *client, + bool iaid_append, + bool iaid_set, + uint32_t iaid, + uint16_t duid_type, + const void *duid, + size_t duid_len, + usec_t llt_time) { + + DHCP_CLIENT_DONT_DESTROY(client); + int r; + size_t len; + + assert_return(client, -EINVAL); + assert_return(duid_len == 0 || duid, -EINVAL); + + if (duid) { + r = dhcp_validate_duid_len(duid_type, duid_len, true); + if (r < 0) + return r; + } + + zero(client->client_id); + client->client_id.type = 255; + + if (iaid_append) { + if (iaid_set) + client->client_id.ns.iaid = htobe32(iaid); + else { + r = dhcp_identifier_set_iaid(client->ifindex, client->mac_addr, + client->mac_addr_len, + true, + &client->client_id.ns.iaid); + if (r < 0) + return r; + } + } + + if (duid) { + client->client_id.ns.duid.type = htobe16(duid_type); + memcpy(&client->client_id.ns.duid.raw.data, duid, duid_len); + len = sizeof(client->client_id.ns.duid.type) + duid_len; + } else + switch (duid_type) { + case DUID_TYPE_LLT: + if (client->mac_addr_len == 0) + return -EOPNOTSUPP; + + r = dhcp_identifier_set_duid_llt(&client->client_id.ns.duid, llt_time, client->mac_addr, client->mac_addr_len, client->arp_type, &len); + if (r < 0) + return r; + break; + case DUID_TYPE_EN: + r = dhcp_identifier_set_duid_en(&client->client_id.ns.duid, &len); + if (r < 0) + return r; + break; + case DUID_TYPE_LL: + if (client->mac_addr_len == 0) + return -EOPNOTSUPP; + + r = dhcp_identifier_set_duid_ll(&client->client_id.ns.duid, client->mac_addr, client->mac_addr_len, client->arp_type, &len); + if (r < 0) + return r; + break; + case DUID_TYPE_UUID: + r = dhcp_identifier_set_duid_uuid(&client->client_id.ns.duid, &len); + if (r < 0) + return r; + break; + default: + return -EINVAL; + } + + client->client_id_len = sizeof(client->client_id.type) + len + + (iaid_append ? sizeof(client->client_id.ns.iaid) : 0); + + if (!IN_SET(client->state, DHCP_STATE_INIT, DHCP_STATE_STOPPED)) { + log_dhcp_client(client, "Configured %sDUID, restarting.", iaid_append ? "IAID+" : ""); + client_stop(client, SD_DHCP_CLIENT_EVENT_STOP); + sd_dhcp_client_start(client); + } + + return 0; +} + +int sd_dhcp_client_set_iaid_duid( + sd_dhcp_client *client, + bool iaid_set, + uint32_t iaid, + uint16_t duid_type, + const void *duid, + size_t duid_len) { + return dhcp_client_set_iaid_duid_internal(client, true, iaid_set, iaid, duid_type, duid, duid_len, 0); +} + +int sd_dhcp_client_set_iaid_duid_llt( + sd_dhcp_client *client, + bool iaid_set, + uint32_t iaid, + usec_t llt_time) { + return dhcp_client_set_iaid_duid_internal(client, true, iaid_set, iaid, DUID_TYPE_LLT, NULL, 0, llt_time); +} + +int sd_dhcp_client_set_duid( + sd_dhcp_client *client, + uint16_t duid_type, + const void *duid, + size_t duid_len) { + return dhcp_client_set_iaid_duid_internal(client, false, false, 0, duid_type, duid, duid_len, 0); +} + +int sd_dhcp_client_set_duid_llt( + sd_dhcp_client *client, + usec_t llt_time) { + return dhcp_client_set_iaid_duid_internal(client, false, false, 0, DUID_TYPE_LLT, NULL, 0, llt_time); +} + +int sd_dhcp_client_set_hostname( + sd_dhcp_client *client, + const char *hostname) { + + assert_return(client, -EINVAL); + + /* Make sure hostnames qualify as DNS and as Linux hostnames */ + if (hostname && + !(hostname_is_valid(hostname, false) && dns_name_is_valid(hostname) > 0)) + return -EINVAL; + + return free_and_strdup(&client->hostname, hostname); +} + +int sd_dhcp_client_set_vendor_class_identifier( + sd_dhcp_client *client, + const char *vci) { + + assert_return(client, -EINVAL); + + return free_and_strdup(&client->vendor_class_identifier, vci); +} + +int sd_dhcp_client_set_user_class( + sd_dhcp_client *client, + const char* const* user_class) { + + _cleanup_strv_free_ char **s = NULL; + char **p; + + STRV_FOREACH(p, (char **) user_class) + if (strlen(*p) > 255) + return -ENAMETOOLONG; + + s = strv_copy((char **) user_class); + if (!s) + return -ENOMEM; + + client->user_class = TAKE_PTR(s); + + return 0; +} + +int sd_dhcp_client_set_client_port( + sd_dhcp_client *client, + uint16_t port) { + + assert_return(client, -EINVAL); + + client->port = port; + + return 0; +} + +int sd_dhcp_client_set_mtu(sd_dhcp_client *client, uint32_t mtu) { + assert_return(client, -EINVAL); + assert_return(mtu >= DHCP_DEFAULT_MIN_SIZE, -ERANGE); + + client->mtu = mtu; + + return 0; +} + +int sd_dhcp_client_get_lease(sd_dhcp_client *client, sd_dhcp_lease **ret) { + assert_return(client, -EINVAL); + + if (!IN_SET(client->state, DHCP_STATE_BOUND, DHCP_STATE_RENEWING, DHCP_STATE_REBINDING)) + return -EADDRNOTAVAIL; + + if (ret) + *ret = client->lease; + + return 0; +} + +static void client_notify(sd_dhcp_client *client, int event) { + assert(client); + + if (client->callback) + client->callback(client, event, client->userdata); +} + +static int client_initialize(sd_dhcp_client *client) { + assert_return(client, -EINVAL); + + client->receive_message = sd_event_source_unref(client->receive_message); + + client->fd = asynchronous_close(client->fd); + + (void) event_source_disable(client->timeout_resend); + (void) event_source_disable(client->timeout_t1); + (void) event_source_disable(client->timeout_t2); + (void) event_source_disable(client->timeout_expire); + + client->attempt = 1; + + client->state = DHCP_STATE_INIT; + client->xid = 0; + + client->lease = sd_dhcp_lease_unref(client->lease); + + return 0; +} + +static void client_stop(sd_dhcp_client *client, int error) { + assert(client); + + if (error < 0) + log_dhcp_client(client, "STOPPED: %s", strerror(-error)); + else if (error == SD_DHCP_CLIENT_EVENT_STOP) + log_dhcp_client(client, "STOPPED"); + else + log_dhcp_client(client, "STOPPED: Unknown event"); + + client_notify(client, error); + + client_initialize(client); +} + +static int client_message_init( + sd_dhcp_client *client, + DHCPPacket **ret, + uint8_t type, + size_t *_optlen, + size_t *_optoffset) { + + _cleanup_free_ DHCPPacket *packet = NULL; + size_t optlen, optoffset, size; + be16_t max_size; + usec_t time_now; + uint16_t secs; + int r; + + assert(client); + assert(client->start_time); + assert(ret); + assert(_optlen); + assert(_optoffset); + assert(IN_SET(type, DHCP_DISCOVER, DHCP_REQUEST)); + + optlen = DHCP_MIN_OPTIONS_SIZE; + size = sizeof(DHCPPacket) + optlen; + + packet = malloc0(size); + if (!packet) + return -ENOMEM; + + r = dhcp_message_init(&packet->dhcp, BOOTREQUEST, client->xid, type, + client->arp_type, optlen, &optoffset); + if (r < 0) + return r; + + /* Although 'secs' field is a SHOULD in RFC 2131, certain DHCP servers + refuse to issue an DHCP lease if 'secs' is set to zero */ + r = sd_event_now(client->event, clock_boottime_or_monotonic(), &time_now); + if (r < 0) + return r; + assert(time_now >= client->start_time); + + /* seconds between sending first and last DISCOVER + * must always be strictly positive to deal with broken servers */ + secs = ((time_now - client->start_time) / USEC_PER_SEC) ? : 1; + packet->dhcp.secs = htobe16(secs); + + /* RFC2132 section 4.1 + A client that cannot receive unicast IP datagrams until its protocol + software has been configured with an IP address SHOULD set the + BROADCAST bit in the 'flags' field to 1 in any DHCPDISCOVER or + DHCPREQUEST messages that client sends. The BROADCAST bit will + provide a hint to the DHCP server and BOOTP relay agent to broadcast + any messages to the client on the client's subnet. + + Note: some interfaces needs this to be enabled, but some networks + needs this to be disabled as broadcasts are filteretd, so this + needs to be configurable */ + if (client->request_broadcast || client->arp_type != ARPHRD_ETHER) + packet->dhcp.flags = htobe16(0x8000); + + /* RFC2132 section 4.1.1: + The client MUST include its hardware address in the ’chaddr’ field, if + necessary for delivery of DHCP reply messages. Non-Ethernet + interfaces will leave 'chaddr' empty and use the client identifier + instead (eg, RFC 4390 section 2.1). + */ + if (client->arp_type == ARPHRD_ETHER) + memcpy(&packet->dhcp.chaddr, &client->mac_addr, ETH_ALEN); + + /* If no client identifier exists, construct an RFC 4361-compliant one */ + if (client->client_id_len == 0) { + size_t duid_len; + + client->client_id.type = 255; + + r = dhcp_identifier_set_iaid(client->ifindex, client->mac_addr, client->mac_addr_len, + true, &client->client_id.ns.iaid); + if (r < 0) + return r; + + r = dhcp_identifier_set_duid_en(&client->client_id.ns.duid, &duid_len); + if (r < 0) + return r; + + client->client_id_len = sizeof(client->client_id.type) + sizeof(client->client_id.ns.iaid) + duid_len; + } + + /* Some DHCP servers will refuse to issue an DHCP lease if the Client + Identifier option is not set */ + if (client->client_id_len) { + r = dhcp_option_append(&packet->dhcp, optlen, &optoffset, 0, + SD_DHCP_OPTION_CLIENT_IDENTIFIER, + client->client_id_len, + &client->client_id); + if (r < 0) + return r; + } + + /* RFC2131 section 3.5: + in its initial DHCPDISCOVER or DHCPREQUEST message, a + client may provide the server with a list of specific + parameters the client is interested in. If the client + includes a list of parameters in a DHCPDISCOVER message, + it MUST include that list in any subsequent DHCPREQUEST + messages. + */ + + /* RFC7844 section 3: + MAY contain the Parameter Request List option. */ + /* NOTE: in case that there would be an option to do not send + * any PRL at all, the size should be checked before sending */ + if (client->req_opts_size > 0) { + r = dhcp_option_append(&packet->dhcp, optlen, &optoffset, 0, + SD_DHCP_OPTION_PARAMETER_REQUEST_LIST, + client->req_opts_size, client->req_opts); + if (r < 0) + return r; + } + + /* RFC2131 section 3.5: + The client SHOULD include the ’maximum DHCP message size’ option to + let the server know how large the server may make its DHCP messages. + + Note (from ConnMan): Some DHCP servers will send bigger DHCP packets + than the defined default size unless the Maximum Message Size option + is explicitly set + + RFC3442 "Requirements to Avoid Sizing Constraints": + Because a full routing table can be quite large, the standard 576 + octet maximum size for a DHCP message may be too short to contain + some legitimate Classless Static Route options. Because of this, + clients implementing the Classless Static Route option SHOULD send a + Maximum DHCP Message Size [4] option if the DHCP client's TCP/IP + stack is capable of receiving larger IP datagrams. In this case, the + client SHOULD set the value of this option to at least the MTU of the + interface that the client is configuring. The client MAY set the + value of this option higher, up to the size of the largest UDP packet + it is prepared to accept. (Note that the value specified in the + Maximum DHCP Message Size option is the total maximum packet size, + including IP and UDP headers.) + */ + /* RFC7844 section 3: + SHOULD NOT contain any other option. */ + if (!client->anonymize) { + max_size = htobe16(size); + r = dhcp_option_append(&packet->dhcp, client->mtu, &optoffset, 0, + SD_DHCP_OPTION_MAXIMUM_MESSAGE_SIZE, + 2, &max_size); + if (r < 0) + return r; + } + + *_optlen = optlen; + *_optoffset = optoffset; + *ret = TAKE_PTR(packet); + + return 0; +} + +static int client_append_fqdn_option( + DHCPMessage *message, + size_t optlen, + size_t *optoffset, + const char *fqdn) { + + uint8_t buffer[3 + DHCP_MAX_FQDN_LENGTH]; + int r; + + buffer[0] = DHCP_FQDN_FLAG_S | /* Request server to perform A RR DNS updates */ + DHCP_FQDN_FLAG_E; /* Canonical wire format */ + buffer[1] = 0; /* RCODE1 (deprecated) */ + buffer[2] = 0; /* RCODE2 (deprecated) */ + + r = dns_name_to_wire_format(fqdn, buffer + 3, sizeof(buffer) - 3, false); + if (r > 0) + r = dhcp_option_append(message, optlen, optoffset, 0, + SD_DHCP_OPTION_FQDN, 3 + r, buffer); + + return r; +} + +static int dhcp_client_send_raw( + sd_dhcp_client *client, + DHCPPacket *packet, + size_t len) { + + dhcp_packet_append_ip_headers(packet, INADDR_ANY, client->port, + INADDR_BROADCAST, DHCP_PORT_SERVER, len); + + return dhcp_network_send_raw_socket(client->fd, &client->link, + packet, len); +} + +static int client_send_discover(sd_dhcp_client *client) { + _cleanup_free_ DHCPPacket *discover = NULL; + size_t optoffset, optlen; + int r; + + assert(client); + assert(IN_SET(client->state, DHCP_STATE_INIT, DHCP_STATE_SELECTING)); + + r = client_message_init(client, &discover, DHCP_DISCOVER, + &optlen, &optoffset); + if (r < 0) + return r; + + /* the client may suggest values for the network address + and lease time in the DHCPDISCOVER message. The client may include + the ’requested IP address’ option to suggest that a particular IP + address be assigned, and may include the ’IP address lease time’ + option to suggest the lease time it would like. + */ + if (client->last_addr != INADDR_ANY) { + r = dhcp_option_append(&discover->dhcp, optlen, &optoffset, 0, + SD_DHCP_OPTION_REQUESTED_IP_ADDRESS, + 4, &client->last_addr); + if (r < 0) + return r; + } + + if (client->hostname) { + /* According to RFC 4702 "clients that send the Client FQDN option in + their messages MUST NOT also send the Host Name option". Just send + one of the two depending on the hostname type. + */ + if (dns_name_is_single_label(client->hostname)) { + /* it is unclear from RFC 2131 if client should send hostname in + DHCPDISCOVER but dhclient does and so we do as well + */ + r = dhcp_option_append(&discover->dhcp, optlen, &optoffset, 0, + SD_DHCP_OPTION_HOST_NAME, + strlen(client->hostname), client->hostname); + } else + r = client_append_fqdn_option(&discover->dhcp, optlen, &optoffset, + client->hostname); + if (r < 0) + return r; + } + + if (client->vendor_class_identifier) { + r = dhcp_option_append(&discover->dhcp, optlen, &optoffset, 0, + SD_DHCP_OPTION_VENDOR_CLASS_IDENTIFIER, + strlen(client->vendor_class_identifier), + client->vendor_class_identifier); + if (r < 0) + return r; + } + + if (client->user_class) { + r = dhcp_option_append(&discover->dhcp, optlen, &optoffset, 0, + SD_DHCP_OPTION_USER_CLASS, + strv_length(client->user_class), + client->user_class); + if (r < 0) + return r; + } + + r = dhcp_option_append(&discover->dhcp, optlen, &optoffset, 0, + SD_DHCP_OPTION_END, 0, NULL); + if (r < 0) + return r; + + /* We currently ignore: + The client SHOULD wait a random time between one and ten seconds to + desynchronize the use of DHCP at startup. + */ + r = dhcp_client_send_raw(client, discover, sizeof(DHCPPacket) + optoffset); + if (r < 0) + return r; + + log_dhcp_client(client, "DISCOVER"); + + return 0; +} + +static int client_send_request(sd_dhcp_client *client) { + _cleanup_free_ DHCPPacket *request = NULL; + size_t optoffset, optlen; + int r; + + assert(client); + + r = client_message_init(client, &request, DHCP_REQUEST, &optlen, &optoffset); + if (r < 0) + return r; + + switch (client->state) { + /* See RFC2131 section 4.3.2 (note that there is a typo in the RFC, + SELECTING should be REQUESTING) + */ + + case DHCP_STATE_REQUESTING: + /* Client inserts the address of the selected server in ’server + identifier’, ’ciaddr’ MUST be zero, ’requested IP address’ MUST be + filled in with the yiaddr value from the chosen DHCPOFFER. + */ + + r = dhcp_option_append(&request->dhcp, optlen, &optoffset, 0, + SD_DHCP_OPTION_SERVER_IDENTIFIER, + 4, &client->lease->server_address); + if (r < 0) + return r; + + r = dhcp_option_append(&request->dhcp, optlen, &optoffset, 0, + SD_DHCP_OPTION_REQUESTED_IP_ADDRESS, + 4, &client->lease->address); + if (r < 0) + return r; + + break; + + case DHCP_STATE_INIT_REBOOT: + /* ’server identifier’ MUST NOT be filled in, ’requested IP address’ + option MUST be filled in with client’s notion of its previously + assigned address. ’ciaddr’ MUST be zero. + */ + r = dhcp_option_append(&request->dhcp, optlen, &optoffset, 0, + SD_DHCP_OPTION_REQUESTED_IP_ADDRESS, + 4, &client->last_addr); + if (r < 0) + return r; + break; + + case DHCP_STATE_RENEWING: + /* ’server identifier’ MUST NOT be filled in, ’requested IP address’ + option MUST NOT be filled in, ’ciaddr’ MUST be filled in with + client’s IP address. + */ + + case DHCP_STATE_REBINDING: + /* ’server identifier’ MUST NOT be filled in, ’requested IP address’ + option MUST NOT be filled in, ’ciaddr’ MUST be filled in with + client’s IP address. + + This message MUST be broadcast to the 0xffffffff IP broadcast address. + */ + request->dhcp.ciaddr = client->lease->address; + + break; + + case DHCP_STATE_INIT: + case DHCP_STATE_SELECTING: + case DHCP_STATE_REBOOTING: + case DHCP_STATE_BOUND: + case DHCP_STATE_STOPPED: + return -EINVAL; + } + + if (client->hostname) { + if (dns_name_is_single_label(client->hostname)) + r = dhcp_option_append(&request->dhcp, optlen, &optoffset, 0, + SD_DHCP_OPTION_HOST_NAME, + strlen(client->hostname), client->hostname); + else + r = client_append_fqdn_option(&request->dhcp, optlen, &optoffset, + client->hostname); + if (r < 0) + return r; + } + + if (client->vendor_class_identifier) { + r = dhcp_option_append(&request->dhcp, optlen, &optoffset, 0, + SD_DHCP_OPTION_VENDOR_CLASS_IDENTIFIER, + strlen(client->vendor_class_identifier), + client->vendor_class_identifier); + if (r < 0) + return r; + } + + r = dhcp_option_append(&request->dhcp, optlen, &optoffset, 0, + SD_DHCP_OPTION_END, 0, NULL); + if (r < 0) + return r; + + if (client->state == DHCP_STATE_RENEWING) { + r = dhcp_network_send_udp_socket(client->fd, + client->lease->server_address, + DHCP_PORT_SERVER, + &request->dhcp, + sizeof(DHCPMessage) + optoffset); + } else { + r = dhcp_client_send_raw(client, request, sizeof(DHCPPacket) + optoffset); + } + if (r < 0) + return r; + + switch (client->state) { + + case DHCP_STATE_REQUESTING: + log_dhcp_client(client, "REQUEST (requesting)"); + break; + + case DHCP_STATE_INIT_REBOOT: + log_dhcp_client(client, "REQUEST (init-reboot)"); + break; + + case DHCP_STATE_RENEWING: + log_dhcp_client(client, "REQUEST (renewing)"); + break; + + case DHCP_STATE_REBINDING: + log_dhcp_client(client, "REQUEST (rebinding)"); + break; + + default: + log_dhcp_client(client, "REQUEST (invalid)"); + break; + } + + return 0; +} + +static int client_start(sd_dhcp_client *client); + +static int client_timeout_resend( + sd_event_source *s, + uint64_t usec, + void *userdata) { + + sd_dhcp_client *client = userdata; + DHCP_CLIENT_DONT_DESTROY(client); + usec_t next_timeout = 0; + uint64_t time_now; + uint32_t time_left; + int r; + + assert(s); + assert(client); + assert(client->event); + + r = sd_event_now(client->event, clock_boottime_or_monotonic(), &time_now); + if (r < 0) + goto error; + + switch (client->state) { + + case DHCP_STATE_RENEWING: + + time_left = (client->lease->t2 - client->lease->t1) / 2; + if (time_left < 60) + time_left = 60; + + next_timeout = time_now + time_left * USEC_PER_SEC; + + break; + + case DHCP_STATE_REBINDING: + + time_left = (client->lease->lifetime - client->lease->t2) / 2; + if (time_left < 60) + time_left = 60; + + next_timeout = time_now + time_left * USEC_PER_SEC; + break; + + case DHCP_STATE_REBOOTING: + /* start over as we did not receive a timely ack or nak */ + r = client_initialize(client); + if (r < 0) + goto error; + + r = client_start(client); + if (r < 0) + goto error; + else { + log_dhcp_client(client, "REBOOTED"); + return 0; + } + + case DHCP_STATE_INIT: + case DHCP_STATE_INIT_REBOOT: + case DHCP_STATE_SELECTING: + case DHCP_STATE_REQUESTING: + case DHCP_STATE_BOUND: + + if (client->attempt < 64) + client->attempt *= 2; + + next_timeout = time_now + (client->attempt - 1) * USEC_PER_SEC; + + break; + + case DHCP_STATE_STOPPED: + r = -EINVAL; + goto error; + } + + next_timeout += (random_u32() & 0x1fffff); + + r = event_reset_time(client->event, &client->timeout_resend, + clock_boottime_or_monotonic(), + next_timeout, 10 * USEC_PER_MSEC, + client_timeout_resend, client, + client->event_priority, "dhcp4-resend-timer", true); + if (r < 0) + goto error; + + switch (client->state) { + case DHCP_STATE_INIT: + r = client_send_discover(client); + if (r >= 0) { + client->state = DHCP_STATE_SELECTING; + client->attempt = 1; + } else { + if (client->attempt >= 64) + goto error; + } + + break; + + case DHCP_STATE_SELECTING: + r = client_send_discover(client); + if (r < 0 && client->attempt >= 64) + goto error; + + break; + + case DHCP_STATE_INIT_REBOOT: + case DHCP_STATE_REQUESTING: + case DHCP_STATE_RENEWING: + case DHCP_STATE_REBINDING: + r = client_send_request(client); + if (r < 0 && client->attempt >= 64) + goto error; + + if (client->state == DHCP_STATE_INIT_REBOOT) + client->state = DHCP_STATE_REBOOTING; + + client->request_sent = time_now; + + break; + + case DHCP_STATE_REBOOTING: + case DHCP_STATE_BOUND: + + break; + + case DHCP_STATE_STOPPED: + r = -EINVAL; + goto error; + } + + return 0; + +error: + client_stop(client, r); + + /* Errors were dealt with when stopping the client, don't spill + errors into the event loop handler */ + return 0; +} + +static int client_initialize_io_events( + sd_dhcp_client *client, + sd_event_io_handler_t io_callback) { + + int r; + + assert(client); + assert(client->event); + + r = sd_event_add_io(client->event, &client->receive_message, + client->fd, EPOLLIN, io_callback, + client); + if (r < 0) + goto error; + + r = sd_event_source_set_priority(client->receive_message, + client->event_priority); + if (r < 0) + goto error; + + r = sd_event_source_set_description(client->receive_message, "dhcp4-receive-message"); + if (r < 0) + goto error; + +error: + if (r < 0) + client_stop(client, r); + + return 0; +} + +static int client_initialize_time_events(sd_dhcp_client *client) { + uint64_t usec = 0; + int r; + + assert(client); + assert(client->event); + + if (client->start_delay) { + assert_se(sd_event_now(client->event, clock_boottime_or_monotonic(), &usec) >= 0); + usec += client->start_delay; + } + + r = event_reset_time(client->event, &client->timeout_resend, + clock_boottime_or_monotonic(), + usec, 0, + client_timeout_resend, client, + client->event_priority, "dhcp4-resend-timer", true); + if (r < 0) + client_stop(client, r); + + return 0; + +} + +static int client_initialize_events(sd_dhcp_client *client, sd_event_io_handler_t io_callback) { + client_initialize_io_events(client, io_callback); + client_initialize_time_events(client); + + return 0; +} + +static int client_start_delayed(sd_dhcp_client *client) { + int r; + + assert_return(client, -EINVAL); + assert_return(client->event, -EINVAL); + assert_return(client->ifindex > 0, -EINVAL); + assert_return(client->fd < 0, -EBUSY); + assert_return(client->xid == 0, -EINVAL); + assert_return(IN_SET(client->state, DHCP_STATE_INIT, DHCP_STATE_INIT_REBOOT), -EBUSY); + + client->xid = random_u32(); + + r = dhcp_network_bind_raw_socket(client->ifindex, &client->link, + client->xid, client->mac_addr, + client->mac_addr_len, client->arp_type, client->port); + if (r < 0) { + client_stop(client, r); + return r; + } + client->fd = r; + + if (IN_SET(client->state, DHCP_STATE_INIT, DHCP_STATE_INIT_REBOOT)) + client->start_time = now(clock_boottime_or_monotonic()); + + return client_initialize_events(client, client_receive_message_raw); +} + +static int client_start(sd_dhcp_client *client) { + client->start_delay = 0; + return client_start_delayed(client); +} + +static int client_timeout_expire(sd_event_source *s, uint64_t usec, void *userdata) { + sd_dhcp_client *client = userdata; + DHCP_CLIENT_DONT_DESTROY(client); + + log_dhcp_client(client, "EXPIRED"); + + client_notify(client, SD_DHCP_CLIENT_EVENT_EXPIRED); + + /* lease was lost, start over if not freed or stopped in callback */ + if (client->state != DHCP_STATE_STOPPED) { + client_initialize(client); + client_start(client); + } + + return 0; +} + +static int client_timeout_t2(sd_event_source *s, uint64_t usec, void *userdata) { + sd_dhcp_client *client = userdata; + DHCP_CLIENT_DONT_DESTROY(client); + int r; + + assert(client); + + client->receive_message = sd_event_source_unref(client->receive_message); + client->fd = asynchronous_close(client->fd); + + client->state = DHCP_STATE_REBINDING; + client->attempt = 1; + + r = dhcp_network_bind_raw_socket(client->ifindex, &client->link, + client->xid, client->mac_addr, + client->mac_addr_len, client->arp_type, + client->port); + if (r < 0) { + client_stop(client, r); + return 0; + } + client->fd = r; + + return client_initialize_events(client, client_receive_message_raw); +} + +static int client_timeout_t1(sd_event_source *s, uint64_t usec, void *userdata) { + sd_dhcp_client *client = userdata; + DHCP_CLIENT_DONT_DESTROY(client); + + client->state = DHCP_STATE_RENEWING; + client->attempt = 1; + + return client_initialize_time_events(client); +} + +static int client_handle_offer(sd_dhcp_client *client, DHCPMessage *offer, size_t len) { + _cleanup_(sd_dhcp_lease_unrefp) sd_dhcp_lease *lease = NULL; + int r; + + r = dhcp_lease_new(&lease); + if (r < 0) + return r; + + if (client->client_id_len) { + r = dhcp_lease_set_client_id(lease, + (uint8_t *) &client->client_id, + client->client_id_len); + if (r < 0) + return r; + } + + r = dhcp_option_parse(offer, len, dhcp_lease_parse_options, lease, NULL); + if (r != DHCP_OFFER) { + log_dhcp_client(client, "received message was not an OFFER, ignoring"); + return -ENOMSG; + } + + lease->next_server = offer->siaddr; + lease->address = offer->yiaddr; + + if (lease->address == 0 || + lease->server_address == 0 || + lease->lifetime == 0) { + log_dhcp_client(client, "received lease lacks address, server address or lease lifetime, ignoring"); + return -ENOMSG; + } + + if (!lease->have_subnet_mask) { + r = dhcp_lease_set_default_subnet_mask(lease); + if (r < 0) { + log_dhcp_client(client, + "received lease lacks subnet mask, " + "and a fallback one cannot be generated, ignoring"); + return -ENOMSG; + } + } + + sd_dhcp_lease_unref(client->lease); + client->lease = TAKE_PTR(lease); + + log_dhcp_client(client, "OFFER"); + + return 0; +} + +static int client_handle_forcerenew(sd_dhcp_client *client, DHCPMessage *force, size_t len) { + int r; + + r = dhcp_option_parse(force, len, NULL, NULL, NULL); + if (r != DHCP_FORCERENEW) + return -ENOMSG; + + log_dhcp_client(client, "FORCERENEW"); + + return 0; +} + +static int client_handle_ack(sd_dhcp_client *client, DHCPMessage *ack, size_t len) { + _cleanup_(sd_dhcp_lease_unrefp) sd_dhcp_lease *lease = NULL; + _cleanup_free_ char *error_message = NULL; + int r; + + r = dhcp_lease_new(&lease); + if (r < 0) + return r; + + if (client->client_id_len) { + r = dhcp_lease_set_client_id(lease, + (uint8_t *) &client->client_id, + client->client_id_len); + if (r < 0) + return r; + } + + r = dhcp_option_parse(ack, len, dhcp_lease_parse_options, lease, &error_message); + if (r == DHCP_NAK) { + log_dhcp_client(client, "NAK: %s", strna(error_message)); + return -EADDRNOTAVAIL; + } + + if (r != DHCP_ACK) { + log_dhcp_client(client, "received message was not an ACK, ignoring"); + return -ENOMSG; + } + + lease->next_server = ack->siaddr; + + lease->address = ack->yiaddr; + + if (lease->address == INADDR_ANY || + lease->server_address == INADDR_ANY || + lease->lifetime == 0) { + log_dhcp_client(client, "received lease lacks address, server " + "address or lease lifetime, ignoring"); + return -ENOMSG; + } + + if (lease->subnet_mask == INADDR_ANY) { + r = dhcp_lease_set_default_subnet_mask(lease); + if (r < 0) { + log_dhcp_client(client, + "received lease lacks subnet mask, " + "and a fallback one cannot be generated, ignoring"); + return -ENOMSG; + } + } + + r = SD_DHCP_CLIENT_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 = SD_DHCP_CLIENT_EVENT_IP_CHANGE; + } else + r = SD_DHCP_CLIENT_EVENT_RENEW; + + client->lease = sd_dhcp_lease_unref(client->lease); + } + + client->lease = TAKE_PTR(lease); + + log_dhcp_client(client, "ACK"); + + return r; +} + +static uint64_t client_compute_timeout(sd_dhcp_client *client, uint32_t lifetime, double factor) { + assert(client); + assert(client->request_sent); + assert(lifetime > 0); + + if (lifetime > 3) + lifetime -= 3; + else + lifetime = 0; + + return client->request_sent + (lifetime * USEC_PER_SEC * factor) + + + (random_u32() & 0x1fffff); +} + +static int client_set_lease_timeouts(sd_dhcp_client *client) { + usec_t time_now; + uint64_t lifetime_timeout; + uint64_t t2_timeout; + uint64_t t1_timeout; + char time_string[FORMAT_TIMESPAN_MAX]; + int r; + + assert(client); + assert(client->event); + assert(client->lease); + assert(client->lease->lifetime); + + /* don't set timers for infinite leases */ + if (client->lease->lifetime == 0xffffffff) { + (void) event_source_disable(client->timeout_t1); + (void) event_source_disable(client->timeout_t2); + (void) event_source_disable(client->timeout_expire); + + return 0; + } + + r = sd_event_now(client->event, clock_boottime_or_monotonic(), &time_now); + if (r < 0) + return r; + assert(client->request_sent <= time_now); + + /* convert the various timeouts from relative (secs) to absolute (usecs) */ + lifetime_timeout = client_compute_timeout(client, client->lease->lifetime, 1); + if (client->lease->t1 > 0 && client->lease->t2 > 0) { + /* both T1 and T2 are given */ + if (client->lease->t1 < client->lease->t2 && + client->lease->t2 < client->lease->lifetime) { + /* they are both valid */ + t2_timeout = client_compute_timeout(client, client->lease->t2, 1); + t1_timeout = client_compute_timeout(client, client->lease->t1, 1); + } else { + /* discard both */ + t2_timeout = client_compute_timeout(client, client->lease->lifetime, 7.0 / 8.0); + client->lease->t2 = (client->lease->lifetime * 7) / 8; + t1_timeout = client_compute_timeout(client, client->lease->lifetime, 0.5); + client->lease->t1 = client->lease->lifetime / 2; + } + } else if (client->lease->t2 > 0 && client->lease->t2 < client->lease->lifetime) { + /* only T2 is given, and it is valid */ + t2_timeout = client_compute_timeout(client, client->lease->t2, 1); + t1_timeout = client_compute_timeout(client, client->lease->lifetime, 0.5); + client->lease->t1 = client->lease->lifetime / 2; + if (t2_timeout <= t1_timeout) { + /* the computed T1 would be invalid, so discard T2 */ + t2_timeout = client_compute_timeout(client, client->lease->lifetime, 7.0 / 8.0); + client->lease->t2 = (client->lease->lifetime * 7) / 8; + } + } else if (client->lease->t1 > 0 && client->lease->t1 < client->lease->lifetime) { + /* only T1 is given, and it is valid */ + t1_timeout = client_compute_timeout(client, client->lease->t1, 1); + t2_timeout = client_compute_timeout(client, client->lease->lifetime, 7.0 / 8.0); + client->lease->t2 = (client->lease->lifetime * 7) / 8; + if (t2_timeout <= t1_timeout) { + /* the computed T2 would be invalid, so discard T1 */ + t2_timeout = client_compute_timeout(client, client->lease->lifetime, 0.5); + client->lease->t2 = client->lease->lifetime / 2; + } + } else { + /* fall back to the default timeouts */ + t1_timeout = client_compute_timeout(client, client->lease->lifetime, 0.5); + client->lease->t1 = client->lease->lifetime / 2; + t2_timeout = client_compute_timeout(client, client->lease->lifetime, 7.0 / 8.0); + client->lease->t2 = (client->lease->lifetime * 7) / 8; + } + + /* arm lifetime timeout */ + r = event_reset_time(client->event, &client->timeout_expire, + clock_boottime_or_monotonic(), + lifetime_timeout, 10 * USEC_PER_MSEC, + client_timeout_expire, client, + client->event_priority, "dhcp4-lifetime", true); + if (r < 0) + return r; + + log_dhcp_client(client, "lease expires in %s", + format_timespan(time_string, FORMAT_TIMESPAN_MAX, lifetime_timeout - time_now, USEC_PER_SEC)); + + /* don't arm earlier timeouts if this has already expired */ + if (lifetime_timeout <= time_now) + return 0; + + /* arm T2 timeout */ + r = event_reset_time(client->event, &client->timeout_t2, + clock_boottime_or_monotonic(), + t2_timeout, 10 * USEC_PER_MSEC, + client_timeout_t2, client, + client->event_priority, "dhcp4-t2-timeout", true); + if (r < 0) + return r; + + log_dhcp_client(client, "T2 expires in %s", + format_timespan(time_string, FORMAT_TIMESPAN_MAX, t2_timeout - time_now, USEC_PER_SEC)); + + /* don't arm earlier timeout if this has already expired */ + if (t2_timeout <= time_now) + return 0; + + /* arm T1 timeout */ + r = event_reset_time(client->event, &client->timeout_t1, + clock_boottime_or_monotonic(), + t1_timeout, 10 * USEC_PER_MSEC, + client_timeout_t1, client, + client->event_priority, "dhcp4-t1-timer", true); + if (r < 0) + return r; + + log_dhcp_client(client, "T1 expires in %s", + format_timespan(time_string, FORMAT_TIMESPAN_MAX, t1_timeout - time_now, USEC_PER_SEC)); + + return 0; +} + +static int client_handle_message(sd_dhcp_client *client, DHCPMessage *message, int len) { + DHCP_CLIENT_DONT_DESTROY(client); + char time_string[FORMAT_TIMESPAN_MAX]; + int r = 0, notify_event = 0; + + assert(client); + assert(client->event); + assert(message); + + switch (client->state) { + case DHCP_STATE_SELECTING: + + r = client_handle_offer(client, message, len); + if (r >= 0) { + + client->state = DHCP_STATE_REQUESTING; + client->attempt = 1; + + r = event_reset_time(client->event, &client->timeout_resend, + clock_boottime_or_monotonic(), + 0, 0, + client_timeout_resend, client, + client->event_priority, "dhcp4-resend-timer", true); + if (r < 0) + goto error; + } else if (r == -ENOMSG) + /* invalid message, let's ignore it */ + return 0; + + break; + + case DHCP_STATE_REBOOTING: + case DHCP_STATE_REQUESTING: + case DHCP_STATE_RENEWING: + case DHCP_STATE_REBINDING: + + r = client_handle_ack(client, message, len); + if (r >= 0) { + client->start_delay = 0; + (void) event_source_disable(client->timeout_resend); + client->receive_message = + sd_event_source_unref(client->receive_message); + client->fd = asynchronous_close(client->fd); + + if (IN_SET(client->state, DHCP_STATE_REQUESTING, + DHCP_STATE_REBOOTING)) + notify_event = SD_DHCP_CLIENT_EVENT_IP_ACQUIRE; + else if (r != SD_DHCP_CLIENT_EVENT_IP_ACQUIRE) + notify_event = r; + + client->state = DHCP_STATE_BOUND; + client->attempt = 1; + + client->last_addr = client->lease->address; + + r = client_set_lease_timeouts(client); + if (r < 0) { + log_dhcp_client(client, "could not set lease timeouts"); + goto error; + } + + r = dhcp_network_bind_udp_socket(client->ifindex, client->lease->address, client->port); + if (r < 0) { + log_dhcp_client(client, "could not bind UDP socket"); + goto error; + } + + client->fd = r; + + client_initialize_io_events(client, client_receive_message_udp); + + if (notify_event) { + client_notify(client, notify_event); + if (client->state == DHCP_STATE_STOPPED) + return 0; + } + + } else if (r == -EADDRNOTAVAIL) { + /* got a NAK, let's restart the client */ + client_notify(client, SD_DHCP_CLIENT_EVENT_EXPIRED); + + r = client_initialize(client); + if (r < 0) + goto error; + + r = client_start_delayed(client); + if (r < 0) + goto error; + + log_dhcp_client(client, "REBOOT in %s", format_timespan(time_string, FORMAT_TIMESPAN_MAX, + client->start_delay, USEC_PER_SEC)); + + client->start_delay = CLAMP(client->start_delay * 2, + RESTART_AFTER_NAK_MIN_USEC, RESTART_AFTER_NAK_MAX_USEC); + + return 0; + } else if (r == -ENOMSG) + /* invalid message, let's ignore it */ + return 0; + + break; + + case DHCP_STATE_BOUND: + r = client_handle_forcerenew(client, message, len); + if (r >= 0) { + r = client_timeout_t1(NULL, 0, client); + if (r < 0) + goto error; + } else if (r == -ENOMSG) + /* invalid message, let's ignore it */ + return 0; + + break; + + case DHCP_STATE_INIT: + case DHCP_STATE_INIT_REBOOT: + + break; + + case DHCP_STATE_STOPPED: + r = -EINVAL; + goto error; + } + +error: + if (r < 0) + client_stop(client, r); + + return r; +} + +static int client_receive_message_udp( + sd_event_source *s, + int fd, + uint32_t revents, + void *userdata) { + + sd_dhcp_client *client = userdata; + _cleanup_free_ DHCPMessage *message = NULL; + const struct ether_addr zero_mac = {}; + const struct ether_addr *expected_chaddr = NULL; + uint8_t expected_hlen = 0; + ssize_t len, buflen; + + assert(s); + assert(client); + + buflen = next_datagram_size_fd(fd); + if (buflen < 0) + return buflen; + + message = malloc0(buflen); + if (!message) + return -ENOMEM; + + len = recv(fd, message, buflen, 0); + if (len < 0) { + if (IN_SET(errno, EAGAIN, EINTR)) + return 0; + + return log_dhcp_client_errno(client, errno, + "Could not receive message from UDP socket: %m"); + } + if ((size_t) len < sizeof(DHCPMessage)) { + log_dhcp_client(client, "Too small to be a DHCP message: ignoring"); + return 0; + } + + if (be32toh(message->magic) != DHCP_MAGIC_COOKIE) { + log_dhcp_client(client, "Not a DHCP message: ignoring"); + return 0; + } + + if (message->op != BOOTREPLY) { + log_dhcp_client(client, "Not a BOOTREPLY message: ignoring"); + return 0; + } + + if (message->htype != client->arp_type) { + log_dhcp_client(client, "Packet type does not match client type"); + return 0; + } + + if (client->arp_type == ARPHRD_ETHER) { + expected_hlen = ETH_ALEN; + expected_chaddr = (const struct ether_addr *) &client->mac_addr; + } else { + /* Non-Ethernet links expect zero chaddr */ + expected_hlen = 0; + expected_chaddr = &zero_mac; + } + + if (message->hlen != expected_hlen) { + log_dhcp_client(client, "Unexpected packet hlen %d", message->hlen); + return 0; + } + + if (memcmp(&message->chaddr[0], expected_chaddr, ETH_ALEN)) { + log_dhcp_client(client, "Received chaddr does not match expected: ignoring"); + return 0; + } + + if (client->state != DHCP_STATE_BOUND && + be32toh(message->xid) != client->xid) { + /* in BOUND state, we may receive FORCERENEW with xid set by server, + so ignore the xid in this case */ + log_dhcp_client(client, "Received xid (%u) does not match expected (%u): ignoring", + be32toh(message->xid), client->xid); + return 0; + } + + return client_handle_message(client, message, len); +} + +static int client_receive_message_raw( + sd_event_source *s, + int fd, + uint32_t revents, + void *userdata) { + + sd_dhcp_client *client = userdata; + _cleanup_free_ DHCPPacket *packet = NULL; + uint8_t cmsgbuf[CMSG_LEN(sizeof(struct tpacket_auxdata))]; + struct iovec iov = {}; + struct msghdr msg = { + .msg_iov = &iov, + .msg_iovlen = 1, + .msg_control = cmsgbuf, + .msg_controllen = sizeof(cmsgbuf), + }; + struct cmsghdr *cmsg; + bool checksum = true; + ssize_t buflen, len; + int r; + + assert(s); + assert(client); + + buflen = next_datagram_size_fd(fd); + if (buflen < 0) + return buflen; + + packet = malloc0(buflen); + if (!packet) + return -ENOMEM; + + iov = IOVEC_MAKE(packet, buflen); + + len = recvmsg(fd, &msg, 0); + if (len < 0) { + if (IN_SET(errno, EAGAIN, EINTR)) + return 0; + + return log_dhcp_client_errno(client, errno, + "Could not receive message from raw socket: %m"); + } else if ((size_t)len < sizeof(DHCPPacket)) + return 0; + + CMSG_FOREACH(cmsg, &msg) + if (cmsg->cmsg_level == SOL_PACKET && + cmsg->cmsg_type == PACKET_AUXDATA && + cmsg->cmsg_len == CMSG_LEN(sizeof(struct tpacket_auxdata))) { + struct tpacket_auxdata *aux = (struct tpacket_auxdata*)CMSG_DATA(cmsg); + + checksum = !(aux->tp_status & TP_STATUS_CSUMNOTREADY); + break; + } + + r = dhcp_packet_verify_headers(packet, len, checksum, client->port); + if (r < 0) + return 0; + + len -= DHCP_IP_UDP_SIZE; + + return client_handle_message(client, &packet->dhcp, len); +} + +int sd_dhcp_client_start(sd_dhcp_client *client) { + int r; + + assert_return(client, -EINVAL); + + r = client_initialize(client); + if (r < 0) + return r; + + /* RFC7844 section 3.3: + SHOULD perform a complete four-way handshake, starting with a + DHCPDISCOVER, to obtain a new address lease. If the client can + ascertain that this is exactly the same network to which it was + previously connected, and if the link-layer address did not change, + the client MAY issue a DHCPREQUEST to try to reclaim the current + address. */ + if (client->last_addr && !client->anonymize) + client->state = DHCP_STATE_INIT_REBOOT; + + r = client_start(client); + if (r >= 0) + log_dhcp_client(client, "STARTED on ifindex %i", client->ifindex); + + return r; +} + +int sd_dhcp_client_stop(sd_dhcp_client *client) { + DHCP_CLIENT_DONT_DESTROY(client); + + assert_return(client, -EINVAL); + + client_stop(client, SD_DHCP_CLIENT_EVENT_STOP); + client->state = DHCP_STATE_STOPPED; + + return 0; +} + +int sd_dhcp_client_attach_event(sd_dhcp_client *client, sd_event *event, int64_t priority) { + int r; + + assert_return(client, -EINVAL); + assert_return(!client->event, -EBUSY); + + if (event) + client->event = sd_event_ref(event); + else { + r = sd_event_default(&client->event); + if (r < 0) + return 0; + } + + client->event_priority = priority; + + return 0; +} + +int sd_dhcp_client_detach_event(sd_dhcp_client *client) { + assert_return(client, -EINVAL); + + client->event = sd_event_unref(client->event); + + return 0; +} + +sd_event *sd_dhcp_client_get_event(sd_dhcp_client *client) { + assert_return(client, NULL); + + return client->event; +} + +static sd_dhcp_client *dhcp_client_free(sd_dhcp_client *client) { + assert(client); + + log_dhcp_client(client, "FREE"); + + 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_initialize(client); + + sd_dhcp_client_detach_event(client); + + sd_dhcp_lease_unref(client->lease); + + free(client->req_opts); + free(client->hostname); + free(client->vendor_class_identifier); + client->user_class = strv_free(client->user_class); + return mfree(client); +} + +DEFINE_TRIVIAL_REF_UNREF_FUNC(sd_dhcp_client, sd_dhcp_client, dhcp_client_free); + +int sd_dhcp_client_new(sd_dhcp_client **ret, int anonymize) { + _cleanup_(sd_dhcp_client_unrefp) sd_dhcp_client *client = NULL; + + assert_return(ret, -EINVAL); + + client = new(sd_dhcp_client, 1); + if (!client) + return -ENOMEM; + + *client = (sd_dhcp_client) { + .n_ref = 1, + .state = DHCP_STATE_INIT, + .ifindex = -1, + .fd = -1, + .attempt = 1, + .mtu = DHCP_DEFAULT_MIN_SIZE, + .port = DHCP_PORT_CLIENT, + .anonymize = !!anonymize, + }; + /* NOTE: this could be moved to a function. */ + if (anonymize) { + client->req_opts_size = ELEMENTSOF(default_req_opts_anonymize); + client->req_opts = memdup(default_req_opts_anonymize, client->req_opts_size); + } else { + client->req_opts_size = ELEMENTSOF(default_req_opts); + client->req_opts = memdup(default_req_opts, client->req_opts_size); + } + if (!client->req_opts) + return -ENOMEM; + + *ret = TAKE_PTR(client); + + return 0; +} |