diff options
Diffstat (limited to 'src/libsystemd-network/sd-dhcp-client.c')
| -rw-r--r-- | src/libsystemd-network/sd-dhcp-client.c | 2222 |
1 files changed, 2222 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..b755c12 --- /dev/null +++ b/src/libsystemd-network/sd-dhcp-client.c @@ -0,0 +1,2222 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ +/*** + 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 <sys/ioctl.h> +#include <linux/if_infiniband.h> + +#include "sd-dhcp-client.h" + +#include "alloc-util.h" +#include "dhcp-identifier.h" +#include "dhcp-internal.h" +#include "dhcp-lease-internal.h" +#include "dhcp-protocol.h" +#include "dns-domain.h" +#include "ether-addr-util.h" +#include "event-util.h" +#include "fd-util.h" +#include "hostname-util.h" +#include "io-util.h" +#include "memory-util.h" +#include "network-common.h" +#include "random-util.h" +#include "set.h" +#include "sort-util.h" +#include "string-util.h" +#include "strv.h" +#include "time-util.h" +#include "utf8.h" +#include "web-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) + +#define TRANSIENT_FAILURE_ATTEMPTS 3 /* Arbitrary limit: how many attempts are considered enough to report + * transient failure. */ + +typedef struct sd_dhcp_client_id { + 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_ sd_dhcp_client_id; + +struct sd_dhcp_client { + unsigned n_ref; + + DHCPState state; + sd_event *event; + int event_priority; + sd_event_source *timeout_resend; + int ifindex; + char *ifname; + int fd; + uint16_t port; + union sockaddr_union link; + sd_event_source *receive_message; + bool request_broadcast; + Set *req_opts; + bool anonymize; + be32_t last_addr; + struct hw_addr_data hw_addr; + struct hw_addr_data bcast_addr; + uint16_t arp_type; + sd_dhcp_client_id client_id; + size_t client_id_len; + char *hostname; + char *vendor_class_identifier; + char *mudurl; + char **user_class; + uint32_t mtu; + uint32_t fallback_lease_lifetime; + uint32_t xid; + usec_t start_time; + usec_t t1_time; + usec_t t2_time; + usec_t expire_time; + uint64_t attempt; + uint64_t max_attempts; + OrderedHashmap *extra_options; + OrderedHashmap *vendor_options; + 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; + int ip_service_type; + + /* Ignore ifindex when generating iaid. See dhcp_identifier_set_iaid(). */ + bool test_mode; +}; + +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_DISCOVERY, /* 31 */ + SD_DHCP_OPTION_STATIC_ROUTE, /* 33 */ + SD_DHCP_OPTION_VENDOR_SPECIFIC, /* 43 */ + SD_DHCP_OPTION_NETBIOS_NAME_SERVER, /* 44 */ + SD_DHCP_OPTION_NETBIOS_NODE_TYPE, /* 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_id_to_string(const void *data, size_t len, char **ret) { + const sd_dhcp_client_id *client_id = data; + _cleanup_free_ char *t = NULL; + int r = 0; + + assert_return(data, -EINVAL); + assert_return(len >= 1, -EINVAL); + assert_return(ret, -EINVAL); + + len -= 1; + if (len > MAX_CLIENT_ID_LEN) + return -EINVAL; + + switch (client_id->type) { + case 0: + if (utf8_is_printable((char *) client_id->gen.data, len)) + r = asprintf(&t, "%.*s", (int) len, client_id->gen.data); + else + r = asprintf(&t, "DATA"); + break; + case 1: + if (len == sizeof_field(sd_dhcp_client_id, eth)) + r = asprintf(&t, "%02x:%02x:%02x:%02x:%02x:%02x", + client_id->eth.haddr[0], + client_id->eth.haddr[1], + client_id->eth.haddr[2], + client_id->eth.haddr[3], + client_id->eth.haddr[4], + client_id->eth.haddr[5]); + else + r = asprintf(&t, "ETHER"); + break; + case 2 ... 254: + r = asprintf(&t, "ARP/LL"); + break; + case 255: + if (len < sizeof(uint32_t)) + r = asprintf(&t, "IAID/DUID"); + else { + uint32_t iaid = be32toh(client_id->ns.iaid); + /* TODO: check and stringify DUID */ + r = asprintf(&t, "IAID:0x%x/DUID", iaid); + } + break; + } + if (r < 0) + return -ENOMEM; + + *ret = TAKE_PTR(t); + return 0; +} + +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); + assert_return(!sd_dhcp_client_is_running(client), -EBUSY); + + client->request_broadcast = broadcast; + + return 0; +} + +int sd_dhcp_client_set_request_option(sd_dhcp_client *client, uint8_t option) { + assert_return(client, -EINVAL); + assert_return(!sd_dhcp_client_is_running(client), -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; + } + + return set_ensure_put(&client->req_opts, NULL, UINT8_TO_PTR(option)); +} + +int sd_dhcp_client_set_request_address( + sd_dhcp_client *client, + const struct in_addr *last_addr) { + + assert_return(client, -EINVAL); + assert_return(!sd_dhcp_client_is_running(client), -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(!sd_dhcp_client_is_running(client), -EBUSY); + assert_return(ifindex > 0, -EINVAL); + + client->ifindex = ifindex; + return 0; +} + +int sd_dhcp_client_set_ifname(sd_dhcp_client *client, const char *ifname) { + assert_return(client, -EINVAL); + assert_return(ifname, -EINVAL); + + if (!ifname_valid_full(ifname, IFNAME_VALID_ALTERNATIVE)) + return -EINVAL; + + return free_and_strdup(&client->ifname, ifname); +} + +int sd_dhcp_client_get_ifname(sd_dhcp_client *client, const char **ret) { + int r; + + assert_return(client, -EINVAL); + + r = get_ifname(client->ifindex, &client->ifname); + if (r < 0) + return r; + + if (ret) + *ret = client->ifname; + + return 0; +} + +int sd_dhcp_client_set_mac( + sd_dhcp_client *client, + const uint8_t *hw_addr, + const uint8_t *bcast_addr, + size_t addr_len, + uint16_t arp_type) { + + assert_return(client, -EINVAL); + assert_return(!sd_dhcp_client_is_running(client), -EBUSY); + assert_return(IN_SET(arp_type, ARPHRD_ETHER, ARPHRD_INFINIBAND), -EINVAL); + assert_return(hw_addr, -EINVAL); + assert_return(addr_len == (arp_type == ARPHRD_ETHER ? ETH_ALEN : INFINIBAND_ALEN), -EINVAL); + + client->arp_type = arp_type; + hw_addr_set(&client->hw_addr, hw_addr, addr_len); + hw_addr_set(&client->bcast_addr, bcast_addr, bcast_addr ? addr_len : 0); + + 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); + + 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); + } else { + *type = 0; + *data = NULL; + *data_len = 0; + } + + return 0; +} + +int sd_dhcp_client_set_client_id( + sd_dhcp_client *client, + uint8_t type, + const uint8_t *data, + size_t data_len) { + + assert_return(client, -EINVAL); + assert_return(!sd_dhcp_client_is_running(client), -EBUSY); + assert_return(data, -EINVAL); + assert_return(data_len > 0 && data_len <= MAX_CLIENT_ID_LEN, -EINVAL); + + /* For hardware types, log debug message about unexpected data length. + * + * Note that infiniband's INFINIBAND_ALEN is 20 bytes long, but only + * the 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); + + 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); + + 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, + DUIDType duid_type, + const void *duid, + size_t duid_len, + usec_t llt_time) { + + size_t len; + int r; + + assert_return(client, -EINVAL); + assert_return(!sd_dhcp_client_is_running(client), -EBUSY); + assert_return(duid_len == 0 || duid, -EINVAL); + + if (duid) { + r = dhcp_validate_duid_len(duid_type, duid_len, true); + if (r < 0) + return log_dhcp_client_errno(client, r, "Failed to validate length of DUID: %m"); + } + + 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->hw_addr, + /* legacy_unstable_byteorder = */ true, + /* use_mac = */ client->test_mode, + &client->client_id.ns.iaid); + if (r < 0) + return log_dhcp_client_errno(client, r, "Failed to set IAID: %m"); + } + } + + 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 { + r = dhcp_identifier_set_duid(duid_type, &client->hw_addr, + client->arp_type, llt_time, client->test_mode, + &client->client_id.ns.duid, &len); + if (r == -EOPNOTSUPP) + return log_dhcp_client_errno(client, r, + "Failed to set %s. MAC address is not set or " + "interface type is not supported.", + duid_type_to_string(duid_type)); + if (r < 0) + return log_dhcp_client_errno(client, r, "Failed to set %s: %m", + duid_type_to_string(duid_type)); + } + + client->client_id_len = sizeof(client->client_id.type) + len + + (iaid_append ? sizeof(client->client_id.ns.iaid) : 0); + + 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); +} + +void dhcp_client_set_test_mode(sd_dhcp_client *client, bool test_mode) { + assert(client); + + client->test_mode = test_mode; +} + +int sd_dhcp_client_set_hostname( + sd_dhcp_client *client, + const char *hostname) { + + assert_return(client, -EINVAL); + assert_return(!sd_dhcp_client_is_running(client), -EBUSY); + + /* Make sure hostnames qualify as DNS and as Linux hostnames */ + if (hostname && + !(hostname_is_valid(hostname, 0) && 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); + assert_return(!sd_dhcp_client_is_running(client), -EBUSY); + + return free_and_strdup(&client->vendor_class_identifier, vci); +} + +int sd_dhcp_client_set_mud_url( + sd_dhcp_client *client, + const char *mudurl) { + + assert_return(client, -EINVAL); + assert_return(!sd_dhcp_client_is_running(client), -EBUSY); + assert_return(mudurl, -EINVAL); + assert_return(strlen(mudurl) <= 255, -EINVAL); + assert_return(http_url_is_valid(mudurl), -EINVAL); + + return free_and_strdup(&client->mudurl, mudurl); +} + +int sd_dhcp_client_set_user_class( + sd_dhcp_client *client, + char * const *user_class) { + + char **s = NULL; + + assert_return(client, -EINVAL); + assert_return(!sd_dhcp_client_is_running(client), -EBUSY); + assert_return(!strv_isempty(user_class), -EINVAL); + + STRV_FOREACH(p, user_class) { + size_t n = strlen(*p); + + if (n > 255 || n == 0) + return -EINVAL; + } + + s = strv_copy(user_class); + if (!s) + return -ENOMEM; + + return strv_free_and_replace(client->user_class, s); +} + +int sd_dhcp_client_set_client_port( + sd_dhcp_client *client, + uint16_t port) { + + assert_return(client, -EINVAL); + assert_return(!sd_dhcp_client_is_running(client), -EBUSY); + + 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_MIN_PACKET_SIZE, -ERANGE); + + /* MTU may be changed by the acquired lease. Hence, we cannot require that the client is stopped here. + * Please do not add assertion for !sd_dhcp_client_is_running(client) here. */ + + client->mtu = mtu; + + return 0; +} + +int sd_dhcp_client_set_max_attempts(sd_dhcp_client *client, uint64_t max_attempts) { + assert_return(client, -EINVAL); + assert_return(!sd_dhcp_client_is_running(client), -EBUSY); + + client->max_attempts = max_attempts; + + return 0; +} + +int sd_dhcp_client_add_option(sd_dhcp_client *client, sd_dhcp_option *v) { + int r; + + assert_return(client, -EINVAL); + assert_return(!sd_dhcp_client_is_running(client), -EBUSY); + assert_return(v, -EINVAL); + + r = ordered_hashmap_ensure_put(&client->extra_options, &dhcp_option_hash_ops, UINT_TO_PTR(v->option), v); + if (r < 0) + return r; + + sd_dhcp_option_ref(v); + return 0; +} + +int sd_dhcp_client_add_vendor_option(sd_dhcp_client *client, sd_dhcp_option *v) { + int r; + + assert_return(client, -EINVAL); + assert_return(!sd_dhcp_client_is_running(client), -EBUSY); + assert_return(v, -EINVAL); + + r = ordered_hashmap_ensure_allocated(&client->vendor_options, &dhcp_option_hash_ops); + if (r < 0) + return -ENOMEM; + + r = ordered_hashmap_put(client->vendor_options, v, v); + if (r < 0) + return r; + + sd_dhcp_option_ref(v); + + return 1; +} + +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_SELECTING, DHCP_STATE_BOUND, DHCP_STATE_RENEWING, DHCP_STATE_REBINDING)) + return -EADDRNOTAVAIL; + + if (ret) + *ret = client->lease; + + return 0; +} + +int sd_dhcp_client_set_service_type(sd_dhcp_client *client, int type) { + assert_return(client, -EINVAL); + assert_return(!sd_dhcp_client_is_running(client), -EBUSY); + + client->ip_service_type = type; + + return 0; +} + +int sd_dhcp_client_set_fallback_lease_lifetime(sd_dhcp_client *client, uint32_t fallback_lease_lifetime) { + assert_return(client, -EINVAL); + assert_return(!sd_dhcp_client_is_running(client), -EBUSY); + assert_return(fallback_lease_lifetime > 0, -EINVAL); + + client->fallback_lease_lifetime = fallback_lease_lifetime; + + return 0; +} + +static int client_notify(sd_dhcp_client *client, int event) { + assert(client); + + if (client->callback) + return client->callback(client, event, client->userdata); + + return 0; +} + +static int client_initialize(sd_dhcp_client *client) { + assert_return(client, -EINVAL); + + client->receive_message = sd_event_source_disable_unref(client->receive_message); + + client->fd = safe_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 = 0; + + 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_errno(client, error, "STOPPED: %m"); + 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); +} + +/* RFC2131 section 4.1: + * retransmission delays should include -1 to +1 sec of random 'fuzz'. */ +#define RFC2131_RANDOM_FUZZ \ + ((int64_t)(random_u64() % (2 * USEC_PER_SEC)) - (int64_t)USEC_PER_SEC) + +/* RFC2131 section 4.1: + * for retransmission delays, timeout should start at 4s then double + * each attempt with max of 64s, with -1 to +1 sec of random 'fuzz' added. + * This assumes the first call will be using attempt 1. */ +static usec_t client_compute_request_timeout(usec_t now, uint64_t attempt) { + usec_t timeout = (UINT64_C(1) << MIN(attempt + 1, UINT64_C(6))) * USEC_PER_SEC; + + return usec_sub_signed(usec_add(now, timeout), RFC2131_RANDOM_FUZZ); +} + +/* RFC2131 section 4.4.5: + * T1 defaults to (0.5 * duration_of_lease). + * T2 defaults to (0.875 * duration_of_lease). */ +#define T1_DEFAULT(lifetime) ((lifetime) / 2) +#define T2_DEFAULT(lifetime) (((lifetime) * 7) / 8) + +/* RFC2131 section 4.4.5: + * the client SHOULD wait one-half of the remaining time until T2 (in RENEWING state) + * and one-half of the remaining lease time (in REBINDING state), down to a minimum + * of 60 seconds. + * Note that while the default T1/T2 initial times do have random 'fuzz' applied, + * the RFC sec 4.4.5 does not mention adding any fuzz to retries. */ +static usec_t client_compute_reacquisition_timeout(usec_t now, usec_t expire) { + return now + MAX(usec_sub_unsigned(expire, now) / 2, 60 * USEC_PER_SEC); +} + +static int cmp_uint8(const uint8_t *a, const uint8_t *b) { + return CMP(*a, *b); +} + +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; + 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, DHCP_RELEASE, DHCP_DECLINE)); + + 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, client->hw_addr.length, client->hw_addr.bytes, + 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, &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); + + /* RFC2131 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); + + /* 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->hw_addr, + /* legacy_unstable_byteorder = */ true, + /* use_mac = */ client->test_mode, + &client->client_id.ns.iaid); + if (r < 0) + return r; + + r = dhcp_identifier_set_duid_en(client->test_mode, &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 (!set_isempty(client->req_opts) && type != DHCP_RELEASE) { + _cleanup_free_ uint8_t *opts = NULL; + size_t n_opts, i = 0; + void *val; + + n_opts = set_size(client->req_opts); + opts = new(uint8_t, n_opts); + if (!opts) + return -ENOMEM; + + SET_FOREACH(val, client->req_opts) + opts[i++] = PTR_TO_UINT8(val); + assert(i == n_opts); + + /* For anonymizing the request, let's sort the options. */ + typesafe_qsort(opts, n_opts, cmp_uint8); + + r = dhcp_option_append(&packet->dhcp, optlen, &optoffset, 0, + SD_DHCP_OPTION_PARAMETER_REQUEST_LIST, + n_opts, 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 && IN_SET(type, DHCP_DISCOVER, DHCP_REQUEST)) { + be16_t max_size = htobe16(MIN(client->mtu - DHCP_IP_UDP_SIZE, (uint32_t) UINT16_MAX)); + r = dhcp_option_append(&packet->dhcp, optlen, &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, client->ip_service_type); + + return dhcp_network_send_raw_socket(client->fd, &client->link, + packet, len); +} + +static int client_append_common_discover_request_options(sd_dhcp_client *client, DHCPPacket *packet, size_t *optoffset, size_t optlen) { + sd_dhcp_option *j; + int r; + + assert(client); + + 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(&packet->dhcp, optlen, optoffset, 0, + SD_DHCP_OPTION_HOST_NAME, + strlen(client->hostname), client->hostname); + } else + r = client_append_fqdn_option(&packet->dhcp, optlen, optoffset, + client->hostname); + if (r < 0) + return r; + } + + if (client->vendor_class_identifier) { + r = dhcp_option_append(&packet->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->mudurl) { + r = dhcp_option_append(&packet->dhcp, optlen, optoffset, 0, + SD_DHCP_OPTION_MUD_URL, + strlen(client->mudurl), + client->mudurl); + if (r < 0) + return r; + } + + if (client->user_class) { + r = dhcp_option_append(&packet->dhcp, optlen, optoffset, 0, + SD_DHCP_OPTION_USER_CLASS, + strv_length(client->user_class), + client->user_class); + if (r < 0) + return r; + } + + ORDERED_HASHMAP_FOREACH(j, client->extra_options) { + r = dhcp_option_append(&packet->dhcp, optlen, optoffset, 0, + j->option, j->length, j->data); + if (r < 0) + return r; + } + + if (!ordered_hashmap_isempty(client->vendor_options)) { + r = dhcp_option_append( + &packet->dhcp, optlen, optoffset, 0, + SD_DHCP_OPTION_VENDOR_SPECIFIC, + ordered_hashmap_size(client->vendor_options), client->vendor_options); + if (r < 0) + return r; + } + + + return 0; +} + +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. + */ + /* RFC7844 section 3: + SHOULD NOT contain any other option. */ + if (!client->anonymize && 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; + } + + r = client_append_common_discover_request_options(client, discover, &optoffset, optlen); + 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; + } + + r = client_append_common_discover_request_options(client, request, &optoffset, optlen); + 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 = ASSERT_PTR(userdata); + DHCP_CLIENT_DONT_DESTROY(client); + usec_t next_timeout; + uint64_t time_now; + int r; + + assert(s); + assert(client->event); + + r = sd_event_now(client->event, CLOCK_BOOTTIME, &time_now); + if (r < 0) + goto error; + + switch (client->state) { + + case DHCP_STATE_RENEWING: + next_timeout = client_compute_reacquisition_timeout(time_now, client->t2_time); + break; + + case DHCP_STATE_REBINDING: + next_timeout = client_compute_reacquisition_timeout(time_now, client->expire_time); + 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; + + 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 >= client->max_attempts) + goto error; + + client->attempt++; + next_timeout = client_compute_request_timeout(time_now, client->attempt); + break; + + case DHCP_STATE_STOPPED: + r = -EINVAL; + goto error; + + default: + assert_not_reached(); + } + + r = event_reset_time(client->event, &client->timeout_resend, + CLOCK_BOOTTIME, + 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 = 0; + } else if (client->attempt >= client->max_attempts) + goto error; + + break; + + case DHCP_STATE_SELECTING: + r = client_send_discover(client); + if (r < 0 && client->attempt >= client->max_attempts) + 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 >= client->max_attempts) + 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; + } + + if (client->attempt >= TRANSIENT_FAILURE_ATTEMPTS) + client_notify(client, SD_DHCP_CLIENT_EVENT_TRANSIENT_FAILURE); + + 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 > 0) { + assert_se(sd_event_now(client->event, CLOCK_BOOTTIME, &usec) >= 0); + usec += client->start_delay; + } + + r = event_reset_time(client->event, &client->timeout_resend, + CLOCK_BOOTTIME, + 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->hw_addr, &client->bcast_addr, + 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); + + 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 = ASSERT_PTR(userdata); + DHCP_CLIENT_DONT_DESTROY(client); + int r; + + client->receive_message = sd_event_source_disable_unref(client->receive_message); + client->fd = safe_close(client->fd); + + client->state = DHCP_STATE_REBINDING; + client->attempt = 0; + + r = dhcp_network_bind_raw_socket(client->ifindex, &client->link, client->xid, + &client->hw_addr, &client->bcast_addr, + 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); + + if (client->lease) + client->state = DHCP_STATE_RENEWING; + else if (client->state != DHCP_STATE_INIT) + client->state = DHCP_STATE_INIT_REBOOT; + client->attempt = 0; + + 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->lifetime == 0 && client->fallback_lease_lifetime > 0) + lease->lifetime = client->fallback_lease_lifetime; + + 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); + + if (client_notify(client, SD_DHCP_CLIENT_EVENT_SELECTING) < 0) + return -ENOMSG; + + 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; + +#if 0 + log_dhcp_client(client, "FORCERENEW"); + + return 0; +#else + /* FIXME: Ignore FORCERENEW requests until we implement RFC3118 (Authentication for DHCP + * Messages) and/or RFC6704 (Forcerenew Nonce Authentication), as unauthenticated FORCERENEW + * requests causes a security issue (TALOS-2020-1142, CVE-2020-13529). */ + log_dhcp_client(client, "Received FORCERENEW, ignoring."); + return -ENOMSG; +#endif +} + +static bool lease_equal(const sd_dhcp_lease *a, const sd_dhcp_lease *b) { + if (a->address != b->address) + return false; + + if (a->subnet_mask != b->subnet_mask) + return false; + + if (a->router_size != b->router_size) + return false; + + for (size_t i = 0; i < a->router_size; i++) + if (a->router[i].s_addr != b->router[i].s_addr) + return false; + + return true; +} + +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 (lease_equal(client->lease, lease)) + r = SD_DHCP_CLIENT_EVENT_RENEW; + else + r = SD_DHCP_CLIENT_EVENT_IP_CHANGE; + + client->lease = sd_dhcp_lease_unref(client->lease); + } + + client->lease = TAKE_PTR(lease); + + log_dhcp_client(client, "ACK"); + + return r; +} + +static int client_set_lease_timeouts(sd_dhcp_client *client) { + usec_t time_now; + 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, &time_now); + if (r < 0) + return r; + assert(client->request_sent <= time_now); + + /* verify that 0 < t2 < lifetime */ + if (client->lease->t2 == 0 || client->lease->t2 >= client->lease->lifetime) + client->lease->t2 = T2_DEFAULT(client->lease->lifetime); + /* verify that 0 < t1 < lifetime */ + if (client->lease->t1 == 0 || client->lease->t1 >= client->lease->t2) + client->lease->t1 = T1_DEFAULT(client->lease->lifetime); + /* now, if t1 >= t2, t1 *must* be T1_DEFAULT, since the previous check + * could not evalate to false if t1 >= t2; so setting t2 to T2_DEFAULT + * guarantees t1 < t2. */ + if (client->lease->t1 >= client->lease->t2) + client->lease->t2 = T2_DEFAULT(client->lease->lifetime); + + client->expire_time = client->request_sent + client->lease->lifetime * USEC_PER_SEC; + client->t1_time = client->request_sent + client->lease->t1 * USEC_PER_SEC; + client->t2_time = client->request_sent + client->lease->t2 * USEC_PER_SEC; + + /* RFC2131 section 4.4.5: + * Times T1 and T2 SHOULD be chosen with some random "fuzz". + * Since the RFC doesn't specify here the exact 'fuzz' to use, + * we use the range from section 4.1: -1 to +1 sec. */ + client->t1_time = usec_sub_signed(client->t1_time, RFC2131_RANDOM_FUZZ); + client->t2_time = usec_sub_signed(client->t2_time, RFC2131_RANDOM_FUZZ); + + /* after fuzzing, ensure t2 is still >= t1 */ + client->t2_time = MAX(client->t1_time, client->t2_time); + + /* arm lifetime timeout */ + r = event_reset_time(client->event, &client->timeout_expire, + CLOCK_BOOTTIME, + client->expire_time, 10 * USEC_PER_MSEC, + client_timeout_expire, client, + client->event_priority, "dhcp4-lifetime", true); + if (r < 0) + return r; + + /* don't arm earlier timeouts if this has already expired */ + if (client->expire_time <= time_now) + return 0; + + log_dhcp_client(client, "lease expires in %s", + FORMAT_TIMESPAN(client->expire_time - time_now, USEC_PER_SEC)); + + /* arm T2 timeout */ + r = event_reset_time(client->event, &client->timeout_t2, + CLOCK_BOOTTIME, + client->t2_time, 10 * USEC_PER_MSEC, + client_timeout_t2, client, + client->event_priority, "dhcp4-t2-timeout", true); + if (r < 0) + return r; + + /* don't arm earlier timeout if this has already expired */ + if (client->t2_time <= time_now) + return 0; + + log_dhcp_client(client, "T2 expires in %s", + FORMAT_TIMESPAN(client->t2_time - time_now, USEC_PER_SEC)); + + /* arm T1 timeout */ + r = event_reset_time(client->event, &client->timeout_t1, + CLOCK_BOOTTIME, + client->t1_time, 10 * USEC_PER_MSEC, + client_timeout_t1, client, + client->event_priority, "dhcp4-t1-timer", true); + if (r < 0) + return r; + + if (client->t1_time > time_now) + log_dhcp_client(client, "T1 expires in %s", + FORMAT_TIMESPAN(client->t1_time - 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); + int r, notify_event; + + assert(client); + assert(client->event); + assert(message); + + switch (client->state) { + case DHCP_STATE_SELECTING: + + r = client_handle_offer(client, message, len); + if (r == -ENOMSG) + return 0; /* invalid message, let's ignore it */ + if (r < 0) + goto error; + + client->state = DHCP_STATE_REQUESTING; + client->attempt = 0; + + r = event_reset_time(client->event, &client->timeout_resend, + CLOCK_BOOTTIME, + 0, 0, + client_timeout_resend, client, + client->event_priority, "dhcp4-resend-timer", true); + 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 == -ENOMSG) + return 0; /* invalid message, let's ignore it */ + 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(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; + } + if (r < 0) + goto error; + + if (IN_SET(client->state, DHCP_STATE_REQUESTING, DHCP_STATE_REBOOTING)) + notify_event = SD_DHCP_CLIENT_EVENT_IP_ACQUIRE; + else + notify_event = r; + + client->start_delay = 0; + (void) event_source_disable(client->timeout_resend); + client->receive_message = sd_event_source_disable_unref(client->receive_message); + client->fd = safe_close(client->fd); + + client->state = DHCP_STATE_BOUND; + client->attempt = 0; + + 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, client->ip_service_type); + 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 (IN_SET(client->state, DHCP_STATE_RENEWING, DHCP_STATE_REBINDING) && + notify_event == SD_DHCP_CLIENT_EVENT_IP_ACQUIRE) + /* FIXME: hmm, maybe this is a bug... */ + log_dhcp_client(client, "client_handle_ack() returned SD_DHCP_CLIENT_EVENT_IP_ACQUIRE while DHCP client is %s the address, skipping callback.", + client->state == DHCP_STATE_RENEWING ? "renewing" : "rebinding"); + else + client_notify(client, notify_event); + break; + + case DHCP_STATE_BOUND: + r = client_handle_forcerenew(client, message, len); + if (r == -ENOMSG) + return 0; /* invalid message, let's ignore it */ + if (r < 0) + goto error; + + r = client_timeout_t1(NULL, 0, client); + break; + + case DHCP_STATE_INIT: + case DHCP_STATE_INIT_REBOOT: + r = 0; + break; + + case DHCP_STATE_STOPPED: + r = -EINVAL; + goto error; + default: + assert_not_reached(); + } + +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 = ASSERT_PTR(userdata); + _cleanup_free_ DHCPMessage *message = NULL; + const uint8_t *expected_chaddr = NULL; + uint8_t expected_hlen = 0; + ssize_t len, buflen; + + assert(s); + + buflen = next_datagram_size_fd(fd); + if (buflen < 0) { + if (ERRNO_IS_TRANSIENT(buflen) || ERRNO_IS_DISCONNECT(buflen)) + return 0; + + log_dhcp_client_errno(client, buflen, "Failed to determine datagram size to read, ignoring: %m"); + return 0; + } + + message = malloc0(buflen); + if (!message) + return -ENOMEM; + + len = recv(fd, message, buflen, 0); + if (len < 0) { + if (ERRNO_IS_TRANSIENT(errno) || ERRNO_IS_DISCONNECT(errno)) + return 0; + + log_dhcp_client_errno(client, errno, "Could not receive message from UDP socket, ignoring: %m"); + return 0; + } + 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 = client->hw_addr.bytes; + } + + if (message->hlen != expected_hlen) { + log_dhcp_client(client, "Unexpected packet hlen %d", message->hlen); + return 0; + } + + if (expected_hlen > 0 && memcmp(&message->chaddr[0], expected_chaddr, expected_hlen)) { + 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; + } + + log_dhcp_client(client, "Received message from UDP socket, processing."); + (void) client_handle_message(client, message, len); + return 0; +} + +static int client_receive_message_raw( + sd_event_source *s, + int fd, + uint32_t revents, + void *userdata) { + + sd_dhcp_client *client = ASSERT_PTR(userdata); + _cleanup_free_ DHCPPacket *packet = NULL; + CMSG_BUFFER_TYPE(CMSG_SPACE(sizeof(struct tpacket_auxdata))) control; + struct iovec iov = {}; + struct msghdr msg = { + .msg_iov = &iov, + .msg_iovlen = 1, + .msg_control = &control, + .msg_controllen = sizeof(control), + }; + struct cmsghdr *cmsg; + bool checksum = true; + ssize_t buflen, len; + int r; + + assert(s); + + buflen = next_datagram_size_fd(fd); + if (buflen < 0) { + if (ERRNO_IS_TRANSIENT(buflen) || ERRNO_IS_DISCONNECT(buflen)) + return 0; + + log_dhcp_client_errno(client, buflen, "Failed to determine datagram size to read, ignoring: %m"); + return 0; + } + + packet = malloc0(buflen); + if (!packet) + return -ENOMEM; + + iov = IOVEC_MAKE(packet, buflen); + + len = recvmsg_safe(fd, &msg, 0); + if (len < 0) { + if (ERRNO_IS_TRANSIENT(len) || ERRNO_IS_DISCONNECT(len)) + return 0; + + log_dhcp_client_errno(client, len, "Could not receive message from raw socket, ignoring: %m"); + return 0; + } + if ((size_t) len < sizeof(DHCPPacket)) + return 0; + + cmsg = cmsg_find(&msg, SOL_PACKET, PACKET_AUXDATA, CMSG_LEN(sizeof(struct tpacket_auxdata))); + if (cmsg) { + struct tpacket_auxdata *aux = (struct tpacket_auxdata*) CMSG_DATA(cmsg); + checksum = !(aux->tp_status & TP_STATUS_CSUMNOTREADY); + } + + r = dhcp_packet_verify_headers(packet, len, checksum, client->port); + if (r < 0) + return 0; + + len -= DHCP_IP_UDP_SIZE; + + log_dhcp_client(client, "Received message from RAW socket, processing."); + (void) client_handle_message(client, &packet->dhcp, len); + return 0; +} + +int sd_dhcp_client_send_renew(sd_dhcp_client *client) { + assert_return(client, -EINVAL); + assert_return(sd_dhcp_client_is_running(client), -ESTALE); + assert_return(client->fd >= 0, -EINVAL); + + if (!client->lease) + return 0; + + client->start_delay = 0; + client->attempt = 1; + client->state = DHCP_STATE_RENEWING; + + return client_initialize_time_events(client); +} + +int sd_dhcp_client_is_running(sd_dhcp_client *client) { + if (!client) + return 0; + + return !IN_SET(client->state, DHCP_STATE_INIT, DHCP_STATE_STOPPED); +} + +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_send_release(sd_dhcp_client *client) { + assert_return(client, -EINVAL); + assert_return(sd_dhcp_client_is_running(client), -ESTALE); + assert_return(client->lease, -EUNATCH); + + _cleanup_free_ DHCPPacket *release = NULL; + size_t optoffset, optlen; + int r; + + r = client_message_init(client, &release, DHCP_RELEASE, &optlen, &optoffset); + if (r < 0) + return r; + + /* Fill up release IP and MAC */ + release->dhcp.ciaddr = client->lease->address; + memcpy(&release->dhcp.chaddr, client->hw_addr.bytes, client->hw_addr.length); + + r = dhcp_option_append(&release->dhcp, optlen, &optoffset, 0, + SD_DHCP_OPTION_END, 0, NULL); + if (r < 0) + return r; + + r = dhcp_network_send_udp_socket(client->fd, + client->lease->server_address, + DHCP_PORT_SERVER, + &release->dhcp, + sizeof(DHCPMessage) + optoffset); + if (r < 0) + return r; + + log_dhcp_client(client, "RELEASE"); + + return 0; +} + +int sd_dhcp_client_send_decline(sd_dhcp_client *client) { + assert_return(client, -EINVAL); + assert_return(sd_dhcp_client_is_running(client), -ESTALE); + assert_return(client->lease, -EUNATCH); + + _cleanup_free_ DHCPPacket *release = NULL; + size_t optoffset, optlen; + int r; + + r = client_message_init(client, &release, DHCP_DECLINE, &optlen, &optoffset); + if (r < 0) + return r; + + release->dhcp.ciaddr = client->lease->address; + memcpy(&release->dhcp.chaddr, client->hw_addr.bytes, client->hw_addr.length); + + r = dhcp_option_append(&release->dhcp, optlen, &optoffset, 0, + SD_DHCP_OPTION_END, 0, NULL); + if (r < 0) + return r; + + r = dhcp_network_send_udp_socket(client->fd, + client->lease->server_address, + DHCP_PORT_SERVER, + &release->dhcp, + sizeof(DHCPMessage) + optoffset); + if (r < 0) + return r; + + log_dhcp_client(client, "DECLINE"); + + client_stop(client, SD_DHCP_CLIENT_EVENT_STOP); + + if (client->state != DHCP_STATE_STOPPED) { + r = sd_dhcp_client_start(client); + if (r < 0) + return r; + } + + return 0; +} + +int sd_dhcp_client_stop(sd_dhcp_client *client) { + if (!client) + return 0; + + DHCP_CLIENT_DONT_DESTROY(client); + + 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); + assert_return(!sd_dhcp_client_is_running(client), -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); + assert_return(!sd_dhcp_client_is_running(client), -EBUSY); + + 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) { + if (!client) + return NULL; + + log_dhcp_client(client, "FREE"); + + client_initialize(client); + + 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); + + sd_dhcp_client_detach_event(client); + + set_free(client->req_opts); + free(client->hostname); + free(client->vendor_class_identifier); + free(client->mudurl); + client->user_class = strv_free(client->user_class); + ordered_hashmap_free(client->extra_options); + ordered_hashmap_free(client->vendor_options); + free(client->ifname); + 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) { + const uint8_t *opts; + size_t n_opts; + int r; + + assert_return(ret, -EINVAL); + + _cleanup_(sd_dhcp_client_unrefp) sd_dhcp_client *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, + .mtu = DHCP_MIN_PACKET_SIZE, + .port = DHCP_PORT_CLIENT, + .anonymize = !!anonymize, + .max_attempts = UINT64_MAX, + .ip_service_type = -1, + }; + /* NOTE: this could be moved to a function. */ + if (anonymize) { + n_opts = ELEMENTSOF(default_req_opts_anonymize); + opts = default_req_opts_anonymize; + } else { + n_opts = ELEMENTSOF(default_req_opts); + opts = default_req_opts; + } + + for (size_t i = 0; i < n_opts; i++) { + r = sd_dhcp_client_set_request_option(client, opts[i]); + if (r < 0) + return r; + } + + *ret = TAKE_PTR(client); + + return 0; +} |