sd-network: add new library

This is similar to sd-login, but exposes the state of networkd rather than logind.

Include it in libsystemd-dhcp and rename it to libsystemd-network.

1 files changed, 1051 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 0000000000..1f676ccb65
--- /dev/null
+++ b/src/libsystemd-network/sd-dhcp-client.c
@@ -0,0 +1,1051 @@
+/***
+  This file is part of systemd.
+
+  Copyright (C) 2013 Intel Corporation. All rights reserved.
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <stdlib.h>
+#include <errno.h>
+#include <string.h>
+#include <stdio.h>
+#include <net/ethernet.h>
+#include <sys/param.h>
+#include <sys/ioctl.h>
+
+#include "util.h"
+#include "list.h"
+
+#include "dhcp-protocol.h"
+#include "dhcp-internal.h"
+#include "dhcp-lease-internal.h"
+#include "sd-dhcp-client.h"
+
+struct sd_dhcp_client {
+        DHCPState state;
+        sd_event *event;
+        int event_priority;
+        sd_event_source *timeout_resend;
+        int index;
+        int fd;
+        union sockaddr_union link;
+        sd_event_source *receive_message;
+        uint8_t *req_opts;
+        size_t req_opts_allocated;
+        size_t req_opts_size;
+        be32_t last_addr;
+        struct ether_addr mac_addr;
+        uint32_t xid;
+        usec_t start_time;
+        uint16_t secs;
+        unsigned int attempt;
+        usec_t request_sent;
+        sd_event_source *timeout_t1;
+        sd_event_source *timeout_t2;
+        sd_event_source *timeout_expire;
+        sd_dhcp_client_cb_t cb;
+        void *userdata;
+        sd_dhcp_lease *lease;
+};
+
+static const uint8_t default_req_opts[] = {
+        DHCP_OPTION_SUBNET_MASK,
+        DHCP_OPTION_ROUTER,
+        DHCP_OPTION_HOST_NAME,
+        DHCP_OPTION_DOMAIN_NAME,
+        DHCP_OPTION_DOMAIN_NAME_SERVER,
+        DHCP_OPTION_NTP_SERVER,
+};
+
+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);
+
+int sd_dhcp_client_set_callback(sd_dhcp_client *client, sd_dhcp_client_cb_t cb,
+                                void *userdata) {
+        assert_return(client, -EINVAL);
+
+        client->cb = cb;
+        client->userdata = userdata;
+
+        return 0;
+}
+
+int sd_dhcp_client_set_request_option(sd_dhcp_client *client, uint8_t option) {
+        size_t i;
+
+        assert_return(client, -EINVAL);
+        assert_return (client->state == DHCP_STATE_INIT, -EBUSY);
+
+        switch(option) {
+        case DHCP_OPTION_PAD:
+        case DHCP_OPTION_OVERLOAD:
+        case DHCP_OPTION_MESSAGE_TYPE:
+        case DHCP_OPTION_PARAMETER_REQUEST_LIST:
+        case DHCP_OPTION_END:
+                return -EINVAL;
+
+        default:
+                break;
+        }
+
+        for (i = 0; i < client->req_opts_size; i++)
+                if (client->req_opts[i] == option)
+                        return -EEXIST;
+
+        if (!GREEDY_REALLOC(client->req_opts, client->req_opts_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(client->state == DHCP_STATE_INIT, -EBUSY);
+
+        if (last_addr)
+                client->last_addr = last_addr->s_addr;
+        else
+                client->last_addr = INADDR_ANY;
+
+        return 0;
+}
+
+int sd_dhcp_client_set_index(sd_dhcp_client *client, int interface_index) {
+        assert_return(client, -EINVAL);
+        assert_return(client->state == DHCP_STATE_INIT, -EBUSY);
+        assert_return(interface_index >= -1, -EINVAL);
+
+        client->index = interface_index;
+
+        return 0;
+}
+
+int sd_dhcp_client_set_mac(sd_dhcp_client *client,
+                           const struct ether_addr *addr) {
+        assert_return(client, -EINVAL);
+        assert_return(client->state == DHCP_STATE_INIT, -EBUSY);
+
+        memcpy(&client->mac_addr, addr, ETH_ALEN);
+
+        return 0;
+}
+
+int sd_dhcp_client_get_lease(sd_dhcp_client *client, sd_dhcp_lease **ret) {
+        assert_return(client, -EINVAL);
+        assert_return(ret, -EINVAL);
+
+        if (client->state != DHCP_STATE_BOUND &&
+            client->state != DHCP_STATE_RENEWING &&
+            client->state != DHCP_STATE_REBINDING)
+                return -EADDRNOTAVAIL;
+
+        *ret = sd_dhcp_lease_ref(client->lease);
+
+        return 0;
+}
+
+static int client_notify(sd_dhcp_client *client, int event) {
+        if (client->cb)
+                client->cb(client, event, client->userdata);
+
+        return 0;
+}
+
+static int client_stop(sd_dhcp_client *client, int error) {
+        assert_return(client, -EINVAL);
+
+        client->receive_message =
+                sd_event_source_unref(client->receive_message);
+
+        if (client->fd >= 0)
+                close(client->fd);
+        client->fd = -1;
+
+        client->timeout_resend = sd_event_source_unref(client->timeout_resend);
+
+        client->timeout_t1 = sd_event_source_unref(client->timeout_t1);
+        client->timeout_t2 = sd_event_source_unref(client->timeout_t2);
+        client->timeout_expire = sd_event_source_unref(client->timeout_expire);
+
+        client->attempt = 1;
+
+        client_notify(client, error);
+
+        client->start_time = 0;
+        client->secs = 0;
+        client->state = DHCP_STATE_INIT;
+
+        if (client->lease)
+                client->lease = sd_dhcp_lease_unref(client->lease);
+
+        log_dhcp_client(client, "STOPPED");
+
+        return 0;
+}
+
+static int client_message_init(sd_dhcp_client *client, DHCPMessage *message,
+                               uint8_t type, uint16_t secs, uint8_t **opt,
+                               size_t *optlen) {
+        int r;
+
+        assert(secs);
+
+        r = dhcp_message_init(message, BOOTREQUEST, client->xid, type, opt,
+                              optlen);
+        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 */
+        message->secs = htobe16(secs);
+
+        memcpy(&message->chaddr, &client->mac_addr, ETH_ALEN);
+
+        if (client->state == DHCP_STATE_RENEWING ||
+            client->state == DHCP_STATE_REBINDING)
+                message->ciaddr = client->lease->address;
+
+        /* Some DHCP servers will refuse to issue an DHCP lease if the Client
+           Identifier option is not set */
+        r = dhcp_option_append(opt, optlen, DHCP_OPTION_CLIENT_IDENTIFIER,
+                               ETH_ALEN, &client->mac_addr);
+        if (r < 0)
+                return r;
+
+        if (type == DHCP_DISCOVER || type == DHCP_REQUEST) {
+                be16_t max_size;
+
+                r = dhcp_option_append(opt, optlen,
+                                       DHCP_OPTION_PARAMETER_REQUEST_LIST,
+                                       client->req_opts_size,
+                                       client->req_opts);
+                if (r < 0)
+                        return r;
+
+                /* Some DHCP servers will send bigger DHCP packets than the
+                   defined default size unless the Maximum Messge Size option
+                   is explicitely set */
+                max_size = htobe16(DHCP_IP_UDP_SIZE + DHCP_MESSAGE_SIZE +
+                                   DHCP_MIN_OPTIONS_SIZE);
+                r = dhcp_option_append(opt, optlen,
+                                       DHCP_OPTION_MAXIMUM_MESSAGE_SIZE,
+                                       2, &max_size);
+                if (r < 0)
+                        return r;
+        }
+
+        return 0;
+}
+
+static int client_send_discover(sd_dhcp_client *client, uint16_t secs) {
+        int err = 0;
+        _cleanup_free_ DHCPPacket *discover;
+        size_t optlen, len;
+        uint8_t *opt;
+
+        optlen = DHCP_MIN_OPTIONS_SIZE;
+        len = sizeof(DHCPPacket) + optlen;
+
+        discover = malloc0(len);
+
+        if (!discover)
+                return -ENOMEM;
+
+        err = client_message_init(client, &discover->dhcp, DHCP_DISCOVER,
+                                  secs, &opt, &optlen);
+        if (err < 0)
+                return err;
+
+        if (client->last_addr != INADDR_ANY) {
+                err = dhcp_option_append(&opt, &optlen,
+                                         DHCP_OPTION_REQUESTED_IP_ADDRESS,
+                                         4, &client->last_addr);
+                if (err < 0)
+                        return err;
+        }
+
+        err = dhcp_option_append(&opt, &optlen, DHCP_OPTION_END, 0, NULL);
+        if (err < 0)
+                return err;
+
+        dhcp_packet_append_ip_headers(discover, len);
+
+        err = dhcp_network_send_raw_socket(client->fd, &client->link,
+                                           discover, len);
+
+        log_dhcp_client(client, "DISCOVER");
+
+        return err;
+}
+
+static int client_send_request(sd_dhcp_client *client, uint16_t secs) {
+        _cleanup_free_ DHCPPacket *request;
+        size_t optlen, len;
+        int err;
+        uint8_t *opt;
+
+        optlen = DHCP_MIN_OPTIONS_SIZE;
+        len = sizeof(DHCPPacket) + optlen;
+
+        request = malloc0(len);
+        if (!request)
+                return -ENOMEM;
+
+        err = client_message_init(client, &request->dhcp, DHCP_REQUEST, secs,
+                                  &opt, &optlen);
+        if (err < 0)
+                return err;
+
+        if (client->state == DHCP_STATE_REQUESTING) {
+                err = dhcp_option_append(&opt, &optlen,
+                                         DHCP_OPTION_REQUESTED_IP_ADDRESS,
+                                         4, &client->lease->address);
+                if (err < 0)
+                        return err;
+
+                err = dhcp_option_append(&opt, &optlen,
+                                         DHCP_OPTION_SERVER_IDENTIFIER,
+                                         4, &client->lease->server_address);
+                if (err < 0)
+                        return err;
+        }
+
+        err = dhcp_option_append(&opt, &optlen, DHCP_OPTION_END, 0, NULL);
+        if (err < 0)
+                return err;
+
+        if (client->state == DHCP_STATE_RENEWING) {
+                err = dhcp_network_send_udp_socket(client->fd,
+                                                   client->lease->server_address,
+                                                   DHCP_PORT_SERVER,
+                                                   &request->dhcp,
+                                                   len - DHCP_IP_UDP_SIZE);
+        } else {
+                dhcp_packet_append_ip_headers(request, len);
+
+                err = dhcp_network_send_raw_socket(client->fd, &client->link,
+                                                   request, len);
+        }
+
+        log_dhcp_client(client, "REQUEST");
+
+        return err;
+}
+
+static uint16_t client_update_secs(sd_dhcp_client *client, usec_t time_now)
+{
+        client->secs = ((time_now - client->start_time) / USEC_PER_SEC) ? : 1;
+
+        return client->secs;
+}
+
+static int client_timeout_resend(sd_event_source *s, uint64_t usec,
+                                 void *userdata) {
+        sd_dhcp_client *client = userdata;
+        usec_t next_timeout = 0;
+        uint32_t time_left;
+        int r = 0;
+
+        assert(s);
+        assert(client);
+        assert(client->event);
+
+        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 = usec + 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 = usec + time_left * USEC_PER_SEC;
+                break;
+
+        case DHCP_STATE_INIT:
+        case DHCP_STATE_INIT_REBOOT:
+        case DHCP_STATE_REBOOTING:
+        case DHCP_STATE_SELECTING:
+        case DHCP_STATE_REQUESTING:
+        case DHCP_STATE_BOUND:
+
+                if (client->attempt < 64)
+                        client->attempt *= 2;
+
+                next_timeout = usec + (client->attempt - 1) * USEC_PER_SEC;
+
+                break;
+        }
+
+        next_timeout += (random_u32() & 0x1fffff);
+
+        client->timeout_resend = sd_event_source_unref(client->timeout_resend);
+
+        r = sd_event_add_monotonic(client->event,
+                                     &client->timeout_resend,
+                                     next_timeout,
+                                     10 * USEC_PER_MSEC,
+                                     client_timeout_resend, client);
+        if (r < 0)
+                goto error;
+
+        r = sd_event_source_set_priority(client->timeout_resend,
+                                         client->event_priority);
+        if (r < 0)
+                goto error;
+
+        switch (client->state) {
+        case DHCP_STATE_INIT:
+
+                client_update_secs(client, usec);
+
+                r = client_send_discover(client, client->secs);
+                if (r >= 0) {
+                        client->state = DHCP_STATE_SELECTING;
+                        client->attempt = 1;
+                } else {
+                        if (client->attempt >= 64)
+                                goto error;
+                }
+
+                break;
+
+        case DHCP_STATE_SELECTING:
+                client_update_secs(client, usec);
+
+                r = client_send_discover(client, client->secs);
+                if (r < 0 && client->attempt >= 64)
+                        goto error;
+
+                break;
+
+        case DHCP_STATE_REQUESTING:
+        case DHCP_STATE_RENEWING:
+        case DHCP_STATE_REBINDING:
+                r = client_send_request(client, client->secs);
+                if (r < 0 && client->attempt >= 64)
+                         goto error;
+
+                client->request_sent = usec;
+
+                break;
+
+        case DHCP_STATE_INIT_REBOOT:
+        case DHCP_STATE_REBOOTING:
+        case DHCP_STATE_BOUND:
+
+                break;
+        }
+
+        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_events(sd_dhcp_client *client,
+                                    sd_event_io_handler_t io_callback,
+                                    usec_t usec) {
+        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;
+
+        client->timeout_resend = sd_event_source_unref(client->timeout_resend);
+
+        r = sd_event_add_monotonic(client->event,
+                                   &client->timeout_resend,
+                                   usec, 0,
+                                   client_timeout_resend, client);
+        if (r < 0)
+                goto error;
+
+        r = sd_event_source_set_priority(client->timeout_resend,
+                                         client->event_priority);
+
+error:
+        if (r < 0)
+                client_stop(client, r);
+
+        return 0;
+
+}
+
+static int client_timeout_expire(sd_event_source *s, uint64_t usec,
+                                 void *userdata) {
+        sd_dhcp_client *client = userdata;
+
+        log_dhcp_client(client, "EXPIRED");
+
+        client_stop(client, DHCP_EVENT_EXPIRED);
+
+        return 0;
+}
+
+static int client_timeout_t2(sd_event_source *s, uint64_t usec, void *userdata) {
+        sd_dhcp_client *client = userdata;
+        int r;
+
+        if (client->fd >= 0) {
+                client->receive_message =
+                        sd_event_source_unref(client->receive_message);
+                close(client->fd);
+                client->fd = -1;
+        }
+
+        client->state = DHCP_STATE_REBINDING;
+        client->attempt = 1;
+
+        r = dhcp_network_bind_raw_socket(client->index, &client->link);
+        if (r < 0) {
+                client_stop(client, r);
+                return 0;
+        }
+
+        client->fd = r;
+
+        log_dhcp_client(client, "TIMEOUT T2");
+
+        return client_initialize_events(client, client_receive_message_raw,
+                                        usec);
+}
+
+static int client_timeout_t1(sd_event_source *s, uint64_t usec,
+                             void *userdata) {
+        sd_dhcp_client *client = userdata;
+        int r;
+
+        client->state = DHCP_STATE_RENEWING;
+        client->attempt = 1;
+
+        r = dhcp_network_bind_udp_socket(client->index,
+                                         client->lease->address,
+                                         DHCP_PORT_CLIENT);
+        if (r < 0) {
+                client_stop(client, r);
+                return 0;
+        }
+
+        client->fd = r;
+
+        log_dhcp_client(client, "TIMEOUT T1");
+
+        return client_initialize_events(client, client_receive_message_udp, usec);
+}
+
+static int client_handle_offer(sd_dhcp_client *client, DHCPMessage *offer,
+                               size_t len) {
+        _cleanup_dhcp_lease_unref_ sd_dhcp_lease *lease = NULL;
+        int r;
+
+        r = dhcp_lease_new(&lease);
+        if (r < 0)
+                return r;
+
+        r = dhcp_option_parse(offer, len, dhcp_lease_parse_options, lease);
+        if (r != DHCP_OFFER)
+                return -ENOMSG;
+
+        lease->address = offer->yiaddr;
+
+        if (lease->address == INADDR_ANY ||
+            lease->server_address == INADDR_ANY ||
+            lease->subnet_mask == INADDR_ANY ||
+            lease->lifetime == 0)
+                return -ENOMSG;
+
+        client->lease = lease;
+        lease = NULL;
+
+        log_dhcp_client(client, "OFFER");
+
+        return 0;
+}
+
+static int client_handle_ack(sd_dhcp_client *client, DHCPMessage *ack,
+                             size_t len) {
+        _cleanup_dhcp_lease_unref_ sd_dhcp_lease *lease = NULL;
+        int r;
+
+        r = dhcp_lease_new(&lease);
+        if (r < 0)
+                return r;
+
+        r = dhcp_option_parse(ack, len, dhcp_lease_parse_options, lease);
+        if (r == DHCP_NAK) {
+                log_dhcp_client(client, "NAK");
+                return DHCP_EVENT_NO_LEASE;
+        }
+
+        if (r != DHCP_ACK)
+                return -ENOMSG;
+
+        lease->address = ack->yiaddr;
+
+        if (lease->address == INADDR_ANY ||
+            lease->server_address == INADDR_ANY ||
+            lease->subnet_mask == INADDR_ANY || lease->lifetime == 0)
+                return -ENOMSG;
+
+        r = DHCP_EVENT_IP_ACQUIRE;
+        if (client->lease) {
+                if (client->lease->address != lease->address ||
+                    client->lease->subnet_mask != lease->subnet_mask ||
+                    client->lease->router != lease->router) {
+                        r = DHCP_EVENT_IP_CHANGE;
+                }
+
+                client->lease = sd_dhcp_lease_unref(client->lease);
+        }
+
+        client->lease = lease;
+        lease = NULL;
+
+        log_dhcp_client(client, "ACK");
+
+        return r;
+}
+
+static uint64_t client_compute_timeout(uint64_t request_sent,
+                                       uint32_t lifetime) {
+        return request_sent + (lifetime - 3) * USEC_PER_SEC +
+                + (random_u32() & 0x1fffff);
+}
+
+static int client_set_lease_timeouts(sd_dhcp_client *client, uint64_t usec) {
+        uint64_t next_timeout;
+        int r;
+
+        assert(client);
+        assert(client->event);
+
+        if (client->lease->lifetime < 10)
+                return -EINVAL;
+
+        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);
+
+        if (!client->lease->t1)
+                client->lease->t1 = client->lease->lifetime / 2;
+
+        next_timeout = client_compute_timeout(client->request_sent,
+                                              client->lease->t1);
+        if (next_timeout < usec)
+                return -EINVAL;
+
+        r = sd_event_add_monotonic(client->event,
+                                     &client->timeout_t1,
+                                     next_timeout,
+                                     10 * USEC_PER_MSEC,
+                                     client_timeout_t1, client);
+        if (r < 0)
+                return r;
+
+        r = sd_event_source_set_priority(client->timeout_t1,
+                                         client->event_priority);
+        if (r < 0)
+                return r;
+
+        if (!client->lease->t2)
+                client->lease->t2 = client->lease->lifetime * 7 / 8;
+
+        if (client->lease->t2 < client->lease->t1)
+                return -EINVAL;
+
+        if (client->lease->lifetime < client->lease->t2)
+                return -EINVAL;
+
+        next_timeout = client_compute_timeout(client->request_sent,
+                                              client->lease->t2);
+        if (next_timeout < usec)
+                return -EINVAL;
+
+        r = sd_event_add_monotonic(client->event,
+                                     &client->timeout_t2,
+                                     next_timeout,
+                                     10 * USEC_PER_MSEC,
+                                     client_timeout_t2, client);
+        if (r < 0)
+                return r;
+
+        r = sd_event_source_set_priority(client->timeout_t2,
+                                         client->event_priority);
+        if (r < 0)
+                return r;
+
+        next_timeout = client_compute_timeout(client->request_sent,
+                                              client->lease->lifetime);
+        if (next_timeout < usec)
+                return -EINVAL;
+
+        r = sd_event_add_monotonic(client->event,
+                                     &client->timeout_expire, next_timeout,
+                                     10 * USEC_PER_MSEC,
+                                     client_timeout_expire, client);
+        if (r < 0)
+                return r;
+
+        r = sd_event_source_set_priority(client->timeout_expire,
+                                         client->event_priority);
+        if (r < 0)
+                return r;
+
+        return 0;
+}
+
+static int client_handle_message(sd_dhcp_client *client, DHCPMessage *message,
+                                 int len, usec_t time_now) {
+        int r = 0, notify_event = 0;
+
+        assert(client);
+        assert(client->event);
+        assert(message);
+
+        if (len < DHCP_MESSAGE_SIZE) {
+                log_dhcp_client(client, "message too small (%d bytes): "
+                                "ignoring", len);
+                return 0;
+        }
+
+        if (message->op != BOOTREPLY) {
+                log_dhcp_client(client, "not a BOOTREPLY message: ignoring");
+                return 0;
+        }
+
+        if (be32toh(message->xid) != client->xid) {
+                log_dhcp_client(client, "received xid (%u) does not match "
+                                "expected (%u): ignoring",
+                                be32toh(message->xid), client->xid);
+                return 0;
+        }
+
+        if (memcmp(&message->chaddr[0], &client->mac_addr.ether_addr_octet,
+                   ETHER_ADDR_LEN)) {
+                log_dhcp_client(client, "received chaddr does not match "
+                                "expected: ignoring");
+                return 0;
+        }
+
+        switch (client->state) {
+        case DHCP_STATE_SELECTING:
+
+                r = client_handle_offer(client, message, len);
+                if (r >= 0) {
+
+                        client->timeout_resend =
+                                sd_event_source_unref(client->timeout_resend);
+
+                        client->state = DHCP_STATE_REQUESTING;
+                        client->attempt = 1;
+
+                        r = sd_event_add_monotonic(client->event,
+                                                   &client->timeout_resend,
+                                                   time_now, 0,
+                                                   client_timeout_resend,
+                                                   client);
+                        if (r < 0)
+                                goto error;
+
+                        r = sd_event_source_set_priority(client->timeout_resend,
+                                                         client->event_priority);
+                        if (r < 0)
+                                goto error;
+                }
+
+                break;
+
+        case DHCP_STATE_REQUESTING:
+        case DHCP_STATE_RENEWING:
+        case DHCP_STATE_REBINDING:
+
+                r = client_handle_ack(client, message, len);
+
+                if (r == DHCP_EVENT_NO_LEASE)
+                        goto error;
+
+                if (r >= 0) {
+                        client->timeout_resend =
+                                sd_event_source_unref(client->timeout_resend);
+
+                        if (client->state == DHCP_STATE_REQUESTING)
+                                notify_event = DHCP_EVENT_IP_ACQUIRE;
+                        else if (r != DHCP_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, time_now);
+                        if (r < 0)
+                                goto error;
+
+                        if (notify_event)
+                                client_notify(client, notify_event);
+
+                        client->receive_message =
+                                sd_event_source_unref(client->receive_message);
+                        close(client->fd);
+                        client->fd = -1;
+                }
+
+                r = 0;
+
+                break;
+
+        case DHCP_STATE_INIT:
+        case DHCP_STATE_INIT_REBOOT:
+        case DHCP_STATE_REBOOTING:
+        case DHCP_STATE_BOUND:
+
+                break;
+        }
+
+error:
+        if (r < 0 || r == DHCP_EVENT_NO_LEASE)
+                return client_stop(client, r);
+
+        return 0;
+}
+
+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;
+        int buflen = 0, len, r;
+        usec_t time_now;
+
+        assert(s);
+        assert(client);
+        assert(client->event);
+
+        r = ioctl(fd, FIONREAD, &buflen);
+        if (r < 0 || buflen <= 0)
+                buflen = sizeof(DHCPMessage) + DHCP_MIN_OPTIONS_SIZE;
+
+        message = malloc0(buflen);
+        if (!message)
+                return -ENOMEM;
+
+        len = read(fd, message, buflen);
+        if (len < 0)
+                return 0;
+
+        r = sd_event_get_now_monotonic(client->event, &time_now);
+        if (r < 0)
+                return client_stop(client, r);
+
+        return client_handle_message(client, message, len,
+                                     time_now);
+}
+
+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;
+        usec_t time_now;
+        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;
+        int buflen = 0, len, r;
+
+        assert(s);
+        assert(client);
+        assert(client->event);
+
+        r = ioctl(fd, FIONREAD, &buflen);
+        if (r < 0 || buflen <= 0)
+                buflen = sizeof(DHCPPacket) + DHCP_MIN_OPTIONS_SIZE;
+
+        packet = malloc0(buflen);
+        if (!packet)
+                return -ENOMEM;
+
+        iov.iov_base = packet;
+        iov.iov_len = buflen;
+
+        len = recvmsg(fd, &msg, 0);
+        if (len < 0) {
+                log_dhcp_client(client, "could not receive message from raw "
+                                "socket: %s", strerror(errno));
+                return 0;
+        }
+
+        for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
+                if (cmsg->cmsg_level == SOL_PACKET && cmsg->cmsg_type == PACKET_AUXDATA) {
+                        struct tpacket_auxdata *aux = (void *)CMSG_DATA(cmsg);
+
+                        checksum = !(aux->tp_status & TP_STATUS_CSUMNOTREADY);
+                        break;
+                }
+        }
+
+        r = dhcp_packet_verify_headers(packet, len, checksum);
+        if (r < 0)
+                return 0;
+
+        len -= DHCP_IP_UDP_SIZE;
+
+        r = sd_event_get_now_monotonic(client->event, &time_now);
+        if (r < 0)
+                return client_stop(client, r);
+
+        return client_handle_message(client, &packet->dhcp, len, time_now);
+}
+
+int sd_dhcp_client_start(sd_dhcp_client *client) {
+        int r;
+
+        assert_return(client, -EINVAL);
+        assert_return(client->event, -EINVAL);
+        assert_return(client->index > 0, -EINVAL);
+        assert_return(client->state == DHCP_STATE_INIT ||
+                      client->state == DHCP_STATE_INIT_REBOOT, -EBUSY);
+
+        client->xid = random_u32();
+
+        r = dhcp_network_bind_raw_socket(client->index, &client->link);
+
+        if (r < 0) {
+                client_stop(client, r);
+                return r;
+        }
+
+        client->fd = r;
+        client->start_time = now(CLOCK_MONOTONIC);
+        client->secs = 0;
+
+        log_dhcp_client(client, "STARTED");
+
+        return client_initialize_events(client, client_receive_message_raw,
+                                        client->start_time);
+}
+
+int sd_dhcp_client_stop(sd_dhcp_client *client) {
+        return client_stop(client, DHCP_EVENT_STOP);
+}
+
+int sd_dhcp_client_attach_event(sd_dhcp_client *client, sd_event *event,
+                                int 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) {
+        if (!client)
+                return NULL;
+
+        return client->event;
+}
+
+void sd_dhcp_client_free(sd_dhcp_client *client) {
+        if (!client)
+                return;
+
+        sd_dhcp_client_stop(client);
+        sd_dhcp_client_detach_event(client);
+
+        free(client->req_opts);
+        free(client);
+}
+
+DEFINE_TRIVIAL_CLEANUP_FUNC(sd_dhcp_client*, sd_dhcp_client_free);
+#define _cleanup_dhcp_client_free_ _cleanup_(sd_dhcp_client_freep)
+
+int sd_dhcp_client_new(sd_dhcp_client **ret) {
+        _cleanup_dhcp_client_free_ sd_dhcp_client *client = NULL;
+
+        assert_return(ret, -EINVAL);
+
+        client = new0(sd_dhcp_client, 1);
+        if (!client)
+                return -ENOMEM;
+
+        client->state = DHCP_STATE_INIT;
+        client->index = -1;
+        client->fd = -1;
+        client->attempt = 1;
+
+        client->req_opts_size = ELEMENTSOF(default_req_opts);
+
+        client->req_opts = memdup(default_req_opts, client->req_opts_size);
+        if (!client->req_opts)
+                return -ENOMEM;
+
+        *ret = client;
+        client = NULL;
+
+        return 0;
+}