libsystemd-dhcp: revert merge into libsystemd

Unlike the other merged libs, the rest of libsystemd will never depend on
sd-dhcp-client, so there is no reason not to keep it separate.

1 files changed, 1254 insertions, 0 deletions

diff --git a/src/libsystemd-dhcp/sd-dhcp-client.c b/src/libsystemd-dhcp/sd-dhcp-client.c
new file mode 100644
index 0000000000..3b7b9f4ccd
--- /dev/null
+++ b/src/libsystemd-dhcp/sd-dhcp-client.c
@@ -0,0 +1,1254 @@
+/***
+  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 "util.h"
+#include "list.h"
+
+#include "dhcp-protocol.h"
+#include "dhcp-internal.h"
+#include "sd-dhcp-client.h"
+
+#define DHCP_CLIENT_MIN_OPTIONS_SIZE            312
+
+#define client_state_machine_check(s, r)                                \
+        do {                                                            \
+                if (s != DHCP_STATE_BOUND &&                            \
+                    s != DHCP_STATE_RENEWING &&                         \
+                    s != DHCP_STATE_REBINDING) {                        \
+                        return (r);                                     \
+                }                                                       \
+        } while (false)
+
+struct DHCPLease {
+        uint32_t t1;
+        uint32_t t2;
+        uint32_t lifetime;
+        be32_t address;
+        be32_t server_address;
+        be32_t subnet_mask;
+        be32_t router;
+        struct in_addr *dns;
+        size_t dns_size;
+        uint16_t mtu;
+        char *domainname;
+        char *hostname;
+};
+
+typedef struct DHCPLease DHCPLease;
+
+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;
+        unsigned int attempt;
+        usec_t request_sent;
+        sd_event_source *timeout_t1;
+        sd_event_source *timeout_t2;
+        sd_event_source *timeout_expire;
+        sd_dhcp_client_cb_t cb;
+        void *userdata;
+        DHCPLease *lease;
+};
+
+static const uint8_t default_req_opts[] = {
+        DHCP_OPTION_SUBNET_MASK,
+        DHCP_OPTION_ROUTER,
+        DHCP_OPTION_HOST_NAME,
+        DHCP_OPTION_DOMAIN_NAME,
+        DHCP_OPTION_DOMAIN_NAME_SERVER,
+        DHCP_OPTION_NTP_SERVER,
+};
+
+static int client_receive_message(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_address(sd_dhcp_client *client, struct in_addr *addr) {
+        assert_return(client, -EINVAL);
+        assert_return(addr, -EINVAL);
+
+        client_state_machine_check (client->state, -EADDRNOTAVAIL);
+
+        addr->s_addr = client->lease->address;
+
+        return 0;
+}
+
+int sd_dhcp_client_get_mtu(sd_dhcp_client *client, uint16_t *mtu) {
+        assert_return(client, -EINVAL);
+        assert_return(mtu, -EINVAL);
+
+        client_state_machine_check (client->state, -EADDRNOTAVAIL);
+
+        if (client->lease->mtu)
+                *mtu = client->lease->mtu;
+        else
+                return -ENOENT;
+
+        return 0;
+}
+
+int sd_dhcp_client_get_dns(sd_dhcp_client *client, struct in_addr **addr, size_t *addr_size) {
+        assert_return(client, -EINVAL);
+        assert_return(addr, -EINVAL);
+        assert_return(addr_size, -EINVAL);
+
+        client_state_machine_check (client->state, -EADDRNOTAVAIL);
+
+        if (client->lease->dns_size) {
+                *addr_size = client->lease->dns_size;
+                *addr = client->lease->dns;
+        } else
+                return -ENOENT;
+
+        return 0;
+}
+
+int sd_dhcp_client_get_domainname(sd_dhcp_client *client, const char **domainname) {
+        assert_return(client, -EINVAL);
+        assert_return(domainname, -EINVAL);
+
+        client_state_machine_check (client->state, -EADDRNOTAVAIL);
+
+        if (client->lease->domainname)
+                *domainname = client->lease->domainname;
+        else
+                return -ENOENT;
+
+        return 0;
+}
+
+int sd_dhcp_client_get_hostname(sd_dhcp_client *client, const char **hostname) {
+        assert_return(client, -EINVAL);
+        assert_return(hostname, -EINVAL);
+
+        client_state_machine_check (client->state, -EADDRNOTAVAIL);
+
+        if (client->lease->hostname)
+                *hostname = client->lease->hostname;
+        else
+                return -ENOENT;
+
+        return 0;
+}
+
+int sd_dhcp_client_prefixlen(const struct in_addr *addr) {
+        int len = 0;
+        uint32_t mask;
+
+        assert_return(addr, -EADDRNOTAVAIL);
+
+        mask = be32toh(addr->s_addr);
+        while (mask) {
+                len++;
+                mask = mask << 1;
+        }
+
+        return len;
+}
+
+int sd_dhcp_client_get_router(sd_dhcp_client *client, struct in_addr *addr) {
+        assert_return(client, -EINVAL);
+        assert_return(addr, -EINVAL);
+
+        client_state_machine_check (client->state, -EADDRNOTAVAIL);
+
+        addr->s_addr = client->lease->router;
+
+        return 0;
+}
+
+int sd_dhcp_client_get_netmask(sd_dhcp_client *client, struct in_addr *addr) {
+        assert_return(client, -EINVAL);
+        assert_return(addr, -EINVAL);
+
+        client_state_machine_check (client->state, -EADDRNOTAVAIL);
+
+        addr->s_addr = client->lease->subnet_mask;
+
+        return 0;
+}
+
+static int client_notify(sd_dhcp_client *client, int event) {
+        if (client->cb)
+                client->cb(client, event, client->userdata);
+
+        return 0;
+}
+
+static void lease_free(DHCPLease *lease) {
+        if (!lease)
+                return;
+
+        free(lease->hostname);
+        free(lease->domainname);
+        free(lease->dns);
+        free(lease);
+}
+
+DEFINE_TRIVIAL_CLEANUP_FUNC(DHCPLease*, lease_free);
+#define _cleanup_lease_free_ _cleanup_(lease_freep)
+
+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);
+
+        switch (client->state) {
+
+        case DHCP_STATE_INIT:
+        case DHCP_STATE_SELECTING:
+        case DHCP_STATE_REQUESTING:
+        case DHCP_STATE_BOUND:
+
+                client->start_time = 0;
+                client->state = DHCP_STATE_INIT;
+                break;
+
+        case DHCP_STATE_INIT_REBOOT:
+        case DHCP_STATE_REBOOTING:
+        case DHCP_STATE_RENEWING:
+        case DHCP_STATE_REBINDING:
+
+                break;
+        }
+
+        if (client->lease) {
+                lease_free(client->lease);
+                client->lease = NULL;
+        }
+
+        return 0;
+}
+
+static int client_packet_init(sd_dhcp_client *client, uint8_t type,
+                              DHCPMessage *message, uint16_t secs,
+                              uint8_t **opt, size_t *optlen) {
+        int err;
+        be16_t max_size;
+
+        *opt = (uint8_t *)(message + 1);
+
+        if (*optlen < 4)
+                return -ENOBUFS;
+        *optlen -= 4;
+
+        message->op = BOOTREQUEST;
+        message->htype = 1;
+        message->hlen = ETHER_ADDR_LEN;
+        message->xid = htobe32(client->xid);
+
+        /* Although 'secs' field is a SHOULD in RFC 2131, certain DHCP servers
+           refuse to issue an DHCP lease if 'secs' is set to zero */
+        message->secs = htobe16(secs);
+
+        if (client->state == DHCP_STATE_RENEWING ||
+            client->state == DHCP_STATE_REBINDING)
+                message->ciaddr = client->lease->address;
+
+        memcpy(&message->chaddr, &client->mac_addr, ETH_ALEN);
+        (*opt)[0] = 0x63;
+        (*opt)[1] = 0x82;
+        (*opt)[2] = 0x53;
+        (*opt)[3] = 0x63;
+
+        *opt += 4;
+
+        err = dhcp_option_append(opt, optlen, DHCP_OPTION_MESSAGE_TYPE, 1,
+                                 &type);
+        if (err < 0)
+                return err;
+
+        /* Some DHCP servers will refuse to issue an DHCP lease if the Cliient
+           Identifier option is not set */
+        err = dhcp_option_append(opt, optlen, DHCP_OPTION_CLIENT_IDENTIFIER,
+                                 ETH_ALEN, &client->mac_addr);
+        if (err < 0)
+                return err;
+
+        if (type == DHCP_DISCOVER || type == DHCP_REQUEST) {
+                err = dhcp_option_append(opt, optlen,
+                                         DHCP_OPTION_PARAMETER_REQUEST_LIST,
+                                         client->req_opts_size,
+                                         client->req_opts);
+                if (err < 0)
+                        return err;
+
+                /* Some DHCP servers will send bigger DHCP packets than the
+                   defined default size unless the Maximum Messge Size option
+                   is explicitely set */
+                max_size = htobe16(DHCP_IP_UDP_SIZE + DHCP_MESSAGE_SIZE +
+                                   DHCP_CLIENT_MIN_OPTIONS_SIZE);
+                err = dhcp_option_append(opt, optlen,
+                                         DHCP_OPTION_MAXIMUM_MESSAGE_SIZE,
+                                         2, &max_size);
+                if (err < 0)
+                        return err;
+        }
+
+        return 0;
+}
+
+static uint16_t client_checksum(void *buf, int len) {
+        uint32_t sum;
+        uint16_t *check;
+        int i;
+        uint8_t *odd;
+
+        sum = 0;
+        check = buf;
+
+        for (i = 0; i < len / 2 ; i++)
+                sum += check[i];
+
+        if (len & 0x01) {
+                odd = buf;
+                sum += odd[len - 1];
+        }
+
+        while (sum >> 16)
+                sum = (sum & 0xffff) + (sum >> 16);
+
+        return ~sum;
+}
+
+static void client_append_ip_headers(DHCPPacket *packet, uint16_t len) {
+        packet->ip.version = IPVERSION;
+        packet->ip.ihl = DHCP_IP_SIZE / 4;
+        packet->ip.tot_len = htobe16(len);
+
+        packet->ip.protocol = IPPROTO_UDP;
+        packet->ip.saddr = INADDR_ANY;
+        packet->ip.daddr = INADDR_BROADCAST;
+
+        packet->udp.source = htobe16(DHCP_PORT_CLIENT);
+        packet->udp.dest = htobe16(DHCP_PORT_SERVER);
+        packet->udp.len = htobe16(len - DHCP_IP_SIZE);
+
+        packet->ip.check = packet->udp.len;
+        packet->udp.check = client_checksum(&packet->ip.ttl, len - 8);
+
+        packet->ip.ttl = IPDEFTTL;
+        packet->ip.check = 0;
+        packet->ip.check = client_checksum(&packet->ip, DHCP_IP_SIZE);
+}
+
+static int client_send_discover(sd_dhcp_client *client, uint16_t secs) {
+        int err = 0;
+        _cleanup_free_ DHCPPacket *discover;
+        size_t optlen, len;
+        uint8_t *opt;
+
+        optlen = DHCP_CLIENT_MIN_OPTIONS_SIZE;
+        len = sizeof(DHCPPacket) + optlen;
+
+        discover = malloc0(len);
+
+        if (!discover)
+                return -ENOMEM;
+
+        err = client_packet_init(client, DHCP_DISCOVER, &discover->dhcp,
+                                 secs, &opt, &optlen);
+        if (err < 0)
+                return err;
+
+        if (client->last_addr != INADDR_ANY) {
+                err = dhcp_option_append(&opt, &optlen,
+                                         DHCP_OPTION_REQUESTED_IP_ADDRESS,
+                                         4, &client->last_addr);
+                if (err < 0)
+                        return err;
+        }
+
+        err = dhcp_option_append(&opt, &optlen, DHCP_OPTION_END, 0, NULL);
+        if (err < 0)
+                return err;
+
+        client_append_ip_headers(discover, len);
+
+        err = dhcp_network_send_raw_socket(client->fd, &client->link,
+                                           discover, len);
+
+        return err;
+}
+
+static int client_send_request(sd_dhcp_client *client, uint16_t secs) {
+        _cleanup_free_ DHCPPacket *request;
+        size_t optlen, len;
+        int err;
+        uint8_t *opt;
+
+        optlen = DHCP_CLIENT_MIN_OPTIONS_SIZE;
+        len = DHCP_MESSAGE_SIZE + optlen;
+
+        request = malloc0(len);
+        if (!request)
+                return -ENOMEM;
+
+        err = client_packet_init(client, DHCP_REQUEST, &request->dhcp, secs,
+                                 &opt, &optlen);
+        if (err < 0)
+                return err;
+
+        if (client->state == DHCP_STATE_REQUESTING) {
+                err = dhcp_option_append(&opt, &optlen,
+                                         DHCP_OPTION_REQUESTED_IP_ADDRESS,
+                                         4, &client->lease->address);
+                if (err < 0)
+                        return err;
+
+                err = dhcp_option_append(&opt, &optlen,
+                                         DHCP_OPTION_SERVER_IDENTIFIER,
+                                         4, &client->lease->server_address);
+                if (err < 0)
+                        return err;
+        }
+
+        err = dhcp_option_append(&opt, &optlen, DHCP_OPTION_END, 0, NULL);
+        if (err < 0)
+                return err;
+
+        if (client->state == DHCP_STATE_RENEWING) {
+                err = dhcp_network_send_udp_socket(client->fd,
+                                                   client->lease->server_address,
+                                                   &request->dhcp,
+                                                   len - DHCP_IP_UDP_SIZE);
+        } else {
+                client_append_ip_headers(request, len);
+
+                err = dhcp_network_send_raw_socket(client->fd, &client->link,
+                                                   request, len);
+        }
+
+        return err;
+}
+
+static int client_timeout_resend(sd_event_source *s, uint64_t usec,
+                                 void *userdata) {
+        sd_dhcp_client *client = userdata;
+        usec_t next_timeout = 0;
+        uint32_t time_left;
+        uint16_t secs;
+        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);
+
+        r = sd_event_add_monotonic(client->event, next_timeout,
+                                     10 * USEC_PER_MSEC,
+                                     client_timeout_resend, client,
+                                     &client->timeout_resend);
+        if (r < 0)
+                goto error;
+
+        r = sd_event_source_set_priority(client->timeout_resend, client->event_priority);
+        if (r < 0)
+                goto error;
+
+        secs = (usec - client->start_time) / USEC_PER_SEC;
+
+        switch (client->state) {
+        case DHCP_STATE_INIT:
+                r = client_send_discover(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:
+                r = client_send_discover(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, 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, usec_t usec) {
+        int r;
+
+        assert(client);
+        assert(client->event);
+
+        r = sd_event_add_io(client->event, client->fd, EPOLLIN,
+                            client_receive_message, client,
+                            &client->receive_message);
+        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_add_monotonic(client->event, usec, 0,
+                                   client_timeout_resend, client,
+                                   &client->timeout_resend);
+        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;
+
+        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;
+
+        return client_initialize_events(client, 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);
+        if (r < 0) {
+                client_stop(client, r);
+                return 0;
+        }
+
+        client->fd = r;
+
+        return client_initialize_events(client, usec);
+}
+
+static int client_parse_offer(uint8_t code, uint8_t len, const uint8_t *option,
+                              void *user_data) {
+        DHCPLease *lease = user_data;
+        be32_t val;
+
+        switch(code) {
+
+        case DHCP_OPTION_IP_ADDRESS_LEASE_TIME:
+                if (len == 4) {
+                        memcpy(&val, option, 4);
+                        lease->lifetime = be32toh(val);
+                }
+
+                break;
+
+        case DHCP_OPTION_SERVER_IDENTIFIER:
+                if (len >= 4)
+                        memcpy(&lease->server_address, option, 4);
+
+                break;
+
+        case DHCP_OPTION_SUBNET_MASK:
+                if (len >= 4)
+                        memcpy(&lease->subnet_mask, option, 4);
+
+                break;
+
+        case DHCP_OPTION_ROUTER:
+                if (len >= 4)
+                        memcpy(&lease->router, option, 4);
+
+                break;
+
+        case DHCP_OPTION_DOMAIN_NAME_SERVER:
+                if (len >= 4) {
+                        unsigned i;
+
+                        lease->dns_size = len / 4;
+
+                        free(lease->dns);
+                        lease->dns = new0(struct in_addr, lease->dns_size);
+                        if (!lease->dns)
+                                return -ENOMEM;
+
+                        for (i = 0; i < lease->dns_size; i++) {
+                                memcpy(&lease->dns[i].s_addr, option + 4 * i, 4);
+                        }
+                }
+
+                break;
+
+        case DHCP_OPTION_INTERFACE_MTU:
+                if (len >= 2) {
+                        be16_t mtu;
+
+                        memcpy(&mtu, option, 2);
+                        lease->mtu = be16toh(mtu);
+
+                        if (lease->mtu < 68)
+                                lease->mtu = 0;
+                }
+
+                break;
+
+        case DHCP_OPTION_DOMAIN_NAME:
+                if (len >= 1) {
+                        free(lease->domainname);
+                        lease->domainname = strndup((const char *)option, len);
+                }
+
+                break;
+
+        case DHCP_OPTION_HOST_NAME:
+                if (len >= 1) {
+                        free(lease->hostname);
+                        lease->hostname = strndup((const char *)option, len);
+                }
+
+                break;
+
+        case DHCP_OPTION_RENEWAL_T1_TIME:
+                if (len == 4) {
+                        memcpy(&val, option, 4);
+                        lease->t1 = be32toh(val);
+                }
+
+                break;
+
+        case DHCP_OPTION_REBINDING_T2_TIME:
+                if (len == 4) {
+                        memcpy(&val, option, 4);
+                        lease->t2 = be32toh(val);
+                }
+
+                break;
+        }
+
+        return 0;
+}
+
+static int client_verify_headers(sd_dhcp_client *client, DHCPPacket *message,
+                                 size_t len) {
+        size_t hdrlen;
+
+        if (len < (DHCP_IP_UDP_SIZE + DHCP_MESSAGE_SIZE))
+                return -EINVAL;
+
+        hdrlen = message->ip.ihl * 4;
+        if (hdrlen < 20 || hdrlen > len || client_checksum(&message->ip,
+                                                           hdrlen))
+                return -EINVAL;
+
+        message->ip.check = message->udp.len;
+        message->ip.ttl = 0;
+
+        if (hdrlen + be16toh(message->udp.len) > len ||
+            client_checksum(&message->ip.ttl, be16toh(message->udp.len) + 12))
+                return -EINVAL;
+
+        if (be16toh(message->udp.source) != DHCP_PORT_SERVER ||
+            be16toh(message->udp.dest) != DHCP_PORT_CLIENT)
+                return -EINVAL;
+
+        if (message->dhcp.op != BOOTREPLY)
+                return -EINVAL;
+
+        if (be32toh(message->dhcp.xid) != client->xid)
+                return -EINVAL;
+
+        if (memcmp(&message->dhcp.chaddr[0], &client->mac_addr.ether_addr_octet,
+                    ETHER_ADDR_LEN))
+                return -EINVAL;
+
+        return 0;
+}
+
+static int client_receive_offer(sd_dhcp_client *client, DHCPPacket *offer,
+                                size_t len) {
+        _cleanup_lease_free_ DHCPLease *lease = NULL;
+        int r;
+
+        r = client_verify_headers(client, offer, len);
+        if (r < 0)
+                return r;
+
+        lease = new0(DHCPLease, 1);
+        if (!lease)
+                return -ENOMEM;
+
+        len = len - DHCP_IP_UDP_SIZE;
+        r = dhcp_option_parse(&offer->dhcp, len, client_parse_offer,
+                              lease);
+        if (r != DHCP_OFFER)
+                return -ENOMSG;
+
+        lease->address = offer->dhcp.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;
+
+        return 0;
+}
+
+static int client_receive_ack(sd_dhcp_client *client, const uint8_t *buf,
+                              size_t len) {
+        DHCPPacket *ack;
+        DHCPMessage *dhcp;
+        _cleanup_lease_free_ DHCPLease *lease = NULL;
+        int r;
+
+        if (client->state == DHCP_STATE_RENEWING) {
+                dhcp = (DHCPMessage *)buf;
+        } else {
+                ack = (DHCPPacket *)buf;
+
+                r = client_verify_headers(client, ack, len);
+                if (r < 0)
+                        return r;
+
+                dhcp = &ack->dhcp;
+                len -= DHCP_IP_UDP_SIZE;
+        }
+
+        lease = new0(DHCPLease, 1);
+        if (!lease)
+                return -ENOMEM;
+
+        r = dhcp_option_parse(dhcp, len, client_parse_offer, lease);
+        if (r == DHCP_NAK)
+                return DHCP_EVENT_NO_LEASE;
+
+        if (r != DHCP_ACK)
+                return -ENOMSG;
+
+        lease->address = dhcp->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;
+                }
+
+                lease_free(client->lease);
+        }
+
+        client->lease = lease;
+        lease = NULL;
+
+        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, next_timeout,
+                                     10 * USEC_PER_MSEC,
+                                     client_timeout_t1, client,
+                                     &client->timeout_t1);
+        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, next_timeout,
+                                     10 * USEC_PER_MSEC,
+                                     client_timeout_t2, client,
+                                     &client->timeout_t2);
+        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, next_timeout,
+                                     10 * USEC_PER_MSEC,
+                                     client_timeout_expire, client,
+                                     &client->timeout_expire);
+        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_receive_message(sd_event_source *s, int fd,
+                                  uint32_t revents, void *userdata) {
+        sd_dhcp_client *client = userdata;
+        uint8_t buf[sizeof(DHCPPacket) + DHCP_CLIENT_MIN_OPTIONS_SIZE];
+        int buflen = sizeof(buf);
+        int len, r = 0, notify_event = 0;
+        DHCPPacket *message;
+        usec_t time_now;
+
+        assert(s);
+        assert(client);
+        assert(client->event);
+
+        len = read(fd, &buf, buflen);
+        if (len < 0)
+                return 0;
+
+        r = sd_event_get_now_monotonic(client->event, &time_now);
+        if (r < 0)
+                goto error;
+
+        switch (client->state) {
+        case DHCP_STATE_SELECTING:
+
+                message = (DHCPPacket *)&buf;
+
+                if (client_receive_offer(client, message, len) >= 0) {
+
+                        client->timeout_resend =
+                                sd_event_source_unref(client->timeout_resend);
+
+                        client->state = DHCP_STATE_REQUESTING;
+                        client->attempt = 1;
+
+                        r = sd_event_add_monotonic(client->event, time_now, 0,
+                                                   client_timeout_resend,
+                                                   client,
+                                                   &client->timeout_resend);
+                        if (r < 0)
+                                goto error;
+
+                        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_receive_ack(client, buf, 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;
+}
+
+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);
+
+        return client_initialize_events(client, 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;
+}