chiark / gitweb /
sd-dhcp-client: return NULL from _unref() like the other sd-* libraries
[elogind.git] / src / libsystemd-network / sd-dhcp-client.c
index 722f862..1603c41 100644 (file)
 #include <stdio.h>
 #include <net/ethernet.h>
 #include <net/if_arp.h>
+#include <netinet/ether.h>
 #include <sys/param.h>
 #include <sys/ioctl.h>
 
 #include "util.h"
 #include "list.h"
+#include "refcnt.h"
+#include "async.h"
 
 #include "dhcp-protocol.h"
 #include "dhcp-internal.h"
@@ -35,6 +38,8 @@
 #include "sd-dhcp-client.h"
 
 struct sd_dhcp_client {
+        RefCount n_ref;
+
         DHCPState state;
         sd_event *event;
         int event_priority;
@@ -77,6 +82,7 @@ static int client_receive_message_raw(sd_event_source *s, int fd,
                                       uint32_t revents, void *userdata);
 static int client_receive_message_udp(sd_event_source *s, int fd,
                                       uint32_t revents, void *userdata);
+static void client_stop(sd_dhcp_client *client, int error);
 
 int sd_dhcp_client_set_callback(sd_dhcp_client *client, sd_dhcp_client_cb_t cb,
                                 void *userdata) {
@@ -92,7 +98,8 @@ 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);
+        assert_return (IN_SET(client->state, DHCP_STATE_INIT,
+                              DHCP_STATE_STOPPED), -EBUSY);
 
         switch(option) {
         case DHCP_OPTION_PAD:
@@ -122,7 +129,8 @@ int sd_dhcp_client_set_request_option(sd_dhcp_client *client, uint8_t option) {
 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);
+        assert_return (IN_SET(client->state, DHCP_STATE_INIT,
+                              DHCP_STATE_STOPPED), -EBUSY);
 
         if (last_addr)
                 client->last_addr = last_addr->s_addr;
@@ -134,8 +142,9 @@ int sd_dhcp_client_set_request_address(sd_dhcp_client *client,
 
 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);
+        assert_return (IN_SET(client->state, DHCP_STATE_INIT,
+                              DHCP_STATE_STOPPED), -EBUSY);
+        assert_return(interface_index > 0, -EINVAL);
 
         client->index = interface_index;
 
@@ -144,6 +153,7 @@ int sd_dhcp_client_set_index(sd_dhcp_client *client, int interface_index) {
 
 int sd_dhcp_client_set_mac(sd_dhcp_client *client,
                            const struct ether_addr *addr) {
+        DHCP_CLIENT_DONT_DESTROY(client);
         bool need_restart = false;
 
         assert_return(client, -EINVAL);
@@ -152,17 +162,17 @@ int sd_dhcp_client_set_mac(sd_dhcp_client *client,
         if (memcmp(&client->client_id.mac_addr, addr, ETH_ALEN) == 0)
                 return 0;
 
-        if (client->state != DHCP_STATE_INIT) {
+        if (!IN_SET(client->state, DHCP_STATE_INIT, DHCP_STATE_STOPPED)) {
                 log_dhcp_client(client, "Changing MAC address on running DHCP "
                                 "client, restarting");
-                sd_dhcp_client_stop(client);
                 need_restart = true;
+                client_stop(client, DHCP_EVENT_STOP);
         }
 
         memcpy(&client->client_id.mac_addr, addr, ETH_ALEN);
         client->client_id.type = 0x01;
 
-        if (need_restart)
+        if (need_restart && client->state != DHCP_STATE_STOPPED)
                 sd_dhcp_client_start(client);
 
         return 0;
@@ -182,11 +192,9 @@ int sd_dhcp_client_get_lease(sd_dhcp_client *client, sd_dhcp_lease **ret) {
         return 0;
 }
 
-static int client_notify(sd_dhcp_client *client, int event) {
+static void client_notify(sd_dhcp_client *client, int event) {
         if (client->cb)
                 client->cb(client, event, client->userdata);
-
-        return 0;
 }
 
 static int client_initialize(sd_dhcp_client *client) {
@@ -195,7 +203,7 @@ static int client_initialize(sd_dhcp_client *client) {
         client->receive_message =
                 sd_event_source_unref(client->receive_message);
 
-        client->fd = safe_close(client->fd);
+        client->fd = asynchronous_close(client->fd);
 
         client->timeout_resend = sd_event_source_unref(client->timeout_resend);
 
@@ -214,71 +222,117 @@ static int client_initialize(sd_dhcp_client *client) {
         return 0;
 }
 
-static int client_stop(sd_dhcp_client *client, int error) {
-        assert_return(client, -EINVAL);
+static void client_stop(sd_dhcp_client *client, int error) {
+        assert(client);
+
+        if (error < 0)
+                log_dhcp_client(client, "STOPPED: %s", strerror(-error));
+        else {
+                switch(error) {
+                case DHCP_EVENT_STOP:
+                        log_dhcp_client(client, "STOPPED");
+                        break;
+                case DHCP_EVENT_NO_LEASE:
+                        log_dhcp_client(client, "STOPPED: No lease");
+                        break;
+                default:
+                        log_dhcp_client(client, "STOPPED: Unknown reason");
+                        break;
+                }
+        }
 
         client_notify(client, error);
 
         client_initialize(client);
-
-        log_dhcp_client(client, "STOPPED");
-
-        return 0;
 }
 
-static int client_message_init(sd_dhcp_client *client, DHCPMessage *message,
-                               uint8_t type, uint8_t **opt, size_t *optlen) {
+static int client_message_init(sd_dhcp_client *client, DHCPPacket **ret,
+                               uint8_t type, size_t *_optlen, size_t *_optoffset) {
+        _cleanup_free_ DHCPPacket *packet;
+        size_t optlen, optoffset, size;
+        be16_t max_size;
         int r;
 
         assert(client);
         assert(client->secs);
-        assert(message);
-        assert(opt);
-        assert(optlen);
+        assert(ret);
+        assert(_optlen);
+        assert(_optoffset);
+        assert(type == DHCP_DISCOVER || type == DHCP_REQUEST);
 
-        r = dhcp_message_init(message, BOOTREQUEST, client->xid, type, opt,
-                              optlen);
+        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,
+                              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 */
-        message->secs = htobe16(client->secs);
-
-        memcpy(&message->chaddr, &client->client_id.mac_addr, ETH_ALEN);
-
-        if (client->state == DHCP_STATE_RENEWING ||
-            client->state == DHCP_STATE_REBINDING)
-                message->ciaddr = client->lease->address;
+        packet->dhcp.secs = htobe16(client->secs);
+
+        /* RFC2132 section 4.1
+           A client that cannot receive unicast IP datagrams until its protocol
+           software has been configured with an IP address SHOULD set the
+           BROADCAST bit in the 'flags' field to 1 in any DHCPDISCOVER or
+           DHCPREQUEST messages that client sends.  The BROADCAST bit will
+           provide a hint to the DHCP server and BOOTP relay agent to broadcast
+           any messages to the client on the client's subnet. */
+        packet->dhcp.flags = htobe16(0x8000);
+
+        /* RFC2132 section 4.1.1:
+           The client MUST include its hardware address in the ’chaddr’ field, if
+           necessary for delivery of DHCP reply messages.
+         */
+        memcpy(&packet->dhcp.chaddr, &client->client_id.mac_addr, ETH_ALEN);
 
         /* 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,
+        r = dhcp_option_append(&packet->dhcp, optlen, &optoffset, 0,
+                               DHCP_OPTION_CLIENT_IDENTIFIER,
                                sizeof(client->client_id), &client->client_id);
         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;
+        /* 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.
+         */
+        r = dhcp_option_append(&packet->dhcp, optlen, &optoffset, 0,
+                               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;
-        }
+        /* 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 Messge Size option
+           is explicitely set
+         */
+        max_size = htobe16(size);
+        r = dhcp_option_append(&packet->dhcp, optlen, &optoffset, 0,
+                               DHCP_OPTION_MAXIMUM_MESSAGE_SIZE,
+                               2, &max_size);
+        if (r < 0)
+                return r;
+
+        *_optlen = optlen;
+        *_optoffset = optoffset;
+        *ret = packet;
+        packet = NULL;
 
         return 0;
 }
@@ -294,12 +348,15 @@ static int dhcp_client_send_raw(sd_dhcp_client *client, DHCPPacket *packet,
 
 static int client_send_discover(sd_dhcp_client *client) {
         _cleanup_free_ DHCPPacket *discover = NULL;
-        size_t optlen, len;
-        uint8_t *opt;
+        size_t optoffset, optlen;
         usec_t time_now;
         int r;
 
         assert(client);
+        assert(client->state == DHCP_STATE_INIT ||
+               client->state == DHCP_STATE_SELECTING);
+
+        /* See RFC2131 section 4.4.1 */
 
         r = sd_event_now(client->event, CLOCK_MONOTONIC, &time_now);
         if (r < 0)
@@ -310,31 +367,35 @@ static int client_send_discover(sd_dhcp_client *client) {
          * must always be strictly positive to deal with broken servers */
         client->secs = ((time_now - client->start_time) / USEC_PER_SEC) ? : 1;
 
-        optlen = DHCP_MIN_OPTIONS_SIZE;
-        len = sizeof(DHCPPacket) + optlen;
-
-        discover = malloc0(len);
-        if (!discover)
-                return -ENOMEM;
-
-        r = client_message_init(client, &discover->dhcp, DHCP_DISCOVER,
-                                &opt, &optlen);
+        r = client_message_init(client, &discover, DHCP_DISCOVER,
+                                &optlen, &optoffset);
         if (r < 0)
                 return r;
 
+        /* the client may suggest values for the network address
+           and lease time in the DHCPDISCOVER message. The client may include
+           the ’requested IP address’ option to suggest that a particular IP
+           address be assigned, and may include the ’IP address lease time’
+           option to suggest the lease time it would like.
+         */
         if (client->last_addr != INADDR_ANY) {
-                r = dhcp_option_append(&opt, &optlen,
-                                         DHCP_OPTION_REQUESTED_IP_ADDRESS,
-                                         4, &client->last_addr);
+                r = dhcp_option_append(&discover->dhcp, optlen, &optoffset, 0,
+                                       DHCP_OPTION_REQUESTED_IP_ADDRESS,
+                                       4, &client->last_addr);
                 if (r < 0)
                         return r;
         }
 
-        r = dhcp_option_append(&opt, &optlen, DHCP_OPTION_END, 0, NULL);
+        r = dhcp_option_append(&discover->dhcp, optlen, &optoffset, 0,
+                               DHCP_OPTION_END, 0, NULL);
         if (r < 0)
                 return r;
 
-        r = dhcp_client_send_raw(client, discover, len - optlen);
+        /* 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;
 
@@ -344,58 +405,80 @@ static int client_send_discover(sd_dhcp_client *client) {
 }
 
 static int client_send_request(sd_dhcp_client *client) {
-        _cleanup_free_ DHCPPacket *request;
-        size_t optlen, len;
-        uint8_t *opt;
+        _cleanup_free_ DHCPPacket *request = NULL;
+        size_t optoffset, optlen;
         int r;
 
-        optlen = DHCP_MIN_OPTIONS_SIZE;
-        len = sizeof(DHCPPacket) + optlen;
-
-        request = malloc0(len);
-        if (!request)
-                return -ENOMEM;
-
-        r = client_message_init(client, &request->dhcp, DHCP_REQUEST, &opt,
-                                &optlen);
+        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_INIT_REBOOT:
-                r = dhcp_option_append(&opt, &optlen,
-                                         DHCP_OPTION_REQUESTED_IP_ADDRESS,
-                                         4, &client->last_addr);
+        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,
+                                       DHCP_OPTION_SERVER_IDENTIFIER,
+                                       4, &client->lease->server_address);
                 if (r < 0)
                         return r;
-                break;
 
-        case DHCP_STATE_REQUESTING:
-                r = dhcp_option_append(&opt, &optlen,
+                r = dhcp_option_append(&request->dhcp, optlen, &optoffset, 0,
                                        DHCP_OPTION_REQUESTED_IP_ADDRESS,
                                        4, &client->lease->address);
                 if (r < 0)
                         return r;
 
-                r = dhcp_option_append(&opt, &optlen,
-                                       DHCP_OPTION_SERVER_IDENTIFIER,
-                                       4, &client->lease->server_address);
+                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,
+                                       DHCP_OPTION_REQUESTED_IP_ADDRESS,
+                                       4, &client->last_addr);
                 if (r < 0)
                         return r;
                 break;
 
-        case DHCP_STATE_INIT:
-        case DHCP_STATE_SELECTING:
-        case DHCP_STATE_REBOOTING:
-        case DHCP_STATE_BOUND:
         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.
+                */
+
+                /* fall through */
         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 = dhcp_option_append(&opt, &optlen, DHCP_OPTION_END, 0, NULL);
+        r = dhcp_option_append(&request->dhcp, optlen, &optoffset, 0,
+                               DHCP_OPTION_END, 0, NULL);
         if (r < 0)
                 return r;
 
@@ -404,21 +487,40 @@ static int client_send_request(sd_dhcp_client *client) {
                                                  client->lease->server_address,
                                                  DHCP_PORT_SERVER,
                                                  &request->dhcp,
-                                                 len - optlen - DHCP_IP_UDP_SIZE);
+                                                 sizeof(DHCPMessage) + optoffset);
         } else {
-                r = dhcp_client_send_raw(client, request, len - optlen);
+                r = dhcp_client_send_raw(client, request, sizeof(DHCPPacket) + optoffset);
         }
         if (r < 0)
                 return r;
 
-        log_dhcp_client(client, "REQUEST");
+        switch (client->state) {
+        case DHCP_STATE_REQUESTING:
+                log_dhcp_client(client, "REQUEST (requesting)");
+                break;
+        case DHCP_STATE_INIT_REBOOT:
+                log_dhcp_client(client, "REQUEST (init-reboot)");
+                break;
+        case DHCP_STATE_RENEWING:
+                log_dhcp_client(client, "REQUEST (renewing)");
+                break;
+        case DHCP_STATE_REBINDING:
+                log_dhcp_client(client, "REQUEST (rebinding)");
+                break;
+        default:
+                log_dhcp_client(client, "REQUEST (invalid)");
+                break;
+        }
 
         return 0;
 }
 
+static int client_start(sd_dhcp_client *client);
+
 static int client_timeout_resend(sd_event_source *s, uint64_t usec,
                                  void *userdata) {
         sd_dhcp_client *client = userdata;
+        DHCP_CLIENT_DONT_DESTROY(client);
         usec_t next_timeout = 0;
         uint64_t time_now;
         uint32_t time_left;
@@ -454,11 +556,18 @@ static int client_timeout_resend(sd_event_source *s, uint64_t usec,
 
         case DHCP_STATE_REBOOTING:
                 /* start over as we did not receive a timely ack or nak */
-                client->state = DHCP_STATE_INIT;
-                client->attempt = 1;
-                client->xid = random_u32();
+                r = client_initialize(client);
+                if (r < 0)
+                        goto error;
+
+                r = client_start(client);
+                if (r < 0)
+                        goto error;
+                else {
+                        log_dhcp_client(client, "REBOOTED");
+                        return 0;
+                }
 
-                /* fall through */
         case DHCP_STATE_INIT:
         case DHCP_STATE_INIT_REBOOT:
         case DHCP_STATE_SELECTING:
@@ -471,6 +580,10 @@ static int client_timeout_resend(sd_event_source *s, uint64_t usec,
                 next_timeout = time_now + (client->attempt - 1) * USEC_PER_SEC;
 
                 break;
+
+        case DHCP_STATE_STOPPED:
+                r = -EINVAL;
+                goto error;
         }
 
         next_timeout += (random_u32() & 0x1fffff);
@@ -529,6 +642,10 @@ static int client_timeout_resend(sd_event_source *s, uint64_t usec,
         case DHCP_STATE_BOUND:
 
                 break;
+
+        case DHCP_STATE_STOPPED:
+                r = -EINVAL;
+                goto error;
         }
 
         return 0;
@@ -593,8 +710,7 @@ static int client_start(sd_dhcp_client *client) {
 
         client->xid = random_u32();
 
-        r = dhcp_network_bind_raw_socket(client->index, &client->link);
-
+        r = dhcp_network_bind_raw_socket(client->index, &client->link, client->xid);
         if (r < 0) {
                 client_stop(client, r);
                 return r;
@@ -606,59 +722,58 @@ static int client_start(sd_dhcp_client *client) {
                 client->secs = 0;
         }
 
-        log_dhcp_client(client, "STARTED");
-
         return client_initialize_events(client, client_receive_message_raw);
 }
 
 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, DHCP_EVENT_EXPIRED);
 
-        /* start over as the lease was lost */
-        client_initialize(client);
-        client_start(client);
+        /* lease was lost, start over if not freed or stopped in callback */
+        if (client->state != DHCP_STATE_STOPPED) {
+                client_initialize(client);
+                client_start(client);
+        }
 
         return 0;
 }
 
 static int client_timeout_t2(sd_event_source *s, uint64_t usec, void *userdata) {
         sd_dhcp_client *client = userdata;
+        DHCP_CLIENT_DONT_DESTROY(client);
         int r;
 
         client->receive_message = sd_event_source_unref(client->receive_message);
-        client->fd = safe_close(client->fd);
+        client->fd = asynchronous_close(client->fd);
 
         client->state = DHCP_STATE_REBINDING;
         client->attempt = 1;
 
-        r = dhcp_network_bind_raw_socket(client->index, &client->link);
+        r = dhcp_network_bind_raw_socket(client->index, &client->link, client->xid);
         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);
 }
 
 static int client_timeout_t1(sd_event_source *s, uint64_t usec,
                              void *userdata) {
         sd_dhcp_client *client = userdata;
+        DHCP_CLIENT_DONT_DESTROY(client);
         int r;
 
         client->state = DHCP_STATE_RENEWING;
         client->attempt = 1;
 
-        r = dhcp_network_bind_udp_socket(client->index,
-                                         client->lease->address,
+        r = dhcp_network_bind_udp_socket(client->lease->address,
                                          DHCP_PORT_CLIENT);
         if (r < 0) {
                 client_stop(client, r);
@@ -667,8 +782,6 @@ static int client_timeout_t1(sd_event_source *s, uint64_t usec,
 
         client->fd = r;
 
-        log_dhcp_client(client, "TIMEOUT T1");
-
         return client_initialize_events(client, client_receive_message_udp);
 }
 
@@ -709,6 +822,7 @@ static int client_handle_offer(sd_dhcp_client *client, DHCPMessage *offer,
                 }
         }
 
+        sd_dhcp_lease_unref(client->lease);
         client->lease = lease;
         lease = NULL;
 
@@ -925,6 +1039,7 @@ static int client_set_lease_timeouts(sd_dhcp_client *client) {
 
 static int client_handle_message(sd_dhcp_client *client, DHCPMessage *message,
                                  int len) {
+        DHCP_CLIENT_DONT_DESTROY(client);
         int r = 0, notify_event = 0;
 
         assert(client);
@@ -1009,6 +1124,8 @@ static int client_handle_message(sd_dhcp_client *client, DHCPMessage *message,
                                 r = client_start(client);
                                 if (r < 0)
                                         goto error;
+
+                                log_dhcp_client(client, "REBOOTED");
                         }
 
                         goto error;
@@ -1031,12 +1148,15 @@ static int client_handle_message(sd_dhcp_client *client, DHCPMessage *message,
                         if (r < 0)
                                 goto error;
 
-                        if (notify_event)
+                        if (notify_event) {
                                 client_notify(client, notify_event);
+                                if (client->state == DHCP_STATE_STOPPED)
+                                        return 0;
+                        }
 
                         client->receive_message =
                                 sd_event_source_unref(client->receive_message);
-                        client->fd = safe_close(client->fd);
+                        client->fd = asynchronous_close(client->fd);
                 } else if (r == -ENOMSG)
                         /* invalid message, let's ignore it */
                         return 0;
@@ -1048,13 +1168,17 @@ static int client_handle_message(sd_dhcp_client *client, DHCPMessage *message,
         case DHCP_STATE_BOUND:
 
                 break;
+
+        case DHCP_STATE_STOPPED:
+                r = -EINVAL;
+                goto error;
         }
 
 error:
         if (r < 0 || r == DHCP_EVENT_NO_LEASE)
-                return client_stop(client, r);
+                client_stop(client, r);
 
-        return 0;
+        return r;
 }
 
 static int client_receive_message_udp(sd_event_source *s, int fd,
@@ -1067,8 +1191,12 @@ static int client_receive_message_udp(sd_event_source *s, int fd,
         assert(client);
 
         r = ioctl(fd, FIONREAD, &buflen);
-        if (r < 0 || buflen <= 0)
-                buflen = sizeof(DHCPMessage) + DHCP_MIN_OPTIONS_SIZE;
+        if (r < 0)
+                return r;
+
+        if (buflen < 0)
+                /* this can't be right */
+                return -EIO;
 
         message = malloc0(buflen);
         if (!message)
@@ -1077,7 +1205,7 @@ static int client_receive_message_udp(sd_event_source *s, int fd,
         len = read(fd, message, buflen);
         if (len < 0) {
                 log_dhcp_client(client, "could not receive message from UDP "
-                                "socket: %s", strerror(errno));
+                                "socket: %m");
                 return 0;
         } else if ((size_t)len < sizeof(DHCPMessage))
                 return 0;
@@ -1105,8 +1233,12 @@ static int client_receive_message_raw(sd_event_source *s, int fd,
         assert(client);
 
         r = ioctl(fd, FIONREAD, &buflen);
-        if (r < 0 || buflen <= 0)
-                buflen = sizeof(DHCPPacket) + DHCP_MIN_OPTIONS_SIZE;
+        if (r < 0)
+                return r;
+
+        if (buflen < 0)
+                /* this can't be right */
+                return -EIO;
 
         packet = malloc0(buflen);
         if (!packet)
@@ -1118,14 +1250,16 @@ static int client_receive_message_raw(sd_event_source *s, int fd,
         len = recvmsg(fd, &msg, 0);
         if (len < 0) {
                 log_dhcp_client(client, "could not receive message from raw "
-                                "socket: %s", strerror(errno));
+                                "socket: %m");
                 return 0;
         } else if ((size_t)len < sizeof(DHCPPacket))
                 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);
+                if (cmsg->cmsg_level == SOL_PACKET &&
+                    cmsg->cmsg_type == PACKET_AUXDATA &&
+                    cmsg->cmsg_len == CMSG_LEN(sizeof(struct tpacket_auxdata))) {
+                        struct tpacket_auxdata *aux = (struct tpacket_auxdata*)CMSG_DATA(cmsg);
 
                         checksum = !(aux->tp_status & TP_STATUS_CSUMNOTREADY);
                         break;
@@ -1153,11 +1287,24 @@ int sd_dhcp_client_start(sd_dhcp_client *client) {
         if (client->last_addr)
                 client->state = DHCP_STATE_INIT_REBOOT;
 
-        return client_start(client);
+        r = client_start(client);
+        if (r >= 0)
+                log_dhcp_client(client, "STARTED on ifindex %u with address %s",
+                                client->index,
+                                ether_ntoa(&client->client_id.mac_addr));
+
+        return r;
 }
 
 int sd_dhcp_client_stop(sd_dhcp_client *client) {
-        return client_stop(client, DHCP_EVENT_STOP);
+        DHCP_CLIENT_DONT_DESTROY(client);
+
+        assert_return(client, -EINVAL);
+
+        client_stop(client, DHCP_EVENT_STOP);
+        client->state = DHCP_STATE_STOPPED;
+
+        return 0;
 }
 
 int sd_dhcp_client_attach_event(sd_dhcp_client *client, sd_event *event,
@@ -1195,22 +1342,35 @@ sd_event *sd_dhcp_client_get_event(sd_dhcp_client *client) {
         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);
+sd_dhcp_client *sd_dhcp_client_ref(sd_dhcp_client *client) {
+        if (client)
+                assert_se(REFCNT_INC(client->n_ref) >= 2);
 
-        free(client->req_opts);
-        free(client);
+        return client;
 }
 
-DEFINE_TRIVIAL_CLEANUP_FUNC(sd_dhcp_client*, sd_dhcp_client_free);
-#define _cleanup_dhcp_client_free_ _cleanup_(sd_dhcp_client_freep)
+sd_dhcp_client *sd_dhcp_client_unref(sd_dhcp_client *client) {
+        if (client && REFCNT_DEC(client->n_ref) <= 0) {
+                log_dhcp_client(client, "FREE");
+
+                client_initialize(client);
+
+                client->receive_message =
+                        sd_event_source_unref(client->receive_message);
+
+                sd_dhcp_client_detach_event(client);
+
+                sd_dhcp_lease_unref(client->lease);
+
+                free(client->req_opts);
+                free(client);
+        }
+
+        return NULL;
+}
 
 int sd_dhcp_client_new(sd_dhcp_client **ret) {
-        _cleanup_dhcp_client_free_ sd_dhcp_client *client = NULL;
+        _cleanup_dhcp_client_unref_ sd_dhcp_client *client = NULL;
 
         assert_return(ret, -EINVAL);
 
@@ -1218,6 +1378,7 @@ int sd_dhcp_client_new(sd_dhcp_client **ret) {
         if (!client)
                 return -ENOMEM;
 
+        client->n_ref = REFCNT_INIT;
         client->state = DHCP_STATE_INIT;
         client->index = -1;
         client->fd = -1;