summaryrefslogtreecommitdiff
path: root/src/libsystemd-network/sd-dhcp-client.c
blob: 392e294ae43e27fe404c30c03542347e201eb99b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
/***
  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 <net/if_arp.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 {
                uint8_t type;
                struct ether_addr mac_addr;
        } _packed_ client_id;
        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) {
        bool need_restart = false;

        assert_return(client, -EINVAL);
        assert_return(addr, -EINVAL);

        if (memcmp(&client->client_id.mac_addr, addr, ETH_ALEN) == 0)
                return 0;

        if (client->state != DHCP_STATE_INIT) {
                log_dhcp_client(client, "Changing MAC address on running DHCP "
                                "client, restarting");
                sd_dhcp_client_stop(client);
                need_restart = true;
        }

        memcpy(&client->client_id.mac_addr, addr, ETH_ALEN);
        client->client_id.type = 0x01;

        if (need_restart)
                sd_dhcp_client_start(client);

        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_initialize(sd_dhcp_client *client) {
        assert_return(client, -EINVAL);

        client->receive_message =
                sd_event_source_unref(client->receive_message);

        client->fd = safe_close(client->fd);

        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->state = DHCP_STATE_INIT;
        client->xid = 0;

        if (client->lease)
                client->lease = sd_dhcp_lease_unref(client->lease);

        return 0;
}

static int client_stop(sd_dhcp_client *client, int error) {
        assert_return(client, -EINVAL);

        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) {
        int r;

        assert(client);
        assert(client->secs);
        assert(message);
        assert(opt);
        assert(optlen);

        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(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;

        /* 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,
                               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;

                /* 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 dhcp_client_send_raw(sd_dhcp_client *client, DHCPPacket *packet,
                                size_t len) {
        dhcp_packet_append_ip_headers(packet, INADDR_ANY, DHCP_PORT_CLIENT,
                                      INADDR_BROADCAST, DHCP_PORT_SERVER, len);

        return dhcp_network_send_raw_socket(client->fd, &client->link,
                                            packet, len);
}

static int client_send_discover(sd_dhcp_client *client) {
        _cleanup_free_ DHCPPacket *discover = NULL;
        size_t optlen, len;
        uint8_t *opt;
        usec_t time_now;
        int r;

        assert(client);

        r = sd_event_now(client->event, CLOCK_MONOTONIC, &time_now);
        if (r < 0)
                return r;
        assert(time_now >= client->start_time);

        /* seconds between sending first and last DISCOVER
         * must always be strictly positive to deal with broken servers */
        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);
        if (r < 0)
                return r;

        if (client->last_addr != INADDR_ANY) {
                r = dhcp_option_append(&opt, &optlen,
                                         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);
        if (r < 0)
                return r;

        r = dhcp_client_send_raw(client, discover, len - optlen);
        if (r < 0)
                return r;

        log_dhcp_client(client, "DISCOVER");

        return 0;
}

static int client_send_request(sd_dhcp_client *client) {
        _cleanup_free_ DHCPPacket *request;
        size_t optlen, len;
        uint8_t *opt;
        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);
        if (r < 0)
                return r;

        switch (client->state) {

        case DHCP_STATE_INIT_REBOOT:
                r = dhcp_option_append(&opt, &optlen,
                                         DHCP_OPTION_REQUESTED_IP_ADDRESS,
                                         4, &client->last_addr);
                if (r < 0)
                        return r;
                break;

        case DHCP_STATE_REQUESTING:
                r = dhcp_option_append(&opt, &optlen,
                                       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);
                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:
        case DHCP_STATE_REBINDING:

                break;
        }

        r = dhcp_option_append(&opt, &optlen, DHCP_OPTION_END, 0, NULL);
        if (r < 0)
                return r;

        if (client->state == DHCP_STATE_RENEWING) {
                r = dhcp_network_send_udp_socket(client->fd,
                                                 client->lease->server_address,
                                                 DHCP_PORT_SERVER,
                                                 &request->dhcp,
                                                 len - optlen - DHCP_IP_UDP_SIZE);
        } else {
                r = dhcp_client_send_raw(client, request, len - optlen);
        }
        if (r < 0)
                return r;

        log_dhcp_client(client, "REQUEST");

        return 0;
}

static int client_timeout_resend(sd_event_source *s, uint64_t usec,
                                 void *userdata) {
        sd_dhcp_client *client = userdata;
        usec_t next_timeout = 0;
        uint64_t time_now;
        uint32_t time_left;
        int r;

        assert(s);
        assert(client);
        assert(client->event);

        r = sd_event_now(client->event, CLOCK_MONOTONIC, &time_now);
        if (r < 0)
                goto error;

        switch (client->state) {
        case DHCP_STATE_RENEWING:

                time_left = (client->lease->t2 - client->lease->t1) / 2;
                if (time_left < 60)
                        time_left = 60;

                next_timeout = time_now + time_left * USEC_PER_SEC;

                break;

        case DHCP_STATE_REBINDING:

                time_left = (client->lease->lifetime - client->lease->t2) / 2;
                if (time_left < 60)
                        time_left = 60;

                next_timeout = time_now + time_left * USEC_PER_SEC;
                break;

        case DHCP_STATE_REBOOTING:
                /* start over as we did not receive a timely ack or nak */
                client->state = DHCP_STATE_INIT;
                client->attempt = 1;
                client->xid = random_u32();

                /* fall through */
        case DHCP_STATE_INIT:
        case DHCP_STATE_INIT_REBOOT:
        case DHCP_STATE_SELECTING:
        case DHCP_STATE_REQUESTING:
        case DHCP_STATE_BOUND:

                if (client->attempt < 64)
                        client->attempt *= 2;

                next_timeout = time_now + (client->attempt - 1) * USEC_PER_SEC;

                break;
        }

        next_timeout += (random_u32() & 0x1fffff);

        client->timeout_resend = sd_event_source_unref(client->timeout_resend);

        r = sd_event_add_time(client->event,
                              &client->timeout_resend,
                              CLOCK_MONOTONIC,
                              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:
                r = client_send_discover(client);
                if (r >= 0) {
                        client->state = DHCP_STATE_SELECTING;
                        client->attempt = 1;
                } else {
                        if (client->attempt >= 64)
                                goto error;
                }

                break;

        case DHCP_STATE_SELECTING:
                r = client_send_discover(client);
                if (r < 0 && client->attempt >= 64)
                        goto error;

                break;

        case DHCP_STATE_INIT_REBOOT:
        case DHCP_STATE_REQUESTING:
        case DHCP_STATE_RENEWING:
        case DHCP_STATE_REBINDING:
                r = client_send_request(client);
                if (r < 0 && client->attempt >= 64)
                         goto error;

                if (client->state == DHCP_STATE_INIT_REBOOT)
                        client->state = DHCP_STATE_REBOOTING;

                client->request_sent = time_now;

                break;

        case DHCP_STATE_REBOOTING:
        case DHCP_STATE_BOUND:

                break;
        }

        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) {
        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_time(client->event,
                              &client->timeout_resend,
                              CLOCK_MONOTONIC,
                              0, 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_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->fd < 0, -EBUSY);
        assert_return(client->xid == 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, client->xid);

        if (r < 0) {
                client_stop(client, r);
                return r;
        }
        client->fd = r;

        if (client->state == DHCP_STATE_INIT) {
                client->start_time = now(CLOCK_MONOTONIC);
                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;

        log_dhcp_client(client, "EXPIRED");

        client_notify(client, DHCP_EVENT_EXPIRED);

        /* start over as the lease was lost */
        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;
        int r;

        client->receive_message = sd_event_source_unref(client->receive_message);
        client->fd = safe_close(client->fd);

        client->state = DHCP_STATE_REBINDING;
        client->attempt = 1;

        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;
        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);
}

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) {
                log_dhcp_client(client, "receieved message was not an OFFER, ignoring");
                return -ENOMSG;
        }

        lease->next_server = offer->siaddr;

        lease->address = offer->yiaddr;

        if (lease->address == INADDR_ANY ||
            lease->server_address == INADDR_ANY ||
            lease->lifetime == 0) {
                log_dhcp_client(client, "receieved lease lacks address, server "
                                "address or lease lifetime, ignoring");
                return -ENOMSG;
        }

        if (lease->subnet_mask == INADDR_ANY) {
                r = dhcp_lease_set_default_subnet_mask(lease);
                if (r < 0) {
                        log_dhcp_client(client, "receieved lease lacks subnet "
                                        "mask, and a fallback one can not be "
                                        "generated, ignoring");
                        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) {
                log_dhcp_client(client, "receieved message was not an ACK, ignoring");
                return -ENOMSG;
        }

        lease->next_server = ack->siaddr;

        lease->address = ack->yiaddr;

        if (lease->address == INADDR_ANY ||
            lease->server_address == INADDR_ANY ||
            lease->lifetime == 0) {
                log_dhcp_client(client, "receieved lease lacks address, server "
                                "address or lease lifetime, ignoring");
                return -ENOMSG;
        }

        if (lease->subnet_mask == INADDR_ANY) {
                r = dhcp_lease_set_default_subnet_mask(lease);
                if (r < 0) {
                        log_dhcp_client(client, "receieved lease lacks subnet "
                                        "mask, and a fallback one can not be "
                                        "generated, ignoring");
                        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(sd_dhcp_client *client,
                                       uint32_t lifetime, double factor) {
        assert(client);
        assert(client->request_sent);
        assert(lifetime);

        return client->request_sent + ((lifetime - 3) * USEC_PER_SEC * factor) +
                + (random_u32() & 0x1fffff);
}

static int client_set_lease_timeouts(sd_dhcp_client *client) {
        usec_t time_now;
        uint64_t lifetime_timeout;
        uint64_t t2_timeout;
        uint64_t t1_timeout;
        char time_string[FORMAT_TIMESPAN_MAX];
        int r;

        assert(client);
        assert(client->event);
        assert(client->lease);
        assert(client->lease->lifetime);

        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);

        /* don't set timers for infinite leases */
        if (client->lease->lifetime == 0xffffffff)
                return 0;

        r = sd_event_now(client->event, CLOCK_MONOTONIC, &time_now);
        if (r < 0)
                return r;
        assert(client->request_sent <= time_now);

        /* convert the various timeouts from relative (secs) to absolute (usecs) */
        lifetime_timeout = client_compute_timeout(client, client->lease->lifetime, 1);
        if (client->lease->t1 && client->lease->t2) {
                /* both T1 and T2 are given */
                if (client->lease->t1 < client->lease->t2 &&
                    client->lease->t2 < client->lease->lifetime) {
                        /* they are both valid */
                        t2_timeout = client_compute_timeout(client, client->lease->t2, 1);
                        t1_timeout = client_compute_timeout(client, client->lease->t1, 1);
                } else {
                        /* discard both */
                        t2_timeout = client_compute_timeout(client, client->lease->lifetime, 7.0 / 8.0);
                        client->lease->t2 = (client->lease->lifetime * 7) / 8;
                        t1_timeout = client_compute_timeout(client, client->lease->lifetime, 0.5);
                        client->lease->t1 = client->lease->lifetime / 2;
                }
        } else if (client->lease->t2 && client->lease->t2 < client->lease->lifetime) {
                /* only T2 is given, and it is valid */
                t2_timeout = client_compute_timeout(client, client->lease->t2, 1);
                t1_timeout = client_compute_timeout(client, client->lease->lifetime, 0.5);
                client->lease->t1 = client->lease->lifetime / 2;
                if (t2_timeout <= t1_timeout) {
                        /* the computed T1 would be invalid, so discard T2 */
                        t2_timeout = client_compute_timeout(client, client->lease->lifetime, 7.0 / 8.0);
                        client->lease->t2 = (client->lease->lifetime * 7) / 8;
                }
        } else if (client->lease->t1 && client->lease->t1 < client->lease->lifetime) {
                /* only T1 is given, and it is valid */
                t1_timeout = client_compute_timeout(client, client->lease->t1, 1);
                t2_timeout = client_compute_timeout(client, client->lease->lifetime, 7.0 / 8.0);
                client->lease->t2 = (client->lease->lifetime * 7) / 8;
                if (t2_timeout <= t1_timeout) {
                        /* the computed T2 would be invalid, so discard T1 */
                        t2_timeout = client_compute_timeout(client, client->lease->lifetime, 0.5);
                        client->lease->t2 = client->lease->lifetime / 2;
                }
        } else {
                /* fall back to the default timeouts */
                t1_timeout = client_compute_timeout(client, client->lease->lifetime, 0.5);
                client->lease->t1 = client->lease->lifetime / 2;
                t2_timeout = client_compute_timeout(client, client->lease->lifetime, 7.0 / 8.0);
                client->lease->t2 = (client->lease->lifetime * 7) / 8;
        }

        /* arm lifetime timeout */
        r = sd_event_add_time(client->event, &client->timeout_expire,
                              CLOCK_MONOTONIC,
                              lifetime_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;

        log_dhcp_client(client, "lease expires in %s",
                        format_timespan(time_string, FORMAT_TIMESPAN_MAX,
                        lifetime_timeout - time_now, 0));

        /* don't arm earlier timeouts if this has already expired */
        if (lifetime_timeout <= time_now)
                return 0;

        /* arm T2 timeout */
        r = sd_event_add_time(client->event,
                              &client->timeout_t2,
                              CLOCK_MONOTONIC,
                              t2_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;

        log_dhcp_client(client, "T2 expires in %s",
                        format_timespan(time_string, FORMAT_TIMESPAN_MAX,
                        t2_timeout - time_now, 0));

        /* don't arm earlier timeout if this has already expired */
        if (t2_timeout <= time_now)
                return 0;

        /* arm T1 timeout */
        r = sd_event_add_time(client->event,
                              &client->timeout_t1,
                              CLOCK_MONOTONIC,
                              t1_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;

        log_dhcp_client(client, "T1 expires in %s",
                        format_timespan(time_string, FORMAT_TIMESPAN_MAX,
                        t1_timeout - time_now, 0));

        return 0;
}

static int client_handle_message(sd_dhcp_client *client, DHCPMessage *message,
                                 int len) {
        int r = 0, notify_event = 0;

        assert(client);
        assert(client->event);
        assert(message);

        if (be32toh(message->magic) != DHCP_MAGIC_COOKIE) {
                log_dhcp_client(client, "not a DHCP message: ignoring");
                return 0;
        }

        if (message->op != BOOTREPLY) {
                log_dhcp_client(client, "not a BOOTREPLY message: ignoring");
                return 0;
        }

        if (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 (message->htype != ARPHRD_ETHER || message->hlen != ETHER_ADDR_LEN) {
                log_dhcp_client(client, "not an ethernet packet");
                return 0;
        }

        if (memcmp(&message->chaddr[0], &client->client_id.mac_addr,
                   ETH_ALEN)) {
                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_time(client->event,
                                              &client->timeout_resend,
                                              CLOCK_MONOTONIC,
                                              0, 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;
                } else if (r == -ENOMSG)
                        /* invalid message, let's ignore it */
                        return 0;

                break;

        case DHCP_STATE_REBOOTING:
        case DHCP_STATE_REQUESTING:
        case DHCP_STATE_RENEWING:
        case DHCP_STATE_REBINDING:

                r = client_handle_ack(client, message, len);
                if (r == DHCP_EVENT_NO_LEASE) {

                        client->timeout_resend =
                                sd_event_source_unref(client->timeout_resend);

                        if (client->state == DHCP_STATE_REBOOTING) {
                                r = client_initialize(client);
                                if (r < 0)
                                        goto error;

                                r = client_start(client);
                                if (r < 0)
                                        goto error;
                        }

                        goto error;
                } else if (r >= 0) {
                        client->timeout_resend =
                                sd_event_source_unref(client->timeout_resend);

                        if (IN_SET(client->state, DHCP_STATE_REQUESTING,
                                   DHCP_STATE_REBOOTING))
                                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);
                        if (r < 0)
                                goto error;

                        if (notify_event)
                                client_notify(client, notify_event);

                        client->receive_message =
                                sd_event_source_unref(client->receive_message);
                        client->fd = safe_close(client->fd);
                } else if (r == -ENOMSG)
                        /* invalid message, let's ignore it */
                        return 0;

                break;

        case DHCP_STATE_INIT:
        case DHCP_STATE_INIT_REBOOT:
        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;

        assert(s);
        assert(client);

        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) {
                log_dhcp_client(client, "could not receive message from UDP "
                                "socket: %s", strerror(errno));
                return 0;
        } else if ((size_t)len < sizeof(DHCPMessage))
                return 0;

        return client_handle_message(client, message, len);
}

static int client_receive_message_raw(sd_event_source *s, int fd,
                                      uint32_t revents, void *userdata) {
        sd_dhcp_client *client = userdata;
        _cleanup_free_ DHCPPacket *packet = NULL;
        uint8_t cmsgbuf[CMSG_LEN(sizeof(struct tpacket_auxdata))];
        struct iovec iov = {};
        struct msghdr msg = {
                .msg_iov = &iov,
                .msg_iovlen = 1,
                .msg_control = cmsgbuf,
                .msg_controllen = sizeof(cmsgbuf),
        };
        struct cmsghdr *cmsg;
        bool checksum = true;
        int buflen = 0, len, r;

        assert(s);
        assert(client);

        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;
        } 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 &&
                    cmsg->cmsg_len == CMSG_LEN(sizeof(struct tpacket_auxdata))) {
                        struct tpacket_auxdata *aux = (struct tpacket_auxdata*)CMSG_DATA(cmsg);

                        checksum = !(aux->tp_status & TP_STATUS_CSUMNOTREADY);
                        break;
                }
        }

        r = dhcp_packet_verify_headers(packet, len, checksum);
        if (r < 0)
                return 0;

        len -= DHCP_IP_UDP_SIZE;

        return client_handle_message(client, &packet->dhcp, len);
}

int sd_dhcp_client_start(sd_dhcp_client *client) {
        int r;

        assert_return(client, -EINVAL);

        r = client_initialize(client);
        if (r < 0)
                return r;

        if (client->last_addr)
                client->state = DHCP_STATE_INIT_REBOOT;

        return client_start(client);
}

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;
}