kdc/announce.c

   1 /*
   2  * Copyright (c) 2008 Apple Inc.  All Rights Reserved.
   3  *
   4  * Export of this software from the United States of America may require
   5  * a specific license from the United States Government.  It is the
   6  * responsibility of any person or organization contemplating export to
   7  * obtain such a license before exporting.
   8  *
   9  * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
  10  * distribute this software and its documentation for any purpose and
  11  * without fee is hereby granted, provided that the above copyright
  12  * notice appear in all copies and that both that copyright notice and
  13  * this permission notice appear in supporting documentation, and that
  14  * the name of Apple Inc. not be used in advertising or publicity pertaining
  15  * to distribution of the software without specific, written prior
  16  * permission.  Apple Inc. makes no representations about the suitability of
  17  * this software for any purpose.  It is provided "as is" without express
  18  * or implied warranty.
  19  *
  20  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
  21  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
  22  * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  23  *
  24  */
  25
  26 #ifdef __APPLE__
  27
  28 #include <CoreFoundation/CoreFoundation.h>
  29 #include <SystemConfiguration/SCDynamicStore.h>
  30 #include <SystemConfiguration/SCDynamicStoreCopySpecific.h>
  31 #include <SystemConfiguration/SCDynamicStoreKey.h>
  32
  33 #include <dispatch/dispatch.h>
  34
  35 #include <asl.h>
  36 #include <resolv.h>
  37
  38 #include <dns_sd.h>
  39 #include <err.h>
  40
  41 #include "kdc_locl.h"
  42
  43 static krb5_kdc_configuration *announce_config;
  44 static krb5_context announce_context;
  45
  46 struct entry {
  47     DNSRecordRef recordRef;
  48     char *domain;
  49     char *realm;
  50 #define F_EXISTS 1
  51 #define F_PUSH 2
  52     int flags;
  53     struct entry *next;
  54 };
  55
  56 /* #define REGISTER_SRV_RR */
  57
  58 static struct entry *g_entries = NULL;
  59 static CFStringRef g_hostname = NULL;
  60 static DNSServiceRef g_dnsRef = NULL;
  61 static SCDynamicStoreRef g_store = NULL;
  62 static dispatch_queue_t g_queue = NULL;
  63
  64 #define LOG(...) asl_log(NULL, NULL, ASL_LEVEL_INFO, __VA_ARGS__)
  65
  66 static void create_dns_sd(void);
  67 static void destroy_dns_sd(void);
  68 static void update_all(SCDynamicStoreRef, CFArrayRef, void *);
  69
  70
  71 /* parameters */
  72 static CFStringRef NetworkChangedKey_BackToMyMac = CFSTR("Setup:/Network/BackToMyMac");
  73
  74
  75 static char *
  76 CFString2utf8(CFStringRef string)
  77 {
  78     size_t size;
  79     char *str;
  80
  81     size = 1 + CFStringGetMaximumSizeForEncoding(CFStringGetLength(string), kCFStringEncodingUTF8);
  82     str = malloc(size);
  83     if (str == NULL)
  84         return NULL;
  85
  86     if (CFStringGetCString(string, str, size, kCFStringEncodingUTF8) == false) {
  87         free(str);
  88         return NULL;
  89     }
  90     return str;
  91 }
  92
  93 /*
  94  *
  95  */
  96
  97 static void
  98 retry_timer(void)
  99 {
 100     dispatch_source_t s;
 101     dispatch_time_t t;
 102
 103     s = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER,
 104                                0, 0, g_queue);
 105     t = dispatch_time(DISPATCH_TIME_NOW, 5ull * NSEC_PER_SEC);
 106     dispatch_source_set_timer(s, t, 0, NSEC_PER_SEC);
 107     dispatch_source_set_event_handler(s, ^{
 108             create_dns_sd();
 109             dispatch_release(s);
 110         });
 111     dispatch_resume(s);
 112 }
 113
 114 /*
 115  *
 116  */
 117
 118 static void
 119 create_dns_sd(void)
 120 {
 121     DNSServiceErrorType error;
 122     dispatch_source_t s;
 123
 124     error = DNSServiceCreateConnection(&g_dnsRef);
 125     if (error) {
 126         retry_timer();
 127         return;
 128     }
 129
 130     dispatch_suspend(g_queue);
 131
 132     s = dispatch_source_create(DISPATCH_SOURCE_TYPE_READ,
 133                                DNSServiceRefSockFD(g_dnsRef),
 134                                0, g_queue);
 135
 136     dispatch_source_set_event_handler(s, ^{
 137             DNSServiceErrorType ret = DNSServiceProcessResult(g_dnsRef);
 138             /* on error tear down and set timer to recreate */
 139             if (ret != kDNSServiceErr_NoError && ret != kDNSServiceErr_Transient) {
 140                 dispatch_source_cancel(s);
 141             }
 142         });
 143
 144     dispatch_source_set_cancel_handler(s, ^{
 145             destroy_dns_sd();
 146             retry_timer();
 147             dispatch_release(s);
 148         });
 149
 150     dispatch_resume(s);
 151
 152     /* Do the first update ourself */
 153     update_all(g_store, NULL, NULL);
 154     dispatch_resume(g_queue);
 155 }
 156
 157 static void
 158 domain_add(const char *domain, const char *realm, int flag)
 159 {
 160     struct entry *e;
 161
 162     for (e = g_entries; e != NULL; e = e->next) {
 163         if (strcmp(domain, e->domain) == 0 && strcmp(realm, e->realm) == 0) {
 164             e->flags |= flag;
 165             return;
 166         }
 167     }
 168
 169     LOG("Adding realm %s to domain %s", realm, domain);
 170
 171     e = calloc(1, sizeof(*e));
 172     if (e == NULL)
 173         return;
 174     e->domain = strdup(domain);
 175     e->realm = strdup(realm);
 176     if (e->domain == NULL || e->realm == NULL) {
 177         free(e->domain);
 178         free(e->realm);
 179         free(e);
 180         return;
 181     }
 182     e->flags = flag | F_PUSH; /* if we allocate, we push */
 183     e->next = g_entries;
 184     g_entries = e;
 185 }
 186
 187 struct addctx {
 188     int flags;
 189     const char *realm;
 190 };
 191
 192 static void
 193 domains_add(const void *key, const void *value, void *context)
 194 {
 195     char *str = CFString2utf8((CFStringRef)value);
 196     struct addctx *ctx = context;
 197
 198     if (str == NULL)
 199         return;
 200     if (str[0] != '\0')
 201         domain_add(str, ctx->realm, F_EXISTS | ctx->flags);
 202     free(str);
 203 }
 204
 205
 206 static void
 207 dnsCallback(DNSServiceRef sdRef __attribute__((unused)),
 208             DNSRecordRef RecordRef __attribute__((unused)),
 209             DNSServiceFlags flags __attribute__((unused)),
 210             DNSServiceErrorType errorCode __attribute__((unused)),
 211             void *context __attribute__((unused)))
 212 {
 213 }
 214
 215 #ifdef REGISTER_SRV_RR
 216
 217 /*
 218  * Register DNS SRV rr for the realm.
 219  */
 220
 221 static const char *register_names[2] = {
 222     "_kerberos._tcp",
 223     "_kerberos._udp"
 224 };
 225
 226 static struct {
 227     DNSRecordRef *val;
 228     size_t len;
 229 } srvRefs = { NULL, 0 };
 230
 231 static void
 232 register_srv(const char *realm, const char *hostname, int port)
 233 {
 234     unsigned char target[1024];
 235     int i;
 236     int size;
 237
 238     /* skip registering LKDC realms */
 239     if (strncmp(realm, "LKDC:", 5) == 0)
 240         return;
 241
 242     /* encode SRV-RR */
 243     target[0] = 0; /* priority */
 244     target[1] = 0; /* priority */
 245     target[2] = 0; /* weight */
 246     target[3] = 0; /* weigth */
 247     target[4] = (port >> 8) & 0xff; /* port */
 248     target[5] = (port >> 0) & 0xff; /* port */
 249
 250     size = dn_comp(hostname, target + 6, sizeof(target) - 6, NULL, NULL);
 251     if (size < 0)
 252         return;
 253
 254     size += 6;
 255
 256     LOG("register SRV rr for realm %s hostname %s:%d", realm, hostname, port);
 257
 258     for (i = 0; i < sizeof(register_names)/sizeof(register_names[0]); i++) {
 259         char name[kDNSServiceMaxDomainName];
 260         DNSServiceErrorType error;
 261         void *ptr;
 262
 263         ptr = realloc(srvRefs.val, sizeof(srvRefs.val[0]) * (srvRefs.len + 1));
 264         if (ptr == NULL)
 265             errx(1, "malloc: out of memory");
 266         srvRefs.val = ptr;
 267
 268         DNSServiceConstructFullName(name, NULL, register_names[i], realm);
 269
 270         error = DNSServiceRegisterRecord(g_dnsRef,
 271                                          &srvRefs.val[srvRefs.len],
 272                                          kDNSServiceFlagsUnique | kDNSServiceFlagsShareConnection,
 273                                          0,
 274                                          name,
 275                                          kDNSServiceType_SRV,
 276                                          kDNSServiceClass_IN,
 277                                          size,
 278                                          target,
 279                                          0,
 280                                          dnsCallback,
 281                                          NULL);
 282         if (error) {
 283             LOG("Failed to register SRV rr for realm %s: %d", realm, error);
 284         } else
 285             srvRefs.len++;
 286     }
 287 }
 288
 289 static void
 290 unregister_srv_realms(void)
 291 {
 292     if (g_dnsRef) {
 293         for (i = 0; i < srvRefs.len; i++)
 294             DNSServiceRemoveRecord(g_dnsRef, srvRefs.val[i], 0);
 295     }
 296     free(srvRefs.val);
 297     srvRefs.len = 0;
 298     srvRefs.val = NULL;
 299 }
 300
 301 static void
 302 register_srv_realms(CFStringRef host)
 303 {
 304     krb5_error_code ret;
 305     char *hostname;
 306     size_t i;
 307
 308     /* first unregister old names */
 309
 310     hostname = CFString2utf8(host);
 311     if (hostname == NULL)
 312         return;
 313
 314     for(i = 0; i < announce_config->num_db; i++) {
 315         char **realms, **r;
 316
 317         if (announce_config->db[i]->hdb_get_realms == NULL)
 318             continue;
 319
 320         ret = (announce_config->db[i]->hdb_get_realms)(announce_context, &realms);
 321         if (ret == 0) {
 322             for (r = realms; r && *r; r++)
 323                 register_srv(*r, hostname, 88);
 324             krb5_free_host_realm(announce_context, realms);
 325         }
 326     }
 327
 328     free(hostname);
 329 }
 330 #endif /* REGISTER_SRV_RR */
 331
 332 static void
 333 update_dns(void)
 334 {
 335     DNSServiceErrorType error;
 336     struct entry **e = &g_entries;
 337     char *hostname;
 338
 339     hostname = CFString2utf8(g_hostname);
 340     if (hostname == NULL)
 341         return;
 342
 343     while (*e != NULL) {
 344         /* remove if this wasn't updated */
 345         if (((*e)->flags & F_EXISTS) == 0) {
 346             struct entry *drop = *e;
 347             *e = (*e)->next;
 348
 349             LOG("Deleting realm %s from domain %s",
 350                 drop->realm, drop->domain);
 351
 352             if (drop->recordRef && g_dnsRef)
 353                 DNSServiceRemoveRecord(g_dnsRef, drop->recordRef, 0);
 354             free(drop->domain);
 355             free(drop->realm);
 356             free(drop);
 357             continue;
 358         }
 359         if ((*e)->flags & F_PUSH) {
 360             struct entry *update = *e;
 361             char *dnsdata, *name;
 362             size_t len;
 363
 364             len = strlen(update->realm);
 365             asprintf(&dnsdata, "%c%s", len, update->realm);
 366             if (dnsdata == NULL)
 367                 errx(1, "malloc");
 368
 369             asprintf(&name, "_kerberos.%s.%s", hostname, update->domain);
 370             if (name == NULL)
 371                 errx(1, "malloc");
 372
 373             if (update->recordRef)
 374                 DNSServiceRemoveRecord(g_dnsRef, update->recordRef, 0);
 375
 376             error = DNSServiceRegisterRecord(g_dnsRef,
 377                                              &update->recordRef,
 378                                              kDNSServiceFlagsShared | kDNSServiceFlagsAllowRemoteQuery,
 379                                              0,
 380                                              name,
 381                                              kDNSServiceType_TXT,
 382                                              kDNSServiceClass_IN,
 383                                              len+1,
 384                                              dnsdata,
 385                                              0,
 386                                              dnsCallback,
 387                                              NULL);
 388             free(name);
 389             free(dnsdata);
 390             if (error)
 391                 errx(1, "failure to update entry for %s/%s",
 392                      update->domain, update->realm);
 393         }
 394         e = &(*e)->next;
 395     }
 396     free(hostname);
 397 }
 398
 399 static void
 400 update_entries(SCDynamicStoreRef store, const char *realm, int flags)
 401 {
 402     CFDictionaryRef btmm;
 403
 404     /* we always announce in the local domain */
 405     domain_add("local", realm, F_EXISTS | flags);
 406
 407     /* announce btmm */
 408     btmm = SCDynamicStoreCopyValue(store, NetworkChangedKey_BackToMyMac);
 409     if (btmm) {
 410         struct addctx addctx;
 411
 412         addctx.flags = flags;
 413         addctx.realm = realm;
 414
 415         CFDictionaryApplyFunction(btmm, domains_add, &addctx);
 416         CFRelease(btmm);
 417     }
 418 }
 419
 420 static void
 421 update_all(SCDynamicStoreRef store, CFArrayRef changedKeys, void *info)
 422 {
 423     struct entry *e;
 424     CFStringRef host;
 425     int i, flags = 0;
 426
 427     LOG("something changed, running update");
 428
 429     host = SCDynamicStoreCopyLocalHostName(store);
 430     if (host == NULL)
 431         return;
 432
 433     if (g_hostname == NULL || CFStringCompare(host, g_hostname, 0) != kCFCompareEqualTo) {
 434         if (g_hostname)
 435             CFRelease(g_hostname);
 436         g_hostname = CFRetain(host);
 437         flags = F_PUSH; /* if hostname has changed, force push */
 438
 439 #ifdef REGISTER_SRV_RR
 440         register_srv_realms(g_hostname);
 441 #endif
 442     }
 443
 444     for (e = g_entries; e != NULL; e = e->next)
 445         e->flags &= ~(F_EXISTS|F_PUSH);
 446
 447     for(i = 0; i < announce_config->num_db; i++) {
 448         krb5_error_code ret;
 449         char **realms, **r;
 450
 451         if (announce_config->db[i]->hdb_get_realms == NULL)
 452             continue;
 453
 454         ret = (announce_config->db[i]->hdb_get_realms)(announce_context, announce_config->db[i], &realms);
 455         if (ret == 0) {
 456             for (r = realms; r && *r; r++)
 457                 update_entries(store, *r, flags);
 458             krb5_free_host_realm(announce_context, realms);
 459         }
 460     }
 461
 462     update_dns();
 463
 464     CFRelease(host);
 465 }
 466
 467 static void
 468 delete_all(void)
 469 {
 470     struct entry *e;
 471
 472     for (e = g_entries; e != NULL; e = e->next)
 473         e->flags &= ~(F_EXISTS|F_PUSH);
 474
 475     update_dns();
 476     if (g_entries != NULL)
 477         errx(1, "Failed to remove all bonjour entries");
 478 }
 479
 480 static void
 481 destroy_dns_sd(void)
 482 {
 483     if (g_dnsRef == NULL)
 484         return;
 485
 486     delete_all();
 487 #ifdef REGISTER_SRV_RR
 488     unregister_srv_realms();
 489 #endif
 490
 491     DNSServiceRefDeallocate(g_dnsRef);
 492     g_dnsRef = NULL;
 493 }
 494
 495
 496 static SCDynamicStoreRef
 497 register_notification(void)
 498 {
 499     SCDynamicStoreRef store;
 500     CFStringRef computerNameKey;
 501     CFMutableArrayRef keys;
 502
 503     computerNameKey = SCDynamicStoreKeyCreateHostNames(kCFAllocatorDefault);
 504
 505     store = SCDynamicStoreCreate(kCFAllocatorDefault, CFSTR("Network watcher"),
 506                                  update_all, NULL);
 507     if (store == NULL)
 508         errx(1, "SCDynamicStoreCreate");
 509
 510     keys = CFArrayCreateMutable(kCFAllocatorDefault, 2, &kCFTypeArrayCallBacks);
 511     if (keys == NULL)
 512         errx(1, "CFArrayCreateMutable");
 513
 514     CFArrayAppendValue(keys, computerNameKey);
 515     CFArrayAppendValue(keys, NetworkChangedKey_BackToMyMac);
 516
 517     if (SCDynamicStoreSetNotificationKeys(store, keys, NULL) == false)
 518         errx(1, "SCDynamicStoreSetNotificationKeys");
 519
 520     CFRelease(computerNameKey);
 521     CFRelease(keys);
 522
 523     if (!SCDynamicStoreSetDispatchQueue(store, g_queue))
 524         errx(1, "SCDynamicStoreSetDispatchQueue");
 525
 526     return store;
 527 }
 528
 529 void
 530 bonjour_announce(krb5_context context, krb5_kdc_configuration *config)
 531 {
 532     g_queue = dispatch_queue_create("com.apple.kdc_announce", NULL);
 533     if (!g_queue)
 534         errx(1, "dispatch_queue_create");
 535
 536     g_store = register_notification();
 537     announce_config = config;
 538     announce_context = context;
 539
 540     create_dns_sd();
 541 }
 542
 543 #endif /* __APPLE__ */