src/transport/gnunet-service-transport_validation.c

   1 /*
   2      This file is part of GNUnet.
   3      Copyright (C) 2010-2015 GNUnet e.V.
   4
   5      GNUnet is free software: you can redistribute it and/or modify it
   6      under the terms of the GNU Affero General Public License as published
   7      by the Free Software Foundation, either version 3 of the License,
   8      or (at your option) any later version.
   9
  10      GNUnet is distributed in the hope that it will be useful, but
  11      WITHOUT ANY WARRANTY; without even the implied warranty of
  12      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13      Affero General Public License for more details.
  14
  15      You should have received a copy of the GNU Affero General Public License
  16      along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17
  18      SPDX-License-Identifier: AGPL3.0-or-later
  19  */
  20
  21 /**
  22  * @file transport/gnunet-service-transport_validation.c
  23  * @brief address validation subsystem
  24  * @author Christian Grothoff
  25  */
  26 #include "platform.h"
  27 #include "gnunet-service-transport_ats.h"
  28 #include "gnunet-service-transport_hello.h"
  29 #include "gnunet-service-transport_neighbours.h"
  30 #include "gnunet-service-transport_plugins.h"
  31 #include "gnunet-service-transport_validation.h"
  32 #include "gnunet-service-transport.h"
  33 #include "gnunet_hello_lib.h"
  34 #include "gnunet_ats_service.h"
  35 #include "gnunet_peerinfo_service.h"
  36 #include "gnunet_signatures.h"
  37
  38 /**
  39  * Current state of a validation process.
  40  *
  41  * FIXME: what state is used to indicate that a validation
  42  * was successful? If that is clarified/determined, "UGH" in
  43  * ~gnunetpeerinfogtk.c:1103 should be resolved.
  44  */
  45 enum GNUNET_TRANSPORT_ValidationState {
  46   /**
  47    * Undefined state
  48    *
  49    * Used for final callback indicating operation done
  50    */
  51   GNUNET_TRANSPORT_VS_NONE,
  52
  53   /**
  54    * Fresh validation entry
  55    *
  56    * Entry was just created, no validation process was executed
  57    */
  58   GNUNET_TRANSPORT_VS_NEW,
  59
  60   /**
  61    * Updated validation entry
  62    *
  63    * This is an update for an existing validation entry
  64    */
  65   GNUNET_TRANSPORT_VS_UPDATE,
  66
  67   /**
  68    * Timeout for validation entry
  69    *
  70    * A timeout occured during the validation process
  71    */
  72   GNUNET_TRANSPORT_VS_TIMEOUT,
  73
  74   /**
  75    * Validation entry is removed
  76    *
  77    * The validation entry is getting removed due to a failed validation
  78    */
  79   GNUNET_TRANSPORT_VS_REMOVE
  80 };
  81
  82
  83
  84
  85 /**
  86  * How long is a PONG signature valid?  We'll recycle a signature until
  87  * 1/4 of this time is remaining.  PONGs should expire so that if our
  88  * external addresses change an adversary cannot replay them indefinitely.
  89  * OTOH, we don't want to spend too much time generating PONG signatures,
  90  * so they must have some lifetime to reduce our CPU usage.
  91  */
  92 #define PONG_SIGNATURE_LIFETIME GNUNET_TIME_relative_multiply(GNUNET_TIME_UNIT_HOURS, 1)
  93
  94 /**
  95  * After how long do we expire an address in a HELLO that we just
  96  * validated?  This value is also used for our own addresses when we
  97  * create a HELLO.
  98  */
  99 #define HELLO_ADDRESS_EXPIRATION GNUNET_TIME_relative_multiply(GNUNET_TIME_UNIT_HOURS, 12)
 100
 101 /**
 102  * How often do we allow PINGing an address that we have not yet
 103  * validated?  This also determines how long we track an address that
 104  * we cannot validate (because after this time we can destroy the
 105  * validation record).
 106  */
 107 #define UNVALIDATED_PING_KEEPALIVE GNUNET_TIME_relative_multiply(GNUNET_TIME_UNIT_MINUTES, 5)
 108
 109 /**
 110  * How often do we PING an address that we have successfully validated
 111  * in the past but are not actively using?  Should be (significantly)
 112  * smaller than HELLO_ADDRESS_EXPIRATION.
 113  */
 114 #define VALIDATED_PING_FREQUENCY GNUNET_TIME_relative_multiply(GNUNET_TIME_UNIT_MINUTES, 15)
 115
 116 /**
 117  * How often do we PING an address that we are currently using?
 118  */
 119 #define CONNECTED_PING_FREQUENCY GNUNET_TIME_relative_multiply(GNUNET_TIME_UNIT_MINUTES, 2)
 120
 121 /**
 122  * How much delay is acceptable for sending the PING or PONG?
 123  */
 124 #define ACCEPTABLE_PING_DELAY GNUNET_TIME_relative_multiply(GNUNET_TIME_UNIT_SECONDS, 1)
 125
 126 /**
 127  * Size of the validation map hashmap.
 128  */
 129 #define VALIDATION_MAP_SIZE 256
 130
 131 /**
 132  * Priority to use for PINGs
 133  */
 134 #define PING_PRIORITY 2
 135
 136 /**
 137  * Priority to use for PONGs
 138  */
 139 #define PONG_PRIORITY 4
 140
 141
 142 GNUNET_NETWORK_STRUCT_BEGIN
 143
 144 /**
 145  * Message used to ask a peer to validate receipt (to check an address
 146  * from a HELLO).  Followed by the address we are trying to validate,
 147  * or an empty address if we are just sending a PING to confirm that a
 148  * connection which the receiver (of the PING) initiated is still valid.
 149  */
 150 struct TransportPingMessage {
 151   /**
 152    * Type will be #GNUNET_MESSAGE_TYPE_TRANSPORT_PING
 153    */
 154   struct GNUNET_MessageHeader header;
 155
 156   /**
 157    * Challenge code (to ensure fresh reply).
 158    */
 159   uint32_t challenge GNUNET_PACKED;
 160
 161   /**
 162    * Who is the intended recipient?
 163    */
 164   struct GNUNET_PeerIdentity target;
 165 };
 166
 167
 168 /**
 169  * Message used to validate a HELLO.  The challenge is included in the
 170  * confirmation to make matching of replies to requests possible.  The
 171  * signature signs our public key, an expiration time and our address.<p>
 172  *
 173  * This message is followed by our transport address that the PING tried
 174  * to confirm (if we liked it).  The address can be empty (zero bytes)
 175  * if the PING had not address either (and we received the request via
 176  * a connection that we initiated).
 177  */
 178 struct TransportPongMessage {
 179   /**
 180    * Type will be #GNUNET_MESSAGE_TYPE_TRANSPORT_PONG
 181    */
 182   struct GNUNET_MessageHeader header;
 183
 184   /**
 185    * Challenge code from PING (showing freshness).  Not part of what
 186    * is signed so that we can re-use signatures.
 187    */
 188   uint32_t challenge GNUNET_PACKED;
 189
 190   /**
 191    * Signature.
 192    */
 193   struct GNUNET_CRYPTO_EddsaSignature signature;
 194
 195   /**
 196    * #GNUNET_SIGNATURE_PURPOSE_TRANSPORT_PONG_OWN to confirm that this is a
 197    * plausible address for the signing peer.
 198    */
 199   struct GNUNET_CRYPTO_EccSignaturePurpose purpose;
 200
 201   /**
 202    * When does this signature expire?
 203    */
 204   struct GNUNET_TIME_AbsoluteNBO expiration;
 205
 206   /**
 207    * Size of address appended to this message (part of what is
 208    * being signed, hence not redundant).
 209    */
 210   uint32_t addrlen GNUNET_PACKED;
 211 };
 212 GNUNET_NETWORK_STRUCT_END
 213
 214 /**
 215  * Information about an address under validation
 216  */
 217 struct ValidationEntry {
 218   /**
 219    * The address.
 220    */
 221   struct GNUNET_HELLO_Address *address;
 222
 223   /**
 224    * Handle to the blacklist check (if we're currently in it).
 225    */
 226   struct GST_BlacklistCheck *bc;
 227
 228   /**
 229    * Cached PONG signature
 230    */
 231   struct GNUNET_CRYPTO_EddsaSignature pong_sig_cache;
 232
 233   /**
 234    * ID of task that will clean up this entry if nothing happens.
 235    */
 236   struct GNUNET_SCHEDULER_Task *timeout_task;
 237
 238   /**
 239    * ID of task that will trigger address revalidation.
 240    */
 241   struct GNUNET_SCHEDULER_Task *revalidation_task;
 242
 243   /**
 244    * At what time did we send the latest validation request (PING)?
 245    */
 246   struct GNUNET_TIME_Absolute send_time;
 247
 248   /**
 249    * At what time do we send the next validation request (PING)?
 250    */
 251   struct GNUNET_TIME_Absolute next_validation;
 252
 253   /**
 254    * Until when is this address valid?
 255    * ZERO if it is not currently considered valid.
 256    */
 257   struct GNUNET_TIME_Absolute valid_until;
 258
 259   /**
 260    * Until when is the cached PONG signature valid?
 261    * ZERO if it is not currently considered valid.
 262    */
 263   struct GNUNET_TIME_Absolute pong_sig_valid_until;
 264
 265   /**
 266    * How long until we can try to validate this address again?
 267    * FOREVER if the address is for an unsupported plugin (from PEERINFO)
 268    * ZERO if the address is considered valid (no validation needed)
 269    * otherwise a time in the future if we're currently denying re-validation
 270    */
 271   struct GNUNET_TIME_Absolute revalidation_block;
 272
 273   /**
 274    * Last observed latency for this address (round-trip), delay between
 275    * last PING sent and PONG received; FOREVER if we never got a PONG.
 276    */
 277   struct GNUNET_TIME_Relative latency;
 278
 279   /**
 280    * Current state of this validation entry
 281    */
 282   enum GNUNET_TRANSPORT_ValidationState state;
 283
 284   /**
 285    * Challenge number we used.
 286    */
 287   uint32_t challenge;
 288
 289   /**
 290    * When passing the address in #add_valid_peer_address(), did we
 291    * copy the address to the HELLO yet?
 292    */
 293   int copied;
 294
 295   /**
 296    * Are we currently using this address for a connection?
 297    */
 298   int in_use;
 299
 300   /**
 301    * Are we expecting a PONG message for this validation entry?
 302    */
 303   int expecting_pong;
 304
 305   /**
 306    * Is this address known to ATS as valid right now?
 307    */
 308   int known_to_ats;
 309
 310   /**
 311    * Which network type does our address belong to?
 312    */
 313   enum GNUNET_NetworkType network;
 314 };
 315
 316
 317 /**
 318  * Map of PeerIdentities to 'struct ValidationEntry*'s (addresses
 319  * of the given peer that we are currently validating, have validated
 320  * or are blocked from re-validation for a while).
 321  */
 322 static struct GNUNET_CONTAINER_MultiPeerMap *validation_map;
 323
 324 /**
 325  * Context for peerinfo iteration.
 326  */
 327 static struct GNUNET_PEERINFO_NotifyContext *pnc;
 328
 329 /**
 330  * Minimum delay between to validations
 331  */
 332 static struct GNUNET_TIME_Relative validation_delay;
 333
 334 /**
 335  * Number of validations running; any PING that was not yet
 336  * matched by a PONG and for which we have not yet hit the
 337  * timeout is considered a running 'validation'.
 338  */
 339 static unsigned int validations_running;
 340
 341 /**
 342  * Validition fast start threshold
 343  */
 344 static unsigned int validations_fast_start_threshold;
 345
 346 /**
 347  * When is next validation allowed
 348  */
 349 static struct GNUNET_TIME_Absolute validation_next;
 350
 351
 352 /**
 353  * Context for the validation entry match function.
 354  */
 355 struct ValidationEntryMatchContext {
 356   /**
 357    * Where to store the result?
 358    */
 359   struct ValidationEntry *ve;
 360
 361   /**
 362    * Address we're interested in.
 363    */
 364   const struct GNUNET_HELLO_Address *address;
 365 };
 366
 367
 368 /**
 369  * Provide an update on the `validation_map` map size to statistics.
 370  * This function should be called whenever the `validation_map`
 371  * is changed.
 372  */
 373 static void
 374 publish_ve_stat_update()
 375 {
 376   GNUNET_STATISTICS_set(GST_stats,
 377                         gettext_noop("# Addresses in validation map"),
 378                         GNUNET_CONTAINER_multipeermap_size(validation_map),
 379                         GNUNET_NO);
 380 }
 381
 382
 383 /**
 384  * Iterate over validation entries until a matching one is found.
 385  *
 386  * @param cls the `struct ValidationEntryMatchContext *`
 387  * @param key peer identity (unused)
 388  * @param value a `struct ValidationEntry *` to match
 389  * @return #GNUNET_YES if the entry does not match,
 390  *         #GNUNET_NO if the entry does match
 391  */
 392 static int
 393 validation_entry_match(void *cls,
 394                        const struct GNUNET_PeerIdentity *key,
 395                        void *value)
 396 {
 397   struct ValidationEntryMatchContext *vemc = cls;
 398   struct ValidationEntry *ve = value;
 399
 400   if (0 == GNUNET_HELLO_address_cmp(ve->address,
 401                                     vemc->address))
 402     {
 403       vemc->ve = ve;
 404       return GNUNET_NO;
 405     }
 406   return GNUNET_YES;
 407 }
 408
 409
 410 /**
 411  * A validation entry changed.  Update the state and notify
 412  * monitors.
 413  *
 414  * @param ve validation entry that changed
 415  * @param state new state
 416  */
 417 static void
 418 validation_entry_changed(struct ValidationEntry *ve,
 419                          enum GNUNET_TRANSPORT_ValidationState state)
 420 {
 421   ve->state = state;
 422 }
 423
 424
 425 /**
 426  * Iterate over validation entries and free them.
 427  *
 428  * @param cls (unused)
 429  * @param key peer identity (unused)
 430  * @param value a `struct ValidationEntry *` to clean up
 431  * @return #GNUNET_YES (continue to iterate)
 432  */
 433 static int
 434 cleanup_validation_entry(void *cls,
 435                          const struct GNUNET_PeerIdentity *key,
 436                          void *value)
 437 {
 438   struct ValidationEntry *ve = value;
 439
 440   ve->next_validation = GNUNET_TIME_UNIT_ZERO_ABS;
 441   ve->valid_until = GNUNET_TIME_UNIT_ZERO_ABS;
 442
 443   /* Notify about deleted entry */
 444   validation_entry_changed(ve,
 445                            GNUNET_TRANSPORT_VS_REMOVE);
 446
 447   if (NULL != ve->bc)
 448     {
 449       GST_blacklist_test_cancel(ve->bc);
 450       ve->bc = NULL;
 451     }
 452   GNUNET_break(GNUNET_OK ==
 453                GNUNET_CONTAINER_multipeermap_remove(validation_map,
 454                                                     &ve->address->peer,
 455                                                     ve));
 456   publish_ve_stat_update();
 457   if (GNUNET_YES == ve->known_to_ats)
 458     {
 459       GST_ats_expire_address(ve->address);
 460       GNUNET_assert(GNUNET_NO ==
 461                     GST_ats_is_known_no_session(ve->address));
 462       ve->known_to_ats = GNUNET_NO;
 463     }
 464   GNUNET_HELLO_address_free(ve->address);
 465   if (NULL != ve->timeout_task)
 466     {
 467       GNUNET_SCHEDULER_cancel(ve->timeout_task);
 468       ve->timeout_task = NULL;
 469     }
 470   if (NULL != ve->revalidation_task)
 471     {
 472       GNUNET_SCHEDULER_cancel(ve->revalidation_task);
 473       ve->revalidation_task = NULL;
 474     }
 475   if ((GNUNET_YES == ve->expecting_pong) &&
 476       (validations_running > 0))
 477     {
 478       validations_running--;
 479       GNUNET_STATISTICS_set(GST_stats,
 480                             gettext_noop("# validations running"),
 481                             validations_running,
 482                             GNUNET_NO);
 483     }
 484   GNUNET_free(ve);
 485   return GNUNET_OK;
 486 }
 487
 488
 489 /**
 490  * Address validation cleanup task.  Assesses if the record is no
 491  * longer valid and then possibly triggers its removal.
 492  *
 493  * @param cls the `struct ValidationEntry`
 494  */
 495 static void
 496 timeout_hello_validation(void *cls)
 497 {
 498   struct ValidationEntry *ve = cls;
 499   struct GNUNET_TIME_Absolute max;
 500   struct GNUNET_TIME_Relative left;
 501
 502   ve->timeout_task = NULL;
 503   /* For valid addresses, we want to wait until the expire;
 504      for addresses under PING validation, we want to wait
 505      until we give up on the PING */
 506   max = GNUNET_TIME_absolute_max(ve->valid_until,
 507                                  ve->revalidation_block);
 508   left = GNUNET_TIME_absolute_get_remaining(max);
 509   if (left.rel_value_us > 0)
 510     {
 511       /* We should wait a bit longer. This happens when
 512          address lifetimes are extended due to successful
 513          validations. */
 514       ve->timeout_task =
 515         GNUNET_SCHEDULER_add_delayed(left,
 516                                      &timeout_hello_validation,
 517                                      ve);
 518       return;
 519     }
 520   GNUNET_STATISTICS_update(GST_stats,
 521                            gettext_noop("# address records discarded (timeout)"),
 522                            1,
 523                            GNUNET_NO);
 524   cleanup_validation_entry(NULL,
 525                            &ve->address->peer,
 526                            ve);
 527 }
 528
 529
 530 /**
 531  * Function called with the result from blacklisting.
 532  * Send a PING to the other peer if a communication is allowed.
 533  *
 534  * @param cls our `struct ValidationEntry`
 535  * @param pid identity of the other peer
 536  * @param address_null address associated with the request, always NULL
 537  * @param session_null session associated with the request, always NULL
 538  * @param result #GNUNET_OK if the connection is allowed,
 539  *               #GNUNET_NO if not,
 540  *               #GNUNET_SYSERR if operation was aborted
 541  */
 542 static void
 543 transmit_ping_if_allowed(void *cls,
 544                          const struct GNUNET_PeerIdentity *pid,
 545                          const struct GNUNET_HELLO_Address *address_null,
 546                          struct GNUNET_ATS_Session *session_null,
 547                          int result)
 548 {
 549   struct ValidationEntry *ve = cls;
 550   struct TransportPingMessage ping;
 551   struct GNUNET_TRANSPORT_PluginFunctions *papi;
 552   struct GNUNET_TIME_Absolute next;
 553   const struct GNUNET_MessageHeader *hello;
 554   ssize_t ret;
 555   size_t tsize;
 556   size_t slen;
 557   uint16_t hsize;
 558   struct GNUNET_ATS_Session *session;
 559
 560   ve->bc = NULL;
 561   if (GNUNET_OK != result)
 562     {
 563       GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
 564                  "Blacklist denies sending PING to `%s' `%s' `%s'\n",
 565                  GNUNET_i2s(pid),
 566                  GST_plugins_a2s(ve->address),
 567                  ve->address->transport_name);
 568       GNUNET_STATISTICS_update(GST_stats,
 569                                gettext_noop("# address records discarded (blacklist)"),
 570                                1,
 571                                GNUNET_NO);
 572       cleanup_validation_entry(NULL,
 573                                pid,
 574                                ve);
 575       return;
 576     }
 577   hello = GST_hello_get();
 578   GNUNET_assert(NULL != hello);
 579   slen = strlen(ve->address->transport_name) + 1;
 580   hsize = ntohs(hello->size);
 581   tsize = sizeof(struct TransportPingMessage) +
 582           ve->address->address_length + slen + hsize;
 583
 584   ping.header.size =
 585     htons(sizeof(struct TransportPingMessage) +
 586           ve->address->address_length + slen);
 587   ping.header.type = htons(GNUNET_MESSAGE_TYPE_TRANSPORT_PING);
 588   ping.challenge = htonl(ve->challenge);
 589   ping.target = *pid;
 590
 591   if (tsize >= GNUNET_MAX_MESSAGE_SIZE)
 592     {
 593       GNUNET_break(0);
 594       hsize = 0;
 595       tsize =
 596         sizeof(struct TransportPingMessage) + ve->address->address_length +
 597         slen + hsize;
 598     }
 599   {
 600     char message_buf[tsize] GNUNET_ALIGN;
 601
 602     GNUNET_memcpy(message_buf,
 603                   hello,
 604                   hsize);
 605     GNUNET_memcpy(&message_buf[hsize],
 606                   &ping,
 607                   sizeof(struct TransportPingMessage));
 608     GNUNET_memcpy(&message_buf[sizeof(struct TransportPingMessage) + hsize],
 609                   ve->address->transport_name,
 610                   slen);
 611     GNUNET_memcpy(&message_buf[sizeof(struct TransportPingMessage) + slen + hsize],
 612                   ve->address->address,
 613                   ve->address->address_length);
 614     papi = GST_plugins_find(ve->address->transport_name);
 615     GNUNET_assert(NULL != papi);
 616     session = papi->get_session(papi->cls,
 617                                 ve->address);
 618     if (NULL == session)
 619       {
 620         /* Could not get a valid session */
 621         GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
 622                    "Failed to get session to send PING to `%s' at `%s'\n",
 623                    GNUNET_i2s(pid),
 624                    GST_plugins_a2s(ve->address));
 625         return;
 626       }
 627
 628     ret = papi->send(papi->cls, session,
 629                      message_buf, tsize,
 630                      PING_PRIORITY,
 631                      ACCEPTABLE_PING_DELAY,
 632                      NULL, NULL);
 633     if (-1 == ret)
 634       {
 635         GNUNET_log(GNUNET_ERROR_TYPE_INFO,
 636                    "Failed to send PING to `%s' at `%s'\n",
 637                    GNUNET_i2s(pid),
 638                    GST_plugins_a2s(ve->address));
 639         return;
 640       }
 641     GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
 642                "Transmitted plain PING to `%s' `%s' `%s'\n",
 643                GNUNET_i2s(pid),
 644                GST_plugins_a2s(ve->address),
 645                ve->address->transport_name);
 646     ve->network = papi->get_network(papi->cls,
 647                                     session);
 648     GNUNET_break(GNUNET_NT_UNSPECIFIED != ve->network);
 649     GST_neighbours_notify_data_sent(ve->address,
 650                                     session,
 651                                     tsize);
 652     next = GNUNET_TIME_relative_to_absolute(validation_delay);
 653     validation_next = GNUNET_TIME_absolute_max(next,
 654                                                validation_next);
 655     ve->send_time = GNUNET_TIME_absolute_get();
 656     GNUNET_STATISTICS_update(GST_stats,
 657                              gettext_noop("# PINGs for address validation sent"),
 658                              1,
 659                              GNUNET_NO);
 660     ve->expecting_pong = GNUNET_YES;
 661     validations_running++;
 662     GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
 663                "Validation started, %u validation processes running\n",
 664                validations_running);
 665     GNUNET_STATISTICS_set(GST_stats,
 666                           gettext_noop("# validations running"),
 667                           validations_running,
 668                           GNUNET_NO);
 669     /*  Notify about PING sent */
 670     validation_entry_changed(ve,
 671                              GNUNET_TRANSPORT_VS_UPDATE);
 672   }
 673 }
 674
 675
 676 /**
 677  * Do address validation again to keep address valid.
 678  *
 679  * @param cls the `struct ValidationEntry`
 680  */
 681 static void
 682 revalidate_address(void *cls)
 683 {
 684   struct ValidationEntry *ve = cls;
 685   struct GNUNET_TIME_Relative canonical_delay;
 686   struct GNUNET_TIME_Relative delay;
 687   struct GNUNET_TIME_Relative blocked_for;
 688   struct GST_BlacklistCheck *bc;
 689   uint32_t rdelay;
 690
 691   ve->revalidation_task = NULL;
 692   delay = GNUNET_TIME_absolute_get_remaining(ve->revalidation_block);
 693   /* Considering current connectivity situation, what is the maximum
 694      block period permitted? */
 695   if (GNUNET_YES == ve->in_use)
 696     canonical_delay = CONNECTED_PING_FREQUENCY;
 697   else if (GNUNET_TIME_absolute_get_remaining(ve->valid_until).rel_value_us > 0)
 698     canonical_delay = VALIDATED_PING_FREQUENCY;
 699   else
 700     canonical_delay = UNVALIDATED_PING_KEEPALIVE;
 701   /* Use delay that is MIN of original delay and possibly adjusted
 702      new maximum delay (which may be lower); the real delay
 703      is originally randomized between "canonical_delay" and "2 * canonical_delay",
 704      so continue to permit that window for the operation. */
 705   delay = GNUNET_TIME_relative_min(delay,
 706                                    GNUNET_TIME_relative_multiply(canonical_delay,
 707                                                                  2));
 708   ve->revalidation_block = GNUNET_TIME_relative_to_absolute(delay);
 709   if (delay.rel_value_us > 0)
 710     {
 711       /* should wait a bit longer */
 712       GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
 713                  "Waiting for %s longer before (re)validating address `%s'\n",
 714                  GNUNET_STRINGS_relative_time_to_string(delay,
 715                                                         GNUNET_YES),
 716                  GST_plugins_a2s(ve->address));
 717       ve->revalidation_task =
 718         GNUNET_SCHEDULER_add_delayed(delay,
 719                                      &revalidate_address, ve);
 720       ve->next_validation = GNUNET_TIME_relative_to_absolute(delay);
 721       return;
 722     }
 723   /* check if globally we have too many active validations at a
 724      too high rate, if so, delay ours */
 725   blocked_for = GNUNET_TIME_absolute_get_remaining(validation_next);
 726   if ((validations_running > validations_fast_start_threshold) &&
 727       (blocked_for.rel_value_us > 0))
 728     {
 729       /* Validations are blocked, have to wait for blocked_for time */
 730       GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
 731                  "Validations blocked for another %s, delaying validating address `%s'\n",
 732                  GNUNET_STRINGS_relative_time_to_string(blocked_for,
 733                                                         GNUNET_YES),
 734                  GST_plugins_a2s(ve->address));
 735       GNUNET_STATISTICS_update(GST_stats,
 736                                gettext_noop("# validations delayed by global throttle"),
 737                                1,
 738                                GNUNET_NO);
 739       ve->revalidation_task =
 740         GNUNET_SCHEDULER_add_delayed(blocked_for,
 741                                      &revalidate_address,
 742                                      ve);
 743       ve->next_validation = GNUNET_TIME_relative_to_absolute(blocked_for);
 744       return;
 745     }
 746
 747   /* We are good to go; remember to not go again for `canonical_delay` time;
 748      add up to `canonical_delay` to randomize start time */
 749   ve->revalidation_block = GNUNET_TIME_relative_to_absolute(canonical_delay);
 750   /* schedule next PINGing with some extra random delay to avoid synchronous re-validations */
 751   rdelay =
 752     GNUNET_CRYPTO_random_u32(GNUNET_CRYPTO_QUALITY_WEAK,
 753                              canonical_delay.rel_value_us);
 754
 755   delay = GNUNET_TIME_relative_add(canonical_delay,
 756                                    GNUNET_TIME_relative_multiply
 757                                      (GNUNET_TIME_UNIT_MICROSECONDS,
 758                                      rdelay));
 759
 760   GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
 761              "Validating now, next scheduled for %s, now validating address `%s'\n",
 762              GNUNET_STRINGS_relative_time_to_string(blocked_for,
 763                                                     GNUNET_YES),
 764              GST_plugins_a2s(ve->address));
 765   ve->revalidation_task =
 766     GNUNET_SCHEDULER_add_delayed(delay,
 767                                  &revalidate_address,
 768                                  ve);
 769   ve->next_validation = GNUNET_TIME_relative_to_absolute(delay);
 770
 771   /* start PINGing by checking blacklist */
 772   GNUNET_STATISTICS_update(GST_stats,
 773                            gettext_noop("# address revalidations started"), 1,
 774                            GNUNET_NO);
 775   if (NULL != ve->bc)
 776     {
 777       GST_blacklist_test_cancel(ve->bc);
 778       ve->bc = NULL;
 779     }
 780   bc = GST_blacklist_test_allowed(&ve->address->peer,
 781                                   ve->address->transport_name,
 782                                   &transmit_ping_if_allowed,
 783                                   ve,
 784                                   NULL,
 785                                   NULL);
 786   if (NULL != bc)
 787     {
 788       /* If transmit_ping_if_allowed was already called it may have freed ve,
 789        * so only set ve->bc if it has not been called.
 790        */
 791       ve->bc = bc;
 792     }
 793 }
 794
 795
 796 /**
 797  * Find a ValidationEntry entry for the given neighbour that matches
 798  * the given address and transport.  If none exists, create one (but
 799  * without starting any validation).
 800  *
 801  * @param address address to find
 802  * @return validation entry matching the given specifications, NULL
 803  *         if we don't have an existing entry and no public key was given
 804  */
 805 static struct ValidationEntry *
 806 find_validation_entry(const struct GNUNET_HELLO_Address *address)
 807 {
 808   struct ValidationEntryMatchContext vemc;
 809   struct ValidationEntry *ve;
 810
 811   vemc.ve = NULL;
 812   vemc.address = address;
 813   GNUNET_CONTAINER_multipeermap_get_multiple(validation_map,
 814                                              &address->peer,
 815                                              &validation_entry_match, &vemc);
 816   if (NULL != (ve = vemc.ve))
 817     return ve;
 818   GNUNET_assert(GNUNET_NO ==
 819                 GST_ats_is_known_no_session(address));
 820   ve = GNUNET_new(struct ValidationEntry);
 821   ve->in_use = GNUNET_SYSERR; /* not defined */
 822   ve->address = GNUNET_HELLO_address_copy(address);
 823   ve->pong_sig_valid_until = GNUNET_TIME_UNIT_ZERO_ABS;
 824   memset(&ve->pong_sig_cache,
 825          '\0',
 826          sizeof(struct GNUNET_CRYPTO_EddsaSignature));
 827   ve->latency = GNUNET_TIME_UNIT_FOREVER_REL;
 828   ve->challenge =
 829     GNUNET_CRYPTO_random_u32(GNUNET_CRYPTO_QUALITY_NONCE, UINT32_MAX);
 830   ve->timeout_task =
 831     GNUNET_SCHEDULER_add_delayed(UNVALIDATED_PING_KEEPALIVE,
 832                                  &timeout_hello_validation,
 833                                  ve);
 834   GNUNET_CONTAINER_multipeermap_put(validation_map,
 835                                     &address->peer,
 836                                     ve,
 837                                     GNUNET_CONTAINER_MULTIHASHMAPOPTION_MULTIPLE);
 838   publish_ve_stat_update();
 839   validation_entry_changed(ve,
 840                            GNUNET_TRANSPORT_VS_NEW);
 841   return ve;
 842 }
 843
 844
 845 /**
 846  * Iterator which adds the given address to the set of validated
 847  * addresses.
 848  *
 849  * @param cls original HELLO message
 850  * @param address the address
 851  * @param expiration expiration time
 852  * @return #GNUNET_OK (keep the address), could return
 853  *         #GNUNET_NO (delete address, but this is ignored);
 854  *         #GNUNET_SYSERR would abort iteration (but we always iterate all)
 855  */
 856 static int
 857 add_valid_address(void *cls,
 858                   const struct GNUNET_HELLO_Address *address,
 859                   struct GNUNET_TIME_Absolute expiration)
 860 {
 861   const struct GNUNET_HELLO_Message *hello = cls;
 862   struct ValidationEntry *ve;
 863   struct GNUNET_PeerIdentity pid;
 864   struct GNUNET_ATS_Properties prop;
 865   struct GNUNET_TRANSPORT_PluginFunctions *papi;
 866
 867   if (0 == GNUNET_TIME_absolute_get_remaining(expiration).rel_value_us)
 868     return GNUNET_OK;           /* expired */
 869   if (GNUNET_OK != GNUNET_HELLO_get_id(hello, &pid))
 870     {
 871       GNUNET_break(0);
 872       return GNUNET_OK;         /* invalid HELLO !? */
 873     }
 874   if (NULL == (papi = GST_plugins_find(address->transport_name)))
 875     {
 876       /* might have been valid in the past, but we don't have that
 877          plugin loaded right now */
 878       return GNUNET_OK;
 879     }
 880   if (NULL ==
 881       papi->address_to_string(papi->cls,
 882                               address->address,
 883                               address->address_length))
 884     {
 885       /* Why do we try to add an ill-formed address? */
 886       GNUNET_break(0);
 887       GNUNET_log(GNUNET_ERROR_TYPE_ERROR,
 888                  "Address with %u bytes for plugin %s and peer %s is malformed\n",
 889                  (unsigned int)address->address_length,
 890                  address->transport_name,
 891                  GNUNET_i2s(&pid));
 892       return GNUNET_OK;
 893     }
 894
 895   ve = find_validation_entry(address);
 896   ve->network = papi->get_network_for_address(papi->cls,
 897                                               address);
 898   GNUNET_break(GNUNET_NT_UNSPECIFIED != ve->network);
 899   ve->valid_until = GNUNET_TIME_absolute_max(ve->valid_until,
 900                                              expiration);
 901   if (NULL == ve->revalidation_task)
 902     {
 903       GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
 904                  "Starting revalidations for valid address `%s'\n",
 905                  GST_plugins_a2s(ve->address));
 906       ve->next_validation = GNUNET_TIME_absolute_get();
 907       ve->revalidation_task = GNUNET_SCHEDULER_add_now(&revalidate_address, ve);
 908     }
 909   validation_entry_changed(ve,
 910                            GNUNET_TRANSPORT_VS_UPDATE);
 911   memset(&prop, 0, sizeof(prop));
 912   prop.scope = ve->network;
 913   prop.delay = GNUNET_TIME_relative_divide(ve->latency, 2);
 914   if (GNUNET_YES != ve->known_to_ats)
 915     {
 916       ve->known_to_ats = GNUNET_YES;
 917       GST_ats_add_address(address, &prop);
 918       GNUNET_assert(GNUNET_YES ==
 919                     GST_ats_is_known_no_session(ve->address));
 920     }
 921   return GNUNET_OK;
 922 }
 923
 924
 925 /**
 926  * Function called for any HELLO known to PEERINFO.
 927  *
 928  * @param cls unused (NULL)
 929  * @param peer id of the peer, NULL for last call (during iteration,
 930  *             as we are monitoring, this should never happen)
 931  * @param hello hello message for the peer (can be NULL)
 932  * @param err_msg error message
 933  */
 934 static void
 935 process_peerinfo_hello(void *cls,
 936                        const struct GNUNET_PeerIdentity *peer,
 937                        const struct GNUNET_HELLO_Message *hello,
 938                        const char *err_msg)
 939 {
 940   GNUNET_assert(NULL != peer);
 941   if (NULL == hello)
 942     return;
 943   if (0 == memcmp(&GST_my_identity,
 944                   peer,
 945                   sizeof(struct GNUNET_PeerIdentity)))
 946     {
 947       /* Peerinfo returned own identity, skip validation */
 948       return;
 949     }
 950   GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
 951              "Handling HELLO for peer `%s'\n",
 952              GNUNET_i2s(peer));
 953   GNUNET_assert(NULL ==
 954                 GNUNET_HELLO_iterate_addresses(hello, GNUNET_NO,
 955                                                &add_valid_address,
 956                                                (void *)hello));
 957 }
 958
 959
 960 /**
 961  * Start the validation subsystem.
 962  *
 963  * @param max_fds maximum number of fds to use
 964  */
 965 void
 966 GST_validation_start(unsigned int max_fds)
 967 {
 968   /**
 969    * Initialization for validation throttling
 970    *
 971    * We have a maximum number max_fds of connections we can use for validation
 972    * We monitor the number of validations in parallel and start to throttle it
 973    * when doing to many validations in parallel:
 974    * if (running validations < (max_fds / 2))
 975    * - "fast start": run validation immediately
 976    * - have delay of (GNUNET_CONSTANTS_IDLE_CONNECTION_TIMEOUT.rel_value_us) / (max_fds / 2)
 977    *   (300 sec / ~150 == ~2 sec.) between two validations
 978    */
 979
 980   validation_next = GNUNET_TIME_absolute_get();
 981   validation_delay.rel_value_us = (GNUNET_CONSTANTS_IDLE_CONNECTION_TIMEOUT.rel_value_us) / (max_fds / 2);
 982   validations_fast_start_threshold = (max_fds / 2);
 983   validations_running = 0;
 984   GNUNET_STATISTICS_set(GST_stats,
 985                         gettext_noop("# validations running"),
 986                         validations_running,
 987                         GNUNET_NO);
 988   GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
 989              "Validation uses a fast start threshold of %u connections and a delay of %s\n",
 990              validations_fast_start_threshold,
 991              GNUNET_STRINGS_relative_time_to_string(validation_delay,
 992                                                     GNUNET_YES));
 993   validation_map = GNUNET_CONTAINER_multipeermap_create(VALIDATION_MAP_SIZE,
 994                                                         GNUNET_NO);
 995   pnc = GNUNET_PEERINFO_notify(GST_cfg, GNUNET_YES,
 996                                &process_peerinfo_hello, NULL);
 997 }
 998
 999
1000 /**
1001  * Stop the validation subsystem.
1002  */
1003 void
1004 GST_validation_stop()
1005 {
1006   GNUNET_CONTAINER_multipeermap_iterate(validation_map,
1007                                         &cleanup_validation_entry,
1008                                         NULL);
1009   GNUNET_CONTAINER_multipeermap_destroy(validation_map);
1010   validation_map = NULL;
1011   GNUNET_PEERINFO_notify_cancel(pnc);
1012 }
1013
1014
1015 /**
1016  * Send the given PONG to the given address.
1017  *
1018  * @param cls the PONG message
1019  * @param valid_until is ZERO if we never validated the address,
1020  *                    otherwise a time up to when we consider it (or was) valid
1021  * @param validation_block  is FOREVER if the address is for an unsupported plugin (from PEERINFO)
1022  *                          is ZERO if the address is considered valid (no validation needed)
1023  *                          otherwise a time in the future if we're currently denying re-validation
1024  * @param address target address
1025  */
1026 static void
1027 multicast_pong(void *cls,
1028                struct GNUNET_TIME_Absolute valid_until,
1029                struct GNUNET_TIME_Absolute validation_block,
1030                const struct GNUNET_HELLO_Address *address)
1031 {
1032   struct TransportPongMessage *pong = cls;
1033   struct GNUNET_TRANSPORT_PluginFunctions *papi;
1034   struct GNUNET_ATS_Session *session;
1035
1036   papi = GST_plugins_find(address->transport_name);
1037   if (NULL == papi)
1038     {
1039       GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
1040                  "Plugin %s not supported, cannot send PONG\n",
1041                  address->transport_name);
1042       return;
1043     }
1044   GNUNET_assert(NULL != papi->send);
1045   GNUNET_assert(NULL != papi->get_session);
1046   session = papi->get_session(papi->cls, address);
1047   if (NULL == session)
1048     {
1049       GNUNET_break(0);
1050       return;
1051     }
1052   GST_ats_new_session(address, session);
1053   papi->send(papi->cls, session,
1054              (const char *)pong,
1055              ntohs(pong->header.size),
1056              PONG_PRIORITY,
1057              ACCEPTABLE_PING_DELAY,
1058              NULL, NULL);
1059   GST_neighbours_notify_data_sent(address,
1060                                   session,
1061                                   pong->header.size);
1062 }
1063
1064
1065 /**
1066  * We've received a PING.  If appropriate, generate a PONG.
1067  *
1068  * @param sender peer sending the PING
1069  * @param hdr the PING
1070  * @param sender_address the sender address as we got it
1071  * @param session session we got the PING from
1072  * @return #GNUNET_OK if the message was fine, #GNUNET_SYSERR on serious error
1073  */
1074 int
1075 GST_validation_handle_ping(const struct GNUNET_PeerIdentity *sender,
1076                            const struct GNUNET_MessageHeader *hdr,
1077                            const struct GNUNET_HELLO_Address *sender_address,
1078                            struct GNUNET_ATS_Session *session)
1079 {
1080   const struct TransportPingMessage *ping;
1081   struct TransportPongMessage *pong;
1082   struct GNUNET_TRANSPORT_PluginFunctions *papi;
1083   struct GNUNET_CRYPTO_EddsaSignature *sig_cache;
1084   struct GNUNET_TIME_Absolute *sig_cache_exp;
1085   const char *addr;
1086   const char *addrend;
1087   char *plugin_name;
1088   char *pos;
1089   size_t len_address;
1090   size_t len_plugin;
1091   ssize_t ret;
1092   struct GNUNET_HELLO_Address address;
1093
1094   if (0 ==
1095       memcmp(&GST_my_identity,
1096              sender,
1097              sizeof(struct GNUNET_PeerIdentity)))
1098     return GNUNET_OK; /* our own, ignore! */
1099   if (ntohs(hdr->size) < sizeof(struct TransportPingMessage))
1100     {
1101       GNUNET_break_op(0);
1102       return GNUNET_SYSERR;
1103     }
1104   ping = (const struct TransportPingMessage *)hdr;
1105   if (0 !=
1106       memcmp(&ping->target,
1107              &GST_my_identity,
1108              sizeof(struct GNUNET_PeerIdentity)))
1109     {
1110       GNUNET_STATISTICS_update(GST_stats,
1111                                gettext_noop
1112                                  ("# PING message for different peer received"), 1,
1113                                GNUNET_NO);
1114       return GNUNET_SYSERR;
1115     }
1116   GNUNET_STATISTICS_update(GST_stats,
1117                            gettext_noop("# PING messages received"), 1,
1118                            GNUNET_NO);
1119   addr = (const char *)&ping[1];
1120   len_address = ntohs(hdr->size) - sizeof(struct TransportPingMessage);
1121   /* peer wants to confirm that this is one of our addresses, this is what is
1122    * used for address validation */
1123
1124   sig_cache = NULL;
1125   sig_cache_exp = NULL;
1126   papi = NULL;
1127   if (len_address > 0)
1128     {
1129       addrend = memchr(addr, '\0', len_address);
1130       if (NULL == addrend)
1131         {
1132           GNUNET_break_op(0);
1133           return GNUNET_SYSERR;
1134         }
1135       addrend++;
1136       len_plugin = strlen(addr) + 1;
1137       len_address -= len_plugin;
1138       address.local_info = GNUNET_HELLO_ADDRESS_INFO_NONE;
1139       address.address = addrend;
1140       address.address_length = len_address;
1141       address.transport_name = addr;
1142       address.peer = GST_my_identity;
1143
1144       if (NULL == address.transport_name)
1145         {
1146           GNUNET_break(0);
1147         }
1148
1149       if (0 != strstr(address.transport_name, "_client"))
1150         {
1151           plugin_name = GNUNET_strdup(address.transport_name);
1152           pos = strstr(plugin_name, "_client");
1153           GNUNET_assert(NULL != pos);
1154           GNUNET_snprintf(pos, strlen("_server") + 1, "%s", "_server");
1155         }
1156       else
1157         plugin_name = GNUNET_strdup(address.transport_name);
1158
1159       if (NULL == (papi = GST_plugins_find(plugin_name)))
1160         {
1161           /* we don't have the plugin for this address */
1162           GNUNET_log(GNUNET_ERROR_TYPE_INFO,
1163                      _("Plugin `%s' not available, cannot confirm having this address\n"),
1164                      plugin_name);
1165           GNUNET_free(plugin_name);
1166           return GNUNET_SYSERR;
1167         }
1168       GNUNET_free(plugin_name);
1169       if (GNUNET_OK !=
1170           papi->check_address(papi->cls,
1171                               addrend,
1172                               len_address))
1173         {
1174           GNUNET_STATISTICS_update(GST_stats,
1175                                    gettext_noop
1176                                      ("# failed address checks during validation"), 1,
1177                                    GNUNET_NO);
1178           GNUNET_log(GNUNET_ERROR_TYPE_INFO,
1179                      _("Address `%s' is not one of my addresses, not confirming PING\n"),
1180                      GST_plugins_a2s(&address));
1181           return GNUNET_SYSERR;
1182         }
1183       else
1184         {
1185           GNUNET_STATISTICS_update(GST_stats,
1186                                    gettext_noop
1187                                      ("# successful address checks during validation"), 1,
1188                                    GNUNET_NO);
1189           GNUNET_log(GNUNET_ERROR_TYPE_INFO,
1190                      "Address `%s' is one of my addresses, confirming PING\n",
1191                      GST_plugins_a2s(&address));
1192         }
1193
1194       if (GNUNET_YES !=
1195           GST_hello_test_address(&address,
1196                                  &sig_cache,
1197                                  &sig_cache_exp))
1198         {
1199           GNUNET_log(GNUNET_ERROR_TYPE_INFO,
1200                      _("Not confirming PING from peer `%s' with address `%s' since I cannot confirm having this address.\n"),
1201                      GNUNET_i2s(sender),
1202                      GST_plugins_a2s(&address));
1203           return GNUNET_SYSERR;
1204         }
1205     }
1206   else
1207     {
1208       addrend = NULL;           /* make gcc happy */
1209       len_plugin = 0;
1210       static struct GNUNET_CRYPTO_EddsaSignature no_address_signature;
1211       static struct GNUNET_TIME_Absolute no_address_signature_expiration;
1212
1213       sig_cache = &no_address_signature;
1214       sig_cache_exp = &no_address_signature_expiration;
1215     }
1216
1217   GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
1218              "I am `%s', sending PONG to peer `%s'\n",
1219              GNUNET_i2s_full(&GST_my_identity),
1220              GNUNET_i2s(sender));
1221
1222   /* message with structure:
1223    * [TransportPongMessage][Transport name][Address] */
1224
1225   pong = GNUNET_malloc(sizeof(struct TransportPongMessage) + len_address + len_plugin);
1226   pong->header.size =
1227     htons(sizeof(struct TransportPongMessage) + len_address + len_plugin);
1228   pong->header.type = htons(GNUNET_MESSAGE_TYPE_TRANSPORT_PONG);
1229   pong->purpose.size =
1230     htonl(sizeof(struct GNUNET_CRYPTO_EccSignaturePurpose) +
1231           sizeof(uint32_t) + sizeof(struct GNUNET_TIME_AbsoluteNBO) +
1232           len_address + len_plugin);
1233   pong->purpose.purpose = htonl(GNUNET_SIGNATURE_PURPOSE_TRANSPORT_PONG_OWN);
1234   GNUNET_memcpy(&pong->challenge, &ping->challenge, sizeof(ping->challenge));
1235   pong->addrlen = htonl(len_address + len_plugin);
1236   GNUNET_memcpy(&pong[1], addr, len_plugin);    /* Copy transport plugin */
1237   if (len_address > 0)
1238     {
1239       GNUNET_assert(NULL != addrend);
1240       GNUNET_memcpy(&((char *)&pong[1])[len_plugin], addrend, len_address);
1241     }
1242   if (GNUNET_TIME_absolute_get_remaining(*sig_cache_exp).rel_value_us <
1243       PONG_SIGNATURE_LIFETIME.rel_value_us / 4)
1244     {
1245       /* create / update cached sig */
1246       GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
1247                  "Creating PONG signature to indicate ownership.\n");
1248       *sig_cache_exp = GNUNET_TIME_relative_to_absolute(PONG_SIGNATURE_LIFETIME);
1249       pong->expiration = GNUNET_TIME_absolute_hton(*sig_cache_exp);
1250       if (GNUNET_OK !=
1251           GNUNET_CRYPTO_eddsa_sign(GST_my_private_key, &pong->purpose,
1252                                    sig_cache))
1253         {
1254           GNUNET_log(GNUNET_ERROR_TYPE_ERROR,
1255                      _("Failed to create PONG signature for peer `%s'\n"), GNUNET_i2s(sender));
1256         }
1257     }
1258   else
1259     {
1260       pong->expiration = GNUNET_TIME_absolute_hton(*sig_cache_exp);
1261     }
1262   pong->signature = *sig_cache;
1263
1264   GNUNET_assert(NULL != sender_address);
1265
1266   /* first see if the session we got this PING from can be used to transmit
1267    * a response reliably */
1268   if (NULL == papi)
1269     {
1270       ret = -1;
1271     }
1272   else
1273     {
1274       GNUNET_assert(NULL != papi->send);
1275       GNUNET_assert(NULL != papi->get_session);
1276       if (NULL == session)
1277         {
1278           session = papi->get_session(papi->cls, sender_address);
1279         }
1280       if (NULL == session)
1281         {
1282           GNUNET_break(0);
1283           ret = -1;
1284         }
1285       else
1286         {
1287           ret = papi->send(papi->cls, session,
1288                            (const char *)pong,
1289                            ntohs(pong->header.size),
1290                            PONG_PRIORITY, ACCEPTABLE_PING_DELAY,
1291                            NULL, NULL);
1292           if (-1 != ret)
1293             GST_neighbours_notify_data_sent(sender_address,
1294                                             session,
1295                                             pong->header.size);
1296         }
1297     }
1298   if (-1 != ret)
1299     {
1300       GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
1301                  "Transmitted PONG to `%s' via reliable mechanism\n",
1302                  GNUNET_i2s(sender));
1303       /* done! */
1304       GNUNET_STATISTICS_update(GST_stats,
1305                                gettext_noop
1306                                  ("# PONGs unicast via reliable transport"), 1,
1307                                GNUNET_NO);
1308       GNUNET_free(pong);
1309       return GNUNET_OK;
1310     }
1311
1312   /* no reliable method found, try transmission via all known addresses */
1313   GNUNET_STATISTICS_update(GST_stats,
1314                            gettext_noop
1315                              ("# PONGs multicast to all available addresses"), 1,
1316                            GNUNET_NO);
1317   GST_validation_get_addresses(sender,
1318                                &multicast_pong, pong);
1319   GNUNET_free(pong);
1320   return GNUNET_OK;
1321 }
1322
1323
1324 /**
1325  * Validate an individual address.
1326  *
1327  * @param address address we should try to validate
1328  */
1329 void
1330 GST_validation_handle_address(const struct GNUNET_HELLO_Address *address)
1331 {
1332   struct GNUNET_TRANSPORT_PluginFunctions *papi;
1333   struct ValidationEntry *ve;
1334
1335   papi = GST_plugins_find(address->transport_name);
1336   if (NULL == papi)
1337     {
1338       /* This plugin is currently unvailable ... ignore */
1339       GNUNET_log(GNUNET_ERROR_TYPE_INFO,
1340                  "No plugin available for %s\n",
1341                  address->transport_name);
1342       return;
1343     }
1344   ve = find_validation_entry(address);
1345   if (NULL == ve->revalidation_task)
1346     {
1347       GNUNET_log(GNUNET_ERROR_TYPE_INFO,
1348                  "Validation process started for fresh address `%s' of %s\n",
1349                  GST_plugins_a2s(ve->address),
1350                  GNUNET_i2s(&ve->address->peer));
1351       ve->revalidation_task = GNUNET_SCHEDULER_add_now(&revalidate_address, ve);
1352     }
1353   else
1354     {
1355       GNUNET_log(GNUNET_ERROR_TYPE_INFO,
1356                  "Validation already running for address `%s' of %s\n",
1357                  GST_plugins_a2s(ve->address),
1358                  GNUNET_i2s(&ve->address->peer));
1359     }
1360 }
1361
1362
1363 /**
1364  * Iterator callback to go over all addresses and try to validate them
1365  * (unless blocked or already validated).
1366  *
1367  * @param cls NULL
1368  * @param address the address
1369  * @param expiration expiration time
1370  * @return #GNUNET_OK (keep the address)
1371  */
1372 static int
1373 validate_address_iterator(void *cls,
1374                           const struct GNUNET_HELLO_Address *address,
1375                           struct GNUNET_TIME_Absolute expiration)
1376 {
1377   if (0 == GNUNET_TIME_absolute_get_remaining(expiration).rel_value_us)
1378     {
1379       GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
1380                  "Skipping expired address from HELLO\n");
1381       return GNUNET_OK;         /* expired */
1382     }
1383   GST_validation_handle_address(address);
1384   return GNUNET_OK;
1385 }
1386
1387
1388 /**
1389  * Add the validated peer address to the HELLO.
1390  *
1391  * @param cls the `struct ValidationEntry *` with the validated address
1392  * @param max space in @a buf
1393  * @param buf where to add the address
1394  * @return number of bytes written, #GNUNET_SYSERR to signal the
1395  *         end of the iteration.
1396  */
1397 static ssize_t
1398 add_valid_peer_address(void *cls,
1399                        size_t max,
1400                        void *buf)
1401 {
1402   struct ValidationEntry *ve = cls;
1403
1404   if (GNUNET_YES == ve->copied)
1405     return GNUNET_SYSERR; /* Done */
1406   ve->copied = GNUNET_YES;
1407   return GNUNET_HELLO_add_address(ve->address,
1408                                   ve->valid_until,
1409                                   buf,
1410                                   max);
1411 }
1412
1413
1414 /**
1415  * We've received a PONG.  Check if it matches a pending PING and
1416  * mark the respective address as confirmed.
1417  *
1418  * @param sender peer sending the PONG
1419  * @param hdr the PONG
1420  * @return #GNUNET_OK if the message was fine, #GNUNET_SYSERR on serious error
1421  */
1422 int
1423 GST_validation_handle_pong(const struct GNUNET_PeerIdentity *sender,
1424                            const struct GNUNET_MessageHeader *hdr)
1425 {
1426   const struct TransportPongMessage *pong;
1427   struct ValidationEntry *ve;
1428   const char *tname;
1429   const char *addr;
1430   size_t addrlen;
1431   size_t slen;
1432   size_t size;
1433   struct GNUNET_HELLO_Message *hello;
1434   struct GNUNET_HELLO_Address address;
1435   int sig_res;
1436   int do_verify;
1437
1438   if (0 ==
1439       memcmp(&GST_my_identity,
1440              sender,
1441              sizeof(struct GNUNET_PeerIdentity)))
1442     return GNUNET_OK; /* our own, ignore! */
1443
1444   if (ntohs(hdr->size) < sizeof(struct TransportPongMessage))
1445     {
1446       GNUNET_break_op(0);
1447       return GNUNET_SYSERR;
1448     }
1449   GNUNET_STATISTICS_update(GST_stats,
1450                            gettext_noop("# PONG messages received"), 1,
1451                            GNUNET_NO);
1452
1453   /* message with structure:
1454    * [TransportPongMessage][Transport name][Address] */
1455
1456   pong = (const struct TransportPongMessage *)hdr;
1457   tname = (const char *)&pong[1];
1458   size = ntohs(hdr->size) - sizeof(struct TransportPongMessage);
1459   addr = memchr(tname, '\0', size);
1460   if (NULL == addr)
1461     {
1462       GNUNET_break_op(0);
1463       return GNUNET_SYSERR;
1464     }
1465   addr++;
1466   slen = strlen(tname) + 1;
1467   addrlen = size - slen;
1468
1469   if (NULL == GST_plugins_find(tname))
1470     {
1471       /* we got the PONG, but the transport plugin specified in it
1472          is not supported by this peer, so this cannot be a good
1473          PONG for us. */
1474       GNUNET_break_op(0);
1475       return GNUNET_OK;
1476     }
1477
1478   address.peer = *sender;
1479   address.address = addr;
1480   address.address_length = addrlen;
1481   address.transport_name = tname;
1482   address.local_info = GNUNET_HELLO_ADDRESS_INFO_NONE;
1483   ve = find_validation_entry(&address);
1484   if ((NULL == ve) || (GNUNET_NO == ve->expecting_pong))
1485     {
1486       GNUNET_STATISTICS_update(GST_stats,
1487                                gettext_noop
1488                                  ("# PONGs dropped, no matching pending validation"),
1489                                1, GNUNET_NO);
1490       return GNUNET_OK;
1491     }
1492   /* now check that PONG is well-formed */
1493   if (0 != memcmp(&ve->address->peer,
1494                   sender,
1495                   sizeof(struct GNUNET_PeerIdentity)))
1496     {
1497       GNUNET_break_op(0);
1498       return GNUNET_SYSERR;
1499     }
1500   if (0 ==
1501       GNUNET_TIME_absolute_get_remaining
1502         (GNUNET_TIME_absolute_ntoh(pong->expiration)).rel_value_us)
1503     {
1504       GNUNET_STATISTICS_update(GST_stats,
1505                                gettext_noop
1506                                  ("# PONGs dropped, signature expired"), 1,
1507                                GNUNET_NO);
1508       return GNUNET_SYSERR;
1509     }
1510
1511   sig_res = GNUNET_SYSERR;
1512   do_verify = GNUNET_YES;
1513   if (0 != GNUNET_TIME_absolute_get_remaining(ve->pong_sig_valid_until).rel_value_us)
1514     {
1515       /* We have a cached and valid signature for this peer,
1516        * try to compare instead of verify */
1517       if (0 == memcmp(&ve->pong_sig_cache,
1518                       &pong->signature,
1519                       sizeof(struct GNUNET_CRYPTO_EddsaSignature)))
1520         {
1521           /* signatures are identical, we can skip verification */
1522           sig_res = GNUNET_OK;
1523           do_verify = GNUNET_NO;
1524         }
1525       else
1526         {
1527           sig_res = GNUNET_SYSERR;
1528           /* signatures do not match, we have to verify */
1529         }
1530     }
1531
1532   if (GNUNET_YES == do_verify)
1533     {
1534       /* Do expensive verification */
1535       sig_res = GNUNET_CRYPTO_eddsa_verify(GNUNET_SIGNATURE_PURPOSE_TRANSPORT_PONG_OWN,
1536                                            &pong->purpose,
1537                                            &pong->signature,
1538                                            &ve->address->peer.public_key);
1539       if (sig_res == GNUNET_SYSERR)
1540         {
1541           GNUNET_break_op(0);
1542           GNUNET_log(GNUNET_ERROR_TYPE_WARNING,
1543                      "Failed to verify: invalid signature on address `%s':%s from peer `%s'\n",
1544                      tname,
1545                      GST_plugins_a2s(ve->address),
1546                      GNUNET_i2s(sender));
1547         }
1548     }
1549   if (sig_res == GNUNET_SYSERR)
1550     {
1551       GNUNET_break_op(0);
1552       return GNUNET_SYSERR;
1553     }
1554
1555   GNUNET_log(GNUNET_ERROR_TYPE_INFO,
1556              "Validation process successful for peer `%s' with plugin `%s' address `%s'\n",
1557              GNUNET_i2s(sender),
1558              tname,
1559              GST_plugins_a2s(ve->address));
1560   GNUNET_STATISTICS_update(GST_stats,
1561                            gettext_noop("# validations succeeded"),
1562                            1,
1563                            GNUNET_NO);
1564   /* validity achieved, remember it! */
1565   ve->expecting_pong = GNUNET_NO;
1566   ve->valid_until = GNUNET_TIME_relative_to_absolute(HELLO_ADDRESS_EXPIRATION);
1567   ve->pong_sig_cache = pong->signature;
1568   ve->pong_sig_valid_until = GNUNET_TIME_absolute_ntoh(pong->expiration);
1569   ve->latency = GNUNET_TIME_absolute_get_duration(ve->send_time);
1570   {
1571     if (GNUNET_YES == ve->known_to_ats)
1572       {
1573         GNUNET_assert(GNUNET_YES ==
1574                       GST_ats_is_known_no_session(ve->address));
1575         GST_ats_update_delay(ve->address,
1576                              GNUNET_TIME_relative_divide(ve->latency, 2));
1577       }
1578     else
1579       {
1580         struct GNUNET_ATS_Properties prop;
1581
1582         memset(&prop, 0, sizeof(prop));
1583         GNUNET_break(GNUNET_NT_UNSPECIFIED != ve->network);
1584         prop.scope = ve->network;
1585         prop.delay = GNUNET_TIME_relative_divide(ve->latency, 2);
1586         GNUNET_assert(GNUNET_NO ==
1587                       GST_ats_is_known_no_session(ve->address));
1588         ve->known_to_ats = GNUNET_YES;
1589         GST_ats_add_address(ve->address, &prop);
1590         GNUNET_assert(GNUNET_YES ==
1591                       GST_ats_is_known_no_session(ve->address));
1592       }
1593   }
1594   if (validations_running > 0)
1595     {
1596       validations_running--;
1597       GNUNET_STATISTICS_set(GST_stats,
1598                             gettext_noop("# validations running"),
1599                             validations_running,
1600                             GNUNET_NO);
1601       GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
1602                  "Validation finished, %u validation processes running\n",
1603                  validations_running);
1604     }
1605   else
1606     {
1607       GNUNET_break(0);
1608     }
1609
1610   /* Notify about new validity */
1611   validation_entry_changed(ve,
1612                            GNUNET_TRANSPORT_VS_UPDATE);
1613
1614   /* build HELLO to store in PEERINFO */
1615   GNUNET_STATISTICS_update(GST_stats,
1616                            gettext_noop("# HELLOs given to peerinfo"),
1617                            1,
1618                            GNUNET_NO);
1619   ve->copied = GNUNET_NO;
1620   hello = GNUNET_HELLO_create(&ve->address->peer.public_key,
1621                               &add_valid_peer_address,
1622                               ve,
1623                               GNUNET_NO);
1624   GNUNET_break(NULL !=
1625                GNUNET_PEERINFO_add_peer(GST_peerinfo,
1626                                         hello,
1627                                         NULL,
1628                                         NULL));
1629   GNUNET_free(hello);
1630   return GNUNET_OK;
1631 }
1632
1633
1634 /**
1635  * We've received a HELLO, check which addresses are new and trigger
1636  * validation.
1637  *
1638  * @param hello the HELLO we received
1639  * @return #GNUNET_OK if the message was fine, #GNUNET_SYSERR on serious error
1640  */
1641 int
1642 GST_validation_handle_hello(const struct GNUNET_MessageHeader *hello)
1643 {
1644   const struct GNUNET_HELLO_Message *hm =
1645     (const struct GNUNET_HELLO_Message *)hello;
1646   struct GNUNET_PeerIdentity pid;
1647   int friend;
1648
1649   friend = GNUNET_HELLO_is_friend_only(hm);
1650   if (((GNUNET_YES != friend) &&
1651        (GNUNET_NO != friend)) ||
1652       (GNUNET_OK != GNUNET_HELLO_get_id(hm, &pid)))
1653     {
1654       /* malformed HELLO */
1655       GNUNET_break_op(0);
1656       return GNUNET_SYSERR;
1657     }
1658   if (0 ==
1659       memcmp(&GST_my_identity,
1660              &pid,
1661              sizeof(struct GNUNET_PeerIdentity)))
1662     {
1663       /* got our own HELLO, how boring */
1664       GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
1665                  "Validation received our own HELLO (%s), ignoring\n",
1666                  GNUNET_i2s(&pid));
1667       return GNUNET_OK;
1668     }
1669   GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
1670              "Validation received HELLO message for peer `%s' with size %u, checking for new addresses\n",
1671              GNUNET_i2s(&pid),
1672              ntohs(hello->size));
1673   GNUNET_assert(NULL ==
1674                 GNUNET_HELLO_iterate_addresses(hm,
1675                                                GNUNET_NO,
1676                                                &validate_address_iterator,
1677                                                NULL));
1678   return GNUNET_OK;
1679 }
1680
1681
1682 /**
1683  * Closure for #iterate_addresses().
1684  */
1685 struct IteratorContext {
1686   /**
1687    * Function to call on each address.
1688    */
1689   GST_ValidationAddressCallback cb;
1690
1691   /**
1692    * Closure for @e cb.
1693    */
1694   void *cb_cls;
1695 };
1696
1697
1698 /**
1699  * Call the callback in the closure for each validation entry.
1700  *
1701  * @param cls the `struct IteratorContext`
1702  * @param key the peer's identity
1703  * @param value the `struct ValidationEntry`
1704  * @return #GNUNET_OK (continue to iterate)
1705  */
1706 static int
1707 iterate_addresses(void *cls,
1708                   const struct GNUNET_PeerIdentity *key,
1709                   void *value)
1710 {
1711   struct IteratorContext *ic = cls;
1712   struct ValidationEntry *ve = value;
1713
1714   ic->cb(ic->cb_cls,
1715          ve->valid_until,
1716          ve->revalidation_block,
1717          ve->address);
1718   return GNUNET_OK;
1719 }
1720
1721
1722 /**
1723  * Call the given function for each address for the given target.
1724  * Can either give a snapshot (synchronous API) or be continuous.
1725  *
1726  * @param target peer information is requested for
1727  * @param cb function to call; will not be called after this function returns
1728  * @param cb_cls closure for @a cb
1729  */
1730 void
1731 GST_validation_get_addresses(const struct GNUNET_PeerIdentity *target,
1732                              GST_ValidationAddressCallback cb,
1733                              void *cb_cls)
1734 {
1735   struct IteratorContext ic;
1736
1737   ic.cb = cb;
1738   ic.cb_cls = cb_cls;
1739   GNUNET_CONTAINER_multipeermap_get_multiple(validation_map,
1740                                              target,
1741                                              &iterate_addresses, &ic);
1742 }
1743
1744
1745 /**
1746  * Update if we are using an address for a connection actively right now.
1747  * Based on this, the validation module will measure latency for the
1748  * address more or less often.
1749  *
1750  * @param address the address that we are now using (or not)
1751  * @param in_use #GNUNET_YES if we are now using the address for a connection,
1752  *               #GNUNET_NO if we are no longer using the address for a connection
1753  */
1754 void
1755 GST_validation_set_address_use(const struct GNUNET_HELLO_Address *address,
1756                                int in_use)
1757 {
1758   struct ValidationEntry *ve;
1759
1760   if (GNUNET_HELLO_address_check_option(address,
1761                                         GNUNET_HELLO_ADDRESS_INFO_INBOUND))
1762     return; /* ignore inbound for validation */
1763   if (NULL == GST_plugins_find(address->transport_name))
1764     {
1765       /* How can we use an address for which we don't have the plugin? */
1766       GNUNET_break(0);
1767       return;
1768     }
1769   ve = find_validation_entry(address);
1770   if (NULL == ve)
1771     {
1772       GNUNET_break(0);
1773       return;
1774     }
1775   if (in_use == ve->in_use)
1776     return;
1777   ve->in_use = in_use;
1778   if (GNUNET_YES == in_use)
1779     {
1780       /* from now on, higher frequeny, so reschedule now */
1781       if (NULL != ve->revalidation_task)
1782         GNUNET_SCHEDULER_cancel(ve->revalidation_task);
1783       ve->revalidation_task = GNUNET_SCHEDULER_add_now(&revalidate_address,
1784                                                        ve);
1785     }
1786 }
1787
1788
1789 /* end of file gnunet-service-transport_validation.c */