OSX/sec/SOSCircle/SecureObjectSync/SOSCoder.c

   1 /*
   2  * Copyright (c) 2013-2014 Apple Inc. All Rights Reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23
  24 #include <stdlib.h>
  25
  26 #include <CoreFoundation/CFBase.h>
  27 #include <CoreFoundation/CFError.h>
  28
  29 #include <Security/SecBasePriv.h>
  30 #include <Security/SecOTR.h>
  31 #include <Security/SecOTRSession.h>
  32 #include <Security/SecOTRSessionPriv.h>
  33 #include <Security/SecureObjectSync/SOSInternal.h>
  34 #include <Security/SecureObjectSync/SOSFullPeerInfo.h>
  35 #include <Security/SecureObjectSync/SOSPeerInfo.h>
  36 #include <Security/SecureObjectSync/SOSPeer.h>
  37 #include <Security/SecureObjectSync/SOSCoder.h>
  38
  39 #include <utilities/SecCFRelease.h>
  40 #include <utilities/SecCFWrappers.h>
  41 #include <utilities/SecIOFormat.h>
  42 #include <utilities/SecCFError.h>
  43 #include <utilities/SecCoreCrypto.h>
  44 #include <utilities/debugging.h>
  45
  46 #include <utilities/der_plist.h>
  47 #include <utilities/der_plist_internal.h>
  48
  49 #include <corecrypto/ccder.h>
  50 #include <utilities/iCloudKeychainTrace.h>
  51
  52 #include "AssertMacros.h"
  53
  54 struct __OpaqueSOSCoder {
  55     CFRuntimeBase _base;
  56
  57     CFStringRef peer_id;
  58     SecOTRSessionRef sessRef;
  59     bool waitingForDataPacket;
  60     CFDataRef pendingResponse;
  61
  62     CFDataRef hashOfLastReceived;
  63     bool      lastReceivedWasOld;
  64 };
  65
  66 #define lastReceived_di ccsha1_di
  67
  68 CFGiblisWithCompareFor(SOSCoder)
  69
  70 static CFStringRef SOSCoderCopyFormatDescription(CFTypeRef cf, CFDictionaryRef formatOptions) {
  71     SOSCoderRef coder = (SOSCoderRef)cf;
  72     if(coder){
  73         __block CFStringRef desc = NULL;
  74         CFDataPerformWithHexString(coder->hashOfLastReceived, ^(CFStringRef dataString) {
  75             desc = CFStringCreateWithFormat(kCFAllocatorDefault, NULL, CFSTR("<Coder %@ %@ %s%s>"),
  76                                             coder->sessRef,
  77                                             dataString,
  78                                             coder->waitingForDataPacket ? "W" : "w",
  79                                             coder->lastReceivedWasOld ? "O" : "o"
  80                                             );
  81
  82         });
  83         return desc;
  84     }
  85     else
  86         return CFSTR("NULL");
  87 }
  88
  89 static Boolean SOSCoderCompare(CFTypeRef cfA, CFTypeRef cfB) {
  90     SOSCoderRef coderA = (SOSCoderRef)cfA, coderB = (SOSCoderRef)cfB;
  91     // Use mainly to see if peerB is actually this device (peerA)
  92     return CFStringCompare(coderA->peer_id, coderB->peer_id, 0) == kCFCompareEqualTo;
  93 }
  94
  95
  96 static const char *SOSCoderString(SOSCoderStatus coderStatus) {
  97     switch (coderStatus) {
  98         case kSOSCoderDataReturned: return "DataReturned";
  99         case kSOSCoderNegotiating: return "Negotiating";
 100         case kSOSCoderNegotiationCompleted: return "NegotiationCompleted";
 101         case kSOSCoderFailure: return "Failure";
 102         case kSOSCoderStaleEvent: return "StaleEvent";
 103         case kSOSCoderTooNew: return "TooNew";
 104         default: return "StatusUnknown";
 105     }
 106 }
 107
 108 static CFMutableDataRef sessSerializedCreate(SOSCoderRef coder, CFErrorRef *error) {
 109     CFMutableDataRef otr_state = NULL;
 110
 111     if(!coder || !coder->sessRef) {
 112         SOSCreateErrorWithFormat(kSOSErrorUnexpectedType, NULL, error, 0, CFSTR("No session reference."));
 113         return NULL;
 114     }
 115
 116     if ((otr_state = CFDataCreateMutable(NULL, 0)) == NULL) {
 117         SOSCreateErrorWithFormat(kSOSErrorAllocationFailure, NULL, error, 0, CFSTR("Mutable Data allocation failed."));
 118         return NULL;
 119     }
 120
 121     if (errSecSuccess != SecOTRSAppendSerialization(coder->sessRef, otr_state)) {
 122         SOSCreateErrorWithFormat(kSOSErrorEncodeFailure, NULL, error, 0, CFSTR("Append Serialization failed."));
 123         CFReleaseSafe(otr_state);
 124         return NULL;
 125     }
 126
 127     return otr_state;
 128
 129 }
 130
 131 static size_t der_sizeof_optional_data(CFDataRef data) {
 132     return data ? der_sizeof_data(data, NULL) : 0;
 133 }
 134
 135 static uint8_t* der_encode_optional_data(CFDataRef data, CFErrorRef *error, const uint8_t* der, uint8_t* der_end) {
 136     return data ? der_encode_data(data, error, der, der_end) : der_end;
 137 }
 138
 139
 140
 141 static size_t SOSCoderGetDEREncodedSize(SOSCoderRef coder, CFErrorRef *error) {
 142     size_t encoded_size = 0;
 143     CFMutableDataRef otr_state = sessSerializedCreate(coder, error);
 144
 145     if (otr_state) {
 146         size_t data_size = der_sizeof_data(otr_state, error);
 147         size_t waiting_size = ccder_sizeof_bool(coder->waitingForDataPacket, error);
 148         size_t pending_size = der_sizeof_optional_data(coder->pendingResponse);
 149
 150         if ((data_size != 0) && (waiting_size != 0))
 151         {
 152             encoded_size = ccder_sizeof(CCDER_CONSTRUCTED_SEQUENCE, data_size + waiting_size + pending_size);
 153         }
 154         CFReleaseSafe(otr_state);
 155     }
 156     return encoded_size;
 157 }
 158
 159
 160 static uint8_t* SOSCoderEncodeToDER(SOSCoderRef coder, CFErrorRef* error, const uint8_t* der, uint8_t* der_end) {
 161     if(!der_end) return NULL;
 162     uint8_t* result = NULL;
 163     CFMutableDataRef otr_state = sessSerializedCreate(coder, error);
 164
 165     if(otr_state) {
 166         result = ccder_encode_constructed_tl(CCDER_CONSTRUCTED_SEQUENCE, der_end, der,
 167                                              der_encode_data(otr_state, error, der,
 168                                              ccder_encode_bool(coder->waitingForDataPacket, der,
 169                                              der_encode_optional_data(coder->pendingResponse, error, der, der_end))));
 170         CFReleaseSafe(otr_state);
 171     }
 172     return result;
 173 }
 174
 175 bool SOSCoderIsCoderInAwaitingState(SOSCoderRef coder){
 176     return SecOTRSessionIsSessionInAwaitingState(coder->sessRef);
 177 }
 178
 179 CFDataRef SOSCoderCopyDER(SOSCoderRef coder, CFErrorRef* error) {
 180     CFMutableDataRef encoded = NULL;
 181     size_t encoded_size = SOSCoderGetDEREncodedSize(coder, error);
 182
 183     if (encoded_size > 0) {
 184         encoded = CFDataCreateMutable(NULL, encoded_size);
 185         if (encoded) {
 186             CFDataSetLength(encoded, encoded_size);
 187             uint8_t * der = CFDataGetMutableBytePtr(encoded);
 188             uint8_t * der_end = der + encoded_size;
 189             if (!SOSCoderEncodeToDER(coder, error, der, der_end)) {
 190                 CFReleaseNull(encoded);
 191                 encoded = NULL;
 192             }
 193         }
 194     }
 195     return encoded;
 196 }
 197
 198 static SOSCoderRef SOSCoderCreate_internal() {
 199     SOSCoderRef p = CFTypeAllocate(SOSCoder, struct __OpaqueSOSCoder, kCFAllocatorDefault);
 200
 201     p->peer_id = NULL;
 202     p->sessRef = NULL;
 203     p->pendingResponse = NULL;
 204     p->waitingForDataPacket = false;
 205
 206     p->hashOfLastReceived = NULL;
 207     p->lastReceivedWasOld = false;
 208
 209     return p;
 210
 211 }
 212
 213 // 0 - Type not understood
 214 // 1 - OCTET_STRING, just stored the data for OTR
 215 // 2 - SEQUENCE with no version value
 216 // 3 - SEQUENCE with version value we pull out of the CCDER_INTEGER
 217
 218 typedef enum coderExportFormatVersion {
 219     kNotUnderstood = 0,
 220     kCoderAsOTRDataOnly = 1,
 221     kCoderAsSequence = 2,
 222     kCoderAsVersionedSequence = 3,
 223
 224     kCurrentCoderExportVersion = kCoderAsVersionedSequence
 225 } CoderExportFormatVersion;
 226
 227 static uint64_t SOSCoderGetExportedVersion(const uint8_t *der, const uint8_t *der_end) {
 228     ccder_tag tag;
 229     uint64_t result = kNotUnderstood;
 230     require(ccder_decode_tag(&tag, der, der_end),xit);
 231     switch (tag) {
 232         case CCDER_OCTET_STRING: // TODO: this code is safe to delete?
 233             result = kCoderAsOTRDataOnly;
 234             break;
 235
 236         case CCDER_CONSTRUCTED_SEQUENCE:
 237         {
 238             const uint8_t *sequence_end = NULL;
 239             der = ccder_decode_sequence_tl(&sequence_end, der, der_end);
 240             ccder_tag firstSequenceTag;
 241             require(ccder_decode_tag(&firstSequenceTag, der, der_end),xit);
 242
 243             switch (firstSequenceTag) {
 244                 case CCDER_OCTET_STRING:
 245                     result = kCoderAsSequence;
 246                     break;
 247                 case CCDER_INTEGER:
 248                     der = ccder_decode_uint64(NULL, der, sequence_end);
 249                     if (der == NULL) {
 250                         result = kNotUnderstood;
 251                     } else {
 252                         result = kCoderAsVersionedSequence;
 253                     }
 254                     break;
 255             }
 256         }
 257     }
 258 xit:
 259     return result;
 260
 261 }
 262
 263 SOSCoderRef SOSCoderCreateFromData(CFDataRef exportedData, CFErrorRef *error) {
 264     // TODO: fill in errors for all failure cases
 265     //require_action_quiet(coder, xit, SOSCreateError(kSOSErrorSendFailure, CFSTR("No coder for peer"), NULL, error));
 266
 267     SOSCoderRef p = SOSCoderCreate_internal();
 268
 269     const uint8_t *der = CFDataGetBytePtr(exportedData);
 270     const uint8_t *der_end = der + CFDataGetLength(exportedData);
 271
 272     CFDataRef otr_data = NULL;
 273
 274     switch (SOSCoderGetExportedVersion(der, der_end)) {
 275         case kCoderAsOTRDataOnly:
 276             der = der_decode_data(kCFAllocatorDefault, 0, &otr_data, error, der, der_end);
 277             p->waitingForDataPacket = false;
 278             break;
 279
 280         case kCoderAsSequence:
 281         {
 282             const uint8_t *sequence_end = NULL;
 283             der = ccder_decode_sequence_tl(&sequence_end, der, der_end);
 284
 285             require_action_quiet(sequence_end == der_end, fail, SecCFDERCreateError(kSOSErrorDecodeFailure, CFSTR("Extra data in SOS coder"), NULL, error));
 286
 287             der = der_decode_data(kCFAllocatorDefault, 0, &otr_data, error, der, sequence_end);
 288             der = ccder_decode_bool(&p->waitingForDataPacket, der, sequence_end);
 289             if (der != sequence_end) { // optionally a pending response
 290                 der = der_decode_data(kCFAllocatorDefault, 0, &p->pendingResponse, error, der, sequence_end);
 291             }
 292         }
 293             break;
 294
 295         case kCoderAsVersionedSequence:
 296         {
 297             const uint8_t *sequence_end = NULL;
 298             der = ccder_decode_sequence_tl(&sequence_end, der, der_end);
 299
 300             require_action_quiet(sequence_end == der_end, fail, SecCFDERCreateError(kSOSErrorDecodeFailure, CFSTR("Extra data in SOS coder"), NULL, error));
 301
 302             uint64_t version;
 303             der = ccder_decode_uint64(&version, der, sequence_end);
 304             if (version != kCoderAsVersionedSequence) {
 305                 SOSErrorCreate(kSOSErrorDecodeFailure, error, NULL, CFSTR("Unsupported Sequence Version: %lld"), version);
 306                 goto fail;
 307             }
 308
 309             der = der_decode_data(kCFAllocatorDefault, 0, &otr_data, error, der, sequence_end);
 310             der = ccder_decode_bool(&p->waitingForDataPacket, der, sequence_end);
 311             der = ccder_decode_bool(&p->lastReceivedWasOld, der, sequence_end);
 312             der = der_decode_data(kCFAllocatorDefault, 0, &p->hashOfLastReceived, error, der, sequence_end);
 313             if (der != sequence_end) { // optionally a pending response
 314                 der = der_decode_data(kCFAllocatorDefault, 0, &p->pendingResponse, error, der, sequence_end);
 315             }
 316         }
 317             break;
 318
 319         default:
 320             SOSErrorCreate(kSOSErrorDecodeFailure, error, NULL, CFSTR("Unsupported SOS Coder DER"));
 321             goto fail;
 322     }
 323
 324     require(der, fail);
 325
 326     p->sessRef = SecOTRSessionCreateFromData(NULL, otr_data);
 327     require(p->sessRef, fail);
 328
 329     if (p->hashOfLastReceived == NULL)
 330         p->hashOfLastReceived = CFDataCreateMutableWithScratch(kCFAllocatorDefault, lastReceived_di()->output_size);
 331
 332     CFReleaseSafe(otr_data);
 333     return p;
 334
 335 fail:
 336     CFReleaseNull(p);
 337     CFReleaseSafe(otr_data);
 338     return NULL;
 339 }
 340
 341
 342 SOSCoderRef SOSCoderCreate(SOSPeerInfoRef peerInfo, SOSFullPeerInfoRef myPeerInfo, CFBooleanRef useCompact, CFErrorRef *error) {
 343     CFAllocatorRef allocator = CFGetAllocator(peerInfo);
 344
 345     SOSCoderRef coder = SOSCoderCreate_internal();
 346
 347     CFErrorRef localError = NULL;
 348
 349     SecOTRFullIdentityRef myRef = NULL;
 350     SecOTRPublicIdentityRef peerRef = NULL;
 351     SecKeyRef privateKey = NULL;
 352     SecKeyRef publicKey = NULL;
 353
 354     if (myPeerInfo && peerInfo) {
 355         privateKey = SOSFullPeerInfoCopyDeviceKey(myPeerInfo, &localError);
 356         require_quiet(privateKey, errOut);
 357
 358         myRef = SecOTRFullIdentityCreateFromSecKeyRef(allocator, privateKey, &localError);
 359         require_quiet(myRef, errOut);
 360
 361         CFReleaseNull(privateKey);
 362
 363         publicKey = SOSPeerInfoCopyPubKey(peerInfo, &localError);
 364         require(publicKey, errOut);
 365
 366         peerRef = SecOTRPublicIdentityCreateFromSecKeyRef(allocator, publicKey, &localError);
 367         require_quiet(peerRef, errOut);
 368
 369         if(useCompact == kCFBooleanTrue)
 370             coder->sessRef = SecOTRSessionCreateFromIDAndFlags(allocator, myRef, peerRef, kSecOTRUseAppleCustomMessageFormat);
 371
 372         else
 373             coder->sessRef = SecOTRSessionCreateFromID(allocator, myRef, peerRef);
 374
 375         require(coder->sessRef, errOut);
 376
 377         coder->waitingForDataPacket = false;
 378         coder->pendingResponse = NULL;
 379
 380         CFReleaseNull(publicKey);
 381         CFReleaseNull(privateKey);
 382         CFReleaseNull(myRef);
 383         CFReleaseNull(peerRef);
 384     } else {
 385         secnotice("coder", "NULL Coder requested, no transport security");
 386     }
 387
 388     coder->hashOfLastReceived = CFDataCreateMutableWithScratch(kCFAllocatorDefault, lastReceived_di()->output_size);
 389     coder->lastReceivedWasOld = false;
 390
 391     SOSCoderStart(coder, NULL);
 392
 393     return coder;
 394
 395 errOut:
 396     secerror("Coder create failed: %@\n", localError ? localError : (CFTypeRef)CFSTR("No local error in SOSCoderCreate"));
 397     secerror("Coder create failed: %@\n", error ? *error : (CFTypeRef)CFSTR("WTF NULL?"));
 398     CFReleaseNull(myRef);
 399     CFReleaseNull(peerRef);
 400     CFReleaseNull(publicKey);
 401     CFReleaseNull(privateKey);
 402
 403     CFReleaseNull(coder);
 404     return NULL;
 405 }
 406
 407 static void SOSCoderDestroy(CFTypeRef cf)
 408 {
 409     SOSCoderRef coder = (SOSCoderRef) cf;
 410     if (coder) {
 411         CFReleaseNull(coder->sessRef);
 412         CFReleaseNull(coder->pendingResponse);
 413         CFReleaseNull(coder->hashOfLastReceived);
 414     }
 415 }
 416
 417 void SOSCoderReset(SOSCoderRef coder)
 418 {
 419     SecOTRSessionReset(coder->sessRef);
 420     coder->waitingForDataPacket = false;
 421     CFReleaseNull(coder->pendingResponse);
 422
 423     coder->lastReceivedWasOld = false;
 424     CFReleaseNull(coder->hashOfLastReceived);
 425     coder->hashOfLastReceived = CFDataCreateMutableWithScratch(kCFAllocatorDefault, lastReceived_di()->output_size);
 426 }
 427
 428 bool SOSCoderIsFor(SOSCoderRef coder, SOSPeerInfoRef peerInfo, SOSFullPeerInfoRef myPeerInfo) {
 429     SecKeyRef theirPublicKey = NULL;
 430     SecKeyRef myPublicKey = NULL;
 431     bool isForThisPair = false;
 432     CFErrorRef localError = NULL;
 433
 434     myPublicKey = SOSPeerInfoCopyPubKey(SOSFullPeerInfoGetPeerInfo(myPeerInfo), &localError);
 435     require(myPublicKey, errOut);
 436
 437     theirPublicKey = SOSPeerInfoCopyPubKey(peerInfo, &localError);
 438     require(theirPublicKey, errOut);
 439
 440     isForThisPair = SecOTRSIsForKeys(coder->sessRef, myPublicKey, theirPublicKey);
 441
 442 errOut:
 443     if (localError) {
 444         secerror("SOSCoderIsFor failed: %@\n", localError ? localError : (CFTypeRef)CFSTR("No local error in SOSCoderCreate"));
 445     }
 446
 447     CFReleaseNull(myPublicKey);
 448     CFReleaseNull(theirPublicKey);
 449     CFReleaseNull(localError);
 450     return isForThisPair;
 451 }
 452
 453 CFDataRef SOSCoderCopyPendingResponse(SOSCoderRef coder)
 454 {
 455     return coder->pendingResponse ? CFDataCreateCopy(kCFAllocatorDefault, coder->pendingResponse) : NULL;
 456 }
 457
 458 void SOSCoderConsumeResponse(SOSCoderRef coder)
 459 {
 460     CFReleaseNull(coder->pendingResponse);
 461 }
 462
 463 static bool SOSOTRSAppendStartPacket(SecOTRSessionRef session, CFMutableDataRef appendPacket, CFErrorRef *error) {
 464     OSStatus otrStatus = SecOTRSAppendStartPacket(session, appendPacket);
 465     if (otrStatus != errSecSuccess) {
 466         SOSCreateErrorWithFormat(kSOSErrorEncodeFailure, (error != NULL) ? *error : NULL, error, NULL, CFSTR("append start packet returned: %" PRIdOSStatus), otrStatus);
 467     }
 468     return otrStatus == errSecSuccess;
 469 }
 470
 471 // Start OTR negotiation if we haven't already done so.
 472 SOSCoderStatus
 473 SOSCoderStart(SOSCoderRef coder, CFErrorRef *error) {
 474     CFMutableStringRef action = CFStringCreateMutable(kCFAllocatorDefault, 0);
 475     CFStringRef beginState = NULL;
 476     SOSCoderStatus result = kSOSCoderFailure;
 477     CFMutableDataRef startPacket = NULL;
 478
 479     require_action_quiet(coder->sessRef, coderFailure, CFStringAppend(action, CFSTR("*** no otr session ***")));
 480     beginState = CFCopyDescription(coder->sessRef);
 481     require_action_quiet(!coder->waitingForDataPacket, negotiatingOut, CFStringAppend(action, CFSTR("waiting for peer to send first data packet")));
 482     require_action_quiet(!SecOTRSGetIsReadyForMessages(coder->sessRef), coderFailure, CFStringAppend(action, CFSTR("otr session ready"));
 483                          result = kSOSCoderDataReturned);
 484     require_action_quiet(SecOTRSGetIsIdle(coder->sessRef), negotiatingOut, CFStringAppend(action, CFSTR("otr negotiating already")));
 485     require_action_quiet(startPacket = CFDataCreateMutable(kCFAllocatorDefault, 0), coderFailure, SOSCreateError(kSOSErrorAllocationFailure, CFSTR("alloc failed"), NULL, error));
 486     require_quiet(SOSOTRSAppendStartPacket(coder->sessRef, startPacket, error), coderFailure);
 487     CFRetainAssign(coder->pendingResponse, startPacket);
 488
 489 negotiatingOut:
 490     result = kSOSCoderNegotiating;
 491 coderFailure:
 492     // Uber state log
 493     if (result == kSOSCoderFailure && error && *error)
 494         CFStringAppendFormat(action, NULL, CFSTR(" %@"), *error);
 495     secinfo("coder", "%@ %s %@ %@ returned %s", beginState,
 496               SecOTRPacketTypeString(startPacket), action, coder->sessRef, SOSCoderString(result));
 497     CFReleaseNull(startPacket);
 498     CFReleaseSafe(beginState);
 499     CFRelease(action);
 500
 501     return result;
 502
 503 }
 504
 505 SOSCoderStatus
 506 SOSCoderResendDH(SOSCoderRef coder, CFErrorRef *error) {
 507     if(coder->sessRef == NULL) return kSOSCoderDataReturned;
 508     CFMutableDataRef startPacket = CFDataCreateMutable(kCFAllocatorDefault, 0);
 509     SOSCoderStatus result = kSOSCoderFailure;
 510     require_noerr_quiet(SecOTRSAppendRestartPacket(coder->sessRef, startPacket), exit);
 511     secnotice("coder", "Resending OTR Start %@", startPacket);
 512     CFRetainAssign(coder->pendingResponse, startPacket);
 513     result = kSOSCoderNegotiating;
 514 exit:
 515     CFReleaseNull(startPacket);
 516     return result;
 517 }
 518
 519
 520 static SOSCoderStatus nullCoder(CFDataRef from, CFMutableDataRef *to) {
 521     *to = CFDataCreateMutableCopy(NULL, CFDataGetLength(from), from);
 522     return kSOSCoderDataReturned;
 523 }
 524
 525 SOSCoderStatus SOSCoderUnwrap(SOSCoderRef coder, CFDataRef codedMessage, CFMutableDataRef *message,
 526                               CFStringRef clientId, CFErrorRef *error) {
 527     if(codedMessage == NULL) return kSOSCoderDataReturned;
 528     if(coder->sessRef == NULL) return nullCoder(codedMessage, message);
 529     CFMutableStringRef action = CFStringCreateMutable(kCFAllocatorDefault, 0);
 530     /* This should be the "normal" case.  We just use OTR to unwrap the received message. */
 531     SOSCoderStatus result = kSOSCoderFailure;
 532
 533     CFStringRef beginState = CFCopyDescription(coder->sessRef);
 534     enum SecOTRSMessageKind kind = SecOTRSGetMessageKind(coder->sessRef, codedMessage);
 535
 536
 537     switch (kind) {
 538         case kOTRNegotiationPacket: {
 539             /* If we're in here we haven't completed negotiating a session.  Use SecOTRSProcessPacket() to go through
 540              the negotiation steps and immediately send a reply back if necessary using the sendBlock.  This
 541              assumes the sendBlock is still available.
 542              */
 543             CFMutableDataRef response = CFDataCreateMutable(kCFAllocatorDefault, 0);
 544             OSStatus ppstatus = errSecSuccess;
 545             if (response) {
 546                 switch (ppstatus = SecOTRSProcessPacket(coder->sessRef, codedMessage, response)) {
 547                     case errSecSuccess:
 548                         if (CFDataGetLength(response) > 1) {
 549                             CFStringAppendFormat(action, NULL, CFSTR("Sending OTR Response %s"), SecOTRPacketTypeString(response));
 550                             CFRetainAssign(coder->pendingResponse, response);
 551                             result = kSOSCoderNegotiating;
 552                             if (SecOTRSGetIsReadyForMessages(coder->sessRef)) {
 553                                 CFStringAppend(action, CFSTR(" begin waiting for data packet"));
 554                                 coder->waitingForDataPacket = true;
 555                             }
 556                         } else if(!SecOTRSGetIsReadyForMessages(coder->sessRef)) {
 557                             CFStringAppend(action, CFSTR("stuck?"));
 558                             result = kSOSCoderNegotiating;
 559                         } else {
 560                             CFStringAppend(action, CFSTR("completed negotiation"));
 561                             result = kSOSCoderNegotiationCompleted;
 562                             coder->waitingForDataPacket = false;
 563                         }
 564                         break;
 565                     case errSecDecode:
 566                         CFStringAppend(action, CFSTR("resending dh"));
 567                         result = SOSCoderResendDH(coder, error);
 568                         break;
 569                     default:
 570                         SOSCreateErrorWithFormat(kSOSErrorEncodeFailure, (error != NULL) ? *error : NULL, error, NULL, CFSTR("%@ Cannot negotiate session (%ld)"), clientId, (long)ppstatus);
 571                         result = kSOSCoderFailure;
 572                         break;
 573                 };
 574             } else {
 575                 SOSCreateErrorWithFormat(kSOSErrorAllocationFailure, (error != NULL) ? *error : NULL, error, NULL, CFSTR("%@ Cannot allocate CFData"), clientId);
 576                 result = kSOSCoderFailure;
 577             }
 578
 579             CFReleaseNull(response);
 580
 581             break;
 582         }
 583
 584         case kOTRDataPacket:
 585         {
 586             CFDataRef previousMessageHash = coder->hashOfLastReceived;
 587             coder->hashOfLastReceived = CFDataCreateWithHash(kCFAllocatorDefault, lastReceived_di(), CFDataGetBytePtr(codedMessage), CFDataGetLength(codedMessage));
 588             bool lastWasOld = coder->lastReceivedWasOld;
 589             coder->lastReceivedWasOld = false;
 590
 591             if(!SecOTRSGetIsReadyForMessages(coder->sessRef)) {
 592                 CFStringAppend(action, CFSTR("not ready for data; resending DH packet"));
 593                                 SetCloudKeychainTraceValueForKey(kCloudKeychainNumberOfTimesSyncFailed, 1);
 594                 result = SOSCoderResendDH(coder, error);
 595             } else {
 596                 if (coder->waitingForDataPacket) {
 597                     CFStringAppend(action, CFSTR("got data packet we were waiting for "));
 598                     coder->waitingForDataPacket = false;
 599                 }
 600                 CFMutableDataRef exposed = CFDataCreateMutable(0, 0);
 601                 OSStatus otrResult = SecOTRSVerifyAndExposeMessage(coder->sessRef, codedMessage, exposed);
 602                 CFStringAppend(action, CFSTR("verify and expose message"));
 603                 switch(otrResult) {
 604                     case errSecSuccess:
 605                         CFStringAppend(action, CFSTR("decoded OTR protected packet"));
 606                         CFTransferRetained(*message, exposed);
 607                         result = kSOSCoderDataReturned;
 608                         break;
 609                     case errSecOTRTooOld:
 610                         if (CFEqualSafe(previousMessageHash, coder->hashOfLastReceived)) {
 611                             CFStringAppend(action, CFSTR(" repeated"));
 612                             result = kSOSCoderStaleEvent;
 613                         } else {
 614                             coder->lastReceivedWasOld = true;
 615                             if (lastWasOld) {
 616                                 CFStringAppend(action, CFSTR(" too old, repeated renegotiating"));
 617                                 // Fail so we will renegotiate
 618                                 result = kSOSCoderFailure;
 619                             } else {
 620                                 CFStringAppend(action, CFSTR(" too old, forcing message"));
 621                                 // Force message send.
 622                                 result = kSOSCoderForceMessage;
 623                             }
 624                         }
 625                         break;
 626                     case errSecOTRIDTooNew:
 627                         CFStringAppend(action, CFSTR(" too new"));
 628                         result = kSOSCoderTooNew;
 629                         break;
 630                     default:
 631                         SecError(otrResult, error, CFSTR("%@ Cannot expose message: %" PRIdOSStatus), clientId, otrResult);
 632                         secerror("%@ Decode OTR Protected Packet: %@", clientId, error ? *error : NULL);
 633                         result = kSOSCoderFailure;
 634                         break;
 635                 }
 636
 637                 CFReleaseNull(exposed);
 638             }
 639             CFReleaseNull(previousMessageHash);
 640         }
 641             break;
 642
 643         default:
 644             secerror("%@ Unknown packet type: %@", clientId, codedMessage);
 645             SOSCreateError(kSOSErrorDecodeFailure, CFSTR("Unknown packet type"), (error != NULL) ? *error : NULL, error);
 646             result = kSOSCoderFailure;
 647             break;
 648     };
 649
 650     // Uber state log
 651     if (result == kSOSCoderFailure && error && *error)
 652         CFStringAppendFormat(action, NULL, CFSTR(" %@"), *error);
 653     secnotice("coder", "%@ %@ %s %@ %@ returned %s", clientId, beginState,
 654               SecOTRPacketTypeString(codedMessage), action, coder->sessRef, SOSCoderString(result));
 655     CFReleaseSafe(beginState);
 656     CFRelease(action);
 657
 658     return result;
 659 }
 660
 661
 662 SOSCoderStatus SOSCoderWrap(SOSCoderRef coder, CFDataRef message, CFMutableDataRef *codedMessage, CFStringRef clientId, CFErrorRef *error) {
 663     CFMutableStringRef action = CFStringCreateMutable(kCFAllocatorDefault, 0);
 664     SOSCoderStatus result = kSOSCoderDataReturned;
 665     CFStringRef beginState = NULL;
 666     CFMutableDataRef encoded = NULL;
 667     OSStatus otrStatus = 0;
 668
 669     require_action_quiet(coder->sessRef, errOut,
 670                          CFStringAppend(action, CFSTR("*** using null coder ***"));
 671                          result = nullCoder(message, codedMessage));
 672     beginState = CFCopyDescription(coder->sessRef);
 673     require_action_quiet(SecOTRSGetIsReadyForMessages(coder->sessRef), errOut,
 674                          CFStringAppend(action, CFSTR("not ready"));
 675                          result = kSOSCoderNegotiating);
 676     require_action_quiet(!coder->waitingForDataPacket, errOut,
 677                          CFStringAppend(action, CFSTR("waiting for peer to send data packet first"));
 678                          result = kSOSCoderNegotiating);
 679     require_action_quiet(encoded = CFDataCreateMutable(kCFAllocatorDefault, 0), errOut,
 680                          SOSCreateErrorWithFormat(kSOSErrorAllocationFailure, NULL, error, NULL, CFSTR("%@ alloc failed"), clientId);
 681                          result = kSOSCoderFailure);
 682     require_noerr_action_quiet(otrStatus = SecOTRSSignAndProtectMessage(coder->sessRef, message, encoded), errOut,
 683                                SOSCreateErrorWithFormat(kSOSErrorEncodeFailure, (error != NULL) ? *error : NULL, error, NULL, CFSTR("%@ cannot protect message: %" PRIdOSStatus), clientId, otrStatus);
 684                                CFReleaseNull(encoded);
 685                                result = kSOSCoderFailure);
 686     *codedMessage = encoded;
 687
 688 errOut:
 689     // Uber state log
 690     if (result == kSOSCoderFailure && error && *error)
 691         CFStringAppendFormat(action, NULL, CFSTR(" %@"), *error);
 692     secinfo("coder", "%@ %@ %s %@ %@ returned %s", clientId, beginState,
 693               SecOTRPacketTypeString(encoded), action, coder->sessRef, SOSCoderString(result));
 694     CFReleaseSafe(beginState);
 695     CFRelease(action);
 696
 697     return result;
 698 }
 699
 700 bool SOSCoderCanWrap(SOSCoderRef coder) {
 701     return coder->sessRef && SecOTRSGetIsReadyForMessages(coder->sessRef) && !coder->waitingForDataPacket;
 702 }