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/SecureObjectSync/SOSInternal.h>
  33 #include <Security/SecureObjectSync/SOSFullPeerInfo.h>
  34 #include <Security/SecureObjectSync/SOSPeerInfo.h>
  35 #include <Security/SecureObjectSync/SOSPeer.h>
  36 #include <Security/SecureObjectSync/SOSCoder.h>
  37
  38 #include <utilities/SecCFRelease.h>
  39 #include <utilities/SecCFWrappers.h>
  40 #include <utilities/SecIOFormat.h>
  41 #include <utilities/SecCFError.h>
  42 #include <utilities/debugging.h>
  43
  44 #include <utilities/der_plist.h>
  45 #include <utilities/der_plist_internal.h>
  46
  47 #include <corecrypto/ccder.h>
  48 #include <utilities/iCloudKeychainTrace.h>
  49
  50 #include "AssertMacros.h"
  51
  52 struct __OpaqueSOSCoder {
  53     CFStringRef peer_id;
  54     SecOTRSessionRef sessRef;
  55     bool waitingForDataPacket;
  56     CFDataRef pendingResponse;
  57 };
  58
  59 static const char *SOSCoderString(SOSCoderStatus coderStatus) {
  60     switch (coderStatus) {
  61         case kSOSCoderDataReturned: return "DataReturned";
  62         case kSOSCoderNegotiating: return "Negotiating";
  63         case kSOSCoderNegotiationCompleted: return "NegotiationCompleted";
  64         case kSOSCoderFailure: return "Failure";
  65         case kSOSCoderStaleEvent: return "StaleEvent";
  66         case kSOSCoderTooNew: return "TooNew";
  67         default: return "StatusUnknown";
  68     }
  69 }
  70
  71 /*
  72  static void logRawCoderMessage(const uint8_t* der, uint8_t* der_end, bool encoding)
  73 {
  74 #ifndef NDEBUG
  75     CFStringRef hexMessage = NULL;
  76     if (der && der_end) {
  77         CFIndex length = der_end - der;
  78         CFDataRef message = CFDataCreate(kCFAllocatorDefault, der, length);
  79         hexMessage = CFDataCopyHexString(message);
  80         secnoticeq("coder", "%s RAW [%ld] %@", encoding ? "encode" : "decode", length, hexMessage);
  81         CFReleaseSafe(message);
  82     }
  83     CFReleaseSafe(hexMessage);
  84 #endif
  85 }
  86 */
  87
  88 static size_t der_sizeof_bool(bool value) {
  89     return ccder_sizeof(CCDER_BOOLEAN, 1);
  90 }
  91
  92 static uint8_t* der_encode_bool(bool value, const uint8_t *der, uint8_t *der_end) {
  93     uint8_t valueByte = value;
  94     return ccder_encode_tl(CCDER_BOOLEAN, 1, der,
  95               ccder_encode_body(1, &valueByte, der, der_end));
  96 }
  97
  98 static const uint8_t* der_decode_bool(bool *value, const uint8_t *der, const uint8_t *der_end) {
  99     size_t payload_size = 0;
 100
 101     der = ccder_decode_tl(CCDER_BOOLEAN, &payload_size, der, der_end);
 102
 103     if (payload_size != 1) {
 104         der = NULL;
 105     }
 106
 107     if (der != NULL) {
 108         *value = (*der != 0);
 109         der++;
 110     }
 111
 112     return der;
 113 }
 114
 115 static CFMutableDataRef sessSerialized(SOSCoderRef coder, CFErrorRef *error) {
 116     CFMutableDataRef otr_state = NULL;
 117
 118     if(!coder || !coder->sessRef) {
 119         SOSCreateErrorWithFormat(kSOSErrorUnexpectedType, NULL, error, 0, CFSTR("No session reference."));
 120         return NULL;
 121     }
 122
 123     if ((otr_state = CFDataCreateMutable(NULL, 0)) == NULL) {
 124         SOSCreateErrorWithFormat(kSOSErrorAllocationFailure, NULL, error, 0, CFSTR("Mutable Data allocation failed."));
 125         return NULL;
 126     }
 127
 128     if (errSecSuccess != SecOTRSAppendSerialization(coder->sessRef, otr_state)) {
 129         SOSCreateErrorWithFormat(kSOSErrorEncodeFailure, NULL, error, 0, CFSTR("Append Serialization failed."));
 130         CFReleaseSafe(otr_state);
 131         return NULL;
 132     }
 133
 134     return otr_state;
 135
 136 }
 137
 138 static size_t der_sizeof_optional_data(CFDataRef data) {
 139     return data ? der_sizeof_data(data, NULL) : 0;
 140 }
 141
 142 static uint8_t* der_encode_optional_data(CFDataRef data, CFErrorRef *error, const uint8_t* der, uint8_t* der_end) {
 143     return data ? der_encode_data(data, error, der, der_end) : der_end;
 144 }
 145
 146
 147
 148 static size_t SOSCoderGetDEREncodedSize(SOSCoderRef coder, CFErrorRef *error) {
 149     size_t encoded_size = 0;
 150     CFMutableDataRef otr_state = sessSerialized(coder, error);
 151
 152     if (otr_state) {
 153         size_t data_size = der_sizeof_data(otr_state, error);
 154         size_t waiting_size = der_sizeof_bool(coder->waitingForDataPacket);
 155         size_t pending_size = der_sizeof_optional_data(coder->pendingResponse);
 156
 157         if ((data_size != 0) && (waiting_size != 0))
 158         {
 159             encoded_size = ccder_sizeof(CCDER_CONSTRUCTED_SEQUENCE, data_size + waiting_size + pending_size);
 160         }
 161         CFReleaseSafe(otr_state);
 162     }
 163     return encoded_size;
 164 }
 165
 166
 167 static uint8_t* SOSCoderEncodeToDER(SOSCoderRef coder, CFErrorRef* error, const uint8_t* der, uint8_t* der_end) {
 168     if(!der_end) return NULL;
 169     uint8_t* result = NULL;
 170     CFMutableDataRef otr_state = sessSerialized(coder, error);
 171
 172     if(otr_state) {
 173         result = ccder_encode_constructed_tl(CCDER_CONSTRUCTED_SEQUENCE, der_end, der,
 174                                              der_encode_data(otr_state, error, der,
 175                                              der_encode_bool(coder->waitingForDataPacket, der,
 176                                              der_encode_optional_data(coder->pendingResponse, error, der, der_end))));
 177         CFReleaseSafe(otr_state);
 178     }
 179     return result;
 180 }
 181
 182
 183 CFDataRef SOSCoderCopyDER(SOSCoderRef coder, CFErrorRef* error) {
 184     CFMutableDataRef encoded = NULL;
 185     size_t encoded_size = SOSCoderGetDEREncodedSize(coder, error);
 186
 187     if (encoded_size > 0) {
 188         encoded = CFDataCreateMutable(NULL, encoded_size);
 189         if (encoded) {
 190             CFDataSetLength(encoded, encoded_size);
 191             uint8_t * der = CFDataGetMutableBytePtr(encoded);
 192             uint8_t * der_end = der + encoded_size;
 193             if (!SOSCoderEncodeToDER(coder, error, der, der_end)) {
 194                 CFReleaseNull(encoded);
 195                 encoded = NULL;
 196             }
 197         }
 198     }
 199     return encoded;
 200 }
 201
 202 SOSCoderRef SOSCoderCreateFromData(CFDataRef exportedData, CFErrorRef *error) {
 203     // TODO: fill in errors for all failure cases
 204     //require_action_quiet(coder, xit, SOSCreateError(kSOSErrorSendFailure, CFSTR("No coder for peer"), NULL, error));
 205
 206     SOSCoderRef p = calloc(1, sizeof(struct __OpaqueSOSCoder));
 207
 208     const uint8_t *der = CFDataGetBytePtr(exportedData);
 209     const uint8_t *der_end = der + CFDataGetLength(exportedData);
 210
 211     CFDataRef otr_data = NULL;
 212
 213     ccder_tag tag;
 214     require(ccder_decode_tag(&tag, der, der_end),fail);
 215
 216     switch (tag) {
 217         case CCDER_OCTET_STRING: // TODO: this code is safe to delete?
 218         {
 219             der = der_decode_data(kCFAllocatorDefault, 0, &otr_data, error, der, der_end);
 220             p->waitingForDataPacket = false;
 221         }
 222         break;
 223
 224         case CCDER_CONSTRUCTED_SEQUENCE:
 225         {
 226             const uint8_t *sequence_end = NULL;
 227             der = ccder_decode_sequence_tl(&sequence_end, der, der_end);
 228
 229             require_action_quiet(sequence_end == der_end, fail, SecCFDERCreateError(kSOSErrorDecodeFailure, CFSTR("Extra data in SOS coder"), NULL, error));
 230
 231             der = der_decode_data(kCFAllocatorDefault, 0, &otr_data, error, der, sequence_end);
 232             der = der_decode_bool(&p->waitingForDataPacket, der, sequence_end);
 233             if (der != sequence_end) { // optionally a pending response
 234                 der = der_decode_data(kCFAllocatorDefault, 0, &p->pendingResponse, error, der, sequence_end);
 235             }
 236         }
 237         break;
 238
 239         default:
 240             SecCFDERCreateError(kSOSErrorDecodeFailure, CFSTR("Unsupported SOS Coder DER"), NULL, error);
 241             goto fail;
 242     }
 243
 244     require(der, fail);
 245
 246     p->sessRef = SecOTRSessionCreateFromData(NULL, otr_data);
 247     require(p->sessRef, fail);
 248
 249     CFReleaseSafe(otr_data);
 250     return p;
 251
 252 fail:
 253     SOSCoderDispose(p);
 254     CFReleaseSafe(otr_data);
 255     return NULL;
 256 }
 257
 258
 259 SOSCoderRef SOSCoderCreate(SOSPeerInfoRef peerInfo, SOSFullPeerInfoRef myPeerInfo, CFBooleanRef useCompact, CFErrorRef *error) {
 260     CFAllocatorRef allocator = CFGetAllocator(peerInfo);
 261
 262     SOSCoderRef coder = calloc(1, sizeof(struct __OpaqueSOSCoder));
 263     CFErrorRef localError = NULL;
 264
 265     SecOTRFullIdentityRef myRef = NULL;
 266     SecOTRPublicIdentityRef peerRef = NULL;
 267     SecKeyRef privateKey = NULL;
 268     SecKeyRef publicKey = NULL;
 269
 270     if (myPeerInfo && peerInfo) {
 271         privateKey = SOSFullPeerInfoCopyDeviceKey(myPeerInfo, &localError);
 272         require_quiet(privateKey, errOut);
 273
 274         myRef = SecOTRFullIdentityCreateFromSecKeyRef(allocator, privateKey, &localError);
 275         require_quiet(myRef, errOut);
 276
 277         CFReleaseNull(privateKey);
 278
 279         publicKey = SOSPeerInfoCopyPubKey(peerInfo);
 280
 281         peerRef = SecOTRPublicIdentityCreateFromSecKeyRef(allocator, publicKey, &localError);
 282         require_quiet(peerRef, errOut);
 283
 284         if(useCompact == kCFBooleanTrue)
 285             coder->sessRef = SecOTRSessionCreateFromIDAndFlags(allocator, myRef, peerRef, kSecOTRUseAppleCustomMessageFormat);
 286
 287         else
 288             coder->sessRef = SecOTRSessionCreateFromID(allocator, myRef, peerRef);
 289
 290         require(coder->sessRef, errOut);
 291
 292         coder->waitingForDataPacket = false;
 293         coder->pendingResponse = NULL;
 294
 295         CFReleaseNull(publicKey);
 296         CFReleaseNull(privateKey);
 297         CFReleaseNull(myRef);
 298         CFReleaseNull(peerRef);
 299     } else {
 300         secnotice("coder", "NULL Coder requested, no transport security");
 301     }
 302
 303     SOSCoderStart(coder, NULL);
 304
 305     return coder;
 306
 307 errOut:
 308     secerror("Coder create failed: %@\n", localError ? localError : (CFTypeRef)CFSTR("No local error in SOSCoderCreate"));
 309     secerror("Coder create failed: %@\n", error ? *error : (CFTypeRef)CFSTR("WTF NULL?"));
 310     CFReleaseNull(myRef);
 311     CFReleaseNull(peerRef);
 312     CFReleaseNull(publicKey);
 313     CFReleaseNull(privateKey);
 314
 315     free(coder);
 316     return NULL;
 317 }
 318
 319 void SOSCoderDispose(SOSCoderRef coder)
 320 {
 321     if (coder) {
 322         CFReleaseNull(coder->sessRef);
 323         CFReleaseNull(coder->pendingResponse);
 324         CFReleaseNull(coder->peer_id);
 325         free(coder);
 326     }
 327     coder = NULL;
 328 }
 329
 330 void SOSCoderReset(SOSCoderRef coder)
 331 {
 332     SecOTRSessionReset(coder->sessRef);
 333     coder->waitingForDataPacket = false;
 334     CFReleaseNull(coder->pendingResponse);
 335 }
 336
 337 CFDataRef SOSCoderCopyPendingResponse(SOSCoderRef coder)
 338 {
 339     return coder->pendingResponse ? CFDataCreateCopy(kCFAllocatorDefault, coder->pendingResponse) : NULL;
 340 }
 341
 342 void SOSCoderConsumeResponse(SOSCoderRef coder)
 343 {
 344     CFReleaseNull(coder->pendingResponse);
 345 }
 346
 347 static bool SOSOTRSAppendStartPacket(SecOTRSessionRef session, CFMutableDataRef appendPacket, CFErrorRef *error) {
 348     OSStatus otrStatus = SecOTRSAppendStartPacket(session, appendPacket);
 349     if (otrStatus != errSecSuccess) {
 350         SOSCreateErrorWithFormat(kSOSErrorEncodeFailure, (error != NULL) ? *error : NULL, error, NULL, CFSTR("append start packet returned: %" PRIdOSStatus), otrStatus);
 351     }
 352     return otrStatus == errSecSuccess;
 353 }
 354
 355 // Start OTR negotiation if we haven't already done so.
 356 SOSCoderStatus
 357 SOSCoderStart(SOSCoderRef coder, CFErrorRef *error) {
 358     CFMutableStringRef action = CFStringCreateMutable(kCFAllocatorDefault, 0);
 359     CFStringRef beginState = NULL;
 360     SOSCoderStatus result = kSOSCoderFailure;
 361     CFMutableDataRef startPacket = NULL;
 362
 363     require_action_quiet(coder->sessRef, coderFailure, CFStringAppend(action, CFSTR("*** no otr session ***")));
 364     beginState = CFCopyDescription(coder->sessRef);
 365     require_action_quiet(!coder->waitingForDataPacket, negotiatingOut, CFStringAppend(action, CFSTR("waiting for peer to send first data packet")));
 366     require_action_quiet(!SecOTRSGetIsReadyForMessages(coder->sessRef), coderFailure, CFStringAppend(action, CFSTR("otr session ready"));
 367                          result = kSOSCoderDataReturned);
 368     require_action_quiet(SecOTRSGetIsIdle(coder->sessRef), negotiatingOut, CFStringAppend(action, CFSTR("otr negotiating already")));
 369     require_action_quiet(startPacket = CFDataCreateMutable(kCFAllocatorDefault, 0), coderFailure, SOSCreateError(kSOSErrorAllocationFailure, CFSTR("alloc failed"), NULL, error));
 370     require_quiet(SOSOTRSAppendStartPacket(coder->sessRef, startPacket, error), coderFailure);
 371     CFRetainAssign(coder->pendingResponse, startPacket);
 372
 373 negotiatingOut:
 374     result = kSOSCoderNegotiating;
 375 coderFailure:
 376     // Uber state log
 377     if (result == kSOSCoderFailure && error && *error)
 378         CFStringAppendFormat(action, NULL, CFSTR(" %@"), *error);
 379     secinfo("coder", "%@ %s %@ %@ returned %s", beginState,
 380               SecOTRPacketTypeString(startPacket), action, coder->sessRef, SOSCoderString(result));
 381     CFReleaseNull(startPacket);
 382     CFReleaseSafe(beginState);
 383     CFRelease(action);
 384
 385     return result;
 386
 387 }
 388
 389 SOSCoderStatus
 390 SOSCoderResendDH(SOSCoderRef coder, CFErrorRef *error) {
 391     if(coder->sessRef == NULL) return kSOSCoderDataReturned;
 392     CFMutableDataRef startPacket = CFDataCreateMutable(kCFAllocatorDefault, 0);
 393     SOSCoderStatus result = kSOSCoderFailure;
 394     require_noerr_quiet(SecOTRSAppendRestartPacket(coder->sessRef, startPacket), exit);
 395     secnotice("coder", "Resending OTR Start %@", startPacket);
 396     CFRetainAssign(coder->pendingResponse, startPacket);
 397     result = kSOSCoderNegotiating;
 398 exit:
 399     CFReleaseNull(startPacket);
 400     return result;
 401 }
 402
 403
 404 static SOSCoderStatus nullCoder(CFDataRef from, CFMutableDataRef *to) {
 405     *to = CFDataCreateMutableCopy(NULL, CFDataGetLength(from), from);
 406     return kSOSCoderDataReturned;
 407 }
 408
 409 SOSCoderStatus SOSCoderUnwrap(SOSCoderRef coder, CFDataRef codedMessage, CFMutableDataRef *message,
 410                               CFStringRef clientId, CFErrorRef *error) {
 411     if(codedMessage == NULL) return kSOSCoderDataReturned;
 412     if(coder->sessRef == NULL) return nullCoder(codedMessage, message);
 413     CFMutableStringRef action = CFStringCreateMutable(kCFAllocatorDefault, 0);
 414     /* This should be the "normal" case.  We just use OTR to unwrap the received message. */
 415     SOSCoderStatus result = kSOSCoderFailure;
 416
 417     CFStringRef beginState = CFCopyDescription(coder->sessRef);
 418     enum SecOTRSMessageKind kind = SecOTRSGetMessageKind(coder->sessRef, codedMessage);
 419
 420     switch (kind) {
 421         case kOTRNegotiationPacket: {
 422             /* If we're in here we haven't completed negotiating a session.  Use SecOTRSProcessPacket() to go through
 423              the negotiation steps and immediately send a reply back if necessary using the sendBlock.  This
 424              assumes the sendBlock is still available.
 425              */
 426             CFMutableDataRef response = CFDataCreateMutable(kCFAllocatorDefault, 0);
 427             OSStatus ppstatus = errSecSuccess;
 428             if (response) {
 429                 switch (ppstatus = SecOTRSProcessPacket(coder->sessRef, codedMessage, response)) {
 430                     case errSecSuccess:
 431                         if (CFDataGetLength(response) > 1) {
 432                             CFStringAppendFormat(action, NULL, CFSTR("Sending OTR Response %s"), SecOTRPacketTypeString(response));
 433                             CFRetainAssign(coder->pendingResponse, response);
 434                             result = kSOSCoderNegotiating;
 435                             if (SecOTRSGetIsReadyForMessages(coder->sessRef)) {
 436                                 CFStringAppend(action, CFSTR(" begin waiting for data packet"));
 437                                 coder->waitingForDataPacket = true;
 438                             }
 439                         } else if(!SecOTRSGetIsReadyForMessages(coder->sessRef)) {
 440                             CFStringAppend(action, CFSTR("stuck?"));
 441                             result = kSOSCoderNegotiating;
 442                         } else {
 443                             CFStringAppend(action, CFSTR("completed negotiation"));
 444                             result = kSOSCoderNegotiationCompleted;
 445                             coder->waitingForDataPacket = false;
 446                         }
 447                         break;
 448                     case errSecDecode:
 449                         CFStringAppend(action, CFSTR("resending dh"));
 450                         result = SOSCoderResendDH(coder, error);
 451                         break;
 452                     default:
 453                         SOSCreateErrorWithFormat(kSOSErrorEncodeFailure, (error != NULL) ? *error : NULL, error, NULL, CFSTR("%@ Cannot negotiate session (%ld)"), clientId, (long)ppstatus);
 454                         result = kSOSCoderFailure;
 455                         break;
 456                 };
 457             } else {
 458                 SOSCreateErrorWithFormat(kSOSErrorAllocationFailure, (error != NULL) ? *error : NULL, error, NULL, CFSTR("%@ Cannot allocate CFData"), clientId);
 459                 result = kSOSCoderFailure;
 460             }
 461
 462             CFReleaseNull(response);
 463
 464             break;
 465         }
 466
 467         case kOTRDataPacket:
 468             if(!SecOTRSGetIsReadyForMessages(coder->sessRef)) {
 469                 CFStringAppend(action, CFSTR("not ready for data; resending DH packet"));
 470                                 SetCloudKeychainTraceValueForKey(kCloudKeychainNumberOfTimesSyncFailed, 1);
 471                 result = SOSCoderResendDH(coder, error);
 472             } else {
 473                 if (coder->waitingForDataPacket) {
 474                     CFStringAppend(action, CFSTR("got data packet we were waiting for "));
 475                     coder->waitingForDataPacket = false;
 476                 }
 477                 CFMutableDataRef exposed = CFDataCreateMutable(0, 0);
 478                 OSStatus otrResult = SecOTRSVerifyAndExposeMessage(coder->sessRef, codedMessage, exposed);
 479                 CFStringAppend(action, CFSTR("verify and expose message"));
 480                 if (otrResult) {
 481                     if (otrResult == errSecOTRTooOld) {
 482                         CFStringAppend(action, CFSTR(" too old"));
 483                         result = kSOSCoderStaleEvent;
 484                     }
 485                     else if(otrResult == errSecOTRIDTooNew){
 486                         CFStringAppend(action, CFSTR(" too new"));
 487                         result = kSOSCoderTooNew;
 488                     }else {
 489                         SecError(otrResult, error, CFSTR("%@ Cannot expose message: %" PRIdOSStatus), clientId, otrResult);
 490                         secerror("%@ Decode OTR Protected Packet: %@", clientId, error ? *error : NULL);
 491                         result = kSOSCoderFailure;
 492                     }
 493                 } else {
 494                     CFStringAppend(action, CFSTR("decoded OTR protected packet"));
 495                     *message = exposed;
 496                     exposed = NULL;
 497                     result = kSOSCoderDataReturned;
 498                 }
 499                 CFReleaseNull(exposed);
 500             }
 501             break;
 502
 503         default:
 504             secerror("%@ Unknown packet type: %@", clientId, codedMessage);
 505             SOSCreateError(kSOSErrorDecodeFailure, CFSTR("Unknown packet type"), (error != NULL) ? *error : NULL, error);
 506             result = kSOSCoderFailure;
 507             break;
 508     };
 509
 510     // Uber state log
 511     if (result == kSOSCoderFailure && error && *error)
 512         CFStringAppendFormat(action, NULL, CFSTR(" %@"), *error);
 513     secnotice("coder", "%@ %@ %s %@ %@ returned %s", clientId, beginState,
 514               SecOTRPacketTypeString(codedMessage), action, coder->sessRef, SOSCoderString(result));
 515     CFReleaseSafe(beginState);
 516     CFRelease(action);
 517
 518     return result;
 519 }
 520
 521
 522 SOSCoderStatus SOSCoderWrap(SOSCoderRef coder, CFDataRef message, CFMutableDataRef *codedMessage, CFStringRef clientId, CFErrorRef *error) {
 523     CFMutableStringRef action = CFStringCreateMutable(kCFAllocatorDefault, 0);
 524     SOSCoderStatus result = kSOSCoderDataReturned;
 525     CFStringRef beginState = NULL;
 526     CFMutableDataRef encoded = NULL;
 527     OSStatus otrStatus = 0;
 528
 529     require_action_quiet(coder->sessRef, errOut,
 530                          CFStringAppend(action, CFSTR("*** using null coder ***"));
 531                          result = nullCoder(message, codedMessage));
 532     beginState = CFCopyDescription(coder->sessRef);
 533     require_action_quiet(SecOTRSGetIsReadyForMessages(coder->sessRef), errOut,
 534                          CFStringAppend(action, CFSTR("not ready"));
 535                          result = kSOSCoderNegotiating);
 536     require_action_quiet(!coder->waitingForDataPacket, errOut,
 537                          CFStringAppend(action, CFSTR("waiting for peer to send data packet first"));
 538                          result = kSOSCoderNegotiating);
 539     require_action_quiet(encoded = CFDataCreateMutable(kCFAllocatorDefault, 0), errOut,
 540                          SOSCreateErrorWithFormat(kSOSErrorAllocationFailure, NULL, error, NULL, CFSTR("%@ alloc failed"), clientId);
 541                          result = kSOSCoderFailure);
 542     require_noerr_action_quiet(otrStatus = SecOTRSSignAndProtectMessage(coder->sessRef, message, encoded), errOut,
 543                                SOSCreateErrorWithFormat(kSOSErrorEncodeFailure, (error != NULL) ? *error : NULL, error, NULL, CFSTR("%@ cannot protect message: %" PRIdOSStatus), clientId, otrStatus);
 544                                CFReleaseNull(encoded);
 545                                result = kSOSCoderFailure);
 546     *codedMessage = encoded;
 547
 548 errOut:
 549     // Uber state log
 550     if (result == kSOSCoderFailure && error && *error)
 551         CFStringAppendFormat(action, NULL, CFSTR(" %@"), *error);
 552     secinfo("coder", "%@ %@ %s %@ %@ returned %s", clientId, beginState,
 553               SecOTRPacketTypeString(encoded), action, coder->sessRef, SOSCoderString(result));
 554     CFReleaseSafe(beginState);
 555     CFRelease(action);
 556
 557     return result;
 558 }
 559
 560 bool SOSCoderCanWrap(SOSCoderRef coder) {
 561     return coder->sessRef && SecOTRSGetIsReadyForMessages(coder->sessRef) && !coder->waitingForDataPacket;
 562 }