OSX/sec/SOSCircle/SecureObjectSync/SOSMessage.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
  25 /*
  26  * SOSMessage.c -  Creation and decoding of SOSMessage objects.
  27  */
  28
  29 #include <Security/SecureObjectSync/SOSMessage.h>
  30
  31 #include <AssertMacros.h>
  32 #include <CoreFoundation/CoreFoundation.h>
  33 #include <Security/SecureObjectSync/SOSDigestVector.h>
  34 #include <Security/SecureObjectSync/SOSManifest.h>
  35 #include <Security/SecureObjectSync/SOSInternal.h>
  36 #include <corecrypto/ccder.h>
  37 #include <stdlib.h>
  38 #include <stdbool.h>
  39 #include <utilities/SecCFError.h>
  40 #include <utilities/SecCFRelease.h>
  41 #include <utilities/SecCFWrappers.h>
  42 #include <utilities/array_size.h>
  43 #include <utilities/der_date.h>
  44 #include <utilities/der_plist.h>
  45 #include <utilities/der_plist_internal.h>
  46 #include <utilities/debugging.h>
  47 #include <utilities/iCloudKeychainTrace.h>
  48
  49 // TODO: This is a layer violation, we need a better way to do this
  50 // Currently it's only used for logging.
  51 #include <securityd/SecItemDataSource.h>
  52
  53 #if defined(SOSMessageFormatSpecification) && 0
  54
  55 -- Secure Object Syncing Peer to Peer Message format ASN.1 definition
  56 -- Everything MUST be DER encoded unless otherwise noted.  These exceptions
  57 -- Allow us to stream messages on a streamy network, without loading more
  58 -- than one object into memory at once.
  59
  60 SOSMessage := SEQUENCE {
  61     CHOICE {
  62         v0          V0-MESSAGE-BODY-CLASS
  63         v2          SOSV2MessageBody
  64     }
  65 }
  66
  67 -- v0 Message
  68
  69 V0-MESSAGE-BODY-CLASS ::= CLASS
  70     {
  71      &messageType    INTEGER (manifestDigest, manifest, manifestDeltaAndObjects)
  72      &version        INTEGER OPTIONAL default v0
  73      &Type
  74     }
  75     WITH SYNTAX {&Type IDENTIFIED BY &messageType}
  76
  77 ManifestDigest ::= OCTECT STRING (length 20)
  78
  79 Manifest ::= OCTECT STRING -- (length 20 * number of entries)
  80
  81 manifestDigestBody ::=
  82     { ManifestDigest IDENTIFIED BY {manifestDigest}}
  83
  84 manifestBody ::=
  85     { Manifest IDENTIFIED BY {manifest}}
  86
  87  manifestDeltaAndObjectsBody ::=
  88     { ManifestDeltaAndObjects IDENTIFIED BY {manifestDeltaAndObjects}}
  89
  90 SOSV1MessageBody ::= MESSAGE-BODY-CLASS
  91
  92 ManifestDeltaAndObjects ::= SEQUENCE {
  93      manfestDigest ManifestDigest
  94      removals Manifest
  95      additions Manifest
  96      addedObjects SEQUENCE OF SOSObject
  97 }
  98
  99 -- v2 Message
 100
 101 SOSMessageBody := {
 102     -- top level SEQUENCE may be Constructed, indefinite-length BER encoded
 103     header         SOSMessageHeader,
 104     deltas         [0] IMPLICIT SOSManifestDeltas OPTIONAL,
 105     extensions     [1] IMPLICIT SOSExtensions OPTIONAL,
 106     objects        [2] IMPLICIT SEQUENCE OF SOSObject OPTIONAL
 107         -- [2] IMPLICIT SEQUENCE OF SOSObject may be Constructed,
 108         -- indefinite-length BER encoded -- }
 109
 110 SOSMessageHeader ::= SEQUENCE {
 111     version         [0] IMPLICIT SOSMessageVersion DEFAULT v2,
 112     creationTime    GeneralizedTime OPTIONAL,
 113         -- When this message was created by the sender for tracking latency
 114     sequenceNumber  SOSSequenceNumber OPTIONAL,
 115         -- Message Sequence Number for tracking packet loss in transport
 116     digestTypes     SOSDigestTypes OPTIONAL,
 117         -- Determines the size and format of each SOSManifestDigest and the
 118         -- elements of each SOSManifest.
 119         -- We send the intersection our desired SOSDigestTypes and our peers
 120         -- last received SOSDigestType. If we never received a message from our
 121         -- peer we send our entire desired set and set the digestTypesProposed
 122         -- messageFlag.
 123         -- If the intersection is the empty set we fallback to sha1
 124         -- Each digest and manifest entry is constructed by appending the
 125         -- agreed upon digests in the order they are listed in the DER encoded
 126         -- digestTypes.
 127     messageFlags    BIT STRING {
 128         getObjects                          (0),
 129         joinRequest                         (1),
 130         partial                             (2),
 131         digestTypesProposed                 (3),
 132             -- This is a partial update and might not contain accurate manifest deltas (check this against spec --mb), only objects
 133         clearGetObjects                     (4), -- WIP mb ignore
 134             -- Stop sending me objects for this delta update, I will send you mine instead if you give me a full manifest delta
 135         didClearGetObjectsSinceLastDelta    (5)  -- WIP mb ignore
 136             -- clearGetObjects was set during this delta update, do not
 137             -- set it again (STICKY until either peer clears delta) -- }
 138         skipHello                           (6)  -- Respond with at least a manifest
 139     senderDigest    SOSManifestDigest,
 140         -- The senders manifest digest at the time of sending this message.
 141     baseDigest      [0] IMPLICIT SOSManifestDigest,
 142         -- What this message is based on, if it contains deltas.  If missing we assume the empty set
 143     proposedDigest  [1] IMPLICIT SOSManifestDigest,
 144         -- What the receiver should have after patching baseDigest with
 145         -- additions and removals -- }
 146
 147 SOSMessageVersion ::= INTEGER { v0(0), v2(2), v3(3) }
 148
 149 SOSSequenceNumber ::= INTEGER
 150
 151 -- Note this is not implemented in v2 it only supports sha1
 152 SOSDigestTypes ::= SEQUENCE {
 153     messageFlags    BIT STRING {
 154         sha1(0) -- implied if SOSDigestTypes is not present
 155             sha224(1)
 156             sha256(2)
 157             sha384(3)
 158             sha512(4)
 159             digestAlgorithms SET OF AlgorithmIdentifier
 160             -- Same as AlgorithmIdentifier from X.509 -- } }
 161
 162 SOSManifestDeltas ::= SEQUENCE {
 163     removals    SOSManifest
 164     additions   SOSManifest }
 165
 166 SOSExtensions ::= SEQUENCE SIZE (1..MAX) OF SOSExtension
 167
 168 SOSExtension ::= SEQUENCE {
 169     extnID      OBJECT IDENTIFIER,
 170     critical    BOOLEAN DEFAULT FALSE,
 171     extnValue   OCTET STRING }
 172
 173 SOSManifest ::= OCTET STRING
 174     -- DER encoding is sorted and ready to merge.
 175     -- All SOSDigest entries in a SOSManifest /must/ be the same size
 176     -- As the negotiated SOSManifestEntry.  Se comment in SOSMessageBody
 177     -- on digestTypes
 178
 179 SOSManifestDigest  ::= OCTET STRING
 180
 181 SOSObject ::= SEQUENCE {
 182     [0] conflict OCTECT STRING OPTIONAL
 183     [1] change OCTECT STRING OPTIONAL
 184     object SecDictionary }
 185
 186 SecDictionary ::= SET of SecKVPair
 187
 188 SecKVPair ::= SEQUENCE {
 189     key UTF8String
 190     value Value }
 191
 192 SecValue ::= CHOICE {
 193     bool Boolean
 194     number INTEGER
 195     string UTF8String
 196     data OCTECT STRING
 197     date GENERAL TIME
 198     dictionary Object
 199     array Array }
 200
 201 SecArray ::= SEQUENCE of SecValue
 202
 203 -- For reference:
 204 AlgorithmIdentifier ::= SEQUENCE {
 205 algorithm        OBJECT IDENTIFIER,
 206 parameters       ANY DEFINED BY algorithm OPTIONAL }
 207 -- contains a value of the type
 208 -- registered for use with the
 209 -- algorithm object identifier value
 210
 211 #endif // defined(SOSMessageFormatSpecification) && 0
 212
 213
 214 #if 0
 215 static inline bool SecMallocOk(const void *ptr) {
 216     if (ptr) return true;
 217
 218     return false;
 219 }
 220 #endif
 221 #if 0
 222 static void appendObjects(CFMutableStringRef desc, CFArrayRef objects) {
 223     __block bool needComma = false;
 224     CFArrayForEach(objects, ^(const void *value) {
 225         if (needComma)
 226             CFStringAppend(desc, CFSTR(","));
 227         else
 228             needComma = true;
 229
 230         SecItemServerAppendItemDescription(desc, value);
 231     });
 232 }
 233 #endif
 234
 235
 236
 237 //
 238 // MARK: SOSMessage implementation.
 239 //
 240
 241 // Legacy v1 message type numbers
 242 enum SOSMessageType {
 243     SOSManifestInvalidMessageType = 0,
 244     SOSManifestDigestMessageType = 1,
 245     SOSManifestMessageType = 2,
 246     SOSManifestDeltaAndObjectsMessageType = 3,
 247 };
 248
 249 struct __OpaqueSOSMessage {
 250     CFRuntimeBase _base;
 251
 252     CFDataRef der;
 253     const uint8_t *objectsDer;
 254     size_t objectsLen;
 255
 256     CFDataRef senderDigest;
 257     CFDataRef baseDigest;
 258     CFDataRef proposedDigest;
 259     SOSManifestRef removals;
 260     SOSManifestRef additions;
 261
 262     CFMutableArrayRef objects;
 263
 264     SOSMessageFlags flags;
 265     uint64_t sequenceNumber;
 266     CFAbsoluteTime creationTime;
 267     uint64_t version;               // Message version (currently always 2)
 268     bool indefiniteLength;          // If set to true the top SEQUENCE and the OBJECTS SEQUENCE are written indefinite length.
 269 };
 270
 271 CFGiblisWithCompareFor(SOSMessage)
 272
 273 static Boolean SOSMessageCompare(CFTypeRef cf1, CFTypeRef cf2) {
 274     SOSMessageRef M = (SOSMessageRef)cf1;
 275     SOSMessageRef P = (SOSMessageRef)cf2;
 276     if (M->flags != P->flags) return false;
 277     if (M->sequenceNumber != P->sequenceNumber) return false;
 278     if (M->creationTime != P->creationTime) return false;
 279     //if (!CFEqualSafe(M->der, P->der)) return false;
 280     if (!CFEqualSafe(M->senderDigest, P->senderDigest)) return false;
 281     if (!CFEqualSafe(M->baseDigest, P->baseDigest)) return false;
 282     if (!CFEqualSafe(M->proposedDigest, P->proposedDigest)) return false;
 283     if (!CFEqualSafe(M->removals, P->removals)) return false;
 284     if (!CFEqualSafe(M->additions, P->additions)) return false;
 285
 286     // TODO Compare Objects if present.
 287
 288     return true;
 289 }
 290
 291 static void SOSMessageDestroy(CFTypeRef cf) {
 292     SOSMessageRef message = (SOSMessageRef)cf;
 293     CFReleaseNull(message->der);
 294     CFReleaseNull(message->senderDigest);
 295     CFReleaseNull(message->baseDigest);
 296     CFReleaseNull(message->proposedDigest);
 297     CFReleaseNull(message->additions);
 298     CFReleaseNull(message->removals);
 299     CFReleaseNull(message->objects);
 300 }
 301
 302 // TODO: Remove this layer violation!
 303 #include <securityd/SecItemServer.h>
 304
 305 static uint64_t SOSMessageInferType(SOSMessageRef message, CFErrorRef *error);
 306
 307 static CFStringRef SOSMessageCopyFormatDescription(CFTypeRef cf, CFDictionaryRef formatOptions) {
 308     SOSMessageRef message = (SOSMessageRef)cf;
 309     static const uint8_t zero[4] = {};
 310     const uint8_t *S = message->senderDigest ? CFDataGetBytePtr(message->senderDigest) : zero;
 311     const uint8_t *B = message->baseDigest ? CFDataGetBytePtr(message->baseDigest) : zero;
 312     const uint8_t *P = message->proposedDigest ? CFDataGetBytePtr(message->proposedDigest) : zero;
 313     CFDateRef creationDate = CFDateCreate(CFGetAllocator(message), message->creationTime);
 314
 315     CFMutableStringRef objects = CFStringCreateMutable(kCFAllocatorDefault, 0);
 316
 317     // TODO: Remove this layer violation!
 318     SOSDataSourceFactoryRef dsf = SecItemDataSourceFactoryGetDefault();
 319     SOSDataSourceRef ds = SOSDataSourceFactoryCreateDataSource(dsf, kSecAttrAccessibleWhenUnlocked, NULL);
 320
 321     __block size_t maxEntries = 16;
 322     CFStringAppendFormat(objects, NULL, CFSTR("{[%zu]"), SOSMessageCountObjects(message));
 323     SOSMessageWithSOSObjects(message, ds, NULL, ^(SOSObjectRef object, bool *stop) {
 324         CFDataRef digest = SOSObjectCopyDigest(ds, object, NULL);
 325         const uint8_t *O = CFDataGetBytePtr(digest);
 326         CFStringAppendFormat(objects, NULL, CFSTR(" %02X%02X%02X%02X"), O[0],O[1],O[2],O[3]);
 327         CFReleaseSafe(digest);
 328         if (!--maxEntries) {
 329             CFStringAppend(objects, CFSTR("..."));
 330             *stop = true;
 331         }
 332     });
 333     CFStringAppend(objects, CFSTR("}"));
 334
 335     CFStringRef desc;
 336     if (message->version == 0) {
 337         switch (SOSMessageInferType(message, NULL)) {
 338             case SOSManifestInvalidMessageType:
 339                 desc = CFStringCreateWithFormat(CFGetAllocator(message), NULL, CFSTR("<MSGInvalid %"PRIu64" >"), message->sequenceNumber);
 340                 break;
 341             case SOSManifestDigestMessageType:
 342                 desc = CFStringCreateWithFormat(CFGetAllocator(message), NULL, CFSTR("<MSGDigest %"PRIu64" %02X%02X%02X%02X>"), message->sequenceNumber, S[0],S[1],S[2],S[3]);
 343                 break;
 344             case SOSManifestMessageType:
 345                 desc = CFStringCreateWithFormat(CFGetAllocator(message), NULL, CFSTR("<MSGManifest %"PRIu64" %@>"), message->sequenceNumber, message->additions);
 346                 break;
 347             case SOSManifestDeltaAndObjectsMessageType:
 348                 desc = CFStringCreateWithFormat(CFGetAllocator(message), NULL, CFSTR("<MSGObjects %"PRIu64" %02X%02X%02X%02X %@ %@ %@"),
 349                                                 message->sequenceNumber,
 350                                                 B[0],B[1],B[2],B[3],
 351                                                 message->removals, message->additions,
 352                                                 objects);
 353                 break;
 354         }
 355     } else {
 356         desc = CFStringCreateWithFormat
 357         (CFGetAllocator(message), NULL, CFSTR("<MSG %"PRIu64" %@ %02X%02X%02X%02X %02X%02X%02X%02X %02X%02X%02X%02X %@ %@ %@ %s%s%s%s%s%s%s>"),
 358         message->sequenceNumber,
 359         creationDate,
 360         S[0],S[1],S[2],S[3],
 361         B[0],B[1],B[2],B[3],
 362         P[0],P[1],P[2],P[3],
 363         message->removals, message->additions,
 364         objects,
 365         (message->flags & kSOSMessageGetObjects) ? "G" : "g",
 366         (message->flags & kSOSMessageJoinRequest) ? "J" : "j",
 367         (message->flags & kSOSMessagePartial) ? "P" : "p",
 368         (message->flags & kSOSMessageDigestTypesProposed) ? "D" : "d",
 369         (message->flags & kSOSMessageClearGetObjects) ? "K" : "k",
 370         (message->flags & kSOSMessageDidClearGetObjectsSinceLastDelta) ? "Z" : "z",
 371         (message->flags & kSOSMessageSkipHello) ? "H" : "h");
 372     }
 373     CFReleaseSafe(creationDate);
 374     CFReleaseSafe(objects);
 375     return desc;
 376 }
 377
 378 //
 379 // MARK: SOSMessage encoding
 380 //
 381
 382 // Create an SOSMessage ready to be encoded.
 383 SOSMessageRef SOSMessageCreate(CFAllocatorRef allocator, uint64_t version, CFErrorRef *error) {
 384     SOSMessageRef message = CFTypeAllocate(SOSMessage, struct __OpaqueSOSMessage, allocator);
 385     message->version = version;
 386     return message;
 387 }
 388
 389 // TODO: Remove me this is for testing only, tests should use the real thing.
 390 SOSMessageRef SOSMessageCreateWithManifests(CFAllocatorRef allocator, SOSManifestRef sender,
 391                                             SOSManifestRef base, SOSManifestRef proposed,
 392                                             bool includeManifestDeltas, CFErrorRef *error) {
 393     SOSMessageRef message = SOSMessageCreate(allocator, kEngineMessageProtocolVersion, error);
 394     if (!SOSMessageSetManifests(message, sender, base, proposed, includeManifestDeltas, NULL, error))
 395         CFReleaseNull(message);
 396     return message;
 397 }
 398
 399 bool SOSMessageSetManifests(SOSMessageRef message, SOSManifestRef sender,
 400                             SOSManifestRef base, SOSManifestRef proposed,
 401                             bool includeManifestDeltas, SOSManifestRef objectsSent,
 402                             CFErrorRef *error) {
 403     if (!message) return true;
 404     bool ok = true;
 405     // TODO: Check at v2 encoding time
 406     // if (!sender) return (SOSMessageRef)SOSErrorCreate(kSOSErrorProcessingFailure, error, NULL, CFSTR("no sender manifest specified for SOSMessage"));
 407     message->baseDigest = CFRetainSafe(SOSManifestGetDigest(base, NULL));
 408     message->proposedDigest = CFRetainSafe(SOSManifestGetDigest(proposed, NULL));
 409     message->senderDigest = CFRetainSafe(SOSManifestGetDigest(sender, NULL));
 410     if (includeManifestDeltas) {
 411         SOSManifestRef additions = NULL;
 412         ok = SOSManifestDiff(base, proposed, &message->removals, &additions, error);
 413         if (message->version == 0) {
 414             message->additions = additions;
 415         } else {
 416             message->additions = SOSManifestCreateComplement(objectsSent, additions, error);
 417             CFReleaseSafe(additions);
 418         }
 419     }
 420     return ok;
 421 }
 422
 423 void SOSMessageSetFlags(SOSMessageRef message, SOSMessageFlags flags) {
 424     message->flags = flags;
 425 }
 426
 427 // Add an extension to this message
 428 void SOSMessageAddExtension(SOSMessageRef message, CFDataRef oid, bool isCritical, CFDataRef extension) {
 429     // TODO: Implement
 430     secerror("not implemented yet!");
 431 }
 432
 433 static bool SecMessageIsObjectValid(CFDataRef object, CFErrorRef *error) {
 434     const uint8_t *der = CFDataGetBytePtr(object);
 435     const uint8_t *der_end = der + CFDataGetLength(object);
 436     ccder_tag tag = 0;
 437     size_t len = 0;
 438     der = ccder_decode_tag(&tag, der, der_end);
 439     if (!der )
 440         return SOSErrorCreate(kSOSErrorBadFormat, error, NULL, CFSTR("Invalid DER, no tag found"));
 441     if (tag == CCDER_EOL)
 442         return SOSErrorCreate(kSOSErrorBadFormat, error, NULL, CFSTR("Object has EOL tag"));
 443     der = ccder_decode_len(&len, der, der_end);
 444     if (!der)
 445         return SOSErrorCreate(kSOSErrorBadFormat, error, NULL, CFSTR("Object with tag %lu has no valid DER length"), tag);
 446     der += len;
 447      if (der_end - der)
 448         return SOSErrorCreate(kSOSErrorBadFormat, error, NULL, CFSTR("Object has %td trailing unused bytes"), der_end - der);
 449     return true;
 450 }
 451
 452 bool SOSMessageAppendObject(SOSMessageRef message, CFDataRef object, CFErrorRef *error) {
 453     if (!SecMessageIsObjectValid(object, error)) return false;
 454     if (!message->objects)
 455         message->objects = CFArrayCreateMutableForCFTypes(CFGetAllocator(message));
 456     if (message->objects)
 457         CFArrayAppendValue(message->objects, object);
 458     return true;
 459 }
 460
 461 static CC_NONNULL_ALL
 462 size_t ccder_sizeof_bit_string(cc_size n, const cc_unit *s) {
 463     return ccder_sizeof(CCDER_BIT_STRING, ccn_sizeof(ccn_bitlen(n, s)) + 1);
 464 }
 465
 466 static CC_NONNULL_ALL
 467 uint8_t *ccder_encode_bit_string(cc_size n, const cc_unit *s, const uint8_t *der, uint8_t *der_end) {
 468     size_t bits = ccn_bitlen(n, s);
 469     size_t out_size = ccn_sizeof(bits) + 1;
 470     der_end = ccder_encode_body_nocopy(out_size, der, der_end);
 471     if (der_end)
 472         ccn_write_uint_padded(n, s, out_size, der_end);
 473     return ccder_encode_tl(CCDER_BIT_STRING, out_size, der, der_end);
 474 }
 475
 476
 477 static
 478 size_t der_sizeof_implicit_data(ccder_tag tag, CFDataRef data) {
 479     if (!data)
 480         return 0;
 481     return ccder_sizeof_implicit_raw_octet_string(tag, CFDataGetLength(data));
 482 }
 483
 484
 485 static CC_NONNULL((3, 4))
 486 uint8_t *der_encode_implicit_data(ccder_tag tag, CFDataRef data, const uint8_t *der, uint8_t *der_end) {
 487     if (!data)
 488         return der_end;
 489     return ccder_encode_implicit_raw_octet_string(tag, CFDataGetLength(data), CFDataGetBytePtr(data), der, der_end);
 490 }
 491
 492 static size_t der_sizeof_message_header(SOSMessageRef message, CFErrorRef *error) {
 493     if (!message->senderDigest) {
 494         // TODO: Create Error.
 495         return 0;
 496     }
 497     cc_unit flags[1];
 498     flags[0] = (cc_unit)message->flags; // TODO Fix cast or something
 499
 500     return ccder_sizeof(CCDER_CONSTRUCTED_SEQUENCE,
 501         der_sizeof_generalizedtime(message->creationTime, error) +
 502         ccder_sizeof_uint64(message->sequenceNumber) +
 503         ccder_sizeof_bit_string(array_size(flags), flags) +
 504         der_sizeof_implicit_data(CCDER_OCTET_STRING, message->senderDigest) +
 505         der_sizeof_implicit_data(0 | CCDER_CONTEXT_SPECIFIC, message->baseDigest) +
 506         der_sizeof_implicit_data(1 | CCDER_CONTEXT_SPECIFIC, message->proposedDigest));
 507 }
 508
 509 static uint8_t *der_encode_message_header(SOSMessageRef message, CFErrorRef *error, const uint8_t *der, uint8_t *der_end) {
 510     if (!message->senderDigest) {
 511         // TODO: Create Error.
 512         return NULL;
 513     }
 514     cc_unit flags[1];
 515     flags[0] = (cc_unit)message->flags; // TODO Fix cast or something
 516     return ccder_encode_constructed_tl(CCDER_CONSTRUCTED_SEQUENCE, der_end, der,
 517         der_encode_generalizedtime(message->creationTime, error, der,
 518         ccder_encode_uint64(message->sequenceNumber, der,
 519         ccder_encode_bit_string(array_size(flags), flags, der,
 520         der_encode_implicit_data(CCDER_OCTET_STRING, message->senderDigest, der,
 521         der_encode_implicit_data(0 | CCDER_CONTEXT_SPECIFIC, message->baseDigest, der,
 522         der_encode_implicit_data(1 | CCDER_CONTEXT_SPECIFIC, message->proposedDigest, der, der_end)))))));
 523 }
 524
 525 static size_t der_sizeof_deltas(SOSMessageRef message) {
 526     if (!message->additions && !message->removals) return 0;
 527     if (message->version == 0) {
 528         return ccder_sizeof(CCDER_OCTET_STRING, SOSManifestGetSize(message->removals))+
 529                ccder_sizeof(CCDER_OCTET_STRING, SOSManifestGetSize(message->additions));
 530     } else {
 531         return ccder_sizeof(0 | CCDER_CONTEXT_SPECIFIC | CCDER_CONSTRUCTED,
 532                             ccder_sizeof(CCDER_OCTET_STRING, SOSManifestGetSize(message->removals))+
 533                             ccder_sizeof(CCDER_OCTET_STRING, SOSManifestGetSize(message->additions)));
 534     }
 535 }
 536
 537 static uint8_t *der_encode_deltas(SOSMessageRef message, CFErrorRef *error, const uint8_t *der, uint8_t *der_end) {
 538     if (!message->additions && !message->removals) return der_end;
 539     if (message->version == 0) {
 540         return der_encode_implicit_data(CCDER_OCTET_STRING, SOSManifestGetData(message->removals), der,
 541             der_encode_implicit_data(CCDER_OCTET_STRING, SOSManifestGetData(message->additions), der, der_end));
 542     } else {
 543         return ccder_encode_constructed_tl(0 | CCDER_CONTEXT_SPECIFIC | CCDER_CONSTRUCTED, der_end, der,
 544             der_encode_implicit_data(CCDER_OCTET_STRING, SOSManifestGetData(message->removals), der,
 545             der_encode_implicit_data(CCDER_OCTET_STRING, SOSManifestGetData(message->additions), der, der_end)));
 546     }
 547 }
 548
 549 static size_t der_sizeof_extensions(SOSMessageRef message) {
 550     // We don't support any yet.
 551     return 0;
 552 }
 553
 554 static uint8_t *der_encode_extensions(SOSMessageRef message, CFErrorRef *error, const uint8_t *der, uint8_t *der_end) {
 555     // We don't support any yet.
 556     return der_end;
 557 }
 558
 559 static size_t der_sizeof_objects(SOSMessageRef message) {
 560     size_t len = 0;
 561     if (message->objects) {
 562         CFDataRef data;
 563         CFArrayForEachC(message->objects, data) {
 564             len += (size_t)CFDataGetLength(data);
 565         }
 566     } else if (message->version != 0)
 567         return 0;
 568
 569     if (message->indefiniteLength)
 570         return len + 4;
 571     else
 572         return ccder_sizeof(2 | CCDER_CONTEXT_SPECIFIC | CCDER_CONSTRUCTED, len);
 573 }
 574
 575 static uint8_t *der_encode_objects(SOSMessageRef message, CFErrorRef *error, const uint8_t *der, uint8_t *der_end) {
 576     if (!message->objects && message->version != 0) return der_end;
 577     const uint8_t *original_der_end = der_end;
 578     if (message->indefiniteLength)
 579         der_end = ccder_encode_tl(CCDER_EOL, 0, der, der_end);
 580
 581     for (CFIndex position = (message->objects ? CFArrayGetCount(message->objects) : 0) - 1; position >= 0; --position) {
 582         CFDataRef object = CFArrayGetValueAtIndex(message->objects, position);
 583         der_end = ccder_encode_body(CFDataGetLength(object), CFDataGetBytePtr(object), der, der_end);
 584     }
 585     if (message->indefiniteLength) {
 586         return ccder_encode_tag(2 | CCDER_CONTEXT_SPECIFIC | CCDER_CONSTRUCTED, der,
 587                ccder_encode_len(0, der, der_end));
 588     } else {
 589         ccder_tag otag = message->version == 0 ? CCDER_CONSTRUCTED_SEQUENCE : 2 | CCDER_CONTEXT_SPECIFIC | CCDER_CONSTRUCTED;
 590         return ccder_encode_constructed_tl(otag, original_der_end, der, der_end);
 591     }
 592 }
 593
 594 static size_t der_sizeof_v2_message(SOSMessageRef message, CFErrorRef *error) {
 595     size_t body_size = (der_sizeof_message_header(message, error) +
 596                         der_sizeof_deltas(message) +
 597                         der_sizeof_extensions(message) +
 598                         der_sizeof_objects(message));
 599     if (message->indefiniteLength)
 600         return body_size + 4;
 601     else
 602         return ccder_sizeof(CCDER_CONSTRUCTED_SEQUENCE, body_size);
 603 }
 604
 605
 606 static uint8_t *der_encode_v2_message(SOSMessageRef message, CFErrorRef *error, const uint8_t *der, uint8_t *der_end) {
 607     const uint8_t *original_der_end = der_end;
 608     if (message->indefiniteLength)
 609         der_end = ccder_encode_tl(CCDER_EOL, 0, der, der_end);
 610
 611     der_end = der_encode_message_header(message, error, der,
 612         der_encode_deltas(message, error, der,
 613         der_encode_extensions(message, error, der,
 614         der_encode_objects(message, error, der, der_end))));
 615
 616     if (message->indefiniteLength) {
 617         return ccder_encode_tag(CCDER_CONSTRUCTED_SEQUENCE, der,
 618                ccder_encode_len(0, der, der_end));
 619     } else {
 620         return ccder_encode_constructed_tl(CCDER_CONSTRUCTED_SEQUENCE, original_der_end, der, der_end);
 621     }
 622 }
 623
 624 //------------------------------------------------------------------------------------------------------------------------------------
 625 //      V1 support
 626 //------------------------------------------------------------------------------------------------------------------------------------
 627
 628 /* ManifestDigest message */
 629 static size_t der_sizeof_manifest_digest_message(SOSMessageRef message, CFErrorRef *error) {
 630     if (!message->senderDigest || CFDataGetLength(message->senderDigest) != SOSDigestSize) {
 631         SOSErrorCreate(kSOSErrorProcessingFailure, error, NULL, CFSTR("digest length mismatch"));
 632         return 0;
 633     }
 634     return ccder_sizeof(CCDER_CONSTRUCTED_SEQUENCE,
 635                         (ccder_sizeof_uint64(SOSManifestDigestMessageType) +
 636                          ccder_sizeof_raw_octet_string(SOSDigestSize)));
 637 }
 638
 639 static uint8_t *der_encode_manifest_digest_message(SOSMessageRef message, CFErrorRef *error, const uint8_t *der, uint8_t *der_end) {
 640     return ccder_encode_constructed_tl(CCDER_CONSTRUCTED_SEQUENCE, der_end, der,
 641            ccder_encode_uint64(SOSManifestDigestMessageType, der,
 642            ccder_encode_raw_octet_string(SOSDigestSize, CFDataGetBytePtr(message->senderDigest), der, der_end)));
 643 }
 644
 645 /* Manifest message */
 646 static size_t der_sizeof_manifest_message(SOSMessageRef message, CFErrorRef *error) {
 647     if (!message->additions) {
 648         SOSErrorCreate(kSOSErrorProcessingFailure, error, NULL, CFSTR("no manifest for manifest message"));
 649         return 0;
 650     }
 651     return ccder_sizeof(CCDER_CONSTRUCTED_SEQUENCE,
 652         (ccder_sizeof_uint64(SOSManifestMessageType) +
 653          der_sizeof_implicit_data(CCDER_OCTET_STRING, SOSManifestGetData(message->additions))));
 654 }
 655
 656 static uint8_t *der_encode_manifest_message(SOSMessageRef message, CFErrorRef *error, const uint8_t *der, uint8_t *der_end) {
 657     return ccder_encode_constructed_tl(CCDER_CONSTRUCTED_SEQUENCE, der_end, der,
 658                ccder_encode_uint64(SOSManifestMessageType, der,
 659                der_encode_implicit_data(CCDER_OCTET_STRING, SOSManifestGetData(message->additions), der, der_end)));
 660 }
 661
 662 /* ManifestDeltaAndObjects message */
 663 static size_t der_sizeof_manifest_and_objects_message(SOSMessageRef message, CFErrorRef *error) {
 664     if (!message->baseDigest || CFDataGetLength(message->baseDigest) != SOSDigestSize) {
 665         SOSErrorCreate(kSOSErrorProcessingFailure, error, NULL, CFSTR("digest length mismatch"));
 666         return 0;
 667     }
 668
 669     return ccder_sizeof(CCDER_CONSTRUCTED_SEQUENCE,
 670         (ccder_sizeof_uint64(SOSManifestDeltaAndObjectsMessageType) +
 671          ccder_sizeof(CCDER_CONSTRUCTED_SEQUENCE,
 672              (ccder_sizeof_raw_octet_string(SOSDigestSize) +
 673               der_sizeof_implicit_data(CCDER_OCTET_STRING, SOSManifestGetData(message->removals)) +
 674               der_sizeof_implicit_data(CCDER_OCTET_STRING, SOSManifestGetData(message->additions)) +
 675               der_sizeof_objects(message)))));
 676 }
 677
 678 static uint8_t *der_encode_manifest_and_objects_message(SOSMessageRef message, CFErrorRef *error, const uint8_t *der, uint8_t *der_end) {
 679     return ccder_encode_constructed_tl(CCDER_CONSTRUCTED_SEQUENCE, der_end, der,
 680                ccder_encode_uint64(SOSManifestDeltaAndObjectsMessageType, der,
 681                ccder_encode_constructed_tl(CCDER_CONSTRUCTED_SEQUENCE, der_end, der,
 682                    ccder_encode_raw_octet_string(SOSDigestSize, CFDataGetBytePtr(message->baseDigest), der,
 683                    der_encode_implicit_data(CCDER_OCTET_STRING, SOSManifestGetData(message->removals), der,
 684                    der_encode_implicit_data(CCDER_OCTET_STRING, SOSManifestGetData(message->additions), der,
 685                    der_encode_objects(message, error, der, der_end)))))));
 686 }
 687
 688 static uint64_t SOSMessageInferType(SOSMessageRef message, CFErrorRef *error) {
 689     if (message->baseDigest) {
 690         // TODO: Assert that we don't have senderDigest or proposedDigest
 691         if (SOSManifestGetCount(message->removals) || SOSManifestGetCount(message->additions) || SOSMessageCountObjects(message)) {
 692             return SOSManifestDeltaAndObjectsMessageType;
 693         } else {
 694             // NOTE: If we force a SOSManifestDeltaAndObjectsMessageType instead then
 695             // true v0 peers will overwrite their last objects message to us.  However this
 696             // implements the current v0 behaviour
 697             return SOSManifestDigestMessageType;
 698         }
 699     } else if (message->additions) {
 700         // TODO: Assert that we don't have senderDigest, proposedDigest, additions, removals or objects
 701         return SOSManifestMessageType;
 702     } else if (message->senderDigest) {
 703         // TODO: Assert that we don't have proposedDigest, removals or objects
 704         return SOSManifestDigestMessageType;
 705     }
 706     // TODO: Create error.
 707     return SOSManifestInvalidMessageType;
 708 }
 709
 710 static size_t der_sizeof_message(SOSMessageRef message, uint64_t messageType, CFErrorRef *error) {
 711     switch (messageType) {
 712         case SOSManifestInvalidMessageType:
 713             return der_sizeof_v2_message(message, error);
 714         case SOSManifestDigestMessageType:
 715             return der_sizeof_manifest_digest_message(message, error);
 716         case SOSManifestMessageType:
 717             return der_sizeof_manifest_message(message, error);
 718         case SOSManifestDeltaAndObjectsMessageType:
 719             return der_sizeof_manifest_and_objects_message(message, error);
 720     }
 721     return 0;
 722 }
 723
 724 static uint8_t *der_encode_message(SOSMessageRef message, uint64_t messageType, CFErrorRef *error, const uint8_t *der, uint8_t *der_end) {
 725     switch (messageType) {
 726         case SOSManifestInvalidMessageType:
 727             return der_encode_v2_message(message, error, der, der_end);
 728         case SOSManifestDigestMessageType:
 729             return der_encode_manifest_digest_message(message, error, der, der_end);
 730         case SOSManifestMessageType:
 731             return der_encode_manifest_message(message, error, der, der_end);
 732         case SOSManifestDeltaAndObjectsMessageType:
 733             return der_encode_manifest_and_objects_message(message, error, der, der_end);
 734     }
 735     return der_end;
 736 }
 737
 738 // Encode an SOSMessage, calls addObject callback and appends returned objects
 739 // one by one, until addObject returns NULL.
 740 CFDataRef SOSMessageCreateData(SOSMessageRef message, uint64_t sequenceNumber, CFErrorRef *error) {
 741     // Version 2 message have sequence numbers, version 0 messages do not.
 742     uint64_t messageType = SOSManifestInvalidMessageType;
 743     message->sequenceNumber = sequenceNumber;
 744     if (message->version == 0) {
 745         message->indefiniteLength = false;
 746         messageType = SOSMessageInferType(message, error);
 747         if (!messageType) {
 748             // Propagate error
 749             return NULL;
 750         }
 751     } else {
 752         message->creationTime = floor(CFAbsoluteTimeGetCurrent());
 753     }
 754     size_t der_size = der_sizeof_message(message, messageType, error);
 755     CFMutableDataRef data = CFDataCreateMutable(NULL, der_size);
 756     if (data == NULL) {
 757         // TODO Error.
 758         return NULL;
 759     }
 760     CFDataSetLength(data, der_size);
 761     uint8_t *der_end = CFDataGetMutableBytePtr(data);
 762     const uint8_t *der = der_end;
 763     der_end += der_size;
 764
 765     der_end = der_encode_message(message, messageType, error, der, der_end);
 766     if (der != der_end) {
 767         secwarning("internal error %td bytes unused in der buffer", der_end - der);
 768     }
 769     return data;
 770 }
 771
 772 //
 773 // MARK: SOSMessage decoding
 774 //
 775
 776 #define CCBER_LEN_INDEFINITE ((size_t)-1)
 777
 778 // Decode BER length field.  Sets *lenp to ccber_indefinite_len if this is an indefinite length encoded object.
 779 // Behaves like ccder_decode_len in every other way.
 780 static CC_NONNULL((1, 3))
 781 const uint8_t *ccber_decode_len(size_t *lenp, const uint8_t *der, const uint8_t *der_end) {
 782     if (der && der < der_end) {
 783         if (*der == 0x80) {
 784             der++;
 785             *lenp = CCBER_LEN_INDEFINITE;
 786         }
 787         else
 788             der = ccder_decode_len(lenp, der, der_end);
 789     }
 790     return der;
 791 }
 792
 793 static const uint8_t *der_decode_generalizedtime(CFAbsoluteTime *at, CFErrorRef *error, const uint8_t *der, const uint8_t *der_end) {
 794     const uint8_t *times_end = NULL;
 795     der = ccder_decode_constructed_tl(CCDER_GENERALIZED_TIME, &times_end, der, der_end);
 796     der = der_decode_generalizedtime_body(at, error, der, times_end);
 797     if (times_end != der) {
 798         secwarning("internal error %td bytes unused in generalizedtime DER buffer", times_end - der);
 799     }
 800     return der;
 801 }
 802
 803 static const uint8_t *der_decode_optional_generalizedtime(CFAbsoluteTime *at, CFErrorRef *error, const uint8_t *der, const uint8_t *der_end) {
 804     const uint8_t *times_end = der_decode_generalizedtime(at, error, der, der_end);
 805     return times_end ? times_end : der;
 806 }
 807
 808 static CC_NONNULL((2, 4))
 809 const uint8_t *ccder_decode_implicit_uint64(ccder_tag expected_tag, uint64_t* r, const uint8_t *der, const uint8_t *der_end) {
 810     size_t len;
 811     der = ccder_decode_tl(expected_tag, &len, der, der_end);
 812     if (der && len && (*der & 0x80) != 0x80) {
 813         if (ccn_read_uint(ccn_nof_size(sizeof(*r)), (cc_unit*)r, len, der) >= 0)
 814             return der + len;
 815     }
 816     return NULL;
 817 }
 818
 819 static const uint8_t *ccder_decode_optional_implicit_uint64(ccder_tag expected_tag, uint64_t *value, const uint8_t *der, const uint8_t *der_end) {
 820     const uint8_t *ui64_end = ccder_decode_implicit_uint64(expected_tag, value, der, der_end);
 821     return ui64_end ? ui64_end : der;
 822 }
 823
 824
 825 static const uint8_t *ccder_decode_optional_uint64(uint64_t *value, const uint8_t *der, const uint8_t *der_end) {
 826     const uint8_t *ui64_end = ccder_decode_uint64(value, der, der_end);
 827     return ui64_end ? ui64_end : der;
 828 }
 829
 830 static const uint8_t *ccder_decode_digest_types(SOSMessageRef message, const uint8_t *der, const uint8_t *der_end) {
 831     const uint8_t *dt_end;
 832     der = ccder_decode_sequence_tl(&dt_end, der, der_end);
 833     if (!der) return NULL;
 834     // Skip over digestType body for now.
 835     // TODO: Support DigestType
 836     return dt_end;
 837 }
 838
 839 static const uint8_t *ccder_decode_optional_digest_types(SOSMessageRef message, const uint8_t *der, const uint8_t *der_end) {
 840     const uint8_t *dt_end = ccder_decode_digest_types(message, der, der_end);
 841     return dt_end ? dt_end : der;
 842 }
 843
 844 static const uint8_t *ccder_decode_bit_string(cc_size n, size_t *r_bitlen, cc_unit *r, const uint8_t *der, const uint8_t *der_end) {
 845     size_t len;
 846     const uint8_t *body = ccder_decode_tl(CCDER_BIT_STRING, &len, der, der_end);
 847     if (!body || len < 1)
 848         return NULL;
 849
 850     if (r_bitlen) *r_bitlen = (len - 1) * 8 - (body[0] & 7);
 851     ccn_read_uint(1, r, len - 1, body + 1);
 852     return body + len;
 853 }
 854
 855 static const uint8_t *der_decode_implicit_data(ccder_tag expected_tag, CFDataRef *data, const uint8_t *der, const uint8_t *der_end) {
 856     size_t len = 0;
 857     der = ccder_decode_tl(expected_tag, &len, der, der_end);
 858     if (der && data) {
 859         *data = CFDataCreateWithBytesNoCopy(kCFAllocatorDefault, der, len, kCFAllocatorNull);
 860         if (*data)
 861             der += len;
 862         else
 863             der = NULL;
 864     }
 865     return der;
 866 }
 867
 868 static const uint8_t *der_decode_optional_implicit_data(ccder_tag expected_tag, CFDataRef *data, const uint8_t *der, const uint8_t *der_end) {
 869     const uint8_t *data_end = der_decode_implicit_data(expected_tag, data, der, der_end);
 870     return data_end ? data_end : der;
 871 }
 872
 873 static const uint8_t *der_decode_deltas_body(SOSMessageRef message, CFErrorRef *error, const uint8_t *der, const uint8_t *der_end) {
 874     CFDataRef removals = NULL, additions = NULL;
 875     der = der_decode_implicit_data(CCDER_OCTET_STRING, &removals, der, der_end);
 876     der = der_decode_implicit_data(CCDER_OCTET_STRING, &additions, der, der_end);
 877     if (der) {
 878         message->removals = SOSManifestCreateWithData(removals, error);
 879         message->additions = SOSManifestCreateWithData(additions, error);
 880         if (!message->removals || !message->additions) {
 881             CFReleaseNull(message->removals);
 882             CFReleaseNull(message->additions);
 883             der = NULL;
 884         }
 885     }
 886     CFReleaseSafe(removals);
 887     CFReleaseSafe(additions);
 888
 889     return der;
 890 }
 891
 892 static const uint8_t *der_decode_deltas(SOSMessageRef message, CFErrorRef *error, const uint8_t *der, const uint8_t *der_end) {
 893     const uint8_t *deltas_end = NULL;
 894     der = ccder_decode_constructed_tl(0 | CCDER_CONTEXT_SPECIFIC | CCDER_CONSTRUCTED, &deltas_end, der, der_end);
 895     return der_decode_deltas_body(message, error, der, deltas_end);
 896 }
 897
 898 static const uint8_t *der_decode_optional_deltas(SOSMessageRef message, const uint8_t *der, const uint8_t *der_end) {
 899     const uint8_t *seq_end = der_decode_deltas(message, NULL, der, der_end);
 900     return seq_end ? seq_end : der;
 901 }
 902
 903 static const uint8_t *der_decode_extensions(SOSMessageRef message, CFErrorRef *error, const uint8_t *der, const uint8_t *der_end) {
 904     const uint8_t *extensions_end;
 905     der = ccder_decode_constructed_tl(1 | CCDER_CONTEXT_SPECIFIC | CCDER_CONSTRUCTED, &extensions_end, der, der_end);
 906     if (!der) return NULL;
 907     // Skip over extensions for now.
 908     return extensions_end;
 909 }
 910
 911 static const uint8_t *der_decode_optional_extensions(SOSMessageRef message, CFErrorRef *error, const uint8_t *der, const uint8_t *der_end) {
 912     const uint8_t *extensions_end = der_decode_extensions(message, NULL, der, der_end);
 913     return extensions_end ? extensions_end : der;
 914 }
 915
 916 static const uint8_t *der_foreach_objects(size_t length, const uint8_t *der, const uint8_t *der_end, CFErrorRef *error, void(^withObject)(CFDataRef object, bool *stop)) {
 917     bool stop = false;
 918     ccder_tag tag;
 919     // Look ahead at the tag
 920     while (!stop && ccder_decode_tag(&tag, der, der_end) && tag != CCDER_EOL) {
 921         const uint8_t *object_end = NULL;
 922         if (!ccder_decode_constructed_tl(tag, &object_end, der, der_end)) {
 923             SOSErrorCreate(kSOSErrorDecodeFailure, error, NULL, CFSTR("failed to decode object header"));
 924             return NULL;
 925         }
 926         if (withObject) {
 927             CFDataRef object = CFDataCreateWithBytesNoCopy(kCFAllocatorDefault, der, object_end - der, kCFAllocatorNull);
 928             withObject(object, &stop);
 929             CFReleaseSafe(object);
 930         }
 931         der = object_end;
 932     }
 933     if (length == CCBER_LEN_INDEFINITE) {
 934         size_t len = 0;
 935         der = ccder_decode_tl(CCDER_EOL, &len, der, der_end);
 936         if (len != 0) {
 937             secwarning("%td length ", der_end - der);
 938         }
 939     }
 940     if (!stop && der != der_end)
 941         secwarning("%td trailing bytes after objects DER", der_end - der);
 942
 943     return der;
 944 }
 945
 946 static const uint8_t *der_decode_objects(SOSMessageRef message, CFErrorRef *error, const uint8_t *der, const uint8_t *der_end) {
 947     ccder_tag tag = 0;
 948     size_t objects_len = 0;
 949     der = ccder_decode_tag(&tag, der, der_end);
 950     if (tag != (2 | CCDER_CONTEXT_SPECIFIC | CCDER_CONSTRUCTED)) return NULL;
 951     der = ccber_decode_len(&objects_len, der, der_end);
 952     if (objects_len != CCBER_LEN_INDEFINITE && der_end - der != (ptrdiff_t)objects_len) {
 953         secwarning("%td trailing bytes after SOSMessage DER", (der_end - der) - (ptrdiff_t)objects_len);
 954     }
 955     // Remember a pointer into message->der where objects starts.
 956     message->objectsDer = der;
 957     message->objectsLen = objects_len;
 958
 959     return der + objects_len;
 960 }
 961
 962 static const uint8_t *der_decode_optional_objects(SOSMessageRef message, CFErrorRef *error, const uint8_t *der, const uint8_t *der_end) {
 963     const uint8_t *seq_end = der_decode_objects(message, NULL, der, der_end);
 964     return seq_end ? seq_end : der;
 965 }
 966
 967 #if 0
 968 // Move to ccder and possibly refactor ccder_decode_constructed_tl to call this.
 969 #ifdef CCDER_DECODE_CONSTRUCTED_LEN_SPECIFIER
 970 CCDER_DECODE_CONSTRUCTED_LEN_SPECIFIER
 971 #endif
 972 inline CC_NONNULL((1, 3))
 973 const uint8_t *
 974 ccder_decode_constructed_len(const uint8_t **body_end,
 975                              const uint8_t *der, const uint8_t *der_end) {
 976     size_t len;
 977     der = ccder_decode_len(&len, der, der_end);
 978     *body_end = der + len;
 979     return der;
 980 }
 981 #endif
 982
 983 static const uint8_t *der_decode_message_header(SOSMessageRef message, CFErrorRef *error, const uint8_t *der, const uint8_t *der_end) {
 984     cc_unit flags[1] = {};
 985     der = ccder_decode_constructed_tl(CCDER_CONSTRUCTED_SEQUENCE, &der_end, der, der_end);
 986     message->version = 2;
 987     der = ccder_decode_optional_implicit_uint64(0 | CCDER_CONTEXT_SPECIFIC, &message->version, der, der_end);
 988     der = der_decode_optional_generalizedtime(&message->creationTime, error, der, der_end);
 989     der = ccder_decode_optional_uint64(&message->sequenceNumber, der, der_end);
 990     der = ccder_decode_optional_digest_types(message, der, der_end);
 991     der = ccder_decode_bit_string(array_size(flags), NULL, flags, der, der_end);
 992     message->flags = flags[0];
 993
 994     der = der_decode_implicit_data(CCDER_OCTET_STRING, &message->senderDigest, der, der_end);
 995     der = der_decode_optional_implicit_data(0 | CCDER_CONTEXT_SPECIFIC, &message->baseDigest, der, der_end);
 996     der = der_decode_optional_implicit_data(1 | CCDER_CONTEXT_SPECIFIC, &message->proposedDigest, der, der_end);
 997     return der;
 998 }
 999
1000 static const uint8_t *
1001 der_decode_manifest_and_objects_message(SOSMessageRef message,
1002                                         CFErrorRef *error, const uint8_t *der,
1003                                         const uint8_t *der_end) {
1004     size_t objects_len = 0;
1005     const uint8_t *body_end;
1006     der = ccder_decode_sequence_tl(&body_end, der, der_end);
1007     if (body_end != der_end) {
1008         SOSErrorCreate(kSOSErrorInvalidMessage, error, NULL, CFSTR("Trailing garbage at end of message"));
1009         return NULL;
1010     }
1011     der = der_decode_implicit_data(CCDER_OCTET_STRING, &message->baseDigest, der, body_end);
1012     der = der_decode_deltas_body(message, error, der, body_end);
1013     // Remember a pointer into message->der where objects starts.
1014     der = message->objectsDer = ccder_decode_tl(CCDER_CONSTRUCTED_SEQUENCE, &objects_len, der, body_end);
1015     message->objectsLen = objects_len;
1016
1017     return der ? der + objects_len : NULL;
1018 }
1019
1020 static const uint8_t *der_decode_v0_message_body(SOSMessageRef message, CFErrorRef *error, const uint8_t *der, const uint8_t *der_end) {
1021     uint64_t messageType = 0;
1022     der = ccder_decode_uint64(&messageType, der, der_end);
1023     if (der) switch (messageType) {
1024         case SOSManifestDigestMessageType:
1025         {
1026             der = der_decode_implicit_data(CCDER_OCTET_STRING, &message->senderDigest, der, der_end);
1027             break;
1028         }
1029         case SOSManifestMessageType:
1030         {
1031             CFDataRef manifestBody = NULL;
1032             der = der_decode_implicit_data(CCDER_OCTET_STRING, &manifestBody, der, der_end);
1033             if (!der) return NULL;
1034             if (der != der_end) {
1035                 secwarning("%td trailing bytes after deltas DER", der_end - der);
1036             }
1037             message->additions = SOSManifestCreateWithData(manifestBody, error);
1038             CFReleaseSafe(manifestBody);
1039             break;
1040         }
1041         case SOSManifestDeltaAndObjectsMessageType:
1042         {
1043             der = der_decode_manifest_and_objects_message(message, error, der, der_end);
1044             break;
1045         }
1046         default:
1047             SOSErrorCreate(kSOSErrorInvalidMessage, error, NULL, CFSTR("Invalid message type %llu"), messageType);
1048             break;
1049     }
1050     return der;
1051 }
1052
1053 static const uint8_t *der_decode_message(SOSMessageRef message, CFErrorRef *error, const uint8_t *der, const uint8_t *der_end) {
1054     ccder_tag tag = 0;
1055     size_t body_len = 0;
1056
1057     der = ccder_decode_tag(&tag, der, der_end);
1058     if (tag != CCDER_CONSTRUCTED_SEQUENCE) return NULL;
1059     der = ccber_decode_len(&body_len, der, der_end);
1060     if (der && body_len && body_len != CCBER_LEN_INDEFINITE && (der_end - der) != (ptrdiff_t)body_len) {
1061         secwarning("%td trailing bytes after SOSMessage DER", (der_end - der) - (ptrdiff_t)body_len);
1062         der_end = der + body_len;
1063     }
1064
1065     if (ccder_decode_tag(&tag, der, der_end)) switch (tag) {
1066         case CCDER_INTEGER: // v0
1067             if (body_len == CCBER_LEN_INDEFINITE)
1068                 der = NULL; // Not supported for v0 messages
1069             else
1070                 der = der_decode_v0_message_body(message, error, der, der_end);
1071             break;
1072         case CCDER_CONSTRUCTED_SEQUENCE: //v2
1073             der = der_decode_message_header(message, error, der, der_end);
1074             der = der_decode_optional_deltas(message, der, der_end);
1075             der = der_decode_optional_extensions(message, error, der, der_end);
1076             der = der_decode_optional_objects(message, error, der, der_end);
1077         break;
1078     }
1079     return der;
1080 }
1081
1082 // Decode a SOSMessage
1083 SOSMessageRef SOSMessageCreateWithData(CFAllocatorRef allocator, CFDataRef derData, CFErrorRef *error) {
1084     if (!derData)
1085         return (SOSMessageRef)SOSErrorCreate(kSOSErrorDecodeFailure, error, NULL, CFSTR("NULL data => no SOSMessage"));
1086     SOSMessageRef message = CFTypeAllocate(SOSMessage, struct __OpaqueSOSMessage, allocator);
1087     if (!message)
1088         return (SOSMessageRef)SOSErrorCreate(kSOSErrorAllocationFailure, error, NULL, CFSTR("failed to alloc SOSMessage"));
1089     message->der = CFRetainSafe(derData);
1090     const uint8_t *der = CFDataGetBytePtr(derData);
1091     const uint8_t *der_end = der + CFDataGetLength(derData);
1092     der = der_decode_message(message, error, der, der_end);
1093     if (!der_end || der != der_end) {
1094         if (error && !*error)
1095             SOSErrorCreate(kSOSErrorDecodeFailure, error, NULL, CFSTR("SOSMessage DER decoding failure %td bytes left"), der_end - der);
1096         return CFReleaseSafe(message);
1097     }
1098     return message;
1099 }
1100
1101 // Read values from a decoded messgage
1102
1103 CFDataRef SOSMessageGetBaseDigest(SOSMessageRef message) {
1104     return message->baseDigest;
1105 }
1106
1107 CFDataRef SOSMessageGetProposedDigest(SOSMessageRef message) {
1108     return message->proposedDigest;
1109 }
1110
1111 CFDataRef SOSMessageGetSenderDigest(SOSMessageRef message) {
1112     return message->senderDigest;
1113 }
1114
1115 SOSMessageFlags SOSMessageGetFlags(SOSMessageRef message) {
1116     return message->flags;
1117 }
1118
1119 uint64_t SOSMessageGetSequenceNumber(SOSMessageRef message) {
1120     return message->sequenceNumber;
1121 }
1122
1123 SOSManifestRef SOSMessageGetRemovals(SOSMessageRef message) {
1124     return message->removals;
1125 }
1126
1127 SOSManifestRef SOSMessageGetAdditions(SOSMessageRef message) {
1128     return message->additions;
1129 }
1130
1131 // Iterate though the extensions in a decoded SOSMessage.  If criticalOnly is
1132 // true all non critical extensions are skipped.
1133 void SOSMessageWithExtensions(SOSMessageRef message, bool criticalOnly, void(^withExtension)(CFDataRef oid, bool isCritical, CFDataRef extension, bool *stop)) {
1134     // TODO
1135 }
1136
1137 size_t SOSMessageCountObjects(SOSMessageRef message) {
1138     if (message->objects)
1139         return CFArrayGetCount(message->objects);
1140     if (!message->objectsDer)
1141         return 0;
1142     const uint8_t *der = CFDataGetBytePtr(message->der);
1143     const uint8_t *der_end = der + CFDataGetLength(message->der);
1144     __block size_t count = 0;
1145     der_foreach_objects(message->objectsLen, message->objectsDer, der_end, NULL, ^(CFDataRef object, bool *stop){ ++count; });
1146     return count;
1147 }
1148
1149 // Iterate though the objects in a decoded SOSMessage.
1150 bool SOSMessageWithObjects(SOSMessageRef message, CFErrorRef *error,
1151                            void(^withObject)(CFDataRef object, bool *stop)) {
1152     if (message->objects) {
1153         CFDataRef object;
1154         CFArrayForEachC(message->objects, object) {
1155             bool stop = false;
1156             withObject(object, &stop);
1157             if (stop)
1158                 break;
1159         }
1160         return true;
1161     }
1162     if (!message->objectsDer)
1163         return true;
1164     const uint8_t *der = CFDataGetBytePtr(message->der);
1165     const uint8_t *der_end = der + CFDataGetLength(message->der);
1166     return der_foreach_objects(message->objectsLen, message->objectsDer, der_end, error, withObject);
1167 }
1168
1169 bool SOSMessageWithSOSObjects(SOSMessageRef message, SOSDataSourceRef dataSource, CFErrorRef *error,
1170                            void(^withObject)(SOSObjectRef object, bool *stop)) {
1171     return SOSMessageWithObjects(message, error, ^(CFDataRef object, bool *stop) {
1172         CFDictionaryRef plist = NULL;
1173         const uint8_t *der = CFDataGetBytePtr(object);
1174         const uint8_t *der_end = der + CFDataGetLength(object);
1175         // TODO Remove intermediate plist format
1176         der = der_decode_dictionary(kCFAllocatorDefault, kCFPropertyListImmutable, &plist, error, der, der_end);
1177         if (der) {
1178             SOSObjectRef peersObject = SOSObjectCreateWithPropertyList(dataSource, plist, error);
1179             withObject(peersObject, stop);
1180             CFReleaseSafe(peersObject);
1181         }
1182         CFReleaseSafe(plist);
1183     });
1184 }