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     if (ds) {
 322         __block size_t maxEntries = 16;
 323         CFStringAppendFormat(objects, NULL, CFSTR("{[%zu]"), SOSMessageCountObjects(message));
 324         SOSMessageWithSOSObjects(message, ds, NULL, ^(SOSObjectRef object, bool *stop) {
 325             CFDataRef digest = SOSObjectCopyDigest(ds, object, NULL);
 326             const uint8_t *O = CFDataGetBytePtr(digest);
 327             CFStringAppendFormat(objects, NULL, CFSTR(" %02X%02X%02X%02X"), O[0],O[1],O[2],O[3]);
 328             CFReleaseSafe(digest);
 329             if (!--maxEntries) {
 330                 CFStringAppend(objects, CFSTR("..."));
 331                 *stop = true;
 332             }
 333         });
 334         CFStringAppend(objects, CFSTR("}"));
 335     } else {
 336         CFStringAppend(objects, CFSTR("{NO DATASOURCE}"));
 337     }
 338
 339     CFStringRef desc = NULL;
 340     if (message->version == 0) {
 341         switch (SOSMessageInferType(message, NULL)) {
 342             case SOSManifestInvalidMessageType:
 343                 desc = CFStringCreateWithFormat(CFGetAllocator(message), NULL, CFSTR("<MSGInvalid %"PRIu64" >"), message->sequenceNumber);
 344                 break;
 345             case SOSManifestDigestMessageType:
 346                 desc = CFStringCreateWithFormat(CFGetAllocator(message), NULL, CFSTR("<MSGDigest %"PRIu64" %02X%02X%02X%02X>"), message->sequenceNumber, S[0],S[1],S[2],S[3]);
 347                 break;
 348             case SOSManifestMessageType:
 349                 desc = CFStringCreateWithFormat(CFGetAllocator(message), NULL, CFSTR("<MSGManifest %"PRIu64" %@>"), message->sequenceNumber, message->additions);
 350                 break;
 351             case SOSManifestDeltaAndObjectsMessageType:
 352                 desc = CFStringCreateWithFormat(CFGetAllocator(message), NULL, CFSTR("<MSGObjects %"PRIu64" %02X%02X%02X%02X %@ %@ %@"),
 353                                                 message->sequenceNumber,
 354                                                 B[0],B[1],B[2],B[3],
 355                                                 message->removals, message->additions,
 356                                                 objects);
 357                 break;
 358         }
 359     } else {
 360         desc = CFStringCreateWithFormat
 361         (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>"),
 362         message->sequenceNumber,
 363         creationDate,
 364         S[0],S[1],S[2],S[3],
 365         B[0],B[1],B[2],B[3],
 366         P[0],P[1],P[2],P[3],
 367         message->removals, message->additions,
 368         objects,
 369         (message->flags & kSOSMessageGetObjects) ? "G" : "g",
 370         (message->flags & kSOSMessageJoinRequest) ? "J" : "j",
 371         (message->flags & kSOSMessagePartial) ? "P" : "p",
 372         (message->flags & kSOSMessageDigestTypesProposed) ? "D" : "d",
 373         (message->flags & kSOSMessageClearGetObjects) ? "K" : "k",
 374         (message->flags & kSOSMessageDidClearGetObjectsSinceLastDelta) ? "Z" : "z",
 375         (message->flags & kSOSMessageSkipHello) ? "H" : "h");
 376     }
 377     CFReleaseSafe(creationDate);
 378     CFReleaseSafe(objects);
 379     return desc;
 380 }
 381
 382 //
 383 // MARK: SOSMessage encoding
 384 //
 385
 386 // Create an SOSMessage ready to be encoded.
 387 SOSMessageRef SOSMessageCreate(CFAllocatorRef allocator, uint64_t version, CFErrorRef *error) {
 388     SOSMessageRef message = CFTypeAllocate(SOSMessage, struct __OpaqueSOSMessage, allocator);
 389     message->version = version;
 390     return message;
 391 }
 392
 393 // TODO: Remove me this is for testing only, tests should use the real thing.
 394 SOSMessageRef SOSMessageCreateWithManifests(CFAllocatorRef allocator, SOSManifestRef sender,
 395                                             SOSManifestRef base, SOSManifestRef proposed,
 396                                             bool includeManifestDeltas, CFErrorRef *error) {
 397     SOSMessageRef message = SOSMessageCreate(allocator, kEngineMessageProtocolVersion, error);
 398     if (!SOSMessageSetManifests(message, sender, base, proposed, includeManifestDeltas, NULL, error))
 399         CFReleaseNull(message);
 400     return message;
 401 }
 402
 403 bool SOSMessageSetManifests(SOSMessageRef message, SOSManifestRef sender,
 404                             SOSManifestRef base, SOSManifestRef proposed,
 405                             bool includeManifestDeltas, SOSManifestRef objectsSent,
 406                             CFErrorRef *error) {
 407     if (!message) return true;
 408     bool ok = true;
 409     // TODO: Check at v2 encoding time
 410     // if (!sender) return (SOSMessageRef)SOSErrorCreate(kSOSErrorProcessingFailure, error, NULL, CFSTR("no sender manifest specified for SOSMessage"));
 411     message->baseDigest = CFRetainSafe(SOSManifestGetDigest(base, NULL));
 412     message->proposedDigest = CFRetainSafe(SOSManifestGetDigest(proposed, NULL));
 413     message->senderDigest = CFRetainSafe(SOSManifestGetDigest(sender, NULL));
 414     if (includeManifestDeltas) {
 415         SOSManifestRef additions = NULL;
 416         ok = SOSManifestDiff(base, proposed, &message->removals, &additions, error);
 417         if (message->version == 0) {
 418             message->additions = additions;
 419         } else {
 420             message->additions = SOSManifestCreateComplement(objectsSent, additions, error);
 421             CFReleaseSafe(additions);
 422         }
 423     }
 424     return ok;
 425 }
 426
 427 void SOSMessageSetFlags(SOSMessageRef message, SOSMessageFlags flags) {
 428     message->flags = flags;
 429 }
 430
 431 // Add an extension to this message
 432 void SOSMessageAddExtension(SOSMessageRef message, CFDataRef oid, bool isCritical, CFDataRef extension) {
 433     // TODO: Implement
 434     secerror("not implemented yet!");
 435 }
 436
 437 static bool SecMessageIsObjectValid(CFDataRef object, CFErrorRef *error) {
 438     const uint8_t *der = CFDataGetBytePtr(object);
 439     const uint8_t *der_end = der + CFDataGetLength(object);
 440     ccder_tag tag = 0;
 441     size_t len = 0;
 442     der = ccder_decode_tag(&tag, der, der_end);
 443     if (!der )
 444         return SOSErrorCreate(kSOSErrorBadFormat, error, NULL, CFSTR("Invalid DER, no tag found"));
 445     if (tag == CCDER_EOL)
 446         return SOSErrorCreate(kSOSErrorBadFormat, error, NULL, CFSTR("Object has EOL tag"));
 447     der = ccder_decode_len(&len, der, der_end);
 448     if (!der)
 449         return SOSErrorCreate(kSOSErrorBadFormat, error, NULL, CFSTR("Object with tag %lu has no valid DER length"), tag);
 450     der += len;
 451      if (der_end - der)
 452         return SOSErrorCreate(kSOSErrorBadFormat, error, NULL, CFSTR("Object has %td trailing unused bytes"), der_end - der);
 453     return true;
 454 }
 455
 456 bool SOSMessageAppendObject(SOSMessageRef message, CFDataRef object, CFErrorRef *error) {
 457     if (!SecMessageIsObjectValid(object, error)) return false;
 458     if (!message->objects)
 459         message->objects = CFArrayCreateMutableForCFTypes(CFGetAllocator(message));
 460     if (message->objects)
 461         CFArrayAppendValue(message->objects, object);
 462     return true;
 463 }
 464
 465 static CC_NONNULL_ALL
 466 size_t ccder_sizeof_bit_string(cc_size n, const cc_unit *s) {
 467     return ccder_sizeof(CCDER_BIT_STRING, ccn_sizeof(ccn_bitlen(n, s)) + 1);
 468 }
 469
 470 static CC_NONNULL_ALL
 471 uint8_t *ccder_encode_bit_string(cc_size n, const cc_unit *s, const uint8_t *der, uint8_t *der_end) {
 472     size_t bits = ccn_bitlen(n, s);
 473     size_t out_size = ccn_sizeof(bits) + 1;
 474     der_end = ccder_encode_body_nocopy(out_size, der, der_end);
 475     if (der_end)
 476         ccn_write_uint_padded(n, s, out_size, der_end);
 477     return ccder_encode_tl(CCDER_BIT_STRING, out_size, der, der_end);
 478 }
 479
 480
 481 static
 482 size_t der_sizeof_implicit_data(ccder_tag tag, CFDataRef data) {
 483     if (!data)
 484         return 0;
 485     return ccder_sizeof_implicit_raw_octet_string(tag, CFDataGetLength(data));
 486 }
 487
 488
 489 static CC_NONNULL((3, 4))
 490 uint8_t *der_encode_implicit_data(ccder_tag tag, CFDataRef data, const uint8_t *der, uint8_t *der_end) {
 491     if (!data)
 492         return der_end;
 493     return ccder_encode_implicit_raw_octet_string(tag, CFDataGetLength(data), CFDataGetBytePtr(data), der, der_end);
 494 }
 495
 496 static size_t der_sizeof_message_header(SOSMessageRef message, CFErrorRef *error) {
 497     if (!message->senderDigest) {
 498         // TODO: Create Error.
 499         return 0;
 500     }
 501     cc_unit flags[1];
 502     flags[0] = (cc_unit)message->flags; // TODO Fix cast or something
 503
 504     return ccder_sizeof(CCDER_CONSTRUCTED_SEQUENCE,
 505         der_sizeof_generalizedtime(message->creationTime, error) +
 506         ccder_sizeof_uint64(message->sequenceNumber) +
 507         ccder_sizeof_bit_string(array_size(flags), flags) +
 508         der_sizeof_implicit_data(CCDER_OCTET_STRING, message->senderDigest) +
 509         der_sizeof_implicit_data(0 | CCDER_CONTEXT_SPECIFIC, message->baseDigest) +
 510         der_sizeof_implicit_data(1 | CCDER_CONTEXT_SPECIFIC, message->proposedDigest));
 511 }
 512
 513 static uint8_t *der_encode_message_header(SOSMessageRef message, CFErrorRef *error, const uint8_t *der, uint8_t *der_end) {
 514     if (!message->senderDigest) {
 515         // TODO: Create Error.
 516         return NULL;
 517     }
 518     cc_unit flags[1];
 519     flags[0] = (cc_unit)message->flags; // TODO Fix cast or something
 520     return ccder_encode_constructed_tl(CCDER_CONSTRUCTED_SEQUENCE, der_end, der,
 521         der_encode_generalizedtime(message->creationTime, error, der,
 522         ccder_encode_uint64(message->sequenceNumber, der,
 523         ccder_encode_bit_string(array_size(flags), flags, der,
 524         der_encode_implicit_data(CCDER_OCTET_STRING, message->senderDigest, der,
 525         der_encode_implicit_data(0 | CCDER_CONTEXT_SPECIFIC, message->baseDigest, der,
 526         der_encode_implicit_data(1 | CCDER_CONTEXT_SPECIFIC, message->proposedDigest, der, der_end)))))));
 527 }
 528
 529 static size_t der_sizeof_deltas(SOSMessageRef message) {
 530     if (!message->additions && !message->removals) return 0;
 531     if (message->version == 0) {
 532         return ccder_sizeof(CCDER_OCTET_STRING, SOSManifestGetSize(message->removals))+
 533                ccder_sizeof(CCDER_OCTET_STRING, SOSManifestGetSize(message->additions));
 534     } else {
 535         return ccder_sizeof(0 | CCDER_CONTEXT_SPECIFIC | CCDER_CONSTRUCTED,
 536                             ccder_sizeof(CCDER_OCTET_STRING, SOSManifestGetSize(message->removals))+
 537                             ccder_sizeof(CCDER_OCTET_STRING, SOSManifestGetSize(message->additions)));
 538     }
 539 }
 540
 541 static uint8_t *der_encode_deltas(SOSMessageRef message, CFErrorRef *error, const uint8_t *der, uint8_t *der_end) {
 542     if (!message->additions && !message->removals) return der_end;
 543     if (message->version == 0) {
 544         return 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     } else {
 547         return ccder_encode_constructed_tl(0 | CCDER_CONTEXT_SPECIFIC | CCDER_CONSTRUCTED, der_end, der,
 548             der_encode_implicit_data(CCDER_OCTET_STRING, SOSManifestGetData(message->removals), der,
 549             der_encode_implicit_data(CCDER_OCTET_STRING, SOSManifestGetData(message->additions), der, der_end)));
 550     }
 551 }
 552
 553 static size_t der_sizeof_extensions(SOSMessageRef message) {
 554     // We don't support any yet.
 555     return 0;
 556 }
 557
 558 static uint8_t *der_encode_extensions(SOSMessageRef message, CFErrorRef *error, const uint8_t *der, uint8_t *der_end) {
 559     // We don't support any yet.
 560     return der_end;
 561 }
 562
 563 static size_t der_sizeof_objects(SOSMessageRef message) {
 564     size_t len = 0;
 565     if (message->objects) {
 566         CFDataRef data;
 567         CFArrayForEachC(message->objects, data) {
 568             len += (size_t)CFDataGetLength(data);
 569         }
 570     } else if (message->version != 0)
 571         return 0;
 572
 573     if (message->indefiniteLength)
 574         return len + 4;
 575     else
 576         return ccder_sizeof(2 | CCDER_CONTEXT_SPECIFIC | CCDER_CONSTRUCTED, len);
 577 }
 578
 579 static uint8_t *der_encode_objects(SOSMessageRef message, CFErrorRef *error, const uint8_t *der, uint8_t *der_end) {
 580     if (!message->objects && message->version != 0) return der_end;
 581     const uint8_t *original_der_end = der_end;
 582     if (message->indefiniteLength)
 583         der_end = ccder_encode_tl(CCDER_EOL, 0, der, der_end);
 584
 585     for (CFIndex position = (message->objects ? CFArrayGetCount(message->objects) : 0) - 1; position >= 0; --position) {
 586         CFDataRef object = CFArrayGetValueAtIndex(message->objects, position);
 587         der_end = ccder_encode_body(CFDataGetLength(object), CFDataGetBytePtr(object), der, der_end);
 588     }
 589     if (message->indefiniteLength) {
 590         return ccder_encode_tag(2 | CCDER_CONTEXT_SPECIFIC | CCDER_CONSTRUCTED, der,
 591                ccder_encode_len(0, der, der_end));
 592     } else {
 593         ccder_tag otag = message->version == 0 ? CCDER_CONSTRUCTED_SEQUENCE : 2 | CCDER_CONTEXT_SPECIFIC | CCDER_CONSTRUCTED;
 594         return ccder_encode_constructed_tl(otag, original_der_end, der, der_end);
 595     }
 596 }
 597
 598 static size_t der_sizeof_v2_message(SOSMessageRef message, CFErrorRef *error) {
 599     size_t body_size = (der_sizeof_message_header(message, error) +
 600                         der_sizeof_deltas(message) +
 601                         der_sizeof_extensions(message) +
 602                         der_sizeof_objects(message));
 603     if (message->indefiniteLength)
 604         return body_size + 4;
 605     else
 606         return ccder_sizeof(CCDER_CONSTRUCTED_SEQUENCE, body_size);
 607 }
 608
 609
 610 static uint8_t *der_encode_v2_message(SOSMessageRef message, CFErrorRef *error, const uint8_t *der, uint8_t *der_end) {
 611     const uint8_t *original_der_end = der_end;
 612     if (message->indefiniteLength)
 613         der_end = ccder_encode_tl(CCDER_EOL, 0, der, der_end);
 614
 615     der_end = der_encode_message_header(message, error, der,
 616         der_encode_deltas(message, error, der,
 617         der_encode_extensions(message, error, der,
 618         der_encode_objects(message, error, der, der_end))));
 619
 620     if (message->indefiniteLength) {
 621         return ccder_encode_tag(CCDER_CONSTRUCTED_SEQUENCE, der,
 622                ccder_encode_len(0, der, der_end));
 623     } else {
 624         return ccder_encode_constructed_tl(CCDER_CONSTRUCTED_SEQUENCE, original_der_end, der, der_end);
 625     }
 626 }
 627
 628 //------------------------------------------------------------------------------------------------------------------------------------
 629 //      V1 support
 630 //------------------------------------------------------------------------------------------------------------------------------------
 631
 632 /* ManifestDigest message */
 633 static size_t der_sizeof_manifest_digest_message(SOSMessageRef message, CFErrorRef *error) {
 634     if (!message->senderDigest || CFDataGetLength(message->senderDigest) != SOSDigestSize) {
 635         SOSErrorCreate(kSOSErrorProcessingFailure, error, NULL, CFSTR("digest length mismatch"));
 636         return 0;
 637     }
 638     return ccder_sizeof(CCDER_CONSTRUCTED_SEQUENCE,
 639                         (ccder_sizeof_uint64(SOSManifestDigestMessageType) +
 640                          ccder_sizeof_raw_octet_string(SOSDigestSize)));
 641 }
 642
 643 static uint8_t *der_encode_manifest_digest_message(SOSMessageRef message, CFErrorRef *error, const uint8_t *der, uint8_t *der_end) {
 644     return ccder_encode_constructed_tl(CCDER_CONSTRUCTED_SEQUENCE, der_end, der,
 645            ccder_encode_uint64(SOSManifestDigestMessageType, der,
 646            ccder_encode_raw_octet_string(SOSDigestSize, CFDataGetBytePtr(message->senderDigest), der, der_end)));
 647 }
 648
 649 /* Manifest message */
 650 static size_t der_sizeof_manifest_message(SOSMessageRef message, CFErrorRef *error) {
 651     if (!message->additions) {
 652         SOSErrorCreate(kSOSErrorProcessingFailure, error, NULL, CFSTR("no manifest for manifest message"));
 653         return 0;
 654     }
 655     return ccder_sizeof(CCDER_CONSTRUCTED_SEQUENCE,
 656         (ccder_sizeof_uint64(SOSManifestMessageType) +
 657          der_sizeof_implicit_data(CCDER_OCTET_STRING, SOSManifestGetData(message->additions))));
 658 }
 659
 660 static uint8_t *der_encode_manifest_message(SOSMessageRef message, CFErrorRef *error, const uint8_t *der, uint8_t *der_end) {
 661     return ccder_encode_constructed_tl(CCDER_CONSTRUCTED_SEQUENCE, der_end, der,
 662                ccder_encode_uint64(SOSManifestMessageType, der,
 663                der_encode_implicit_data(CCDER_OCTET_STRING, SOSManifestGetData(message->additions), der, der_end)));
 664 }
 665
 666 /* ManifestDeltaAndObjects message */
 667 static size_t der_sizeof_manifest_and_objects_message(SOSMessageRef message, CFErrorRef *error) {
 668     if (!message->baseDigest || CFDataGetLength(message->baseDigest) != SOSDigestSize) {
 669         SOSErrorCreate(kSOSErrorProcessingFailure, error, NULL, CFSTR("digest length mismatch"));
 670         return 0;
 671     }
 672
 673     return ccder_sizeof(CCDER_CONSTRUCTED_SEQUENCE,
 674         (ccder_sizeof_uint64(SOSManifestDeltaAndObjectsMessageType) +
 675          ccder_sizeof(CCDER_CONSTRUCTED_SEQUENCE,
 676              (ccder_sizeof_raw_octet_string(SOSDigestSize) +
 677               der_sizeof_implicit_data(CCDER_OCTET_STRING, SOSManifestGetData(message->removals)) +
 678               der_sizeof_implicit_data(CCDER_OCTET_STRING, SOSManifestGetData(message->additions)) +
 679               der_sizeof_objects(message)))));
 680 }
 681
 682 static uint8_t *der_encode_manifest_and_objects_message(SOSMessageRef message, CFErrorRef *error, const uint8_t *der, uint8_t *der_end) {
 683     return ccder_encode_constructed_tl(CCDER_CONSTRUCTED_SEQUENCE, der_end, der,
 684                ccder_encode_uint64(SOSManifestDeltaAndObjectsMessageType, der,
 685                ccder_encode_constructed_tl(CCDER_CONSTRUCTED_SEQUENCE, der_end, der,
 686                    ccder_encode_raw_octet_string(SOSDigestSize, CFDataGetBytePtr(message->baseDigest), der,
 687                    der_encode_implicit_data(CCDER_OCTET_STRING, SOSManifestGetData(message->removals), der,
 688                    der_encode_implicit_data(CCDER_OCTET_STRING, SOSManifestGetData(message->additions), der,
 689                    der_encode_objects(message, error, der, der_end)))))));
 690 }
 691
 692 static uint64_t SOSMessageInferType(SOSMessageRef message, CFErrorRef *error) {
 693     if (message->baseDigest) {
 694         // TODO: Assert that we don't have senderDigest or proposedDigest
 695         if (SOSManifestGetCount(message->removals) || SOSManifestGetCount(message->additions) || SOSMessageCountObjects(message)) {
 696             return SOSManifestDeltaAndObjectsMessageType;
 697         } else {
 698             // NOTE: If we force a SOSManifestDeltaAndObjectsMessageType instead then
 699             // true v0 peers will overwrite their last objects message to us.  However this
 700             // implements the current v0 behaviour
 701             return SOSManifestDigestMessageType;
 702         }
 703     } else if (message->additions) {
 704         // TODO: Assert that we don't have senderDigest, proposedDigest, additions, removals or objects
 705         return SOSManifestMessageType;
 706     } else if (message->senderDigest) {
 707         // TODO: Assert that we don't have proposedDigest, removals or objects
 708         return SOSManifestDigestMessageType;
 709     }
 710     // TODO: Create error.
 711     return SOSManifestInvalidMessageType;
 712 }
 713
 714 static size_t der_sizeof_message(SOSMessageRef message, uint64_t messageType, CFErrorRef *error) {
 715     switch (messageType) {
 716         case SOSManifestInvalidMessageType:
 717             return der_sizeof_v2_message(message, error);
 718         case SOSManifestDigestMessageType:
 719             return der_sizeof_manifest_digest_message(message, error);
 720         case SOSManifestMessageType:
 721             return der_sizeof_manifest_message(message, error);
 722         case SOSManifestDeltaAndObjectsMessageType:
 723             return der_sizeof_manifest_and_objects_message(message, error);
 724     }
 725     return 0;
 726 }
 727
 728 static uint8_t *der_encode_message(SOSMessageRef message, uint64_t messageType, CFErrorRef *error, const uint8_t *der, uint8_t *der_end) {
 729     switch (messageType) {
 730         case SOSManifestInvalidMessageType:
 731             return der_encode_v2_message(message, error, der, der_end);
 732         case SOSManifestDigestMessageType:
 733             return der_encode_manifest_digest_message(message, error, der, der_end);
 734         case SOSManifestMessageType:
 735             return der_encode_manifest_message(message, error, der, der_end);
 736         case SOSManifestDeltaAndObjectsMessageType:
 737             return der_encode_manifest_and_objects_message(message, error, der, der_end);
 738     }
 739     return der_end;
 740 }
 741
 742 // Encode an SOSMessage, calls addObject callback and appends returned objects
 743 // one by one, until addObject returns NULL.
 744 CFDataRef SOSMessageCreateData(SOSMessageRef message, uint64_t sequenceNumber, CFErrorRef *error) {
 745     // Version 2 message have sequence numbers, version 0 messages do not.
 746     uint64_t messageType = SOSManifestInvalidMessageType;
 747     message->sequenceNumber = sequenceNumber;
 748     if (message->version == 0) {
 749         message->indefiniteLength = false;
 750         messageType = SOSMessageInferType(message, error);
 751         if (!messageType) {
 752             // Propagate error
 753             return NULL;
 754         }
 755     } else {
 756         message->creationTime = floor(CFAbsoluteTimeGetCurrent());
 757     }
 758     size_t der_size = der_sizeof_message(message, messageType, error);
 759     CFMutableDataRef data = CFDataCreateMutable(NULL, der_size);
 760     if (data == NULL) {
 761         // TODO Error.
 762         return NULL;
 763     }
 764     CFDataSetLength(data, der_size);
 765     uint8_t *der_end = CFDataGetMutableBytePtr(data);
 766     const uint8_t *der = der_end;
 767     der_end += der_size;
 768
 769     der_end = der_encode_message(message, messageType, error, der, der_end);
 770     if (der != der_end) {
 771         secwarning("internal error %td bytes unused in der buffer", der_end - der);
 772     }
 773     return data;
 774 }
 775
 776 //
 777 // MARK: SOSMessage decoding
 778 //
 779
 780 #define CCBER_LEN_INDEFINITE ((size_t)-1)
 781
 782 // Decode BER length field.  Sets *lenp to ccber_indefinite_len if this is an indefinite length encoded object.
 783 // Behaves like ccder_decode_len in every other way.
 784 static CC_NONNULL((1, 3))
 785 const uint8_t *ccber_decode_len(size_t *lenp, const uint8_t *der, const uint8_t *der_end) {
 786     if (der && der < der_end) {
 787         if (*der == 0x80) {
 788             der++;
 789             *lenp = CCBER_LEN_INDEFINITE;
 790         }
 791         else
 792             der = ccder_decode_len(lenp, der, der_end);
 793     }
 794     return der;
 795 }
 796
 797 static const uint8_t *der_decode_generalizedtime(CFAbsoluteTime *at, CFErrorRef *error, const uint8_t *der, const uint8_t *der_end) {
 798     const uint8_t *times_end = NULL;
 799     der = ccder_decode_constructed_tl(CCDER_GENERALIZED_TIME, &times_end, der, der_end);
 800     der = der_decode_generalizedtime_body(at, error, der, times_end);
 801     if (times_end != der) {
 802         secwarning("internal error %td bytes unused in generalizedtime DER buffer", times_end - der);
 803     }
 804     return der;
 805 }
 806
 807 static const uint8_t *der_decode_optional_generalizedtime(CFAbsoluteTime *at, CFErrorRef *error, const uint8_t *der, const uint8_t *der_end) {
 808     const uint8_t *times_end = der_decode_generalizedtime(at, error, der, der_end);
 809     return times_end ? times_end : der;
 810 }
 811
 812 static CC_NONNULL((2, 4))
 813 const uint8_t *ccder_decode_implicit_uint64(ccder_tag expected_tag, uint64_t* r, const uint8_t *der, const uint8_t *der_end) {
 814     size_t len;
 815     der = ccder_decode_tl(expected_tag, &len, der, der_end);
 816     if (der && len && (*der & 0x80) != 0x80) {
 817         if (ccn_read_uint(ccn_nof_size(sizeof(*r)), (cc_unit*)r, len, der) >= 0)
 818             return der + len;
 819     }
 820     return NULL;
 821 }
 822
 823 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) {
 824     const uint8_t *ui64_end = ccder_decode_implicit_uint64(expected_tag, value, der, der_end);
 825     return ui64_end ? ui64_end : der;
 826 }
 827
 828
 829 static const uint8_t *ccder_decode_optional_uint64(uint64_t *value, const uint8_t *der, const uint8_t *der_end) {
 830     const uint8_t *ui64_end = ccder_decode_uint64(value, der, der_end);
 831     return ui64_end ? ui64_end : der;
 832 }
 833
 834 static const uint8_t *ccder_decode_digest_types(SOSMessageRef message, const uint8_t *der, const uint8_t *der_end) {
 835     const uint8_t *dt_end;
 836     der = ccder_decode_sequence_tl(&dt_end, der, der_end);
 837     if (!der) return NULL;
 838     // Skip over digestType body for now.
 839     // TODO: Support DigestType
 840     return dt_end;
 841 }
 842
 843 static const uint8_t *ccder_decode_optional_digest_types(SOSMessageRef message, const uint8_t *der, const uint8_t *der_end) {
 844     const uint8_t *dt_end = ccder_decode_digest_types(message, der, der_end);
 845     return dt_end ? dt_end : der;
 846 }
 847
 848 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) {
 849     size_t len;
 850     const uint8_t *body = ccder_decode_tl(CCDER_BIT_STRING, &len, der, der_end);
 851     if (!body || len < 1)
 852         return NULL;
 853
 854     if (r_bitlen) *r_bitlen = (len - 1) * 8 - (body[0] & 7);
 855     ccn_read_uint(1, r, len - 1, body + 1);
 856     return body + len;
 857 }
 858
 859 static const uint8_t *der_decode_implicit_data(ccder_tag expected_tag, CFDataRef *data, const uint8_t *der, const uint8_t *der_end) {
 860     size_t len = 0;
 861     der = ccder_decode_tl(expected_tag, &len, der, der_end);
 862     if (der && data) {
 863         *data = CFDataCreateWithBytesNoCopy(kCFAllocatorDefault, der, len, kCFAllocatorNull);
 864         if (*data)
 865             der += len;
 866         else
 867             der = NULL;
 868     }
 869     return der;
 870 }
 871
 872 static const uint8_t *der_decode_optional_implicit_data(ccder_tag expected_tag, CFDataRef *data, const uint8_t *der, const uint8_t *der_end) {
 873     const uint8_t *data_end = der_decode_implicit_data(expected_tag, data, der, der_end);
 874     return data_end ? data_end : der;
 875 }
 876
 877 static const uint8_t *der_decode_deltas_body(SOSMessageRef message, CFErrorRef *error, const uint8_t *der, const uint8_t *der_end) {
 878     CFDataRef removals = NULL, additions = NULL;
 879     der = der_decode_implicit_data(CCDER_OCTET_STRING, &removals, der, der_end);
 880     der = der_decode_implicit_data(CCDER_OCTET_STRING, &additions, der, der_end);
 881     if (der) {
 882         message->removals = SOSManifestCreateWithData(removals, error);
 883         message->additions = SOSManifestCreateWithData(additions, error);
 884         if (!message->removals || !message->additions) {
 885             CFReleaseNull(message->removals);
 886             CFReleaseNull(message->additions);
 887             der = NULL;
 888         }
 889     }
 890     CFReleaseSafe(removals);
 891     CFReleaseSafe(additions);
 892
 893     return der;
 894 }
 895
 896 static const uint8_t *der_decode_deltas(SOSMessageRef message, CFErrorRef *error, const uint8_t *der, const uint8_t *der_end) {
 897     const uint8_t *deltas_end = NULL;
 898     der = ccder_decode_constructed_tl(0 | CCDER_CONTEXT_SPECIFIC | CCDER_CONSTRUCTED, &deltas_end, der, der_end);
 899     return der_decode_deltas_body(message, error, der, deltas_end);
 900 }
 901
 902 static const uint8_t *der_decode_optional_deltas(SOSMessageRef message, const uint8_t *der, const uint8_t *der_end) {
 903     const uint8_t *seq_end = der_decode_deltas(message, NULL, der, der_end);
 904     return seq_end ? seq_end : der;
 905 }
 906
 907 static const uint8_t *der_decode_extensions(SOSMessageRef message, CFErrorRef *error, const uint8_t *der, const uint8_t *der_end) {
 908     const uint8_t *extensions_end;
 909     der = ccder_decode_constructed_tl(1 | CCDER_CONTEXT_SPECIFIC | CCDER_CONSTRUCTED, &extensions_end, der, der_end);
 910     if (!der) return NULL;
 911     // Skip over extensions for now.
 912     return extensions_end;
 913 }
 914
 915 static const uint8_t *der_decode_optional_extensions(SOSMessageRef message, CFErrorRef *error, const uint8_t *der, const uint8_t *der_end) {
 916     const uint8_t *extensions_end = der_decode_extensions(message, NULL, der, der_end);
 917     return extensions_end ? extensions_end : der;
 918 }
 919
 920 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)) {
 921     bool stop = false;
 922     ccder_tag tag;
 923     // Look ahead at the tag
 924     while (!stop && ccder_decode_tag(&tag, der, der_end) && tag != CCDER_EOL) {
 925         const uint8_t *object_end = NULL;
 926         if (!ccder_decode_constructed_tl(tag, &object_end, der, der_end)) {
 927             SOSErrorCreate(kSOSErrorDecodeFailure, error, NULL, CFSTR("failed to decode object header"));
 928             return NULL;
 929         }
 930         if (withObject) {
 931             CFDataRef object = CFDataCreateWithBytesNoCopy(kCFAllocatorDefault, der, object_end - der, kCFAllocatorNull);
 932             withObject(object, &stop);
 933             CFReleaseSafe(object);
 934         }
 935         der = object_end;
 936     }
 937     if (length == CCBER_LEN_INDEFINITE) {
 938         size_t len = 0;
 939         der = ccder_decode_tl(CCDER_EOL, &len, der, der_end);
 940         if (len != 0) {
 941             secwarning("%td length ", der_end - der);
 942         }
 943     }
 944     if (!stop && der != der_end)
 945         secwarning("%td trailing bytes after objects DER", der_end - der);
 946
 947     return der;
 948 }
 949
 950 static const uint8_t *der_decode_objects(SOSMessageRef message, CFErrorRef *error, const uint8_t *der, const uint8_t *der_end) {
 951     ccder_tag tag = 0;
 952     size_t objects_len = 0;
 953     der = ccder_decode_tag(&tag, der, der_end);
 954     if (tag != (2 | CCDER_CONTEXT_SPECIFIC | CCDER_CONSTRUCTED)) return NULL;
 955     der = ccber_decode_len(&objects_len, der, der_end);
 956     if (objects_len != CCBER_LEN_INDEFINITE && der_end - der != (ptrdiff_t)objects_len) {
 957         secwarning("%td trailing bytes after SOSMessage DER", (der_end - der) - (ptrdiff_t)objects_len);
 958     }
 959     // Remember a pointer into message->der where objects starts.
 960     message->objectsDer = der;
 961     message->objectsLen = objects_len;
 962
 963     return der + objects_len;
 964 }
 965
 966 static const uint8_t *der_decode_optional_objects(SOSMessageRef message, CFErrorRef *error, const uint8_t *der, const uint8_t *der_end) {
 967     const uint8_t *seq_end = der_decode_objects(message, NULL, der, der_end);
 968     return seq_end ? seq_end : der;
 969 }
 970
 971 #if 0
 972 // Move to ccder and possibly refactor ccder_decode_constructed_tl to call this.
 973 #ifdef CCDER_DECODE_CONSTRUCTED_LEN_SPECIFIER
 974 CCDER_DECODE_CONSTRUCTED_LEN_SPECIFIER
 975 #endif
 976 inline CC_NONNULL((1, 3))
 977 const uint8_t *
 978 ccder_decode_constructed_len(const uint8_t **body_end,
 979                              const uint8_t *der, const uint8_t *der_end) {
 980     size_t len;
 981     der = ccder_decode_len(&len, der, der_end);
 982     *body_end = der + len;
 983     return der;
 984 }
 985 #endif
 986
 987 static const uint8_t *der_decode_message_header(SOSMessageRef message, CFErrorRef *error, const uint8_t *der, const uint8_t *der_end) {
 988     cc_unit flags[1] = {};
 989     der = ccder_decode_constructed_tl(CCDER_CONSTRUCTED_SEQUENCE, &der_end, der, der_end);
 990     message->version = 2;
 991     der = ccder_decode_optional_implicit_uint64(0 | CCDER_CONTEXT_SPECIFIC, &message->version, der, der_end);
 992     der = der_decode_optional_generalizedtime(&message->creationTime, error, der, der_end);
 993     der = ccder_decode_optional_uint64(&message->sequenceNumber, der, der_end);
 994     der = ccder_decode_optional_digest_types(message, der, der_end);
 995     der = ccder_decode_bit_string(array_size(flags), NULL, flags, der, der_end);
 996     message->flags = flags[0];
 997
 998     der = der_decode_implicit_data(CCDER_OCTET_STRING, &message->senderDigest, der, der_end);
 999     der = der_decode_optional_implicit_data(0 | CCDER_CONTEXT_SPECIFIC, &message->baseDigest, der, der_end);
1000     der = der_decode_optional_implicit_data(1 | CCDER_CONTEXT_SPECIFIC, &message->proposedDigest, der, der_end);
1001     return der;
1002 }
1003
1004 static const uint8_t *
1005 der_decode_manifest_and_objects_message(SOSMessageRef message,
1006                                         CFErrorRef *error, const uint8_t *der,
1007                                         const uint8_t *der_end) {
1008     size_t objects_len = 0;
1009     const uint8_t *body_end;
1010     der = ccder_decode_sequence_tl(&body_end, der, der_end);
1011     if (body_end != der_end) {
1012         SOSErrorCreate(kSOSErrorInvalidMessage, error, NULL, CFSTR("Trailing garbage at end of message"));
1013         return NULL;
1014     }
1015     der = der_decode_implicit_data(CCDER_OCTET_STRING, &message->baseDigest, der, body_end);
1016     der = der_decode_deltas_body(message, error, der, body_end);
1017     // Remember a pointer into message->der where objects starts.
1018     der = message->objectsDer = ccder_decode_tl(CCDER_CONSTRUCTED_SEQUENCE, &objects_len, der, body_end);
1019     message->objectsLen = objects_len;
1020
1021     return der ? der + objects_len : NULL;
1022 }
1023
1024 static const uint8_t *der_decode_v0_message_body(SOSMessageRef message, CFErrorRef *error, const uint8_t *der, const uint8_t *der_end) {
1025     uint64_t messageType = 0;
1026     der = ccder_decode_uint64(&messageType, der, der_end);
1027     if (der) switch (messageType) {
1028         case SOSManifestDigestMessageType:
1029         {
1030             der = der_decode_implicit_data(CCDER_OCTET_STRING, &message->senderDigest, der, der_end);
1031             break;
1032         }
1033         case SOSManifestMessageType:
1034         {
1035             CFDataRef manifestBody = NULL;
1036             der = der_decode_implicit_data(CCDER_OCTET_STRING, &manifestBody, der, der_end);
1037             if (!der) return NULL;
1038             if (der != der_end) {
1039                 secwarning("%td trailing bytes after deltas DER", der_end - der);
1040             }
1041             message->additions = SOSManifestCreateWithData(manifestBody, error);
1042             CFReleaseSafe(manifestBody);
1043             break;
1044         }
1045         case SOSManifestDeltaAndObjectsMessageType:
1046         {
1047             der = der_decode_manifest_and_objects_message(message, error, der, der_end);
1048             break;
1049         }
1050         default:
1051             SOSErrorCreate(kSOSErrorInvalidMessage, error, NULL, CFSTR("Invalid message type %llu"), messageType);
1052             break;
1053     }
1054     return der;
1055 }
1056
1057 static const uint8_t *der_decode_message(SOSMessageRef message, CFErrorRef *error, const uint8_t *der, const uint8_t *der_end) {
1058     ccder_tag tag = 0;
1059     size_t body_len = 0;
1060
1061     der = ccder_decode_tag(&tag, der, der_end);
1062     if (tag != CCDER_CONSTRUCTED_SEQUENCE) return NULL;
1063     der = ccber_decode_len(&body_len, der, der_end);
1064     if (der && body_len && body_len != CCBER_LEN_INDEFINITE && (der_end - der) != (ptrdiff_t)body_len) {
1065         secwarning("%td trailing bytes after SOSMessage DER", (der_end - der) - (ptrdiff_t)body_len);
1066         der_end = der + body_len;
1067     }
1068
1069     if (ccder_decode_tag(&tag, der, der_end)) switch (tag) {
1070         case CCDER_INTEGER: // v0
1071             if (body_len == CCBER_LEN_INDEFINITE)
1072                 der = NULL; // Not supported for v0 messages
1073             else
1074                 der = der_decode_v0_message_body(message, error, der, der_end);
1075             break;
1076         case CCDER_CONSTRUCTED_SEQUENCE: //v2
1077             der = der_decode_message_header(message, error, der, der_end);
1078             der = der_decode_optional_deltas(message, der, der_end);
1079             der = der_decode_optional_extensions(message, error, der, der_end);
1080             der = der_decode_optional_objects(message, error, der, der_end);
1081         break;
1082     }
1083     return der;
1084 }
1085
1086 // Decode a SOSMessage
1087 SOSMessageRef SOSMessageCreateWithData(CFAllocatorRef allocator, CFDataRef derData, CFErrorRef *error) {
1088     if (!derData)
1089         return (SOSMessageRef)SOSErrorCreate(kSOSErrorDecodeFailure, error, NULL, CFSTR("NULL data => no SOSMessage"));
1090     SOSMessageRef message = CFTypeAllocate(SOSMessage, struct __OpaqueSOSMessage, allocator);
1091     if (!message)
1092         return (SOSMessageRef)SOSErrorCreate(kSOSErrorAllocationFailure, error, NULL, CFSTR("failed to alloc SOSMessage"));
1093     message->der = CFRetainSafe(derData);
1094     const uint8_t *der = CFDataGetBytePtr(derData);
1095     const uint8_t *der_end = der + CFDataGetLength(derData);
1096     der = der_decode_message(message, error, der, der_end);
1097     if (!der_end || der != der_end) {
1098         if (error && !*error)
1099             SOSErrorCreate(kSOSErrorDecodeFailure, error, NULL, CFSTR("SOSMessage DER decoding failure %td bytes left"), der_end - der);
1100         return CFReleaseSafe(message);
1101     }
1102     return message;
1103 }
1104
1105 // Read values from a decoded messgage
1106
1107 CFDataRef SOSMessageGetBaseDigest(SOSMessageRef message) {
1108     return message->baseDigest;
1109 }
1110
1111 CFDataRef SOSMessageGetProposedDigest(SOSMessageRef message) {
1112     return message->proposedDigest;
1113 }
1114
1115 CFDataRef SOSMessageGetSenderDigest(SOSMessageRef message) {
1116     return message->senderDigest;
1117 }
1118
1119 SOSMessageFlags SOSMessageGetFlags(SOSMessageRef message) {
1120     return message->flags;
1121 }
1122
1123 uint64_t SOSMessageGetSequenceNumber(SOSMessageRef message) {
1124     return message->sequenceNumber;
1125 }
1126
1127 SOSManifestRef SOSMessageGetRemovals(SOSMessageRef message) {
1128     return message->removals;
1129 }
1130
1131 SOSManifestRef SOSMessageGetAdditions(SOSMessageRef message) {
1132     return message->additions;
1133 }
1134
1135 // Iterate though the extensions in a decoded SOSMessage.  If criticalOnly is
1136 // true all non critical extensions are skipped.
1137 void SOSMessageWithExtensions(SOSMessageRef message, bool criticalOnly, void(^withExtension)(CFDataRef oid, bool isCritical, CFDataRef extension, bool *stop)) {
1138     // TODO
1139 }
1140
1141 size_t SOSMessageCountObjects(SOSMessageRef message) {
1142     if (message->objects)
1143         return CFArrayGetCount(message->objects);
1144     if (!message->objectsDer)
1145         return 0;
1146     const uint8_t *der = CFDataGetBytePtr(message->der);
1147     const uint8_t *der_end = der + CFDataGetLength(message->der);
1148     __block size_t count = 0;
1149     der_foreach_objects(message->objectsLen, message->objectsDer, der_end, NULL, ^(CFDataRef object, bool *stop){ ++count; });
1150     return count;
1151 }
1152
1153 // Iterate though the objects in a decoded SOSMessage.
1154 bool SOSMessageWithObjects(SOSMessageRef message, CFErrorRef *error,
1155                            void(^withObject)(CFDataRef object, bool *stop)) {
1156     if (message->objects) {
1157         CFDataRef object;
1158         CFArrayForEachC(message->objects, object) {
1159             bool stop = false;
1160             withObject(object, &stop);
1161             if (stop)
1162                 break;
1163         }
1164         return true;
1165     }
1166     if (!message->objectsDer)
1167         return true;
1168     const uint8_t *der = CFDataGetBytePtr(message->der);
1169     const uint8_t *der_end = der + CFDataGetLength(message->der);
1170     return der_foreach_objects(message->objectsLen, message->objectsDer, der_end, error, withObject);
1171 }
1172
1173 bool SOSMessageWithSOSObjects(SOSMessageRef message, SOSDataSourceRef dataSource, CFErrorRef *error,
1174                            void(^withObject)(SOSObjectRef object, bool *stop)) {
1175     return SOSMessageWithObjects(message, error, ^(CFDataRef object, bool *stop) {
1176         CFDictionaryRef plist = NULL;
1177         const uint8_t *der = CFDataGetBytePtr(object);
1178         const uint8_t *der_end = der + CFDataGetLength(object);
1179         // TODO Remove intermediate plist format
1180         der = der_decode_dictionary(kCFAllocatorDefault, kCFPropertyListImmutable, &plist, error, der, der_end);
1181         if (der) {
1182             SOSObjectRef peersObject = SOSObjectCreateWithPropertyList(dataSource, plist, error);
1183             withObject(peersObject, stop);
1184             CFReleaseSafe(peersObject);
1185         }
1186         CFReleaseSafe(plist);
1187     });
1188 }