keychain/SecureObjectSync/SOSGenCount.c

   1 //
   2 //  SOSGenCount.c
   3 //  sec
   4 //
   5 //  Created by Richard Murphy on 1/29/15.
   6 //
   7 //
   8
   9 #include "SOSGenCount.h"
  10 #include <utilities/SecCFWrappers.h>
  11 #include <CoreFoundation/CFLocale.h>
  12 #include <utilities/der_plist.h>
  13 #include <utilities/der_plist_internal.h>
  14
  15
  16 static CFAbsoluteTime SOSGenerationCountGetDateBits(int64_t genValue) {
  17     return (uint32_t) ((((uint64_t) genValue) >> 32) << 1);
  18 }
  19
  20 void SOSGenerationCountWithDescription(SOSGenCountRef gen, void (^operation)(CFStringRef description)) {
  21     CFStringRef description = SOSGenerationCountCopyDescription(gen);
  22
  23     operation(description);
  24
  25     CFReleaseSafe(description);
  26 }
  27
  28 CFStringRef SOSGenerationCountCopyDescription(SOSGenCountRef gen) {
  29     int64_t value = SOSGetGenerationSint(gen);
  30
  31     CFMutableStringRef gcDecsription = CFStringCreateMutableCopy(kCFAllocatorDefault, 0, CFSTR("["));
  32
  33     withStringOfAbsoluteTime(SOSGenerationCountGetDateBits(value), ^(CFStringRef decription) {
  34         CFStringAppend(gcDecsription, decription);
  35     });
  36
  37     CFStringAppendFormat(gcDecsription, NULL, CFSTR(" %u]"), (uint32_t)(value & 0xFFFFFFFF));
  38
  39     return gcDecsription;
  40 }
  41
  42 int64_t SOSGetGenerationSint(SOSGenCountRef gen) {
  43     int64_t value;
  44     if(!gen) return 0;
  45     CFNumberGetValue(gen, kCFNumberSInt64Type, &value);
  46     return value;
  47 }
  48
  49 static int64_t sosGenerationSetHighBits(int64_t value, int32_t high_31)
  50 {
  51     value &= 0xFFFFFFFF; // Keep the low 32 bits.
  52     value |= ((int64_t) high_31) << 32;
  53
  54     return value;
  55 }
  56
  57 static SOSGenCountRef sosGenerationCreateOrIncrement(SOSGenCountRef gen) {
  58     int64_t value = 0;
  59
  60     if(gen) {
  61         value = SOSGetGenerationSint(gen);
  62     }
  63
  64     if((value >> 32) == 0) {
  65         uint32_t seconds = CFAbsoluteTimeGetCurrent(); // seconds
  66         value = sosGenerationSetHighBits(value, (seconds >> 1));
  67     }
  68
  69     value++;
  70     return CFNumberCreate(NULL, kCFNumberSInt64Type, &value);
  71 }
  72
  73 SOSGenCountRef SOSGenerationCreate() {
  74     return sosGenerationCreateOrIncrement(NULL);
  75 }
  76
  77
  78 // We need this for a circle gencount test
  79 SOSGenCountRef SOSGenerationCreateWithValue(int64_t value) {
  80     return CFNumberCreate(NULL, kCFNumberSInt64Type, &value);
  81 }
  82
  83 SOSGenCountRef SOSGenerationIncrementAndCreate(SOSGenCountRef gen) {
  84     return sosGenerationCreateOrIncrement(gen);
  85 }
  86
  87 SOSGenCountRef SOSGenerationCopy(SOSGenCountRef gen) {
  88     if(!gen) return NULL;
  89     int64_t value = SOSGetGenerationSint(gen);
  90     return CFNumberCreate(NULL, kCFNumberSInt64Type, &value);
  91 }
  92
  93 // Is current older than proposed?
  94 bool SOSGenerationIsOlder(SOSGenCountRef older, SOSGenCountRef newer) {
  95     switch(CFNumberCompare(older, newer, NULL)) {
  96         case kCFCompareLessThan:  return true;
  97         case kCFCompareEqualTo: return false;
  98         case kCFCompareGreaterThan:  return false;
  99     }
 100     return false;
 101 }
 102
 103 // Is current older than proposed?
 104 static bool SOSGenerationIsOlderOrEqual(SOSGenCountRef older, SOSGenCountRef newer) {
 105     switch(CFNumberCompare(older, newer, NULL)) {
 106         case kCFCompareLessThan:  return true;
 107         case kCFCompareEqualTo: return true;
 108         case kCFCompareGreaterThan:  return false;
 109     }
 110     return false;
 111 }
 112
 113
 114 SOSGenCountRef SOSGenerationCreateWithBaseline(SOSGenCountRef reference) {
 115     SOSGenCountRef retval = SOSGenerationCreate();
 116     if(SOSGenerationIsOlderOrEqual(retval, reference)) {
 117         CFReleaseNull(retval);
 118         retval = SOSGenerationIncrementAndCreate(reference);
 119     }
 120     return retval;
 121 }
 122
 123
 124 SOSGenCountRef SOSGenCountCreateFromDER(CFAllocatorRef allocator, CFErrorRef* error,
 125                                         const uint8_t** der_p, const uint8_t *der_end) {
 126     SOSGenCountRef retval = NULL;
 127     *der_p = der_decode_number(allocator, &retval, error, *der_p, der_end);
 128     if(retval == NULL)
 129         retval = SOSGenerationCreate();
 130     return retval;
 131 }
 132
 133 size_t SOSGenCountGetDEREncodedSize(SOSGenCountRef gencount, CFErrorRef *error) {
 134     return der_sizeof_number(gencount, error);
 135 }
 136
 137 uint8_t *SOSGenCountEncodeToDER(SOSGenCountRef gencount, CFErrorRef* error, const uint8_t* der, uint8_t* der_end) {
 138     return der_encode_number(gencount, error, der, der_end);
 139 }
 140
 141
 142