libsecurity_transform/lib/SecTransformReadTransform.cpp

   1 #include "SecTransformReadTransform.h"
   2 #include "SecCustomTransform.h"
   3 #include "Utilities.h"
   4
   5 static CFStringRef kStreamTransformName = CFSTR("SecReadStreamTransform");
   6 static CFStringRef kStreamMaxSize = CFSTR("MAX_READSIZE");
   7
   8 static SecTransformInstanceBlock StreamTransformImplementation(CFStringRef name,
   9                                                                                                                            SecTransformRef newTransform,
  10                                                                                                                            SecTransformImplementationRef ref)
  11 {
  12         SecTransformInstanceBlock instanceBlock =
  13         ^{
  14                 CFErrorRef result = NULL;
  15
  16                 if (NULL == name || NULL == newTransform)
  17                 {
  18                 }
  19
  20                 // define the storage for our block
  21                 __block CFIndex blockSize = 4096;  // make a default block size
  22
  23                 // it's not necessary to set the input stream size
  24                 SecTransformCustomSetAttribute(ref, kStreamMaxSize, kSecTransformMetaAttributeRequired, kCFBooleanFalse);
  25
  26                 // define the action if we change the max read size
  27                 SecTransformSetAttributeAction(ref, kSecTransformActionAttributeNotification, kStreamMaxSize,
  28                 ^(SecTransformAttributeRef attribute, CFTypeRef value)
  29                 {
  30                         CFNumberGetValue((CFNumberRef) value, kCFNumberCFIndexType, &blockSize);
  31                         return value;
  32                 });
  33
  34                 // define for our input action
  35                 SecTransformSetAttributeAction(ref, kSecTransformActionAttributeNotification, kSecTransformInputAttributeName,
  36                 ^(SecTransformAttributeRef attribute, CFTypeRef value)
  37                 {
  38                         if (value == NULL)
  39                         {
  40                                 return (CFTypeRef) NULL;
  41                         }
  42
  43                         CFArrayRef array = (CFArrayRef) value;
  44                         CFTypeRef item = (CFTypeRef) CFArrayGetValueAtIndex(array, 0);
  45
  46                         // Ensure that indeed we do have a CFReadStreamRef
  47                         if (NULL == item || CFReadStreamGetTypeID() != CFGetTypeID(item))
  48                         {
  49                                 return (CFTypeRef) CreateSecTransformErrorRef(kSecTransformErrorInvalidInput, "The input attribute item was nil or not a read stream");
  50                         }
  51
  52                         // This now is a safe cast
  53                         CFReadStreamRef input = (CFReadStreamRef)item;
  54
  55                         // Get the state of the stream
  56                         CFStreamStatus streamStatus = CFReadStreamGetStatus(input);
  57                         switch (streamStatus)
  58                         {
  59                                 case kCFStreamStatusNotOpen:
  60                                 {
  61                                         if (!CFReadStreamOpen(input))
  62                                         {
  63                                                 // We didn't open properly.  Error out
  64                                                 return (CFTypeRef) CreateSecTransformErrorRef(kSecTransformErrorInvalidInput, "An error occurred while opening the stream.");
  65                                         }
  66                                 }
  67                                 break;
  68
  69                                 case kCFStreamStatusError:
  70                                 {
  71                                         return (CFTypeRef) CreateSecTransformErrorRef(kSecTransformErrorInvalidInput, "The read stream is in an error state");
  72                                 }
  73                                 break;
  74
  75                                 default:
  76                                         // The assumption is that the stream is ready to go as is.
  77                                 break;
  78                         }
  79
  80                         // allocate the read buffer on the heap
  81                         u_int8_t* buffer = (u_int8_t*) malloc(blockSize);
  82
  83                         CFIndex bytesRead;
  84
  85                         bytesRead = CFReadStreamRead(input, buffer, blockSize);
  86                         while (bytesRead > 0)
  87                         {
  88                                 // make data from what was read
  89                                 CFDataRef value = CFDataCreate(NULL, buffer, bytesRead);
  90
  91                                 // send it down the chain
  92                                 SecTransformCustomSetAttribute(ref, kSecTransformOutputAttributeName, kSecTransformMetaAttributeValue, value);
  93
  94                                 // cleanup
  95                                 CFRelease(value);
  96
  97                                 bytesRead = CFReadStreamRead(input, buffer, blockSize);
  98                         }
  99
 100                         free(buffer);
 101
 102                         SecTransformCustomSetAttribute(ref, kSecTransformOutputAttributeName, kSecTransformMetaAttributeValue, (CFTypeRef) NULL);
 103
 104                         return (CFTypeRef) NULL;
 105                 });
 106
 107                 return result;
 108         };
 109
 110         return Block_copy(instanceBlock);
 111 }
 112
 113
 114
 115 SecTransformRef SecTransformCreateReadTransformWithReadStream(CFReadStreamRef inputStream)
 116 {
 117         static dispatch_once_t once = 0;
 118
 119         __block bool ok = true;
 120         __block CFErrorRef result = NULL;
 121
 122         dispatch_once(&once,
 123         ^{
 124                 ok = SecTransformRegister(kStreamTransformName, &StreamTransformImplementation, &result);
 125         });
 126
 127         if (!ok)
 128         {
 129                 return result;
 130         }
 131         else
 132         {
 133
 134                 SecTransformRef transform = SecTransformCreate(kStreamTransformName, &result);
 135                 if (NULL != transform)
 136                 {
 137                         // if we add the read stream directly to the transform the internal source stream
 138                         // will take over. This is bad.  Instead, we wrap this in a CFArray so that we can
 139                         // pass through undetected
 140                         CFTypeRef arrayData[] = {inputStream};
 141                         CFArrayRef arrayRef = CFArrayCreate(NULL, arrayData, 1, &kCFTypeArrayCallBacks);
 142
 143                         // add the input to the transform
 144                         SecTransformSetAttribute(transform, kSecTransformInputAttributeName, arrayRef, &result);
 145
 146                         CFRelease(arrayRef);
 147                 }
 148
 149                 return transform;
 150         }
 151 }