Security-55471.tar.gz

[apple/security.git] / utilities / src / der_number.c

diff --git a/utilities/src/der_number.c b/utilities/src/der_number.c
new file mode 100644 (file)
index 0000000..979b97b
--- /dev/null
+++ b/utilities/src/der_number.c
@@ -0,0 +1,122 @@
+//
+//  der_number.c
+//  utilities
+//
+//  Created by Mitch Adler on 6/19/12.
+//  Copyright (c) 2012 Apple Inc. All rights reserved.
+//
+
+
+#include <stdio.h>
+
+#include "utilities/SecCFRelease.h"
+#include "utilities/der_plist.h"
+#include "utilities/der_plist_internal.h"
+
+#include <corecrypto/ccder.h>
+#include <CoreFoundation/CoreFoundation.h>
+
+
+const uint8_t* der_decode_number(CFAllocatorRef allocator, CFOptionFlags mutability,
+                                 CFNumberRef* number, CFErrorRef *error,
+                                 const uint8_t* der, const uint8_t *der_end)
+{
+    if (NULL == der)
+        return NULL;
+
+    size_t payload_size = 0;
+    const uint8_t *payload = ccder_decode_tl(CCDER_INTEGER, &payload_size, der, der_end);
+
+    if (NULL == payload || (der_end - payload) < payload_size) {
+        SecCFDERCreateError(kSecDERErrorUnknownEncoding, CFSTR("Unknown number encoding"), NULL, error);
+        return NULL;
+    }
+    if (payload_size > sizeof(long long)) {
+        SecCFDERCreateError(kSecDERErrorUnsupportedNumberType, CFSTR("Number too large"), NULL, error);
+        return NULL;
+
+    }
+
+    long long value = 0;
+    
+    if (payload_size > 0) {
+        if ((*payload & 0x80) == 0x80)
+            value = -1; // Negative integers fill with 1s so we end up negative.
+        
+        const uint8_t* const payload_end = payload + payload_size;
+        
+        for (const uint8_t *payload_byte = payload;
+             payload_byte < payload_end;
+             ++payload_byte) {
+            value <<= 8;
+            value |= *payload_byte;
+        }
+    }
+
+    *number = CFNumberCreate(allocator, kCFNumberLongLongType, &value);
+    
+    if (*number == NULL) {
+        SecCFDERCreateError(kSecDERErrorAllocationFailure, CFSTR("Number allocation failed"), NULL, error);
+        return NULL;
+    }
+    
+    return payload + payload_size;
+}
+
+
+static inline uint8_t byte_of(size_t byteNumber, long long value)
+{
+    return value >> (8 * (byteNumber - 1));
+}
+
+static inline size_t bytes_when_encoded(long long value)
+{
+    size_t bytes_encoded = sizeof(long long);
+    
+    uint8_t first_byte = byte_of(bytes_encoded, value);
+    
+    // Skip initial 0xFFs or 0x00
+    if (first_byte == 0xFF || first_byte == 0x00) {
+        do {
+            --bytes_encoded;
+        } while (bytes_encoded > 1 && (byte_of(bytes_encoded, value) == first_byte));
+        
+        if ((first_byte & 0x80) != (byte_of(bytes_encoded, value) & 0x80))
+            bytes_encoded += 1;
+    }
+    
+    return bytes_encoded;
+}
+
+size_t der_sizeof_number(CFNumberRef data, CFErrorRef *error)
+{
+    long long value;
+    if (!CFNumberGetValue(data, kCFNumberLongLongType, &value))
+        return 0;
+    
+    return ccder_sizeof(CCDER_INTEGER, bytes_when_encoded(value));
+}
+
+uint8_t* der_encode_number(CFNumberRef number, CFErrorRef *error,
+                           const uint8_t *der, uint8_t *der_end)
+{
+    long long value;
+    if (!CFNumberGetValue(number, kCFNumberLongLongType, &value))
+        return NULL;
+    
+    size_t first_byte_to_include = bytes_when_encoded(value);
+    
+    if (!der_end || der_end - der < first_byte_to_include)
+        return NULL;
+
+    // Put the bytes we should include on the end.
+    for(int bytes_included = 0; bytes_included < first_byte_to_include; ++bytes_included)
+    {
+        --der_end;
+        *der_end = value & 0xFF;
+        value >>= 8;
+    }
+
+    return ccder_encode_tl(CCDER_INTEGER, first_byte_to_include, der, der_end);
+
+}