140 lines
4.6 KiB
Objective-C
140 lines
4.6 KiB
Objective-C
/* Copyright (c) 2012 Google Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#import "GTLBase64.h"
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// Based on Cyrus Najmabadi's elegent little encoder and decoder from
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// http://www.cocoadev.com/index.pl?BaseSixtyFour
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static char gStandardEncodingTable[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
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static char gWebSafeEncodingTable[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";
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#pragma mark Encode
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static NSString *EncodeBase64StringCommon(NSData *data, const char *table) {
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if (data == nil) return nil;
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const uint8_t* input = [data bytes];
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NSUInteger length = [data length];
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NSUInteger bufferSize = ((length + 2) / 3) * 4;
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NSMutableData* buffer = [NSMutableData dataWithLength:bufferSize];
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int8_t *output = [buffer mutableBytes];
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for (NSUInteger i = 0; i < length; i += 3) {
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NSUInteger value = 0;
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for (NSUInteger j = i; j < (i + 3); j++) {
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value <<= 8;
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if (j < length) {
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value |= (0xFF & input[j]);
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}
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}
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NSInteger idx = (i / 3) * 4;
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output[idx + 0] = table[(value >> 18) & 0x3F];
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output[idx + 1] = table[(value >> 12) & 0x3F];
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output[idx + 2] = (i + 1) < length ? table[(value >> 6) & 0x3F] : '=';
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output[idx + 3] = (i + 2) < length ? table[(value >> 0) & 0x3F] : '=';
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}
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NSString *result = [[[NSString alloc] initWithData:buffer
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encoding:NSASCIIStringEncoding] autorelease];
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return result;
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}
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NSString *GTLEncodeBase64(NSData *data) {
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return EncodeBase64StringCommon(data, gStandardEncodingTable);
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}
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NSString *GTLEncodeWebSafeBase64(NSData *data) {
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return EncodeBase64StringCommon(data, gWebSafeEncodingTable);
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}
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#pragma mark Decode
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static void CreateDecodingTable(const char *encodingTable,
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size_t encodingTableSize, char *decodingTable) {
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memset(decodingTable, 0, 128);
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for (unsigned int i = 0; i < encodingTableSize; i++) {
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decodingTable[(unsigned int) encodingTable[i]] = (char)i;
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}
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}
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static NSData *DecodeBase64StringCommon(NSString *base64Str,
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char *decodingTable) {
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// The input string should be plain ASCII
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const char *cString = [base64Str cStringUsingEncoding:NSASCIIStringEncoding];
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if (cString == nil) return nil;
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NSInteger inputLength = (NSInteger)strlen(cString);
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if (inputLength % 4 != 0) return nil;
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if (inputLength == 0) return [NSData data];
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while (inputLength > 0 && cString[inputLength - 1] == '=') {
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inputLength--;
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}
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NSInteger outputLength = inputLength * 3 / 4;
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NSMutableData* data = [NSMutableData dataWithLength:(NSUInteger)outputLength];
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uint8_t *output = [data mutableBytes];
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NSInteger inputPoint = 0;
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NSInteger outputPoint = 0;
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char *table = decodingTable;
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while (inputPoint < inputLength) {
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int i0 = cString[inputPoint++];
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int i1 = cString[inputPoint++];
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int i2 = inputPoint < inputLength ? cString[inputPoint++] : 'A'; // 'A' will decode to \0
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int i3 = inputPoint < inputLength ? cString[inputPoint++] : 'A';
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output[outputPoint++] = (uint8_t)((table[i0] << 2) | (table[i1] >> 4));
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if (outputPoint < outputLength) {
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output[outputPoint++] = (uint8_t)(((table[i1] & 0xF) << 4) | (table[i2] >> 2));
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}
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if (outputPoint < outputLength) {
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output[outputPoint++] = (uint8_t)(((table[i2] & 0x3) << 6) | table[i3]);
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}
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}
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return data;
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}
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NSData *GTLDecodeBase64(NSString *base64Str) {
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static char decodingTable[128];
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static BOOL hasInited = NO;
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if (!hasInited) {
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CreateDecodingTable(gStandardEncodingTable, sizeof(gStandardEncodingTable),
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decodingTable);
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hasInited = YES;
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}
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return DecodeBase64StringCommon(base64Str, decodingTable);
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}
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NSData *GTLDecodeWebSafeBase64(NSString *base64Str) {
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static char decodingTable[128];
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static BOOL hasInited = NO;
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if (!hasInited) {
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CreateDecodingTable(gWebSafeEncodingTable, sizeof(gWebSafeEncodingTable),
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decodingTable);
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hasInited = YES;
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}
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return DecodeBase64StringCommon(base64Str, decodingTable);
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}
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