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// // FIRInstanceIDStringEncoding.m // // Copyright 2009 Google Inc. // // Licensed under the Apache License, Version 2.0 (the "License"); you may not // use this file except in compliance with the License. You may obtain a copy // of the License at // // http://www.apache.org/licenses/LICENSE-2.0 // // Unless required by applicable law or agreed to in writing, software // distributed under the License is distributed on an "AS IS" BASIS, WITHOUT // WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the // License for the specific language governing permissions and limitations under // the License. //
// This is a copy of GTMStringEncoding. FIRInstanceID wants to avoid // a CocoaPods GTM dependency. Hence we use our own version of StringEncoding.
#import "FIRInstanceIDStringEncoding.h"
#import "FIRInstanceIDLogger.h"
enum { kUnknownChar = -1, kPaddingChar = -2, kIgnoreChar = -3 };
@implementation FIRInstanceIDStringEncoding
+ (id)rfc4648Base64WebsafeStringEncoding { FIRInstanceIDStringEncoding *ret = [self stringEncodingWithString:@"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_"];
[ret setPaddingChar:'=']; [ret setDoPad:YES]; return ret; }
static inline int lcm(int a, int b) { for (int aa = a, bb = b;;) { if (aa == bb) return aa; else if (aa < bb) aa += a; else bb += b; } }
+ (id)stringEncodingWithString:(NSString *)string { return [[FIRInstanceIDStringEncoding alloc] initWithString:string]; }
- (id)initWithString:(NSString *)string { if ((self = [super init])) { charMapData_ = [string dataUsingEncoding:NSASCIIStringEncoding]; if (!charMapData_) { // Unable to convert string to ASCII return nil; } charMap_ = (char *)[charMapData_ bytes]; NSUInteger length = [charMapData_ length]; if (length < 2 || length > 128 || length & (length - 1)) { // Length not a power of 2 between 2 and 128 return nil; }
memset(reverseCharMap_, kUnknownChar, sizeof(reverseCharMap_)); for (unsigned int i = 0; i < length; i++) { if (reverseCharMap_[(int)charMap_[i]] != kUnknownChar) { // Duplicate character at |i| return nil; } reverseCharMap_[(int)charMap_[i]] = i; }
for (NSUInteger i = 1; i < length; i <<= 1) shift_++; mask_ = (1 << shift_) - 1; padLen_ = lcm(8, shift_) / shift_; } return self; }
- (NSString *)description { return [NSString stringWithFormat:@"<Base%d StringEncoder: %@>", 1 << shift_, charMapData_]; }
- (BOOL)doPad { return doPad_; }
- (void)setDoPad:(BOOL)doPad { doPad_ = doPad; }
- (void)setPaddingChar:(char)c { paddingChar_ = c; reverseCharMap_[(int)c] = kPaddingChar; }
- (NSString *)encode:(NSData *)inData { NSUInteger inLen = [inData length]; if (inLen <= 0) { // Empty input return @""; } unsigned char *inBuf = (unsigned char *)[inData bytes]; NSUInteger inPos = 0;
NSUInteger outLen = (inLen * 8 + shift_ - 1) / shift_; if (doPad_) { outLen = ((outLen + padLen_ - 1) / padLen_) * padLen_; } NSMutableData *outData = [NSMutableData dataWithLength:outLen]; unsigned char *outBuf = (unsigned char *)[outData mutableBytes]; NSUInteger outPos = 0;
unsigned int buffer = inBuf[inPos++]; int bitsLeft = 8; while (bitsLeft > 0 || inPos < inLen) { if (bitsLeft < shift_) { if (inPos < inLen) { buffer <<= 8; buffer |= (inBuf[inPos++] & 0xff); bitsLeft += 8; } else { int pad = shift_ - bitsLeft; buffer <<= pad; bitsLeft += pad; } } unsigned int idx = (buffer >> (bitsLeft - shift_)) & mask_; bitsLeft -= shift_; outBuf[outPos++] = charMap_[idx]; }
if (doPad_) { while (outPos < outLen) outBuf[outPos++] = paddingChar_; }
if (outPos != outLen) { FIRInstanceIDLoggerError(kFIRInstanceIDStringEncodingBufferUnderflow, @"Underflowed output buffer"); return nil; } [outData setLength:outPos];
return [[NSString alloc] initWithData:outData encoding:NSASCIIStringEncoding]; }
- (NSData *)decode:(NSString *)inString { char *inBuf = (char *)[inString cStringUsingEncoding:NSASCIIStringEncoding]; if (!inBuf) { // Unable to convert buffer to ASCII return nil; } NSUInteger inLen = strlen(inBuf);
NSUInteger outLen = inLen * shift_ / 8; NSMutableData *outData = [NSMutableData dataWithLength:outLen]; unsigned char *outBuf = (unsigned char *)[outData mutableBytes]; NSUInteger outPos = 0;
int buffer = 0; int bitsLeft = 0; BOOL expectPad = NO; for (NSUInteger i = 0; i < inLen; i++) { int val = reverseCharMap_[(int)inBuf[i]]; switch (val) { case kIgnoreChar: break; case kPaddingChar: expectPad = YES; break; case kUnknownChar: // Unexpected data at input pos |i| return nil; default: if (expectPad) { // Expected further padding characters return nil; } buffer <<= shift_; buffer |= val & mask_; bitsLeft += shift_; if (bitsLeft >= 8) { outBuf[outPos++] = (unsigned char)(buffer >> (bitsLeft - 8)); bitsLeft -= 8; } break; } }
if (bitsLeft && buffer & ((1 << bitsLeft) - 1)) { // Incomplete trailing data return nil; }
// Shorten buffer if needed due to padding chars if (outPos > outLen) { FIRInstanceIDLoggerError(kFIRInstanceIDStringEncodingBufferOverflow, @"Overflowed buffer"); } [outData setLength:outPos];
return outData; }
@end
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