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Diffstat (limited to 'Foundation/GTMBase64.m')
| -rw-r--r-- | Foundation/GTMBase64.m | 697 |
1 files changed, 697 insertions, 0 deletions
diff --git a/Foundation/GTMBase64.m b/Foundation/GTMBase64.m new file mode 100644 index 0000000..06d0414 --- /dev/null +++ b/Foundation/GTMBase64.m @@ -0,0 +1,697 @@ +// +// GTMBase64.m +// +// Copyright 2006-2008 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. +// + +#import "GTMBase64.h" +#import "GTMDefines.h" + +static const char *kBase64EncodeChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; +static const char *kWebSafeBase64EncodeChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_"; +static const char kBase64PaddingChar = '='; +static const char kBase64InvalidChar = 99; + +static const char kBase64DecodeChars[] = { + // This array was generated by the following code: + // #include <sys/time.h> + // #include <stdlib.h> + // #include <string.h> + // main() + // { + // static const char Base64[] = + // "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; + // char *pos; + // int idx, i, j; + // printf(" "); + // for (i = 0; i < 255; i += 8) { + // for (j = i; j < i + 8; j++) { + // pos = strchr(Base64, j); + // if ((pos == NULL) || (j == 0)) + // idx = 99; + // else + // idx = pos - Base64; + // if (idx == 99) + // printf(" %2d, ", idx); + // else + // printf(" %2d/*%c*/,", idx, j); + // } + // printf("\n "); + // } + // } + 99, 99, 99, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 99, 99, 99, + 99, 99, 99, 62/*+*/, 99, 99, 99, 63/*/ */, + 52/*0*/, 53/*1*/, 54/*2*/, 55/*3*/, 56/*4*/, 57/*5*/, 58/*6*/, 59/*7*/, + 60/*8*/, 61/*9*/, 99, 99, 99, 99, 99, 99, + 99, 0/*A*/, 1/*B*/, 2/*C*/, 3/*D*/, 4/*E*/, 5/*F*/, 6/*G*/, + 7/*H*/, 8/*I*/, 9/*J*/, 10/*K*/, 11/*L*/, 12/*M*/, 13/*N*/, 14/*O*/, + 15/*P*/, 16/*Q*/, 17/*R*/, 18/*S*/, 19/*T*/, 20/*U*/, 21/*V*/, 22/*W*/, + 23/*X*/, 24/*Y*/, 25/*Z*/, 99, 99, 99, 99, 99, + 99, 26/*a*/, 27/*b*/, 28/*c*/, 29/*d*/, 30/*e*/, 31/*f*/, 32/*g*/, + 33/*h*/, 34/*i*/, 35/*j*/, 36/*k*/, 37/*l*/, 38/*m*/, 39/*n*/, 40/*o*/, + 41/*p*/, 42/*q*/, 43/*r*/, 44/*s*/, 45/*t*/, 46/*u*/, 47/*v*/, 48/*w*/, + 49/*x*/, 50/*y*/, 51/*z*/, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 99, 99, 99 +}; + +static const char kWebSafeBase64DecodeChars[] = { + // This array was generated by the following code: + // #include <sys/time.h> + // #include <stdlib.h> + // #include <string.h> + // main() + // { + // static const char Base64[] = + // "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_"; + // char *pos; + // int idx, i, j; + // printf(" "); + // for (i = 0; i < 255; i += 8) { + // for (j = i; j < i + 8; j++) { + // pos = strchr(Base64, j); + // if ((pos == NULL) || (j == 0)) + // idx = 99; + // else + // idx = pos - Base64; + // if (idx == 99) + // printf(" %2d, ", idx); + // else + // printf(" %2d/*%c*/,", idx, j); + // } + // printf("\n "); + // } + // } + 99, 99, 99, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 62/*-*/, 99, 99, + 52/*0*/, 53/*1*/, 54/*2*/, 55/*3*/, 56/*4*/, 57/*5*/, 58/*6*/, 59/*7*/, + 60/*8*/, 61/*9*/, 99, 99, 99, 99, 99, 99, + 99, 0/*A*/, 1/*B*/, 2/*C*/, 3/*D*/, 4/*E*/, 5/*F*/, 6/*G*/, + 7/*H*/, 8/*I*/, 9/*J*/, 10/*K*/, 11/*L*/, 12/*M*/, 13/*N*/, 14/*O*/, + 15/*P*/, 16/*Q*/, 17/*R*/, 18/*S*/, 19/*T*/, 20/*U*/, 21/*V*/, 22/*W*/, + 23/*X*/, 24/*Y*/, 25/*Z*/, 99, 99, 99, 99, 63/*_*/, + 99, 26/*a*/, 27/*b*/, 28/*c*/, 29/*d*/, 30/*e*/, 31/*f*/, 32/*g*/, + 33/*h*/, 34/*i*/, 35/*j*/, 36/*k*/, 37/*l*/, 38/*m*/, 39/*n*/, 40/*o*/, + 41/*p*/, 42/*q*/, 43/*r*/, 44/*s*/, 45/*t*/, 46/*u*/, 47/*v*/, 48/*w*/, + 49/*x*/, 50/*y*/, 51/*z*/, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 99, 99, 99 +}; + + +// Tests a charact to see if it's a whitespace character. +// +// Returns: +// YES if the character is a whitespace character. +// NO if the character is not a whitespace character. +// +FOUNDATION_STATIC_INLINE BOOL IsSpace(unsigned char c) { + // we use our own mapping here because we don't want anything w/ locale + // support. + static BOOL kSpaces[256] = { + 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, // 0-9 + 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, // 10-19 + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 20-29 + 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, // 30-39 + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 40-49 + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 50-59 + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 60-69 + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 70-79 + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 80-89 + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 90-99 + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 100-109 + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 110-119 + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 120-129 + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 130-139 + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 140-149 + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 150-159 + 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 160-169 + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 170-179 + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 180-189 + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 190-199 + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 200-209 + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 210-219 + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 220-229 + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 230-239 + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 240-249 + 0, 0, 0, 0, 0, 1, // 250-255 + }; + return kSpaces[c]; +} + +// Calculate how long the data will be once it's base64 encoded. +// +// Returns: +// The guessed encoded length for a source length +// +FOUNDATION_STATIC_INLINE NSUInteger CalcEncodedLength(NSUInteger srcLen, + BOOL padded) { + NSUInteger intermediate_result = 8 * srcLen + 5; + NSUInteger len = intermediate_result / 6; + if (padded) { + len = ((len + 3) / 4) * 4; + } + return len; +} + +// Tries to calculate how long the data will be once it's base64 decoded. +// Unlinke the above, this is always an upperbound, since the source data +// could have spaces and might end with the padding characters on them. +// +// Returns: +// The guessed decoded length for a source length +// +FOUNDATION_STATIC_INLINE NSUInteger GuessDecodedLength(NSUInteger srcLen) { + return (srcLen + 3) / 4 * 3; +} + + +@interface GTMBase64 (PrivateMethods) + ++(NSData *)baseEncode:(const void *)bytes + length:(NSUInteger)length + charset:(const char *)charset + padded:(BOOL)padded; + ++(NSData *)baseDecode:(const void *)bytes + length:(NSUInteger)length + charset:(const char*)charset + requirePadding:(BOOL)requirePadding; + ++(NSUInteger)baseEncode:(const char *)srcBytes + srcLen:(NSUInteger)srcLen + destBytes:(char *)destBytes + destLen:(NSUInteger)destLen + charset:(const char *)charset + padded:(BOOL)padded; + ++(NSUInteger)baseDecode:(const char *)srcBytes + srcLen:(NSUInteger)srcLen + destBytes:(char *)destBytes + destLen:(NSUInteger)destLen + charset:(const char *)charset + requirePadding:(BOOL)requirePadding; + +@end + + +@implementation GTMBase64 + +// +// Standard Base64 (RFC) handling +// + ++(NSData *)encodeData:(NSData *)data { + return [self baseEncode:[data bytes] + length:[data length] + charset:kBase64EncodeChars + padded:YES]; +} + ++(NSData *)decodeData:(NSData *)data { + return [self baseDecode:[data bytes] + length:[data length] + charset:kBase64DecodeChars + requirePadding:YES]; +} + ++(NSData *)encodeBytes:(const void *)bytes length:(NSUInteger)length { + return [self baseEncode:bytes + length:length + charset:kBase64EncodeChars + padded:YES]; +} + ++(NSData *)decodeBytes:(const void *)bytes length:(NSUInteger)length { + return [self baseDecode:bytes + length:length + charset:kBase64DecodeChars + requirePadding:YES]; +} + ++(NSString *)stringByEncodingData:(NSData *)data { + NSString *result = nil; + NSData *converted = [self baseEncode:[data bytes] + length:[data length] + charset:kBase64EncodeChars + padded:YES]; + if (converted) { + result = [[[NSString alloc] initWithData:converted + encoding:NSASCIIStringEncoding] autorelease]; + } + return result; +} + ++(NSString *)stringByEncodingBytes:(const void *)bytes length:(NSUInteger)length { + NSString *result = nil; + NSData *converted = [self baseEncode:bytes + length:length + charset:kBase64EncodeChars + padded:YES]; + if (converted) { + result = [[[NSString alloc] initWithData:converted + encoding:NSASCIIStringEncoding] autorelease]; + } + return result; +} + ++(NSData *)decodeString:(NSString *)string { + NSData *result = nil; + NSData *data = [string dataUsingEncoding:NSASCIIStringEncoding]; + if (data) { + result = [self baseDecode:[data bytes] + length:[data length] + charset:kBase64DecodeChars + requirePadding:YES]; + } + return result; +} + +// +// Modified Base64 encoding so the results can go onto urls. +// +// The changes are in the characters generated and also the result isn't +// padded to a multiple of 4. +// Must use the matching call to encode/decode, won't interop with the +// RFC versions. +// + ++(NSData *)webSafeEncodeData:(NSData *)data + padded:(BOOL)padded { + return [self baseEncode:[data bytes] + length:[data length] + charset:kWebSafeBase64EncodeChars + padded:padded]; +} + ++(NSData *)webSafeDecodeData:(NSData *)data { + return [self baseDecode:[data bytes] + length:[data length] + charset:kWebSafeBase64DecodeChars + requirePadding:NO]; +} + ++(NSData *)webSafeEncodeBytes:(const void *)bytes + length:(NSUInteger)length + padded:(BOOL)padded { + return [self baseEncode:bytes + length:length + charset:kWebSafeBase64EncodeChars + padded:padded]; +} + ++(NSData *)webSafeDecodeBytes:(const void *)bytes length:(NSUInteger)length { + return [self baseDecode:bytes + length:length + charset:kWebSafeBase64DecodeChars + requirePadding:NO]; +} + ++(NSString *)stringByWebSafeEncodingData:(NSData *)data + padded:(BOOL)padded { + NSString *result = nil; + NSData *converted = [self baseEncode:[data bytes] + length:[data length] + charset:kWebSafeBase64EncodeChars + padded:padded]; + if (converted) { + result = [[[NSString alloc] initWithData:converted + encoding:NSASCIIStringEncoding] autorelease]; + } + return result; +} + ++(NSString *)stringByWebSafeEncodingBytes:(const void *)bytes + length:(NSUInteger)length + padded:(BOOL)padded { + NSString *result = nil; + NSData *converted = [self baseEncode:bytes + length:length + charset:kWebSafeBase64EncodeChars + padded:padded]; + if (converted) { + result = [[[NSString alloc] initWithData:converted + encoding:NSASCIIStringEncoding] autorelease]; + } + return result; +} + ++(NSData *)webSafeDecodeString:(NSString *)string { + NSData *result = nil; + NSData *data = [string dataUsingEncoding:NSASCIIStringEncoding]; + if (data) { + result = [self baseDecode:[data bytes] + length:[data length] + charset:kWebSafeBase64DecodeChars + requirePadding:NO]; + } + return result; +} + +@end + +@implementation GTMBase64 (PrivateMethods) + +// +// baseEncode:length:charset:padded: +// +// Does the common lifting of creating the dest NSData. it creates & sizes the +// data for the results. |charset| is the characters to use for the encoding +// of the data. |padding| controls if the encoded data should be padded to a +// multiple of 4. +// +// Returns: +// an autorelease NSData with the encoded data, nil if any error. +// ++(NSData *)baseEncode:(const void *)bytes + length:(NSUInteger)length + charset:(const char *)charset + padded:(BOOL)padded { + // how big could it be? + NSUInteger maxLength = CalcEncodedLength(length, padded); + // make space + NSMutableData *result = [NSMutableData data]; + [result setLength:maxLength]; + // do it + NSUInteger finalLength = [self baseEncode:bytes + srcLen:length + destBytes:[result mutableBytes] + destLen:[result length] + charset:charset + padded:padded]; + if (finalLength) { + _GTMDevAssert(finalLength == maxLength, @"how did we calc the length wrong?"); + } else { + // shouldn't happen, this means we ran out of space + result = nil; + } + return result; +} + +// +// baseDecode:length:charset:requirePadding: +// +// Does the common lifting of creating the dest NSData. it creates & sizes the +// data for the results. |charset| is the characters to use for the decoding +// of the data. +// +// Returns: +// an autorelease NSData with the decoded data, nil if any error. +// +// ++(NSData *)baseDecode:(const void *)bytes + length:(NSUInteger)length + charset:(const char *)charset + requirePadding:(BOOL)requirePadding { + // could try to calculate what it will end up as + NSUInteger maxLength = GuessDecodedLength(length); + // make space + NSMutableData *result = [NSMutableData data]; + [result setLength:maxLength]; + // do it + NSUInteger finalLength = [self baseDecode:bytes + srcLen:length + destBytes:[result mutableBytes] + destLen:[result length] + charset:charset + requirePadding:requirePadding]; + if (finalLength) { + if (finalLength != maxLength) { + // resize down to how big it was + [result setLength:finalLength]; + } + } else { + // either an error in the args, or we ran out of space + result = nil; + } + return result; +} + +// +// baseEncode:srcLen:destBytes:destLen:charset:padded: +// +// Encodes the buffer into the larger. returns the length of the encoded +// data, or zero for an error. +// |charset| is the characters to use for the encoding +// |padded| tells if the result should be padded to a multiple of 4. +// +// Returns: +// the length of the encoded data. zero if any error. +// ++(NSUInteger)baseEncode:(const char *)srcBytes + srcLen:(NSUInteger)srcLen + destBytes:(char *)destBytes + destLen:(NSUInteger)destLen + charset:(const char *)charset + padded:(BOOL)padded { + if (!srcLen || !destLen || !srcBytes || !destBytes) { + return 0; + } + + char *curDest = destBytes; + const unsigned char *curSrc = (const unsigned char *)(srcBytes); + + // Three bytes of data encodes to four characters of cyphertext. + // So we can pump through three-byte chunks atomically. + while (srcLen > 2) { + // space? + _GTMDevAssert(destLen >= 4, @"our calc for encoded length was wrong"); + curDest[0] = charset[curSrc[0] >> 2]; + curDest[1] = charset[((curSrc[0] & 0x03) << 4) + (curSrc[1] >> 4)]; + curDest[2] = charset[((curSrc[1] & 0x0f) << 2) + (curSrc[2] >> 6)]; + curDest[3] = charset[curSrc[2] & 0x3f]; + + curDest += 4; + curSrc += 3; + srcLen -= 3; + destLen -= 4; + } + + // now deal with the tail (<=2 bytes) + switch (srcLen) { + case 0: + // Nothing left; nothing more to do. + break; + case 1: + // One byte left: this encodes to two characters, and (optionally) + // two pad characters to round out the four-character cypherblock. + _GTMDevAssert(destLen >= 2, @"our calc for encoded length was wrong"); + curDest[0] = charset[curSrc[0] >> 2]; + curDest[1] = charset[(curSrc[0] & 0x03) << 4]; + curDest += 2; + destLen -= 2; + if (padded) { + _GTMDevAssert(destLen >= 2, @"our calc for encoded length was wrong"); + curDest[0] = kBase64PaddingChar; + curDest[1] = kBase64PaddingChar; + curDest += 2; + destLen -= 2; + } + break; + case 2: + // Two bytes left: this encodes to three characters, and (optionally) + // one pad character to round out the four-character cypherblock. + _GTMDevAssert(destLen >= 3, @"our calc for encoded length was wrong"); + curDest[0] = charset[curSrc[0] >> 2]; + curDest[1] = charset[((curSrc[0] & 0x03) << 4) + (curSrc[1] >> 4)]; + curDest[2] = charset[(curSrc[1] & 0x0f) << 2]; + curDest += 3; + destLen -= 3; + if (padded) { + _GTMDevAssert(destLen >= 1, @"our calc for encoded length was wrong"); + curDest[0] = kBase64PaddingChar; + curDest += 1; + destLen -= 1; + } + break; + } + // return the length + return (curDest - destBytes); +} + +// +// baseDecode:srcLen:destBytes:destLen:charset:requirePadding: +// +// Decodes the buffer into the larger. returns the length of the decoded +// data, or zero for an error. +// |charset| is the character decoding buffer to use +// +// Returns: +// the length of the encoded data. zero if any error. +// ++(NSUInteger)baseDecode:(const char *)srcBytes + srcLen:(NSUInteger)srcLen + destBytes:(char *)destBytes + destLen:(NSUInteger)destLen + charset:(const char *)charset + requirePadding:(BOOL)requirePadding { + if (!srcLen || !destLen || !srcBytes || !destBytes) { + return 0; + } + + int decode; + NSUInteger destIndex = 0; + int state = 0; + char ch = 0; + while (srcLen-- && (ch = *srcBytes++) != 0) { + if (IsSpace(ch)) // Skip whitespace + continue; + + if (ch == kBase64PaddingChar) + break; + + decode = charset[(unsigned int)ch]; + if (decode == kBase64InvalidChar) + return 0; + + // Four cyphertext characters decode to three bytes. + // Therefore we can be in one of four states. + switch (state) { + case 0: + // We're at the beginning of a four-character cyphertext block. + // This sets the high six bits of the first byte of the + // plaintext block. + _GTMDevAssert(destIndex < destLen, @"our calc for decoded length was wrong"); + destBytes[destIndex] = decode << 2; + state = 1; + break; + case 1: + // We're one character into a four-character cyphertext block. + // This sets the low two bits of the first plaintext byte, + // and the high four bits of the second plaintext byte. + _GTMDevAssert((destIndex+1) < destLen, @"our calc for decoded length was wrong"); + destBytes[destIndex] |= decode >> 4; + destBytes[destIndex+1] = (decode & 0x0f) << 4; + destIndex++; + state = 2; + break; + case 2: + // We're two characters into a four-character cyphertext block. + // This sets the low four bits of the second plaintext + // byte, and the high two bits of the third plaintext byte. + // However, if this is the end of data, and those two + // bits are zero, it could be that those two bits are + // leftovers from the encoding of data that had a length + // of two mod three. + _GTMDevAssert((destIndex+1) < destLen, @"our calc for decoded length was wrong"); + destBytes[destIndex] |= decode >> 2; + destBytes[destIndex+1] = (decode & 0x03) << 6; + destIndex++; + state = 3; + break; + case 3: + // We're at the last character of a four-character cyphertext block. + // This sets the low six bits of the third plaintext byte. + _GTMDevAssert(destIndex < destLen, @"our calc for decoded length was wrong"); + destBytes[destIndex] |= decode; + destIndex++; + state = 0; + break; + } + } + + // We are done decoding Base-64 chars. Let's see if we ended + // on a byte boundary, and/or with erroneous trailing characters. + if (ch == kBase64PaddingChar) { // We got a pad char + if ((state == 0) || (state == 1)) { + return 0; // Invalid '=' in first or second position + } + if (srcLen == 0) { + if (state == 2) { // We run out of input but we still need another '=' + return 0; + } + // Otherwise, we are in state 3 and only need this '=' + } else { + if (state == 2) { // need another '=' + while ((ch = *srcBytes++) && (srcLen-- > 0)) { + if (!IsSpace(ch)) + break; + } + if (ch != kBase64PaddingChar) { + return 0; + } + } + // state = 1 or 2, check if all remain padding is space + while ((ch = *srcBytes++) && (srcLen-- > 0)) { + if (!IsSpace(ch)) { + return 0; + } + } + } + } else { + // We ended by seeing the end of the string. + + if (requirePadding) { + // If we require padding, then anything but state 0 is an error. + if (state != 0) { + return 0; + } + } else { + // Make sure we have no partial bytes lying around. Note that we do not + // require trailing '=', so states 2 and 3 are okay too. + if (state == 1) { + return 0; + } + } + } + + // If then next piece of output was valid and got written to it means we got a + // very carefully crafted input that appeared valid but contains some trailing + // bits past the real length, so just toss the thing. + if ((destIndex < destLen) && + (destBytes[destIndex] != 0)) { + return 0; + } + + return destIndex; +} + +@end |