base64是广为使用的一种编码及解码方式, 通常用于网络传输和邮件传输中,使用base64可以将标点符号以及多字节文字等特殊字符编码以便传输,以下是base64 编码解码的objective-c代码, 可以用于desktop和iphone程序当中
头文件
1 2 3 4 5 6 7 | #include <UIKit/UIKit.h> extern size_t EstimateBas64EncodedDataSize(size_t inDataSize); extern size_t EstimateBas64DecodedDataSize(size_t inDataSize); extern bool Base64EncodeData(const void *inInputData, size_t inInputDataSize, char *outOutputData, size_t *ioOutputDataSize, BOOL wrapped); extern bool Base64DecodeData(const void *inInputData, size_t inInputDataSize, void *ioOutputData, size_t *ioOutputDataSize); |
实现文件
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 | #include "Base64Transcoder.h" #include <math.h> const UInt8 kBase64EncodeTable[64] = { /* 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', /* 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', /* 52 */ '0', /* 53 */ '1', /* 54 */ '2', /* 55 */ '3', /* 56 */ '4', /* 57 */ '5', /* 58 */ '6', /* 59 */ '7', /* 60 */ '8', /* 61 */ '9', /* 62 */ '+', /* 63 */ '/' }; /* -1 = Base64 end of data marker. -2 = White space (tabs, cr, lf, space) -3 = Noise (all non whitespace, non-base64 characters) -4 = Dangerous noise -5 = Illegal noise (null byte) */ const SInt8 kBase64DecodeTable[128] = { /* 0x00 */ -5, /* 0x01 */ -3, /* 0x02 */ -3, /* 0x03 */ -3, /* 0x04 */ -3, /* 0x05 */ -3, /* 0x06 */ -3, /* 0x07 */ -3, /* 0x08 */ -3, /* 0x09 */ -2, /* 0x0a */ -2, /* 0x0b */ -2, /* 0x0c */ -2, /* 0x0d */ -2, /* 0x0e */ -3, /* 0x0f */ -3, /* 0x10 */ -3, /* 0x11 */ -3, /* 0x12 */ -3, /* 0x13 */ -3, /* 0x14 */ -3, /* 0x15 */ -3, /* 0x16 */ -3, /* 0x17 */ -3, /* 0x18 */ -3, /* 0x19 */ -3, /* 0x1a */ -3, /* 0x1b */ -3, /* 0x1c */ -3, /* 0x1d */ -3, /* 0x1e */ -3, /* 0x1f */ -3, /* ' ' */ -2, /* '!' */ -3, /* '"' */ -3, /* '#' */ -3, /* '$' */ -3, /* '%' */ -3, /* '&' */ -3, /* ''' */ -3, /* '(' */ -3, /* ')' */ -3, /* '*' */ -3, /* '+' */ 62, /* ',' */ -3, /* '-' */ -3, /* '.' */ -3, /* '/' */ 63, /* '0' */ 52, /* '1' */ 53, /* '2' */ 54, /* '3' */ 55, /* '4' */ 56, /* '5' */ 57, /* '6' */ 58, /* '7' */ 59, /* '8' */ 60, /* '9' */ 61, /* ':' */ -3, /* ';' */ -3, /* '<' */ -3, /* '=' */ -1, /* '>' */ -3, /* '?' */ -3, /* '@' */ -3, /* 'A' */ 0, /* 'B' */ 1, /* 'C' */ 2, /* 'D' */ 3, /* 'E' */ 4, /* 'F' */ 5, /* 'G' */ 6, /* 'H' */ 7, /* 'I' */ 8, /* 'J' */ 9, /* 'K' */ 10, /* 'L' */ 11, /* 'M' */ 12, /* 'N' */ 13, /* 'O' */ 14, /* 'P' */ 15, /* 'Q' */ 16, /* 'R' */ 17, /* 'S' */ 18, /* 'T' */ 19, /* 'U' */ 20, /* 'V' */ 21, /* 'W' */ 22, /* 'X' */ 23, /* 'Y' */ 24, /* 'Z' */ 25, /* '[' */ -3, /* '\' */ -3, /* ']' */ -3, /* '^' */ -3, /* '_' */ -3, /* '`' */ -3, /* 'a' */ 26, /* 'b' */ 27, /* 'c' */ 28, /* 'd' */ 29, /* 'e' */ 30, /* 'f' */ 31, /* 'g' */ 32, /* 'h' */ 33, /* 'i' */ 34, /* 'j' */ 35, /* 'k' */ 36, /* 'l' */ 37, /* 'm' */ 38, /* 'n' */ 39, /* 'o' */ 40, /* 'p' */ 41, /* 'q' */ 42, /* 'r' */ 43, /* 's' */ 44, /* 't' */ 45, /* 'u' */ 46, /* 'v' */ 47, /* 'w' */ 48, /* 'x' */ 49, /* 'y' */ 50, /* 'z' */ 51, /* '{' */ -3, /* '|' */ -3, /* '}' */ -3, /* '~' */ -3, /* 0x7f */ -3 }; const UInt8 kBits_00000011 = 0x03; const UInt8 kBits_00001111 = 0x0F; const UInt8 kBits_00110000 = 0x30; const UInt8 kBits_00111100 = 0x3C; const UInt8 kBits_00111111 = 0x3F; const UInt8 kBits_11000000 = 0xC0; const UInt8 kBits_11110000 = 0xF0; const UInt8 kBits_11111100 = 0xFC; size_t EstimateBas64EncodedDataSize(size_t inDataSize) { size_t theEncodedDataSize = (int)ceil(inDataSize / 3.0) * 4; theEncodedDataSize = theEncodedDataSize / 72 * 74 + theEncodedDataSize % 72; return(theEncodedDataSize); } size_t EstimateBas64DecodedDataSize(size_t inDataSize) { size_t theDecodedDataSize = (int)ceil(inDataSize / 4.0) * 3; //theDecodedDataSize = theDecodedDataSize / 72 * 74 + theDecodedDataSize % 72; return(theDecodedDataSize); } bool Base64EncodeData(const void *inInputData, size_t inInputDataSize, char *outOutputData, size_t *ioOutputDataSize, BOOL wrapped) { size_t theEncodedDataSize = EstimateBas64EncodedDataSize(inInputDataSize); if (*ioOutputDataSize < theEncodedDataSize) return(false); *ioOutputDataSize = theEncodedDataSize; const UInt8 *theInPtr = (const UInt8 *)inInputData; UInt32 theInIndex = 0, theOutIndex = 0; for (; theInIndex < (inInputDataSize / 3) * 3; theInIndex += 3) { outOutputData[theOutIndex++] = kBase64EncodeTable[(theInPtr[theInIndex] & kBits_11111100) >> 2]; outOutputData[theOutIndex++] = kBase64EncodeTable[(theInPtr[theInIndex] & kBits_00000011) << 4 | (theInPtr[theInIndex + 1] & kBits_11110000) >> 4]; outOutputData[theOutIndex++] = kBase64EncodeTable[(theInPtr[theInIndex + 1] & kBits_00001111) << 2 | (theInPtr[theInIndex + 2] & kBits_11000000) >> 6]; outOutputData[theOutIndex++] = kBase64EncodeTable[(theInPtr[theInIndex + 2] & kBits_00111111) >> 0]; if (wrapped && (theOutIndex % 74 == 72)) { outOutputData[theOutIndex++] = '\r'; outOutputData[theOutIndex++] = '\n'; } } const size_t theRemainingBytes = inInputDataSize - theInIndex; if (theRemainingBytes == 1) { outOutputData[theOutIndex++] = kBase64EncodeTable[(theInPtr[theInIndex] & kBits_11111100) >> 2]; outOutputData[theOutIndex++] = kBase64EncodeTable[(theInPtr[theInIndex] & kBits_00000011) << 4 | (0 & kBits_11110000) >> 4]; outOutputData[theOutIndex++] = '='; outOutputData[theOutIndex++] = '='; if (wrapped && (theOutIndex % 74 == 72)) { outOutputData[theOutIndex++] = '\r'; outOutputData[theOutIndex++] = '\n'; } } else if (theRemainingBytes == 2) { outOutputData[theOutIndex++] = kBase64EncodeTable[(theInPtr[theInIndex] & kBits_11111100) >> 2]; outOutputData[theOutIndex++] = kBase64EncodeTable[(theInPtr[theInIndex] & kBits_00000011) << 4 | (theInPtr[theInIndex + 1] & kBits_11110000) >> 4]; outOutputData[theOutIndex++] = kBase64EncodeTable[(theInPtr[theInIndex + 1] & kBits_00001111) << 2 | (0 & kBits_11000000) >> 6]; outOutputData[theOutIndex++] = '='; if (wrapped && (theOutIndex % 74 == 72)) { outOutputData[theOutIndex++] = '\r'; outOutputData[theOutIndex++] = '\n'; } } return(true); } bool Base64DecodeData(const void *inInputData, size_t inInputDataSize, void *ioOutputData, size_t *ioOutputDataSize) { memset(ioOutputData, '.', *ioOutputDataSize); size_t theDecodedDataSize = EstimateBas64DecodedDataSize(inInputDataSize); if (*ioOutputDataSize < theDecodedDataSize) return(false); *ioOutputDataSize = 0; const UInt8 *theInPtr = (const UInt8 *)inInputData; UInt8 *theOutPtr = (UInt8 *)ioOutputData; size_t theInIndex = 0, theOutIndex = 0; UInt8 theOutputOctet; size_t theSequence = 0; for (; theInIndex < inInputDataSize; ) { SInt8 theSextet = 0; SInt8 theCurrentInputOctet = theInPtr[theInIndex]; theSextet = kBase64DecodeTable[theCurrentInputOctet]; if (theSextet == -1) break; while (theSextet == -2) { theCurrentInputOctet = theInPtr[++theInIndex]; theSextet = kBase64DecodeTable[theCurrentInputOctet]; } while (theSextet == -3) { theCurrentInputOctet = theInPtr[++theInIndex]; theSextet = kBase64DecodeTable[theCurrentInputOctet]; } if (theSequence == 0) { theOutputOctet = (theSextet >= 0 ? theSextet : 0) << 2 & kBits_11111100; } else if (theSequence == 1) { theOutputOctet |= (theSextet >- 0 ? theSextet : 0) >> 4 & kBits_00000011; theOutPtr[theOutIndex++] = theOutputOctet; } else if (theSequence == 2) { theOutputOctet = (theSextet >= 0 ? theSextet : 0) << 4 & kBits_11110000; } else if (theSequence == 3) { theOutputOctet |= (theSextet >= 0 ? theSextet : 0) >> 2 & kBits_00001111; theOutPtr[theOutIndex++] = theOutputOctet; } else if (theSequence == 4) { theOutputOctet = (theSextet >= 0 ? theSextet : 0) << 6 & kBits_11000000; } else if (theSequence == 5) { theOutputOctet |= (theSextet >= 0 ? theSextet : 0) >> 0 & kBits_00111111; theOutPtr[theOutIndex++] = theOutputOctet; } theSequence = (theSequence + 1) % 6; if (theSequence != 2 && theSequence != 4) theInIndex++; } *ioOutputDataSize = theOutIndex; return(true); } |