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//*********************************************************************
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//* Base64 - a simple base64 encoder and decoder.
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//* Copyright (c) 1999, Bob Withers - bwit@pobox.com
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//* This code may be freely used for any purpose, either personal
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//* or commercial, provided the authors copyright notice remains
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//* Enhancements by Stanley Yamane:
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//* o reverse lookup table for the decode function
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//* o reserve string buffer space in advance
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//*********************************************************************
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#include "talk/base/base64.h"
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#include "talk/base/common.h"
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static const char kPad = '=';
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static const unsigned char pd = 0xFD; // Padding
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static const unsigned char sp = 0xFE; // Whitespace
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static const unsigned char il = 0xFF; // Illegal base64 character
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const char Base64::Base64Table[] =
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// 0000000000111111111122222222223333333333444444444455555555556666
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// 0123456789012345678901234567890123456789012345678901234567890123
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"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
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// Decode Table gives the index of any valid base64 character in the
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// 65 == A, 97 == a, 48 == 0, 43 == +, 47 == /
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const unsigned char Base64::DecodeTable[] = {
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// 0 1 2 3 4 5 6 7 8 9
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il,il,il,il,il,il,il,il,il,sp, // 0 - 9
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sp,sp,sp,sp,il,il,il,il,il,il, // 10 - 19
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il,il,il,il,il,il,il,il,il,il, // 20 - 29
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il,il,sp,il,il,il,il,il,il,il, // 30 - 39
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il,il,il,62,il,il,il,63,52,53, // 40 - 49
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54,55,56,57,58,59,60,61,il,il, // 50 - 59
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il,pd,il,il,il, 0, 1, 2, 3, 4, // 60 - 69
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5, 6, 7, 8, 9,10,11,12,13,14, // 70 - 79
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15,16,17,18,19,20,21,22,23,24, // 80 - 89
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25,il,il,il,il,il,il,26,27,28, // 90 - 99
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29,30,31,32,33,34,35,36,37,38, // 100 - 109
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39,40,41,42,43,44,45,46,47,48, // 110 - 119
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49,50,51,il,il,il,il,il,il,il, // 120 - 129
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il,il,il,il,il,il,il,il,il,il, // 130 - 139
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il,il,il,il,il,il,il,il,il,il, // 140 - 149
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il,il,il,il,il,il,il,il,il,il, // 150 - 159
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il,il,il,il,il,il,il,il,il,il, // 160 - 169
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il,il,il,il,il,il,il,il,il,il, // 170 - 179
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il,il,il,il,il,il,il,il,il,il, // 180 - 189
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il,il,il,il,il,il,il,il,il,il, // 190 - 199
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il,il,il,il,il,il,il,il,il,il, // 200 - 209
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il,il,il,il,il,il,il,il,il,il, // 210 - 219
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il,il,il,il,il,il,il,il,il,il, // 220 - 229
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il,il,il,il,il,il,il,il,il,il, // 230 - 239
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il,il,il,il,il,il,il,il,il,il, // 240 - 249
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il,il,il,il,il,il // 250 - 255
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bool Base64::IsBase64Char(char ch) {
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return (('A' <= ch) && (ch <= 'Z')) ||
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(('a' <= ch) && (ch <= 'z')) ||
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(('0' <= ch) && (ch <= '9')) ||
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(ch == '+') || (ch == '/');
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bool Base64::IsBase64Encoded(const std::string& str) {
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for (size_t i = 0; i < str.size(); ++i) {
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if (!IsBase64Char(str.at(i)))
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void Base64::EncodeFromArray(const void* data, size_t len, string* result) {
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ASSERT(NULL != result);
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result->reserve(((len + 2) / 3) * 4);
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const unsigned char* byte_data = static_cast<const unsigned char*>(data);
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c = (byte_data[i] >> 2) & 0x3f;
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result->push_back(Base64Table[c]);
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c = (byte_data[i] << 4) & 0x3f;
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c |= (byte_data[i] >> 4) & 0x0f;
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result->push_back(Base64Table[c]);
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c = (byte_data[i] << 2) & 0x3f;
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c |= (byte_data[i] >> 6) & 0x03;
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result->push_back(Base64Table[c]);
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result->push_back(kPad);
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c = byte_data[i] & 0x3f;
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result->push_back(Base64Table[c]);
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result->push_back(kPad);
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size_t Base64::GetNextQuantum(DecodeFlags parse_flags, bool illegal_pads,
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const char* data, size_t len, size_t* dpos,
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unsigned char qbuf[4], bool* padded)
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size_t byte_len = 0, pad_len = 0, pad_start = 0;
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for (; (byte_len < 4) && (*dpos < len); ++*dpos) {
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qbuf[byte_len] = DecodeTable[static_cast<unsigned char>(data[*dpos])];
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if ((il == qbuf[byte_len]) || (illegal_pads && (pd == qbuf[byte_len]))) {
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if (parse_flags != DO_PARSE_ANY)
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// Ignore illegal characters
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} else if (sp == qbuf[byte_len]) {
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if (parse_flags == DO_PARSE_STRICT)
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} else if (pd == qbuf[byte_len]) {
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if (parse_flags != DO_PARSE_ANY)
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// Ignore unexpected padding
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} else if (byte_len + pad_len >= 4) {
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if (parse_flags != DO_PARSE_ANY)
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if (1 == ++pad_len) {
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if (parse_flags != DO_PARSE_ANY)
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// Ignore pads which are followed by data
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for (size_t i = byte_len; i < 4; ++i) {
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if (4 == byte_len + pad_len) {
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// Roll back illegal padding
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bool Base64::DecodeFromArray(const char* data, size_t len, DecodeFlags flags,
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string* result, size_t* data_used) {
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return DecodeFromArrayTemplate<string>(data, len, flags, result, data_used);
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bool Base64::DecodeFromArray(const char* data, size_t len, DecodeFlags flags,
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vector<char>* result, size_t* data_used) {
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return DecodeFromArrayTemplate<vector<char> >(data, len, flags, result,
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bool Base64::DecodeFromArrayTemplate(const char* data, size_t len,
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DecodeFlags flags, T* result,
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ASSERT(NULL != result);
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ASSERT(flags <= (DO_PARSE_MASK | DO_PAD_MASK | DO_TERM_MASK));
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const DecodeFlags parse_flags = flags & DO_PARSE_MASK;
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const DecodeFlags pad_flags = flags & DO_PAD_MASK;
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const DecodeFlags term_flags = flags & DO_TERM_MASK;
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ASSERT(0 != parse_flags);
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ASSERT(0 != pad_flags);
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ASSERT(0 != term_flags);
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result->reserve(len);
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bool success = true, padded;
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unsigned char c, qbuf[4];
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size_t qlen = GetNextQuantum(parse_flags, (DO_PAD_NO == pad_flags),
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data, len, &dpos, qbuf, &padded);
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c = (qbuf[0] << 2) | ((qbuf[1] >> 4) & 0x3);
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result->push_back(c);
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c = ((qbuf[1] << 4) & 0xf0) | ((qbuf[2] >> 2) & 0xf);
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result->push_back(c);
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c = ((qbuf[2] << 6) & 0xc0) | qbuf[3];
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result->push_back(c);
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if ((DO_TERM_ANY != term_flags) && (0 != c)) {
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success = false; // unused bits
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if ((DO_PAD_YES == pad_flags) && !padded) {
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success = false; // expected padding
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if ((DO_TERM_BUFFER == term_flags) && (dpos != len)) {
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success = false; // unused chars
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} // namespace talk_base