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/**
* Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
* SPDX-License-Identifier: Apache-2.0.
*/
#include <aws/core/utils/base64/Base64.h>
#include <cstring>
using namespace Aws::Utils::Base64;
static const uint8_t SENTINEL_VALUE = 255;
static const char BASE64_ENCODING_TABLE_MIME[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
namespace Aws
{
namespace Utils
{
namespace Base64
{
Base64::Base64(const char *encodingTable)
{
if(encodingTable == nullptr)
{
encodingTable = BASE64_ENCODING_TABLE_MIME;
}
size_t encodingTableLength = strlen(encodingTable);
if(encodingTableLength != 64)
{
encodingTable = BASE64_ENCODING_TABLE_MIME;
encodingTableLength = 64;
}
memcpy(m_mimeBase64EncodingTable, encodingTable, encodingTableLength);
memset((void *)m_mimeBase64DecodingTable, 0, 256);
for(uint32_t i = 0; i < encodingTableLength; ++i)
{
uint32_t index = static_cast<uint32_t>(m_mimeBase64EncodingTable[i]);
m_mimeBase64DecodingTable[index] = static_cast<uint8_t>(i);
}
m_mimeBase64DecodingTable[(uint32_t)'='] = SENTINEL_VALUE;
}
Aws::String Base64::Encode(const Aws::Utils::ByteBuffer& buffer) const
{
size_t bufferLength = buffer.GetLength();
size_t blockCount = (bufferLength + 2) / 3;
size_t remainderCount = (bufferLength % 3);
Aws::String outputString;
outputString.reserve(CalculateBase64EncodedLength(buffer));
for(size_t i = 0; i < bufferLength; i += 3 )
{
uint32_t block = buffer[ i ];
block <<= 8;
if (i + 1 < bufferLength)
{
block = block | buffer[ i + 1 ];
}
block <<= 8;
if (i + 2 < bufferLength)
{
block = block | buffer[ i + 2 ];
}
outputString.push_back(m_mimeBase64EncodingTable[(block >> 18) & 0x3F]);
outputString.push_back(m_mimeBase64EncodingTable[(block >> 12) & 0x3F]);
outputString.push_back(m_mimeBase64EncodingTable[(block >> 6) & 0x3F]);
outputString.push_back(m_mimeBase64EncodingTable[block & 0x3F]);
}
if(remainderCount > 0)
{
outputString[blockCount * 4 - 1] = '=';
if(remainderCount == 1)
{
outputString[blockCount * 4 - 2] = '=';
}
}
return outputString;
}
Aws::Utils::ByteBuffer Base64::Decode(const Aws::String& str) const
{
size_t decodedLength = CalculateBase64DecodedLength(str);
Aws::Utils::ByteBuffer buffer(decodedLength);
const char* rawString = str.c_str();
size_t blockCount = str.length() / 4;
for(size_t i = 0; i < blockCount; ++i)
{
size_t stringIndex = i * 4;
uint32_t value1 = m_mimeBase64DecodingTable[uint32_t(rawString[stringIndex])];
uint32_t value2 = m_mimeBase64DecodingTable[uint32_t(rawString[++stringIndex])];
uint32_t value3 = m_mimeBase64DecodingTable[uint32_t(rawString[++stringIndex])];
uint32_t value4 = m_mimeBase64DecodingTable[uint32_t(rawString[++stringIndex])];
size_t bufferIndex = i * 3;
buffer[bufferIndex] = static_cast<uint8_t>((value1 << 2) | ((value2 >> 4) & 0x03));
if(value3 != SENTINEL_VALUE)
{
buffer[++bufferIndex] = static_cast<uint8_t>(((value2 << 4) & 0xF0) | ((value3 >> 2) & 0x0F));
if(value4 != SENTINEL_VALUE)
{
buffer[++bufferIndex] = static_cast<uint8_t>((value3 & 0x03) << 6 | value4);
}
}
}
return buffer;
}
size_t Base64::CalculateBase64DecodedLength(const Aws::String& b64input)
{
const size_t len = b64input.length();
if(len < 2)
{
return 0;
}
size_t padding = 0;
if (b64input[len - 1] == '=' && b64input[len - 2] == '=') //last two chars are =
padding = 2;
else if (b64input[len - 1] == '=') //last char is =
padding = 1;
return (len * 3 / 4 - padding);
}
size_t Base64::CalculateBase64EncodedLength(const Aws::Utils::ByteBuffer& buffer)
{
return 4 * ((buffer.GetLength() + 2) / 3);
}
} // namespace Base64
} // namespace Utils
} // namespace Aws
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