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/**
* Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
* SPDX-License-Identifier: Apache-2.0.
*/
#include <aws/core/utils/crypto/CryptoBuf.h>
namespace Aws
{
namespace Utils
{
namespace Crypto
{
SymmetricCryptoBufSrc::SymmetricCryptoBufSrc(Aws::IStream& stream, SymmetricCipher& cipher, CipherMode cipherMode, size_t bufferSize)
:
m_isBuf(PUT_BACK_SIZE), m_cipher(cipher), m_stream(stream), m_cipherMode(cipherMode), m_isFinalized(false),
m_bufferSize(bufferSize), m_putBack(PUT_BACK_SIZE)
{
char* end = reinterpret_cast<char*>(m_isBuf.GetUnderlyingData() + m_isBuf.GetLength());
setg(end, end, end);
}
SymmetricCryptoBufSrc::pos_type SymmetricCryptoBufSrc::seekoff(off_type off, std::ios_base::seekdir dir, std::ios_base::openmode which)
{
if(which == std::ios_base::in)
{
auto curPos = m_stream.tellg();
//error on seek we may have read past the end already. Try resetting and seeking to the end first
if (curPos == pos_type(-1))
{
m_stream.clear();
m_stream.seekg(0, std::ios_base::end);
curPos = m_stream.tellg();
}
auto absPosition = ComputeAbsSeekPosition(off, dir, curPos);
size_t seekTo = static_cast<size_t>(absPosition);
size_t index = static_cast<size_t>(curPos);
if(index == seekTo)
{
return curPos;
}
else if (seekTo < index)
{
m_cipher.Reset();
m_stream.clear();
m_stream.seekg(0);
m_isFinalized = false;
index = 0;
}
CryptoBuffer cryptoBuffer;
while (m_cipher && index < seekTo && !m_isFinalized)
{
size_t max_read = std::min<size_t>(static_cast<size_t>(seekTo - index), m_bufferSize);
Aws::Utils::Array<char> buf(max_read);
size_t readSize(0);
if(m_stream)
{
m_stream.read(buf.GetUnderlyingData(), max_read);
readSize = static_cast<size_t>(m_stream.gcount());
}
if (readSize > 0)
{
if (m_cipherMode == CipherMode::Encrypt)
{
cryptoBuffer = m_cipher.EncryptBuffer(CryptoBuffer(reinterpret_cast<unsigned char*>(buf.GetUnderlyingData()), readSize));
}
else
{
cryptoBuffer = m_cipher.DecryptBuffer(CryptoBuffer(reinterpret_cast<unsigned char*>(buf.GetUnderlyingData()), readSize));
}
}
else
{
if (m_cipherMode == CipherMode::Encrypt)
{
cryptoBuffer = m_cipher.FinalizeEncryption();
}
else
{
cryptoBuffer = m_cipher.FinalizeDecryption();
}
m_isFinalized = true;
}
index += cryptoBuffer.GetLength();
}
if (cryptoBuffer.GetLength() && m_cipher)
{
CryptoBuffer putBackArea(m_putBack);
m_isBuf = CryptoBuffer({&putBackArea, &cryptoBuffer});
//in the very unlikely case that the cipher had less output than the source stream.
assert(seekTo <= index);
size_t newBufferPos = index > seekTo ? cryptoBuffer.GetLength() - (index - seekTo) : cryptoBuffer.GetLength();
char* baseBufPtr = reinterpret_cast<char*>(m_isBuf.GetUnderlyingData());
setg(baseBufPtr, baseBufPtr + m_putBack + newBufferPos, baseBufPtr + m_isBuf.GetLength());
return pos_type(seekTo);
}
else if (seekTo == 0)
{
m_isBuf = CryptoBuffer(m_putBack);
char* end = reinterpret_cast<char*>(m_isBuf.GetUnderlyingData() + m_isBuf.GetLength());
setg(end, end, end);
return pos_type(seekTo);
}
}
return pos_type(off_type(-1));
}
SymmetricCryptoBufSrc::pos_type SymmetricCryptoBufSrc::seekpos(pos_type pos, std::ios_base::openmode which)
{
return seekoff(pos, std::ios_base::beg, which);
}
SymmetricCryptoBufSrc::int_type SymmetricCryptoBufSrc::underflow()
{
if (!m_cipher || (m_isFinalized && gptr() >= egptr()))
{
return traits_type::eof();
}
if (gptr() < egptr())
{
return traits_type::to_int_type(*gptr());
}
char* baseBufPtr = reinterpret_cast<char*>(m_isBuf.GetUnderlyingData());
CryptoBuffer putBackArea(m_putBack);
//eback is properly set after the first fill. So this guarantees we are on the second or later fill.
if (eback() == baseBufPtr)
{
//just fill in the last bit of the previous buffer into the put back area so that it has some data in it
memcpy(putBackArea.GetUnderlyingData(), egptr() - m_putBack, m_putBack);
}
CryptoBuffer newDataBuf;
while(!newDataBuf.GetLength() && !m_isFinalized)
{
Aws::Utils::Array<char> buf(m_bufferSize);
m_stream.read(buf.GetUnderlyingData(), m_bufferSize);
size_t readSize = static_cast<size_t>(m_stream.gcount());
if (readSize > 0)
{
if (m_cipherMode == CipherMode::Encrypt)
{
newDataBuf = m_cipher.EncryptBuffer(CryptoBuffer(reinterpret_cast<unsigned char*>(buf.GetUnderlyingData()), readSize));
}
else
{
newDataBuf = m_cipher.DecryptBuffer(CryptoBuffer(reinterpret_cast<unsigned char*>(buf.GetUnderlyingData()), readSize));
}
}
else
{
if (m_cipherMode == CipherMode::Encrypt)
{
newDataBuf = m_cipher.FinalizeEncryption();
}
else
{
newDataBuf = m_cipher.FinalizeDecryption();
}
m_isFinalized = true;
}
}
if(newDataBuf.GetLength() > 0)
{
m_isBuf = CryptoBuffer({&putBackArea, &newDataBuf});
baseBufPtr = reinterpret_cast<char*>(m_isBuf.GetUnderlyingData());
setg(baseBufPtr, baseBufPtr + m_putBack, baseBufPtr + m_isBuf.GetLength());
return traits_type::to_int_type(*gptr());
}
return traits_type::eof();
}
SymmetricCryptoBufSrc::off_type SymmetricCryptoBufSrc::ComputeAbsSeekPosition(off_type pos, std::ios_base::seekdir dir, std::fpos<FPOS_TYPE> curPos)
{
switch(dir)
{
case std::ios_base::beg:
return pos;
case std::ios_base::cur:
return m_stream.tellg() + pos;
case std::ios_base::end:
{
off_type absPos = m_stream.seekg(0, std::ios_base::end).tellg() - pos;
m_stream.seekg(curPos);
return absPos;
}
default:
assert(0);
return off_type(-1);
}
}
void SymmetricCryptoBufSrc::FinalizeCipher()
{
if(m_cipher && !m_isFinalized)
{
if(m_cipherMode == CipherMode::Encrypt)
{
m_cipher.FinalizeEncryption();
}
else
{
m_cipher.FinalizeDecryption();
}
}
}
SymmetricCryptoBufSink::SymmetricCryptoBufSink(Aws::OStream& stream, SymmetricCipher& cipher, CipherMode cipherMode, size_t bufferSize, int16_t blockOffset)
:
m_osBuf(bufferSize), m_cipher(cipher), m_stream(stream), m_cipherMode(cipherMode), m_isFinalized(false), m_blockOffset(blockOffset)
{
assert(m_blockOffset < 16 && m_blockOffset >= 0);
char* outputBase = reinterpret_cast<char*>(m_osBuf.GetUnderlyingData());
setp(outputBase, outputBase + bufferSize - 1);
}
SymmetricCryptoBufSink::~SymmetricCryptoBufSink()
{
FinalizeCiphersAndFlushSink();
}
void SymmetricCryptoBufSink::FinalizeCiphersAndFlushSink()
{
if(m_cipher && !m_isFinalized)
{
writeOutput(true);
}
}
bool SymmetricCryptoBufSink::writeOutput(bool finalize)
{
if(!m_isFinalized)
{
CryptoBuffer cryptoBuf;
if (pptr() > pbase())
{
if (m_cipherMode == CipherMode::Encrypt)
{
cryptoBuf = m_cipher.EncryptBuffer(CryptoBuffer(reinterpret_cast<unsigned char*>(pbase()), pptr() - pbase()));
}
else
{
cryptoBuf = m_cipher.DecryptBuffer(CryptoBuffer(reinterpret_cast<unsigned char*>(pbase()), pptr() - pbase()));
}
pbump(-(static_cast<int>(pptr() - pbase())));
}
if(finalize)
{
CryptoBuffer finalBuffer;
if (m_cipherMode == CipherMode::Encrypt)
{
finalBuffer = m_cipher.FinalizeEncryption();
}
else
{
finalBuffer = m_cipher.FinalizeDecryption();
}
if(cryptoBuf.GetLength())
{
cryptoBuf = CryptoBuffer({&cryptoBuf, &finalBuffer});
}
else
{
cryptoBuf = std::move(finalBuffer);
}
m_isFinalized = true;
}
if (m_cipher)
{
if(cryptoBuf.GetLength())
{
//allow mid block decryption. We have to decrypt it, but we don't have to write it to the stream.
//the assumption here is that tellp() will always be 0 or >= 16 bytes. The block offset should only
//be the offset of the first block read.
size_t len = cryptoBuf.GetLength();
size_t blockOffset = m_stream.tellp() > m_blockOffset ? 0 : m_blockOffset;
if (len > blockOffset)
{
m_stream.write(reinterpret_cast<char*>(cryptoBuf.GetUnderlyingData() + blockOffset), len - blockOffset);
m_blockOffset = 0;
}
else
{
m_blockOffset -= static_cast<int16_t>(len);
}
}
return true;
}
}
return false;
}
SymmetricCryptoBufSink::int_type SymmetricCryptoBufSink::overflow(int_type ch)
{
if(m_cipher && m_stream)
{
if(ch != traits_type::eof())
{
*pptr() = (char)ch;
pbump(1);
}
if(writeOutput(ch == traits_type::eof()))
{
return ch;
}
}
return traits_type::eof();
}
int SymmetricCryptoBufSink::sync()
{
if(m_cipher && m_stream)
{
return writeOutput(false) ? 0 : -1;
}
return -1;
}
}
}
}
|
