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Schannel: slightly optimize memory-usage for encryption 

Change-Id: I0f4b372ad3a0cd5e6730ed2e23e738fb06b2aad5
Reviewed-by: Timur Pocheptsov <timur.pocheptsov@qt.io>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
bb10
Mårten Nordheim 2019-01-28 15:57:44 +01:00
parent 26ebdeff75
commit c41efe7373
1 changed files with 14 additions and 23 deletions
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37
src/network/ssl/qsslsocket_schannel.cpp
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@ -142,12 +142,9 @@
Medium priority:
- Setting cipher-suites (or ALG_ID)
- People have survived without it in WinRT
- ALPN:
For HTTP2. Note: Windows 8.1 and up ONLY.
Low priority:
- Possibly make RAII wrappers for SecBuffer (which I commonly create QScopeGuards for)
- Perform the '@future' optimization in "transmit()"
*/
@ -1188,23 +1185,21 @@ void QSslSocketBackendPrivate::transmit()
qint64 totalBytesWritten = 0;
qint64 writeBufferSize;
while ((writeBufferSize = writeBuffer.size()) > 0) {
QByteArray plaintext;
const int headerSize = int(streamSizes.cbHeader);
const int trailerSize = int(streamSizes.cbTrailer);
// Try to read 'cbMaximumMessage' bytes from buffer before encrypting.
const int size = int(std::min(writeBufferSize, qint64(streamSizes.cbMaximumMessage)));
QByteArray fullMessage(headerSize + trailerSize + size, Qt::Uninitialized);
{
// Try to read 'cbMaximumMessage' bytes from buffer before encrypting.
int size = int(std::min(writeBufferSize, qint64(streamSizes.cbMaximumMessage)));
plaintext.resize(size);
// Use peek() here instead of read() so we don't lose data if encryption fails.
qint64 copied = writeBuffer.peek(plaintext.data(), size);
qint64 copied = writeBuffer.peek(fullMessage.data() + headerSize, size);
Q_ASSERT(copied == size);
}
QByteArray header(int(streamSizes.cbHeader), '\0');
QByteArray trailer(int(streamSizes.cbTrailer), '\0');
SecBuffer inputBuffers[4]{
// @future[0/1]: optimize by using one container for all fields...
createSecBuffer(header, SECBUFFER_STREAM_HEADER),
createSecBuffer(plaintext, SECBUFFER_DATA),
createSecBuffer(trailer, SECBUFFER_STREAM_TRAILER),
createSecBuffer(fullMessage.data(), headerSize, SECBUFFER_STREAM_HEADER),
createSecBuffer(fullMessage.data() + headerSize, size, SECBUFFER_DATA),
createSecBuffer(fullMessage.data() + headerSize + size, trailerSize, SECBUFFER_STREAM_TRAILER),
createSecBuffer(nullptr, 0, SECBUFFER_EMPTY)
};
SecBufferDesc message{
@ -1220,18 +1215,14 @@ void QSslSocketBackendPrivate::transmit()
return;
}
// Data was encrypted successfully, so we free() what we peek()ed earlier
writeBuffer.free(plaintext.length());
writeBuffer.free(size);
// trailer has been observed to change size, so resize them all (when needed) to be safe
header = header.left(int(inputBuffers[0].cbBuffer));
plaintext = plaintext.left(int(inputBuffers[1].cbBuffer));
trailer = trailer.left(int(inputBuffers[2].cbBuffer));
const qint64 bytesWritten = plainSocket->write(header // @future[1/1]: ...because they need to be merged
+ plaintext
+ trailer);
// The trailer's size is not final, so resize fullMessage to not send trailing junk
fullMessage.resize(inputBuffers[0].cbBuffer + inputBuffers[1].cbBuffer + inputBuffers[2].cbBuffer);
const qint64 bytesWritten = plainSocket->write(fullMessage);
#ifdef QSSLSOCKET_DEBUG
qCDebug(lcSsl) << "Wrote" << bytesWritten << "of total"
<< header.length() + plaintext.length() + trailer.length() << "bytes";
<< fullMessage.length() << "bytes";
#endif
if (bytesWritten >= 0) {
totalBytesWritten += bytesWritten;