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WebsocketInputStreambuf.cpp
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110 lines (95 loc) · 4.1 KB
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#include "WebsocketInputStreambuf.hpp"
namespace httpsserver {
/**
* @brief Create a Web Socket input record streambuf
* @param [in] socket The socket we will be reading from.
* @param [in] dataLength The size of a record.
* @param [in] bufferSize The size of the buffer we wish to allocate to hold data.
*/
WebsocketInputStreambuf::WebsocketInputStreambuf(
ConnectionContext *con,
size_t dataLength,
uint8_t *pMask,
size_t bufferSize
) {
_con = con; // The socket we will be reading from
_dataLength = dataLength; // The size of the record we wish to read.
_pMask = pMask;
_bufferSize = bufferSize; // The size of the buffer used to hold data
_sizeRead = 0; // The size of data read from the socket
_buffer = new char[bufferSize]; // Create the buffer used to hold the data read from the socket.
setg(_buffer, _buffer, _buffer); // Set the initial get buffer pointers to no data.
}
WebsocketInputStreambuf::~WebsocketInputStreambuf() {
//FIXME: Call order incorrect? discard() uses _buffer
delete[] _buffer;
discard();
}
/**
* @brief Discard data for the record that has not yet been read.
*
* We are working on a logical fixed length record in a socket stream. This means that we know in advance
* how big the record should be. If we have read some data from the stream and no longer wish to consume
* any further, we have to discard the remaining bytes in the stream before we can get to process the
* next record. This function discards the remainder of the data.
*
* For example, if our record size is 1000 bytes and we have read 700 bytes and determine that we no
* longer need to continue, we can't just stop. There are still 300 bytes in the socket stream that
* need to be consumed/discarded before we can move on to the next record.
*/
void WebsocketInputStreambuf::discard() {
uint8_t byte;
HTTPS_DLOGINT("[ ] WebsocketContext >> discard: Discarding bytes: ", _dataLength - _sizeRead);
while(_sizeRead < _dataLength) {
_con->readBuffer(&byte, 1);
_sizeRead++;
}
HTTPS_DLOG("[ ] WebsocketContext << discard");
} // WebsocketInputStreambuf::discard
/**
* @brief Get the size of the expected record.
* @return The size of the expected record.
*/
size_t WebsocketInputStreambuf::getRecordSize() {
return _dataLength;
} // WebsocketInputStreambuf::getRecordSize
/**
* @brief Handle the request to read data from the stream but we need more data from the source.
*
*/
WebsocketInputStreambuf::int_type WebsocketInputStreambuf::underflow() {
HTTPS_DLOG("[ ] WebSocketInputStreambuf >> underflow");
// If we have already read as many bytes as our record definition says we should read
// then don't attempt to ready any further.
if (_sizeRead >= getRecordSize()) {
HTTPS_DLOG("[ ] WebSocketInputStreambuf << underflow: Already read maximum");
return EOF;
}
// We wish to refill the buffer. We want to read data from the socket. We want to read either
// the size of the buffer to fill it or the maximum number of bytes remaining to be read.
// We will choose which ever is smaller as the number of bytes to read into the buffer.
int remainingBytes = getRecordSize()-_sizeRead;
size_t sizeToRead;
if (remainingBytes < _bufferSize) {
sizeToRead = remainingBytes;
} else {
sizeToRead = _bufferSize;
}
HTTPS_DLOGINT("[ ] WebSocketInputRecordStreambuf - getting next buffer of data; size request: ", sizeToRead);
int bytesRead = _con->readBuffer((uint8_t*)_buffer, sizeToRead);
if (bytesRead == 0) {
HTTPS_DLOG("[ ] WebSocketInputRecordStreambuf << underflow: Read 0 bytes");
return EOF;
}
// If the WebSocket frame shows that we have a mask bit set then we have to unmask the data.
if (_pMask != nullptr) {
for (int i=0; i<bytesRead; i++) {
_buffer[i] = _buffer[i] ^ _pMask[(_sizeRead+i)%4];
}
}
_sizeRead += bytesRead; // Increase the count of number of bytes actually read from the source.
setg(_buffer, _buffer, _buffer + bytesRead); // Change the buffer pointers to reflect the new data read.
HTTPS_DLOGINT("[ ] WebSocketInputRecordStreambuf << underflow - got more bytes: ", bytesRead);
return traits_type::to_int_type(*gptr());
} // underflow
}