scummvm/backends/networking/sdl_net/reader.cpp

/* ScummVM - Graphic Adventure Engine
*
* ScummVM is the legal property of its developers, whose names
* are too numerous to list here. Please refer to the COPYRIGHT
* file distributed with this source distribution.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
*/

#include "backends/networking/sdl_net/reader.h"
#include "backends/fs/fs-factory.h"
#include "backends/networking/sdl_net/localwebserver.h"
#include "common/memstream.h"
#include "common/stream.h"

namespace Networking {

Reader::Reader() {
	_state = RS_NONE;
	_content = nullptr;
	_bytesLeft = 0;

	_window = nullptr;
	_windowUsed = 0;
	_windowSize = 0;

	_headers = "";
	_firstBlock = true;

	_contentLength = 0;
	_availableBytes = 0;
	_isBadRequest = false;
	_allContentRead = false;
}

Reader::~Reader() {
	cleanup();
}

Reader &Reader::operator=(Reader &r) {
	if (this == &r) return *this;
	cleanup();

	_state = r._state;
	_content = r._content;
	_bytesLeft = r._bytesLeft;
	r._state = RS_NONE;

	_window = r._window;
	_windowUsed = r._windowUsed;
	_windowSize = r._windowSize;
	r._window = nullptr;

	_headers = r._headers;
	_method = r._method;
	_path = r._path;
	_query = r._query;
	_anchor = r._anchor;
	_queryParameters = r._queryParameters;
	_contentLength = r._contentLength;
	_boundary = r._boundary;
	_availableBytes = r._availableBytes;
	_firstBlock = r._firstBlock;
	_isBadRequest = r._isBadRequest;
	_allContentRead = r._allContentRead;

	return *this;
}

void Reader::cleanup() {
	//_content is not to be freed, it's not owned by Reader

	if (_window != nullptr) freeWindow();
}

bool Reader::readAndHandleFirstHeaders() {
	Common::String boundary = "\r\n\r\n";
	if (_window == nullptr) {
		makeWindow(boundary.size());
		_headers = "";
	}

	while (readOneByteInString(_headers, boundary)) {
		if (!bytesLeft()) return false;
	}
	handleFirstHeaders(_headers);

	freeWindow();
	_state = RS_READING_CONTENT;
	return true;
}

bool Reader::readBlockHeadersIntoStream(Common::WriteStream *stream) {
	Common::String boundary = "\r\n\r\n";
	if (_window == nullptr) makeWindow(boundary.size());

	while (readOneByteInStream(stream, boundary)) {
		if (!bytesLeft()) return false;
	}
	if (stream) stream->flush();

	freeWindow();
	_state = RS_READING_CONTENT;
	return true;
}

namespace {
void readFromThatUntilLineEnd(const char *cstr, Common::String needle, Common::String &result) {
	const char *position = strstr(cstr, needle.c_str());

	if (position) {
		char c;
		for (const char *i = position + needle.size(); c = *i, c != 0; ++i) {
			if (c == '\n' || c == '\r') break;
			result += c;
		}
	}
}
}

void Reader::handleFirstHeaders(Common::String headers) {
	if (!_boundary.empty()) {
		warning("handleFirstHeaders() called when first headers were already handled");
		return;
	}

	//parse method, path, query, fragment
	parseFirstLine(headers);

	//find boundary
	_boundary = "";
	readFromThatUntilLineEnd(headers.c_str(), "boundary=", _boundary);

	//find content length
	Common::String contentLength = "";
	readFromThatUntilLineEnd(headers.c_str(), "Content-Length: ", contentLength);
	_contentLength = contentLength.asUint64();
	_availableBytes = _contentLength;
}

void Reader::parseFirstLine(const Common::String &headers) {
	uint32 headersSize = headers.size();
	bool bad = false;

	const uint32 SUSPICIOUS_HEADERS_SIZE = 128 * 1024;
	if (headersSize > SUSPICIOUS_HEADERS_SIZE) bad = true;

	if (!bad) {
		if (headersSize > 0) {
			const char *cstr = headers.c_str();
			const char *position = strstr(cstr, "\r\n");
			if (position) { //we have at least one line - and we want the first one
							//"<METHOD> <path> HTTP/<VERSION>\r\n"
				Common::String method, path, http, buf;
				uint32 length = position - cstr;
				if (headersSize > length) headersSize = length;
				for (uint32 i = 0; i < headersSize; ++i) {
					if (headers[i] != ' ') buf += headers[i];
					if (headers[i] == ' ' || i == headersSize - 1) {
						if (method == "") method = buf;
						else if (path == "") path = buf;
						else if (http == "") http = buf;
						else {
							bad = true;
							break;
						}
						buf = "";
					}
				}

				//check that method is supported
				if (method != "GET" && method != "PUT" && method != "POST") bad = true;

				//check that HTTP/<VERSION> is OK
				if (!http.hasPrefix("HTTP/")) bad = true;

				_method = method;
				parsePathQueryAndAnchor(path);
			}
		}
	}

	if (bad) _isBadRequest = true;
}

void Reader::parsePathQueryAndAnchor(Common::String path) {
	//<path>[?query][#anchor]
	bool readingPath = true;
	bool readingQuery = false;
	_path = "";
	_query = "";
	_anchor = "";
	for (uint32 i = 0; i < path.size(); ++i) {
		if (readingPath) {
			if (path[i] == '?') {
				readingPath = false;
				readingQuery = true;
			} else _path += path[i];
		} else if (readingQuery) {
			if (path[i] == '#') {
				readingQuery = false;
			} else _query += path[i];
		} else _anchor += path[i];
	}

	parseQueryParameters();
}

void Reader::parseQueryParameters() {
	Common::String key = "";
	Common::String value = "";
	bool readingKey = true;
	for (uint32 i = 0; i < _query.size(); ++i) {
		if (readingKey) {
			if (_query[i] == '=') {
				readingKey = false;
				value = "";
			} else key += _query[i];
		} else {
			if (_query[i] == '&') {				
				if (_queryParameters.contains(key)) warning("Query parameter \"%s\" is already set!", key.c_str());
				else _queryParameters[key] = LocalWebserver::urlDecode(value);
				readingKey = true;
				key = "";
			} else value += _query[i];
		}
	}

	if (!key.empty()) {
		if (_queryParameters.contains(key)) warning("Query parameter \"%s\" is already set!", key.c_str());
		else _queryParameters[key] = LocalWebserver::urlDecode(value);
	}
}

bool Reader::readContentIntoStream(Common::WriteStream *stream) {
	Common::String boundary = "--" + _boundary;
	if (!_firstBlock) boundary = "\r\n" + boundary;
	if (_boundary.empty()) boundary = "\r\n";
	if (_window == nullptr) makeWindow(boundary.size());

	while (readOneByteInStream(stream, boundary)) {
		if (!bytesLeft()) return false;
	}

	_firstBlock = false;
	if (stream) stream->flush();

	freeWindow();
	_state = RS_READING_HEADERS;
	return true;
}

void Reader::makeWindow(uint32 size) {
	freeWindow();

	_window = new byte[size];
	_windowUsed = 0;
	_windowSize = size;
}

void Reader::freeWindow() {
	delete[] _window;
	_window = nullptr;
	_windowUsed = _windowSize = 0;
}

bool Reader::readOneByteInStream(Common::WriteStream *stream, const Common::String &boundary) {
	byte b = readOne();
	_window[_windowUsed++] = b;
	if (_windowUsed < _windowSize) return true;

	//when window is filled, check whether that's the boundary
	if (Common::String((char *)_window, _windowSize) == boundary)
		return false;

	//if not, add the first byte of the window to the string
	if (stream) stream->writeByte(_window[0]);
	for (uint32 i = 1; i < _windowSize; ++i)
		_window[i - 1] = _window[i];
	--_windowUsed;
	return true;
}

bool Reader::readOneByteInString(Common::String &buffer, const Common::String &boundary) {
	byte b = readOne();
	_window[_windowUsed++] = b;
	if (_windowUsed < _windowSize) return true;

	//when window is filled, check whether that's the boundary
	if (Common::String((char *)_window, _windowSize) == boundary)
		return false;

	//if not, add the first byte of the window to the string
	buffer += _window[0];
	for (uint32 i = 1; i < _windowSize; ++i)
		_window[i - 1] = _window[i];
	--_windowUsed;
	return true;
}

byte Reader::readOne() {
	byte b;
	_content->read(&b, 1);
	--_availableBytes;
	--_bytesLeft;
	return b;
}

/// public

bool Reader::readFirstHeaders() {
	if (_state == RS_NONE) _state = RS_READING_HEADERS;

	if (!bytesLeft()) return false;

	if (_state == RS_READING_HEADERS)
		return readAndHandleFirstHeaders();

	warning("Reader::readFirstHeaders(): bad state");
	return false;
}

bool Reader::readFirstContent(Common::WriteStream *stream) {
	if (_state != RS_READING_CONTENT) {
		warning("Reader::readFirstContent(): bad state");
		return false;
	}

	// no difference, actually
	return readBlockContent(stream);
}

bool Reader::readBlockHeaders(Common::WriteStream *stream) {
	if (_state != RS_READING_HEADERS) {
		warning("Reader::readBlockHeaders(): bad state");
		return false;
	}

	if (!bytesLeft()) return false;

	return readBlockHeadersIntoStream(stream);
}

bool Reader::readBlockContent(Common::WriteStream *stream) {
	if (_state != RS_READING_CONTENT) {
		warning("Reader::readBlockContent(): bad state");
		return false;
	}

	if (!bytesLeft()) return false;

	if (!readContentIntoStream(stream))
		return false;

	if (_availableBytes >= 2) {
		Common::String bts;
		bts += readOne();
		bts += readOne();
		if (bts == "--") _allContentRead = true;
		else if (bts != "\r\n")
			warning("strange bytes: \"%s\"", bts.c_str());
	} else {
		warning("strange ending");
		_allContentRead = true;
	}

	return true;
}

uint32 Reader::bytesLeft() { return _bytesLeft; }

void Reader::setContent(Common::MemoryReadWriteStream *stream) {
	_content = stream;
	_bytesLeft = stream->size() - stream->pos();
}

bool Reader::badRequest() const { return _isBadRequest; }

bool Reader::noMoreContent() const { return _allContentRead; }

Common::String Reader::headers() const { return _headers; }

Common::String Reader::method() const { return _method; }

Common::String Reader::path() const { return _path; }

Common::String Reader::query() const { return _query; }

Common::String Reader::queryParameter(Common::String name) const { return _queryParameters[name]; }

Common::String Reader::anchor() const { return _anchor; }

} // End of namespace Networking