ZaStoGram_desktop/Telegram/SourceFiles/mtproto/proxy/wss/socket.h

/*
This file is part of Telegram Desktop,
the official desktop application for the Telegram messaging service.

For license and copyright information please follow this link:
https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
*/
#pragma once

#include "mtproto/transport/details/mtproto_abstract_socket.h"

#include <QtNetwork/QSslSocket>

#include <optional>

namespace MTP::details {

struct WssRoute {
	QString relayHost;
	QString relayHostFallback; // retried once if relayHost fails (e.g. domain)
	int relayPort = 443;
	QString domain;
	QString path;
	bool tunnel = false; // path gets ?dst=<datacenter address> on connect
	// Position in the Cloudflare front catalog (kwsN.<front domain>), or -1.
	// The front forwards the WebSocket to Telegram Web itself, so unlike the
	// tunnel it needs no destination and carries the byte stream as is.
	int cdnSlot = -1;
	int cdnDcId = 0;
	// Failure counting and suppression key when it must not follow the
	// domain: every front domain of a DC shares one health record.
	QString healthDomain;
	// Network the route was chosen on (see WssTrackNetwork): its failures
	// count against that network only, even when reported after a switch.
	bool metered = false;
};

// A phone's hotspot (Windows marks Android tethering as metered) reaches
// Telegram through the mobile operator, whose blocks differ from the home
// provider's. Relay health, suppression and the IP/DNS preference are kept
// separately for metered and unmetered networks. Call on the main thread.
void WssTrackNetwork();

// A passive snapshot for user-facing media diagnostics. It observes the
// relay preference and health maps, but never changes connection admission,
// retry timing or the lifetime of a live session.
struct WssRouteDiagnostics {
	std::optional<WssRoute> route;
	QString selectedRelayHost;
	bool custom = false;
	bool prefersFallback = false;
	bool suppressed = false;
	int consecutiveFailures = 0;
	crl::time suppressedFor = 0;
};

// Official MTProto-over-WebSocket route for a data center, mirroring the
// web.telegram.org transport; while the DC's relay is suppressed, the
// Cloudflare fronts of tg-ws-proxy (kwsN.<front domain>), then the tunnel.
// With everything suppressed the fronts stay the floor: the direct TCP this
// used to fall back to is what the blocking networks close.
//
// Every production DC (1-5) has a working web relay, but the ingress addresses are NOT interchangeable: each one serves
// only its own datacenters. Reaching the wrong ingress answers 302 (with an
// X-Redirect-Host header naming the right relay) or accepts the connection
// and stays silent - which is where the widespread "web sockets exist only
// for DC2/DC4" belief came from. Measured against live relays 2026-08-08.
[[nodiscard]] std::optional<WssRoute> WssOfficialRoute(
	int16 protocolDcId);

// The relay of this DC has not answered on this network yet, or failed since
// it last did, while it is not suppressed. A session then races a Cloudflare
// front (WssFrontRoute) against it instead of waiting for the relay to be
// suppressed first.
[[nodiscard]] bool WssRelayUnproven(int16 protocolDcId);
[[nodiscard]] std::optional<WssRoute> WssFrontRoute(int16 protocolDcId);

// Expert-only user-configured relay (ProxyStealthOptions.wssCustom*), used
// for any DC when set and verified against the configured relay domain.
[[nodiscard]] std::optional<WssRoute> WssCustomRoute(
	const ProxyStealthOptions &stealth);

[[nodiscard]] WssRouteDiagnostics WssRouteDiagnosticsForDc(
	const ProxyStealthOptions &stealth,
	int16 protocolDcId);

// The media relay of this DC is suppressed and its files go through the
// Cloudflare tunnel, where every connection freezes after ~16 KB downstream.
// File downloads then use small parts over many short-lived connections.
[[nodiscard]] bool WssMediaTunneled(int dcId);

// A clean, self-contained MTProto-over-WebSocket(-over-TLS) transport. It
// speaks RFC 6455 over a real QSslSocket and carries the obfuscated MTProto
// stream transparently inside binary frames, so the rest of the connection
// stack (obfuscation, protocol negotiation) is unchanged.
class WssSocket final : public AbstractSocket {
public:
	WssSocket(
		not_null<RuntimeEnvironment*> runtime,
		not_null<QThread*> thread,
		const QNetworkProxy &proxy,
		bool protocolForFiles,
		WssRoute route);
	~WssSocket();

	void connectToHost(const QString &address, int port) override;
	bool isGoodStartNonce(bytes::const_span nonce) override;
	void timedOut() override;
	[[nodiscard]] bool takeRotation() override;
	[[nodiscard]] bool plainDcMarker() const override;
	bool isConnected() override;
	bool hasBytesAvailable() override;
	int64 read(bytes::span buffer) override;
	void write(bytes::const_span prefix, bytes::const_span buffer) override;

	int32 debugState() override;
	QString debugPostfix() const override;
	HandshakePhase handshakePhase() const override;
	QString transportName() const override;

private:
	void handleError(int errorCode);
	void connectToRelayHost();
	void onTcpConnected();
	void onEncrypted();
	void onReadyRead();
	void sendHttpUpgrade();
	[[nodiscard]] bool tryFinishUpgrade();
	[[nodiscard]] bool checkUpgradeAccept(const QByteArray &header) const;
	[[nodiscard]] bool retryRefusedUpgrade(const QByteArray &header);
	[[nodiscard]] bool outputDrained() const;
	void noteFrontFailed();
	void parseFrames();
	void sendFrame(quint8 opcode, bytes::const_span data);

	QSslSocket _socket;
	WssRoute _route;
	QString _secWebSocketKey;
	QByteArray _incoming;
	QByteArray _readBuffer;
	bool _upgraded = false;
	bool _usedFallback = false;
	bool _hostFlipped = false;
	QString _currentHost;
	bool _tcpConnected = false;
	qint64 _bytesReceived = 0;
	qint64 _bytesSent = 0;
	bool _tunnelProven = false;
	bool _frontAnswered = false;
	bool _frontProven = false;
	bool _frontFailureNoted = false;
	int _upgradeRetries = 0;
	bool _forFiles = false;
	bool _rotated = false;
	crl::time _openedAt = 0;
	crl::time _upgradedAt = 0;
	crl::time _firstDataAt = 0;
	HandshakePhase _phase = HandshakePhase::None;

};

} // namespace MTP::details