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Telegram/SourceFiles/mtproto/details/mtproto_domain_resolver.h

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+/*
+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 "base/weak_ptr.h"
+
+#include <QtCore/QPointer>
+#include <QtNetwork/QNetworkReply>
+#include <optional>
+
+namespace MTP::details {
+
+[[nodiscard]] const std::vector<QString> &DnsDomains();
+[[nodiscard]] QString GenerateDnsRandomPadding();
+[[nodiscard]] QByteArray DnsUserAgent();
+
+struct DnsEntry {
+	QString data;
+	crl::time TTL = 0;
+};
+
+[[nodiscard]] std::vector<DnsEntry> ParseDnsResponse(
+	const QByteArray &bytes,
+	std::optional<int> typeRestriction = std::nullopt);
+
+struct ServiceWebRequest {
+	ServiceWebRequest(not_null<QNetworkReply*> reply);
+	ServiceWebRequest(ServiceWebRequest &&other);
+	ServiceWebRequest &operator=(ServiceWebRequest &&other);
+	~ServiceWebRequest();
+
+	void destroy();
+
+	QPointer<QNetworkReply> reply;
+};
+
+class DomainResolver : public QObject {
+public:
+	DomainResolver(Fn<void(
+		const QString &domain,
+		const QStringList &ips,
+		crl::time expireAt)> callback);
+
+	void resolve(const QString &domain);
+
+private:
+	enum class Type {
+		Mozilla,
+		Google,
+	};
+	struct Attempt {
+		Type type;
+		QString data;
+		QString host;
+	};
+	struct AttemptKey {
+		QString domain;
+		bool ipv6 = false;
+
+		inline bool operator<(const AttemptKey &other) const {
+			return (domain < other.domain)
+				|| (domain == other.domain && !ipv6 && other.ipv6);
+		}
+		inline bool operator==(const AttemptKey &other) const {
+			return (domain == other.domain) && (ipv6 == other.ipv6);
+		}
+	};
+	struct CacheEntry {
+		QStringList ips;
+		crl::time expireAt = 0;
+	};
+	struct Attempts {
+		std::vector<Attempt> list;
+		base::has_weak_ptr guard;
+	};
+
+	void resolve(const AttemptKey &key);
+	void sendNextRequest(const AttemptKey &key);
+	void performRequest(const AttemptKey &key, const Attempt &attempt);
+	void checkExpireAndPushResult(const QString &domain);
+	void requestFinished(
+		const AttemptKey &key,
+		not_null<QNetworkReply*> reply);
+	QByteArray finalizeRequest(
+		const AttemptKey &key,
+		not_null<QNetworkReply*> reply);
+
+	Fn<void(
+		const QString &domain,
+		const QStringList &ips,
+		crl::time expireAt)> _callback;
+
+	QNetworkAccessManager _manager;
+	std::map<AttemptKey, Attempts> _attempts;
+	std::map<AttemptKey, std::vector<ServiceWebRequest>> _requests;
+	std::map<AttemptKey, CacheEntry> _cache;
+	crl::time _lastTimestamp = 0;
+
+};
+
+} // namespace MTP::details