mendersoftware / mender / 1583599051

// Copyright 2023 Northern.tech AS

//

//    Licensed under the Apache License, Version 2.0 (the "License");

//    you may not use this file except in compliance with the License.

//    You may obtain a copy of the License at

//

//        http://www.apache.org/licenses/LICENSE-2.0

//

//    Unless required by applicable law or agreed to in writing, software

//    distributed under the License is distributed on an "AS IS" BASIS,

//    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

//    See the License for the specific language governing permissions and

//    limitations under the License.

#ifndef MENDER_COMMON_HTTP_HPP

#define MENDER_COMMON_HTTP_HPP

#include <functional>

#include <string>

#include <memory>

#include <unordered_map>

#include <unordered_set>

#include <vector>

#include <common/config.h>

#ifdef MENDER_USE_BOOST_BEAST

#include <boost/asio.hpp>

#include <boost/beast.hpp>

#include <boost/asio/ssl.hpp>

#include <boost/asio/ssl/error.hpp>

#include <boost/asio/ssl/stream.hpp>

#endif // MENDER_USE_BOOST_BEAST

#include <common/common.hpp>

#include <common/error.hpp>

#include <common/events.hpp>

#include <common/expected.hpp>

#include <common/io.hpp>

#include <common/log.hpp>

namespace mender {

namespace common {

namespace http {

namespace resumer {

class DownloadResumerClient;

class HeaderHandlerFunctor;

class BodyHandlerFunctor;

} // namespace resumer

using namespace std;

#ifdef MENDER_USE_BOOST_BEAST

namespace asio = boost::asio;

namespace beast = boost::beast;

namespace http = beast::http;

namespace ssl = asio::ssl;

using tcp = asio::ip::tcp;

#endif // MENDER_USE_BOOST_BEAST

namespace common = mender::common;

namespace error = mender::common::error;

namespace events = mender::common::events;

namespace expected = mender::common::expected;

namespace io = mender::common::io;

namespace log = mender::common::log;

class Client;

class ClientInterface;

class HttpErrorCategoryClass : public std::error_category {

public:

        const char *name() const noexcept override;

        string message(int code) const override;

};

extern const HttpErrorCategoryClass HttpErrorCategory;

enum ErrorCode {

        NoError = 0,

        NoSuchHeaderError,

        InvalidUrlError,

        BodyMissingError,

        BodyIgnoredError,

        HTTPInitError,

        UnsupportedMethodError,

        StreamCancelledError,

        MaxRetryError,

        DownloadResumerError,

        ProxyError,

};

error::Error MakeError(ErrorCode code, const string &msg);

enum class Method {

        Invalid,

        GET,

        HEAD,

        POST,

        PUT,

        PATCH,

        CONNECT,

};

enum StatusCode {

        // Not a complete enum, we define only the ones we use.

        StatusSwitchingProtocols = 101,

        StatusOK = 200,

        StatusNoContent = 204,

        StatusPartialContent = 206,

        StatusBadRequest = 400,

        StatusUnauthorized = 401,

        StatusNotFound = 404,

        StatusConflict = 409,

        StatusInternalServerError = 500,

        StatusNotImplemented = 501,

};

string MethodToString(Method method);

struct BrokenDownUrl {

        string protocol;

        string host;

        uint16_t port;

        string path;

        string username;

        string password;

};

error::Error BreakDownUrl(const string &url, BrokenDownUrl &address, bool with_auth = false);

string URLEncode(const string &value);

expected::ExpectedString URLDecode(const string &value);

string JoinOneUrl(const string &prefix, const string &url);

template <typename... Urls>

        }

}

class CaseInsensitiveHasher {

public:

        size_t operator()(const string &str) const;

};

class CaseInsensitiveComparator {

public:

        bool operator()(const string &str1, const string &str2) const;

};

class Transaction {

public:

        expected::ExpectedString GetHeader(const string &name) const;

        using HeaderMap =

                unordered_map<string, string, CaseInsensitiveHasher, CaseInsensitiveComparator>;

        const HeaderMap &GetHeaders() const {

                return headers_;

        }

protected:

        HeaderMap headers_;

        friend class Client;

};

using TransactionPtr = shared_ptr<Transaction>;

using BodyGenerator = function<io::ExpectedReaderPtr()>;

using AsyncBodyGenerator = function<io::ExpectedAsyncReaderPtr()>;

class Request : public Transaction {

public:

        Request() {

        }

        string GetHost() const;

        string GetProtocol() const;

        int GetPort() const;

        Method GetMethod() const;

        string GetPath() const;

protected:

        Method method_ {Method::Invalid};

        BrokenDownUrl address_;

        friend class Client;

        friend class Stream;

};

using RequestPtr = shared_ptr<Request>;

using ExpectedRequestPtr = expected::expected<RequestPtr, error::Error>;

class Response : public Transaction {

public:

        Response() {

        }

        unsigned GetStatusCode() const;

        string GetStatusMessage() const;

protected:

        unsigned status_code_ {StatusInternalServerError};

        string status_message_;

        friend class Client;

        friend class Stream;

};

using ResponsePtr = shared_ptr<Response>;

using ExpectedResponsePtr = expected::expected<ResponsePtr, error::Error>;

class OutgoingRequest;

using OutgoingRequestPtr = shared_ptr<OutgoingRequest>;

using ExpectedOutgoingRequestPtr = expected::expected<OutgoingRequestPtr, error::Error>;

class IncomingRequest;

using IncomingRequestPtr = shared_ptr<IncomingRequest>;

using ExpectedIncomingRequestPtr = expected::expected<IncomingRequestPtr, error::Error>;

class IncomingResponse;

using IncomingResponsePtr = shared_ptr<IncomingResponse>;

using ExpectedIncomingResponsePtr = expected::expected<IncomingResponsePtr, error::Error>;

class OutgoingResponse;

using OutgoingResponsePtr = shared_ptr<OutgoingResponse>;

using ExpectedOutgoingResponsePtr = expected::expected<OutgoingResponsePtr, error::Error>;

using RequestHandler = function<void(ExpectedIncomingRequestPtr)>;

using IdentifiedRequestHandler = function<void(IncomingRequestPtr, error::Error)>;

using ResponseHandler = function<void(ExpectedIncomingResponsePtr)>;

using ReplyFinishedHandler = function<void(error::Error)>;

using SwitchProtocolHandler = function<void(io::ExpectedAsyncReadWriterPtr)>;

class BaseOutgoingRequest : public Request {

public:

        BaseOutgoingRequest() {

        }

        void SetMethod(Method method);

        void SetHeader(const string &name, const string &value);

        // Set to a function which will generate the body. Make sure that the Content-Length set in

        // the headers matches the length of the body. Using a generator instead of a direct reader

        // is needed in case of redirects. Note that it is not possible to set both; setting one

        // unsets the other.

        void SetBodyGenerator(BodyGenerator body_gen);

        void SetAsyncBodyGenerator(AsyncBodyGenerator body_gen);

protected:

        // Original address.

        string orig_address_;

private:

        BodyGenerator body_gen_;

        io::ReaderPtr body_reader_;

        AsyncBodyGenerator async_body_gen_;

        io::AsyncReaderPtr async_body_reader_;

        friend class Client;

};

class OutgoingRequest : public BaseOutgoingRequest {

public:

        OutgoingRequest() {

        }

        error::Error SetAddress(const string &address);

};

class Stream;

class IncomingRequest :

        public Request,

        virtual public io::Canceller,

        public enable_shared_from_this<IncomingRequest> {

public:

        ~IncomingRequest();

        // Set this after receiving the headers to automatically write the body. If there is no

        // body, nothing will be written. Mutually exclusive with `MakeBodyAsyncReader()`.

        void SetBodyWriter(io::WriterPtr body_writer);

        // Use this to get an async reader for the body. If there is no body, it returns a

        // `BodyMissingError`; it's safe to continue afterwards, but without a reader. Mutually

        // exclusive with `SetBodyWriter()`.

        io::ExpectedAsyncReaderPtr MakeBodyAsyncReader();

        // Use this to get a response that can be used to reply to the request. Due to the

        // asynchronous nature, this can be done immediately or some time later.

        ExpectedOutgoingResponsePtr MakeResponse();

        void Cancel() override;

private:

        IncomingRequest(Stream &stream, shared_ptr<bool> cancelled) :

                stream_(stream),

                cancelled_(cancelled) {

        }

        Stream &stream_;

        shared_ptr<bool> cancelled_;

        friend class Server;

        friend class Stream;

};

class IncomingResponse :

        public Response,

        virtual public io::Canceller,

        public enable_shared_from_this<IncomingResponse> {

public:

        void Cancel() override;

        // Set this after receiving the headers to automatically write the body. If there is no

        // body, nothing will be written. Mutually exclusive with `MakeBodyAsyncReader()`.

        void SetBodyWriter(io::WriterPtr body_writer);

        // Use this to get an async reader for the body. If there is no body, it returns a

        // `BodyMissingError`; it's safe to continue afterwards, but without a reader. Mutually

        // exclusive with `SetBodyWriter()`.

        io::ExpectedAsyncReaderPtr MakeBodyAsyncReader();

        // Gets the underlying socket after a 101 Switching Protocols response. This detaches the

        // socket from `Client`, and both can be used independently from then on.

        io::ExpectedAsyncReadWriterPtr SwitchProtocol();

private:

        IncomingResponse(ClientInterface &client, shared_ptr<bool> cancelled);

private:

        ClientInterface &client_;

        shared_ptr<bool> cancelled_;

        friend class Client;

        friend class resumer::DownloadResumerClient;

        // The DownloadResumer's handlers needs to manipulate internals of IncomingResponse

        friend class resumer::HeaderHandlerFunctor;

        friend class resumer::BodyHandlerFunctor;

};

class OutgoingResponse :

        public Response,

        virtual public io::Canceller,

        public enable_shared_from_this<OutgoingResponse> {

public:

        ~OutgoingResponse();

        error::Error AsyncReply(ReplyFinishedHandler reply_finished_handler);

        void Cancel() override;

        void SetStatusCodeAndMessage(unsigned code, const string &message);

        void SetHeader(const string &name, const string &value);

        // Set to a Reader which contains the body. Make sure that the Content-Length set in the

        // headers matches the length of the body. Note that it is not possible to set both; setting

        // one unsets the other.

        void SetBodyReader(io::ReaderPtr body_reader);

        void SetAsyncBodyReader(io::AsyncReaderPtr body_reader);

        // An alternative to AsyncReply. `resp` should already contain the correct status and

        // headers to perform the switch, and the handler will be called after the HTTP headers have

        // been written.

        error::Error AsyncSwitchProtocol(SwitchProtocolHandler handler);

private:

        OutgoingResponse(Stream &stream, shared_ptr<bool> cancelled) :

                stream_ {stream},

                cancelled_ {cancelled} {

        }

        io::ReaderPtr body_reader_;

        io::AsyncReaderPtr async_body_reader_;

        Stream &stream_;

        shared_ptr<bool> cancelled_;

        friend class Server;

        friend class Stream;

        friend class IncomingRequest;

};

template <typename StreamType>

class BodyAsyncReader;

// Master object that connections are made from. Configure TLS options on this object before making

// connections.

struct ClientConfig {

        string server_cert_path;

        string client_cert_path;

        string client_cert_key_path;

        // C++11 cannot mix default member initializers with designated initializers

        // (named parameters). However, bool doesn't have a guaranteed initial value

        // so we need to use our custom type that defaults to false.

        common::def_bool skip_verify;

        string http_proxy;

        string https_proxy;

        string no_proxy;

        string ssl_engine;

};

enum class TransactionStatus {

        None,

        HeaderHandlerCalled,

        ReaderCreated,

        BodyReadingInProgress,

        BodyReadingFinished,

        BodyHandlerCalled, // Only used by server.

        Replying,          // Only used by server.

        SwitchingProtocol,

        Done,

};

static inline bool AtLeast(TransactionStatus status, TransactionStatus expected_status) {

        return static_cast<int>(status) >= static_cast<int>(expected_status);

}

// Interface which manages one connection, and its requests and responses (one at a time).

class ClientInterface {

public:

        virtual ~ClientInterface() {};

        // `header_handler` is called when header has arrived, `body_handler` is called when the

        // whole body has arrived.

        virtual error::Error AsyncCall(

                OutgoingRequestPtr req, ResponseHandler header_handler, ResponseHandler body_handler) = 0;

        virtual void Cancel() = 0;

        // Use this to get an async reader for the body. If there is no body, it returns a

        // `BodyMissingError`; it's safe to continue afterwards, but without a reader.

        virtual io::ExpectedAsyncReaderPtr MakeBodyAsyncReader(IncomingResponsePtr resp) = 0;

        // Returns the real HTTP client.

        virtual Client &GetHttpClient() = 0;

};

class Client :

        virtual public ClientInterface,

        public events::EventLoopObject,

        virtual public io::Canceller {

public:

        Client(

                const ClientConfig &client,

                events::EventLoop &event_loop,

                const string &logger_name = "http_client");

        virtual ~Client();

        Client(Client &&) = default;

        error::Error AsyncCall(

                OutgoingRequestPtr req,

                ResponseHandler header_handler,

                ResponseHandler body_handler) override;

        void Cancel() override;

        io::ExpectedAsyncReaderPtr MakeBodyAsyncReader(IncomingResponsePtr resp) override;

        // Gets the underlying socket after a 101 Switching Protocols response. This detaches the

        // socket from `Client`, and both can be used independently from then on.

        virtual io::ExpectedAsyncReadWriterPtr SwitchProtocol(IncomingResponsePtr req);

        Client &GetHttpClient() override {

                return *this;

        };

protected:

        events::EventLoop &event_loop_;

        string logger_name_;

        log::Logger logger_ {logger_name_};

        ClientConfig client_config_;

        string http_proxy_;

        string https_proxy_;

        string no_proxy_;

private:

        enum class SocketMode {

                Plain,

                Tls,

                TlsTls,

        };

        SocketMode socket_mode_;

        // Used during connections. Must remain valid due to async nature.

        OutgoingRequestPtr request_;

        IncomingResponsePtr response_;

        ResponseHandler header_handler_;

        ResponseHandler body_handler_;

        vector<uint8_t>::iterator reader_buf_start_;

        vector<uint8_t>::iterator reader_buf_end_;

        io::AsyncIoHandler reader_handler_;

        // Each time we cancel something, we set this to true, and then make a new one. This ensures

        // that for everyone who has a copy, it will stay true even after a new request is made, or

        // after things have been destroyed.

        shared_ptr<bool> cancelled_;

#ifdef MENDER_USE_BOOST_BEAST

        bool initialized_ {false};

#define MENDER_BOOST_BEAST_SSL_CTX_COUNT 2

        ssl::context ssl_ctx_[MENDER_BOOST_BEAST_SSL_CTX_COUNT] = {

                ssl::context {ssl::context::tls_client},

                ssl::context {ssl::context::tls_client},

        };

        boost::asio::ip::tcp::resolver resolver_;

        shared_ptr<ssl::stream<ssl::stream<tcp::socket>>> stream_;

        vector<uint8_t> body_buffer_;

        asio::ip::tcp::resolver::results_type resolver_results_;

        // The reason that these are inside a struct is a bit complicated. We need to deal with what

        // may be a bug in Boost Beast: Parsers and serializers can access the corresponding request

        // and response structures even after they have been cancelled. This means two things:

        //

        // 1. We need to make sure that the response/request and the parser/serializer both survive

        //    until the handler is called, even if they are not used in the handler, and even if

        //    the handler returns `operation_aborted` (cancelled).

        //

        // 2. We need to make sure that the parser/serializer is destroyed before the

        //    response/request, since the former accesses the latter.

        //

        // For point number 1, it is enough to simply make a copy of the shared pointers in the

        // handler function, which will keep them alive long enough.

        //

        // For point 2 however, even though it may seem logical that a lambda would destroy its

        // captured variables in the reverse order they are captured, the order is in fact

        // unspecified. That means we need to enforce the order, and that's what the struct is

        // for: Struct members are always destroyed in reverse declaration order.

        struct {

                shared_ptr<http::request<http::buffer_body>> http_request_;

                shared_ptr<http::request_serializer<http::buffer_body>> http_request_serializer_;

        } request_data_;

        // See `Client::request_data_` for why this is a struct.

        struct {

                shared_ptr<beast::flat_buffer> response_buffer_;

                shared_ptr<http::response_parser<http::buffer_body>> http_response_parser_;

                size_t last_buffer_size_;

        } response_data_;

        TransactionStatus status_ {TransactionStatus::None};

        // Only used for HTTPS proxy requests, because we need two requests, one to CONNECT, and one

        // for the original request. HTTP doesn't need it because it only modifies the original

        // request.

        OutgoingRequestPtr secondary_req_;

        error::Error Initialize();

        void DoCancel();

        void CallHandler(ResponseHandler handler);

        void CallErrorHandler(

                const error_code &ec, const OutgoingRequestPtr &req, ResponseHandler handler);

        void CallErrorHandler(

                const error::Error &err, const OutgoingRequestPtr &req, ResponseHandler handler);

        error::Error HandleProxySetup();

        void ResolveHandler(const error_code &ec, const asio::ip::tcp::resolver::results_type &results);

        void ConnectHandler(const error_code &ec, const asio::ip::tcp::endpoint &endpoint);

        template <typename StreamType>

        void HandshakeHandler(

                StreamType &stream, const error_code &ec, const asio::ip::tcp::endpoint &endpoint);

        void WriteHeaderHandler(const error_code &ec, size_t num_written);

        void WriteBodyHandler(const error_code &ec, size_t num_written);

        void PrepareAndWriteNewBodyBuffer();

        void WriteNewBodyBuffer(size_t size);

        void WriteBody();

        void ReadHeaderHandler(const error_code &ec, size_t num_read);

        void HandleSecondaryRequest();

        void ReadHeader();

        void AsyncReadNextBodyPart(

                vector<uint8_t>::iterator start, vector<uint8_t>::iterator end, io::AsyncIoHandler handler);

        void ReadBodyHandler(error_code ec, size_t num_read);

#endif // MENDER_USE_BOOST_BEAST

        friend class IncomingResponse;

        friend class BodyAsyncReader<Client>;

};

using ClientPtr = shared_ptr<Client>;

// Master object that servers are made from.

struct ServerConfig {

        // Empty for now, but will probably contain configuration options later.

};

class Server;

class Stream : public enable_shared_from_this<Stream> {

public:

        Stream(const Stream &) = delete;

        ~Stream();

        void Cancel();

private:

        Stream(Server &server);

private:

        Server &server_;

        friend class Server;

        log::Logger logger_;

        IncomingRequestPtr request_;

        // The reason we have two pointers is this: Between receiving a request, and producing a

        // reply, an arbitrary amount of time may pass, and it is the caller's responsibility to

        // first call MakeResponse(), and then at some point later, call AsyncReply(). However, if

        // the caller never does this, and destroys the response instead, we still have ownership to

        // the response here, which means it will never be destroyed, and we will leak memory. So we

        // use a weak_ptr to bridge the gap. As long as AsyncReply() has not been called yet, we use

        // a weak pointer so if the response goes out of scope, it will be properly destroyed. After

        // AsyncReply is called, we know that a handler will eventually be called, so we take

        // ownership of the response object from that point onwards.

        OutgoingResponsePtr response_;

        weak_ptr<OutgoingResponse> maybe_response_;

        friend class IncomingRequest;

        friend class OutgoingResponse;

        friend class BodyAsyncReader<Stream>;

        ReplyFinishedHandler reply_finished_handler_;

        SwitchProtocolHandler switch_protocol_handler_;

        vector<uint8_t>::iterator reader_buf_start_;

        vector<uint8_t>::iterator reader_buf_end_;

        io::AsyncIoHandler reader_handler_;

        // Each time we cancel something, we set this to true, and then make a new one. This ensures

        // that for everyone who has a copy, it will stay true even after a new request is made, or

        // after things have been destroyed.

        shared_ptr<bool> cancelled_;

#ifdef MENDER_USE_BOOST_BEAST

        asio::ip::tcp::socket socket_;

        // See `Client::request_data_` for why this is a struct.

        struct {

                shared_ptr<beast::flat_buffer> request_buffer_;

                shared_ptr<http::request_parser<http::buffer_body>> http_request_parser_;

                size_t last_buffer_size_;

        } request_data_;

        vector<uint8_t> body_buffer_;

        TransactionStatus status_ {TransactionStatus::None};

        // See `Client::request_data_` for why this is a struct.

        struct {

                shared_ptr<http::response<http::buffer_body>> http_response_;

                shared_ptr<http::response_serializer<http::buffer_body>> http_response_serializer_;

        } response_data_;

        void DoCancel();

        void CallErrorHandler(const error_code &ec, const RequestPtr &req, RequestHandler handler);

        void CallErrorHandler(const error::Error &err, const RequestPtr &req, RequestHandler handler);

        void CallErrorHandler(

                const error_code &ec, const IncomingRequestPtr &req, IdentifiedRequestHandler handler);

        void CallErrorHandler(

                const error::Error &err, const IncomingRequestPtr &req, IdentifiedRequestHandler handler);

        void CallErrorHandler(

                const error_code &ec, const RequestPtr &req, ReplyFinishedHandler handler);

        void CallErrorHandler(

                const error::Error &err, const RequestPtr &req, ReplyFinishedHandler handler);

        void CallErrorHandler(

                const error_code &ec, const RequestPtr &req, SwitchProtocolHandler handler);

        void CallErrorHandler(

                const error::Error &err, const RequestPtr &req, SwitchProtocolHandler handler);

        void AcceptHandler(const error_code &ec);

        void ReadHeader();

        void ReadHeaderHandler(const error_code &ec, size_t num_read);

        void AsyncReadNextBodyPart(

                vector<uint8_t>::iterator start, vector<uint8_t>::iterator end, io::AsyncIoHandler handler);

        void ReadBodyHandler(error_code ec, size_t num_read);

        void AsyncReply(ReplyFinishedHandler reply_finished_handler);

        void SetupResponse();

        void WriteHeaderHandler(const error_code &ec, size_t num_written);

        void PrepareAndWriteNewBodyBuffer();

        void WriteNewBodyBuffer(size_t size);

        void WriteBody();

        void WriteBodyHandler(const error_code &ec, size_t num_written);

        void CallBodyHandler();

        void FinishReply();

        error::Error AsyncSwitchProtocol(SwitchProtocolHandler handler);

        void SwitchingProtocolHandler(error_code ec, size_t num_written);

#endif // MENDER_USE_BOOST_BEAST

};

class Server : public events::EventLoopObject, virtual public io::Canceller {

public:

        Server(const ServerConfig &server, events::EventLoop &event_loop);

        ~Server();

        Server(Server &&) = default;

        error::Error AsyncServeUrl(

                const string &url, RequestHandler header_handler, RequestHandler body_handler);

        // Same as the above, except that the body handler has the `IncomingRequestPtr` included

        // even when there is an error, so that the request can be matched with the request which

        // was received in the header handler.

        error::Error AsyncServeUrl(

                const string &url, RequestHandler header_handler, IdentifiedRequestHandler body_handler);

        void Cancel() override;

        uint16_t GetPort() const;

        // Can differ from the passed in URL if a 0 (random) port number was used.

        string GetUrl() const;

        // Use this to get a response that can be used to reply to the request. Due to the

        // asynchronous nature, this can be done immediately or some time later.

        virtual ExpectedOutgoingResponsePtr MakeResponse(IncomingRequestPtr req);

        virtual error::Error AsyncReply(

                OutgoingResponsePtr resp, ReplyFinishedHandler reply_finished_handler);

        // Use this to get an async reader for the body. If there is no body, it returns a

        // `BodyMissingError`; it's safe to continue afterwards, but without a reader.

        virtual io::ExpectedAsyncReaderPtr MakeBodyAsyncReader(IncomingRequestPtr req);

        // An alternative to AsyncReply. `resp` should already contain the correct status and

        // headers to perform the switch, and the handler will be called after the HTTP headers have

        // been written.

        virtual error::Error AsyncSwitchProtocol(

                OutgoingResponsePtr resp, SwitchProtocolHandler handler);

private:

        events::EventLoop &event_loop_;

        BrokenDownUrl address_;

        RequestHandler header_handler_;

        IdentifiedRequestHandler body_handler_;

        friend class IncomingRequest;

        friend class Stream;

        friend class OutgoingResponse;

        using StreamPtr = shared_ptr<Stream>;

        friend class TestInspector;

#ifdef MENDER_USE_BOOST_BEAST

        asio::ip::tcp::acceptor acceptor_;

        unordered_set<StreamPtr> streams_;

        void DoCancel();

        void PrepareNewStream();

        void AsyncAccept(StreamPtr stream);

        void RemoveStream(StreamPtr stream);

#endif // MENDER_USE_BOOST_BEAST

};

class ExponentialBackoff {

public:

        ExponentialBackoff(chrono::milliseconds max_interval, int try_count = -1) :

                try_count_ {try_count} {

                SetMaxInterval(max_interval);

        }

        void Reset() {

                SetIteration(0);

        }

        int TryCount() {

                return try_count_;

        }

        void SetTryCount(int count) {

                try_count_ = count;

        }

        chrono::milliseconds SmallestInterval() {

                return smallest_interval_;

        }

        void SetSmallestInterval(chrono::milliseconds interval) {

                smallest_interval_ = interval;

                if (max_interval_ < smallest_interval_) {

                        max_interval_ = smallest_interval_;

                }

        }

        chrono::milliseconds MaxInterval() {

                return max_interval_;

        }

        void SetMaxInterval(chrono::milliseconds interval) {

                max_interval_ = interval;

                if (max_interval_ < smallest_interval_) {

                        max_interval_ = smallest_interval_;

                }

        }

        using ExpectedInterval = expected::expected<chrono::milliseconds, error::Error>;

        ExpectedInterval NextInterval();

        // Set which iteration we're at. Mainly for use in tests.

        void SetIteration(int iteration) {

                iteration_ = iteration;

        }

private:

        chrono::milliseconds smallest_interval_ {chrono::minutes(1)};

        chrono::milliseconds max_interval_;

        int try_count_;

        int iteration_ {0};

};

expected::ExpectedString GetHttpProxyStringFromEnvironment();

expected::ExpectedString GetHttpsProxyStringFromEnvironment();

expected::ExpectedString GetNoProxyStringFromEnvironment();

bool HostNameMatchesNoProxy(const string &host, const string &no_proxy);

} // namespace http

} // namespace common

} // namespace mender

#endif // MENDER_COMMON_HTTP_HPP