CClientTCPSocket.h

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/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          https://www.mrpt.org/                         |
   |                                                                        |
   | Copyright (c) 2005-2020, Individual contributors, see AUTHORS file     |
   | See: https://www.mrpt.org/Authors - All rights reserved.               |
   | Released under BSD License. See: https://www.mrpt.org/License          |
   +------------------------------------------------------------------------+ */
#pragma once

#include <mrpt/config.h>  // MRPT_WORD_SIZE
#include <mrpt/io/CStream.h>
#include <mrpt/system/os.h>
#include <cstdint>
#include <cstring>  // strlen()
#include <string>

namespace mrpt
{
/** Serial and networking devices and utilities */
namespace comms
{
class CServerTCPSocket;

/** A TCP socket that can be connected to a TCP server, implementing MRPT's
 * CStream interface for passing objects as well as generic read/write methods.
 *  Unless otherwise noticed, operations are blocking.
 *
 *  Note that for convenience, DNS lookup is performed with a timeout
 * (default=3000ms), which can be changed by the static member
 * CClientTCPSocket::DNS_LOOKUP_TIMEOUT_MS
 * \ingroup mrpt_comms_grp
 */
class CClientTCPSocket : public mrpt::io::CStream
{
    friend class CServerTCPSocket;

   public:
    /** See description of CClientTCPSocket */
    static unsigned int DNS_LOOKUP_TIMEOUT_MS;

   protected:
#ifdef _WIN32
/** The handle for the connected TCP socket, or INVALID_SOCKET
 */
#if MRPT_WORD_SIZE == 64
    uint64_t m_hSock;
#else
    uint32_t m_hSock;
#endif
#else
    /** The handle for the connected TCP socket, or -1 */
    int m_hSock;
#endif
    /** The IP address of the remote part of the connection. */
    std::string m_remotePartIP;
    /** The TCP port of the remote part of the connection. */
    unsigned short m_remotePartPort = 0;

    /** Introduces a virtual method responsible for reading from the stream
     * (This method BLOCKS)
     * This method is implemented as a call to "readAsync" with infinite
     * timeouts.
     * \sa readAsync */
    size_t Read(void* Buffer, size_t Count) override;

    /** Introduces a virtual method responsible for writing to the stream.
     *  Write attempts to write up to Count bytes to Buffer, and returns the
     * number of bytes actually written.
     *  This method is implemented as a call to "writeAsync" with infinite
     * timeouts.
     * \sa writeAsync */
    size_t Write(const void* Buffer, size_t Count) override;

    /** Returns a description of the last Sockets error */
    std::string getLastErrorStr();

   public:
    /** Default constructor \sa connect  */
    CClientTCPSocket();

    /** Destructor */
    ~CClientTCPSocket() override;

    /** Establishes a connection with a remote part.
     * \param remotePartAddress This string can be a host name, like "server"
     * or "www.mydomain.org", or an IP address "11.22.33.44".
     * \param remotePartTCPPort The port on the remote machine to connect to.
     * \param timeout_ms  The timeout to wait for the connection (0: NO
     * TIMEOUT)
     * \exception This method raises an exception if an error is found with a
     * textual description of the error.
     */
    void connect(
        const std::string& remotePartAddress, unsigned short remotePartTCPPort,
        unsigned int timeout_ms = 0);

    /** Returns true if this objects represents a successfully connected socket
     */
    bool isConnected();

    /** Closes the connection */
    void close();

    /** Writes a string to the socket.
     * \exception std::exception On communication errors
     */
    void sendString(const std::string& str);

    /** This virtual method has no effect in this implementation over a TCP
     * socket, and its use raises an exception */
    uint64_t Seek(
        int64_t off, CStream::TSeekOrigin org = sFromBeginning) override;

    /** This virtual method has no effect in this implementation over a TCP
     * socket, and its use raises an exception */
    uint64_t getTotalBytesCount() const override;

    /** This virtual method has no effect in this implementation over a TCP
     * socket, and its use raises an exception */
    uint64_t getPosition() const override;

    /** A method for reading from the socket with an optional timeout.
     * \param Buffer The destination of data.
     * \param Cound The number of bytes to read.
     * \param timeoutStart_ms The maximum timeout (in milliseconds) to wait for
     * the starting of data from the other side.
     * \param timeoutBetween_ms The maximum timeout (in milliseconds) to wait
     * for a chunk of data after a previous one.
     *  Set timeout's to -1 to block until the desired number of bytes are
     * read, or an error happens.
     *  \return The number of actually read bytes.
     */
    size_t readAsync(
        void* Buffer, const size_t Count, const int timeoutStart_ms = -1,
        const int timeoutBetween_ms = -1);

    /** A method for writing to the socket with optional timeouts.
     *  The method supports writing block by block as the socket allows us to
     * write more data.
     * \param Buffer The data.
     * \param Cound The number of bytes to write.
     * \param timeout_ms The maximum timeout (in milliseconds) to wait for the
     * socket to be available for writing (for each block).
     *  Set timeout's to -1 to block until the desired number of bytes are
     * written, or an error happens.
     *  \return The number of actually written bytes.
     */
    size_t writeAsync(
        const void* Buffer, const size_t Count, const int timeout_ms = -1);

    /** Send a message through the TCP stream.
     * \param outMsg The message to be shown.
     * \param timeout_ms The maximum timeout (in milliseconds) to wait for the
     * socket in each write operation.
     * \return Returns false on any error, or true if everything goes fine.
     * \tparam MESSAGE can be mrpt::serialization::CMessage
     */
    template <class MESSAGE>
    bool sendMessage(const MESSAGE& outMsg, const int timeout_ms = -1)
    {
        // (1) Send a "magic word":
        const char* magic = "MRPTMessage";
        uint32_t toWrite = strlen(magic);
        uint32_t written = writeAsync(magic, toWrite, timeout_ms);
        if (written != toWrite) return false;  // Error!
        // (2) Send the message type:
        toWrite = sizeof(outMsg.type);
        written = writeAsync(&outMsg.type, toWrite, timeout_ms);
        if (written != toWrite) return false;  // Error!
        // (3) Send the message's content length:
        uint32_t contentLen = outMsg.content.size();
        toWrite = sizeof(contentLen);
        written = writeAsync(&contentLen, toWrite, timeout_ms);
        if (written != toWrite) return false;  // Error!
        // (4) Send the message's contents:
        toWrite = contentLen;
        written = writeAsync(&outMsg.content[0], toWrite, timeout_ms);
        if (written != toWrite) return false;  // Error!
        return true;
    }

    /** Waits for an incoming message through the TCP stream.
     * \param inMsg The received message is placed here.
     * \param timeoutStart_ms The maximum timeout (in milliseconds) to wait for
     * the starting of data from the other side.
     * \param timeoutBetween_ms The maximum timeout (in milliseconds) to wait
     * for a chunk of data after a previous one.
     * \return Returns false on any error (or timeout), or true if everything
     * goes fine.
     * \tparam MESSAGE can be mrpt::serialization::CMessage
     */
    template <class MESSAGE>
    bool receiveMessage(
        MESSAGE& inMsg, const unsigned int timeoutStart_ms = 100,
        const unsigned int timeoutBetween_ms = 1000)
    {
        // (1) Read the "magic word":
        char magic[20];
        uint32_t toRead = 11;
        uint32_t actRead =
            readAsync(magic, toRead, timeoutStart_ms, timeoutBetween_ms);
        if (actRead != toRead) return false;  // Error!
        magic[actRead] = 0;  // Null-term string
        // Check magic:
        if (0 != ::strcmp("MRPTMessage", magic)) return false;
        // (2) Read the message type:
        toRead = sizeof(inMsg.type);
        actRead = readAsync(
            &inMsg.type, toRead, timeoutBetween_ms, timeoutBetween_ms);
        if (actRead != toRead) return false;  // Error!
        // (3) Read the message's content length:
        uint32_t contentLen;
        toRead = sizeof(contentLen);
        actRead = readAsync(
            &contentLen, toRead, timeoutBetween_ms, timeoutBetween_ms);
        if (actRead != toRead) return false;  // Error!
        inMsg.content.resize(contentLen);
        // (4) Read the message's contents:
        toRead = contentLen;
        actRead = readAsync(
            &inMsg.content[0], toRead, timeoutBetween_ms, timeoutBetween_ms);
        if (actRead != toRead) return false;  // Error!
        return true;
    }

    /** Return the number of bytes already in the receive queue (they can be
     * read without waiting) */
    size_t getReadPendingBytes();

    /** Set the TCP no delay option of the protocol (Nagle algorithm).
     * \param newValue New value (0 enable Nagle algorithm, 1 disable).
     * \return Return a number lower than 0 if any error occurred.
     */
    int setTCPNoDelay(int newValue);

    /** Return the value of the TCPNoDelay option. */
    int getTCPNoDelay();

    /** Set the size of the SO send buffer. This buffer is used to store data,
     * and is sended when is full.
     * \param newValue New size of the SO send buffer.
     * \return Return a number lower than 0 if any error occurred.
     */
    int setSOSendBufffer(int newValue);

    /** Return the current size of the SO send buffer. */
    int getSOSendBufffer();

};  // End of class def.

}  // namespace comms
}  // namespace mrpt