[C/C++] 전송 제어 프로토콜 (TCP, Transmission Control Protocol)

📣 전송 제어 프로토콜 (TCP, Transmission Control Protocol, SOCK_STREAM)

 

[C/C++] 전송 제어 프로토콜 (TCP, Transmission Control Protocol)

 

전송 제어 프로토콜(Transmission Control Protocol, TCP, 문화어: 전송 조종 규약)은 인터넷 프로토콜 스위트(IP)의 핵심 프로토콜 중 하나로, IP와 함께 TCP/IP라는 명칭으로도 널리 불린다. TCP는 근거리 통신망이나 인트라넷, 인터넷에 연결된 컴퓨터에서 실행되는 프로그램 간에 일련의 옥텟을 안정적으로, 순서대로, 에러 없이 교환할 수 있게 한다. TCP는 전송 계층에 위치한다. 네트워크의 정보 전달을 통제하는 프로토콜이자 인터넷을 이루는 핵심 프로토콜의 하나로서 국제 인터넷 표준화 기구(IETF)의 RFC 793에 기술되어 있다.

 

📌 Connection Establishment (3 Way handshaking)

📌 Connection Termination (4 Way handshaking)

[C/C++] 전송 제어 프로토콜 (TCP, Transmission Control Protocol)

 

In telecommunications, a handshake is an automated process of negotiation between two communicating in between participants (example "Alice and Bob") through the exchange of information that establishes the protocols of a communication link at the start of the communication, before full communication begins. The handshaking process usually takes place in order to establish rules for communication when a computer attempts to communicate with another device. Signals are usually exchanged between two devices to establish a communication link. For example, when a computer communicates with another device such as a modem, the two devices will signal each other that they are switched on and ready to work, as well as to agree to which protocols are being used.

 

📌 전송 제어 프로토콜의 특징 (Transmission Control Protocol Features)

• 중간에 데이터가 소멸되지 않고 목적지로의 전송을 보장한다.

• 전송 순서대로 데이터가 수신된다.

• 전송되는 데이터의 경계 (Boundary)가 존재하지 않는다.

---

🔍 TCP/IP Server 함수호출 순서

1️⃣ Socket() - 소켓생성

• The socket function creates a socket that is bound to a specific transport service provider.

📋 Socket() Syntax

SOCKET WSAAPI socket(
  int af,
  int type,
  int protocol
);

---

📋 Socket() Source Code by C++

private:        
   int szClntAddr;
   SOCKET hServSock;
   SOCKADDR_IN servAddr;

/* ^---------HEADER---------^ */

// MARK: Create TCP Socket
this->hServSock = socket(PF_INET, SOCK_STREAM, 0);
if (this->hServSock == INVALID_SOCKET) {
    // here error message.
}

---

2️⃣ Bind() - 소켓 주소할당

• The bind function associates a local address with a socket.

📋 Bind() Syntax

int bind(
  SOCKET         s,
  const sockaddr *addr,
  int            namelen
);

---

📋 Bind() Source Code by C++

std::memset(&this->servAddr, 0, sizeof(SOCKADDR_IN));
this->servAddr.sin_family        = AF_INET;
this->servAddr.sin_addr.s_addr        = htonl(INADDR_ANY); // INADDR_ANY 모든 IP 대역 접속을 허가한다.
this->servAddr.sin_port            = htons(port);

// MARK: bind 함수는 지역주소를 소켓과 함께 결합(연관)시킵니다.
if (bind(this->hServSock, (sockaddr *)&this->servAddr, sizeof(SOCKADDR_IN)) == SOCKET_ERROR) {
    // here error message.
}

---

3️⃣ Listen() - 연결요청 대기상태

• The listen function places a socket in a state in which it is listening for an incoming connection.

📋 Listen() Syntax

int WSAAPI listen(
  SOCKET s,
  int    backlog
);

---

📋 Listen() Source Code by C++

// MARK: listen 함수는 소켓을 들어오는 연결에 대해 listening 상태에 배치합니다.
if (listen(this->hServSock, MAX_REQUEST_QUEUE_SIZE) == SOCKET_ERROR) {
    // here error message.
}

---

4️⃣ Accept() - 연결허용

• The accept function permits an incoming connection attempt on a socket.

📋 Accept() Syntax

SOCKET WSAAPI accept(
  SOCKET   s,
  sockaddr *addr,
  int      *addrlen
);

---

📋 Accept() Source Code by C++

// MARK: Accpet 함수는 소켓에 들어오는 연결 시도에 대해서 허가한다.
SOCKADDR_IN clientAddr;
this->szClntAddr    = sizeof(SOCKADDR_IN);
SOCKET hClientSock  = accept(this->hServSock, (SOCKADDR *)&clientAddr, &this->szClntAddr);

if (hClientSock == INVALID_SOCKET || hClientSock == SOCKET_ERROR) {
    // here error message and close sock.
}

---

5️⃣ Read()/Write() - 데이터 송수신

• The recv function receives data from a connected socket or a bound connectionless socket.

• The send function sends data on a connected socket.

📋 Read() / Write() Syntax

int WSAAPI send(
  SOCKET     s,
  const char *buf,
  int        len,
  int        flags
);

int recv(
  SOCKET s,
  char   *buf,
  int    len,
  int    flags
);

---

📋 Read() / Write() Source Code by C++

const bool OnSendMessage(const SOCKET sock, const std::string message) {
    return send(sock, message.c_str(), message.size(), 0) == 0 ? true : false; // ZERO == Success, EOF == Fail
}

const int OnReceiveMessage(const SOCKET sock) {
    char message[BUFSIZ];
    const int length = recv(sock, message, BUFSIZ, 0);
    return length;
}

---

6️⃣ Close() - 연결종료

• The closesocket function closes an existing socket.

📋 Close() Syntax

int closesocket(
  IN SOCKET s
);

📋 Close() Source Code by C++

closesocket(this->hServSock);

---

🔍 TCP/IP Client 함수호출 순서

1️⃣ Socket() - 소켓생성

• The socket function creates a socket that is bound to a specific transport service provider.

📋 Socket() Syntax

SOCKET WSAAPI socket(
  int af,
  int type,
  int protocol
);

---

📋 Socket() Source Code by C++

private:        
   SOCKET hServSock;
   SOCKADDR_IN servAddr;

/* ^---------HEADER---------^ */

this->hServSock = socket(PF_INET, SOCK_STREAM, 0);
if (this->hServSock == INVALID_SOCKET) { 
    // here error message and close sock.
}

---

2️⃣ Connect() - 연결요청

• The connect function establishes a connection to a specified socket.

📋 Connect() Syntax

int WSAAPI connect(
  SOCKET         s,
  const sockaddr *name,
  int            namelen
);

---

📋 Connect() Source Code by C++

std::memset( &this->servAddr, 0, sizeof(SOCKADDR_IN) );
this->servAddr.sin_family    = AF_INET; // IPv4
this->servAddr.sin_addr.s_addr    = inet_addr("127.0.0.1");
this->servAddr.sin_port        = htons(1234);

// MARK: 생성한 소켓을 통해 서버로 접속을 요청합니다.
if ( connect(this->hServSock, (SOCKADDR *)&servAddr, sizeof(SOCKADDR)) == SOCKET_FAIL_ERROR) {
    // here error message and close sock.
}

---

3️⃣ Read()/Write() - 데이터 송수신

• The recv function receives data from a connected socket or a bound connectionless socket.

• The send function sends data on a connected socket.

📋 Read() / Write() Syntax

int WSAAPI send(
  SOCKET     s,
  const char *buf,
  int        len,
  int        flags
);

int recv(
  SOCKET s,
  char   *buf,
  int    len,
  int    flags
);

---

📋 Read() / Write() Source Code by C++

const bool OnSendMessage(const SOCKET sock, const std::string message) {
    return send(sock, message.c_str(), message.size(), 0) == 0 ? true : false; // ZERO == Success, EOF == Fail
}

const int OnReceiveMessage(const SOCKET sock) {
    char message[BUFSIZ];
    const int length = recv(sock, message, BUFSIZ, 0);
    return length;
}

---

4️⃣ Close() - 연결종료

• The closesocket function closes an existing socket.

📋 Close() Syntax

int closesocket(
  IN SOCKET s
);

---

📋 Close() Source Code by C++

closesocket(this->hServSock);

---

📂 Windows TCP/IP Source Code Files

ChatMFCApplicationDlg.cpp

0.02MB

ChatMFCApplicationDlg.h

0.00MB

WinSocket.cpp

0.01MB

WinSocket.h

0.00MB

WinSocketError.h

0.00MB

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[C/C++] MFC 기반의 Serial 및 Socket 통신 프로그램 레포트

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🚀 REFERENCE

인터넷 프로토콜 스위트 - 위키백과, 우리 모두의 백과사전

ChangYeop-Yang/Study-ComputerScience