有圖有真相 直接上圖
簡述Tcp的特點:上圖吧
簡述 tcp的三次握手
Connet 客戶端請求連接 發送字段syn = 1
Accept 服務器確認接收客戶端的連接 回覆syn = 1 ack=1;
Write 客戶端向服務器發送ack = 1
四次揮手:
假設客戶端先發起斷連
客戶端向服務器發送fin = 1 請求釋放連接
服務器端收到後發送ack = 1
服務器向客戶端發送釋放連接請求 fin =1
客戶端收到回覆ack 等待2msl時間後關閉 服務器收到ack立刻關閉
關於服務器和客戶端通信之間存在阻塞的地方:
accept函數
recv函數
下面直接上代碼:(服務器採用低效的併發模式C11線程+lambda表達式,客戶端採用異步事件選擇模型)
/******************************************server***************************************************************************/
//Need to link with Ws2_32.lib
#include <Winsock2.h>
#include <iostream>
#include <thread>
#pragma comment(lib, "Ws2_32.lib")
using namespace std;
int main(void)
{
/* 初始化winsock2庫 */
//Step 0. Initialize winsock2 library...
WSADATA wsaData;
if (WSAStartup(MAKEWORD(2, 2), &wsaData) != 0)
{
return 1;
}
// Step 1. Ask system for a socket.this socket is waiter
SOCKET sockServer = ::socket(PF_INET, SOCK_STREAM, 0);
if (sockServer == INVALID_SOCKET)
{
return 1;
}
//Step 2. bind the socket to a local address and port.接待套接字
sockaddr_in addrServer = { 0 };
addrServer.sin_family = AF_INET;
addrServer.sin_addr.S_un.S_addr = inet_addr("88.88.106.30");
//host to network short.小端轉大端
addrServer.sin_port = htons(30001);
if (::bind(sockServer, reinterpret_cast<const sockaddr*>(&addrServer),
sizeof addrServer) == SOCKET_ERROR)
{
return 1;
}
// Step 3. listen. 監聽隊列的設置 監聽五個套接字的連接
if (listen(sockServer, 5) == SOCKET_ERROR)
{
return 1;
}
// Step 4. accept.
sockaddr_in addrClient = { 0 }; //將對放的信息保存在這個結構體裏
int iLength = sizeof addrClient;
SOCKET sockClient = INVALID_SOCKET;
while (true)
{
//該返回的套接字纔是用於收發的套接字-這裏的邏輯是 一個連接開一個線程
sockClient = ::accept(sockServer, reinterpret_cast<sockaddr*>(&addrClient), &iLength);
if (sockClient == INVALID_SOCKET)
{
return 1;
}
thread t1([sockClient]()->void
{
//Step 5. receive and send data.
int iResult = ::send(sockClient, reinterpret_cast<const char*>(L"hello"),
(wcslen(L"hello") + 1) * 2, 0);
if (iResult <= 0)
{
return;
}
wchar_t buf[100] = { 0 };
iResult = ::recv(sockClient, reinterpret_cast<char*>(buf), 200, 0);
wcout << buf << endl;
::closesocket(sockClient);
});
t1.detach();//脫離主線程的管理 自己去跑
}
::closesocket(sockServer);
::WSACleanup();
return 0;
}
/******************************************client***************************************************************************/
#include <Winsock2.h>
#include <iostream>
#include<Windows.h>
#pragma comment(lib, "Ws2_32.lib")
#include <thread>
using namespace std;
HANDLE socketEvent;
HANDLE mythread;
HANDLE stopEvent;
DWORD __stdcall RecvThreadProc(LPVOID lpParam)
{
if (lpParam == NULL)
return 0;
SOCKET sock2server = reinterpret_cast<SOCKET>(lpParam);
//ClientBase *client = (ClientBase *)lpParam;
DWORD ret = 0;
int index = 0;
WSANETWORKEVENTS networkEvent;
HANDLE events[2];
events[0] = socketEvent; //網絡事件
events[1] = stopEvent; //線程退出事件
while (true)
{
ret = WSAWaitForMultipleEvents(2, events, FALSE, INFINITE, FALSE);
if (ret == WSA_WAIT_FAILED || ret == WSA_WAIT_TIMEOUT)
continue;
index = ret - WSA_WAIT_EVENT_0; //相減可以獲得響應的事件對應的事件數組下標,來確定是哪個網絡事件
if (index == 0)
{
WSAEnumNetworkEvents(sock2server, events[0], &networkEvent);//根據這個結構體我們就可以判斷是否是 我們所關注的網絡事件已經發生了
if (networkEvent.lNetworkEvents & FD_READ) //這裏有讀FD_WRITE 和 寫 FD_READ 接收消息用FD_READ
{
if (networkEvent.iErrorCode[FD_READ_BIT != 0])
{
//Error
continue;
}
wchar_t *buff = new wchar_t[100];
ret = recv(sock2server, reinterpret_cast<char*>( buff), 1024, 0);
if (ret == 0 || (ret == SOCKET_ERROR && WSAGetLastError() == WSAECONNRESET))
{
//client->OnConnectionClosed();
break; //錯誤
}
wcout << buff << endl;
}
if (networkEvent.lNetworkEvents & FD_CLOSE)//這裏指服務器主動斷連
{
//client->OnConnectionClosed();
break; //關閉
}
}
else//stopEvent 控制退出
{
wcout << L"program will exit."<< endl;
break;
}
}
}
int main(void)
{
/* 初始化winsock2庫 */
//Step 0. Initialize winsock2 library...
WSADATA wsaData;
if (WSAStartup(MAKEWORD(2, 2), &wsaData) != 0)
{
return 1;
}
//Step 1. Ask system for a socket. to->2. for->4.
SOCKET sock2Server = ::socket(PF_INET, SOCK_STREAM, 0);
if (sock2Server == INVALID_SOCKET)
{
return 0;
}
//network event
socketEvent = WSACreateEvent();
//program exit event
stopEvent = CreateEvent(NULL, FALSE, FALSE, NULL);
//Step 2. connect a server.the ip and port is server`s ip port
sockaddr_in addrServer = { 0 };
addrServer.sin_addr.S_un.S_addr = inet_addr("88.88.106.30");
addrServer.sin_port = htons(30001);
addrServer.sin_family = AF_INET;
//connect not bolock....
if (::connect(sock2Server, reinterpret_cast<const sockaddr*>
(&addrServer), sizeof addrServer) == SOCKET_ERROR)
{
return 1;
}
// bind event whith socket 接受到數據和服務器主動斷連都以事件通知
if (WSAEventSelect(sock2Server, socketEvent, FD_READ | FD_CLOSE) == 0)
{
mythread = CreateThread(0, 0, RecvThreadProc, (void *)sock2Server, 0, 0);
}
//main event is sleep to wait
Sleep(20000);
SetEvent(stopEvent);
//wait sub thread exit
Sleep(500);
::closesocket(sock2Server);
::WSACleanup();
return 0;
}