简单的客户端/服务端

//服务端
#include <iostream>  
#include <string>  
#include <fstream>
using namespace std;

#ifdef WINDOWS_SOCK
#include <winsock2.h>  
#pragma comment(lib,"ws2_32.lib")  

#define socklen_t int
#else
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <fcntl.h>
#define SOCKET int
#define SOCKET_ERROR -1
#define INVALID_SOCKET ~0
#endif

#define PORT 8080 
/* 
*socket 服务器端  
*/   
int main()  
{  
#ifdef WINDOWS_SOCK

    //1.winows sock init
    WORD word = MAKEWORD(2,2);
    WSADATA wsaData;  
    //异步sock初始化,0成功
    int err = WSAStartup(word, &wsaData);
    if(err!=0)  
    {  
        printf("Failed to load Winsock./n");  
        return -1;  
    }  

#endif
    
    //2.sock
    //AF_INET为ipv4地址32位与端口16位。SOCK_STREAM为TCP连接。IPPROTO_TCP为TCP传输协议
    SOCKET sockListen = socket(AF_INET,SOCK_STREAM, 0);//创建服务器端套接口  
    if(sockListen == INVALID_SOCKET)  
    {  
        printf("socket() Failed");  
        return -1;  
    }  

#ifdef WINDOWS_SOCK
    //iMode为0则阻塞，非0不阻塞
    u_long iMode = 0;
    if(ioctlsocket(sockListen, FIONBIO, &iMode) != NO_ERROR)
    {
        printf("ioctlsocket error");    
    }
#else
    int flags = fcntl(sockListen, F_GETFL, 0);
    //0为阻塞，flags | O_NONBLOCK为非阻塞
    //if (fcntl(sockListen, F_SETFL, flags | O_NONBLOCK) < 0)
    if (fcntl(sockListen, F_SETFL, 0) < 0)
    {
        printf("fcntl error!");
    }
#endif


    //3.bind
    sockaddr_in addr;//服务器和客户的地址  
    memset(&addr, 0, sizeof(addr));
    //使用IP地址族  
    addr.sin_family = AF_INET;  
    //使用htons()把双字节主机序端口号转换为网络字节序端口号  
    addr.sin_port = htons(PORT);  
    //htonl()把一个四字节主机序IP地址转换为网络字节序主机地址  
    //使用系统指定的IP地址INADDR_ANY  
    addr.sin_addr.s_addr = htonl(INADDR_ANY);  
    //bind()函数进行套接定与地址的绑定,成功为0 
    if(bind(sockListen,(sockaddr*)&addr, sizeof(addr)) == SOCKET_ERROR)  
    {  
        printf("bind() Failed /n");  
        return -1;  
    }  

    //4.listen
    //进入监听状态,监听数量5,正确返回0  
    if(listen(sockListen, 5) == SOCKET_ERROR)  
    {  
        printf("lisiten() Failed/n");  
        return -1;  
    }  

    //5.accept
    //初始化客户地址长度参数  
    //进入一个无限循环，等待客户的连接请求  
    SOCKET sockAccept;
    while(1)  
    {  
        sockaddr_in addrClient;//服务器和客户的地址  
        socklen_t iLen = sizeof(sockaddr_in);  
        sockAccept = accept(sockListen, (struct sockaddr *)&addrClient, &iLen);  
        if(sockAccept == INVALID_SOCKET)  
        {  
            printf("accept() Failed: /n");  
            continue;
        }  

        //输出客户IP地址和端口号  
        printf("Accepted client IP:[%s],port:[%d]/n",inet_ntoa(addrClient.sin_addr),ntohs(addrClient.sin_port));  
        //给连接的客户发送信息  

        //6.send
        char buf[1024] = "I am a server";//要发送给客户的信息  
        int iSend;
        ifstream ifs("msg.txt", ifstream::in);    
        if(ifs.is_open())
        {
            string s;
            while (getline(ifs, s))
            {
                iSend = send(sockAccept, s.c_str(), s.size(),0);  

                if(iSend == SOCKET_ERROR)
                {
                    cout<<"send error"<<endl;
                }
                else if(iSend == 0)
                {
                    cout<<"isend == 0"<<endl;
                    continue;
                }
                else
                {
                    cout<<s<<"size:"<<strlen(buf)<<endl;
                }
            }
        }
        
#ifdef WINDOWS_SOCK
        closesocket(sockAccept);  
#else
        close(sockAccept);
#endif
    }  

#ifdef WINDOWS_SOCK
    closesocket(sockListen);  
    WSACleanup();
#else
    close(sockListen);
#endif

    return 0;  
} 



//客户端
#include <iostream>  
#include <string>  

#ifdef WINDOWS_SOCK
#include <winsock2.h>  
#pragma comment(lib,"ws2_32.lib")  

#define socklen_t int
#else
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#define SOCKET int
#define SOCKET_ERROR -1
#define INVALID_SOCKET ~0
#endif
using namespace std;  

#define PORT 8080
#define DATA_BUFFER 1024
/* 
*客户端 
*/  
int main()  
{     
    int iLen;//从服务器端接收的数据长度  
    struct sockaddr_in addr;//服务器端地址  
    char buf[DATA_BUFFER];//接收数据的缓冲区  
    memset(buf,0,sizeof(buf));//接收缓冲区初始化  

#ifdef WINDOWS_SOCK
    WSADATA wsaData;  
    if(WSAStartup(MAKEWORD(2,2),&wsaData)!=0)  
    {  
        printf("Failed to load Winsock./n");  
        return -1;  
    }  
#endif

    //1.socket
    //建立客户端流式套接口  
    SOCKET sockClient = socket(AF_INET,SOCK_STREAM, 0);  

    if(sockClient == INVALID_SOCKET)  
    {  
        printf("socket() Failed /n");  
        return -1;  
    }  

    //2.connect请求与服务器端建立TCP连接  
    addr.sin_family = AF_INET;  
    addr.sin_port = htons(PORT);  
    //inet_addr()将命令行中输入的点分IP地址转换为二进制表示的网络字节序IP地址  
    addr.sin_addr.s_addr = inet_addr("127.0.0.1");  

    if(connect(sockClient,(struct sockaddr *)&addr, sizeof(addr)) == INVALID_SOCKET)  
    {  
        printf("connect() Failed \n");  
    }  
    else  
    {  
        //send
        string s = "hello, come from client!";
        int slen = strlen(s.c_str());
        {
            iLen = send(sockClient, s.c_str(), slen, 0);
            if (iLen == 0)
            {
                cout<<"send 0"<<endl;
            }
            else if (iLen < 0)
            {
                cout<<"send -1"<<endl;
            }
            else
            {
                cout<<"send: "<<iLen<<endl;
            }

        }

        //recv
        while(true)
        {
            iLen = recv(sockClient,buf,sizeof(buf),0);  
            if(iLen == 0)
            {
                cout<<"iLen = 0"<<endl;
                break;
                //continue;
            }
            else if ( iLen == SOCKET_ERROR)
            {
                cout<<"recv() failed"<<endl;
                return -1;
            }
            else
            {
                buf[iLen] = ‘\0‘;
                cout<<"length:"<<iLen<<" buf:"<<buf<<endl;
            }

        }
    }  

#ifdef WINDOWS_SOCK
    closesocket(sockClient);  
    cout<<"sock close"<<endl;
    WSACleanup();
#else
    close(sockClient);
#endif

    system("pause");
    return 0;  
}