socket编程

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <unistd.h>
#include <arpa/inet.h>
int main()
{
    printf("a server
");
    int listenfd = socket(AF_INET, SOCK_STREAM, 0);//创建一个socket描述符，唯一标识一个socket，socket()返回文件描述符
        0,1,2分别表示标准输入、标准输出、标准错误，所以其他打开的文件描述符都会大于2, 错误时就返回 -1
    if(listenfd == -1)
    {
        printf("error:socket
");
        return 0;
    }

    struct sockaddr_in addr;
    addr.sin_family = AF_INET;//IPV4
    addr.sin_port = htons(8000);//host to net，主机字节转为网络字节
    addr.sin_addr.s_addr = INADDR_ANY;//指定ip地址：所有地址
    if(bind(listenfd, (struct sockaddr*)&addr, sizeof(addr)) == -1)//bind()把地址和端口号组合赋给socket
    {
        printf("error:bind()
");
        return 0;
    }

    if(listen(listenfd, 5) == -1)//int listen( int sockfd/*用于标识一个已捆绑未连接套接口的描述字*/,
                                                             int backlog/*等待连接队列最大长度*/);
    {
        printf("error:listen
");
        return 0;
    }

    int conn;//客户端套接字描述字
    char clientIP[INET_ADDRSTRLEN];
    struct sockaddr_in clientAddr;
    socklen_t clientAddrLen = sizeof(clientAddr);
    while(1)
    {
        printf("listening......
");
        conn = accept(listenfd, (struct sockaddr*)&clientAddr, &clientAddrLen);//监听到之后，调用accept()
        if(conn < 0)
        {
            printf("error:accept
");
            continue;
        }
        inet_ntop(AF_INET/*IPV4*/, &clientAddr.sin_addr/*source*/, clientIP/*destination*/, INET_ADDRSTRLEN/*IP长度*/);
        /*在点分十进制和二进制整数转换*/ 
        printf("connect %s
",clientIP);//IP:port

        char buff[255];
        while(1)
        {
            for(int i=0; i<255; ++i)buff[i]=0;
            int len = recv(conn, buff/*存放接收数据*/, sizeof(buff), 0/*一般置零*/);
            buff[len] = '';
            if(!strcmp(buff,"exit"))
            {
                printf("disconnect
");
                return 0;
            }    
            printf("%s
",buff);
            for(int i=0; i<len; ++i)
            {
                buff[i] = toupper(buff[i]);
            }
            send(conn, buff, len, 0);
        }
        close(conn/*socket描述字*/);//关闭连接
    }
    close(listenfd);
    return 0;
}

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <unistd.h>
#include <arpa/inet.h>
int main() 
{
    printf("a client
");
    // socket
    int client = socket(AF_INET, SOCK_STREAM, 0);
    if (client == -1) 
    {
        printf("error:socket
");
        return 0;
    }
    // connect
    struct sockaddr_in serverAddr;
    serverAddr.sin_family = AF_INET;
    serverAddr.sin_port = htons(8000);
    serverAddr.sin_addr.s_addr = inet_addr("192.168.246.140");//连接到master
    if (connect(client, (struct sockaddr*)&serverAddr, sizeof(serverAddr)) < 0) 
    {
        printf("error:connect");
        return 0;
    }
    printf("connect
");
    char data[255];
    char result[255];
    while (1) 
    {
        scanf("%s",data);
        if(!strcmp(data,"exit"))
        {
            printf("disconnect");
            break;
        }
        send(client, data, strlen(data), 0);
        for(int i=0 ;i<sizeof(result);++i)result[i]=0;
        int len = recv(client, result, sizeof(result), 0);
        printf("result:%s
",result);
    }
    close(client);
    return 0;
}