Linux系统下通过TCP与UDP方式建立简易的客户端与服务器之间的连接

TCP方式

1. 服务器函数

#include "head.h"
#define IP "192.168.31.38"
#define PORT 2023
int main(int argc, const char *argv[])
{    
    //创建套接字socket
    int sfd = socket(AF_INET,SOCK_STREAM,0);
    if(sfd<0)
    {
        ERR_MSG("socket");
        return -1;
    }
    fprintf(stderr,"socket sceeuss\n");


    //完善服务器信息struct sockaddr_in 
    struct sockaddr_in sin;
    sin.sin_family = AF_INET;
    sin.sin_port = htons(PORT);
    sin.sin_addr.s_addr = inet_addr(IP);

    //绑定端口以及IP bind
    if(bind(sfd,(struct sockaddr*)&sin,sizeof(sin))<0)
    {
        ERR_MSG("bind");
        return -1;
    }
    fprintf(stderr,"bind sceeuss\n");

    //将套接字设置为被动监听状态listen
    if(listen(sfd,128)<0)
    {
        ERR_MSG("listen");
        return -1;
    }
    fprintf(stderr,"listen sceeuss\n");

    //获取连接成功后的套接字accept
    //阻塞函数，等待客户端连接成功,并生产一个新的文件秒速符
    //定义结构体，存储客户端的地址信息
    struct sockaddr_in cin;
    socklen_t addrlen = sizeof(cin);
    int newsfd_1 = -1;
    newsfd_1 = accept(sfd,(struct sockaddr*)&cin,&addrlen);
    if(newsfd_1<0)
    {
        ERR_MSG("accept");
        return -1;
    }
    fprintf(stderr,"accept sceeuss\n");


    char buf[128] = "";
    ssize_t res;
    while(1)
    {
    bzero(buf,sizeof(buf));
    //接收客户端的信息recv
    res = recv(newsfd_1,buf,sizeof(buf),0);
    if(res<0)
    {
        ERR_MSG("recv");
        return -1;
    }
    else if(0==res)
    {
        fprintf(stderr,"k=客户端断开连接\n");
    }
    fprintf(stderr,"recv sceeuss\n");

    //向客户端发送信息send
    bzero(buf,sizeof(buf));
    strcpy(buf,"sceeuss");
    if(send(newsfd_1,buf,sizeof(buf),0)<0)
    {
        ERR_MSG("send");
        return -1;
    }
    fprintf(stderr,"send sceeuss\n");
    }


    //关闭套接字
    close(sfd);
    close(newsfd_1);
    return 0;
}

1. 客户端的函数

#include "head.h"
#define PORT 2023
#define CLI_PORT 2024
#define IP "192.168.31.38"
int main(int argc, const char *argv[])
{
    //创建套接字
    int cfd = socket(AF_INET,SOCK_STREAM,0);
    if(cfd<0)
    {
        ERR_MSG("socket");
        return -1;
    }
    fprintf(stderr,"socket sccuess\n");

    struct sockaddr_in sin;
    sin.sin_family = AF_INET;
    sin.sin_port = htons(PORT);
    sin.sin_addr.s_addr = inet_addr(IP);

    //不用绑定IP与端口
    //连接服务器
    if(connect(cfd,(struct sockaddr*)&sin,sizeof(sin))<0)
    {
        ERR_MSG("connect");
        return -1;
    }
    fprintf(stderr,"connect sccuess\n");


    char buf[128] = "";
    ssize_t res;
    printf("请输入传输的数据:\n");
    while(1)
    {    
    //发送信息
    bzero(buf,sizeof(buf));
    scanf("%s",buf);
    if(0==strcmp(buf,"quit"))
    {
        fprintf(stderr,"客户端退出\n");
        return -1;
    }
    if(send(cfd,buf,sizeof(buf),0)<0)
    {
        ERR_MSG("send");
        return -1;
    }
    fprintf(stderr,"send sccuess\n");

    
    //接受服务器信息
    res = recv(cfd,buf,sizeof(buf),0);
    if(res<0)
    {
        ERR_MSG("recv");
        return -1;
    }
    else if(0==res)
    {
        fprintf(stderr,"服务器退出\n");
    }
    fprintf(stderr,"recv sccuess\n");

    }

UDP方式

1. 服务器函数

#include "head.h"
#define IP "192.168.31.38"
#define PORT 6666
int main(int argc, const char *argv[])
{
    //创建套接字 socket
    int sfd=socket(AF_INET,SOCK_DGRAM,0);
    if(sfd<0)
    {
        ERR_MSG("socket");
        return -1;
    }
    fprintf(stderr,"socket sceeuss\n");

    //填充服务器自身的地址信息结构体
    struct sockaddr_in sin;
    sin.sin_family = AF_INET;
    sin.sin_port = htons(PORT);
    sin.sin_addr.s_addr = inet_addr(IP);

    socklen_t addrlen = sizeof(sin);
    //绑定IP以及端口 bind
    if(bind(sfd,(struct sockaddr*)&sin,addrlen)<0)
    {
        ERR_MSG("bind");
        return -1;
    }
    fprintf(stderr,"bind sceeuss\n");


    char buf[128]="";
    struct sockaddr_in cin;
    socklen_t addrlen_c = sizeof(cin);
    while(1)
    {
    bzero(buf,sizeof(buf));

    //接受recvfrom
    ssize_t res=recvfrom(sfd,buf,sizeof(buf),0,(struct sockaddr*)&cin,&addrlen_c);
    if(res<0)
    {
        ERR_MSG("recvfrom");
        return -1;
    }
    else if(0==res)
    {
        fprintf(stderr,"客户端已关闭\n");
        return -1;
    }
    if(0==strcmp(buf,"quit"))
    {
        fprintf(stderr,"客户端退出\n");
    }
    else
    {
    printf("连接成功\n");
    }
    printf("ser=%s\n",buf);
//    fprintf(stderr,"recvfrom sceeuss\n");



    //发送sendto
    strcat(buf,"***");
    if(sendto(sfd,buf,sizeof(buf),0,(struct sockaddr*)&cin,addrlen_c)<0)
    {
        ERR_MSG("sendto");
        return -1;
    }
//    fprintf(stderr,"sendto sceeuss\n");
    }
    //关闭套接字 close
    close(sfd);
    return 0;
}

1. 客户端函数

#include "head.h"
#define IP "192.168.31.38"
#define PORT 6666
#define CLI_PORT 7777
int main(int argc, const char *argv[])
{
    //创建套接字 socket
    int sfd=socket(AF_INET,SOCK_DGRAM,0);
    if(sfd<0)
    {
        ERR_MSG("socket");
        return -1;
    }
    fprintf(stderr,"socket sceeuss\n");

    //填充客户端自身的地址信息结构体
    struct sockaddr_in cin;
    cin.sin_family = AF_INET;
    cin.sin_port = htons(CLI_PORT);
    cin.sin_addr.s_addr = inet_addr(IP);

    socklen_t addrlen_c = sizeof(cin);
    //绑定IP以及端口 bind
    //如果不绑定 操作系统会自动绑定本机IP，随机使用一个
    
    if(bind(sfd,(struct sockaddr*)&cin,addrlen_c)<0)
    {
        ERR_MSG("bind");
        return -1;
    }
    
//    fprintf(stderr,"bind sceeuss\n");
    struct sockaddr_in sin;  
    sin.sin_family = AF_INET;
      sin.sin_port = htons(PORT);           
      sin.sin_addr.s_addr = inet_addr(IP);
    char buf[128]="";
    socklen_t addrlen = sizeof(sin);    

    //存储客户端发过来的数据
    struct sockaddr_in recvaddr;
    socklen_t recvlen = sizeof(recvaddr); 

    while(1)
    {
    bzero(buf,sizeof(buf));
    printf("请输入数据：\n");
    scanf("%s",buf);
    //发送sendto
    if(sendto(sfd,buf,sizeof(buf),0,(struct sockaddr*)&sin,addrlen)<0)
    {
        ERR_MSG("sendto");
        return -1;
    }
    if(0==strcmp(buf,"quit"))
    {
        fprintf(stderr,"客户端退出\n");
        return -1;
    }
//    fprintf(stderr,"sendto sceeuss\n");
    
    //接受recvfrom
    ssize_t res=recvfrom(sfd,buf,sizeof(buf),0,(struct sockaddr*)&recvaddr,&recvlen);
    if(res<0)
    {
        ERR_MSG("recvfrom");
        return -1;
    }
    else if(0==res)
    {
        fprintf(stderr,"服务器已关闭\n");
        return -1;
    }
//    fprintf(stderr,"recvfrom sceeuss\n");
    printf("cli=%s\n",buf);
    }
    //关闭套接字 close
    close(sfd);
    return 0;
}