通过网络套接字实现客户机和服务器的通信.c

/*通过网络套接字实现服务器与主机的通信，客户端向主机
 *发送数据，服务器读取客户端数据，并将小写字母转化为
 大写返回给客户端
 * */
 /* 服务器*/
# include <stdio.h>
# include <sys/types.h>  
# include <sys/socket.h>
# include <netinet/in.h>
# include <arpa/inet.h>
# include <unistd.h>
# include <stdlib.h>
# include <string.h>

#define _DEBUG 0

# define PORT 8080

void work(char *buf){
    char *p = buf ;
    while(*p){
    if ('a'<=*p&&*p<='z'){
        *p+='A'-'a';
    }
        p++;
    }
}

int main ()
{
    int ret ;
    char buf[1024];
    close(0);
//step 1 :创建套接字
    int server_fd;
    int client_fd;

    server_fd = socket (AF_INET ,SOCK_STREAM ,0 ) ;
    if (server_fd==-1){
    perror("socket is failed\n");
    exit(0);
    }
#ifdef DEBUG
    printf ("socket is susses\n");
#endif

//step 2 :设置服务器地址
    struct sockaddr_in sockaddr_server;
    struct sockaddr_in sockaddr_client ;

    sockaddr_server.sin_family = AF_INET;
    sockaddr_server.sin_port = htons(PORT);
    sockaddr_server.sin_addr.s_addr = INADDR_ANY;
//step 3:绑定套接字
     ret = bind (server_fd,(struct sockaddr*)&sockaddr_server,sizeof(sockaddr_server));
        if (ret ==-1){
        perror ("bind is failed\n");
        exit(0);
        }
#ifdef DEBUG
        printf ("bind is susses\n");
#endif
//step 4 :设置队列
    ret = listen (server_fd, 10);
        if (ret ==-1){
        perror("listen is failed\n");
        exit(0);
        }
#ifdef DEBUG
        printf ("listen is susses\n");
#endif
//step 5 :等待客户端连接
b:        printf ("waitting for client\n") ;
        socklen_t sockaddr_len = sizeof (sockaddr_server);
        client_fd = accept(server_fd, (struct sockaddr*)&sockaddr_client, &sockaddr_len);
        if (client_fd== -1){
        perror("accept is failed\n");
        exit(0);
        }
        printf ("\naccept is susses\n");
//step end
//处理数据，即服务器读取客户端数据，将小写字母转化为大写 返回给客户端
        while(1){
        ret = read (client_fd,buf,sizeof(buf)-1);
        buf[ret]=0;
        if(ret == -1){
        perror("read is failed \n");
        exit(0);
        }
        if(ret==0){
        printf("client is closed\n");
        goto b ;
        }
        else{
        printf ("received %d bytes,they are  %s\n",ret,buf);
        work(buf);
        }
        ret = write(client_fd,buf,sizeof(buf));
        if (ret == -1){
        perror ("write is failed \n");
        exit(0);
        }
        }
        return 0 ;
}
----------------------------------------------------------------------------------------------------------------

/*通过网络套接字实现服务器与主机的通信，客户端向主机
 *发送数据，服务器读取客户端数据，并将小写字母转化为
  大写返回给客户端
 * */
 /* 客户端*/

# include <stdio.h>
# include <sys/types.h> 
# include <sys/socket.h>
# include <netinet/in.h>
# include <arpa/inet.h>
# include <unistd.h>
# include <stdlib.h>
# include <string.h>

# define MYIP "192.168.220.131"
# define PORT 8080
# define _DEBUG 0

int main(void)
{
    int client_fd;
    int ret ;
    char buf[1024];
//setp 1 创建网络套接字
    client_fd = socket(AF_INET,SOCK_STREAM,0);
    if ( client_fd <0){
        perror("scoket is faild \n");
        exit(0);
    }
#ifdef DEBUG
        printf("socket is sucess\n");
#endif
//setp 2 套接字地址
    struct sockaddr_in addr_server; //定义
                                                              
    addr_server.sin_family = AF_INET ; //类型
    addr_server.sin_addr.s_addr = inet_addr(MYIP); //IP
    addr_server.sin_port = htons( PORT) ; //端口
//setp 3 连接到服务器

   ret = connect (client_fd , (struct sockaddr*)&addr_server ,sizeof(addr_server)) ;
       if (ret == -1){
        perror ("connect faild \n") ;
        exit(0);
    }
#ifdef DEBUG
        printf("connect is sucess\n");
#endif
    printf ("server is connectd \n");
//step end
//处理数据，向服务器发送数据，并打印出服务器返回的数据
    while(1){
    printf ("input strings:\n");
    fgets (buf,sizeof(buf),stdin);
    write(client_fd,buf,strlen(buf));
    read(client_fd,buf,sizeof(buf));
    printf ("%s\n",buf);
    }
    return 0 ;
}