初试linux下的Socket通信（下）

自己动手写客户端程序

同样是实现上篇的功能，客户端程序不再用telnet，自己写代码实现，服务器端程序也需要修改下

1. 服务器程序

#include  <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <sys/socket.h>
#include <arpa/inet.h>

void error(char *msg)
{
    fprintf(stderr, "%s :  %s\n", msg, strerror(errno) );
    exit(1);
}

int open_listener_socket(void)
{
    int s = socket(PF_INET,  SOCK_STREAM, 0); //创建服务器Socket ,  Ipv4协议，面向连接通信，TCP协议
    if (s == -1)
        error("scoket open error");
    return s;
}

void bind_to_port(int socket, int port)
{
    struct sockaddr_in name;  //服务器网络地址结构体
    name.sin_family = PF_INET;
    name.sin_port = (in_port_t)htons(port);          // 服务器端口号
    name.sin_addr.s_addr = htonl(INADDR_ANY);  //服务器地址，允许连接到所有本地连接上

    // 设置socket能重新使用已经绑定过的接口
    int reuse = 1;
    if ( setsockopt(socket, SOL_SOCKET, SO_REUSEADDR, (char *)&reuse, sizeof(int)) == -1)
        error(" cant set the reuse option on the scoket");

    //将服务器socket绑定到网络地址上
    int c = bind(socket, (struct sockaddr*) &name, sizeof(name));
    if (c == -1)
        error("cant bind to socket");
}

int sent_msg_to_client(int socket, char *s)
{
    int result = send(socket, s, strlen(s), 0);
    if (result == -1)
        fprintf(stderr, "%s :  %s\n", "error talking to client", strerror(errno) );
    return result;
}

int main(int argc, char const *argv[])
{
    int server_sockfd;
    int len;

    server_sockfd = open_listener_socket();
    bind_to_port(server_sockfd , 30000);

    // 监听连接请求，监听队列长度为10
    if (listen(server_sockfd , 10) == -1)
        error("cant listen");

    struct sockaddr_storage client_addr;   //client_addr 保存连接客户端的详细信息
    unsigned int address_size = sizeof(client_addr);
    puts("waiting for connection");
    char buf[255];
    //等待客户端连接请求到达
    int client_sockfd = accept(server_sockfd, (struct sockaddr *)&client_addr, &address_size);
    if (client_sockfd == -1)
        error("accept error");
    sent_msg_to_client( client_sockfd, "Welcome to my server\n>");
    while ((len = recv(client_sockfd, buf, sizeof(buf), 0)) > 0)
    {
        buf[len] = ‘\0‘;
        printf("%s\n", buf);
        if (strncasecmp("Who is there?", buf, 12))
            sent_msg_to_client(client_sockfd, "You should say ‘Who is there?‘ !\r\n>");
        else
        {
            sent_msg_to_client(client_sockfd, "Oscar\r\n>");
            while ((len = recv(client_sockfd, buf, sizeof(buf), 0)) > 0)
            {
                buf[len] = ‘\0‘;
                printf("%s\n", buf);
                if (strncasecmp("Oscar who?", buf, 9))
                {
                    sent_msg_to_client(client_sockfd, "You should say ‘Oscar who?‘ !\r\n>");
                    continue;
                }
                else
                {
                    sent_msg_to_client(client_sockfd, "Oscar silly question, you get a silly answer\r\n");
                    break;
                }

            }

        }

    }
    return 0;
}

1. 客户端程序

#include  <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <sys/socket.h>
#include <arpa/inet.h>

void error(char *msg)
{
    fprintf(stderr, "%s :  %s\n", msg, strerror(errno) );
    exit(1);
}

int open_listener_socket(void)
{
    int s = socket(AF_INET,  SOCK_STREAM, 0); //创建服务器Socket ,  Ipv4协议，面向连接通信，TCP协议
    if (s == -1)
        error("scoket open error");
    return s;
}

int main(int argc, char *argv[])
{
    int client_sockfd;
    char buf[255];
    int len;
    struct sockaddr_in client_addr; //客户端网络地址结构体

    client_addr.sin_family=PF_INET; //设置为IP通信
    client_addr.sin_addr.s_addr=inet_addr("127.0.0.1");//服务器IP地址
    client_addr.sin_port=htons(30000); //服务器端口号

    /*创建客户端套接字--IPv4协议，面向连接通信，TCP协议*/
    client_sockfd= open_listener_socket();
    /*将套接字绑定到客户端的网络地址上*/

    if(connect(client_sockfd,(struct sockaddr *)&client_addr,sizeof(struct sockaddr)) == -1)
    {
        error("cant connected to server");
    }
    puts("connected to server\n");
    len=recv(client_sockfd,buf,BUFSIZ,0);//接收服务器端信息
            buf[len]=‘\0‘;
    printf("%s",buf); //打印服务器端信息

    while(1)
    {
        //scanf("%s",buf);
        gets(buf);
        if(!strcmp(buf,"quit"))
            break;
        len=send(client_sockfd,buf,strlen(buf),0);

        len=recv(client_sockfd,buf,BUFSIZ,0);
        buf[len]=‘\0‘;
        printf("%s",buf);

    }
    close(client_sockfd);//关闭套接字

         return 0;
}