linux 进程通信 ：流套接字

消息队列是可以实现没有共同关系的进程之间的通信。Socket则可以实现不同计算机的不同进程之间的通信。

//地址的结构体
struct sockaddr_in{
    short int            sin_family;//AF_INET
    unsigned short int    sin_port;//端口号
    struct in_addr        sin_addr;//IP地址
};  

struct in_addr{
    unsigned long int s_addr;
};

几个重要的函数：

//创建socket
int socket(int domain, int type, int protocol);  

//命名（绑定）套接字 服务器采用
int bind( int socket, const struct sockaddr *address, size_t address_len);

//创建套接字队列（监听）
int listen(int socket, int backlog);  

//接受连接
int accept(int socket, struct sockaddr *address, size_t *address_len); 

//请求连接
int connect(int socket, const struct sockaddr *address, size_t address_len);

服务器接收来自客户的信息：

客户发送信息：

客户端代码：

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

int main(){

    int sockfd = -;
    struct sockaddr_in address;

        //创建套接字
    sockfd = socket(AF_INET, SOCK_STREAM, );

        //对地址结构体赋值
    address.sin_family = AF_INET;
    address.sin_addr.s_addr = inet_addr("127.0.0.1");
    address.sin_port = htons();

        //连接服务器的时候 要把套接字和地址结构传进去
    connect(sockfd, (struct sockaddr*)&address, sizeof(address));    

    printf("Connect OK!\n");

    printf("Enter a string\n");

    char buffer[];
    memset(buffer,'\0',);

    fgets(buffer,,stdin);

        //socketfd的用处在这里，通过write和read来读写数据

    write(sockfd,buffer,);

    memset(buffer,'\0',);

    read(sockfd,buffer,);

    printf("%s\n",buffer);

    close(sockfd);

}        

服务端代码：

#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h> 

int main(){

    int server_sockfd = -;
    int client_sockfd = -;

    struct sockaddr_in server_addr;
    struct sockaddr_in client_addr;

    server_sockfd = socket(AF_INET, SOCK_STREAM, );
    //internet    stream    protocol

    server_addr.sin_family = AF_INET;
        //接收任何地址
    server_addr.sin_addr.s_addr = htonl(INADDR_ANY);
    server_addr.sin_port = htons();

        //绑定才能被别人找到
    bind(server_sockfd, (struct sockaddr*)&server_addr, sizeof(server_addr));

        //创建队列
    listen(server_sockfd, );

    //create end

    while(){

        printf("Server start!\n");

        char buffer[];
        memset(buffer,'\0',);

        int client_len = sizeof(client_addr);

                //接收成功会返回客户的文件描述符 把客户的地址信息填到client_addr里面
        client_sockfd = accept(server_sockfd, (struct sockaddr*)&client_addr, &client_len);

                //调用子进程来处理
        if(fork()==){

            //in child process

            read(client_sockfd,buffer,);

            printf("client:\n");
            printf("%ld\n",client_addr.sin_addr.s_addr);
            printf("%d\n",client_addr.sin_port);
            printf("Message:%s\n",buffer);

            write(client_sockfd,"Get Message\n",);

            close(client_sockfd);

        }
        else{

            close(client_sockfd);

        }

    }

}