网络编程知识点总结（7）

socket服务端和客户端实现多方消息收发

相关函数

（1）socket()函数

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

（2）bind()函数: IP号端口号与相应描述字赋值函数

int bind(int sockfd, const struct sockaddr *addr,socklen t addrlen);

（3）listen()函数:监听设置函数

int listen(int sockfd, int backlog);

（4）accept()函数

int accept(int sockfd, struct sockaddr *addr, socklen t *addrlen);

服务端代码实现：

#include 
#include           /* See NOTES */
#include 
//#include 
#include 
#include 
#include 
#include 

int main(int argc, char **argv)
{
        int s_fd;
        int c_fd;
        int n_read;
        char readBuf[128];

        int mark = 0;
        char msg[128] = {0};
        //      char *msg = "I get your connect";
        struct sockaddr_in s_addr;
        struct sockaddr_in c_addr;

        if(argc != 3){
                printf("param is not good\n");
               exit(-1);
        }

        memset(&s_addr,0,sizeof(struct sockaddr_in));
        memset(&c_addr,0,sizeof(struct sockaddr_in));

        //1. socket
        s_fd = socket(AF_INET, SOCK_STREAM, 0);
        if(s_fd == -1){
                perror("socket");
                exit(-1);
        }

        s_addr.sin_family = AF_INET;
        s_addr.sin_port = htons(atoi(argv[2]));
        inet_aton(argv[1],&s_addr.sin_addr);


        //2. bind
        bind(s_fd,(struct sockaddr *)&s_addr,sizeof(struct sockaddr_in));

        //3. listen
        listen(s_fd,10);
        //4. accept
        int clen = sizeof(struct sockaddr_in);
        while(1){

                c_fd = accept(s_fd,(struct sockaddr *)&c_addr,&clen);
                if(c_fd == -1){
                        perror("accept");
                }

                mark++;
                printf("get connect: %s\n",inet_ntoa(c_addr.sin_addr));

                if(fork() == 0){

                        if(fork()==0){
                                while(1){
                                        sprintf(msg,"welcom No.%d client",mark);
                                        write(c_fd,msg,strlen(msg));
										sleep(3);
                                }
                        }

                        //5. read
                        while(1){
                                memset(readBuf,0,sizeof(readBuf));
                                n_read = read(c_fd, readBuf, 128);
                                if(n_read == -1){
                                        perror("read");
                                }else if(n_read>0){
                                        printf("\nget:%s\n",readBuf);
                                }else{

                                        printf("client quit\n");
                                        break;
                                }
                        }
                        break;
                }

        }
        return 0;
}

客户端代码实现：

#include 
#include           /* See NOTES */
#include 
//#include 
#include 
#include 
#include 
#include 

int main(int argc, char **argv)
{
        int c_fd;
        int n_read;
        char readBuf[128];
        int tmp;

        //      char *msg = "msg from client";
        char msg[128] = {0};
        struct sockaddr_in c_addr;

        memset(&c_addr,0,sizeof(struct sockaddr_in));

        if(argc != 3){
                printf("param is not good\n");
                exit(-1);
        }

        printf("%d\n",getpid());
        //1. socket
        c_fd = socket(AF_INET, SOCK_STREAM, 0);
        if(c_fd == -1){
                perror("socket");
                exit(-1);
        }

        c_addr.sin_family = AF_INET;
        c_addr.sin_port = htons(atoi(argv[2]));
        inet_aton(argv[1],&c_addr.sin_addr);

        //2.connect     
        if(connect(c_fd, (struct sockaddr *)&c_addr,sizeof(struct sockaddr)) == -1){
                perror("connect");
                exit(-1);
        }
        while(1){

                if(fork()==0){
                        while(1){
                                memset(msg,0,sizeof(msg));
                                printf("input: ");
                                gets(msg);
                                write(c_fd,msg,strlen(msg));
                        }
                }

                while(1){
                        memset(readBuf,0,sizeof(readBuf));
                        n_read = read(c_fd, readBuf, 128);
                        if(n_read == -1){
                                perror("read");
                        }else{
                                printf("\nget:%s\n",readBuf);
                        }
                }
        }
        //3.send

        //4.read


        return 0;
}

编译结果：

连接一个

、

连接两个