在C网络中,使用select我首先必须listen()和accept()？

概述我正在尝试允许多个客户端使用select连接到主机.我是否必须连接每个,告诉他们移动到另一个端口,然后重新连接新端口？或者会选择允许我将多个客户端连接到同一个端口？ 这是客户端代码： int rv;int sockfd, numbytes;if ((rv = getaddrinfo(hostName, hostPort, &hints, &servinfo)) != 0) { cou 我正在尝试允许多个客户端使用select连接到主机.我是否必须连接每个,告诉他们移动到另一个端口,然后重新连接新端口？或者会选择允许我将多个客户端连接到同一个端口？

这是客户端代码：

int rv;int sockfd,numbytes;if ((rv = getaddrinfo(hostname,hostPort,&hints,&servinfo)) != 0) {    cout << "Could not get server address.\n";    exit(1);}// loop through all the results and connect to the first we canfor(p = servinfo; p != NulL; p = p->ai_next) {    if ((sockfd = socket(p->ai_family,p->ai_socktype,p->ai_protocol)) == -1) {        perror("ClIEnt: no socket");        continue;    }    if (connect(sockfd,p->ai_addr,p->ai_addrlen) == -1) {        close(sockfd);        perror("ClIEnt: connect");        continue;    }    break;}if (p == NulL) {    fprintf(stderr,"Unable to connect to server.\n");    exit(2);}FD_SET(sockfd,&masterSet);

这是服务器代码：

int rv = getaddrinfo(NulL,port,&res);    int yes = 1;//Not sure what this is for,found it in Beej's    if(rv != 0){            cout<< "Error,nothing matches criteria for file descriptor.\n";            exit(1);    }    int fdInit;    for(temp = res; temp != NulL; temp = temp->ai_next){            if((fdInit = socket(temp->ai_family,temp->ai_socktype,temp->ai_protocol)) == -1){                    cout << "This is not the fd you're looking for.  Move along.\n";                    continue; //This is not the fd you're looking for,move along.            }            if(setsockopt(fdInit,Sol_SOCKET,SO_REUSEADDR,&yes,sizeof(int)) == -1){                    cout << "Doom has fallen upon this set socket.\n";                    perror("setsockopt");                    exit(1); //Unable to set socket,exit program with code 1            }            if(bind(fdInit,temp->ai_addr,temp->ai_addrlen) == -1){                    cout << "Could not bind fd\n";                    close(fdInit);                    continue; //Could not bind fd,continue looking for valID fd            }            break; //If a valID fd has been found,stop checking the List    }    if(temp==NulL){            cout<<"Server Failed to bind a socket\n";            exit(2);    }    cout << fdInit << endl;    //Setup the file descriptor for initial connections on specifIEd port    freeaddrinfo(res);    FD_SET(fdInit,&masterSet);

任何帮助都会很棒！谢谢.

解决方法 TCP连接由连接两端的IP地址和端口号标识.因此,有很多客户端(通常会随机分配端口号)连接到单个服务器端口.

你创建一个套接字并将它绑定到一个侦听()的端口,然后等待客户端敲响它.如果你不介意阻止你可以直接调用它上面的accept(),但你不会做任何超时循环或任何事情.否则,您可以在侦听套接字上选择(),当客户端尝试连接时,它将变为可读,然后调用accept().

accept()将返回一个新创建的套接字,这是与客户端通信的实际套接字.原始侦听套接字继续侦听,并且可以接受更多连接.

通常使用select()循环来查找侦听套接字和任何连接套接字的可读性.然后当select()返回时,只需检查监听套接字是否可读,如果是,则接受();否则寻找一个可读的连接套接字并处理它.

fd_set fds;int max = 0,reuse = 1;struct timeval tv;int server;std::vector<int> connected;// create server Listening socketserver = socket(PF_INET,SOCK_STREAM,getprotobyname("tcp")->p_proto);setsockopt(server,&reuse,sizeof(int)); // optional,but recommendedif (bind(server,(struct sockaddr *)&addr,sizeof(struct sockaddr_in)) < 0) {    // error,Could not bind server socket}if (Listen(server,8) < 0) {    // error,Could not Listen on server port}// loop looking for connections / data to handlewhile (running) {    FD_ZERO(&fds);    FD_SET(server,&fds);    if (server >= max) max = server + 1;    for (std::vector<int>::iterator it = connected.begin(); it != connected.end(); ++it) {        FD_SET(*it,&fds);        if (*it >= max) max = *it + 1;    }    tv.tv_sec = 2; tv.tv_usec = 0;    if (select(max,&fds,NulL,&tv) > 0) {        // something is readable        if (FD_ISSET(server,&fds)) {            // it's the Listener            connected.push_back(accept(server,(struct sockaddr *)&addr));        }        for (std::vector<int>::iterator it = connected.begin(); it != connected.end(); ++it) {            if (FD_ISSET(*it,&fds)) {                // handle data on this connection            }        }    }}

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