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 can
for(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 socket
server = socket(PF_INET,SOCK_STREAM,getprotobyname("tcp")->p_proto);
setsockopt(server,&reuse,sizeof(int)); // optional,but recommended
if (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 handle
while (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
}
}
}
}
