sockets - 服务器无法从多个客户端发送邮件?

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两个客户机可以连接到服务器,但只接受和显示第一个客户端的输入流消息。

接下来是我接受流的代码,我试图关闭每个套接字,但是它没有工作。


int main(int argc,char *argv[])
{
fd_set ready;
struct sockaddr_in msgfrom;
int msgsize;
union {
 uint32_t addr;
 char bytes[4];
} fromaddr;

if ((progname = rindex(argv[0], '/')) == NULL)
 progname = argv[0];
else
 progname++;
while ((ch = getopt(argc, argv,"adsp:h:"))!= -1)
 switch(ch) {
 case 'a':
 aflg++;/* print address in output */
 break;
 case 'd':
 soctype = SOCK_DGRAM;
 break;
 case 's':
 server = 1;
 break;
 case 'p':
 port = optarg;
 break;
 case 'h':
 host = optarg;
 break;
 case '?':
 default:
 usage();
 }
argc -= optind;
if (argc!= 0)
 usage();
if (!server && (host == NULL || port == NULL))
 usage();
if (server && host!= NULL)
 usage();
/*
 * Create socket on local host.
 */
if ((s = socket(AF_INET, soctype, 0)) <0) {
 perror("socket");
 exit(1);
}
sock = setup_server(); 
while (!done) {
 FD_ZERO(&ready);
 FD_SET(sock, &ready);
 FD_SET(fileno(stdin), &ready);
 if (select((sock + 1), &ready, 0, 0, 0) <0) {
 perror("select");
 exit(1);
 }
 if (FD_ISSET(fileno(stdin), &ready)) {
 if ((bytes = read(fileno(stdin), buf, BUF_LEN)) <= 0)
 done++;
 send(sock, buf, bytes, 0);
 }
 msgsize = sizeof(msgfrom);
 if (FD_ISSET(sock, &ready)) {
 if ((bytes = recvfrom(sock, buf, BUF_LEN, 0, (struct sockaddr *)&msgfrom, &msgsize)) <= 0) {
 done++;
 } else if (aflg) {
 fromaddr.addr = ntohl(msgfrom.sin_addr.s_addr);
 fprintf(stderr,"%d.%d.%d.%d:", 0xff & (unsigned int)fromaddr.bytes[0],
 0xff & (unsigned int)fromaddr.bytes[1],
 0xff & (unsigned int)fromaddr.bytes[2],
 0xff & (unsigned int)fromaddr.bytes[3]);
 }
 write(fileno(stdout), buf, bytes);
 }
}

下面是我设置服务器的代码,供参考:


int setup_server() {
struct sockaddr_in serv, remote;
struct servent *se;
int newsock, len;

len = sizeof(remote);
memset((void *)&serv, 0, sizeof(serv));
serv.sin_family = AF_INET;
if (port == NULL)
 serv.sin_port = htons(9990);
else if (isdigit(*port))
 serv.sin_port = htons(atoi(port));
if (bind(s, (struct sockaddr *)&serv, sizeof(serv)) <0) {
 perror("bind");
 exit(1);
}
if (getsockname(s, (struct sockaddr *) &remote, &len) <0) {
 perror("getsockname");
 exit(1);
}
fprintf(stderr,"Port number is %dn", ntohs(remote.sin_port));
listen(s, 1);
newsock = s;
if (soctype == SOCK_STREAM) {
 fprintf(stderr,"Entering accept() waiting for connection.n");
 newsock = accept(s, (struct sockaddr *) &remote, &len);
}
return(newsock);
}

客户端代码:


sock = setup_client();
/*
 * Set up select(2) on both socket and terminal, anything that comes
 * in on socket goes to terminal, anything that gets typed on terminal
 * goes out socket...
 */
while (!done) {
 FD_ZERO(&ready);
 FD_SET(sock, &ready);
 FD_SET(fileno(stdin), &ready);
 if (select((sock + 1), &ready, 0, 0, 0) <0) {
 perror("select");
 exit(1);
 }
 if (FD_ISSET(fileno(stdin), &ready)) {
 if ((bytes = read(fileno(stdin), buf, BUF_LEN)) <= 0)
 done++;
 send(sock, buf, bytes, 0);
 }
 msgsize = sizeof(msgfrom);
 if (FD_ISSET(sock, &ready)) {
 if ((bytes = recvfrom(sock, buf, BUF_LEN, 0, (struct sockaddr *)&msgfrom, &msgsize)) <= 0) {
 done++;
 } else if (aflg) {
 fromaddr.addr = ntohl(msgfrom.sin_addr.s_addr);
 fprintf(stderr,"%d.%d.%d.%d:", 0xff & (unsigned int)fromaddr.bytes[0], 0xff & (unsigned int)fromaddr.bytes[1],
 0xff & (unsigned int)fromaddr.bytes[2],
 0xff & (unsigned int)fromaddr.bytes[3]);
 }
 write(fileno(stdout), buf, bytes);
 }
//close(sock);
}
return(0);
}

/*
 * setup_client() - set up socket for the mode of soc running as a
 * client connecting to a port on a remote machine.
 */

int setup_client() {

struct hostent *hp, *gethostbyname();
struct sockaddr_in serv;
struct servent *se;

/*
 * Look up name of remote machine, getting its address.
 */
if ((hp = gethostbyname(host)) == NULL) {
 fprintf(stderr,"%s: %s unknown hostn", progname, host);
 exit(1);
}
/*
 * Set up the information needed for the socket to be bound to a socket on
 * a remote host. Needs address family to use, the address of the remote
 * host (obtained 上面), and the port on the remote host to connect to.
 */
serv.sin_family = AF_INET;
memcpy(&serv.sin_addr, hp->h_addr, hp->h_length);
if (isdigit(*port))
 serv.sin_port = htons(atoi(port));
else {
 if ((se = getservbyname(port, (char *)NULL)) <(struct servent *) 0) {
 perror(port);
 exit(1);
 }
 serv.sin_port = se->s_port;
}
/*
 * Try to connect the sockets...
 */
if (connect(s, (struct sockaddr *) &serv, sizeof(serv)) <0) {
 perror("connect");
 exit(1);
} else
 fprintf(stderr,"Connected...n");
return(s);
}

时间: 原作者:

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UDP是好的,你只能像正在做的那样。

TCP不同,但你几乎在那里: 如果你希望处理连接,需要调用 accept(),请在循环中的服务器套接字上单击 accept(),根据需要调用,并将它的与 close() 联系起来,并在结束时进行处理。

在客户端看起来好像已经连接好了,因为你处于挂起连接队列中--看到 listen(2) 页面。

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