我应该让服务器将从客户端获取的消息广播到所有其他连接的客户端。
实际广播有效，但我不知道如何阻止客户端无限打印“[客户端]从朋友那里收到：”当我按CTRL + C服务器时，
OR
当我按CTRL + C任何连接的客户端时，如何阻止服务器无限打印“[服务器]收到消息...”。或者如何在某处添加验证，以便客户端在尝试发送字符串“quit”时断开连接
也许我要求太多，但是有人可以向我解释一下select（..）究竟做了什么？我知道它正在监视FD，但我无法完全理解1秒后发生的事情（一步一步）。它是否通过所有FD，每次1秒然后重复？我有点想法，但并不完全。 谢谢你
SERVER
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <netinet/in.h>
#include <unistd.h>
#include <errno.h>
#include <stdio.h>
#include <arpa/inet.h>
#include <string.h>
#include <stdlib.h>
#define PORT 3050 //The port used by Clients
extern int errno;
char * conv_addr (struct sockaddr_in address)
{
static char str[25];
char port[7];
strcpy (str, inet_ntoa (address.sin_addr)); /* client IP */
bzero (port, 7); /* PORT */
sprintf (port, ":%d", ntohs (address.sin_port));
strcat (str, port);
return (str);
}
void Msgs(int fd,int sd,fd_set fds,int nr);
int main ()
{
struct sockaddr_in server_addr; /* struct for Server */
struct sockaddr_in client_addr; /* struct for Clients */
fd_set readfds; /* ready-to-read File Descriptors */
fd_set actfds; /* active/existant File Descriptors */
struct timeval tv; /* time thing, for select() */
int ServerSocketFD, ClientSocketFD; /* Socket descriptors */
int optval=1; /* ????*/
int fd; /* FD used to pass through all FDs */
int nfds; /* max number of FDs */
(ServerSocketFD = socket (AF_INET, SOCK_STREAM, 0));
setsockopt(ServerSocketFD, SOL_SOCKET, SO_REUSEADDR, &optval, sizeof(optval) );
bzero (&server_addr, sizeof (server_addr));
server_addr.sin_family = AF_INET;
server_addr.sin_addr.s_addr = htonl (INADDR_ANY);
server_addr.sin_port = htons (PORT);
bind (ServerSocketFD, (struct sockaddr *) &server_addr, sizeof(struct sockaddr) );
listen (ServerSocketFD, 5); //listen to maximum 5 clients,no more
FD_ZERO (&actfds);
FD_SET (ServerSocketFD, &actfds); /* Add the only existant one for now */
tv.tv_sec = 1; /* wait 1s */
tv.tv_usec = 0;
nfds = ServerSocketFD; /* max value of currently used FDs */
printf ("[server] Waiting at port :%d...\n", PORT);
fflush (stdout);
while (1) /* serve clients CONCURRENTLY */
{
bcopy ((char *) &actfds, (char *) &readfds, sizeof (readfds)); /* copy all existing FDs in actfds vector to the read-to-read-FDs vector */
select(nfds+1, &readfds, NULL, NULL, &tv);
if (FD_ISSET (ServerSocketFD, &readfds)) /* if ServerSocket is ready to read stuff */
{
bzero (&client_addr, sizeof (client_addr));
int len = sizeof (client_addr);
ClientSocketFD = accept (ServerSocketFD, (struct sockaddr *) &client_addr, &len);
if (nfds < ClientSocketFD) /* adjust max FD, for select */
nfds = ClientSocketFD;
/* Add this accepted sockets' FD to the existing FDs */
FD_SET (ClientSocketFD, &actfds);
printf("[server] Client connected, with FD %d, from this address %s.\n",ClientSocketFD, conv_addr (client_addr));
fflush (stdout);
}
for (fd = 0; fd <= nfds; fd++) /* all FDs*/
{
if (fd != ServerSocketFD && FD_ISSET (fd, &readfds)) /* is a client ready to send/get messages? */
{
Msgs(fd,ServerSocketFD,actfds,nfds);
}
}
}
}
void Msgs(int fd,int ServerSocketFD,fd_set fds,int nrFD)
{
char buffer[100];
int bytes;
char msg[100];
bytes = read (fd, msg, sizeof (buffer));
/*
if(strstr(msg,"quit")!=0)
{
FD_CLR(fd, &fds);
close(fd);
exit(1);
}
*/
printf ("[server]Message received...%s\n", msg);
for(int i=0;i<=nrFD;i++)
{
if(i!=fd && i!=ServerSocketFD)
{
write (i, msg, bytes);
}
}
}
客户端
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <errno.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <netdb.h>
#include <string.h>
#include <arpa/inet.h>
extern int errno;
int port;
int main (int argc, char *argv[])
{
int ClientSocketFD;
struct sockaddr_in server_addr;
char msg[100];
char reply[100];
if (argc != 3)
{
printf ("[client] Sintax: %s <server_address> <port>\n", argv[0]);
return -1;
}
port = atoi (argv[2]);
ClientSocketFD = socket (AF_INET, SOCK_STREAM, 0);
server_addr.sin_family = AF_INET;
server_addr.sin_addr.s_addr = inet_addr(argv[1]);
server_addr.sin_port = htons (port);
connect(ClientSocketFD, (struct sockaddr *) &server_addr,sizeof (struct sockaddr));
int pid;
if((pid=fork())==-1)
{
perror("Error fork()");
exit(10);
}
if(pid==0) //CHILD
{
while(1)
{
bzero(msg,100);
printf ("[client]Send something to other clients: ");
fflush (stdout);
read (0, msg, 100);
if(strstr(msg,"quit")!=0)
{
break;
}
write (ClientSocketFD, msg, 100);
}
exit(7);
}
else if(pid > 0) //PARENT
{
while(1)
{
bzero(reply,100);
read (ClientSocketFD, reply, 100);
printf ("[client]Received from friends: %s\n", reply);
}
}
close (ClientSocketFD);
}
答案 0 :(得分：0)
我不知道如何在我CTRL + C服务器时阻止客户端无限打印“ [从朋友那里收到的：]”
read()如果服务器终止则返回0，因此将客户端PARENT中的while(1)循环替换为
while (bzero(reply, 100), read(ClientSocketFD, reply, 100) > 0)
printf("[client]Received from friends: %.100s\n", reply);
kill(pid, SIGTERM); // terminate also the child
（和#include <signal.h>）。
当我CTRL + C任意一个连接的客户端时，如何阻止服务器无限打印“ [server]消息已接收...”
read()如果客户端终止，则返回0，请致电
Msgs(fd, ServerSocketFD, &actfds, nfds);
将Msgs()类型更改为
void Msgs(int fd, int ServerSocketFD, fd_set *fds, int nrFD)
并在Msgs()之后的bytes = read (fd, msg, sizeof (buffer));中添加
if (bytes <= 0) { FD_CLR(fd, fds); close(fd); return; }
有人可以告诉我select（..）到底做什么？我了解它正在监视FD，但是我无法完全了解1秒后发生的情况（逐步）。它是否通过所有FD，每个FD都需要1秒，然后重复执行？
正如wildplasser在他的评论中指出的那样，select()可能会更改超时参数以指示还剩多少时间，因此在没有FD活动的情况下经过1秒后，我们很可能最终会得到零超时和无用的繁忙循环。仅当我们想要在特定时间内没有任何受监视的FD准备就绪时做某事时，才需要select()超时，因此在您的情况下，最好完全不指定超时：
select(nfds+1, &readfds, NULL, NULL, NULL);