socket编程使用select的问题？
一个简单的程序：
Server端使用select监听多个Client，Client发数据给Server,Server把受到的数据打印出来。
出现的问题是：当只有一个Client连接时，无法收到Client端发来的数据，多个Client连接时则正常。
我是使用telnet做Client来测试的。
代码如下，各位老大帮看一下：
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <strings.h>
#include <sys/select.h>
#include <netdb.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#define BUF_SIZ 1024
int port = 2007;
int main()
{
/* local varibles */
int srv_skt_fd;
int clt_skt_fd;
fd_set set,read_set;
int max_fd;
int i;
char buf[BUF_SIZ];
int len;
struct sockaddr_in serv_addr;
struct sockaddr_in clt_addr;
/* program begin from here */
/* Step1: open a socket */
if ((srv_skt_fd = socket(AF_INET,SOCK_STREAM,0)) == -1)/* TCP socket */
{
perror( "socket open ");
exit(1);
}
/* Step2: bind it to host address */
bzero(&serv_addr,sizeof(serv_addr));
serv_addr.sin_family = AF_INET;
serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
serv_addr.sin_port = htons(port);
if (bind(srv_skt_fd,(struct sockaddr*)&serv_addr,sizeof(serv_addr)) == -1)
{
perror( "bind ");
close(srv_skt_fd);
exit(1);
}
/* Step3: listen */
if (listen(srv_skt_fd,SOMAXCONN) == -1)
{
perror( "listen ");
close(srv_skt_fd);
exit(1);
}
/* Step4: build a fd_set for select */
FD_ZERO(&set);
/* Step5: add server socket fd to this fd_set */
FD_SET(srv_skt_fd,&set);
max_fd = srv_skt_fd + 1;
/* Step6: write a infinite loop that call select and handle all requests */
while (1)
{
printf( "start\n ");
read_set = set;
/* wait for a request here */
if (select(max_fd,&read_set,NULL,NULL,NULL) == -1)
{
perror( "select ");
close(srv_skt_fd);
exit(1);
}
printf( "after select\n ");
/* cleck which one is coming */
for (i = 0;i < max_fd;i++)
{
/* Step7: case 1:if the request is from the server socket fd,
then accept it and add this new socket fd to fd_set
case 2:if the requeset is from a client, handle it;
*/
if (FD_ISSET(i,&read_set))
{
/* case 1 */
if (i == srv_skt_fd)
{
if ((clt_skt_fd = accept(srv_skt_fd,NULL,0)) == -1)
{
perror( "accept ");
close(srv_skt_fd);
exit(1);
}
printf( "accept a connection from client %d\n ",clt_skt_fd);
FD_SET(clt_skt_fd,&set);
if (clt_skt_fd > max_fd)
{
max_fd = clt_skt_fd + 1;
}
}else /* case 2 */
{
/* add your code here */
if ((len = recv(i,buf,BUF_SIZ,0)) == -1)
{
perror( "recv ");
close(srv_skt_fd);
exit(1);
}
if (len == 0)
{
FD_CLR(i,&set);
if ((i+1) == max_fd)
{
max_fd--;
}
close(i);
}else {
buf[len] = '\0 ';
printf( "got msg from %d: %s\n ",i,buf);
}
}
}
}
}
/* Step8: clean up */
return 0;
}
[解决办法]
srv_skt_fd这个，select监听我觉得应该是返回的clientsock和srv_skt_fd之间最大值加1；而不是本身监听端口加1；
