在我的主要功能中，我创建了（使用教程等）迭代服务器，该服务器只是接收消息，然后将其返回给客户端。但是，我将fd_setsize传递到select（）函数中，我认为这实际上不是从最大值来增加文件描述符。
#include <dns_sd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdlib.h>
#include <time.h>
#include <math.h>
#include <string.h>
#include <errno.h>
#include <time.h>
#include <math.h>
#include <sys/select.h> /* <===== */
#ifdef _WIN32
#include <process.h>
typedef int pid_t;
#define getpid _getpid
#define strcasecmp _stricmp
#define snprintf _snprintf
#else
#include <sys/time.h> // For struct timeval
#include <unistd.h> // For getopt() and optind
#include <arpa/inet.h> // For inet_addr()
#endif
#include <netdb.h>
#include <sys/select.h>
#include <fcntl.h>
#include <err.h>
#define BUFFER_SIZE 1024
#define MAX_CLIENTS 100 /* <===== */
// ... lots of skipped code here
/**
* Creates a connection with a socket. It handles
* socket(), bind().
*
* @name create_socket
* @param server_addr the server address
*
*/
int create_socket(struct sockaddr_in* server) {
/* Create the listener socket as TCP socket */
int sock = socket(PF_INET, SOCK_STREAM, 0); //use protocol family, internet
if (sock < 0) {
perror("socket()");
exit(EXIT_FAILURE);
}
bzero(&*server, sizeof(*server)); // causing segault
//server->sin_family = PF_INET;
server->sin_family = AF_INET;
//server->sin_addr.s_addr = INADDR_ANY;
server->sin_addr.s_addr = htonl(INADDR_ANY);
unsigned short port = 8129;
server->sin_port = htons(port); //the port is chosen as the first available.
int len = sizeof(*server);
if (bind(sock, (struct sockaddr*) &*server, len) < 0) {
perror("bind()");
exit(EXIT_FAILURE);
}
return sock;
}
这是主要功能：
/** MAIN **/
int main()
{
/* Socket Structures */
struct sockaddr_in server, client, temp;
fd_set readfds;
int client_sockets[ MAX_CLIENTS ]; /* client socket fd list */
int client_socket_index = 0; /* next free spot */
/* Create the listener socket as TCP socket */
int sock = create_socket(&server);
listen(sock, 5); /* 5 is number of waiting clients */
//printf("Listener bound to port %dn", port);
printf("Started server; listening on port: %dn", local_port);
/** Read from and Write to the Client **/
int fromlen = sizeof( client );
char buffer[ BUFFER_SIZE ];
int i;
while ( 1 )
{
#if 1
struct timeval timeout;
timeout.tv_sec = 3;
timeout.tv_usec = 500; /* 3 AND 500 microseconds */
#endif
FD_ZERO( &readfds );
FD_SET( sock, &readfds ); // FD_SET to include listener fd, sock
for ( i = 0 ; i < client_socket_index ; i++ )
{
FD_SET( client_sockets[ i ], &readfds ); //Set FD_SET to include client socket fd
}
#if 0
/* BLOCK */
int ready = select( FD_SETSIZE, &readfds, NULL, NULL, NULL );
/* ready is the number of ready file descriptors */
printf( "select() identified %d descriptor(s) with activityn", ready );
#endif
#if 1
int ready = select( FD_SETSIZE, &readfds, NULL, NULL, &timeout );
if ( ready == 0 ) {
//printf( "No activityn" );
continue;
}
#endif
if ( FD_ISSET( sock, &readfds ) )
{
int newsock = accept( sock,
(struct sockaddr *)&client,
(socklen_t *)&fromlen );
/* this accept() call we know will not block */
printf( "Accepted client connectionn" );
client_sockets[ client_socket_index++ ] = newsock;
}
for ( i = 0 ; i < client_socket_index ; i++ )
{
int fd = client_sockets[ i ];
if ( FD_ISSET( fd, &readfds ) )
{
int n, guess, success;
/** Recieve user input, check for errors **/
n = recv( fd, buffer, BUFFER_SIZE - 1, 0 );
if ( n < 0 )
{
perror( "recv()" );
}
else if ( n == 0 )
{
int k;
printf( "Client on fd %d closed connectionn", fd );
close( fd );
/* remove fd from client_sockets[] array: */
for ( k = 0 ; k < client_socket_index ; k++ )
{
if ( fd == client_sockets[ k ] )
{
/* found it -- copy remaining elements over fd */
int m;
for ( m = k ; m < client_socket_index - 1 ; m++ )
{
client_sockets[ m ] = client_sockets[ m + 1 ];
}
client_socket_index--;
break; /* all done */
}
}
} else {
buffer[n] = ' ';
printf("Recieved %s",buffer);
n = send(fd, buffer, strlen(buffer), 0);
/* Divide input into parts and get the guess */
}
}
}
}
return EXIT_SUCCESS; /* we never get here */
}
再进行几个小时的谷歌搜索，我弄清楚了！很小的变化。
while(1) {
//...
int maxfd = sock;
for ( i = 0; i < client_socket_index ; i++ )
{
int sd = client_sockets[i];
FD_SET( sd, &readfds ); //Set FD_SET to include client socket fd
if(sd > maxfd)
maxfd = sd;
}
int ready = select(maxfd+1, &readfds, NULL, NULL, &timeout );
}