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/*
* Demonstration of "accept after select" socket bug.
*
* This program works fine on:
* LinuxPPC, FreeBSD, and MacOSX
*
* This program does not work on:
* LinuxX86 Kernel 2.4
* (accept fails after select returns)
*
* This bug has something to do with the size of the
* variables on the stack...
* Getting rid of the union (which is unnecessary) seems
* to fix the problem.
*
*
* Jason Rohrer
* 2002-April-12
* rohrer@cse.ucsc.edu
*/
#include <sys/types.h>
#include <sys/time.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
union sock {
struct sockaddr s;
struct sockaddr_in i;
} sock;
void usage( char *inAppName );
int acceptConnection( int inSocketID, long inTimeoutMS );
int port;
int main( int inNumArgs, char **inArgs ) {
if( inNumArgs != 2 ) {
usage( inArgs[0] );
}
int numRead = sscanf( inArgs[1], "%d", &port );
// create a socket and start listening for connections
printf( "Creating socket\n" );
int socketID = socket( AF_INET, SOCK_STREAM, 0 );
if( socketID == -1 ) {
printf( "Socket creation failed\n" );
exit( 1 );
}
// bind socket to the port
union sock sockAddress;
sockAddress.i.sin_family = AF_INET;
sockAddress.i.sin_port = htons( port );
sockAddress.i.sin_addr.s_addr = INADDR_ANY;
printf( "Binding to socket at port %d\n", port );
int error = bind( socketID, &(sockAddress.s), sizeof( struct sockaddr ) );
if( error == -1 ) {
printf( "Bad socket bind, port %d\n", port );
exit( 1 );
}
// start listening for connections, max queued = 100 connections
printf( "Starting to listen to socket\n" );
error = listen( socketID, 100 );
if( error == -1 ) {
printf( "Bad socket listen\n" );
exit(1);
}
// no we're listening to this socket
int acceptedID = acceptConnection( socketID, 50000 );
if( acceptedID != -1 ) {
// close the connection
shutdown( acceptedID, SHUT_RDWR );
close( acceptedID );
}
shutdown( socketID, SHUT_RD );
return 1;
}
int acceptConnection( int inSocketID, long inTimeoutMS ) {
// use select to timeout if no connection received in 10 seconds
struct timeval tv;
socklen_t addressLength;
union sock acceptedAddress;
int acceptedID = accept( inSocketID,
&( acceptedAddress.s ), &addressLength );
if( acceptedID == -1 ) {
printf( "Failed to accept the connection\n" );
printf( "Error = %d\n", errno );
return -1;
}
else {
printf( "Successfully accepted the connection\n" );
return acceptedID;
}
}
void usage( char *inAppName ) {
printf( "Usage:\n" );
printf( " %s port_number\n", inAppName );
exit( 1 );
}
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