nonblocking socket 관련해서요.

int main( int argc , char **argv )
{
    char buf[2000];
    int nValue;
	int nRet;

	   gstServer.sin_family = AF_INET;
       gstServer.sin_port = htons( 7000 );
       if ( ( nRet = inet_pton( AF_INET , "192.168.10.220" , &gstServer.sin_addr ) ) < 0 )
        {
                perror( "inet_pton" );
								return -1;
        }
        else if ( nRet == 0 )
        {
                perror( "address is not valid." );
								return -1;
        }
lb_create_socket:
        while ( 1 )
        {
			    if ( ( gnSockfd = socket( AF_INET , SOCK_STREAM , 0 ) ) < 0 )
        		{
					perror( "socket call failed.\n" );
                	sleep( 1 );
					continue;
        		}
        		if ( ( gnConnfd = connect( gnSockfd , ( struct sockaddr * )&gstServer , sizeof ( struct sockaddr_in ) ) ) < 0 )
        		{
						    perror( "connect call failed" );
						    close( gnSockfd );
						    sleep( 1 );
						    continue;
        		}
       			break;
        } // end of while

        printf( "Realtime connect O.K.[%d][%d]\n" , gnSockfd , gnConnfd );
/* gnConnfd 가 0으로 나오거든요... 
0은 표준입력(stdin)의 번호인데 그럴수 있는건가요?*/
        
        // Non-blocking socket
        while ( 1 )
        {
        	if ( ( nValue = fcntl( gnConnfd , F_GETFL , 0 ) ) < 0 )
        	{
        	    perror( "fcntl( F_GETFL )" );
        	    sleep( 1 );
        		continue;
        	}
        	if ( ( nValue = fcntl( gnConnfd , F_SETFL , nValue | O_NONBLOCK ) ) < 0 )
        	{
        	    perror( "fcntl( F_SETFL O_NONBLOCK )" );
        	    sleep( 1 );
        		continue;
        	}
        	break;
       }
    SendTestData( argv[0] );
	return 0;
}

/*-------------------------------------------------------------------------
* FUNCTIONS   : SendTestData 
* SYNOPSIS    : 
* PARAMETERS  :
* returnS     :
* REMARKS     : TestData 전송
* ------------------------------------------------------------------------*/
int SendTestData( char *pData )
{
    int nSendMsgLen;
	int nwrite;
	int nread;
	socklen_t namelen;
    int nRet;
    int nValue;
    char *pbuf;  
    FILE *lfp;
    char buf[2000];
  
    printf( "%s" , "SendTestData ... start\n" );
    lfp = fopen( "testdata.txt" , "r" );
    while ( fgets( buf , sizeof buf , lfp ) )
    {
    /* Header setting */
    memset( gstSendDataMsg.szData , 0x00 , sizeof gstSendDataMsg.szData );
    SetSendMsgHeader( &gstSendDataMsg.stHeader , A_MSGID_DATA ); 
    memcpy( gstSendDataMsg.szData , buf , strlen( buf ) );
    nSendMsgLen = gstSendDataMsg.stHeader.stHeaderM.unMsgLen = strlen( buf );
    pbuf = (char*)&gstSendDataMsg;
    while ( nSendMsgLen )
    {
			if ( ( nwrite = write( gnConnfd , pbuf , nSendMsgLen ) ) < 0 )
			{
					if ( errno == EAGAIN )
					{
							fprintf( stderr , "EAGAIN write %s\n" , strerror( errno ) );
					}
					// error processing
					fprintf( stderr , "write %s\n" , strerror( errno ) );
					break;
			}
			else  /* if send is ok */
			{
					nSendMsgLen -= nwrite;
					pbuf += nwrite;
			}
    }
    }
    fclose( lfp );
    printf( "%s" , "SendTestData ... Good-Bye\n" );
	return 0;	
}

connect의 리턴값이 0으로 나오는데요...
stdin 과 중복해서 그런 값을 가질수 있나요?