slp_xid.c

SLP协议在linux下的实现。此版本为1.2.1版。官方网站为www.openslp.org

/***************************************************************************/
/*                                                                         */
/* Project:     OpenSLP - OpenSource implementation of Service Location    */
/*              Protocol                                                   */
/*                                                                         */
/* File:        slplib_xid.c                                               */
/*                                                                         */
/* Abstract:    Internal implementation for generating unique XIDs.        */
/*              Provides functions that are supposed to generate 16-bit    */
/*              values that won't be generated for a long time in this     */
/*              process and hopefully won't be generated by other process  */ 
/*              for a long time.                                           */
/*                                                                         */
/*-------------------------------------------------------------------------*/
/*                                                                         */
/*     Please submit patches to http://www.openslp.org                     */
/*                                                                         */
/*-------------------------------------------------------------------------*/
/*                                                                         */
/* Copyright (C) 2000 Caldera Systems, Inc                                 */
/* All rights reserved.                                                    */
/*                                                                         */
/* Redistribution and use in source and binary forms, with or without      */
/* modification, are permitted provided that the following conditions are  */
/* met:                                                                    */ 
/*                                                                         */
/*      Redistributions of source code must retain the above copyright     */
/*      notice, this list of conditions and the following disclaimer.      */
/*                                                                         */
/*      Redistributions in binary form must reproduce the above copyright  */
/*      notice, this list of conditions and the following disclaimer in    */
/*      the documentation and/or other materials provided with the         */
/*      distribution.                                                      */
/*                                                                         */
/*      Neither the name of Caldera Systems nor the names of its           */
/*      contributors may be used to endorse or promote products derived    */
/*      from this software without specific prior written permission.      */
/*                                                                         */
/* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS     */
/* `AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT      */
/* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR   */
/* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE CALDERA      */
/* SYSTEMS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, */
/* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT        */
/* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;  LOSS OF USE,  */
/* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON       */
/* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT */
/* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE   */
/* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.    */
/*                                                                         */
/***************************************************************************/

#ifdef _WIN32
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#include <stdlib.h>
#else
#include <stdlib.h>
#include <unistd.h>
#endif

#include "slp_xid.h"
#include "slp_pid.h"

/*=========================================================================*/
int G_Xid = 0;
/* Global variable that is incremented before SLPGenerateXid() returns     */
/*=========================================================================*/


/*=========================================================================*/
void SLPXidSeed()
/* Seeds the XID generator.  Should only be called 1 time per process!     */
/* currently called when the first handle is opened.                       */
/*=========================================================================*/
{
/* Generate a random start*/
#ifdef _WIN32
srand(SLPPidGet() | G_Xid);   
G_Xid = (unsigned short)rand();
#else
srandom(SLPPidGet() | G_Xid);   
G_Xid = (unsigned short)random();
#endif
}


/*=========================================================================*/
unsigned short SLPXidGenerate()
/*                                                                         */
/* Returns: A 16-bit value                                                 */
/*=========================================================================*/
{
    G_Xid++;
    return G_Xid;
}