xrootd/XrdSec/XrdSecAttr.hh

0001 #ifndef __SEC_ATTR_H__
0002 #define __SEC_ATTR_H__
0003 /******************************************************************************/
0004 /*                                                                            */
0005 /*                         X r d S e c A t t r . h h                          */
0006 /*                                                                            */
0007 /* (c) 2019 by the Board of Trustees of the Leland Stanford, Jr., University  */
0008 /*   Produced by Andrew Hanushevsky for Stanford University under contract    */
0009 /*              DE-AC02-76-SFO0515 with the Department of Energy              */
0010 /*                                                                            */
0011 /* This file is part of the XRootD software suite.                            */
0012 /*                                                                            */
0013 /* XRootD is free software: you can redistribute it and/or modify it under    */
0014 /* the terms of the GNU Lesser General Public License as published by the     */
0015 /* Free Software Foundation, either version 3 of the License, or (at your     */
0016 /* option) any later version.                                                 */
0017 /*                                                                            */
0018 /* XRootD is distributed in the hope that it will be useful, but WITHOUT      */
0019 /* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or      */
0020 /* FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public       */
0021 /* License for more details.                                                  */
0022 /*                                                                            */
0023 /* You should have received a copy of the GNU Lesser General Public License   */
0024 /* along with XRootD in a file called COPYING.LESSER (LGPL license) and file  */
0025 /* COPYING (GPL license).  If not, see <http://www.gnu.org/licenses/>.        */
0026 /*                                                                            */
0027 /* The copyright holder's institutional names and contributor's names may not */
0028 /* be used to endorse or promote products derived from this software without  */
0029 /* specific prior written permission of the institution or contributor.       */
0030 /******************************************************************************/
0031
0032 /*! The XrdSecAttr object is used as the base class to add arbitrary
0033     extensions to the XrdSecEntity object. A derived class definition should
0034     have a unique signature which is used by XrdSecEntity::Add() to
0035     differentiate extentions. The easiest way to do this is to use a unique
0036     memory address specific to all instances of the derived class. For instance,
0037
0038     class myAttr :: public XrdSecAttr
0039     { ....
0040      static const <type> mySig;
0041
0042           myAttr(...) : XrdSecAttr((const void *)&mySig), ...
0043       ....
0044     };
0045
0046    You use this signature to retrieve an instance of the extension added to
0047    a specific XrdSecEntity object. Since signatures are unique the derived
0048    class is well known and you can safely use a static cast to downcast the
0049    returned pointer to the proper class (see the XrdSecEntity::Get() method).
0050    To successfully downcast using static_cast your derived class must be
0051    fully defined and in the scope of the static_cast. Otherwise, you must
0052    use the more expensive dynamic_cast.
0053
0054    Attribute objects are deleted when the associated XrdSecEntity instance
0055    is deleted. This happens when the client's server connection is closed.
0056 */
0057
0058 class  XrdSecEntity;
0059
0060 class  XrdSecAttr
0061 {
0062 public:
0063 friend class XrdSecEntityAttr;
0064
0065 //------------------------------------------------------------------------------
0066 //! Delete this object (may be over-ridden for custom action).
0067 //------------------------------------------------------------------------------
0068
0069 virtual void Delete() {delete this;}
0070
0071 //------------------------------------------------------------------------------
0072 //! Constructor.
0073 //!
0074 //! @param  dSig - the unique signature for all instances of the class that
0075 //!                uses this class as its base (i.e. the derived class).
0076 //------------------------------------------------------------------------------
0077
0078          XrdSecAttr(const void *dSig) : Signature(dSig) {}
0079
0080 //------------------------------------------------------------------------------
0081 //! Destructor (always externally done via Delete() method).
0082 //------------------------------------------------------------------------------
0083 protected:
0084
0085 virtual ~XrdSecAttr() {}
0086
0087 private:
0088
0089 const void *Signature;
0090 };
0091 #endif