xref: /illumos-gate/usr/src/lib/gss_mechs/mech_krb5/include/cache-addrinfo.h (revision 55fea89d)

/*
 * Copyright (C) 2004 by the Massachusetts Institute of Technology,
 * Cambridge, MA, USA.  All Rights Reserved.
 *
 * This software is being provided to you, the LICENSEE, by the
 * Massachusetts Institute of Technology (M.I.T.) under the following
 * license.  By obtaining, using and/or copying this software, you agree
 * that you have read, understood, and will comply with these terms and
 * conditions:
 *
 * Export of this software from the United States of America may
 * require a specific license from the United States Government.
 * It is the responsibility of any person or organization contemplating
 * export to obtain such a license before exporting.
 *
 * WITHIN THAT CONSTRAINT, permission to use, copy, modify and distribute
 * this software and its documentation for any purpose and without fee or
 * royalty is hereby granted, provided that you agree to comply with the
 * following copyright notice and statements, including the disclaimer, and
 * that the same appear on ALL copies of the software and documentation,
 * including modifications that you make for internal use or for
 * distribution:
 *
 * THIS SOFTWARE IS PROVIDED "AS IS", AND M.I.T. MAKES NO REPRESENTATIONS
 * OR WARRANTIES, EXPRESS OR IMPLIED.  By way of example, but not
 * limitation, M.I.T. MAKES NO REPRESENTATIONS OR WARRANTIES OF
 * MERCHANTABILITY OR FITNESS FOR ANY PARTICULAR PURPOSE OR THAT THE USE OF
 * THE LICENSED SOFTWARE OR DOCUMENTATION WILL NOT INFRINGE ANY THIRD PARTY
 * PATENTS, COPYRIGHTS, TRADEMARKS OR OTHER RIGHTS.
 *
 * The name of the Massachusetts Institute of Technology or M.I.T. may NOT
 * be used in advertising or publicity pertaining to distribution of the
 * software.  Title to copyright in this software and any associated
 * documentation shall at all times remain with M.I.T., and USER agrees to
 * preserve same.
 *
 * Furthermore if you modify this software you must label
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 * fashion that it might be confused with the original M.I.T. software.
 */

/* Approach overview:

   If a system version is available but buggy, save handles to it,
   redefine the names to refer to static functions defined here, and
   in those functions, call the system versions and fix up the
   returned data.  Use the native data structures and flag values.

   If no system version exists, use gethostby* and fake it.  Define
   the data structures and flag values locally.


   On Mac OS X, getaddrinfo results aren't cached (though
   gethostbyname results are), so we need to build a cache here.  Now
   things are getting really messy.  Because the cache is in use, we
   use getservbyname, and throw away thread safety.  (Not that the
   cache is thread safe, but when we get locking support, that'll be
   dealt with.)  This code needs tearing down and rebuilding, soon.


   Note that recent Windows developers' code has an interesting hack:
   When you include the right header files, with the right set of
   macros indicating system versions, you'll get an inline function
   that looks for getaddrinfo (or whatever) in the system library, and
   calls it if it's there.  If it's not there, it fakes it with
   gethostby* calls.

   We're taking a simpler approach: A system provides these routines or
   it does not.

   Someday, we may want to take into account different versions (say,
   different revs of GNU libc) where some are broken in one way, and
   some work or are broken in another way.  Cross that bridge when we
   come to it.  */

/* To do, maybe:

   + For AIX 4.3.3, using the RFC 2133 definition: Implement
     AI_NUMERICHOST.  It's not defined in the header file.

     For certain (old?) versions of GNU libc, AI_NUMERICHOST is
     defined but not implemented.

   + Use gethostbyname2, inet_aton and other IPv6 or thread-safe
     functions if available.  But, see
     http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=135182 for one
     gethostbyname2 problem on Linux.  And besides, if a platform is
     supporting IPv6 at all, they really should be doing getaddrinfo
     by now.

   + inet_ntop, inet_pton

   + Conditionally export/import the function definitions, so a
     library can have a single copy instead of multiple.

   + Upgrade host requirements to include working implementations of
     these functions, and throw all this away.  Pleeease?  :-)  */

#include "port-sockets.h"
#include "socket-utils.h"
#include "k5-platform.h"
#include "k5-thread.h"

#include "fake-addrinfo.h"

#if defined (__APPLE__) && defined (__MACH__)
#define FAI_CACHE
#endif

struct face {
    struct in_addr *addrs4;
    struct in6_addr *addrs6;
    unsigned int naddrs4, naddrs6;
    time_t expiration;
    char *canonname, *name;
    struct face *next;
};

/* fake addrinfo cache */
struct fac {
    k5_mutex_t lock;
    struct face *data;
};

extern struct fac krb5int_fac;

extern int krb5int_init_fac (void);
extern void krb5int_fini_fac (void);