146 lines
4.9 KiB
C
146 lines
4.9 KiB
C
/*
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* Copyright (c) 1995-1999 by Internet Software Consortium.
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
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* ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
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* CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
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* DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
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* PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
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* ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
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* SOFTWARE.
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*/
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/* This file contains the definitions related to res_init which are
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linked into libc instead of libresolv. */
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#include <atomic.h>
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#include <limits.h>
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#include <sys/types.h>
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#include <netinet/in.h>
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#include <arpa/nameser.h>
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#include <resolv.h>
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#include <libc-lock.h>
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extern unsigned long long int __res_initstamp attribute_hidden;
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/* We have atomic increment operations on 64-bit platforms. */
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#if __WORDSIZE == 64
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# define atomicinclock(lock) (void) 0
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# define atomicincunlock(lock) (void) 0
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# define atomicinc(var) catomic_increment (&(var))
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#else
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__libc_lock_define_initialized (static, lock);
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# define atomicinclock(lock) __libc_lock_lock (lock)
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# define atomicincunlock(lock) __libc_lock_unlock (lock)
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# define atomicinc(var) ++var
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#endif
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int
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res_init(void) {
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extern int __res_vinit(res_state, int);
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/*
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* These three fields used to be statically initialized. This made
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* it hard to use this code in a shared library. It is necessary,
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* now that we're doing dynamic initialization here, that we preserve
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* the old semantics: if an application modifies one of these three
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* fields of _res before res_init() is called, res_init() will not
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* alter them. Of course, if an application is setting them to
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* _zero_ before calling res_init(), hoping to override what used
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* to be the static default, we can't detect it and unexpected results
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* will follow. Zero for any of these fields would make no sense,
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* so one can safely assume that the applications were already getting
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* unexpected results.
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*
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* _res.options is tricky since some apps were known to diddle the bits
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* before res_init() was first called. We can't replicate that semantic
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* with dynamic initialization (they may have turned bits off that are
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* set in RES_DEFAULT). Our solution is to declare such applications
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* "broken". They could fool us by setting RES_INIT but none do (yet).
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*/
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if (!_res.retrans)
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_res.retrans = RES_TIMEOUT;
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if (!_res.retry)
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_res.retry = 4;
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if (!(_res.options & RES_INIT))
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_res.options = RES_DEFAULT;
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else if (_res.nscount > 0)
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__res_iclose (&_res, true); /* Close any VC sockets. */
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/*
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* This one used to initialize implicitly to zero, so unless the app
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* has set it to something in particular, we can randomize it now.
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*/
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if (!_res.id)
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_res.id = res_randomid();
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atomicinclock (lock);
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/* Request all threads to re-initialize their resolver states,
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resolv.conf might have changed. */
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atomicinc (__res_initstamp);
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atomicincunlock (lock);
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return (__res_vinit(&_res, 1));
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}
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/* Initialize resp if RES_INIT is not yet set or if res_init in some other
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thread requested re-initializing. */
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int
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__res_maybe_init (res_state resp, int preinit)
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{
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if (resp->options & RES_INIT) {
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if (__res_initstamp != resp->_u._ext.initstamp) {
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if (resp->nscount > 0)
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__res_iclose (resp, true);
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return __res_vinit (resp, 1);
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}
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return 0;
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} else if (preinit) {
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if (!resp->retrans)
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resp->retrans = RES_TIMEOUT;
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if (!resp->retry)
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resp->retry = 4;
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resp->options = RES_DEFAULT;
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if (!resp->id)
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resp->id = res_randomid ();
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return __res_vinit (resp, 1);
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} else
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return __res_ninit (resp);
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}
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libc_hidden_def (__res_maybe_init)
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/* This needs to be after the use of _res in res_init, above. */
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#undef _res
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/* The resolver state for use by single-threaded programs.
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This differs from plain `struct __res_state _res;' in that it doesn't
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create a common definition, but a plain symbol that resides in .bss,
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which can have an alias. */
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struct __res_state _res __attribute__ ((nocommon));
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#undef __resp
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__thread struct __res_state *__resp = &_res;
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extern __thread struct __res_state *__libc_resp
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__attribute__ ((alias ("__resp"))) attribute_hidden;
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/* We declare this with compat_symbol so that it's not
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visible at link time. Programs must use the accessor functions. */
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#ifdef SHARED
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# include <shlib-compat.h>
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compat_symbol (libc, _res, _res, GLIBC_2_0);
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#endif
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#include <shlib-compat.h>
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#if SHLIB_COMPAT(libc, GLIBC_2_0, GLIBC_2_2)
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# undef res_init
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extern int __res_init_weak (void);
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weak_extern (__res_init_weak);
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strong_alias (__res_init, __res_init_weak);
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compat_symbol (libc, __res_init_weak, res_init, GLIBC_2_0);
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#endif
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