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