33dee81933
The getaddrinfo(3), getipnodebyname(3) and resolver(3) can coincide now with what should be totally reentrant, and h_errno values will now be preserved correctly, but this does not affect interfaces such as gethostbyname(3) which are still mostly non-reentrant. In all of these relevant functions, the thread-safety has been pushed down as far as it seems possible right now. This means that operations that are selected via nsdispatch(3) (i.e. files, yp, dns) are protected still under global locks that getaddrinfo(3) defines, but where possible the locking is greatly reduced. The most noticeable improvement is that multiple DNS lookups can now be run at the same time, and this shows major improvement in performance of DNS-lookup threaded programs, and solves the "Mozilla tab serialization" problem. No single-threaded applications need to be recompiled. Multi-threaded applications that reference "_res" to change resolver(3) options will need to be recompiled, and ones which reference "h_errno" will also if they desire the correct h_errno values. If the applications already understood that _res and h_errno were not thread-safe and had their own locking, they will see no performance improvement but will not actually break in any way. Please note that when NSS modules are used, or when nsdispatch(3) defaults to adding any lookups of its own to the individual libc _nsdispatch() calls, those MUST be reentrant as well.
114 lines
3.9 KiB
C
114 lines
3.9 KiB
C
/*
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* Copyright (c) 1987, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/*
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* Portions Copyright (c) 1996 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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#if defined(LIBC_SCCS) && !defined(lint)
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static char sccsid[] = "@(#)herror.c 8.1 (Berkeley) 6/4/93";
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#endif /* LIBC_SCCS and not lint */
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "namespace.h"
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#include <sys/types.h>
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#include <sys/uio.h>
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#include <netdb.h>
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#include <string.h>
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#include <unistd.h>
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#include "un-namespace.h"
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const char *h_errlist[] = {
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"Resolver Error 0 (no error)",
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"Unknown host", /* 1 HOST_NOT_FOUND */
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"Host name lookup failure", /* 2 TRY_AGAIN */
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"Unknown server error", /* 3 NO_RECOVERY */
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"No address associated with name", /* 4 NO_ADDRESS */
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};
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const int h_nerr = { sizeof h_errlist / sizeof h_errlist[0] };
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/*
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* herror --
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* print the error indicated by the h_errno value.
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*/
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void
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herror(s)
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const char *s;
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{
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struct iovec iov[4];
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struct iovec *v = iov;
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if (s && *s) {
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v->iov_base = (char *)s;
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v->iov_len = strlen(s);
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v++;
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v->iov_base = ": ";
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v->iov_len = 2;
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v++;
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}
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v->iov_base = (char *)hstrerror(h_errno);
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v->iov_len = strlen(v->iov_base);
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v++;
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v->iov_base = "\n";
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v->iov_len = 1;
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_writev(STDERR_FILENO, iov, (v - iov) + 1);
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}
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const char *
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hstrerror(err)
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int err;
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{
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if (err < 0)
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return ("Resolver internal error");
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else if (err < h_nerr)
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return (h_errlist[err]);
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return ("Unknown resolver error");
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}
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#undef h_errno
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int h_errno;
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