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aef16cc8a4
This commit enhances the stub resolver to reload the configuration in the per-thread _res object if the /etc/resolv.conf file has changed. The resolver checks whether the application has modified _res and will not overwrite the _res object in that case. The struct resolv_context mechanism is used to check the configuration file only once per name lookup.
101 lines
4.2 KiB
C
101 lines
4.2 KiB
C
/* libresolv interfaces for internal use across glibc.
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Copyright (C) 2016-2017 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#ifndef _RESOLV_INTERNAL_H
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#define _RESOLV_INTERNAL_H 1
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#include <resolv.h>
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#include <stdbool.h>
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/* Resolver flags. Used for _flags in struct __res_state. */
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#define RES_F_VC 0x00000001 /* Socket is TCP. */
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#define RES_F_CONN 0x00000002 /* Socket is connected. */
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#define RES_F_EDNS0ERR 0x00000004 /* EDNS0 caused errors. */
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/* Internal version of RES_USE_INET6 which does not trigger a
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deprecation warning. */
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#define DEPRECATED_RES_USE_INET6 0x00002000
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static inline bool
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res_use_inet6 (void)
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{
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return _res.options & DEPRECATED_RES_USE_INET6;
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}
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enum
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{
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/* The advertized EDNS buffer size. The value 1200 is derived
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from the IPv6 minimum MTU (1280 bytes) minus some arbitrary
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space for tunneling overhead. If the DNS server does not react
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to ICMP Fragmentation Needed But DF Set messages, this should
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avoid all UDP fragments on current networks. Avoiding UDP
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fragments is desirable because it prevents fragmentation-based
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spoofing attacks because the randomness in a DNS packet is
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concentrated in the first fragment (with the headers) and does
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not protect subsequent fragments. */
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RESOLV_EDNS_BUFFER_SIZE = 1200,
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};
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struct resolv_context;
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/* Internal function for implementing res_nmkquery and res_mkquery.
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Also used by __res_context_query. */
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int __res_context_mkquery (struct resolv_context *, int op, const char *dname,
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int class, int type, const unsigned char *data,
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unsigned char *buf, int buflen) attribute_hidden;
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/* Main resolver query function for use within glibc. */
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int __res_context_search (struct resolv_context *, const char *, int, int,
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unsigned char *, int, unsigned char **,
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unsigned char **, int *, int *, int *);
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libresolv_hidden_proto (__res_context_search)
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/* Main resolver query function for use within glibc. */
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int __res_context_query (struct resolv_context *, const char *, int, int,
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unsigned char *, int, unsigned char **,
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unsigned char **, int *, int *, int *);
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libresolv_hidden_proto (__res_context_query)
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/* Internal function used to implement the query and search
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functions. */
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int __res_context_send (struct resolv_context *, const unsigned char *, int,
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const unsigned char *, int, unsigned char *,
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int, unsigned char **, unsigned char **,
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int *, int *, int *) attribute_hidden;
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/* Internal function similar to res_hostalias. */
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const char *__res_context_hostalias (struct resolv_context *,
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const char *, char *, size_t);
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libresolv_hidden_proto (__res_context_hostalias);
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/* Add an OPT record to a DNS query. */
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int __res_nopt (struct resolv_context *, int n0,
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unsigned char *buf, int buflen, int anslen) attribute_hidden;
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/* Convert from presentation format (which usually means ASCII
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printable) to network format (which is usually some kind of binary
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format). The input is in the range [SRC, SRC + SRCLEN). The
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output is written to DST (which has to be 4 or 16 bytes long,
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depending on AF). Return 0 for invalid input, 1 for success, -1
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for an invalid address family. */
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int __inet_pton_length (int af, const char *src, size_t srclen, void *);
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libc_hidden_proto (__inet_pton_length)
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#endif /* _RESOLV_INTERNAL_H */
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