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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.
104 lines
3.9 KiB
C
104 lines
3.9 KiB
C
/* Extended resolver state separate from struct __res_state.
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Copyright (C) 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_STATE_H
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#define RESOLV_STATE_H
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#include <netinet/in.h>
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#include <stdbool.h>
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#include <stddef.h>
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/* This type corresponds to members of the _res.sort_list array. */
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struct resolv_sortlist_entry
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{
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struct in_addr addr;
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uint32_t mask;
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};
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/* Extended resolver state associated with res_state objects. Client
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code can reach this state through a struct resolv_context
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object. */
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struct resolv_conf
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{
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/* Reference counter. The object is deallocated once it reaches
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zero. For internal use within resolv_conf only. */
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size_t __refcount;
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/* List of IPv4 and IPv6 name server addresses. */
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const struct sockaddr **nameserver_list;
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size_t nameserver_list_size;
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/* The domain names forming the search list. */
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const char *const *search_list;
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size_t search_list_size;
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/* IPv4 address preference rules. */
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const struct resolv_sortlist_entry *sort_list;
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size_t sort_list_size;
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/* _res.options has type unsigned long, but we can only use 32 bits
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for portability across all architectures. */
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unsigned int options;
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unsigned int retrans; /* Timeout. */
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unsigned int retry; /* Number of times to retry. */
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unsigned int ndots; /* Dots needed for initial non-search query. */
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};
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/* The functions below are for use by the res_init resolv.conf parser
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and the struct resolv_context facility. */
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struct __res_state;
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/* Read /etc/resolv.conf and return a configuration object, or NULL if
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/etc/resolv.conf cannot be read due to memory allocation errors.
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If PREINIT is not NULL, some configuration values are taken from the
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struct __res_state object. */
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struct resolv_conf *__resolv_conf_load (struct __res_state *preinit)
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attribute_hidden __attribute__ ((warn_unused_result));
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/* Return a configuration object for the current /etc/resolv.conf
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settings, or NULL on failure. The object is cached. */
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struct resolv_conf *__resolv_conf_get_current (void)
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attribute_hidden __attribute__ ((warn_unused_result));
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/* Return the extended resolver state for *RESP, or NULL if it cannot
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be determined. A call to this function must be paired with a call
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to __resolv_conf_put. */
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struct resolv_conf *__resolv_conf_get (struct __res_state *) attribute_hidden;
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/* Converse of __resolv_conf_get. */
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void __resolv_conf_put (struct resolv_conf *) attribute_hidden;
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/* Allocate a new struct resolv_conf object and copy the
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pre-configured values from *INIT. Return NULL on allocation
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failure. The object must be deallocated using
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__resolv_conf_put. */
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struct resolv_conf *__resolv_conf_allocate (const struct resolv_conf *init)
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attribute_hidden __attribute__ ((nonnull (1), warn_unused_result));
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/* Associate an existing extended resolver state with *RESP. Return
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false on allocation failure. In addition, update *RESP with the
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overlapping non-extended resolver state. */
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bool __resolv_conf_attach (struct __res_state *, struct resolv_conf *)
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attribute_hidden;
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/* Detach the extended resolver state from *RESP. */
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void __resolv_conf_detach (struct __res_state *resp) attribute_hidden;
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#endif /* RESOLV_STATE_H */
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