79 lines
2.8 KiB
C
79 lines
2.8 KiB
C
/*
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* Asterisk -- An open source telephony toolkit.
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*
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* Copyright (C) 2015, Digium, Inc.
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*
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* Joshua Colp <jcolp@digium.com>
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*
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* See http://www.asterisk.org for more information about
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* the Asterisk project. Please do not directly contact
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* any of the maintainers of this project for assistance;
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* the project provides a web site, mailing lists and IRC
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* channels for your use.
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*
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* This program is free software, distributed under the terms of
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* the GNU General Public License Version 2. See the LICENSE file
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* at the top of the source tree.
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*/
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/*! \file
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* \brief DNS Recurring Resolution API
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* \author Joshua Colp <jcolp@digium.com>
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*/
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#ifndef _ASTERISK_DNS_RECURRING_H
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#define _ASTERISK_DNS_RECURRING_H
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#if defined(__cplusplus) || defined(c_plusplus)
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extern "C" {
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#endif
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/*! \brief Opaque structure for a recurring DNS query */
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struct ast_dns_query_recurring;
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/*!
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* \brief Asynchronously resolve a DNS query, and continue resolving it according to the lowest TTL available
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*
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* \param name The name of what to resolve
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* \param rr_type Resource record type
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* \param rr_class Resource record class
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* \param callback The callback to invoke upon completion
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* \param data User data to make available on the query
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*
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* \retval non-NULL success - query has been sent for resolution
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* \retval NULL failure
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*
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* \note The user data passed in to this function must be ao2 allocated
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*
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* \note This query will continue to happen according to the lowest TTL unless cancelled using ast_dns_resolve_recurring_cancel
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*
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* \note It is NOT possible for the callback to be invoked concurrently for the query multiple times
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*
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* \note The query will occur when the TTL expires, not before. This means that there is a period of time where the previous
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* information can be considered stale.
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*
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* \note If the TTL is determined to be 0 (the record specifies 0, or no records exist) this will cease doing a recurring query.
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* It is the responsibility of the caller to resume querying at an interval they determine.
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*/
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struct ast_dns_query_recurring *ast_dns_resolve_recurring(const char *name, int rr_type, int rr_class, ast_dns_resolve_callback callback, void *data);
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/*!
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* \brief Cancel an asynchronous recurring DNS resolution
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*
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* \param recurring The DNS query returned from ast_dns_resolve_recurring
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*
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* \retval 0 success - any active query has been cancelled and the query will no longer occur
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* \retval -1 failure - an active query was in progress and could not be cancelled
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*
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* \note If successfully cancelled the callback will not be invoked
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*
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* \note This function does NOT drop your reference to the recurring query, this should be dropped using ao2_ref
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*/
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int ast_dns_resolve_recurring_cancel(struct ast_dns_query_recurring *recurring);
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#if defined(__cplusplus) || defined(c_plusplus)
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}
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#endif
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#endif /* _ASTERISK_DNS_RECURRING_H */
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