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/*
This file is part of GNUnet
Copyright (C) 2012, 2018 GNUnet e.V.
GNUnet is free software: you can redistribute it and/or modify it
under the terms of the GNU Affero General Public License as published
by the Free Software Foundation, either version 3 of the License,
or (at your option) any later version.
GNUnet is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/**
* @author Christian Grothoff
*
* @file
* API for helper library to send DNS requests to DNS resolver
*
* @defgroup dns-stub DNS Stub library
* Helper library to send DNS requests to DNS resolver
* @{
*/
#ifndef GNUNET_DNSSTUB_LIB_H
#define GNUNET_DNSSTUB_LIB_H
#include "gnunet_common.h"
#include "gnunet_tun_lib.h"
/**
* Opaque handle to the stub resolver.
*/
struct GNUNET_DNSSTUB_Context;
/**
* Opaque handle to a socket doing UDP requests.
*/
struct GNUNET_DNSSTUB_RequestSocket;
/**
* Start a DNS stub resolver.
*
* @param num_sockets how many sockets should we open
* in parallel for DNS queries for this stub?
* @return NULL on error
*/
struct GNUNET_DNSSTUB_Context *
GNUNET_DNSSTUB_start (unsigned int num_sockets);
/**
* Add nameserver for use by the DNSSTUB. We will use
* all provided nameservers for resolution (round-robin).
*
* @param ctx resolver context to modify
* @param dns_ip target IP address to use (as string)
* @return #GNUNET_OK on success
*/
int
GNUNET_DNSSTUB_add_dns_ip (struct GNUNET_DNSSTUB_Context *ctx,
const char *dns_ip);
/**
* Add nameserver for use by the DNSSTUB. We will use
* all provided nameservers for resolution (round-robin).
*
* @param ctx resolver context to modify
* @param sa socket address of DNS resolver to use
* @return #GNUNET_OK on success
*/
int
GNUNET_DNSSTUB_add_dns_sa (struct GNUNET_DNSSTUB_Context *ctx,
const struct sockaddr *sa);
/**
* How long should we try requests before timing out?
* Only effective for requests issued after this call.
*
* @param ctx resolver context to modify
* @param retry_frequ how long to wait between retries
*/
void
GNUNET_DNSSTUB_set_retry (struct GNUNET_DNSSTUB_Context *ctx,
struct GNUNET_TIME_Relative retry_freq);
/**
* Cleanup DNSSTUB resolver.
*
* @param ctx stub resolver to clean up
*/
void
GNUNET_DNSSTUB_stop (struct GNUNET_DNSSTUB_Context *ctx);
/**
* Function called with the result of a DNS resolution.
* Once this function is called, the resolution request
* is automatically cancelled / cleaned up. In particular,
* the function will only be called once.
*
* @param cls closure
* @param dns dns response, NULL on hard error (i.e. timeout)
* @param dns_len number of bytes in @a dns
*/
typedef void
(*GNUNET_DNSSTUB_ResultCallback)(void *cls,
const struct GNUNET_TUN_DnsHeader *dns,
size_t dns_len);
/**
* Perform DNS resolution using our default IP from init.
*
* @param ctx stub resolver to use
* @param request DNS request to transmit
* @param request_len number of bytes in msg
* @param rc function to call with result (once)
* @param rc_cls closure for @a rc
* @return socket used for the request, NULL on error
*/
struct GNUNET_DNSSTUB_RequestSocket *
GNUNET_DNSSTUB_resolve (struct GNUNET_DNSSTUB_Context *ctx,
const void *request,
size_t request_len,
GNUNET_DNSSTUB_ResultCallback rc,
void *rc_cls);
/**
* Cancel DNS resolution.
*
* @param rs resolution to cancel
*/
void
GNUNET_DNSSTUB_resolve_cancel (struct GNUNET_DNSSTUB_RequestSocket *rs);
#endif
/** @} */ /* end of group */
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