2 This file is part of GNUnet
3 Copyright (C) 2012 Christian Grothoff (and other contributing authors)
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6 it under the terms of the GNU General Public License as published
7 by the Free Software Foundation; either version 3, or (at your
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12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 General Public License for more details.
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18 Boston, MA 02110-1301, USA.
22 * @author Christian Grothoff
25 * API to access the DNS service.
27 * @defgroup dns DNS service
30 #ifndef GNUNET_DNS_SERVICE_H
31 #define GNUNET_DNS_SERVICE_H
33 #include "gnunet_util_lib.h"
39 struct GNUNET_DNS_Handle;
42 * Handle to identify an individual DNS request.
44 struct GNUNET_DNS_RequestHandle;
47 * Flags that specify when to call the client's handler.
53 * Useless option: never call the client.
55 GNUNET_DNS_FLAG_NEVER = 0,
58 * Set this flag to see all requests first prior to resolution
59 * (for monitoring). Clients that set this flag must then
60 * call "GNUNET_DNS_request_forward" when they process a request
61 * for the first time. Caling "GNUNET_DNS_request_answer" is
62 * not allowed for MONITOR peers.
64 GNUNET_DNS_FLAG_REQUEST_MONITOR = 1,
67 * This client should be called on requests that have not
68 * yet been resolved as this client provides a resolution
69 * service. Note that this does not guarantee that the
70 * client will see all requests as another client might be
71 * called first and that client might have already done the
72 * resolution, in which case other pre-resolution clients
73 * won't see the request anymore.
75 GNUNET_DNS_FLAG_PRE_RESOLUTION = 2,
78 * This client wants to be called on the results of a DNS resolution
79 * (either resolved by PRE-RESOLUTION clients or the global DNS).
80 * The client then has a chance to modify the answer (or cause it to
81 * be dropped). There is no guarantee that other POST-RESOLUTION
82 * client's won't modify (or drop) the answer afterwards.
84 GNUNET_DNS_FLAG_POST_RESOLUTION = 4,
87 * Set this flag to see all requests just before they are
88 * returned to the network. Clients that set this flag must then
89 * call "GNUNET_DNS_request_forward" when they process a request
90 * for the last time. Caling "GNUNET_DNS_request_answer" is
91 * not allowed for MONITOR peers.
93 GNUNET_DNS_FLAG_RESPONSE_MONITOR = 8
100 * Signature of a function that is called whenever the DNS service
101 * encounters a DNS request and needs to do something with it. The
102 * function has then the chance to generate or modify the response by
103 * calling one of the three "GNUNET_DNS_request_*" continuations.
105 * When a request is intercepted, this function is called first to
106 * give the client a chance to do the complete address resolution;
107 * "rdata" will be NULL for this first call for a DNS request, unless
108 * some other client has already filled in a response.
110 * If multiple clients exist, all of them are called before the global
111 * DNS. The global DNS is only called if all of the clients'
112 * functions call GNUNET_DNS_request_forward. Functions that call
113 * GNUNET_DNS_request_forward will be called again before a final
114 * response is returned to the application. If any of the clients'
115 * functions call GNUNET_DNS_request_drop, the response is dropped.
118 * @param rh request handle to user for reply
119 * @param request_length number of bytes in request
120 * @param request udp payload of the DNS request
122 typedef void (*GNUNET_DNS_RequestHandler)(void *cls,
123 struct GNUNET_DNS_RequestHandle *rh,
124 size_t request_length,
125 const char *request);
129 * If a GNUNET_DNS_RequestHandler calls this function, the client
130 * has no desire to interfer with the request and it should
131 * continue to be processed normally.
133 * @param rh request that should now be forwarded
136 GNUNET_DNS_request_forward (struct GNUNET_DNS_RequestHandle *rh);
140 * If a GNUNET_DNS_RequestHandler calls this function, the request is
141 * to be dropped and no response should be generated.
143 * @param rh request that should now be dropped
146 GNUNET_DNS_request_drop (struct GNUNET_DNS_RequestHandle *rh);
150 * If a GNUNET_DNS_RequestHandler calls this function, the request is
151 * supposed to be answered with the data provided to this call (with
152 * the modifications the function might have made). The reply given
153 * must always be a valid DNS reply and not a mutated DNS request.
155 * @param rh request that should now be answered
156 * @param reply_length size of reply (uint16_t to force sane size)
157 * @param reply reply data
160 GNUNET_DNS_request_answer (struct GNUNET_DNS_RequestHandle *rh,
161 uint16_t reply_length,
166 * Connect to the service-dns
168 * @param cfg configuration to use
169 * @param flags when to call rh
170 * @param rh function to call with DNS requests
171 * @param rh_cls closure to pass to rh
174 struct GNUNET_DNS_Handle *
175 GNUNET_DNS_connect (const struct GNUNET_CONFIGURATION_Handle *cfg,
176 enum GNUNET_DNS_Flags flags,
177 GNUNET_DNS_RequestHandler rh,
182 * Disconnect from the DNS service.
184 * @param dh DNS handle
187 GNUNET_DNS_disconnect (struct GNUNET_DNS_Handle *dh);
189 /** @} */ /* end of group */