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3 Copyright (C) 2012 GNUnet e.V.
5 GNUnet is free software: you can redistribute it and/or modify it
6 under the terms of the GNU Affero General Public License as published
7 by the Free Software Foundation, either version 3 of the License,
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11 WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Affero General Public License for more details.
15 You should have received a copy of the GNU Affero General Public License
16 along with this program. If not, see <http://www.gnu.org/licenses/>.
20 * @author Christian Grothoff
23 * API to access the DNS service.
25 * @defgroup dns DNS service
27 * @see [Documentation](https://gnunet.org/gnunet-service-dns)
31 #ifndef GNUNET_DNS_SERVICE_H
32 #define GNUNET_DNS_SERVICE_H
34 #include "gnunet_util_lib.h"
40 struct GNUNET_DNS_Handle;
43 * Handle to identify an individual DNS request.
45 struct GNUNET_DNS_RequestHandle;
48 * Flags that specify when to call the client's handler.
54 * Useless option: never call the client.
56 GNUNET_DNS_FLAG_NEVER = 0,
59 * Set this flag to see all requests first prior to resolution
60 * (for monitoring). Clients that set this flag must then
61 * call "GNUNET_DNS_request_forward" when they process a request
62 * for the first time. Caling "GNUNET_DNS_request_answer" is
63 * not allowed for MONITOR peers.
65 GNUNET_DNS_FLAG_REQUEST_MONITOR = 1,
68 * This client should be called on requests that have not
69 * yet been resolved as this client provides a resolution
70 * service. Note that this does not guarantee that the
71 * client will see all requests as another client might be
72 * called first and that client might have already done the
73 * resolution, in which case other pre-resolution clients
74 * won't see the request anymore.
76 GNUNET_DNS_FLAG_PRE_RESOLUTION = 2,
79 * This client wants to be called on the results of a DNS resolution
80 * (either resolved by PRE-RESOLUTION clients or the global DNS).
81 * The client then has a chance to modify the answer (or cause it to
82 * be dropped). There is no guarantee that other POST-RESOLUTION
83 * client's won't modify (or drop) the answer afterwards.
85 GNUNET_DNS_FLAG_POST_RESOLUTION = 4,
88 * Set this flag to see all requests just before they are
89 * returned to the network. Clients that set this flag must then
90 * call "GNUNET_DNS_request_forward" when they process a request
91 * for the last time. Caling "GNUNET_DNS_request_answer" is
92 * not allowed for MONITOR peers.
94 GNUNET_DNS_FLAG_RESPONSE_MONITOR = 8
101 * Signature of a function that is called whenever the DNS service
102 * encounters a DNS request and needs to do something with it. The
103 * function has then the chance to generate or modify the response by
104 * calling one of the three "GNUNET_DNS_request_*" continuations.
106 * When a request is intercepted, this function is called first to
107 * give the client a chance to do the complete address resolution;
108 * "rdata" will be NULL for this first call for a DNS request, unless
109 * some other client has already filled in a response.
111 * If multiple clients exist, all of them are called before the global
112 * DNS. The global DNS is only called if all of the clients'
113 * functions call GNUNET_DNS_request_forward. Functions that call
114 * GNUNET_DNS_request_forward will be called again before a final
115 * response is returned to the application. If any of the clients'
116 * functions call GNUNET_DNS_request_drop, the response is dropped.
119 * @param rh request handle to user for reply
120 * @param request_length number of bytes in request
121 * @param request udp payload of the DNS request
124 (*GNUNET_DNS_RequestHandler)(void *cls,
125 struct GNUNET_DNS_RequestHandle *rh,
126 size_t request_length,
127 const char *request);
131 * If a GNUNET_DNS_RequestHandler calls this function, the client
132 * has no desire to interfer with the request and it should
133 * continue to be processed normally.
135 * @param rh request that should now be forwarded
138 GNUNET_DNS_request_forward (struct GNUNET_DNS_RequestHandle *rh);
142 * If a GNUNET_DNS_RequestHandler calls this function, the request is
143 * to be dropped and no response should be generated.
145 * @param rh request that should now be dropped
148 GNUNET_DNS_request_drop (struct GNUNET_DNS_RequestHandle *rh);
152 * If a GNUNET_DNS_RequestHandler calls this function, the request is
153 * supposed to be answered with the data provided to this call (with
154 * the modifications the function might have made). The reply given
155 * must always be a valid DNS reply and not a mutated DNS request.
157 * @param rh request that should now be answered
158 * @param reply_length size of @a reply (uint16_t to force sane size)
159 * @param reply reply data
162 GNUNET_DNS_request_answer (struct GNUNET_DNS_RequestHandle *rh,
163 uint16_t reply_length,
168 * Connect to the service-dns
170 * @param cfg configuration to use
171 * @param flags when to call @a rh
172 * @param rh function to call with DNS requests
173 * @param rh_cls closure to pass to @a rh
176 struct GNUNET_DNS_Handle *
177 GNUNET_DNS_connect (const struct GNUNET_CONFIGURATION_Handle *cfg,
178 enum GNUNET_DNS_Flags flags,
179 GNUNET_DNS_RequestHandler rh,
184 * Disconnect from the DNS service.
186 * @param dh DNS handle
189 GNUNET_DNS_disconnect (struct GNUNET_DNS_Handle *dh);
194 /** @} */ /* end of group */