2 This file is part of GNUnet
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,
8 or (at your option) any later version.
10 GNUnet is distributed in the hope that it will be useful, but
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.
17 * @author Christian Grothoff
20 * API to access the DNS service.
22 * @defgroup dns DNS service
24 * @see [Documentation](https://gnunet.org/gnunet-service-dns)
28 #ifndef GNUNET_DNS_SERVICE_H
29 #define GNUNET_DNS_SERVICE_H
31 #include "gnunet_util_lib.h"
37 struct GNUNET_DNS_Handle;
40 * Handle to identify an individual DNS request.
42 struct GNUNET_DNS_RequestHandle;
45 * Flags that specify when to call the client's handler.
51 * Useless option: never call the client.
53 GNUNET_DNS_FLAG_NEVER = 0,
56 * Set this flag to see all requests first prior to resolution
57 * (for monitoring). Clients that set this flag must then
58 * call "GNUNET_DNS_request_forward" when they process a request
59 * for the first time. Caling "GNUNET_DNS_request_answer" is
60 * not allowed for MONITOR peers.
62 GNUNET_DNS_FLAG_REQUEST_MONITOR = 1,
65 * This client should be called on requests that have not
66 * yet been resolved as this client provides a resolution
67 * service. Note that this does not guarantee that the
68 * client will see all requests as another client might be
69 * called first and that client might have already done the
70 * resolution, in which case other pre-resolution clients
71 * won't see the request anymore.
73 GNUNET_DNS_FLAG_PRE_RESOLUTION = 2,
76 * This client wants to be called on the results of a DNS resolution
77 * (either resolved by PRE-RESOLUTION clients or the global DNS).
78 * The client then has a chance to modify the answer (or cause it to
79 * be dropped). There is no guarantee that other POST-RESOLUTION
80 * client's won't modify (or drop) the answer afterwards.
82 GNUNET_DNS_FLAG_POST_RESOLUTION = 4,
85 * Set this flag to see all requests just before they are
86 * returned to the network. Clients that set this flag must then
87 * call "GNUNET_DNS_request_forward" when they process a request
88 * for the last time. Caling "GNUNET_DNS_request_answer" is
89 * not allowed for MONITOR peers.
91 GNUNET_DNS_FLAG_RESPONSE_MONITOR = 8
98 * Signature of a function that is called whenever the DNS service
99 * encounters a DNS request and needs to do something with it. The
100 * function has then the chance to generate or modify the response by
101 * calling one of the three "GNUNET_DNS_request_*" continuations.
103 * When a request is intercepted, this function is called first to
104 * give the client a chance to do the complete address resolution;
105 * "rdata" will be NULL for this first call for a DNS request, unless
106 * some other client has already filled in a response.
108 * If multiple clients exist, all of them are called before the global
109 * DNS. The global DNS is only called if all of the clients'
110 * functions call GNUNET_DNS_request_forward. Functions that call
111 * GNUNET_DNS_request_forward will be called again before a final
112 * response is returned to the application. If any of the clients'
113 * functions call GNUNET_DNS_request_drop, the response is dropped.
116 * @param rh request handle to user for reply
117 * @param request_length number of bytes in request
118 * @param request udp payload of the DNS request
121 (*GNUNET_DNS_RequestHandler)(void *cls,
122 struct GNUNET_DNS_RequestHandle *rh,
123 size_t request_length,
124 const char *request);
128 * If a GNUNET_DNS_RequestHandler calls this function, the client
129 * has no desire to interfer with the request and it should
130 * continue to be processed normally.
132 * @param rh request that should now be forwarded
135 GNUNET_DNS_request_forward (struct GNUNET_DNS_RequestHandle *rh);
139 * If a GNUNET_DNS_RequestHandler calls this function, the request is
140 * to be dropped and no response should be generated.
142 * @param rh request that should now be dropped
145 GNUNET_DNS_request_drop (struct GNUNET_DNS_RequestHandle *rh);
149 * If a GNUNET_DNS_RequestHandler calls this function, the request is
150 * supposed to be answered with the data provided to this call (with
151 * the modifications the function might have made). The reply given
152 * must always be a valid DNS reply and not a mutated DNS request.
154 * @param rh request that should now be answered
155 * @param reply_length size of @a reply (uint16_t to force sane size)
156 * @param reply reply data
159 GNUNET_DNS_request_answer (struct GNUNET_DNS_RequestHandle *rh,
160 uint16_t reply_length,
165 * Connect to the service-dns
167 * @param cfg configuration to use
168 * @param flags when to call @a rh
169 * @param rh function to call with DNS requests
170 * @param rh_cls closure to pass to @a rh
173 struct GNUNET_DNS_Handle *
174 GNUNET_DNS_connect (const struct GNUNET_CONFIGURATION_Handle *cfg,
175 enum GNUNET_DNS_Flags flags,
176 GNUNET_DNS_RequestHandler rh,
181 * Disconnect from the DNS service.
183 * @param dh DNS handle
186 GNUNET_DNS_disconnect (struct GNUNET_DNS_Handle *dh);
191 /** @} */ /* end of group */