GNUnet  0.19.2
dns_api.c
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1 /*
2  This file is part of GNUnet
3  Copyright (C) 2012, 2016 GNUnet e.V.
4 
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.
9 
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.
14 
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/>.
17 
18  SPDX-License-Identifier: AGPL3.0-or-later
19  */
20 
26 #include "platform.h"
27 #include "gnunet_dns_service.h"
28 #include "dns.h"
29 
30 
35 {
40 
44  uint64_t request_id;
45 
49  uint32_t generation;
50 };
51 
52 
57 {
62 
67 
72 
76  void *rh_cls;
77 
82 
86  uint32_t generation;
87 
92 
97  unsigned int pending_requests;
98 };
99 
100 
106 static void
107 reconnect (void *cls);
108 
109 
115 static void
117 {
118  if (NULL != dh->mq)
119  {
120  GNUNET_MQ_destroy (dh->mq);
121  dh->mq = NULL;
122  }
123  dh->reconnect_task =
125  &reconnect,
126  dh);
127 }
128 
129 
138 static void
139 mq_error_handler (void *cls,
140  enum GNUNET_MQ_Error error)
141 {
142  struct GNUNET_DNS_Handle *dh = cls;
143 
144  force_reconnect (dh);
145 }
146 
147 
155 static int
156 check_request (void *cls,
157  const struct GNUNET_DNS_Request *req)
158 {
159  if (0 != ntohl (req->reserved))
160  {
161  GNUNET_break (0);
162  return GNUNET_SYSERR;
163  }
164  return GNUNET_OK;
165 }
166 
167 
175 static void
176 handle_request (void *cls,
177  const struct GNUNET_DNS_Request *req)
178 {
179  struct GNUNET_DNS_Handle *dh = cls;
180  size_t payload_length = ntohs (req->header.size) - sizeof(*req);
181  struct GNUNET_DNS_RequestHandle *rh;
182 
183  rh = GNUNET_new (struct GNUNET_DNS_RequestHandle);
184  rh->dh = dh;
185  rh->request_id = req->request_id;
186  rh->generation = dh->generation;
187  dh->pending_requests++;
188  dh->rh (dh->rh_cls,
189  rh,
190  payload_length,
191  (const char *) &req[1]);
192 }
193 
194 
195 static void
196 reconnect (void *cls)
197 {
198  struct GNUNET_DNS_Handle *dh = cls;
202  struct GNUNET_DNS_Request,
203  dh),
205  };
206  struct GNUNET_MQ_Envelope *env;
207  struct GNUNET_DNS_Register *msg;
208 
209  dh->reconnect_task = NULL;
210  dh->mq = GNUNET_CLIENT_connect (dh->cfg,
211  "dns",
212  handlers,
214  dh);
215  if (NULL == dh->mq)
216  return;
217  dh->generation++;
218  env = GNUNET_MQ_msg (msg,
220  msg->flags = htonl (dh->flags);
221  GNUNET_MQ_send (dh->mq,
222  env);
223 }
224 
225 
236 void
238 {
239  struct GNUNET_MQ_Envelope *env;
240  struct GNUNET_DNS_Response *resp;
241 
242  GNUNET_assert (0 < rh->dh->pending_requests--);
243  if (rh->generation != rh->dh->generation)
244  {
245  GNUNET_free (rh);
246  return;
247  }
248  env = GNUNET_MQ_msg (resp,
250  resp->drop_flag = htonl (1);
251  resp->request_id = rh->request_id;
252  GNUNET_MQ_send (rh->dh->mq,
253  env);
254  GNUNET_free (rh);
255 }
256 
257 
264 void
266 {
267  struct GNUNET_MQ_Envelope *env;
268  struct GNUNET_DNS_Response *resp;
269 
270  GNUNET_assert (0 < rh->dh->pending_requests--);
271  if (rh->generation != rh->dh->generation)
272  {
273  GNUNET_free (rh);
274  return;
275  }
276  env = GNUNET_MQ_msg (resp,
278  resp->request_id = rh->request_id;
279  resp->drop_flag = htonl (0);
280  GNUNET_MQ_send (rh->dh->mq,
281  env);
282  GNUNET_free (rh);
283 }
284 
285 
295 void
297  uint16_t reply_length,
298  const char *reply)
299 {
300  struct GNUNET_MQ_Envelope *env;
301  struct GNUNET_DNS_Response *resp;
302 
303  GNUNET_assert (0 < rh->dh->pending_requests--);
304  if (rh->generation != rh->dh->generation)
305  {
306  GNUNET_free (rh);
307  return;
308  }
309  if (reply_length + sizeof(struct GNUNET_DNS_Response)
311  {
312  GNUNET_break (0);
313  GNUNET_free (rh);
314  return;
315  }
316  env = GNUNET_MQ_msg_extra (resp,
317  reply_length,
319  resp->drop_flag = htonl (2);
320  resp->request_id = rh->request_id;
321  GNUNET_memcpy (&resp[1],
322  reply,
323  reply_length);
324  GNUNET_MQ_send (rh->dh->mq,
325  env);
326  GNUNET_free (rh);
327 }
328 
329 
339 struct GNUNET_DNS_Handle *
341  enum GNUNET_DNS_Flags flags,
343  void *rh_cls)
344 {
345  struct GNUNET_DNS_Handle *dh;
346 
347  dh = GNUNET_new (struct GNUNET_DNS_Handle);
348  dh->cfg = cfg;
349  dh->flags = flags;
350  dh->rh = rh;
351  dh->rh_cls = rh_cls;
353  return dh;
354 }
355 
356 
362 void
364 {
365  if (NULL != dh->mq)
366  {
367  GNUNET_MQ_destroy (dh->mq);
368  dh->mq = NULL;
369  }
370  if (NULL != dh->reconnect_task)
371  {
373  dh->reconnect_task = NULL;
374  }
375  /* make sure client has no pending requests left over! */
376  GNUNET_break (0 == dh->pending_requests);
377  GNUNET_free (dh);
378 }
379 
380 
381 /* end of dns_api.c */
struct GNUNET_MessageHeader * msg
Definition: 005.c:2
struct GNUNET_MQ_Envelope * env
Definition: 005.c:1
IPC messages between DNS API and DNS service.
static void force_reconnect(struct GNUNET_DNS_Handle *dh)
Drop the existing connection and reconnect to the DNS service.
Definition: dns_api.c:116
static void mq_error_handler(void *cls, enum GNUNET_MQ_Error error)
Generic error handler, called with the appropriate error code and the same closure specified at the c...
Definition: dns_api.c:139
static void reconnect(void *cls)
Reconnect to the DNS service.
Definition: dns_api.c:196
static int check_request(void *cls, const struct GNUNET_DNS_Request *req)
This receives packets from the DNS service and calls the application to check that the request is wel...
Definition: dns_api.c:156
static void handle_request(void *cls, const struct GNUNET_DNS_Request *req)
This receives packets from the DNS service and calls the application to handle it.
Definition: dns_api.c:176
static const struct GNUNET_CONFIGURATION_Handle * cfg
Configuration we are using.
Definition: gnunet-abd.c:36
static struct GNUNET_CADET_MessageHandler handlers[]
Handlers, for diverse services.
static struct GNUNET_VPN_RedirectionRequest * request
Opaque redirection request handle.
Definition: gnunet-vpn.c:40
API to access the DNS service.
#define GNUNET_MAX_MESSAGE_SIZE
Largest supported message (to be precise, one byte more than the largest possible message,...
struct GNUNET_MQ_Handle * GNUNET_CLIENT_connect(const struct GNUNET_CONFIGURATION_Handle *cfg, const char *service_name, const struct GNUNET_MQ_MessageHandler *handlers, GNUNET_MQ_ErrorHandler error_handler, void *error_handler_cls)
Create a message queue to connect to a GNUnet service.
Definition: client.c:1057
void(* GNUNET_DNS_RequestHandler)(void *cls, struct GNUNET_DNS_RequestHandle *rh, size_t request_length, const char *request)
Signature of a function that is called whenever the DNS service encounters a DNS request and needs to...
struct GNUNET_DNS_Handle * GNUNET_DNS_connect(const struct GNUNET_CONFIGURATION_Handle *cfg, enum GNUNET_DNS_Flags flags, GNUNET_DNS_RequestHandler rh, void *rh_cls)
Connect to the service-dns.
Definition: dns_api.c:340
void GNUNET_DNS_disconnect(struct GNUNET_DNS_Handle *dh)
Disconnect from the DNS service.
Definition: dns_api.c:363
void GNUNET_DNS_request_forward(struct GNUNET_DNS_RequestHandle *rh)
If a GNUNET_DNS_RequestHandler calls this function, the request is given to other clients or the glob...
Definition: dns_api.c:237
void GNUNET_DNS_request_answer(struct GNUNET_DNS_RequestHandle *rh, uint16_t reply_length, const char *reply)
If a GNUNET_DNS_RequestHandler calls this function, the request is supposed to be answered with the d...
Definition: dns_api.c:296
void GNUNET_DNS_request_drop(struct GNUNET_DNS_RequestHandle *rh)
If a GNUNET_DNS_RequestHandler calls this function, the request is to be dropped and no response shou...
Definition: dns_api.c:265
GNUNET_DNS_Flags
Flags that specify when to call the client's handler.
#define GNUNET_memcpy(dst, src, n)
Call memcpy() but check for n being 0 first.
@ GNUNET_OK
@ GNUNET_SYSERR
#define GNUNET_assert(cond)
Use this for fatal errors that cannot be handled.
#define GNUNET_break(cond)
Use this for internal assertion violations that are not fatal (can be handled) but should not occur.
#define GNUNET_new(type)
Allocate a struct or union of the given type.
#define GNUNET_free(ptr)
Wrapper around free.
GNUNET_MQ_Error
Error codes for the queue.
void GNUNET_MQ_send(struct GNUNET_MQ_Handle *mq, struct GNUNET_MQ_Envelope *ev)
Send a message with the given message queue.
Definition: mq.c:304
#define GNUNET_MQ_handler_end()
End-marker for the handlers array.
#define GNUNET_MQ_msg_extra(mvar, esize, type)
Allocate an envelope, with extra space allocated after the space needed by the message struct.
Definition: gnunet_mq_lib.h:62
#define GNUNET_MQ_msg(mvar, type)
Allocate a GNUNET_MQ_Envelope.
Definition: gnunet_mq_lib.h:77
#define GNUNET_MQ_hd_var_size(name, code, str, ctx)
void GNUNET_MQ_destroy(struct GNUNET_MQ_Handle *mq)
Destroy the message queue.
Definition: mq.c:687
#define GNUNET_MESSAGE_TYPE_DNS_CLIENT_REQUEST
Type of messages between the gnunet-helper-dns and the service.
#define GNUNET_MESSAGE_TYPE_DNS_CLIENT_RESPONSE
Type of messages between the gnunet-helper-dns and the service.
#define GNUNET_MESSAGE_TYPE_DNS_CLIENT_INIT
Initial message from client to DNS service for registration.
struct GNUNET_SCHEDULER_Task * GNUNET_SCHEDULER_add_now(GNUNET_SCHEDULER_TaskCallback task, void *task_cls)
Schedule a new task to be run as soon as possible.
Definition: scheduler.c:1268
void * GNUNET_SCHEDULER_cancel(struct GNUNET_SCHEDULER_Task *task)
Cancel the task with the specified identifier.
Definition: scheduler.c:944
struct GNUNET_SCHEDULER_Task * GNUNET_SCHEDULER_add_delayed(struct GNUNET_TIME_Relative delay, GNUNET_SCHEDULER_TaskCallback task, void *task_cls)
Schedule a new task to be run with a specified delay.
Definition: scheduler.c:1241
#define GNUNET_TIME_UNIT_SECONDS
One second.
DNS handle.
Definition: dns_api.c:57
struct GNUNET_SCHEDULER_Task * reconnect_task
Task to reconnect to the service.
Definition: dns_api.c:81
GNUNET_DNS_RequestHandler rh
Function to call to get replies.
Definition: dns_api.c:71
enum GNUNET_DNS_Flags flags
Flags for events we care about.
Definition: dns_api.c:91
const struct GNUNET_CONFIGURATION_Handle * cfg
Configuration to use.
Definition: dns_api.c:66
struct GNUNET_MQ_Handle * mq
Connection to DNS service, or NULL.
Definition: dns_api.c:61
uint32_t generation
Re-connect counter, to make sure we did not reconnect in the meantime.
Definition: dns_api.c:86
unsigned int pending_requests
Number of GNUNET_DNS_RequestHandles we have outstanding.
Definition: dns_api.c:97
void * rh_cls
Closure for rh.
Definition: dns_api.c:76
Message from client to DNS service to register itself.
Definition: dns.h:36
Handle to identify an individual DNS request.
Definition: dns_api.c:35
struct GNUNET_DNS_Handle * dh
Handle to DNS API.
Definition: dns_api.c:39
uint32_t generation
Re-connect counter, to make sure we did not reconnect in the meantime.
Definition: dns_api.c:49
uint64_t request_id
Stored in network byte order (as for us, it is just a random number).
Definition: dns_api.c:44
Message from DNS service to client: please handle a request.
Definition: dns.h:53
uint32_t reserved
Always zero.
Definition: dns.h:62
uint64_t request_id
Unique request ID.
Definition: dns.h:67
struct GNUNET_MessageHeader header
Header of type GNUNET_MESSAGE_TYPE_DNS_CLIENT_REQUEST.
Definition: dns.h:57
Message from client to DNS service: here is my reply.
Definition: dns.h:77
uint32_t drop_flag
Zero to drop, 1 for no change (no payload), 2 for update (message has payload).
Definition: dns.h:86
uint64_t request_id
Unique request ID.
Definition: dns.h:91
Handle to a message queue.
Definition: mq.c:87
Message handler for a specific message type.
uint16_t size
The length of the struct (in bytes, including the length field itself), in big-endian format.
Entry in list of pending tasks.
Definition: scheduler.c:136