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-rw-r--r--src/util/server_nc.c472
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diff --git a/src/util/server_nc.c b/src/util/server_nc.c
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1/*
2 This file is part of GNUnet.
3 Copyright (C) 2010 GNUnet e.V.
4
5 GNUnet is free software; you can redistribute it and/or modify
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
8 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 General Public License for more details.
14
15 You should have received a copy of the GNU General Public License
16 along with GNUnet; see the file COPYING. If not, write to the
17 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
18 Boston, MA 02110-1301, USA.
19*/
20
21/**
22 * @file util/server_nc.c
23 * @brief convenience functions for transmission of
24 * a notification stream
25 * @author Christian Grothoff
26 */
27
28#include "platform.h"
29#include "gnunet_util_lib.h"
30
31#define LOG(kind,...) GNUNET_log_from (kind, "util-server-nc", __VA_ARGS__)
32
33
34/**
35 * Entry in list of messages pending to be transmitted.
36 */
37struct PendingMessageList
38{
39
40 /**
41 * This is a doubly-linked list.
42 */
43 struct PendingMessageList *next;
44
45 /**
46 * This is a doubly-linked list.
47 */
48 struct PendingMessageList *prev;
49
50 /**
51 * Message to transmit (allocated at the end of this
52 * struct, do not free)
53 */
54 const struct GNUNET_MessageHeader *msg;
55
56 /**
57 * Can this message be dropped?
58 */
59 int can_drop;
60
61};
62
63
64/**
65 * Lists of clients we manage for notifications.
66 */
67struct ClientList
68{
69
70 /**
71 * This is a doubly linked list.
72 */
73 struct ClientList *next;
74
75 /**
76 * This is a doubly linked list.
77 */
78 struct ClientList *prev;
79
80 /**
81 * Overall context this client belongs to.
82 */
83 struct GNUNET_SERVER_NotificationContext *nc;
84
85 /**
86 * Handle to the client.
87 */
88 struct GNUNET_SERVER_Client *client;
89
90 /**
91 * Handle for pending transmission request to the client (or NULL).
92 */
93 struct GNUNET_SERVER_TransmitHandle *th;
94
95 /**
96 * Head of linked list of requests queued for transmission.
97 */
98 struct PendingMessageList *pending_head;
99
100 /**
101 * Tail of linked list of requests queued for transmission.
102 */
103 struct PendingMessageList *pending_tail;
104
105 /**
106 * Number of messages currently in the list.
107 */
108 unsigned int num_pending;
109
110};
111
112
113/**
114 * The notification context is the key datastructure for a convenience
115 * API used for transmission of notifications to the client until the
116 * client disconnects (or the notification context is destroyed, in
117 * which case we disconnect these clients). Essentially, all
118 * (notification) messages are queued up until the client is able to
119 * read them.
120 */
121struct GNUNET_SERVER_NotificationContext
122{
123
124 /**
125 * Server we do notifications for.
126 */
127 struct GNUNET_SERVER_Handle *server;
128
129 /**
130 * Head of list of clients receiving notifications.
131 */
132 struct ClientList *clients_head;
133
134 /**
135 * Tail of list of clients receiving notifications.
136 */
137 struct ClientList *clients_tail;
138
139 /**
140 * Maximum number of optional messages to queue per client.
141 */
142 unsigned int queue_length;
143
144};
145
146
147/**
148 * Client has disconnected, clean up.
149 *
150 * @param cls our `struct GNUNET_SERVER_NotificationContext *`
151 * @param client handle of client that disconnected
152 */
153static void
154handle_client_disconnect (void *cls,
155 struct GNUNET_SERVER_Client *client)
156{
157 struct GNUNET_SERVER_NotificationContext *nc = cls;
158 struct ClientList *pos;
159 struct PendingMessageList *pml;
160
161 if (NULL == client)
162 {
163 nc->server = NULL;
164 return;
165 }
166 for (pos = nc->clients_head; NULL != pos; pos = pos->next)
167 if (pos->client == client)
168 break;
169 if (NULL == pos)
170 return;
171 LOG (GNUNET_ERROR_TYPE_DEBUG,
172 "Client disconnected, cleaning up %u messages in NC queue\n",
173 pos->num_pending);
174 GNUNET_CONTAINER_DLL_remove (nc->clients_head,
175 nc->clients_tail,
176 pos);
177 while (NULL != (pml = pos->pending_head))
178 {
179 GNUNET_CONTAINER_DLL_remove (pos->pending_head,
180 pos->pending_tail,
181 pml);
182 GNUNET_free (pml);
183 pos->num_pending--;
184 }
185 if (NULL != pos->th)
186 {
187 GNUNET_SERVER_notify_transmit_ready_cancel (pos->th);
188 pos->th = NULL;
189 }
190 GNUNET_SERVER_client_drop (client);
191 GNUNET_assert (0 == pos->num_pending);
192 GNUNET_free (pos);
193}
194
195
196/**
197 * Create a new notification context.
198 *
199 * @param server server for which this function creates the context
200 * @param queue_length maximum number of messages to keep in
201 * the notification queue; optional messages are dropped
202 * if the queue gets longer than this number of messages
203 * @return handle to the notification context
204 */
205struct GNUNET_SERVER_NotificationContext *
206GNUNET_SERVER_notification_context_create (struct GNUNET_SERVER_Handle *server,
207 unsigned int queue_length)
208{
209 struct GNUNET_SERVER_NotificationContext *ret;
210
211 ret = GNUNET_new (struct GNUNET_SERVER_NotificationContext);
212 ret->server = server;
213 ret->queue_length = queue_length;
214 GNUNET_SERVER_disconnect_notify (server,
215 &handle_client_disconnect,
216 ret);
217 return ret;
218}
219
220
221/**
222 * Destroy the context, force disconnect for all clients.
223 *
224 * @param nc context to destroy.
225 */
226void
227GNUNET_SERVER_notification_context_destroy (struct GNUNET_SERVER_NotificationContext *nc)
228{
229 struct ClientList *pos;
230 struct PendingMessageList *pml;
231
232 while (NULL != (pos = nc->clients_head))
233 {
234 GNUNET_CONTAINER_DLL_remove (nc->clients_head,
235 nc->clients_tail,
236 pos);
237 if (NULL != pos->th)
238 {
239 GNUNET_SERVER_notify_transmit_ready_cancel (pos->th);
240 pos->th = NULL;
241 }
242 GNUNET_SERVER_client_drop (pos->client);
243 while (NULL != (pml = pos->pending_head))
244 {
245 GNUNET_CONTAINER_DLL_remove (pos->pending_head,
246 pos->pending_tail,
247 pml);
248 GNUNET_free (pml);
249 pos->num_pending--;
250 }
251 GNUNET_assert (0 == pos->num_pending);
252 GNUNET_free (pos);
253 }
254 if (NULL != nc->server)
255 GNUNET_SERVER_disconnect_notify_cancel (nc->server,
256 &handle_client_disconnect,
257 nc);
258 GNUNET_free (nc);
259}
260
261
262/**
263 * Add a client to the notification context.
264 *
265 * @param nc context to modify
266 * @param client client to add
267 */
268void
269GNUNET_SERVER_notification_context_add (struct GNUNET_SERVER_NotificationContext *nc,
270 struct GNUNET_SERVER_Client *client)
271{
272 struct ClientList *cl;
273
274 for (cl = nc->clients_head; NULL != cl; cl = cl->next)
275 if (cl->client == client)
276 return; /* already present */
277 cl = GNUNET_new (struct ClientList);
278 GNUNET_CONTAINER_DLL_insert (nc->clients_head,
279 nc->clients_tail,
280 cl);
281 cl->nc = nc;
282 cl->client = client;
283 GNUNET_SERVER_client_keep (client);
284}
285
286
287/**
288 * Function called to notify a client about the socket begin ready to
289 * queue more data. @a buf will be NULL and @a size zero if the socket
290 * was closed for writing in the meantime.
291 *
292 * @param cls the `struct ClientList *`
293 * @param size number of bytes available in @a buf
294 * @param buf where the callee should write the message
295 * @return number of bytes written to buf
296 */
297static size_t
298transmit_message (void *cls,
299 size_t size,
300 void *buf)
301{
302 struct ClientList *cl = cls;
303 char *cbuf = buf;
304 struct PendingMessageList *pml;
305 uint16_t msize;
306 size_t ret;
307
308 cl->th = NULL;
309 if (NULL == buf)
310 {
311 /* 'cl' should be freed via disconnect notification shortly */
312 LOG (GNUNET_ERROR_TYPE_DEBUG,
313 "Failed to transmit message from NC queue to client\n");
314 return 0;
315 }
316 ret = 0;
317 while (NULL != (pml = cl->pending_head))
318 {
319 msize = ntohs (pml->msg->size);
320 if (size < msize)
321 break;
322 GNUNET_CONTAINER_DLL_remove (cl->pending_head,
323 cl->pending_tail,
324 pml);
325 LOG (GNUNET_ERROR_TYPE_DEBUG,
326 "Copying message of type %u and size %u from pending queue to transmission buffer\n",
327 ntohs (pml->msg->type),
328 msize);
329 GNUNET_memcpy (&cbuf[ret], pml->msg, msize);
330 ret += msize;
331 size -= msize;
332 GNUNET_free (pml);
333 cl->num_pending--;
334 }
335 if (NULL != pml)
336 {
337 LOG (GNUNET_ERROR_TYPE_DEBUG,
338 "Have %u messages left in NC queue, will try transmission again\n",
339 cl->num_pending);
340 cl->th =
341 GNUNET_SERVER_notify_transmit_ready (cl->client,
342 ntohs (pml->msg->size),
343 GNUNET_TIME_UNIT_FOREVER_REL,
344 &transmit_message, cl);
345 }
346 else
347 {
348 GNUNET_assert (0 == cl->num_pending);
349 }
350 return ret;
351}
352
353
354/**
355 * Send a message to a particular client.
356 *
357 * @param nc context to modify
358 * @param client client to transmit to
359 * @param msg message to send
360 * @param can_drop can this message be dropped due to queue length limitations
361 */
362static void
363do_unicast (struct GNUNET_SERVER_NotificationContext *nc,
364 struct ClientList *client,
365 const struct GNUNET_MessageHeader *msg,
366 int can_drop)
367{
368 struct PendingMessageList *pml;
369 uint16_t size;
370
371 if ( (client->num_pending > nc->queue_length) &&
372 (GNUNET_YES == can_drop) )
373 {
374 LOG (GNUNET_ERROR_TYPE_INFO,
375 "Dropping message of type %u and size %u due to full queue (%u entries)\n",
376 ntohs (msg->type), ntohs (msg->size), (unsigned int) nc->queue_length);
377 return; /* drop! */
378 }
379 if (client->num_pending > nc->queue_length)
380 {
381 /* FIXME: consider checking for other messages in the
382 * queue that are 'droppable' */
383 }
384 client->num_pending++;
385 size = ntohs (msg->size);
386 pml = GNUNET_malloc (sizeof (struct PendingMessageList) + size);
387 pml->msg = (const struct GNUNET_MessageHeader *) &pml[1];
388 pml->can_drop = can_drop;
389 LOG (GNUNET_ERROR_TYPE_DEBUG,
390 "Adding message of type %u and size %u to pending queue (which has %u entries)\n",
391 ntohs (msg->type),
392 ntohs (msg->size),
393 (unsigned int) nc->queue_length);
394 GNUNET_memcpy (&pml[1], msg, size);
395 /* append */
396 GNUNET_CONTAINER_DLL_insert_tail (client->pending_head,
397 client->pending_tail,
398 pml);
399 if (NULL == client->th)
400 client->th =
401 GNUNET_SERVER_notify_transmit_ready (client->client,
402 ntohs (client->pending_head->
403 msg->size),
404 GNUNET_TIME_UNIT_FOREVER_REL,
405 &transmit_message, client);
406}
407
408
409/**
410 * Send a message to a particular client; must have
411 * already been added to the notification context.
412 *
413 * @param nc context to modify
414 * @param client client to transmit to
415 * @param msg message to send
416 * @param can_drop can this message be dropped due to queue length limitations
417 */
418void
419GNUNET_SERVER_notification_context_unicast (struct GNUNET_SERVER_NotificationContext *nc,
420 struct GNUNET_SERVER_Client *client,
421 const struct GNUNET_MessageHeader *msg,
422 int can_drop)
423{
424 struct ClientList *pos;
425
426 for (pos = nc->clients_head; NULL != pos; pos = pos->next)
427 if (pos->client == client)
428 break;
429 GNUNET_assert (NULL != pos);
430 do_unicast (nc, pos, msg, can_drop);
431}
432
433
434/**
435 * Send a message to all clients of this context.
436 *
437 * @param nc context to modify
438 * @param msg message to send
439 * @param can_drop can this message be dropped due to queue length limitations
440 */
441void
442GNUNET_SERVER_notification_context_broadcast (struct
443 GNUNET_SERVER_NotificationContext *nc,
444 const struct GNUNET_MessageHeader *msg,
445 int can_drop)
446{
447 struct ClientList *pos;
448
449 for (pos = nc->clients_head; NULL != pos; pos = pos->next)
450 do_unicast (nc, pos, msg, can_drop);
451}
452
453
454/**
455 * Return active number of subscribers in this context.
456 *
457 * @param nc context to query
458 * @return number of current subscribers
459 */
460unsigned int
461GNUNET_SERVER_notification_context_get_size (struct GNUNET_SERVER_NotificationContext *nc)
462{
463 unsigned int num;
464 struct ClientList *pos;
465
466 num = 0;
467 for (pos = nc->clients_head; NULL != pos; pos = pos->next)
468 num++;
469 return num;
470}
471
472/* end of server_nc.c */