summaryrefslogtreecommitdiff
path: root/net/tipc/discover.c
blob: bc849f1efa167739d4831ea0f013f28541de2a79 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
/*
 * net/tipc/discover.c
 *
 * Copyright (c) 2003-2006, Ericsson AB
 * Copyright (c) 2005-2006, 2010-2011, Wind River Systems
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the names of the copyright holders nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * Alternatively, this software may be distributed under the terms of the
 * GNU General Public License ("GPL") version 2 as published by the Free
 * Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include "core.h"
#include "link.h"
#include "discover.h"

#define TIPC_LINK_REQ_INIT	125	/* min delay during bearer start up */
#define TIPC_LINK_REQ_FAST	1000	/* max delay if bearer has no links */
#define TIPC_LINK_REQ_SLOW	60000	/* max delay if bearer has links */
#define TIPC_LINK_REQ_INACTIVE	0xffffffff /* indicates no timer in use */


/**
 * struct tipc_link_req - information about an ongoing link setup request
 * @bearer: bearer issuing requests
 * @dest: destination address for request messages
 * @domain: network domain to which links can be established
 * @num_nodes: number of nodes currently discovered (i.e. with an active link)
 * @buf: request message to be (repeatedly) sent
 * @timer: timer governing period between requests
 * @timer_intv: current interval between requests (in ms)
 */
struct tipc_link_req {
	struct tipc_bearer *bearer;
	struct tipc_media_addr dest;
	u32 domain;
	int num_nodes;
	struct sk_buff *buf;
	struct timer_list timer;
	unsigned int timer_intv;
};

/**
 * tipc_disc_init_msg - initialize a link setup message
 * @type: message type (request or response)
 * @dest_domain: network domain of node(s) which should respond to message
 * @b_ptr: ptr to bearer issuing message
 */
static struct sk_buff *tipc_disc_init_msg(u32 type, u32 dest_domain,
					  struct tipc_bearer *b_ptr)
{
	struct sk_buff *buf = tipc_buf_acquire(INT_H_SIZE);
	struct tipc_msg *msg;

	if (buf) {
		msg = buf_msg(buf);
		tipc_msg_init(msg, LINK_CONFIG, type, INT_H_SIZE, dest_domain);
		msg_set_non_seq(msg, 1);
		msg_set_node_sig(msg, tipc_random);
		msg_set_dest_domain(msg, dest_domain);
		msg_set_bc_netid(msg, tipc_net_id);
		b_ptr->media->addr2msg(&b_ptr->addr, msg_media_addr(msg));
	}
	return buf;
}

/**
 * disc_dupl_alert - issue node address duplication alert
 * @b_ptr: pointer to bearer detecting duplication
 * @node_addr: duplicated node address
 * @media_addr: media address advertised by duplicated node
 */
static void disc_dupl_alert(struct tipc_bearer *b_ptr, u32 node_addr,
			    struct tipc_media_addr *media_addr)
{
	char node_addr_str[16];
	char media_addr_str[64];

	tipc_addr_string_fill(node_addr_str, node_addr);
	tipc_media_addr_printf(media_addr_str, sizeof(media_addr_str),
			       media_addr);
	pr_warn("Duplicate %s using %s seen on <%s>\n", node_addr_str,
		media_addr_str, b_ptr->name);
}

/**
 * tipc_disc_recv_msg - handle incoming link setup message (request or response)
 * @buf: buffer containing message
 * @b_ptr: bearer that message arrived on
 */
void tipc_disc_recv_msg(struct sk_buff *buf, struct tipc_bearer *b_ptr)
{
	struct tipc_node *n_ptr;
	struct tipc_link *link;
	struct tipc_media_addr media_addr;
	struct sk_buff *rbuf;
	struct tipc_msg *msg = buf_msg(buf);
	u32 dest = msg_dest_domain(msg);
	u32 orig = msg_prevnode(msg);
	u32 net_id = msg_bc_netid(msg);
	u32 type = msg_type(msg);
	u32 signature = msg_node_sig(msg);
	int addr_mismatch;
	int link_fully_up;

	media_addr.broadcast = 1;
	b_ptr->media->msg2addr(b_ptr, &media_addr, msg_media_addr(msg));
	kfree_skb(buf);

	/* Ensure message from node is valid and communication is permitted */
	if (net_id != tipc_net_id)
		return;
	if (media_addr.broadcast)
		return;
	if (!tipc_addr_domain_valid(dest))
		return;
	if (!tipc_addr_node_valid(orig))
		return;
	if (orig == tipc_own_addr) {
		if (memcmp(&media_addr, &b_ptr->addr, sizeof(media_addr)))
			disc_dupl_alert(b_ptr, tipc_own_addr, &media_addr);
		return;
	}
	if (!tipc_in_scope(dest, tipc_own_addr))
		return;
	if (!tipc_in_scope(b_ptr->link_req->domain, orig))
		return;

	/* Locate structure corresponding to requesting node */
	n_ptr = tipc_node_find(orig);
	if (!n_ptr) {
		n_ptr = tipc_node_create(orig);
		if (!n_ptr)
			return;
	}
	tipc_node_lock(n_ptr);

	/* Prepare to validate requesting node's signature and media address */
	link = n_ptr->links[b_ptr->identity];
	addr_mismatch = (link != NULL) &&
		memcmp(&link->media_addr, &media_addr, sizeof(media_addr));

	/*
	 * Ensure discovery message's signature is correct
	 *
	 * If signature is incorrect and there is no working link to the node,
	 * accept the new signature but invalidate all existing links to the
	 * node so they won't re-activate without a new discovery message.
	 *
	 * If signature is incorrect and the requested link to the node is
	 * working, accept the new signature. (This is an instance of delayed
	 * rediscovery, where a link endpoint was able to re-establish contact
	 * with its peer endpoint on a node that rebooted before receiving a
	 * discovery message from that node.)
	 *
	 * If signature is incorrect and there is a working link to the node
	 * that is not the requested link, reject the request (must be from
	 * a duplicate node).
	 */
	if (signature != n_ptr->signature) {
		if (n_ptr->working_links == 0) {
			struct tipc_link *curr_link;
			int i;

			for (i = 0; i < MAX_BEARERS; i++) {
				curr_link = n_ptr->links[i];
				if (curr_link) {
					memset(&curr_link->media_addr, 0,
					       sizeof(media_addr));
					tipc_link_reset(curr_link);
				}
			}
			addr_mismatch = (link != NULL);
		} else if (tipc_link_is_up(link) && !addr_mismatch) {
			/* delayed rediscovery */
		} else {
			disc_dupl_alert(b_ptr, orig, &media_addr);
			tipc_node_unlock(n_ptr);
			return;
		}
		n_ptr->signature = signature;
	}

	/*
	 * Ensure requesting node's media address is correct
	 *
	 * If media address doesn't match and the link is working, reject the
	 * request (must be from a duplicate node).
	 *
	 * If media address doesn't match and the link is not working, accept
	 * the new media address and reset the link to ensure it starts up
	 * cleanly.
	 */
	if (addr_mismatch) {
		if (tipc_link_is_up(link)) {
			disc_dupl_alert(b_ptr, orig, &media_addr);
			tipc_node_unlock(n_ptr);
			return;
		} else {
			memcpy(&link->media_addr, &media_addr,
			       sizeof(media_addr));
			tipc_link_reset(link);
		}
	}

	/* Create a link endpoint for this bearer, if necessary */
	if (!link) {
		link = tipc_link_create(n_ptr, b_ptr, &media_addr);
		if (!link) {
			tipc_node_unlock(n_ptr);
			return;
		}
	}

	/* Accept discovery message & send response, if necessary */
	link_fully_up = link_working_working(link);

	if ((type == DSC_REQ_MSG) && !link_fully_up) {
		rbuf = tipc_disc_init_msg(DSC_RESP_MSG, orig, b_ptr);
		if (rbuf) {
			tipc_bearer_send(b_ptr, rbuf, &media_addr);
			kfree_skb(rbuf);
		}
	}

	tipc_node_unlock(n_ptr);
}

/**
 * disc_update - update frequency of periodic link setup requests
 * @req: ptr to link request structure
 *
 * Reinitiates discovery process if discovery object has no associated nodes
 * and is either not currently searching or is searching at a slow rate
 */
static void disc_update(struct tipc_link_req *req)
{
	if (!req->num_nodes) {
		if ((req->timer_intv == TIPC_LINK_REQ_INACTIVE) ||
		    (req->timer_intv > TIPC_LINK_REQ_FAST)) {
			req->timer_intv = TIPC_LINK_REQ_INIT;
			k_start_timer(&req->timer, req->timer_intv);
		}
	}
}

/**
 * tipc_disc_add_dest - increment set of discovered nodes
 * @req: ptr to link request structure
 */
void tipc_disc_add_dest(struct tipc_link_req *req)
{
	req->num_nodes++;
}

/**
 * tipc_disc_remove_dest - decrement set of discovered nodes
 * @req: ptr to link request structure
 */
void tipc_disc_remove_dest(struct tipc_link_req *req)
{
	req->num_nodes--;
	disc_update(req);
}

/**
 * disc_timeout - send a periodic link setup request
 * @req: ptr to link request structure
 *
 * Called whenever a link setup request timer associated with a bearer expires.
 */
static void disc_timeout(struct tipc_link_req *req)
{
	int max_delay;

	spin_lock_bh(&req->bearer->lock);

	/* Stop searching if only desired node has been found */
	if (tipc_node(req->domain) && req->num_nodes) {
		req->timer_intv = TIPC_LINK_REQ_INACTIVE;
		goto exit;
	}

	/*
	 * Send discovery message, then update discovery timer
	 *
	 * Keep doubling time between requests until limit is reached;
	 * hold at fast polling rate if don't have any associated nodes,
	 * otherwise hold at slow polling rate
	 */
	tipc_bearer_send(req->bearer, req->buf, &req->dest);


	req->timer_intv *= 2;
	if (req->num_nodes)
		max_delay = TIPC_LINK_REQ_SLOW;
	else
		max_delay = TIPC_LINK_REQ_FAST;
	if (req->timer_intv > max_delay)
		req->timer_intv = max_delay;

	k_start_timer(&req->timer, req->timer_intv);
exit:
	spin_unlock_bh(&req->bearer->lock);
}

/**
 * tipc_disc_create - create object to send periodic link setup requests
 * @b_ptr: ptr to bearer issuing requests
 * @dest: destination address for request messages
 * @dest_domain: network domain to which links can be established
 *
 * Returns 0 if successful, otherwise -errno.
 */
int tipc_disc_create(struct tipc_bearer *b_ptr, struct tipc_media_addr *dest,
		     u32 dest_domain)
{
	struct tipc_link_req *req;

	req = kmalloc(sizeof(*req), GFP_ATOMIC);
	if (!req)
		return -ENOMEM;

	req->buf = tipc_disc_init_msg(DSC_REQ_MSG, dest_domain, b_ptr);
	if (!req->buf) {
		kfree(req);
		return -ENOMSG;
	}

	memcpy(&req->dest, dest, sizeof(*dest));
	req->bearer = b_ptr;
	req->domain = dest_domain;
	req->num_nodes = 0;
	req->timer_intv = TIPC_LINK_REQ_INIT;
	k_init_timer(&req->timer, (Handler)disc_timeout, (unsigned long)req);
	k_start_timer(&req->timer, req->timer_intv);
	b_ptr->link_req = req;
	tipc_bearer_send(req->bearer, req->buf, &req->dest);
	return 0;
}

/**
 * tipc_disc_delete - destroy object sending periodic link setup requests
 * @req: ptr to link request structure
 */
void tipc_disc_delete(struct tipc_link_req *req)
{
	k_cancel_timer(&req->timer);
	k_term_timer(&req->timer);
	kfree_skb(req->buf);
	kfree(req);
}