1/*
2 * net/tipc/discover.c
3 *
4 * Copyright (c) 2003-2006, Ericsson AB
5 * Copyright (c) 2005-2006, 2010-2011, Wind River Systems
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions are met:
10 *
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 * 3. Neither the names of the copyright holders nor the names of its
17 *    contributors may be used to endorse or promote products derived from
18 *    this software without specific prior written permission.
19 *
20 * Alternatively, this software may be distributed under the terms of the
21 * GNU General Public License ("GPL") version 2 as published by the Free
22 * Software Foundation.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
25 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
28 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
29 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
30 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
31 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
32 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
33 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
34 * POSSIBILITY OF SUCH DAMAGE.
35 */
36
37#include "core.h"
38#include "link.h"
39#include "discover.h"
40
41#define TIPC_LINK_REQ_INIT	125	/* min delay during bearer start up */
42#define TIPC_LINK_REQ_FAST	1000	/* max delay if bearer has no links */
43#define TIPC_LINK_REQ_SLOW	60000	/* max delay if bearer has links */
44#define TIPC_LINK_REQ_INACTIVE	0xffffffff /* indicates no timer in use */
45
46
47/**
48 * struct tipc_link_req - information about an ongoing link setup request
49 * @bearer: bearer issuing requests
50 * @dest: destination address for request messages
51 * @domain: network domain to which links can be established
52 * @num_nodes: number of nodes currently discovered (i.e. with an active link)
53 * @buf: request message to be (repeatedly) sent
54 * @timer: timer governing period between requests
55 * @timer_intv: current interval between requests (in ms)
56 */
57struct tipc_link_req {
58	struct tipc_bearer *bearer;
59	struct tipc_media_addr dest;
60	u32 domain;
61	int num_nodes;
62	struct sk_buff *buf;
63	struct timer_list timer;
64	unsigned int timer_intv;
65};
66
67/**
68 * tipc_disc_init_msg - initialize a link setup message
69 * @type: message type (request or response)
70 * @dest_domain: network domain of node(s) which should respond to message
71 * @b_ptr: ptr to bearer issuing message
72 */
73static struct sk_buff *tipc_disc_init_msg(u32 type,
74					  u32 dest_domain,
75					  struct tipc_bearer *b_ptr)
76{
77	struct sk_buff *buf = tipc_buf_acquire(INT_H_SIZE);
78	struct tipc_msg *msg;
79
80	if (buf) {
81		msg = buf_msg(buf);
82		tipc_msg_init(msg, LINK_CONFIG, type, INT_H_SIZE, dest_domain);
83		msg_set_non_seq(msg, 1);
84		msg_set_node_sig(msg, tipc_random);
85		msg_set_dest_domain(msg, dest_domain);
86		msg_set_bc_netid(msg, tipc_net_id);
87		b_ptr->media->addr2msg(&b_ptr->addr, msg_media_addr(msg));
88	}
89	return buf;
90}
91
92/**
93 * disc_dupl_alert - issue node address duplication alert
94 * @b_ptr: pointer to bearer detecting duplication
95 * @node_addr: duplicated node address
96 * @media_addr: media address advertised by duplicated node
97 */
98static void disc_dupl_alert(struct tipc_bearer *b_ptr, u32 node_addr,
99			    struct tipc_media_addr *media_addr)
100{
101	char node_addr_str[16];
102	char media_addr_str[64];
103
104	tipc_addr_string_fill(node_addr_str, node_addr);
105	tipc_media_addr_printf(media_addr_str, sizeof(media_addr_str),
106			       media_addr);
107	pr_warn("Duplicate %s using %s seen on <%s>\n", node_addr_str,
108		media_addr_str, b_ptr->name);
109}
110
111/**
112 * tipc_disc_recv_msg - handle incoming link setup message (request or response)
113 * @buf: buffer containing message
114 * @b_ptr: bearer that message arrived on
115 */
116void tipc_disc_recv_msg(struct sk_buff *buf, struct tipc_bearer *b_ptr)
117{
118	struct tipc_node *n_ptr;
119	struct tipc_link *link;
120	struct tipc_media_addr media_addr;
121	struct sk_buff *rbuf;
122	struct tipc_msg *msg = buf_msg(buf);
123	u32 dest = msg_dest_domain(msg);
124	u32 orig = msg_prevnode(msg);
125	u32 net_id = msg_bc_netid(msg);
126	u32 type = msg_type(msg);
127	u32 signature = msg_node_sig(msg);
128	int addr_mismatch;
129	int link_fully_up;
130
131	media_addr.broadcast = 1;
132	b_ptr->media->msg2addr(b_ptr, &media_addr, msg_media_addr(msg));
133	kfree_skb(buf);
134
135	/* Ensure message from node is valid and communication is permitted */
136	if (net_id != tipc_net_id)
137		return;
138	if (media_addr.broadcast)
139		return;
140	if (!tipc_addr_domain_valid(dest))
141		return;
142	if (!tipc_addr_node_valid(orig))
143		return;
144	if (orig == tipc_own_addr) {
145		if (memcmp(&media_addr, &b_ptr->addr, sizeof(media_addr)))
146			disc_dupl_alert(b_ptr, tipc_own_addr, &media_addr);
147		return;
148	}
149	if (!tipc_in_scope(dest, tipc_own_addr))
150		return;
151	if (!tipc_in_scope(b_ptr->link_req->domain, orig))
152		return;
153
154	/* Locate structure corresponding to requesting node */
155	n_ptr = tipc_node_find(orig);
156	if (!n_ptr) {
157		n_ptr = tipc_node_create(orig);
158		if (!n_ptr)
159			return;
160	}
161	tipc_node_lock(n_ptr);
162
163	/* Prepare to validate requesting node's signature and media address */
164	link = n_ptr->links[b_ptr->identity];
165	addr_mismatch = (link != NULL) &&
166		memcmp(&link->media_addr, &media_addr, sizeof(media_addr));
167
168	/*
169	 * Ensure discovery message's signature is correct
170	 *
171	 * If signature is incorrect and there is no working link to the node,
172	 * accept the new signature but invalidate all existing links to the
173	 * node so they won't re-activate without a new discovery message.
174	 *
175	 * If signature is incorrect and the requested link to the node is
176	 * working, accept the new signature. (This is an instance of delayed
177	 * rediscovery, where a link endpoint was able to re-establish contact
178	 * with its peer endpoint on a node that rebooted before receiving a
179	 * discovery message from that node.)
180	 *
181	 * If signature is incorrect and there is a working link to the node
182	 * that is not the requested link, reject the request (must be from
183	 * a duplicate node).
184	 */
185	if (signature != n_ptr->signature) {
186		if (n_ptr->working_links == 0) {
187			struct tipc_link *curr_link;
188			int i;
189
190			for (i = 0; i < MAX_BEARERS; i++) {
191				curr_link = n_ptr->links[i];
192				if (curr_link) {
193					memset(&curr_link->media_addr, 0,
194					       sizeof(media_addr));
195					tipc_link_reset(curr_link);
196				}
197			}
198			addr_mismatch = (link != NULL);
199		} else if (tipc_link_is_up(link) && !addr_mismatch) {
200			/* delayed rediscovery */
201		} else {
202			disc_dupl_alert(b_ptr, orig, &media_addr);
203			tipc_node_unlock(n_ptr);
204			return;
205		}
206		n_ptr->signature = signature;
207	}
208
209	/*
210	 * Ensure requesting node's media address is correct
211	 *
212	 * If media address doesn't match and the link is working, reject the
213	 * request (must be from a duplicate node).
214	 *
215	 * If media address doesn't match and the link is not working, accept
216	 * the new media address and reset the link to ensure it starts up
217	 * cleanly.
218	 */
219	if (addr_mismatch) {
220		if (tipc_link_is_up(link)) {
221			disc_dupl_alert(b_ptr, orig, &media_addr);
222			tipc_node_unlock(n_ptr);
223			return;
224		} else {
225			memcpy(&link->media_addr, &media_addr,
226			       sizeof(media_addr));
227			tipc_link_reset(link);
228		}
229	}
230
231	/* Create a link endpoint for this bearer, if necessary */
232	if (!link) {
233		link = tipc_link_create(n_ptr, b_ptr, &media_addr);
234		if (!link) {
235			tipc_node_unlock(n_ptr);
236			return;
237		}
238	}
239
240	/* Accept discovery message & send response, if necessary */
241	link_fully_up = link_working_working(link);
242
243	if ((type == DSC_REQ_MSG) && !link_fully_up && !b_ptr->blocked) {
244		rbuf = tipc_disc_init_msg(DSC_RESP_MSG, orig, b_ptr);
245		if (rbuf) {
246			tipc_bearer_send(b_ptr, rbuf, &media_addr);
247			kfree_skb(rbuf);
248		}
249	}
250
251	tipc_node_unlock(n_ptr);
252}
253
254/**
255 * disc_update - update frequency of periodic link setup requests
256 * @req: ptr to link request structure
257 *
258 * Reinitiates discovery process if discovery object has no associated nodes
259 * and is either not currently searching or is searching at a slow rate
260 */
261static void disc_update(struct tipc_link_req *req)
262{
263	if (!req->num_nodes) {
264		if ((req->timer_intv == TIPC_LINK_REQ_INACTIVE) ||
265		    (req->timer_intv > TIPC_LINK_REQ_FAST)) {
266			req->timer_intv = TIPC_LINK_REQ_INIT;
267			k_start_timer(&req->timer, req->timer_intv);
268		}
269	}
270}
271
272/**
273 * tipc_disc_add_dest - increment set of discovered nodes
274 * @req: ptr to link request structure
275 */
276void tipc_disc_add_dest(struct tipc_link_req *req)
277{
278	req->num_nodes++;
279}
280
281/**
282 * tipc_disc_remove_dest - decrement set of discovered nodes
283 * @req: ptr to link request structure
284 */
285void tipc_disc_remove_dest(struct tipc_link_req *req)
286{
287	req->num_nodes--;
288	disc_update(req);
289}
290
291/**
292 * disc_send_msg - send link setup request message
293 * @req: ptr to link request structure
294 */
295static void disc_send_msg(struct tipc_link_req *req)
296{
297	if (!req->bearer->blocked)
298		tipc_bearer_send(req->bearer, req->buf, &req->dest);
299}
300
301/**
302 * disc_timeout - send a periodic link setup request
303 * @req: ptr to link request structure
304 *
305 * Called whenever a link setup request timer associated with a bearer expires.
306 */
307static void disc_timeout(struct tipc_link_req *req)
308{
309	int max_delay;
310
311	spin_lock_bh(&req->bearer->lock);
312
313	/* Stop searching if only desired node has been found */
314	if (tipc_node(req->domain) && req->num_nodes) {
315		req->timer_intv = TIPC_LINK_REQ_INACTIVE;
316		goto exit;
317	}
318
319	/*
320	 * Send discovery message, then update discovery timer
321	 *
322	 * Keep doubling time between requests until limit is reached;
323	 * hold at fast polling rate if don't have any associated nodes,
324	 * otherwise hold at slow polling rate
325	 */
326	disc_send_msg(req);
327
328	req->timer_intv *= 2;
329	if (req->num_nodes)
330		max_delay = TIPC_LINK_REQ_SLOW;
331	else
332		max_delay = TIPC_LINK_REQ_FAST;
333	if (req->timer_intv > max_delay)
334		req->timer_intv = max_delay;
335
336	k_start_timer(&req->timer, req->timer_intv);
337exit:
338	spin_unlock_bh(&req->bearer->lock);
339}
340
341/**
342 * tipc_disc_create - create object to send periodic link setup requests
343 * @b_ptr: ptr to bearer issuing requests
344 * @dest: destination address for request messages
345 * @dest_domain: network domain to which links can be established
346 *
347 * Returns 0 if successful, otherwise -errno.
348 */
349int tipc_disc_create(struct tipc_bearer *b_ptr,
350		     struct tipc_media_addr *dest, u32 dest_domain)
351{
352	struct tipc_link_req *req;
353
354	req = kmalloc(sizeof(*req), GFP_ATOMIC);
355	if (!req)
356		return -ENOMEM;
357
358	req->buf = tipc_disc_init_msg(DSC_REQ_MSG, dest_domain, b_ptr);
359	if (!req->buf) {
360		kfree(req);
361		return -ENOMSG;
362	}
363
364	memcpy(&req->dest, dest, sizeof(*dest));
365	req->bearer = b_ptr;
366	req->domain = dest_domain;
367	req->num_nodes = 0;
368	req->timer_intv = TIPC_LINK_REQ_INIT;
369	k_init_timer(&req->timer, (Handler)disc_timeout, (unsigned long)req);
370	k_start_timer(&req->timer, req->timer_intv);
371	b_ptr->link_req = req;
372	disc_send_msg(req);
373	return 0;
374}
375
376/**
377 * tipc_disc_delete - destroy object sending periodic link setup requests
378 * @req: ptr to link request structure
379 */
380void tipc_disc_delete(struct tipc_link_req *req)
381{
382	k_cancel_timer(&req->timer);
383	k_term_timer(&req->timer);
384	kfree_skb(req->buf);
385	kfree(req);
386}
387