xref: /openbmc/linux/net/tipc/node.c (revision e868d61272caa648214046a096e5a6bfc068dc8c)
1 /*
2  * net/tipc/node.c: TIPC node management routines
3  *
4  * Copyright (c) 2000-2006, Ericsson AB
5  * Copyright (c) 2005-2006, 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 "config.h"
39 #include "node.h"
40 #include "cluster.h"
41 #include "net.h"
42 #include "addr.h"
43 #include "node_subscr.h"
44 #include "link.h"
45 #include "port.h"
46 #include "bearer.h"
47 #include "name_distr.h"
48 
49 void node_print(struct print_buf *buf, struct node *n_ptr, char *str);
50 static void node_lost_contact(struct node *n_ptr);
51 static void node_established_contact(struct node *n_ptr);
52 
53 struct node *tipc_nodes = NULL;	/* sorted list of nodes within cluster */
54 
55 u32 tipc_own_tag = 0;
56 
57 struct node *tipc_node_create(u32 addr)
58 {
59 	struct cluster *c_ptr;
60 	struct node *n_ptr;
61 	struct node **curr_node;
62 
63 	n_ptr = kzalloc(sizeof(*n_ptr),GFP_ATOMIC);
64 	if (!n_ptr) {
65 		warn("Node creation failed, no memory\n");
66 		return NULL;
67 	}
68 
69 	c_ptr = tipc_cltr_find(addr);
70 	if (!c_ptr) {
71 		c_ptr = tipc_cltr_create(addr);
72 	}
73 	if (!c_ptr) {
74 		kfree(n_ptr);
75 		return NULL;
76 	}
77 
78 	n_ptr->addr = addr;
79 		spin_lock_init(&n_ptr->lock);
80 	INIT_LIST_HEAD(&n_ptr->nsub);
81 	n_ptr->owner = c_ptr;
82 	tipc_cltr_attach_node(c_ptr, n_ptr);
83 	n_ptr->last_router = -1;
84 
85 	/* Insert node into ordered list */
86 	for (curr_node = &tipc_nodes; *curr_node;
87 	     curr_node = &(*curr_node)->next) {
88 		if (addr < (*curr_node)->addr) {
89 			n_ptr->next = *curr_node;
90 			break;
91 		}
92 	}
93 	(*curr_node) = n_ptr;
94 	return n_ptr;
95 }
96 
97 void tipc_node_delete(struct node *n_ptr)
98 {
99 	if (!n_ptr)
100 		return;
101 
102 #if 0
103 	/* Not needed because links are already deleted via tipc_bearer_stop() */
104 
105 	u32 l_num;
106 
107 	for (l_num = 0; l_num < MAX_BEARERS; l_num++) {
108 		link_delete(n_ptr->links[l_num]);
109 	}
110 #endif
111 
112 	dbg("node %x deleted\n", n_ptr->addr);
113 	kfree(n_ptr);
114 }
115 
116 
117 /**
118  * tipc_node_link_up - handle addition of link
119  *
120  * Link becomes active (alone or shared) or standby, depending on its priority.
121  */
122 
123 void tipc_node_link_up(struct node *n_ptr, struct link *l_ptr)
124 {
125 	struct link **active = &n_ptr->active_links[0];
126 
127 	n_ptr->working_links++;
128 
129 	info("Established link <%s> on network plane %c\n",
130 	     l_ptr->name, l_ptr->b_ptr->net_plane);
131 
132 	if (!active[0]) {
133 		dbg(" link %x into %x/%x\n", l_ptr, &active[0], &active[1]);
134 		active[0] = active[1] = l_ptr;
135 		node_established_contact(n_ptr);
136 		return;
137 	}
138 	if (l_ptr->priority < active[0]->priority) {
139 		info("New link <%s> becomes standby\n", l_ptr->name);
140 		return;
141 	}
142 	tipc_link_send_duplicate(active[0], l_ptr);
143 	if (l_ptr->priority == active[0]->priority) {
144 		active[0] = l_ptr;
145 		return;
146 	}
147 	info("Old link <%s> becomes standby\n", active[0]->name);
148 	if (active[1] != active[0])
149 		info("Old link <%s> becomes standby\n", active[1]->name);
150 	active[0] = active[1] = l_ptr;
151 }
152 
153 /**
154  * node_select_active_links - select active link
155  */
156 
157 static void node_select_active_links(struct node *n_ptr)
158 {
159 	struct link **active = &n_ptr->active_links[0];
160 	u32 i;
161 	u32 highest_prio = 0;
162 
163 	active[0] = active[1] = NULL;
164 
165 	for (i = 0; i < MAX_BEARERS; i++) {
166 		struct link *l_ptr = n_ptr->links[i];
167 
168 		if (!l_ptr || !tipc_link_is_up(l_ptr) ||
169 		    (l_ptr->priority < highest_prio))
170 			continue;
171 
172 		if (l_ptr->priority > highest_prio) {
173 			highest_prio = l_ptr->priority;
174 			active[0] = active[1] = l_ptr;
175 		} else {
176 			active[1] = l_ptr;
177 		}
178 	}
179 }
180 
181 /**
182  * tipc_node_link_down - handle loss of link
183  */
184 
185 void tipc_node_link_down(struct node *n_ptr, struct link *l_ptr)
186 {
187 	struct link **active;
188 
189 	n_ptr->working_links--;
190 
191 	if (!tipc_link_is_active(l_ptr)) {
192 		info("Lost standby link <%s> on network plane %c\n",
193 		     l_ptr->name, l_ptr->b_ptr->net_plane);
194 		return;
195 	}
196 	info("Lost link <%s> on network plane %c\n",
197 		l_ptr->name, l_ptr->b_ptr->net_plane);
198 
199 	active = &n_ptr->active_links[0];
200 	if (active[0] == l_ptr)
201 		active[0] = active[1];
202 	if (active[1] == l_ptr)
203 		active[1] = active[0];
204 	if (active[0] == l_ptr)
205 		node_select_active_links(n_ptr);
206 	if (tipc_node_is_up(n_ptr))
207 		tipc_link_changeover(l_ptr);
208 	else
209 		node_lost_contact(n_ptr);
210 }
211 
212 int tipc_node_has_active_links(struct node *n_ptr)
213 {
214 	return (n_ptr &&
215 		((n_ptr->active_links[0]) || (n_ptr->active_links[1])));
216 }
217 
218 int tipc_node_has_redundant_links(struct node *n_ptr)
219 {
220 	return (n_ptr->working_links > 1);
221 }
222 
223 static int tipc_node_has_active_routes(struct node *n_ptr)
224 {
225 	return (n_ptr && (n_ptr->last_router >= 0));
226 }
227 
228 int tipc_node_is_up(struct node *n_ptr)
229 {
230 	return (tipc_node_has_active_links(n_ptr) || tipc_node_has_active_routes(n_ptr));
231 }
232 
233 struct node *tipc_node_attach_link(struct link *l_ptr)
234 {
235 	struct node *n_ptr = tipc_node_find(l_ptr->addr);
236 
237 	if (!n_ptr)
238 		n_ptr = tipc_node_create(l_ptr->addr);
239 	if (n_ptr) {
240 		u32 bearer_id = l_ptr->b_ptr->identity;
241 		char addr_string[16];
242 
243 		if (n_ptr->link_cnt >= 2) {
244 			char addr_string[16];
245 
246 			err("Attempt to create third link to %s\n",
247 			    addr_string_fill(addr_string, n_ptr->addr));
248 			return NULL;
249 		}
250 
251 		if (!n_ptr->links[bearer_id]) {
252 			n_ptr->links[bearer_id] = l_ptr;
253 			tipc_net.zones[tipc_zone(l_ptr->addr)]->links++;
254 			n_ptr->link_cnt++;
255 			return n_ptr;
256 		}
257 		err("Attempt to establish second link on <%s> to %s \n",
258 		    l_ptr->b_ptr->publ.name,
259 		    addr_string_fill(addr_string, l_ptr->addr));
260 	}
261 	return NULL;
262 }
263 
264 void tipc_node_detach_link(struct node *n_ptr, struct link *l_ptr)
265 {
266 	n_ptr->links[l_ptr->b_ptr->identity] = NULL;
267 	tipc_net.zones[tipc_zone(l_ptr->addr)]->links--;
268 	n_ptr->link_cnt--;
269 }
270 
271 /*
272  * Routing table management - five cases to handle:
273  *
274  * 1: A link towards a zone/cluster external node comes up.
275  *    => Send a multicast message updating routing tables of all
276  *    system nodes within own cluster that the new destination
277  *    can be reached via this node.
278  *    (node.establishedContact()=>cluster.multicastNewRoute())
279  *
280  * 2: A link towards a slave node comes up.
281  *    => Send a multicast message updating routing tables of all
282  *    system nodes within own cluster that the new destination
283  *    can be reached via this node.
284  *    (node.establishedContact()=>cluster.multicastNewRoute())
285  *    => Send a  message to the slave node about existence
286  *    of all system nodes within cluster:
287  *    (node.establishedContact()=>cluster.sendLocalRoutes())
288  *
289  * 3: A new cluster local system node becomes available.
290  *    => Send message(s) to this particular node containing
291  *    information about all cluster external and slave
292  *     nodes which can be reached via this node.
293  *    (node.establishedContact()==>network.sendExternalRoutes())
294  *    (node.establishedContact()==>network.sendSlaveRoutes())
295  *    => Send messages to all directly connected slave nodes
296  *    containing information about the existence of the new node
297  *    (node.establishedContact()=>cluster.multicastNewRoute())
298  *
299  * 4: The link towards a zone/cluster external node or slave
300  *    node goes down.
301  *    => Send a multcast message updating routing tables of all
302  *    nodes within cluster that the new destination can not any
303  *    longer be reached via this node.
304  *    (node.lostAllLinks()=>cluster.bcastLostRoute())
305  *
306  * 5: A cluster local system node becomes unavailable.
307  *    => Remove all references to this node from the local
308  *    routing tables. Note: This is a completely node
309  *    local operation.
310  *    (node.lostAllLinks()=>network.removeAsRouter())
311  *    => Send messages to all directly connected slave nodes
312  *    containing information about loss of the node
313  *    (node.establishedContact()=>cluster.multicastLostRoute())
314  *
315  */
316 
317 static void node_established_contact(struct node *n_ptr)
318 {
319 	struct cluster *c_ptr;
320 
321 	dbg("node_established_contact:-> %x\n", n_ptr->addr);
322 	if (!tipc_node_has_active_routes(n_ptr) && in_own_cluster(n_ptr->addr)) {
323 		tipc_k_signal((Handler)tipc_named_node_up, n_ptr->addr);
324 	}
325 
326 	/* Syncronize broadcast acks */
327 	n_ptr->bclink.acked = tipc_bclink_get_last_sent();
328 
329 	if (is_slave(tipc_own_addr))
330 		return;
331 	if (!in_own_cluster(n_ptr->addr)) {
332 		/* Usage case 1 (see above) */
333 		c_ptr = tipc_cltr_find(tipc_own_addr);
334 		if (!c_ptr)
335 			c_ptr = tipc_cltr_create(tipc_own_addr);
336 		if (c_ptr)
337 			tipc_cltr_bcast_new_route(c_ptr, n_ptr->addr, 1,
338 						  tipc_max_nodes);
339 		return;
340 	}
341 
342 	c_ptr = n_ptr->owner;
343 	if (is_slave(n_ptr->addr)) {
344 		/* Usage case 2 (see above) */
345 		tipc_cltr_bcast_new_route(c_ptr, n_ptr->addr, 1, tipc_max_nodes);
346 		tipc_cltr_send_local_routes(c_ptr, n_ptr->addr);
347 		return;
348 	}
349 
350 	if (n_ptr->bclink.supported) {
351 		tipc_nmap_add(&tipc_cltr_bcast_nodes, n_ptr->addr);
352 		if (n_ptr->addr < tipc_own_addr)
353 			tipc_own_tag++;
354 	}
355 
356 	/* Case 3 (see above) */
357 	tipc_net_send_external_routes(n_ptr->addr);
358 	tipc_cltr_send_slave_routes(c_ptr, n_ptr->addr);
359 	tipc_cltr_bcast_new_route(c_ptr, n_ptr->addr, LOWEST_SLAVE,
360 				  tipc_highest_allowed_slave);
361 }
362 
363 static void node_lost_contact(struct node *n_ptr)
364 {
365 	struct cluster *c_ptr;
366 	struct node_subscr *ns, *tns;
367 	char addr_string[16];
368 	u32 i;
369 
370 	/* Clean up broadcast reception remains */
371 	n_ptr->bclink.gap_after = n_ptr->bclink.gap_to = 0;
372 	while (n_ptr->bclink.deferred_head) {
373 		struct sk_buff* buf = n_ptr->bclink.deferred_head;
374 		n_ptr->bclink.deferred_head = buf->next;
375 		buf_discard(buf);
376 	}
377 	if (n_ptr->bclink.defragm) {
378 		buf_discard(n_ptr->bclink.defragm);
379 		n_ptr->bclink.defragm = NULL;
380 	}
381 	if (in_own_cluster(n_ptr->addr) && n_ptr->bclink.supported) {
382 		tipc_bclink_acknowledge(n_ptr, mod(n_ptr->bclink.acked + 10000));
383 	}
384 
385 	/* Update routing tables */
386 	if (is_slave(tipc_own_addr)) {
387 		tipc_net_remove_as_router(n_ptr->addr);
388 	} else {
389 		if (!in_own_cluster(n_ptr->addr)) {
390 			/* Case 4 (see above) */
391 			c_ptr = tipc_cltr_find(tipc_own_addr);
392 			tipc_cltr_bcast_lost_route(c_ptr, n_ptr->addr, 1,
393 						   tipc_max_nodes);
394 		} else {
395 			/* Case 5 (see above) */
396 			c_ptr = tipc_cltr_find(n_ptr->addr);
397 			if (is_slave(n_ptr->addr)) {
398 				tipc_cltr_bcast_lost_route(c_ptr, n_ptr->addr, 1,
399 							   tipc_max_nodes);
400 			} else {
401 				if (n_ptr->bclink.supported) {
402 					tipc_nmap_remove(&tipc_cltr_bcast_nodes,
403 							 n_ptr->addr);
404 					if (n_ptr->addr < tipc_own_addr)
405 						tipc_own_tag--;
406 				}
407 				tipc_net_remove_as_router(n_ptr->addr);
408 				tipc_cltr_bcast_lost_route(c_ptr, n_ptr->addr,
409 							   LOWEST_SLAVE,
410 							   tipc_highest_allowed_slave);
411 			}
412 		}
413 	}
414 	if (tipc_node_has_active_routes(n_ptr))
415 		return;
416 
417 	info("Lost contact with %s\n",
418 	     addr_string_fill(addr_string, n_ptr->addr));
419 
420 	/* Abort link changeover */
421 	for (i = 0; i < MAX_BEARERS; i++) {
422 		struct link *l_ptr = n_ptr->links[i];
423 		if (!l_ptr)
424 			continue;
425 		l_ptr->reset_checkpoint = l_ptr->next_in_no;
426 		l_ptr->exp_msg_count = 0;
427 		tipc_link_reset_fragments(l_ptr);
428 	}
429 
430 	/* Notify subscribers */
431 	list_for_each_entry_safe(ns, tns, &n_ptr->nsub, nodesub_list) {
432 		ns->node = NULL;
433 		list_del_init(&ns->nodesub_list);
434 		tipc_k_signal((Handler)ns->handle_node_down,
435 			      (unsigned long)ns->usr_handle);
436 	}
437 }
438 
439 /**
440  * tipc_node_select_next_hop - find the next-hop node for a message
441  *
442  * Called by when cluster local lookup has failed.
443  */
444 
445 struct node *tipc_node_select_next_hop(u32 addr, u32 selector)
446 {
447 	struct node *n_ptr;
448 	u32 router_addr;
449 
450 	if (!tipc_addr_domain_valid(addr))
451 		return NULL;
452 
453 	/* Look for direct link to destination processsor */
454 	n_ptr = tipc_node_find(addr);
455 	if (n_ptr && tipc_node_has_active_links(n_ptr))
456 		return n_ptr;
457 
458 	/* Cluster local system nodes *must* have direct links */
459 	if (!is_slave(addr) && in_own_cluster(addr))
460 		return NULL;
461 
462 	/* Look for cluster local router with direct link to node */
463 	router_addr = tipc_node_select_router(n_ptr, selector);
464 	if (router_addr)
465 		return tipc_node_select(router_addr, selector);
466 
467 	/* Slave nodes can only be accessed within own cluster via a
468 	   known router with direct link -- if no router was found,give up */
469 	if (is_slave(addr))
470 		return NULL;
471 
472 	/* Inter zone/cluster -- find any direct link to remote cluster */
473 	addr = tipc_addr(tipc_zone(addr), tipc_cluster(addr), 0);
474 	n_ptr = tipc_net_select_remote_node(addr, selector);
475 	if (n_ptr && tipc_node_has_active_links(n_ptr))
476 		return n_ptr;
477 
478 	/* Last resort -- look for any router to anywhere in remote zone */
479 	router_addr =  tipc_net_select_router(addr, selector);
480 	if (router_addr)
481 		return tipc_node_select(router_addr, selector);
482 
483 	return NULL;
484 }
485 
486 /**
487  * tipc_node_select_router - select router to reach specified node
488  *
489  * Uses a deterministic and fair algorithm for selecting router node.
490  */
491 
492 u32 tipc_node_select_router(struct node *n_ptr, u32 ref)
493 {
494 	u32 ulim;
495 	u32 mask;
496 	u32 start;
497 	u32 r;
498 
499 	if (!n_ptr)
500 		return 0;
501 
502 	if (n_ptr->last_router < 0)
503 		return 0;
504 	ulim = ((n_ptr->last_router + 1) * 32) - 1;
505 
506 	/* Start entry must be random */
507 	mask = tipc_max_nodes;
508 	while (mask > ulim)
509 		mask >>= 1;
510 	start = ref & mask;
511 	r = start;
512 
513 	/* Lookup upwards with wrap-around */
514 	do {
515 		if (((n_ptr->routers[r / 32]) >> (r % 32)) & 1)
516 			break;
517 	} while (++r <= ulim);
518 	if (r > ulim) {
519 		r = 1;
520 		do {
521 			if (((n_ptr->routers[r / 32]) >> (r % 32)) & 1)
522 				break;
523 		} while (++r < start);
524 		assert(r != start);
525 	}
526 	assert(r && (r <= ulim));
527 	return tipc_addr(own_zone(), own_cluster(), r);
528 }
529 
530 void tipc_node_add_router(struct node *n_ptr, u32 router)
531 {
532 	u32 r_num = tipc_node(router);
533 
534 	n_ptr->routers[r_num / 32] =
535 		((1 << (r_num % 32)) | n_ptr->routers[r_num / 32]);
536 	n_ptr->last_router = tipc_max_nodes / 32;
537 	while ((--n_ptr->last_router >= 0) &&
538 	       !n_ptr->routers[n_ptr->last_router]);
539 }
540 
541 void tipc_node_remove_router(struct node *n_ptr, u32 router)
542 {
543 	u32 r_num = tipc_node(router);
544 
545 	if (n_ptr->last_router < 0)
546 		return;		/* No routes */
547 
548 	n_ptr->routers[r_num / 32] =
549 		((~(1 << (r_num % 32))) & (n_ptr->routers[r_num / 32]));
550 	n_ptr->last_router = tipc_max_nodes / 32;
551 	while ((--n_ptr->last_router >= 0) &&
552 	       !n_ptr->routers[n_ptr->last_router]);
553 
554 	if (!tipc_node_is_up(n_ptr))
555 		node_lost_contact(n_ptr);
556 }
557 
558 #if 0
559 void node_print(struct print_buf *buf, struct node *n_ptr, char *str)
560 {
561 	u32 i;
562 
563 	tipc_printf(buf, "\n\n%s", str);
564 	for (i = 0; i < MAX_BEARERS; i++) {
565 		if (!n_ptr->links[i])
566 			continue;
567 		tipc_printf(buf, "Links[%u]: %x, ", i, n_ptr->links[i]);
568 	}
569 	tipc_printf(buf, "Active links: [%x,%x]\n",
570 		    n_ptr->active_links[0], n_ptr->active_links[1]);
571 }
572 #endif
573 
574 u32 tipc_available_nodes(const u32 domain)
575 {
576 	struct node *n_ptr;
577 	u32 cnt = 0;
578 
579 	for (n_ptr = tipc_nodes; n_ptr; n_ptr = n_ptr->next) {
580 		if (!in_scope(domain, n_ptr->addr))
581 			continue;
582 		if (tipc_node_is_up(n_ptr))
583 			cnt++;
584 	}
585 	return cnt;
586 }
587 
588 struct sk_buff *tipc_node_get_nodes(const void *req_tlv_area, int req_tlv_space)
589 {
590 	u32 domain;
591 	struct sk_buff *buf;
592 	struct node *n_ptr;
593 	struct tipc_node_info node_info;
594 	u32 payload_size;
595 
596 	if (!TLV_CHECK(req_tlv_area, req_tlv_space, TIPC_TLV_NET_ADDR))
597 		return tipc_cfg_reply_error_string(TIPC_CFG_TLV_ERROR);
598 
599 	domain = ntohl(*(__be32 *)TLV_DATA(req_tlv_area));
600 	if (!tipc_addr_domain_valid(domain))
601 		return tipc_cfg_reply_error_string(TIPC_CFG_INVALID_VALUE
602 						   " (network address)");
603 
604 	if (!tipc_nodes)
605 		return tipc_cfg_reply_none();
606 
607 	/* For now, get space for all other nodes
608 	   (will need to modify this when slave nodes are supported */
609 
610 	payload_size = TLV_SPACE(sizeof(node_info)) * (tipc_max_nodes - 1);
611 	if (payload_size > 32768u)
612 		return tipc_cfg_reply_error_string(TIPC_CFG_NOT_SUPPORTED
613 						   " (too many nodes)");
614 	buf = tipc_cfg_reply_alloc(payload_size);
615 	if (!buf)
616 		return NULL;
617 
618 	/* Add TLVs for all nodes in scope */
619 
620 	for (n_ptr = tipc_nodes; n_ptr; n_ptr = n_ptr->next) {
621 		if (!in_scope(domain, n_ptr->addr))
622 			continue;
623 		node_info.addr = htonl(n_ptr->addr);
624 		node_info.up = htonl(tipc_node_is_up(n_ptr));
625 		tipc_cfg_append_tlv(buf, TIPC_TLV_NODE_INFO,
626 				    &node_info, sizeof(node_info));
627 	}
628 
629 	return buf;
630 }
631 
632 struct sk_buff *tipc_node_get_links(const void *req_tlv_area, int req_tlv_space)
633 {
634 	u32 domain;
635 	struct sk_buff *buf;
636 	struct node *n_ptr;
637 	struct tipc_link_info link_info;
638 	u32 payload_size;
639 
640 	if (!TLV_CHECK(req_tlv_area, req_tlv_space, TIPC_TLV_NET_ADDR))
641 		return tipc_cfg_reply_error_string(TIPC_CFG_TLV_ERROR);
642 
643 	domain = ntohl(*(__be32 *)TLV_DATA(req_tlv_area));
644 	if (!tipc_addr_domain_valid(domain))
645 		return tipc_cfg_reply_error_string(TIPC_CFG_INVALID_VALUE
646 						   " (network address)");
647 
648 	if (tipc_mode != TIPC_NET_MODE)
649 		return tipc_cfg_reply_none();
650 
651 	/* Get space for all unicast links + multicast link */
652 
653 	payload_size = TLV_SPACE(sizeof(link_info)) *
654 		(tipc_net.zones[tipc_zone(tipc_own_addr)]->links + 1);
655 	if (payload_size > 32768u)
656 		return tipc_cfg_reply_error_string(TIPC_CFG_NOT_SUPPORTED
657 						   " (too many links)");
658 	buf = tipc_cfg_reply_alloc(payload_size);
659 	if (!buf)
660 		return NULL;
661 
662 	/* Add TLV for broadcast link */
663 
664 	link_info.dest = htonl(tipc_own_addr & 0xfffff00);
665 	link_info.up = htonl(1);
666 	sprintf(link_info.str, tipc_bclink_name);
667 	tipc_cfg_append_tlv(buf, TIPC_TLV_LINK_INFO, &link_info, sizeof(link_info));
668 
669 	/* Add TLVs for any other links in scope */
670 
671 	for (n_ptr = tipc_nodes; n_ptr; n_ptr = n_ptr->next) {
672 		u32 i;
673 
674 		if (!in_scope(domain, n_ptr->addr))
675 			continue;
676 		for (i = 0; i < MAX_BEARERS; i++) {
677 			if (!n_ptr->links[i])
678 				continue;
679 			link_info.dest = htonl(n_ptr->addr);
680 			link_info.up = htonl(tipc_link_is_up(n_ptr->links[i]));
681 			strcpy(link_info.str, n_ptr->links[i]->name);
682 			tipc_cfg_append_tlv(buf, TIPC_TLV_LINK_INFO,
683 					    &link_info, sizeof(link_info));
684 		}
685 	}
686 
687 	return buf;
688 }
689