xref: /linux/net/tipc/node.c (revision d8327c784b51b57dac2c26cfad87dce0d68dfd98)
1 /*
2  * net/tipc/node.c: TIPC node management routines
3  *
4  * Copyright (c) 2000-2006, Ericsson AB
5  * Copyright (c) 2005, 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 = kmalloc(sizeof(*n_ptr),GFP_ATOMIC);
64         if (n_ptr != NULL) {
65                 memset(n_ptr, 0, sizeof(*n_ptr));
66                 n_ptr->addr = addr;
67                 n_ptr->lock =  SPIN_LOCK_UNLOCKED;
68                 INIT_LIST_HEAD(&n_ptr->nsub);
69 
70 		c_ptr = tipc_cltr_find(addr);
71                 if (c_ptr == NULL)
72                         c_ptr = tipc_cltr_create(addr);
73                 if (c_ptr != NULL) {
74                         n_ptr->owner = c_ptr;
75                         tipc_cltr_attach_node(c_ptr, n_ptr);
76                         n_ptr->last_router = -1;
77 
78                         /* Insert node into ordered list */
79                         for (curr_node = &tipc_nodes; *curr_node;
80 			     curr_node = &(*curr_node)->next) {
81                                 if (addr < (*curr_node)->addr) {
82                                         n_ptr->next = *curr_node;
83                                         break;
84                                 }
85                         }
86                         (*curr_node) = n_ptr;
87                 } else {
88                         kfree(n_ptr);
89                         n_ptr = NULL;
90                 }
91         }
92 	return n_ptr;
93 }
94 
95 void tipc_node_delete(struct node *n_ptr)
96 {
97 	if (!n_ptr)
98 		return;
99 
100 #if 0
101 	/* Not needed because links are already deleted via tipc_bearer_stop() */
102 
103 	u32 l_num;
104 
105 	for (l_num = 0; l_num < MAX_BEARERS; l_num++) {
106 		link_delete(n_ptr->links[l_num]);
107 	}
108 #endif
109 
110 	dbg("node %x deleted\n", n_ptr->addr);
111 	kfree(n_ptr);
112 }
113 
114 
115 /**
116  * tipc_node_link_up - handle addition of link
117  *
118  * Link becomes active (alone or shared) or standby, depending on its priority.
119  */
120 
121 void tipc_node_link_up(struct node *n_ptr, struct link *l_ptr)
122 {
123 	struct link **active = &n_ptr->active_links[0];
124 
125 	info("Established link <%s> on network plane %c\n",
126 	     l_ptr->name, l_ptr->b_ptr->net_plane);
127 
128 	if (!active[0]) {
129 		dbg(" link %x into %x/%x\n", l_ptr, &active[0], &active[1]);
130 		active[0] = active[1] = l_ptr;
131 		node_established_contact(n_ptr);
132 		return;
133 	}
134 	if (l_ptr->priority < active[0]->priority) {
135 		info("Link is standby\n");
136 		return;
137 	}
138 	tipc_link_send_duplicate(active[0], l_ptr);
139 	if (l_ptr->priority == active[0]->priority) {
140 		active[0] = l_ptr;
141 		return;
142 	}
143 	info("Link <%s> on network plane %c becomes standby\n",
144 	     active[0]->name, active[0]->b_ptr->net_plane);
145 	active[0] = active[1] = l_ptr;
146 }
147 
148 /**
149  * node_select_active_links - select active link
150  */
151 
152 static void node_select_active_links(struct node *n_ptr)
153 {
154 	struct link **active = &n_ptr->active_links[0];
155 	u32 i;
156 	u32 highest_prio = 0;
157 
158         active[0] = active[1] = 0;
159 
160 	for (i = 0; i < MAX_BEARERS; i++) {
161                 struct link *l_ptr = n_ptr->links[i];
162 
163 		if (!l_ptr || !tipc_link_is_up(l_ptr) ||
164 		    (l_ptr->priority < highest_prio))
165 			continue;
166 
167 		if (l_ptr->priority > highest_prio) {
168                         highest_prio = l_ptr->priority;
169 			active[0] = active[1] = l_ptr;
170 		} else {
171 			active[1] = l_ptr;
172 		}
173 	}
174 }
175 
176 /**
177  * tipc_node_link_down - handle loss of link
178  */
179 
180 void tipc_node_link_down(struct node *n_ptr, struct link *l_ptr)
181 {
182 	struct link **active;
183 
184 	if (!tipc_link_is_active(l_ptr)) {
185 		info("Lost standby link <%s> on network plane %c\n",
186 		     l_ptr->name, l_ptr->b_ptr->net_plane);
187 		return;
188 	}
189 	info("Lost link <%s> on network plane %c\n",
190 		l_ptr->name, l_ptr->b_ptr->net_plane);
191 
192 	active = &n_ptr->active_links[0];
193 	if (active[0] == l_ptr)
194 		active[0] = active[1];
195 	if (active[1] == l_ptr)
196 		active[1] = active[0];
197 	if (active[0] == l_ptr)
198 		node_select_active_links(n_ptr);
199 	if (tipc_node_is_up(n_ptr))
200 		tipc_link_changeover(l_ptr);
201 	else
202 		node_lost_contact(n_ptr);
203 }
204 
205 int tipc_node_has_active_links(struct node *n_ptr)
206 {
207 	return (n_ptr &&
208 		((n_ptr->active_links[0]) || (n_ptr->active_links[1])));
209 }
210 
211 int tipc_node_has_redundant_links(struct node *n_ptr)
212 {
213 	return (tipc_node_has_active_links(n_ptr) &&
214 		(n_ptr->active_links[0] != n_ptr->active_links[1]));
215 }
216 
217 int tipc_node_has_active_routes(struct node *n_ptr)
218 {
219 	return (n_ptr && (n_ptr->last_router >= 0));
220 }
221 
222 int tipc_node_is_up(struct node *n_ptr)
223 {
224 	return (tipc_node_has_active_links(n_ptr) || tipc_node_has_active_routes(n_ptr));
225 }
226 
227 struct node *tipc_node_attach_link(struct link *l_ptr)
228 {
229 	struct node *n_ptr = tipc_node_find(l_ptr->addr);
230 
231 	if (!n_ptr)
232 		n_ptr = tipc_node_create(l_ptr->addr);
233         if (n_ptr) {
234 		u32 bearer_id = l_ptr->b_ptr->identity;
235 		char addr_string[16];
236 
237                 assert(bearer_id < MAX_BEARERS);
238                 if (n_ptr->link_cnt >= 2) {
239 			char addr_string[16];
240 
241                         err("Attempt to create third link to %s\n",
242 			    addr_string_fill(addr_string, n_ptr->addr));
243                         return 0;
244                 }
245 
246                 if (!n_ptr->links[bearer_id]) {
247                         n_ptr->links[bearer_id] = l_ptr;
248                         tipc_net.zones[tipc_zone(l_ptr->addr)]->links++;
249                         n_ptr->link_cnt++;
250                         return n_ptr;
251                 }
252                 err("Attempt to establish second link on <%s> to <%s> \n",
253                     l_ptr->b_ptr->publ.name,
254 		    addr_string_fill(addr_string, l_ptr->addr));
255         }
256 	return 0;
257 }
258 
259 void tipc_node_detach_link(struct node *n_ptr, struct link *l_ptr)
260 {
261 	n_ptr->links[l_ptr->b_ptr->identity] = 0;
262 	tipc_net.zones[tipc_zone(l_ptr->addr)]->links--;
263 	n_ptr->link_cnt--;
264 }
265 
266 /*
267  * Routing table management - five cases to handle:
268  *
269  * 1: A link towards a zone/cluster external node comes up.
270  *    => Send a multicast message updating routing tables of all
271  *    system nodes within own cluster that the new destination
272  *    can be reached via this node.
273  *    (node.establishedContact()=>cluster.multicastNewRoute())
274  *
275  * 2: A link towards a slave node comes up.
276  *    => Send a multicast message updating routing tables of all
277  *    system nodes within own cluster that the new destination
278  *    can be reached via this node.
279  *    (node.establishedContact()=>cluster.multicastNewRoute())
280  *    => Send a  message to the slave node about existence
281  *    of all system nodes within cluster:
282  *    (node.establishedContact()=>cluster.sendLocalRoutes())
283  *
284  * 3: A new cluster local system node becomes available.
285  *    => Send message(s) to this particular node containing
286  *    information about all cluster external and slave
287  *     nodes which can be reached via this node.
288  *    (node.establishedContact()==>network.sendExternalRoutes())
289  *    (node.establishedContact()==>network.sendSlaveRoutes())
290  *    => Send messages to all directly connected slave nodes
291  *    containing information about the existence of the new node
292  *    (node.establishedContact()=>cluster.multicastNewRoute())
293  *
294  * 4: The link towards a zone/cluster external node or slave
295  *    node goes down.
296  *    => Send a multcast message updating routing tables of all
297  *    nodes within cluster that the new destination can not any
298  *    longer be reached via this node.
299  *    (node.lostAllLinks()=>cluster.bcastLostRoute())
300  *
301  * 5: A cluster local system node becomes unavailable.
302  *    => Remove all references to this node from the local
303  *    routing tables. Note: This is a completely node
304  *    local operation.
305  *    (node.lostAllLinks()=>network.removeAsRouter())
306  *    => Send messages to all directly connected slave nodes
307  *    containing information about loss of the node
308  *    (node.establishedContact()=>cluster.multicastLostRoute())
309  *
310  */
311 
312 static void node_established_contact(struct node *n_ptr)
313 {
314 	struct cluster *c_ptr;
315 
316 	dbg("node_established_contact:-> %x\n", n_ptr->addr);
317 	if (!tipc_node_has_active_routes(n_ptr)) {
318 		tipc_k_signal((Handler)tipc_named_node_up, n_ptr->addr);
319 	}
320 
321         /* Syncronize broadcast acks */
322         n_ptr->bclink.acked = tipc_bclink_get_last_sent();
323 
324 	if (is_slave(tipc_own_addr))
325 		return;
326 	if (!in_own_cluster(n_ptr->addr)) {
327 		/* Usage case 1 (see above) */
328 		c_ptr = tipc_cltr_find(tipc_own_addr);
329 		if (!c_ptr)
330 			c_ptr = tipc_cltr_create(tipc_own_addr);
331                 if (c_ptr)
332                         tipc_cltr_bcast_new_route(c_ptr, n_ptr->addr, 1,
333 						  tipc_max_nodes);
334 		return;
335 	}
336 
337 	c_ptr = n_ptr->owner;
338 	if (is_slave(n_ptr->addr)) {
339 		/* Usage case 2 (see above) */
340 		tipc_cltr_bcast_new_route(c_ptr, n_ptr->addr, 1, tipc_max_nodes);
341 		tipc_cltr_send_local_routes(c_ptr, n_ptr->addr);
342 		return;
343 	}
344 
345 	if (n_ptr->bclink.supported) {
346 		tipc_nmap_add(&tipc_cltr_bcast_nodes, n_ptr->addr);
347 		if (n_ptr->addr < tipc_own_addr)
348 			tipc_own_tag++;
349 	}
350 
351 	/* Case 3 (see above) */
352 	tipc_net_send_external_routes(n_ptr->addr);
353 	tipc_cltr_send_slave_routes(c_ptr, n_ptr->addr);
354 	tipc_cltr_bcast_new_route(c_ptr, n_ptr->addr, LOWEST_SLAVE,
355 				  tipc_highest_allowed_slave);
356 }
357 
358 static void node_lost_contact(struct node *n_ptr)
359 {
360 	struct cluster *c_ptr;
361 	struct node_subscr *ns, *tns;
362 	char addr_string[16];
363 	u32 i;
364 
365         /* Clean up broadcast reception remains */
366         n_ptr->bclink.gap_after = n_ptr->bclink.gap_to = 0;
367         while (n_ptr->bclink.deferred_head) {
368                 struct sk_buff* buf = n_ptr->bclink.deferred_head;
369                 n_ptr->bclink.deferred_head = buf->next;
370                 buf_discard(buf);
371         }
372         if (n_ptr->bclink.defragm) {
373                 buf_discard(n_ptr->bclink.defragm);
374                 n_ptr->bclink.defragm = NULL;
375         }
376         if (in_own_cluster(n_ptr->addr) && n_ptr->bclink.supported) {
377                 tipc_bclink_acknowledge(n_ptr, mod(n_ptr->bclink.acked + 10000));
378         }
379 
380         /* Update routing tables */
381 	if (is_slave(tipc_own_addr)) {
382 		tipc_net_remove_as_router(n_ptr->addr);
383 	} else {
384 		if (!in_own_cluster(n_ptr->addr)) {
385 			/* Case 4 (see above) */
386 			c_ptr = tipc_cltr_find(tipc_own_addr);
387 			tipc_cltr_bcast_lost_route(c_ptr, n_ptr->addr, 1,
388 						   tipc_max_nodes);
389 		} else {
390 			/* Case 5 (see above) */
391 			c_ptr = tipc_cltr_find(n_ptr->addr);
392 			if (is_slave(n_ptr->addr)) {
393 				tipc_cltr_bcast_lost_route(c_ptr, n_ptr->addr, 1,
394 							   tipc_max_nodes);
395 			} else {
396 				if (n_ptr->bclink.supported) {
397 					tipc_nmap_remove(&tipc_cltr_bcast_nodes,
398 							 n_ptr->addr);
399 					if (n_ptr->addr < tipc_own_addr)
400 						tipc_own_tag--;
401 				}
402 				tipc_net_remove_as_router(n_ptr->addr);
403 				tipc_cltr_bcast_lost_route(c_ptr, n_ptr->addr,
404 							   LOWEST_SLAVE,
405 							   tipc_highest_allowed_slave);
406 			}
407 		}
408 	}
409 	if (tipc_node_has_active_routes(n_ptr))
410 		return;
411 
412 	info("Lost contact with %s\n",
413 	     addr_string_fill(addr_string, n_ptr->addr));
414 
415 	/* Abort link changeover */
416 	for (i = 0; i < MAX_BEARERS; i++) {
417 		struct link *l_ptr = n_ptr->links[i];
418 		if (!l_ptr)
419 			continue;
420 		l_ptr->reset_checkpoint = l_ptr->next_in_no;
421 		l_ptr->exp_msg_count = 0;
422 		tipc_link_reset_fragments(l_ptr);
423 	}
424 
425 	/* Notify subscribers */
426 	list_for_each_entry_safe(ns, tns, &n_ptr->nsub, nodesub_list) {
427                 ns->node = 0;
428 		list_del_init(&ns->nodesub_list);
429 		tipc_k_signal((Handler)ns->handle_node_down,
430 			      (unsigned long)ns->usr_handle);
431 	}
432 }
433 
434 /**
435  * tipc_node_select_next_hop - find the next-hop node for a message
436  *
437  * Called by when cluster local lookup has failed.
438  */
439 
440 struct node *tipc_node_select_next_hop(u32 addr, u32 selector)
441 {
442 	struct node *n_ptr;
443 	u32 router_addr;
444 
445         if (!tipc_addr_domain_valid(addr))
446                 return 0;
447 
448 	/* Look for direct link to destination processsor */
449 	n_ptr = tipc_node_find(addr);
450 	if (n_ptr && tipc_node_has_active_links(n_ptr))
451                 return n_ptr;
452 
453 	/* Cluster local system nodes *must* have direct links */
454 	if (!is_slave(addr) && in_own_cluster(addr))
455 		return 0;
456 
457 	/* Look for cluster local router with direct link to node */
458 	router_addr = tipc_node_select_router(n_ptr, selector);
459 	if (router_addr)
460                 return tipc_node_select(router_addr, selector);
461 
462 	/* Slave nodes can only be accessed within own cluster via a
463 	   known router with direct link -- if no router was found,give up */
464 	if (is_slave(addr))
465 		return 0;
466 
467 	/* Inter zone/cluster -- find any direct link to remote cluster */
468 	addr = tipc_addr(tipc_zone(addr), tipc_cluster(addr), 0);
469 	n_ptr = tipc_net_select_remote_node(addr, selector);
470 	if (n_ptr && tipc_node_has_active_links(n_ptr))
471                 return n_ptr;
472 
473 	/* Last resort -- look for any router to anywhere in remote zone */
474 	router_addr =  tipc_net_select_router(addr, selector);
475 	if (router_addr)
476                 return tipc_node_select(router_addr, selector);
477 
478         return 0;
479 }
480 
481 /**
482  * tipc_node_select_router - select router to reach specified node
483  *
484  * Uses a deterministic and fair algorithm for selecting router node.
485  */
486 
487 u32 tipc_node_select_router(struct node *n_ptr, u32 ref)
488 {
489 	u32 ulim;
490 	u32 mask;
491 	u32 start;
492 	u32 r;
493 
494         if (!n_ptr)
495                 return 0;
496 
497 	if (n_ptr->last_router < 0)
498 		return 0;
499 	ulim = ((n_ptr->last_router + 1) * 32) - 1;
500 
501 	/* Start entry must be random */
502 	mask = tipc_max_nodes;
503 	while (mask > ulim)
504 		mask >>= 1;
505 	start = ref & mask;
506 	r = start;
507 
508 	/* Lookup upwards with wrap-around */
509 	do {
510 		if (((n_ptr->routers[r / 32]) >> (r % 32)) & 1)
511 			break;
512 	} while (++r <= ulim);
513 	if (r > ulim) {
514 		r = 1;
515 		do {
516 			if (((n_ptr->routers[r / 32]) >> (r % 32)) & 1)
517 				break;
518 		} while (++r < start);
519 		assert(r != start);
520 	}
521 	assert(r && (r <= ulim));
522 	return tipc_addr(own_zone(), own_cluster(), r);
523 }
524 
525 void tipc_node_add_router(struct node *n_ptr, u32 router)
526 {
527 	u32 r_num = tipc_node(router);
528 
529 	n_ptr->routers[r_num / 32] =
530 		((1 << (r_num % 32)) | n_ptr->routers[r_num / 32]);
531 	n_ptr->last_router = tipc_max_nodes / 32;
532 	while ((--n_ptr->last_router >= 0) &&
533 	       !n_ptr->routers[n_ptr->last_router]);
534 }
535 
536 void tipc_node_remove_router(struct node *n_ptr, u32 router)
537 {
538 	u32 r_num = tipc_node(router);
539 
540 	if (n_ptr->last_router < 0)
541 		return;		/* No routes */
542 
543 	n_ptr->routers[r_num / 32] =
544 		((~(1 << (r_num % 32))) & (n_ptr->routers[r_num / 32]));
545 	n_ptr->last_router = tipc_max_nodes / 32;
546 	while ((--n_ptr->last_router >= 0) &&
547 	       !n_ptr->routers[n_ptr->last_router]);
548 
549 	if (!tipc_node_is_up(n_ptr))
550 		node_lost_contact(n_ptr);
551 }
552 
553 #if 0
554 void node_print(struct print_buf *buf, struct node *n_ptr, char *str)
555 {
556 	u32 i;
557 
558 	tipc_printf(buf, "\n\n%s", str);
559 	for (i = 0; i < MAX_BEARERS; i++) {
560 		if (!n_ptr->links[i])
561 			continue;
562 		tipc_printf(buf, "Links[%u]: %x, ", i, n_ptr->links[i]);
563 	}
564 	tipc_printf(buf, "Active links: [%x,%x]\n",
565 		    n_ptr->active_links[0], n_ptr->active_links[1]);
566 }
567 #endif
568 
569 u32 tipc_available_nodes(const u32 domain)
570 {
571 	struct node *n_ptr;
572 	u32 cnt = 0;
573 
574 	for (n_ptr = tipc_nodes; n_ptr; n_ptr = n_ptr->next) {
575 		if (!in_scope(domain, n_ptr->addr))
576 			continue;
577 		if (tipc_node_is_up(n_ptr))
578 			cnt++;
579 	}
580 	return cnt;
581 }
582 
583 struct sk_buff *tipc_node_get_nodes(const void *req_tlv_area, int req_tlv_space)
584 {
585 	u32 domain;
586 	struct sk_buff *buf;
587 	struct node *n_ptr;
588         struct tipc_node_info node_info;
589 
590 	if (!TLV_CHECK(req_tlv_area, req_tlv_space, TIPC_TLV_NET_ADDR))
591 		return tipc_cfg_reply_error_string(TIPC_CFG_TLV_ERROR);
592 
593 	domain = *(u32 *)TLV_DATA(req_tlv_area);
594 	domain = ntohl(domain);
595 	if (!tipc_addr_domain_valid(domain))
596 		return tipc_cfg_reply_error_string(TIPC_CFG_INVALID_VALUE
597 						   " (network address)");
598 
599         if (!tipc_nodes)
600                 return tipc_cfg_reply_none();
601 
602 	/* For now, get space for all other nodes
603 	   (will need to modify this when slave nodes are supported */
604 
605 	buf = tipc_cfg_reply_alloc(TLV_SPACE(sizeof(node_info)) *
606 				   (tipc_max_nodes - 1));
607 	if (!buf)
608 		return NULL;
609 
610 	/* Add TLVs for all nodes in scope */
611 
612 	for (n_ptr = tipc_nodes; n_ptr; n_ptr = n_ptr->next) {
613 		if (!in_scope(domain, n_ptr->addr))
614 			continue;
615                 node_info.addr = htonl(n_ptr->addr);
616                 node_info.up = htonl(tipc_node_is_up(n_ptr));
617 		tipc_cfg_append_tlv(buf, TIPC_TLV_NODE_INFO,
618 				    &node_info, sizeof(node_info));
619 	}
620 
621 	return buf;
622 }
623 
624 struct sk_buff *tipc_node_get_links(const void *req_tlv_area, int req_tlv_space)
625 {
626 	u32 domain;
627 	struct sk_buff *buf;
628 	struct node *n_ptr;
629         struct tipc_link_info link_info;
630 
631 	if (!TLV_CHECK(req_tlv_area, req_tlv_space, TIPC_TLV_NET_ADDR))
632 		return tipc_cfg_reply_error_string(TIPC_CFG_TLV_ERROR);
633 
634 	domain = *(u32 *)TLV_DATA(req_tlv_area);
635 	domain = ntohl(domain);
636 	if (!tipc_addr_domain_valid(domain))
637 		return tipc_cfg_reply_error_string(TIPC_CFG_INVALID_VALUE
638 						   " (network address)");
639 
640         if (!tipc_nodes)
641                 return tipc_cfg_reply_none();
642 
643 	/* For now, get space for 2 links to all other nodes + bcast link
644 	   (will need to modify this when slave nodes are supported */
645 
646 	buf = tipc_cfg_reply_alloc(TLV_SPACE(sizeof(link_info)) *
647 				   (2 * (tipc_max_nodes - 1) + 1));
648 	if (!buf)
649 		return NULL;
650 
651 	/* Add TLV for broadcast link */
652 
653         link_info.dest = tipc_own_addr & 0xfffff00;
654 	link_info.dest = htonl(link_info.dest);
655         link_info.up = htonl(1);
656         sprintf(link_info.str, tipc_bclink_name);
657 	tipc_cfg_append_tlv(buf, TIPC_TLV_LINK_INFO, &link_info, sizeof(link_info));
658 
659 	/* Add TLVs for any other links in scope */
660 
661 	for (n_ptr = tipc_nodes; n_ptr; n_ptr = n_ptr->next) {
662                 u32 i;
663 
664 		if (!in_scope(domain, n_ptr->addr))
665 			continue;
666                 for (i = 0; i < MAX_BEARERS; i++) {
667                         if (!n_ptr->links[i])
668                                 continue;
669                         link_info.dest = htonl(n_ptr->addr);
670                         link_info.up = htonl(tipc_link_is_up(n_ptr->links[i]));
671                         strcpy(link_info.str, n_ptr->links[i]->name);
672 			tipc_cfg_append_tlv(buf, TIPC_TLV_LINK_INFO,
673 					    &link_info, sizeof(link_info));
674                 }
675 	}
676 
677 	return buf;
678 }
679