net/tipc/discover.c

   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  */
  57 struct 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  */
  73 static 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  */
  98 static 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  */
 116 void 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(&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                         b_ptr->media->send_msg(rbuf, b_ptr, &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  */
 261 static 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  */
 276 void 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  */
 285 void 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  */
 295 static 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  */
 307 static 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);
 337 exit:
 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  */
 349 int 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  */
 380 void 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 }