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, u32 dest_domain,
  74                                           struct tipc_bearer *b_ptr)
  75 {
  76         struct sk_buff *buf = tipc_buf_acquire(INT_H_SIZE);
  77         struct tipc_msg *msg;
  78
  79         if (buf) {
  80                 msg = buf_msg(buf);
  81                 tipc_msg_init(msg, LINK_CONFIG, type, INT_H_SIZE, dest_domain);
  82                 msg_set_non_seq(msg, 1);
  83                 msg_set_node_sig(msg, tipc_random);
  84                 msg_set_dest_domain(msg, dest_domain);
  85                 msg_set_bc_netid(msg, tipc_net_id);
  86                 b_ptr->media->addr2msg(&b_ptr->addr, msg_media_addr(msg));
  87         }
  88         return buf;
  89 }
  90
  91 /**
  92  * disc_dupl_alert - issue node address duplication alert
  93  * @b_ptr: pointer to bearer detecting duplication
  94  * @node_addr: duplicated node address
  95  * @media_addr: media address advertised by duplicated node
  96  */
  97 static void disc_dupl_alert(struct tipc_bearer *b_ptr, u32 node_addr,
  98                             struct tipc_media_addr *media_addr)
  99 {
 100         char node_addr_str[16];
 101         char media_addr_str[64];
 102
 103         tipc_addr_string_fill(node_addr_str, node_addr);
 104         tipc_media_addr_printf(media_addr_str, sizeof(media_addr_str),
 105                                media_addr);
 106         pr_warn("Duplicate %s using %s seen on <%s>\n", node_addr_str,
 107                 media_addr_str, b_ptr->name);
 108 }
 109
 110 /**
 111  * tipc_disc_recv_msg - handle incoming link setup message (request or response)
 112  * @buf: buffer containing message
 113  * @b_ptr: bearer that message arrived on
 114  */
 115 void tipc_disc_recv_msg(struct sk_buff *buf, struct tipc_bearer *b_ptr)
 116 {
 117         struct tipc_node *n_ptr;
 118         struct tipc_link *link;
 119         struct tipc_media_addr media_addr;
 120         struct sk_buff *rbuf;
 121         struct tipc_msg *msg = buf_msg(buf);
 122         u32 dest = msg_dest_domain(msg);
 123         u32 orig = msg_prevnode(msg);
 124         u32 net_id = msg_bc_netid(msg);
 125         u32 type = msg_type(msg);
 126         u32 signature = msg_node_sig(msg);
 127         int addr_mismatch;
 128         int link_fully_up;
 129
 130         media_addr.broadcast = 1;
 131         b_ptr->media->msg2addr(b_ptr, &media_addr, msg_media_addr(msg));
 132         kfree_skb(buf);
 133
 134         /* Ensure message from node is valid and communication is permitted */
 135         if (net_id != tipc_net_id)
 136                 return;
 137         if (media_addr.broadcast)
 138                 return;
 139         if (!tipc_addr_domain_valid(dest))
 140                 return;
 141         if (!tipc_addr_node_valid(orig))
 142                 return;
 143         if (orig == tipc_own_addr) {
 144                 if (memcmp(&media_addr, &b_ptr->addr, sizeof(media_addr)))
 145                         disc_dupl_alert(b_ptr, tipc_own_addr, &media_addr);
 146                 return;
 147         }
 148         if (!tipc_in_scope(dest, tipc_own_addr))
 149                 return;
 150         if (!tipc_in_scope(b_ptr->link_req->domain, orig))
 151                 return;
 152
 153         /* Locate structure corresponding to requesting node */
 154         n_ptr = tipc_node_find(orig);
 155         if (!n_ptr) {
 156                 n_ptr = tipc_node_create(orig);
 157                 if (!n_ptr)
 158                         return;
 159         }
 160         tipc_node_lock(n_ptr);
 161
 162         /* Prepare to validate requesting node's signature and media address */
 163         link = n_ptr->links[b_ptr->identity];
 164         addr_mismatch = (link != NULL) &&
 165                 memcmp(&link->media_addr, &media_addr, sizeof(media_addr));
 166
 167         /*
 168          * Ensure discovery message's signature is correct
 169          *
 170          * If signature is incorrect and there is no working link to the node,
 171          * accept the new signature but invalidate all existing links to the
 172          * node so they won't re-activate without a new discovery message.
 173          *
 174          * If signature is incorrect and the requested link to the node is
 175          * working, accept the new signature. (This is an instance of delayed
 176          * rediscovery, where a link endpoint was able to re-establish contact
 177          * with its peer endpoint on a node that rebooted before receiving a
 178          * discovery message from that node.)
 179          *
 180          * If signature is incorrect and there is a working link to the node
 181          * that is not the requested link, reject the request (must be from
 182          * a duplicate node).
 183          */
 184         if (signature != n_ptr->signature) {
 185                 if (n_ptr->working_links == 0) {
 186                         struct tipc_link *curr_link;
 187                         int i;
 188
 189                         for (i = 0; i < MAX_BEARERS; i++) {
 190                                 curr_link = n_ptr->links[i];
 191                                 if (curr_link) {
 192                                         memset(&curr_link->media_addr, 0,
 193                                                sizeof(media_addr));
 194                                         tipc_link_reset(curr_link);
 195                                 }
 196                         }
 197                         addr_mismatch = (link != NULL);
 198                 } else if (tipc_link_is_up(link) && !addr_mismatch) {
 199                         /* delayed rediscovery */
 200                 } else {
 201                         disc_dupl_alert(b_ptr, orig, &media_addr);
 202                         tipc_node_unlock(n_ptr);
 203                         return;
 204                 }
 205                 n_ptr->signature = signature;
 206         }
 207
 208         /*
 209          * Ensure requesting node's media address is correct
 210          *
 211          * If media address doesn't match and the link is working, reject the
 212          * request (must be from a duplicate node).
 213          *
 214          * If media address doesn't match and the link is not working, accept
 215          * the new media address and reset the link to ensure it starts up
 216          * cleanly.
 217          */
 218         if (addr_mismatch) {
 219                 if (tipc_link_is_up(link)) {
 220                         disc_dupl_alert(b_ptr, orig, &media_addr);
 221                         tipc_node_unlock(n_ptr);
 222                         return;
 223                 } else {
 224                         memcpy(&link->media_addr, &media_addr,
 225                                sizeof(media_addr));
 226                         tipc_link_reset(link);
 227                 }
 228         }
 229
 230         /* Create a link endpoint for this bearer, if necessary */
 231         if (!link) {
 232                 link = tipc_link_create(n_ptr, b_ptr, &media_addr);
 233                 if (!link) {
 234                         tipc_node_unlock(n_ptr);
 235                         return;
 236                 }
 237         }
 238
 239         /* Accept discovery message & send response, if necessary */
 240         link_fully_up = link_working_working(link);
 241
 242         if ((type == DSC_REQ_MSG) && !link_fully_up && !b_ptr->blocked) {
 243                 rbuf = tipc_disc_init_msg(DSC_RESP_MSG, orig, b_ptr);
 244                 if (rbuf) {
 245                         tipc_bearer_send(b_ptr, rbuf, &media_addr);
 246                         kfree_skb(rbuf);
 247                 }
 248         }
 249
 250         tipc_node_unlock(n_ptr);
 251 }
 252
 253 /**
 254  * disc_update - update frequency of periodic link setup requests
 255  * @req: ptr to link request structure
 256  *
 257  * Reinitiates discovery process if discovery object has no associated nodes
 258  * and is either not currently searching or is searching at a slow rate
 259  */
 260 static void disc_update(struct tipc_link_req *req)
 261 {
 262         if (!req->num_nodes) {
 263                 if ((req->timer_intv == TIPC_LINK_REQ_INACTIVE) ||
 264                     (req->timer_intv > TIPC_LINK_REQ_FAST)) {
 265                         req->timer_intv = TIPC_LINK_REQ_INIT;
 266                         k_start_timer(&req->timer, req->timer_intv);
 267                 }
 268         }
 269 }
 270
 271 /**
 272  * tipc_disc_add_dest - increment set of discovered nodes
 273  * @req: ptr to link request structure
 274  */
 275 void tipc_disc_add_dest(struct tipc_link_req *req)
 276 {
 277         req->num_nodes++;
 278 }
 279
 280 /**
 281  * tipc_disc_remove_dest - decrement set of discovered nodes
 282  * @req: ptr to link request structure
 283  */
 284 void tipc_disc_remove_dest(struct tipc_link_req *req)
 285 {
 286         req->num_nodes--;
 287         disc_update(req);
 288 }
 289
 290 /**
 291  * disc_send_msg - send link setup request message
 292  * @req: ptr to link request structure
 293  */
 294 static void disc_send_msg(struct tipc_link_req *req)
 295 {
 296         if (!req->bearer->blocked)
 297                 tipc_bearer_send(req->bearer, req->buf, &req->dest);
 298 }
 299
 300 /**
 301  * disc_timeout - send a periodic link setup request
 302  * @req: ptr to link request structure
 303  *
 304  * Called whenever a link setup request timer associated with a bearer expires.
 305  */
 306 static void disc_timeout(struct tipc_link_req *req)
 307 {
 308         int max_delay;
 309
 310         spin_lock_bh(&req->bearer->lock);
 311
 312         /* Stop searching if only desired node has been found */
 313         if (tipc_node(req->domain) && req->num_nodes) {
 314                 req->timer_intv = TIPC_LINK_REQ_INACTIVE;
 315                 goto exit;
 316         }
 317
 318         /*
 319          * Send discovery message, then update discovery timer
 320          *
 321          * Keep doubling time between requests until limit is reached;
 322          * hold at fast polling rate if don't have any associated nodes,
 323          * otherwise hold at slow polling rate
 324          */
 325         disc_send_msg(req);
 326
 327         req->timer_intv *= 2;
 328         if (req->num_nodes)
 329                 max_delay = TIPC_LINK_REQ_SLOW;
 330         else
 331                 max_delay = TIPC_LINK_REQ_FAST;
 332         if (req->timer_intv > max_delay)
 333                 req->timer_intv = max_delay;
 334
 335         k_start_timer(&req->timer, req->timer_intv);
 336 exit:
 337         spin_unlock_bh(&req->bearer->lock);
 338 }
 339
 340 /**
 341  * tipc_disc_create - create object to send periodic link setup requests
 342  * @b_ptr: ptr to bearer issuing requests
 343  * @dest: destination address for request messages
 344  * @dest_domain: network domain to which links can be established
 345  *
 346  * Returns 0 if successful, otherwise -errno.
 347  */
 348 int tipc_disc_create(struct tipc_bearer *b_ptr, struct tipc_media_addr *dest,
 349                      u32 dest_domain)
 350 {
 351         struct tipc_link_req *req;
 352
 353         req = kmalloc(sizeof(*req), GFP_ATOMIC);
 354         if (!req)
 355                 return -ENOMEM;
 356
 357         req->buf = tipc_disc_init_msg(DSC_REQ_MSG, dest_domain, b_ptr);
 358         if (!req->buf) {
 359                 kfree(req);
 360                 return -ENOMSG;
 361         }
 362
 363         memcpy(&req->dest, dest, sizeof(*dest));
 364         req->bearer = b_ptr;
 365         req->domain = dest_domain;
 366         req->num_nodes = 0;
 367         req->timer_intv = TIPC_LINK_REQ_INIT;
 368         k_init_timer(&req->timer, (Handler)disc_timeout, (unsigned long)req);
 369         k_start_timer(&req->timer, req->timer_intv);
 370         b_ptr->link_req = req;
 371         disc_send_msg(req);
 372         return 0;
 373 }
 374
 375 /**
 376  * tipc_disc_delete - destroy object sending periodic link setup requests
 377  * @req: ptr to link request structure
 378  */
 379 void tipc_disc_delete(struct tipc_link_req *req)
 380 {
 381         k_cancel_timer(&req->timer);
 382         k_term_timer(&req->timer);
 383         kfree_skb(req->buf);
 384         kfree(req);
 385 }