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  * @lock: spinlock for controlling access to requests
  54  * @buf: request message to be (repeatedly) sent
  55  * @timer: timer governing period between requests
  56  * @timer_intv: current interval between requests (in ms)
  57  */
  58 struct tipc_link_req {
  59         struct tipc_bearer *bearer;
  60         struct tipc_media_addr dest;
  61         u32 domain;
  62         int num_nodes;
  63         spinlock_t lock;
  64         struct sk_buff *buf;
  65         struct timer_list timer;
  66         unsigned int timer_intv;
  67 };
  68
  69 /**
  70  * tipc_disc_init_msg - initialize a link setup message
  71  * @type: message type (request or response)
  72  * @dest_domain: network domain of node(s) which should respond to message
  73  * @b_ptr: ptr to bearer issuing message
  74  */
  75 static struct sk_buff *tipc_disc_init_msg(u32 type, u32 dest_domain,
  76                                           struct tipc_bearer *b_ptr)
  77 {
  78         struct sk_buff *buf = tipc_buf_acquire(INT_H_SIZE);
  79         struct tipc_msg *msg;
  80
  81         if (buf) {
  82                 msg = buf_msg(buf);
  83                 tipc_msg_init(msg, LINK_CONFIG, type, INT_H_SIZE, dest_domain);
  84                 msg_set_non_seq(msg, 1);
  85                 msg_set_node_sig(msg, tipc_random);
  86                 msg_set_dest_domain(msg, dest_domain);
  87                 msg_set_bc_netid(msg, tipc_net_id);
  88                 b_ptr->media->addr2msg(&b_ptr->addr, msg_media_addr(msg));
  89         }
  90         return buf;
  91 }
  92
  93 /**
  94  * disc_dupl_alert - issue node address duplication alert
  95  * @b_ptr: pointer to bearer detecting duplication
  96  * @node_addr: duplicated node address
  97  * @media_addr: media address advertised by duplicated node
  98  */
  99 static void disc_dupl_alert(struct tipc_bearer *b_ptr, u32 node_addr,
 100                             struct tipc_media_addr *media_addr)
 101 {
 102         char node_addr_str[16];
 103         char media_addr_str[64];
 104
 105         tipc_addr_string_fill(node_addr_str, node_addr);
 106         tipc_media_addr_printf(media_addr_str, sizeof(media_addr_str),
 107                                media_addr);
 108         pr_warn("Duplicate %s using %s seen on <%s>\n", node_addr_str,
 109                 media_addr_str, b_ptr->name);
 110 }
 111
 112 /**
 113  * tipc_disc_recv_msg - handle incoming link setup message (request or response)
 114  * @buf: buffer containing message
 115  * @b_ptr: bearer that message arrived on
 116  */
 117 void tipc_disc_recv_msg(struct sk_buff *buf, struct tipc_bearer *b_ptr)
 118 {
 119         struct tipc_node *n_ptr;
 120         struct tipc_link *link;
 121         struct tipc_media_addr media_addr;
 122         struct sk_buff *rbuf;
 123         struct tipc_msg *msg = buf_msg(buf);
 124         u32 dest = msg_dest_domain(msg);
 125         u32 orig = msg_prevnode(msg);
 126         u32 net_id = msg_bc_netid(msg);
 127         u32 type = msg_type(msg);
 128         u32 signature = msg_node_sig(msg);
 129         int addr_mismatch;
 130         int link_fully_up;
 131
 132         media_addr.broadcast = 1;
 133         b_ptr->media->msg2addr(b_ptr, &media_addr, msg_media_addr(msg));
 134         kfree_skb(buf);
 135
 136         /* Ensure message from node is valid and communication is permitted */
 137         if (net_id != tipc_net_id)
 138                 return;
 139         if (media_addr.broadcast)
 140                 return;
 141         if (!tipc_addr_domain_valid(dest))
 142                 return;
 143         if (!tipc_addr_node_valid(orig))
 144                 return;
 145         if (orig == tipc_own_addr) {
 146                 if (memcmp(&media_addr, &b_ptr->addr, sizeof(media_addr)))
 147                         disc_dupl_alert(b_ptr, tipc_own_addr, &media_addr);
 148                 return;
 149         }
 150         if (!tipc_in_scope(dest, tipc_own_addr))
 151                 return;
 152         if (!tipc_in_scope(b_ptr->link_req->domain, orig))
 153                 return;
 154
 155         /* Locate structure corresponding to requesting node */
 156         n_ptr = tipc_node_find(orig);
 157         if (!n_ptr) {
 158                 n_ptr = tipc_node_create(orig);
 159                 if (!n_ptr)
 160                         return;
 161         }
 162         tipc_node_lock(n_ptr);
 163
 164         /* Prepare to validate requesting node's signature and media address */
 165         link = n_ptr->links[b_ptr->identity];
 166         addr_mismatch = (link != NULL) &&
 167                 memcmp(&link->media_addr, &media_addr, sizeof(media_addr));
 168
 169         /*
 170          * Ensure discovery message's signature is correct
 171          *
 172          * If signature is incorrect and there is no working link to the node,
 173          * accept the new signature but invalidate all existing links to the
 174          * node so they won't re-activate without a new discovery message.
 175          *
 176          * If signature is incorrect and the requested link to the node is
 177          * working, accept the new signature. (This is an instance of delayed
 178          * rediscovery, where a link endpoint was able to re-establish contact
 179          * with its peer endpoint on a node that rebooted before receiving a
 180          * discovery message from that node.)
 181          *
 182          * If signature is incorrect and there is a working link to the node
 183          * that is not the requested link, reject the request (must be from
 184          * a duplicate node).
 185          */
 186         if (signature != n_ptr->signature) {
 187                 if (n_ptr->working_links == 0) {
 188                         struct tipc_link *curr_link;
 189                         int i;
 190
 191                         for (i = 0; i < MAX_BEARERS; i++) {
 192                                 curr_link = n_ptr->links[i];
 193                                 if (curr_link) {
 194                                         memset(&curr_link->media_addr, 0,
 195                                                sizeof(media_addr));
 196                                         tipc_link_reset(curr_link);
 197                                 }
 198                         }
 199                         addr_mismatch = (link != NULL);
 200                 } else if (tipc_link_is_up(link) && !addr_mismatch) {
 201                         /* delayed rediscovery */
 202                 } else {
 203                         disc_dupl_alert(b_ptr, orig, &media_addr);
 204                         tipc_node_unlock(n_ptr);
 205                         return;
 206                 }
 207                 n_ptr->signature = signature;
 208         }
 209
 210         /*
 211          * Ensure requesting node's media address is correct
 212          *
 213          * If media address doesn't match and the link is working, reject the
 214          * request (must be from a duplicate node).
 215          *
 216          * If media address doesn't match and the link is not working, accept
 217          * the new media address and reset the link to ensure it starts up
 218          * cleanly.
 219          */
 220         if (addr_mismatch) {
 221                 if (tipc_link_is_up(link)) {
 222                         disc_dupl_alert(b_ptr, orig, &media_addr);
 223                         tipc_node_unlock(n_ptr);
 224                         return;
 225                 } else {
 226                         memcpy(&link->media_addr, &media_addr,
 227                                sizeof(media_addr));
 228                         tipc_link_reset(link);
 229                 }
 230         }
 231
 232         /* Create a link endpoint for this bearer, if necessary */
 233         if (!link) {
 234                 link = tipc_link_create(n_ptr, b_ptr, &media_addr);
 235                 if (!link) {
 236                         tipc_node_unlock(n_ptr);
 237                         return;
 238                 }
 239         }
 240
 241         /* Accept discovery message & send response, if necessary */
 242         link_fully_up = link_working_working(link);
 243
 244         if ((type == DSC_REQ_MSG) && !link_fully_up) {
 245                 rbuf = tipc_disc_init_msg(DSC_RESP_MSG, orig, b_ptr);
 246                 if (rbuf) {
 247                         tipc_bearer_send(b_ptr, rbuf, &media_addr);
 248                         kfree_skb(rbuf);
 249                 }
 250         }
 251
 252         tipc_node_unlock(n_ptr);
 253 }
 254
 255 /**
 256  * disc_update - update frequency of periodic link setup requests
 257  * @req: ptr to link request structure
 258  *
 259  * Reinitiates discovery process if discovery object has no associated nodes
 260  * and is either not currently searching or is searching at a slow rate
 261  */
 262 static void disc_update(struct tipc_link_req *req)
 263 {
 264         if (!req->num_nodes) {
 265                 if ((req->timer_intv == TIPC_LINK_REQ_INACTIVE) ||
 266                     (req->timer_intv > TIPC_LINK_REQ_FAST)) {
 267                         req->timer_intv = TIPC_LINK_REQ_INIT;
 268                         k_start_timer(&req->timer, req->timer_intv);
 269                 }
 270         }
 271 }
 272
 273 /**
 274  * tipc_disc_add_dest - increment set of discovered nodes
 275  * @req: ptr to link request structure
 276  */
 277 void tipc_disc_add_dest(struct tipc_link_req *req)
 278 {
 279         spin_lock_bh(&req->lock);
 280         req->num_nodes++;
 281         spin_unlock_bh(&req->lock);
 282 }
 283
 284 /**
 285  * tipc_disc_remove_dest - decrement set of discovered nodes
 286  * @req: ptr to link request structure
 287  */
 288 void tipc_disc_remove_dest(struct tipc_link_req *req)
 289 {
 290         spin_lock_bh(&req->lock);
 291         req->num_nodes--;
 292         disc_update(req);
 293         spin_unlock_bh(&req->lock);
 294 }
 295
 296 /**
 297  * disc_timeout - send a periodic link setup request
 298  * @req: ptr to link request structure
 299  *
 300  * Called whenever a link setup request timer associated with a bearer expires.
 301  */
 302 static void disc_timeout(struct tipc_link_req *req)
 303 {
 304         int max_delay;
 305
 306         spin_lock_bh(&req->lock);
 307
 308         /* Stop searching if only desired node has been found */
 309         if (tipc_node(req->domain) && req->num_nodes) {
 310                 req->timer_intv = TIPC_LINK_REQ_INACTIVE;
 311                 goto exit;
 312         }
 313
 314         /*
 315          * Send discovery message, then update discovery timer
 316          *
 317          * Keep doubling time between requests until limit is reached;
 318          * hold at fast polling rate if don't have any associated nodes,
 319          * otherwise hold at slow polling rate
 320          */
 321         tipc_bearer_send(req->bearer, req->buf, &req->dest);
 322
 323
 324         req->timer_intv *= 2;
 325         if (req->num_nodes)
 326                 max_delay = TIPC_LINK_REQ_SLOW;
 327         else
 328                 max_delay = TIPC_LINK_REQ_FAST;
 329         if (req->timer_intv > max_delay)
 330                 req->timer_intv = max_delay;
 331
 332         k_start_timer(&req->timer, req->timer_intv);
 333 exit:
 334         spin_unlock_bh(&req->lock);
 335 }
 336
 337 /**
 338  * tipc_disc_create - create object to send periodic link setup requests
 339  * @b_ptr: ptr to bearer issuing requests
 340  * @dest: destination address for request messages
 341  * @dest_domain: network domain to which links can be established
 342  *
 343  * Returns 0 if successful, otherwise -errno.
 344  */
 345 int tipc_disc_create(struct tipc_bearer *b_ptr, struct tipc_media_addr *dest,
 346                      u32 dest_domain)
 347 {
 348         struct tipc_link_req *req;
 349
 350         req = kmalloc(sizeof(*req), GFP_ATOMIC);
 351         if (!req)
 352                 return -ENOMEM;
 353
 354         req->buf = tipc_disc_init_msg(DSC_REQ_MSG, dest_domain, b_ptr);
 355         if (!req->buf) {
 356                 kfree(req);
 357                 return -ENOMSG;
 358         }
 359
 360         memcpy(&req->dest, dest, sizeof(*dest));
 361         req->bearer = b_ptr;
 362         req->domain = dest_domain;
 363         req->num_nodes = 0;
 364         req->timer_intv = TIPC_LINK_REQ_INIT;
 365         spin_lock_init(&req->lock);
 366         k_init_timer(&req->timer, (Handler)disc_timeout, (unsigned long)req);
 367         k_start_timer(&req->timer, req->timer_intv);
 368         b_ptr->link_req = req;
 369         tipc_bearer_send(req->bearer, req->buf, &req->dest);
 370         return 0;
 371 }
 372
 373 /**
 374  * tipc_disc_delete - destroy object sending periodic link setup requests
 375  * @req: ptr to link request structure
 376  */
 377 void tipc_disc_delete(struct tipc_link_req *req)
 378 {
 379         k_cancel_timer(&req->timer);
 380         k_term_timer(&req->timer);
 381         kfree_skb(req->buf);
 382         kfree(req);
 383 }