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
  74 static struct sk_buff *tipc_disc_init_msg(u32 type,
  75                                           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
 100 static void disc_dupl_alert(struct tipc_bearer *b_ptr, u32 node_addr,
 101                             struct tipc_media_addr *media_addr)
 102 {
 103         char node_addr_str[16];
 104         char media_addr_str[64];
 105         struct print_buf pb;
 106
 107         tipc_addr_string_fill(node_addr_str, node_addr);
 108         tipc_printbuf_init(&pb, media_addr_str, sizeof(media_addr_str));
 109         tipc_media_addr_printf(&pb, media_addr);
 110         tipc_printbuf_validate(&pb);
 111         warn("Duplicate %s using %s seen on <%s>\n",
 112              node_addr_str, media_addr_str, b_ptr->name);
 113 }
 114
 115 /**
 116  * tipc_disc_recv_msg - handle incoming link setup message (request or response)
 117  * @buf: buffer containing message
 118  * @b_ptr: bearer that message arrived on
 119  */
 120
 121 void tipc_disc_recv_msg(struct sk_buff *buf, struct tipc_bearer *b_ptr)
 122 {
 123         struct tipc_node *n_ptr;
 124         struct tipc_link *link;
 125         struct tipc_media_addr media_addr;
 126         struct sk_buff *rbuf;
 127         struct tipc_msg *msg = buf_msg(buf);
 128         u32 dest = msg_dest_domain(msg);
 129         u32 orig = msg_prevnode(msg);
 130         u32 net_id = msg_bc_netid(msg);
 131         u32 type = msg_type(msg);
 132         u32 signature = msg_node_sig(msg);
 133         int addr_mismatch;
 134         int link_fully_up;
 135
 136         media_addr.broadcast = 1;
 137         b_ptr->media->msg2addr(&media_addr, msg_media_addr(msg));
 138         kfree_skb(buf);
 139
 140         /* Ensure message from node is valid and communication is permitted */
 141         if (net_id != tipc_net_id)
 142                 return;
 143         if (media_addr.broadcast)
 144                 return;
 145         if (!tipc_addr_domain_valid(dest))
 146                 return;
 147         if (!tipc_addr_node_valid(orig))
 148                 return;
 149         if (orig == tipc_own_addr) {
 150                 if (memcmp(&media_addr, &b_ptr->addr, sizeof(media_addr)))
 151                         disc_dupl_alert(b_ptr, tipc_own_addr, &media_addr);
 152                 return;
 153         }
 154         if (!tipc_in_scope(dest, tipc_own_addr))
 155                 return;
 156         if (!tipc_in_scope(b_ptr->link_req->domain, orig))
 157                 return;
 158
 159         /* Locate structure corresponding to requesting node */
 160         n_ptr = tipc_node_find(orig);
 161         if (!n_ptr) {
 162                 n_ptr = tipc_node_create(orig);
 163                 if (!n_ptr)
 164                         return;
 165         }
 166         tipc_node_lock(n_ptr);
 167
 168         /* Prepare to validate requesting node's signature and media address */
 169         link = n_ptr->links[b_ptr->identity];
 170         addr_mismatch = (link != NULL) &&
 171                 memcmp(&link->media_addr, &media_addr, sizeof(media_addr));
 172
 173         /*
 174          * Ensure discovery message's signature is correct
 175          *
 176          * If signature is incorrect and there is no working link to the node,
 177          * accept the new signature but invalidate all existing links to the
 178          * node so they won't re-activate without a new discovery message.
 179          *
 180          * If signature is incorrect and the requested link to the node is
 181          * working, accept the new signature. (This is an instance of delayed
 182          * rediscovery, where a link endpoint was able to re-establish contact
 183          * with its peer endpoint on a node that rebooted before receiving a
 184          * discovery message from that node.)
 185          *
 186          * If signature is incorrect and there is a working link to the node
 187          * that is not the requested link, reject the request (must be from
 188          * a duplicate node).
 189          */
 190         if (signature != n_ptr->signature) {
 191                 if (n_ptr->working_links == 0) {
 192                         struct tipc_link *curr_link;
 193                         int i;
 194
 195                         for (i = 0; i < MAX_BEARERS; i++) {
 196                                 curr_link = n_ptr->links[i];
 197                                 if (curr_link) {
 198                                         memset(&curr_link->media_addr, 0,
 199                                                sizeof(media_addr));
 200                                         tipc_link_reset(curr_link);
 201                                 }
 202                         }
 203                         addr_mismatch = (link != NULL);
 204                 } else if (tipc_link_is_up(link) && !addr_mismatch) {
 205                         /* delayed rediscovery */
 206                 } else {
 207                         disc_dupl_alert(b_ptr, orig, &media_addr);
 208                         tipc_node_unlock(n_ptr);
 209                         return;
 210                 }
 211                 n_ptr->signature = signature;
 212         }
 213
 214         /*
 215          * Ensure requesting node's media address is correct
 216          *
 217          * If media address doesn't match and the link is working, reject the
 218          * request (must be from a duplicate node).
 219          *
 220          * If media address doesn't match and the link is not working, accept
 221          * the new media address and reset the link to ensure it starts up
 222          * cleanly.
 223          */
 224
 225         if (addr_mismatch) {
 226                 if (tipc_link_is_up(link)) {
 227                         disc_dupl_alert(b_ptr, orig, &media_addr);
 228                         tipc_node_unlock(n_ptr);
 229                         return;
 230                 } else {
 231                         memcpy(&link->media_addr, &media_addr,
 232                                sizeof(media_addr));
 233                         tipc_link_reset(link);
 234                 }
 235         }
 236
 237         /* Create a link endpoint for this bearer, if necessary */
 238         if (!link) {
 239                 link = tipc_link_create(n_ptr, b_ptr, &media_addr);
 240                 if (!link) {
 241                         tipc_node_unlock(n_ptr);
 242                         return;
 243                 }
 244         }
 245
 246         /* Accept discovery message & send response, if necessary */
 247         link_fully_up = link_working_working(link);
 248
 249         if ((type == DSC_REQ_MSG) && !link_fully_up && !b_ptr->blocked) {
 250                 rbuf = tipc_disc_init_msg(DSC_RESP_MSG, orig, b_ptr);
 251                 if (rbuf) {
 252                         b_ptr->media->send_msg(rbuf, b_ptr, &media_addr);
 253                         kfree_skb(rbuf);
 254                 }
 255         }
 256
 257         tipc_node_unlock(n_ptr);
 258 }
 259
 260 /**
 261  * disc_update - update frequency of periodic link setup requests
 262  * @req: ptr to link request structure
 263  *
 264  * Reinitiates discovery process if discovery object has no associated nodes
 265  * and is either not currently searching or is searching at a slow rate
 266  */
 267
 268 static void disc_update(struct tipc_link_req *req)
 269 {
 270         if (!req->num_nodes) {
 271                 if ((req->timer_intv == TIPC_LINK_REQ_INACTIVE) ||
 272                     (req->timer_intv > TIPC_LINK_REQ_FAST)) {
 273                         req->timer_intv = TIPC_LINK_REQ_INIT;
 274                         k_start_timer(&req->timer, req->timer_intv);
 275                 }
 276         }
 277 }
 278
 279 /**
 280  * tipc_disc_add_dest - increment set of discovered nodes
 281  * @req: ptr to link request structure
 282  */
 283
 284 void tipc_disc_add_dest(struct tipc_link_req *req)
 285 {
 286         req->num_nodes++;
 287 }
 288
 289 /**
 290  * tipc_disc_remove_dest - decrement set of discovered nodes
 291  * @req: ptr to link request structure
 292  */
 293
 294 void tipc_disc_remove_dest(struct tipc_link_req *req)
 295 {
 296         req->num_nodes--;
 297         disc_update(req);
 298 }
 299
 300 /**
 301  * disc_send_msg - send link setup request message
 302  * @req: ptr to link request structure
 303  */
 304
 305 static void disc_send_msg(struct tipc_link_req *req)
 306 {
 307         if (!req->bearer->blocked)
 308                 tipc_bearer_send(req->bearer, req->buf, &req->dest);
 309 }
 310
 311 /**
 312  * disc_timeout - send a periodic link setup request
 313  * @req: ptr to link request structure
 314  *
 315  * Called whenever a link setup request timer associated with a bearer expires.
 316  */
 317
 318 static void disc_timeout(struct tipc_link_req *req)
 319 {
 320         int max_delay;
 321
 322         spin_lock_bh(&req->bearer->lock);
 323
 324         /* Stop searching if only desired node has been found */
 325
 326         if (tipc_node(req->domain) && req->num_nodes) {
 327                 req->timer_intv = TIPC_LINK_REQ_INACTIVE;
 328                 goto exit;
 329         }
 330
 331         /*
 332          * Send discovery message, then update discovery timer
 333          *
 334          * Keep doubling time between requests until limit is reached;
 335          * hold at fast polling rate if don't have any associated nodes,
 336          * otherwise hold at slow polling rate
 337          */
 338
 339         disc_send_msg(req);
 340
 341         req->timer_intv *= 2;
 342         if (req->num_nodes)
 343                 max_delay = TIPC_LINK_REQ_SLOW;
 344         else
 345                 max_delay = TIPC_LINK_REQ_FAST;
 346         if (req->timer_intv > max_delay)
 347                 req->timer_intv = max_delay;
 348
 349         k_start_timer(&req->timer, req->timer_intv);
 350 exit:
 351         spin_unlock_bh(&req->bearer->lock);
 352 }
 353
 354 /**
 355  * tipc_disc_create - create object to send periodic link setup requests
 356  * @b_ptr: ptr to bearer issuing requests
 357  * @dest: destination address for request messages
 358  * @dest_domain: network domain to which links can be established
 359  *
 360  * Returns 0 if successful, otherwise -errno.
 361  */
 362
 363 int tipc_disc_create(struct tipc_bearer *b_ptr,
 364                      struct tipc_media_addr *dest, u32 dest_domain)
 365 {
 366         struct tipc_link_req *req;
 367
 368         req = kmalloc(sizeof(*req), GFP_ATOMIC);
 369         if (!req)
 370                 return -ENOMEM;
 371
 372         req->buf = tipc_disc_init_msg(DSC_REQ_MSG, dest_domain, b_ptr);
 373         if (!req->buf) {
 374                 kfree(req);
 375                 return -ENOMSG;
 376         }
 377
 378         memcpy(&req->dest, dest, sizeof(*dest));
 379         req->bearer = b_ptr;
 380         req->domain = dest_domain;
 381         req->num_nodes = 0;
 382         req->timer_intv = TIPC_LINK_REQ_INIT;
 383         k_init_timer(&req->timer, (Handler)disc_timeout, (unsigned long)req);
 384         k_start_timer(&req->timer, req->timer_intv);
 385         b_ptr->link_req = req;
 386         disc_send_msg(req);
 387         return 0;
 388 }
 389
 390 /**
 391  * tipc_disc_delete - destroy object sending periodic link setup requests
 392  * @req: ptr to link request structure
 393  */
 394
 395 void tipc_disc_delete(struct tipc_link_req *req)
 396 {
 397         k_cancel_timer(&req->timer);
 398         k_term_timer(&req->timer);
 399         kfree_skb(req->buf);
 400         kfree(req);
 401 }
 402