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 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 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_dest_domain(msg, dest_domain);
  86                 msg_set_bc_netid(msg, tipc_net_id);
  87                 msg_set_media_addr(msg, &b_ptr->addr);
  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
  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         struct print_buf pb;
 105
 106         tipc_addr_string_fill(node_addr_str, node_addr);
 107         tipc_printbuf_init(&pb, media_addr_str, sizeof(media_addr_str));
 108         tipc_media_addr_printf(&pb, media_addr);
 109         tipc_printbuf_validate(&pb);
 110         warn("Duplicate %s using %s seen on <%s>\n",
 111              node_addr_str, media_addr_str, b_ptr->name);
 112 }
 113
 114 /**
 115  * tipc_disc_recv_msg - handle incoming link setup message (request or response)
 116  * @buf: buffer containing message
 117  * @b_ptr: bearer that message arrived on
 118  */
 119
 120 void tipc_disc_recv_msg(struct sk_buff *buf, struct tipc_bearer *b_ptr)
 121 {
 122         struct tipc_node *n_ptr;
 123         struct link *link;
 124         struct tipc_media_addr media_addr, *addr;
 125         struct sk_buff *rbuf;
 126         struct tipc_msg *msg = buf_msg(buf);
 127         u32 dest = msg_dest_domain(msg);
 128         u32 orig = msg_prevnode(msg);
 129         u32 net_id = msg_bc_netid(msg);
 130         u32 type = msg_type(msg);
 131         int link_fully_up;
 132
 133         msg_get_media_addr(msg, &media_addr);
 134         buf_discard(buf);
 135
 136         /* Validate discovery message from requesting node */
 137         if (net_id != tipc_net_id)
 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         /* Don't talk to neighbor during cleanup after last session */
 163         if (n_ptr->cleanup_required) {
 164                 tipc_node_unlock(n_ptr);
 165                 return;
 166         }
 167
 168         link = n_ptr->links[b_ptr->identity];
 169
 170         /* Create a link endpoint for this bearer, if necessary */
 171         if (!link) {
 172                 link = tipc_link_create(n_ptr, b_ptr, &media_addr);
 173                 if (!link) {
 174                         tipc_node_unlock(n_ptr);
 175                         return;
 176                 }
 177         }
 178
 179         /*
 180          * Ensure requesting node's media address is correct
 181          *
 182          * If media address doesn't match and the link is working, reject the
 183          * request (must be from a duplicate node).
 184          *
 185          * If media address doesn't match and the link is not working, accept
 186          * the new media address and reset the link to ensure it starts up
 187          * cleanly.
 188          */
 189         addr = &link->media_addr;
 190         if (memcmp(addr, &media_addr, sizeof(*addr))) {
 191                 if (tipc_link_is_up(link) || (!link->started)) {
 192                         disc_dupl_alert(b_ptr, orig, &media_addr);
 193                         tipc_node_unlock(n_ptr);
 194                         return;
 195                 }
 196                 warn("Resetting link <%s>, peer interface address changed\n",
 197                      link->name);
 198                 memcpy(addr, &media_addr, sizeof(*addr));
 199                 tipc_link_reset(link);
 200         }
 201
 202         /* Accept discovery message & send response, if necessary */
 203         link_fully_up = link_working_working(link);
 204
 205         if ((type == DSC_REQ_MSG) && !link_fully_up && !b_ptr->blocked) {
 206                 rbuf = tipc_disc_init_msg(DSC_RESP_MSG, orig, b_ptr);
 207                 if (rbuf) {
 208                         b_ptr->media->send_msg(rbuf, b_ptr, &media_addr);
 209                         buf_discard(rbuf);
 210                 }
 211         }
 212
 213         tipc_node_unlock(n_ptr);
 214 }
 215
 216 /**
 217  * disc_update - update frequency of periodic link setup requests
 218  * @req: ptr to link request structure
 219  *
 220  * Reinitiates discovery process if discovery object has no associated nodes
 221  * and is either not currently searching or is searching at a slow rate
 222  */
 223
 224 static void disc_update(struct link_req *req)
 225 {
 226         if (!req->num_nodes) {
 227                 if ((req->timer_intv == TIPC_LINK_REQ_INACTIVE) ||
 228                     (req->timer_intv > TIPC_LINK_REQ_FAST)) {
 229                         req->timer_intv = TIPC_LINK_REQ_INIT;
 230                         k_start_timer(&req->timer, req->timer_intv);
 231                 }
 232         }
 233 }
 234
 235 /**
 236  * tipc_disc_add_dest - increment set of discovered nodes
 237  * @req: ptr to link request structure
 238  */
 239
 240 void tipc_disc_add_dest(struct link_req *req)
 241 {
 242         req->num_nodes++;
 243 }
 244
 245 /**
 246  * tipc_disc_remove_dest - decrement set of discovered nodes
 247  * @req: ptr to link request structure
 248  */
 249
 250 void tipc_disc_remove_dest(struct link_req *req)
 251 {
 252         req->num_nodes--;
 253         disc_update(req);
 254 }
 255
 256 /**
 257  * disc_send_msg - send link setup request message
 258  * @req: ptr to link request structure
 259  */
 260
 261 static void disc_send_msg(struct link_req *req)
 262 {
 263         if (!req->bearer->blocked)
 264                 tipc_bearer_send(req->bearer, req->buf, &req->dest);
 265 }
 266
 267 /**
 268  * disc_timeout - send a periodic link setup request
 269  * @req: ptr to link request structure
 270  *
 271  * Called whenever a link setup request timer associated with a bearer expires.
 272  */
 273
 274 static void disc_timeout(struct link_req *req)
 275 {
 276         int max_delay;
 277
 278         spin_lock_bh(&req->bearer->lock);
 279
 280         /* Stop searching if only desired node has been found */
 281
 282         if (tipc_node(req->domain) && req->num_nodes) {
 283                 req->timer_intv = TIPC_LINK_REQ_INACTIVE;
 284                 goto exit;
 285         }
 286
 287         /*
 288          * Send discovery message, then update discovery timer
 289          *
 290          * Keep doubling time between requests until limit is reached;
 291          * hold at fast polling rate if don't have any associated nodes,
 292          * otherwise hold at slow polling rate
 293          */
 294
 295         disc_send_msg(req);
 296
 297         req->timer_intv *= 2;
 298         if (req->num_nodes)
 299                 max_delay = TIPC_LINK_REQ_SLOW;
 300         else
 301                 max_delay = TIPC_LINK_REQ_FAST;
 302         if (req->timer_intv > max_delay)
 303                 req->timer_intv = max_delay;
 304
 305         k_start_timer(&req->timer, req->timer_intv);
 306 exit:
 307         spin_unlock_bh(&req->bearer->lock);
 308 }
 309
 310 /**
 311  * tipc_disc_create - create object to send periodic link setup requests
 312  * @b_ptr: ptr to bearer issuing requests
 313  * @dest: destination address for request messages
 314  * @dest_domain: network domain to which links can be established
 315  *
 316  * Returns 0 if successful, otherwise -errno.
 317  */
 318
 319 int tipc_disc_create(struct tipc_bearer *b_ptr,
 320                      struct tipc_media_addr *dest, u32 dest_domain)
 321 {
 322         struct link_req *req;
 323
 324         req = kmalloc(sizeof(*req), GFP_ATOMIC);
 325         if (!req)
 326                 return -ENOMEM;
 327
 328         req->buf = tipc_disc_init_msg(DSC_REQ_MSG, dest_domain, b_ptr);
 329         if (!req->buf) {
 330                 kfree(req);
 331                 return -ENOMSG;
 332         }
 333
 334         memcpy(&req->dest, dest, sizeof(*dest));
 335         req->bearer = b_ptr;
 336         req->domain = dest_domain;
 337         req->num_nodes = 0;
 338         req->timer_intv = TIPC_LINK_REQ_INIT;
 339         k_init_timer(&req->timer, (Handler)disc_timeout, (unsigned long)req);
 340         k_start_timer(&req->timer, req->timer_intv);
 341         b_ptr->link_req = req;
 342         disc_send_msg(req);
 343         return 0;
 344 }
 345
 346 /**
 347  * tipc_disc_delete - destroy object sending periodic link setup requests
 348  * @req: ptr to link request structure
 349  */
 350
 351 void tipc_disc_delete(struct link_req *req)
 352 {
 353         k_cancel_timer(&req->timer);
 354         k_term_timer(&req->timer);
 355         buf_discard(req->buf);
 356         kfree(req);
 357 }
 358