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   1 /*
   2  * llc_conn.c - Driver routines for connection component.
   3  *
   4  * Copyright (c) 1997 by Procom Technology, Inc.
   5  *               2001-2003 by Arnaldo Carvalho de Melo <acme@conectiva.com.br>
   6  *
   7  * This program can be redistributed or modified under the terms of the
   8  * GNU General Public License as published by the Free Software Foundation.
   9  * This program is distributed without any warranty or implied warranty
  10  * of merchantability or fitness for a particular purpose.
  11  *
  12  * See the GNU General Public License for more details.
  13  */
  14
  15 #include <linux/init.h>
  16 #include <net/llc_sap.h>
  17 #include <net/llc_conn.h>
  18 #include <net/sock.h>
  19 #include <net/tcp_states.h>
  20 #include <net/llc_c_ev.h>
  21 #include <net/llc_c_ac.h>
  22 #include <net/llc_c_st.h>
  23 #include <net/llc_pdu.h>
  24
  25 #if 0
  26 #define dprintk(args...) printk(KERN_DEBUG args)
  27 #else
  28 #define dprintk(args...)
  29 #endif
  30
  31 static int llc_find_offset(int state, int ev_type);
  32 static void llc_conn_send_pdus(struct sock *sk);
  33 static int llc_conn_service(struct sock *sk, struct sk_buff *skb);
  34 static int llc_exec_conn_trans_actions(struct sock *sk,
  35                                        struct llc_conn_state_trans *trans,
  36                                        struct sk_buff *ev);
  37 static struct llc_conn_state_trans *llc_qualify_conn_ev(struct sock *sk,
  38                                                         struct sk_buff *skb);
  39
  40 /* Offset table on connection states transition diagram */
  41 static int llc_offset_table[NBR_CONN_STATES][NBR_CONN_EV];
  42
  43 int sysctl_llc2_ack_timeout = LLC2_ACK_TIME * HZ;
  44 int sysctl_llc2_p_timeout = LLC2_P_TIME * HZ;
  45 int sysctl_llc2_rej_timeout = LLC2_REJ_TIME * HZ;
  46 int sysctl_llc2_busy_timeout = LLC2_BUSY_TIME * HZ;
  47
  48 /**
  49  *      llc_conn_state_process - sends event to connection state machine
  50  *      @sk: connection
  51  *      @skb: occurred event
  52  *
  53  *      Sends an event to connection state machine. After processing event
  54  *      (executing it's actions and changing state), upper layer will be
  55  *      indicated or confirmed, if needed. Returns 0 for success, 1 for
  56  *      failure. The socket lock has to be held before calling this function.
  57  */
  58 int llc_conn_state_process(struct sock *sk, struct sk_buff *skb)
  59 {
  60         int rc;
  61         struct llc_sock *llc = llc_sk(skb->sk);
  62         struct llc_conn_state_ev *ev = llc_conn_ev(skb);
  63
  64         /*
  65          * We have to hold the skb, because llc_conn_service will kfree it in
  66          * the sending path and we need to look at the skb->cb, where we encode
  67          * llc_conn_state_ev.
  68          */
  69         skb_get(skb);
  70         ev->ind_prim = ev->cfm_prim = 0;
  71         /*
  72          * Send event to state machine
  73          */
  74         rc = llc_conn_service(skb->sk, skb);
  75         if (unlikely(rc != 0)) {
  76                 printk(KERN_ERR "%s: llc_conn_service failed\n", __func__);
  77                 goto out_kfree_skb;
  78         }
  79
  80         if (unlikely(!ev->ind_prim && !ev->cfm_prim)) {
  81                 /* indicate or confirm not required */
  82                 if (!skb->next)
  83                         goto out_kfree_skb;
  84                 goto out_skb_put;
  85         }
  86
  87         if (unlikely(ev->ind_prim && ev->cfm_prim)) /* Paranoia */
  88                 skb_get(skb);
  89
  90         switch (ev->ind_prim) {
  91         case LLC_DATA_PRIM:
  92                 llc_save_primitive(sk, skb, LLC_DATA_PRIM);
  93                 if (unlikely(sock_queue_rcv_skb(sk, skb))) {
  94                         /*
  95                          * shouldn't happen
  96                          */
  97                         printk(KERN_ERR "%s: sock_queue_rcv_skb failed!\n",
  98                                __func__);
  99                         kfree_skb(skb);
 100                 }
 101                 break;
 102         case LLC_CONN_PRIM:
 103                 /*
 104                  * Can't be sock_queue_rcv_skb, because we have to leave the
 105                  * skb->sk pointing to the newly created struct sock in
 106                  * llc_conn_handler. -acme
 107                  */
 108                 skb_queue_tail(&sk->sk_receive_queue, skb);
 109                 sk->sk_state_change(sk);
 110                 break;
 111         case LLC_DISC_PRIM:
 112                 sock_hold(sk);
 113                 if (sk->sk_type == SOCK_STREAM &&
 114                     sk->sk_state == TCP_ESTABLISHED) {
 115                         sk->sk_shutdown       = SHUTDOWN_MASK;
 116                         sk->sk_socket->state  = SS_UNCONNECTED;
 117                         sk->sk_state          = TCP_CLOSE;
 118                         if (!sock_flag(sk, SOCK_DEAD)) {
 119                                 sock_set_flag(sk, SOCK_DEAD);
 120                                 sk->sk_state_change(sk);
 121                         }
 122                 }
 123                 kfree_skb(skb);
 124                 sock_put(sk);
 125                 break;
 126         case LLC_RESET_PRIM:
 127                 /*
 128                  * FIXME:
 129                  * RESET is not being notified to upper layers for now
 130                  */
 131                 printk(KERN_INFO "%s: received a reset ind!\n", __func__);
 132                 kfree_skb(skb);
 133                 break;
 134         default:
 135                 if (ev->ind_prim) {
 136                         printk(KERN_INFO "%s: received unknown %d prim!\n",
 137                                 __func__, ev->ind_prim);
 138                         kfree_skb(skb);
 139                 }
 140                 /* No indication */
 141                 break;
 142         }
 143
 144         switch (ev->cfm_prim) {
 145         case LLC_DATA_PRIM:
 146                 if (!llc_data_accept_state(llc->state))
 147                         sk->sk_write_space(sk);
 148                 else
 149                         rc = llc->failed_data_req = 1;
 150                 break;
 151         case LLC_CONN_PRIM:
 152                 if (sk->sk_type == SOCK_STREAM &&
 153                     sk->sk_state == TCP_SYN_SENT) {
 154                         if (ev->status) {
 155                                 sk->sk_socket->state = SS_UNCONNECTED;
 156                                 sk->sk_state         = TCP_CLOSE;
 157                         } else {
 158                                 sk->sk_socket->state = SS_CONNECTED;
 159                                 sk->sk_state         = TCP_ESTABLISHED;
 160                         }
 161                         sk->sk_state_change(sk);
 162                 }
 163                 break;
 164         case LLC_DISC_PRIM:
 165                 sock_hold(sk);
 166                 if (sk->sk_type == SOCK_STREAM && sk->sk_state == TCP_CLOSING) {
 167                         sk->sk_socket->state = SS_UNCONNECTED;
 168                         sk->sk_state         = TCP_CLOSE;
 169                         sk->sk_state_change(sk);
 170                 }
 171                 sock_put(sk);
 172                 break;
 173         case LLC_RESET_PRIM:
 174                 /*
 175                  * FIXME:
 176                  * RESET is not being notified to upper layers for now
 177                  */
 178                 printk(KERN_INFO "%s: received a reset conf!\n", __func__);
 179                 break;
 180         default:
 181                 if (ev->cfm_prim) {
 182                         printk(KERN_INFO "%s: received unknown %d prim!\n",
 183                                         __func__, ev->cfm_prim);
 184                         break;
 185                 }
 186                 goto out_skb_put; /* No confirmation */
 187         }
 188 out_kfree_skb:
 189         kfree_skb(skb);
 190 out_skb_put:
 191         kfree_skb(skb);
 192         return rc;
 193 }
 194
 195 void llc_conn_send_pdu(struct sock *sk, struct sk_buff *skb)
 196 {
 197         /* queue PDU to send to MAC layer */
 198         skb_queue_tail(&sk->sk_write_queue, skb);
 199         llc_conn_send_pdus(sk);
 200 }
 201
 202 /**
 203  *      llc_conn_rtn_pdu - sends received data pdu to upper layer
 204  *      @sk: Active connection
 205  *      @skb: Received data frame
 206  *
 207  *      Sends received data pdu to upper layer (by using indicate function).
 208  *      Prepares service parameters (prim and prim_data). calling indication
 209  *      function will be done in llc_conn_state_process.
 210  */
 211 void llc_conn_rtn_pdu(struct sock *sk, struct sk_buff *skb)
 212 {
 213         struct llc_conn_state_ev *ev = llc_conn_ev(skb);
 214
 215         ev->ind_prim = LLC_DATA_PRIM;
 216 }
 217
 218 /**
 219  *      llc_conn_resend_i_pdu_as_cmd - resend all all unacknowledged I PDUs
 220  *      @sk: active connection
 221  *      @nr: NR
 222  *      @first_p_bit: p_bit value of first pdu
 223  *
 224  *      Resend all unacknowledged I PDUs, starting with the NR; send first as
 225  *      command PDU with P bit equal first_p_bit; if more than one send
 226  *      subsequent as command PDUs with P bit equal zero (0).
 227  */
 228 void llc_conn_resend_i_pdu_as_cmd(struct sock *sk, u8 nr, u8 first_p_bit)
 229 {
 230         struct sk_buff *skb;
 231         struct llc_pdu_sn *pdu;
 232         u16 nbr_unack_pdus;
 233         struct llc_sock *llc;
 234         u8 howmany_resend = 0;
 235
 236         llc_conn_remove_acked_pdus(sk, nr, &nbr_unack_pdus);
 237         if (!nbr_unack_pdus)
 238                 goto out;
 239         /*
 240          * Process unack PDUs only if unack queue is not empty; remove
 241          * appropriate PDUs, fix them up, and put them on mac_pdu_q.
 242          */
 243         llc = llc_sk(sk);
 244
 245         while ((skb = skb_dequeue(&llc->pdu_unack_q)) != NULL) {
 246                 pdu = llc_pdu_sn_hdr(skb);
 247                 llc_pdu_set_cmd_rsp(skb, LLC_PDU_CMD);
 248                 llc_pdu_set_pf_bit(skb, first_p_bit);
 249                 skb_queue_tail(&sk->sk_write_queue, skb);
 250                 first_p_bit = 0;
 251                 llc->vS = LLC_I_GET_NS(pdu);
 252                 howmany_resend++;
 253         }
 254         if (howmany_resend > 0)
 255                 llc->vS = (llc->vS + 1) % LLC_2_SEQ_NBR_MODULO;
 256         /* any PDUs to re-send are queued up; start sending to MAC */
 257         llc_conn_send_pdus(sk);
 258 out:;
 259 }
 260
 261 /**
 262  *      llc_conn_resend_i_pdu_as_rsp - Resend all unacknowledged I PDUs
 263  *      @sk: active connection.
 264  *      @nr: NR
 265  *      @first_f_bit: f_bit value of first pdu.
 266  *
 267  *      Resend all unacknowledged I PDUs, starting with the NR; send first as
 268  *      response PDU with F bit equal first_f_bit; if more than one send
 269  *      subsequent as response PDUs with F bit equal zero (0).
 270  */
 271 void llc_conn_resend_i_pdu_as_rsp(struct sock *sk, u8 nr, u8 first_f_bit)
 272 {
 273         struct sk_buff *skb;
 274         u16 nbr_unack_pdus;
 275         struct llc_sock *llc = llc_sk(sk);
 276         u8 howmany_resend = 0;
 277
 278         llc_conn_remove_acked_pdus(sk, nr, &nbr_unack_pdus);
 279         if (!nbr_unack_pdus)
 280                 goto out;
 281         /*
 282          * Process unack PDUs only if unack queue is not empty; remove
 283          * appropriate PDUs, fix them up, and put them on mac_pdu_q
 284          */
 285         while ((skb = skb_dequeue(&llc->pdu_unack_q)) != NULL) {
 286                 struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
 287
 288                 llc_pdu_set_cmd_rsp(skb, LLC_PDU_RSP);
 289                 llc_pdu_set_pf_bit(skb, first_f_bit);
 290                 skb_queue_tail(&sk->sk_write_queue, skb);
 291                 first_f_bit = 0;
 292                 llc->vS = LLC_I_GET_NS(pdu);
 293                 howmany_resend++;
 294         }
 295         if (howmany_resend > 0)
 296                 llc->vS = (llc->vS + 1) % LLC_2_SEQ_NBR_MODULO;
 297         /* any PDUs to re-send are queued up; start sending to MAC */
 298         llc_conn_send_pdus(sk);
 299 out:;
 300 }
 301
 302 /**
 303  *      llc_conn_remove_acked_pdus - Removes acknowledged pdus from tx queue
 304  *      @sk: active connection
 305  *      nr: NR
 306  *      how_many_unacked: size of pdu_unack_q after removing acked pdus
 307  *
 308  *      Removes acknowledged pdus from transmit queue (pdu_unack_q). Returns
 309  *      the number of pdus that removed from queue.
 310  */
 311 int llc_conn_remove_acked_pdus(struct sock *sk, u8 nr, u16 *how_many_unacked)
 312 {
 313         int pdu_pos, i;
 314         struct sk_buff *skb;
 315         struct llc_pdu_sn *pdu;
 316         int nbr_acked = 0;
 317         struct llc_sock *llc = llc_sk(sk);
 318         int q_len = skb_queue_len(&llc->pdu_unack_q);
 319
 320         if (!q_len)
 321                 goto out;
 322         skb = skb_peek(&llc->pdu_unack_q);
 323         pdu = llc_pdu_sn_hdr(skb);
 324
 325         /* finding position of last acked pdu in queue */
 326         pdu_pos = ((int)LLC_2_SEQ_NBR_MODULO + (int)nr -
 327                         (int)LLC_I_GET_NS(pdu)) % LLC_2_SEQ_NBR_MODULO;
 328
 329         for (i = 0; i < pdu_pos && i < q_len; i++) {
 330                 skb = skb_dequeue(&llc->pdu_unack_q);
 331                 kfree_skb(skb);
 332                 nbr_acked++;
 333         }
 334 out:
 335         *how_many_unacked = skb_queue_len(&llc->pdu_unack_q);
 336         return nbr_acked;
 337 }
 338
 339 /**
 340  *      llc_conn_send_pdus - Sends queued PDUs
 341  *      @sk: active connection
 342  *
 343  *      Sends queued pdus to MAC layer for transmission.
 344  */
 345 static void llc_conn_send_pdus(struct sock *sk)
 346 {
 347         struct sk_buff *skb;
 348
 349         while ((skb = skb_dequeue(&sk->sk_write_queue)) != NULL) {
 350                 struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
 351
 352                 if (LLC_PDU_TYPE_IS_I(pdu) &&
 353                     !(skb->dev->flags & IFF_LOOPBACK)) {
 354                         struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
 355
 356                         skb_queue_tail(&llc_sk(sk)->pdu_unack_q, skb);
 357                         if (!skb2)
 358                                 break;
 359                         skb = skb2;
 360                 }
 361                 dev_queue_xmit(skb);
 362         }
 363 }
 364
 365 /**
 366  *      llc_conn_service - finds transition and changes state of connection
 367  *      @sk: connection
 368  *      @skb: happened event
 369  *
 370  *      This function finds transition that matches with happened event, then
 371  *      executes related actions and finally changes state of connection.
 372  *      Returns 0 for success, 1 for failure.
 373  */
 374 static int llc_conn_service(struct sock *sk, struct sk_buff *skb)
 375 {
 376         int rc = 1;
 377         struct llc_sock *llc = llc_sk(sk);
 378         struct llc_conn_state_trans *trans;
 379
 380         if (llc->state > NBR_CONN_STATES)
 381                 goto out;
 382         rc = 0;
 383         trans = llc_qualify_conn_ev(sk, skb);
 384         if (trans) {
 385                 rc = llc_exec_conn_trans_actions(sk, trans, skb);
 386                 if (!rc && trans->next_state != NO_STATE_CHANGE) {
 387                         llc->state = trans->next_state;
 388                         if (!llc_data_accept_state(llc->state))
 389                                 sk->sk_state_change(sk);
 390                 }
 391         }
 392 out:
 393         return rc;
 394 }
 395
 396 /**
 397  *      llc_qualify_conn_ev - finds transition for event
 398  *      @sk: connection
 399  *      @skb: happened event
 400  *
 401  *      This function finds transition that matches with happened event.
 402  *      Returns pointer to found transition on success, %NULL otherwise.
 403  */
 404 static struct llc_conn_state_trans *llc_qualify_conn_ev(struct sock *sk,
 405                                                         struct sk_buff *skb)
 406 {
 407         struct llc_conn_state_trans **next_trans;
 408         llc_conn_ev_qfyr_t *next_qualifier;
 409         struct llc_conn_state_ev *ev = llc_conn_ev(skb);
 410         struct llc_sock *llc = llc_sk(sk);
 411         struct llc_conn_state *curr_state =
 412                                         &llc_conn_state_table[llc->state - 1];
 413
 414         /* search thru events for this state until
 415          * list exhausted or until no more
 416          */
 417         for (next_trans = curr_state->transitions +
 418                 llc_find_offset(llc->state - 1, ev->type);
 419              (*next_trans)->ev; next_trans++) {
 420                 if (!((*next_trans)->ev)(sk, skb)) {
 421                         /* got POSSIBLE event match; the event may require
 422                          * qualification based on the values of a number of
 423                          * state flags; if all qualifications are met (i.e.,
 424                          * if all qualifying functions return success, or 0,
 425                          * then this is THE event we're looking for
 426                          */
 427                         for (next_qualifier = (*next_trans)->ev_qualifiers;
 428                              next_qualifier && *next_qualifier &&
 429                              !(*next_qualifier)(sk, skb); next_qualifier++)
 430                                 /* nothing */;
 431                         if (!next_qualifier || !*next_qualifier)
 432                                 /* all qualifiers executed successfully; this is
 433                                  * our transition; return it so we can perform
 434                                  * the associated actions & change the state
 435                                  */
 436                                 return *next_trans;
 437                 }
 438         }
 439         return NULL;
 440 }
 441
 442 /**
 443  *      llc_exec_conn_trans_actions - executes related actions
 444  *      @sk: connection
 445  *      @trans: transition that it's actions must be performed
 446  *      @skb: event
 447  *
 448  *      Executes actions that is related to happened event. Returns 0 for
 449  *      success, 1 to indicate failure of at least one action.
 450  */
 451 static int llc_exec_conn_trans_actions(struct sock *sk,
 452                                        struct llc_conn_state_trans *trans,
 453                                        struct sk_buff *skb)
 454 {
 455         int rc = 0;
 456         llc_conn_action_t *next_action;
 457
 458         for (next_action = trans->ev_actions;
 459              next_action && *next_action; next_action++) {
 460                 int rc2 = (*next_action)(sk, skb);
 461
 462                 if (rc2 == 2) {
 463                         rc = rc2;
 464                         break;
 465                 } else if (rc2)
 466                         rc = 1;
 467         }
 468         return rc;
 469 }
 470
 471 /**
 472  *      __llc_lookup_established - Finds connection for the remote/local sap/mac
 473  *      @sap: SAP
 474  *      @daddr: address of remote LLC (MAC + SAP)
 475  *      @laddr: address of local LLC (MAC + SAP)
 476  *
 477  *      Search connection list of the SAP and finds connection using the remote
 478  *      mac, remote sap, local mac, and local sap. Returns pointer for
 479  *      connection found, %NULL otherwise.
 480  *      Caller has to make sure local_bh is disabled.
 481  */
 482 static struct sock *__llc_lookup_established(struct llc_sap *sap,
 483                                              struct llc_addr *daddr,
 484                                              struct llc_addr *laddr)
 485 {
 486         struct sock *rc;
 487         struct hlist_node *node;
 488
 489         read_lock(&sap->sk_list.lock);
 490         sk_for_each(rc, node, &sap->sk_list.list) {
 491                 struct llc_sock *llc = llc_sk(rc);
 492
 493                 if (llc->laddr.lsap == laddr->lsap &&
 494                     llc->daddr.lsap == daddr->lsap &&
 495                     llc_mac_match(llc->laddr.mac, laddr->mac) &&
 496                     llc_mac_match(llc->daddr.mac, daddr->mac)) {
 497                         sock_hold(rc);
 498                         goto found;
 499                 }
 500         }
 501         rc = NULL;
 502 found:
 503         read_unlock(&sap->sk_list.lock);
 504         return rc;
 505 }
 506
 507 struct sock *llc_lookup_established(struct llc_sap *sap,
 508                                     struct llc_addr *daddr,
 509                                     struct llc_addr *laddr)
 510 {
 511         struct sock *sk;
 512
 513         local_bh_disable();
 514         sk = __llc_lookup_established(sap, daddr, laddr);
 515         local_bh_enable();
 516         return sk;
 517 }
 518
 519 /**
 520  *      llc_lookup_listener - Finds listener for local MAC + SAP
 521  *      @sap: SAP
 522  *      @laddr: address of local LLC (MAC + SAP)
 523  *
 524  *      Search connection list of the SAP and finds connection listening on
 525  *      local mac, and local sap. Returns pointer for parent socket found,
 526  *      %NULL otherwise.
 527  *      Caller has to make sure local_bh is disabled.
 528  */
 529 static struct sock *llc_lookup_listener(struct llc_sap *sap,
 530                                         struct llc_addr *laddr)
 531 {
 532         struct sock *rc;
 533         struct hlist_node *node;
 534
 535         read_lock(&sap->sk_list.lock);
 536         sk_for_each(rc, node, &sap->sk_list.list) {
 537                 struct llc_sock *llc = llc_sk(rc);
 538
 539                 if (rc->sk_type == SOCK_STREAM && rc->sk_state == TCP_LISTEN &&
 540                     llc->laddr.lsap == laddr->lsap &&
 541                     (llc_mac_match(llc->laddr.mac, laddr->mac) ||
 542                      llc_mac_null(llc->laddr.mac))) {
 543                         sock_hold(rc);
 544                         goto found;
 545                 }
 546         }
 547         rc = NULL;
 548 found:
 549         read_unlock(&sap->sk_list.lock);
 550         return rc;
 551 }
 552
 553 static struct sock *__llc_lookup(struct llc_sap *sap,
 554                                  struct llc_addr *daddr,
 555                                  struct llc_addr *laddr)
 556 {
 557         struct sock *sk = __llc_lookup_established(sap, daddr, laddr);
 558
 559         return sk ? : llc_lookup_listener(sap, laddr);
 560 }
 561
 562 /**
 563  *      llc_data_accept_state - designates if in this state data can be sent.
 564  *      @state: state of connection.
 565  *
 566  *      Returns 0 if data can be sent, 1 otherwise.
 567  */
 568 u8 llc_data_accept_state(u8 state)
 569 {
 570         return state != LLC_CONN_STATE_NORMAL && state != LLC_CONN_STATE_BUSY &&
 571                state != LLC_CONN_STATE_REJ;
 572 }
 573
 574 /**
 575  *      llc_find_next_offset - finds offset for next category of transitions
 576  *      @state: state table.
 577  *      @offset: start offset.
 578  *
 579  *      Finds offset of next category of transitions in transition table.
 580  *      Returns the start index of next category.
 581  */
 582 static u16 __init llc_find_next_offset(struct llc_conn_state *state, u16 offset)
 583 {
 584         u16 cnt = 0;
 585         struct llc_conn_state_trans **next_trans;
 586
 587         for (next_trans = state->transitions + offset;
 588              (*next_trans)->ev; next_trans++)
 589                 ++cnt;
 590         return cnt;
 591 }
 592
 593 /**
 594  *      llc_build_offset_table - builds offset table of connection
 595  *
 596  *      Fills offset table of connection state transition table
 597  *      (llc_offset_table).
 598  */
 599 void __init llc_build_offset_table(void)
 600 {
 601         struct llc_conn_state *curr_state;
 602         int state, ev_type, next_offset;
 603
 604         for (state = 0; state < NBR_CONN_STATES; state++) {
 605                 curr_state = &llc_conn_state_table[state];
 606                 next_offset = 0;
 607                 for (ev_type = 0; ev_type < NBR_CONN_EV; ev_type++) {
 608                         llc_offset_table[state][ev_type] = next_offset;
 609                         next_offset += llc_find_next_offset(curr_state,
 610                                                             next_offset) + 1;
 611                 }
 612         }
 613 }
 614
 615 /**
 616  *      llc_find_offset - finds start offset of category of transitions
 617  *      @state: state of connection
 618  *      @ev_type: type of happened event
 619  *
 620  *      Finds start offset of desired category of transitions. Returns the
 621  *      desired start offset.
 622  */
 623 static int llc_find_offset(int state, int ev_type)
 624 {
 625         int rc = 0;
 626         /* at this stage, llc_offset_table[..][2] is not important. it is for
 627          * init_pf_cycle and I don't know what is it.
 628          */
 629         switch (ev_type) {
 630         case LLC_CONN_EV_TYPE_PRIM:
 631                 rc = llc_offset_table[state][0]; break;
 632         case LLC_CONN_EV_TYPE_PDU:
 633                 rc = llc_offset_table[state][4]; break;
 634         case LLC_CONN_EV_TYPE_SIMPLE:
 635                 rc = llc_offset_table[state][1]; break;
 636         case LLC_CONN_EV_TYPE_P_TMR:
 637         case LLC_CONN_EV_TYPE_ACK_TMR:
 638         case LLC_CONN_EV_TYPE_REJ_TMR:
 639         case LLC_CONN_EV_TYPE_BUSY_TMR:
 640                 rc = llc_offset_table[state][3]; break;
 641         }
 642         return rc;
 643 }
 644
 645 /**
 646  *      llc_sap_add_socket - adds a socket to a SAP
 647  *      @sap: SAP
 648  *      @sk: socket
 649  *
 650  *      This function adds a socket to sk_list of a SAP.
 651  */
 652 void llc_sap_add_socket(struct llc_sap *sap, struct sock *sk)
 653 {
 654         llc_sap_hold(sap);
 655         write_lock_bh(&sap->sk_list.lock);
 656         llc_sk(sk)->sap = sap;
 657         sk_add_node(sk, &sap->sk_list.list);
 658         write_unlock_bh(&sap->sk_list.lock);
 659 }
 660
 661 /**
 662  *      llc_sap_remove_socket - removes a socket from SAP
 663  *      @sap: SAP
 664  *      @sk: socket
 665  *
 666  *      This function removes a connection from sk_list.list of a SAP if
 667  *      the connection was in this list.
 668  */
 669 void llc_sap_remove_socket(struct llc_sap *sap, struct sock *sk)
 670 {
 671         write_lock_bh(&sap->sk_list.lock);
 672         sk_del_node_init(sk);
 673         write_unlock_bh(&sap->sk_list.lock);
 674         llc_sap_put(sap);
 675 }
 676
 677 /**
 678  *      llc_conn_rcv - sends received pdus to the connection state machine
 679  *      @sk: current connection structure.
 680  *      @skb: received frame.
 681  *
 682  *      Sends received pdus to the connection state machine.
 683  */
 684 static int llc_conn_rcv(struct sock* sk, struct sk_buff *skb)
 685 {
 686         struct llc_conn_state_ev *ev = llc_conn_ev(skb);
 687
 688         ev->type   = LLC_CONN_EV_TYPE_PDU;
 689         ev->reason = 0;
 690         return llc_conn_state_process(sk, skb);
 691 }
 692
 693 static struct sock *llc_create_incoming_sock(struct sock *sk,
 694                                              struct net_device *dev,
 695                                              struct llc_addr *saddr,
 696                                              struct llc_addr *daddr)
 697 {
 698         struct sock *newsk = llc_sk_alloc(sock_net(sk), sk->sk_family, GFP_ATOMIC,
 699                                           sk->sk_prot);
 700         struct llc_sock *newllc, *llc = llc_sk(sk);
 701
 702         if (!newsk)
 703                 goto out;
 704         newllc = llc_sk(newsk);
 705         memcpy(&newllc->laddr, daddr, sizeof(newllc->laddr));
 706         memcpy(&newllc->daddr, saddr, sizeof(newllc->daddr));
 707         newllc->dev = dev;
 708         dev_hold(dev);
 709         llc_sap_add_socket(llc->sap, newsk);
 710         llc_sap_hold(llc->sap);
 711 out:
 712         return newsk;
 713 }
 714
 715 void llc_conn_handler(struct llc_sap *sap, struct sk_buff *skb)
 716 {
 717         struct llc_addr saddr, daddr;
 718         struct sock *sk;
 719
 720         llc_pdu_decode_sa(skb, saddr.mac);
 721         llc_pdu_decode_ssap(skb, &saddr.lsap);
 722         llc_pdu_decode_da(skb, daddr.mac);
 723         llc_pdu_decode_dsap(skb, &daddr.lsap);
 724
 725         sk = __llc_lookup(sap, &saddr, &daddr);
 726         if (!sk)
 727                 goto drop;
 728
 729         bh_lock_sock(sk);
 730         /*
 731          * This has to be done here and not at the upper layer ->accept
 732          * method because of the way the PROCOM state machine works:
 733          * it needs to set several state variables (see, for instance,
 734          * llc_adm_actions_2 in net/llc/llc_c_st.c) and send a packet to
 735          * the originator of the new connection, and this state has to be
 736          * in the newly created struct sock private area. -acme
 737          */
 738         if (unlikely(sk->sk_state == TCP_LISTEN)) {
 739                 struct sock *newsk = llc_create_incoming_sock(sk, skb->dev,
 740                                                               &saddr, &daddr);
 741                 if (!newsk)
 742                         goto drop_unlock;
 743                 skb_set_owner_r(skb, newsk);
 744         } else {
 745                 /*
 746                  * Can't be skb_set_owner_r, this will be done at the
 747                  * llc_conn_state_process function, later on, when we will use
 748                  * skb_queue_rcv_skb to send it to upper layers, this is
 749                  * another trick required to cope with how the PROCOM state
 750                  * machine works. -acme
 751                  */
 752                 skb->sk = sk;
 753         }
 754         if (!sock_owned_by_user(sk))
 755                 llc_conn_rcv(sk, skb);
 756         else {
 757                 dprintk("%s: adding to backlog...\n", __func__);
 758                 llc_set_backlog_type(skb, LLC_PACKET);
 759                 sk_add_backlog(sk, skb);
 760         }
 761 out:
 762         bh_unlock_sock(sk);
 763         sock_put(sk);
 764         return;
 765 drop:
 766         kfree_skb(skb);
 767         return;
 768 drop_unlock:
 769         kfree_skb(skb);
 770         goto out;
 771 }
 772
 773 #undef LLC_REFCNT_DEBUG
 774 #ifdef LLC_REFCNT_DEBUG
 775 static atomic_t llc_sock_nr;
 776 #endif
 777
 778 /**
 779  *      llc_backlog_rcv - Processes rx frames and expired timers.
 780  *      @sk: LLC sock (p8022 connection)
 781  *      @skb: queued rx frame or event
 782  *
 783  *      This function processes frames that has received and timers that has
 784  *      expired during sending an I pdu (refer to data_req_handler).  frames
 785  *      queue by llc_rcv function (llc_mac.c) and timers queue by timer
 786  *      callback functions(llc_c_ac.c).
 787  */
 788 static int llc_backlog_rcv(struct sock *sk, struct sk_buff *skb)
 789 {
 790         int rc = 0;
 791         struct llc_sock *llc = llc_sk(sk);
 792
 793         if (likely(llc_backlog_type(skb) == LLC_PACKET)) {
 794                 if (likely(llc->state > 1)) /* not closed */
 795                         rc = llc_conn_rcv(sk, skb);
 796                 else
 797                         goto out_kfree_skb;
 798         } else if (llc_backlog_type(skb) == LLC_EVENT) {
 799                 /* timer expiration event */
 800                 if (likely(llc->state > 1))  /* not closed */
 801                         rc = llc_conn_state_process(sk, skb);
 802                 else
 803                         goto out_kfree_skb;
 804         } else {
 805                 printk(KERN_ERR "%s: invalid skb in backlog\n", __func__);
 806                 goto out_kfree_skb;
 807         }
 808 out:
 809         return rc;
 810 out_kfree_skb:
 811         kfree_skb(skb);
 812         goto out;
 813 }
 814
 815 /**
 816  *     llc_sk_init - Initializes a socket with default llc values.
 817  *     @sk: socket to initialize.
 818  *
 819  *     Initializes a socket with default llc values.
 820  */
 821 static void llc_sk_init(struct sock* sk)
 822 {
 823         struct llc_sock *llc = llc_sk(sk);
 824
 825         llc->state    = LLC_CONN_STATE_ADM;
 826         llc->inc_cntr = llc->dec_cntr = 2;
 827         llc->dec_step = llc->connect_step = 1;
 828
 829         setup_timer(&llc->ack_timer.timer, llc_conn_ack_tmr_cb,
 830                         (unsigned long)sk);
 831         llc->ack_timer.expire         = sysctl_llc2_ack_timeout;
 832
 833         setup_timer(&llc->pf_cycle_timer.timer, llc_conn_pf_cycle_tmr_cb,
 834                         (unsigned long)sk);
 835         llc->pf_cycle_timer.expire         = sysctl_llc2_p_timeout;
 836
 837         setup_timer(&llc->rej_sent_timer.timer, llc_conn_rej_tmr_cb,
 838                         (unsigned long)sk);
 839         llc->rej_sent_timer.expire         = sysctl_llc2_rej_timeout;
 840
 841         setup_timer(&llc->busy_state_timer.timer, llc_conn_busy_tmr_cb,
 842                         (unsigned long)sk);
 843         llc->busy_state_timer.expire         = sysctl_llc2_busy_timeout;
 844
 845         llc->n2 = 2;   /* max retransmit */
 846         llc->k  = 2;   /* tx win size, will adjust dynam */
 847         llc->rw = 128; /* rx win size (opt and equal to
 848                         * tx_win of remote LLC) */
 849         skb_queue_head_init(&llc->pdu_unack_q);
 850         sk->sk_backlog_rcv = llc_backlog_rcv;
 851 }
 852
 853 /**
 854  *      llc_sk_alloc - Allocates LLC sock
 855  *      @family: upper layer protocol family
 856  *      @priority: for allocation (%GFP_KERNEL, %GFP_ATOMIC, etc)
 857  *
 858  *      Allocates a LLC sock and initializes it. Returns the new LLC sock
 859  *      or %NULL if there's no memory available for one
 860  */
 861 struct sock *llc_sk_alloc(struct net *net, int family, gfp_t priority, struct proto *prot)
 862 {
 863         struct sock *sk = sk_alloc(net, family, priority, prot);
 864
 865         if (!sk)
 866                 goto out;
 867         llc_sk_init(sk);
 868         sock_init_data(NULL, sk);
 869 #ifdef LLC_REFCNT_DEBUG
 870         atomic_inc(&llc_sock_nr);
 871         printk(KERN_DEBUG "LLC socket %p created in %s, now we have %d alive\n", sk,
 872                 __func__, atomic_read(&llc_sock_nr));
 873 #endif
 874 out:
 875         return sk;
 876 }
 877
 878 /**
 879  *      llc_sk_free - Frees a LLC socket
 880  *      @sk - socket to free
 881  *
 882  *      Frees a LLC socket
 883  */
 884 void llc_sk_free(struct sock *sk)
 885 {
 886         struct llc_sock *llc = llc_sk(sk);
 887
 888         llc->state = LLC_CONN_OUT_OF_SVC;
 889         /* Stop all (possibly) running timers */
 890         llc_conn_ac_stop_all_timers(sk, NULL);
 891 #ifdef DEBUG_LLC_CONN_ALLOC
 892         printk(KERN_INFO "%s: unackq=%d, txq=%d\n", __func__,
 893                 skb_queue_len(&llc->pdu_unack_q),
 894                 skb_queue_len(&sk->sk_write_queue));
 895 #endif
 896         skb_queue_purge(&sk->sk_receive_queue);
 897         skb_queue_purge(&sk->sk_write_queue);
 898         skb_queue_purge(&llc->pdu_unack_q);
 899 #ifdef LLC_REFCNT_DEBUG
 900         if (atomic_read(&sk->sk_refcnt) != 1) {
 901                 printk(KERN_DEBUG "Destruction of LLC sock %p delayed in %s, cnt=%d\n",
 902                         sk, __func__, atomic_read(&sk->sk_refcnt));
 903                 printk(KERN_DEBUG "%d LLC sockets are still alive\n",
 904                         atomic_read(&llc_sock_nr));
 905         } else {
 906                 atomic_dec(&llc_sock_nr);
 907                 printk(KERN_DEBUG "LLC socket %p released in %s, %d are still alive\n", sk,
 908                         __func__, atomic_read(&llc_sock_nr));
 909         }
 910 #endif
 911         sock_put(sk);
 912 }
 913
 914 /**
 915  *      llc_sk_reset - resets a connection
 916  *      @sk: LLC socket to reset
 917  *
 918  *      Resets a connection to the out of service state. Stops its timers
 919  *      and frees any frames in the queues of the connection.
 920  */
 921 void llc_sk_reset(struct sock *sk)
 922 {
 923         struct llc_sock *llc = llc_sk(sk);
 924
 925         llc_conn_ac_stop_all_timers(sk, NULL);
 926         skb_queue_purge(&sk->sk_write_queue);
 927         skb_queue_purge(&llc->pdu_unack_q);
 928         llc->remote_busy_flag   = 0;
 929         llc->cause_flag         = 0;
 930         llc->retry_count        = 0;
 931         llc_conn_set_p_flag(sk, 0);
 932         llc->f_flag             = 0;
 933         llc->s_flag             = 0;
 934         llc->ack_pf             = 0;
 935         llc->first_pdu_Ns       = 0;
 936         llc->ack_must_be_send   = 0;
 937         llc->dec_step           = 1;
 938         llc->inc_cntr           = 2;
 939         llc->dec_cntr           = 2;
 940         llc->X                  = 0;
 941         llc->failed_data_req    = 0 ;
 942         llc->last_nr            = 0;
 943 }