linux/net/llc/llc_conn.c
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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
  31static int llc_find_offset(int state, int ev_type);
  32static void llc_conn_send_pdus(struct sock *sk);
  33static int llc_conn_service(struct sock *sk, struct sk_buff *skb);
  34static int llc_exec_conn_trans_actions(struct sock *sk,
  35                                       struct llc_conn_state_trans *trans,
  36                                       struct sk_buff *ev);
  37static 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 */
  41static int llc_offset_table[NBR_CONN_STATES][NBR_CONN_EV];
  42
  43int sysctl_llc2_ack_timeout = LLC2_ACK_TIME * HZ;
  44int sysctl_llc2_p_timeout = LLC2_P_TIME * HZ;
  45int sysctl_llc2_rej_timeout = LLC2_REJ_TIME * HZ;
  46int 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 */
  58int 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                /* XXX this is not very pretty, perhaps we should store
  83                 * XXX indicate/confirm-needed state in the llc_conn_state_ev
  84                 * XXX control block of the SKB instead? -DaveM
  85                 */
  86                if (!skb->next)
  87                        goto out_kfree_skb;
  88                goto out_skb_put;
  89        }
  90
  91        if (unlikely(ev->ind_prim && ev->cfm_prim)) /* Paranoia */
  92                skb_get(skb);
  93
  94        switch (ev->ind_prim) {
  95        case LLC_DATA_PRIM:
  96                llc_save_primitive(sk, skb, LLC_DATA_PRIM);
  97                if (unlikely(sock_queue_rcv_skb(sk, skb))) {
  98                        /*
  99                         * shouldn't happen
 100                         */
 101                        printk(KERN_ERR "%s: sock_queue_rcv_skb failed!\n",
 102                               __func__);
 103                        kfree_skb(skb);
 104                }
 105                break;
 106        case LLC_CONN_PRIM:
 107                /*
 108                 * Can't be sock_queue_rcv_skb, because we have to leave the
 109                 * skb->sk pointing to the newly created struct sock in
 110                 * llc_conn_handler. -acme
 111                 */
 112                skb_queue_tail(&sk->sk_receive_queue, skb);
 113                sk->sk_state_change(sk);
 114                break;
 115        case LLC_DISC_PRIM:
 116                sock_hold(sk);
 117                if (sk->sk_type == SOCK_STREAM &&
 118                    sk->sk_state == TCP_ESTABLISHED) {
 119                        sk->sk_shutdown       = SHUTDOWN_MASK;
 120                        sk->sk_socket->state  = SS_UNCONNECTED;
 121                        sk->sk_state          = TCP_CLOSE;
 122                        if (!sock_flag(sk, SOCK_DEAD)) {
 123                                sock_set_flag(sk, SOCK_DEAD);
 124                                sk->sk_state_change(sk);
 125                        }
 126                }
 127                kfree_skb(skb);
 128                sock_put(sk);
 129                break;
 130        case LLC_RESET_PRIM:
 131                /*
 132                 * FIXME:
 133                 * RESET is not being notified to upper layers for now
 134                 */
 135                printk(KERN_INFO "%s: received a reset ind!\n", __func__);
 136                kfree_skb(skb);
 137                break;
 138        default:
 139                if (ev->ind_prim) {
 140                        printk(KERN_INFO "%s: received unknown %d prim!\n",
 141                                __func__, ev->ind_prim);
 142                        kfree_skb(skb);
 143                }
 144                /* No indication */
 145                break;
 146        }
 147
 148        switch (ev->cfm_prim) {
 149        case LLC_DATA_PRIM:
 150                if (!llc_data_accept_state(llc->state))
 151                        sk->sk_write_space(sk);
 152                else
 153                        rc = llc->failed_data_req = 1;
 154                break;
 155        case LLC_CONN_PRIM:
 156                if (sk->sk_type == SOCK_STREAM &&
 157                    sk->sk_state == TCP_SYN_SENT) {
 158                        if (ev->status) {
 159                                sk->sk_socket->state = SS_UNCONNECTED;
 160                                sk->sk_state         = TCP_CLOSE;
 161                        } else {
 162                                sk->sk_socket->state = SS_CONNECTED;
 163                                sk->sk_state         = TCP_ESTABLISHED;
 164                        }
 165                        sk->sk_state_change(sk);
 166                }
 167                break;
 168        case LLC_DISC_PRIM:
 169                sock_hold(sk);
 170                if (sk->sk_type == SOCK_STREAM && sk->sk_state == TCP_CLOSING) {
 171                        sk->sk_socket->state = SS_UNCONNECTED;
 172                        sk->sk_state         = TCP_CLOSE;
 173                        sk->sk_state_change(sk);
 174                }
 175                sock_put(sk);
 176                break;
 177        case LLC_RESET_PRIM:
 178                /*
 179                 * FIXME:
 180                 * RESET is not being notified to upper layers for now
 181                 */
 182                printk(KERN_INFO "%s: received a reset conf!\n", __func__);
 183                break;
 184        default:
 185                if (ev->cfm_prim) {
 186                        printk(KERN_INFO "%s: received unknown %d prim!\n",
 187                                        __func__, ev->cfm_prim);
 188                        break;
 189                }
 190                goto out_skb_put; /* No confirmation */
 191        }
 192out_kfree_skb:
 193        kfree_skb(skb);
 194out_skb_put:
 195        kfree_skb(skb);
 196        return rc;
 197}
 198
 199void llc_conn_send_pdu(struct sock *sk, struct sk_buff *skb)
 200{
 201        /* queue PDU to send to MAC layer */
 202        skb_queue_tail(&sk->sk_write_queue, skb);
 203        llc_conn_send_pdus(sk);
 204}
 205
 206/**
 207 *      llc_conn_rtn_pdu - sends received data pdu to upper layer
 208 *      @sk: Active connection
 209 *      @skb: Received data frame
 210 *
 211 *      Sends received data pdu to upper layer (by using indicate function).
 212 *      Prepares service parameters (prim and prim_data). calling indication
 213 *      function will be done in llc_conn_state_process.
 214 */
 215void llc_conn_rtn_pdu(struct sock *sk, struct sk_buff *skb)
 216{
 217        struct llc_conn_state_ev *ev = llc_conn_ev(skb);
 218
 219        ev->ind_prim = LLC_DATA_PRIM;
 220}
 221
 222/**
 223 *      llc_conn_resend_i_pdu_as_cmd - resend all all unacknowledged I PDUs
 224 *      @sk: active connection
 225 *      @nr: NR
 226 *      @first_p_bit: p_bit value of first pdu
 227 *
 228 *      Resend all unacknowledged I PDUs, starting with the NR; send first as
 229 *      command PDU with P bit equal first_p_bit; if more than one send
 230 *      subsequent as command PDUs with P bit equal zero (0).
 231 */
 232void llc_conn_resend_i_pdu_as_cmd(struct sock *sk, u8 nr, u8 first_p_bit)
 233{
 234        struct sk_buff *skb;
 235        struct llc_pdu_sn *pdu;
 236        u16 nbr_unack_pdus;
 237        struct llc_sock *llc;
 238        u8 howmany_resend = 0;
 239
 240        llc_conn_remove_acked_pdus(sk, nr, &nbr_unack_pdus);
 241        if (!nbr_unack_pdus)
 242                goto out;
 243        /*
 244         * Process unack PDUs only if unack queue is not empty; remove
 245         * appropriate PDUs, fix them up, and put them on mac_pdu_q.
 246         */
 247        llc = llc_sk(sk);
 248
 249        while ((skb = skb_dequeue(&llc->pdu_unack_q)) != NULL) {
 250                pdu = llc_pdu_sn_hdr(skb);
 251                llc_pdu_set_cmd_rsp(skb, LLC_PDU_CMD);
 252                llc_pdu_set_pf_bit(skb, first_p_bit);
 253                skb_queue_tail(&sk->sk_write_queue, skb);
 254                first_p_bit = 0;
 255                llc->vS = LLC_I_GET_NS(pdu);
 256                howmany_resend++;
 257        }
 258        if (howmany_resend > 0)
 259                llc->vS = (llc->vS + 1) % LLC_2_SEQ_NBR_MODULO;
 260        /* any PDUs to re-send are queued up; start sending to MAC */
 261        llc_conn_send_pdus(sk);
 262out:;
 263}
 264
 265/**
 266 *      llc_conn_resend_i_pdu_as_rsp - Resend all unacknowledged I PDUs
 267 *      @sk: active connection.
 268 *      @nr: NR
 269 *      @first_f_bit: f_bit value of first pdu.
 270 *
 271 *      Resend all unacknowledged I PDUs, starting with the NR; send first as
 272 *      response PDU with F bit equal first_f_bit; if more than one send
 273 *      subsequent as response PDUs with F bit equal zero (0).
 274 */
 275void llc_conn_resend_i_pdu_as_rsp(struct sock *sk, u8 nr, u8 first_f_bit)
 276{
 277        struct sk_buff *skb;
 278        u16 nbr_unack_pdus;
 279        struct llc_sock *llc = llc_sk(sk);
 280        u8 howmany_resend = 0;
 281
 282        llc_conn_remove_acked_pdus(sk, nr, &nbr_unack_pdus);
 283        if (!nbr_unack_pdus)
 284                goto out;
 285        /*
 286         * Process unack PDUs only if unack queue is not empty; remove
 287         * appropriate PDUs, fix them up, and put them on mac_pdu_q
 288         */
 289        while ((skb = skb_dequeue(&llc->pdu_unack_q)) != NULL) {
 290                struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
 291
 292                llc_pdu_set_cmd_rsp(skb, LLC_PDU_RSP);
 293                llc_pdu_set_pf_bit(skb, first_f_bit);
 294                skb_queue_tail(&sk->sk_write_queue, skb);
 295                first_f_bit = 0;
 296                llc->vS = LLC_I_GET_NS(pdu);
 297                howmany_resend++;
 298        }
 299        if (howmany_resend > 0)
 300                llc->vS = (llc->vS + 1) % LLC_2_SEQ_NBR_MODULO;
 301        /* any PDUs to re-send are queued up; start sending to MAC */
 302        llc_conn_send_pdus(sk);
 303out:;
 304}
 305
 306/**
 307 *      llc_conn_remove_acked_pdus - Removes acknowledged pdus from tx queue
 308 *      @sk: active connection
 309 *      nr: NR
 310 *      how_many_unacked: size of pdu_unack_q after removing acked pdus
 311 *
 312 *      Removes acknowledged pdus from transmit queue (pdu_unack_q). Returns
 313 *      the number of pdus that removed from queue.
 314 */
 315int llc_conn_remove_acked_pdus(struct sock *sk, u8 nr, u16 *how_many_unacked)
 316{
 317        int pdu_pos, i;
 318        struct sk_buff *skb;
 319        struct llc_pdu_sn *pdu;
 320        int nbr_acked = 0;
 321        struct llc_sock *llc = llc_sk(sk);
 322        int q_len = skb_queue_len(&llc->pdu_unack_q);
 323
 324        if (!q_len)
 325                goto out;
 326        skb = skb_peek(&llc->pdu_unack_q);
 327        pdu = llc_pdu_sn_hdr(skb);
 328
 329        /* finding position of last acked pdu in queue */
 330        pdu_pos = ((int)LLC_2_SEQ_NBR_MODULO + (int)nr -
 331                        (int)LLC_I_GET_NS(pdu)) % LLC_2_SEQ_NBR_MODULO;
 332
 333        for (i = 0; i < pdu_pos && i < q_len; i++) {
 334                skb = skb_dequeue(&llc->pdu_unack_q);
 335                if (skb)
 336                        kfree_skb(skb);
 337                nbr_acked++;
 338        }
 339out:
 340        *how_many_unacked = skb_queue_len(&llc->pdu_unack_q);
 341        return nbr_acked;
 342}
 343
 344/**
 345 *      llc_conn_send_pdus - Sends queued PDUs
 346 *      @sk: active connection
 347 *
 348 *      Sends queued pdus to MAC layer for transmission.
 349 */
 350static void llc_conn_send_pdus(struct sock *sk)
 351{
 352        struct sk_buff *skb;
 353
 354        while ((skb = skb_dequeue(&sk->sk_write_queue)) != NULL) {
 355                struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
 356
 357                if (LLC_PDU_TYPE_IS_I(pdu) &&
 358                    !(skb->dev->flags & IFF_LOOPBACK)) {
 359                        struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
 360
 361                        skb_queue_tail(&llc_sk(sk)->pdu_unack_q, skb);
 362                        if (!skb2)
 363                                break;
 364                        skb = skb2;
 365                }
 366                dev_queue_xmit(skb);
 367        }
 368}
 369
 370/**
 371 *      llc_conn_service - finds transition and changes state of connection
 372 *      @sk: connection
 373 *      @skb: happened event
 374 *
 375 *      This function finds transition that matches with happened event, then
 376 *      executes related actions and finally changes state of connection.
 377 *      Returns 0 for success, 1 for failure.
 378 */
 379static int llc_conn_service(struct sock *sk, struct sk_buff *skb)
 380{
 381        int rc = 1;
 382        struct llc_sock *llc = llc_sk(sk);
 383        struct llc_conn_state_trans *trans;
 384
 385        if (llc->state > NBR_CONN_STATES)
 386                goto out;
 387        rc = 0;
 388        trans = llc_qualify_conn_ev(sk, skb);
 389        if (trans) {
 390                rc = llc_exec_conn_trans_actions(sk, trans, skb);
 391                if (!rc && trans->next_state != NO_STATE_CHANGE) {
 392                        llc->state = trans->next_state;
 393                        if (!llc_data_accept_state(llc->state))
 394                                sk->sk_state_change(sk);
 395                }
 396        }
 397out:
 398        return rc;
 399}
 400
 401/**
 402 *      llc_qualify_conn_ev - finds transition for event
 403 *      @sk: connection
 404 *      @skb: happened event
 405 *
 406 *      This function finds transition that matches with happened event.
 407 *      Returns pointer to found transition on success, %NULL otherwise.
 408 */
 409static struct llc_conn_state_trans *llc_qualify_conn_ev(struct sock *sk,
 410                                                        struct sk_buff *skb)
 411{
 412        struct llc_conn_state_trans **next_trans;
 413        llc_conn_ev_qfyr_t *next_qualifier;
 414        struct llc_conn_state_ev *ev = llc_conn_ev(skb);
 415        struct llc_sock *llc = llc_sk(sk);
 416        struct llc_conn_state *curr_state =
 417                                        &llc_conn_state_table[llc->state - 1];
 418
 419        /* search thru events for this state until
 420         * list exhausted or until no more
 421         */
 422        for (next_trans = curr_state->transitions +
 423                llc_find_offset(llc->state - 1, ev->type);
 424             (*next_trans)->ev; next_trans++) {
 425                if (!((*next_trans)->ev)(sk, skb)) {
 426                        /* got POSSIBLE event match; the event may require
 427                         * qualification based on the values of a number of
 428                         * state flags; if all qualifications are met (i.e.,
 429                         * if all qualifying functions return success, or 0,
 430                         * then this is THE event we're looking for
 431                         */
 432                        for (next_qualifier = (*next_trans)->ev_qualifiers;
 433                             next_qualifier && *next_qualifier &&
 434                             !(*next_qualifier)(sk, skb); next_qualifier++)
 435                                /* nothing */;
 436                        if (!next_qualifier || !*next_qualifier)
 437                                /* all qualifiers executed successfully; this is
 438                                 * our transition; return it so we can perform
 439                                 * the associated actions & change the state
 440                                 */
 441                                return *next_trans;
 442                }
 443        }
 444        return NULL;
 445}
 446
 447/**
 448 *      llc_exec_conn_trans_actions - executes related actions
 449 *      @sk: connection
 450 *      @trans: transition that it's actions must be performed
 451 *      @skb: event
 452 *
 453 *      Executes actions that is related to happened event. Returns 0 for
 454 *      success, 1 to indicate failure of at least one action.
 455 */
 456static int llc_exec_conn_trans_actions(struct sock *sk,
 457                                       struct llc_conn_state_trans *trans,
 458                                       struct sk_buff *skb)
 459{
 460        int rc = 0;
 461        llc_conn_action_t *next_action;
 462
 463        for (next_action = trans->ev_actions;
 464             next_action && *next_action; next_action++) {
 465                int rc2 = (*next_action)(sk, skb);
 466
 467                if (rc2 == 2) {
 468                        rc = rc2;
 469                        break;
 470                } else if (rc2)
 471                        rc = 1;
 472        }
 473        return rc;
 474}
 475
 476/**
 477 *      __llc_lookup_established - Finds connection for the remote/local sap/mac
 478 *      @sap: SAP
 479 *      @daddr: address of remote LLC (MAC + SAP)
 480 *      @laddr: address of local LLC (MAC + SAP)
 481 *
 482 *      Search connection list of the SAP and finds connection using the remote
 483 *      mac, remote sap, local mac, and local sap. Returns pointer for
 484 *      connection found, %NULL otherwise.
 485 *      Caller has to make sure local_bh is disabled.
 486 */
 487static struct sock *__llc_lookup_established(struct llc_sap *sap,
 488                                             struct llc_addr *daddr,
 489                                             struct llc_addr *laddr)
 490{
 491        struct sock *rc;
 492        struct hlist_node *node;
 493
 494        read_lock(&sap->sk_list.lock);
 495        sk_for_each(rc, node, &sap->sk_list.list) {
 496                struct llc_sock *llc = llc_sk(rc);
 497
 498                if (llc->laddr.lsap == laddr->lsap &&
 499                    llc->daddr.lsap == daddr->lsap &&
 500                    llc_mac_match(llc->laddr.mac, laddr->mac) &&
 501                    llc_mac_match(llc->daddr.mac, daddr->mac)) {
 502                        sock_hold(rc);
 503                        goto found;
 504                }
 505        }
 506        rc = NULL;
 507found:
 508        read_unlock(&sap->sk_list.lock);
 509        return rc;
 510}
 511
 512struct sock *llc_lookup_established(struct llc_sap *sap,
 513                                    struct llc_addr *daddr,
 514                                    struct llc_addr *laddr)
 515{
 516        struct sock *sk;
 517
 518        local_bh_disable();
 519        sk = __llc_lookup_established(sap, daddr, laddr);
 520        local_bh_enable();
 521        return sk;
 522}
 523
 524/**
 525 *      llc_lookup_listener - Finds listener for local MAC + SAP
 526 *      @sap: SAP
 527 *      @laddr: address of local LLC (MAC + SAP)
 528 *
 529 *      Search connection list of the SAP and finds connection listening on
 530 *      local mac, and local sap. Returns pointer for parent socket found,
 531 *      %NULL otherwise.
 532 *      Caller has to make sure local_bh is disabled.
 533 */
 534static struct sock *llc_lookup_listener(struct llc_sap *sap,
 535                                        struct llc_addr *laddr)
 536{
 537        struct sock *rc;
 538        struct hlist_node *node;
 539
 540        read_lock(&sap->sk_list.lock);
 541        sk_for_each(rc, node, &sap->sk_list.list) {
 542                struct llc_sock *llc = llc_sk(rc);
 543
 544                if (rc->sk_type == SOCK_STREAM && rc->sk_state == TCP_LISTEN &&
 545                    llc->laddr.lsap == laddr->lsap &&
 546                    (llc_mac_match(llc->laddr.mac, laddr->mac) ||
 547                     llc_mac_null(llc->laddr.mac))) {
 548                        sock_hold(rc);
 549                        goto found;
 550                }
 551        }
 552        rc = NULL;
 553found:
 554        read_unlock(&sap->sk_list.lock);
 555        return rc;
 556}
 557
 558static struct sock *__llc_lookup(struct llc_sap *sap,
 559                                 struct llc_addr *daddr,
 560                                 struct llc_addr *laddr)
 561{
 562        struct sock *sk = __llc_lookup_established(sap, daddr, laddr);
 563
 564        return sk ? : llc_lookup_listener(sap, laddr);
 565}
 566
 567/**
 568 *      llc_data_accept_state - designates if in this state data can be sent.
 569 *      @state: state of connection.
 570 *
 571 *      Returns 0 if data can be sent, 1 otherwise.
 572 */
 573u8 llc_data_accept_state(u8 state)
 574{
 575        return state != LLC_CONN_STATE_NORMAL && state != LLC_CONN_STATE_BUSY &&
 576               state != LLC_CONN_STATE_REJ;
 577}
 578
 579/**
 580 *      llc_find_next_offset - finds offset for next category of transitions
 581 *      @state: state table.
 582 *      @offset: start offset.
 583 *
 584 *      Finds offset of next category of transitions in transition table.
 585 *      Returns the start index of next category.
 586 */
 587static u16 __init llc_find_next_offset(struct llc_conn_state *state, u16 offset)
 588{
 589        u16 cnt = 0;
 590        struct llc_conn_state_trans **next_trans;
 591
 592        for (next_trans = state->transitions + offset;
 593             (*next_trans)->ev; next_trans++)
 594                ++cnt;
 595        return cnt;
 596}
 597
 598/**
 599 *      llc_build_offset_table - builds offset table of connection
 600 *
 601 *      Fills offset table of connection state transition table
 602 *      (llc_offset_table).
 603 */
 604void __init llc_build_offset_table(void)
 605{
 606        struct llc_conn_state *curr_state;
 607        int state, ev_type, next_offset;
 608
 609        for (state = 0; state < NBR_CONN_STATES; state++) {
 610                curr_state = &llc_conn_state_table[state];
 611                next_offset = 0;
 612                for (ev_type = 0; ev_type < NBR_CONN_EV; ev_type++) {
 613                        llc_offset_table[state][ev_type] = next_offset;
 614                        next_offset += llc_find_next_offset(curr_state,
 615                                                            next_offset) + 1;
 616                }
 617        }
 618}
 619
 620/**
 621 *      llc_find_offset - finds start offset of category of transitions
 622 *      @state: state of connection
 623 *      @ev_type: type of happened event
 624 *
 625 *      Finds start offset of desired category of transitions. Returns the
 626 *      desired start offset.
 627 */
 628static int llc_find_offset(int state, int ev_type)
 629{
 630        int rc = 0;
 631        /* at this stage, llc_offset_table[..][2] is not important. it is for
 632         * init_pf_cycle and I don't know what is it.
 633         */
 634        switch (ev_type) {
 635        case LLC_CONN_EV_TYPE_PRIM:
 636                rc = llc_offset_table[state][0]; break;
 637        case LLC_CONN_EV_TYPE_PDU:
 638                rc = llc_offset_table[state][4]; break;
 639        case LLC_CONN_EV_TYPE_SIMPLE:
 640                rc = llc_offset_table[state][1]; break;
 641        case LLC_CONN_EV_TYPE_P_TMR:
 642        case LLC_CONN_EV_TYPE_ACK_TMR:
 643        case LLC_CONN_EV_TYPE_REJ_TMR:
 644        case LLC_CONN_EV_TYPE_BUSY_TMR:
 645                rc = llc_offset_table[state][3]; break;
 646        }
 647        return rc;
 648}
 649
 650/**
 651 *      llc_sap_add_socket - adds a socket to a SAP
 652 *      @sap: SAP
 653 *      @sk: socket
 654 *
 655 *      This function adds a socket to sk_list of a SAP.
 656 */
 657void llc_sap_add_socket(struct llc_sap *sap, struct sock *sk)
 658{
 659        llc_sap_hold(sap);
 660        write_lock_bh(&sap->sk_list.lock);
 661        llc_sk(sk)->sap = sap;
 662        sk_add_node(sk, &sap->sk_list.list);
 663        write_unlock_bh(&sap->sk_list.lock);
 664}
 665
 666/**
 667 *      llc_sap_remove_socket - removes a socket from SAP
 668 *      @sap: SAP
 669 *      @sk: socket
 670 *
 671 *      This function removes a connection from sk_list.list of a SAP if
 672 *      the connection was in this list.
 673 */
 674void llc_sap_remove_socket(struct llc_sap *sap, struct sock *sk)
 675{
 676        write_lock_bh(&sap->sk_list.lock);
 677        sk_del_node_init(sk);
 678        write_unlock_bh(&sap->sk_list.lock);
 679        llc_sap_put(sap);
 680}
 681
 682/**
 683 *      llc_conn_rcv - sends received pdus to the connection state machine
 684 *      @sk: current connection structure.
 685 *      @skb: received frame.
 686 *
 687 *      Sends received pdus to the connection state machine.
 688 */
 689static int llc_conn_rcv(struct sock* sk, struct sk_buff *skb)
 690{
 691        struct llc_conn_state_ev *ev = llc_conn_ev(skb);
 692
 693        ev->type   = LLC_CONN_EV_TYPE_PDU;
 694        ev->reason = 0;
 695        return llc_conn_state_process(sk, skb);
 696}
 697
 698static struct sock *llc_create_incoming_sock(struct sock *sk,
 699                                             struct net_device *dev,
 700                                             struct llc_addr *saddr,
 701                                             struct llc_addr *daddr)
 702{
 703        struct sock *newsk = llc_sk_alloc(sock_net(sk), sk->sk_family, GFP_ATOMIC,
 704                                          sk->sk_prot);
 705        struct llc_sock *newllc, *llc = llc_sk(sk);
 706
 707        if (!newsk)
 708                goto out;
 709        newllc = llc_sk(newsk);
 710        memcpy(&newllc->laddr, daddr, sizeof(newllc->laddr));
 711        memcpy(&newllc->daddr, saddr, sizeof(newllc->daddr));
 712        newllc->dev = dev;
 713        dev_hold(dev);
 714        llc_sap_add_socket(llc->sap, newsk);
 715        llc_sap_hold(llc->sap);
 716out:
 717        return newsk;
 718}
 719
 720void llc_conn_handler(struct llc_sap *sap, struct sk_buff *skb)
 721{
 722        struct llc_addr saddr, daddr;
 723        struct sock *sk;
 724
 725        llc_pdu_decode_sa(skb, saddr.mac);
 726        llc_pdu_decode_ssap(skb, &saddr.lsap);
 727        llc_pdu_decode_da(skb, daddr.mac);
 728        llc_pdu_decode_dsap(skb, &daddr.lsap);
 729
 730        sk = __llc_lookup(sap, &saddr, &daddr);
 731        if (!sk)
 732                goto drop;
 733
 734        bh_lock_sock(sk);
 735        /*
 736         * This has to be done here and not at the upper layer ->accept
 737         * method because of the way the PROCOM state machine works:
 738         * it needs to set several state variables (see, for instance,
 739         * llc_adm_actions_2 in net/llc/llc_c_st.c) and send a packet to
 740         * the originator of the new connection, and this state has to be
 741         * in the newly created struct sock private area. -acme
 742         */
 743        if (unlikely(sk->sk_state == TCP_LISTEN)) {
 744                struct sock *newsk = llc_create_incoming_sock(sk, skb->dev,
 745                                                              &saddr, &daddr);
 746                if (!newsk)
 747                        goto drop_unlock;
 748                skb_set_owner_r(skb, newsk);
 749        } else {
 750                /*
 751                 * Can't be skb_set_owner_r, this will be done at the
 752                 * llc_conn_state_process function, later on, when we will use
 753                 * skb_queue_rcv_skb to send it to upper layers, this is
 754                 * another trick required to cope with how the PROCOM state
 755                 * machine works. -acme
 756                 */
 757                skb->sk = sk;
 758        }
 759        if (!sock_owned_by_user(sk))
 760                llc_conn_rcv(sk, skb);
 761        else {
 762                dprintk("%s: adding to backlog...\n", __func__);
 763                llc_set_backlog_type(skb, LLC_PACKET);
 764                sk_add_backlog(sk, skb);
 765        }
 766out:
 767        bh_unlock_sock(sk);
 768        sock_put(sk);
 769        return;
 770drop:
 771        kfree_skb(skb);
 772        return;
 773drop_unlock:
 774        kfree_skb(skb);
 775        goto out;
 776}
 777
 778#undef LLC_REFCNT_DEBUG
 779#ifdef LLC_REFCNT_DEBUG
 780static atomic_t llc_sock_nr;
 781#endif
 782
 783/**
 784 *      llc_backlog_rcv - Processes rx frames and expired timers.
 785 *      @sk: LLC sock (p8022 connection)
 786 *      @skb: queued rx frame or event
 787 *
 788 *      This function processes frames that has received and timers that has
 789 *      expired during sending an I pdu (refer to data_req_handler).  frames
 790 *      queue by llc_rcv function (llc_mac.c) and timers queue by timer
 791 *      callback functions(llc_c_ac.c).
 792 */
 793static int llc_backlog_rcv(struct sock *sk, struct sk_buff *skb)
 794{
 795        int rc = 0;
 796        struct llc_sock *llc = llc_sk(sk);
 797
 798        if (likely(llc_backlog_type(skb) == LLC_PACKET)) {
 799                if (likely(llc->state > 1)) /* not closed */
 800                        rc = llc_conn_rcv(sk, skb);
 801                else
 802                        goto out_kfree_skb;
 803        } else if (llc_backlog_type(skb) == LLC_EVENT) {
 804                /* timer expiration event */
 805                if (likely(llc->state > 1))  /* not closed */
 806                        rc = llc_conn_state_process(sk, skb);
 807                else
 808                        goto out_kfree_skb;
 809        } else {
 810                printk(KERN_ERR "%s: invalid skb in backlog\n", __func__);
 811                goto out_kfree_skb;
 812        }
 813out:
 814        return rc;
 815out_kfree_skb:
 816        kfree_skb(skb);
 817        goto out;
 818}
 819
 820/**
 821 *     llc_sk_init - Initializes a socket with default llc values.
 822 *     @sk: socket to initialize.
 823 *
 824 *     Initializes a socket with default llc values.
 825 */
 826static void llc_sk_init(struct sock* sk)
 827{
 828        struct llc_sock *llc = llc_sk(sk);
 829
 830        llc->state    = LLC_CONN_STATE_ADM;
 831        llc->inc_cntr = llc->dec_cntr = 2;
 832        llc->dec_step = llc->connect_step = 1;
 833
 834        setup_timer(&llc->ack_timer.timer, llc_conn_ack_tmr_cb,
 835                        (unsigned long)sk);
 836        llc->ack_timer.expire         = sysctl_llc2_ack_timeout;
 837
 838        setup_timer(&llc->pf_cycle_timer.timer, llc_conn_pf_cycle_tmr_cb,
 839                        (unsigned long)sk);
 840        llc->pf_cycle_timer.expire         = sysctl_llc2_p_timeout;
 841
 842        setup_timer(&llc->rej_sent_timer.timer, llc_conn_rej_tmr_cb,
 843                        (unsigned long)sk);
 844        llc->rej_sent_timer.expire         = sysctl_llc2_rej_timeout;
 845
 846        setup_timer(&llc->busy_state_timer.timer, llc_conn_busy_tmr_cb,
 847                        (unsigned long)sk);
 848        llc->busy_state_timer.expire         = sysctl_llc2_busy_timeout;
 849
 850        llc->n2 = 2;   /* max retransmit */
 851        llc->k  = 2;   /* tx win size, will adjust dynam */
 852        llc->rw = 128; /* rx win size (opt and equal to
 853                        * tx_win of remote LLC) */
 854        skb_queue_head_init(&llc->pdu_unack_q);
 855        sk->sk_backlog_rcv = llc_backlog_rcv;
 856}
 857
 858/**
 859 *      llc_sk_alloc - Allocates LLC sock
 860 *      @family: upper layer protocol family
 861 *      @priority: for allocation (%GFP_KERNEL, %GFP_ATOMIC, etc)
 862 *
 863 *      Allocates a LLC sock and initializes it. Returns the new LLC sock
 864 *      or %NULL if there's no memory available for one
 865 */
 866struct sock *llc_sk_alloc(struct net *net, int family, gfp_t priority, struct proto *prot)
 867{
 868        struct sock *sk = sk_alloc(net, family, priority, prot);
 869
 870        if (!sk)
 871                goto out;
 872        llc_sk_init(sk);
 873        sock_init_data(NULL, sk);
 874#ifdef LLC_REFCNT_DEBUG
 875        atomic_inc(&llc_sock_nr);
 876        printk(KERN_DEBUG "LLC socket %p created in %s, now we have %d alive\n", sk,
 877                __func__, atomic_read(&llc_sock_nr));
 878#endif
 879out:
 880        return sk;
 881}
 882
 883/**
 884 *      llc_sk_free - Frees a LLC socket
 885 *      @sk - socket to free
 886 *
 887 *      Frees a LLC socket
 888 */
 889void llc_sk_free(struct sock *sk)
 890{
 891        struct llc_sock *llc = llc_sk(sk);
 892
 893        llc->state = LLC_CONN_OUT_OF_SVC;
 894        /* Stop all (possibly) running timers */
 895        llc_conn_ac_stop_all_timers(sk, NULL);
 896#ifdef DEBUG_LLC_CONN_ALLOC
 897        printk(KERN_INFO "%s: unackq=%d, txq=%d\n", __func__,
 898                skb_queue_len(&llc->pdu_unack_q),
 899                skb_queue_len(&sk->sk_write_queue));
 900#endif
 901        skb_queue_purge(&sk->sk_receive_queue);
 902        skb_queue_purge(&sk->sk_write_queue);
 903        skb_queue_purge(&llc->pdu_unack_q);
 904#ifdef LLC_REFCNT_DEBUG
 905        if (atomic_read(&sk->sk_refcnt) != 1) {
 906                printk(KERN_DEBUG "Destruction of LLC sock %p delayed in %s, cnt=%d\n",
 907                        sk, __func__, atomic_read(&sk->sk_refcnt));
 908                printk(KERN_DEBUG "%d LLC sockets are still alive\n",
 909                        atomic_read(&llc_sock_nr));
 910        } else {
 911                atomic_dec(&llc_sock_nr);
 912                printk(KERN_DEBUG "LLC socket %p released in %s, %d are still alive\n", sk,
 913                        __func__, atomic_read(&llc_sock_nr));
 914        }
 915#endif
 916        sock_put(sk);
 917}
 918
 919/**
 920 *      llc_sk_reset - resets a connection
 921 *      @sk: LLC socket to reset
 922 *
 923 *      Resets a connection to the out of service state. Stops its timers
 924 *      and frees any frames in the queues of the connection.
 925 */
 926void llc_sk_reset(struct sock *sk)
 927{
 928        struct llc_sock *llc = llc_sk(sk);
 929
 930        llc_conn_ac_stop_all_timers(sk, NULL);
 931        skb_queue_purge(&sk->sk_write_queue);
 932        skb_queue_purge(&llc->pdu_unack_q);
 933        llc->remote_busy_flag   = 0;
 934        llc->cause_flag         = 0;
 935        llc->retry_count        = 0;
 936        llc_conn_set_p_flag(sk, 0);
 937        llc->f_flag             = 0;
 938        llc->s_flag             = 0;
 939        llc->ack_pf             = 0;
 940        llc->first_pdu_Ns       = 0;
 941        llc->ack_must_be_send   = 0;
 942        llc->dec_step           = 1;
 943        llc->inc_cntr           = 2;
 944        llc->dec_cntr           = 2;
 945        llc->X                  = 0;
 946        llc->failed_data_req    = 0 ;
 947        llc->last_nr            = 0;
 948}
 949