linux/net/decnet/dn_nsp_in.c
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   1/*
   2 * DECnet       An implementation of the DECnet protocol suite for the LINUX
   3 *              operating system.  DECnet is implemented using the  BSD Socket
   4 *              interface as the means of communication with the user level.
   5 *
   6 *              DECnet Network Services Protocol (Input)
   7 *
   8 * Author:      Eduardo Marcelo Serrat <emserrat@geocities.com>
   9 *
  10 * Changes:
  11 *
  12 *    Steve Whitehouse:  Split into dn_nsp_in.c and dn_nsp_out.c from
  13 *                       original dn_nsp.c.
  14 *    Steve Whitehouse:  Updated to work with my new routing architecture.
  15 *    Steve Whitehouse:  Add changes from Eduardo Serrat's patches.
  16 *    Steve Whitehouse:  Put all ack handling code in a common routine.
  17 *    Steve Whitehouse:  Put other common bits into dn_nsp_rx()
  18 *    Steve Whitehouse:  More checks on skb->len to catch bogus packets
  19 *                       Fixed various race conditions and possible nasties.
  20 *    Steve Whitehouse:  Now handles returned conninit frames.
  21 *     David S. Miller:  New socket locking
  22 *    Steve Whitehouse:  Fixed lockup when socket filtering was enabled.
  23 *         Paul Koning:  Fix to push CC sockets into RUN when acks are
  24 *                       received.
  25 *    Steve Whitehouse:
  26 *   Patrick Caulfield:  Checking conninits for correctness & sending of error
  27 *                       responses.
  28 *    Steve Whitehouse:  Added backlog congestion level return codes.
  29 *   Patrick Caulfield:
  30 *    Steve Whitehouse:  Added flow control support (outbound)
  31 *    Steve Whitehouse:  Prepare for nonlinear skbs
  32 */
  33
  34/******************************************************************************
  35    (c) 1995-1998 E.M. Serrat           emserrat@geocities.com
  36
  37    This program is free software; you can redistribute it and/or modify
  38    it under the terms of the GNU General Public License as published by
  39    the Free Software Foundation; either version 2 of the License, or
  40    any later version.
  41
  42    This program is distributed in the hope that it will be useful,
  43    but WITHOUT ANY WARRANTY; without even the implied warranty of
  44    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  45    GNU General Public License for more details.
  46*******************************************************************************/
  47
  48#include <linux/errno.h>
  49#include <linux/types.h>
  50#include <linux/socket.h>
  51#include <linux/in.h>
  52#include <linux/kernel.h>
  53#include <linux/timer.h>
  54#include <linux/string.h>
  55#include <linux/sockios.h>
  56#include <linux/net.h>
  57#include <linux/netdevice.h>
  58#include <linux/inet.h>
  59#include <linux/route.h>
  60#include <net/sock.h>
  61#include <net/tcp_states.h>
  62#include <asm/system.h>
  63#include <linux/fcntl.h>
  64#include <linux/mm.h>
  65#include <linux/termios.h>
  66#include <linux/interrupt.h>
  67#include <linux/proc_fs.h>
  68#include <linux/stat.h>
  69#include <linux/init.h>
  70#include <linux/poll.h>
  71#include <linux/netfilter_decnet.h>
  72#include <net/neighbour.h>
  73#include <net/dst.h>
  74#include <net/dn.h>
  75#include <net/dn_nsp.h>
  76#include <net/dn_dev.h>
  77#include <net/dn_route.h>
  78
  79extern int decnet_log_martians;
  80
  81static void dn_log_martian(struct sk_buff *skb, const char *msg)
  82{
  83        if (decnet_log_martians && net_ratelimit()) {
  84                char *devname = skb->dev ? skb->dev->name : "???";
  85                struct dn_skb_cb *cb = DN_SKB_CB(skb);
  86                printk(KERN_INFO "DECnet: Martian packet (%s) dev=%s src=0x%04hx dst=0x%04hx srcport=0x%04hx dstport=0x%04hx\n",
  87                       msg, devname, le16_to_cpu(cb->src), le16_to_cpu(cb->dst),
  88                       le16_to_cpu(cb->src_port), le16_to_cpu(cb->dst_port));
  89        }
  90}
  91
  92/*
  93 * For this function we've flipped the cross-subchannel bit
  94 * if the message is an otherdata or linkservice message. Thus
  95 * we can use it to work out what to update.
  96 */
  97static void dn_ack(struct sock *sk, struct sk_buff *skb, unsigned short ack)
  98{
  99        struct dn_scp *scp = DN_SK(sk);
 100        unsigned short type = ((ack >> 12) & 0x0003);
 101        int wakeup = 0;
 102
 103        switch(type) {
 104                case 0: /* ACK - Data */
 105                        if (dn_after(ack, scp->ackrcv_dat)) {
 106                                scp->ackrcv_dat = ack & 0x0fff;
 107                                wakeup |= dn_nsp_check_xmit_queue(sk, skb, &scp->data_xmit_queue, ack);
 108                        }
 109                        break;
 110                case 1: /* NAK - Data */
 111                        break;
 112                case 2: /* ACK - OtherData */
 113                        if (dn_after(ack, scp->ackrcv_oth)) {
 114                                scp->ackrcv_oth = ack & 0x0fff;
 115                                wakeup |= dn_nsp_check_xmit_queue(sk, skb, &scp->other_xmit_queue, ack);
 116                        }
 117                        break;
 118                case 3: /* NAK - OtherData */
 119                        break;
 120        }
 121
 122        if (wakeup && !sock_flag(sk, SOCK_DEAD))
 123                sk->sk_state_change(sk);
 124}
 125
 126/*
 127 * This function is a universal ack processor.
 128 */
 129static int dn_process_ack(struct sock *sk, struct sk_buff *skb, int oth)
 130{
 131        __le16 *ptr = (__le16 *)skb->data;
 132        int len = 0;
 133        unsigned short ack;
 134
 135        if (skb->len < 2)
 136                return len;
 137
 138        if ((ack = le16_to_cpu(*ptr)) & 0x8000) {
 139                skb_pull(skb, 2);
 140                ptr++;
 141                len += 2;
 142                if ((ack & 0x4000) == 0) {
 143                        if (oth)
 144                                ack ^= 0x2000;
 145                        dn_ack(sk, skb, ack);
 146                }
 147        }
 148
 149        if (skb->len < 2)
 150                return len;
 151
 152        if ((ack = le16_to_cpu(*ptr)) & 0x8000) {
 153                skb_pull(skb, 2);
 154                len += 2;
 155                if ((ack & 0x4000) == 0) {
 156                        if (oth)
 157                                ack ^= 0x2000;
 158                        dn_ack(sk, skb, ack);
 159                }
 160        }
 161
 162        return len;
 163}
 164
 165
 166/**
 167 * dn_check_idf - Check an image data field format is correct.
 168 * @pptr: Pointer to pointer to image data
 169 * @len: Pointer to length of image data
 170 * @max: The maximum allowed length of the data in the image data field
 171 * @follow_on: Check that this many bytes exist beyond the end of the image data
 172 *
 173 * Returns: 0 if ok, -1 on error
 174 */
 175static inline int dn_check_idf(unsigned char **pptr, int *len, unsigned char max, unsigned char follow_on)
 176{
 177        unsigned char *ptr = *pptr;
 178        unsigned char flen = *ptr++;
 179
 180        (*len)--;
 181        if (flen > max)
 182                return -1;
 183        if ((flen + follow_on) > *len)
 184                return -1;
 185
 186        *len -= flen;
 187        *pptr = ptr + flen;
 188        return 0;
 189}
 190
 191/*
 192 * Table of reason codes to pass back to node which sent us a badly
 193 * formed message, plus text messages for the log. A zero entry in
 194 * the reason field means "don't reply" otherwise a disc init is sent with
 195 * the specified reason code.
 196 */
 197static struct {
 198        unsigned short reason;
 199        const char *text;
 200} ci_err_table[] = {
 201 { 0,             "CI: Truncated message" },
 202 { NSP_REASON_ID, "CI: Destination username error" },
 203 { NSP_REASON_ID, "CI: Destination username type" },
 204 { NSP_REASON_US, "CI: Source username error" },
 205 { 0,             "CI: Truncated at menuver" },
 206 { 0,             "CI: Truncated before access or user data" },
 207 { NSP_REASON_IO, "CI: Access data format error" },
 208 { NSP_REASON_IO, "CI: User data format error" }
 209};
 210
 211/*
 212 * This function uses a slightly different lookup method
 213 * to find its sockets, since it searches on object name/number
 214 * rather than port numbers. Various tests are done to ensure that
 215 * the incoming data is in the correct format before it is queued to
 216 * a socket.
 217 */
 218static struct sock *dn_find_listener(struct sk_buff *skb, unsigned short *reason)
 219{
 220        struct dn_skb_cb *cb = DN_SKB_CB(skb);
 221        struct nsp_conn_init_msg *msg = (struct nsp_conn_init_msg *)skb->data;
 222        struct sockaddr_dn dstaddr;
 223        struct sockaddr_dn srcaddr;
 224        unsigned char type = 0;
 225        int dstlen;
 226        int srclen;
 227        unsigned char *ptr;
 228        int len;
 229        int err = 0;
 230        unsigned char menuver;
 231
 232        memset(&dstaddr, 0, sizeof(struct sockaddr_dn));
 233        memset(&srcaddr, 0, sizeof(struct sockaddr_dn));
 234
 235        /*
 236         * 1. Decode & remove message header
 237         */
 238        cb->src_port = msg->srcaddr;
 239        cb->dst_port = msg->dstaddr;
 240        cb->services = msg->services;
 241        cb->info     = msg->info;
 242        cb->segsize  = le16_to_cpu(msg->segsize);
 243
 244        if (!pskb_may_pull(skb, sizeof(*msg)))
 245                goto err_out;
 246
 247        skb_pull(skb, sizeof(*msg));
 248
 249        len = skb->len;
 250        ptr = skb->data;
 251
 252        /*
 253         * 2. Check destination end username format
 254         */
 255        dstlen = dn_username2sockaddr(ptr, len, &dstaddr, &type);
 256        err++;
 257        if (dstlen < 0)
 258                goto err_out;
 259
 260        err++;
 261        if (type > 1)
 262                goto err_out;
 263
 264        len -= dstlen;
 265        ptr += dstlen;
 266
 267        /*
 268         * 3. Check source end username format
 269         */
 270        srclen = dn_username2sockaddr(ptr, len, &srcaddr, &type);
 271        err++;
 272        if (srclen < 0)
 273                goto err_out;
 274
 275        len -= srclen;
 276        ptr += srclen;
 277        err++;
 278        if (len < 1)
 279                goto err_out;
 280
 281        menuver = *ptr;
 282        ptr++;
 283        len--;
 284
 285        /*
 286         * 4. Check that optional data actually exists if menuver says it does
 287         */
 288        err++;
 289        if ((menuver & (DN_MENUVER_ACC | DN_MENUVER_USR)) && (len < 1))
 290                goto err_out;
 291
 292        /*
 293         * 5. Check optional access data format
 294         */
 295        err++;
 296        if (menuver & DN_MENUVER_ACC) {
 297                if (dn_check_idf(&ptr, &len, 39, 1))
 298                        goto err_out;
 299                if (dn_check_idf(&ptr, &len, 39, 1))
 300                        goto err_out;
 301                if (dn_check_idf(&ptr, &len, 39, (menuver & DN_MENUVER_USR) ? 1 : 0))
 302                        goto err_out;
 303        }
 304
 305        /*
 306         * 6. Check optional user data format
 307         */
 308        err++;
 309        if (menuver & DN_MENUVER_USR) {
 310                if (dn_check_idf(&ptr, &len, 16, 0))
 311                        goto err_out;
 312        }
 313
 314        /*
 315         * 7. Look up socket based on destination end username
 316         */
 317        return dn_sklist_find_listener(&dstaddr);
 318err_out:
 319        dn_log_martian(skb, ci_err_table[err].text);
 320        *reason = ci_err_table[err].reason;
 321        return NULL;
 322}
 323
 324
 325static void dn_nsp_conn_init(struct sock *sk, struct sk_buff *skb)
 326{
 327        if (sk_acceptq_is_full(sk)) {
 328                kfree_skb(skb);
 329                return;
 330        }
 331
 332        sk->sk_ack_backlog++;
 333        skb_queue_tail(&sk->sk_receive_queue, skb);
 334        sk->sk_state_change(sk);
 335}
 336
 337static void dn_nsp_conn_conf(struct sock *sk, struct sk_buff *skb)
 338{
 339        struct dn_skb_cb *cb = DN_SKB_CB(skb);
 340        struct dn_scp *scp = DN_SK(sk);
 341        unsigned char *ptr;
 342
 343        if (skb->len < 4)
 344                goto out;
 345
 346        ptr = skb->data;
 347        cb->services = *ptr++;
 348        cb->info = *ptr++;
 349        cb->segsize = le16_to_cpu(*(__le16 *)ptr);
 350
 351        if ((scp->state == DN_CI) || (scp->state == DN_CD)) {
 352                scp->persist = 0;
 353                scp->addrrem = cb->src_port;
 354                sk->sk_state = TCP_ESTABLISHED;
 355                scp->state = DN_RUN;
 356                scp->services_rem = cb->services;
 357                scp->info_rem = cb->info;
 358                scp->segsize_rem = cb->segsize;
 359
 360                if ((scp->services_rem & NSP_FC_MASK) == NSP_FC_NONE)
 361                        scp->max_window = decnet_no_fc_max_cwnd;
 362
 363                if (skb->len > 0) {
 364                        u16 dlen = *skb->data;
 365                        if ((dlen <= 16) && (dlen <= skb->len)) {
 366                                scp->conndata_in.opt_optl = cpu_to_le16(dlen);
 367                                skb_copy_from_linear_data_offset(skb, 1,
 368                                              scp->conndata_in.opt_data, dlen);
 369                        }
 370                }
 371                dn_nsp_send_link(sk, DN_NOCHANGE, 0);
 372                if (!sock_flag(sk, SOCK_DEAD))
 373                        sk->sk_state_change(sk);
 374        }
 375
 376out:
 377        kfree_skb(skb);
 378}
 379
 380static void dn_nsp_conn_ack(struct sock *sk, struct sk_buff *skb)
 381{
 382        struct dn_scp *scp = DN_SK(sk);
 383
 384        if (scp->state == DN_CI) {
 385                scp->state = DN_CD;
 386                scp->persist = 0;
 387        }
 388
 389        kfree_skb(skb);
 390}
 391
 392static void dn_nsp_disc_init(struct sock *sk, struct sk_buff *skb)
 393{
 394        struct dn_scp *scp = DN_SK(sk);
 395        struct dn_skb_cb *cb = DN_SKB_CB(skb);
 396        unsigned short reason;
 397
 398        if (skb->len < 2)
 399                goto out;
 400
 401        reason = le16_to_cpu(*(__le16 *)skb->data);
 402        skb_pull(skb, 2);
 403
 404        scp->discdata_in.opt_status = cpu_to_le16(reason);
 405        scp->discdata_in.opt_optl   = 0;
 406        memset(scp->discdata_in.opt_data, 0, 16);
 407
 408        if (skb->len > 0) {
 409                u16 dlen = *skb->data;
 410                if ((dlen <= 16) && (dlen <= skb->len)) {
 411                        scp->discdata_in.opt_optl = cpu_to_le16(dlen);
 412                        skb_copy_from_linear_data_offset(skb, 1, scp->discdata_in.opt_data, dlen);
 413                }
 414        }
 415
 416        scp->addrrem = cb->src_port;
 417        sk->sk_state = TCP_CLOSE;
 418
 419        switch(scp->state) {
 420                case DN_CI:
 421                case DN_CD:
 422                        scp->state = DN_RJ;
 423                        sk->sk_err = ECONNREFUSED;
 424                        break;
 425                case DN_RUN:
 426                        sk->sk_shutdown |= SHUTDOWN_MASK;
 427                        scp->state = DN_DN;
 428                        break;
 429                case DN_DI:
 430                        scp->state = DN_DIC;
 431                        break;
 432        }
 433
 434        if (!sock_flag(sk, SOCK_DEAD)) {
 435                if (sk->sk_socket->state != SS_UNCONNECTED)
 436                        sk->sk_socket->state = SS_DISCONNECTING;
 437                sk->sk_state_change(sk);
 438        }
 439
 440        /*
 441         * It appears that its possible for remote machines to send disc
 442         * init messages with no port identifier if we are in the CI and
 443         * possibly also the CD state. Obviously we shouldn't reply with
 444         * a message if we don't know what the end point is.
 445         */
 446        if (scp->addrrem) {
 447                dn_nsp_send_disc(sk, NSP_DISCCONF, NSP_REASON_DC, GFP_ATOMIC);
 448        }
 449        scp->persist_fxn = dn_destroy_timer;
 450        scp->persist = dn_nsp_persist(sk);
 451
 452out:
 453        kfree_skb(skb);
 454}
 455
 456/*
 457 * disc_conf messages are also called no_resources or no_link
 458 * messages depending upon the "reason" field.
 459 */
 460static void dn_nsp_disc_conf(struct sock *sk, struct sk_buff *skb)
 461{
 462        struct dn_scp *scp = DN_SK(sk);
 463        unsigned short reason;
 464
 465        if (skb->len != 2)
 466                goto out;
 467
 468        reason = le16_to_cpu(*(__le16 *)skb->data);
 469
 470        sk->sk_state = TCP_CLOSE;
 471
 472        switch(scp->state) {
 473                case DN_CI:
 474                        scp->state = DN_NR;
 475                        break;
 476                case DN_DR:
 477                        if (reason == NSP_REASON_DC)
 478                                scp->state = DN_DRC;
 479                        if (reason == NSP_REASON_NL)
 480                                scp->state = DN_CN;
 481                        break;
 482                case DN_DI:
 483                        scp->state = DN_DIC;
 484                        break;
 485                case DN_RUN:
 486                        sk->sk_shutdown |= SHUTDOWN_MASK;
 487                case DN_CC:
 488                        scp->state = DN_CN;
 489        }
 490
 491        if (!sock_flag(sk, SOCK_DEAD)) {
 492                if (sk->sk_socket->state != SS_UNCONNECTED)
 493                        sk->sk_socket->state = SS_DISCONNECTING;
 494                sk->sk_state_change(sk);
 495        }
 496
 497        scp->persist_fxn = dn_destroy_timer;
 498        scp->persist = dn_nsp_persist(sk);
 499
 500out:
 501        kfree_skb(skb);
 502}
 503
 504static void dn_nsp_linkservice(struct sock *sk, struct sk_buff *skb)
 505{
 506        struct dn_scp *scp = DN_SK(sk);
 507        unsigned short segnum;
 508        unsigned char lsflags;
 509        signed char fcval;
 510        int wake_up = 0;
 511        char *ptr = skb->data;
 512        unsigned char fctype = scp->services_rem & NSP_FC_MASK;
 513
 514        if (skb->len != 4)
 515                goto out;
 516
 517        segnum = le16_to_cpu(*(__le16 *)ptr);
 518        ptr += 2;
 519        lsflags = *(unsigned char *)ptr++;
 520        fcval = *ptr;
 521
 522        /*
 523         * Here we ignore erronous packets which should really
 524         * should cause a connection abort. It is not critical
 525         * for now though.
 526         */
 527        if (lsflags & 0xf8)
 528                goto out;
 529
 530        if (seq_next(scp->numoth_rcv, segnum)) {
 531                seq_add(&scp->numoth_rcv, 1);
 532                switch(lsflags & 0x04) { /* FCVAL INT */
 533                case 0x00: /* Normal Request */
 534                        switch(lsflags & 0x03) { /* FCVAL MOD */
 535                        case 0x00: /* Request count */
 536                                if (fcval < 0) {
 537                                        unsigned char p_fcval = -fcval;
 538                                        if ((scp->flowrem_dat > p_fcval) &&
 539                                            (fctype == NSP_FC_SCMC)) {
 540                                                scp->flowrem_dat -= p_fcval;
 541                                        }
 542                                } else if (fcval > 0) {
 543                                        scp->flowrem_dat += fcval;
 544                                        wake_up = 1;
 545                                }
 546                                break;
 547                        case 0x01: /* Stop outgoing data */
 548                                scp->flowrem_sw = DN_DONTSEND;
 549                                break;
 550                        case 0x02: /* Ok to start again */
 551                                scp->flowrem_sw = DN_SEND;
 552                                dn_nsp_output(sk);
 553                                wake_up = 1;
 554                        }
 555                        break;
 556                case 0x04: /* Interrupt Request */
 557                        if (fcval > 0) {
 558                                scp->flowrem_oth += fcval;
 559                                wake_up = 1;
 560                        }
 561                        break;
 562                }
 563                if (wake_up && !sock_flag(sk, SOCK_DEAD))
 564                        sk->sk_state_change(sk);
 565        }
 566
 567        dn_nsp_send_oth_ack(sk);
 568
 569out:
 570        kfree_skb(skb);
 571}
 572
 573/*
 574 * Copy of sock_queue_rcv_skb (from sock.h) without
 575 * bh_lock_sock() (its already held when this is called) which
 576 * also allows data and other data to be queued to a socket.
 577 */
 578static __inline__ int dn_queue_skb(struct sock *sk, struct sk_buff *skb, int sig, struct sk_buff_head *queue)
 579{
 580        int err;
 581
 582        /* Cast skb->rcvbuf to unsigned... It's pointless, but reduces
 583           number of warnings when compiling with -W --ANK
 584         */
 585        if (atomic_read(&sk->sk_rmem_alloc) + skb->truesize >=
 586            (unsigned)sk->sk_rcvbuf) {
 587                err = -ENOMEM;
 588                goto out;
 589        }
 590
 591        err = sk_filter(sk, skb);
 592        if (err)
 593                goto out;
 594
 595        skb_set_owner_r(skb, sk);
 596        skb_queue_tail(queue, skb);
 597
 598        /* This code only runs from BH or BH protected context.
 599         * Therefore the plain read_lock is ok here. -DaveM
 600         */
 601        read_lock(&sk->sk_callback_lock);
 602        if (!sock_flag(sk, SOCK_DEAD)) {
 603                struct socket *sock = sk->sk_socket;
 604                wake_up_interruptible(sk->sk_sleep);
 605                if (sock && sock->fasync_list &&
 606                    !test_bit(SOCK_ASYNC_WAITDATA, &sock->flags))
 607                        __kill_fasync(sock->fasync_list, sig,
 608                                    (sig == SIGURG) ? POLL_PRI : POLL_IN);
 609        }
 610        read_unlock(&sk->sk_callback_lock);
 611out:
 612        return err;
 613}
 614
 615static void dn_nsp_otherdata(struct sock *sk, struct sk_buff *skb)
 616{
 617        struct dn_scp *scp = DN_SK(sk);
 618        unsigned short segnum;
 619        struct dn_skb_cb *cb = DN_SKB_CB(skb);
 620        int queued = 0;
 621
 622        if (skb->len < 2)
 623                goto out;
 624
 625        cb->segnum = segnum = le16_to_cpu(*(__le16 *)skb->data);
 626        skb_pull(skb, 2);
 627
 628        if (seq_next(scp->numoth_rcv, segnum)) {
 629
 630                if (dn_queue_skb(sk, skb, SIGURG, &scp->other_receive_queue) == 0) {
 631                        seq_add(&scp->numoth_rcv, 1);
 632                        scp->other_report = 0;
 633                        queued = 1;
 634                }
 635        }
 636
 637        dn_nsp_send_oth_ack(sk);
 638out:
 639        if (!queued)
 640                kfree_skb(skb);
 641}
 642
 643static void dn_nsp_data(struct sock *sk, struct sk_buff *skb)
 644{
 645        int queued = 0;
 646        unsigned short segnum;
 647        struct dn_skb_cb *cb = DN_SKB_CB(skb);
 648        struct dn_scp *scp = DN_SK(sk);
 649
 650        if (skb->len < 2)
 651                goto out;
 652
 653        cb->segnum = segnum = le16_to_cpu(*(__le16 *)skb->data);
 654        skb_pull(skb, 2);
 655
 656        if (seq_next(scp->numdat_rcv, segnum)) {
 657                if (dn_queue_skb(sk, skb, SIGIO, &sk->sk_receive_queue) == 0) {
 658                        seq_add(&scp->numdat_rcv, 1);
 659                        queued = 1;
 660                }
 661
 662                if ((scp->flowloc_sw == DN_SEND) && dn_congested(sk)) {
 663                        scp->flowloc_sw = DN_DONTSEND;
 664                        dn_nsp_send_link(sk, DN_DONTSEND, 0);
 665                }
 666        }
 667
 668        dn_nsp_send_data_ack(sk);
 669out:
 670        if (!queued)
 671                kfree_skb(skb);
 672}
 673
 674/*
 675 * If one of our conninit messages is returned, this function
 676 * deals with it. It puts the socket into the NO_COMMUNICATION
 677 * state.
 678 */
 679static void dn_returned_conn_init(struct sock *sk, struct sk_buff *skb)
 680{
 681        struct dn_scp *scp = DN_SK(sk);
 682
 683        if (scp->state == DN_CI) {
 684                scp->state = DN_NC;
 685                sk->sk_state = TCP_CLOSE;
 686                if (!sock_flag(sk, SOCK_DEAD))
 687                        sk->sk_state_change(sk);
 688        }
 689
 690        kfree_skb(skb);
 691}
 692
 693static int dn_nsp_no_socket(struct sk_buff *skb, unsigned short reason)
 694{
 695        struct dn_skb_cb *cb = DN_SKB_CB(skb);
 696        int ret = NET_RX_DROP;
 697
 698        /* Must not reply to returned packets */
 699        if (cb->rt_flags & DN_RT_F_RTS)
 700                goto out;
 701
 702        if ((reason != NSP_REASON_OK) && ((cb->nsp_flags & 0x0c) == 0x08)) {
 703                switch(cb->nsp_flags & 0x70) {
 704                        case 0x10:
 705                        case 0x60: /* (Retransmitted) Connect Init */
 706                                dn_nsp_return_disc(skb, NSP_DISCINIT, reason);
 707                                ret = NET_RX_SUCCESS;
 708                                break;
 709                        case 0x20: /* Connect Confirm */
 710                                dn_nsp_return_disc(skb, NSP_DISCCONF, reason);
 711                                ret = NET_RX_SUCCESS;
 712                                break;
 713                }
 714        }
 715
 716out:
 717        kfree_skb(skb);
 718        return ret;
 719}
 720
 721static int dn_nsp_rx_packet(struct sk_buff *skb)
 722{
 723        struct dn_skb_cb *cb = DN_SKB_CB(skb);
 724        struct sock *sk = NULL;
 725        unsigned char *ptr = (unsigned char *)skb->data;
 726        unsigned short reason = NSP_REASON_NL;
 727
 728        if (!pskb_may_pull(skb, 2))
 729                goto free_out;
 730
 731        skb_reset_transport_header(skb);
 732        cb->nsp_flags = *ptr++;
 733
 734        if (decnet_debug_level & 2)
 735                printk(KERN_DEBUG "dn_nsp_rx: Message type 0x%02x\n", (int)cb->nsp_flags);
 736
 737        if (cb->nsp_flags & 0x83)
 738                goto free_out;
 739
 740        /*
 741         * Filter out conninits and useless packet types
 742         */
 743        if ((cb->nsp_flags & 0x0c) == 0x08) {
 744                switch(cb->nsp_flags & 0x70) {
 745                        case 0x00: /* NOP */
 746                        case 0x70: /* Reserved */
 747                        case 0x50: /* Reserved, Phase II node init */
 748                                goto free_out;
 749                        case 0x10:
 750                        case 0x60:
 751                                if (unlikely(cb->rt_flags & DN_RT_F_RTS))
 752                                        goto free_out;
 753                                sk = dn_find_listener(skb, &reason);
 754                                goto got_it;
 755                }
 756        }
 757
 758        if (!pskb_may_pull(skb, 3))
 759                goto free_out;
 760
 761        /*
 762         * Grab the destination address.
 763         */
 764        cb->dst_port = *(__le16 *)ptr;
 765        cb->src_port = 0;
 766        ptr += 2;
 767
 768        /*
 769         * If not a connack, grab the source address too.
 770         */
 771        if (pskb_may_pull(skb, 5)) {
 772                cb->src_port = *(__le16 *)ptr;
 773                ptr += 2;
 774                skb_pull(skb, 5);
 775        }
 776
 777        /*
 778         * Returned packets...
 779         * Swap src & dst and look up in the normal way.
 780         */
 781        if (unlikely(cb->rt_flags & DN_RT_F_RTS)) {
 782                __le16 tmp = cb->dst_port;
 783                cb->dst_port = cb->src_port;
 784                cb->src_port = tmp;
 785                tmp = cb->dst;
 786                cb->dst = cb->src;
 787                cb->src = tmp;
 788        }
 789
 790        /*
 791         * Find the socket to which this skb is destined.
 792         */
 793        sk = dn_find_by_skb(skb);
 794got_it:
 795        if (sk != NULL) {
 796                struct dn_scp *scp = DN_SK(sk);
 797
 798                /* Reset backoff */
 799                scp->nsp_rxtshift = 0;
 800
 801                /*
 802                 * We linearize everything except data segments here.
 803                 */
 804                if (cb->nsp_flags & ~0x60) {
 805                        if (unlikely(skb_linearize(skb)))
 806                                goto free_out;
 807                }
 808
 809                return sk_receive_skb(sk, skb, 0);
 810        }
 811
 812        return dn_nsp_no_socket(skb, reason);
 813
 814free_out:
 815        kfree_skb(skb);
 816        return NET_RX_DROP;
 817}
 818
 819int dn_nsp_rx(struct sk_buff *skb)
 820{
 821        return NF_HOOK(PF_DECnet, NF_DN_LOCAL_IN, skb, skb->dev, NULL, dn_nsp_rx_packet);
 822}
 823
 824/*
 825 * This is the main receive routine for sockets. It is called
 826 * from the above when the socket is not busy, and also from
 827 * sock_release() when there is a backlog queued up.
 828 */
 829int dn_nsp_backlog_rcv(struct sock *sk, struct sk_buff *skb)
 830{
 831        struct dn_scp *scp = DN_SK(sk);
 832        struct dn_skb_cb *cb = DN_SKB_CB(skb);
 833
 834        if (cb->rt_flags & DN_RT_F_RTS) {
 835                if (cb->nsp_flags == 0x18 || cb->nsp_flags == 0x68)
 836                        dn_returned_conn_init(sk, skb);
 837                else
 838                        kfree_skb(skb);
 839                return NET_RX_SUCCESS;
 840        }
 841
 842        /*
 843         * Control packet.
 844         */
 845        if ((cb->nsp_flags & 0x0c) == 0x08) {
 846                switch(cb->nsp_flags & 0x70) {
 847                        case 0x10:
 848                        case 0x60:
 849                                dn_nsp_conn_init(sk, skb);
 850                                break;
 851                        case 0x20:
 852                                dn_nsp_conn_conf(sk, skb);
 853                                break;
 854                        case 0x30:
 855                                dn_nsp_disc_init(sk, skb);
 856                                break;
 857                        case 0x40:
 858                                dn_nsp_disc_conf(sk, skb);
 859                                break;
 860                }
 861
 862        } else if (cb->nsp_flags == 0x24) {
 863                /*
 864                 * Special for connacks, 'cos they don't have
 865                 * ack data or ack otherdata info.
 866                 */
 867                dn_nsp_conn_ack(sk, skb);
 868        } else {
 869                int other = 1;
 870
 871                /* both data and ack frames can kick a CC socket into RUN */
 872                if ((scp->state == DN_CC) && !sock_flag(sk, SOCK_DEAD)) {
 873                        scp->state = DN_RUN;
 874                        sk->sk_state = TCP_ESTABLISHED;
 875                        sk->sk_state_change(sk);
 876                }
 877
 878                if ((cb->nsp_flags & 0x1c) == 0)
 879                        other = 0;
 880                if (cb->nsp_flags == 0x04)
 881                        other = 0;
 882
 883                /*
 884                 * Read out ack data here, this applies equally
 885                 * to data, other data, link serivce and both
 886                 * ack data and ack otherdata.
 887                 */
 888                dn_process_ack(sk, skb, other);
 889
 890                /*
 891                 * If we've some sort of data here then call a
 892                 * suitable routine for dealing with it, otherwise
 893                 * the packet is an ack and can be discarded.
 894                 */
 895                if ((cb->nsp_flags & 0x0c) == 0) {
 896
 897                        if (scp->state != DN_RUN)
 898                                goto free_out;
 899
 900                        switch(cb->nsp_flags) {
 901                                case 0x10: /* LS */
 902                                        dn_nsp_linkservice(sk, skb);
 903                                        break;
 904                                case 0x30: /* OD */
 905                                        dn_nsp_otherdata(sk, skb);
 906                                        break;
 907                                default:
 908                                        dn_nsp_data(sk, skb);
 909                        }
 910
 911                } else { /* Ack, chuck it out here */
 912free_out:
 913                        kfree_skb(skb);
 914                }
 915        }
 916
 917        return NET_RX_SUCCESS;
 918}
 919
 920