net/decnet/dn_nsp_in.c

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