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
 589         /* Cast skb->rcvbuf to unsigned... It's pointless, but reduces
 590            number of warnings when compiling with -W --ANK
 591          */
 592         if (atomic_read(&sk->sk_rmem_alloc) + skb->truesize >=
 593             (unsigned int)sk->sk_rcvbuf) {
 594                 err = -ENOMEM;
 595                 goto out;
 596         }
 597
 598         err = sk_filter(sk, skb);
 599         if (err)
 600                 goto out;
 601
 602         skb_set_owner_r(skb, sk);
 603         skb_queue_tail(queue, skb);
 604
 605         if (!sock_flag(sk, SOCK_DEAD))
 606                 sk->sk_data_ready(sk);
 607 out:
 608         return err;
 609 }
 610
 611 static void dn_nsp_otherdata(struct sock *sk, struct sk_buff *skb)
 612 {
 613         struct dn_scp *scp = DN_SK(sk);
 614         unsigned short segnum;
 615         struct dn_skb_cb *cb = DN_SKB_CB(skb);
 616         int queued = 0;
 617
 618         if (skb->len < 2)
 619                 goto out;
 620
 621         cb->segnum = segnum = le16_to_cpu(*(__le16 *)skb->data);
 622         skb_pull(skb, 2);
 623
 624         if (seq_next(scp->numoth_rcv, segnum)) {
 625
 626                 if (dn_queue_skb(sk, skb, SIGURG, &scp->other_receive_queue) == 0) {
 627                         seq_add(&scp->numoth_rcv, 1);
 628                         scp->other_report = 0;
 629                         queued = 1;
 630                 }
 631         }
 632
 633         dn_nsp_send_oth_ack(sk);
 634 out:
 635         if (!queued)
 636                 kfree_skb(skb);
 637 }
 638
 639 static void dn_nsp_data(struct sock *sk, struct sk_buff *skb)
 640 {
 641         int queued = 0;
 642         unsigned short segnum;
 643         struct dn_skb_cb *cb = DN_SKB_CB(skb);
 644         struct dn_scp *scp = DN_SK(sk);
 645
 646         if (skb->len < 2)
 647                 goto out;
 648
 649         cb->segnum = segnum = le16_to_cpu(*(__le16 *)skb->data);
 650         skb_pull(skb, 2);
 651
 652         if (seq_next(scp->numdat_rcv, segnum)) {
 653                 if (dn_queue_skb(sk, skb, SIGIO, &sk->sk_receive_queue) == 0) {
 654                         seq_add(&scp->numdat_rcv, 1);
 655                         queued = 1;
 656                 }
 657
 658                 if ((scp->flowloc_sw == DN_SEND) && dn_congested(sk)) {
 659                         scp->flowloc_sw = DN_DONTSEND;
 660                         dn_nsp_send_link(sk, DN_DONTSEND, 0);
 661                 }
 662         }
 663
 664         dn_nsp_send_data_ack(sk);
 665 out:
 666         if (!queued)
 667                 kfree_skb(skb);
 668 }
 669
 670 /*
 671  * If one of our conninit messages is returned, this function
 672  * deals with it. It puts the socket into the NO_COMMUNICATION
 673  * state.
 674  */
 675 static void dn_returned_conn_init(struct sock *sk, struct sk_buff *skb)
 676 {
 677         struct dn_scp *scp = DN_SK(sk);
 678
 679         if (scp->state == DN_CI) {
 680                 scp->state = DN_NC;
 681                 sk->sk_state = TCP_CLOSE;
 682                 if (!sock_flag(sk, SOCK_DEAD))
 683                         sk->sk_state_change(sk);
 684         }
 685
 686         kfree_skb(skb);
 687 }
 688
 689 static int dn_nsp_no_socket(struct sk_buff *skb, unsigned short reason)
 690 {
 691         struct dn_skb_cb *cb = DN_SKB_CB(skb);
 692         int ret = NET_RX_DROP;
 693
 694         /* Must not reply to returned packets */
 695         if (cb->rt_flags & DN_RT_F_RTS)
 696                 goto out;
 697
 698         if ((reason != NSP_REASON_OK) && ((cb->nsp_flags & 0x0c) == 0x08)) {
 699                 switch (cb->nsp_flags & 0x70) {
 700                 case 0x10:
 701                 case 0x60: /* (Retransmitted) Connect Init */
 702                         dn_nsp_return_disc(skb, NSP_DISCINIT, reason);
 703                         ret = NET_RX_SUCCESS;
 704                         break;
 705                 case 0x20: /* Connect Confirm */
 706                         dn_nsp_return_disc(skb, NSP_DISCCONF, reason);
 707                         ret = NET_RX_SUCCESS;
 708                         break;
 709                 }
 710         }
 711
 712 out:
 713         kfree_skb(skb);
 714         return ret;
 715 }
 716
 717 static int dn_nsp_rx_packet(struct net *net, struct sock *sk2,
 718                             struct sk_buff *skb)
 719 {
 720         struct dn_skb_cb *cb = DN_SKB_CB(skb);
 721         struct sock *sk = NULL;
 722         unsigned char *ptr = (unsigned char *)skb->data;
 723         unsigned short reason = NSP_REASON_NL;
 724
 725         if (!pskb_may_pull(skb, 2))
 726                 goto free_out;
 727
 728         skb_reset_transport_header(skb);
 729         cb->nsp_flags = *ptr++;
 730
 731         if (decnet_debug_level & 2)
 732                 printk(KERN_DEBUG "dn_nsp_rx: Message type 0x%02x\n", (int)cb->nsp_flags);
 733
 734         if (cb->nsp_flags & 0x83)
 735                 goto free_out;
 736
 737         /*
 738          * Filter out conninits and useless packet types
 739          */
 740         if ((cb->nsp_flags & 0x0c) == 0x08) {
 741                 switch (cb->nsp_flags & 0x70) {
 742                 case 0x00: /* NOP */
 743                 case 0x70: /* Reserved */
 744                 case 0x50: /* Reserved, Phase II node init */
 745                         goto free_out;
 746                 case 0x10:
 747                 case 0x60:
 748                         if (unlikely(cb->rt_flags & DN_RT_F_RTS))
 749                                 goto free_out;
 750                         sk = dn_find_listener(skb, &reason);
 751                         goto got_it;
 752                 }
 753         }
 754
 755         if (!pskb_may_pull(skb, 3))
 756                 goto free_out;
 757
 758         /*
 759          * Grab the destination address.
 760          */
 761         cb->dst_port = *(__le16 *)ptr;
 762         cb->src_port = 0;
 763         ptr += 2;
 764
 765         /*
 766          * If not a connack, grab the source address too.
 767          */
 768         if (pskb_may_pull(skb, 5)) {
 769                 cb->src_port = *(__le16 *)ptr;
 770                 ptr += 2;
 771                 skb_pull(skb, 5);
 772         }
 773
 774         /*
 775          * Returned packets...
 776          * Swap src & dst and look up in the normal way.
 777          */
 778         if (unlikely(cb->rt_flags & DN_RT_F_RTS)) {
 779                 swap(cb->dst_port, cb->src_port);
 780                 swap(cb->dst, cb->src);
 781         }
 782
 783         /*
 784          * Find the socket to which this skb is destined.
 785          */
 786         sk = dn_find_by_skb(skb);
 787 got_it:
 788         if (sk != NULL) {
 789                 struct dn_scp *scp = DN_SK(sk);
 790
 791                 /* Reset backoff */
 792                 scp->nsp_rxtshift = 0;
 793
 794                 /*
 795                  * We linearize everything except data segments here.
 796                  */
 797                 if (cb->nsp_flags & ~0x60) {
 798                         if (unlikely(skb_linearize(skb)))
 799                                 goto free_out;
 800                 }
 801
 802                 return sk_receive_skb(sk, skb, 0);
 803         }
 804
 805         return dn_nsp_no_socket(skb, reason);
 806
 807 free_out:
 808         kfree_skb(skb);
 809         return NET_RX_DROP;
 810 }
 811
 812 int dn_nsp_rx(struct sk_buff *skb)
 813 {
 814         return NF_HOOK(NFPROTO_DECNET, NF_DN_LOCAL_IN,
 815                        &init_net, NULL, skb, skb->dev, NULL,
 816                        dn_nsp_rx_packet);
 817 }
 818
 819 /*
 820  * This is the main receive routine for sockets. It is called
 821  * from the above when the socket is not busy, and also from
 822  * sock_release() when there is a backlog queued up.
 823  */
 824 int dn_nsp_backlog_rcv(struct sock *sk, struct sk_buff *skb)
 825 {
 826         struct dn_scp *scp = DN_SK(sk);
 827         struct dn_skb_cb *cb = DN_SKB_CB(skb);
 828
 829         if (cb->rt_flags & DN_RT_F_RTS) {
 830                 if (cb->nsp_flags == 0x18 || cb->nsp_flags == 0x68)
 831                         dn_returned_conn_init(sk, skb);
 832                 else
 833                         kfree_skb(skb);
 834                 return NET_RX_SUCCESS;
 835         }
 836
 837         /*
 838          * Control packet.
 839          */
 840         if ((cb->nsp_flags & 0x0c) == 0x08) {
 841                 switch (cb->nsp_flags & 0x70) {
 842                 case 0x10:
 843                 case 0x60:
 844                         dn_nsp_conn_init(sk, skb);
 845                         break;
 846                 case 0x20:
 847                         dn_nsp_conn_conf(sk, skb);
 848                         break;
 849                 case 0x30:
 850                         dn_nsp_disc_init(sk, skb);
 851                         break;
 852                 case 0x40:
 853                         dn_nsp_disc_conf(sk, skb);
 854                         break;
 855                 }
 856
 857         } else if (cb->nsp_flags == 0x24) {
 858                 /*
 859                  * Special for connacks, 'cos they don't have
 860                  * ack data or ack otherdata info.
 861                  */
 862                 dn_nsp_conn_ack(sk, skb);
 863         } else {
 864                 int other = 1;
 865
 866                 /* both data and ack frames can kick a CC socket into RUN */
 867                 if ((scp->state == DN_CC) && !sock_flag(sk, SOCK_DEAD)) {
 868                         scp->state = DN_RUN;
 869                         sk->sk_state = TCP_ESTABLISHED;
 870                         sk->sk_state_change(sk);
 871                 }
 872
 873                 if ((cb->nsp_flags & 0x1c) == 0)
 874                         other = 0;
 875                 if (cb->nsp_flags == 0x04)
 876                         other = 0;
 877
 878                 /*
 879                  * Read out ack data here, this applies equally
 880                  * to data, other data, link serivce and both
 881                  * ack data and ack otherdata.
 882                  */
 883                 dn_process_ack(sk, skb, other);
 884
 885                 /*
 886                  * If we've some sort of data here then call a
 887                  * suitable routine for dealing with it, otherwise
 888                  * the packet is an ack and can be discarded.
 889                  */
 890                 if ((cb->nsp_flags & 0x0c) == 0) {
 891
 892                         if (scp->state != DN_RUN)
 893                                 goto free_out;
 894
 895                         switch (cb->nsp_flags) {
 896                         case 0x10: /* LS */
 897                                 dn_nsp_linkservice(sk, skb);
 898                                 break;
 899                         case 0x30: /* OD */
 900                                 dn_nsp_otherdata(sk, skb);
 901                                 break;
 902                         default:
 903                                 dn_nsp_data(sk, skb);
 904                         }
 905
 906                 } else { /* Ack, chuck it out here */
 907 free_out:
 908                         kfree_skb(skb);
 909                 }
 910         }
 911
 912         return NET_RX_SUCCESS;
 913 }
 914