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/config.h>
  49 #include <linux/errno.h>
  50 #include <linux/types.h>
  51 #include <linux/socket.h>
  52 #include <linux/in.h>
  53 #include <linux/kernel.h>
  54 #include <linux/sched.h>
  55 #include <linux/timer.h>
  56 #include <linux/string.h>
  57 #include <linux/sockios.h>
  58 #include <linux/net.h>
  59 #include <linux/netdevice.h>
  60 #include <linux/inet.h>
  61 #include <linux/route.h>
  62 #include <net/sock.h>
  63 #include <net/tcp_states.h>
  64 #include <asm/system.h>
  65 #include <linux/fcntl.h>
  66 #include <linux/mm.h>
  67 #include <linux/termios.h>
  68 #include <linux/interrupt.h>
  69 #include <linux/proc_fs.h>
  70 #include <linux/stat.h>
  71 #include <linux/init.h>
  72 #include <linux/poll.h>
  73 #include <linux/netfilter_decnet.h>
  74 #include <net/neighbour.h>
  75 #include <net/dst.h>
  76 #include <net/dn.h>
  77 #include <net/dn_nsp.h>
  78 #include <net/dn_dev.h>
  79 #include <net/dn_route.h>
  80
  81 extern int decnet_log_martians;
  82
  83 static void dn_log_martian(struct sk_buff *skb, const char *msg)
  84 {
  85         if (decnet_log_martians && net_ratelimit()) {
  86                 char *devname = skb->dev ? skb->dev->name : "???";
  87                 struct dn_skb_cb *cb = DN_SKB_CB(skb);
  88                 printk(KERN_INFO "DECnet: Martian packet (%s) dev=%s src=0x%04hx dst=0x%04hx srcport=0x%04hx dstport=0x%04hx\n", msg, devname, dn_ntohs(cb->src), dn_ntohs(cb->dst), dn_ntohs(cb->src_port), dn_ntohs(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  */
  97 static 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  */
 129 static 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 = dn_ntohs(*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 = dn_ntohs(*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  */
 175 static 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  */
 197 static 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  */
 218 static 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  = dn_ntohs(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);
 318 err_out:
 319         dn_log_martian(skb, ci_err_table[err].text);
 320         *reason = ci_err_table[err].reason;
 321         return NULL;
 322 }
 323
 324
 325 static 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
 337 static 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 = dn_ntohs(*(__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                         unsigned char dlen = *skb->data;
 365                         if ((dlen <= 16) && (dlen <= skb->len)) {
 366                                 scp->conndata_in.opt_optl = dn_htons((__u16)dlen);
 367                                 memcpy(scp->conndata_in.opt_data, skb->data + 1, dlen);
 368                         }
 369                 }
 370                 dn_nsp_send_link(sk, DN_NOCHANGE, 0);
 371                 if (!sock_flag(sk, SOCK_DEAD))
 372                         sk->sk_state_change(sk);
 373         }
 374
 375 out:
 376         kfree_skb(skb);
 377 }
 378
 379 static void dn_nsp_conn_ack(struct sock *sk, struct sk_buff *skb)
 380 {
 381         struct dn_scp *scp = DN_SK(sk);
 382
 383         if (scp->state == DN_CI) {
 384                 scp->state = DN_CD;
 385                 scp->persist = 0;
 386         }
 387
 388         kfree_skb(skb);
 389 }
 390
 391 static void dn_nsp_disc_init(struct sock *sk, struct sk_buff *skb)
 392 {
 393         struct dn_scp *scp = DN_SK(sk);
 394         struct dn_skb_cb *cb = DN_SKB_CB(skb);
 395         unsigned short reason;
 396
 397         if (skb->len < 2)
 398                 goto out;
 399
 400         reason = dn_ntohs(*(__le16 *)skb->data);
 401         skb_pull(skb, 2);
 402
 403         scp->discdata_in.opt_status = dn_htons(reason);
 404         scp->discdata_in.opt_optl   = 0;
 405         memset(scp->discdata_in.opt_data, 0, 16);
 406
 407         if (skb->len > 0) {
 408                 unsigned char dlen = *skb->data;
 409                 if ((dlen <= 16) && (dlen <= skb->len)) {
 410                         scp->discdata_in.opt_optl = dn_htons((__u16)dlen);
 411                         memcpy(scp->discdata_in.opt_data, skb->data + 1, dlen);
 412                 }
 413         }
 414
 415         scp->addrrem = cb->src_port;
 416         sk->sk_state = TCP_CLOSE;
 417
 418         switch(scp->state) {
 419                 case DN_CI:
 420                 case DN_CD:
 421                         scp->state = DN_RJ;
 422                         sk->sk_err = ECONNREFUSED;
 423                         break;
 424                 case DN_RUN:
 425                         sk->sk_shutdown |= SHUTDOWN_MASK;
 426                         scp->state = DN_DN;
 427                         break;
 428                 case DN_DI:
 429                         scp->state = DN_DIC;
 430                         break;
 431         }
 432
 433         if (!sock_flag(sk, SOCK_DEAD)) {
 434                 if (sk->sk_socket->state != SS_UNCONNECTED)
 435                         sk->sk_socket->state = SS_DISCONNECTING;
 436                 sk->sk_state_change(sk);
 437         }
 438
 439         /*
 440          * It appears that its possible for remote machines to send disc
 441          * init messages with no port identifier if we are in the CI and
 442          * possibly also the CD state. Obviously we shouldn't reply with
 443          * a message if we don't know what the end point is.
 444          */
 445         if (scp->addrrem) {
 446                 dn_nsp_send_disc(sk, NSP_DISCCONF, NSP_REASON_DC, GFP_ATOMIC);
 447         }
 448         scp->persist_fxn = dn_destroy_timer;
 449         scp->persist = dn_nsp_persist(sk);
 450
 451 out:
 452         kfree_skb(skb);
 453 }
 454
 455 /*
 456  * disc_conf messages are also called no_resources or no_link
 457  * messages depending upon the "reason" field.
 458  */
 459 static void dn_nsp_disc_conf(struct sock *sk, struct sk_buff *skb)
 460 {
 461         struct dn_scp *scp = DN_SK(sk);
 462         unsigned short reason;
 463
 464         if (skb->len != 2)
 465                 goto out;
 466
 467         reason = dn_ntohs(*(__le16 *)skb->data);
 468
 469         sk->sk_state = TCP_CLOSE;
 470
 471         switch(scp->state) {
 472                 case DN_CI:
 473                         scp->state = DN_NR;
 474                         break;
 475                 case DN_DR:
 476                         if (reason == NSP_REASON_DC)
 477                                 scp->state = DN_DRC;
 478                         if (reason == NSP_REASON_NL)
 479                                 scp->state = DN_CN;
 480                         break;
 481                 case DN_DI:
 482                         scp->state = DN_DIC;
 483                         break;
 484                 case DN_RUN:
 485                         sk->sk_shutdown |= SHUTDOWN_MASK;
 486                 case DN_CC:
 487                         scp->state = DN_CN;
 488         }
 489
 490         if (!sock_flag(sk, SOCK_DEAD)) {
 491                 if (sk->sk_socket->state != SS_UNCONNECTED)
 492                         sk->sk_socket->state = SS_DISCONNECTING;
 493                 sk->sk_state_change(sk);
 494         }
 495
 496         scp->persist_fxn = dn_destroy_timer;
 497         scp->persist = dn_nsp_persist(sk);
 498
 499 out:
 500         kfree_skb(skb);
 501 }
 502
 503 static void dn_nsp_linkservice(struct sock *sk, struct sk_buff *skb)
 504 {
 505         struct dn_scp *scp = DN_SK(sk);
 506         unsigned short segnum;
 507         unsigned char lsflags;
 508         signed char fcval;
 509         int wake_up = 0;
 510         char *ptr = skb->data;
 511         unsigned char fctype = scp->services_rem & NSP_FC_MASK;
 512
 513         if (skb->len != 4)
 514                 goto out;
 515
 516         segnum = dn_ntohs(*(__le16 *)ptr);
 517         ptr += 2;
 518         lsflags = *(unsigned char *)ptr++;
 519         fcval = *ptr;
 520
 521         /*
 522          * Here we ignore erronous packets which should really
 523          * should cause a connection abort. It is not critical
 524          * for now though.
 525          */
 526         if (lsflags & 0xf8)
 527                 goto out;
 528
 529         if (seq_next(scp->numoth_rcv, segnum)) {
 530                 seq_add(&scp->numoth_rcv, 1);
 531                 switch(lsflags & 0x04) { /* FCVAL INT */
 532                 case 0x00: /* Normal Request */
 533                         switch(lsflags & 0x03) { /* FCVAL MOD */
 534                         case 0x00: /* Request count */
 535                                 if (fcval < 0) {
 536                                         unsigned char p_fcval = -fcval;
 537                                         if ((scp->flowrem_dat > p_fcval) &&
 538                                             (fctype == NSP_FC_SCMC)) {
 539                                                 scp->flowrem_dat -= p_fcval;
 540                                         }
 541                                 } else if (fcval > 0) {
 542                                         scp->flowrem_dat += fcval;
 543                                         wake_up = 1;
 544                                 }
 545                                 break;
 546                         case 0x01: /* Stop outgoing data */
 547                                 scp->flowrem_sw = DN_DONTSEND;
 548                                 break;
 549                         case 0x02: /* Ok to start again */
 550                                 scp->flowrem_sw = DN_SEND;
 551                                 dn_nsp_output(sk);
 552                                 wake_up = 1;
 553                         }
 554                         break;
 555                 case 0x04: /* Interrupt Request */
 556                         if (fcval > 0) {
 557                                 scp->flowrem_oth += fcval;
 558                                 wake_up = 1;
 559                         }
 560                         break;
 561                 }
 562                 if (wake_up && !sock_flag(sk, SOCK_DEAD))
 563                         sk->sk_state_change(sk);
 564         }
 565
 566         dn_nsp_send_oth_ack(sk);
 567
 568 out:
 569         kfree_skb(skb);
 570 }
 571
 572 /*
 573  * Copy of sock_queue_rcv_skb (from sock.h) without
 574  * bh_lock_sock() (its already held when this is called) which
 575  * also allows data and other data to be queued to a socket.
 576  */
 577 static __inline__ int dn_queue_skb(struct sock *sk, struct sk_buff *skb, int sig, struct sk_buff_head *queue)
 578 {
 579         int err;
 580
 581         /* Cast skb->rcvbuf to unsigned... It's pointless, but reduces
 582            number of warnings when compiling with -W --ANK
 583          */
 584         if (atomic_read(&sk->sk_rmem_alloc) + skb->truesize >=
 585             (unsigned)sk->sk_rcvbuf) {
 586                 err = -ENOMEM;
 587                 goto out;
 588         }
 589
 590         err = sk_filter(sk, skb, 0);
 591         if (err)
 592                 goto out;
 593
 594         skb_set_owner_r(skb, sk);
 595         skb_queue_tail(queue, skb);
 596
 597         /* This code only runs from BH or BH protected context.
 598          * Therefore the plain read_lock is ok here. -DaveM
 599          */
 600         read_lock(&sk->sk_callback_lock);
 601         if (!sock_flag(sk, SOCK_DEAD)) {
 602                 struct socket *sock = sk->sk_socket;
 603                 wake_up_interruptible(sk->sk_sleep);
 604                 if (sock && sock->fasync_list &&
 605                     !test_bit(SOCK_ASYNC_WAITDATA, &sock->flags))
 606                         __kill_fasync(sock->fasync_list, sig,
 607                                     (sig == SIGURG) ? POLL_PRI : POLL_IN);
 608         }
 609         read_unlock(&sk->sk_callback_lock);
 610 out:
 611         return err;
 612 }
 613
 614 static void dn_nsp_otherdata(struct sock *sk, struct sk_buff *skb)
 615 {
 616         struct dn_scp *scp = DN_SK(sk);
 617         unsigned short segnum;
 618         struct dn_skb_cb *cb = DN_SKB_CB(skb);
 619         int queued = 0;
 620
 621         if (skb->len < 2)
 622                 goto out;
 623
 624         cb->segnum = segnum = dn_ntohs(*(__le16 *)skb->data);
 625         skb_pull(skb, 2);
 626
 627         if (seq_next(scp->numoth_rcv, segnum)) {
 628
 629                 if (dn_queue_skb(sk, skb, SIGURG, &scp->other_receive_queue) == 0) {
 630                         seq_add(&scp->numoth_rcv, 1);
 631                         scp->other_report = 0;
 632                         queued = 1;
 633                 }
 634         }
 635
 636         dn_nsp_send_oth_ack(sk);
 637 out:
 638         if (!queued)
 639                 kfree_skb(skb);
 640 }
 641
 642 static void dn_nsp_data(struct sock *sk, struct sk_buff *skb)
 643 {
 644         int queued = 0;
 645         unsigned short segnum;
 646         struct dn_skb_cb *cb = DN_SKB_CB(skb);
 647         struct dn_scp *scp = DN_SK(sk);
 648
 649         if (skb->len < 2)
 650                 goto out;
 651
 652         cb->segnum = segnum = dn_ntohs(*(__le16 *)skb->data);
 653         skb_pull(skb, 2);
 654
 655         if (seq_next(scp->numdat_rcv, segnum)) {
 656                 if (dn_queue_skb(sk, skb, SIGIO, &sk->sk_receive_queue) == 0) {
 657                         seq_add(&scp->numdat_rcv, 1);
 658                         queued = 1;
 659                 }
 660
 661                 if ((scp->flowloc_sw == DN_SEND) && dn_congested(sk)) {
 662                         scp->flowloc_sw = DN_DONTSEND;
 663                         dn_nsp_send_link(sk, DN_DONTSEND, 0);
 664                 }
 665         }
 666
 667         dn_nsp_send_data_ack(sk);
 668 out:
 669         if (!queued)
 670                 kfree_skb(skb);
 671 }
 672
 673 /*
 674  * If one of our conninit messages is returned, this function
 675  * deals with it. It puts the socket into the NO_COMMUNICATION
 676  * state.
 677  */
 678 static void dn_returned_conn_init(struct sock *sk, struct sk_buff *skb)
 679 {
 680         struct dn_scp *scp = DN_SK(sk);
 681
 682         if (scp->state == DN_CI) {
 683                 scp->state = DN_NC;
 684                 sk->sk_state = TCP_CLOSE;
 685                 if (!sock_flag(sk, SOCK_DEAD))
 686                         sk->sk_state_change(sk);
 687         }
 688
 689         kfree_skb(skb);
 690 }
 691
 692 static int dn_nsp_no_socket(struct sk_buff *skb, unsigned short reason)
 693 {
 694         struct dn_skb_cb *cb = DN_SKB_CB(skb);
 695         int ret = NET_RX_DROP;
 696
 697         /* Must not reply to returned packets */
 698         if (cb->rt_flags & DN_RT_F_RTS)
 699                 goto out;
 700
 701         if ((reason != NSP_REASON_OK) && ((cb->nsp_flags & 0x0c) == 0x08)) {
 702                 switch(cb->nsp_flags & 0x70) {
 703                         case 0x10:
 704                         case 0x60: /* (Retransmitted) Connect Init */
 705                                 dn_nsp_return_disc(skb, NSP_DISCINIT, reason);
 706                                 ret = NET_RX_SUCCESS;
 707                                 break;
 708                         case 0x20: /* Connect Confirm */
 709                                 dn_nsp_return_disc(skb, NSP_DISCCONF, reason);
 710                                 ret = NET_RX_SUCCESS;
 711                                 break;
 712                 }
 713         }
 714
 715 out:
 716         kfree_skb(skb);
 717         return ret;
 718 }
 719
 720 static int dn_nsp_rx_packet(struct sk_buff *skb)
 721 {
 722         struct dn_skb_cb *cb = DN_SKB_CB(skb);
 723         struct sock *sk = NULL;
 724         unsigned char *ptr = (unsigned char *)skb->data;
 725         unsigned short reason = NSP_REASON_NL;
 726
 727         if (!pskb_may_pull(skb, 2))
 728                 goto free_out;
 729
 730         skb->h.raw    = skb->data;
 731         cb->nsp_flags = *ptr++;
 732
 733         if (decnet_debug_level & 2)
 734                 printk(KERN_DEBUG "dn_nsp_rx: Message type 0x%02x\n", (int)cb->nsp_flags);
 735
 736         if (cb->nsp_flags & 0x83)
 737                 goto free_out;
 738
 739         /*
 740          * Filter out conninits and useless packet types
 741          */
 742         if ((cb->nsp_flags & 0x0c) == 0x08) {
 743                 switch(cb->nsp_flags & 0x70) {
 744                         case 0x00: /* NOP */
 745                         case 0x70: /* Reserved */
 746                         case 0x50: /* Reserved, Phase II node init */
 747                                 goto free_out;
 748                         case 0x10:
 749                         case 0x60:
 750                                 if (unlikely(cb->rt_flags & DN_RT_F_RTS))
 751                                         goto free_out;
 752                                 sk = dn_find_listener(skb, &reason);
 753                                 goto got_it;
 754                 }
 755         }
 756
 757         if (!pskb_may_pull(skb, 3))
 758                 goto free_out;
 759
 760         /*
 761          * Grab the destination address.
 762          */
 763         cb->dst_port = *(__le16 *)ptr;
 764         cb->src_port = 0;
 765         ptr += 2;
 766
 767         /*
 768          * If not a connack, grab the source address too.
 769          */
 770         if (pskb_may_pull(skb, 5)) {
 771                 cb->src_port = *(__le16 *)ptr;
 772                 ptr += 2;
 773                 skb_pull(skb, 5);
 774         }
 775
 776         /*
 777          * Returned packets...
 778          * Swap src & dst and look up in the normal way.
 779          */
 780         if (unlikely(cb->rt_flags & DN_RT_F_RTS)) {
 781                 __le16 tmp = cb->dst_port;
 782                 cb->dst_port = cb->src_port;
 783                 cb->src_port = tmp;
 784                 tmp = cb->dst;
 785                 cb->dst = cb->src;
 786                 cb->src = tmp;
 787         }
 788
 789         /*
 790          * Find the socket to which this skb is destined.
 791          */
 792         sk = dn_find_by_skb(skb);
 793 got_it:
 794         if (sk != NULL) {
 795                 struct dn_scp *scp = DN_SK(sk);
 796
 797                 /* Reset backoff */
 798                 scp->nsp_rxtshift = 0;
 799
 800                 /*
 801                  * We linearize everything except data segments here.
 802                  */
 803                 if (cb->nsp_flags & ~0x60) {
 804                         if (unlikely(skb_is_nonlinear(skb)) &&
 805                             skb_linearize(skb, GFP_ATOMIC) != 0)
 806                                 goto free_out;
 807                 }
 808
 809                 return sk_receive_skb(sk, skb);
 810         }
 811
 812         return dn_nsp_no_socket(skb, reason);
 813
 814 free_out:
 815         kfree_skb(skb);
 816         return NET_RX_DROP;
 817 }
 818
 819 int 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  */
 829 int 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 */
 912 free_out:
 913                         kfree_skb(skb);
 914                 }
 915         }
 916
 917         return NET_RX_SUCCESS;
 918 }
 919