1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1989, 1993, 1994 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the University nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 * 31 * @(#)slcompress.c 8.2 (Berkeley) 4/16/94 32 */ 33 34 /* 35 * Routines to compress and uncompess tcp packets (for transmission 36 * over low speed serial lines. 37 * 38 * Van Jacobson (van@helios.ee.lbl.gov), Dec 31, 1989: 39 * - Initial distribution. 40 * 41 * $FreeBSD$ 42 */ 43 44 #include <sys/param.h> 45 #include <netinet/in_systm.h> 46 #include <netinet/in.h> 47 #include <netinet/tcp.h> 48 #include <netinet/ip.h> 49 #include <sys/socket.h> 50 #include <sys/un.h> 51 52 #include <stdarg.h> 53 #include <stdio.h> 54 #include <string.h> 55 #include <termios.h> 56 57 #include "layer.h" 58 #include "defs.h" 59 #include "command.h" 60 #include "mbuf.h" 61 #include "log.h" 62 #include "slcompress.h" 63 #include "descriptor.h" 64 #include "prompt.h" 65 #include "timer.h" 66 #include "fsm.h" 67 #include "throughput.h" 68 #include "iplist.h" 69 #include "lqr.h" 70 #include "hdlc.h" 71 #include "ncpaddr.h" 72 #include "ipcp.h" 73 #include "filter.h" 74 #include "lcp.h" 75 #include "ccp.h" 76 #include "link.h" 77 #include "mp.h" 78 #ifndef NORADIUS 79 #include "radius.h" 80 #endif 81 #include "ipv6cp.h" 82 #include "ncp.h" 83 #include "bundle.h" 84 85 void 86 sl_compress_init(struct slcompress *comp, int max_state) 87 { 88 register u_int i; 89 register struct cstate *tstate = comp->tstate; 90 91 memset(comp, '\0', sizeof *comp); 92 for (i = max_state; i > 0; --i) { 93 tstate[i].cs_id = i; 94 tstate[i].cs_next = &tstate[i - 1]; 95 } 96 tstate[0].cs_next = &tstate[max_state]; 97 tstate[0].cs_id = 0; 98 comp->last_cs = &tstate[0]; 99 comp->last_recv = 255; 100 comp->last_xmit = 255; 101 comp->flags = SLF_TOSS; 102 } 103 104 105 /* ENCODE encodes a number that is known to be non-zero. ENCODEZ 106 * checks for zero (since zero has to be encoded in the 32-bit, 3 byte 107 * form). 108 */ 109 #define ENCODE(n) { \ 110 if ((u_short)(n) >= 256) { \ 111 *cp++ = 0; \ 112 cp[1] = (n); \ 113 cp[0] = (n) >> 8; \ 114 cp += 2; \ 115 } else { \ 116 *cp++ = (n); \ 117 } \ 118 } 119 #define ENCODEZ(n) { \ 120 if ((u_short)(n) >= 256 || (u_short)(n) == 0) { \ 121 *cp++ = 0; \ 122 cp[1] = (n); \ 123 cp[0] = (n) >> 8; \ 124 cp += 2; \ 125 } else { \ 126 *cp++ = (n); \ 127 } \ 128 } 129 130 #define DECODEL(f) { \ 131 if (*cp == 0) {\ 132 (f) = htonl(ntohl(f) + ((cp[1] << 8) | cp[2])); \ 133 cp += 3; \ 134 } else { \ 135 (f) = htonl(ntohl(f) + (u_int32_t)*cp++); \ 136 } \ 137 } 138 139 #define DECODES(f) { \ 140 if (*cp == 0) {\ 141 (f) = htons(ntohs(f) + ((cp[1] << 8) | cp[2])); \ 142 cp += 3; \ 143 } else { \ 144 (f) = htons(ntohs(f) + (u_int32_t)*cp++); \ 145 } \ 146 } 147 148 #define DECODEU(f) { \ 149 if (*cp == 0) {\ 150 (f) = htons((cp[1] << 8) | cp[2]); \ 151 cp += 3; \ 152 } else { \ 153 (f) = htons((u_int32_t)*cp++); \ 154 } \ 155 } 156 157 158 u_char 159 sl_compress_tcp(struct mbuf * m, 160 struct ip * ip, 161 struct slcompress *comp, 162 struct slstat *slstat, 163 int compress_cid) 164 { 165 register struct cstate *cs = comp->last_cs->cs_next; 166 register u_int hlen = ip->ip_hl; 167 register struct tcphdr *oth; 168 register struct tcphdr *th; 169 register u_int deltaS, deltaA; 170 register u_int changes = 0; 171 u_char new_seq[16]; 172 register u_char *cp = new_seq; 173 174 /* 175 * Bail if this is an IP fragment or if the TCP packet isn't `compressible' 176 * (i.e., ACK isn't set or some other control bit is set). (We assume that 177 * the caller has already made sure the packet is IP proto TCP). 178 */ 179 if ((ip->ip_off & htons(0x3fff)) || m->m_len < 40) { 180 log_Printf(LogDEBUG, "??? 1 ip_off = %x, m_len = %lu\n", 181 ip->ip_off, (unsigned long)m->m_len); 182 log_DumpBp(LogDEBUG, "", m); 183 return (TYPE_IP); 184 } 185 th = (struct tcphdr *) & ((int *) ip)[hlen]; 186 if ((th->th_flags & (TH_SYN | TH_FIN | TH_RST | TH_ACK)) != TH_ACK) { 187 log_Printf(LogDEBUG, "??? 2 th_flags = %x\n", th->th_flags); 188 log_DumpBp(LogDEBUG, "", m); 189 return (TYPE_IP); 190 } 191 192 /* 193 * Packet is compressible -- we're going to send either a COMPRESSED_TCP or 194 * UNCOMPRESSED_TCP packet. Either way we need to locate (or create) the 195 * connection state. Special case the most recently used connection since 196 * it's most likely to be used again & we don't have to do any reordering 197 * if it's used. 198 */ 199 slstat->sls_packets++; 200 if (ip->ip_src.s_addr != cs->cs_ip.ip_src.s_addr || 201 ip->ip_dst.s_addr != cs->cs_ip.ip_dst.s_addr || 202 *(int *) th != ((int *) &cs->cs_ip)[cs->cs_ip.ip_hl]) { 203 204 /* 205 * Wasn't the first -- search for it. 206 * 207 * States are kept in a circularly linked list with last_cs pointing to the 208 * end of the list. The list is kept in lru order by moving a state to 209 * the head of the list whenever it is referenced. Since the list is 210 * short and, empirically, the connection we want is almost always near 211 * the front, we locate states via linear search. If we don't find a 212 * state for the datagram, the oldest state is (re-)used. 213 */ 214 register struct cstate *lcs; 215 register struct cstate *lastcs = comp->last_cs; 216 217 do { 218 lcs = cs; 219 cs = cs->cs_next; 220 slstat->sls_searches++; 221 if (ip->ip_src.s_addr == cs->cs_ip.ip_src.s_addr 222 && ip->ip_dst.s_addr == cs->cs_ip.ip_dst.s_addr 223 && *(int *) th == ((int *) &cs->cs_ip)[cs->cs_ip.ip_hl]) 224 goto found; 225 } while (cs != lastcs); 226 227 /* 228 * Didn't find it -- re-use oldest cstate. Send an uncompressed packet 229 * that tells the other side what connection number we're using for this 230 * conversation. Note that since the state list is circular, the oldest 231 * state points to the newest and we only need to set last_cs to update 232 * the lru linkage. 233 */ 234 slstat->sls_misses++; 235 comp->last_cs = lcs; 236 #define THOFFSET(th) (th->th_off) 237 hlen += th->th_off; 238 hlen <<= 2; 239 if (hlen > m->m_len) 240 return (TYPE_IP); 241 goto uncompressed; 242 243 found: 244 245 /* 246 * Found it -- move to the front on the connection list. 247 */ 248 if (cs == lastcs) 249 comp->last_cs = lcs; 250 else { 251 lcs->cs_next = cs->cs_next; 252 cs->cs_next = lastcs->cs_next; 253 lastcs->cs_next = cs; 254 } 255 } 256 257 /* 258 * Make sure that only what we expect to change changed. The first line of 259 * the `if' checks the IP protocol version, header length & type of 260 * service. The 2nd line checks the "Don't fragment" bit. The 3rd line 261 * checks the time-to-live and protocol (the protocol check is unnecessary 262 * but costless). The 4th line checks the TCP header length. The 5th line 263 * checks IP options, if any. The 6th line checks TCP options, if any. If 264 * any of these things are different between the previous & current 265 * datagram, we send the current datagram `uncompressed'. 266 */ 267 oth = (struct tcphdr *) & ((int *) &cs->cs_ip)[hlen]; 268 deltaS = hlen; 269 hlen += th->th_off; 270 hlen <<= 2; 271 if (hlen > m->m_len) 272 return (TYPE_IP); 273 274 if (((u_short *) ip)[0] != ((u_short *) & cs->cs_ip)[0] || 275 ((u_short *) ip)[3] != ((u_short *) & cs->cs_ip)[3] || 276 ((u_short *) ip)[4] != ((u_short *) & cs->cs_ip)[4] || 277 THOFFSET(th) != THOFFSET(oth) || 278 (deltaS > 5 && 279 memcmp(ip + 1, &cs->cs_ip + 1, (deltaS - 5) << 2)) || 280 (THOFFSET(th) > 5 && 281 memcmp(th + 1, oth + 1, (THOFFSET(th) - 5) << 2))) { 282 goto uncompressed; 283 } 284 285 /* 286 * Figure out which of the changing fields changed. The receiver expects 287 * changes in the order: urgent, window, ack, seq (the order minimizes the 288 * number of temporaries needed in this section of code). 289 */ 290 if (th->th_flags & TH_URG) { 291 deltaS = ntohs(th->th_urp); 292 ENCODEZ(deltaS); 293 changes |= NEW_U; 294 } else if (th->th_urp != oth->th_urp) { 295 296 /* 297 * argh! URG not set but urp changed -- a sensible implementation should 298 * never do this but RFC793 doesn't prohibit the change so we have to 299 * deal with it. 300 */ 301 goto uncompressed; 302 } 303 deltaS = (u_short) (ntohs(th->th_win) - ntohs(oth->th_win)); 304 if (deltaS) { 305 ENCODE(deltaS); 306 changes |= NEW_W; 307 } 308 deltaA = ntohl(th->th_ack) - ntohl(oth->th_ack); 309 if (deltaA) { 310 if (deltaA > 0xffff) { 311 goto uncompressed; 312 } 313 ENCODE(deltaA); 314 changes |= NEW_A; 315 } 316 deltaS = ntohl(th->th_seq) - ntohl(oth->th_seq); 317 if (deltaS) { 318 if (deltaS > 0xffff) { 319 goto uncompressed; 320 } 321 ENCODE(deltaS); 322 changes |= NEW_S; 323 } 324 switch (changes) { 325 326 case 0: 327 328 /* 329 * Nothing changed. If this packet contains data and the last one didn't, 330 * this is probably a data packet following an ack (normal on an 331 * interactive connection) and we send it compressed. Otherwise it's 332 * probably a retransmit, retransmitted ack or window probe. Send it 333 * uncompressed in case the other side missed the compressed version. 334 */ 335 if (ip->ip_len != cs->cs_ip.ip_len && 336 ntohs(cs->cs_ip.ip_len) == hlen) 337 break; 338 339 /* FALLTHROUGH */ 340 341 case SPECIAL_I: 342 case SPECIAL_D: 343 344 /* 345 * actual changes match one of our special case encodings -- send packet 346 * uncompressed. 347 */ 348 goto uncompressed; 349 350 case NEW_S | NEW_A: 351 if (deltaS == deltaA && 352 deltaS == ntohs(cs->cs_ip.ip_len) - hlen) { 353 /* special case for echoed terminal traffic */ 354 changes = SPECIAL_I; 355 cp = new_seq; 356 } 357 break; 358 359 case NEW_S: 360 if (deltaS == ntohs(cs->cs_ip.ip_len) - hlen) { 361 /* special case for data xfer */ 362 changes = SPECIAL_D; 363 cp = new_seq; 364 } 365 break; 366 } 367 368 deltaS = ntohs(ip->ip_id) - ntohs(cs->cs_ip.ip_id); 369 if (deltaS != 1) { 370 ENCODEZ(deltaS); 371 changes |= NEW_I; 372 } 373 if (th->th_flags & TH_PUSH) 374 changes |= TCP_PUSH_BIT; 375 376 /* 377 * Grab the cksum before we overwrite it below. Then update our state with 378 * this packet's header. 379 */ 380 deltaA = ntohs(th->th_sum); 381 memcpy(&cs->cs_ip, ip, hlen); 382 383 /* 384 * We want to use the original packet as our compressed packet. (cp - 385 * new_seq) is the number of bytes we need for compressed sequence numbers. 386 * In addition we need one byte for the change mask, one for the connection 387 * id and two for the tcp checksum. So, (cp - new_seq) + 4 bytes of header 388 * are needed. hlen is how many bytes of the original packet to toss so 389 * subtract the two to get the new packet size. 390 */ 391 deltaS = cp - new_seq; 392 cp = (u_char *) ip; 393 394 /* 395 * Since fastq traffic can jump ahead of the background traffic, we don't 396 * know what order packets will go on the line. In this case, we always 397 * send a "new" connection id so the receiver state stays synchronized. 398 */ 399 if (comp->last_xmit == cs->cs_id && compress_cid) { 400 hlen -= deltaS + 3; 401 cp += hlen; 402 *cp++ = changes; 403 } else { 404 comp->last_xmit = cs->cs_id; 405 hlen -= deltaS + 4; 406 cp += hlen; 407 *cp++ = changes | NEW_C; 408 *cp++ = cs->cs_id; 409 } 410 m->m_len -= hlen; 411 m->m_offset += hlen; 412 *cp++ = deltaA >> 8; 413 *cp++ = deltaA; 414 memcpy(cp, new_seq, deltaS); 415 slstat->sls_compressed++; 416 return (TYPE_COMPRESSED_TCP); 417 418 /* 419 * Update connection state cs & send uncompressed packet ('uncompressed' 420 * means a regular ip/tcp packet but with the 'conversation id' we hope to 421 * use on future compressed packets in the protocol field). 422 */ 423 uncompressed: 424 memcpy(&cs->cs_ip, ip, hlen); 425 ip->ip_p = cs->cs_id; 426 comp->last_xmit = cs->cs_id; 427 return (TYPE_UNCOMPRESSED_TCP); 428 } 429 430 431 int 432 sl_uncompress_tcp(u_char ** bufp, int len, u_int type, struct slcompress *comp, 433 struct slstat *slstat, int max_state) 434 { 435 register u_char *cp; 436 register u_int hlen, changes; 437 register struct tcphdr *th; 438 register struct cstate *cs; 439 register struct ip *ip; 440 u_short *bp; 441 442 switch (type) { 443 444 case TYPE_UNCOMPRESSED_TCP: 445 ip = (struct ip *) * bufp; 446 if (ip->ip_p > max_state) 447 goto bad; 448 cs = &comp->rstate[comp->last_recv = ip->ip_p]; 449 comp->flags &= ~SLF_TOSS; 450 ip->ip_p = IPPROTO_TCP; 451 452 /* 453 * Calculate the size of the TCP/IP header and make sure that we don't 454 * overflow the space we have available for it. 455 */ 456 hlen = ip->ip_hl << 2; 457 if ((int)(hlen + sizeof(struct tcphdr)) > len) 458 goto bad; 459 th = (struct tcphdr *) & ((char *) ip)[hlen]; 460 hlen += THOFFSET(th) << 2; 461 if (hlen > MAX_HDR) 462 goto bad; 463 memcpy(&cs->cs_ip, ip, hlen); 464 cs->cs_hlen = hlen; 465 slstat->sls_uncompressedin++; 466 return (len); 467 468 default: 469 goto bad; 470 471 case TYPE_COMPRESSED_TCP: 472 break; 473 } 474 475 /* We've got a compressed packet. */ 476 slstat->sls_compressedin++; 477 cp = *bufp; 478 changes = *cp++; 479 log_Printf(LogDEBUG, "compressed: changes = %02x\n", changes); 480 481 if (changes & NEW_C) { 482 /* 483 * Make sure the state index is in range, then grab the state. If we have 484 * a good state index, clear the 'discard' flag. 485 */ 486 if (*cp > max_state || comp->last_recv == 255) 487 goto bad; 488 489 comp->flags &= ~SLF_TOSS; 490 comp->last_recv = *cp++; 491 } else { 492 /* 493 * this packet has an implicit state index. If we've had a line error 494 * since the last time we got an explicit state index, we have to toss 495 * the packet. 496 */ 497 if (comp->flags & SLF_TOSS) { 498 slstat->sls_tossed++; 499 return (0); 500 } 501 } 502 cs = &comp->rstate[comp->last_recv]; 503 hlen = cs->cs_ip.ip_hl << 2; 504 th = (struct tcphdr *) & ((u_char *) & cs->cs_ip)[hlen]; 505 th->th_sum = htons((*cp << 8) | cp[1]); 506 cp += 2; 507 if (changes & TCP_PUSH_BIT) 508 th->th_flags |= TH_PUSH; 509 else 510 th->th_flags &= ~TH_PUSH; 511 512 switch (changes & SPECIALS_MASK) { 513 case SPECIAL_I: 514 { 515 register u_int i = ntohs(cs->cs_ip.ip_len) - cs->cs_hlen; 516 517 th->th_ack = htonl(ntohl(th->th_ack) + i); 518 th->th_seq = htonl(ntohl(th->th_seq) + i); 519 } 520 break; 521 522 case SPECIAL_D: 523 th->th_seq = htonl(ntohl(th->th_seq) + ntohs(cs->cs_ip.ip_len) 524 - cs->cs_hlen); 525 break; 526 527 default: 528 if (changes & NEW_U) { 529 th->th_flags |= TH_URG; 530 DECODEU(th->th_urp) 531 } else 532 th->th_flags &= ~TH_URG; 533 if (changes & NEW_W) 534 DECODES(th->th_win) 535 if (changes & NEW_A) 536 DECODEL(th->th_ack) 537 if (changes & NEW_S) { 538 log_Printf(LogDEBUG, "NEW_S: %02x, %02x, %02x\n", 539 *cp, cp[1], cp[2]); 540 DECODEL(th->th_seq) 541 } 542 break; 543 } 544 if (changes & NEW_I) { 545 DECODES(cs->cs_ip.ip_id) 546 } else 547 cs->cs_ip.ip_id = htons(ntohs(cs->cs_ip.ip_id) + 1); 548 549 log_Printf(LogDEBUG, "Uncompress: id = %04x, seq = %08lx\n", 550 cs->cs_ip.ip_id, (u_long)ntohl(th->th_seq)); 551 552 /* 553 * At this point, cp points to the first byte of data in the packet. 554 * Back up cp by the tcp/ip header length to make room for the 555 * reconstructed header (we assume the packet we were handed has enough 556 * space to prepend 128 bytes of header). Adjust the length to account 557 * for the new header & fill in the IP total length. 558 */ 559 len -= (cp - *bufp); 560 if (len < 0) 561 /* 562 * we must have dropped some characters (crc should detect this but the 563 * old slip framing won't) 564 */ 565 goto bad; 566 567 *bufp = cp - cs->cs_hlen; 568 len += cs->cs_hlen; 569 cs->cs_ip.ip_len = htons(len); 570 571 /* recompute the ip header checksum */ 572 cs->cs_ip.ip_sum = 0; 573 bp = (u_short *)&cs->cs_ip; 574 for (changes = 0; hlen > 0; hlen -= 2) 575 changes += *bp++; 576 changes = (changes & 0xffff) + (changes >> 16); 577 changes = (changes & 0xffff) + (changes >> 16); 578 cs->cs_ip.ip_sum = ~changes; 579 580 /* And copy the result into our buffer */ 581 memcpy(*bufp, &cs->cs_ip, cs->cs_hlen); 582 583 return (len); 584 bad: 585 comp->flags |= SLF_TOSS; 586 slstat->sls_errorin++; 587 return (0); 588 } 589 590 int 591 sl_Show(struct cmdargs const *arg) 592 { 593 prompt_Printf(arg->prompt, "VJ compression statistics:\n"); 594 prompt_Printf(arg->prompt, " Out: %d (compress) / %d (total)", 595 arg->bundle->ncp.ipcp.vj.slstat.sls_compressed, 596 arg->bundle->ncp.ipcp.vj.slstat.sls_packets); 597 prompt_Printf(arg->prompt, " %d (miss) / %d (search)\n", 598 arg->bundle->ncp.ipcp.vj.slstat.sls_misses, 599 arg->bundle->ncp.ipcp.vj.slstat.sls_searches); 600 prompt_Printf(arg->prompt, " In: %d (compress), %d (uncompress)", 601 arg->bundle->ncp.ipcp.vj.slstat.sls_compressedin, 602 arg->bundle->ncp.ipcp.vj.slstat.sls_uncompressedin); 603 prompt_Printf(arg->prompt, " %d (error), %d (tossed)\n", 604 arg->bundle->ncp.ipcp.vj.slstat.sls_errorin, 605 arg->bundle->ncp.ipcp.vj.slstat.sls_tossed); 606 return 0; 607 } 608