1 /*- 2 * Copyright (c) 1989, 1993, 1994 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 * @(#)slcompress.c 8.2 (Berkeley) 4/16/94 30 */ 31 32 /* 33 * Routines to compress and uncompess tcp packets (for transmission 34 * over low speed serial lines. 35 * 36 * Van Jacobson (van (at) helios.ee.lbl.gov), Dec 31, 1989: 37 * - Initial distribution. 38 * 39 * $FreeBSD: src/usr.sbin/ppp/slcompress.c,v 1.39.26.1 2010/12/21 17:10:29 kensmith Exp $ 40 */ 41 42 #include <sys/param.h> 43 #include <netinet/in_systm.h> 44 #include <netinet/in.h> 45 #include <netinet/tcp.h> 46 #include <netinet/ip.h> 47 #include <sys/socket.h> 48 #include <sys/un.h> 49 50 #include <stdarg.h> 51 #include <stdio.h> 52 #include <string.h> 53 #include <termios.h> 54 55 #include "layer.h" 56 #include "defs.h" 57 #include "command.h" 58 #include "mbuf.h" 59 #include "log.h" 60 #include "slcompress.h" 61 #include "descriptor.h" 62 #include "prompt.h" 63 #include "timer.h" 64 #include "fsm.h" 65 #include "throughput.h" 66 #include "iplist.h" 67 #include "lqr.h" 68 #include "hdlc.h" 69 #include "ncpaddr.h" 70 #include "ipcp.h" 71 #include "filter.h" 72 #include "lcp.h" 73 #include "ccp.h" 74 #include "link.h" 75 #include "mp.h" 76 #ifndef NORADIUS 77 #include "radius.h" 78 #endif 79 #include "ipv6cp.h" 80 #include "ncp.h" 81 #include "bundle.h" 82 83 void 84 sl_compress_init(struct slcompress *comp, int max_state) 85 { 86 register u_int i; 87 register struct cstate *tstate = comp->tstate; 88 89 memset(comp, '\0', sizeof *comp); 90 for (i = max_state; i > 0; --i) { 91 tstate[i].cs_id = i; 92 tstate[i].cs_next = &tstate[i - 1]; 93 } 94 tstate[0].cs_next = &tstate[max_state]; 95 tstate[0].cs_id = 0; 96 comp->last_cs = &tstate[0]; 97 comp->last_recv = 255; 98 comp->last_xmit = 255; 99 comp->flags = SLF_TOSS; 100 } 101 102 103 /* ENCODE encodes a number that is known to be non-zero. ENCODEZ 104 * checks for zero (since zero has to be encoded in the 32-bit, 3 byte 105 * form). 106 */ 107 #define ENCODE(n) { \ 108 if ((u_short)(n) >= 256) { \ 109 *cp++ = 0; \ 110 cp[1] = (n); \ 111 cp[0] = (n) >> 8; \ 112 cp += 2; \ 113 } else { \ 114 *cp++ = (n); \ 115 } \ 116 } 117 #define ENCODEZ(n) { \ 118 if ((u_short)(n) >= 256 || (u_short)(n) == 0) { \ 119 *cp++ = 0; \ 120 cp[1] = (n); \ 121 cp[0] = (n) >> 8; \ 122 cp += 2; \ 123 } else { \ 124 *cp++ = (n); \ 125 } \ 126 } 127 128 #define DECODEL(f) { \ 129 if (*cp == 0) {\ 130 (f) = htonl(ntohl(f) + ((cp[1] << 8) | cp[2])); \ 131 cp += 3; \ 132 } else { \ 133 (f) = htonl(ntohl(f) + (u_int32_t)*cp++); \ 134 } \ 135 } 136 137 #define DECODES(f) { \ 138 if (*cp == 0) {\ 139 (f) = htons(ntohs(f) + ((cp[1] << 8) | cp[2])); \ 140 cp += 3; \ 141 } else { \ 142 (f) = htons(ntohs(f) + (u_int32_t)*cp++); \ 143 } \ 144 } 145 146 #define DECODEU(f) { \ 147 if (*cp == 0) {\ 148 (f) = htons((cp[1] << 8) | cp[2]); \ 149 cp += 3; \ 150 } else { \ 151 (f) = htons((u_int32_t)*cp++); \ 152 } \ 153 } 154 155 156 u_char 157 sl_compress_tcp(struct mbuf * m, 158 struct ip * ip, 159 struct slcompress *comp, 160 struct slstat *slstat, 161 int compress_cid) 162 { 163 register struct cstate *cs = comp->last_cs->cs_next; 164 register u_int hlen = ip->ip_hl; 165 register struct tcphdr *oth; 166 register struct tcphdr *th; 167 register u_int deltaS, deltaA; 168 register u_int changes = 0; 169 u_char new_seq[16]; 170 register u_char *cp = new_seq; 171 172 /* 173 * Bail if this is an IP fragment or if the TCP packet isn't `compressible' 174 * (i.e., ACK isn't set or some other control bit is set). (We assume that 175 * the caller has already made sure the packet is IP proto TCP). 176 */ 177 if ((ip->ip_off & htons(0x3fff)) || m->m_len < 40) { 178 log_Printf(LogDEBUG, "??? 1 ip_off = %x, m_len = %lu\n", 179 ip->ip_off, (unsigned long)m->m_len); 180 log_DumpBp(LogDEBUG, "", m); 181 return (TYPE_IP); 182 } 183 th = (struct tcphdr *) & ((int *) ip)[hlen]; 184 if ((th->th_flags & (TH_SYN | TH_FIN | TH_RST | TH_ACK)) != TH_ACK) { 185 log_Printf(LogDEBUG, "??? 2 th_flags = %x\n", th->th_flags); 186 log_DumpBp(LogDEBUG, "", m); 187 return (TYPE_IP); 188 } 189 190 /* 191 * Packet is compressible -- we're going to send either a COMPRESSED_TCP or 192 * UNCOMPRESSED_TCP packet. Either way we need to locate (or create) the 193 * connection state. Special case the most recently used connection since 194 * it's most likely to be used again & we don't have to do any reordering 195 * if it's used. 196 */ 197 slstat->sls_packets++; 198 if (ip->ip_src.s_addr != cs->cs_ip.ip_src.s_addr || 199 ip->ip_dst.s_addr != cs->cs_ip.ip_dst.s_addr || 200 *(int *) th != ((int *) &cs->cs_ip)[cs->cs_ip.ip_hl]) { 201 202 /* 203 * Wasn't the first -- search for it. 204 * 205 * States are kept in a circularly linked list with last_cs pointing to the 206 * end of the list. The list is kept in lru order by moving a state to 207 * the head of the list whenever it is referenced. Since the list is 208 * short and, empirically, the connection we want is almost always near 209 * the front, we locate states via linear search. If we don't find a 210 * state for the datagram, the oldest state is (re-)used. 211 */ 212 register struct cstate *lcs; 213 register struct cstate *lastcs = comp->last_cs; 214 215 do { 216 lcs = cs; 217 cs = cs->cs_next; 218 slstat->sls_searches++; 219 if (ip->ip_src.s_addr == cs->cs_ip.ip_src.s_addr 220 && ip->ip_dst.s_addr == cs->cs_ip.ip_dst.s_addr 221 && *(int *) th == ((int *) &cs->cs_ip)[cs->cs_ip.ip_hl]) 222 goto found; 223 } while (cs != lastcs); 224 225 /* 226 * Didn't find it -- re-use oldest cstate. Send an uncompressed packet 227 * that tells the other side what connection number we're using for this 228 * conversation. Note that since the state list is circular, the oldest 229 * state points to the newest and we only need to set last_cs to update 230 * the lru linkage. 231 */ 232 slstat->sls_misses++; 233 comp->last_cs = lcs; 234 #define THOFFSET(th) (th->th_off) 235 hlen += th->th_off; 236 hlen <<= 2; 237 if (hlen > m->m_len) 238 return (TYPE_IP); 239 goto uncompressed; 240 241 found: 242 243 /* 244 * Found it -- move to the front on the connection list. 245 */ 246 if (cs == lastcs) 247 comp->last_cs = lcs; 248 else { 249 lcs->cs_next = cs->cs_next; 250 cs->cs_next = lastcs->cs_next; 251 lastcs->cs_next = cs; 252 } 253 } 254 255 /* 256 * Make sure that only what we expect to change changed. The first line of 257 * the `if' checks the IP protocol version, header length & type of 258 * service. The 2nd line checks the "Don't fragment" bit. The 3rd line 259 * checks the time-to-live and protocol (the protocol check is unnecessary 260 * but costless). The 4th line checks the TCP header length. The 5th line 261 * checks IP options, if any. The 6th line checks TCP options, if any. If 262 * any of these things are different between the previous & current 263 * datagram, we send the current datagram `uncompressed'. 264 */ 265 oth = (struct tcphdr *) & ((int *) &cs->cs_ip)[hlen]; 266 deltaS = hlen; 267 hlen += th->th_off; 268 hlen <<= 2; 269 if (hlen > m->m_len) 270 return (TYPE_IP); 271 272 if (((u_short *) ip)[0] != ((u_short *) & cs->cs_ip)[0] || 273 ((u_short *) ip)[3] != ((u_short *) & cs->cs_ip)[3] || 274 ((u_short *) ip)[4] != ((u_short *) & cs->cs_ip)[4] || 275 THOFFSET(th) != THOFFSET(oth) || 276 (deltaS > 5 && 277 memcmp(ip + 1, &cs->cs_ip + 1, (deltaS - 5) << 2)) || 278 (THOFFSET(th) > 5 && 279 memcmp(th + 1, oth + 1, (THOFFSET(th) - 5) << 2))) { 280 goto uncompressed; 281 } 282 283 /* 284 * Figure out which of the changing fields changed. The receiver expects 285 * changes in the order: urgent, window, ack, seq (the order minimizes the 286 * number of temporaries needed in this section of code). 287 */ 288 if (th->th_flags & TH_URG) { 289 deltaS = ntohs(th->th_urp); 290 ENCODEZ(deltaS); 291 changes |= NEW_U; 292 } else if (th->th_urp != oth->th_urp) { 293 294 /* 295 * argh! URG not set but urp changed -- a sensible implementation should 296 * never do this but RFC793 doesn't prohibit the change so we have to 297 * deal with it. 298 */ 299 goto uncompressed; 300 } 301 deltaS = (u_short) (ntohs(th->th_win) - ntohs(oth->th_win)); 302 if (deltaS) { 303 ENCODE(deltaS); 304 changes |= NEW_W; 305 } 306 deltaA = ntohl(th->th_ack) - ntohl(oth->th_ack); 307 if (deltaA) { 308 if (deltaA > 0xffff) { 309 goto uncompressed; 310 } 311 ENCODE(deltaA); 312 changes |= NEW_A; 313 } 314 deltaS = ntohl(th->th_seq) - ntohl(oth->th_seq); 315 if (deltaS) { 316 if (deltaS > 0xffff) { 317 goto uncompressed; 318 } 319 ENCODE(deltaS); 320 changes |= NEW_S; 321 } 322 switch (changes) { 323 324 case 0: 325 326 /* 327 * Nothing changed. If this packet contains data and the last one didn't, 328 * this is probably a data packet following an ack (normal on an 329 * interactive connection) and we send it compressed. Otherwise it's 330 * probably a retransmit, retransmitted ack or window probe. Send it 331 * uncompressed in case the other side missed the compressed version. 332 */ 333 if (ip->ip_len != cs->cs_ip.ip_len && 334 ntohs(cs->cs_ip.ip_len) == hlen) 335 break; 336 337 /* FALLTHROUGH */ 338 339 case SPECIAL_I: 340 case SPECIAL_D: 341 342 /* 343 * actual changes match one of our special case encodings -- send packet 344 * uncompressed. 345 */ 346 goto uncompressed; 347 348 case NEW_S | NEW_A: 349 if (deltaS == deltaA && 350 deltaS == ntohs(cs->cs_ip.ip_len) - hlen) { 351 /* special case for echoed terminal traffic */ 352 changes = SPECIAL_I; 353 cp = new_seq; 354 } 355 break; 356 357 case NEW_S: 358 if (deltaS == ntohs(cs->cs_ip.ip_len) - hlen) { 359 /* special case for data xfer */ 360 changes = SPECIAL_D; 361 cp = new_seq; 362 } 363 break; 364 } 365 366 deltaS = ntohs(ip->ip_id) - ntohs(cs->cs_ip.ip_id); 367 if (deltaS != 1) { 368 ENCODEZ(deltaS); 369 changes |= NEW_I; 370 } 371 if (th->th_flags & TH_PUSH) 372 changes |= TCP_PUSH_BIT; 373 374 /* 375 * Grab the cksum before we overwrite it below. Then update our state with 376 * this packet's header. 377 */ 378 deltaA = ntohs(th->th_sum); 379 memcpy(&cs->cs_ip, ip, hlen); 380 381 /* 382 * We want to use the original packet as our compressed packet. (cp - 383 * new_seq) is the number of bytes we need for compressed sequence numbers. 384 * In addition we need one byte for the change mask, one for the connection 385 * id and two for the tcp checksum. So, (cp - new_seq) + 4 bytes of header 386 * are needed. hlen is how many bytes of the original packet to toss so 387 * subtract the two to get the new packet size. 388 */ 389 deltaS = cp - new_seq; 390 cp = (u_char *) ip; 391 392 /* 393 * Since fastq traffic can jump ahead of the background traffic, we don't 394 * know what order packets will go on the line. In this case, we always 395 * send a "new" connection id so the receiver state stays synchronized. 396 */ 397 if (comp->last_xmit == cs->cs_id && compress_cid) { 398 hlen -= deltaS + 3; 399 cp += hlen; 400 *cp++ = changes; 401 } else { 402 comp->last_xmit = cs->cs_id; 403 hlen -= deltaS + 4; 404 cp += hlen; 405 *cp++ = changes | NEW_C; 406 *cp++ = cs->cs_id; 407 } 408 m->m_len -= hlen; 409 m->m_offset += hlen; 410 *cp++ = deltaA >> 8; 411 *cp++ = deltaA; 412 memcpy(cp, new_seq, deltaS); 413 slstat->sls_compressed++; 414 return (TYPE_COMPRESSED_TCP); 415 416 /* 417 * Update connection state cs & send uncompressed packet ('uncompressed' 418 * means a regular ip/tcp packet but with the 'conversation id' we hope to 419 * use on future compressed packets in the protocol field). 420 */ 421 uncompressed: 422 memcpy(&cs->cs_ip, ip, hlen); 423 ip->ip_p = cs->cs_id; 424 comp->last_xmit = cs->cs_id; 425 return (TYPE_UNCOMPRESSED_TCP); 426 } 427 428 429 int 430 sl_uncompress_tcp(u_char ** bufp, int len, u_int type, struct slcompress *comp, 431 struct slstat *slstat, int max_state) 432 { 433 register u_char *cp; 434 register u_int hlen, changes; 435 register struct tcphdr *th; 436 register struct cstate *cs; 437 register struct ip *ip; 438 u_short *bp; 439 440 switch (type) { 441 442 case TYPE_UNCOMPRESSED_TCP: 443 ip = (struct ip *) * bufp; 444 if (ip->ip_p > max_state) 445 goto bad; 446 cs = &comp->rstate[comp->last_recv = ip->ip_p]; 447 comp->flags &= ~SLF_TOSS; 448 ip->ip_p = IPPROTO_TCP; 449 450 /* 451 * Calculate the size of the TCP/IP header and make sure that we don't 452 * overflow the space we have available for it. 453 */ 454 hlen = ip->ip_hl << 2; 455 if ((int)(hlen + sizeof(struct tcphdr)) > len) 456 goto bad; 457 th = (struct tcphdr *) & ((char *) ip)[hlen]; 458 hlen += THOFFSET(th) << 2; 459 if (hlen > MAX_HDR) 460 goto bad; 461 memcpy(&cs->cs_ip, ip, hlen); 462 cs->cs_hlen = hlen; 463 slstat->sls_uncompressedin++; 464 return (len); 465 466 default: 467 goto bad; 468 469 case TYPE_COMPRESSED_TCP: 470 break; 471 } 472 473 /* We've got a compressed packet. */ 474 slstat->sls_compressedin++; 475 cp = *bufp; 476 changes = *cp++; 477 log_Printf(LogDEBUG, "compressed: changes = %02x\n", changes); 478 479 if (changes & NEW_C) { 480 /* 481 * Make sure the state index is in range, then grab the state. If we have 482 * a good state index, clear the 'discard' flag. 483 */ 484 if (*cp > max_state || comp->last_recv == 255) 485 goto bad; 486 487 comp->flags &= ~SLF_TOSS; 488 comp->last_recv = *cp++; 489 } else { 490 /* 491 * this packet has an implicit state index. If we've had a line error 492 * since the last time we got an explicit state index, we have to toss 493 * the packet. 494 */ 495 if (comp->flags & SLF_TOSS) { 496 slstat->sls_tossed++; 497 return (0); 498 } 499 } 500 cs = &comp->rstate[comp->last_recv]; 501 hlen = cs->cs_ip.ip_hl << 2; 502 th = (struct tcphdr *) & ((u_char *) & cs->cs_ip)[hlen]; 503 th->th_sum = htons((*cp << 8) | cp[1]); 504 cp += 2; 505 if (changes & TCP_PUSH_BIT) 506 th->th_flags |= TH_PUSH; 507 else 508 th->th_flags &= ~TH_PUSH; 509 510 switch (changes & SPECIALS_MASK) { 511 case SPECIAL_I: 512 { 513 register u_int i = ntohs(cs->cs_ip.ip_len) - cs->cs_hlen; 514 515 th->th_ack = htonl(ntohl(th->th_ack) + i); 516 th->th_seq = htonl(ntohl(th->th_seq) + i); 517 } 518 break; 519 520 case SPECIAL_D: 521 th->th_seq = htonl(ntohl(th->th_seq) + ntohs(cs->cs_ip.ip_len) 522 - cs->cs_hlen); 523 break; 524 525 default: 526 if (changes & NEW_U) { 527 th->th_flags |= TH_URG; 528 DECODEU(th->th_urp) 529 } else 530 th->th_flags &= ~TH_URG; 531 if (changes & NEW_W) 532 DECODES(th->th_win) 533 if (changes & NEW_A) 534 DECODEL(th->th_ack) 535 if (changes & NEW_S) { 536 log_Printf(LogDEBUG, "NEW_S: %02x, %02x, %02x\n", 537 *cp, cp[1], cp[2]); 538 DECODEL(th->th_seq) 539 } 540 break; 541 } 542 if (changes & NEW_I) { 543 DECODES(cs->cs_ip.ip_id) 544 } else 545 cs->cs_ip.ip_id = htons(ntohs(cs->cs_ip.ip_id) + 1); 546 547 log_Printf(LogDEBUG, "Uncompress: id = %04x, seq = %08lx\n", 548 cs->cs_ip.ip_id, (u_long)ntohl(th->th_seq)); 549 550 /* 551 * At this point, cp points to the first byte of data in the packet. 552 * Back up cp by the tcp/ip header length to make room for the 553 * reconstructed header (we assume the packet we were handed has enough 554 * space to prepend 128 bytes of header). Adjust the length to account 555 * for the new header & fill in the IP total length. 556 */ 557 len -= (cp - *bufp); 558 if (len < 0) 559 /* 560 * we must have dropped some characters (crc should detect this but the 561 * old slip framing won't) 562 */ 563 goto bad; 564 565 *bufp = cp - cs->cs_hlen; 566 len += cs->cs_hlen; 567 cs->cs_ip.ip_len = htons(len); 568 569 /* recompute the ip header checksum */ 570 cs->cs_ip.ip_sum = 0; 571 bp = (u_short *)&cs->cs_ip; 572 for (changes = 0; hlen > 0; hlen -= 2) 573 changes += *bp++; 574 changes = (changes & 0xffff) + (changes >> 16); 575 changes = (changes & 0xffff) + (changes >> 16); 576 cs->cs_ip.ip_sum = ~changes; 577 578 /* And copy the result into our buffer */ 579 memcpy(*bufp, &cs->cs_ip, cs->cs_hlen); 580 581 return (len); 582 bad: 583 comp->flags |= SLF_TOSS; 584 slstat->sls_errorin++; 585 return (0); 586 } 587 588 int 589 sl_Show(struct cmdargs const *arg) 590 { 591 prompt_Printf(arg->prompt, "VJ compression statistics:\n"); 592 prompt_Printf(arg->prompt, " Out: %d (compress) / %d (total)", 593 arg->bundle->ncp.ipcp.vj.slstat.sls_compressed, 594 arg->bundle->ncp.ipcp.vj.slstat.sls_packets); 595 prompt_Printf(arg->prompt, " %d (miss) / %d (search)\n", 596 arg->bundle->ncp.ipcp.vj.slstat.sls_misses, 597 arg->bundle->ncp.ipcp.vj.slstat.sls_searches); 598 prompt_Printf(arg->prompt, " In: %d (compress), %d (uncompress)", 599 arg->bundle->ncp.ipcp.vj.slstat.sls_compressedin, 600 arg->bundle->ncp.ipcp.vj.slstat.sls_uncompressedin); 601 prompt_Printf(arg->prompt, " %d (error), %d (tossed)\n", 602 arg->bundle->ncp.ipcp.vj.slstat.sls_errorin, 603 arg->bundle->ncp.ipcp.vj.slstat.sls_tossed); 604 return 0; 605 } 606
