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