| 1 | /* $NetBSD: slcompress.c,v 1.40 2016/08/05 08:56:36 pgoyette Exp $ */ |
| 2 | /* Id: slcompress.c,v 1.3 1996/05/24 07:04:47 paulus Exp */ |
| 3 | |
| 4 | /* |
| 5 | * Copyright (c) 1989, 1993, 1994 |
| 6 | * The Regents of the University of California. All rights reserved. |
| 7 | * |
| 8 | * Redistribution and use in source and binary forms, with or without |
| 9 | * modification, are permitted provided that the following conditions |
| 10 | * are met: |
| 11 | * 1. Redistributions of source code must retain the above copyright |
| 12 | * notice, this list of conditions and the following disclaimer. |
| 13 | * 2. Redistributions in binary form must reproduce the above copyright |
| 14 | * notice, this list of conditions and the following disclaimer in the |
| 15 | * documentation and/or other materials provided with the distribution. |
| 16 | * 3. Neither the name of the University nor the names of its contributors |
| 17 | * may be used to endorse or promote products derived from this software |
| 18 | * without specific prior written permission. |
| 19 | * |
| 20 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
| 21 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| 22 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| 23 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
| 24 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| 25 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| 26 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| 27 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| 28 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| 29 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| 30 | * SUCH DAMAGE. |
| 31 | * |
| 32 | * @(#)slcompress.c 8.2 (Berkeley) 4/16/94 |
| 33 | */ |
| 34 | |
| 35 | /* |
| 36 | * Routines to compress and uncompess tcp packets (for transmission |
| 37 | * over low speed serial lines. |
| 38 | * |
| 39 | * Van Jacobson (van@helios.ee.lbl.gov), Dec 31, 1989: |
| 40 | * - Initial distribution. |
| 41 | */ |
| 42 | |
| 43 | #include <sys/cdefs.h> |
| 44 | __KERNEL_RCSID(0, "$NetBSD: slcompress.c,v 1.40 2016/08/05 08:56:36 pgoyette Exp $" ); |
| 45 | |
| 46 | #ifdef _KERNEL_OPT |
| 47 | #include "opt_inet.h" |
| 48 | #endif |
| 49 | |
| 50 | #ifdef INET |
| 51 | #include <sys/param.h> |
| 52 | #include <sys/mbuf.h> |
| 53 | #include <sys/systm.h> |
| 54 | #include <sys/module.h> |
| 55 | |
| 56 | #include <netinet/in.h> |
| 57 | #include <netinet/in_systm.h> |
| 58 | #include <netinet/ip.h> |
| 59 | #include <netinet/tcp.h> |
| 60 | |
| 61 | #include <net/slcompress.h> |
| 62 | |
| 63 | #ifndef SL_NO_STATS |
| 64 | #define INCR(counter) ++comp->counter; |
| 65 | #else |
| 66 | #define INCR(counter) |
| 67 | #endif |
| 68 | |
| 69 | |
| 70 | void |
| 71 | sl_compress_init(struct slcompress *comp) |
| 72 | { |
| 73 | u_int i; |
| 74 | struct cstate *tstate = comp->tstate; |
| 75 | |
| 76 | memset(comp, 0, sizeof(*comp)); |
| 77 | for (i = MAX_STATES - 1; i > 0; --i) { |
| 78 | tstate[i].cs_id = i; |
| 79 | tstate[i].cs_next = &tstate[i - 1]; |
| 80 | } |
| 81 | tstate[0].cs_next = &tstate[MAX_STATES - 1]; |
| 82 | tstate[0].cs_id = 0; |
| 83 | comp->last_cs = &tstate[0]; |
| 84 | comp->last_recv = 255; |
| 85 | comp->last_xmit = 255; |
| 86 | comp->flags = SLF_TOSS; |
| 87 | } |
| 88 | |
| 89 | |
| 90 | /* |
| 91 | * Like sl_compress_init, but we get to specify the maximum connection |
| 92 | * ID to use on transmission. |
| 93 | */ |
| 94 | void |
| 95 | sl_compress_setup(struct slcompress *comp, int max_state) |
| 96 | { |
| 97 | u_int i; |
| 98 | struct cstate *tstate = comp->tstate; |
| 99 | |
| 100 | if (max_state == -1) { |
| 101 | max_state = MAX_STATES - 1; |
| 102 | memset(comp, 0, sizeof(*comp)); |
| 103 | } else { |
| 104 | /* Don't reset statistics */ |
| 105 | memset(comp->tstate, 0, sizeof(comp->tstate)); |
| 106 | memset(comp->rstate, 0, sizeof(comp->rstate)); |
| 107 | } |
| 108 | for (i = max_state; i > 0; --i) { |
| 109 | tstate[i].cs_id = i; |
| 110 | tstate[i].cs_next = &tstate[i - 1]; |
| 111 | } |
| 112 | tstate[0].cs_next = &tstate[max_state]; |
| 113 | tstate[0].cs_id = 0; |
| 114 | comp->last_cs = &tstate[0]; |
| 115 | comp->last_recv = 255; |
| 116 | comp->last_xmit = 255; |
| 117 | comp->flags = SLF_TOSS; |
| 118 | } |
| 119 | |
| 120 | |
| 121 | /* ENCODE encodes a number that is known to be non-zero. ENCODEZ |
| 122 | * checks for zero (since zero has to be encoded in the long, 3 byte |
| 123 | * form). |
| 124 | */ |
| 125 | #define ENCODE(n) { \ |
| 126 | if ((uint16_t)(n) >= 256) { \ |
| 127 | *cp++ = 0; \ |
| 128 | cp[1] = (n); \ |
| 129 | cp[0] = (n) >> 8; \ |
| 130 | cp += 2; \ |
| 131 | } else { \ |
| 132 | *cp++ = (n); \ |
| 133 | } \ |
| 134 | } |
| 135 | #define ENCODEZ(n) { \ |
| 136 | if ((uint16_t)(n) >= 256 || (uint16_t)(n) == 0) { \ |
| 137 | *cp++ = 0; \ |
| 138 | cp[1] = (n); \ |
| 139 | cp[0] = (n) >> 8; \ |
| 140 | cp += 2; \ |
| 141 | } else { \ |
| 142 | *cp++ = (n); \ |
| 143 | } \ |
| 144 | } |
| 145 | |
| 146 | #define DECODEL(f) { \ |
| 147 | if (*cp == 0) {\ |
| 148 | (f) = htonl(ntohl(f) + ((cp[1] << 8) | cp[2])); \ |
| 149 | cp += 3; \ |
| 150 | } else { \ |
| 151 | (f) = htonl(ntohl(f) + (uint32_t)*cp++); \ |
| 152 | } \ |
| 153 | } |
| 154 | |
| 155 | #define DECODES(f) { \ |
| 156 | if (*cp == 0) {\ |
| 157 | (f) = htons(ntohs(f) + ((cp[1] << 8) | cp[2])); \ |
| 158 | cp += 3; \ |
| 159 | } else { \ |
| 160 | (f) = htons(ntohs(f) + (uint32_t)*cp++); \ |
| 161 | } \ |
| 162 | } |
| 163 | |
| 164 | #define DECODEU(f) { \ |
| 165 | if (*cp == 0) {\ |
| 166 | (f) = htons((cp[1] << 8) | cp[2]); \ |
| 167 | cp += 3; \ |
| 168 | } else { \ |
| 169 | (f) = htons((uint32_t)*cp++); \ |
| 170 | } \ |
| 171 | } |
| 172 | |
| 173 | u_int |
| 174 | sl_compress_tcp(struct mbuf *m, struct ip *ip, struct slcompress *comp, |
| 175 | int compress_cid) |
| 176 | { |
| 177 | struct cstate *cs = comp->last_cs->cs_next; |
| 178 | u_int hlen = ip->ip_hl; |
| 179 | struct tcphdr *oth; |
| 180 | struct tcphdr *th; |
| 181 | u_int deltaS, deltaA; |
| 182 | u_int changes = 0; |
| 183 | u_char new_seq[16]; |
| 184 | u_char *cp = new_seq; |
| 185 | |
| 186 | /* |
| 187 | * Bail if this is an IP fragment or if the TCP packet isn't |
| 188 | * `compressible' (i.e., ACK isn't set or some other control bit is |
| 189 | * set). (We assume that the caller has already made sure the |
| 190 | * packet is IP proto TCP). |
| 191 | */ |
| 192 | if ((ip->ip_off & htons(0x3fff)) || m->m_len < 40) |
| 193 | return (TYPE_IP); |
| 194 | |
| 195 | th = (struct tcphdr *)&((int32_t *)ip)[hlen]; |
| 196 | if ((th->th_flags & (TH_SYN|TH_FIN|TH_RST|TH_ACK)) != TH_ACK) |
| 197 | return (TYPE_IP); |
| 198 | /* |
| 199 | * Packet is compressible -- we're going to send either a |
| 200 | * COMPRESSED_TCP or UNCOMPRESSED_TCP packet. Either way we need |
| 201 | * to locate (or create) the connection state. Special case the |
| 202 | * most recently used connection since it's most likely to be used |
| 203 | * again & we don't have to do any reordering if it's used. |
| 204 | */ |
| 205 | INCR(sls_packets) |
| 206 | if (ip->ip_src.s_addr != cs->cs_ip.ip_src.s_addr || |
| 207 | ip->ip_dst.s_addr != cs->cs_ip.ip_dst.s_addr || |
| 208 | *(int32_t *)th != ((int32_t *)&cs->cs_ip)[cs->cs_ip.ip_hl]) { |
| 209 | /* |
| 210 | * Wasn't the first -- search for it. |
| 211 | * |
| 212 | * States are kept in a circularly linked list with |
| 213 | * last_cs pointing to the end of the list. The |
| 214 | * list is kept in lru order by moving a state to the |
| 215 | * head of the list whenever it is referenced. Since |
| 216 | * the list is short and, empirically, the connection |
| 217 | * we want is almost always near the front, we locate |
| 218 | * states via linear search. If we don't find a state |
| 219 | * for the datagram, the oldest state is (re-)used. |
| 220 | */ |
| 221 | struct cstate *lcs; |
| 222 | struct cstate *lastcs = comp->last_cs; |
| 223 | |
| 224 | do { |
| 225 | lcs = cs; cs = cs->cs_next; |
| 226 | INCR(sls_searches) |
| 227 | if (ip->ip_src.s_addr == cs->cs_ip.ip_src.s_addr |
| 228 | && ip->ip_dst.s_addr == cs->cs_ip.ip_dst.s_addr |
| 229 | && *(int32_t *)th == |
| 230 | ((int32_t *)&cs->cs_ip)[cs->cs_ip.ip_hl]) |
| 231 | goto found; |
| 232 | } while (cs != lastcs); |
| 233 | |
| 234 | /* |
| 235 | * Didn't find it -- re-use oldest cstate. Send an |
| 236 | * uncompressed packet that tells the other side what |
| 237 | * connection number we're using for this conversation. |
| 238 | * Note that since the state list is circular, the oldest |
| 239 | * state points to the newest and we only need to set |
| 240 | * last_cs to update the lru linkage. |
| 241 | */ |
| 242 | INCR(sls_misses) |
| 243 | comp->last_cs = lcs; |
| 244 | hlen += th->th_off; |
| 245 | hlen <<= 2; |
| 246 | if (hlen > m->m_len) |
| 247 | return (TYPE_IP); |
| 248 | goto uncompressed; |
| 249 | |
| 250 | found: |
| 251 | /* |
| 252 | * Found it -- move to the front on the connection list. |
| 253 | */ |
| 254 | if (cs == lastcs) |
| 255 | comp->last_cs = lcs; |
| 256 | else { |
| 257 | lcs->cs_next = cs->cs_next; |
| 258 | cs->cs_next = lastcs->cs_next; |
| 259 | lastcs->cs_next = cs; |
| 260 | } |
| 261 | } |
| 262 | |
| 263 | /* |
| 264 | * Make sure that only what we expect to change changed. The first |
| 265 | * line of the `if' checks the IP protocol version, header length & |
| 266 | * type of service. The 2nd line checks the "Don't fragment" bit. |
| 267 | * The 3rd line checks the time-to-live and protocol (the protocol |
| 268 | * check is unnecessary but costless). The 4th line checks the TCP |
| 269 | * header length. The 5th line checks IP options, if any. The 6th |
| 270 | * line checks TCP options, if any. If any of these things are |
| 271 | * different between the previous & current datagram, we send the |
| 272 | * current datagram `uncompressed'. |
| 273 | */ |
| 274 | oth = (struct tcphdr *)&((int32_t *)&cs->cs_ip)[hlen]; |
| 275 | deltaS = hlen; |
| 276 | hlen += th->th_off; |
| 277 | hlen <<= 2; |
| 278 | if (hlen > m->m_len) |
| 279 | return (TYPE_IP); |
| 280 | |
| 281 | if (((uint16_t *)ip)[0] != ((uint16_t *)&cs->cs_ip)[0] || |
| 282 | ((uint16_t *)ip)[3] != ((uint16_t *)&cs->cs_ip)[3] || |
| 283 | ((uint16_t *)ip)[4] != ((uint16_t *)&cs->cs_ip)[4] || |
| 284 | th->th_off != oth->th_off || |
| 285 | (deltaS > 5 && |
| 286 | memcmp(ip + 1, &cs->cs_ip + 1, (deltaS - 5) << 2)) || |
| 287 | (th->th_off > 5 && |
| 288 | memcmp(th + 1, oth + 1, (th->th_off - 5) << 2))) |
| 289 | goto uncompressed; |
| 290 | |
| 291 | /* |
| 292 | * Figure out which of the changing fields changed. The |
| 293 | * receiver expects changes in the order: urgent, window, |
| 294 | * ack, seq (the order minimizes the number of temporaries |
| 295 | * needed in this section of code). |
| 296 | */ |
| 297 | if (th->th_flags & TH_URG) { |
| 298 | deltaS = ntohs(th->th_urp); |
| 299 | ENCODEZ(deltaS); |
| 300 | changes |= NEW_U; |
| 301 | } else if (th->th_urp != oth->th_urp) |
| 302 | /* argh! URG not set but urp changed -- a sensible |
| 303 | * implementation should never do this but RFC793 |
| 304 | * doesn't prohibit the change so we have to deal |
| 305 | * with it. */ |
| 306 | goto uncompressed; |
| 307 | |
| 308 | deltaS = (uint16_t)(ntohs(th->th_win) - ntohs(oth->th_win)); |
| 309 | if (deltaS) { |
| 310 | ENCODE(deltaS); |
| 311 | changes |= NEW_W; |
| 312 | } |
| 313 | |
| 314 | deltaA = ntohl(th->th_ack) - ntohl(oth->th_ack); |
| 315 | if (deltaA) { |
| 316 | if (deltaA > 0xffff) |
| 317 | goto uncompressed; |
| 318 | ENCODE(deltaA); |
| 319 | changes |= NEW_A; |
| 320 | } |
| 321 | |
| 322 | deltaS = ntohl(th->th_seq) - ntohl(oth->th_seq); |
| 323 | if (deltaS) { |
| 324 | if (deltaS > 0xffff) |
| 325 | goto uncompressed; |
| 326 | ENCODE(deltaS); |
| 327 | changes |= NEW_S; |
| 328 | } |
| 329 | |
| 330 | switch (changes) { |
| 331 | |
| 332 | case 0: |
| 333 | /* |
| 334 | * Nothing changed. If this packet contains data and the |
| 335 | * last one didn't, this is probably a data packet following |
| 336 | * an ack (normal on an interactive connection) and we send |
| 337 | * it compressed. Otherwise it's probably a retransmit, |
| 338 | * retransmitted ack or window probe. Send it uncompressed |
| 339 | * in case the other side missed the compressed version. |
| 340 | */ |
| 341 | if (ip->ip_len != cs->cs_ip.ip_len && |
| 342 | ntohs(cs->cs_ip.ip_len) == hlen) |
| 343 | break; |
| 344 | |
| 345 | /* (fall through) */ |
| 346 | |
| 347 | case SPECIAL_I: |
| 348 | case SPECIAL_D: |
| 349 | /* |
| 350 | * actual changes match one of our special case encodings -- |
| 351 | * send packet uncompressed. |
| 352 | */ |
| 353 | goto uncompressed; |
| 354 | |
| 355 | case NEW_S|NEW_A: |
| 356 | if (deltaS == deltaA && |
| 357 | deltaS == ntohs(cs->cs_ip.ip_len) - hlen) { |
| 358 | /* special case for echoed terminal traffic */ |
| 359 | changes = SPECIAL_I; |
| 360 | cp = new_seq; |
| 361 | } |
| 362 | break; |
| 363 | |
| 364 | case NEW_S: |
| 365 | if (deltaS == ntohs(cs->cs_ip.ip_len) - hlen) { |
| 366 | /* special case for data xfer */ |
| 367 | changes = SPECIAL_D; |
| 368 | cp = new_seq; |
| 369 | } |
| 370 | break; |
| 371 | } |
| 372 | |
| 373 | deltaS = ntohs(ip->ip_id) - ntohs(cs->cs_ip.ip_id); |
| 374 | if (deltaS != 1) { |
| 375 | ENCODEZ(deltaS); |
| 376 | changes |= NEW_I; |
| 377 | } |
| 378 | if (th->th_flags & TH_PUSH) |
| 379 | changes |= TCP_PUSH_BIT; |
| 380 | /* |
| 381 | * Grab the cksum before we overwrite it below. Then update our |
| 382 | * state with this packet's header. |
| 383 | */ |
| 384 | deltaA = ntohs(th->th_sum); |
| 385 | memcpy(&cs->cs_ip, ip, hlen); |
| 386 | |
| 387 | /* |
| 388 | * We want to use the original packet as our compressed packet. |
| 389 | * (cp - new_seq) is the number of bytes we need for compressed |
| 390 | * sequence numbers. In addition we need one byte for the change |
| 391 | * mask, one for the connection id and two for the tcp checksum. |
| 392 | * So, (cp - new_seq) + 4 bytes of header are needed. hlen is how |
| 393 | * many bytes of the original packet to toss so subtract the two to |
| 394 | * get the new packet size. |
| 395 | */ |
| 396 | deltaS = cp - new_seq; |
| 397 | cp = (u_char *)ip; |
| 398 | if (compress_cid == 0 || comp->last_xmit != cs->cs_id) { |
| 399 | comp->last_xmit = cs->cs_id; |
| 400 | hlen -= deltaS + 4; |
| 401 | cp += hlen; |
| 402 | *cp++ = changes | NEW_C; |
| 403 | *cp++ = cs->cs_id; |
| 404 | } else { |
| 405 | hlen -= deltaS + 3; |
| 406 | cp += hlen; |
| 407 | *cp++ = changes; |
| 408 | } |
| 409 | m->m_len -= hlen; |
| 410 | m->m_data += hlen; |
| 411 | *cp++ = deltaA >> 8; |
| 412 | *cp++ = deltaA; |
| 413 | memcpy(cp, new_seq, deltaS); |
| 414 | INCR(sls_compressed) |
| 415 | return (TYPE_COMPRESSED_TCP); |
| 416 | |
| 417 | /* |
| 418 | * Update connection state cs & send uncompressed packet ('uncompressed' |
| 419 | * means a regular ip/tcp packet but with the 'conversation id' we hope |
| 420 | * to use on future compressed packets in the protocol field). |
| 421 | */ |
| 422 | uncompressed: |
| 423 | memcpy(&cs->cs_ip, ip, hlen); |
| 424 | ip->ip_p = cs->cs_id; |
| 425 | comp->last_xmit = cs->cs_id; |
| 426 | return (TYPE_UNCOMPRESSED_TCP); |
| 427 | } |
| 428 | |
| 429 | |
| 430 | int |
| 431 | sl_uncompress_tcp(u_char **bufp, int len, u_int type, struct slcompress *comp) |
| 432 | { |
| 433 | u_char *hdr, *cp; |
| 434 | int vjlen; |
| 435 | u_int hlen; |
| 436 | |
| 437 | cp = bufp ? *bufp : NULL; |
| 438 | vjlen = sl_uncompress_tcp_core(cp, len, len, type, comp, &hdr, &hlen); |
| 439 | if (vjlen < 0) |
| 440 | return (0); /* error */ |
| 441 | if (vjlen == 0) |
| 442 | return (len); /* was uncompressed already */ |
| 443 | |
| 444 | cp += vjlen; |
| 445 | len -= vjlen; |
| 446 | |
| 447 | /* |
| 448 | * At this point, cp points to the first byte of data in the |
| 449 | * packet. If we're not aligned on a 4-byte boundary, copy the |
| 450 | * data down so the ip & tcp headers will be aligned. Then back up |
| 451 | * cp by the tcp/ip header length to make room for the reconstructed |
| 452 | * header (we assume the packet we were handed has enough space to |
| 453 | * prepend 128 bytes of header). |
| 454 | */ |
| 455 | if ((long)cp & 3) { |
| 456 | if (len > 0) |
| 457 | memmove((void *)((long)cp &~ 3), cp, len); |
| 458 | cp = (u_char *)((long)cp &~ 3); |
| 459 | } |
| 460 | cp -= hlen; |
| 461 | len += hlen; |
| 462 | memcpy(cp, hdr, hlen); |
| 463 | |
| 464 | *bufp = cp; |
| 465 | return (len); |
| 466 | } |
| 467 | |
| 468 | /* |
| 469 | * Uncompress a packet of total length total_len. The first buflen |
| 470 | * bytes are at buf; this must include the entire (compressed or |
| 471 | * uncompressed) TCP/IP header. This procedure returns the length |
| 472 | * of the VJ header, with a pointer to the uncompressed IP header |
| 473 | * in *hdrp and its length in *hlenp. |
| 474 | */ |
| 475 | int |
| 476 | sl_uncompress_tcp_core(u_char *buf, int buflen, int total_len, u_int type, |
| 477 | struct slcompress *comp, u_char **hdrp, u_int *hlenp) |
| 478 | { |
| 479 | u_char *cp; |
| 480 | u_int hlen, changes; |
| 481 | struct tcphdr *th; |
| 482 | struct cstate *cs; |
| 483 | struct ip *ip; |
| 484 | uint16_t *bp; |
| 485 | u_int vjlen; |
| 486 | |
| 487 | switch (type) { |
| 488 | |
| 489 | case TYPE_UNCOMPRESSED_TCP: |
| 490 | if (buf == NULL) |
| 491 | goto bad; |
| 492 | ip = (struct ip *) buf; |
| 493 | if (ip->ip_p >= MAX_STATES) |
| 494 | goto bad; |
| 495 | cs = &comp->rstate[comp->last_recv = ip->ip_p]; |
| 496 | comp->flags &=~ SLF_TOSS; |
| 497 | ip->ip_p = IPPROTO_TCP; |
| 498 | /* |
| 499 | * Calculate the size of the TCP/IP header and make sure that |
| 500 | * we don't overflow the space we have available for it. |
| 501 | */ |
| 502 | hlen = ip->ip_hl << 2; |
| 503 | if (hlen + sizeof(struct tcphdr) > buflen) |
| 504 | goto bad; |
| 505 | hlen += ((struct tcphdr *)&((char *)ip)[hlen])->th_off << 2; |
| 506 | if (hlen > MAX_HDR || hlen > buflen) |
| 507 | goto bad; |
| 508 | memcpy(&cs->cs_ip, ip, hlen); |
| 509 | cs->cs_hlen = hlen; |
| 510 | INCR(sls_uncompressedin) |
| 511 | *hdrp = (u_char *) &cs->cs_ip; |
| 512 | *hlenp = hlen; |
| 513 | return (0); |
| 514 | |
| 515 | default: |
| 516 | goto bad; |
| 517 | |
| 518 | case TYPE_COMPRESSED_TCP: |
| 519 | break; |
| 520 | } |
| 521 | /* We've got a compressed packet. */ |
| 522 | INCR(sls_compressedin) |
| 523 | if (buf == NULL) |
| 524 | goto bad; |
| 525 | cp = buf; |
| 526 | changes = *cp++; |
| 527 | if (changes & NEW_C) { |
| 528 | /* Make sure the state index is in range, then grab the state. |
| 529 | * If we have a good state index, clear the 'discard' flag. */ |
| 530 | if (*cp >= MAX_STATES) |
| 531 | goto bad; |
| 532 | |
| 533 | comp->flags &=~ SLF_TOSS; |
| 534 | comp->last_recv = *cp++; |
| 535 | } else { |
| 536 | /* this packet has an implicit state index. If we've |
| 537 | * had a line error since the last time we got an |
| 538 | * explicit state index, we have to toss the packet. */ |
| 539 | if (comp->flags & SLF_TOSS) { |
| 540 | INCR(sls_tossed) |
| 541 | return (-1); |
| 542 | } |
| 543 | } |
| 544 | cs = &comp->rstate[comp->last_recv]; |
| 545 | hlen = cs->cs_ip.ip_hl << 2; |
| 546 | th = (struct tcphdr *)&((u_char *)&cs->cs_ip)[hlen]; |
| 547 | th->th_sum = htons((*cp << 8) | cp[1]); |
| 548 | cp += 2; |
| 549 | if (changes & TCP_PUSH_BIT) |
| 550 | th->th_flags |= TH_PUSH; |
| 551 | else |
| 552 | th->th_flags &=~ TH_PUSH; |
| 553 | |
| 554 | switch (changes & SPECIALS_MASK) { |
| 555 | case SPECIAL_I: |
| 556 | { |
| 557 | u_int i = ntohs(cs->cs_ip.ip_len) - cs->cs_hlen; |
| 558 | th->th_ack = htonl(ntohl(th->th_ack) + i); |
| 559 | th->th_seq = htonl(ntohl(th->th_seq) + i); |
| 560 | } |
| 561 | break; |
| 562 | |
| 563 | case SPECIAL_D: |
| 564 | th->th_seq = htonl(ntohl(th->th_seq) + ntohs(cs->cs_ip.ip_len) |
| 565 | - cs->cs_hlen); |
| 566 | break; |
| 567 | |
| 568 | default: |
| 569 | if (changes & NEW_U) { |
| 570 | th->th_flags |= TH_URG; |
| 571 | DECODEU(th->th_urp) |
| 572 | } else |
| 573 | th->th_flags &=~ TH_URG; |
| 574 | if (changes & NEW_W) |
| 575 | DECODES(th->th_win) |
| 576 | if (changes & NEW_A) |
| 577 | DECODEL(th->th_ack) |
| 578 | if (changes & NEW_S) |
| 579 | DECODEL(th->th_seq) |
| 580 | break; |
| 581 | } |
| 582 | if (changes & NEW_I) { |
| 583 | DECODES(cs->cs_ip.ip_id) |
| 584 | } else |
| 585 | cs->cs_ip.ip_id = htons(ntohs(cs->cs_ip.ip_id) + 1); |
| 586 | |
| 587 | /* |
| 588 | * At this point, cp points to the first byte of data in the |
| 589 | * packet. Fill in the IP total length and update the IP |
| 590 | * header checksum. |
| 591 | */ |
| 592 | vjlen = cp - buf; |
| 593 | buflen -= vjlen; |
| 594 | if (buflen < 0) |
| 595 | /* we must have dropped some characters (crc should detect |
| 596 | * this but the old slip framing won't) */ |
| 597 | goto bad; |
| 598 | |
| 599 | total_len += cs->cs_hlen - vjlen; |
| 600 | cs->cs_ip.ip_len = htons(total_len); |
| 601 | |
| 602 | /* recompute the ip header checksum */ |
| 603 | bp = (uint16_t *) &cs->cs_ip; |
| 604 | cs->cs_ip.ip_sum = 0; |
| 605 | for (changes = 0; hlen > 0; hlen -= 2) |
| 606 | changes += *bp++; |
| 607 | changes = (changes & 0xffff) + (changes >> 16); |
| 608 | changes = (changes & 0xffff) + (changes >> 16); |
| 609 | cs->cs_ip.ip_sum = ~ changes; |
| 610 | |
| 611 | *hdrp = (u_char *) &cs->cs_ip; |
| 612 | *hlenp = cs->cs_hlen; |
| 613 | return vjlen; |
| 614 | |
| 615 | bad: |
| 616 | comp->flags |= SLF_TOSS; |
| 617 | INCR(sls_errorin) |
| 618 | return (-1); |
| 619 | } |
| 620 | #endif |
| 621 | |
| 622 | MODULE(MODULE_CLASS_MISC, slcompress, NULL); |
| 623 | |
| 624 | static int |
| 625 | slcompress_modcmd(modcmd_t cmd, void *arg) |
| 626 | { |
| 627 | switch (cmd) { |
| 628 | case MODULE_CMD_INIT: |
| 629 | case MODULE_CMD_FINI: |
| 630 | #ifdef INET |
| 631 | return 0; |
| 632 | #endif |
| 633 | case MODULE_CMD_STAT: |
| 634 | case MODULE_CMD_AUTOUNLOAD: |
| 635 | default: |
| 636 | return ENOTTY; |
| 637 | } |
| 638 | } |
| 639 | |