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606 |
jeremybenn |
/*
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* Routines to compress and uncompess tcp packets (for transmission
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* over low speed serial lines.
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*
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* Copyright (c) 1989 Regents of the University of California.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms are permitted
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* provided that the above copyright notice and this paragraph are
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* duplicated in all such forms and that any documentation,
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* advertising materials, and other materials related to such
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* distribution and use acknowledge that the software was developed
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* by the University of California, Berkeley. The name of the
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* University may not be used to endorse or promote products derived
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* from this software without specific prior written permission.
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
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* WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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*
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* Van Jacobson (van@helios.ee.lbl.gov), Dec 31, 1989:
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* Initial distribution.
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*
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* Modified June 1993 by Paul Mackerras, paulus@cs.anu.edu.au,
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* so that the entire packet being decompressed doesn't have
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* to be in contiguous memory (just the compressed header).
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*
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* Modified March 1998 by Guy Lancaster, glanca@gesn.com,
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* for a 16 bit processor.
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*/
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| 31 |
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#include "lwip/opt.h"
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| 32 |
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| 33 |
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#if PPP_SUPPORT /* don't build if not configured for use in lwipopts.h */
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| 35 |
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#include "ppp.h"
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#include "pppdebug.h"
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| 38 |
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#include "vj.h"
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| 39 |
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| 40 |
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#include <string.h>
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#if VJ_SUPPORT
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| 44 |
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#if LINK_STATS
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#define INCR(counter) ++comp->stats.counter
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#else
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| 47 |
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#define INCR(counter)
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| 48 |
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#endif
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| 49 |
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| 50 |
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#if defined(NO_CHAR_BITFIELDS)
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| 51 |
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#define getip_hl(base) ((base).ip_hl_v&0xf)
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| 52 |
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#define getth_off(base) (((base).th_x2_off&0xf0)>>4)
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| 53 |
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#else
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| 54 |
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#define getip_hl(base) ((base).ip_hl)
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| 55 |
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#define getth_off(base) ((base).th_off)
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| 56 |
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#endif
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| 57 |
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| 58 |
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void
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| 59 |
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vj_compress_init(struct vjcompress *comp)
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| 60 |
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{
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| 61 |
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register u_int i;
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| 62 |
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register struct cstate *tstate = comp->tstate;
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| 63 |
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| 64 |
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#if MAX_SLOTS == 0
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| 65 |
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memset((char *)comp, 0, sizeof(*comp));
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| 66 |
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#endif
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comp->maxSlotIndex = MAX_SLOTS - 1;
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| 68 |
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comp->compressSlot = 0; /* Disable slot ID compression by default. */
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| 69 |
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for (i = MAX_SLOTS - 1; i > 0; --i) {
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| 70 |
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tstate[i].cs_id = i;
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| 71 |
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tstate[i].cs_next = &tstate[i - 1];
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| 72 |
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}
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| 73 |
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tstate[0].cs_next = &tstate[MAX_SLOTS - 1];
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| 74 |
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tstate[0].cs_id = 0;
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comp->last_cs = &tstate[0];
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comp->last_recv = 255;
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| 77 |
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comp->last_xmit = 255;
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| 78 |
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comp->flags = VJF_TOSS;
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}
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| 81 |
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| 82 |
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/* ENCODE encodes a number that is known to be non-zero. ENCODEZ
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* checks for zero (since zero has to be encoded in the long, 3 byte
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* form).
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*/
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| 86 |
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#define ENCODE(n) { \
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| 87 |
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if ((u_short)(n) >= 256) { \
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| 88 |
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*cp++ = 0; \
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| 89 |
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cp[1] = (n); \
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| 90 |
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cp[0] = (n) >> 8; \
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| 91 |
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cp += 2; \
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| 92 |
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} else { \
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| 93 |
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*cp++ = (n); \
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| 94 |
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} \
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| 95 |
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}
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| 96 |
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#define ENCODEZ(n) { \
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| 97 |
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if ((u_short)(n) >= 256 || (u_short)(n) == 0) { \
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| 98 |
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*cp++ = 0; \
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| 99 |
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cp[1] = (n); \
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| 100 |
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cp[0] = (n) >> 8; \
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| 101 |
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cp += 2; \
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| 102 |
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} else { \
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| 103 |
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*cp++ = (n); \
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| 104 |
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} \
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| 105 |
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}
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| 106 |
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| 107 |
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#define DECODEL(f) { \
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if (*cp == 0) {\
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u32_t tmp = ntohl(f) + ((cp[1] << 8) | cp[2]); \
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| 110 |
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(f) = htonl(tmp); \
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| 111 |
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cp += 3; \
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} else { \
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u32_t tmp = ntohl(f) + (u32_t)*cp++; \
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(f) = htonl(tmp); \
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| 115 |
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} \
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| 116 |
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}
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| 118 |
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#define DECODES(f) { \
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| 119 |
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if (*cp == 0) {\
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u_short tmp = ntohs(f) + (((u_short)cp[1] << 8) | cp[2]); \
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| 121 |
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(f) = htons(tmp); \
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cp += 3; \
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} else { \
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u_short tmp = ntohs(f) + (u_short)*cp++; \
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(f) = htons(tmp); \
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| 126 |
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} \
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}
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| 128 |
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| 129 |
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#define DECODEU(f) { \
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| 130 |
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if (*cp == 0) {\
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(f) = htons(((u_short)cp[1] << 8) | cp[2]); \
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cp += 3; \
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} else { \
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(f) = htons((u_short)*cp++); \
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| 135 |
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} \
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| 136 |
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}
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| 138 |
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/*
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* vj_compress_tcp - Attempt to do Van Jacobson header compression on a
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* packet. This assumes that nb and comp are not null and that the first
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| 141 |
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* buffer of the chain contains a valid IP header.
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| 142 |
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* Return the VJ type code indicating whether or not the packet was
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* compressed.
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| 144 |
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*/
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| 145 |
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u_int
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| 146 |
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vj_compress_tcp(struct vjcompress *comp, struct pbuf *pb)
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| 147 |
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{
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| 148 |
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register struct ip *ip = (struct ip *)pb->payload;
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| 149 |
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register struct cstate *cs = comp->last_cs->cs_next;
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| 150 |
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register u_short hlen = getip_hl(*ip);
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| 151 |
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register struct tcphdr *oth;
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| 152 |
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register struct tcphdr *th;
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| 153 |
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register u_short deltaS, deltaA;
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| 154 |
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register u_long deltaL;
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| 155 |
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register u_int changes = 0;
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| 156 |
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u_char new_seq[16];
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| 157 |
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register u_char *cp = new_seq;
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| 159 |
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/*
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* Check that the packet is IP proto TCP.
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*/
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| 162 |
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if (ip->ip_p != IPPROTO_TCP) {
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| 163 |
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return (TYPE_IP);
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| 164 |
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}
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| 165 |
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| 166 |
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/*
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* Bail if this is an IP fragment or if the TCP packet isn't
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| 168 |
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* `compressible' (i.e., ACK isn't set or some other control bit is
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| 169 |
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* set).
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| 170 |
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*/
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| 171 |
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if ((ip->ip_off & htons(0x3fff)) || pb->tot_len < 40) {
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| 172 |
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return (TYPE_IP);
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| 173 |
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}
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| 174 |
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th = (struct tcphdr *)&((long *)ip)[hlen];
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| 175 |
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if ((th->th_flags & (TCP_SYN|TCP_FIN|TCP_RST|TCP_ACK)) != TCP_ACK) {
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| 176 |
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return (TYPE_IP);
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| 177 |
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}
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| 178 |
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/*
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| 179 |
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* Packet is compressible -- we're going to send either a
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| 180 |
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* COMPRESSED_TCP or UNCOMPRESSED_TCP packet. Either way we need
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| 181 |
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* to locate (or create) the connection state. Special case the
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| 182 |
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* most recently used connection since it's most likely to be used
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| 183 |
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* again & we don't have to do any reordering if it's used.
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| 184 |
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*/
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| 185 |
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INCR(vjs_packets);
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| 186 |
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if (ip->ip_src.s_addr != cs->cs_ip.ip_src.s_addr
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| 187 |
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|| ip->ip_dst.s_addr != cs->cs_ip.ip_dst.s_addr
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| 188 |
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|| *(long *)th != ((long *)&cs->cs_ip)[getip_hl(cs->cs_ip)]) {
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| 189 |
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/*
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| 190 |
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* Wasn't the first -- search for it.
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| 191 |
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*
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| 192 |
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* States are kept in a circularly linked list with
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| 193 |
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* last_cs pointing to the end of the list. The
|
| 194 |
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* list is kept in lru order by moving a state to the
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| 195 |
|
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* head of the list whenever it is referenced. Since
|
| 196 |
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* the list is short and, empirically, the connection
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| 197 |
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* we want is almost always near the front, we locate
|
| 198 |
|
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* states via linear search. If we don't find a state
|
| 199 |
|
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* for the datagram, the oldest state is (re-)used.
|
| 200 |
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*/
|
| 201 |
|
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register struct cstate *lcs;
|
| 202 |
|
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register struct cstate *lastcs = comp->last_cs;
|
| 203 |
|
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|
| 204 |
|
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do {
|
| 205 |
|
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lcs = cs; cs = cs->cs_next;
|
| 206 |
|
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INCR(vjs_searches);
|
| 207 |
|
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if (ip->ip_src.s_addr == cs->cs_ip.ip_src.s_addr
|
| 208 |
|
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&& ip->ip_dst.s_addr == cs->cs_ip.ip_dst.s_addr
|
| 209 |
|
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&& *(long *)th == ((long *)&cs->cs_ip)[getip_hl(cs->cs_ip)]) {
|
| 210 |
|
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goto found;
|
| 211 |
|
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}
|
| 212 |
|
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} while (cs != lastcs);
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| 213 |
|
|
|
| 214 |
|
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/*
|
| 215 |
|
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* Didn't find it -- re-use oldest cstate. Send an
|
| 216 |
|
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* uncompressed packet that tells the other side what
|
| 217 |
|
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* connection number we're using for this conversation.
|
| 218 |
|
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* Note that since the state list is circular, the oldest
|
| 219 |
|
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* state points to the newest and we only need to set
|
| 220 |
|
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* last_cs to update the lru linkage.
|
| 221 |
|
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*/
|
| 222 |
|
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INCR(vjs_misses);
|
| 223 |
|
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comp->last_cs = lcs;
|
| 224 |
|
|
hlen += getth_off(*th);
|
| 225 |
|
|
hlen <<= 2;
|
| 226 |
|
|
/* Check that the IP/TCP headers are contained in the first buffer. */
|
| 227 |
|
|
if (hlen > pb->len) {
|
| 228 |
|
|
return (TYPE_IP);
|
| 229 |
|
|
}
|
| 230 |
|
|
goto uncompressed;
|
| 231 |
|
|
|
| 232 |
|
|
found:
|
| 233 |
|
|
/*
|
| 234 |
|
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* Found it -- move to the front on the connection list.
|
| 235 |
|
|
*/
|
| 236 |
|
|
if (cs == lastcs) {
|
| 237 |
|
|
comp->last_cs = lcs;
|
| 238 |
|
|
} else {
|
| 239 |
|
|
lcs->cs_next = cs->cs_next;
|
| 240 |
|
|
cs->cs_next = lastcs->cs_next;
|
| 241 |
|
|
lastcs->cs_next = cs;
|
| 242 |
|
|
}
|
| 243 |
|
|
}
|
| 244 |
|
|
|
| 245 |
|
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oth = (struct tcphdr *)&((long *)&cs->cs_ip)[hlen];
|
| 246 |
|
|
deltaS = hlen;
|
| 247 |
|
|
hlen += getth_off(*th);
|
| 248 |
|
|
hlen <<= 2;
|
| 249 |
|
|
/* Check that the IP/TCP headers are contained in the first buffer. */
|
| 250 |
|
|
if (hlen > pb->len) {
|
| 251 |
|
|
PPPDEBUG((LOG_INFO, "vj_compress_tcp: header len %d spans buffers\n", hlen));
|
| 252 |
|
|
return (TYPE_IP);
|
| 253 |
|
|
}
|
| 254 |
|
|
|
| 255 |
|
|
/*
|
| 256 |
|
|
* Make sure that only what we expect to change changed. The first
|
| 257 |
|
|
* line of the `if' checks the IP protocol version, header length &
|
| 258 |
|
|
* type of service. The 2nd line checks the "Don't fragment" bit.
|
| 259 |
|
|
* The 3rd line checks the time-to-live and protocol (the protocol
|
| 260 |
|
|
* check is unnecessary but costless). The 4th line checks the TCP
|
| 261 |
|
|
* header length. The 5th line checks IP options, if any. The 6th
|
| 262 |
|
|
* line checks TCP options, if any. If any of these things are
|
| 263 |
|
|
* different between the previous & current datagram, we send the
|
| 264 |
|
|
* current datagram `uncompressed'.
|
| 265 |
|
|
*/
|
| 266 |
|
|
if (((u_short *)ip)[0] != ((u_short *)&cs->cs_ip)[0]
|
| 267 |
|
|
|| ((u_short *)ip)[3] != ((u_short *)&cs->cs_ip)[3]
|
| 268 |
|
|
|| ((u_short *)ip)[4] != ((u_short *)&cs->cs_ip)[4]
|
| 269 |
|
|
|| getth_off(*th) != getth_off(*oth)
|
| 270 |
|
|
|| (deltaS > 5 && BCMP(ip + 1, &cs->cs_ip + 1, (deltaS - 5) << 2))
|
| 271 |
|
|
|| (getth_off(*th) > 5 && BCMP(th + 1, oth + 1, (getth_off(*th) - 5) << 2))) {
|
| 272 |
|
|
goto uncompressed;
|
| 273 |
|
|
}
|
| 274 |
|
|
|
| 275 |
|
|
/*
|
| 276 |
|
|
* Figure out which of the changing fields changed. The
|
| 277 |
|
|
* receiver expects changes in the order: urgent, window,
|
| 278 |
|
|
* ack, seq (the order minimizes the number of temporaries
|
| 279 |
|
|
* needed in this section of code).
|
| 280 |
|
|
*/
|
| 281 |
|
|
if (th->th_flags & TCP_URG) {
|
| 282 |
|
|
deltaS = ntohs(th->th_urp);
|
| 283 |
|
|
ENCODEZ(deltaS);
|
| 284 |
|
|
changes |= NEW_U;
|
| 285 |
|
|
} else if (th->th_urp != oth->th_urp) {
|
| 286 |
|
|
/* argh! URG not set but urp changed -- a sensible
|
| 287 |
|
|
* implementation should never do this but RFC793
|
| 288 |
|
|
* doesn't prohibit the change so we have to deal
|
| 289 |
|
|
* with it. */
|
| 290 |
|
|
goto uncompressed;
|
| 291 |
|
|
}
|
| 292 |
|
|
|
| 293 |
|
|
if ((deltaS = (u_short)(ntohs(th->th_win) - ntohs(oth->th_win))) != 0) {
|
| 294 |
|
|
ENCODE(deltaS);
|
| 295 |
|
|
changes |= NEW_W;
|
| 296 |
|
|
}
|
| 297 |
|
|
|
| 298 |
|
|
if ((deltaL = ntohl(th->th_ack) - ntohl(oth->th_ack)) != 0) {
|
| 299 |
|
|
if (deltaL > 0xffff) {
|
| 300 |
|
|
goto uncompressed;
|
| 301 |
|
|
}
|
| 302 |
|
|
deltaA = (u_short)deltaL;
|
| 303 |
|
|
ENCODE(deltaA);
|
| 304 |
|
|
changes |= NEW_A;
|
| 305 |
|
|
}
|
| 306 |
|
|
|
| 307 |
|
|
if ((deltaL = ntohl(th->th_seq) - ntohl(oth->th_seq)) != 0) {
|
| 308 |
|
|
if (deltaL > 0xffff) {
|
| 309 |
|
|
goto uncompressed;
|
| 310 |
|
|
}
|
| 311 |
|
|
deltaS = (u_short)deltaL;
|
| 312 |
|
|
ENCODE(deltaS);
|
| 313 |
|
|
changes |= NEW_S;
|
| 314 |
|
|
}
|
| 315 |
|
|
|
| 316 |
|
|
switch(changes) {
|
| 317 |
|
|
case 0:
|
| 318 |
|
|
/*
|
| 319 |
|
|
* Nothing changed. If this packet contains data and the
|
| 320 |
|
|
* last one didn't, this is probably a data packet following
|
| 321 |
|
|
* an ack (normal on an interactive connection) and we send
|
| 322 |
|
|
* it compressed. Otherwise it's probably a retransmit,
|
| 323 |
|
|
* retransmitted ack or window probe. Send it uncompressed
|
| 324 |
|
|
* in case the other side missed the compressed version.
|
| 325 |
|
|
*/
|
| 326 |
|
|
if (ip->ip_len != cs->cs_ip.ip_len &&
|
| 327 |
|
|
ntohs(cs->cs_ip.ip_len) == hlen) {
|
| 328 |
|
|
break;
|
| 329 |
|
|
}
|
| 330 |
|
|
|
| 331 |
|
|
/* (fall through) */
|
| 332 |
|
|
|
| 333 |
|
|
case SPECIAL_I:
|
| 334 |
|
|
case SPECIAL_D:
|
| 335 |
|
|
/*
|
| 336 |
|
|
* actual changes match one of our special case encodings --
|
| 337 |
|
|
* send packet uncompressed.
|
| 338 |
|
|
*/
|
| 339 |
|
|
goto uncompressed;
|
| 340 |
|
|
|
| 341 |
|
|
case NEW_S|NEW_A:
|
| 342 |
|
|
if (deltaS == deltaA && deltaS == ntohs(cs->cs_ip.ip_len) - hlen) {
|
| 343 |
|
|
/* special case for echoed terminal traffic */
|
| 344 |
|
|
changes = SPECIAL_I;
|
| 345 |
|
|
cp = new_seq;
|
| 346 |
|
|
}
|
| 347 |
|
|
break;
|
| 348 |
|
|
|
| 349 |
|
|
case NEW_S:
|
| 350 |
|
|
if (deltaS == ntohs(cs->cs_ip.ip_len) - hlen) {
|
| 351 |
|
|
/* special case for data xfer */
|
| 352 |
|
|
changes = SPECIAL_D;
|
| 353 |
|
|
cp = new_seq;
|
| 354 |
|
|
}
|
| 355 |
|
|
break;
|
| 356 |
|
|
}
|
| 357 |
|
|
|
| 358 |
|
|
deltaS = (u_short)(ntohs(ip->ip_id) - ntohs(cs->cs_ip.ip_id));
|
| 359 |
|
|
if (deltaS != 1) {
|
| 360 |
|
|
ENCODEZ(deltaS);
|
| 361 |
|
|
changes |= NEW_I;
|
| 362 |
|
|
}
|
| 363 |
|
|
if (th->th_flags & TCP_PSH) {
|
| 364 |
|
|
changes |= TCP_PUSH_BIT;
|
| 365 |
|
|
}
|
| 366 |
|
|
/*
|
| 367 |
|
|
* Grab the cksum before we overwrite it below. Then update our
|
| 368 |
|
|
* state with this packet's header.
|
| 369 |
|
|
*/
|
| 370 |
|
|
deltaA = ntohs(th->th_sum);
|
| 371 |
|
|
BCOPY(ip, &cs->cs_ip, hlen);
|
| 372 |
|
|
|
| 373 |
|
|
/*
|
| 374 |
|
|
* We want to use the original packet as our compressed packet.
|
| 375 |
|
|
* (cp - new_seq) is the number of bytes we need for compressed
|
| 376 |
|
|
* sequence numbers. In addition we need one byte for the change
|
| 377 |
|
|
* mask, one for the connection id and two for the tcp checksum.
|
| 378 |
|
|
* So, (cp - new_seq) + 4 bytes of header are needed. hlen is how
|
| 379 |
|
|
* many bytes of the original packet to toss so subtract the two to
|
| 380 |
|
|
* get the new packet size.
|
| 381 |
|
|
*/
|
| 382 |
|
|
deltaS = (u_short)(cp - new_seq);
|
| 383 |
|
|
if (!comp->compressSlot || comp->last_xmit != cs->cs_id) {
|
| 384 |
|
|
comp->last_xmit = cs->cs_id;
|
| 385 |
|
|
hlen -= deltaS + 4;
|
| 386 |
|
|
if(pbuf_header(pb, -hlen)){
|
| 387 |
|
|
/* Can we cope with this failing? Just assert for now */
|
| 388 |
|
|
LWIP_ASSERT("pbuf_header failed\n", 0);
|
| 389 |
|
|
}
|
| 390 |
|
|
cp = (u_char *)pb->payload;
|
| 391 |
|
|
*cp++ = changes | NEW_C;
|
| 392 |
|
|
*cp++ = cs->cs_id;
|
| 393 |
|
|
} else {
|
| 394 |
|
|
hlen -= deltaS + 3;
|
| 395 |
|
|
if(pbuf_header(pb, -hlen)) {
|
| 396 |
|
|
/* Can we cope with this failing? Just assert for now */
|
| 397 |
|
|
LWIP_ASSERT("pbuf_header failed\n", 0);
|
| 398 |
|
|
}
|
| 399 |
|
|
cp = (u_char *)pb->payload;
|
| 400 |
|
|
*cp++ = changes;
|
| 401 |
|
|
}
|
| 402 |
|
|
*cp++ = deltaA >> 8;
|
| 403 |
|
|
*cp++ = deltaA;
|
| 404 |
|
|
BCOPY(new_seq, cp, deltaS);
|
| 405 |
|
|
INCR(vjs_compressed);
|
| 406 |
|
|
return (TYPE_COMPRESSED_TCP);
|
| 407 |
|
|
|
| 408 |
|
|
/*
|
| 409 |
|
|
* Update connection state cs & send uncompressed packet (that is,
|
| 410 |
|
|
* a regular ip/tcp packet but with the 'conversation id' we hope
|
| 411 |
|
|
* to use on future compressed packets in the protocol field).
|
| 412 |
|
|
*/
|
| 413 |
|
|
uncompressed:
|
| 414 |
|
|
BCOPY(ip, &cs->cs_ip, hlen);
|
| 415 |
|
|
ip->ip_p = cs->cs_id;
|
| 416 |
|
|
comp->last_xmit = cs->cs_id;
|
| 417 |
|
|
return (TYPE_UNCOMPRESSED_TCP);
|
| 418 |
|
|
}
|
| 419 |
|
|
|
| 420 |
|
|
/*
|
| 421 |
|
|
* Called when we may have missed a packet.
|
| 422 |
|
|
*/
|
| 423 |
|
|
void
|
| 424 |
|
|
vj_uncompress_err(struct vjcompress *comp)
|
| 425 |
|
|
{
|
| 426 |
|
|
comp->flags |= VJF_TOSS;
|
| 427 |
|
|
INCR(vjs_errorin);
|
| 428 |
|
|
}
|
| 429 |
|
|
|
| 430 |
|
|
/*
|
| 431 |
|
|
* "Uncompress" a packet of type TYPE_UNCOMPRESSED_TCP.
|
| 432 |
|
|
* Return 0 on success, -1 on failure.
|
| 433 |
|
|
*/
|
| 434 |
|
|
int
|
| 435 |
|
|
vj_uncompress_uncomp(struct pbuf *nb, struct vjcompress *comp)
|
| 436 |
|
|
{
|
| 437 |
|
|
register u_int hlen;
|
| 438 |
|
|
register struct cstate *cs;
|
| 439 |
|
|
register struct ip *ip;
|
| 440 |
|
|
|
| 441 |
|
|
ip = (struct ip *)nb->payload;
|
| 442 |
|
|
hlen = getip_hl(*ip) << 2;
|
| 443 |
|
|
if (ip->ip_p >= MAX_SLOTS
|
| 444 |
|
|
|| hlen + sizeof(struct tcphdr) > nb->len
|
| 445 |
|
|
|| (hlen += getth_off(*((struct tcphdr *)&((char *)ip)[hlen])) << 2)
|
| 446 |
|
|
> nb->len
|
| 447 |
|
|
|| hlen > MAX_HDR) {
|
| 448 |
|
|
PPPDEBUG((LOG_INFO, "vj_uncompress_uncomp: bad cid=%d, hlen=%d buflen=%d\n",
|
| 449 |
|
|
ip->ip_p, hlen, nb->len));
|
| 450 |
|
|
comp->flags |= VJF_TOSS;
|
| 451 |
|
|
INCR(vjs_errorin);
|
| 452 |
|
|
return -1;
|
| 453 |
|
|
}
|
| 454 |
|
|
cs = &comp->rstate[comp->last_recv = ip->ip_p];
|
| 455 |
|
|
comp->flags &=~ VJF_TOSS;
|
| 456 |
|
|
ip->ip_p = IPPROTO_TCP;
|
| 457 |
|
|
BCOPY(ip, &cs->cs_ip, hlen);
|
| 458 |
|
|
cs->cs_hlen = hlen;
|
| 459 |
|
|
INCR(vjs_uncompressedin);
|
| 460 |
|
|
return 0;
|
| 461 |
|
|
}
|
| 462 |
|
|
|
| 463 |
|
|
/*
|
| 464 |
|
|
* Uncompress a packet of type TYPE_COMPRESSED_TCP.
|
| 465 |
|
|
* The packet is composed of a buffer chain and the first buffer
|
| 466 |
|
|
* must contain an accurate chain length.
|
| 467 |
|
|
* The first buffer must include the entire compressed TCP/IP header.
|
| 468 |
|
|
* This procedure replaces the compressed header with the uncompressed
|
| 469 |
|
|
* header and returns the length of the VJ header.
|
| 470 |
|
|
*/
|
| 471 |
|
|
int
|
| 472 |
|
|
vj_uncompress_tcp(struct pbuf **nb, struct vjcompress *comp)
|
| 473 |
|
|
{
|
| 474 |
|
|
u_char *cp;
|
| 475 |
|
|
struct tcphdr *th;
|
| 476 |
|
|
struct cstate *cs;
|
| 477 |
|
|
u_short *bp;
|
| 478 |
|
|
struct pbuf *n0 = *nb;
|
| 479 |
|
|
u32_t tmp;
|
| 480 |
|
|
u_int vjlen, hlen, changes;
|
| 481 |
|
|
|
| 482 |
|
|
INCR(vjs_compressedin);
|
| 483 |
|
|
cp = (u_char *)n0->payload;
|
| 484 |
|
|
changes = *cp++;
|
| 485 |
|
|
if (changes & NEW_C) {
|
| 486 |
|
|
/*
|
| 487 |
|
|
* Make sure the state index is in range, then grab the state.
|
| 488 |
|
|
* If we have a good state index, clear the 'discard' flag.
|
| 489 |
|
|
*/
|
| 490 |
|
|
if (*cp >= MAX_SLOTS) {
|
| 491 |
|
|
PPPDEBUG((LOG_INFO, "vj_uncompress_tcp: bad cid=%d\n", *cp));
|
| 492 |
|
|
goto bad;
|
| 493 |
|
|
}
|
| 494 |
|
|
|
| 495 |
|
|
comp->flags &=~ VJF_TOSS;
|
| 496 |
|
|
comp->last_recv = *cp++;
|
| 497 |
|
|
} else {
|
| 498 |
|
|
/*
|
| 499 |
|
|
* this packet has an implicit state index. If we've
|
| 500 |
|
|
* had a line error since the last time we got an
|
| 501 |
|
|
* explicit state index, we have to toss the packet.
|
| 502 |
|
|
*/
|
| 503 |
|
|
if (comp->flags & VJF_TOSS) {
|
| 504 |
|
|
PPPDEBUG((LOG_INFO, "vj_uncompress_tcp: tossing\n"));
|
| 505 |
|
|
INCR(vjs_tossed);
|
| 506 |
|
|
return (-1);
|
| 507 |
|
|
}
|
| 508 |
|
|
}
|
| 509 |
|
|
cs = &comp->rstate[comp->last_recv];
|
| 510 |
|
|
hlen = getip_hl(cs->cs_ip) << 2;
|
| 511 |
|
|
th = (struct tcphdr *)&((u_char *)&cs->cs_ip)[hlen];
|
| 512 |
|
|
th->th_sum = htons((*cp << 8) | cp[1]);
|
| 513 |
|
|
cp += 2;
|
| 514 |
|
|
if (changes & TCP_PUSH_BIT) {
|
| 515 |
|
|
th->th_flags |= TCP_PSH;
|
| 516 |
|
|
} else {
|
| 517 |
|
|
th->th_flags &=~ TCP_PSH;
|
| 518 |
|
|
}
|
| 519 |
|
|
|
| 520 |
|
|
switch (changes & SPECIALS_MASK) {
|
| 521 |
|
|
case SPECIAL_I:
|
| 522 |
|
|
{
|
| 523 |
|
|
register u32_t i = ntohs(cs->cs_ip.ip_len) - cs->cs_hlen;
|
| 524 |
|
|
/* some compilers can't nest inline assembler.. */
|
| 525 |
|
|
tmp = ntohl(th->th_ack) + i;
|
| 526 |
|
|
th->th_ack = htonl(tmp);
|
| 527 |
|
|
tmp = ntohl(th->th_seq) + i;
|
| 528 |
|
|
th->th_seq = htonl(tmp);
|
| 529 |
|
|
}
|
| 530 |
|
|
break;
|
| 531 |
|
|
|
| 532 |
|
|
case SPECIAL_D:
|
| 533 |
|
|
/* some compilers can't nest inline assembler.. */
|
| 534 |
|
|
tmp = ntohl(th->th_seq) + ntohs(cs->cs_ip.ip_len) - cs->cs_hlen;
|
| 535 |
|
|
th->th_seq = htonl(tmp);
|
| 536 |
|
|
break;
|
| 537 |
|
|
|
| 538 |
|
|
default:
|
| 539 |
|
|
if (changes & NEW_U) {
|
| 540 |
|
|
th->th_flags |= TCP_URG;
|
| 541 |
|
|
DECODEU(th->th_urp);
|
| 542 |
|
|
} else {
|
| 543 |
|
|
th->th_flags &=~ TCP_URG;
|
| 544 |
|
|
}
|
| 545 |
|
|
if (changes & NEW_W) {
|
| 546 |
|
|
DECODES(th->th_win);
|
| 547 |
|
|
}
|
| 548 |
|
|
if (changes & NEW_A) {
|
| 549 |
|
|
DECODEL(th->th_ack);
|
| 550 |
|
|
}
|
| 551 |
|
|
if (changes & NEW_S) {
|
| 552 |
|
|
DECODEL(th->th_seq);
|
| 553 |
|
|
}
|
| 554 |
|
|
break;
|
| 555 |
|
|
}
|
| 556 |
|
|
if (changes & NEW_I) {
|
| 557 |
|
|
DECODES(cs->cs_ip.ip_id);
|
| 558 |
|
|
} else {
|
| 559 |
|
|
cs->cs_ip.ip_id = ntohs(cs->cs_ip.ip_id) + 1;
|
| 560 |
|
|
cs->cs_ip.ip_id = htons(cs->cs_ip.ip_id);
|
| 561 |
|
|
}
|
| 562 |
|
|
|
| 563 |
|
|
/*
|
| 564 |
|
|
* At this point, cp points to the first byte of data in the
|
| 565 |
|
|
* packet. Fill in the IP total length and update the IP
|
| 566 |
|
|
* header checksum.
|
| 567 |
|
|
*/
|
| 568 |
|
|
vjlen = (u_short)(cp - (u_char*)n0->payload);
|
| 569 |
|
|
if (n0->len < vjlen) {
|
| 570 |
|
|
/*
|
| 571 |
|
|
* We must have dropped some characters (crc should detect
|
| 572 |
|
|
* this but the old slip framing won't)
|
| 573 |
|
|
*/
|
| 574 |
|
|
PPPDEBUG((LOG_INFO, "vj_uncompress_tcp: head buffer %d too short %d\n",
|
| 575 |
|
|
n0->len, vjlen));
|
| 576 |
|
|
goto bad;
|
| 577 |
|
|
}
|
| 578 |
|
|
|
| 579 |
|
|
#if BYTE_ORDER == LITTLE_ENDIAN
|
| 580 |
|
|
tmp = n0->tot_len - vjlen + cs->cs_hlen;
|
| 581 |
|
|
cs->cs_ip.ip_len = htons(tmp);
|
| 582 |
|
|
#else
|
| 583 |
|
|
cs->cs_ip.ip_len = htons(n0->tot_len - vjlen + cs->cs_hlen);
|
| 584 |
|
|
#endif
|
| 585 |
|
|
|
| 586 |
|
|
/* recompute the ip header checksum */
|
| 587 |
|
|
bp = (u_short *) &cs->cs_ip;
|
| 588 |
|
|
cs->cs_ip.ip_sum = 0;
|
| 589 |
|
|
for (tmp = 0; hlen > 0; hlen -= 2) {
|
| 590 |
|
|
tmp += *bp++;
|
| 591 |
|
|
}
|
| 592 |
|
|
tmp = (tmp & 0xffff) + (tmp >> 16);
|
| 593 |
|
|
tmp = (tmp & 0xffff) + (tmp >> 16);
|
| 594 |
|
|
cs->cs_ip.ip_sum = (u_short)(~tmp);
|
| 595 |
|
|
|
| 596 |
|
|
/* Remove the compressed header and prepend the uncompressed header. */
|
| 597 |
|
|
if(pbuf_header(n0, -((s16_t)(vjlen)))) {
|
| 598 |
|
|
/* Can we cope with this failing? Just assert for now */
|
| 599 |
|
|
LWIP_ASSERT("pbuf_header failed\n", 0);
|
| 600 |
|
|
goto bad;
|
| 601 |
|
|
}
|
| 602 |
|
|
|
| 603 |
|
|
if(LWIP_MEM_ALIGN(n0->payload) != n0->payload) {
|
| 604 |
|
|
struct pbuf *np, *q;
|
| 605 |
|
|
u8_t *bufptr;
|
| 606 |
|
|
|
| 607 |
|
|
np = pbuf_alloc(PBUF_RAW, n0->len + cs->cs_hlen, PBUF_POOL);
|
| 608 |
|
|
if(!np) {
|
| 609 |
|
|
PPPDEBUG((LOG_WARNING, "vj_uncompress_tcp: realign failed\n"));
|
| 610 |
|
|
goto bad;
|
| 611 |
|
|
}
|
| 612 |
|
|
|
| 613 |
|
|
if(pbuf_header(np, -cs->cs_hlen)) {
|
| 614 |
|
|
/* Can we cope with this failing? Just assert for now */
|
| 615 |
|
|
LWIP_ASSERT("pbuf_header failed\n", 0);
|
| 616 |
|
|
goto bad;
|
| 617 |
|
|
}
|
| 618 |
|
|
|
| 619 |
|
|
bufptr = n0->payload;
|
| 620 |
|
|
for(q = np; q != NULL; q = q->next) {
|
| 621 |
|
|
MEMCPY(q->payload, bufptr, q->len);
|
| 622 |
|
|
bufptr += q->len;
|
| 623 |
|
|
}
|
| 624 |
|
|
|
| 625 |
|
|
if(n0->next) {
|
| 626 |
|
|
pbuf_chain(np, n0->next);
|
| 627 |
|
|
pbuf_dechain(n0);
|
| 628 |
|
|
}
|
| 629 |
|
|
pbuf_free(n0);
|
| 630 |
|
|
n0 = np;
|
| 631 |
|
|
}
|
| 632 |
|
|
|
| 633 |
|
|
if(pbuf_header(n0, cs->cs_hlen)) {
|
| 634 |
|
|
struct pbuf *np;
|
| 635 |
|
|
|
| 636 |
|
|
LWIP_ASSERT("vj_uncompress_tcp: cs->cs_hlen <= PBUF_POOL_BUFSIZE", cs->cs_hlen <= PBUF_POOL_BUFSIZE);
|
| 637 |
|
|
np = pbuf_alloc(PBUF_RAW, cs->cs_hlen, PBUF_POOL);
|
| 638 |
|
|
if(!np) {
|
| 639 |
|
|
PPPDEBUG((LOG_WARNING, "vj_uncompress_tcp: prepend failed\n"));
|
| 640 |
|
|
goto bad;
|
| 641 |
|
|
}
|
| 642 |
|
|
pbuf_cat(np, n0);
|
| 643 |
|
|
n0 = np;
|
| 644 |
|
|
}
|
| 645 |
|
|
LWIP_ASSERT("n0->len >= cs->cs_hlen", n0->len >= cs->cs_hlen);
|
| 646 |
|
|
MEMCPY(n0->payload, &cs->cs_ip, cs->cs_hlen);
|
| 647 |
|
|
|
| 648 |
|
|
*nb = n0;
|
| 649 |
|
|
|
| 650 |
|
|
return vjlen;
|
| 651 |
|
|
|
| 652 |
|
|
bad:
|
| 653 |
|
|
comp->flags |= VJF_TOSS;
|
| 654 |
|
|
INCR(vjs_errorin);
|
| 655 |
|
|
return (-1);
|
| 656 |
|
|
}
|
| 657 |
|
|
|
| 658 |
|
|
#endif /* VJ_SUPPORT */
|
| 659 |
|
|
|
| 660 |
|
|
#endif /* PPP_SUPPORT */
|
