[85a0f07] | 1 | /* |
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| 2 | * Definitions for tcp compression routines. |
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| 3 | * |
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| 4 | * Copyright (c) 1989 Regents of the University of California. |
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| 5 | * All rights reserved. |
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| 6 | * |
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| 7 | * Redistribution and use in source and binary forms, with or without |
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| 8 | * modification, are permitted provided that the following conditions |
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| 9 | * are met: |
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| 10 | * 1. Redistributions of source code must retain the above copyright |
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| 11 | * notice, this list of conditions and the following disclaimer. |
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| 12 | * 2. Redistributions in binary form must reproduce the above copyright |
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| 13 | * notice, this list of conditions and the following disclaimer in the |
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| 14 | * documentation and/or other materials provided with the distribution. |
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| 15 | * 3. All advertising materials mentioning features or use of this software |
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| 16 | * must display the following acknowledgement: |
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| 17 | * This product includes software developed by the University of |
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| 18 | * California, Berkeley and its contributors. |
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| 19 | * 4. Neither the name of the University nor the names of its contributors |
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| 20 | * may be used to endorse or promote products derived from this software |
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| 21 | * without specific prior written permission. |
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| 22 | * |
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| 23 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
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| 24 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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| 25 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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| 26 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
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| 27 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
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| 28 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
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| 29 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
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| 30 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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| 31 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
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| 32 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
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| 33 | * SUCH DAMAGE. |
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| 34 | * |
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| 35 | * Van Jacobson (van@helios.ee.lbl.gov), Dec 31, 1989: |
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| 36 | * - Initial distribution. |
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| 37 | * |
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| 38 | * From: slcompress.h 7.4 90/06/28 |
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| 39 | * $Id$ |
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| 40 | */ |
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| 41 | |
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| 42 | #ifndef _NET_PPPCOMPRESS_H_ |
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| 43 | #define _NET_PPPCOMPRESS_H_ |
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| 44 | |
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| 45 | #define MAX_STATES 16 /* must be > 2 and < 256 */ |
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| 46 | #define MAX_HDR MLEN /* XXX 4bsd-ism: should really be 128 */ |
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| 47 | |
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| 48 | /* |
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| 49 | * Compressed packet format: |
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| 50 | * |
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| 51 | * The first octet contains the packet type (top 3 bits), TCP |
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| 52 | * 'push' bit, and flags that indicate which of the 4 TCP sequence |
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| 53 | * numbers have changed (bottom 5 bits). The next octet is a |
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| 54 | * conversation number that associates a saved IP/TCP header with |
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| 55 | * the compressed packet. The next two octets are the TCP checksum |
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| 56 | * from the original datagram. The next 0 to 15 octets are |
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| 57 | * sequence number changes, one change per bit set in the header |
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| 58 | * (there may be no changes and there are two special cases where |
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| 59 | * the receiver implicitly knows what changed -- see below). |
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| 60 | * |
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| 61 | * There are 5 numbers which can change (they are always inserted |
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| 62 | * in the following order): TCP urgent pointer, window, |
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| 63 | * acknowlegement, sequence number and IP ID. (The urgent pointer |
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| 64 | * is different from the others in that its value is sent, not the |
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| 65 | * change in value.) Since typical use of SLIP links is biased |
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| 66 | * toward small packets (see comments on MTU/MSS below), changes |
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| 67 | * use a variable length coding with one octet for numbers in the |
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| 68 | * range 1 - 255 and 3 octets (0, MSB, LSB) for numbers in the |
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| 69 | * range 256 - 65535 or 0. (If the change in sequence number or |
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| 70 | * ack is more than 65535, an uncompressed packet is sent.) |
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| 71 | */ |
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| 72 | |
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| 73 | /* |
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| 74 | * Packet types (must not conflict with IP protocol version) |
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| 75 | * |
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| 76 | * The top nibble of the first octet is the packet type. There are |
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| 77 | * three possible types: IP (not proto TCP or tcp with one of the |
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| 78 | * control flags set); uncompressed TCP (a normal IP/TCP packet but |
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| 79 | * with the 8-bit protocol field replaced by an 8-bit connection id -- |
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| 80 | * this type of packet syncs the sender & receiver); and compressed |
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| 81 | * TCP (described above). |
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| 82 | * |
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| 83 | * LSB of 4-bit field is TCP "PUSH" bit (a worthless anachronism) and |
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| 84 | * is logically part of the 4-bit "changes" field that follows. Top |
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| 85 | * three bits are actual packet type. For backward compatibility |
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| 86 | * and in the interest of conserving bits, numbers are chosen so the |
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| 87 | * IP protocol version number (4) which normally appears in this nibble |
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| 88 | * means "IP packet". |
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| 89 | */ |
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| 90 | |
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| 91 | /* packet types */ |
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| 92 | #define TYPE_IP 0x40 |
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| 93 | #define TYPE_UNCOMPRESSED_TCP 0x70 |
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| 94 | #define TYPE_COMPRESSED_TCP 0x80 |
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| 95 | #define TYPE_ERROR 0x00 |
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| 96 | |
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| 97 | /* Bits in first octet of compressed packet */ |
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| 98 | #define NEW_C 0x40 /* flag bits for what changed in a packet */ |
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| 99 | #define NEW_I 0x20 |
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| 100 | #define NEW_S 0x08 |
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| 101 | #define NEW_A 0x04 |
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| 102 | #define NEW_W 0x02 |
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| 103 | #define NEW_U 0x01 |
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| 104 | |
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| 105 | /* reserved, special-case values of above */ |
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| 106 | #define SPECIAL_I (NEW_S|NEW_W|NEW_U) /* echoed interactive traffic */ |
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| 107 | #define SPECIAL_D (NEW_S|NEW_A|NEW_W|NEW_U) /* unidirectional data */ |
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| 108 | #define SPECIALS_MASK (NEW_S|NEW_A|NEW_W|NEW_U) |
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| 109 | |
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| 110 | #define TCP_PUSH_BIT 0x10 |
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| 111 | |
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| 112 | |
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| 113 | /* |
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| 114 | * "state" data for each active tcp conversation on the wire. This is |
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| 115 | * basically a copy of the entire IP/TCP header from the last packet |
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| 116 | * we saw from the conversation together with a small identifier |
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| 117 | * the transmit & receive ends of the line use to locate saved header. |
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| 118 | */ |
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| 119 | struct cstate { |
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| 120 | struct cstate *cs_next; /* next most recently used cstate (xmit only) */ |
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| 121 | u_short cs_hlen; /* size of hdr (receive only) */ |
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| 122 | u_char cs_id; /* connection # associated with this state */ |
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| 123 | u_char cs_filler; |
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| 124 | union { |
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| 125 | char csu_hdr[MAX_HDR]; |
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| 126 | struct ip csu_ip; /* ip/tcp hdr from most recent packet */ |
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| 127 | } slcs_u; |
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| 128 | }; |
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| 129 | #define cs_ip slcs_u.csu_ip |
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| 130 | #define cs_hdr slcs_u.csu_hdr |
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| 131 | |
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| 132 | /* |
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| 133 | * all the state data for one serial line (we need one of these |
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| 134 | * per line). |
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| 135 | */ |
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| 136 | struct vjcompress { |
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| 137 | struct cstate *last_cs; /* most recently used tstate */ |
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| 138 | u_char last_recv; /* last rcvd conn. id */ |
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| 139 | u_char last_xmit; /* last sent conn. id */ |
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| 140 | u_short flags; |
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| 141 | #ifndef SL_NO_STATS |
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| 142 | int sls_packets; /* outbound packets */ |
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| 143 | int sls_compressed; /* outbound compressed packets */ |
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| 144 | int sls_searches; /* searches for connection state */ |
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| 145 | int sls_misses; /* times couldn't find conn. state */ |
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| 146 | int sls_uncompressedin; /* inbound uncompressed packets */ |
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| 147 | int sls_compressedin; /* inbound compressed packets */ |
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| 148 | int sls_errorin; /* inbound unknown type packets */ |
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| 149 | int sls_tossed; /* inbound packets tossed because of error */ |
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| 150 | #endif |
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| 151 | struct cstate tstate[MAX_STATES]; /* xmit connection states */ |
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| 152 | struct cstate rstate[MAX_STATES]; /* receive connection states */ |
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| 153 | }; |
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| 154 | /* flag values */ |
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| 155 | #define SLF_TOSS 1 /* tossing rcvd frames because of input err */ |
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| 156 | |
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| 157 | void vj_compress_init __P((struct vjcompress *, int)); |
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| 158 | u_int vj_compress_tcp __P((struct mbuf *, |
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| 159 | struct ip *, struct vjcompress *, int)); |
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| 160 | int vj_uncompress_tcp __P((u_char **, int, u_int, struct vjcompress *)); |
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| 161 | int vj_uncompress_tcp_core __P((u_char *, int, int, u_int, |
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| 162 | struct vjcompress *, u_char **, u_int *)); |
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| 163 | |
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| 164 | #endif /* _NET_PPPCOMPRESS_H_ */ |
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