1 | /* $Id$ */ |
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2 | |
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3 | /* Because this code is derived from the 4.3BSD compress source: |
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4 | * |
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5 | * |
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6 | * Copyright (c) 1985, 1986 The Regents of the University of California. |
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7 | * All rights reserved. |
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8 | * |
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9 | * This code is derived from software contributed to Berkeley by |
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10 | * James A. Woods, derived from original work by Spencer Thomas |
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11 | * and Joseph Orost. |
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12 | * |
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13 | * Redistribution and use in source and binary forms, with or without |
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14 | * modification, are permitted provided that the following conditions |
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15 | * are met: |
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16 | * 1. Redistributions of source code must retain the above copyright |
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17 | * notice, this list of conditions and the following disclaimer. |
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18 | * 2. Redistributions in binary form must reproduce the above copyright |
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19 | * notice, this list of conditions and the following disclaimer in the |
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20 | * documentation and/or other materials provided with the distribution. |
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21 | * 3. All advertising materials mentioning features or use of this software |
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22 | * must display the following acknowledgement: |
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23 | * This product includes software developed by the University of |
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24 | * California, Berkeley and its contributors. |
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25 | * 4. Neither the name of the University nor the names of its contributors |
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26 | * may be used to endorse or promote products derived from this software |
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27 | * without specific prior written permission. |
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28 | * |
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29 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
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30 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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31 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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32 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
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33 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
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34 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
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35 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
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36 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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37 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
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38 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
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39 | * SUCH DAMAGE. |
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40 | */ |
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41 | |
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42 | /* |
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43 | * This version is for use with mbufs on BSD-derived systems. |
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44 | */ |
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45 | |
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46 | #include <sys/param.h> |
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47 | #include <sys/types.h> |
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48 | #include <sys/systm.h> |
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49 | #include <sys/mbuf.h> |
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50 | #include <sys/socket.h> |
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51 | #include <net/if.h> |
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52 | #include <net/if_types.h> |
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53 | #include <net/ppp_defs.h> |
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54 | #include <net/if_ppp.h> |
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55 | |
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56 | #define PACKETPTR struct mbuf * |
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57 | #include <net/ppp-comp.h> |
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58 | |
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59 | #if DO_BSD_COMPRESS |
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60 | /* |
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61 | * PPP "BSD compress" compression |
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62 | * The differences between this compression and the classic BSD LZW |
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63 | * source are obvious from the requirement that the classic code worked |
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64 | * with files while this handles arbitrarily long streams that |
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65 | * are broken into packets. They are: |
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66 | * |
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67 | * When the code size expands, a block of junk is not emitted by |
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68 | * the compressor and not expected by the decompressor. |
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69 | * |
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70 | * New codes are not necessarily assigned every time an old |
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71 | * code is output by the compressor. This is because a packet |
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72 | * end forces a code to be emitted, but does not imply that a |
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73 | * new sequence has been seen. |
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74 | * |
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75 | * The compression ratio is checked at the first end of a packet |
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76 | * after the appropriate gap. Besides simplifying and speeding |
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77 | * things up, this makes it more likely that the transmitter |
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78 | * and receiver will agree when the dictionary is cleared when |
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79 | * compression is not going well. |
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80 | */ |
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81 | |
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82 | /* |
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83 | * A dictionary for doing BSD compress. |
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84 | */ |
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85 | struct bsd_db { |
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86 | int totlen; /* length of this structure */ |
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87 | u_int hsize; /* size of the hash table */ |
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88 | u_char hshift; /* used in hash function */ |
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89 | u_char n_bits; /* current bits/code */ |
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90 | u_char maxbits; |
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91 | u_char debug; |
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92 | u_char unit; |
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93 | u_int16_t seqno; /* sequence # of next packet */ |
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94 | u_int hdrlen; /* header length to preallocate */ |
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95 | u_int mru; |
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96 | u_int maxmaxcode; /* largest valid code */ |
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97 | u_int max_ent; /* largest code in use */ |
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98 | u_int in_count; /* uncompressed bytes, aged */ |
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99 | u_int bytes_out; /* compressed bytes, aged */ |
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100 | u_int ratio; /* recent compression ratio */ |
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101 | u_int checkpoint; /* when to next check the ratio */ |
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102 | u_int clear_count; /* times dictionary cleared */ |
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103 | u_int incomp_count; /* incompressible packets */ |
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104 | u_int incomp_bytes; /* incompressible bytes */ |
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105 | u_int uncomp_count; /* uncompressed packets */ |
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106 | u_int uncomp_bytes; /* uncompressed bytes */ |
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107 | u_int comp_count; /* compressed packets */ |
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108 | u_int comp_bytes; /* compressed bytes */ |
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109 | u_int16_t *lens; /* array of lengths of codes */ |
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110 | struct bsd_dict { |
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111 | union { /* hash value */ |
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112 | u_int32_t fcode; |
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113 | struct { |
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114 | #if BYTE_ORDER == LITTLE_ENDIAN |
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115 | u_int16_t prefix; /* preceding code */ |
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116 | u_char suffix; /* last character of new code */ |
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117 | u_char pad; |
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118 | #else |
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119 | u_char pad; |
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120 | u_char suffix; /* last character of new code */ |
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121 | u_int16_t prefix; /* preceding code */ |
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122 | #endif |
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123 | } hs; |
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124 | } f; |
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125 | u_int16_t codem1; /* output of hash table -1 */ |
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126 | u_int16_t cptr; /* map code to hash table entry */ |
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127 | } dict[1]; |
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128 | }; |
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129 | |
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130 | #define BSD_OVHD 2 /* BSD compress overhead/packet */ |
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131 | #define BSD_INIT_BITS BSD_MIN_BITS |
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132 | |
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133 | static void *bsd_comp_alloc __P((u_char *options, int opt_len)); |
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134 | static void *bsd_decomp_alloc __P((u_char *options, int opt_len)); |
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135 | static void bsd_free __P((void *state)); |
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136 | static int bsd_comp_init __P((void *state, u_char *options, int opt_len, |
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137 | int unit, int hdrlen, int debug)); |
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138 | static int bsd_decomp_init __P((void *state, u_char *options, int opt_len, |
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139 | int unit, int hdrlen, int mru, int debug)); |
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140 | static int bsd_compress __P((void *state, struct mbuf **mret, |
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141 | struct mbuf *mp, int slen, int maxolen)); |
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142 | static void bsd_incomp __P((void *state, struct mbuf *dmsg)); |
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143 | static int bsd_decompress __P((void *state, struct mbuf *cmp, |
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144 | struct mbuf **dmpp)); |
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145 | static void bsd_reset __P((void *state)); |
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146 | static void bsd_comp_stats __P((void *state, struct compstat *stats)); |
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147 | |
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148 | /* |
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149 | * Procedures exported to if_ppp.c. |
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150 | */ |
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151 | struct compressor ppp_bsd_compress = { |
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152 | CI_BSD_COMPRESS, /* compress_proto */ |
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153 | bsd_comp_alloc, /* comp_alloc */ |
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154 | bsd_free, /* comp_free */ |
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155 | bsd_comp_init, /* comp_init */ |
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156 | bsd_reset, /* comp_reset */ |
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157 | bsd_compress, /* compress */ |
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158 | bsd_comp_stats, /* comp_stat */ |
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159 | bsd_decomp_alloc, /* decomp_alloc */ |
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160 | bsd_free, /* decomp_free */ |
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161 | bsd_decomp_init, /* decomp_init */ |
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162 | bsd_reset, /* decomp_reset */ |
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163 | bsd_decompress, /* decompress */ |
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164 | bsd_incomp, /* incomp */ |
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165 | bsd_comp_stats, /* decomp_stat */ |
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166 | }; |
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167 | |
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168 | /* |
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169 | * the next two codes should not be changed lightly, as they must not |
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170 | * lie within the contiguous general code space. |
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171 | */ |
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172 | #define CLEAR 256 /* table clear output code */ |
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173 | #define FIRST 257 /* first free entry */ |
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174 | #define LAST 255 |
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175 | |
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176 | #define MAXCODE(b) ((1 << (b)) - 1) |
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177 | #define BADCODEM1 MAXCODE(BSD_MAX_BITS) |
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178 | |
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179 | #define BSD_HASH(prefix,suffix,hshift) ((((u_int32_t)(suffix)) << (hshift)) \ |
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180 | ^ (u_int32_t)(prefix)) |
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181 | #define BSD_KEY(prefix,suffix) ((((u_int32_t)(suffix)) << 16) \ |
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182 | + (u_int32_t)(prefix)) |
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183 | |
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184 | #define CHECK_GAP 10000 /* Ratio check interval */ |
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185 | |
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186 | #define RATIO_SCALE_LOG 8 |
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187 | #define RATIO_SCALE (1<<RATIO_SCALE_LOG) |
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188 | #define RATIO_MAX (0x7fffffff>>RATIO_SCALE_LOG) |
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189 | |
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190 | static void bsd_clear __P((struct bsd_db *)); |
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191 | static int bsd_check __P((struct bsd_db *)); |
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192 | static void *bsd_alloc __P((u_char *, int, int)); |
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193 | static int bsd_init __P((struct bsd_db *, u_char *, int, int, int, int, |
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194 | int, int)); |
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195 | |
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196 | /* |
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197 | * clear the dictionary |
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198 | */ |
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199 | static void |
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200 | bsd_clear(db) |
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201 | struct bsd_db *db; |
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202 | { |
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203 | db->clear_count++; |
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204 | db->max_ent = FIRST-1; |
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205 | db->n_bits = BSD_INIT_BITS; |
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206 | db->ratio = 0; |
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207 | db->bytes_out = 0; |
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208 | db->in_count = 0; |
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209 | db->checkpoint = CHECK_GAP; |
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210 | } |
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211 | |
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212 | /* |
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213 | * If the dictionary is full, then see if it is time to reset it. |
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214 | * |
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215 | * Compute the compression ratio using fixed-point arithmetic |
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216 | * with 8 fractional bits. |
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217 | * |
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218 | * Since we have an infinite stream instead of a single file, |
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219 | * watch only the local compression ratio. |
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220 | * |
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221 | * Since both peers must reset the dictionary at the same time even in |
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222 | * the absence of CLEAR codes (while packets are incompressible), they |
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223 | * must compute the same ratio. |
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224 | */ |
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225 | static int /* 1=output CLEAR */ |
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226 | bsd_check(db) |
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227 | struct bsd_db *db; |
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228 | { |
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229 | u_int new_ratio; |
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230 | |
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231 | if (db->in_count >= db->checkpoint) { |
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232 | /* age the ratio by limiting the size of the counts */ |
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233 | if (db->in_count >= RATIO_MAX |
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234 | || db->bytes_out >= RATIO_MAX) { |
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235 | db->in_count -= db->in_count/4; |
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236 | db->bytes_out -= db->bytes_out/4; |
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237 | } |
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238 | |
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239 | db->checkpoint = db->in_count + CHECK_GAP; |
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240 | |
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241 | if (db->max_ent >= db->maxmaxcode) { |
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242 | /* Reset the dictionary only if the ratio is worse, |
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243 | * or if it looks as if it has been poisoned |
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244 | * by incompressible data. |
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245 | * |
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246 | * This does not overflow, because |
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247 | * db->in_count <= RATIO_MAX. |
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248 | */ |
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249 | new_ratio = db->in_count << RATIO_SCALE_LOG; |
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250 | if (db->bytes_out != 0) |
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251 | new_ratio /= db->bytes_out; |
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252 | |
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253 | if (new_ratio < db->ratio || new_ratio < 1 * RATIO_SCALE) { |
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254 | bsd_clear(db); |
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255 | return 1; |
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256 | } |
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257 | db->ratio = new_ratio; |
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258 | } |
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259 | } |
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260 | return 0; |
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261 | } |
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262 | |
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263 | /* |
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264 | * Return statistics. |
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265 | */ |
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266 | static void |
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267 | bsd_comp_stats(state, stats) |
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268 | void *state; |
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269 | struct compstat *stats; |
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270 | { |
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271 | struct bsd_db *db = (struct bsd_db *) state; |
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272 | u_int out; |
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273 | |
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274 | stats->unc_bytes = db->uncomp_bytes; |
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275 | stats->unc_packets = db->uncomp_count; |
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276 | stats->comp_bytes = db->comp_bytes; |
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277 | stats->comp_packets = db->comp_count; |
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278 | stats->inc_bytes = db->incomp_bytes; |
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279 | stats->inc_packets = db->incomp_count; |
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280 | stats->ratio = db->in_count; |
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281 | out = db->bytes_out; |
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282 | if (stats->ratio <= 0x7fffff) |
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283 | stats->ratio <<= 8; |
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284 | else |
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285 | out >>= 8; |
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286 | if (out != 0) |
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287 | stats->ratio /= out; |
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288 | } |
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289 | |
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290 | /* |
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291 | * Reset state, as on a CCP ResetReq. |
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292 | */ |
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293 | static void |
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294 | bsd_reset(state) |
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295 | void *state; |
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296 | { |
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297 | struct bsd_db *db = (struct bsd_db *) state; |
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298 | |
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299 | db->seqno = 0; |
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300 | bsd_clear(db); |
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301 | db->clear_count = 0; |
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302 | } |
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303 | |
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304 | /* |
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305 | * Allocate space for a (de) compressor. |
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306 | */ |
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307 | static void * |
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308 | bsd_alloc(options, opt_len, decomp) |
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309 | u_char *options; |
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310 | int opt_len, decomp; |
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311 | { |
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312 | int bits; |
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313 | u_int newlen, hsize, hshift, maxmaxcode; |
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314 | struct bsd_db *db; |
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315 | |
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316 | if (opt_len < CILEN_BSD_COMPRESS || options[0] != CI_BSD_COMPRESS |
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317 | || options[1] != CILEN_BSD_COMPRESS |
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318 | || BSD_VERSION(options[2]) != BSD_CURRENT_VERSION) |
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319 | return NULL; |
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320 | bits = BSD_NBITS(options[2]); |
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321 | switch (bits) { |
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322 | case 9: /* needs 82152 for both directions */ |
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323 | case 10: /* needs 84144 */ |
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324 | case 11: /* needs 88240 */ |
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325 | case 12: /* needs 96432 */ |
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326 | hsize = 5003; |
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327 | hshift = 4; |
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328 | break; |
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329 | case 13: /* needs 176784 */ |
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330 | hsize = 9001; |
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331 | hshift = 5; |
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332 | break; |
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333 | case 14: /* needs 353744 */ |
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334 | hsize = 18013; |
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335 | hshift = 6; |
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336 | break; |
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337 | case 15: /* needs 691440 */ |
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338 | hsize = 35023; |
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339 | hshift = 7; |
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340 | break; |
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341 | case 16: /* needs 1366160--far too much, */ |
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342 | /* hsize = 69001; */ /* and 69001 is too big for cptr */ |
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343 | /* hshift = 8; */ /* in struct bsd_db */ |
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344 | /* break; */ |
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345 | default: |
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346 | return NULL; |
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347 | } |
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348 | |
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349 | maxmaxcode = MAXCODE(bits); |
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350 | newlen = sizeof(*db) + (hsize-1) * (sizeof(db->dict[0])); |
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351 | MALLOC(db, struct bsd_db *, newlen, M_DEVBUF, M_NOWAIT); |
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352 | if (!db) |
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353 | return NULL; |
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354 | bzero(db, sizeof(*db) - sizeof(db->dict)); |
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355 | |
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356 | if (!decomp) { |
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357 | db->lens = NULL; |
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358 | } else { |
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359 | MALLOC(db->lens, u_int16_t *, (maxmaxcode+1) * sizeof(db->lens[0]), |
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360 | M_DEVBUF, M_NOWAIT); |
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361 | if (!db->lens) { |
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362 | FREE(db, M_DEVBUF); |
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363 | return NULL; |
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364 | } |
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365 | } |
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366 | |
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367 | db->totlen = newlen; |
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368 | db->hsize = hsize; |
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369 | db->hshift = hshift; |
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370 | db->maxmaxcode = maxmaxcode; |
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371 | db->maxbits = bits; |
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372 | |
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373 | return (void *) db; |
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374 | } |
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375 | |
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376 | static void |
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377 | bsd_free(state) |
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378 | void *state; |
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379 | { |
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380 | struct bsd_db *db = (struct bsd_db *) state; |
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381 | |
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382 | if (db->lens) |
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383 | FREE(db->lens, M_DEVBUF); |
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384 | FREE(db, M_DEVBUF); |
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385 | } |
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386 | |
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387 | static void * |
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388 | bsd_comp_alloc(options, opt_len) |
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389 | u_char *options; |
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390 | int opt_len; |
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391 | { |
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392 | return bsd_alloc(options, opt_len, 0); |
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393 | } |
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394 | |
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395 | static void * |
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396 | bsd_decomp_alloc(options, opt_len) |
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397 | u_char *options; |
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398 | int opt_len; |
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399 | { |
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400 | return bsd_alloc(options, opt_len, 1); |
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401 | } |
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402 | |
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403 | /* |
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404 | * Initialize the database. |
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405 | */ |
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406 | static int |
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407 | bsd_init(db, options, opt_len, unit, hdrlen, mru, debug, decomp) |
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408 | struct bsd_db *db; |
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409 | u_char *options; |
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410 | int opt_len, unit, hdrlen, mru, debug, decomp; |
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411 | { |
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412 | int i; |
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413 | |
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414 | if (opt_len < CILEN_BSD_COMPRESS || options[0] != CI_BSD_COMPRESS |
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415 | || options[1] != CILEN_BSD_COMPRESS |
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416 | || BSD_VERSION(options[2]) != BSD_CURRENT_VERSION |
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417 | || BSD_NBITS(options[2]) != db->maxbits |
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418 | || (decomp && db->lens == NULL)) |
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419 | return 0; |
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420 | |
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421 | if (decomp) { |
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422 | i = LAST+1; |
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423 | while (i != 0) |
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424 | db->lens[--i] = 1; |
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425 | } |
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426 | i = db->hsize; |
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427 | while (i != 0) { |
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428 | db->dict[--i].codem1 = BADCODEM1; |
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429 | db->dict[i].cptr = 0; |
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430 | } |
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431 | |
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432 | db->unit = unit; |
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433 | db->hdrlen = hdrlen; |
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434 | db->mru = mru; |
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435 | #ifndef DEBUG |
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436 | if (debug) |
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437 | #endif |
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438 | db->debug = 1; |
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439 | |
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440 | bsd_reset(db); |
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441 | |
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442 | return 1; |
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443 | } |
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444 | |
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445 | static int |
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446 | bsd_comp_init(state, options, opt_len, unit, hdrlen, debug) |
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447 | void *state; |
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448 | u_char *options; |
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449 | int opt_len, unit, hdrlen, debug; |
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450 | { |
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451 | return bsd_init((struct bsd_db *) state, options, opt_len, |
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452 | unit, hdrlen, 0, debug, 0); |
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453 | } |
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454 | |
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455 | static int |
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456 | bsd_decomp_init(state, options, opt_len, unit, hdrlen, mru, debug) |
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457 | void *state; |
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458 | u_char *options; |
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459 | int opt_len, unit, hdrlen, mru, debug; |
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460 | { |
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461 | return bsd_init((struct bsd_db *) state, options, opt_len, |
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462 | unit, hdrlen, mru, debug, 1); |
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463 | } |
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464 | |
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465 | |
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466 | /* |
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467 | * compress a packet |
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468 | * One change from the BSD compress command is that when the |
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469 | * code size expands, we do not output a bunch of padding. |
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470 | */ |
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471 | int /* new slen */ |
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472 | bsd_compress(state, mret, mp, slen, maxolen) |
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473 | void *state; |
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474 | struct mbuf **mret; /* return compressed mbuf chain here */ |
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475 | struct mbuf *mp; /* from here */ |
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476 | int slen; /* uncompressed length */ |
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477 | int maxolen; /* max compressed length */ |
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478 | { |
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479 | struct bsd_db *db = (struct bsd_db *) state; |
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480 | int hshift = db->hshift; |
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481 | u_int max_ent = db->max_ent; |
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482 | u_int n_bits = db->n_bits; |
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483 | u_int bitno = 32; |
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484 | u_int32_t accm = 0, fcode; |
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485 | struct bsd_dict *dictp; |
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486 | u_char c; |
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487 | int hval, disp, ent, ilen; |
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488 | u_char *rptr, *wptr; |
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489 | u_char *cp_end; |
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490 | int olen; |
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491 | struct mbuf *m; |
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492 | |
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493 | #define PUTBYTE(v) { \ |
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494 | ++olen; \ |
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495 | if (wptr) { \ |
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496 | *wptr++ = (v); \ |
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497 | if (wptr >= cp_end) { \ |
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498 | m->m_len = wptr - mtod(m, u_char *); \ |
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499 | MGET(m->m_next, M_DONTWAIT, MT_DATA); \ |
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500 | m = m->m_next; \ |
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501 | if (m) { \ |
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502 | m->m_len = 0; \ |
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503 | if (maxolen - olen > MLEN) \ |
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504 | MCLGET(m, M_DONTWAIT); \ |
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505 | wptr = mtod(m, u_char *); \ |
---|
506 | cp_end = wptr + M_TRAILINGSPACE(m); \ |
---|
507 | } else \ |
---|
508 | wptr = NULL; \ |
---|
509 | } \ |
---|
510 | } \ |
---|
511 | } |
---|
512 | |
---|
513 | #define OUTPUT(ent) { \ |
---|
514 | bitno -= n_bits; \ |
---|
515 | accm |= ((ent) << bitno); \ |
---|
516 | do { \ |
---|
517 | PUTBYTE(accm >> 24); \ |
---|
518 | accm <<= 8; \ |
---|
519 | bitno += 8; \ |
---|
520 | } while (bitno <= 24); \ |
---|
521 | } |
---|
522 | |
---|
523 | /* |
---|
524 | * If the protocol is not in the range we're interested in, |
---|
525 | * just return without compressing the packet. If it is, |
---|
526 | * the protocol becomes the first byte to compress. |
---|
527 | */ |
---|
528 | rptr = mtod(mp, u_char *); |
---|
529 | ent = PPP_PROTOCOL(rptr); |
---|
530 | if (ent < 0x21 || ent > 0xf9) { |
---|
531 | *mret = NULL; |
---|
532 | return slen; |
---|
533 | } |
---|
534 | |
---|
535 | /* Don't generate compressed packets which are larger than |
---|
536 | the uncompressed packet. */ |
---|
537 | if (maxolen > slen) |
---|
538 | maxolen = slen; |
---|
539 | |
---|
540 | /* Allocate one mbuf to start with. */ |
---|
541 | MGET(m, M_DONTWAIT, MT_DATA); |
---|
542 | *mret = m; |
---|
543 | if (m != NULL) { |
---|
544 | m->m_len = 0; |
---|
545 | if (maxolen + db->hdrlen > MLEN) |
---|
546 | MCLGET(m, M_DONTWAIT); |
---|
547 | m->m_data += db->hdrlen; |
---|
548 | wptr = mtod(m, u_char *); |
---|
549 | cp_end = wptr + M_TRAILINGSPACE(m); |
---|
550 | } else |
---|
551 | wptr = cp_end = NULL; |
---|
552 | |
---|
553 | /* |
---|
554 | * Copy the PPP header over, changing the protocol, |
---|
555 | * and install the 2-byte packet sequence number. |
---|
556 | */ |
---|
557 | if (wptr) { |
---|
558 | *wptr++ = PPP_ADDRESS(rptr); /* assumes the ppp header is */ |
---|
559 | *wptr++ = PPP_CONTROL(rptr); /* all in one mbuf */ |
---|
560 | *wptr++ = 0; /* change the protocol */ |
---|
561 | *wptr++ = PPP_COMP; |
---|
562 | *wptr++ = db->seqno >> 8; |
---|
563 | *wptr++ = db->seqno; |
---|
564 | } |
---|
565 | ++db->seqno; |
---|
566 | |
---|
567 | olen = 0; |
---|
568 | rptr += PPP_HDRLEN; |
---|
569 | slen = mp->m_len - PPP_HDRLEN; |
---|
570 | ilen = slen + 1; |
---|
571 | for (;;) { |
---|
572 | if (slen <= 0) { |
---|
573 | mp = mp->m_next; |
---|
574 | if (!mp) |
---|
575 | break; |
---|
576 | rptr = mtod(mp, u_char *); |
---|
577 | slen = mp->m_len; |
---|
578 | if (!slen) |
---|
579 | continue; /* handle 0-length buffers */ |
---|
580 | ilen += slen; |
---|
581 | } |
---|
582 | |
---|
583 | slen--; |
---|
584 | c = *rptr++; |
---|
585 | fcode = BSD_KEY(ent, c); |
---|
586 | hval = BSD_HASH(ent, c, hshift); |
---|
587 | dictp = &db->dict[hval]; |
---|
588 | |
---|
589 | /* Validate and then check the entry. */ |
---|
590 | if (dictp->codem1 >= max_ent) |
---|
591 | goto nomatch; |
---|
592 | if (dictp->f.fcode == fcode) { |
---|
593 | ent = dictp->codem1+1; |
---|
594 | continue; /* found (prefix,suffix) */ |
---|
595 | } |
---|
596 | |
---|
597 | /* continue probing until a match or invalid entry */ |
---|
598 | disp = (hval == 0) ? 1 : hval; |
---|
599 | do { |
---|
600 | hval += disp; |
---|
601 | if (hval >= db->hsize) |
---|
602 | hval -= db->hsize; |
---|
603 | dictp = &db->dict[hval]; |
---|
604 | if (dictp->codem1 >= max_ent) |
---|
605 | goto nomatch; |
---|
606 | } while (dictp->f.fcode != fcode); |
---|
607 | ent = dictp->codem1 + 1; /* finally found (prefix,suffix) */ |
---|
608 | continue; |
---|
609 | |
---|
610 | nomatch: |
---|
611 | OUTPUT(ent); /* output the prefix */ |
---|
612 | |
---|
613 | /* code -> hashtable */ |
---|
614 | if (max_ent < db->maxmaxcode) { |
---|
615 | struct bsd_dict *dictp2; |
---|
616 | /* expand code size if needed */ |
---|
617 | if (max_ent >= MAXCODE(n_bits)) |
---|
618 | db->n_bits = ++n_bits; |
---|
619 | |
---|
620 | /* Invalidate old hash table entry using |
---|
621 | * this code, and then take it over. |
---|
622 | */ |
---|
623 | dictp2 = &db->dict[max_ent+1]; |
---|
624 | if (db->dict[dictp2->cptr].codem1 == max_ent) |
---|
625 | db->dict[dictp2->cptr].codem1 = BADCODEM1; |
---|
626 | dictp2->cptr = hval; |
---|
627 | dictp->codem1 = max_ent; |
---|
628 | dictp->f.fcode = fcode; |
---|
629 | |
---|
630 | db->max_ent = ++max_ent; |
---|
631 | } |
---|
632 | ent = c; |
---|
633 | } |
---|
634 | |
---|
635 | OUTPUT(ent); /* output the last code */ |
---|
636 | db->bytes_out += olen; |
---|
637 | db->in_count += ilen; |
---|
638 | if (bitno < 32) |
---|
639 | ++db->bytes_out; /* count complete bytes */ |
---|
640 | |
---|
641 | if (bsd_check(db)) |
---|
642 | OUTPUT(CLEAR); /* do not count the CLEAR */ |
---|
643 | |
---|
644 | /* |
---|
645 | * Pad dribble bits of last code with ones. |
---|
646 | * Do not emit a completely useless byte of ones. |
---|
647 | */ |
---|
648 | if (bitno != 32) |
---|
649 | PUTBYTE((accm | (0xff << (bitno-8))) >> 24); |
---|
650 | |
---|
651 | if (m != NULL) { |
---|
652 | m->m_len = wptr - mtod(m, u_char *); |
---|
653 | m->m_next = NULL; |
---|
654 | } |
---|
655 | |
---|
656 | /* |
---|
657 | * Increase code size if we would have without the packet |
---|
658 | * boundary and as the decompressor will. |
---|
659 | */ |
---|
660 | if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode) |
---|
661 | db->n_bits++; |
---|
662 | |
---|
663 | db->uncomp_bytes += ilen; |
---|
664 | ++db->uncomp_count; |
---|
665 | if (olen + PPP_HDRLEN + BSD_OVHD > maxolen) { |
---|
666 | /* throw away the compressed stuff if it is longer than uncompressed */ |
---|
667 | if (*mret != NULL) { |
---|
668 | m_freem(*mret); |
---|
669 | *mret = NULL; |
---|
670 | } |
---|
671 | ++db->incomp_count; |
---|
672 | db->incomp_bytes += ilen; |
---|
673 | } else { |
---|
674 | ++db->comp_count; |
---|
675 | db->comp_bytes += olen + BSD_OVHD; |
---|
676 | } |
---|
677 | |
---|
678 | return olen + PPP_HDRLEN + BSD_OVHD; |
---|
679 | #undef OUTPUT |
---|
680 | #undef PUTBYTE |
---|
681 | } |
---|
682 | |
---|
683 | |
---|
684 | /* |
---|
685 | * Update the "BSD Compress" dictionary on the receiver for |
---|
686 | * incompressible data by pretending to compress the incoming data. |
---|
687 | */ |
---|
688 | static void |
---|
689 | bsd_incomp(state, dmsg) |
---|
690 | void *state; |
---|
691 | struct mbuf *dmsg; |
---|
692 | { |
---|
693 | struct bsd_db *db = (struct bsd_db *) state; |
---|
694 | u_int hshift = db->hshift; |
---|
695 | u_int max_ent = db->max_ent; |
---|
696 | u_int n_bits = db->n_bits; |
---|
697 | struct bsd_dict *dictp; |
---|
698 | u_int32_t fcode; |
---|
699 | u_char c; |
---|
700 | u_int32_t hval, disp; |
---|
701 | int slen, ilen; |
---|
702 | u_int bitno = 7; |
---|
703 | u_char *rptr; |
---|
704 | u_int ent; |
---|
705 | |
---|
706 | /* |
---|
707 | * If the protocol is not in the range we're interested in, |
---|
708 | * just return without looking at the packet. If it is, |
---|
709 | * the protocol becomes the first byte to "compress". |
---|
710 | */ |
---|
711 | rptr = mtod(dmsg, u_char *); |
---|
712 | ent = PPP_PROTOCOL(rptr); |
---|
713 | if (ent < 0x21 || ent > 0xf9) |
---|
714 | return; |
---|
715 | |
---|
716 | db->seqno++; |
---|
717 | ilen = 1; /* count the protocol as 1 byte */ |
---|
718 | rptr += PPP_HDRLEN; |
---|
719 | slen = dmsg->m_len - PPP_HDRLEN; |
---|
720 | for (;;) { |
---|
721 | if (slen <= 0) { |
---|
722 | dmsg = dmsg->m_next; |
---|
723 | if (!dmsg) |
---|
724 | break; |
---|
725 | rptr = mtod(dmsg, u_char *); |
---|
726 | slen = dmsg->m_len; |
---|
727 | continue; |
---|
728 | } |
---|
729 | ilen += slen; |
---|
730 | |
---|
731 | do { |
---|
732 | c = *rptr++; |
---|
733 | fcode = BSD_KEY(ent, c); |
---|
734 | hval = BSD_HASH(ent, c, hshift); |
---|
735 | dictp = &db->dict[hval]; |
---|
736 | |
---|
737 | /* validate and then check the entry */ |
---|
738 | if (dictp->codem1 >= max_ent) |
---|
739 | goto nomatch; |
---|
740 | if (dictp->f.fcode == fcode) { |
---|
741 | ent = dictp->codem1+1; |
---|
742 | continue; /* found (prefix,suffix) */ |
---|
743 | } |
---|
744 | |
---|
745 | /* continue probing until a match or invalid entry */ |
---|
746 | disp = (hval == 0) ? 1 : hval; |
---|
747 | do { |
---|
748 | hval += disp; |
---|
749 | if (hval >= db->hsize) |
---|
750 | hval -= db->hsize; |
---|
751 | dictp = &db->dict[hval]; |
---|
752 | if (dictp->codem1 >= max_ent) |
---|
753 | goto nomatch; |
---|
754 | } while (dictp->f.fcode != fcode); |
---|
755 | ent = dictp->codem1+1; |
---|
756 | continue; /* finally found (prefix,suffix) */ |
---|
757 | |
---|
758 | nomatch: /* output (count) the prefix */ |
---|
759 | bitno += n_bits; |
---|
760 | |
---|
761 | /* code -> hashtable */ |
---|
762 | if (max_ent < db->maxmaxcode) { |
---|
763 | struct bsd_dict *dictp2; |
---|
764 | /* expand code size if needed */ |
---|
765 | if (max_ent >= MAXCODE(n_bits)) |
---|
766 | db->n_bits = ++n_bits; |
---|
767 | |
---|
768 | /* Invalidate previous hash table entry |
---|
769 | * assigned this code, and then take it over. |
---|
770 | */ |
---|
771 | dictp2 = &db->dict[max_ent+1]; |
---|
772 | if (db->dict[dictp2->cptr].codem1 == max_ent) |
---|
773 | db->dict[dictp2->cptr].codem1 = BADCODEM1; |
---|
774 | dictp2->cptr = hval; |
---|
775 | dictp->codem1 = max_ent; |
---|
776 | dictp->f.fcode = fcode; |
---|
777 | |
---|
778 | db->max_ent = ++max_ent; |
---|
779 | db->lens[max_ent] = db->lens[ent]+1; |
---|
780 | } |
---|
781 | ent = c; |
---|
782 | } while (--slen != 0); |
---|
783 | } |
---|
784 | bitno += n_bits; /* output (count) the last code */ |
---|
785 | db->bytes_out += bitno/8; |
---|
786 | db->in_count += ilen; |
---|
787 | (void)bsd_check(db); |
---|
788 | |
---|
789 | ++db->incomp_count; |
---|
790 | db->incomp_bytes += ilen; |
---|
791 | ++db->uncomp_count; |
---|
792 | db->uncomp_bytes += ilen; |
---|
793 | |
---|
794 | /* Increase code size if we would have without the packet |
---|
795 | * boundary and as the decompressor will. |
---|
796 | */ |
---|
797 | if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode) |
---|
798 | db->n_bits++; |
---|
799 | } |
---|
800 | |
---|
801 | |
---|
802 | /* |
---|
803 | * Decompress "BSD Compress". |
---|
804 | * |
---|
805 | * Because of patent problems, we return DECOMP_ERROR for errors |
---|
806 | * found by inspecting the input data and for system problems, but |
---|
807 | * DECOMP_FATALERROR for any errors which could possibly be said to |
---|
808 | * be being detected "after" decompression. For DECOMP_ERROR, |
---|
809 | * we can issue a CCP reset-request; for DECOMP_FATALERROR, we may be |
---|
810 | * infringing a patent of Motorola's if we do, so we take CCP down |
---|
811 | * instead. |
---|
812 | * |
---|
813 | * Given that the frame has the correct sequence number and a good FCS, |
---|
814 | * errors such as invalid codes in the input most likely indicate a |
---|
815 | * bug, so we return DECOMP_FATALERROR for them in order to turn off |
---|
816 | * compression, even though they are detected by inspecting the input. |
---|
817 | */ |
---|
818 | int |
---|
819 | bsd_decompress(state, cmp, dmpp) |
---|
820 | void *state; |
---|
821 | struct mbuf *cmp, **dmpp; |
---|
822 | { |
---|
823 | struct bsd_db *db = (struct bsd_db *) state; |
---|
824 | u_int max_ent = db->max_ent; |
---|
825 | u_int32_t accm = 0; |
---|
826 | u_int bitno = 32; /* 1st valid bit in accm */ |
---|
827 | u_int n_bits = db->n_bits; |
---|
828 | u_int tgtbitno = 32-n_bits; /* bitno when we have a code */ |
---|
829 | struct bsd_dict *dictp; |
---|
830 | int explen, i, seq, len; |
---|
831 | u_int incode, oldcode, finchar; |
---|
832 | u_char *p, *rptr, *wptr; |
---|
833 | struct mbuf *m, *dmp, *mret; |
---|
834 | int adrs, ctrl, ilen; |
---|
835 | int space, codelen, extra; |
---|
836 | |
---|
837 | /* |
---|
838 | * Save the address/control from the PPP header |
---|
839 | * and then get the sequence number. |
---|
840 | */ |
---|
841 | *dmpp = NULL; |
---|
842 | rptr = mtod(cmp, u_char *); |
---|
843 | adrs = PPP_ADDRESS(rptr); |
---|
844 | ctrl = PPP_CONTROL(rptr); |
---|
845 | rptr += PPP_HDRLEN; |
---|
846 | len = cmp->m_len - PPP_HDRLEN; |
---|
847 | seq = 0; |
---|
848 | for (i = 0; i < 2; ++i) { |
---|
849 | while (len <= 0) { |
---|
850 | cmp = cmp->m_next; |
---|
851 | if (cmp == NULL) |
---|
852 | return DECOMP_ERROR; |
---|
853 | rptr = mtod(cmp, u_char *); |
---|
854 | len = cmp->m_len; |
---|
855 | } |
---|
856 | seq = (seq << 8) + *rptr++; |
---|
857 | --len; |
---|
858 | } |
---|
859 | |
---|
860 | /* |
---|
861 | * Check the sequence number and give up if it differs from |
---|
862 | * the value we're expecting. |
---|
863 | */ |
---|
864 | if (seq != db->seqno) { |
---|
865 | if (db->debug) |
---|
866 | printf("bsd_decomp%d: bad sequence # %d, expected %d\n", |
---|
867 | db->unit, seq, db->seqno - 1); |
---|
868 | return DECOMP_ERROR; |
---|
869 | } |
---|
870 | ++db->seqno; |
---|
871 | |
---|
872 | /* |
---|
873 | * Allocate one mbuf to start with. |
---|
874 | */ |
---|
875 | MGETHDR(dmp, M_DONTWAIT, MT_DATA); |
---|
876 | if (dmp == NULL) |
---|
877 | return DECOMP_ERROR; |
---|
878 | mret = dmp; |
---|
879 | dmp->m_len = 0; |
---|
880 | dmp->m_next = NULL; |
---|
881 | MCLGET(dmp, M_DONTWAIT); |
---|
882 | dmp->m_data += db->hdrlen; |
---|
883 | wptr = mtod(dmp, u_char *); |
---|
884 | space = M_TRAILINGSPACE(dmp) - PPP_HDRLEN + 1; |
---|
885 | |
---|
886 | /* |
---|
887 | * Fill in the ppp header, but not the last byte of the protocol |
---|
888 | * (that comes from the decompressed data). |
---|
889 | */ |
---|
890 | wptr[0] = adrs; |
---|
891 | wptr[1] = ctrl; |
---|
892 | wptr[2] = 0; |
---|
893 | wptr += PPP_HDRLEN - 1; |
---|
894 | |
---|
895 | ilen = len; |
---|
896 | oldcode = CLEAR; |
---|
897 | explen = 0; |
---|
898 | for (;;) { |
---|
899 | if (len == 0) { |
---|
900 | cmp = cmp->m_next; |
---|
901 | if (!cmp) /* quit at end of message */ |
---|
902 | break; |
---|
903 | rptr = mtod(cmp, u_char *); |
---|
904 | len = cmp->m_len; |
---|
905 | ilen += len; |
---|
906 | continue; /* handle 0-length buffers */ |
---|
907 | } |
---|
908 | |
---|
909 | /* |
---|
910 | * Accumulate bytes until we have a complete code. |
---|
911 | * Then get the next code, relying on the 32-bit, |
---|
912 | * unsigned accm to mask the result. |
---|
913 | */ |
---|
914 | bitno -= 8; |
---|
915 | accm |= *rptr++ << bitno; |
---|
916 | --len; |
---|
917 | if (tgtbitno < bitno) |
---|
918 | continue; |
---|
919 | incode = accm >> tgtbitno; |
---|
920 | accm <<= n_bits; |
---|
921 | bitno += n_bits; |
---|
922 | |
---|
923 | if (incode == CLEAR) { |
---|
924 | /* |
---|
925 | * The dictionary must only be cleared at |
---|
926 | * the end of a packet. But there could be an |
---|
927 | * empty mbuf at the end. |
---|
928 | */ |
---|
929 | if (len > 0 || cmp->m_next != NULL) { |
---|
930 | while ((cmp = cmp->m_next) != NULL) |
---|
931 | len += cmp->m_len; |
---|
932 | if (len > 0) { |
---|
933 | m_freem(mret); |
---|
934 | if (db->debug) |
---|
935 | printf("bsd_decomp%d: bad CLEAR\n", db->unit); |
---|
936 | return DECOMP_FATALERROR; /* probably a bug */ |
---|
937 | } |
---|
938 | } |
---|
939 | bsd_clear(db); |
---|
940 | explen = ilen = 0; |
---|
941 | break; |
---|
942 | } |
---|
943 | |
---|
944 | if (incode > max_ent + 2 || incode > db->maxmaxcode |
---|
945 | || (incode > max_ent && oldcode == CLEAR)) { |
---|
946 | m_freem(mret); |
---|
947 | if (db->debug) { |
---|
948 | printf("bsd_decomp%d: bad code 0x%x oldcode=0x%x ", |
---|
949 | db->unit, incode, oldcode); |
---|
950 | printf("max_ent=0x%x explen=%d seqno=%d\n", |
---|
951 | max_ent, explen, db->seqno); |
---|
952 | } |
---|
953 | return DECOMP_FATALERROR; /* probably a bug */ |
---|
954 | } |
---|
955 | |
---|
956 | /* Special case for KwKwK string. */ |
---|
957 | if (incode > max_ent) { |
---|
958 | finchar = oldcode; |
---|
959 | extra = 1; |
---|
960 | } else { |
---|
961 | finchar = incode; |
---|
962 | extra = 0; |
---|
963 | } |
---|
964 | |
---|
965 | codelen = db->lens[finchar]; |
---|
966 | explen += codelen + extra; |
---|
967 | if (explen > db->mru + 1) { |
---|
968 | m_freem(mret); |
---|
969 | if (db->debug) { |
---|
970 | printf("bsd_decomp%d: ran out of mru\n", db->unit); |
---|
971 | #ifdef DEBUG |
---|
972 | while ((cmp = cmp->m_next) != NULL) |
---|
973 | len += cmp->m_len; |
---|
974 | printf(" len=%d, finchar=0x%x, codelen=%d, explen=%d\n", |
---|
975 | len, finchar, codelen, explen); |
---|
976 | #endif |
---|
977 | } |
---|
978 | return DECOMP_FATALERROR; |
---|
979 | } |
---|
980 | |
---|
981 | /* |
---|
982 | * For simplicity, the decoded characters go in a single mbuf, |
---|
983 | * so we allocate a single extra cluster mbuf if necessary. |
---|
984 | */ |
---|
985 | if ((space -= codelen + extra) < 0) { |
---|
986 | dmp->m_len = wptr - mtod(dmp, u_char *); |
---|
987 | MGET(m, M_DONTWAIT, MT_DATA); |
---|
988 | if (m == NULL) { |
---|
989 | m_freem(mret); |
---|
990 | return DECOMP_ERROR; |
---|
991 | } |
---|
992 | m->m_len = 0; |
---|
993 | m->m_next = NULL; |
---|
994 | dmp->m_next = m; |
---|
995 | MCLGET(m, M_DONTWAIT); |
---|
996 | space = M_TRAILINGSPACE(m) - (codelen + extra); |
---|
997 | if (space < 0) { |
---|
998 | /* now that's what I call *compression*. */ |
---|
999 | m_freem(mret); |
---|
1000 | return DECOMP_ERROR; |
---|
1001 | } |
---|
1002 | dmp = m; |
---|
1003 | wptr = mtod(dmp, u_char *); |
---|
1004 | } |
---|
1005 | |
---|
1006 | /* |
---|
1007 | * Decode this code and install it in the decompressed buffer. |
---|
1008 | */ |
---|
1009 | p = (wptr += codelen); |
---|
1010 | while (finchar > LAST) { |
---|
1011 | dictp = &db->dict[db->dict[finchar].cptr]; |
---|
1012 | #ifdef DEBUG |
---|
1013 | if (--codelen <= 0 || dictp->codem1 != finchar-1) |
---|
1014 | goto bad; |
---|
1015 | #endif |
---|
1016 | *--p = dictp->f.hs.suffix; |
---|
1017 | finchar = dictp->f.hs.prefix; |
---|
1018 | } |
---|
1019 | *--p = finchar; |
---|
1020 | |
---|
1021 | #ifdef DEBUG |
---|
1022 | if (--codelen != 0) |
---|
1023 | printf("bsd_decomp%d: short by %d after code 0x%x, max_ent=0x%x\n", |
---|
1024 | db->unit, codelen, incode, max_ent); |
---|
1025 | #endif |
---|
1026 | |
---|
1027 | if (extra) /* the KwKwK case again */ |
---|
1028 | *wptr++ = finchar; |
---|
1029 | |
---|
1030 | /* |
---|
1031 | * If not first code in a packet, and |
---|
1032 | * if not out of code space, then allocate a new code. |
---|
1033 | * |
---|
1034 | * Keep the hash table correct so it can be used |
---|
1035 | * with uncompressed packets. |
---|
1036 | */ |
---|
1037 | if (oldcode != CLEAR && max_ent < db->maxmaxcode) { |
---|
1038 | struct bsd_dict *dictp2; |
---|
1039 | u_int32_t fcode; |
---|
1040 | u_int32_t hval, disp; |
---|
1041 | |
---|
1042 | fcode = BSD_KEY(oldcode,finchar); |
---|
1043 | hval = BSD_HASH(oldcode,finchar,db->hshift); |
---|
1044 | dictp = &db->dict[hval]; |
---|
1045 | |
---|
1046 | /* look for a free hash table entry */ |
---|
1047 | if (dictp->codem1 < max_ent) { |
---|
1048 | disp = (hval == 0) ? 1 : hval; |
---|
1049 | do { |
---|
1050 | hval += disp; |
---|
1051 | if (hval >= db->hsize) |
---|
1052 | hval -= db->hsize; |
---|
1053 | dictp = &db->dict[hval]; |
---|
1054 | } while (dictp->codem1 < max_ent); |
---|
1055 | } |
---|
1056 | |
---|
1057 | /* |
---|
1058 | * Invalidate previous hash table entry |
---|
1059 | * assigned this code, and then take it over |
---|
1060 | */ |
---|
1061 | dictp2 = &db->dict[max_ent+1]; |
---|
1062 | if (db->dict[dictp2->cptr].codem1 == max_ent) { |
---|
1063 | db->dict[dictp2->cptr].codem1 = BADCODEM1; |
---|
1064 | } |
---|
1065 | dictp2->cptr = hval; |
---|
1066 | dictp->codem1 = max_ent; |
---|
1067 | dictp->f.fcode = fcode; |
---|
1068 | |
---|
1069 | db->max_ent = ++max_ent; |
---|
1070 | db->lens[max_ent] = db->lens[oldcode]+1; |
---|
1071 | |
---|
1072 | /* Expand code size if needed. */ |
---|
1073 | if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode) { |
---|
1074 | db->n_bits = ++n_bits; |
---|
1075 | tgtbitno = 32-n_bits; |
---|
1076 | } |
---|
1077 | } |
---|
1078 | oldcode = incode; |
---|
1079 | } |
---|
1080 | dmp->m_len = wptr - mtod(dmp, u_char *); |
---|
1081 | |
---|
1082 | /* |
---|
1083 | * Keep the checkpoint right so that incompressible packets |
---|
1084 | * clear the dictionary at the right times. |
---|
1085 | */ |
---|
1086 | db->bytes_out += ilen; |
---|
1087 | db->in_count += explen; |
---|
1088 | if (bsd_check(db) && db->debug) { |
---|
1089 | printf("bsd_decomp%d: peer should have cleared dictionary\n", |
---|
1090 | db->unit); |
---|
1091 | } |
---|
1092 | |
---|
1093 | ++db->comp_count; |
---|
1094 | db->comp_bytes += ilen + BSD_OVHD; |
---|
1095 | ++db->uncomp_count; |
---|
1096 | db->uncomp_bytes += explen; |
---|
1097 | |
---|
1098 | *dmpp = mret; |
---|
1099 | return DECOMP_OK; |
---|
1100 | |
---|
1101 | #ifdef DEBUG |
---|
1102 | bad: |
---|
1103 | if (codelen <= 0) { |
---|
1104 | printf("bsd_decomp%d: fell off end of chain ", db->unit); |
---|
1105 | printf("0x%x at 0x%x by 0x%x, max_ent=0x%x\n", |
---|
1106 | incode, finchar, db->dict[finchar].cptr, max_ent); |
---|
1107 | } else if (dictp->codem1 != finchar-1) { |
---|
1108 | printf("bsd_decomp%d: bad code chain 0x%x finchar=0x%x ", |
---|
1109 | db->unit, incode, finchar); |
---|
1110 | printf("oldcode=0x%x cptr=0x%x codem1=0x%x\n", oldcode, |
---|
1111 | db->dict[finchar].cptr, dictp->codem1); |
---|
1112 | } |
---|
1113 | m_freem(mret); |
---|
1114 | return DECOMP_FATALERROR; |
---|
1115 | #endif /* DEBUG */ |
---|
1116 | } |
---|
1117 | #endif /* DO_BSD_COMPRESS */ |
---|