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1 | /* -*-c-*- |
2 | * |
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3 | * Simple packet buffering |
4 | * |
5 | * (c) 2000 Straylight/Edgeware |
6 | */ |
7 | |
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8 | /*----- Licensing notice --------------------------------------------------* |
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9 | * |
10 | * This file is part of the mLib utilities library. |
11 | * |
12 | * mLib is free software; you can redistribute it and/or modify |
13 | * it under the terms of the GNU Library General Public License as |
14 | * published by the Free Software Foundation; either version 2 of the |
15 | * License, or (at your option) any later version. |
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16 | * |
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17 | * mLib is distributed in the hope that it will be useful, |
18 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
20 | * GNU Library General Public License for more details. |
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21 | * |
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22 | * You should have received a copy of the GNU Library General Public |
23 | * License along with mLib; if not, write to the Free |
24 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
25 | * MA 02111-1307, USA. |
26 | */ |
27 | |
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28 | /*----- Header files ------------------------------------------------------*/ |
29 | |
30 | #include <stdio.h> |
31 | #include <stdlib.h> |
32 | #include <string.h> |
33 | |
34 | #include "alloc.h" |
35 | #include "arena.h" |
36 | #include "pkbuf.h" |
37 | |
38 | /*----- Main code ---------------------------------------------------------*/ |
39 | |
40 | /* --- @pkbuf_flush@ --- * |
41 | * |
42 | * Arguments: @pkbuf *pk@ = pointer to buffer block |
43 | * @octet *p@ = pointer to where to start searching |
44 | * @size_t len@ = length of new material added |
45 | * |
46 | * Returns: --- |
47 | * |
48 | * Use: Flushes any complete packets in a packet buffer. New |
49 | * material is assumed to have been added starting at @p@. If |
50 | * @p@ is null, then the scan starts at the beginning of the |
51 | * buffer, and the size of data already in the buffer is used in |
52 | * place of @len@. |
53 | * |
54 | * It is assumed that the buffer is initially enabled. You |
55 | * shouldn't be contributing data to a disabled buffer anyway. |
56 | * However, the buffer handler may at some point disable itself, |
57 | * and @pkbuf_flush@ can cope with this eventuality. Any |
58 | * pending data is left at the start of the buffer and can be |
59 | * flushed out by calling @pkbuf_flush(b, 0, 0)@ if the buffer |
60 | * is ever re-enabled. |
61 | */ |
62 | |
63 | void pkbuf_flush(pkbuf *pk, octet *p, size_t len) |
64 | { |
65 | size_t l; |
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66 | size_t o, keep; |
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67 | |
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68 | if (pk->f & PKBUF_CLOSE) { |
69 | pk->func(0, 0, pk, 0, pk->p); |
70 | return; |
71 | } |
72 | |
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73 | /* --- Initialize variables as necessary --- */ |
74 | |
75 | if (!p) { |
76 | p = pk->buf; |
77 | len = pk->len; |
78 | } |
79 | l = p + len - pk->buf; |
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80 | o = 0; |
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81 | |
82 | /* --- Now grind through any packets which have accumulated --- */ |
83 | |
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84 | pk->len = l; |
85 | while (l >= pk->want) { |
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86 | size_t sz = pk->want; |
87 | |
88 | /* --- Pass a packet to the user handler --- */ |
89 | |
90 | keep = 0; |
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91 | pk->func(pk->buf + o, sz, pk, &keep, pk->p); |
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92 | |
93 | /* --- Adjust all the pointers for the next packet --- */ |
94 | |
95 | sz -= keep; |
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96 | o += sz; |
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97 | l -= sz; |
98 | |
99 | /* --- Abort here if disabled --- */ |
100 | |
101 | if (!(pk->f & PKBUF_ENABLE)) |
102 | break; |
103 | } |
104 | |
105 | /* --- Shunt data around in the buffer --- */ |
106 | |
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107 | if (o > 0 && l != 0) |
108 | memmove(pk->buf, pk->buf + o, l); |
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109 | pk->len = l; |
110 | } |
111 | |
112 | /* --- @pkbuf_close@ --- * |
113 | * |
114 | * Arguments: @pkbuf *pk@ = pointer to buffer block |
115 | * |
116 | * Returns: --- |
117 | * |
118 | * Use: Informs the client that no more data is likely to arrive. If |
119 | * there is a partial packet in the buffer, it is discarded. |
120 | */ |
121 | |
122 | void pkbuf_close(pkbuf *pk) |
123 | { |
124 | if (pk->buf) { |
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125 | x_free(pk->a, pk->buf); |
126 | pk->buf = 0; |
127 | } |
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128 | pk->f |= PKBUF_CLOSE; |
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129 | if (pk->f & PKBUF_ENABLE) |
130 | pk->func(0, 0, pk, 0, pk->p); |
131 | } |
132 | |
133 | /* --- @pkbuf_free@ --- * |
134 | * |
135 | * Arguments: @pkbuf *pk@ = pointer to buffer block |
136 | * @octet **p@ = output pointer to free space |
137 | * |
138 | * Returns: Free buffer size. |
139 | * |
140 | * Use: Returns the free portion of a packet buffer. Data can then |
141 | * be written to this portion, and split out into packets by |
142 | * calling @pkbuf_flush@. A buffer is allocated if none |
143 | * currently exists. |
144 | */ |
145 | |
146 | size_t pkbuf_free(pkbuf *pk, octet **p) |
147 | { |
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148 | if (!pk->buf) |
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149 | pk->buf = x_alloc(pk->a, pk->sz); |
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150 | *p = pk->buf + pk->len; |
151 | return (pk->sz - pk->len); |
152 | } |
153 | |
154 | /* --- @pkbuf_snarf@ --- * |
155 | * |
156 | * Arguments: @pkbuf *pk@ = pointer to buffer block |
157 | * @const void *p@ = pointer to input data buffer |
158 | * @size_t sz@ = size of data in input buffer |
159 | * |
160 | * Returns: --- |
161 | * |
162 | * Use: Snarfs the data from the input buffer and spits it out as |
163 | * packets. This interface ignores the complexities of dealing |
164 | * with disablement: you should be using @pkbuf_free@ to |
165 | * contribute data if you want to cope with that. |
166 | */ |
167 | |
168 | void pkbuf_snarf(pkbuf *pk, const void *p, size_t sz) |
169 | { |
170 | const octet *pp = p; |
171 | while (sz && (pk->f & PKBUF_ENABLE)) { |
172 | size_t bsz; |
173 | octet *bp; |
174 | |
175 | bsz = pkbuf_free(pk, &bp); |
176 | if (bsz > sz) |
177 | bsz = sz; |
178 | memcpy(bp, pp, bsz); |
179 | pkbuf_flush(pk, bp, bsz); |
180 | pp += bsz; |
181 | sz -= bsz; |
182 | } |
183 | } |
184 | |
185 | /* --- @pkbuf_want@ --- * |
186 | * |
187 | * Arguments: @pkbuf *pk@ = pointer to buffer block |
188 | * @size_t want@ = how many octets wanted for next packet |
189 | * |
190 | * Returns: --- |
191 | * |
192 | * Use: Sets the desired size for the next packet to be read. If |
193 | * it's larger than the current buffer, the buffer is extended. |
194 | */ |
195 | |
196 | void pkbuf_want(pkbuf *pk, size_t want) |
197 | { |
198 | pk->want = want; |
199 | if (want > pk->sz) { |
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200 | do pk->sz <<= 1; while (want > pk->sz); |
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201 | if (pk->buf) { |
202 | if (pk->len) |
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203 | pk->buf = x_realloc(pk->a, pk->buf, pk->sz, pk->len); |
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204 | else { |
205 | x_free(pk->a, pk->buf); |
206 | pk->buf = 0; |
207 | } |
208 | } |
209 | } |
210 | } |
211 | |
212 | /* --- @pkbuf_init@ --- * |
213 | * |
214 | * Arguments: @pkbuf *pk@ = pointer to buffer block |
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215 | * @pkbuf *func@ = handler function |
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216 | * @void *p@ = argument pointer for @func@ |
217 | * |
218 | * Returns: --- |
219 | * |
220 | * Use: Initializes a packet buffer block. Any packets are passed to |
221 | * the provided function for handling. |
222 | */ |
223 | |
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224 | void pkbuf_init(pkbuf *pk, pkbuf_func *func, void *p) |
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225 | { |
226 | pk->func = func; |
227 | pk->p = p; |
228 | pk->len = 0; |
229 | pk->f = PKBUF_ENABLE; |
230 | pk->buf = 0; |
231 | pk->sz = 256; |
232 | pk->want = 1; |
233 | pk->a = arena_global; |
234 | } |
235 | |
236 | /* --- @pkbuf_destroy@ --- * |
237 | * |
238 | * Arguments: @pkbuf *pk@ = pointer to buffer block |
239 | * |
240 | * Returns: --- |
241 | * |
242 | * Use: Deallocates a line buffer and frees any resources it owned. |
243 | */ |
244 | |
245 | void pkbuf_destroy(pkbuf *pk) |
246 | { |
247 | if (pk->buf) { |
248 | x_free(pk->a, pk->buf); |
249 | pk->buf = 0; |
250 | } |
251 | } |
252 | |
253 | /*----- That's all, folks -------------------------------------------------*/ |