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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: pkbuf.c,v 1.4 2001/02/03 16:23:33 mdw Exp $ |
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4 | * |
5 | * Simple packet buffering |
6 | * |
7 | * (c) 2000 Straylight/Edgeware |
8 | */ |
9 | |
10 | /*----- Licensing notice --------------------------------------------------* |
11 | * |
12 | * This file is part of the mLib utilities library. |
13 | * |
14 | * mLib is free software; you can redistribute it and/or modify |
15 | * it under the terms of the GNU Library General Public License as |
16 | * published by the Free Software Foundation; either version 2 of the |
17 | * License, or (at your option) any later version. |
18 | * |
19 | * mLib is distributed in the hope that it will be useful, |
20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
22 | * GNU Library General Public License for more details. |
23 | * |
24 | * You should have received a copy of the GNU Library General Public |
25 | * License along with mLib; if not, write to the Free |
26 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
27 | * MA 02111-1307, USA. |
28 | */ |
29 | |
30 | /*----- Revision history --------------------------------------------------* |
31 | * |
32 | * $Log: pkbuf.c,v $ |
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33 | * Revision 1.4 2001/02/03 16:23:33 mdw |
34 | * Bug fix: handle a disable during a close-induced flush without dumping |
35 | * core. |
36 | * |
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37 | * Revision 1.3 2000/07/16 18:55:45 mdw |
38 | * Remove some stray debugging code. |
39 | * |
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40 | * Revision 1.2 2000/07/16 12:29:16 mdw |
41 | * Change to arena `realloc' interface, to fix a design bug. |
42 | * |
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43 | * Revision 1.1 2000/06/17 10:39:19 mdw |
44 | * Experimental new support for packet buffering. |
45 | * |
46 | */ |
47 | |
48 | /*----- Header files ------------------------------------------------------*/ |
49 | |
50 | #include <stdio.h> |
51 | #include <stdlib.h> |
52 | #include <string.h> |
53 | |
54 | #include "alloc.h" |
55 | #include "arena.h" |
56 | #include "pkbuf.h" |
57 | |
58 | /*----- Main code ---------------------------------------------------------*/ |
59 | |
60 | /* --- @pkbuf_flush@ --- * |
61 | * |
62 | * Arguments: @pkbuf *pk@ = pointer to buffer block |
63 | * @octet *p@ = pointer to where to start searching |
64 | * @size_t len@ = length of new material added |
65 | * |
66 | * Returns: --- |
67 | * |
68 | * Use: Flushes any complete packets in a packet buffer. New |
69 | * material is assumed to have been added starting at @p@. If |
70 | * @p@ is null, then the scan starts at the beginning of the |
71 | * buffer, and the size of data already in the buffer is used in |
72 | * place of @len@. |
73 | * |
74 | * It is assumed that the buffer is initially enabled. You |
75 | * shouldn't be contributing data to a disabled buffer anyway. |
76 | * However, the buffer handler may at some point disable itself, |
77 | * and @pkbuf_flush@ can cope with this eventuality. Any |
78 | * pending data is left at the start of the buffer and can be |
79 | * flushed out by calling @pkbuf_flush(b, 0, 0)@ if the buffer |
80 | * is ever re-enabled. |
81 | */ |
82 | |
83 | void pkbuf_flush(pkbuf *pk, octet *p, size_t len) |
84 | { |
85 | size_t l; |
86 | size_t keep; |
87 | |
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88 | if (pk->f & PKBUF_CLOSE) { |
89 | pk->func(0, 0, pk, 0, pk->p); |
90 | return; |
91 | } |
92 | |
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93 | /* --- Initialize variables as necessary --- */ |
94 | |
95 | if (!p) { |
96 | p = pk->buf; |
97 | len = pk->len; |
98 | } |
99 | l = p + len - pk->buf; |
100 | p = pk->buf; |
101 | |
102 | /* --- Now grind through any packets which have accumulated --- */ |
103 | |
104 | while (l > pk->want) { |
105 | size_t sz = pk->want; |
106 | |
107 | /* --- Pass a packet to the user handler --- */ |
108 | |
109 | keep = 0; |
110 | pk->func(p, sz, pk, &keep, pk->p); |
111 | |
112 | /* --- Adjust all the pointers for the next packet --- */ |
113 | |
114 | sz -= keep; |
115 | p += sz; |
116 | l -= sz; |
117 | |
118 | /* --- Abort here if disabled --- */ |
119 | |
120 | if (!(pk->f & PKBUF_ENABLE)) |
121 | break; |
122 | } |
123 | |
124 | /* --- Shunt data around in the buffer --- */ |
125 | |
126 | if (p > pk->buf && l != 0) |
127 | memmove(pk->buf, p, l); |
128 | pk->len = l; |
129 | } |
130 | |
131 | /* --- @pkbuf_close@ --- * |
132 | * |
133 | * Arguments: @pkbuf *pk@ = pointer to buffer block |
134 | * |
135 | * Returns: --- |
136 | * |
137 | * Use: Informs the client that no more data is likely to arrive. If |
138 | * there is a partial packet in the buffer, it is discarded. |
139 | */ |
140 | |
141 | void pkbuf_close(pkbuf *pk) |
142 | { |
143 | if (pk->buf) { |
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144 | x_free(pk->a, pk->buf); |
145 | pk->buf = 0; |
146 | } |
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147 | pk->f |= PKBUF_CLOSE; |
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148 | if (pk->f & PKBUF_ENABLE) |
149 | pk->func(0, 0, pk, 0, pk->p); |
150 | } |
151 | |
152 | /* --- @pkbuf_free@ --- * |
153 | * |
154 | * Arguments: @pkbuf *pk@ = pointer to buffer block |
155 | * @octet **p@ = output pointer to free space |
156 | * |
157 | * Returns: Free buffer size. |
158 | * |
159 | * Use: Returns the free portion of a packet buffer. Data can then |
160 | * be written to this portion, and split out into packets by |
161 | * calling @pkbuf_flush@. A buffer is allocated if none |
162 | * currently exists. |
163 | */ |
164 | |
165 | size_t pkbuf_free(pkbuf *pk, octet **p) |
166 | { |
167 | if (!pk->buf) { |
168 | fprintf(stderr, "*** allocating new buffer\n"); |
169 | pk->buf = x_alloc(pk->a, pk->sz); |
170 | } |
171 | *p = pk->buf + pk->len; |
172 | return (pk->sz - pk->len); |
173 | } |
174 | |
175 | /* --- @pkbuf_snarf@ --- * |
176 | * |
177 | * Arguments: @pkbuf *pk@ = pointer to buffer block |
178 | * @const void *p@ = pointer to input data buffer |
179 | * @size_t sz@ = size of data in input buffer |
180 | * |
181 | * Returns: --- |
182 | * |
183 | * Use: Snarfs the data from the input buffer and spits it out as |
184 | * packets. This interface ignores the complexities of dealing |
185 | * with disablement: you should be using @pkbuf_free@ to |
186 | * contribute data if you want to cope with that. |
187 | */ |
188 | |
189 | void pkbuf_snarf(pkbuf *pk, const void *p, size_t sz) |
190 | { |
191 | const octet *pp = p; |
192 | while (sz && (pk->f & PKBUF_ENABLE)) { |
193 | size_t bsz; |
194 | octet *bp; |
195 | |
196 | bsz = pkbuf_free(pk, &bp); |
197 | if (bsz > sz) |
198 | bsz = sz; |
199 | memcpy(bp, pp, bsz); |
200 | pkbuf_flush(pk, bp, bsz); |
201 | pp += bsz; |
202 | sz -= bsz; |
203 | } |
204 | } |
205 | |
206 | /* --- @pkbuf_want@ --- * |
207 | * |
208 | * Arguments: @pkbuf *pk@ = pointer to buffer block |
209 | * @size_t want@ = how many octets wanted for next packet |
210 | * |
211 | * Returns: --- |
212 | * |
213 | * Use: Sets the desired size for the next packet to be read. If |
214 | * it's larger than the current buffer, the buffer is extended. |
215 | */ |
216 | |
217 | void pkbuf_want(pkbuf *pk, size_t want) |
218 | { |
219 | pk->want = want; |
220 | if (want > pk->sz) { |
221 | do pk->sz <<= 1; while (want < pk->sz); |
222 | if (pk->buf) { |
223 | if (pk->len) |
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224 | pk->buf = x_realloc(pk->a, pk->buf, pk->sz, pk->len); |
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225 | else { |
226 | x_free(pk->a, pk->buf); |
227 | pk->buf = 0; |
228 | } |
229 | } |
230 | } |
231 | } |
232 | |
233 | /* --- @pkbuf_init@ --- * |
234 | * |
235 | * Arguments: @pkbuf *pk@ = pointer to buffer block |
236 | * @void (*func)(octet *b, size_t sz, pkbuf *pk,@ |
237 | * @size_t *keep, void *p)@ = |
238 | * handler function |
239 | * @void *p@ = argument pointer for @func@ |
240 | * |
241 | * Returns: --- |
242 | * |
243 | * Use: Initializes a packet buffer block. Any packets are passed to |
244 | * the provided function for handling. |
245 | */ |
246 | |
247 | void pkbuf_init(pkbuf *pk, |
248 | void (*func)(octet */*b*/, size_t /*sz*/, |
249 | pkbuf */*pk*/, size_t */*keep*/, void */*p*/), |
250 | void *p) |
251 | { |
252 | pk->func = func; |
253 | pk->p = p; |
254 | pk->len = 0; |
255 | pk->f = PKBUF_ENABLE; |
256 | pk->buf = 0; |
257 | pk->sz = 256; |
258 | pk->want = 1; |
259 | pk->a = arena_global; |
260 | } |
261 | |
262 | /* --- @pkbuf_destroy@ --- * |
263 | * |
264 | * Arguments: @pkbuf *pk@ = pointer to buffer block |
265 | * |
266 | * Returns: --- |
267 | * |
268 | * Use: Deallocates a line buffer and frees any resources it owned. |
269 | */ |
270 | |
271 | void pkbuf_destroy(pkbuf *pk) |
272 | { |
273 | if (pk->buf) { |
274 | x_free(pk->a, pk->buf); |
275 | pk->buf = 0; |
276 | } |
277 | } |
278 | |
279 | /*----- That's all, folks -------------------------------------------------*/ |