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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: pkbuf.c,v 1.3 2000/07/16 18:55:45 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 1.3 2000/07/16 18:55:45 mdw |
34 | * Remove some stray debugging code. |
35 | * |
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36 | * Revision 1.2 2000/07/16 12:29:16 mdw |
37 | * Change to arena `realloc' interface, to fix a design bug. |
38 | * |
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39 | * Revision 1.1 2000/06/17 10:39:19 mdw |
40 | * Experimental new support for packet buffering. |
41 | * |
42 | */ |
43 | |
44 | /*----- Header files ------------------------------------------------------*/ |
45 | |
46 | #include <stdio.h> |
47 | #include <stdlib.h> |
48 | #include <string.h> |
49 | |
50 | #include "alloc.h" |
51 | #include "arena.h" |
52 | #include "pkbuf.h" |
53 | |
54 | /*----- Main code ---------------------------------------------------------*/ |
55 | |
56 | /* --- @pkbuf_flush@ --- * |
57 | * |
58 | * Arguments: @pkbuf *pk@ = pointer to buffer block |
59 | * @octet *p@ = pointer to where to start searching |
60 | * @size_t len@ = length of new material added |
61 | * |
62 | * Returns: --- |
63 | * |
64 | * Use: Flushes any complete packets in a packet buffer. New |
65 | * material is assumed to have been added starting at @p@. If |
66 | * @p@ is null, then the scan starts at the beginning of the |
67 | * buffer, and the size of data already in the buffer is used in |
68 | * place of @len@. |
69 | * |
70 | * It is assumed that the buffer is initially enabled. You |
71 | * shouldn't be contributing data to a disabled buffer anyway. |
72 | * However, the buffer handler may at some point disable itself, |
73 | * and @pkbuf_flush@ can cope with this eventuality. Any |
74 | * pending data is left at the start of the buffer and can be |
75 | * flushed out by calling @pkbuf_flush(b, 0, 0)@ if the buffer |
76 | * is ever re-enabled. |
77 | */ |
78 | |
79 | void pkbuf_flush(pkbuf *pk, octet *p, size_t len) |
80 | { |
81 | size_t l; |
82 | size_t keep; |
83 | |
84 | /* --- Initialize variables as necessary --- */ |
85 | |
86 | if (!p) { |
87 | p = pk->buf; |
88 | len = pk->len; |
89 | } |
90 | l = p + len - pk->buf; |
91 | p = pk->buf; |
92 | |
93 | /* --- Now grind through any packets which have accumulated --- */ |
94 | |
95 | while (l > pk->want) { |
96 | size_t sz = pk->want; |
97 | |
98 | /* --- Pass a packet to the user handler --- */ |
99 | |
100 | keep = 0; |
101 | pk->func(p, sz, pk, &keep, pk->p); |
102 | |
103 | /* --- Adjust all the pointers for the next packet --- */ |
104 | |
105 | sz -= keep; |
106 | p += sz; |
107 | l -= sz; |
108 | |
109 | /* --- Abort here if disabled --- */ |
110 | |
111 | if (!(pk->f & PKBUF_ENABLE)) |
112 | break; |
113 | } |
114 | |
115 | /* --- Shunt data around in the buffer --- */ |
116 | |
117 | if (p > pk->buf && l != 0) |
118 | memmove(pk->buf, p, l); |
119 | pk->len = l; |
120 | } |
121 | |
122 | /* --- @pkbuf_close@ --- * |
123 | * |
124 | * Arguments: @pkbuf *pk@ = pointer to buffer block |
125 | * |
126 | * Returns: --- |
127 | * |
128 | * Use: Informs the client that no more data is likely to arrive. If |
129 | * there is a partial packet in the buffer, it is discarded. |
130 | */ |
131 | |
132 | void pkbuf_close(pkbuf *pk) |
133 | { |
134 | if (pk->buf) { |
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135 | x_free(pk->a, pk->buf); |
136 | pk->buf = 0; |
137 | } |
138 | if (pk->f & PKBUF_ENABLE) |
139 | pk->func(0, 0, pk, 0, pk->p); |
140 | } |
141 | |
142 | /* --- @pkbuf_free@ --- * |
143 | * |
144 | * Arguments: @pkbuf *pk@ = pointer to buffer block |
145 | * @octet **p@ = output pointer to free space |
146 | * |
147 | * Returns: Free buffer size. |
148 | * |
149 | * Use: Returns the free portion of a packet buffer. Data can then |
150 | * be written to this portion, and split out into packets by |
151 | * calling @pkbuf_flush@. A buffer is allocated if none |
152 | * currently exists. |
153 | */ |
154 | |
155 | size_t pkbuf_free(pkbuf *pk, octet **p) |
156 | { |
157 | if (!pk->buf) { |
158 | fprintf(stderr, "*** allocating new buffer\n"); |
159 | pk->buf = x_alloc(pk->a, pk->sz); |
160 | } |
161 | *p = pk->buf + pk->len; |
162 | return (pk->sz - pk->len); |
163 | } |
164 | |
165 | /* --- @pkbuf_snarf@ --- * |
166 | * |
167 | * Arguments: @pkbuf *pk@ = pointer to buffer block |
168 | * @const void *p@ = pointer to input data buffer |
169 | * @size_t sz@ = size of data in input buffer |
170 | * |
171 | * Returns: --- |
172 | * |
173 | * Use: Snarfs the data from the input buffer and spits it out as |
174 | * packets. This interface ignores the complexities of dealing |
175 | * with disablement: you should be using @pkbuf_free@ to |
176 | * contribute data if you want to cope with that. |
177 | */ |
178 | |
179 | void pkbuf_snarf(pkbuf *pk, const void *p, size_t sz) |
180 | { |
181 | const octet *pp = p; |
182 | while (sz && (pk->f & PKBUF_ENABLE)) { |
183 | size_t bsz; |
184 | octet *bp; |
185 | |
186 | bsz = pkbuf_free(pk, &bp); |
187 | if (bsz > sz) |
188 | bsz = sz; |
189 | memcpy(bp, pp, bsz); |
190 | pkbuf_flush(pk, bp, bsz); |
191 | pp += bsz; |
192 | sz -= bsz; |
193 | } |
194 | } |
195 | |
196 | /* --- @pkbuf_want@ --- * |
197 | * |
198 | * Arguments: @pkbuf *pk@ = pointer to buffer block |
199 | * @size_t want@ = how many octets wanted for next packet |
200 | * |
201 | * Returns: --- |
202 | * |
203 | * Use: Sets the desired size for the next packet to be read. If |
204 | * it's larger than the current buffer, the buffer is extended. |
205 | */ |
206 | |
207 | void pkbuf_want(pkbuf *pk, size_t want) |
208 | { |
209 | pk->want = want; |
210 | if (want > pk->sz) { |
211 | do pk->sz <<= 1; while (want < pk->sz); |
212 | if (pk->buf) { |
213 | if (pk->len) |
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214 | pk->buf = x_realloc(pk->a, pk->buf, pk->sz, pk->len); |
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215 | else { |
216 | x_free(pk->a, pk->buf); |
217 | pk->buf = 0; |
218 | } |
219 | } |
220 | } |
221 | } |
222 | |
223 | /* --- @pkbuf_init@ --- * |
224 | * |
225 | * Arguments: @pkbuf *pk@ = pointer to buffer block |
226 | * @void (*func)(octet *b, size_t sz, pkbuf *pk,@ |
227 | * @size_t *keep, void *p)@ = |
228 | * handler function |
229 | * @void *p@ = argument pointer for @func@ |
230 | * |
231 | * Returns: --- |
232 | * |
233 | * Use: Initializes a packet buffer block. Any packets are passed to |
234 | * the provided function for handling. |
235 | */ |
236 | |
237 | void pkbuf_init(pkbuf *pk, |
238 | void (*func)(octet */*b*/, size_t /*sz*/, |
239 | pkbuf */*pk*/, size_t */*keep*/, void */*p*/), |
240 | void *p) |
241 | { |
242 | pk->func = func; |
243 | pk->p = p; |
244 | pk->len = 0; |
245 | pk->f = PKBUF_ENABLE; |
246 | pk->buf = 0; |
247 | pk->sz = 256; |
248 | pk->want = 1; |
249 | pk->a = arena_global; |
250 | } |
251 | |
252 | /* --- @pkbuf_destroy@ --- * |
253 | * |
254 | * Arguments: @pkbuf *pk@ = pointer to buffer block |
255 | * |
256 | * Returns: --- |
257 | * |
258 | * Use: Deallocates a line buffer and frees any resources it owned. |
259 | */ |
260 | |
261 | void pkbuf_destroy(pkbuf *pk) |
262 | { |
263 | if (pk->buf) { |
264 | x_free(pk->a, pk->buf); |
265 | pk->buf = 0; |
266 | } |
267 | } |
268 | |
269 | /*----- That's all, folks -------------------------------------------------*/ |