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[mLib] / pkbuf.c
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436fddaa 1/* -*-c-*-
2 *
f88f8d87 3 * $Id: pkbuf.c,v 1.6 2003/04/23 12:47:44 mdw Exp $
436fddaa 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 $
f88f8d87 33 * Revision 1.6 2003/04/23 12:47:44 mdw
34 * Various bugfixes.
35 *
0daaeb18 36 * Revision 1.5 2002/01/13 13:33:51 mdw
37 * Packet handler functions now have a @typedef@ name.
38 *
3fd896a4 39 * Revision 1.4 2001/02/03 16:23:33 mdw
40 * Bug fix: handle a disable during a close-induced flush without dumping
41 * core.
42 *
54116dad 43 * Revision 1.3 2000/07/16 18:55:45 mdw
44 * Remove some stray debugging code.
45 *
b5ea4de3 46 * Revision 1.2 2000/07/16 12:29:16 mdw
47 * Change to arena `realloc' interface, to fix a design bug.
48 *
436fddaa 49 * Revision 1.1 2000/06/17 10:39:19 mdw
50 * Experimental new support for packet buffering.
51 *
52 */
53
54/*----- Header files ------------------------------------------------------*/
55
56#include <stdio.h>
57#include <stdlib.h>
58#include <string.h>
59
60#include "alloc.h"
61#include "arena.h"
62#include "pkbuf.h"
63
64/*----- Main code ---------------------------------------------------------*/
65
66/* --- @pkbuf_flush@ --- *
67 *
68 * Arguments: @pkbuf *pk@ = pointer to buffer block
69 * @octet *p@ = pointer to where to start searching
70 * @size_t len@ = length of new material added
71 *
72 * Returns: ---
73 *
74 * Use: Flushes any complete packets in a packet buffer. New
75 * material is assumed to have been added starting at @p@. If
76 * @p@ is null, then the scan starts at the beginning of the
77 * buffer, and the size of data already in the buffer is used in
78 * place of @len@.
79 *
80 * It is assumed that the buffer is initially enabled. You
81 * shouldn't be contributing data to a disabled buffer anyway.
82 * However, the buffer handler may at some point disable itself,
83 * and @pkbuf_flush@ can cope with this eventuality. Any
84 * pending data is left at the start of the buffer and can be
85 * flushed out by calling @pkbuf_flush(b, 0, 0)@ if the buffer
86 * is ever re-enabled.
87 */
88
89void pkbuf_flush(pkbuf *pk, octet *p, size_t len)
90{
91 size_t l;
f88f8d87 92 size_t o, keep;
436fddaa 93
3fd896a4 94 if (pk->f & PKBUF_CLOSE) {
95 pk->func(0, 0, pk, 0, pk->p);
96 return;
97 }
98
436fddaa 99 /* --- Initialize variables as necessary --- */
100
101 if (!p) {
102 p = pk->buf;
103 len = pk->len;
104 }
105 l = p + len - pk->buf;
f88f8d87 106 o = 0;
436fddaa 107
108 /* --- Now grind through any packets which have accumulated --- */
109
f88f8d87 110 pk->len = l;
111 while (l >= pk->want) {
436fddaa 112 size_t sz = pk->want;
113
114 /* --- Pass a packet to the user handler --- */
115
116 keep = 0;
f88f8d87 117 pk->func(pk->buf + o, sz, pk, &keep, pk->p);
436fddaa 118
119 /* --- Adjust all the pointers for the next packet --- */
120
121 sz -= keep;
f88f8d87 122 o += sz;
436fddaa 123 l -= sz;
124
125 /* --- Abort here if disabled --- */
126
127 if (!(pk->f & PKBUF_ENABLE))
128 break;
129 }
130
131 /* --- Shunt data around in the buffer --- */
132
f88f8d87 133 if (o > 0 && l != 0)
134 memmove(pk->buf, pk->buf + o, l);
436fddaa 135 pk->len = l;
136}
137
138/* --- @pkbuf_close@ --- *
139 *
140 * Arguments: @pkbuf *pk@ = pointer to buffer block
141 *
142 * Returns: ---
143 *
144 * Use: Informs the client that no more data is likely to arrive. If
145 * there is a partial packet in the buffer, it is discarded.
146 */
147
148void pkbuf_close(pkbuf *pk)
149{
150 if (pk->buf) {
436fddaa 151 x_free(pk->a, pk->buf);
152 pk->buf = 0;
153 }
3fd896a4 154 pk->f |= PKBUF_CLOSE;
436fddaa 155 if (pk->f & PKBUF_ENABLE)
156 pk->func(0, 0, pk, 0, pk->p);
157}
158
159/* --- @pkbuf_free@ --- *
160 *
161 * Arguments: @pkbuf *pk@ = pointer to buffer block
162 * @octet **p@ = output pointer to free space
163 *
164 * Returns: Free buffer size.
165 *
166 * Use: Returns the free portion of a packet buffer. Data can then
167 * be written to this portion, and split out into packets by
168 * calling @pkbuf_flush@. A buffer is allocated if none
169 * currently exists.
170 */
171
172size_t pkbuf_free(pkbuf *pk, octet **p)
173{
f88f8d87 174 if (!pk->buf)
436fddaa 175 pk->buf = x_alloc(pk->a, pk->sz);
436fddaa 176 *p = pk->buf + pk->len;
177 return (pk->sz - pk->len);
178}
179
180/* --- @pkbuf_snarf@ --- *
181 *
182 * Arguments: @pkbuf *pk@ = pointer to buffer block
183 * @const void *p@ = pointer to input data buffer
184 * @size_t sz@ = size of data in input buffer
185 *
186 * Returns: ---
187 *
188 * Use: Snarfs the data from the input buffer and spits it out as
189 * packets. This interface ignores the complexities of dealing
190 * with disablement: you should be using @pkbuf_free@ to
191 * contribute data if you want to cope with that.
192 */
193
194void pkbuf_snarf(pkbuf *pk, const void *p, size_t sz)
195{
196 const octet *pp = p;
197 while (sz && (pk->f & PKBUF_ENABLE)) {
198 size_t bsz;
199 octet *bp;
200
201 bsz = pkbuf_free(pk, &bp);
202 if (bsz > sz)
203 bsz = sz;
204 memcpy(bp, pp, bsz);
205 pkbuf_flush(pk, bp, bsz);
206 pp += bsz;
207 sz -= bsz;
208 }
209}
210
211/* --- @pkbuf_want@ --- *
212 *
213 * Arguments: @pkbuf *pk@ = pointer to buffer block
214 * @size_t want@ = how many octets wanted for next packet
215 *
216 * Returns: ---
217 *
218 * Use: Sets the desired size for the next packet to be read. If
219 * it's larger than the current buffer, the buffer is extended.
220 */
221
222void pkbuf_want(pkbuf *pk, size_t want)
223{
224 pk->want = want;
225 if (want > pk->sz) {
f88f8d87 226 do pk->sz <<= 1; while (want > pk->sz);
436fddaa 227 if (pk->buf) {
228 if (pk->len)
b5ea4de3 229 pk->buf = x_realloc(pk->a, pk->buf, pk->sz, pk->len);
436fddaa 230 else {
231 x_free(pk->a, pk->buf);
232 pk->buf = 0;
233 }
234 }
235 }
236}
237
238/* --- @pkbuf_init@ --- *
239 *
240 * Arguments: @pkbuf *pk@ = pointer to buffer block
0daaeb18 241 * @pkbuf *func@ = handler function
436fddaa 242 * @void *p@ = argument pointer for @func@
243 *
244 * Returns: ---
245 *
246 * Use: Initializes a packet buffer block. Any packets are passed to
247 * the provided function for handling.
248 */
249
0daaeb18 250void pkbuf_init(pkbuf *pk, pkbuf_func *func, void *p)
436fddaa 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
271void 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 -------------------------------------------------*/