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