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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: pkbuf.c,v 1.5 2002/01/13 13:33:51 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 1.5 2002/01/13 13:33:51 mdw |
34 | * Packet handler functions now have a @typedef@ name. |
35 | * |
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36 | * Revision 1.4 2001/02/03 16:23:33 mdw |
37 | * Bug fix: handle a disable during a close-induced flush without dumping |
38 | * core. |
39 | * |
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40 | * Revision 1.3 2000/07/16 18:55:45 mdw |
41 | * Remove some stray debugging code. |
42 | * |
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43 | * Revision 1.2 2000/07/16 12:29:16 mdw |
44 | * Change to arena `realloc' interface, to fix a design bug. |
45 | * |
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46 | * Revision 1.1 2000/06/17 10:39:19 mdw |
47 | * Experimental new support for packet buffering. |
48 | * |
49 | */ |
50 | |
51 | /*----- Header files ------------------------------------------------------*/ |
52 | |
53 | #include <stdio.h> |
54 | #include <stdlib.h> |
55 | #include <string.h> |
56 | |
57 | #include "alloc.h" |
58 | #include "arena.h" |
59 | #include "pkbuf.h" |
60 | |
61 | /*----- Main code ---------------------------------------------------------*/ |
62 | |
63 | /* --- @pkbuf_flush@ --- * |
64 | * |
65 | * Arguments: @pkbuf *pk@ = pointer to buffer block |
66 | * @octet *p@ = pointer to where to start searching |
67 | * @size_t len@ = length of new material added |
68 | * |
69 | * Returns: --- |
70 | * |
71 | * Use: Flushes any complete packets in a packet buffer. New |
72 | * material is assumed to have been added starting at @p@. If |
73 | * @p@ is null, then the scan starts at the beginning of the |
74 | * buffer, and the size of data already in the buffer is used in |
75 | * place of @len@. |
76 | * |
77 | * It is assumed that the buffer is initially enabled. You |
78 | * shouldn't be contributing data to a disabled buffer anyway. |
79 | * However, the buffer handler may at some point disable itself, |
80 | * and @pkbuf_flush@ can cope with this eventuality. Any |
81 | * pending data is left at the start of the buffer and can be |
82 | * flushed out by calling @pkbuf_flush(b, 0, 0)@ if the buffer |
83 | * is ever re-enabled. |
84 | */ |
85 | |
86 | void pkbuf_flush(pkbuf *pk, octet *p, size_t len) |
87 | { |
88 | size_t l; |
89 | size_t keep; |
90 | |
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91 | if (pk->f & PKBUF_CLOSE) { |
92 | pk->func(0, 0, pk, 0, pk->p); |
93 | return; |
94 | } |
95 | |
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96 | /* --- Initialize variables as necessary --- */ |
97 | |
98 | if (!p) { |
99 | p = pk->buf; |
100 | len = pk->len; |
101 | } |
102 | l = p + len - pk->buf; |
103 | p = pk->buf; |
104 | |
105 | /* --- Now grind through any packets which have accumulated --- */ |
106 | |
107 | while (l > pk->want) { |
108 | size_t sz = pk->want; |
109 | |
110 | /* --- Pass a packet to the user handler --- */ |
111 | |
112 | keep = 0; |
113 | pk->func(p, sz, pk, &keep, pk->p); |
114 | |
115 | /* --- Adjust all the pointers for the next packet --- */ |
116 | |
117 | sz -= keep; |
118 | p += sz; |
119 | l -= sz; |
120 | |
121 | /* --- Abort here if disabled --- */ |
122 | |
123 | if (!(pk->f & PKBUF_ENABLE)) |
124 | break; |
125 | } |
126 | |
127 | /* --- Shunt data around in the buffer --- */ |
128 | |
129 | if (p > pk->buf && l != 0) |
130 | memmove(pk->buf, p, l); |
131 | pk->len = l; |
132 | } |
133 | |
134 | /* --- @pkbuf_close@ --- * |
135 | * |
136 | * Arguments: @pkbuf *pk@ = pointer to buffer block |
137 | * |
138 | * Returns: --- |
139 | * |
140 | * Use: Informs the client that no more data is likely to arrive. If |
141 | * there is a partial packet in the buffer, it is discarded. |
142 | */ |
143 | |
144 | void pkbuf_close(pkbuf *pk) |
145 | { |
146 | if (pk->buf) { |
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147 | x_free(pk->a, pk->buf); |
148 | pk->buf = 0; |
149 | } |
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150 | pk->f |= PKBUF_CLOSE; |
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151 | if (pk->f & PKBUF_ENABLE) |
152 | pk->func(0, 0, pk, 0, pk->p); |
153 | } |
154 | |
155 | /* --- @pkbuf_free@ --- * |
156 | * |
157 | * Arguments: @pkbuf *pk@ = pointer to buffer block |
158 | * @octet **p@ = output pointer to free space |
159 | * |
160 | * Returns: Free buffer size. |
161 | * |
162 | * Use: Returns the free portion of a packet buffer. Data can then |
163 | * be written to this portion, and split out into packets by |
164 | * calling @pkbuf_flush@. A buffer is allocated if none |
165 | * currently exists. |
166 | */ |
167 | |
168 | size_t pkbuf_free(pkbuf *pk, octet **p) |
169 | { |
170 | if (!pk->buf) { |
171 | fprintf(stderr, "*** allocating new buffer\n"); |
172 | pk->buf = x_alloc(pk->a, pk->sz); |
173 | } |
174 | *p = pk->buf + pk->len; |
175 | return (pk->sz - pk->len); |
176 | } |
177 | |
178 | /* --- @pkbuf_snarf@ --- * |
179 | * |
180 | * Arguments: @pkbuf *pk@ = pointer to buffer block |
181 | * @const void *p@ = pointer to input data buffer |
182 | * @size_t sz@ = size of data in input buffer |
183 | * |
184 | * Returns: --- |
185 | * |
186 | * Use: Snarfs the data from the input buffer and spits it out as |
187 | * packets. This interface ignores the complexities of dealing |
188 | * with disablement: you should be using @pkbuf_free@ to |
189 | * contribute data if you want to cope with that. |
190 | */ |
191 | |
192 | void pkbuf_snarf(pkbuf *pk, const void *p, size_t sz) |
193 | { |
194 | const octet *pp = p; |
195 | while (sz && (pk->f & PKBUF_ENABLE)) { |
196 | size_t bsz; |
197 | octet *bp; |
198 | |
199 | bsz = pkbuf_free(pk, &bp); |
200 | if (bsz > sz) |
201 | bsz = sz; |
202 | memcpy(bp, pp, bsz); |
203 | pkbuf_flush(pk, bp, bsz); |
204 | pp += bsz; |
205 | sz -= bsz; |
206 | } |
207 | } |
208 | |
209 | /* --- @pkbuf_want@ --- * |
210 | * |
211 | * Arguments: @pkbuf *pk@ = pointer to buffer block |
212 | * @size_t want@ = how many octets wanted for next packet |
213 | * |
214 | * Returns: --- |
215 | * |
216 | * Use: Sets the desired size for the next packet to be read. If |
217 | * it's larger than the current buffer, the buffer is extended. |
218 | */ |
219 | |
220 | void pkbuf_want(pkbuf *pk, size_t want) |
221 | { |
222 | pk->want = want; |
223 | if (want > pk->sz) { |
224 | do pk->sz <<= 1; while (want < pk->sz); |
225 | if (pk->buf) { |
226 | if (pk->len) |
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227 | pk->buf = x_realloc(pk->a, pk->buf, pk->sz, pk->len); |
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228 | else { |
229 | x_free(pk->a, pk->buf); |
230 | pk->buf = 0; |
231 | } |
232 | } |
233 | } |
234 | } |
235 | |
236 | /* --- @pkbuf_init@ --- * |
237 | * |
238 | * Arguments: @pkbuf *pk@ = pointer to buffer block |
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239 | * @pkbuf *func@ = handler function |
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240 | * @void *p@ = argument pointer for @func@ |
241 | * |
242 | * Returns: --- |
243 | * |
244 | * Use: Initializes a packet buffer block. Any packets are passed to |
245 | * the provided function for handling. |
246 | */ |
247 | |
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248 | void pkbuf_init(pkbuf *pk, pkbuf_func *func, void *p) |
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249 | { |
250 | pk->func = func; |
251 | pk->p = p; |
252 | pk->len = 0; |
253 | pk->f = PKBUF_ENABLE; |
254 | pk->buf = 0; |
255 | pk->sz = 256; |
256 | pk->want = 1; |
257 | pk->a = arena_global; |
258 | } |
259 | |
260 | /* --- @pkbuf_destroy@ --- * |
261 | * |
262 | * Arguments: @pkbuf *pk@ = pointer to buffer block |
263 | * |
264 | * Returns: --- |
265 | * |
266 | * Use: Deallocates a line buffer and frees any resources it owned. |
267 | */ |
268 | |
269 | void pkbuf_destroy(pkbuf *pk) |
270 | { |
271 | if (pk->buf) { |
272 | x_free(pk->a, pk->buf); |
273 | pk->buf = 0; |
274 | } |
275 | } |
276 | |
277 | /*----- That's all, folks -------------------------------------------------*/ |