3 * $Id: pkbuf.c,v 1.4 2001/02/03 16:23:33 mdw Exp $
5 * Simple packet buffering
7 * (c) 2000 Straylight/Edgeware
10 /*----- Licensing notice --------------------------------------------------*
12 * This file is part of the mLib utilities library.
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.
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.
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,
30 /*----- Revision history --------------------------------------------------*
33 * Revision 1.4 2001/02/03 16:23:33 mdw
34 * Bug fix: handle a disable during a close-induced flush without dumping
37 * Revision 1.3 2000/07/16 18:55:45 mdw
38 * Remove some stray debugging code.
40 * Revision 1.2 2000/07/16 12:29:16 mdw
41 * Change to arena `realloc' interface, to fix a design bug.
43 * Revision 1.1 2000/06/17 10:39:19 mdw
44 * Experimental new support for packet buffering.
48 /*----- Header files ------------------------------------------------------*/
58 /*----- Main code ---------------------------------------------------------*/
60 /* --- @pkbuf_flush@ --- *
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
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
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
83 void pkbuf_flush(pkbuf *pk, octet *p, size_t len)
88 if (pk->f & PKBUF_CLOSE) {
89 pk->func(0, 0, pk, 0, pk->p);
93 /* --- Initialize variables as necessary --- */
99 l = p + len - pk->buf;
102 /* --- Now grind through any packets which have accumulated --- */
104 while (l > pk->want) {
105 size_t sz = pk->want;
107 /* --- Pass a packet to the user handler --- */
110 pk->func(p, sz, pk, &keep, pk->p);
112 /* --- Adjust all the pointers for the next packet --- */
118 /* --- Abort here if disabled --- */
120 if (!(pk->f & PKBUF_ENABLE))
124 /* --- Shunt data around in the buffer --- */
126 if (p > pk->buf && l != 0)
127 memmove(pk->buf, p, l);
131 /* --- @pkbuf_close@ --- *
133 * Arguments: @pkbuf *pk@ = pointer to buffer block
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.
141 void pkbuf_close(pkbuf *pk)
144 x_free(pk->a, pk->buf);
147 pk->f |= PKBUF_CLOSE;
148 if (pk->f & PKBUF_ENABLE)
149 pk->func(0, 0, pk, 0, pk->p);
152 /* --- @pkbuf_free@ --- *
154 * Arguments: @pkbuf *pk@ = pointer to buffer block
155 * @octet **p@ = output pointer to free space
157 * Returns: Free buffer size.
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
165 size_t pkbuf_free(pkbuf *pk, octet **p)
168 fprintf(stderr, "*** allocating new buffer\n");
169 pk->buf = x_alloc(pk->a, pk->sz);
171 *p = pk->buf + pk->len;
172 return (pk->sz - pk->len);
175 /* --- @pkbuf_snarf@ --- *
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
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.
189 void pkbuf_snarf(pkbuf *pk, const void *p, size_t sz)
192 while (sz && (pk->f & PKBUF_ENABLE)) {
196 bsz = pkbuf_free(pk, &bp);
200 pkbuf_flush(pk, bp, bsz);
206 /* --- @pkbuf_want@ --- *
208 * Arguments: @pkbuf *pk@ = pointer to buffer block
209 * @size_t want@ = how many octets wanted for next packet
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.
217 void pkbuf_want(pkbuf *pk, size_t want)
221 do pk->sz <<= 1; while (want < pk->sz);
224 pk->buf = x_realloc(pk->a, pk->buf, pk->sz, pk->len);
226 x_free(pk->a, pk->buf);
233 /* --- @pkbuf_init@ --- *
235 * Arguments: @pkbuf *pk@ = pointer to buffer block
236 * @void (*func)(octet *b, size_t sz, pkbuf *pk,@
237 * @size_t *keep, void *p)@ =
239 * @void *p@ = argument pointer for @func@
243 * Use: Initializes a packet buffer block. Any packets are passed to
244 * the provided function for handling.
247 void pkbuf_init(pkbuf *pk,
248 void (*func)(octet */*b*/, size_t /*sz*/,
249 pkbuf */*pk*/, size_t */*keep*/, void */*p*/),
255 pk->f = PKBUF_ENABLE;
259 pk->a = arena_global;
262 /* --- @pkbuf_destroy@ --- *
264 * Arguments: @pkbuf *pk@ = pointer to buffer block
268 * Use: Deallocates a line buffer and frees any resources it owned.
271 void pkbuf_destroy(pkbuf *pk)
274 x_free(pk->a, pk->buf);
279 /*----- That's all, folks -------------------------------------------------*/