3 * $Id: pkbuf.c,v 1.6 2003/04/23 12:47:44 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 1.6 2003/04/23 12:47:44 mdw
36 * Revision 1.5 2002/01/13 13:33:51 mdw
37 * Packet handler functions now have a @typedef@ name.
39 * Revision 1.4 2001/02/03 16:23:33 mdw
40 * Bug fix: handle a disable during a close-induced flush without dumping
43 * Revision 1.3 2000/07/16 18:55:45 mdw
44 * Remove some stray debugging code.
46 * Revision 1.2 2000/07/16 12:29:16 mdw
47 * Change to arena `realloc' interface, to fix a design bug.
49 * Revision 1.1 2000/06/17 10:39:19 mdw
50 * Experimental new support for packet buffering.
54 /*----- Header files ------------------------------------------------------*/
64 /*----- Main code ---------------------------------------------------------*/
66 /* --- @pkbuf_flush@ --- *
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
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
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
89 void pkbuf_flush(pkbuf
*pk
, octet
*p
, size_t len
)
94 if (pk
->f
& PKBUF_CLOSE
) {
95 pk
->func(0, 0, pk
, 0, pk
->p
);
99 /* --- Initialize variables as necessary --- */
105 l
= p
+ len
- pk
->buf
;
108 /* --- Now grind through any packets which have accumulated --- */
111 while (l
>= pk
->want
) {
112 size_t sz
= pk
->want
;
114 /* --- Pass a packet to the user handler --- */
117 pk
->func(pk
->buf
+ o
, sz
, pk
, &keep
, pk
->p
);
119 /* --- Adjust all the pointers for the next packet --- */
125 /* --- Abort here if disabled --- */
127 if (!(pk
->f
& PKBUF_ENABLE
))
131 /* --- Shunt data around in the buffer --- */
134 memmove(pk
->buf
, pk
->buf
+ o
, l
);
138 /* --- @pkbuf_close@ --- *
140 * Arguments: @pkbuf *pk@ = pointer to buffer block
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.
148 void pkbuf_close(pkbuf
*pk
)
151 x_free(pk
->a
, pk
->buf
);
154 pk
->f
|= PKBUF_CLOSE
;
155 if (pk
->f
& PKBUF_ENABLE
)
156 pk
->func(0, 0, pk
, 0, pk
->p
);
159 /* --- @pkbuf_free@ --- *
161 * Arguments: @pkbuf *pk@ = pointer to buffer block
162 * @octet **p@ = output pointer to free space
164 * Returns: Free buffer size.
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
172 size_t pkbuf_free(pkbuf
*pk
, octet
**p
)
175 pk
->buf
= x_alloc(pk
->a
, pk
->sz
);
176 *p
= pk
->buf
+ pk
->len
;
177 return (pk
->sz
- pk
->len
);
180 /* --- @pkbuf_snarf@ --- *
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
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.
194 void pkbuf_snarf(pkbuf
*pk
, const void *p
, size_t sz
)
197 while (sz
&& (pk
->f
& PKBUF_ENABLE
)) {
201 bsz
= pkbuf_free(pk
, &bp
);
205 pkbuf_flush(pk
, bp
, bsz
);
211 /* --- @pkbuf_want@ --- *
213 * Arguments: @pkbuf *pk@ = pointer to buffer block
214 * @size_t want@ = how many octets wanted for next packet
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.
222 void pkbuf_want(pkbuf
*pk
, size_t want
)
226 do pk
->sz
<<= 1; while (want
> pk
->sz
);
229 pk
->buf
= x_realloc(pk
->a
, pk
->buf
, pk
->sz
, pk
->len
);
231 x_free(pk
->a
, pk
->buf
);
238 /* --- @pkbuf_init@ --- *
240 * Arguments: @pkbuf *pk@ = pointer to buffer block
241 * @pkbuf *func@ = handler function
242 * @void *p@ = argument pointer for @func@
246 * Use: Initializes a packet buffer block. Any packets are passed to
247 * the provided function for handling.
250 void pkbuf_init(pkbuf
*pk
, pkbuf_func
*func
, 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 -------------------------------------------------*/