3 * $Id: pkbuf.c,v 1.5 2002/01/13 13:33:51 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 1.5 2002/01/13 13:33:51 mdw
34 * Packet handler functions now have a @typedef@ name.
36 * Revision 1.4 2001/02/03 16:23:33 mdw
37 * Bug fix: handle a disable during a close-induced flush without dumping
40 * Revision 1.3 2000/07/16 18:55:45 mdw
41 * Remove some stray debugging code.
43 * Revision 1.2 2000/07/16 12:29:16 mdw
44 * Change to arena `realloc' interface, to fix a design bug.
46 * Revision 1.1 2000/06/17 10:39:19 mdw
47 * Experimental new support for packet buffering.
51 /*----- Header files ------------------------------------------------------*/
61 /*----- Main code ---------------------------------------------------------*/
63 /* --- @pkbuf_flush@ --- *
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
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
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
86 void pkbuf_flush(pkbuf
*pk
, octet
*p
, size_t len
)
91 if (pk
->f
& PKBUF_CLOSE
) {
92 pk
->func(0, 0, pk
, 0, pk
->p
);
96 /* --- Initialize variables as necessary --- */
102 l
= p
+ len
- pk
->buf
;
105 /* --- Now grind through any packets which have accumulated --- */
107 while (l
> pk
->want
) {
108 size_t sz
= pk
->want
;
110 /* --- Pass a packet to the user handler --- */
113 pk
->func(p
, sz
, pk
, &keep
, pk
->p
);
115 /* --- Adjust all the pointers for the next packet --- */
121 /* --- Abort here if disabled --- */
123 if (!(pk
->f
& PKBUF_ENABLE
))
127 /* --- Shunt data around in the buffer --- */
129 if (p
> pk
->buf
&& l
!= 0)
130 memmove(pk
->buf
, p
, l
);
134 /* --- @pkbuf_close@ --- *
136 * Arguments: @pkbuf *pk@ = pointer to buffer block
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.
144 void pkbuf_close(pkbuf
*pk
)
147 x_free(pk
->a
, pk
->buf
);
150 pk
->f
|= PKBUF_CLOSE
;
151 if (pk
->f
& PKBUF_ENABLE
)
152 pk
->func(0, 0, pk
, 0, pk
->p
);
155 /* --- @pkbuf_free@ --- *
157 * Arguments: @pkbuf *pk@ = pointer to buffer block
158 * @octet **p@ = output pointer to free space
160 * Returns: Free buffer size.
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
168 size_t pkbuf_free(pkbuf
*pk
, octet
**p
)
171 fprintf(stderr
, "*** allocating new buffer\n");
172 pk
->buf
= x_alloc(pk
->a
, pk
->sz
);
174 *p
= pk
->buf
+ pk
->len
;
175 return (pk
->sz
- pk
->len
);
178 /* --- @pkbuf_snarf@ --- *
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
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.
192 void pkbuf_snarf(pkbuf
*pk
, const void *p
, size_t sz
)
195 while (sz
&& (pk
->f
& PKBUF_ENABLE
)) {
199 bsz
= pkbuf_free(pk
, &bp
);
203 pkbuf_flush(pk
, bp
, bsz
);
209 /* --- @pkbuf_want@ --- *
211 * Arguments: @pkbuf *pk@ = pointer to buffer block
212 * @size_t want@ = how many octets wanted for next packet
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.
220 void pkbuf_want(pkbuf
*pk
, size_t want
)
224 do pk
->sz
<<= 1; while (want
< pk
->sz
);
227 pk
->buf
= x_realloc(pk
->a
, pk
->buf
, pk
->sz
, pk
->len
);
229 x_free(pk
->a
, pk
->buf
);
236 /* --- @pkbuf_init@ --- *
238 * Arguments: @pkbuf *pk@ = pointer to buffer block
239 * @pkbuf *func@ = handler function
240 * @void *p@ = argument pointer for @func@
244 * Use: Initializes a packet buffer block. Any packets are passed to
245 * the provided function for handling.
248 void pkbuf_init(pkbuf
*pk
, pkbuf_func
*func
, void *p
)
253 pk
->f
= PKBUF_ENABLE
;
257 pk
->a
= arena_global
;
260 /* --- @pkbuf_destroy@ --- *
262 * Arguments: @pkbuf *pk@ = pointer to buffer block
266 * Use: Deallocates a line buffer and frees any resources it owned.
269 void pkbuf_destroy(pkbuf
*pk
)
272 x_free(pk
->a
, pk
->buf
);
277 /*----- That's all, folks -------------------------------------------------*/