3 * Simple packet buffering
5 * (c) 2000 Straylight/Edgeware
8 /*----- Licensing notice --------------------------------------------------*
10 * This file is part of the mLib utilities library.
12 * mLib is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU Library General Public License as
14 * published by the Free Software Foundation; either version 2 of the
15 * License, or (at your option) any later version.
17 * mLib is distributed in the hope that it will be useful,
18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 * GNU Library General Public License for more details.
22 * You should have received a copy of the GNU Library General Public
23 * License along with mLib; if not, write to the Free
24 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
28 /*----- Header files ------------------------------------------------------*/
38 /*----- Main code ---------------------------------------------------------*/
40 /* --- @pkbuf_flush@ --- *
42 * Arguments: @pkbuf *pk@ = pointer to buffer block
43 * @octet *p@ = pointer to where to start searching
44 * @size_t len@ = length of new material added
48 * Use: Flushes any complete packets in a packet buffer. New
49 * material is assumed to have been added starting at @p@. If
50 * @p@ is null, then the scan starts at the beginning of the
51 * buffer, and the size of data already in the buffer is used in
54 * It is assumed that the buffer is initially enabled. You
55 * shouldn't be contributing data to a disabled buffer anyway.
56 * However, the buffer handler may at some point disable itself,
57 * and @pkbuf_flush@ can cope with this eventuality. Any
58 * pending data is left at the start of the buffer and can be
59 * flushed out by calling @pkbuf_flush(b, 0, 0)@ if the buffer
63 void pkbuf_flush(pkbuf
*pk
, octet
*p
, size_t len
)
68 if (pk
->f
& PKBUF_CLOSE
) {
69 pk
->func(0, 0, pk
, 0, pk
->p
);
73 /* --- Initialize variables as necessary --- */
79 l
= p
+ len
- pk
->buf
;
82 /* --- Now grind through any packets which have accumulated --- */
85 while (l
>= pk
->want
) {
88 /* --- Pass a packet to the user handler --- */
91 pk
->func(pk
->buf
+ o
, sz
, pk
, &keep
, pk
->p
);
93 /* --- Adjust all the pointers for the next packet --- */
99 /* --- Abort here if disabled --- */
101 if (!(pk
->f
& PKBUF_ENABLE
))
105 /* --- Shunt data around in the buffer --- */
108 memmove(pk
->buf
, pk
->buf
+ o
, l
);
112 /* --- @pkbuf_close@ --- *
114 * Arguments: @pkbuf *pk@ = pointer to buffer block
118 * Use: Informs the client that no more data is likely to arrive. If
119 * there is a partial packet in the buffer, it is discarded.
122 void pkbuf_close(pkbuf
*pk
)
125 x_free(pk
->a
, pk
->buf
);
128 pk
->f
|= PKBUF_CLOSE
;
129 if (pk
->f
& PKBUF_ENABLE
)
130 pk
->func(0, 0, pk
, 0, pk
->p
);
133 /* --- @pkbuf_free@ --- *
135 * Arguments: @pkbuf *pk@ = pointer to buffer block
136 * @octet **p@ = output pointer to free space
138 * Returns: Free buffer size.
140 * Use: Returns the free portion of a packet buffer. Data can then
141 * be written to this portion, and split out into packets by
142 * calling @pkbuf_flush@. A buffer is allocated if none
146 size_t pkbuf_free(pkbuf
*pk
, octet
**p
)
149 pk
->buf
= x_alloc(pk
->a
, pk
->sz
);
150 *p
= pk
->buf
+ pk
->len
;
151 return (pk
->sz
- pk
->len
);
154 /* --- @pkbuf_snarf@ --- *
156 * Arguments: @pkbuf *pk@ = pointer to buffer block
157 * @const void *p@ = pointer to input data buffer
158 * @size_t sz@ = size of data in input buffer
162 * Use: Snarfs the data from the input buffer and spits it out as
163 * packets. This interface ignores the complexities of dealing
164 * with disablement: you should be using @pkbuf_free@ to
165 * contribute data if you want to cope with that.
168 void pkbuf_snarf(pkbuf
*pk
, const void *p
, size_t sz
)
171 while (sz
&& (pk
->f
& PKBUF_ENABLE
)) {
175 bsz
= pkbuf_free(pk
, &bp
);
179 pkbuf_flush(pk
, bp
, bsz
);
185 /* --- @pkbuf_want@ --- *
187 * Arguments: @pkbuf *pk@ = pointer to buffer block
188 * @size_t want@ = how many octets wanted for next packet
192 * Use: Sets the desired size for the next packet to be read. If
193 * it's larger than the current buffer, the buffer is extended.
196 void pkbuf_want(pkbuf
*pk
, size_t want
)
200 do pk
->sz
<<= 1; while (want
> pk
->sz
);
203 pk
->buf
= x_realloc(pk
->a
, pk
->buf
, pk
->sz
, pk
->len
);
205 x_free(pk
->a
, pk
->buf
);
212 /* --- @pkbuf_init@ --- *
214 * Arguments: @pkbuf *pk@ = pointer to buffer block
215 * @pkbuf *func@ = handler function
216 * @void *p@ = argument pointer for @func@
220 * Use: Initializes a packet buffer block. Any packets are passed to
221 * the provided function for handling.
224 void pkbuf_init(pkbuf
*pk
, pkbuf_func
*func
, void *p
)
229 pk
->f
= PKBUF_ENABLE
;
233 pk
->a
= arena_global
;
236 /* --- @pkbuf_destroy@ --- *
238 * Arguments: @pkbuf *pk@ = pointer to buffer block
242 * Use: Deallocates a line buffer and frees any resources it owned.
245 void pkbuf_destroy(pkbuf
*pk
)
248 x_free(pk
->a
, pk
->buf
);
253 /*----- That's all, folks -------------------------------------------------*/