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,
35 /*----- Header files ------------------------------------------------------*/
47 /*----- Data structures ---------------------------------------------------*/
51 typedef void pkbuf_func(octet */*b*/, size_t /*sz*/,
52 struct pkbuf */*pk*/, size_t */*keep*/,
55 typedef struct pkbuf {
56 size_t sz; /* Size of current buffer */
57 size_t len; /* Length of data in the buffer */
58 size_t want; /* Want this many bytes for packet */
59 unsigned f; /* Various state flags */
60 pkbuf_func *func; /* Handler function */
61 void *p; /* Argument for handler */
62 arena *a; /* Memory allocation arena */
63 octet *buf; /* Actual buffer space */
66 #define PKBUF_ENABLE 1u /* Buffer is currently enabled */
67 #define PKBUF_CLOSE 2u /* Buffer is now closed */
69 /*----- Functions provided ------------------------------------------------*/
71 /* --- @pkbuf_flush@ --- *
73 * Arguments: @pkbuf *pk@ = pointer to buffer block
74 * @octet *p@ = pointer to where to start searching
75 * @size_t len@ = length of new material added
79 * Use: Flushes any complete packets in a packet buffer. New
80 * material is assumed to have been added starting at @p@. If
81 * @p@ is null, then the scan starts at the beginning of the
82 * buffer, and the size of data already in the buffer is used in
85 * It is assumed that the buffer is initially enabled. You
86 * shouldn't be contributing data to a disabled buffer anyway.
87 * However, the buffer handler may at some point disable itself,
88 * and @pkbuf_flush@ can cope with this eventuality. Any
89 * pending data is left at the start of the buffer and can be
90 * flushed out by calling @pkbuf_flush(b, 0, 0)@ if the buffer
94 extern void pkbuf_flush(pkbuf */*pk*/, octet */*p*/, size_t /*len*/);
96 /* --- @pkbuf_close@ --- *
98 * Arguments: @pkbuf *pk@ = pointer to buffer block
102 * Use: Informs the client that no more data is likely to arrive. If
103 * there is a partial packet in the buffer, it is discarded.
106 extern void pkbuf_close(pkbuf */*pk*/);
108 /* --- @pkbuf_free@ --- *
110 * Arguments: @pkbuf *pk@ = pointer to buffer block
111 * @octet **p@ = output pointer to free space
113 * Returns: Free buffer size.
115 * Use: Returns the free portion of a packet buffer. Data can then
116 * be written to this portion, and split out into packets by
117 * calling @pkbuf_flush@.
120 extern size_t pkbuf_free(pkbuf */*pk*/, octet **/*p*/);
122 /* --- @pkbuf_snarf@ --- *
124 * Arguments: @pkbuf *pk@ = pointer to buffer block
125 * @const void *p@ = pointer to input data buffer
126 * @size_t sz@ = size of data in input buffer
130 * Use: Snarfs the data from the input buffer and spits it out as
131 * packets. This interface ignores the complexities of dealing
132 * with disablement: you should be using @pkbuf_free@ to
133 * contribute data if you want to cope with that.
136 extern void pkbuf_snarf(pkbuf */*pk*/, const void */*p*/, size_t /*sz*/);
138 /* --- @pkbuf_want@ --- *
140 * Arguments: @pkbuf *pk@ = pointer to buffer block
141 * @size_t want@ = how many octets wanted for next packet
145 * Use: Sets the desired size for the next packet to be read. If
146 * it's larger than the current buffer, the buffer is extended.
149 extern void pkbuf_want(pkbuf */*pk*/, size_t /*want*/);
151 /* --- @pkbuf_init@ --- *
153 * Arguments: @pkbuf *pk@ = pointer to buffer block
154 * @pkbuf_func *func@ = handler function
155 * @void *p@ = argument pointer for @func@
159 * Use: Initializes a packet buffer block. Any packets are passed to
160 * the provided function for handling.
163 extern void pkbuf_init(pkbuf */*pk*/, pkbuf_func */*func*/, void */*p*/);
165 /* --- @pkbuf_destroy@ --- *
167 * Arguments: @pkbuf *pk@ = pointer to buffer block
171 * Use: Deallocates a packet buffer and frees any resources it owned.
174 extern void pkbuf_destroy(pkbuf */*pk*/);
176 /*----- That's all, folks -------------------------------------------------*/