| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * $Id: pkbuf.c,v 1.7 2004/04/08 01:36:13 mdw Exp $ |
| 4 | * |
| 5 | * Simple packet buffering |
| 6 | * |
| 7 | * (c) 2000 Straylight/Edgeware |
| 8 | */ |
| 9 | |
| 10 | /*----- Licensing notice --------------------------------------------------* |
| 11 | * |
| 12 | * This file is part of the mLib utilities library. |
| 13 | * |
| 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. |
| 18 | * |
| 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. |
| 23 | * |
| 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, |
| 27 | * MA 02111-1307, USA. |
| 28 | */ |
| 29 | |
| 30 | /*----- Header files ------------------------------------------------------*/ |
| 31 | |
| 32 | #include <stdio.h> |
| 33 | #include <stdlib.h> |
| 34 | #include <string.h> |
| 35 | |
| 36 | #include "alloc.h" |
| 37 | #include "arena.h" |
| 38 | #include "pkbuf.h" |
| 39 | |
| 40 | /*----- Main code ---------------------------------------------------------*/ |
| 41 | |
| 42 | /* --- @pkbuf_flush@ --- * |
| 43 | * |
| 44 | * Arguments: @pkbuf *pk@ = pointer to buffer block |
| 45 | * @octet *p@ = pointer to where to start searching |
| 46 | * @size_t len@ = length of new material added |
| 47 | * |
| 48 | * Returns: --- |
| 49 | * |
| 50 | * Use: Flushes any complete packets in a packet buffer. New |
| 51 | * material is assumed to have been added starting at @p@. If |
| 52 | * @p@ is null, then the scan starts at the beginning of the |
| 53 | * buffer, and the size of data already in the buffer is used in |
| 54 | * place of @len@. |
| 55 | * |
| 56 | * It is assumed that the buffer is initially enabled. You |
| 57 | * shouldn't be contributing data to a disabled buffer anyway. |
| 58 | * However, the buffer handler may at some point disable itself, |
| 59 | * and @pkbuf_flush@ can cope with this eventuality. Any |
| 60 | * pending data is left at the start of the buffer and can be |
| 61 | * flushed out by calling @pkbuf_flush(b, 0, 0)@ if the buffer |
| 62 | * is ever re-enabled. |
| 63 | */ |
| 64 | |
| 65 | void pkbuf_flush(pkbuf *pk, octet *p, size_t len) |
| 66 | { |
| 67 | size_t l; |
| 68 | size_t o, keep; |
| 69 | |
| 70 | if (pk->f & PKBUF_CLOSE) { |
| 71 | pk->func(0, 0, pk, 0, pk->p); |
| 72 | return; |
| 73 | } |
| 74 | |
| 75 | /* --- Initialize variables as necessary --- */ |
| 76 | |
| 77 | if (!p) { |
| 78 | p = pk->buf; |
| 79 | len = pk->len; |
| 80 | } |
| 81 | l = p + len - pk->buf; |
| 82 | o = 0; |
| 83 | |
| 84 | /* --- Now grind through any packets which have accumulated --- */ |
| 85 | |
| 86 | pk->len = l; |
| 87 | while (l >= pk->want) { |
| 88 | size_t sz = pk->want; |
| 89 | |
| 90 | /* --- Pass a packet to the user handler --- */ |
| 91 | |
| 92 | keep = 0; |
| 93 | pk->func(pk->buf + o, sz, pk, &keep, pk->p); |
| 94 | |
| 95 | /* --- Adjust all the pointers for the next packet --- */ |
| 96 | |
| 97 | sz -= keep; |
| 98 | o += sz; |
| 99 | l -= sz; |
| 100 | |
| 101 | /* --- Abort here if disabled --- */ |
| 102 | |
| 103 | if (!(pk->f & PKBUF_ENABLE)) |
| 104 | break; |
| 105 | } |
| 106 | |
| 107 | /* --- Shunt data around in the buffer --- */ |
| 108 | |
| 109 | if (o > 0 && l != 0) |
| 110 | memmove(pk->buf, pk->buf + o, l); |
| 111 | pk->len = l; |
| 112 | } |
| 113 | |
| 114 | /* --- @pkbuf_close@ --- * |
| 115 | * |
| 116 | * Arguments: @pkbuf *pk@ = pointer to buffer block |
| 117 | * |
| 118 | * Returns: --- |
| 119 | * |
| 120 | * Use: Informs the client that no more data is likely to arrive. If |
| 121 | * there is a partial packet in the buffer, it is discarded. |
| 122 | */ |
| 123 | |
| 124 | void pkbuf_close(pkbuf *pk) |
| 125 | { |
| 126 | if (pk->buf) { |
| 127 | x_free(pk->a, pk->buf); |
| 128 | pk->buf = 0; |
| 129 | } |
| 130 | pk->f |= PKBUF_CLOSE; |
| 131 | if (pk->f & PKBUF_ENABLE) |
| 132 | pk->func(0, 0, pk, 0, pk->p); |
| 133 | } |
| 134 | |
| 135 | /* --- @pkbuf_free@ --- * |
| 136 | * |
| 137 | * Arguments: @pkbuf *pk@ = pointer to buffer block |
| 138 | * @octet **p@ = output pointer to free space |
| 139 | * |
| 140 | * Returns: Free buffer size. |
| 141 | * |
| 142 | * Use: Returns the free portion of a packet buffer. Data can then |
| 143 | * be written to this portion, and split out into packets by |
| 144 | * calling @pkbuf_flush@. A buffer is allocated if none |
| 145 | * currently exists. |
| 146 | */ |
| 147 | |
| 148 | size_t pkbuf_free(pkbuf *pk, octet **p) |
| 149 | { |
| 150 | if (!pk->buf) |
| 151 | pk->buf = x_alloc(pk->a, pk->sz); |
| 152 | *p = pk->buf + pk->len; |
| 153 | return (pk->sz - pk->len); |
| 154 | } |
| 155 | |
| 156 | /* --- @pkbuf_snarf@ --- * |
| 157 | * |
| 158 | * Arguments: @pkbuf *pk@ = pointer to buffer block |
| 159 | * @const void *p@ = pointer to input data buffer |
| 160 | * @size_t sz@ = size of data in input buffer |
| 161 | * |
| 162 | * Returns: --- |
| 163 | * |
| 164 | * Use: Snarfs the data from the input buffer and spits it out as |
| 165 | * packets. This interface ignores the complexities of dealing |
| 166 | * with disablement: you should be using @pkbuf_free@ to |
| 167 | * contribute data if you want to cope with that. |
| 168 | */ |
| 169 | |
| 170 | void pkbuf_snarf(pkbuf *pk, const void *p, size_t sz) |
| 171 | { |
| 172 | const octet *pp = p; |
| 173 | while (sz && (pk->f & PKBUF_ENABLE)) { |
| 174 | size_t bsz; |
| 175 | octet *bp; |
| 176 | |
| 177 | bsz = pkbuf_free(pk, &bp); |
| 178 | if (bsz > sz) |
| 179 | bsz = sz; |
| 180 | memcpy(bp, pp, bsz); |
| 181 | pkbuf_flush(pk, bp, bsz); |
| 182 | pp += bsz; |
| 183 | sz -= bsz; |
| 184 | } |
| 185 | } |
| 186 | |
| 187 | /* --- @pkbuf_want@ --- * |
| 188 | * |
| 189 | * Arguments: @pkbuf *pk@ = pointer to buffer block |
| 190 | * @size_t want@ = how many octets wanted for next packet |
| 191 | * |
| 192 | * Returns: --- |
| 193 | * |
| 194 | * Use: Sets the desired size for the next packet to be read. If |
| 195 | * it's larger than the current buffer, the buffer is extended. |
| 196 | */ |
| 197 | |
| 198 | void pkbuf_want(pkbuf *pk, size_t want) |
| 199 | { |
| 200 | pk->want = want; |
| 201 | if (want > pk->sz) { |
| 202 | do pk->sz <<= 1; while (want > pk->sz); |
| 203 | if (pk->buf) { |
| 204 | if (pk->len) |
| 205 | pk->buf = x_realloc(pk->a, pk->buf, pk->sz, pk->len); |
| 206 | else { |
| 207 | x_free(pk->a, pk->buf); |
| 208 | pk->buf = 0; |
| 209 | } |
| 210 | } |
| 211 | } |
| 212 | } |
| 213 | |
| 214 | /* --- @pkbuf_init@ --- * |
| 215 | * |
| 216 | * Arguments: @pkbuf *pk@ = pointer to buffer block |
| 217 | * @pkbuf *func@ = handler function |
| 218 | * @void *p@ = argument pointer for @func@ |
| 219 | * |
| 220 | * Returns: --- |
| 221 | * |
| 222 | * Use: Initializes a packet buffer block. Any packets are passed to |
| 223 | * the provided function for handling. |
| 224 | */ |
| 225 | |
| 226 | void pkbuf_init(pkbuf *pk, pkbuf_func *func, void *p) |
| 227 | { |
| 228 | pk->func = func; |
| 229 | pk->p = p; |
| 230 | pk->len = 0; |
| 231 | pk->f = PKBUF_ENABLE; |
| 232 | pk->buf = 0; |
| 233 | pk->sz = 256; |
| 234 | pk->want = 1; |
| 235 | pk->a = arena_global; |
| 236 | } |
| 237 | |
| 238 | /* --- @pkbuf_destroy@ --- * |
| 239 | * |
| 240 | * Arguments: @pkbuf *pk@ = pointer to buffer block |
| 241 | * |
| 242 | * Returns: --- |
| 243 | * |
| 244 | * Use: Deallocates a line buffer and frees any resources it owned. |
| 245 | */ |
| 246 | |
| 247 | void pkbuf_destroy(pkbuf *pk) |
| 248 | { |
| 249 | if (pk->buf) { |
| 250 | x_free(pk->a, pk->buf); |
| 251 | pk->buf = 0; |
| 252 | } |
| 253 | } |
| 254 | |
| 255 | /*----- That's all, folks -------------------------------------------------*/ |