--- /dev/null
+/* -*-c-*-
+ *
+ * Simple packet buffering
+ *
+ * (c) 2000 Straylight/Edgeware
+ */
+
+/*----- Licensing notice --------------------------------------------------*
+ *
+ * This file is part of the mLib utilities library.
+ *
+ * mLib is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Library General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * mLib is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with mLib; if not, write to the Free
+ * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+ * MA 02111-1307, USA.
+ */
+
+/*----- Header files ------------------------------------------------------*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "alloc.h"
+#include "arena.h"
+#include "pkbuf.h"
+
+/*----- Main code ---------------------------------------------------------*/
+
+/* --- @pkbuf_flush@ --- *
+ *
+ * Arguments: @pkbuf *pk@ = pointer to buffer block
+ * @octet *p@ = pointer to where to start searching
+ * @size_t len@ = length of new material added
+ *
+ * Returns: ---
+ *
+ * Use: Flushes any complete packets in a packet buffer. New
+ * material is assumed to have been added starting at @p@. If
+ * @p@ is null, then the scan starts at the beginning of the
+ * buffer, and the size of data already in the buffer is used in
+ * place of @len@.
+ *
+ * It is assumed that the buffer is initially enabled. You
+ * shouldn't be contributing data to a disabled buffer anyway.
+ * However, the buffer handler may at some point disable itself,
+ * and @pkbuf_flush@ can cope with this eventuality. Any
+ * pending data is left at the start of the buffer and can be
+ * flushed out by calling @pkbuf_flush(b, 0, 0)@ if the buffer
+ * is ever re-enabled.
+ */
+
+void pkbuf_flush(pkbuf *pk, octet *p, size_t len)
+{
+ size_t l;
+ size_t o, keep;
+
+ if (pk->f & PKBUF_CLOSE) {
+ pk->func(0, 0, pk, 0, pk->p);
+ return;
+ }
+
+ /* --- Initialize variables as necessary --- */
+
+ if (!p) {
+ p = pk->buf;
+ len = pk->len;
+ }
+ l = p + len - pk->buf;
+ o = 0;
+
+ /* --- Now grind through any packets which have accumulated --- */
+
+ pk->len = l;
+ while (l >= pk->want) {
+ size_t sz = pk->want;
+
+ /* --- Pass a packet to the user handler --- */
+
+ keep = 0;
+ pk->func(pk->buf + o, sz, pk, &keep, pk->p);
+
+ /* --- Adjust all the pointers for the next packet --- */
+
+ sz -= keep;
+ o += sz;
+ l -= sz;
+
+ /* --- Abort here if disabled --- */
+
+ if (!(pk->f & PKBUF_ENABLE))
+ break;
+ }
+
+ /* --- Shunt data around in the buffer --- */
+
+ if (o > 0 && l != 0)
+ memmove(pk->buf, pk->buf + o, l);
+ pk->len = l;
+}
+
+/* --- @pkbuf_close@ --- *
+ *
+ * Arguments: @pkbuf *pk@ = pointer to buffer block
+ *
+ * Returns: ---
+ *
+ * Use: Informs the client that no more data is likely to arrive. If
+ * there is a partial packet in the buffer, it is discarded.
+ */
+
+void pkbuf_close(pkbuf *pk)
+{
+ if (pk->buf) {
+ x_free(pk->a, pk->buf);
+ pk->buf = 0;
+ }
+ pk->f |= PKBUF_CLOSE;
+ if (pk->f & PKBUF_ENABLE)
+ pk->func(0, 0, pk, 0, pk->p);
+}
+
+/* --- @pkbuf_free@ --- *
+ *
+ * Arguments: @pkbuf *pk@ = pointer to buffer block
+ * @octet **p@ = output pointer to free space
+ *
+ * Returns: Free buffer size.
+ *
+ * Use: Returns the free portion of a packet buffer. Data can then
+ * be written to this portion, and split out into packets by
+ * calling @pkbuf_flush@. A buffer is allocated if none
+ * currently exists.
+ */
+
+size_t pkbuf_free(pkbuf *pk, octet **p)
+{
+ if (!pk->buf)
+ pk->buf = x_alloc(pk->a, pk->sz);
+ *p = pk->buf + pk->len;
+ return (pk->sz - pk->len);
+}
+
+/* --- @pkbuf_snarf@ --- *
+ *
+ * Arguments: @pkbuf *pk@ = pointer to buffer block
+ * @const void *p@ = pointer to input data buffer
+ * @size_t sz@ = size of data in input buffer
+ *
+ * Returns: ---
+ *
+ * Use: Snarfs the data from the input buffer and spits it out as
+ * packets. This interface ignores the complexities of dealing
+ * with disablement: you should be using @pkbuf_free@ to
+ * contribute data if you want to cope with that.
+ */
+
+void pkbuf_snarf(pkbuf *pk, const void *p, size_t sz)
+{
+ const octet *pp = p;
+ while (sz && (pk->f & PKBUF_ENABLE)) {
+ size_t bsz;
+ octet *bp;
+
+ bsz = pkbuf_free(pk, &bp);
+ if (bsz > sz)
+ bsz = sz;
+ memcpy(bp, pp, bsz);
+ pkbuf_flush(pk, bp, bsz);
+ pp += bsz;
+ sz -= bsz;
+ }
+}
+
+/* --- @pkbuf_want@ --- *
+ *
+ * Arguments: @pkbuf *pk@ = pointer to buffer block
+ * @size_t want@ = how many octets wanted for next packet
+ *
+ * Returns: ---
+ *
+ * Use: Sets the desired size for the next packet to be read. If
+ * it's larger than the current buffer, the buffer is extended.
+ */
+
+void pkbuf_want(pkbuf *pk, size_t want)
+{
+ pk->want = want;
+ if (want > pk->sz) {
+ do pk->sz <<= 1; while (want > pk->sz);
+ if (pk->buf) {
+ if (pk->len)
+ pk->buf = x_realloc(pk->a, pk->buf, pk->sz, pk->len);
+ else {
+ x_free(pk->a, pk->buf);
+ pk->buf = 0;
+ }
+ }
+ }
+}
+
+/* --- @pkbuf_init@ --- *
+ *
+ * Arguments: @pkbuf *pk@ = pointer to buffer block
+ * @pkbuf *func@ = handler function
+ * @void *p@ = argument pointer for @func@
+ *
+ * Returns: ---
+ *
+ * Use: Initializes a packet buffer block. Any packets are passed to
+ * the provided function for handling.
+ */
+
+void pkbuf_init(pkbuf *pk, pkbuf_func *func, void *p)
+{
+ pk->func = func;
+ pk->p = p;
+ pk->len = 0;
+ pk->f = PKBUF_ENABLE;
+ pk->buf = 0;
+ pk->sz = 256;
+ pk->want = 1;
+ pk->a = arena_global;
+}
+
+/* --- @pkbuf_destroy@ --- *
+ *
+ * Arguments: @pkbuf *pk@ = pointer to buffer block
+ *
+ * Returns: ---
+ *
+ * Use: Deallocates a line buffer and frees any resources it owned.
+ */
+
+void pkbuf_destroy(pkbuf *pk)
+{
+ if (pk->buf) {
+ x_free(pk->a, pk->buf);
+ pk->buf = 0;
+ }
+}
+
+/*----- That's all, folks -------------------------------------------------*/
~mdw / mLib / blobdiff