diff -ru diald-1.0.orig/buffer.c diald-1.0/buffer.c
--- diald-1.0.orig/buffer.c	2001-06-16 15:51:39.000000000 -0400
+++ diald-1.0/buffer.c	2005-10-04 10:38:22.331362000 -0400
@@ -3,6 +3,7 @@
  *
  * Copyright (c) 1994, 1995, 1996 Eric Schenk.
  * Copyright (c) 1999 Mike Jagdis.
+ * Copyright (c) 2002 Jason Turner.
  * All rights reserved. Please see the file LICENSE which should be
  * distributed with this software for terms of use.
  */
@@ -11,90 +12,195 @@
 
 #include <diald.h>
 
+#define BUFFER_CHUNK_SIZE_MAX 4096
 
-#define B(i) buffer[(i)%buffer_size]
-
-static int oldsize = 0;
-static unsigned char *buffer = 0;
-static int head = 0;
-static int used = 0;
-static int tail = 0;
+#ifndef UINT_MAX
+#define UINT_MAX (~0U)
+#endif
 
-void buffer_init(int *var, char **argv)
-{
-    buffer_size = atoi(*argv);
-    if (buffer_size != oldsize) {
-	if (buffer)
-		free(buffer);
-	buffer = malloc(buffer_size);
-	oldsize = buffer_size;
+struct bpkt_hdr {			/* Buffered packet header */
+    unsigned long expires;		/* When it expires in uptime secs */
+    unsigned int len;			/* Length of following packet,
+					 * up to BUFFER_CHUNK_SIZE_MAX */
+};
+
+static char *buffer = 0;		/* start address of ring buffer */
+static char *buffer_end = 0;		/* end address (+1) of ring buffer */
+static unsigned int true_size = 0;	/* actual size of buffer */
+static unsigned int used = 0;		/* bytes used */
+static unsigned int head = 0;		/* read offset */
+static unsigned int tail = 0;		/* write offset */
+
+/* buffer_setup()
+ * Create/recreate/delete the buffer and setup pointers.
+ * Returns the actual buffer size.
+ * The buffer_size variable is declared in diald.h and is given an initial
+ * value in options.c .
+ */
+static unsigned int buffer_setup() {
+    if ( buffer_size < 0 || buffer_size > UINT_MAX ) {
+	mon_syslog(LOG_ERR,"Ignoring invalid buffer_size request.");
+    } else {
+	/* discard existing buffer and any contents */
+	if (buffer) {
+	    free(buffer);
+	    buffer = 0;
+	}
+	true_size = 0; used = 0; head = 0; tail = 0;
+	if (buffer_size) {
+	    /* create new buffer */
+	    if (buffer = malloc(buffer_size)) {
+		true_size = buffer_size;
+		buffer_end = buffer + true_size;
+	    } else {
+		mon_syslog(LOG_ERR, "Out of memory! Cannot create ring buffer.");
+		/* This is not fatal. diald will run fine without the buffer. */
+	    }
+	}
     }
+    return true_size;
 }
 
+/* buffer_check()
+ * If there is no buffer_size param in the config file, the buffer is not
+ * initially set up!
+ * So call this from forward_buffer() and buffer_packet()
+ */
 static void buffer_check()
 {
-    if (!buffer) {
-	buffer = malloc(buffer_size);
-	oldsize = buffer_size;
+    if (buffer)
+	return;
+    if (!buffer_setup()) {
+	/* if we cannot create a buffer, then disable the feature to avoid
+	 * repeated calls.  */
+	buffer_packets = 0;
+	mon_syslog(LOG_WARNING,"No buffer: buffer-packets feature disabled.");
     }
 }
 
+/* buffer_write()
+ * Write data to the ring buffer, adjust tail offset and space used
+ * Should not be called unless sure there is enough free space
+ */
+static void buffer_write(unsigned int count, char *pkt) {
+    char *write_ptr = buffer + tail;
+
+    if (write_ptr + count > buffer_end) {
+	unsigned int count2end = buffer_end - write_ptr;
+	memcpy(write_ptr, pkt, count2end);
+	memcpy(buffer, pkt + count2end, count - count2end);
+    } else {
+	memcpy(write_ptr, pkt, count);
+    }
+    tail = (tail+count)%true_size;
+    used += count;
+}
 
-void buffer_packet(unsigned int len,unsigned char *pkt)
+/* buffer_read()
+ * Read bytes from ring buffer. Do not delete.
+ * Should not be called unless used is positive.
+ */
+static void buffer_read(unsigned int count, char *pkt) {
+    char *read_ptr = buffer + head;
+
+    if (read_ptr + count > buffer_end) {
+	unsigned int count2end = buffer_end - read_ptr;
+	memcpy(pkt, read_ptr, count2end);
+	memcpy(pkt + count2end, buffer, count - count2end);
+    } else {
+	memcpy(pkt, read_ptr, count);
+    }
+}
+
+/* buffer_dispose()
+ * Delete from ring buffer by adjusting read offset
+ */
+static void buffer_dispose(unsigned int count) {
+    head = (head+count)%true_size;
+    used -= count;
+}
+
+/* externally linked functions */
+
+/* buffer_init()
+ * This is called when reading the config file or command line options.
+ * There will be at least one argument, but the arg was not checked to be a
+ * numeric string.
+ */
+void buffer_init(int *var, char **argv)
+{
+    buffer_size = strtol(*argv, NULL, 0);
+    if (buffer_size != true_size)
+    	buffer_setup();
+}
+
+/* buffer_packet()
+ * Place packet into the ring.
+ */
+void buffer_packet(unsigned int len, unsigned char *pkt)
 {
-    unsigned int clen;
-    unsigned long stamp;
+    struct bpkt_hdr pkt_hdr;
     unsigned long ctime = timestamp();
+    unsigned int space_needed = len + sizeof(struct bpkt_hdr);
+
+    if (len > BUFFER_CHUNK_SIZE_MAX) {
+	mon_syslog(LOG_WARNING, "Packet too large to buffer: %d", len);
+	return;
+    }
 
     buffer_check();
-    if (len+6 > buffer_size) {
+
+    if (space_needed > true_size) {
 	mon_syslog(LOG_NOTICE,
 	    "Can't buffer packet of length %d, buffer too small",
 	    len);
 	return;
     }
+
+    /* TODO
+     * Add buffer filtering ?
+     * eg. ntp packets do not fare well to long delays
+     * The expires time could also be different for each packet.
+     */
+
     if (buffer_fifo_dispose) {
 	/* toss from the front of the buffer till we have space */
-	while (used+len+6 > buffer_size) {
-	    clen = (B(head)<<8) | B(head+1);
-	    head = (head+6+clen)%buffer_size;
-	    used -= (6+clen);
+	while (used + space_needed > true_size) {
+	    buffer_read(sizeof(struct bpkt_hdr), (char *)&pkt_hdr);
+	    buffer_dispose(sizeof(struct bpkt_hdr) + pkt_hdr.len);
 	}
     } else {
+	/* toss out expired packets from front of buffer
+	 * Any expired packets in the middle will be killed when forwarding
+	 */
 	for (;;) {
-	    clen = (B(head)<<8) | B(head+1);
-	    stamp = (B(head+2)<<24) | (B(head+3)<<16) | (B(head+4)<<8) | B(head+5);
-	    if (stamp+buffer_timeout >= ctime)
+	    if (!used)
+		break;
+	    buffer_read(sizeof(struct bpkt_hdr), (char *)&pkt_hdr);
+	    if (pkt_hdr.expires >= ctime)
 		break;
-	    head = (head+6+clen)%buffer_size;
-	    used -= (6+clen);
+	    buffer_dispose(sizeof(struct bpkt_hdr) + pkt_hdr.len);
 	}
     }
-    if (used+len+6 <= buffer_size) {
-	used = used + 6 + len;
-	B(tail) = (len>>8)&0xff;
-	B(tail+1) = len&0xff;
-	B(tail+2) = (ctime>>24)&0xff;
-	B(tail+3) = (ctime>>16)&0xff;
-	B(tail+4) = (ctime>>8)&0xff;
-	B(tail+5) = ctime&0xff;
-	tail = (tail+6)%buffer_size;
-	while (len--) {
-	    buffer[tail] = *pkt++;
-	    tail = (tail+1)%buffer_size;
-	}
+    if (used + space_needed <= true_size) {
+	pkt_hdr.len = len;
+	pkt_hdr.expires = ctime + buffer_timeout;
+	buffer_write(sizeof(struct bpkt_hdr), (char *)&pkt_hdr);
+	buffer_write(len, pkt);
     } else {
 	mon_syslog(LOG_NOTICE,
 	    "Can't buffer packet of length %d, only %d bytes available.",
-	    len,buffer_size-(used+6));
+	    len, true_size - ( used + sizeof(struct bpkt_hdr) ) );
     }
 }
 
+/* forward_buffer()
+ * Clears ring buffer and sends unexpired packets on their way.
+ */
 void forward_buffer()
 {
+    struct bpkt_hdr pkt_hdr;
     int forwarding = 0;
-    unsigned int clen, i;
-    unsigned long stamp;
     unsigned long ctime = timestamp();
     struct sockaddr_pkt sp;
 #ifdef HAVE_AF_PACKET
@@ -102,7 +208,7 @@
 #endif
     struct sockaddr *to;
     size_t to_len;
-    unsigned char pkt[4096];
+    char pkt[BUFFER_CHUNK_SIZE_MAX];
 
 #ifdef __linux__
     /* If we are using dynamic addresses we need to know whether we
@@ -141,19 +247,19 @@
     }
 
     while (used > 0) {
-	clen = (B(head)<<8) | B(head+1);
-	stamp = (B(head+2)<<24) | (B(head+3)<<16) | (B(head+4)<<8) | B(head+5);
-        if (stamp+buffer_timeout >= ctime) {
+	buffer_read(sizeof(struct bpkt_hdr), (char *)&pkt_hdr);
+	buffer_dispose(sizeof(struct bpkt_hdr));
+        if (pkt_hdr.expires >= ctime) {
 	    unsigned short wprot;
-	    unsigned char *dpkt;
+	    char *dpkt;
 	    unsigned int dlen;
 
-	    for (i = 0; i < clen; i++)
-		pkt[i] = B(head+6+i);
+	    buffer_read(pkt_hdr.len, pkt);
 
+	    /* strip off the protocol from the raw packet */
 	    wprot = *(unsigned short *)pkt;
 	    dpkt = pkt + sizeof(unsigned short);
-	    dlen = clen - sizeof(unsigned short);
+	    dlen = pkt_hdr.len - sizeof(unsigned short);
 
 	    /* If we are using dynamic addresses and forwarding traffic
 	     * we send the packet back in to the kernel on the proxy so
@@ -180,7 +286,6 @@
 		    mon_syslog(LOG_ERR,"Error forwarding data packet to physical device from buffer: %m");
 	    }
 	}
-	head = (head+6+clen)%buffer_size;
-	used -= (6+clen);
+	buffer_dispose(pkt_hdr.len);
     }
 }