1 files changed, 100 insertions, 0 deletions
diff --git a/lib/libatm/ip_checksum.c b/lib/libatm/ip_checksum.c
new file mode 100644
index 0000000..b9c7fa8
--- /dev/null
+++ b/lib/libatm/ip_checksum.c
@@ -0,0 +1,100 @@
+/*
+ *
+ * ===================================
+ * HARP  |  Host ATM Research Platform
+ * ===================================
+ *
+ *
+ * This Host ATM Research Platform ("HARP") file (the "Software") is
+ * made available by Network Computing Services, Inc. ("NetworkCS")
+ * "AS IS".  NetworkCS does not provide maintenance, improvements or
+ * support of any kind.
+ *
+ * NETWORKCS MAKES NO WARRANTIES OR REPRESENTATIONS, EXPRESS OR IMPLIED,
+ * INCLUDING, BUT NOT LIMITED TO, IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS FOR A PARTICULAR PURPOSE, AS TO ANY ELEMENT OF THE
+ * SOFTWARE OR ANY SUPPORT PROVIDED IN CONNECTION WITH THIS SOFTWARE.
+ * In no event shall NetworkCS be responsible for any damages, including
+ * but not limited to consequential damages, arising from or relating to
+ * any use of the Software or related support.
+ *
+ * Copyright 1994-1998 Network Computing Services, Inc.
+ *
+ * Copies of this Software may be made, however, the above copyright
+ * notice must be reproduced on all copies.
+ *
+ *	@(#) $FreeBSD$
+ *
+ */
+
+
+/*
+ * User Space Library Functions
+ * ----------------------------
+ *
+ * IP checksum computation
+ *
+ */
+
+#include <sys/types.h>
+#include <sys/param.h>
+#include <sys/socket.h>
+#include <net/if.h>
+#include <netinet/in.h>
+#include <netatm/port.h>
+#include <netatm/atm.h>
+#include <netatm/atm_if.h>
+#include <netatm/atm_sap.h>
+#include <netatm/atm_sys.h>
+#include <netatm/atm_ioctl.h>
+
+#include "libatm.h"
+
+#ifndef lint
+__RCSID("@(#) $FreeBSD$");
+#endif
+
+
+/*
+ * Compute an IP checksum
+ *
+ * This code was taken from RFC 1071.
+ *
+ * "The following "C" code algorithm computes the checksum with an inner
+ * loop that sums 16 bits at a time in a 32-bit accumulator."
+ *
+ * Arguments:
+ *	addr	pointer to the buffer whose checksum is to be computed
+ *	count	number of bytes to include in the checksum
+ *
+ * Returns:
+ *	the computed checksum
+ *
+ */
+short
+ip_checksum(addr, count)
+	char 	*addr;
+	int	count;
+{
+	/* Compute Internet Checksum for "count" bytes
+	 * beginning at location "addr".
+	 */
+	register long sum = 0;
+
+	while( count > 1 ) {
+		/* This is the inner loop */
+		sum += ntohs(* (unsigned short *) addr);
+		addr += sizeof(unsigned short);
+		count -= sizeof(unsigned short);
+	}
+
+	/* Add left-over byte, if any */
+	if( count > 0 )
+		sum += * (unsigned char *) addr;
+
+	/* Fold 32-bit sum to 16 bits */
+	while (sum>>16)
+		sum = (sum & 0xffff) + (sum >> 16);
+
+	return((short)~sum);
+}