From: Ted Lemon <source@isc.org>
Date: Wed, 5 Mar 1997 06:15:00 +0000 (+0000)
Subject: New IP header checksum code supplied by Anatoli Logvinski
X-Git-Tag: DHCP-970305~15
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f09bfe772e5df38a6d12cb8e3849a9e9181a70ac;p=thirdparty%2Fdhcp.git

New IP header checksum code supplied by Anatoli Logvinski
---

diff --git a/common/packet.c b/common/packet.c
index 1fc9a0bbe..b7752e234 100644
--- a/common/packet.c
+++ b/common/packet.c
@@ -40,9 +40,10 @@
  * Enterprises, see ``http://www.vix.com''.
  */
 
+
 #ifndef lint
 static char copyright[] =
-"$Id: packet.c,v 1.12 1997/02/18 14:32:51 mellon Exp $ Copyright (c) 1996 The Internet Software Consortium.  All rights reserved.\n";
+"$Id: packet.c,v 1.13 1997/03/05 06:15:00 mellon Exp $ Copyright (c) 1996 The Internet Software Consortium.  All rights reserved.\n";
 #endif /* not lint */
 
 #include "dhcpd.h"
@@ -75,7 +76,6 @@ static u_int32_t checksum (buf, nbytes, sum)
 #endif
 		sum += (u_int16_t) ntohs(*((u_int16_t *)buf)++);
 	}	
-
 	/* If there's a single byte left over, checksum it, too.   Network
 	   byte order is big-endian, so the remaining byte is the high byte. */
 	if (i < nbytes) {
@@ -97,26 +97,20 @@ static u_int32_t wrapsum (sum)
 #ifdef DEBUG_CHECKSUM
 	debug ("wrapsum (%x)", sum);
 #endif
-
-	while (sum > 0x10000) {
-		sum = (sum >> 16) + (sum & 0xFFFF);
-#ifdef DEBUG_CHECKSUM_VERBOSE
-		debug ("sum = %x", sum);
-#endif
-		sum += (sum >> 16);
+	while (sum >> 16) {
 #ifdef DEBUG_CHECKSUM_VERBOSE
 		debug ("sum = %x", sum);
 #endif
+		sum = (sum & 0xFFFF) + (sum >> 16);
 	}
-	sum = sum ^ 0xFFFF;
 #ifdef DEBUG_CHECKSUM_VERBOSE
 	debug ("sum = %x", sum);
 #endif
 	
 #ifdef DEBUG_CHECKSUM
-	debug ("wrapsum returns %x", htons (sum));
+	debug ("wrapsum returns %x", htons (~sum));
 #endif
-	return htons(sum);
+	return htons(~sum);
 }
 #endif /* PACKET_ASSEMBLY || PACKET_DECODING */