Merge pull request #12798 from donaldsharp/rib_match_multicast

[mirror_frr.git] / isisd / iso_checksum.c

diff --git a/isisd/iso_checksum.c b/isisd/iso_checksum.c
index d036c0ba7642780119943a2a63ff411532aae016..f12c19577bd72f8e3e0190a2e87df90a0319b935 100644 (file)
--- a/isisd/iso_checksum.c
+++ b/isisd/iso_checksum.c
@@ -1,24 +1,11 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * IS-IS Rout(e)ing protocol - iso_checksum.c
  *                             ISO checksum related routines
  *
  * Copyright (C) 2001,2002   Sampo Saaristo
- *                           Tampere University of Technology      
+ *                           Tampere University of Technology
  *                           Institute of Communications Engineering
- *
- * This program is free software; you can redistribute it and/or modify it 
- * under the terms of the GNU General Public Licenseas published by the Free 
- * Software Foundation; either version 2 of the License, or (at your option) 
- * any later version.
- *
- * This program 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 General Public License for 
- * more details.
- *
- * You should have received a copy of the GNU General Public License along
- * with this program; see the file COPYING; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 #include <zebra.h>
@@ -33,7 +20,7 @@
  *  sum  a (mod 255) = 0
  *     1  i
  *
- *     L 
+ *     L
  *  sum (L-i+1)a (mod 255) = 0
  *     1        i
  *
@@ -45,33 +32,29 @@
  * Based on Annex C.4 of ISO/IEC 8473
  */
 
-int
-iso_csum_verify (u_char * buffer, int len, uint16_t * csum)
+int iso_csum_verify(uint8_t *buffer, int len, uint16_t csum, int offset)
 {
-  u_int16_t checksum;
-  u_int32_t c0;
-  u_int32_t c1;
-
-  c0 = *csum & 0xff00;
-  c1 = *csum & 0x00ff;
-
-  /*
-   * If both are zero return correct
-   */
-  if (c0 == 0 && c1 == 0)
-    return 0;
-
-  /*
-   * If either, but not both are zero return incorrect
-   */
-  if (c0 == 0 || c1 == 0)
-    return 1;
-
-  /* Offset of checksum from the start of the buffer */
-  int offset = (u_char *) csum - buffer;
-
-  checksum = fletcher_checksum(buffer, len, offset);
-  if (checksum == *csum)
-    return 0;
-  return 1;
+       uint16_t checksum;
+       uint32_t c0;
+       uint32_t c1;
+
+       c0 = csum & 0xff00;
+       c1 = csum & 0x00ff;
+
+       /*
+        * If both are zero return correct
+        */
+       if (c0 == 0 && c1 == 0)
+               return 0;
+
+       /*
+        * If either, but not both are zero return incorrect
+        */
+       if (c0 == 0 || c1 == 0)
+               return 1;
+
+       checksum = fletcher_checksum(buffer, len, offset);
+       if (checksum == htons(csum))
+               return 0;
+       return 1;
 }