1 files changed, 97 insertions, 0 deletions
diff --git a/isisd/iso_checksum.c b/isisd/iso_checksum.c
index 294fe994..abd101b9 100644
--- a/isisd/iso_checksum.c
+++ b/isisd/iso_checksum.c
@@ -75,3 +75,100 @@ iso_csum_verify (u_char * buffer, int len, uint16_t * csum)
     return 0;
   return 1;
 }
+<<<<<<< HEAD:isisd/iso_checksum.c
+
+/*
+ * Creates the checksum. *csum points to the position of the checksum in the 
+ * PDU. 
+ * Based on Annex C.4 of ISO/IEC 8473
+ */
+#define FIXED_CODE
+u_int16_t
+iso_csum_create (u_char * buffer, int len, u_int16_t n)
+{
+
+  u_int8_t *p;
+  int x;
+  int y;
+  u_int32_t mul;
+  u_int32_t c0;
+  u_int32_t c1;
+  u_int16_t checksum;
+  u_int16_t *csum;
+  int i, init_len, partial_len;
+
+  checksum = 0;
+
+  /*
+   * Zero the csum in the packet.
+   */
+  csum = (u_int16_t *) (buffer + n);
+  *(csum) = checksum;
+
+  p = buffer;
+  c0 = 0;
+  c1 = 0;
+  init_len = len;
+
+  while (len != 0)
+    {
+      partial_len = MIN(len, 5803);
+
+      for (i = 0; i < partial_len; i++)
+	{
+	  c0 = c0 + *(p++);
+	  c1 += c0;
+	}
+
+      c0 = c0 % 255;
+      c1 = c1 % 255;
+
+      len -= partial_len;
+    }
+
+  mul = (init_len - n)*(c0);
+
+#ifdef FIXED_CODE
+  x = mul - c0 - c1;
+  y = c1 - mul - 1;
+
+  if (y > 0)
+    y++;
+  if (x < 0)
+    x--;
+
+  x %= 255;
+  y %= 255;
+
+  if (x == 0)
+    x = 255;
+  if (y == 0)
+    y = 1;
+
+  checksum = (y << 8) | (x & 0xFF);
+
+#else
+  x = mul - c0 - c1;
+  x %= 255;
+
+  y = c1 - mul - 1;
+  y %= 255;
+
+  if (x == 0)
+    x = 255;
+  if (y == 0)
+    y = 255;
+
+  checksum = ((y << 8) | x);
+#endif
+
+  /*
+   * Now we write this to the packet
+   */
+  *(csum) = checksum;
+
+  /* return the checksum for user usage */
+  return checksum;
+}
+=======
+>>>>>>> 41dc3488cf127a1e23333459a0c316ded67f7ff3:isisd/iso_checksum.c