Work on lsupdates continues. Some checksum cleanup.

1 files changed, 52 insertions, 35 deletions

diff --git a/proto/ospf/lsalib.c b/proto/ospf/lsalib.c
index 72ca55c..a7ef804 100644
--- a/proto/ospf/lsalib.c
+++ b/proto/ospf/lsalib.c
@@ -230,62 +230,79 @@ ntohlsab(void *n, void *h, u8 type, u16 len)
 #define LSA_CHECKSUM_OFFSET    15
 
 /* FIXME This is VERY uneficient, I have huge endianity problems */
-
 void
 lsasum_calculate(struct ospf_lsa_header *h,void *body,struct proto_ospf *po)
 {
+  u16 length;
+  
+  length=h->length;
+
+  htonlsah(h,h);
+  htonlsab(body,body,h->type,length);
+
+  (void)lsasum_check(h,body,po);
+  
+  ntohlsah(h,h);
+  ntohlsab(body,body,h->type,length);
+}
+
+/*
+ * Note, that this function expects that LSA is in big endianity
+ * It also returns value in big endian
+ */
+u16
+lsasum_check(struct ospf_lsa_header *h,void *body,struct proto_ospf *po)
+{
   u8 *sp, *ep, *p, *q, *b;
   int c0 = 0, c1 = 0;
   int x, y;
-  u16 length;
+  u16 length,chsum;
 
-  h->checksum = 0;
   b=body;
-  length = h->length-2;
   sp = (char *) &h->options;
-
-  htonlsah(h,h);
-  htonlsab(b,b,h->type,length+2);
+  length=ntohs(h->length)-2;
+  h->checksum = 0;
 
   for (ep = sp + length; sp < ep; sp = q)
+  {		/* Actually MODX is very large, do we need the for-cyclus? */
+    q = sp + MODX;
+    if (q > ep) q = ep;
+    for (p = sp; p < q; p++)
     {
-      q = sp + MODX;
-      if (q > ep)
-        q = ep;
-      for (p = sp; p < q; p++)
-        {
-          if(p<(u8 *)(h+1))
-	  {
-            c0 += *p;
-	    /*DBG("XXXXXX: %u\t%u\n", p-sp, *p);*/
-	  }
-	  else
-          {
-            c0 += *(b+(p-sp)-sizeof(struct ospf_lsa_header)+2);
-	    /*DBG("YYYYYY: %u\t%u\n", p-sp,*(b+(p-sp)-sizeof(struct ospf_lsa_header)+2));*/
-          }
-          c1 += c0;
-        }
-      c0 %= 255;
-      c1 %= 255;
+      /* 
+       * I count with bytes from header and than from body
+       * but if there is no body, it's appended to header
+       * (probably checksum in update receiving) and I go on
+       * after header
+       */
+      if((b==NULL) || (p<(u8 *)(h+1)))
+      {
+	      c0 += *p;
+      }
+      else
+      {
+	      c0 += *(b+(p-sp)-sizeof(struct ospf_lsa_header)+2);
+      }
+
+      c1 += c0;
     }
+    c0 %= 255;
+    c1 %= 255;
+  }
 
   x = ((length - LSA_CHECKSUM_OFFSET) * c0 - c1) % 255;
-  if (x <= 0)
-    x += 255;
+  if (x <= 0) x += 255;
   y = 510 - c0 - x;
-  if (y > 255)
-    y -= 255;
+  if (y > 255) y -= 255;
 
-  h->checksum = x + (y << 8);
-  
-  ntohlsah(h,h);
-  ntohlsab(b,b,h->type,length+2);
+  chsum= x + (y << 8);
+  h->checksum = chsum;
+  return chsum;
 }
 
 int
 lsa_comp(struct ospf_lsa_header *l1, struct ospf_lsa_header *l2)
-			/* Return codes form view of l1 */
+			/* Return codes from point of view of l1 */
 {
   if(l1->sn<l2->sn) return CMP_NEWER;
     if(l1->sn==l2->sn)