Extract function to convert ASN.1 INTEGER object to u_int64_t

src/libstrongswan/asn1/asn1.c

@@ -549,6 +549,22 @@ bool asn1_parse_simple_object(chunk_t *object, asn1_t type, u_int level, const c
 	return TRUE;
 }
 
+/*
+ * Described in header
+ */
+u_int64_t asn1_parse_integer_uint64(chunk_t blob)
+{
+	u_int64_t val = 0;
+	int i;
+
+	for (i = 0; i < blob.len; i++)
+	{	/* if it is longer than 8 bytes, we just use the 8 LSBs */
+		val <<= 8;
+		val |= (u_int64_t)blob.ptr[i];
+	}
+	return val;
+}
+
 /**
  * ASN.1 definition of an algorithmIdentifier
  */

src/libstrongswan/asn1/asn1.h

@@ -170,6 +170,15 @@ int asn1_parse_algorithmIdentifier(chunk_t blob, int level0, chunk_t *params);
 bool asn1_parse_simple_object(chunk_t *object, asn1_t type, u_int level0,
 							  const char* name);
 
+/**
+ * Converts an ASN.1 INTEGER object to an u_int64_t. If the INTEGER is longer
+ * than 8 bytes only the 8 LSBs are returned.
+ *
+ * @param blob		body of an ASN.1 coded integer object
+ * @return			converted integer
+ */
+u_int64_t asn1_parse_integer_uint64(chunk_t blob);
+
 /**
  * Print the value of an ASN.1 simple object
  *