asn1: Add function to generate an ASN.1 integer from an uint64_t

src/libstrongswan/asn1/asn1.c

@@ -609,6 +609,26 @@ uint64_t asn1_parse_integer_uint64(chunk_t blob)
 	return val;
 }
 
+/*
+ * Described in header
+ */
+chunk_t asn1_integer_from_uint64(uint64_t val)
+{
+	u_char buf[sizeof(val)];
+	chunk_t enc = chunk_empty;
+
+	if (val < 0x100)
+	{
+		buf[0] = (u_char)val;
+		return chunk_clone(chunk_create(buf, 1));
+	}
+	for (enc.ptr = buf + sizeof(val); val; enc.len++, val >>= 8)
+	{	/* fill the buffer from the end */
+		*(--enc.ptr) = val & 0xff;
+	}
+	return chunk_clone(enc);
+}
+
 /**
  * ASN.1 definition of an algorithmIdentifier
  */

src/libstrongswan/asn1/asn1.h

@@ -180,6 +180,14 @@ bool asn1_parse_simple_object(chunk_t *object, asn1_t type, u_int level0,
  */
 uint64_t asn1_parse_integer_uint64(chunk_t blob);
 
+/**
+ * Converts an uint64_t to an ASN.1 INTEGER object.
+ *
+ * @param val		integer to convert
+ * @return			body of an ASN.1 coded integer object
+ */
+chunk_t asn1_integer_from_uint64(uint64_t val);
+
 /**
  * Print the value of an ASN.1 simple object
  *