x509-cert: fixup string representation

x509-cert/src/name.rs

@@ -59,7 +59,8 @@ impl FromStr for RdnSequence {
 /// [RFC 4514]: https://datatracker.ietf.org/doc/html/rfc4514
 impl fmt::Display for RdnSequence {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        for (i, atv) in self.0.iter().enumerate() {
+        // As per RFC 4514 Section 2.1, the elements are reversed
+        for (i, atv) in self.0.iter().rev().enumerate() {
             match i {
                 0 => write!(f, "{}", atv)?,
                 _ => write!(f, ",{}", atv)?,

x509-cert/tests/name.rs

@@ -66,6 +66,21 @@ fn decode_name() {
             counter += 1;
         }
     }
+
+    #[cfg(feature = "std")]
+    {
+        // https://datatracker.ietf.org/doc/html/rfc4514.html#section-2.1
+        // If the RDNSequence is an empty sequence, the result is the empty or
+        // zero-length string.
+        // Otherwise, the output consists of the string encodings of each
+        // RelativeDistinguishedName in the RDNSequence (according to Section 2.2),
+        // starting with the last element of the sequence and moving backwards
+        // toward the first.
+        // The encodings of adjoining RelativeDistinguishedNames are separated by
+        // a comma (',' U+002C) character.
+        let name = rdn1a.to_string();
+        assert_eq!(name, "CN=Good CA,O=Test Certificates 2011,C=US");
+    }
 }
 
 #[test]