lib: support x509-parser Ia5String DistinguishedNames

This commit updates the logic for converting from the x509-parser
distinguished name types into the rcgen equivalent in order to support
`Ia5String` values.

A small unit test is added that shows round-tripping a certificate with
a subject containing an `Ia5String`, serializing it, parsing with
x509-parser, and then recreating `CertificateParams` from the DER using
`from_ca_cert_der`.

rcgen/src/lib.rs

@@ -473,20 +473,15 @@ impl DistinguishedName {
 				.ok_or(Error::CouldNotParseCertificate)?;
 			let dn_type = DnType::from_oid(&attr_type_oid.collect::<Vec<_>>());
 			let data = attr.attr_value().data;
+			let try_str =
+				|data| std::str::from_utf8(data).map_err(|_| Error::CouldNotParseCertificate);
 			let dn_value = match attr.attr_value().header.tag() {
 				Tag::BmpString => DnValue::BmpString(data.into()),
-				Tag::PrintableString => {
-					let data =
-						std::str::from_utf8(data).map_err(|_| Error::CouldNotParseCertificate)?;
-					DnValue::PrintableString(data.to_owned())
-				},
+				Tag::Ia5String => DnValue::Ia5String(try_str(data)?.to_owned()),
+				Tag::PrintableString => DnValue::PrintableString(try_str(data)?.to_owned()),
 				Tag::T61String => DnValue::TeletexString(data.into()),
 				Tag::UniversalString => DnValue::UniversalString(data.into()),
-				Tag::Utf8String => {
-					let data =
-						std::str::from_utf8(data).map_err(|_| Error::CouldNotParseCertificate)?;
-					DnValue::Utf8String(data.to_owned())
-				},
+				Tag::Utf8String => DnValue::Utf8String(try_str(data)?.to_owned()),
 				_ => return Err(Error::CouldNotParseCertificate),
 			};
 

rcgen/tests/generic.rs

@@ -299,3 +299,40 @@ mod test_parse_crl_dps {
 		);
 	}
 }
+
+#[cfg(feature = "x509-parser")]
+mod test_parse_ia5string_subject {
+	use crate::util;
+	use rcgen::DnType::CustomDnType;
+	use rcgen::{Certificate, CertificateParams, DistinguishedName, DnValue, KeyPair};
+
+	#[test]
+	fn parse_ia5string_subject() {
+		// Create and serialize a certificate with a subject containing an IA5String email address.
+		let email_address_dn_type = CustomDnType(vec![1, 2, 840, 113549, 1, 9, 1]); // id-emailAddress
+		let email_address_dn_value = DnValue::Ia5String("[email protected]".into());
+		let mut params = util::default_params();
+		params.distinguished_name = DistinguishedName::new();
+		params.distinguished_name.push(
+			email_address_dn_type.clone(),
+			email_address_dn_value.clone(),
+		);
+		let cert = Certificate::from_params(params).unwrap();
+		let cert_der = cert.serialize_der().unwrap();
+
+		// We should be able to parse the certificate with x509-parser.
+		assert!(x509_parser::parse_x509_certificate(&cert_der).is_ok());
+
+		// We should be able to reconstitute params from the DER using x509-parser.
+		let key_pair = KeyPair::generate(&rcgen::PKCS_ECDSA_P256_SHA256).unwrap();
+		let params_from_cert = CertificateParams::from_ca_cert_der(&cert_der, key_pair).unwrap();
+
+		// We should find the expected distinguished name in the reconstituted params.
+		let expected_names = &[(&email_address_dn_type, &email_address_dn_value)];
+		let names = params_from_cert
+			.distinguished_name
+			.iter()
+			.collect::<Vec<(_, _)>>();
+		assert_eq!(names, expected_names);
+	}
+}