Implement SEQUENCE encoding and decoding in client

client/src/der.vala

@@ -7,24 +7,26 @@ namespace StudySystemClient.Der {
 
 	private const uint BASE_HEADER_SIZE = 2;
 
-	public static Datum decode(uint8[] bytes) throws DecodeError {
+	public static Datum decode(uint8[] bytes, out uint? size = null)
+			throws DecodeError {
 		if (bytes.length < BASE_HEADER_SIZE) {
 			throw new DecodeError.INCOMPLETE(
 				"Message is fewer than %u bytes", BASE_HEADER_SIZE);
 		}
 
-		uint header_size = 0;
-		var length = decode_length(bytes, ref header_size);
+		uint header_size;
+		var length = decode_length(bytes, out header_size);
 		if (header_size + length > bytes.length) {
 			throw new DecodeError.INCOMPLETE(
 				"Length %u but only %u bytes available", length,
 				bytes.length - header_size);
 		}
 		var content = bytes[header_size:header_size + length];
+		size = header_size + length;
 		return decode_datum(bytes[0], content);
 	}
 
-	private static uint decode_length(uint8[] bytes, ref uint header_size)
+	private static uint decode_length(uint8[] bytes, out uint header_size)
 			throws DecodeError {
 		if ((bytes[1] & 0x80) != 0) {
 			var length_size = bytes[1] & 0x7f;
@@ -53,6 +55,8 @@ namespace StudySystemClient.Der {
 			return new Integer.from_content(content);
 		case Utf8String.TYPE:
 			return new Utf8String.from_content(content);
+		case Sequence.TYPE:
+			return new Sequence.from_content(content);
 		default:
 			throw new DecodeError.UNKNOWN_TYPE("Unsupported type: %02x",
 											   type);
@@ -214,11 +218,48 @@ namespace StudySystemClient.Der {
 			value = decode_string(bytes);
 		}
 
-		public static string decode_string(uint8[] bytes) {
+		private static string decode_string(uint8[] bytes) {
 			var buffer = new uint8[bytes.length + 1];
 			Memory.copy(buffer, bytes, bytes.length);
 			buffer[bytes.length] = 0;
 			return (string)buffer;
 		}
 	}
+
+	public class Sequence : Datum {
+		internal const uint8 TYPE = 0x30;
+
+		public Datum[] value { get; private set; }
+
+		public Sequence(Datum[] val) {
+			type = TYPE;
+			content = encode_array(val);
+			value = val;
+		}
+
+		internal Sequence.from_content(uint8[] bytes) throws DecodeError {
+			type = TYPE;
+			content = bytes;
+			value = decode_array(bytes);
+		}
+
+		private static uint8[] encode_array(Datum[] val) {
+			var buffer = new ByteArray();
+			foreach (var datum in val)
+				buffer.append(datum.encode());
+			return buffer.data;
+		}
+
+		private static Datum[] decode_array(uint8[] bytes)
+								   throws DecodeError {
+			var elems = new GenericArray<Datum>();
+			uint offset = 0;	
+			uint size;
+			while (offset < bytes.length) {
+				elems.add(decode(bytes[offset:], out size));
+				offset += size;
+			}
+			return elems.data;
+		}
+	}
 }