Remove BIT STRING null byte truncation in BER

fixes #111
fixes #89

src/ber/de.rs

@@ -266,9 +266,6 @@ impl<'input> crate::Decoder for Decoder<'input> {
                         if let Some(last) = buffer.last_mut() {
                             *last &= !((1 << bits) - 1);
                         }
-                        if buffer.last().map_or(false, |i| *i == 0) {
-                            buffer.pop();
-                        }
 
                         let string = types::BitString::from_vec(buffer);
 
@@ -283,17 +280,7 @@ impl<'input> crate::Decoder for Decoder<'input> {
             })?;
 
         self.input = input;
-        if let Some((i, _)) = bs
-            .as_raw_slice()
-            .iter()
-            .enumerate()
-            .rev()
-            .find(|(_, v)| **v != 0)
-        {
-            Ok(types::BitString::from_vec(bs.as_raw_slice()[..=i].to_vec()))
-        } else {
-            Ok(bs)
-        }
+        Ok(bs)
     }
 
     fn decode_visible_string(

src/ber/enc.rs

@@ -271,9 +271,6 @@ impl crate::Encoder for Encoder {
             let bit_length = value.len();
             let bytes = value.clone().into_vec();
             let mut deque = VecDeque::from(bytes);
-            while deque.back().map_or(false, |i| *i == 0) {
-                deque.pop_back();
-            }
 
             deque.push_front((deque.len() * 8).saturating_sub(bit_length) as u8);
             self.encode_string(tag, Tag::BIT_STRING, &Vec::from(deque))

standards/kerberos/tests/issue111.rs

@@ -0,0 +1,24 @@
+use rasn::{ber, Decoder, Tag, types::Class, Encoder};
+use rasn_kerberos::KerberosFlags;
+
+#[test]
+fn kerberos_flags_dec() {
+    let input = b"\x03\x05\x00\x40\x81\x00\x00";
+    let mut decoder = ber::de::Decoder::new(input, ber::de::DecoderOptions::ber());
+    let output = decoder
+        .decode_bit_string(Tag::new(Class::Universal, 3), <_>::default())
+        .unwrap();
+    let expected = KerberosFlags::from_vec([0x40, 0x81, 0x00, 0x00].to_vec());
+    assert_eq!(output, expected)
+}
+
+#[test]
+fn kerberos_flags_enc() {
+    let bitstring = KerberosFlags::from_vec([0x40, 0x81, 0x00, 0x00].to_vec());
+    let mut encoder = ber::enc::Encoder::new(ber::enc::EncoderOptions::ber());
+    encoder
+        .encode_bit_string(Tag::new(Class::Universal, 3), <_>::default(), &bitstring)
+        .unwrap();
+    assert_eq!(encoder.output(), vec![0x03, 0x05, 0x00, 0x40, 0x81, 0x00, 0x00])
+}
+