Validate offsets do not point beyond end of message

src/error.rs

@@ -31,9 +31,12 @@ pub enum Error {
  /// Request was less than 1024 bytes
  RequestTooShort,
 
- /// Offset within message was not 32-bit aligned 
+ /// Offset was not 32-bit aligned 
  InvalidOffsetAlignment(u32),
 
+ /// Offset is outside of valid message range
+ InvalidOffsetValue(u32),
+
  /// Invalid number of tags specified 
  InvalidNumTags(u32),
 

src/message.rs

@@ -67,12 +67,17 @@ impl RtMessage {
 
  let mut offsets = Vec::with_capacity((num_tags - 1) as usize);
  let mut tags = Vec::with_capacity(num_tags as usize);
+ let end_of_data = bytes.len() as u32;
 
  for _ in 0..num_tags - 1 {
  let offset = msg.read_u32::<LittleEndian>()?;
+
  if offset % 4 != 0 {
  return Err(Error::InvalidOffsetAlignment(offset));
+ } else if offset > end_of_data {
+ return Err(Error::InvalidOffsetValue(offset));
  }
+
  offsets.push(offset as usize);
  }
 
@@ -343,4 +348,32 @@ mod test {
  // Everything was read
  assert_eq!(encoded.position() as usize, msg.encoded_size());
  }
+
+ #[test]
+ #[should_panic(expected="InvalidOffsetValue(128)")]
+ fn from_bytes_offset_past_end_of_message() {
+ let mut msg = RtMessage::new(2);
+ msg.add_field(Tag::NONC, "1111".as_bytes()).unwrap();
+ msg.add_field(Tag::PAD, "aaaaaaaaa".as_bytes()).unwrap();
+
+ let mut bytes = msg.encode().unwrap();
+ // set the PAD value offset to beyond end of the message 
+ bytes[4] = 128;
+
+ RtMessage::from_bytes(&bytes).unwrap();
+ }
+
+ #[test]
+ #[should_panic(expected="InvalidNumTags(0)")]
+ fn from_bytes_zero_tags() {
+ let mut msg = RtMessage::new(1);
+ msg.add_field(Tag::NONC, "1111".as_bytes()).unwrap();
+
+ let mut bytes = msg.encode().unwrap();
+ // set num_tags to zero
+ bytes[0] = 0;
+
+ RtMessage::from_bytes(&bytes).unwrap();
+ }
+
 }