rfb: be more strict parsing the version

rust/src/rfb/parser.rs

@@ -18,6 +18,7 @@
 // Author: Frank Honza <frank.honza@dcso.de>
 
 use nom7::bytes::streaming::take;
+use nom7::bytes::streaming::tag;
 use nom7::combinator::map_res;
 use nom7::number::streaming::*;
 use nom7::*;
@@ -115,12 +116,11 @@ pub struct ServerInit {
 }
 
 pub fn parse_protocol_version(i: &[u8]) -> IResult<&[u8], ProtocolVersion> {
-    let (i, _rfb_string) = map_res(take(3_usize), str::from_utf8)(i)?;
-    let (i, _) = be_u8(i)?;
+    let (i, _) = tag("RFB ")(i)?;
     let (i, major) = map_res(take(3_usize), str::from_utf8)(i)?;
-    let (i, _) = be_u8(i)?;
+    let (i, _) = tag(".")(i)?;
     let (i, minor) = map_res(take(3_usize), str::from_utf8)(i)?;
-    let (i, _) = be_u8(i)?;
+    let (i, _) = tag("\n")(i)?;
     Ok((
         i,
         ProtocolVersion {