QPACK: known the value of an invalid prefix, fix Literal prefix check

quinn-h3/src/qpack/bloc.rs

@@ -43,7 +43,7 @@ impl Indexed {
         match prefix_int::decode(6, buf)? {
             (0b11, i) => Ok(Indexed::Static(i)),
             (0b10, i) => Ok(Indexed::Dynamic(i)),
-            _ => Err(ParseError::InvalidPrefix),
+            (f, i) => Err(ParseError::InvalidPrefix(f)),
         }
     }
 
@@ -62,7 +62,7 @@ impl IndexedWithPostBase {
     pub fn decode<R: Buf>(buf: &mut R) -> Result<Self, ParseError> {
         match prefix_int::decode(4, buf)? {
             (0b0001, i) => Ok(IndexedWithPostBase(i)),
-            _ => Err(ParseError::InvalidPrefix),
+            (f, _) => Err(ParseError::InvalidPrefix(f)),
         }
     }
 
@@ -102,7 +102,7 @@ impl LiteralWithNameRef {
                 i,
                 prefix_string::decode(8, buf)?,
             )),
-            _ => Err(ParseError::InvalidPrefix),
+            (f, _) => Err(ParseError::InvalidPrefix(f)),
         }
     }
 
@@ -141,7 +141,7 @@ impl LiteralWithPostBaseNameRef {
                 i,
                 prefix_string::decode(8, buf)?,
             )),
-            _ => Err(ParseError::InvalidPrefix),
+            (f, _) => Err(ParseError::InvalidPrefix(f)),
         }
     }
 
@@ -167,8 +167,10 @@ impl Literal {
     }
 
     pub fn decode<R: Buf>(buf: &mut R) -> Result<Self, ParseError> {
-        if buf.remaining() > 0 && buf.bytes()[0] & 0b1110_0000 != 0b0010_0000 {
-            return Err(ParseError::InvalidPrefix);
+        if buf.remaining() < 1 {
+            return Err(ParseError::InvalidInteger(prefix_int::Error::UnexpectedEnd));
+        } else if buf.bytes()[0] & 0b1110_0000 != 0b0010_0000 {
+            return Err(ParseError::InvalidPrefix(buf.bytes()[0]));
         }
         Ok(Literal::new(
             prefix_string::decode(4, buf)?,

quinn-h3/src/qpack/decoder.rs

@@ -251,7 +251,7 @@ impl From<ParseError> for Error {
         match e {
             ParseError::InvalidInteger(x) => Error::InvalidInteger(x),
             ParseError::InvalidString(x) => Error::InvalidString(x),
-            ParseError::InvalidPrefix => Error::UnknownPrefix,
+            ParseError::InvalidPrefix(_) => Error::UnknownPrefix,
         }
     }
 }

quinn-h3/src/qpack/mod.rs

@@ -33,7 +33,7 @@ pub mod prefix_string;
 pub enum ParseError {
     InvalidInteger(prefix_int::Error),
     InvalidString(prefix_string::Error),
-    InvalidPrefix,
+    InvalidPrefix(u8),
 }
 
 impl From<prefix_int::Error> for ParseError {

quinn-h3/src/qpack/stream.rs

@@ -55,7 +55,7 @@ impl InsertWithNameRef {
     pub fn decode<R: Buf>(buf: &mut R) -> Result<Option<Self>, ParseError> {
         let (flags, index) = match prefix_int::decode(6, buf) {
             Ok((f, x)) if f & 0b10 == 0b10 => (f, x),
-            Ok((_, _)) => return Err(ParseError::InvalidPrefix),
+            Ok((f, _)) => return Err(ParseError::InvalidPrefix(f)),
             Err(IntError::UnexpectedEnd) => return Ok(None),
             Err(e) => return Err(e.into()),
         };
@@ -130,7 +130,7 @@ impl Duplicate {
     pub fn decode<R: Buf>(buf: &mut R) -> Result<Option<Self>, ParseError> {
         let index = match prefix_int::decode(5, buf) {
             Ok((0, x)) => x,
-            Ok((_, _)) => return Err(ParseError::InvalidPrefix),
+            Ok((f, _)) => return Err(ParseError::InvalidPrefix(f)),
             Err(IntError::UnexpectedEnd) => return Ok(None),
             Err(e) => return Err(e.into()),
         };
@@ -151,7 +151,7 @@ impl DynamicTableSizeUpdate {
     pub fn decode<R: Buf>(buf: &mut R) -> Result<Option<Self>, ParseError> {
         let size = match prefix_int::decode(5, buf) {
             Ok((0b001, x)) => x,
-            Ok((_, _)) => return Err(ParseError::InvalidPrefix),
+            Ok((f, _)) => return Err(ParseError::InvalidPrefix(f)),
             Err(IntError::UnexpectedEnd) => return Ok(None),
             Err(e) => return Err(e.into()),
         };
@@ -172,7 +172,7 @@ impl TableSizeSync {
     pub fn decode<R: Buf>(buf: &mut R) -> Result<Option<Self>, ParseError> {
         let insert_count = match prefix_int::decode(6, buf) {
             Ok((0b00, x)) => x,
-            Ok((_, _)) => return Err(ParseError::InvalidPrefix),
+            Ok((f, _)) => return Err(ParseError::InvalidPrefix(f)),
             Err(IntError::UnexpectedEnd) => return Ok(None),
             Err(e) => return Err(e.into()),
         };