Remove superfluous freestanding connection ID parser

fuzz/fuzz_targets/packet.rs

@@ -5,15 +5,15 @@ extern crate proto;
 use libfuzzer_sys::fuzz_target;
 use proto::{
     fuzzing::{PacketParams, PartialDecode},
-    FixedLengthConnectionIdParser, DEFAULT_SUPPORTED_VERSIONS,
+    RandomConnectionIdGenerator, DEFAULT_SUPPORTED_VERSIONS,
 };
 
 fuzz_target!(|data: PacketParams| {
     let len = data.buf.len();
     let supported_versions = DEFAULT_SUPPORTED_VERSIONS.to_vec();
     if let Ok(decoded) = PartialDecode::new(
         data.buf,
-        &FixedLengthConnectionIdParser::new(data.local_cid_len),
+        &RandomConnectionIdGenerator::new(data.local_cid_len),
         &supported_versions,
         data.grease_quic_bit,
     ) {

quinn-proto/src/lib.rs

@@ -66,8 +66,8 @@ pub use crate::endpoint::{
 
 mod packet;
 pub use packet::{
-    ConnectionIdParser, FixedLengthConnectionIdParser, LongType, PacketDecodeError, PartialDecode,
-    ProtectedHeader, ProtectedInitialHeader,
+    ConnectionIdParser, LongType, PacketDecodeError, PartialDecode, ProtectedHeader,
+    ProtectedInitialHeader,
 };
 
 mod shared;

quinn-proto/src/packet.rs

@@ -767,26 +767,6 @@ impl PacketNumber {
     }
 }
 
-/// A [`ConnectionIdParser`] implementation that assumes the connection ID is of fixed length
-pub struct FixedLengthConnectionIdParser {
-    expected_len: usize,
-}
-
-impl FixedLengthConnectionIdParser {
-    /// Create a new instance of `FixedLengthConnectionIdParser`
-    pub fn new(expected_len: usize) -> Self {
-        Self { expected_len }
-    }
-}
-
-impl ConnectionIdParser for FixedLengthConnectionIdParser {
-    fn parse(&self, buffer: &mut dyn Buf) -> Result<ConnectionId, PacketDecodeError> {
-        (buffer.remaining() >= self.expected_len)
-            .then(|| ConnectionId::from_buf(buffer, self.expected_len))
-            .ok_or(PacketDecodeError::InvalidHeader("packet too small"))
-    }
-}
-
 /// Parse connection id in short header packet
 pub trait ConnectionIdParser {
     /// Parse a connection id from given buffer