Allow app to accept/reject/retry before handshake begins

.gitignore

@@ -6,3 +6,6 @@ Cargo.lock
 .idea
 .DS_Store
 .vscode
+
+cargo-test-*
+tarpaulin-report.html

perf/src/bin/perf_server.rs

@@ -123,7 +123,7 @@ async fn run(opt: Opt) -> Result<()> {
     Ok(())
 }
 
-async fn handle(handshake: quinn::Connecting, opt: Arc<Opt>) -> Result<()> {
+async fn handle(handshake: quinn::Incoming, opt: Arc<Opt>) -> Result<()> {
     let connection = handshake.await.context("handshake failed")?;
     debug!("{} connected", connection.remote_address());
     tokio::try_join!(

quinn-proto/src/config.rs

@@ -757,16 +757,9 @@ pub struct ServerConfig {
     /// Used to generate one-time AEAD keys to protect handshake tokens
     pub(crate) token_key: Arc<dyn HandshakeTokenKey>,
 
-    /// Whether to require clients to prove ownership of an address before committing resources.
-    ///
-    /// Introduces an additional round-trip to the handshake to make denial of service attacks more difficult.
-    pub(crate) use_retry: bool,
     /// Microseconds after a stateless retry token was issued for which it's considered valid.
     pub(crate) retry_token_lifetime: Duration,
 
-    /// Maximum number of concurrent connections
-    pub(crate) concurrent_connections: u32,
-
     /// Whether to allow clients to migrate to new addresses
     ///
     /// Improves behavior for clients that move between different internet connections or suffer NAT
@@ -785,11 +778,8 @@ impl ServerConfig {
             crypto,
 
             token_key,
-            use_retry: false,
             retry_token_lifetime: Duration::from_secs(15),
 
-            concurrent_connections: 100_000,
-
             migration: true,
         }
     }
@@ -806,29 +796,12 @@ impl ServerConfig {
         self
     }
 
-    /// Whether to require clients to prove ownership of an address before committing resources.
-    ///
-    /// Introduces an additional round-trip to the handshake to make denial of service attacks more difficult.
-    pub fn use_retry(&mut self, value: bool) -> &mut Self {
-        self.use_retry = value;
-        self
-    }
-
     /// Duration after a stateless retry token was issued for which it's considered valid.
     pub fn retry_token_lifetime(&mut self, value: Duration) -> &mut Self {
         self.retry_token_lifetime = value;
         self
     }
 
-    /// Maximum number of simultaneous connections to accept.
-    ///
-    /// New incoming connections are only accepted if the total number of incoming or outgoing
-    /// connections is less than this. Outgoing connections are unaffected.
-    pub fn concurrent_connections(&mut self, value: u32) -> &mut Self {
-        self.concurrent_connections = value;
-        self
-    }
-
     /// Whether to allow clients to migrate to new addresses
     ///
     /// Improves behavior for clients that move between different internet connections or suffer NAT
@@ -874,9 +847,7 @@ impl fmt::Debug for ServerConfig {
             .field("transport", &self.transport)
             .field("crypto", &"ServerConfig { elided }")
             .field("token_key", &"[ elided ]")
-            .field("use_retry", &self.use_retry)
             .field("retry_token_lifetime", &self.retry_token_lifetime)
-            .field("concurrent_connections", &self.concurrent_connections)
             .field("migration", &self.migration)
             .finish()
     }

quinn-proto/src/connection/mod.rs

@@ -252,6 +252,7 @@ impl Connection {
         version: u32,
         allow_mtud: bool,
         rng_seed: [u8; 32],
+        path_validated: bool,
     ) -> Self {
         let side = if server_config.is_some() {
             Side::Server
@@ -268,7 +269,6 @@ impl Connection {
             client_hello: None,
         });
         let mut rng = StdRng::from_seed(rng_seed);
-        let path_validated = server_config.as_ref().map_or(true, |c| c.use_retry);
         let mut this = Self {
             endpoint_config,
             server_config,
@@ -2195,7 +2195,10 @@ impl Connection {
                 }
                 ConnectionError::VersionMismatch => State::Draining,
                 ConnectionError::LocallyClosed => {
-                    unreachable!("LocallyClosed isn't generated by packet processing")
+                    unreachable!("LocallyClosed isn't generated by packet processing");
+                }
+                ConnectionError::CidsExhausted => {
+                    unreachable!("CidsExhausted isn't generated by packet processing");
                 }
             };
         }
@@ -3508,6 +3511,11 @@ pub enum ConnectionError {
     /// The local application closed the connection
     #[error("closed")]
     LocallyClosed,
+    /// The connection could not be created because not enough of the CID space is available
+    ///
+    /// Try using longer connection IDs.
+    #[error("CIDs exhausted")]
+    CidsExhausted,
 }
 
 impl From<Close> for ConnectionError {
@@ -3527,7 +3535,9 @@ impl From<ConnectionError> for io::Error {
             TimedOut => io::ErrorKind::TimedOut,
             Reset => io::ErrorKind::ConnectionReset,
             ApplicationClosed(_) | ConnectionClosed(_) => io::ErrorKind::ConnectionAborted,
-            TransportError(_) | VersionMismatch | LocallyClosed => io::ErrorKind::Other,
+            TransportError(_) | VersionMismatch | LocallyClosed | CidsExhausted => {
+                io::ErrorKind::Other
+            }
         };
         Self::new(kind, x)
     }