fix: More migration tests and related fixes

neqo-transport/src/cid.rs

@@ -14,7 +14,7 @@
     rc::Rc,
 };
 
-use neqo_common::{hex, hex_with_len, qinfo, Decoder, Encoder};
+use neqo_common::{hex, hex_with_len, qdebug, qinfo, Decoder, Encoder};
 use neqo_crypto::{random, randomize};
 use smallvec::{smallvec, SmallVec};
 
@@ -314,6 +314,10 @@
         stats.new_connection_id += 1;
         true
     }
+
+    pub fn is_empty(&self) -> bool {
+        self.seqno == CONNECTION_ID_SEQNO_EMPTY || self.cid.is_empty()
+    }
 }
 
 impl ConnectionIdEntry<()> {
@@ -405,7 +409,7 @@
     pub fn retire_prior_to(&mut self, retire_prior: u64) -> Vec<u64> {
         let mut retired = Vec::new();
         self.cids.retain(|e| {
-            if e.seqno < retire_prior {
+            if !e.is_empty() && e.seqno < retire_prior {
                 retired.push(e.seqno);
                 false
             } else {
@@ -510,8 +514,18 @@
     pub fn retire(&mut self, seqno: u64) {
         // TODO(mt) - consider keeping connection IDs around for a short while.
 
-        self.connection_ids.retire(seqno);
-        self.lost_new_connection_id.retain(|cid| cid.seqno != seqno);
+        let empty_cid = seqno == CONNECTION_ID_SEQNO_EMPTY
+            || self
+                .connection_ids
+                .cids
+                .iter()
+                .any(|c| c.seqno == seqno && c.cid.is_empty());
+        if empty_cid {
+            qdebug!("Connection ID {seqno} is zero-length, not retiring");
+        } else {
+            self.connection_ids.retire(seqno);
+            self.lost_new_connection_id.retain(|cid| cid.seqno != seqno);
+        }
     }
 
     /// During the handshake, a server needs to regard the client's choice of destination

neqo-transport/src/connection/mod.rs

@@ -1536,7 +1536,7 @@ impl Connection {
     /// This takes two times: when the datagram was received, and the current time.
     fn input(&mut self, d: Datagram<impl AsRef<[u8]>>, received: Instant, now: Instant) {
         // First determine the path.
-        let path = self.paths.find_path_with_rebinding(
+        let path = self.paths.find_path(
             d.destination(),
             d.source(),
             self.conn_params.get_cc_algorithm(),

neqo-transport/src/connection/tests/handshake.rs

@@ -25,7 +25,7 @@ use test_fixture::{
 use super::{
     super::{Connection, Output, State},
     assert_error, connect, connect_force_idle, connect_with_rtt, default_client, default_server,
-    get_tokens, handshake, maybe_authenticate, resumed_server, send_something,
+    get_tokens, handshake, maybe_authenticate, resumed_server, send_something, zero_len_cid_client,
     CountingConnectionIdGenerator, AT_LEAST_PTO, DEFAULT_RTT, DEFAULT_STREAM_DATA,
 };
 use crate::{
@@ -38,8 +38,7 @@ use crate::{
     stats::FrameStats,
     tparams::{self, TransportParameter, MIN_ACK_DELAY},
     tracking::DEFAULT_ACK_DELAY,
-    CloseReason, ConnectionParameters, EmptyConnectionIdGenerator, Error, Pmtud, StreamType,
-    Version,
+    CloseReason, ConnectionParameters, Error, Pmtud, StreamType, Version,
 };
 
 const ECH_CONFIG_ID: u8 = 7;
@@ -263,16 +262,7 @@ fn crypto_frame_split() {
 #[test]
 fn chacha20poly1305() {
     let mut server = default_server();
-    let mut client = Connection::new_client(
-        test_fixture::DEFAULT_SERVER_NAME,
-        test_fixture::DEFAULT_ALPN,
-        Rc::new(RefCell::new(EmptyConnectionIdGenerator::default())),
-        DEFAULT_ADDR,
-        DEFAULT_ADDR,
-        ConnectionParameters::default(),
-        now(),
-    )
-    .expect("create a default client");
+    let mut client = zero_len_cid_client(DEFAULT_ADDR, DEFAULT_ADDR);
     client.set_ciphers(&[TLS_CHACHA20_POLY1305_SHA256]).unwrap();
     connect_force_idle(&mut client, &mut server);
 }