quic: fix bug in setSNIContexts that lost ALPN config

Author: pimterry

lib/internal/quic/quic.js

@@ -4515,6 +4515,8 @@ class QuicEndpoint {
     truncatedReads: undefined,
     onsession: undefined,
     sessionCallbacks: undefined,
+    // The encoded ALPN this endpoint listens with.
+    alpn: undefined,
   };
 
   static {
@@ -4823,6 +4825,7 @@ class QuicEndpoint {
     } = options;
 
     inner.truncatedReads = truncatedReads;
+    inner.alpn = rest.tls.alpn;
 
     // Store session and stream callbacks to apply to each new incoming session.
     inner.sessionCallbacks = {
@@ -5030,7 +5033,8 @@ class QuicEndpoint {
       if (identity.certs === undefined) {
         throw new ERR_MISSING_ARGS(`entries['${hostname}'].certs`);
       }
-      processed[hostname] = identity;
+      // These identities offer the same protocols as the ones given to listen():
+      processed[hostname] = { __proto__: null, ...identity, alpn: this.#inner.alpn };
     }
 
     this.#handle.setSNIContexts(processed, replace);

test/parallel/test-quic-sni-setcontexts.mjs

@@ -48,7 +48,10 @@ const serverEndpoint = await listen(mustCall(async (serverSession) => {
 }
 
 endpoint.setSNIContexts(
-  { '*': { keys: [key2], certs: [cert2] } },
+  {
+    '*': { keys: [key2], certs: [cert2] },
+    'localhost': { keys: [key2], certs: [cert2] },
+  },
   { replace: true },
 );