From e951646fb652e23bce7ba79ee39c4f91c226d213 Mon Sep 17 00:00:00 2001
From: Marten Seemann <martenseemann@gmail.com>
Date: Sun, 6 Oct 2019 10:31:30 +0200
Subject: [PATCH] tell if a peer supports DATAGRAM frames in the
 ConnectionState

---
 interface.go | 3 ++-
 session.go   | 7 ++++++-
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/interface.go b/interface.go
index 19d38c74..e27a81d1 100644
--- a/interface.go
+++ b/interface.go
@@ -264,7 +264,8 @@ type Config struct {
 
 // ConnectionState records basic details about a QUIC connection
 type ConnectionState struct {
-	TLS handshake.ConnectionState
+	TLS               handshake.ConnectionState
+	SupportsDatagrams bool
 }
 
 // A Listener for incoming QUIC connections
diff --git a/session.go b/session.go
index 384530d9..7fc28c0c 100644
--- a/session.go
+++ b/session.go
@@ -632,9 +632,14 @@ func (s *session) Context() context.Context {
 	return s.ctx
 }
 
+func (s *session) supportsDatagrams() bool {
+	return s.peerParams.MaxDatagramFrameSize != protocol.InvalidByteCount
+}
+
 func (s *session) ConnectionState() ConnectionState {
 	return ConnectionState{
-		TLS: s.cryptoStreamHandler.ConnectionState(),
+		TLS:               s.cryptoStreamHandler.ConnectionState(),
+		SupportsDatagrams: s.supportsDatagrams(),
 	}
 }