From: Damien Neil <dneil@google.com>
Date: Sat, 23 Nov 2024 01:10:01 +0000 (-0800)
Subject: net/http: avoid redundant installation of HTTP/2 support in transport
X-Git-Tag: go1.24rc1~80
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=fb5fa2a839ef0ea9952e47f6d0e05b51a5a51a8d;p=gostls13.git

net/http: avoid redundant installation of HTTP/2 support in transport

Previously, we'd skip installing the bundled HTTP/2 support
if Transport.TLSNextProto is non-nil.

With the addition of the Transport.Protocols field, we'll
install HTTP/2 if Protocols contains HTTP2, even if TLSNextProto
is non-nil. However, we shouldn't do so if it already contains an
"h2" entry.

Change-Id: Ib086473bb52f1b76d83b1df961d41360c605832c
Reviewed-on: https://go-review.googlesource.com/c/go/+/631395
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Jonathan Amsterdam <jba@google.com>
Auto-Submit: Damien Neil <dneil@google.com>
---

diff --git a/src/net/http/transport.go b/src/net/http/transport.go
index e2ce4dde3d..41e674188f 100644
--- a/src/net/http/transport.go
+++ b/src/net/http/transport.go
@@ -412,6 +412,10 @@ func (t *Transport) onceSetNextProtoDefaults() {
 		}
 	}
 
+	if _, ok := t.TLSNextProto["h2"]; ok {
+		// There's an existing HTTP/2 implementation installed.
+		return
+	}
 	protocols := t.protocols()
 	if !protocols.HTTP2() && !protocols.UnencryptedHTTP2() {
 		return