net/http: fix detection of Roundtrippers that always error

CL 220905 added code to identify alternate transports that always error by using http2erringRoundTripper. This does not work when the transport is from another package, e.g., http2.erringRoundTripper. Expose a new method that allow detection of such a RoundTripper. Switch to an interface that is both a RoundTripper and can return the underlying error. Fixes #40213 Change-Id: I170739857ab9e99dffb5fa55c99b24b23c2f9c54 Reviewed-on: https://go-review.googlesource.com/c/go/+/243258 Reviewed-by: Emmanuel Odeke <[email protected]> Run-TryBot: Emmanuel Odeke <[email protected]> TryBot-Result: Gobot Gobot <[email protected]>
golang · Aug 25, 2020 · 8381408 · 8381408
1 parent 3d77461
commit 8381408
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Showing 2 changed files with 6 additions and 6 deletions.
diff --git a/src/net/http/omithttp2.go b/src/net/http/omithttp2.go
@@ -32,10 +32,6 @@ type http2Transport struct {
 func (*http2Transport) RoundTrip(*Request) (*Response, error) { panic(noHTTP2) }
 func (*http2Transport) CloseIdleConnections()                 {}
 
-type http2erringRoundTripper struct{ err error }
-
-func (http2erringRoundTripper) RoundTrip(*Request) (*Response, error) { panic(noHTTP2) }
-
 type http2noDialH2RoundTripper struct{}
 
 func (http2noDialH2RoundTripper) RoundTrip(*Request) (*Response, error) { panic(noHTTP2) }

diff --git a/src/net/http/transport.go b/src/net/http/transport.go
@@ -1528,6 +1528,10 @@ func (pconn *persistConn) addTLS(name string, trace *httptrace.ClientTrace) erro
 	return nil
 }
 
+type erringRoundTripper interface {
+	RoundTripErr() error
+}
+
 func (t *Transport) dialConn(ctx context.Context, cm connectMethod) (pconn *persistConn, err error) {
 	pconn = &persistConn{
 		t:             t,
@@ -1694,9 +1698,9 @@ func (t *Transport) dialConn(ctx context.Context, cm connectMethod) (pconn *pers
 	if s := pconn.tlsState; s != nil && s.NegotiatedProtocolIsMutual && s.NegotiatedProtocol != "" {
 		if next, ok := t.TLSNextProto[s.NegotiatedProtocol]; ok {
 			alt := next(cm.targetAddr, pconn.conn.(*tls.Conn))
-			if e, ok := alt.(http2erringRoundTripper); ok {
+			if e, ok := alt.(erringRoundTripper); ok {
 				// pconn.conn was closed by next (http2configureTransport.upgradeFn).
-				return nil, e.err
+				return nil, e.RoundTripErr()
 			}
 			return &persistConn{t: t, cacheKey: pconn.cacheKey, alt: alt}, nil
 		}