1 files changed, 38 insertions, 0 deletions
diff --git a/src/net/http/httputil/reverseproxy_test.go b/src/net/http/httputil/reverseproxy_test.go
index 62c93fb261..3cca6eda99 100644
--- a/src/net/http/httputil/reverseproxy_test.go
+++ b/src/net/http/httputil/reverseproxy_test.go
@@ -2149,6 +2149,44 @@ func TestReverseProxyHijackCopyError(t *testing.T) {
 	proxyHandler.ServeHTTP(rw, req)
 }
 
+// https://go.dev/issue/75933.
+func TestReverseProxyInvalidUpstream100ContinueDoNotHang(t *testing.T) {
+	proxy := ReverseProxy{
+		Transport: &http.Transport{DisableKeepAlives: true, ExpectContinueTimeout: time.Second * 60},
+		Director: func(request *http.Request) {
+			request.URL.Scheme = "http"
+			request.URL.Host = "doesnotexist:12345" // non-existent upstream
+		},
+	}
+	handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		proxy.ServeHTTP(w, r)
+	})
+	upstreamServer := httptest.NewServer(handler)
+	defer upstreamServer.Close()
+
+	conn, err := net.Dial("tcp", upstreamServer.Listener.Addr().String())
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer conn.Close()
+
+	requestBody := `{"test": "data"}`
+	initialRequest := fmt.Sprintf("POST %s/test-expect HTTP/1.1\r\n"+
+		"Host: %s\r\n"+
+		"Content-Type: application/json\r\n"+
+		"Content-Length: %d\r\n"+
+		"Expect: 100-continue\r\n"+
+		"\r\n", upstreamServer.URL, upstreamServer.Listener.Addr().String(), len(requestBody))
+
+	if _, err := conn.Write([]byte(initialRequest)); err != nil {
+		log.Fatal(err)
+	}
+	buff := make([]byte, 1024)
+	if _, err := conn.Read(buff); err != nil {
+		log.Fatal(err)
+	}
+}
+
 type testResponseWriter struct {
 	h           http.Header
 	writeHeader func(int)