fix(ptx): use another obfs4 bridge

See discussion at #413 (comment).

internal/ptx/obfs4.go

@@ -19,15 +19,14 @@ import (
 // not wise to use this bridge in general. But, feel free to
 // use this bridge for integration testing of this code.
 func DefaultTestingOBFS4Bridge() *OBFS4Dialer {
-	// TODO(bassosimone): this is a public working bridge we have found
-	// with @hellais. We should ask @cohosh whether there's some obfs4 bridge
-	// dedicated to integration testing that we should use instead.
+	// See https://gitlab.torproject.org/tpo/applications/tor-browser-build/-/blob/master/projects/tor-browser/Bundle-Data/PTConfigs/bridge_prefs.js
+	// for publicly available bridges used by Tor Browser.
 	return &OBFS4Dialer{
-		Address:     "192.95.36.142:443",
-		Cert:        "qUVQ0srL1JI/vO6V6m/24anYXiJD3QP2HgzUKQtQ7GRqqUvs7P+tG43RtAqdhLOALP7DJQ",
+		Address:     "209.148.46.65:443",
+		Cert:        "ssH+9rP8dG2NLDN2XuFw63hIO/9MNNinLmxQDpVa+7kTOa9/m+tGWT1SmSYpQ9uTBGa6Hw",
 		DataDir:     "testdata",
-		Fingerprint: "CDF2E852BF539B82BD10E27E9115A31734E378C2",
-		IATMode:     "1",
+		Fingerprint: "74FAD13168806246602538555B5521A0383A1875",
+		IATMode:     "0",
 	}
 }
 

internal/ptx/obfs4_test.go

@@ -26,7 +26,7 @@ func TestOBFS4DialerWorks(t *testing.T) {
 		t.Fatal("unexpected value returned by Name")
 	}
 	bridgearg := o4d.AsBridgeArgument()
-	expectedbridge := "obfs4 192.95.36.142:443 CDF2E852BF539B82BD10E27E9115A31734E378C2 cert=qUVQ0srL1JI/vO6V6m/24anYXiJD3QP2HgzUKQtQ7GRqqUvs7P+tG43RtAqdhLOALP7DJQ iat-mode=1"
+	expectedbridge := "obfs4 209.148.46.65:443 74FAD13168806246602538555B5521A0383A1875 cert=ssH+9rP8dG2NLDN2XuFw63hIO/9MNNinLmxQDpVa+7kTOa9/m+tGWT1SmSYpQ9uTBGa6Hw iat-mode=0"
 	if bridgearg != expectedbridge {
 		t.Fatal("unexpected AsBridgeArgument value", bridgearg)
 	}