Fix nil pointer dereference segfault when passing "null" config json to cloudflared tunnel ingress validate (#1070)

ingress/ingress.go

@@ -85,7 +85,7 @@ type Ingress struct {
 
 // ParseIngress parses ingress rules, but does not send HTTP requests to the origins.
 func ParseIngress(conf *config.Configuration) (Ingress, error) {
-	if len(conf.Ingress) == 0 {
+	if conf == nil || len(conf.Ingress) == 0 {
 		return Ingress{}, ErrNoIngressRules
 	}
 	return validateIngress(conf.Ingress, originRequestFromConfig(conf.OriginRequest))

ingress/ingress_test.go

@@ -43,6 +43,11 @@ ingress:
 	require.Equal(t, "https", s.scheme)
 }
 
+func TestParseIngressNilConfig(t *testing.T) {
+	_, err := ParseIngress(nil)
+	require.Error(t, err)
+}
+
 func TestParseIngress(t *testing.T) {
 	localhost8000 := MustParseURL(t, "https://localhost:8000")
 	localhost8001 := MustParseURL(t, "https://localhost:8001")