config: fix url type regression (#253)

Signed-off-by: Bobby DeSimone <bobbydesimone@gmail.com>

internal/urlutil/url.go

@@ -25,6 +25,9 @@ func StripPort(hostport string) string {
 // ParseAndValidateURL wraps standard library's default url.Parse because
 // it's much more lenient about what type of urls it accepts than pomerium.
 func ParseAndValidateURL(rawurl string) (*url.URL, error) {
+	if rawurl == "" {
+		return nil, fmt.Errorf("url cannot be empty")
+	}
 	u, err := url.Parse(rawurl)
 	if err != nil {
 		return nil, err
@@ -37,3 +40,10 @@ func ParseAndValidateURL(rawurl string) (*url.URL, error) {
 	}
 	return u, nil
 }
+
+func DeepCopy(u *url.URL) (*url.URL, error) {
+	if u == nil {
+		return nil, nil
+	}
+	return ParseAndValidateURL(u.String())
+}

internal/urlutil/url_test.go

@@ -2,6 +2,7 @@ package urlutil
 
 import (
 	"net/url"
+	"reflect"
 	"testing"
 
 	"github.com/google/go-cmp/cmp"
@@ -45,6 +46,7 @@ func TestParseAndValidateURL(t *testing.T) {
 		{"bad schema", "//some.example", nil, true},
 		{"bad hostname", "https://", nil, true},
 		{"bad parse", "https://^", nil, true},
+		{"empty string error", "", nil, true},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
@@ -59,3 +61,29 @@ func TestParseAndValidateURL(t *testing.T) {
 		})
 	}
 }
+
+func TestDeepCopy(t *testing.T) {
+
+	tests := []struct {
+		name    string
+		u       *url.URL
+		want    *url.URL
+		wantErr bool
+	}{
+		{"nil", nil, nil, false},
+		{"good", &url.URL{Scheme: "https", Host: "some.example"}, &url.URL{Scheme: "https", Host: "some.example"}, false},
+		{"bad no scheme", &url.URL{Host: "some.example"}, nil, true},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := DeepCopy(tt.u)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("DeepCopy() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("DeepCopy() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}