Add support for parsing endpoints without schema.

Fixes smallstep/ca-component#117

ca/client.go

@@ -153,16 +153,42 @@ func getTransportFromSHA256(endpoint, sum string) (http.RoundTripper, error) {
 	})
 }
 
-// parseEndpoint parses and validates the given endpoint
+// parseEndpoint parses and validates the given endpoint. It supports general
+// URLs like https://ca.smallstep.com[:port][/path], and incomplete URLs like
+// ca.smallstep.com[:port][/path].
 func parseEndpoint(endpoint string) (*url.URL, error) {
 	u, err := url.Parse(endpoint)
 	if err != nil {
 		return nil, errors.Wrapf(err, "error parsing endpoint '%s'", endpoint)
 	}
-	if u.Scheme == "" || u.Host == "" {
-		return nil, errors.Errorf("error parsing endpoint: url '%s' is not valid", endpoint)
+
+	// URLs are generally parsed as:
+	// [scheme:][//[userinfo@]host][/]path[?query][#fragment]
+	// But URLs that do not start with a slash after the scheme are interpreted as
+	// scheme:opaque[?query][#fragment]
+	if u.Opaque == "" {
+		if u.Scheme == "" {
+			u.Scheme = "https"
+		}
+		if u.Host == "" {
+			// endpoint looks like ca.smallstep.com or ca.smallstep.com/1.0/sign
+			if u.Path != "" {
+				parts := strings.SplitN(u.Path, "/", 2)
+				u.Host = parts[0]
+				if len(parts) == 2 {
+					u.Path = parts[1]
+				} else {
+					u.Path = ""
+				}
+				return parseEndpoint(u.String())
+			}
+			return nil, errors.Errorf("error parsing endpoint: url '%s' is not valid", endpoint)
+		}
+		return u, nil
 	}
-	return u, nil
+	// scheme:opaque[?query][#fragment]
+	// endpoint looks like ca.smallstep.com:443 or ca.smallstep.com:443/1.0/sign
+	return parseEndpoint("https://" + endpoint)
 }
 
 // ProvisionerOption is the type of options passed to the Provisioner method.

ca/client_test.go

@@ -8,6 +8,7 @@ import (
 	"fmt"
 	"net/http"
 	"net/http/httptest"
+	"net/url"
 	"reflect"
 	"testing"
 	"time"
@@ -510,3 +511,41 @@ func TestClient_ProvisionerKey(t *testing.T) {
 		})
 	}
 }
+
+func Test_parseEndpoint(t *testing.T) {
+	expected1 := &url.URL{Scheme: "https", Host: "ca.smallstep.com"}
+	expected2 := &url.URL{Scheme: "https", Host: "ca.smallstep.com", Path: "/1.0/sign"}
+	type args struct {
+		endpoint string
+	}
+	tests := []struct {
+		name    string
+		args    args
+		want    *url.URL
+		wantErr bool
+	}{
+		{"ok", args{"https://ca.smallstep.com"}, expected1, false},
+		{"ok no scheme", args{"//ca.smallstep.com"}, expected1, false},
+		{"ok only host", args{"ca.smallstep.com"}, expected1, false},
+		{"ok no bars", args{"https://ca.smallstep.com"}, expected1, false},
+		{"ok schema, host and path", args{"https://ca.smallstep.com/1.0/sign"}, expected2, false},
+		{"ok no bars with path", args{"https://ca.smallstep.com/1.0/sign"}, expected2, false},
+		{"ok host and path", args{"ca.smallstep.com/1.0/sign"}, expected2, false},
+		{"ok host and port", args{"ca.smallstep.com:443"}, &url.URL{Scheme: "https", Host: "ca.smallstep.com:443"}, false},
+		{"ok host, path and port", args{"ca.smallstep.com:443/1.0/sign"}, &url.URL{Scheme: "https", Host: "ca.smallstep.com:443", Path: "/1.0/sign"}, false},
+		{"fail bad url", args{"://ca.smallstep.com"}, nil, true},
+		{"fail no host", args{"https://"}, nil, true},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := parseEndpoint(tt.args.endpoint)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("parseEndpoint() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("parseEndpoint() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}