Option -gui-address should accept scheme prefixes (fixes #2371)

lib/config/config.go

@@ -12,6 +12,7 @@ import (
 	"fmt"
 	"io"
 	"math/rand"
+	"net/url"
 	"os"
 	"path/filepath"
 	"reflect"
@@ -288,12 +289,72 @@ func (orig OptionsConfiguration) Copy() OptionsConfiguration {
 }
 
 type GUIConfiguration struct {
-	Enabled  bool   `xml:"enabled,attr" json:"enabled" default:"true"`
-	Address  string `xml:"address" json:"address" default:"127.0.0.1:8384"`
-	User     string `xml:"user,omitempty" json:"user"`
-	Password string `xml:"password,omitempty" json:"password"`
-	UseTLS   bool   `xml:"tls,attr" json:"useTLS"`
-	APIKey   string `xml:"apikey,omitempty" json:"apiKey"`
+	Enabled    bool   `xml:"enabled,attr" json:"enabled" default:"true"`
+	RawAddress string `xml:"address" json:"address" default:"127.0.0.1:8384"`
+	User       string `xml:"user,omitempty" json:"user"`
+	Password   string `xml:"password,omitempty" json:"password"`
+	RawUseTLS  bool   `xml:"tls,attr" json:"useTLS"`
+	RawAPIKey  string `xml:"apikey,omitempty" json:"apiKey"`
+}
+
+func (c GUIConfiguration) Address() string {
+	if override := os.Getenv("STGUIADDRESS"); override != "" {
+		// This value may be of the form "scheme://address:port" or just
+		// "address:port". We need to chop off the scheme. We try to parse it as
+		// an URL if it contains a slash. If that fails, return it as is and let
+		// some other error handling handle it.
+
+		if strings.Contains(override, "/") {
+			url, err := url.Parse(override)
+			if err != nil {
+				return override
+			}
+			return url.Host
+		}
+
+		return override
+	}
+
+	return c.RawAddress
+}
+
+func (c GUIConfiguration) UseTLS() bool {
+	if override := os.Getenv("STGUIADDRESS"); override != "" {
+		return strings.HasPrefix(override, "https:")
+	}
+	return c.RawUseTLS
+}
+
+func (c GUIConfiguration) URL() string {
+	u := url.URL{
+		Scheme: "http",
+		Host:   c.Address(),
+		Path:   "/",
+	}
+
+	if c.UseTLS() {
+		u.Scheme = "https"
+	}
+
+	if strings.HasPrefix(u.Host, ":") {
+		// Empty host, i.e. ":port", use IPv4 localhost
+		u.Host = "127.0.0.1" + u.Host
+	} else if strings.HasPrefix(u.Host, "0.0.0.0:") {
+		// IPv4 all zeroes host, convert to IPv4 localhost
+		u.Host = "127.0.0.1" + u.Host[7:]
+	} else if strings.HasPrefix(u.Host, "[::]:") {
+		// IPv6 all zeroes host, convert to IPv6 localhost
+		u.Host = "[::1]" + u.Host[4:]
+	}
+
+	return u.String()
+}
+
+func (c GUIConfiguration) APIKey() string {
+	if override := os.Getenv("STGUIAPIKEY"); override != "" {
+		return override
+	}
+	return c.RawAPIKey
 }
 
 func New(myID protocol.DeviceID) Configuration {
@@ -463,8 +524,8 @@ func (cfg *Configuration) prepare(myID protocol.DeviceID) {
 		cfg.Options.ReconnectIntervalS = 5
 	}
 
-	if cfg.GUI.APIKey == "" {
-		cfg.GUI.APIKey = randomString(32)
+	if cfg.GUI.RawAPIKey == "" {
+		cfg.GUI.RawAPIKey = randomString(32)
 	}
 }