feat: add controlURL options without env variables

Signed-off-by: Leon Lenzen <ich@leonlenzen.de>

README.md

@@ -93,6 +93,36 @@ However, having a single Caddy site connect to separate Tailscale nodes doesn't
 quite work correctly. If this is something you actually need, please open an
 issue.
 
+#### Alternative ControlURL
+
+To use with a custom coordination server (Headscale) you can include your ControlURL with the listen network.
+
+```
+:80 {
+  bind tailscale/example.de/a
+}
+
+:80 {
+  bind tailscale/example.de/b
+}
+```
+
+It also supports specifying the used protocol (defaults to tcp):
+
+```
+:80 {
+  bind tailscale/example.de/udp/a
+}
+
+:80 {
+  bind tailscale/udp/b
+}
+```
+
+Current shortcommings:
+- no support for path with ControlURL, 
+- it defaults to HTTPS for connection to custom control server
+
 ### HTTPS support
 
 At this time, the Tailscale plugin for Caddy doesn't support using Caddy's
@@ -186,3 +216,42 @@ For example:
 ```
 xcaddy tailscale-proxy --from "tailscale/myhost:80" --to localhost:8000
 ```
+
+## Caddy transport provider
+
+You can also specifiy tailscale as protocol to be used by caddy to proxy to your application.
+
+```json
+{
+ {
+  "apps": {
+    "http": {
+      "servers": {
+        "status": {
+          "listen": [
+            "tailscale/example.com/status:80"
+          ],
+          "routes": [
+            {
+              "handle": [
+                {
+                  "handler": "reverse_proxy",
+                  "upstreams": [
+                    {
+                      "dial": "node1:3000"
+                    }
+                  ],
+                  "transport": {
+                    "protocol": "tailscale",
+                    "controlURL": "https://example.com"
+                  }
+                }
+              ]
+            }
+          ]
+        }
+      }
+    }
+  }
+}
+```

module.go

@@ -33,37 +33,30 @@ func init() {
 }
 
 func getPlainListener(_ context.Context, _ string, addr string, _ net.ListenConfig) (any, error) {
-	network, host, port, err := caddy.SplitNetworkAddress(addr)
+	controlURL, network, host, port, err := parseAddr(addr)
 	if err != nil {
 		return nil, err
 	}
 
-	s, err := getServer("", host)
+	s, err := getServer("", host, controlURL)
 	if err != nil {
 		return nil, err
 	}
 
-	if network == "" {
-		network = "tcp"
-	}
-
 	return s.Listen(network, ":"+port)
 }
 
 func getTLSListener(_ context.Context, _ string, addr string, _ net.ListenConfig) (any, error) {
-	network, host, port, err := caddy.SplitNetworkAddress(addr)
+	controlURL, network, host, port, err := parseAddr(addr)
 	if err != nil {
 		return nil, err
 	}
 
-	s, err := getServer("", host)
+	s, err := getServer("", host, controlURL)
 	if err != nil {
 		return nil, err
 	}
 
-	if network == "" {
-		network = "tcp"
-	}
 	ln, err := s.Listen(network, ":"+port)
 	if err != nil {
 		return nil, err
@@ -86,7 +79,7 @@ func getTLSListener(_ context.Context, _ string, addr string, _ net.ListenConfig
 //
 // Auth keys can be provided in environment variables of the form TS_AUTHKEY_<HOST>.  If
 // no host is specified in the address, the environment variable TS_AUTHKEY will be used.
-func getServer(_, addr string) (*tsnetServerDestructor, error) {
+func getServer(_, addr string, controlURL string) (*tsnetServerDestructor, error) {
 	_, host, _, err := caddy.SplitNetworkAddress(addr)
 	if err != nil {
 		return nil, err
@@ -104,10 +97,9 @@ func getServer(_, addr string) (*tsnetServerDestructor, error) {
 			},
 		}
 
-		// Setting ControlURL to "TS_CONTROL_URL". If empty or not found will default to default of tsnet "https://controlplane.tailscale.com"
-		controlUrl, controlUrlFound := os.LookupEnv("TS_CONTROL_URL")
-		if controlUrlFound && controlUrl != "" {
-			s.ControlURL = controlUrl
+		// Setting ControlURL. If empty or not found will default to default of tsnet "https://controlplane.tailscale.com"
+		if controlURL != "" {
+			s.ControlURL = controlURL
 		}
 
 		if host != "" {
@@ -233,6 +225,34 @@ func parseCaddyfile(_ httpcaddyfile.Helper) (caddyhttp.MiddlewareHandler, error)
 	}, nil
 }
 
+func parseAddr(addr string) (controlURL, network, host, port string, err error) {
+	controlURL = ""
+
+	network, host, port, err = caddy.SplitNetworkAddress(addr)
+	if err != nil {
+		return "", "", "", "", err
+	}
+
+	switch network {
+	case "", "tcp", "tcp4", "tcp6", "udp", "udp4", "udp6":
+	default:
+		controlURL = fmt.Sprintf("https://%s", network)
+		network = "tcp"
+		beforeSlash, afterSlash, slashFound := strings.Cut(host, "/")
+		if slashFound {
+			switch beforeSlash {
+			case "", "tcp", "tcp4", "tcp6", "udp", "udp4", "udp6":
+				network = beforeSlash
+				host = afterSlash
+			default:
+				network = "tcp"
+			}
+		}
+	}
+
+	return controlURL, network, host, port, nil
+}
+
 type tsnetServerDestructor struct {
 	*tsnet.Server
 }

transport.go

@@ -10,8 +10,9 @@ import (
 )
 
 type TailscaleCaddyTransport struct {
-	logger *zap.Logger
-	server *tsnetServerDestructor
+	logger     *zap.Logger
+	server     *tsnetServerDestructor
+	ControlURL string `json:"controlURL,omitempty"`
 }
 
 func (t *TailscaleCaddyTransport) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
@@ -21,7 +22,7 @@ func (t *TailscaleCaddyTransport) UnmarshalCaddyfile(d *caddyfile.Dispenser) err
 func (t *TailscaleCaddyTransport) Provision(context caddy.Context) error {
 	t.logger = context.Logger()
 
-	s, err := getServer("", "caddy-tsnet-client:80")
+	s, err := getServer("", "caddy-tsnet-client:80", t.ControlURL)
 	if err != nil {
 		return err
 	}