feat: add support for specifying custom querystring arguments

This allows folks to implement token-based authentication for websocket access.

Closes #82

server/handlers.go

@@ -8,6 +8,7 @@ import (
 	"log"
 	"net/http"
 	"net/url"
+	"strings"
 	"sync/atomic"
 
 	"github.com/gorilla/websocket"
@@ -233,7 +234,12 @@ func (server *Server) handleAuthToken(w http.ResponseWriter, r *http.Request) {
 
 func (server *Server) handleConfig(w http.ResponseWriter, r *http.Request) {
 	w.Header().Set("Content-Type", "application/javascript")
-	w.Write([]byte("var gotty_term = 'xterm';"))
+	lines := []string{
+		"var gotty_term = 'xterm';",
+		"var gotty_ws_query_args = '" + server.options.WSQueryArgs + "';",
+	}
+
+	w.Write([]byte(strings.Join(lines, "\n")))
 }
 
 // titleVariables merges maps in a specified order.