add unix domain socket support for websocket (#1486)

src/App.h

@@ -533,6 +533,18 @@ public:
         return std::move(*this);
     }
 
+    /* options, callback, path to unix domain socket */
+    TemplatedApp &&listen(int options, MoveOnlyFunction<void(us_listen_socket_t *)> &&handler, std::string path) {
+        handler(httpContext ? httpContext->listen(path.c_str(), options) : nullptr);
+        return std::move(*this);
+    }
+
+    /* callback, path to unix domain socket */
+    TemplatedApp &&listen(MoveOnlyFunction<void(us_listen_socket_t *)> &&handler, std::string path) {
+        handler(httpContext ? httpContext->listen(path.c_str(), 0) : nullptr);
+        return std::move(*this);
+    }
+
     TemplatedApp &&run() {
         uWS::run();
         return std::move(*this);

src/HttpContext.h

@@ -445,6 +445,11 @@ public:
     us_listen_socket_t *listen(const char *host, int port, int options) {
         return us_socket_context_listen(SSL, getSocketContext(), host, port, options, sizeof(HttpResponseData<SSL>));
     }
+
+    /* Listen to unix domain socket using this HttpContext */
+    us_listen_socket_t *listen(const char *path, int options) {
+        return us_socket_context_listen_unix(SSL, getSocketContext(), path, options, sizeof(HttpResponseData<SSL>));
+    }
 };
 
 }