Add support for already-listening sockets

capi/libuwebsockets.cpp

@@ -338,17 +338,36 @@ extern "C"
 
     void uws_app_listen_with_config(int ssl, uws_app_t *app, uws_app_listen_config_t config, uws_listen_handler handler, void *user_data)
     {
+        /* branching is getting untidy */
         if (ssl)
         {
             uWS::SSLApp *uwsApp = (uWS::SSLApp *)app;
-            uwsApp->listen(config.host, config.port, config.options, [handler, config, user_data](struct us_listen_socket_t *listen_socket)
-                           { handler((struct us_listen_socket_t *)listen_socket, config, user_data); });
+            if (config.fd) {
+                uwsApp->listen(
+                    config.options,
+                    [handler, config, user_data](struct us_listen_socket_t *listen_socket) {
+                        handler((struct us_listen_socket_t *)listen_socket, config, user_data);
+                    },
+                    config.fd);
+            } else {
+                uwsApp->listen(config.host, config.port, config.options, [handler, config, user_data](struct us_listen_socket_t *listen_socket)
+                               { handler((struct us_listen_socket_t *)listen_socket, config, user_data); });
+            }
         }
         else
         {
             uWS::App *uwsApp = (uWS::App *)app;
-            uwsApp->listen(config.host, config.port, config.options, [handler, config, user_data](struct us_listen_socket_t *listen_socket)
-                           { handler((struct us_listen_socket_t *)listen_socket, config, user_data); });
+            if (config.fd) {
+                uwsApp->listen(
+                    config.options,
+                    [handler, config, user_data](struct us_listen_socket_t *listen_socket) {
+                        handler((struct us_listen_socket_t *)listen_socket, config, user_data);
+                    },
+                    config.fd);
+            } else {
+                uwsApp->listen(config.host, config.port, config.options, [handler, config, user_data](struct us_listen_socket_t *listen_socket)
+                               { handler((struct us_listen_socket_t *)listen_socket, config, user_data); });
+            }
         }
     }
 

capi/libuwebsockets.h

@@ -90,7 +90,7 @@ extern "C"
 
     DLL_EXPORT typedef struct
     {
-
+        LIBUS_SOCKET_DESCRIPTOR fd;
         int port;
         const char *host;
         int options;

src/App.h

@@ -21,6 +21,7 @@
 #include <string>
 #include <charconv>
 #include <string_view>
+#include "libusockets.h"
 
 namespace uWS {
     /* Safari 15.0 - 15.3 has a completely broken compression implementation (client_no_context_takeover not
@@ -561,6 +562,18 @@ struct TemplatedApp {
         handler(httpContext ? httpContext->listen(nullptr, port, options) : nullptr);
         return std::move(*this);
     }
+
+    /* callback, fd */
+    TemplatedApp &&listen(MoveOnlyFunction<void(us_listen_socket_t *)> &&handler, LIBUS_SOCKET_DESCRIPTOR fd) {
+        handler(httpContext ? httpContext->listen(fd, 0) : nullptr);
+        return std::move(*this);
+    }
+
+    /* options, callback, fd */
+    TemplatedApp &&listen(int options, MoveOnlyFunction<void(us_listen_socket_t *)> &&handler, LIBUS_SOCKET_DESCRIPTOR fd) {
+        handler(httpContext ? httpContext->listen(fd, options) : nullptr);
+        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) {

src/HttpContext.h

@@ -25,6 +25,7 @@
 #include "HttpResponseData.h"
 #include "AsyncSocket.h"
 #include "WebSocketData.h"
+#include "libusockets.h"
 
 #include <string_view>
 #include <iostream>
@@ -466,6 +467,12 @@ struct HttpContext {
     us_listen_socket_t *listen(const char *path, int options) {
         return us_socket_context_listen_unix(SSL, getSocketContext(), path, options, sizeof(HttpResponseData<SSL>));
     }
+
+    /* Attach to bound and listening socket (fd) using this HttpContext */
+    us_listen_socket_t *listen(LIBUS_SOCKET_DESCRIPTOR fd, int options) {
+        return us_socket_context_listen_direct(SSL, getSocketContext(), fd, options, sizeof(HttpResponseData<SSL>));
+    }
+
 };
 
 }