Add support for inetd RFC862 echo server

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

configure.ac

@@ -55,6 +55,7 @@ AC_ARG_ENABLE(quiet,
 # Check for extra plugins to enable
 AC_PLUGIN([alsa-utils], [no],  [Save and restore ALSA sound settings using alsactl])
 AC_PLUGIN([dbus],       [no],  [Setup and start system message bus, D-Bus])
+AC_PLUGIN([inetd-echo], [no],  [Inetd plugin: echo server, RFC862])
 AC_PLUGIN([lost],       [no],  [Example HOOK_SVC_LOST plugin, very noisy as-is!])
 AC_PLUGIN([resolvconf], [no],  [Setup necessary files for resolvconf])
 AC_PLUGIN([x11-common], [no],  [Console setup (for X)])

plugins/Makefile.am

@@ -16,6 +16,10 @@ if BUILD_DBUS_PLUGIN
 libplug_la_SOURCES += dbus.c
 endif
 
+if BUILD_INETD_ECHO_PLUGIN
+libplug_la_SOURCES += echo.c
+endif
+
 if BUILD_LOST_PLUGIN
 libplug_la_SOURCES += lost.c
 endif
@@ -36,6 +40,10 @@ if BUILD_DBUS_PLUGIN
 pkglib_LTLIBRARIES += dbus.la
 endif
 
+if BUILD_INETD_ECHO_PLUGIN
+pkglib_LTLIBRARIES += echo.la
+endif
+
 if BUILD_LOST_PLUGIN
 pkglib_LTLIBRARIES += lost.la
 endif

plugins/echo.c

@@ -0,0 +1,67 @@
+/* Optional inetd plugin for the echo protocol RFC 862
+ *
+ * Copyright (c) 2016  Joachim Nilsson <troglobit@gmail.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <arpa/inet.h>
+#include <unistd.h>		/* STDIN_FILENO */
+#include <sys/socket.h>
+
+#include "../plugin.h"
+
+static int echo_cb(int type)
+{
+	int sd = STDIN_FILENO;
+	char buf[BUFSIZ];
+	ssize_t len;
+	struct sockaddr_storage sa;
+	socklen_t sa_len = sizeof(sa);
+
+	len = recvfrom(sd, buf, sizeof(buf), MSG_DONTWAIT, (struct sockaddr *)&sa, &sa_len);
+	if (-1 == len)
+		return -1;	/* On error, close connection. */
+
+	return sendto(sd, buf, len, MSG_DONTWAIT, (struct sockaddr *)&sa, sa_len);
+}
+
+static plugin_t plugin = {
+	.name  = "echo",	/* Must match the inetd /etc/services entry */
+	.inetd = {
+		.cmd = echo_cb
+	},
+};
+
+PLUGIN_INIT(plugin_init)
+{
+	plugin_register(&plugin);
+}
+
+PLUGIN_EXIT(plugin_exit)
+{
+	plugin_unregister(&plugin);
+}
+
+/**
+ * Local Variables:
+ *  indent-tabs-mode: t
+ *  c-file-style: "linux"
+ * End:
+ */