Initial support for RFC 868 (rdate), internal inetd service.

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

plugins/Makefile

@@ -4,7 +4,7 @@ CPPFLAGS   += -I..
 LDFLAGS    := $(filter-out -rdynamic, $(LDFLAGS))
 LDFLAGS    += -shared
 PLUGINS    ?= initctl.so alsa-utils.so bootmisc.so dbus.so hwclock.so \
-	      resolvconf.so urandom.so x11-common.so tty.so
+	      resolvconf.so urandom.so x11-common.so tty.so time.so
 DEPS        = $(addprefix .,$(PLUGINS:.so=.d))
 TOPDIR     ?= $(shell pwd)
 

plugins/time.c

@@ -0,0 +1,87 @@
+/* Optional inetd plugin for time (rdate) protocol RFC 868
+ *
+ * Copyright (c) 2015  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 <time.h>
+#include <unistd.h>		/* STDIN_FILENO */
+#include <sys/socket.h>
+
+#include "plugin.h"
+
+/* UNIX epoch starts midnight, 1st Jan, 1970 */
+#define EPOCH_OFFSET 2208988800ULL
+
+/* Return number of seconds since midnight, 1st Jan, 1900 */
+static int rfc868(int type)
+{
+	int sd = STDIN_FILENO;
+	time_t now;
+	struct sockaddr_storage sa;
+	socklen_t sa_len = sizeof(sa);
+
+	if (SOCK_DGRAM == type) {
+		int dummy;
+
+		/* Read empty datagram in UDP mode before sending reply. */
+		if (-1 == recvfrom(sd, &dummy, sizeof(dummy), MSG_DONTWAIT, (struct sockaddr *)&sa, &sa_len))
+			return -1;	/* On error, close connection. */
+	}
+
+	now = time(NULL);
+	if ((time_t)-1 == now)
+		return -1;		/* On error, close connection. */
+
+	/* Account for UNIX epoch offset */
+	now += EPOCH_OFFSET;
+
+	/* Convert to network byte order, not explicitly stated in RFC */
+	now = htonl(now);
+
+	/* Send reply, ignore error, simply close connection. */
+	return sendto(sd, &now, sizeof(now), MSG_DONTWAIT, (struct sockaddr *)&sa, sa_len);
+}
+
+static plugin_t plugin = {
+	.name  = "time",
+	.inetd = {
+		.cmd = rfc868
+	}
+};
+
+PLUGIN_INIT(plugin_init)
+{
+	plugin_register(&plugin);
+}
+
+PLUGIN_EXIT(plugin_exit)
+{
+	plugin_unregister(&plugin);
+}
+
+/**
+ * Local Variables:
+ *  version-control: t
+ *  indent-tabs-mode: t
+ *  c-file-style: "linux"
+ * End:
+ */