1 files changed, 156 insertions, 0 deletions
diff --git a/lib/systemd.c b/lib/systemd.c
new file mode 100644
index 0000000..56a53a6
--- /dev/null
+++ b/lib/systemd.c
@@ -0,0 +1,156 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* lib/systemd Code
+ * Copyright (C) 2016 Cumulus Networks, Inc.
+ * Donald Sharp
+ */
+
+#include <zebra.h>
+#include <sys/un.h>
+
+#include "frrevent.h"
+#include "systemd.h"
+#include "lib_errors.h"
+
+/* these are cleared from env so they don't "leak" into things we fork(),
+ * particularly for watchfrr starting individual daemons
+ *
+ * watchdog_pid is currently not used since watchfrr starts forking.
+ * (TODO: handle that better, somehow?)
+ */
+static pid_t watchdog_pid = -1;
+static intmax_t watchdog_msec;
+
+/* not used yet, but can trigger auto-switch to journald logging */
+bool sd_stdout_is_journal;
+bool sd_stderr_is_journal;
+
+static char *notify_socket;
+
+/* talk to whatever entity claims to be systemd ;)
+ *
+ * refer to sd_notify docs for messages systemd accepts over this socket.
+ * This function should be functionally equivalent to sd_notify().
+ */
+static void systemd_send_information(const char *info)
+{
+	int sock;
+	struct sockaddr_un sun;
+
+	if (!notify_socket)
+		return;
+
+	sock = socket(AF_UNIX, SOCK_DGRAM, 0);
+	if (sock < 0)
+		return;
+
+	sun.sun_family = AF_UNIX;
+	strlcpy(sun.sun_path, notify_socket, sizeof(sun.sun_path));
+
+	/* linux abstract unix socket namespace */
+	if (sun.sun_path[0] == '@')
+		sun.sun_path[0] = '\0';
+
+	/* nothing we can do if this errors out... */
+	(void)sendto(sock, info, strlen(info), 0, (struct sockaddr *)&sun,
+		     sizeof(sun));
+
+	close(sock);
+}
+
+void systemd_send_stopping(void)
+{
+	systemd_send_information("STATUS=");
+	systemd_send_information("STOPPING=1");
+}
+
+static struct event_loop *systemd_master = NULL;
+
+static void systemd_send_watchdog(struct event *t)
+{
+	systemd_send_information("WATCHDOG=1");
+
+	assert(watchdog_msec > 0);
+	event_add_timer_msec(systemd_master, systemd_send_watchdog, NULL,
+			     watchdog_msec, NULL);
+}
+
+void systemd_send_started(struct event_loop *m)
+{
+	assert(m != NULL);
+
+	systemd_master = m;
+
+	systemd_send_information("READY=1");
+	if (watchdog_msec > 0)
+		systemd_send_watchdog(NULL);
+}
+
+void systemd_send_status(const char *status)
+{
+	char buffer[1024];
+
+	snprintf(buffer, sizeof(buffer), "STATUS=%s", status);
+	systemd_send_information(buffer);
+}
+
+static intmax_t getenv_int(const char *varname, intmax_t dflt)
+{
+	char *val, *err;
+	intmax_t intval;
+
+	val = getenv(varname);
+	if (!val)
+		return dflt;
+
+	intval = strtoimax(val, &err, 0);
+	if (*err || !*val)
+		return dflt;
+	return intval;
+}
+
+void systemd_init_env(void)
+{
+	char *tmp;
+	uintmax_t dev, ino;
+	int len;
+	struct stat st;
+
+	notify_socket = getenv("NOTIFY_SOCKET");
+
+	/* no point in setting up watchdog w/o notify socket */
+	if (notify_socket) {
+		intmax_t watchdog_usec;
+
+		watchdog_pid = getenv_int("WATCHDOG_PID", -1);
+		if (watchdog_pid <= 0)
+			watchdog_pid = -1;
+
+		/* note this is the deadline, hence the divide by 3 */
+		watchdog_usec = getenv_int("WATCHDOG_USEC", 0);
+		if (watchdog_usec >= 3000)
+			watchdog_msec = watchdog_usec / 3000;
+		else {
+			if (watchdog_usec != 0)
+				flog_err(
+					EC_LIB_UNAVAILABLE,
+					"systemd expects a %jd microsecond watchdog timer, but FRR only supports millisecond resolution!",
+					watchdog_usec);
+			watchdog_msec = 0;
+		}
+	}
+
+	tmp = getenv("JOURNAL_STREAM");
+	if (tmp && sscanf(tmp, "%ju:%ju%n", &dev, &ino, &len) == 2
+	    && (size_t)len == strlen(tmp)) {
+		if (fstat(1, &st) == 0 && st.st_dev == (dev_t)dev
+		    && st.st_ino == (ino_t)ino)
+			sd_stdout_is_journal = true;
+		if (fstat(2, &st) == 0 && st.st_dev == (dev_t)dev
+		    && st.st_ino == (ino_t)ino)
+			sd_stderr_is_journal = true;
+	}
+
+	/* these should *not* be passed to any other process we start */
+	unsetenv("WATCHDOG_PID");
+	unsetenv("WATCHDOG_USEC");
+}