Systemd-based socket activation

configure.ac

@@ -351,5 +351,13 @@ AC_SEARCH_LIBS(clock_nanosleep, [rt posix4])
 # Check for clock_nanosleep support
 AC_CHECK_FUNCS([clock_nanosleep])
 
+#
+# Check for systemd to support socket-based activation
+#
+AC_CHECK_HEADERS([systemd/sd-daemon.h],
+		 AC_DEFINE([HAVE_SD_DAEMON_H], [1], [Have sd-daemon support.])
+		 AC_SEARCH_LIBS(sd_listen_fds, [systemd]))
+
+
 AC_CONFIG_FILES([Makefile src/Makefile src/version.h examples/Makefile iperf3.spec])
 AC_OUTPUT

contrib/iperf3_@.service

@@ -0,0 +1,5 @@
+[Unit]
+Description=Socket-Activated iperf3
+
+[Service]
+ExecStart=/usr/local/bin/iperf3 -s -1 -p %i --forceflush

contrib/iperf3_@.socket

@@ -0,0 +1,6 @@
+[Socket]
+ListenStream=%i
+
+[Install]
+WantedBy=sockets.target
+

src/iperf_config.h.in

@@ -66,6 +66,9 @@
 /* Have SCTP support. */
 #undef HAVE_SCTP_H
 
+/* Have sd-daemon support. */
+#undef HAVE_SD_DAEMON_H
+
 /* Define to 1 if you have the 'sendfile' function. */
 #undef HAVE_SENDFILE
 

src/iperf_server_api.c

@@ -65,6 +65,10 @@
 #endif /* TCP_CA_NAME_MAX */
 #endif /* HAVE_TCP_CONGESTION */
 
+#if defined(HAVE_SD_DAEMON_H)
+#include <systemd/sd-daemon.h>
+#endif
+
 void *
 iperf_server_worker_run(void *s) {
     struct iperf_stream *sp = (struct iperf_stream *) s;
@@ -112,8 +116,19 @@ iperf_server_worker_run(void *s) {
 int
 iperf_server_listen(struct iperf_test *test)
 {
+    int n_systemd_fds = 0;
     retry:
-    if((test->listener = netannounce(test->settings->domain, Ptcp, test->bind_address, test->bind_dev, test->server_port)) < 0) {
+#if defined(HAVE_SD_DAEMON_H)
+    n_systemd_fds  = sd_listen_fds(0);
+    // Got more than one fd from systemd, or sd_listen_fds encountered an error:
+    if (n_systemd_fds > 1 || n_systemd_fds < 0)
+            return -1;
+
+    if (1 == n_systemd_fds)
+            test->listener = SD_LISTEN_FDS_START + 0;
+#endif
+
+    if (0 == n_systemd_fds && (test->listener = netannounce(test->settings->domain, Ptcp, test->bind_address, test->bind_dev, test->server_port)) < 0) {
 	if (errno == EAFNOSUPPORT && (test->settings->domain == AF_INET6 || test->settings->domain == AF_UNSPEC)) {
 	    /* If we get "Address family not supported by protocol", that
 	    ** probably means we were compiled with IPv6 but the running