support/testing: mdnsd: new runtime test

Boot an armv5 image running the mdnsd responder alongside the mquery
client, then check that service discovery works: mquery browses for the
bundled _http._tcp service and mdnsd, on the same host, answers over the
loopback of the eth0 multicast group.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>
[Julien: add "mdnsd -v" invocation to show version]
Signed-off-by: Julien Olivain <ju.o@free.fr>

DEVELOPERS

@@ -1665,6 +1665,7 @@ F:	package/ssdp-responder/
 F:	package/sysklogd/
 F:	package/uredir/
 F:	package/watchdogd/
+F:	support/testing/tests/package/test_mdnsd.py
 
 N:	Jochen Baltes <jochen.baltes@gmail.com>
 F:	package/altera-stapl

support/testing/tests/package/test_mdnsd.py

@@ -0,0 +1,41 @@
+import os
+
+import infra.basetest
+
+
+class TestMdnsd(infra.basetest.BRTest):
+    config = infra.basetest.BASIC_TOOLCHAIN_CONFIG + \
+        """
+        BR2_PACKAGE_MDNSD=y
+        BR2_PACKAGE_MDNSD_MQUERY=y
+        BR2_PACKAGE_MDNSD_HTTP_SERVICE=y
+        BR2_SYSTEM_DHCP="eth0"
+        BR2_TARGET_ROOTFS_CPIO=y
+        # BR2_TARGET_ROOTFS_TAR is not set
+        """
+
+    def test_run(self):
+        img = os.path.join(self.builddir, "images", "rootfs.cpio")
+        self.emulator.boot(arch="armv5",
+                           kernel="builtin",
+                           options=["-initrd", img,
+                                    "-net", "nic,model=rtl8139",
+                                    "-net", "user"])
+        self.emulator.login()
+
+        # We check the program can execute.
+        self.assertRunOk("mdnsd -v")
+
+        # The responder is started at boot by /etc/init.d/S50mdnsd and
+        # advertises the bundled _http._tcp service from /etc/mdns.d/.
+        self.assertRunOk("pidof mdnsd")
+
+        # mdnsd only answers on multicast capable interfaces that are
+        # up, so wait for eth0 to get its DHCP address before querying.
+        cmd = "while ! ifconfig eth0 | grep -q 'inet addr'; do sleep 1; done"
+        self.assertRunOk(cmd, timeout=30)
+
+        # mquery sends a multicast query for the advertised service;
+        # output is one "+ NAME (IP)" line per instance
+        cmd = "mquery -T _http._tcp |grep -F buildroot._http._tcp.local"
+        self.assertRunOk(cmd, timeout=30)