wait for sshd to start in example

examples/baresshd.py

@@ -4,9 +4,10 @@
 
 import sys
 from mininet.node import Host
-from mininet.util import ensureRoot
+from mininet.util import ensureRoot, waitListening
 
 ensureRoot()
+timeout = 5
 
 print "*** Creating nodes"
 h1 = Host( 'h1' )
@@ -33,5 +34,10 @@
 if len( sys.argv ) > 1:
     cmd += ' ' + ' '.join( sys.argv[ 1: ] )
 h1.cmd( cmd )
+listening = waitListening( server=h1, port=22, timeout=timeout )
 
-print "*** You may now ssh into", h1.name, "at", h1.IP()
+if listening:
+    print "*** You may now ssh into", h1.name, "at", h1.IP()
+else:
+    print ( "*** Warning: after %s seconds, %s is not listening on port 22"
+            % ( timeout, h1.name ) )

examples/test/test_baresshd.py

@@ -6,21 +6,18 @@
 
 import unittest
 import pexpect
-from time import sleep
 from mininet.clean import cleanup, sh
 
 class testBareSSHD( unittest.TestCase ):
 
-    opts = [ '\(yes/no\)\?', 'Welcome to h1', 'refused', pexpect.EOF, pexpect.TIMEOUT ]
+    opts = [ 'Welcome to h1', pexpect.EOF, pexpect.TIMEOUT ]
 
     def connected( self ):
         "Log into ssh server, check banner, then exit"
-        p = pexpect.spawn( 'ssh 10.0.0.1 -i /tmp/ssh/test_rsa exit' )
+        p = pexpect.spawn( 'ssh 10.0.0.1 -o StrictHostKeyChecking=no -i /tmp/ssh/test_rsa exit' )
         while True:
             index = p.expect( self.opts )
             if index == 0:
-                p.sendline( 'yes' )
-            elif index == 1:
                 return True
             else:
                 return False
@@ -37,18 +34,23 @@ def setUp( self ):
         cmd = ( 'python -m mininet.examples.baresshd '
                 '-o AuthorizedKeysFile=/tmp/ssh/authorized_keys '
                 '-o StrictModes=no' )
-        sh( cmd )
+        p = pexpect.spawn( cmd )
+        runOpts = [ 'You may now ssh into h1 at 10.0.0.1',
+                    'after 5 seconds, h1 is not listening on port 22', 
+                    pexpect.EOF, pexpect.TIMEOUT ]
+        while True:
+            index = p.expect( runOpts )
+            if index == 0:
+                break
+            else:
+                self.tearDown()
+                self.fail( 'sshd failed to start in host h1' )
 
     def testSSH( self ):
         "Simple test to verify that we can ssh into h1"
         result = False
         # try to connect up to 3 times; sshd can take a while to start
-        for _ in range( 3 ):
-            result = self.connected()
-            if result:
-                break
-            else:
-                sleep( 1 )
+        result = self.connected()
         self.assertTrue( result )
 
     def tearDown( self ):

mininet/util.py

@@ -543,7 +543,8 @@ def ensureRoot():
     return
 
 def waitListening( client=None, server='127.0.0.1', port=80, timeout=None ):
-    "Wait until server is listening on port"
+    """Wait until server is listening on port.
+       returns True if server is listening"""
     run = ( client.cmd if client else
                 partial( quietRun, shell=True ) )
     if not run( 'which telnet' ):
@@ -554,12 +555,13 @@ def waitListening( client=None, server='127.0.0.1', port=80, timeout=None ):
     time = 0
     while 'Connected' not in run( cmd ):
         if timeout:
+            print time
             if time >= timeout:
                 error( 'could not connect to %s on port %d\n'
                        % ( server, port ) )
-                break
+                return False
         output('waiting for', server,
                'to listen on port', port, '\n')
         sleep( .5 )
         time += .5
-
+    return True