node: verify telnet installation for controller checking

Reported-by: Julius Bachnick https://mailman.stanford.edu/pipermail/mininet-discuss/2012-November/001349.html
2012-11-26 15:22:07 -08:00
parent 1e9b5f61fc
commit b453e0068f
1 changed files with 6 additions and 0 deletions
@@ -995,6 +995,12 @@ class Controller( Node ):

    def checkListening( self ):
        "Make sure no controllers are running on our port"
+        # Verify that Telnet is installed first:
+        out, err, returnCode = errRun( "which telnet" )
+        if 'telnet' not in out or returnCode != 0:
+            raise Exception( "Error running telnet to check for listening "
+                             "controllers; please check that it is "
+                             "installed." )
        listening = self.cmd( "echo A | telnet -e A %s %d" %
                              ( self.ip, self.port ) )
        if 'Unable' not in listening: