def callPing(self, nodeToAsk, cert=None):        
        address = (nodeToAsk.ip, nodeToAsk.port)
        challenge = generate_challenge()
        try:
            private = OpenSSL.crypto.load_privatekey(OpenSSL.crypto.FILETYPE_PEM,
                                                    self.priv_key,
                                                    '')
            signature = OpenSSL.crypto.sign(private,
                                           nodeToAsk.id.encode("hex").upper() + challenge,
                                           "sha256")
        except:
            logger(self.sourceNode, "RETNONE: Signing of ping failed")
            return None
        d = self.ping(address,
                     self.sourceNode.id,
                     challenge,
                     signature,
                     cert)
        return d.addCallback(self.handleSignedPingResponse,
                            nodeToAsk,
                            challenge)
Sends a ping message to 'nodeToAsk'
dataset/ETHPy150Open EricssonResearch/calvin-base/calvin/runtime/south/plugins/storage/twistedimpl/securedht/append_server.py/KademliaProtocolAppend.callPing