tests: Use python twisted for sendmsg on python 2

Rather than sending two separate messages with the bare python 2
API, use the python twisted package to send the control and data
in one sendmsg() call. This avoids occasional test failures in
the ctrlchannel test case that is currently sending the data and
control part of the message in 2 steps, which can lead to the
recpient not seeing the whole message.

Add python-twisted as a build dependency to the rpm and Debian
builds and the .travis.yml.

Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>

.travis.yml

@@ -9,6 +9,7 @@ before_install:
 - pep8 $(find . -type f | grep -E "\.py$")
 - sudo apt-get -y install automake autoconf libtool libssl-dev sed make gawk sed bash
   dh-exec
+- sudo pip install twisted
 - git clone https://github.com/stefanberger/libtpms
 - cd libtpms
 - git checkout origin/tpm2-preview.rev146 -b tpm2-preview.rev146

debian/control

@@ -16,6 +16,7 @@ Build-Depends: automake,
 	       socat,
 	       findutils,
 	       tpm-tools (>= 1.3.8),
+	       python-twisted
 # linux-image-extra
 
 Package: swtpm

dist/swtpm.spec

@@ -27,7 +27,7 @@ BuildRoot:      %{_tmppath}/%{name}-%{version}-%{release}-root
 
 BuildRequires:  automake autoconf bash coreutils libtool sed
 BuildRequires:  libtpms-devel fuse-devel glib2-devel gmp-devel
-BuildRequires:  expect bash net-tools nss-devel socat
+BuildRequires:  expect bash net-tools nss-devel socat python-twisted
 %if %{with_gnutls}
 BuildRequires:  gnutls >= 3.1.0 gnutls-devel gnutls-utils
 BuildRequires:  libtasn1-devel libtasn1

dist/swtpm.spec.in

@@ -27,7 +27,7 @@ BuildRoot:      %{_tmppath}/%{name}-%{version}-%{release}-root
 
 BuildRequires:  automake autoconf bash coreutils libtool sed
 BuildRequires:  libtpms-devel fuse-devel glib2-devel gmp-devel
-BuildRequires:  expect bash net-tools nss-devel socat
+BuildRequires:  expect bash net-tools nss-devel socat python-twisted
 %if %{with_gnutls}
 BuildRequires:  gnutls >= 3.1.0 gnutls-devel gnutls-utils
 BuildRequires:  libtasn1-devel libtasn1

tests/test_setdatafd.py

@@ -6,9 +6,10 @@ import socket
 import subprocess
 import time
 import struct
+
 from array import array
 if sys.version_info[0] < 3:
-    import _multiprocessing
+    import twisted.python.sendmsg as sendmsg
 
 
 def toString(arr):
@@ -56,8 +57,10 @@ def test_SetDatafd():
         ctrlfd.connect(sock_path)
         print("Sending data fd over ctrl fd...")
         if sys.version_info[0] < 3:
-            ctrlfd.send(cmd_set_data_fd)
-            _multiprocessing.sendfd(ctrlfd.fileno(), _fd.fileno())
+            sendmsg.sendmsg(ctrlfd, str(cmd_set_data_fd),
+                            [(socket.SOL_SOCKET,
+                              sendmsg.SCM_RIGHTS,
+                              struct.pack("i", _fd.fileno()))])
         else:
             ctrlfd.sendmsg([cmd_set_data_fd],
                            [(socket.SOL_SOCKET, socket.SCM_RIGHTS, fds)])