[PATCH 10/22] Python: add utility function for retrieving port redirection

[Cleber Rosa]

Slightly different versions for the same utility code are currently
present on different locations.  This unifies them all, giving
preference to the version from virtiofs_submounts.py, because of the
last tweaks added to it.

While at it, this adds a "qemu.util" module to host the utility
function and a test.

Signed-off-by: Cleber Rosa <crosa@redhat.com>
---
 python/qemu/utils.py                     | 35 ++++++++++++++++++++++++
 tests/acceptance/info_usernet.py         | 29 ++++++++++++++++++++
 tests/acceptance/linux_ssh_mips_malta.py | 16 +++++------
 tests/acceptance/virtiofs_submounts.py   | 20 +++-----------
 tests/vm/basevm.py                       |  7 ++---
 5 files changed, 77 insertions(+), 30 deletions(-)
 create mode 100644 python/qemu/utils.py
 create mode 100644 tests/acceptance/info_usernet.py

diff --git a/python/qemu/utils.py b/python/qemu/utils.py
new file mode 100644
index 0000000000..89a246ab30
--- /dev/null
+++ b/python/qemu/utils.py
@@ -0,0 +1,35 @@
+"""
+QEMU utility library
+
+This offers miscellaneous utility functions, which may not be easily
+distinguishable or numerous to be in their own module.
+"""
+
+# Copyright (C) 2021 Red Hat Inc.
+#
+# Authors:
+#  Cleber Rosa <crosa@redhat.com>
+#
+# This work is licensed under the terms of the GNU GPL, version 2.  See
+# the COPYING file in the top-level directory.
+#
+
+import re
+from typing import Optional
+
+
+def get_info_usernet_hostfwd_port(info_usernet_output: str) -> Optional[int]:
+    """
+    Returns the port given to the hostfwd parameter via info usernet
+
+    :param info_usernet_output: output generated by hmp command "info usernet"
+    :param info_usernet_output: str
+    :return: the port number allocated by the hostfwd option
+    :rtype: int
+    """
+    for line in info_usernet_output.split('\r\n'):
+        regex = r'TCP.HOST_FORWARD.*127\.0\.0\.1\s+(\d+)\s+10\.'
+        match = re.search(regex, line)
+        if match is not None:
+            return int(match[1])
+    return None
diff --git a/tests/acceptance/info_usernet.py b/tests/acceptance/info_usernet.py
new file mode 100644
index 0000000000..9c1fd903a0
--- /dev/null
+++ b/tests/acceptance/info_usernet.py
@@ -0,0 +1,29 @@
+# Test for the hmp command "info usernet"
+#
+# Copyright (c) 2021 Red Hat, Inc.
+#
+# Author:
+#  Cleber Rosa <crosa@redhat.com>
+#
+# This work is licensed under the terms of the GNU GPL, version 2 or
+# later.  See the COPYING file in the top-level directory.
+
+from avocado_qemu import Test
+
+from qemu.utils import get_info_usernet_hostfwd_port
+
+
+class InfoUsernet(Test):
+
+    def test_hostfwd(self):
+        self.vm.add_args('-netdev', 'user,id=vnet,hostfwd=:127.0.0.1:0-:22')
+        self.vm.launch()
+        res = self.vm.command('human-monitor-command',
+                              command_line='info usernet')
+        port = get_info_usernet_hostfwd_port(res)
+        self.assertIsNotNone(port,
+                             ('"info usernet" output content does not seem to '
+                              'contain the redirected port'))
+        self.assertGreater(port, 0,
+                           ('Found a redirected port that is not greater than'
+                            ' zero'))
diff --git a/tests/acceptance/linux_ssh_mips_malta.py 
b/tests/acceptance/linux_ssh_mips_malta.py
index 25c5c5f741..275659c785 100644
--- a/tests/acceptance/linux_ssh_mips_malta.py
+++ b/tests/acceptance/linux_ssh_mips_malta.py
@@ -18,6 +18,8 @@ from avocado.utils import process
 from avocado.utils import archive
 from avocado.utils import ssh
 
+from qemu.utils import get_info_usernet_hostfwd_port
+
 
 class LinuxSSH(Test):
 
@@ -70,18 +72,14 @@ class LinuxSSH(Test):
     def setUp(self):
         super(LinuxSSH, self).setUp()
 
-    def get_portfwd(self):
+    def ssh_connect(self, username, password):
+        self.ssh_logger = logging.getLogger('ssh')
         res = self.vm.command('human-monitor-command',
                               command_line='info usernet')
-        line = res.split('\r\n')[2]
-        port = re.split(r'.*TCP.HOST_FORWARD.*127\.0\.0\.1 (\d+)\s+10\..*',
-                        line)[1]
+        port = get_info_usernet_hostfwd_port(res)
+        if not port:
+            self.cancel("Failed to retrieve SSH port")
         self.log.debug("sshd listening on port:" + port)
-        return port
-
-    def ssh_connect(self, username, password):
-        self.ssh_logger = logging.getLogger('ssh')
-        port = self.get_portfwd()
         self.ssh_session = ssh.Session(self.VM_IP, port=int(port),
                                        user=username, password=password)
         for i in range(10):
diff --git a/tests/acceptance/virtiofs_submounts.py 
b/tests/acceptance/virtiofs_submounts.py
index 0f9d7a5d9c..bf99164fcb 100644
--- a/tests/acceptance/virtiofs_submounts.py
+++ b/tests/acceptance/virtiofs_submounts.py
@@ -10,6 +10,7 @@ from avocado_qemu import wait_for_console_pattern
 from avocado.utils import ssh
 
 from qemu.accel import kvm_available
+from qemu.utils import get_info_usernet_hostfwd_port
 
 from boot_linux import BootLinux
 
@@ -76,27 +77,14 @@ class VirtiofsSubmountsTest(BootLinux):
     :avocado: tags=arch:x86_64
     """
 
-    def get_portfwd(self):
-        port = None
-
+    def ssh_connect(self, username, keyfile):
+        self.ssh_logger = logging.getLogger('ssh')
         res = self.vm.command('human-monitor-command',
                               command_line='info usernet')
-        for line in res.split('\r\n'):
-            match = \
-                re.search(r'TCP.HOST_FORWARD.*127\.0\.0\.1\s+(\d+)\s+10\.',
-                          line)
-            if match is not None:
-                port = int(match[1])
-                break
-
+        port = get_info_usernet_hostfwd_port(res)
         self.assertIsNotNone(port)
         self.assertGreater(port, 0)
         self.log.debug('sshd listening on port: %d', port)
-        return port
-
-    def ssh_connect(self, username, keyfile):
-        self.ssh_logger = logging.getLogger('ssh')
-        port = self.get_portfwd()
         self.ssh_session = ssh.Session('127.0.0.1', port=port,
                                        user=username, key=keyfile)
         for i in range(10):
diff --git a/tests/vm/basevm.py b/tests/vm/basevm.py
index 00f1d5ca8d..75ce07df36 100644
--- a/tests/vm/basevm.py
+++ b/tests/vm/basevm.py
@@ -21,6 +21,7 @@ import datetime
 sys.path.append(os.path.join(os.path.dirname(__file__), '..', '..', 'python'))
 from qemu.accel import kvm_available
 from qemu.machine import QEMUMachine
+from qemu.utils import get_info_usernet_hostfwd_port
 import subprocess
 import hashlib
 import argparse
@@ -306,11 +307,7 @@ class BaseVM(object):
         self.console_init()
         usernet_info = guest.qmp("human-monitor-command",
                                  command_line="info usernet")
-        self.ssh_port = None
-        for l in usernet_info["return"].splitlines():
-            fields = l.split()
-            if "TCP[HOST_FORWARD]" in fields and "22" in fields:
-                self.ssh_port = l.split()[3]
+        self.ssh_port = get_info_usernet_hostfwd_port(usernet_info)
         if not self.ssh_port:
             raise Exception("Cannot find ssh port from 'info usernet':\n%s" % \
                             usernet_info)
-- 
2.25.4