Python: add utility function for retrieving port redirection

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.utils" module to host the utility
function and a test.

Signed-off-by: Cleber Rosa <crosa@redhat.com>
Reviewed-by: Wainer dos Santos Moschetta <wainersm@redhat.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Willian Rampazzo <willianr@redhat.com>
Message-Id: <20210412044644.55083-4-crosa@redhat.com>
Signed-off-by: John Snow <jsnow@redhat.com>
[Squashed in below fix. --js]
Signed-off-by: John Snow <jsnow@redhat.com>
Signed-off-by: Cleber Rosa <crosa@redhat.com>
Message-Id: <20210601154546.130870-2-crosa@redhat.com>
Signed-off-by: John Snow <jsnow@redhat.com>

python/qemu/utils.py

@@ -0,0 +1,33 @@
+"""
+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"
+    :return: the port number allocated by the hostfwd option
+    """
+    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

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'))

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):
-        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]
-        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()
+        res = self.vm.command('human-monitor-command',
+                              command_line='info usernet')
+        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)
         self.ssh_session = ssh.Session(self.VM_IP, port=int(port),
                                        user=username, password=password)
         for i in range(10):

tests/acceptance/virtiofs_submounts.py

@@ -9,6 +9,8 @@ from avocado_qemu import LinuxTest, BUILD_DIR
 from avocado_qemu import wait_for_console_pattern
 from avocado.utils import ssh
 
+from qemu.utils import get_info_usernet_hostfwd_port
+
 
 def run_cmd(args):
     subp = subprocess.Popen(args,
@@ -73,27 +75,14 @@ class VirtiofsSubmountsTest(LinuxTest):
     :avocado: tags=accel:kvm
     """
 
-    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):

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
@@ -227,7 +228,7 @@ class BaseVM(object):
                    "-o", "UserKnownHostsFile=" + os.devnull,
                    "-o",
                    "ConnectTimeout={}".format(self._config["ssh_timeout"]),
-                   "-p", self.ssh_port, "-i", self._ssh_tmp_key_file]
+                   "-p", str(self.ssh_port), "-i", self._ssh_tmp_key_file]
         # If not in debug mode, set ssh to quiet mode to
         # avoid printing the results of commands.
         if not self.debug:
@@ -305,12 +306,8 @@ class BaseVM(object):
         # Init console so we can start consuming the chars.
         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]
+                                 command_line="info usernet").get("return")
+        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)