Feat: show an error if the hostname is longer than 15 characters

usr/lib/python3/dist-packages/linuxmusterLinuxclient7/computer.py

@@ -1,5 +1,5 @@
-import socket
-from linuxmusterLinuxclient7 import logging, ldapHelper, realm, localUserHelper
+import socket, os, subprocess
+from linuxmusterLinuxclient7 import logging, constants, ldapHelper, realm, localUserHelper
 
 def hostname():
     """
@@ -10,6 +10,31 @@ def hostname():
     """
     return socket.gethostname().split('.', 1)[0]
 
+def hostnameIsValid():
+    """
+    Check if the hostname can be used as a computer account name in the AD (max. 15 characters)
+
+    :return: True or False
+    :rtype: bool
+    """
+    return len(hostname()) <= constants.maxHostnameLength
+
+def checkHostname():
+    """
+    Check if the hostname is valid. If not, an error is logged and shown on the GDM login screen.
+
+    :return: True if the hostname is valid, False otherwise
+    :rtype: bool
+    """
+    if hostnameIsValid():
+        _setLoginScreenWarning(None)
+        return True
+
+    message = f"The hostname '{hostname()}' is longer than {constants.maxHostnameLength} characters, domain logins will not work! Please use a shorter hostname in the devices.csv."
+    logging.error(message)
+    _setLoginScreenWarning(message)
+    return False
+
 def krbHostName():
     """
     Get the krb hostname, eg. `COMPUTER01$`
@@ -54,4 +79,52 @@ def isInAD():
     if not rc:
         return False
 
-    return "domain computers" in groups
+    return "domain computers" in groups
+
+# --------------------
+# - Helper functions -
+# --------------------
+
+def _setLoginScreenWarning(message):
+    """
+    Show a warning on the GDM login screen or remove it
+
+    :param message: The message to show, None to remove the warning
+    :type message: str
+    :return: True if the warning was changed, False otherwise
+    :rtype: bool
+    """
+    if not os.path.isdir(constants.gdmDconfDir):
+        return False
+
+    if message == None:
+        if not os.path.exists(constants.loginScreenWarningFile):
+            return False
+        os.remove(constants.loginScreenWarningFile)
+    else:
+        content = f"[org/gnome/login-screen]\nbanner-message-enable=true\nbanner-message-text=\"{message}\"\n"
+        if os.path.exists(constants.loginScreenWarningFile):
+            with open(constants.loginScreenWarningFile, "r") as file:
+                if file.read() == content:
+                    return False
+        with open(constants.loginScreenWarningFile, "w") as file:
+            file.write(content)
+
+    subprocess.call(["/usr/share/gdm/generate-config"], stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+    if not _userIsLoggedIn():
+        subprocess.call(["systemctl", "try-restart", "gdm"])
+    return True
+
+def _userIsLoggedIn():
+    """
+    Check if a user (other than the display manager) is logged in
+
+    :return: True or False
+    :rtype: bool
+    """
+    result = subprocess.run(["loginctl", "list-users", "--no-legend"], stdout=subprocess.PIPE, stderr=subprocess.PIPE, universal_newlines=True)
+    for line in result.stdout.split("\n"):
+        columns = line.split()
+        if len(columns) >= 2 and not columns[1].startswith("gdm"):
+            return True
+    return False

usr/lib/python3/dist-packages/linuxmusterLinuxclient7/constants.py

@@ -10,6 +10,9 @@
 shareMountBasepath = "/home/{}/media"
 hiddenShareMountBasepath = "/srv/samba/{}"
 machineAccountSysvolMountPath = "/var/lib/samba/sysvol"
+maxHostnameLength = 15
+gdmDconfDir = "/usr/share/gdm/dconf"
+loginScreenWarningFile = gdmDconfDir + "/95-linuxmuster-linuxclient7"
 defaultShareLetterTemplate = " ({letter}:)"
 
 etcBaseDir = "/etc/linuxmuster-linuxclient7"

usr/lib/python3/dist-packages/linuxmusterLinuxclient7/setup.py

@@ -15,6 +15,9 @@ def setup(domain=None, user=None):
     """
     logging.info('#### linuxmuster-linuxclient7 setup ####')
 
+    if not computer.checkHostname():
+        return False
+
     userCacheCleared = realm.clearUserCache()
     if not userCacheCleared and isSetup():
         return False
@@ -88,6 +91,10 @@ def status():
 
     logging.info("Linuxmuster-linuxclient7 is setup!")
 
+    logging.info("Checking hostname...")
+    if not computer.checkHostname():
+        return False
+
     logging.info("Checking sssd krb5_child capabilities...")
     if not _checkSssdKrb5ChildCaps():
         return False

usr/lib/python3/dist-packages/linuxmusterLinuxclient7/tests/test_computer.py

@@ -1,11 +1,70 @@
+from subprocess import CompletedProcess
 from unittest import mock
 from .. import computer
+import os
 
 @mock.patch("linuxmusterLinuxclient7.computer.socket.gethostname")
 def test_hostname(mockSocketGetHostname):
     mockSocketGetHostname.return_value = "computer1.linuxmuster.lan"
     assert computer.hostname() == "computer1"
 
+@mock.patch("linuxmusterLinuxclient7.computer.hostname")
+def test_hostnameIsValid(mockHostname):
+    mockHostname.return_value = "computer1"
+    assert computer.hostnameIsValid()
+    mockHostname.return_value = "aabk-r100-pc012"
+    assert computer.hostnameIsValid()
+    mockHostname.return_value = "aabk-r100-pc0123"
+    assert not computer.hostnameIsValid()
+
+@mock.patch("linuxmusterLinuxclient7.computer._setLoginScreenWarning")
+@mock.patch("linuxmusterLinuxclient7.computer.hostname")
+def test_checkHostname(mockHostname, mockSetLoginScreenWarning):
+    mockHostname.return_value = "computer1"
+    assert computer.checkHostname()
+    assert mockSetLoginScreenWarning.call_args.args[0] is None
+
+    mockHostname.return_value = "aabk-r100-pc0123"
+    assert not computer.checkHostname()
+    assert "aabk-r100-pc0123" in mockSetLoginScreenWarning.call_args.args[0]
+
+@mock.patch("linuxmusterLinuxclient7.computer._userIsLoggedIn")
+@mock.patch("linuxmusterLinuxclient7.computer.subprocess.call")
+def test_setLoginScreenWarning(mockSubprocessCall, mockUserIsLoggedIn, tmp_path):
+    warningFile = str(tmp_path / "95-linuxmuster-linuxclient7")
+    mockUserIsLoggedIn.return_value = False
+
+    with mock.patch("linuxmusterLinuxclient7.computer.constants.gdmDconfDir", str(tmp_path)), mock.patch("linuxmusterLinuxclient7.computer.constants.loginScreenWarningFile", warningFile):
+        assert not computer._setLoginScreenWarning(None)
+        assert mockSubprocessCall.call_count == 0
+
+        assert computer._setLoginScreenWarning("Hostname too long")
+        with open(warningFile) as file:
+            content = file.read()
+        assert "banner-message-enable=true" in content
+        assert 'banner-message-text="Hostname too long"' in content
+        assert ["systemctl", "try-restart", "gdm"] in [c.args[0] for c in mockSubprocessCall.call_args_list]
+
+        mockSubprocessCall.reset_mock()
+        assert not computer._setLoginScreenWarning("Hostname too long")
+        assert mockSubprocessCall.call_count == 0
+
+        mockUserIsLoggedIn.return_value = True
+        assert computer._setLoginScreenWarning(None)
+        assert not os.path.exists(warningFile)
+        assert ["systemctl", "try-restart", "gdm"] not in [c.args[0] for c in mockSubprocessCall.call_args_list]
+
+    with mock.patch("linuxmusterLinuxclient7.computer.constants.gdmDconfDir", str(tmp_path / "missing")):
+        assert not computer._setLoginScreenWarning("Hostname too long")
+
+@mock.patch("linuxmusterLinuxclient7.computer.subprocess.run")
+def test_userIsLoggedIn(mockSubprocessRun):
+    mockSubprocessRun.return_value = CompletedProcess(args=[], returncode=0, stdout="60578 gdm-greeter no active\n")
+    assert not computer._userIsLoggedIn()
+
+    mockSubprocessRun.return_value = CompletedProcess(args=[], returncode=0, stdout="60578 gdm-greeter no active\n1662401376 yukigrun no active\n")
+    assert computer._userIsLoggedIn()
+
 @mock.patch("linuxmusterLinuxclient7.computer.hostname")
 def test_krbHostName(mockHostname):
     mockHostname.return_value = "computer1"

usr/lib/python3/dist-packages/linuxmusterLinuxclient7/tests/test_setup.py

@@ -0,0 +1,18 @@
+from unittest import mock
+from .. import setup
+
+@mock.patch("linuxmusterLinuxclient7.setup.realm.clearUserCache")
+@mock.patch("linuxmusterLinuxclient7.setup.computer.checkHostname")
+def test_setupInvalidHostname(mockCheckHostname, mockClearUserCache):
+    mockCheckHostname.return_value = False
+    assert not setup.setup()
+    assert mockClearUserCache.call_count == 0
+
+@mock.patch("linuxmusterLinuxclient7.setup._checkSssdKrb5ChildCaps")
+@mock.patch("linuxmusterLinuxclient7.setup.computer.checkHostname")
+@mock.patch("linuxmusterLinuxclient7.setup.isSetup")
+def test_statusInvalidHostname(mockIsSetup, mockCheckHostname, mockCheckSssdKrb5ChildCaps):
+    mockIsSetup.return_value = True
+    mockCheckHostname.return_value = False
+    assert not setup.status()
+    assert mockCheckSssdKrb5ChildCaps.call_count == 0

usr/share/linuxmuster-linuxclient7/scripts/onBoot

@@ -6,10 +6,12 @@
 # This script is called in root context when the client is booted
 try:
     import os, sys
-    from linuxmusterLinuxclient7 import logging, hooks, shares, constants, keytab, realm
+    from linuxmusterLinuxclient7 import logging, hooks, shares, constants, keytab, realm, computer
 
     logging.info("====== onBoot started ======")
 
+    computer.checkHostname()
+
     keytab.patchKeytab()
     realm.pullKerberosTicketForComputerAccount(timeout=5)