[PATCH rhel7-branch] (v2) Catch race of network device state vs reading its config properties (#919478, #1005681)

[Radek Vykydal]

Fedora bz: #980576

Catch the infamous

DBusException: org.freedesktop.DBus.Error.UnknownMethod:
Method "Get" with signature "ss" on interface "org.freedesktop.DBus.Properties"
doesn't exist

exception.

Object with path from devices's IPXConfig property is valid only if
its device is in ACTIVATED state.
---
 pyanaconda/nm.py | 29 +++++++++++++++++++++++++----
 1 file changed, 25 insertions(+), 4 deletions(-)

diff --git a/pyanaconda/nm.py b/pyanaconda/nm.py
index dd0df99..0c88800 100644
--- a/pyanaconda/nm.py
+++ b/pyanaconda/nm.py
@@ -53,7 +53,12 @@ class SettingNotFoundError(ValueError):
         return self.__repr__()

class DeviceSettingsNotFoundError(ValueError):
-    """Settings (NMRemoteConnection object was not found"""
+    """Settings NMRemoteConnection object was not found"""
+    def __str__(self):
+        return self.__repr__()
+
+class UnknownMethodGetError(Exception):
+    """Object does not have Get, most probably being invalid"""
     def __str__(self):
         return self.__repr__()

@@ -86,6 +91,8 @@ def _get_property(object_path, prop, interface_name_suffix=""):
     except GLib.GError as e:
         if "org.freedesktop.DBus.Error.AccessDenied" in e.message:
             return None
+        elif "org.freedesktop.DBus.Error.UnknownMethod" in e.message:
+            raise UnknownMethodGetError
         else:
             raise

@@ -305,7 +312,12 @@ def nm_device_ip_config(name, version=4):
     if config == "/":
         return []

-    addresses = _get_property(config, "Addresses", dbus_iface)
+    try:
+        addresses = _get_property(config, "Addresses", dbus_iface)
+    # object is valid only if device is in ACTIVATED state (racy)
+    except UnknownMethodGetError:
+        return []
+
     addr_list = []
     for addr, prefix, gateway in addresses:
         # TODO - look for a library function (could have used IPy but byte order!)
@@ -317,7 +329,12 @@ def nm_device_ip_config(name, version=4):
             gateway_str = nm_dbus_ay_to_ipv6(gateway)
         addr_list.append([addr_str, prefix, gateway_str])

-    nameservers = _get_property(config, "Nameservers", dbus_iface)
+    try:
+        nameservers = _get_property(config, "Nameservers", dbus_iface)
+    # object is valid only if device is in ACTIVATED state (racy)
+    except UnknownMethodGetError:
+        return []
+
     ns_list = []
     for ns in nameservers:
         # TODO - look for a library function
@@ -341,7 +358,11 @@ def nm_ntp_servers_from_dhcp():
     for device in active_devices:
         # harvest NTP server addresses from DHCPv4
         dhcp4_path = nm_device_property(device, "Dhcp4Config")
-        options = _get_property(dhcp4_path, "Options", ".DHCP4Config")
+        try:
+            options = _get_property(dhcp4_path, "Options", ".DHCP4Config")
+        # object is valid only if device is in ACTIVATED state (racy)
+        except UnknownMethodGetError:
+            options = None
         if options and 'ntp_servers' in options:
             # NTP server addresses returned by DHCP are whitespace delimited
             ntp_servers_string = options["ntp_servers"]

[Vratislav Podzimek]

On Tue, 2013-09-10 at 14:57 +0200, Radek Vykydal wrote:
> Fedora bz: #980576
>
> Catch the infamous
>
> DBusException: org.freedesktop.DBus.Error.UnknownMethod:
> Method "Get" with signature "ss" on interface "org.freedesktop.DBus.Properties"
> doesn't exist
>
> exception.
>
> Object with path from devices's IPXConfig property is valid only if
> its device is in ACTIVATED state.
>
> pyanaconda/nm.py | 29 +++++++++++++++++++++++++----
>  1 file changed, 25 insertions(+), 4 deletions(-)
>
> diff --git a/pyanaconda/nm.py b/pyanaconda/nm.py
> index dd0df99..0c88800 100644
> --- a/pyanaconda/nm.py
> +++ b/pyanaconda/nm.py
> @@ -53,7 +53,12 @@ class SettingNotFoundError(ValueError):
>          return self.__repr__()
>
> class DeviceSettingsNotFoundError(ValueError):
> """Settings (NMRemoteConnection object was not found"""
> """Settings NMRemoteConnection object was not found"""
> def __str__(self):
>    return self.__repr__()
>
> +class UnknownMethodGetError(Exception):
> """Object does not have Get, most probably being invalid"""
> def __str__(self):
>     return self.__repr__()
>
> @@ -86,6 +91,8 @@ def _get_property(object_path, prop, interface_name_suffix=""):
>      except GLib.GError as e:
>          if "org.freedesktop.DBus.Error.AccessDenied" in e.message:
>              return None
>    elif "org.freedesktop.DBus.Error.UnknownMethod" in e.message:
>        raise UnknownMethodGetError
>    else:
>        raise
>
> @@ -305,7 +312,12 @@ def nm_device_ip_config(name, version=4):
>      if config == "/":
>          return []
> addresses = _get_property(config, "Addresses", dbus_iface)
> try:
>    addresses = _get_property(config, "Addresses", dbus_iface)
> # object is valid only if device is in ACTIVATED state (racy)
> except UnknownMethodGetError:
>    return []
> addr_list = []
>    for addr, prefix, gateway in addresses:
>        # TODO - look for a library function (could have used IPy but byte order!)
>
> @@ -317,7 +329,12 @@ def nm_device_ip_config(name, version=4):
>              gateway_str = nm_dbus_ay_to_ipv6(gateway)
>          addr_list.append([addr_str, prefix, gateway_str])
> nameservers = _get_property(config, "Nameservers", dbus_iface)
> try:
>    nameservers = _get_property(config, "Nameservers", dbus_iface)
> # object is valid only if device is in ACTIVATED state (racy)
> except UnknownMethodGetError:
>    return []
> ns_list = []
>    for ns in nameservers:
>        # TODO - look for a library function
>
> @@ -341,7 +358,11 @@ def nm_ntp_servers_from_dhcp():
>      for device in active_devices:
>          # harvest NTP server addresses from DHCPv4
>          dhcp4_path = nm_device_property(device, "Dhcp4Config")
>    options = _get_property(dhcp4_path, "Options", ".DHCP4Config")
>    try:
>        options = _get_property(dhcp4_path, "Options", ".DHCP4Config")
>    # object is valid only if device is in ACTIVATED state (racy)
>    except UnknownMethodGetError:
>        options = None
>    if options and 'ntp_servers' in options:
>        # NTP server addresses returned by DHCP are whitespace delimited
>        ntp_servers_string = options["ntp_servers"]

This looks good to me.

[Chris Lumens]

> Fedora bz: #980576
>
> Catch the infamous
>
> DBusException: org.freedesktop.DBus.Error.UnknownMethod:
> Method "Get" with signature "ss" on interface "org.freedesktop.DBus.Properties"
> doesn't exist
>
> exception.

I will be very happy to see this one go away.  Nice work.

- Chris