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The kernel tells the address lifetimes in the 'struct ifa_cacheinfo' attribute. This contains two timestamps (cstamp and tstamp) and two relative lifetimes (ifa_prefered and ifa_valid). The timestamps are equal to clock_gettime(CLOCK_MONOTONIC) scale in 1/100th of a second (wrapping every 497 days). The preferred/valid times are re-adjusted everytime when sending the message and count down as the time goes by. In other words, they are anchored relatively to the moment of when kernel creates the netlink message. As platform is caching the rtnl_addr object, the information of *when* the lifetimes started counting is not available. This patch fixes reading these values by hacking the libnl object when it gets received, so that valid and preferred are instead absolute expiration timestamps in scale nm_utils_get_monotonic_timestamp_s() -- which NM internally is used for address timestamps. There are two minor downsides to this hack: - the valid and preferred properties of a cached rtnl_addr object have an unexpected meaning, i.e. they are absolute and in a different time scale. - later when converting rtnl_addr to NMPlatformIPAddress, the base timestamp is set to "1", i.e. an NMPlatformIPAddress has no knowledge of when the address was created or last modified. The timestamp property of NMPlatformIPAddress is solely there to anchor the relative timestamps lifetime and preferred. Do not use it for anything else. Another reason the timestamp property is meaningless is that its scale nm_utils_get_monotonic_timestamp_s() starts counting at process start. So addresses that existed before would have a negative or zero timestamp, which we avoid. This in turn could be solved by either allowing negative timestamps or by shifting nm_utils_get_monotonic_timestamp_*(). Both is viable, but not necessary (ATM), because the age of an address has no other apparent use then to anchor the relative timestamps. Another implication is, that we potentially could get rid of the timestamp completely, and insteat make preferred and lifetime be absolute expiries. This will be fixed properly later, by not caching libnl objects but instead native NMPlatform objects. For those we have full control over their properties. https://bugzilla.gnome.org/show_bug.cgi?id=727382 Signed-off-by: Thomas Haller <thaller@redhat.com> |
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****************** 2008-12-11: NetworkManager core daemon has moved to git.freedesktop.org! git clone git://git.freedesktop.org/git/NetworkManager/NetworkManager.git ****************** Networking that Just Works -------------------------- NetworkManager attempts to keep an active network connection available at all times. The point of NetworkManager is to make networking configuration and setup as painless and automatic as possible. NetworkManager is intended to replace default route, replace other routes, set IP addresses, and in general configure networking as NM sees fit (with the possibility of manual override as necessary). In effect, the goal of NetworkManager is to make networking Just Work with a minimum of user hassle, but still allow customization and a high level of manual network control. If you have special needs, we'd like to hear about them, but understand that NetworkManager is not intended for every use-case. NetworkManager will attempt to keep every network device in the system up and active, as long as the device is available for use (has a cable plugged in, the killswitch isn't turned on, etc). Network connections can be set to 'autoconnect', meaning that NetworkManager will make that connection active whenever it and the hardware is available. "Settings services" store lists of user- or administrator-defined "connections", which contain all the settings and parameters required to connect to a specific network. NetworkManager will _never_ activate a connection that is not in this list, or that the user has not directed NetworkManager to connect to. How it works: The NetworkManager daemon runs as a privileged service (since it must access and control hardware), but provides a D-Bus interface on the system bus to allow for fine-grained control of networking. NetworkManager does not store connections or settings, it is only the mechanism by which those connections are selected and activated. To store pre-defined network connections, two separate services, the "system settings service" and the "user settings service" store connection information and provide these to NetworkManager, also via D-Bus. Each settings service can determine how and where it persistently stores the connection information; for example, the GNOME applet stores its configuration in GConf, and the system settings service stores it's config in distro-specific formats, or in a distro- agnostic format, depending on user/administrator preference. A variety of other system services are used by NetworkManager to provide network functionality: wpa_supplicant for wireless connections and 802.1x wired connections, pppd for PPP and mobile broadband connections, DHCP clients for dynamic IP addressing, dnsmasq for proxy nameserver and DHCP server functionality for internet connection sharing, and avahi-autoipd for IPv4 link-local addresses. Most communication with these daemons occurs, again, via D-Bus. Why doesn't my network Just Work? Driver problems are the #1 cause of why NetworkManager sometimes fails to connect to wireless networks. Often, the driver simply doesn't behave in a consistent manner, or is just plain buggy. NetworkManager supports _only_ those drivers that are shipped with the upstream Linux kernel, because only those drivers can be easily fixed and debugged. ndiswrapper, vendor binary drivers, or other out-of-tree drivers may or may not work well with NetworkManager, precisely because they have not been vetted and improved by the open-source community, and because problems in these drivers usually cannot be fixed. Sometimes, command-line tools like 'iwconfig' will work, but NetworkManager will fail. This is again often due to buggy drivers, because these drivers simply aren't expecting the dynamic requests that NetworkManager and wpa_supplicant make. Driver bugs should be filed in the bug tracker of the distribution being run, since often distributions customize their kernel and drivers. Sometimes, it really is NetworkManager's fault. If you think that's the case, please file a bug at http://bugzilla.gnome.org and choose the NetworkManager component. Attaching the output of /var/log/messages or /var/log/daemon.log (wherever your distribution directs syslog's 'daemon' facility output) is often very helpful, and (if you can get) a working wpa_supplicant config file helps enormously.