Function openthread_sys::otSrpClientEnableAutoStartMode

source · 
pub unsafe extern "C" fn otSrpClientEnableAutoStartMode(
    aInstance: *mut otInstance,
    aCallback: otSrpClientAutoStartCallback,
    aContext: *mut c_void
)
Expand description

Enables the auto-start mode.

This is only available when auto-start feature OPENTHREAD_CONFIG_SRP_CLIENT_AUTO_START_API_ENABLE is enabled.

Config option OPENTHREAD_CONFIG_SRP_CLIENT_AUTO_START_DEFAULT_MODE specifies the default auto-start mode (whether it is enabled or disabled at the start of OT stack).

When auto-start is enabled, the SRP client will monitor the Thread Network Data to discover SRP servers and select the preferred server and automatically start and stop the client when an SRP server is detected.

There are three categories of Network Data entries indicating presence of SRP sever. They are preferred in the following order:

  1. Preferred unicast entries where server address is included in the service data. If there are multiple options, the one with numerically lowest IPv6 address is preferred.

  2. Anycast entries each having a seq number. A larger sequence number in the sense specified by Serial Number Arithmetic logic in RFC-1982 is considered more recent and therefore preferred. The largest seq number using serial number arithmetic is preferred if it is well-defined (i.e., the seq number is larger than all other seq numbers). If it is not well-defined, then the numerically largest seq number is preferred.

  3. Unicast entries where the server address info is included in server data. If there are multiple options, the one with numerically lowest IPv6 address is preferred.

When there is a change in the Network Data entries, client will check that the currently selected server is still present in the Network Data and is still the preferred one. Otherwise the client will switch to the new preferred server or stop if there is none.

When the SRP client is explicitly started through a successful call to otSrpClientStart(), the given SRP server address in otSrpClientStart() will continue to be used regardless of the state of auto-start mode and whether the same SRP server address is discovered or not in the Thread Network Data. In this case, only an explicit otSrpClientStop() call will stop the client.

@param[in] aInstance A pointer to the OpenThread instance. @param[in] aCallback A callback to notify when client is auto-started/stopped. Can be NULL if not needed. @param[in] aContext A context to be passed when invoking @p aCallback.