Server location interface (locate)

The locate interface allows modules to control how KDCs and similar services are located by clients. For a detailed description of the ccselect interface, see the header file <krb5/locate_plugin.h>.

A locate module exports a structure object of type krb5plugin_service_locate_ftable, with the name service_locator. The structure contains a minor version and pointers to the module’s methods.

The primary locate method is lookup, which accepts a service type, realm name, desired socket type, and desired address family (which will be AF_UNSPEC if no specific address family is desired). The method should invoke the callback function once for each server address it wants to return, passing a socket type (SOCK_STREAM for TCP or SOCK_DGRAM for UDP) and socket address. The lookup method should return 0 if it has authoritatively determined the server addresses for the realm, KRB5_PLUGIN_NO_HANDLE if it wants to let other location mechanisms determine the server addresses, or another code if it experienced a failure which should abort the location process.

A module can create and destroy per-library-context state objects by implementing the init and fini methods. State objects have the type void *, and should be cast to an internal type for the state object.