PMK derivation in Host AP

[Manoj Verma, Noida]

Hi,

I was trying to find out the exact place in the Host-AP code for the
derivation of PMK (256 bit) from the master secret key.

I found that:

In function eap_ttls_process (), the master secret is passed as a parameter
to eap_tls_derive_key(), which internally user eap_prf() function, to get
the another key. 

My confusion is, the key above obtained is of length EAP_TLS_KEY_LEN i.e.
64, then where exactly the 256 bit PMK is derived in the code.

Thanks.