Re: [PATCH 4/7] Network password has exactly 4 digits.

> +static inline int is_valid_password(const char *pass) > +{ > +     return is_valid_pin(pass) && strlen(pass) == 4; > +}

So I suggest not doing it this way, instead let us modify is_valid_pin to take an additional argument, namely whether this is a pin/puk and check the length of the password there.  You might want to include a reference to 22.004 Section 5.2 that says the pin/pin2 is 0000 to 9999 and exactly 4 digits.