[Asterisk-Dev] Pluggable authentication for assorted channels

[James Sharp]

I'd like people's input on this (better ideas are encouraged!)

I've got a client who wants LDAP authentication added to chan_sip.  I was
poking at it for a while, then decided "Hey, why not just add an
abstraction layer for authentication that could be used for any other
authentication?".

So I mulled over it a bit and came up with this:

Add a built-in to * for all of this...call it ast_pam_auth for lack of a
better name.  You call it with a variable set of arguments which details
your request from the PAM system.  The prototype looks something like
this:

int ast_pam_auth(char *source, int numargpairs, ...) where the variable
argument list are pairs of "title" and a pointer for the return.  Example:

char *username
char *password
<mallocing & whatever is in here>
foo = ast_pam_auth("chan_sip",2,"Username",username,"Password",password).

The PAM subsystem then looks and sees that chan_sip is configured to use
pam_ldap (which was registered into the system on load, much like
applications & cdrs).  pam_ldap registered to use pam_ldap_query(...) and
all the pointers that ast_pam_auth got passed get passed to
pam_ldap_query, which runs its query, fills in the pointers with
information, and returns/returns back to the channel.

The channel can then do whatever it needs to with the data that
ast_pam_auth has gotten for it.