Newbie app-writing question

[Nathan Yocom]

> amount of examples and references I've found [1], I *think* I need to write a
> new conversation function and pass that to pam_start(), but I haven't figured
> out the propper syntax to do that [2].

Correct.. kind of.

> int static_conv(int n, const struct pam_message **msg,
>             struct pam_response **resp, void *data)

the void * here is for your "custom" data.  I usually define a structure 
like:

// The structure used to pass a username and password to pam
typedef struct auth_struct
{
   // Username to authenticate
   const char *username;
   // Password to use
   const char *password;
} auth_struct;

Then setup a conversation structure for PAM:

static struct pam_conv myauthconv = {
     auth_conv,	// conversation function 

     NULL
   };

And finally, fill in and provide the auth structure:

struct auth_struct buffer;
buffer.username = username;
buffer.password = password;
myauthconv.appdata_ptr = &buffer;   // This is the meat of the idea here 
- we need to tell PAM to pass our structure as the 'user defined data' 
in the last argument of our conversation function

Now when your conv callback gets hit, pam will pass it the appdata_ptr 
as the last argument and you can cast it back to a structure and get 
whatever info you needed out of it.

Hope that helps!
Nate Yocom

Also - Note that I have written an entire section on writing  PAM aware 
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