SYNOPSIS

           #include "libauth.h"

           struct res_info {
               struct sockaddr *client;
               struct sockaddr *local;
               char *clienthostname;
           };

           struct auth_info {
               char *username;
               char *password;
           };

           struct auth_info *get_auth_info(FILE *);
           struct res_info  *get_res_info (FILE *);

           void free_auth_info(struct auth_info*);
           void free_res_info (struct res_info*);

DESCRIPTION

       These functions provide a convenient C frontend to the nnrpd external
       authentication interface documented in doc/external-auth.  Use of this
       library is not required; in particular, external resolvers and authen-
       ticators written in languages other than C will need to implement the
       necessary functionality themselves.

       The get_auth_info() and get_res_info() functions allocate sufficient
       memory for a struct auth_info or struct res_info and any necessary
       fields, and return a pointer to the struct with the fields filled in
       from information supplied by nnrpd (the FILE* parameter generally
       should be "stdin").  Both functions return NULL on error.  The caller
       is responsible for deallocating the memory by using the functions
       below.

       The string fields of both structs are straightforward.  The client and
       local fields of struct res_info actually point to instances of struct
       sockaddr_in (or struct sockaddr_in6 if IPv6 support is compiled in).

       The free_auth_info() and free_res_info() functions free the struct
       passed in as argument and all necessary fields.

BUGS

       In many cases, nnrpd provides more information than is normally useful
       (for example, even when calling an authenticator, the resolver informa-
       tion is often provided.)  On the other hand, in certain cases it pro-
       vides less information than might be expected (for example, if nnrpd is
       reading from stdin rather than a socket).  The implementation is capa-
       ble of handling at least the first of these issues, but that function-
       ality is not exposed in the interface.

       At present, libauth.h and its implementation are located in authprogs/;