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       libauth - routines for writing nnrpd resolvers and authenticators


           #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*);


       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
       authenticators 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

       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.


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

       At present, libauth.h and its implementation are located in authprogs/;
       perhaps they should be moved to include/ and lib/, respectively?


       Written by Jeffrey M. Vinocur <> for InterNetNews.

       $Id: libauth.pod 8200 2008-11-30 13:31:30Z iulius $


       nnrpd(8), readers.conf(5), doc/external-auth