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


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