NAME

       oath_authenticate_usersfile - API function

SYNOPSIS

       #include <oath.h>

       int  oath_authenticate_usersfile(const char * usersfile, const char * username, const char
       * otp, size_t window, const char * passwd, time_t * last_otp);

ARGUMENTS

       const char * usersfile
                   string with user credential filename, in UsersFile format

       const char * username
                   string with name of user

       const char * otp
                   string with one-time password to authenticate

       size_t window
                   how many past/future OTPs to search

       const char * passwd
                   string with password, or NULL to disable password checking

       time_t * last_otp
                   output variable holding last successful authentication

DESCRIPTION

       Authenticate user named username with the one-time password otp  and  (optional)  password
       passwd.  Credentials are read (and updated) from a text file named usersfile.

       Note  that  for TOTP the usersfile will only record the last OTP and use that to make sure
       more recent OTPs have not been seen yet when validating a new OTP.  That logics relies  on
       using the same search window for the same user.

RETURNS

       On  successful  validation,  OATH_OK  is returned.  If the supplied otp is the same as the
       last successfully authenticated one-time password, OATH_REPLAYED_OTP is returned  and  the
       timestamp of the last authentication is returned in last_otp.  If the one-time password is
       not found in the indicated search window, OATH_INVALID_OTP  is  returned.   Otherwise,  an
       error code is returned.

REPORTING BUGS

       Report     bugs     to     <oath-toolkit-help@nongnu.org>.      liboath     home     page:
       https://www.nongnu.org/oath-toolkit/     General     help     using     GNU      software:
       http://www.gnu.org/gethelp/

COPYRIGHT

       Copyright © 2009-2020 Simon Josefsson.
       Copying  and distribution of this file, with or without modification, are permitted in any
       medium without royalty provided the copyright notice and this notice are preserved.