--- /dev/null
+NOTE: the sudo auth API is subject to change
+
+Purpose: to provide a simple API for authentication methods that
+ encapsulates things nicely without turning into a maze
+ of #ifdef's
+
+The sudo_auth struct looks like this:
+
+typedef struct sudo_auth {
+ int need_root; /* must run as root? */
+ int configured; /* auth type configured on this host? */
+ int status; /* status from verify routine */
+ char *name; /* name of the method in string form */
+ void *data; /* method-specific data pointer */
+
+ int (*init) __P((struct passwd *pw, char **prompt, void **data));
+ int (*setup) __P((struct passwd *pw, char **prompt, void **data));
+ int (*verify) __P((struct passwd *pw, char *p, void **data));
+ int (*cleanup) __P((struct passwd *pw, int status, void **data));
+} sudo_auth;
+
+The variables in the struct are as follows:
+ need_root Boolean flag that determines whether or not the auth functions
+ run with an euid of 0 or the uid of the invoking user.
+
+ configured Boolean flag that is true if the auth method has
+ been configured and false if not. All auth methods
+ start out with this set to true. If an "init" or "setup"
+ functions fails, "configured" is set to false.
+
+ status Contains the return value from the last run of
+ the "verify" function. Starts out as AUTH_FAILURE.
+
+ name The name of the authentication method as a C string.
+
+ data A pointer to method-specific data. This is passed to
+ all the functions of an auth method and is usually
+ initialized in the "init" or "setup" routines.
+
+The member functions can return the following values:
+ AUTH_SUCCESS Function succeeded. For a ``verify'' function
+ this means the user correctly authenticated.
+
+ AUTH_FAILURE Function failed. If this is an ``init'' or
+ ``setup'' routine, the auth method will be
+ marked as !configured.
+
+ AUTH_FATAL A fatal error occurred. The routine should have
+ written an error message to stderr and optionally
+ sent mail to the administrator. (If log_error()
+ is called to do this, the NO_EXIT flag must be used.)
+ When verify_user() gets AUTH_FATAL from an auth
+ function it does an exit(1).
+
+The functions in the struct are as follows:
+
+ int init(struct passwd *pw, char **prompt, void **data)
+ Function to do any one-time initialization for the auth
+ method. All of the "init" functions are run before anything
+ else. A pointer to the prompt string may be used to add
+ method-specific info to the prompt.
+
+ int setup(struct passwd *pw, char **prompt, void **data)
+ Function to do method-specific setup. All the "setup"
+ routines are run before any of the "verify" routines. A
+ pointer to the prompt string may be used to add method-specific
+ info to the prompt.
+
+ int verify(struct passwd *pw, char *p, void **data)
+ Function to do user verification for this auth method. For
+ standalone auth methods ``p'' is the prompt string. For
+ normal auth methods, ``p'' is the password the user entered.
+ Note that standalone auth methods are responsible for
+ rerading the password themselves.
+
+ int cleanup(struct passwd *pw, int status, void **data)
+ Function to do per-auth method cleanup. This is only run
+ at the end of the authentication process, after the user
+ has completely failed or succeeded to authenticate.
+ The ``status'' variable contains the result of the last
+ authentication attempt.
+
+A note about standalone methods. Some authentication methods can't
+coexist with anyh others. This may be because they encapsulate other
+methods (pam, sia) or because they have a special way of interacting
+with the user (securid).
+
+Adding a new authentication method:
+
+Each method should live in its own file. Add prototypes for the functions
+in sudo_auth.h.
+
+If this is a standalone method, add it to the standalone #if cascade
+in sudo_auth.h. For instance, for a method, ``fooauth'', add:
+
+#elif defined(HAVE_FOOAUTH)
+# define AUTH_STANDALONE \
+ AUTH_ENTRY(1, "foo", foo_init, foo_setup, foo_verify, foo_cleanup)
+
+If you don't have a init/setup/cleanup routine, just use a NULL for that
+field.
+
+For a normal authentication method, add it to the ``auth_switch'' in
+sudo_auth.c. If ``fooauth'' is a normal auth method, its entry
+would look like:
+
+# ifdef HAVE_FOOAUTH
+ AUTH_ENTRY(1, "foo", foo_init, foo_setup, foo_verify, foo_cleanup)
+# endif
+
+Again, if you don't have a init/setup/cleanup routine, just use a NULL
+for that field.
+
+NOTE: in general, you should not make a method both ``standalone'' and
+ ``normal'' unless you *really* know what you are doing. See
+ the ``rfc1938'' method for an example of how to do this.
+ In most cases, you are better off using the --without-passwd
+ configure argument.