gnu: services: Add openvpn options.

* gnu/services/vpn.scm (openvpn-client-configuration)
(openvpn-server-configuration): Add fast-io? and auth-user-pass options.

doc/guix.texi

@@ -21794,6 +21794,13 @@ Defaults to @samp{#t}.
 
 @end deftypevr
 
+@deftypevr {@code{openvpn-client-configuration} parameter} boolean fast-io?
+(Experimental) Optimize TUN/TAP/UDP I/O writes by avoiding a call to
+poll/epoll/select prior to the write operation.
+
+Defaults to @samp{#f}.
+@end deftypevr
+
 @deftypevr {@code{openvpn-client-configuration} parameter} number verbosity
 Verbosity level.
 
@@ -21809,6 +21816,14 @@ Defaults to @samp{#f}.
 
 @end deftypevr
 
+@deftypevr {@code{openvpn-client-configuration} parameter} maybe-string auth-user-pass
+Authenticate with server using username/password.  The option is a file
+containing username/password on 2 lines.  Do not use a file-like object as it
+would be added to the store and readable by any user.
+
+Defaults to @samp{'disabled}.
+@end deftypevr
+
 @deftypevr {@code{openvpn-client-configuration} parameter} key-usage verify-key-usage?
 Whether to check the server certificate has server usage extension.
 
@@ -21930,6 +21945,13 @@ Defaults to @samp{#t}.
 
 @end deftypevr
 
+@deftypevr {@code{openvpn-server-configuration} parameter} boolean fast-io?
+(Experimental) Optimize TUN/TAP/UDP I/O writes by avoiding a call to
+poll/epoll/select prior to the write operation.
+
+Defaults to @samp{#f}.
+@end deftypevr
+
 @deftypevr {@code{openvpn-server-configuration} parameter} number verbosity
 Verbosity level.
 

gnu/services/vpn.scm

@@ -59,6 +59,7 @@
       (format #t "")
       (format #t "~a ~a\n" (uglify-field-name field-name) val)))
 (define serialize-string serialize-field)
+(define-maybe string)
 (define (serialize-boolean field-name val)
   (if val
       (serialize-field field-name "")
@@ -298,6 +299,11 @@ certificate is @code{cert}.")
     "Don't close and reopen TUN/TAP device or run up/down scripts across
 SIGUSR1 or --ping-restart restarts.")
 
+   (fast-io?
+     (boolean #f)
+     "(Experimental) Optimize TUN/TAP/UDP I/O writes by avoiding a call to
+poll/epoll/select prior to the write operation.")
+
    (verbosity
     (number 3)
     "Verbosity level."))
@@ -307,6 +313,12 @@ SIGUSR1 or --ping-restart restarts.")
     "Add an additional layer of HMAC authentication on top of the TLS control
 channel to protect against DoS attacks.")
 
+   (auth-user-pass
+     (maybe-string 'disabled)
+     "Authenticate with server using username/password.  The option is a file
+containing username/password on 2 lines.  Do not use a file-like object as it
+would be added to the store and readable by any user.")
+
    (verify-key-usage?
     (key-usage #t)
     "Whether to check the server certificate has server usage extension.")