;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2013, 2014, 2015 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2015 Mark H Weaver <mhw@netris.org>
;;;
;;; This file is part of GNU Guix.
;;;
;;; GNU Guix is free software; you can redistribute it and/or modify it
;;; under the terms of the GNU General Public License as published by
;;; the Free Software Foundation; either version 3 of the License, or (at
;;; your option) any later version.
;;;
;;; GNU Guix is distributed in the hope that it will be useful, but
;;; WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;;; GNU General Public License for more details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.

(define-module (gnu services networking)
  #:use-module (gnu services)
  #:use-module (gnu system shadow)
  #:use-module (gnu packages admin)
  #:use-module (gnu packages linux)
  #:use-module (gnu packages tor)
  #:use-module (gnu packages messaging)
  #:use-module (gnu packages ntp)
  #:use-module (gnu packages wicd)
  #:use-module (guix gexp)
  #:use-module (guix store)
  #:use-module (guix monads)
  #:use-module (srfi srfi-26)
  #:export (%facebook-host-aliases
            static-networking-service
            dhcp-client-service
            %ntp-servers
            ntp-service
            tor-service
            bitlbee-service
            wicd-service))

;;; Commentary:
;;;
;;; Networking services.
;;;
;;; Code:

(define %facebook-host-aliases
  ;; This is the list of known Facebook hosts to be added to /etc/hosts if you
  ;; are to block it.
  "\
# Block Facebook IPv4.
127.0.0.1   www.facebook.com
127.0.0.1   facebook.com
127.0.0.1   login.facebook.com
127.0.0.1   www.login.facebook.com
127.0.0.1   fbcdn.net
127.0.0.1   www.fbcdn.net
127.0.0.1   fbcdn.com
127.0.0.1   www.fbcdn.com
127.0.0.1   static.ak.fbcdn.net
127.0.0.1   static.ak.connect.facebook.com
127.0.0.1   connect.facebook.net
127.0.0.1   www.connect.facebook.net
127.0.0.1   apps.facebook.com

# Block Facebook IPv6.
fe80::1%lo0 facebook.com
fe80::1%lo0 login.facebook.com
fe80::1%lo0 www.login.facebook.com
fe80::1%lo0 fbcdn.net
fe80::1%lo0 www.fbcdn.net
fe80::1%lo0 fbcdn.com
fe80::1%lo0 www.fbcdn.com
fe80::1%lo0 static.ak.fbcdn.net
fe80::1%lo0 static.ak.connect.facebook.com
fe80::1%lo0 connect.facebook.net
fe80::1%lo0 www.connect.facebook.net
fe80::1%lo0 apps.facebook.com\n")


(define* (static-networking-service interface ip
                                    #:key
                                    gateway
                                    (provision '(networking))
                                    (name-servers '())
                                    (net-tools net-tools))
  "Return a service that starts @var{interface} with address @var{ip}.  If
@var{gateway} is true, it must be a string specifying the default network
gateway."
  (define loopback?
    (memq 'loopback provision))

  ;; TODO: Eventually replace 'route' with bindings for the appropriate
  ;; ioctls.
  (with-monad %store-monad
    (return
     (service

      ;; Unless we're providing the loopback interface, wait for udev to be up
      ;; and running so that INTERFACE is actually usable.
      (requirement (if loopback? '() '(udev)))

      (documentation
       "Bring up the networking interface using a static IP address.")
      (provision provision)
      (start #~(lambda _
                 ;; Return #t if successfully started.
                 (let* ((addr     (inet-pton AF_INET #$ip))
                        (sockaddr (make-socket-address AF_INET addr 0)))
                   (configure-network-interface #$interface sockaddr
                                                (logior IFF_UP
                                                        #$(if loopback?
                                                              #~IFF_LOOPBACK
                                                              0))))
                 #$(if gateway
                       #~(zero? (system* (string-append #$net-tools
                                                        "/sbin/route")
                                         "add" "-net" "default"
                                         "gw" #$gateway))
                       #t)
                 #$(if (pair? name-servers)
                       #~(call-with-output-file "/etc/resolv.conf"
                           (lambda (port)
                             (display
                              "# Generated by 'static-networking-service'.\n"
                              port)
                             (for-each (lambda (server)
                                         (format port "nameserver ~a~%"
                                                 server))
                                       '#$name-servers)))
                       #t)))
      (stop #~(lambda _
                ;; Return #f is successfully stopped.
                (let ((sock (socket AF_INET SOCK_STREAM 0)))
                  (set-network-interface-flags sock #$interface 0)
                  (close-port sock))
                (not #$(if gateway
                           #~(system* (string-append #$net-tools
                                                     "/sbin/route")
                                      "del" "-net" "default")
                           #t))))
      (respawn? #f)))))

(define* (dhcp-client-service #:key (dhcp isc-dhcp))
  "Return a service that runs @var{dhcp}, a Dynamic Host Configuration
Protocol (DHCP) client, on all the non-loopback network interfaces."

  (define dhclient
    #~(string-append #$dhcp "/sbin/dhclient"))

  (define pid-file
    "/var/run/dhclient.pid")

  (with-monad %store-monad
    (return (service
             (documentation "Set up networking via DHCP.")
             (requirement '(user-processes udev))

             ;; XXX: Running with '-nw' ("no wait") avoids blocking for a
             ;; minute when networking is unavailable, but also means that the
             ;; interface is not up yet when 'start' completes.  To wait for
             ;; the interface to be ready, one should instead monitor udev
             ;; events.
             (provision '(networking))

             (start #~(lambda _
                        (false-if-exception (delete-file #$pid-file))

                        ;; When invoked without any arguments, 'dhclient'
                        ;; discovers all non-loopback interfaces *that are
                        ;; up*.  However, the relevant interfaces are
                        ;; typically down at this point.  Thus we perform our
                        ;; own interface discovery here.
                        (let* ((valid? (negate loopback-network-interface?))
                               (ifaces (filter valid?
                                               (all-network-interfaces)))
                               (pid    (fork+exec-command
                                        (cons* #$dhclient "-nw"
                                               "-pf" #$pid-file
                                               ifaces))))
                          (and (zero? (cdr (waitpid pid)))
                               (let loop ()
                                 (catch 'system-error
                                   (lambda ()
                                     (call-with-input-file #$pid-file read))
                                   (lambda args
                                     ;; 'dhclient' returned before PID-FILE
                                     ;; was created, so try again.
                                     (let ((errno (system-error-errno args)))
                                       (if (= ENOENT errno)
                                           (begin
                                             (sleep 1)
                                             (loop))
                                           (apply throw args))))))))))
             (stop #~(make-kill-destructor))))))

(define %ntp-servers
  ;; Default set of NTP servers.
  '("0.pool.ntp.org"
    "1.pool.ntp.org"
    "2.pool.ntp.org"))

(define* (ntp-service #:key (ntp ntp)
                      (servers %ntp-servers))
  "Return a service that runs the daemon from @var{ntp}, the
@uref{http://www.ntp.org, Network Time Protocol package}.  The daemon will
keep the system clock synchronized with that of @var{servers}."
  ;; TODO: Add authentication support.

  (define config
    (string-append "driftfile /var/run/ntp.drift\n"
                   (string-join (map (cut string-append "server " <>)
                                     servers)
                                "\n")
                   "
# Disable status queries as a workaround for CVE-2013-5211:
# <http://support.ntp.org/bin/view/Main/SecurityNotice#DRDoS_Amplification_Attack_using>.
restrict default kod nomodify notrap nopeer noquery
restrict -6 default kod nomodify notrap nopeer noquery

# Yet, allow use of the local 'ntpq'.
restrict 127.0.0.1
restrict -6 ::1\n"))

  (mlet %store-monad ((ntpd.conf (text-file "ntpd.conf" config)))
    (return
     (service
      (provision '(ntpd))
      (documentation "Run the Network Time Protocol (NTP) daemon.")
      (requirement '(user-processes networking))
      (start #~(make-forkexec-constructor
                (list (string-append #$ntp "/bin/ntpd") "-n"
                      "-c" #$ntpd.conf
                      "-u" "ntpd")))
      (stop #~(make-kill-destructor))
      (user-accounts (list (user-account
                            (name "ntpd")
                            (group "nogroup")
                            (system? #t)
                            (comment "NTP daemon user")
                            (home-directory "/var/empty")
                            (shell
                             #~(string-append #$shadow "/sbin/nologin")))))))))

(define* (tor-service #:key (tor tor))
  "Return a service to run the @uref{https://torproject.org,Tor} daemon.

The daemon runs with the default settings (in particular the default exit
policy) as the @code{tor} unprivileged user."
  (mlet %store-monad ((torrc (text-file "torrc" "User tor\n")))
    (return
     (service
      (provision '(tor))

      ;; Tor needs at least one network interface to be up, hence the
      ;; dependency on 'loopback'.
      (requirement '(user-processes loopback))

      (start #~(make-forkexec-constructor
                (list (string-append #$tor "/bin/tor") "-f" #$torrc)))
      (stop #~(make-kill-destructor))

      (user-groups   (list (user-group
                            (name "tor")
                            (system? #t))))
      (user-accounts (list (user-account
                            (name "tor")
                            (group "tor")
                            (system? #t)
                            (comment "Tor daemon user")
                            (home-directory "/var/empty")
                            (shell
                             #~(string-append #$shadow "/sbin/nologin")))))

      (documentation "Run the Tor anonymous network overlay.")))))

(define* (bitlbee-service #:key (bitlbee bitlbee)
                          (interface "127.0.0.1") (port 6667)
                          (extra-settings ""))
  "Return a service that runs @url{http://bitlbee.org,BitlBee}, a daemon that
acts as a gateway between IRC and chat networks.

The daemon will listen to the interface corresponding to the IP address
specified in @var{interface}, on @var{port}.  @code{127.0.0.1} means that only
local clients can connect, whereas @code{0.0.0.0} means that connections can
come from any networking interface.

In addition, @var{extra-settings} specifies a string to append to the
configuration file."
  (mlet %store-monad ((conf (text-file "bitlbee.conf"
                                       (string-append "
  [settings]
  User = bitlbee
  ConfigDir = /var/lib/bitlbee
  DaemonInterface = " interface "
  DaemonPort = " (number->string port) "
" extra-settings))))
    (return
     (service
      (provision '(bitlbee))
      (requirement '(user-processes loopback))
      (activate #~(begin
                    (use-modules (guix build utils))

                    ;; This directory is used to store OTR data.
                    (mkdir-p "/var/lib/bitlbee")
                    (let ((user (getpwnam "bitlbee")))
                      (chown "/var/lib/bitlbee"
                             (passwd:uid user) (passwd:gid user)))))
      (start #~(make-forkexec-constructor
                (list (string-append #$bitlbee "/sbin/bitlbee")
                      "-n" "-F" "-u" "bitlbee" "-c" #$conf)))
      (stop  #~(make-kill-destructor))
      (user-groups   (list (user-group (name "bitlbee") (system? #t))))
      (user-accounts (list (user-account
                            (name "bitlbee")
                            (group "bitlbee")
                            (system? #t)
                            (comment "BitlBee daemon user")
                            (home-directory "/var/empty")
                            (shell #~(string-append #$shadow
                                                    "/sbin/nologin")))))))))

(define* (wicd-service #:key (wicd wicd))
  "Return a service that runs @url{https://launchpad.net/wicd,Wicd}, a network
manager that aims to simplify wired and wireless networking."
  (with-monad %store-monad
    (return
     (service
      (documentation "Run the Wicd network manager.")
      (provision '(networking))
      (requirement '(user-processes dbus-system loopback))
      (start #~(make-forkexec-constructor
                (list (string-append #$wicd "/sbin/wicd")
                      "--no-daemon")))
      (stop #~(make-kill-destructor))
      (activate
       #~(begin
           (use-modules (guix build utils))
           (mkdir-p "/etc/wicd")
           (let ((file-name "/etc/wicd/dhclient.conf.template.default"))
             (unless (file-exists? file-name)
               (copy-file (string-append #$wicd file-name)
                          file-name)))))))))

;;; networking.scm ends here
