From 4a6d93dc2c9744a0b61a78cc28558517b3750b4a Mon Sep 17 00:00:00 2001
From: Daniel Barlow <dan@telent.net>
Date: Sat, 11 May 2024 22:48:06 +0100
Subject: [PATCH] add rudimentary l2tp service module

---
 examples/l2tp.nix       | 83 +++++++++++++++++++++++++++++++++++++++++
 modules/ppp/default.nix | 15 ++++++++
 modules/ppp/l2tp.nix    | 63 +++++++++++++++++++++++++++++++
 3 files changed, 161 insertions(+)
 create mode 100644 examples/l2tp.nix
 create mode 100644 modules/ppp/l2tp.nix

diff --git a/examples/l2tp.nix b/examples/l2tp.nix
new file mode 100644
index 0000000..d604881
--- /dev/null
+++ b/examples/l2tp.nix
@@ -0,0 +1,83 @@
+{
+  config,
+  pkgs,
+  lib,
+  ...
+}: let
+  secrets = import ./extneder-secrets.nix;
+  rsecrets = import ./rotuer-secrets.nix;
+  inherit (pkgs.liminix.services) oneshot longrun bundle target;
+  inherit (pkgs.pseudofile) dir symlink;
+  inherit (pkgs) writeText dropbear ifwait serviceFns;
+  svc = config.system.service;
+in rec {
+  boot = {
+    tftp = {
+      serverip = "10.0.0.1";
+      ipaddr = "10.0.0.8";
+    };
+  };
+
+  imports = [
+#    ../modules/wlan.nix
+    ../modules/network
+    ../modules/vlan
+    ../modules/ssh
+    ../modules/usb.nix
+    ../modules/watchdog
+    ../modules/mount
+    ../modules/ppp
+  ];
+  hostname = "thing";
+
+  services.dhcpc =
+    let iface = config.hardware.networkInterfaces.lan;
+    in svc.network.dhcp.client.build {
+      interface = iface;
+      dependencies = [ config.services.hostname ];
+    };
+
+  services.sshd = svc.ssh.build { };
+
+  services.resolvconf = oneshot rec {
+    dependencies = [ services.dhcpc ];
+    name = "resolvconf";
+    up = ''
+      . ${serviceFns}
+      ( in_outputs ${name}
+      for i in $(output ${services.dhcpc} dns); do
+        echo "nameserver $i" > resolv.conf
+      done
+      )
+    '';
+  };
+  filesystem = dir {
+    etc = dir {
+      "resolv.conf" = symlink "${services.resolvconf}/.outputs/resolv.conf";
+    };
+    srv = dir {};
+  };
+
+  services.l2tp = svc.l2tp.build {
+    lns = "l2tp.aaisp.net.uk";
+    ppp-options = [
+      "debug" "+ipv6" "noauth"
+      "name" rsecrets.l2tp.name
+      "password" rsecrets.l2tp.password
+    ];
+    dependencies = [ services.defaultroute4 ];
+  };
+
+  services.defaultroute4 = svc.network.route.build {
+    via = "$(output ${services.dhcpc} router)";
+    target = "default";
+    dependencies = [services.dhcpc];
+  };
+
+  users.root = {
+    passwd = lib.mkForce secrets.root.passwd;
+    openssh.authorizedKeys.keys = secrets.root.keys;
+  };
+
+
+}
diff --git a/modules/ppp/default.nix b/modules/ppp/default.nix
index a0e716a..4806e54 100644
--- a/modules/ppp/default.nix
+++ b/modules/ppp/default.nix
@@ -17,6 +17,9 @@ in {
     system.service.pppoe = mkOption {
       type = liminix.lib.types.serviceDefn;
     };
+    system.service.l2tp = mkOption {
+      type = liminix.lib.types.serviceDefn;
+    };
   };
   config = {
     system.service.pppoe = pkgs.liminix.callService ./pppoe.nix {
@@ -29,6 +32,16 @@ in {
         description = "options supplied on ppp command line";
       };
     };
+    system.service.l2tp = pkgs.liminix.callService ./l2tp.nix {
+      lns = mkOption {
+        type = types.str;
+        description = "hostname or address of the L2TP network server";
+      };
+      ppp-options = mkOption {
+        type = types.listOf types.str;
+        description = "options supplied on ppp command line";
+      };
+    };
     kernel = {
       config = {
         PPP = "y";
@@ -36,6 +49,8 @@ in {
         PPP_DEFLATE = "y";
         PPP_ASYNC = "y";
         PPP_SYNC_TTY = "y";
+        PPPOL2TP = "y";
+        L2TP = "y";
       };
     };
   };
diff --git a/modules/ppp/l2tp.nix b/modules/ppp/l2tp.nix
new file mode 100644
index 0000000..361d032
--- /dev/null
+++ b/modules/ppp/l2tp.nix
@@ -0,0 +1,63 @@
+{
+  liminix
+, lib
+, ppp
+, pppoe
+, writeAshScript
+, writeText
+, serviceFns
+, xl2tpd
+} :
+{ lns, ppp-options }:
+let
+  inherit (liminix.services) longrun;
+  name = "${lns}.l2tp";
+  ip-up = writeAshScript "ip-up" {} ''
+    . ${serviceFns} 
+    (in_outputs ${name}
+     echo $1 > ifname
+     echo $2 > tty
+     echo $3 > speed
+     echo $4 > address
+     echo $5 > peer-address
+     echo $DNS1 > ns1
+     echo $DNS2 > ns2
+    )
+    echo >/proc/self/fd/10
+  '';
+  ip6-up = writeAshScript "ip6-up" {} ''
+    . ${serviceFns} 
+    (in_outputs ${name}
+     echo $4 > ipv6-address
+     echo $5 > ipv6-peer-address
+    )
+    echo >/proc/self/fd/10
+  '';
+  ppp-options' = ppp-options ++ [
+    "ip-up-script" ip-up
+    "ipv6-up-script" ip6-up
+    "ipparam" name
+    "nodetach"
+    "usepeerdns"
+    "logfd" "2"
+  ];
+  conf = writeText "xl2tpd.conf" ''
+    [lac upstream]
+    lns = ${lns}
+    require authentication = no
+    pppoptfile = ${writeText "ppp-options" ppp-options'}
+    autodial = yes
+    redial = yes
+  '';
+  control = "/run/xl2tpd/control-${name}";
+in
+longrun {
+  inherit name;
+  run = ''
+    . ${serviceFns} 
+    mkdir -p /run/xl2tpd
+    touch ${control}
+    ${xl2tpd}/bin/xl2tpd -D -p /run/xl2tpd/${name}.pid -c ${conf} -C ${control} 
+  '';
+  notification-fd = 10;
+}