README.md

@@ -17,34 +17,6 @@ of "limen", or "of the threshold". Your router stands at the threshold
 of your (online) home and everything you send to/receive from the
 outside word goes across it.
 
-### What about NixWRT?
-
-This is an in-progress rewrite of NixWRT, incorporating Lessons
-Learned. That said, as of today (September 2022) it is not yet
-anywhere _near_ feature parity.
-
-Liminix will eventually provide these differentiators over NixWRT:
-
-* a writable filesystem so that software updates or reconfiguration
-  (e.g. changing passwords) don't require taking the device offline to
-  reflash it.
-
-* more flexible service management with dependencies, to allow
-  configurations such as "route through PPPoE if it is healthy, with
-  fallback to LTE"
-
-* a spec for valid configuration options (a la NixOS module options)
-  to that we can detect errors at evaluation time instead of producing
-  a bad image.
-
-* a network-based mechanism for secrets management so that changes can
-  be pushed from a central location to several Liminix devices at once
-
-* send device metrics and logs to a monitoring/alerting/o11y
-  infrastructure
-
-Today though, it does approximately none of these things and certainly
-not on real hardware.
 
 ## Building
 

THOUGHTS.txt

@@ -69,16 +69,3 @@ Fri Sep 23 10:27:22 BST 2022
 * mcast=230.0.0.1:1234  : access (interconnect between router and isp)
 * mcast=230.0.0.1:1235  : lan
 * mcast=230.0.0.1:1236  : world (the internet)
-
-
-Sun Sep 25 20:56:28 BST 2022
-
-1) shutdown doesn't work as its using the busybox one not s6
-
-2) think we shouldn't have process-based services like dhcp, ppp
-implement "address provider interface" - instead have a separate
-service for interface address that depends on the service and uses its
-output
-
-* ppp is not like dhcp because dhcp finds addresses for an existing
-  interface but ppp makes a new one

default.nix

@@ -5,8 +5,7 @@ let
   overlay = import ./overlay.nix;
   nixpkgs = import <nixpkgs> ( device.system // {overlays = [overlay]; });
   config = (import ./merge-modules.nix) [
-    ./modules/base.nix
-    ({ lib, ... } : { config = { inherit (device) kernel; }; })
+    (import ./modules/base.nix { inherit device; })
     <liminix-config>
   ] nixpkgs.pkgs;
   finalConfig = config // {
@@ -16,7 +15,7 @@ let
     ;
   };
   squashfs = (import ./make-image.nix) nixpkgs finalConfig;
-  kernel = (import ./make-kernel.nix)  nixpkgs finalConfig.kernel.config;
+  kernel = (import ./make-kernel.nix)  nixpkgs finalConfig;
 in {
   outputs = {
     inherit squashfs kernel;
@@ -27,7 +26,4 @@ in {
       ln -s ${kernel.vmlinux} vmlinux
    '';
   };
-  # this is just here as a convenience, so that we can get a
-  # cross-compiling nix-shell for any package we're customizing
-  inherit (nixpkgs) pkgs;
 }

make-kernel.nix

@@ -24,6 +24,6 @@ in
 {
   vmlinux = callPackage ./make-vmlinux.nix {
     inherit tree;
-    inherit config;
+    inherit (config.kernel) config;# checkedConfig;
   };
 }

modules/base.nix

@@ -1,3 +1,4 @@
+{ device } :
 { lib, ...}:
 let inherit (lib) mkEnableOption mkOption types;
 in {
@@ -10,6 +11,7 @@ in {
     };
     kernel = mkOption {
       type = types.anything;
+      default = { inherit (device.kernel) config checkedConfig; };
     };
   };
 }

overlay.nix

@@ -3,8 +3,6 @@ final: prev: {
   s6-init-files = final.callPackage ./pkgs/s6-init-files {};
   strace = prev.strace.override { libunwind = null; };
   liminix = final.callPackage ./pkgs/liminix-tools {};
-  writeAshScript = final.callPackage ./pkgs/write-ash-script {};
-
   pppoe = prev.rpPPPoE.overrideAttrs (o: {
     # use newer rp-pppoe, it builds cleanly
     src = final.fetchFromGitHub {

pkgs/liminix-tools/builder.sh

@@ -11,7 +11,6 @@ test -n "$contents" && for d in $contents; do
     touch $out/${name}/contents.d/$d
 done
 test -n "$run" && (echo -e "#!$shell\n$run" > $out/${name}/run)
-test -n "${notificationFd}" && (echo ${notificationFd} > $out/${name}/notification-fd)
 test -n "$up" && (echo -e "#!$shell\n$up" > $out/${name}/up)
 test -n "$down" && (echo -e "#!$shell\n$down" > $out/${name}/down)
 for i in $out/${name}/{down,up,run} ; do test -f $i && chmod +x $i; done

pkgs/liminix-tools/default.nix

@@ -4,14 +4,12 @@
 , lib
 , busybox
 , callPackage
-, writeAshScript
 } :let
   inherit (builtins) concatStringsSep;
   longrun = {
     name
     , run
     , outputs ? []
-    , notification-fd ? null
     , dependencies ? []
   } @ args: stdenvNoCC.mkDerivation {
     name = "${name}.service";
@@ -20,7 +18,6 @@
     dependencies = builtins.map (d: d.name) dependencies;
     shell = "${busybox}/bin/sh";
     inherit run;
-    notificationFd = notification-fd;
     builder = ./builder.sh;
   };
   oneshot = {
@@ -40,9 +37,7 @@
     # store directories?
     buildInputs = dependencies;
     shell = "${busybox}/bin/sh";
-    # up and down for oneshots are pathnames not scripts
-    up = writeAshScript "${name}-up" {} up;
-    down = writeAshScript "${name}-down" {} down;
+    inherit up down;
     dependencies = builtins.map (d: d.name) dependencies;
     builder = ./builder.sh;
   };
@@ -71,14 +66,12 @@ in {
     } // {
       inherit device;
     };
-    address = interface: { family, prefixLength, address } @ args:
-      let inherit (builtins) toString;
-      in oneshot {
-        dependencies = [ interface ];
-        name = "${interface.device}.addr.${address}";
-        up = "ip address add ${address}/${toString prefixLength} dev ${interface.device} ";
-        down = "ip address del ${address}/${toString prefixLength} dev ${interface.device} ";
-      };
+    address = interface: { family, addr } @ args: oneshot {
+      dependencies = [ interface ];
+      name = "${interface.device}.addr.${addr}";
+      up = "ip address add ${addr} dev ${interface.device} ";
+      down = "ip address del ${addr} dev ${interface.device} ";
+    };
     udhcpc = callPackage ./networking/udhcpc.nix {};
     odhcpc = interface: { ... } @ args: longrun {
       name = "${interface.device}.odhcp";
@@ -88,6 +81,6 @@ in {
   };
   services = {
     inherit longrun oneshot bundle target;
-    output = service: name: "/run/service-state/${service.name}/${name}";
+    output = service: name: "/run/s6-rc/scandir/${service.name}/data/outputs/${name}";
   };
 }

pkgs/liminix-tools/networking/pppoe.nix

@@ -4,40 +4,45 @@
 , busybox
 , ppp
 , pppoe
-, writeAshScript
+, writeShellScript
 } :
 let
   inherit (liminix.services) longrun;
+  ip-up = writeShellScript "ip-up" ''
+action=$1
+env > /run/udhcp.values
+
+set_address() {
+    ip address replace $ip/$mask dev $interface
+    mkdir -p data/outputs
+    for i in lease mask ip router siaddr dns serverid subnet opt53 interface ; do
+        echo ''${!i} > data/outputs/$i
+    done
+}
+case $action in
+  deconfig)
+    ip address flush $interface
+    ip link set up dev $interface
+    ;;
+  bound)
+    # this doesn't actually replace, it adds a new address.
+    set_address
+    ;;
+  renew)
+    set_address
+    ;;
+  nak)
+    echo "received NAK on $interface"
+    ;;
+esac
+'';
+
 in
 interface: {
   synchronous ? false
 , ppp-options ? []
 , ...
-} @ args:
-let
-  name = "${interface.device}.pppoe";
-  ip-up = writeAshScript "ip-up" {} ''
-    outputs=/run/service-state/${name}.service/
-    mkdir -p $outputs
-    (cd $outputs
-    echo $1 > ifname
-    echo $2 > tty
-    echo $3 > speed
-    echo $4 > address
-    echo $5 > peer-address
-    )
-    echo >/proc/self/fd/10
-  '';
-  ppp-options' = ppp-options ++ [
-    "ip-up-script" ip-up
-    "ipparam" name
-    "nodetach"
-  ];
-
-in
-longrun {
-  inherit name;
-  run = "${ppp}/bin/pppd pty '${pppoe}/bin/pppoe -I ${interface.device}' ${lib.concatStringsSep " " ppp-options'}" ;
-  notification-fd = 10;
-  dependencies = [ interface ];
+} @ args: longrun {
+  name = "${interface.device}.ppppoe";
+  run = "${ppp}/bin/pppd pty '${pppoe}/bin/pppoe -I ${interface.device}' ${lib.concatStringsSep " " ppp-options}" ;
 }

pkgs/liminix-tools/networking/udhcpc.nix

@@ -5,19 +5,15 @@
 } :
 let
   inherit (liminix.services) longrun;
-in
-interface: { ... } @ args:
-let
-  name = "${interface.device}.udhcp";
   script = writeShellScript "udhcp-notify" ''
 action=$1
+env > /run/udhcp.values
 
 set_address() {
     ip address replace $ip/$mask dev $interface
-    dir=/run/service-state/${name}.service/
-    mkdir -p $dir
+    mkdir -p data/outputs
     for i in lease mask ip router siaddr dns serverid subnet opt53 interface ; do
-        echo ''${!i} > $dir/$i
+        echo ''${!i} > data/outputs/$i
     done
 }
 case $action in
@@ -37,10 +33,11 @@ case $action in
     ;;
 esac
 '';
-in longrun {
-  inherit name;
+
+in
+interface: { ... } @ args: longrun {
+  name = "${interface.device}.udhcp";
   run = "${busybox}/bin/udhcpc -f -i ${interface.device} -s ${script}";
-  dependencies = [ interface ];
 }
 
 # lease=86400

pkgs/write-ash-script/default.nix

@@ -1,14 +0,0 @@
-{
-  busybox
-, writeScript
-, lib
-}
-: name : { runtimeInputs ? [] } : text : writeScript name ''
-#!${busybox}/bin/sh
-set -o errexit
-set -o nounset
-set -o pipefail
-
-export PATH="${lib.makeBinPath ([ busybox ] ++ runtimeInputs)}:$PATH"
-${text}
-''

tests/pppoe/configuration.nix

@@ -8,56 +8,39 @@ in rec {
     in bundle {
       name = "loopback";
       contents = [
-        (address iface { family = "inet4"; address ="127.0.0.1"; prefixLength = 8;})
-        (address iface { family = "inet6"; address ="::1"; prefixLength = 128;})
+        (address iface { family = "inet4"; addr ="127.0.0.1";})
+        (address iface { family = "inet6"; addr ="::1";})
       ];
     };
 
   kernel.config = {
-    "IKCONFIG_PROC" = "y";
     "PPP" = "y";
     "PPPOE" = "y";
     "PPPOL2TP" = "y";
-    "PPP_ASYNC" = "y";
-    "PPP_BSDCOMP" = "y";
-    "PPP_DEFLATE" = "y";
-    "PPP_MPPE" = "y";
-    "PPP_SYNC_TTY" = "y";
-  };
-
-  services.syslogd = longrun {
-    name = "syslogd";
-    run = "${pkgs.busybox}/bin/syslogd -n -O /run/syslog";
   };
 
   services.pppoe =
     let iface = interface { type = "hardware"; device = "eth0"; };
-    in pppoe iface {
-      ppp-options = [
-        "debug" "+ipv6" "noauth"
-        "name" "db123@a.1"
-        "password" "NotReallyTheSecret"
-      ];
-    };
+    in pppoe iface {};
 
   services.defaultroute4 =
     let iface = services.pppoe;
     in oneshot {
       name = "defaultroute4";
       up = ''
-        ip route add default via $(cat ${output iface "address"})
-        echo "1" > /proc/sys/net/ipv4/conf/$(cat ${output iface "ifname"}/forwarding)
+        ip route add default gw $(cat ${output iface "address"})
+        echo "1" > /sys/net/ipv4/$(cat ${output iface "ifname"})
       '';
       down = ''
-        ip route del default via $(cat ${output iface "address"})
-        echo "0" > /proc/sys/net/ipv4/conf/$(cat ${output iface "ifname"}/forwarding)
+        ip route del default gw $(cat ${output iface "address"})
+        echo "0" > /sys/net/ipv4/$(cat ${output iface "ifname"})
       '';
       dependencies = [iface];
     };
 
   services.default = target {
     name = "default";
-    contents = with services; [ loopback defaultroute4 syslogd ];
+    contents = with services; [ loopback defaultroute4 ];
   };
 
   systemPackages = [ pkgs.hello ] ;

tests/smoke/configuration.nix

@@ -8,8 +8,8 @@ in rec {
     in bundle {
       name = "loopback";
       contents = [
-        (address iface { family = "inet4"; address ="127.0.0.1"; prefixLength = 8;})
-        (address iface { family = "inet6"; address ="::1"; prefixLength = 128;})
+        (address iface { family = "inet4"; addr ="127.0.0.1";})
+        (address iface { family = "inet6"; addr ="::1";})
       ];
     };
   services.dhcpv4 =