nixpkgs/modules/services/networking/dhcpcd.nix

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{ config, pkgs, ... }:
with pkgs.lib;
let
inherit (pkgs) dhcpcd;
# Don't start dhclient on explicitly configured interfaces or on
# interfaces that are part of a bridge.
ignoredInterfaces =
map (i: i.name) (filter (i: i ? ipAddress && i.ipAddress != "" ) config.networking.interfaces)
++ concatLists (attrValues (mapAttrs (n: v: v.interfaces) config.networking.bridges));
# Config file adapted from the one that ships with dhcpcd.
dhcpcdConf = pkgs.writeText "dhcpcd.conf"
''
# Inform the DHCP server of our hostname for DDNS.
hostname
# A list of options to request from the DHCP server.
option domain_name_servers, domain_name, domain_search, host_name
option classless_static_routes, ntp_servers, interface_mtu
# A ServerID is required by RFC2131.
require dhcp_server_identifier
# A hook script is provided to lookup the hostname if not set by
# the DHCP server, but it should not be run by default.
nohook lookup-hostname
# Ignore peth* devices; on Xen, they're renamed physical
# Ethernet cards used for bridging. Likewise for vif* and tap*
# (Xen) and virbr* and vnet* (libvirt).
denyinterfaces ${toString ignoredInterfaces} peth* vif* tap* tun* virbr* vnet* vboxnet*
'';
# Hook for emitting ip-up/ip-down events.
exitHook = pkgs.writeText "dhcpcd.exit-hook"
''
#exec >> /var/log/dhcpcd 2>&1
#set -x
params="IFACE=$interface REASON=$reason"
# only works when interface is wireless and wpa_supplicant has a control socket
# but we allow it to fail silently
${optionalString config.networking.wireless.enable ''
params+=" $(${pkgs.wpa_supplicant}/sbin/wpa_cli -i$interface status 2>/dev/null | grep ssid | sed 's|^b|B|;s|ssid|SSID|' | xargs)"
''}
if [ "$reason" = BOUND -o "$reason" = REBOOT ]; then
# Restart ntpd. (The "ip-up" event below will trigger the
# restart.) We need to restart it to make sure that it will
# actually do something: if ntpd cannot resolve the server
# hostnames in its config file, then it will never do
# anything ever again ("couldn't resolve ..., giving up on
# it"), so we silently lose time synchronisation.
${config.system.build.upstart}/sbin/initctl stop ntpd
${config.system.build.upstart}/sbin/initctl emit -n ip-up $params
fi
if [ "$reason" = EXPIRE -o "$reason" = RELEASE -o "$reason" = NOCARRIER ] ; then
${config.system.build.upstart}/sbin/initctl emit -n ip-down $params
fi
'';
in
{
###### implementation
config = mkIf config.networking.useDHCP {
jobs.dhcpcd =
{ startOn = "started network-interfaces";
path = [ dhcpcd pkgs.nettools pkgs.openresolv ];
exec = "dhcpcd --config ${dhcpcdConf} --nobackground";
};
environment.systemPackages = [ dhcpcd ];
environment.etc =
[ { source = exitHook;
target = "dhcpcd.exit-hook";
}
];
powerManagement.resumeCommands =
''
# Tell dhcpcd to rebind its interfaces if it's running.
status="$(${config.system.build.upstart}/sbin/status dhcpcd)"
[[ "$status" =~ start/running ]] && ${dhcpcd}/sbin/dhcpcd --rebind
'';
};
}