networkmanager: remove dhcp and pass dhcpcd instead

The ISC DHCP client has reached its end of life.

nixos/modules/services/networking/networkmanager.nix

@@ -237,7 +237,7 @@ in {
       };
 
       dhcp = mkOption {
-        type = types.enum [ "dhclient" "dhcpcd" "internal" ];
+        type = types.enum [ "dhcpcd" "internal" ];
         default = "internal";
         description = ''
           Which program (or internal library) should be used for DHCP.
@@ -497,7 +497,6 @@ in {
       "d /etc/ipsec.d 0700 root root -"
       "d /var/lib/NetworkManager-fortisslvpn 0700 root root -"
 
-      "d /var/lib/dhclient 0755 root root -"
       "d /var/lib/misc 0755 root root -" # for dnsmasq.leases
     ];
 

pkgs/tools/networking/networkmanager/default.nix

@@ -12,7 +12,7 @@
 , polkit
 , gnutls
 , ppp
-, dhcp
+, dhcpcd
 , iptables
 , nftables
 , python3
@@ -96,9 +96,9 @@ stdenv.mkDerivation rec {
     "-Dresolvconf=${openresolv}/bin/resolvconf"
 
     # DHCP clients
-    "-Ddhclient=${dhcp}/bin/dhclient"
-    # Upstream prefers dhclient, so don't add dhcpcd to the closure
-    "-Ddhcpcd=no"
+    # ISC DHCP client has reached it's end of life, so stop using it
+    "-Ddhclient=no"
+    "-Ddhcpcd=${dhcpcd}/bin/dhcpcd"
     "-Ddhcpcanon=no"
 
     # Miscellaneous