Merge pull request #272 from nix-community/dhcp

Better dhcp support

nix/image-installer/module.nix

@@ -40,8 +40,9 @@ in
   imports = [
     (modulesPath + "/installer/cd-dvd/installation-cd-base.nix")
     ../installer.nix
-    ./wifi.nix
+    ../noveau-workaround.nix
     ./hidden-ssh-announcement.nix
+    ./wifi.nix
   ];
   systemd.tmpfiles.rules = [ "d /var/shared 0777 root root - -" ];
   services.openssh.settings.PermitRootLogin = "yes";

nix/kexec-installer/local-network-restore-test.sh

@@ -0,0 +1,26 @@
+#!/usr/bin/env -S nix shell --inputs-from .# nixos-unstable#bash nixos-unstable#iproute2 nixos-unstable#findutils nixos-unstable#coreutils nixos-unstable#python3 nixos-unstable#jq --command bash
+
+set -eu
+SCRIPT_DIR=$(dirname "$(readlink -f "$0")")
+
+# This script can be used to see what network configuration would be restored by the restore_routes.py script for the current system.
+
+tmp=$(mktemp -d)
+trap "rm -rf $tmp" EXIT
+ip --json address >"$tmp/addrs.json"
+ip -6 --json route >"$tmp/routes-v6.json"
+ip -4 --json route >"$tmp/routes-v4.json"
+python3 "$SCRIPT_DIR/restore_routes.py" "$tmp/addrs.json" "$tmp/routes-v4.json" "$tmp/routes-v6.json" "$tmp"
+ls -la "$tmp"
+
+find "$tmp" -type f -name "*.json" -print0 | while IFS= read -r -d '' file; do
+  echo -e "\033[0;31m$(basename "$file")\033[0m"
+  jq . "$file"
+  echo ""
+done
+
+find "$tmp" -type f -name "*.network" -print0 | while IFS= read -r -d '' file; do
+  echo -e "\033[0;31m$(basename "$file")\033[0m"
+  cat "$file"
+  echo ""
+done

nix/kexec-installer/module.nix

@@ -1,6 +1,6 @@
 { config, lib, modulesPath, pkgs, ... }:
 let
-  restore-network = pkgs.writers.writePython3 "restore-network" { flakeIgnore = [ "E501" ]; }
+  restore-network = pkgs.writers.writePython3Bin "restore-network" { flakeIgnore = [ "E501" ]; }
     ./restore_routes.py;
 
   # does not link with iptables enabled
@@ -64,7 +64,7 @@ in
         Type = "oneshot";
         RemainAfterExit = true;
         ExecStart = [
-          "${restore-network} /root/network/addrs.json /root/network/routes-v4.json /root/network/routes-v6.json /etc/systemd/network"
+          "${restore-network}/bin/restore-network /root/network/addrs.json /root/network/routes-v4.json /root/network/routes-v6.json /etc/systemd/network"
         ];
       };
 

nix/kexec-installer/restore_routes.py

@@ -1,34 +1,80 @@
 import json
 import sys
 from pathlib import Path
-from typing import Any
+from typing import Any, Iterator
+from dataclasses import dataclass
 
 
-def filter_interfaces(network: list[dict[str, Any]]) -> list[dict[str, Any]]:
+@dataclass
-    output = []
+class Address:
+    address: str
+    family: str
+    prefixlen: int
+    preferred_life_time: int = 0
+    valid_life_time: int = 0
+
+
+@dataclass
+class Interface:
+    name: str
+    ifname: str | None
+    mac_address: str
+    dynamic_addresses: list[Address]
+    static_addresses: list[Address]
+    static_routes: list[dict[str, Any]]
+
+
+def filter_interfaces(network: list[dict[str, Any]]) -> list[Interface]:
+    interfaces = []
     for net in network:
         if net.get("link_type") == "loopback":
             continue
-        if not net.get("address"):
+        if not (mac_address := net.get("address")):
             # We need a mac address to match devices reliable
             continue
-        addr_info = []
+        static_addresses = []
-        has_dynamic_address = False
+        dynamic_addresses = []
-        for addr in net.get("addr_info", []):
+        for info in net.get("addr_info", []):
             # no link-local ipv4/ipv6
-            if addr.get("scope") == "link":
+            if info.get("scope") == "link":
                 continue
-            # do not explicitly configure addresses from dhcp or router advertisement
+            if (preferred_life_time := info.get("preferred_life_time")) is None:
-            if addr.get("dynamic", False):
+                continue
-                has_dynamic_address = True
+            if (valid_life_time := info.get("valid_life_time")) is None:
+                continue
+            if (prefixlen := info.get("prefixlen")) is None:
+                continue
+            if (family := info.get("family")) not in ["inet", "inet6"]:
+                continue
+            if (local := info.get("local")) is None:
+                continue
+            if (dynamic := info.get("dynamic", False)) is None:
                 continue
-            else:
-                addr_info.append(addr)
-        if addr_info != [] or has_dynamic_address:
-            net["addr_info"] = addr_info
-            output.append(net)
 
-    return output
+            address = Address(
+                address=local,
+                family=family,
+                prefixlen=prefixlen,
+                preferred_life_time=preferred_life_time,
+                valid_life_time=valid_life_time,
+            )
+
+            if dynamic:
+                dynamic_addresses.append(address)
+            else:
+                static_addresses.append(address)
+        interfaces.append(
+            Interface(
+                name=net.get("ifname", mac_address.replace(":", "-")),
+                ifname=net.get("ifname"),
+                mac_address=mac_address,
+                dynamic_addresses=dynamic_addresses,
+                static_addresses=static_addresses,
+                static_routes=[],
+            )
+        )
+
+    return interfaces
 
 
 def filter_routes(routes: list[dict[str, Any]]) -> list[dict[str, Any]]:
@@ -42,44 +88,54 @@ def filter_routes(routes: list[dict[str, Any]]) -> list[dict[str, Any]]:
     return filtered
 
 
+def find_most_recent_v4_lease(addresses: list[Address]) -> Address | None:
+    most_recent_address = None
+    most_recent_lifetime = -1
+    for addr in addresses:
+        if addr.family == "inet6":
+            continue
+        lifetime = max(addr.preferred_life_time, addr.valid_life_time)
+        if lifetime > most_recent_lifetime:
+            most_recent_lifetime = lifetime
+            most_recent_address = addr
+    return most_recent_address
+
+
+def generate_routes(
+    interface: Interface, routes: list[dict[str, Any]]
+) -> Iterator[str]:
+    for route in routes:
+        if interface.ifname is None or route.get("dev") != interface.ifname:
+            continue
+
+        # we may ignore on-link default routes here, but I don't see how
+        # they would be useful for internet connectivity anyway
+
+        yield "[Route]"
+        if route.get("dst") != "default":
+            # can be skipped for default routes
+            yield f"Destination = {route['dst']}"
+        gateway = route.get("gateway")
+        # route v4 via v6
+        route_via = route.get("via")
+        if route_via and route_via.get("family") == "inet6":
+            gateway = route_via.get("host")
+            if route.get("dst") == "default":
+                yield "Destination = 0.0.0.0/0"
+        if gateway:
+            yield f"Gateway = {gateway}"
+
+
 def generate_networkd_units(
-    interfaces: list[dict[str, Any]], routes: list[dict[str, Any]], directory: Path
+    interfaces: list[Interface], routes: list[dict[str, Any]], directory: Path
 ) -> None:
     directory.mkdir(exist_ok=True)
     for interface in interfaces:
-        name = f"00-{interface['ifname']}.network"
-        addresses = [
-            f"Address = {addr['local']}/{addr['prefixlen']}"
-            for addr in interface.get("addr_info", [])
-        ]
-
-        route_sections = []
-        for route in routes:
-            if route.get("dev", "nodev") != interface.get("ifname", "noif"):
-                continue
-
-            route_section = "[Route]\n"
-            if route.get("dst") != "default":
-                # can be skipped for default routes
-                route_section += f"Destination = {route['dst']}\n"
-            gateway = route.get("gateway")
-            # route v4 via v6
-            route_via = route.get("via")
-            if route_via and route_via.get("family") == "inet6":
-                gateway = route_via.get("host")
-                if route.get("dst") == "default":
-                    route_section += "Destination = 0.0.0.0/0\n"
-            if gateway:
-                route_section += f"Gateway = {gateway}\n"
-
-            # we may ignore on-link default routes here, but I don't see how
-            # they would be useful for internet connectivity anyway
-            route_sections.append(route_section)
-
         # FIXME in some networks we might not want to trust dhcp or router advertisements
-        unit = f"""
+        unit_sections = [
+            f"""
 [Match]
-MACAddress = {interface["address"]}
+MACAddress = {interface.mac_address}
 
 [Network]
 # both ipv4 and ipv6
@@ -89,12 +145,24 @@ LLDP = yes
 # ipv6 router advertisements
 IPv6AcceptRA = yes
 # allows us to ping "nixos.local"
-MulticastDNS = yes
+MulticastDNS = yes"""
+        ]
+        unit_sections.extend(
+            f"Address = {addr.address}/{addr.prefixlen}"
+            for addr in interface.static_addresses
+        )
+        unit_sections.extend(generate_routes(interface, routes))
+        most_recent_v4_lease = find_most_recent_v4_lease(interface.dynamic_addresses)
+        if most_recent_v4_lease:
+            unit_sections.append("[DHCPv4]")
+            unit_sections.append(f"RequestAddress = {most_recent_v4_lease.address}")
 
-"""
+        # trailing newline at the end
-        unit += "\n".join(addresses)
+        unit_sections.append("")
-        unit += "\n" + "\n".join(route_sections)
+
-        (directory / name).write_text(unit)
+        (directory / f"00-{interface.name}.network").write_text(
+            "\n".join(unit_sections)
+        )
 
 
 def main() -> None:

nix/noninteractive.nix

@@ -12,6 +12,7 @@
   imports = [
     ./zfs-minimal.nix
     ./no-bootloaders.nix
+    ./noveau-workaround.nix
     # reduce closure size by removing perl
     "${modulesPath}/profiles/perlless.nix"
     # FIXME: we still are left with nixos-generate-config due to nixos-install-tools
@@ -35,10 +36,14 @@
   users.users.nixos = {
     isSystemUser = true;
     isNormalUser = lib.mkForce false;
+    shell = "/run/current-system/sw/bin/bash";
     group = "nixos";
   };
   users.groups.nixos = {};
 
+  # we prefer root as this is also what we use in nixos-anywhere
+  services.getty.autologinUser = lib.mkForce "root";
+
   # we are missing this from base.nix
   boot.supportedFilesystems = [
     "btrfs"

nix/noveau-workaround.nix

@@ -0,0 +1,4 @@
+{
+  # fixes blank screen on boot for some cards
+  boot.kernelParams = [ "nouveau.modeset=0" ];
+}