Derive LAN subnets and validate addressing at build time

Add an IPv4 helper lib (parse, netmask, cidr, overlap) and derive router.lans.<name>.ipv4.subnet from address and prefixLength instead of requiring it twice. New assertions reject invalid addresses, DHCP pools that are reversed, outside the subnet or contain the router address, and overlapping LANs. Add `lib` unit tests and an `assertions` check that evaluates broken configs and compares the exact error messages. Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
2026-10-27 15:00:24 +01:00
parent 0ba4d49766
commit 96e5b7b859
9 changed files with 362 additions and 47 deletions
@@ -0,0 +1,60 @@
+# Unit tests for modules/router/lib.nix, run at evaluation time.
+{ pkgs }:
+let
+  inherit (pkgs) lib;
+  r = import ../modules/router/lib.nix { inherit lib; };
+  inherit (r) ipv4;
+  ip = ipv4.parse;
+
+  failures = lib.runTests {
+    testParse = { expr = ip "192.168.10.1"; expected = 3232238081; };
+    testParseZero = { expr = ip "0.0.0.0"; expected = 0; };
+    testParseMax = { expr = ip "255.255.255.255"; expected = 4294967295; };
+    testParseBadOctet = { expr = ip "192.168.10.256"; expected = null; };
+    testParseShort = { expr = ip "192.168.10"; expected = null; };
+    testParseJunk = { expr = ip "192.168.10.x"; expected = null; };
+    testFormatRoundTrip = { expr = ipv4.format (ip "10.20.30.40"); expected = "10.20.30.40"; };
+    testFormatZero = { expr = ipv4.format 0; expected = "0.0.0.0"; };
+    testNetMask24 = { expr = ipv4.format (ipv4.netMask 24); expected = "255.255.255.0"; };
+    testNetMask20 = { expr = ipv4.format (ipv4.netMask 20); expected = "255.255.240.0"; };
+    testNetMask8 = { expr = ipv4.format (ipv4.netMask 8); expected = "255.0.0.0"; };
+    testCidr24 = { expr = ipv4.cidr "192.168.10.77" 24; expected = "192.168.10.0/24"; };
+    testCidr20 = { expr = ipv4.cidr "172.16.37.1" 20; expected = "172.16.32.0/20"; };
+    testCidr30 = { expr = ipv4.cidr "10.0.0.6" 30; expected = "10.0.0.4/30"; };
+    testInSubnetYes = {
+      expr = ipv4.inSubnet { address = ip "192.168.10.1"; prefixLength = 24; } (ip "192.168.10.200");
+      expected = true;
+    };
+    testInSubnetNo = {
+      expr = ipv4.inSubnet { address = ip "192.168.10.1"; prefixLength = 24; } (ip "192.168.11.1");
+      expected = false;
+    };
+    testOverlapNested = {
+      expr = ipv4.overlaps
+        { address = ip "10.0.0.1"; prefixLength = 8; }
+        { address = ip "10.1.2.3"; prefixLength = 24; };
+      expected = true;
+    };
+    testOverlapSame = {
+      expr = ipv4.overlaps
+        { address = ip "192.168.10.1"; prefixLength = 24; }
+        { address = ip "192.168.10.9"; prefixLength = 24; };
+      expected = true;
+    };
+    testOverlapDisjoint = {
+      expr = ipv4.overlaps
+        { address = ip "192.168.10.1"; prefixLength = 24; }
+        { address = ip "192.168.11.1"; prefixLength = 24; };
+      expected = false;
+    };
+  };
+in
+pkgs.runCommand "router-lib-tests" { } (
+  if failures == [ ] then
+    "touch $out"
+  else
+    ''
+      echo ${lib.escapeShellArg (lib.generators.toPretty { } failures)} >&2
+      exit 1
+    ''
+)