egress: reject needs the intercept

nix/host-modules/hive-egress.nix

@@ -473,6 +473,17 @@ in
           the low 17 bits of the agent's address.
         '';
       }
+      {
+        assertion = cfg.egress.forward != "reject" || cfg.egress.intercept.enable;
+        message = ''
+          services.hyperhive.network.egress.forward = "reject" needs
+          services.hyperhive.network.egress.intercept.enable = true:
+          without the intercept nothing redirects the agents' web traffic into
+          squid, and the reject would refuse all of it.
+          Enable the intercept (hive-squid.nix does on a hive controller host),
+          or keep forward = "log".
+        '';
+      }
       {
         assertion = !(lib.any (k: isOn (config.boot.kernel.sysctl.${k} or 0)) routeLocalnetKeys);
         message = ''

nix/module-eval/core-toggle.nix

@@ -80,7 +80,10 @@ let
     network.egress.forward = "accept";
     network.egress.antiSpoof = "log";
   };
-  egressForwardReject = hive {
+  egressForwardReject = hiveWithController {
+    network.egress.forward = "reject";
+  };
+  egressRejectNoIntercept = hive {
     network.enable = true;
     network.egress.forward = "reject";
   };
@@ -1699,7 +1702,9 @@ let
           logged = lib.filter (lib.hasInfix "log prefix") rules;
           bareText = bare.services.hyperhive.network.egress.ruleset;
         in
-        !(lib.any (a: !a.assertion) egressForwardReject.assertions)
+        !(lib.any (
+          a: !a.assertion && lib.hasInfix "network.egress" a.message
+        ) egressForwardReject.assertions)
         && lib.hasInfix "type filter hook forward priority filter - 10; policy accept;" chain
         && lib.hasInfix "chain input" text
         && idx ''oifname "wg-hive" accept'' < idx "ether saddr @direct_mac accept"
@@ -1722,6 +1727,28 @@ let
         && !(lib.hasInfix "reject with" bareText)
         && lib.hasInfix "would-drop" bareText;
     }
+    {
+      # `reject` without the intercept is refused by an assertion that names
+      # the option and both ways out; the controller host with `reject` (the
+      # intercept on) and `bare` (`log`) are the controls that the lookup
+      # finds nothing for them.
+      name = "egress.forward reject without the intercept is refused";
+      ok =
+        let
+          refused =
+            m:
+            lib.filter (
+              a:
+              !a.assertion
+              && lib.hasInfix "services.hyperhive.network.egress.forward = \"reject\" needs" a.message
+            ) m.assertions;
+        in
+        lib.length (refused egressRejectNoIntercept) == 1
+        && lib.hasInfix "intercept.enable = true" (lib.head (refused egressRejectNoIntercept)).message
+        && lib.hasInfix "keep forward = \"log\"" (lib.head (refused egressRejectNoIntercept)).message
+        && refused egressForwardReject == [ ]
+        && refused bare == [ ];
+    }
     {
       # The redirect of the agents' web traffic: IPv4 TCP 80 and 443 from the
       # bridge go to squid's two intercept ports, after the rules that leave