modules/dnsmasq/cmd/dnsmasq-tools/templates_test.go

@@ -122,3 +122,43 @@ func TestAddressWaitIsAtMostTwoSeconds(t *testing.T) {
 		t.Fatal("mesh.conf has no ExecStartPre")
 	}
 }
+
+// The two public upstreams are the module's settings, defaulting to the two the resolver always used, placed
+// as server lines beside no-resolv: a person sets them per node or mesh-wide without a build.
+func TestUpstreamsAreConfigValues(t *testing.T) {
+	raw, err := os.ReadFile(filepath.Join(moduleDir, "module.json"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	var m struct {
+		Config map[string]struct {
+			Default string `json:"default"`
+			Pattern string `json:"pattern"`
+		} `json:"config"`
+	}
+	if err := json.Unmarshal(raw, &m); err != nil {
+		t.Fatal(err)
+	}
+	conf, err := os.ReadFile(filepath.Join(moduleDir, "files", "dnsmasq.conf"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	for key, def := range map[string]string{"upstream-resolver-first": "1.1.1.1", "upstream-resolver-second": "8.8.8.8"} {
+		c, ok := m.Config[key]
+		if !ok || c.Default != def {
+			t.Errorf("config %s = %+v, want default %s", key, c, def)
+		}
+		if !regexp.MustCompile(c.Pattern).MatchString(def) {
+			t.Errorf("pattern %q refuses the default %s", c.Pattern, def)
+		}
+		if !strings.Contains(string(conf), "\nserver=${config:"+key+"}\n") {
+			t.Errorf("dnsmasq.conf does not place %s as a server line", key)
+		}
+	}
+	if strings.Contains(string(conf), "server=1.1.1.1") || strings.Contains(string(conf), "server=8.8.8.8") {
+		t.Error("dnsmasq.conf still hard-codes an upstream")
+	}
+	if !strings.Contains(string(conf), "\nno-resolv\n") {
+		t.Error("dnsmasq.conf lost no-resolv")
+	}
+}

modules/dnsmasq/files/dnsmasq.conf

@@ -57,12 +57,12 @@ listen-address=127.0.0.1
 # upstreams would find itself, and every query it could not answer locally would
 # loop until its receive queue filled. That is not theoretical: it filled with
 # 15KB of queries and every lookup on the machine hung. no-resolv makes that loop
-# impossible: the upstreams are the two lines below, and nothing on the machine
+# impossible: the upstreams are the two lines below (the module's settings upstream-resolver-first and -second), and nothing on the machine
 # can redirect them. The mesh's own names never reach them: the local= line in
 # the file above stops them here, answered or refused.
 no-resolv
-server=1.1.1.1
-server=8.8.8.8
+server=${config:upstream-resolver-first}
+server=${config:upstream-resolver-second}
 
 # Both upstreams validate DNSSEC and say so with the Authenticated Data bit,
 # and this passes that bit down rather than dropping it, which dnsmasq does

modules/dnsmasq/module.json

@@ -38,6 +38,22 @@
     "dnsmasq_names",
     "dnsmasq_resolve"
   ],
+  "config": {
+    "upstream-resolver-first": {
+      "type": "string",
+      "description": "The first public resolver this resolver forwards to for every name that is not the mesh's own, as an IP address. It is placed as a server line beside no-resolv, so it must never be an address that resolves through this machine; both upstreams should validate DNSSEC, since the authenticated-data bit is passed down (ADR 0194, ADR 0223). Set per node or for the whole mesh.",
+      "trusted": false,
+      "pattern": "^[0-9A-Fa-f.:]+$",
+      "default": "1.1.1.1"
+    },
+    "upstream-resolver-second": {
+      "type": "string",
+      "description": "The second public resolver this resolver forwards to, as an IP address, tried beside the first so one upstream being down does not stop name resolution. The same rules as upstream-resolver-first.",
+      "trusted": false,
+      "pattern": "^[0-9A-Fa-f.:]+$",
+      "default": "8.8.8.8"
+    }
+  },
   "listens": [
     {
       "name": "dns-udp",