Prohibit localhost in simulator (#428)

Corresponding to #421.

Author: apasel422

impl/e2e-tests/measure-conversion-localhost.json

@@ -0,0 +1,72 @@
+{
+  "events": [
+    {
+      "seconds": 1,
+      "site": "localhost",
+      "event": "measureConversion",
+      "options": {
+        "aggregationService": "https://agg-service.example",
+        "histogramSize": 1
+      },
+      "expected": {
+        "error": "DOMException",
+        "name": "SyntaxError"
+      }
+    },
+    {
+      "seconds": 2,
+      "site": "foo.localhost",
+      "event": "measureConversion",
+      "options": {
+        "aggregationService": "https://agg-service.example",
+        "histogramSize": 1
+      },
+      "expected": {
+        "error": "DOMException",
+        "name": "SyntaxError"
+      }
+    },
+    {
+      "seconds": 3,
+      "site": "a.example",
+      "intermediarySite": "localhost",
+      "event": "measureConversion",
+      "options": {
+        "aggregationService": "https://agg-service.example",
+        "histogramSize": 1
+      },
+      "expected": {
+        "error": "DOMException",
+        "name": "SyntaxError"
+      }
+    },
+    {
+      "seconds": 4,
+      "site": "a.example",
+      "event": "measureConversion",
+      "options": {
+        "aggregationService": "https://agg-service.example",
+        "histogramSize": 1,
+        "impressionSites": ["localhost"]
+      },
+      "expected": {
+        "error": "DOMException",
+        "name": "SyntaxError"
+      }
+    },
+    {
+      "seconds": 5,
+      "site": "a.example",
+      "event": "measureConversion",
+      "options": {
+        "aggregationService": "https://agg-service.example",
+        "histogramSize": 1,
+        "impressionCallers": ["localhost"]
+      },
+      "expected": {
+        "error": "DOMException",
+        "name": "SyntaxError"
+      }
+    }
+  ]
+}

impl/e2e-tests/save-impression-localhost.json

@@ -0,0 +1,67 @@
+{
+  "events": [
+    {
+      "seconds": 1,
+      "site": "localhost",
+      "event": "saveImpression",
+      "options": {
+        "histogramIndex": 0
+      },
+      "expectedError": {
+        "error": "DOMException",
+        "name": "SyntaxError"
+      }
+    },
+    {
+      "seconds": 2,
+      "site": "foo.localhost",
+      "event": "saveImpression",
+      "options": {
+        "histogramIndex": 0
+      },
+      "expectedError": {
+        "error": "DOMException",
+        "name": "SyntaxError"
+      }
+    },
+    {
+      "seconds": 3,
+      "site": "a.example",
+      "intermediarySite": "localhost",
+      "event": "saveImpression",
+      "options": {
+        "histogramIndex": 0
+      },
+      "expectedError": {
+        "error": "DOMException",
+        "name": "SyntaxError"
+      }
+    },
+    {
+      "seconds": 4,
+      "site": "a.example",
+      "event": "saveImpression",
+      "options": {
+        "histogramIndex": 0,
+        "conversionSites": ["localhost"]
+      },
+      "expectedError": {
+        "error": "DOMException",
+        "name": "SyntaxError"
+      }
+    },
+    {
+      "seconds": 5,
+      "site": "a.example",
+      "event": "saveImpression",
+      "options": {
+        "histogramIndex": 0,
+        "conversionCallers": ["localhost"]
+      },
+      "expectedError": {
+        "error": "DOMException",
+        "name": "SyntaxError"
+      }
+    }
+  ]
+}

impl/src/backend.ts

@@ -58,7 +58,7 @@ export function days(days: number): Temporal.Duration {
 
 function parseSite(input: string): string {
   const site = getDomain(input, { allowPrivateDomains: true });
-  if (site === null) {
+  if (site === null || site === "localhost" || site.endsWith(".localhost")) {
     throw new DOMException(`invalid site ${input}`, "SyntaxError");
   }
   return site;