fix: stop favicon requests for private chat-link hosts

apps/mobile/src/features/threads/ThreadFeed.tsx

@@ -84,6 +84,7 @@ import {
   NATIVE_REVIEW_DIFF_CONTENT_WIDTH,
 } from "../review/nativeReviewDiffAdapter";
 import { buildReviewParsedDiff } from "../review/reviewModel";
+import { faviconUrlForOrigin } from "@t3tools/shared/favicon";
 import { cn } from "../../lib/cn";
 import {
   deriveCenteredContentHorizontalPadding,
@@ -447,7 +448,8 @@ const MarkdownExternalLink = memo(function MarkdownExternalLink(props: {
   readonly host: string;
   readonly href: string;
 }) {
-  const [failed, setFailed] = useState(() => failedMarkdownFaviconHosts.has(props.host));
+  const [failedHost, setFailedHost] = useState<string | null>(null);
+  const faviconUrl = faviconUrlForOrigin(`https://${props.host}`);
 
   return (
     <NativeText
@@ -460,15 +462,17 @@ const MarkdownExternalLink = memo(function MarkdownExternalLink(props: {
         textDecorationLine: "none",
       }}
     >
-      {!failed ? (
+      {faviconUrl !== null &&
+      failedHost !== props.host &&
+      !failedMarkdownFaviconHosts.has(props.host) ? (
         <Image
           source={{
-            uri: `https://www.google.com/s2/favicons?domain=${encodeURIComponent(props.host)}&sz=32`,
+            uri: faviconUrl,
           }}
           style={[markdownLinkStyles.inlineIcon, markdownLinkStyles.favicon]}
           onError={() => {
             failedMarkdownFaviconHosts.add(props.host);
-            setFailed(true);
+            setFailedHost(props.host);
           }}
         />
       ) : (

apps/web/src/browser/browserTargetResolver.ts

@@ -4,158 +4,16 @@ import type {
   PreviewUrlResolution,
 } from "@t3tools/contracts";
 import { isLoopbackHost, normalizePreviewUrl } from "@t3tools/shared/preview";
+import {
+  isLocalLoopbackHost,
+  isPrivateNetworkHost,
+  isPublicFaviconHost,
+  normalizeHostname,
+} from "@t3tools/shared/hostClassification";
 
 import { readPreparedConnection } from "~/state/session";
 
-export const normalizeHostname = (host: string): string =>
-  host
-    .toLowerCase()
-    .replace(/^\[|\]$/g, "")
-    .replace(/\.+$/u, "");
-
-const parseIpv4Address = (host: string): readonly number[] | null => {
-  const parts = normalizeHostname(host).split(".").map(Number);
-  return parts.length === 4 &&
-    parts.every((part) => Number.isInteger(part) && part >= 0 && part <= 255)
-    ? parts
-    : null;
-};
-
-const parseIpv4MappedIpv6Address = (host: string): readonly number[] | null => {
-  const normalized = normalizeHostname(host);
-  if (!normalized.startsWith("::ffff:")) return null;
-  const suffix = normalized.slice("::ffff:".length);
-  const dotted = parseIpv4Address(suffix);
-  if (dotted) return dotted;
-  const hextets = suffix.split(":");
-  if (hextets.length !== 2 || hextets.some((part) => !/^[\da-f]{1,4}$/u.test(part))) return null;
-  const high = Number.parseInt(hextets[0]!, 16);
-  const low = Number.parseInt(hextets[1]!, 16);
-  return [high >>> 8, high & 0xff, low >>> 8, low & 0xff];
-};
-
-const parseIpv6Address = (host: string): readonly number[] | null => {
-  const normalized = normalizeHostname(host);
-  if (!normalized.includes(":")) return null;
-  const halves = normalized.split("::");
-  if (halves.length > 2) return null;
-  const head = halves[0] ? halves[0].split(":") : [];
-  const tail = halves[1] ? halves[1].split(":") : [];
-  if ([...head, ...tail].some((part) => !/^[\da-f]{1,4}$/u.test(part))) return null;
-  const missing = 8 - head.length - tail.length;
-  if ((halves.length === 1 && missing !== 0) || (halves.length === 2 && missing < 1)) return null;
-  return [...head, ...Array.from({ length: missing }, () => "0"), ...tail].map((part) =>
-    Number.parseInt(part, 16),
-  );
-};
-
-const ipv6PrefixMatches = (
-  address: readonly number[],
-  prefix: readonly number[],
-  prefixLength: number,
-): boolean => {
-  const fullHextets = Math.floor(prefixLength / 16);
-  if (address.slice(0, fullHextets).some((part, index) => part !== prefix[index])) return false;
-  const remainingBits = prefixLength % 16;
-  if (remainingBits === 0) return true;
-  const mask = (0xffff << (16 - remainingBits)) & 0xffff;
-  return (address[fullHextets]! & mask) === (prefix[fullHextets]! & mask);
-};
-
-const isPrivateIpv4Address = (parts: readonly number[]): boolean =>
-  parts[0] === 0 ||
-  parts[0] === 10 ||
-  parts[0] === 127 ||
-  (parts[0] === 100 && parts[1]! >= 64 && parts[1]! <= 127) ||
-  (parts[0] === 172 && parts[1]! >= 16 && parts[1]! <= 31) ||
-  (parts[0] === 192 && parts[1] === 168) ||
-  (parts[0] === 169 && parts[1] === 254) ||
-  (parts[0] === 198 && parts[1]! >= 18 && parts[1]! <= 19);
-
-const isSpecialPurposeIpv4Address = (parts: readonly number[]): boolean =>
-  isPrivateIpv4Address(parts) ||
-  parts[0]! >= 224 ||
-  // Deliberately suppress the whole protocol-assignment block. IANA marks
-  // .9 and .10 globally reachable, but privacy-safe false negatives are
-  // preferable to disclosing another special-purpose address by mistake.
-  (parts[0] === 192 && parts[1] === 0 && parts[2] === 0) ||
-  (parts[0] === 192 && parts[1] === 0 && parts[2] === 2) ||
-  (parts[0] === 192 && parts[1] === 88 && parts[2] === 99) ||
-  (parts[0] === 198 && parts[1] === 51 && parts[2] === 100) ||
-  (parts[0] === 203 && parts[1] === 0 && parts[2] === 113);
-
-export const isLocalLoopbackHost = (host: string): boolean => {
-  const normalized = normalizeHostname(host);
-  if (normalized === "localhost" || normalized === "::1") return true;
-  return parseIpv4Address(normalized)?.[0] === 127;
-};
-
-export const isPrivateNetworkHost = (host: string): boolean => {
-  const normalized = normalizeHostname(host);
-  if (
-    normalized === "::" ||
-    isLocalLoopbackHost(normalized) ||
-    normalized.endsWith(".localhost") ||
-    normalized.endsWith(".local") ||
-    normalized === "home.arpa" ||
-    normalized.endsWith(".home.arpa") ||
-    (!normalized.includes(".") && !normalized.includes(":"))
-  ) {
-    return true;
-  }
-  if (normalized.endsWith(".ts.net")) return true;
-  const parts = parseIpv4Address(normalized) ?? parseIpv4MappedIpv6Address(normalized);
-  if (parts) return isPrivateIpv4Address(parts);
-  const firstIpv6Token = normalized.split(":", 1)[0] ?? "";
-  if (!normalized.includes(":") || !/^[\da-f]{1,4}$/u.test(firstIpv6Token)) return false;
-  const firstIpv6Hextet = Number.parseInt(firstIpv6Token, 16);
-  return (
-    Number.isInteger(firstIpv6Hextet) &&
-    ((firstIpv6Hextet & 0xfe00) === 0xfc00 || (firstIpv6Hextet & 0xffc0) === 0xfe80)
-  );
-};
-
-/** Whether a hostname is eligible to be disclosed to a public favicon provider. */
-export const isPublicFaviconHost = (host: string): boolean => {
-  // A single trailing dot is a valid absolute DNS name. Repeated trailing
-  // dots are malformed and can conceal legacy numeric forms such as 127.1.
-  if (host.endsWith("..")) return false;
-  const normalized = normalizeHostname(host);
-  if (isPrivateNetworkHost(normalized)) return false;
-  if (
-    [".alt", ".example", ".internal", ".invalid", ".onion", ".test"].some(
-      (suffix) => normalized === suffix.slice(1) || normalized.endsWith(suffix),
-    )
-  ) {
-    return false;
-  }
-  const ipv4 = parseIpv4Address(normalized) ?? parseIpv4MappedIpv6Address(normalized);
-  if (ipv4) return !isSpecialPurposeIpv4Address(ipv4);
-  if (!normalized.includes(":")) return true;
-  const ipv6 = parseIpv6Address(normalized);
-  if (!ipv6) return false;
-  if (ipv6PrefixMatches(ipv6, [0x0064, 0xff9b, 0, 0, 0, 0, 0, 0], 96)) {
-    const embeddedIpv4 = [ipv6[6]! >>> 8, ipv6[6]! & 0xff, ipv6[7]! >>> 8, ipv6[7]! & 0xff];
-    return !isSpecialPurposeIpv4Address(embeddedIpv4);
-  }
-  const first = ipv6[0]!;
-  if ((first & 0xe000) !== 0x2000) return false;
-  if (ipv6PrefixMatches(ipv6, [0x2001, 0, 0, 0, 0, 0, 0, 0], 23)) {
-    const publicProtocolAssignment =
-      (ipv6[1] === 1 &&
-        ipv6.slice(2, 7).every((part) => part === 0) &&
-        [1, 2, 3].includes(ipv6[7]!)) ||
-      ipv6PrefixMatches(ipv6, [0x2001, 3, 0, 0, 0, 0, 0, 0], 32) ||
-      ipv6PrefixMatches(ipv6, [0x2001, 4, 0x0112, 0, 0, 0, 0, 0], 48) ||
-      ipv6PrefixMatches(ipv6, [0x2001, 0x20, 0, 0, 0, 0, 0, 0], 28) ||
-      ipv6PrefixMatches(ipv6, [0x2001, 0x30, 0, 0, 0, 0, 0, 0], 28);
-    return publicProtocolAssignment;
-  }
-  if (ipv6PrefixMatches(ipv6, [0x2001, 0x0db8, 0, 0, 0, 0, 0, 0], 32)) return false;
-  if (ipv6PrefixMatches(ipv6, [0x2002, 0, 0, 0, 0, 0, 0, 0], 16)) return false;
-  if (first === 0x3fff && (ipv6[1]! & 0xf000) === 0) return false;
-  return true;
-};
+export { isLocalLoopbackHost, isPrivateNetworkHost, isPublicFaviconHost, normalizeHostname };
 
 const readEnvironmentUrl = (environmentId: EnvironmentId): URL => {
   const connection = readPreparedConnection(environmentId);

apps/web/src/components/ChatMarkdown.tsx

@@ -25,6 +25,7 @@
   type AtomCommandResult,
 } from "@t3tools/client-runtime/state/runtime";
 import { classifyMarkdownImageSource } from "@t3tools/client-runtime/markdown-images";
+import { faviconUrlForOrigin } from "@t3tools/shared/favicon";
 import * as Cause from "effect/Cause";
 import { AsyncResult } from "effect/unstable/reactivity";
 import React, {
@@ -125,9 +126,9 @@
   WORKSPACE_BASENAME_LOOKUP_LIMIT,
 } from "../workspaceBasenameLookup";
 import {
   findProjectForChangeRequest,
   matchesLinkedPullRequestUrl,
   parseChangeRequestUrl,
   useOpenChangeRequestLink,
 } from "~/lib/openPullRequestLink";
 import { writeTextToClipboard } from "../hooks/useCopyToClipboard";
@@ -1133,16 +1134,17 @@
 
 const MarkdownLinkFavicon = memo(function MarkdownLinkFavicon({ host }: { host: string }) {
   const [failedHost, setFailedHost] = useState<string | null>(null);
+  const faviconUrl = faviconUrlForOrigin(`https://${host}`);
   return (
     <span
       className="ms-[0.25em] me-[0.2em] inline-flex size-[14px] [vertical-align:-0.125em]"
       aria-hidden
     >
-      {failedHost === host || failedFaviconHosts.has(host) ? (
+      {faviconUrl === null || failedHost === host || failedFaviconHosts.has(host) ? (
         <GlobeIcon className={MARKDOWN_LINK_FAVICON_CLASS_NAME} />
       ) : (
         <img
-          src={`https://www.google.com/s2/favicons?domain=${encodeURIComponent(host)}&sz=32`}
+          src={faviconUrl}
           alt=""
           loading="lazy"
           draggable={false}
@@ -1778,10 +1780,10 @@
   );
   const preparedConnection = usePreparedConnection(environmentId);
   const serverConfig = useAtomValue(serverEnvironment.configValueAtom(environmentId));
   const threadServerConfig = useAtomValue(
     serverEnvironment.configValueAtom(threadRef?.environmentId ?? environmentId),
   );
   const projects = useProjects();
   const availableEditors = serverConfig?.availableEditors ?? [];
   const [preferredEditor] = usePreferredEditor(availableEditors);
   const preferredEditorMenuLabel = openInEditorMenuLabel(preferredEditor);

apps/web/src/lib/favicon.ts

@@ -1,23 +1 @@
-import { isPublicFaviconHost } from "~/browser/browserTargetResolver";
-
-/**
- * Favicon helpers for the preview tab strip.
- *
- * Uses Google's s2 favicon endpoint (same approach as ami's tab strip).
- * Callers should always render a `<Globe />` fallback when the returned URL
- * fails to load via an `onError` handler.
- */
-const FAVICON_PROVIDER = "https://www.google.com/s2/favicons";
-
-export function faviconUrlForOrigin(rawUrl: string | null | undefined, size = 32): string | null {
-  if (!rawUrl) return null;
-  try {
-    const url = new URL(rawUrl);
-    if (!url.host) return null;
-    if (url.protocol !== "http:" && url.protocol !== "https:") return null;
-    if (!isPublicFaviconHost(url.hostname)) return null;
-    return `${FAVICON_PROVIDER}?domain=${encodeURIComponent(url.host)}&sz=${size}`;
-  } catch {
-    return null;
-  }
-}
+export { faviconUrlForOrigin } from "@t3tools/shared/favicon";

packages/shared/package.json

@@ -198,6 +198,14 @@
     "./claudeCompaction": {
       "types": "./src/claudeCompaction.ts",
       "import": "./src/claudeCompaction.ts"
+    },
+    "./hostClassification": {
+      "types": "./src/hostClassification.ts",
+      "import": "./src/hostClassification.ts"
+    },
+    "./favicon": {
+      "types": "./src/favicon.ts",
+      "import": "./src/favicon.ts"
     }
   },
   "scripts": {

packages/shared/src/favicon.test.ts

@@ -0,0 +1,42 @@
+import { describe, expect, it } from "vite-plus/test";
+
+import { faviconUrlForOrigin } from "./favicon.ts";
+
+describe("faviconUrlForOrigin", () => {
+  it.each([
+    "http://192.168.1.10:8080",
+    "http://localhost:3000",
+    "http://home.arpa",
+    "https://printer.local.",
+    "https://api.internal",
+    "https://box.tailnet.ts.net",
+    "http://127.1",
+    "http://0x7f000001",
+    "http://[::]",
+    "http://[::1]",
+    "http://[::ffff:192.168.1.10]",
+    "http://[fd00::1]",
+    "http://[fe80::1]",
+    "http://100.64.0.1",
+    "http://198.51.100.1",
+    "http://[2001:db8::1]",
+    "http://service.test",
+    "http://private.onion",
+    "http://127.1..",
+  ])("does not disclose %s to the favicon provider", (origin) => {
+    expect(faviconUrlForOrigin(origin)).toBeNull();
+  });
+
+  it("keeps the public origin, port and requested size", () => {
+    expect(faviconUrlForOrigin("https://github.com:8443/pingdotgg/t3code?private=query", 64)).toBe(
+      "https://www.google.com/s2/favicons?domain=github.com%3A8443&sz=64",
+    );
+  });
+
+  it.each([null, undefined, "", "invalid URL", "file:///tmp/private", "data:text/plain,private"])(
+    "rejects an invalid or unsupported origin %s",
+    (origin) => {
+      expect(faviconUrlForOrigin(origin)).toBeNull();
+    },
+  );
+});

packages/shared/src/favicon.ts

@@ -0,0 +1,15 @@
+import { isPublicFaviconHost } from "./hostClassification.ts";
+
+/** Return a public favicon URL without disclosing private or reserved hosts. */
+export function faviconUrlForOrigin(rawUrl: string | null | undefined, size = 32): string | null {
+  if (!rawUrl) return null;
+  try {
+    const url = new URL(rawUrl);
+    if (!url.host) return null;
+    if (url.protocol !== "http:" && url.protocol !== "https:") return null;
+    if (!isPublicFaviconHost(url.hostname)) return null;
+    return `https://www.google.com/s2/favicons?domain=${encodeURIComponent(url.host)}&sz=${size}`;
+  } catch {
+    return null;
+  }
+}