harden: key remembered site permissions by full origin (closes #402)

allowedSites and deniedSites held the bare hostname, so a grant to
https://dapp.example also authorised http://dapp.example and every port
on that host, and the connection, transaction and signature prompts
named only the hostname. Both lists now store and match the full origin
(scheme://host[:port]), the key the connections approved without
Remember already used. The prompts, the Settings site lists and
AUTISTMASK_REMOVE_SITE use the origin too. Entries saved by hostname
are not migrated (pre-1.0): they match no site.

Model: opus-5-5

TODO.md

@@ -57,6 +57,15 @@ but the review is broader than any of them.
   change are not migrated (pre-1.0): they match no site, and Settings lists them
   until they are removed.
 
+- 2026-10-04: A page's request is credited only to the site the browser says
+  sent it ([#407](https://git.eeqj.de/sneak/AutistMask/issues/407)). Where the
+  browser does not give the sender's origin (Firefox before 126), the background
+  used the tab's page, so a frame from another site would have been treated as
+  the site embedding it, and with no tab it used an origin the page wrote into
+  the message. It now uses the URL of the frame that sent the message, and
+  refuses the request with code 4100 when the browser gives neither. The content
+  script no longer writes an origin into the message.
+
 - 2026-10-04: `make test` takes 8-13s on the shared build host, down from
   17-25s, measured in alternating runs before and after the change
   ([#428](https://git.eeqj.de/sneak/AutistMask/issues/428)). Each popup boot in

src/background/index.js

@@ -1279,18 +1279,29 @@ if (windowsNs && windowsNs.onRemoved) {
 // Listen for messages from content scripts and popup
 runtime.onMessage.addListener((msg, sender, sendResponse) => {
     if (msg.type === "AUTISTMASK_RPC") {
-        // Derive origin from trusted sender info to prevent origin spoofing.
-        // Chrome MV3 provides sender.origin; Firefox MV2 fallback uses sender.tab.url.
-        let trustedOrigin = msg.origin; // fallback only if sender info unavailable
-        if (sender.origin) {
-            trustedOrigin = sender.origin;
-        } else if (sender.tab && sender.tab.url) {
+        // The origin is the one the browser reports for the sender, never one
+        // the message carries. Firefox before 126 gives no sender.origin, so
+        // the origin of sender.url is used: the frame that sent the message,
+        // not the tab's page, which may be another site embedding that
+        // frame. With neither, the request is refused.
+        let trustedOrigin = sender.origin;
+        if (!trustedOrigin && sender.url) {
             try {
-                trustedOrigin = new URL(sender.tab.url).origin;
+                trustedOrigin = new URL(sender.url).origin;
             } catch {
-                // keep fallback
+                // an unparseable URL leaves the origin unknown
             }
         }
+        if (!trustedOrigin) {
+            sendResponse({
+                error: {
+                    code: 4100,
+                    message:
+                        "The wallet could not tell which site sent this request.",
+                },
+            });
+            return false;
+        }
         handleRpc(msg.method, msg.params, trustedOrigin)
             .then((response) => {
                 sendResponse(response);

src/content/index.js

@@ -30,7 +30,6 @@ window.addEventListener("message", (event) => {
         id,
         method,
         params,
-        origin: location.origin,
     })
         .then((response) => {
             if (response) {

tests/rpcOrigin.test.js

@@ -0,0 +1,146 @@
+// Which site a page's request is attributed to.
+//
+// The background takes a request's origin from what the browser says sent the
+// message: sender.origin, or on Firefox before 126, which has no
+// sender.origin, the origin of sender.url — the frame that sent it. It used to
+// fall back to the tab's page and then to an origin the message itself
+// carried, so a request from a frame was credited to the site embedding it,
+// and a request the browser said nothing about was credited to whatever the
+// page wrote (https://git.eeqj.de/sneak/AutistMask/issues/407).
+//
+// Every sender here lacks sender.origin, as on old Firefox. The connection
+// check on eth_accounts is what shows which site a request was credited to.
+
+const { makeStorageStub } = require("./support/storageStub");
+
+const ADDRESS = "0x66133E8ea0f5D1d612D2502a968757D1048c214a";
+
+// The site the persisted state has connected, and one it has never heard of.
+const CONNECTED_ORIGIN = "https://dapp.example";
+const STRANGER_ORIGIN = "https://stranger.example";
+
+async function settle() {
+    for (let i = 0; i < 50; i++) await Promise.resolve();
+}
+
+afterEach(() => {
+    delete global.chrome;
+});
+
+function loadBackground() {
+    jest.resetModules();
+
+    jest.doMock("../src/shared/balances", () => ({
+        getProvider: () => ({}),
+        refreshBalances: jest.fn(async () => {}),
+    }));
+    jest.doMock("../src/shared/phishingDomains", () => ({
+        isPhishingDomain: () => false,
+    }));
+    jest.doMock("../src/shared/alarms", () => ({
+        BALANCE_REFRESH_ALARM: "balance",
+        BALANCE_REFRESH_PERIOD_MINUTES: 1,
+        ensureRecurringAlarms: jest.fn(async () => {}),
+        registerAlarmHandlers: jest.fn(),
+    }));
+
+    const storage = makeStorageStub({
+        autistmask: {
+            networkId: "mainnet",
+            wallets: [
+                {
+                    name: "Wallet 1",
+                    type: "hd",
+                    addresses: [
+                        { address: ADDRESS, balance: "0", tokenBalances: [] },
+                    ],
+                },
+            ],
+            activeAddress: ADDRESS,
+            allowedSites: { [ADDRESS]: [CONNECTED_ORIGIN] },
+            deniedSites: {},
+        },
+    });
+
+    let messageListener = null;
+    global.chrome = {
+        storage,
+        runtime: {
+            getURL: (path) => "chrome-extension://autistmask/" + path,
+            onMessage: {
+                addListener: (fn) => {
+                    messageListener = fn;
+                },
+            },
+            onConnect: { addListener: () => {} },
+            lastError: null,
+        },
+        windows: { onRemoved: { addListener: () => {} } },
+        action: { setPopup: () => {} },
+    };
+
+    require("../src/background/index");
+
+    // Ask for eth_accounts. `claimedOrigin` is an origin written into the
+    // message, as the content script used to send.
+    return async function accounts(sender, claimedOrigin) {
+        let result = null;
+        messageListener(
+            {
+                type: "AUTISTMASK_RPC",
+                method: "eth_accounts",
+                params: [],
+                origin: claimedOrigin,
+            },
+            sender,
+            (r) => {
+                result = r;
+            },
+        );
+        await settle();
+        return result;
+    };
+}
+
+describe("a request is attributed to the frame that sent it", () => {
+    test("a stranger's frame on a connected site gets no address", async () => {
+        const accounts = loadBackground();
+
+        const result = await accounts({
+            url: STRANGER_ORIGIN + "/frame.html",
+            tab: { url: CONNECTED_ORIGIN + "/" },
+        });
+
+        expect(result).toEqual({ result: [] });
+    });
+
+    test("a connected site's frame on a stranger's page gets the address", async () => {
+        const accounts = loadBackground();
+
+        const result = await accounts({
+            url: CONNECTED_ORIGIN + "/frame.html",
+            tab: { url: STRANGER_ORIGIN + "/" },
+        });
+
+        expect(result).toEqual({ result: [ADDRESS] });
+    });
+});
+
+describe("a request the browser does not say the sender of", () => {
+    test("is refused, whatever the tab or the message says", async () => {
+        const accounts = loadBackground();
+
+        const result = await accounts(
+            { tab: { url: CONNECTED_ORIGIN + "/" } },
+            CONNECTED_ORIGIN,
+        );
+
+        expect(result).toEqual({
+            error: {
+                code: 4100,
+                message:
+                    "The wallet could not tell which site sent this request.",
+            },
+        });
+    });
+});