fix: typed data with a missing field or a bool that is not true or false is refused (closes #552)

ethers signs a bool field by whether its value is truthy, so the string
"false" was shown as false and signed as true, and a bool field left out
was shown as nothing and signed as false. The sign screen now refuses
typed data whose message leaves out a declared field, at any level of
nesting, or holds a bool that is not true or false: the error line names
the field and Sign is disabled. The background refuses a signature for it
too. Presence is an own-key test, so a field named like a built-in
property such as constructor is not found by accident. signedPrimaryType()
moves to the shared module so the background reads the message as the
same type.

Model: opus-5-5

tests/backgroundApproval.test.js

@@ -384,13 +384,13 @@ function loadBackground(options) {
 
     // The same through eth_signTypedData_v4, whose params name the address
     // first and the typed data second.
-    function requestTypedData() {
+    function requestTypedData(typedData = TYPED_DATA) {
         let rpcResult = null;
         messageListener(
             {
                 type: "AUTISTMASK_RPC",
                 method: "eth_signTypedData_v4",
-                params: [signer.address, TYPED_DATA],
+                params: [signer.address, typedData],
             },
             { origin: ORIGIN },
             (r) => {
@@ -1494,8 +1494,8 @@ describe("what the approval is verified against", () => {
     // screen; a signature for it that reaches the background anyway is not
     // handed to the page (https://git.eeqj.de/sneak/AutistMask/issues/519).
     // TYPED_DATA names mainnet.
-    async function answerTypedData(bg, pending) {
-        const { domain, types, message } = JSON.parse(TYPED_DATA);
+    async function answerTypedData(bg, pending, typedData = TYPED_DATA) {
+        const { domain, types, message } = JSON.parse(typedData);
         delete types.EIP712Domain;
         const signature = await signer.signTypedData(domain, types, message);
         const answer = bg.send(
@@ -1539,6 +1539,42 @@ describe("what the approval is verified against", () => {
         expect(pending.result()).toEqual({ error: { message: refusal } });
     });
 
+    // ethers signs a `bool` field sent as the string "false" as true, and one
+    // left out as false. The sign screen refuses both; a signature for either
+    // that reaches the background anyway is not handed to the page
+    // (https://git.eeqj.de/sneak/AutistMask/issues/552).
+    test.each([
+        [
+            '"false"',
+            "false",
+            'The field "approved" is not true or false, so this typed data cannot be signed.',
+        ],
+        [
+            "left out",
+            undefined,
+            'The field "approved" is missing from the message, so this typed data cannot be signed.',
+        ],
+    ])(
+        "typed data with a bool %s is refused, not handed back",
+        async (_, approved, refusal) => {
+            const data = JSON.parse(TYPED_DATA);
+            data.types.Note.push({ name: "approved", type: "bool" });
+            data.message.approved = approved;
+            const typedData = JSON.stringify(data);
+            const bg = loadBackground();
+            const pending = bg.requestTypedData(typedData);
+            await settle();
+
+            const { answer } = await answerTypedData(bg, pending, typedData);
+
+            expect(answer.sendResponse).toHaveBeenCalledWith({
+                error: refusal,
+                retryable: false,
+            });
+            expect(pending.result()).toEqual({ error: { message: refusal } });
+        },
+    );
+
     test("a sign request from another address raises no approval at all", async () => {
         const bg = loadBackground();
         const pending = bg.requestSign(other.address);