fix: use the gas limit a site sends as gas (closes #207)

Sites send the gas limit under its JSON-RPC name, `gas`. ethers only
reads `gasLimit`, so the field was dropped and the node's estimate was
shown and signed instead. The page's request now takes `gas` as the gas
limit, and the existing ceiling, display and comparison with the signed
transaction cover it as they already did `gasLimit`. A request that
gives both with different values is refused.

Model: opus-5-5

README.md

@@ -2071,7 +2071,9 @@ view would leave a wallet one click from deletion.
   artifact can be compared with it field for field. A nonce the site supplies is
   ignored: the nonce is always the account's next nonce from the node, so a site
   cannot replace one of the user's pending transactions or leave this one stuck
-  behind a gap. A request that cannot be populated — unreachable node, reverting
+  behind a gap. A gas limit the site supplies, as `gas` or `gasLimit`, is used
+  in place of the node's estimate; a request giving both with different values
+  is refused. A request that cannot be populated — unreachable node, reverting
   gas estimate — opens no window and is failed back to the site. Only one
   transaction approval exists at a time: populating fixes the nonce, so a second
   `eth_sendTransaction` arriving while one is unanswered is refused with
@@ -2124,12 +2126,7 @@ view would leave a wallet one click from deletion.
       blocklist)
     - Site origin (bold, scheme and port included) + "wants you to sign a
       message"
-    - Warning box, shown for `eth_sign`: "This site used the older eth_sign
-      method. The data will be signed as a personal message." An `eth_sign`
-      request names the address first and the data second. Its data is signed
-      exactly as a `personal_sign` message is, as an EIP-191 personal message,
-      which is what the Ethereum JSON-RPC specification defines `eth_sign` to
-      return.
+    - Danger warning box (shown for `eth_sign`, which signs a raw hash)
     - Type: "Personal message" or "Typed data (EIP-712)"
     - From: color dot + full address + etherscan link
     - Message: for `personal_sign` and `eth_sign`, the text the message's bytes

src/background/index.js

@@ -984,8 +984,9 @@ async function handleRpc(method, params, origin) {
 
         if (method === "eth_sign") {
             signParams.dangerWarning =
-                "This site used the older eth_sign method. " +
-                "The data will be signed as a personal message.";
+                "\u26a0\ufe0f DANGER: This site is requesting to sign a raw hash. " +
+                "This can be used to sign transactions that drain your funds. " +
+                "Only proceed if you fully understand what you are signing.";
         }
 
         if (findPendingApproval(origin, "sign")) {

src/popup/index.html

@@ -7,10 +7,9 @@
         <link rel="stylesheet" href="styles.css" />
     </head>
     <!-- Chrome gives extension pages a stylesheet of its own that sets the
-         font and its size on body, and a Tailwind class beats it only when
-         marked important: hence font-mono! and text-sm! rather than
-         font-mono and text-sm. -->
-    <body class="bg-bg text-fg font-mono! text-sm!">
+         font on body, and a Tailwind class beats it only when marked
+         important: hence font-mono! rather than font-mono. -->
+    <body class="bg-bg text-fg font-mono! text-sm">
         <div id="app" class="p-2 pr-5 overflow-x-hidden">
             <!-- ============ GLOBAL TITLE BAR ============ -->
             <div
@@ -88,14 +87,11 @@
 
                 <!-- Mnemonic form section -->
                 <div id="add-wallet-section-mnemonic">
-                    <!-- The die button shares the instruction's row: on a row
-                         of its own it pushes Import below the fold at
-                         360x600. -->
-                    <div class="mb-2 flex justify-between items-start gap-2">
-                        <p>
-                            Enter your 12 or 24 word recovery phrase below, or
-                            click the button to roll the die for a new one.
-                        </p>
+                    <p class="mb-2">
+                        Enter your 12 or 24 word recovery phrase below, or click
+                        the button to roll the die for a new one.
+                    </p>
+                    <div class="mb-1 flex justify-end">
                         <button
                             id="btn-generate-phrase"
                             class="border border-border px-2 py-1 hover:bg-fg hover:text-bg cursor-pointer text-xs"

src/popup/views/approval.js

@@ -721,7 +721,7 @@ function showSignApproval(details) {
             "This message is plain text, not hex, so it cannot be signed.";
     }
 
-    // The warning the background attaches to an eth_sign request.
+    // Display danger warning for eth_sign (raw hash signing)
     const warningEl = $("approve-sign-danger-warning");
     if (warningEl) {
         if (sp.dangerWarning) {

src/shared/approvalTx.js

@@ -31,6 +31,7 @@ const {
     VoidSigner,
     accessListify,
     getAddress,
+    getBigInt,
     getBytes,
     hexlify,
     toQuantity,
@@ -47,10 +48,11 @@ const {
 // minutes long, which is not a wait anyone will sit through.
 const POPULATE_TIMEOUT_MS = 20000;
 
-// The request fields taken from the page. Anything else is dropped rather than
-// passed to ethers: the object is page-controlled, and a future ethers that
-// learns to carry a new transaction field must not start picking one up out of
-// it without this module knowing.
+// The request fields taken from the page, plus `gas`, which requestFrom()
+// takes as the gas limit. Anything else is dropped rather than passed to
+// ethers: the object is page-controlled, and a future ethers that learns to
+// carry a new transaction field must not start picking one up out of it
+// without this module knowing.
 //
 // The nonce is not taken from the page; it is always the account's next nonce
 // from the network. A page that chose it could replace one of the user's
@@ -84,6 +86,16 @@ function present(v) {
     return v !== null && v !== undefined && v !== "";
 }
 
+// Whether two quantities from the page are the same number. One that is not a
+// number matches nothing.
+function sameQuantity(a, b) {
+    try {
+        return getBigInt(a) === getBigInt(b);
+    } catch {
+        return false;
+    }
+}
+
 // These strings reach the user through the requesting page, so they are full
 // sentences even when the tail of one came from ethers or from the node.
 function sentence(text) {
@@ -111,6 +123,20 @@ function requestFrom(txParams, from) {
     for (const key of REQUEST_FIELDS) {
         if (present(txParams[key])) request[key] = txParams[key];
     }
+    // JSON-RPC calls the gas limit `gas`, and that is the name sites send.
+    // ethers only reads `gasLimit`: left as `gas` it would be dropped and an
+    // estimate signed in its place.
+    if (present(txParams.gas)) {
+        if (
+            present(request.gasLimit) &&
+            !sameQuantity(request.gasLimit, txParams.gas)
+        ) {
+            throw fail(
+                "The site asked for two different gas limits for this transaction.",
+            );
+        }
+        request.gasLimit = txParams.gas;
+    }
     if (
         present(request.type) &&
         !ALLOWED_TX_TYPES.includes(Number(request.type))

tests/approvalTx.test.js

@@ -9,7 +9,7 @@
 // requesting page or the RPC node can say turns it into an approval that
 // should never have been raised.
 
-const { Network, Wallet } = require("ethers");
+const { Network, Transaction, Wallet, toQuantity } = require("ethers");
 const {
     prepareApprovalTx,
     serializeApprovedTx,
@@ -138,6 +138,43 @@ describe("prepareApprovalTx", () => {
         expect(approved.maxFeePerGas).toBe("0x12a05f200");
     });
 
+    // `gas` is the JSON-RPC name for the gas limit and the one sites send.
+    // The node would estimate 21000; the site's 200000 is what is shown and
+    // what is signed.
+    test("uses the gas limit a site sends as gas", async () => {
+        const approved = await prepareApprovalTx(
+            providerWith(),
+            signer.address,
+            { ...TX_PARAMS, gas: "0x30d40" },
+        );
+        expect(approved.gasLimit).toBe("0x30d40");
+        const signed = Transaction.from(
+            await signer.signTransaction({ ...approved }),
+        );
+        expect(signed.gasLimit).toBe(200000n);
+    });
+
+    test("accepts gas and gasLimit that name the same number", async () => {
+        const approved = await prepareApprovalTx(
+            providerWith(),
+            signer.address,
+            { ...TX_PARAMS, gas: "0x30d40", gasLimit: 200000 },
+        );
+        expect(approved.gasLimit).toBe("0x30d40");
+    });
+
+    test("refuses gas and gasLimit that disagree", async () => {
+        await expect(
+            prepareApprovalTx(providerWith(), signer.address, {
+                ...TX_PARAMS,
+                gas: "0x30d40",
+                gasLimit: "0x5208",
+            }),
+        ).rejects.toThrow(
+            "The site asked for two different gas limits for this transaction.",
+        );
+    });
+
     test("carries an access list the request asked for", async () => {
         const approved = await prepareApprovalTx(
             providerWith(),
@@ -212,6 +249,15 @@ describe("prepareApprovalTx", () => {
         ).rejects.toThrow(/gas limit no network this wallet supports/);
     });
 
+    test("refuses a gas limit the site sent above the ceiling", async () => {
+        await expect(
+            prepareApprovalTx(providerWith(), signer.address, {
+                ...TX_PARAMS,
+                gas: toQuantity(MAX_GAS_LIMIT + 1n),
+            }),
+        ).rejects.toThrow(/gas limit no network this wallet supports/);
+    });
+
     // The combined bound at population: a gas limit and a fee that are each
     // under their own ceiling but multiply to thousands of ETH is refused
     // before the approval window opens, so the user is never shown a

tests/backgroundApproval.test.js

@@ -1551,53 +1551,6 @@ describe("what the approval is verified against", () => {
     });
 });
 
-// eth_sign names the address first and the data second, the reverse of
-// personal_sign, and is answered as the JSON-RPC specification defines it:
-// with an EIP-191 personal message signature over the data, the same
-// signature personal_sign returns
-// (https://git.eeqj.de/sneak/AutistMask/issues/409).
-describe("eth_sign", () => {
-    test("is read address first, and returns a personal message signature over the data", async () => {
-        const bg = loadBackground();
-        const page = bg.send(
-            {
-                type: "AUTISTMASK_RPC",
-                method: "eth_sign",
-                params: [signer.address, MESSAGE],
-            },
-            { origin: ORIGIN },
-        );
-        await settle();
-        const id = approvalIdIn(bg.created.map((c) => c.url));
-
-        const details = bg.send(
-            { type: "AUTISTMASK_GET_APPROVAL", id },
-            { url: bg.fromPopup.url },
-        );
-        const { signParams } = details.sendResponse.mock.calls[0][0];
-        expect(signParams).toMatchObject({
-            method: "eth_sign",
-            message: MESSAGE,
-            from: signer.address,
-        });
-        expect(signParams.dangerWarning).toBe(
-            "This site used the older eth_sign method. " +
-                "The data will be signed as a personal message.",
-        );
-
-        const signature = await signer.signMessage(
-            Buffer.from(MESSAGE.slice(2), "hex"),
-        );
-        bg.send(
-            { type: "AUTISTMASK_SIGN_RESPONSE", id, approved: true, signature },
-            { url: bg.fromPopup.url },
-        );
-        await settle();
-
-        expect(page.sendResponse).toHaveBeenCalledWith({ result: signature });
-    });
-});
-
 // The interlock must not cost the retry the approval exists to allow.
 describe("the interlock releases a failed attempt", () => {
     test("a retryable failure before the broadcast leaves the approval usable", async () => {

tests/e2e/firefox/run.js

@@ -128,18 +128,6 @@ step("the popup is drawn in the monospace font it declares", async (env) => {
     );
 });
 
-// The same check as the Chrome suite's (#456), so both browsers are held to
-// the same size.
-step("the popup's text is drawn at the 14px text-sm declares", async (env) => {
-    const size = await env.driver.execute(
-        "return getComputedStyle(document.body).fontSize;",
-    );
-    assert(
-        size === "14px",
-        "the popup's text is drawn at " + size + ", not at the 14px of text-sm",
-    );
-});
-
 // The recovery screen (#361): the Chrome suite's four cases, run before any
 // wallet exists for the same reason. With no wallet nothing saves on a timer,
 // so no save can write a good record over the unreadable one. The last of them

tests/e2e/run.js

@@ -113,18 +113,6 @@ test("the popup is drawn in the monospace font it declares (#418)", async (env)
     );
 });
 
-// The same stylesheet sets the size on body to 75%, which would draw the
-// popup at 12px.
-test("the popup's text is drawn at the 14px text-sm declares (#456)", async (env) => {
-    const size = await env.page.evaluate(
-        () => getComputedStyle(document.body).fontSize,
-    );
-    assert(
-        size === "14px",
-        "the popup's text is drawn at " + size + ", not at the 14px of text-sm",
-    );
-});
-
 // The empirical half of #182. The manifest change is only a claim about
 // what the CSP permits; this is the observation. Two things have to hold
 // together, and the run covers both: the popup realm compiles WASM (here),