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
@@ -2678,11 +2680,7 @@ Currently supported:
   or recipient, and amount.
 - **Uniswap Universal Router**: `execute()` calls — shows swap direction (e.g.
   "Swap USDT → ETH"), token addresses, amounts, execution steps, and deadline.
-  Decodes Permit2, V2/V3/V4 swaps, wrap/unwrap, and balance checks. A V4 swap
-  action is read only in the parameter shape deployed on mainnet and Sepolia,
-  not in the newer one on `v4-periphery` `main`, which adds a `minHopPriceX36`
-  field. An action in any other shape is not read, and its step is listed as
-  `V4 Swap (could not be decoded)`.
+  Decodes Permit2, V2/V3/V4 swaps, wrap/unwrap, and balance checks.
 
 ### Non-Goals Forever
 

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))

src/shared/uniswap.js

@@ -295,24 +295,6 @@ function v4ExactInAmount(raw) {
     return raw === 0n ? OPEN_DELTA : raw;
 }
 
-// The V4 swap actions are read only in the parameter structs V4Router has
-// deployed on mainnet and Sepolia. v4-periphery `main` has since added a
-// `minHopPriceX36` field to all four (`src/interfaces/IV4Router.sol`), and
-// reading a shape nobody has deployed would be guessing. ethers alone would
-// read the newer structs anyway: it takes whatever word sits where a
-// deployed field would be, ignores bytes left over, and holds back an error
-// in a field until that field is used. The newer multi-hop exact-in struct
-// then yields the offset of its hop-price array as `amountIn`. So a decode
-// counts only when encoding the result again gives back the same bytes;
-// otherwise this throws, and decodeV4Swap() marks the step as not decoded.
-function decodeExactly(types, data) {
-    const decoded = coder.decode(types, data);
-    if (coder.encode(types, decoded) !== data) {
-        throw new Error("Not in the deployed V4 parameter shape.");
-    }
-    return decoded;
-}
-
 // Decode V4_SWAP (command 0x10) input bytes.
 // The input is ABI-encoded as (bytes actions, bytes[] params).
 // We extract token addresses from SETTLE (input) and TAKE (output) sub-actions,
@@ -327,10 +309,6 @@ function decodeV4Swap(input) {
         let takeToken = null;
         let amountIn = null;
         let amountOutMin = null;
-        // Set when a swap action's parameters are not in the deployed shape
-        // (see decodeExactly()), so nothing was read from that action. SETTLE
-        // and TAKE may still name both currencies.
-        let swapUndecoded = false;
 
         for (let i = 0; i < actions.length; i++) {
             const actionId = actions[i];
@@ -359,7 +337,7 @@ function decodeV4Swap(input) {
                         //   tuple(address,uint24,int24,address,bytes)[] path,
                         //   uint128 amountIn, uint128 amountOutMin)
                         try {
-                            const s = decodeExactly(
+                            const s = coder.decode(
                                 [
                                     "tuple(address,tuple(address,uint24,int24,address,bytes)[],uint128,uint128)",
                                 ],
@@ -377,13 +355,13 @@ function decodeV4Swap(input) {
                                 amountOutMin = s[0][3];
                             }
                         } catch {
-                            swapUndecoded = true;
+                            // Fall through — SETTLE/TAKE will provide tokens
                         }
                     } else {
                         // ExactInputSingleParams: (tuple(address,address,uint24,int24,address) poolKey,
                         //   bool zeroForOne, uint128 amountIn, uint128 amountOutMin, bytes hookData)
                         try {
-                            const s = decodeExactly(
+                            const s = coder.decode(
                                 [
                                     "tuple(tuple(address,address,uint24,int24,address),bool,uint128,uint128,bytes)",
                                 ],
@@ -406,7 +384,7 @@ function decodeV4Swap(input) {
                                 amountOutMin = s[0][3];
                             }
                         } catch {
-                            swapUndecoded = true;
+                            // Fall through
                         }
                     }
                 } else if (
@@ -415,7 +393,7 @@ function decodeV4Swap(input) {
                 ) {
                     if (actionId === V4_SWAP_EXACT_OUT) {
                         try {
-                            const s = decodeExactly(
+                            const s = coder.decode(
                                 [
                                     "tuple(address,tuple(address,uint24,int24,address,bytes)[],uint128,uint128)",
                                 ],
@@ -427,11 +405,11 @@ function decodeV4Swap(input) {
                                 settleToken = path[path.length - 1][0];
                             }
                         } catch {
-                            swapUndecoded = true;
+                            // Fall through
                         }
                     } else {
                         try {
-                            const s = decodeExactly(
+                            const s = coder.decode(
                                 [
                                     "tuple(tuple(address,address,uint24,int24,address),bool,uint128,uint128,bytes)",
                                 ],
@@ -448,7 +426,7 @@ function decodeV4Swap(input) {
                                     ? poolKey[1]
                                     : poolKey[0];
                         } catch {
-                            swapUndecoded = true;
+                            // Fall through
                         }
                     }
                 }
@@ -462,7 +440,6 @@ function decodeV4Swap(input) {
             tokenOut: takeToken,
             amountIn,
             amountOutMin,
-            swapUndecoded,
         };
     } catch {
         return null;
@@ -591,11 +568,6 @@ function decode(data, toAddress, sources) {
                 if (cmdId === 0x10) {
                     const v4 = decodeV4Swap(inputs[i]);
                     if (v4) {
-                        // Without this, a swap action that went unread would
-                        // look like one that had nothing to show.
-                        if (v4.swapUndecoded) {
-                            commandNames[i] += " (could not be decoded)";
-                        }
                         setInputOnce(v4.tokenIn, v4.amountIn);
                         // Always update output: last swap step wins. A step
                         // that carries the Min. received figure but decoded no

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/uniswap.test.js

@@ -163,110 +163,6 @@ function encodeV4ExactInSingle(currency0, currency1, amountIn, amountOutMin) {
     );
 }
 
-// Each V4 swap action's parameters in two shapes: the struct V4Router has
-// deployed on mainnet and Sepolia, and the one v4-periphery `main` has since
-// moved to, which adds a `minHopPriceX36` field. Each swaps WETH for USDC.
-const POOL_KEY = "tuple(address,address,uint24,int24,address)";
-const PATH_KEY = "tuple(address,uint24,int24,address,bytes)";
-const WETH_USDC_POOL = [WETH_ADDR, USDC_ADDR, 100, 1, ZERO_ADDR];
-const ONE_WETH = 1000000000000000000n;
-const V4_SWAP_ACTION_SHAPES = [
-    {
-        action: "SWAP_EXACT_IN_SINGLE",
-        id: 0x06,
-        deployed: coder.encode(
-            [`tuple(${POOL_KEY},bool,uint128,uint128,bytes)`],
-            [[WETH_USDC_POOL, true, ONE_WETH, 990000n, "0x"]],
-        ),
-        newer: coder.encode(
-            [`tuple(${POOL_KEY},bool,uint128,uint128,uint256,bytes)`],
-            [[WETH_USDC_POOL, true, ONE_WETH, 990000n, 0n, "0x"]],
-        ),
-    },
-    {
-        action: "SWAP_EXACT_IN",
-        id: 0x07,
-        deployed: coder.encode(
-            [`tuple(address,${PATH_KEY}[],uint128,uint128)`],
-            [
-                [
-                    WETH_ADDR,
-                    [[USDC_ADDR, 100, 1, ZERO_ADDR, "0x"]],
-                    ONE_WETH,
-                    990000n,
-                ],
-            ],
-        ),
-        newer: coder.encode(
-            [`tuple(address,${PATH_KEY}[],uint256[],uint128,uint128)`],
-            [
-                [
-                    WETH_ADDR,
-                    [[USDC_ADDR, 100, 1, ZERO_ADDR, "0x"]],
-                    [],
-                    ONE_WETH,
-                    990000n,
-                ],
-            ],
-        ),
-    },
-    {
-        action: "SWAP_EXACT_OUT_SINGLE",
-        id: 0x08,
-        deployed: coder.encode(
-            [`tuple(${POOL_KEY},bool,uint128,uint128,bytes)`],
-            [[WETH_USDC_POOL, true, 990000n, ONE_WETH, "0x"]],
-        ),
-        newer: coder.encode(
-            [`tuple(${POOL_KEY},bool,uint128,uint128,uint256,bytes)`],
-            [[WETH_USDC_POOL, true, 990000n, ONE_WETH, 0n, "0x"]],
-        ),
-    },
-    {
-        action: "SWAP_EXACT_OUT",
-        id: 0x09,
-        deployed: coder.encode(
-            [`tuple(address,${PATH_KEY}[],uint128,uint128)`],
-            [
-                [
-                    USDC_ADDR,
-                    [[WETH_ADDR, 100, 1, ZERO_ADDR, "0x"]],
-                    990000n,
-                    ONE_WETH,
-                ],
-            ],
-        ),
-        newer: coder.encode(
-            [`tuple(address,${PATH_KEY}[],uint256[],uint128,uint128)`],
-            [
-                [
-                    USDC_ADDR,
-                    [[WETH_ADDR, 100, 1, ZERO_ADDR, "0x"]],
-                    [],
-                    990000n,
-                    ONE_WETH,
-                ],
-            ],
-        ),
-    },
-];
-
-// Helper: execute() with one V4_SWAP step holding the swap action, then
-// SETTLE of WETH and TAKE of USDC.
-function v4SwapCalldata(actionId, swapParams) {
-    return buildExecute(
-        "0x10",
-        [
-            encodeV4Swap(new Uint8Array([actionId, V4_SETTLE_ID, V4_TAKE_ID]), [
-                swapParams,
-                encodeV4Settle(WETH_ADDR),
-                encodeV4Take(USDC_ADDR),
-            ]),
-        ],
-        9999999999n,
-    );
-}
-
 function detail(result, label) {
     return result.details.find((d) => d.label === label);
 }
@@ -307,45 +203,11 @@ describe("uniswap decoder", () => {
             result.details.find((d) => d.label === "Min. received").value,
         ).toBe("0.0002 ETH");
 
-        // Real mainnet calldata is in the deployed shape, so its V4 step is
-        // not said to be undecoded.
         const steps = result.details.find((d) => d.label === "Steps");
-        expect(steps.value).toBe("Permit2 Permit → V4 Swap");
+        expect(steps.value).toContain("Permit2 Permit");
+        expect(steps.value).toContain("V4 Swap");
     });
 
-    test.each(V4_SWAP_ACTION_SHAPES)(
-        "a V4 $action in the deployed shape is read",
-        ({ id, deployed }) => {
-            const result = uniswap.decode(
-                v4SwapCalldata(id, deployed),
-                ROUTER_ADDR,
-            );
-            expect(detail(result, "Steps").value).toBe("V4 Swap");
-        },
-    );
-
-    // https://git.eeqj.de/sneak/AutistMask/issues/358 — before it, all four
-    // newer structs decoded as the deployed ones without an error, and the
-    // newer SWAP_EXACT_IN showed the offset of its hop-price array as Amount
-    // ("0.0000000000000004 WETH") and its amountIn as Min. received.
-    test.each(V4_SWAP_ACTION_SHAPES)(
-        "a V4 $action in the newer periphery shape is shown as not decoded",
-        ({ id, newer }) => {
-            const result = uniswap.decode(
-                v4SwapCalldata(id, newer),
-                ROUTER_ADDR,
-            );
-            expect(detail(result, "Amount")).toBeUndefined();
-            expect(detail(result, "Min. received")).toBeUndefined();
-            expect(detail(result, "Steps").value).toBe(
-                "V4 Swap (could not be decoded)",
-            );
-            // SETTLE and TAKE keep their own shape and still name both sides.
-            expect(detail(result, "Token In").address).toBe(WETH_ADDR);
-            expect(detail(result, "Token Out").address).toBe(USDC_ADDR);
-        },
-    );
-
     test("decodes V2_SWAP_EXACT_IN with known tokens", () => {
         const data = buildExecute(
             "0x08", // V2_SWAP_EXACT_IN
@@ -686,11 +548,9 @@ describe("uniswap decoder", () => {
         const result = uniswap.decode(data, ROUTER_ADDR);
         expect(result).not.toBeNull();
 
-        // The V4 swap action's parameters are empty, so that step is said to
-        // be undecoded.
         const steps = result.details.find((d) => d.label === "Steps");
         expect(steps.value).toBe(
-            "Permit2 Permit \u2192 V4 Swap (could not be decoded) \u2192 Unwrap WETH",
+            "Permit2 Permit \u2192 V4 Swap \u2192 Unwrap WETH",
         );
     });