Nialexsan/univ3 connectors by nialexsan · Pull Request #47 · onflow/FlowActions

nialexsan · 2025-10-06T19:48:04Z

Uniswap v3 SwapRouterV2 connector
EVM ABI helpers for tuple encoding

…ctors

sisyphusSmiling

I think this connector needs some more testing and perhaps a different approach (EVM-side helper) until tuple encoding is natively available. The lack of testing and application-level byte packing creates potential security & bug surface area and likely lots of computation overhead we can optimize.

sisyphusSmiling · 2025-10-31T18:16:21Z

cadence/contracts/connectors/evm/UniswapV3SwapConnectors.cdc

In general, I think this contract will be low hanging fruit for optimization. Without the ability to encode a tuple from Cadence (see onflow/flow-go#8020), packing the bytes is quite inefficient and difficult to test.

Second to native encoding/decoding, I think having a helper contract in EVM to which we can pass/get natively encodable/decodable types will be preferred to this approach. But I suppose it's not a blocker for initial tracer deployment & setup.

sisyphusSmiling · 2025-10-31T18:31:34Z

cadence/contracts/connectors/evm/UniswapV3SwapConnectors.cdc

+    access(all) fun encodeTuple_bytes_addr_u256_u256(
+        path: [UInt8],
+        recipient: EVM.EVMAddress,
+        amountOne: UInt256,
+        amountTwo: UInt256
+    ): [UInt8] {


Param comments would be helpful here

sisyphusSmiling · 2025-10-31T18:32:43Z

cadence/contracts/utils/EVMAbiHelpers.cdc

+    // ===== Utilities: concat & padding =====
+    access(all) fun concat(_ parts: [[UInt8]]): [UInt8] {
+        var out: [UInt8] = []
+        for p in parts { out = out.concat(p) }


appendAll would probably be more performant here

sisyphusSmiling · 2025-10-31T18:35:37Z

cadence/contracts/utils/EVMAbiHelpers.cdc

+        let hex: [String] = ["0","1","2","3","4","5","6","7","8","9","a","b","c","d","e","f"]
+        var out = ""
+        var i = 0
+        while i < bytes.length {
+            let b = bytes[i]
+            out = out.concat(hex[Int(b / 16)]).concat(hex[Int(b % 16)])
+            i = i + 1
+        }
+        return out


can't this just be return String.encodeHex(bytes)

sisyphusSmiling · 2025-10-31T18:36:38Z

cadence/contracts/utils/EVMAbiHelpers.cdc

+
+    // Represents one ABI argument chunk
+    access(all) struct ABIArg {
+        access(all) let isDynamic: Bool


It's not clear to me what is meant by dynamic here

sisyphusSmiling · 2025-10-31T19:56:27Z

cadence/contracts/connectors/evm/UniswapV3SwapConnectors.cdc

+            // exactInput((bytes,address,uint256,uint256)) selector = 0xb858183f
+            let selector: [UInt8] = [0xb8, 0x58, 0x18, 0x3f]


It's not apparent that the selector values match the commented selector which on its own need to match the .sol contract selector. This seems to work:

Suggested change

// exactInput((bytes,address,uint256,uint256)) selector = 0xb858183f

let selector: [UInt8] = [0xb8, 0x58, 0x18, 0x3f]

// exactInput((bytes,address,uint256,uint256)) selector = 0xb858183f

let selector: [UInt8] = EVM.encodeABIWithSignature("exactInput((bytes,address,uint256,uint256))", [])

sisyphusSmiling · 2025-10-31T19:57:38Z

cadence/contracts/connectors/evm/UniswapV3SwapConnectors.cdc

+        access(self) fun _firstUint256(_ data: [UInt8]): UInt256 {
+            let decoded = EVM.decodeABI(types: [Type<UInt256>()], data: data)
+            if decoded.length > 0 { return decoded[0] as! UInt256 }
+            return UInt256(0)
+        }


I don't see this used anywhere

Suggested change

access(self) fun _firstUint256(_ data: [UInt8]): UInt256 {

let decoded = EVM.decodeABI(types: [Type<UInt256>()], data: data)

if decoded.length > 0 { return decoded[0] as! UInt256 }

return UInt256(0)

}

sisyphusSmiling · 2025-10-31T19:59:00Z

cadence/contracts/connectors/evm/UniswapV3SwapConnectors.cdc

+            let SEL_SLOT0: [UInt8]        = [0x38, 0x50, 0xc7, 0xbd]
+            let SEL_LIQUIDITY: [UInt8]    = [0x1a, 0x68, 0x65, 0x02]
+            let SEL_FEE: [UInt8]          = [0xdd, 0xca, 0x3f, 0x43]
+            let SEL_TICK_BITMAP: [UInt8]  = [0x53, 0x39, 0xc2, 0x96]
+            let SEL_TICKS: [UInt8]        = [0xf3, 0x0d, 0xba, 0x93]
+            let SEL_TICK_SPACING: [UInt8] = [0xd0, 0xc9, 0x3a, 0x7c]


Same comment as elsewhere - it's difficult to catch any mismatch against the desired selector. Suggest decoding the signature for each using EVM.encodeABIWithSignature() using empty data array.

sisyphusSmiling · 2025-10-31T20:04:39Z

cadence/contracts/connectors/evm/UniswapV3SwapConnectors.cdc

+            return EVM.EVMAddress(bytes: addrBytes)
+        }
+
+        access(self) fun getMaxAmount(zeroForOne: Bool): UInt256 {


It's going to be very difficult to test these nested function definitions directly. If we do continue down the path of Cadence-side byte packing, we'll want to move these to a scope that we can test and validate directly.

sisyphusSmiling · 2025-10-31T20:06:17Z

cadence/contracts/connectors/evm/UniswapV3SwapConnectors.cdc

+        access(self) fun to20(_ b: [UInt8]): [UInt8; 20] {
+            if b.length != 20 { panic("to20: need exactly 20 bytes") }
+            return [
+                b[0],  b[1],  b[2],  b[3],  b[4],
+                b[5],  b[6],  b[7],  b[8],  b[9],
+                b[10], b[11], b[12], b[13], b[14],
+                b[15], b[16], b[17], b[18], b[19]
+            ]
+        }


Can just use b.toConstantSized<[UInt8; 20]>()!.

ref

cadence/tests/UniswapV3SwapConnectors_test.cdc

Co-authored-by: Giovanni Sanchez <108043524+sisyphusSmiling@users.noreply.github.com>

sisyphusSmiling

Approving to unblock. Once revisiting, I'm fairly confident the production version will require a redeployment

nialexsan added 8 commits September 26, 2025 11:27

stub univ3 swap connectors

da32fa7

tweak univ3 connector

ee6dbb9

tweak contract

b44b908

working swap shim

fbfdc49

fix quoteIn

bbc9259

swap connector and helpers

b1e6bde

fix typo

ac92ef5

fix renaming

0db9f8f

nialexsan marked this pull request as ready for review October 9, 2025 16:01

nialexsan requested a review from sisyphusSmiling October 9, 2025 16:03

nialexsan added 6 commits October 22, 2025 21:48

max amount

25ac07f

fix deposit cap logic

172771b

update deps

a1666f2

init with factory address

7276c77

limit radius

d42d58f

Merge remote-tracking branch 'origin/main' into nialexsan/univ3-conne…

c8c888e

…ctors

sisyphusSmiling reviewed Oct 31, 2025

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cadence/tests/UniswapV3SwapConnectors_test.cdc Outdated Show resolved Hide resolved

Update cadence/tests/UniswapV3SwapConnectors_test.cdc

a3c3f31

Co-authored-by: Giovanni Sanchez <108043524+sisyphusSmiling@users.noreply.github.com>

sisyphusSmiling approved these changes Oct 31, 2025

View reviewed changes

nialexsan mentioned this pull request Oct 31, 2025

address comments in PR #47 #52

Open

nialexsan merged commit ffc1645 into main Oct 31, 2025
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		// exactInput((bytes,address,uint256,uint256)) selector = 0xb858183f
		let selector: [UInt8] = [0xb8, 0x58, 0x18, 0x3f]

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nialexsan commented Oct 6, 2025 •

edited

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