{ "id": "fVQBtrZ0NyAMHS3D", "name": "n8n Gateway for 1Shot Gas Station", "tags": [], "nodes": [ { "id": "80932427-585a-4ca3-8ee2-cf8aaf756aae", "name": "Sticky Note6", "type": "n8n-nodes-base.stickyNote", "position": [ -1888, 512 ], "parameters": { "width": 408, "height": 524, "content": "## x402 Payment Endpoint \n\nThis workflow lets the operator monetize swaps from ERC-20 tokens to native gas tokens on up to 100 different EVM blockchains via the [Li.Fi](https://li.fi/) protocol. \n\nThis workflow accepts an [x402 payment](https://www.x402.org/) header that will be used with the [1Shot Gas Station](https://github.com/uxlySoftware/1Shot-Gas-Station) smart contract which interacts with Li.Fi to swap EIP-3009 compatible tokens for native tokens (even cross-chain) without the user paying gas. \n\n1. Click on the webhook trigger and give the route a good name.\n2. Click on the \"Payment Token Configs\" and set up the desired tokens you want to support." }, "typeVersion": 1 }, { "id": "39a72092-252c-4e96-9ecb-0b271da73cd5", "name": "Sticky Note3", "type": "n8n-nodes-base.stickyNote", "position": [ -2176, 1088 ], "parameters": { "width": 840, "height": 596, "content": "## Example Curl Command\n\nThe workflow requires the following POST body parameters:\n\n- `fromChain` - the chain the user's EIP-3009 compatible tokens are on\n- `fromToken` - the address of the EIP-3009 compatible token to swap for native token\n- `fromAmount` - the amount of `fromToken` to swap\n- `fromAddress` - the user's address that holds the `fromToken`, must be the same as the `from` address in the `x-payment` header\n- `toChain` - the chain id of the target network to receive native token on\n\nYou can test [1Shot Gas Station](https://github.com/uxlysoftware/1shot-gas-station?tab=readme-ov-file#1shot-api-gas-station) endpoint with a command like this (be sure to use a [properly formatted x-payment header](https://1shotapi.com/tools) payload: \n\n```sh\n# swap out the URL here for you webhook URL endpoint\ncurl -X POST \\\n https://n8n.1shotapi.dev/webhook-test/refactored-gas-station \\\n -H \"x-payment: YOUR-BASE64-ENCODED-PAYMENT-PAYLOAD\" \\\n -H \"User-Agent: CustomUserAgent/1.0\" \\\n -H \"Accept: application/json\" \\\n -H \"Content-Type: application/json\" \\\n -d '{\n \"fromChain\": \"8453\",\n \"fromToken\": \"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913\",\n \"fromAmount\": \"100000000\",\n \"fromAddress\": \"0x55680c6b69d598c0b42f93cd53dff3d20e069b5b\",\n \"toChain\": \"43114\"\n }'\n```" }, "typeVersion": 1 }, { "id": "3e805ca4-f2f2-43db-9f50-ccffd5b770d2", "name": "Response: 200 - Payment Successful", "type": "n8n-nodes-base.respondToWebhook", "position": [ -64, 416 ], "parameters": { "options": { "responseCode": 200 }, "respondWith": "text", "responseBody": "={ \"transactionHash\": \"{{ $json.transactionHash }}\" }" }, "typeVersion": 1.3 }, { "id": "2708bdf9-fcbc-4d0b-b2c1-dbb1ba24e35f", "name": "1Shot API Submit & Wait", "type": "n8n-nodes-1shot.oneShotSynch", "position": [ -288, 512 ], "parameters": { "params": "={\n \"tokenAddress\": \"{{ $('Webhook').item.json.body.fromToken }}\",\n \"from\": \"{{ $('Validate & Verify X-Payment Header').item.json.decodedXPayment.payload.authorization.from }}\",\n \"value\": \"{{ $('Validate & Verify X-Payment Header').item.json.decodedXPayment.payload.authorization.value }}\",\n \"validAfter\": \"{{ $('Validate & Verify X-Payment Header').item.json.decodedXPayment.payload.authorization.validAfter }}\",\n \"validBefore\": \"{{ $('Validate & Verify X-Payment Header').item.json.decodedXPayment.payload.authorization.validBefore }}\",\n \"nonce\": \"{{ $('Validate & Verify X-Payment Header').item.json.decodedXPayment.payload.authorization.nonce }}\",\n \"v\": \"{{ $('Validate & Verify X-Payment Header').item.json.decodedXPayment.payload.v }}\",\n \"r\": \"{{ $('Validate & Verify X-Payment Header').item.json.decodedXPayment.payload.r }}\",\n \"s\": \"{{ $('Validate & Verify X-Payment Header').item.json.decodedXPayment.payload.s }}\",\n \"diamondCalldata\": \"{{ $('Fetch Li.Fi Quote').item.json.transactionRequest.data }}\"\n} ", "additionalFields": { "memo": "=Li.Fi swap - receiver: {{ $('Validate & Verify X-Payment Header').item.json.decodedXPayment.payload.authorization.from }}, token: {{ $('Webhook').item.json.body.fromToken }},amount: {{ $('Validate & Verify X-Payment Header').item.json.decodedXPayment.payload.authorization.value }}, chain: {{ $('Webhook').item.json.body.fromChain }}", "gasLimit": "={{ (parseInt($('Fetch Li.Fi Quote').item.json.transactionRequest.gasLimit, 16) + 100000).toString() }}" }, "contractMethodId": "={{ $('Payment Token Configs').item.json.paymentTokens[$('Validate & Verify POST Body').item.json.selectedToken].contractMethodId }}" }, "credentials": { "oneShotOAuth2Api": { "name": "" } }, "typeVersion": 1 }, { "id": "f7e3314b-5cab-4ca7-930e-d00b03dbc5b4", "name": "On Successful Payment Simulation", "type": "n8n-nodes-base.if", "position": [ -512, 608 ], "parameters": { "options": {}, "conditions": { "options": { "version": 2, "leftValue": "", "caseSensitive": true, "typeValidation": "strict" }, "combinator": "and", "conditions": [ { "id": "81c67679-e256-4fd2-bed7-8f4272c2392b", "operator": { "name": "filter.operator.equals", "type": "string", "operation": "equals" }, "leftValue": "={{ $json.success.toString() }}", "rightValue": "true" } ] } }, "typeVersion": 2.2 }, { "id": "acfea100-cd3a-4099-b828-c6fe0bcfc3ba", "name": "Simulate Payment", "type": "n8n-nodes-1shot.oneShot", "onError": "continueRegularOutput", "position": [ -736, 608 ], "parameters": { "params": "={\n \"tokenAddress\": \"{{ $('Webhook').item.json.body.fromToken }}\",\n \"from\": \"{{ $('Validate & Verify X-Payment Header').item.json.decodedXPayment.payload.authorization.from }}\",\n \"value\": \"{{ $('Validate & Verify X-Payment Header').item.json.decodedXPayment.payload.authorization.value }}\",\n \"validAfter\": \"{{ $('Validate & Verify X-Payment Header').item.json.decodedXPayment.payload.authorization.validAfter }}\",\n \"validBefore\": \"{{ $('Validate & Verify X-Payment Header').item.json.decodedXPayment.payload.authorization.validBefore }}\",\n \"nonce\": \"{{ $('Validate & Verify X-Payment Header').item.json.decodedXPayment.payload.authorization.nonce }}\",\n \"v\": \"{{ $('Validate & Verify X-Payment Header').item.json.decodedXPayment.payload.v }}\",\n \"r\": \"{{ $('Validate & Verify X-Payment Header').item.json.decodedXPayment.payload.r }}\",\n \"s\": \"{{ $('Validate & Verify X-Payment Header').item.json.decodedXPayment.payload.s }}\",\n \"diamondCalldata\": \"{{ $('Fetch Li.Fi Quote').item.json.transactionRequest.data }}\"\n} ", "gasLimit": "={{ (parseInt($('Fetch Li.Fi Quote').item.json.transactionRequest.gasLimit, 16) + 100000).toString() }}", "operation": "simulate", "contractMethodId": "={{ $('Payment Token Configs').item.json.paymentTokens[$('Validate & Verify POST Body').item.json.selectedToken].contractMethodId }}" }, "credentials": { "oneShotOAuth2Api": { "name": "" } }, "retryOnFail": true, "typeVersion": 1 }, { "id": "f5089506-8709-4942-9062-ac66fe091bbe", "name": "Webhook", "type": "n8n-nodes-base.webhook", "position": [ -1856, 896 ], "parameters": { "path": "=refactored-gas-station", "options": {}, "httpMethod": "POST", "responseMode": "responseNode" }, "typeVersion": 2 }, { "id": "bd5ce8db-39eb-4194-ab5f-cffc73eb9397", "name": "Fetch Li.Fi Quote", "type": "n8n-nodes-base.httpRequest", "onError": "continueErrorOutput", "position": [ -1184, 800 ], "parameters": { "url": "https://li.quest/v1/quote", "options": {}, "sendQuery": true, "sendHeaders": true, "queryParameters": { "parameters": [ { "name": "fromChain", "value": "={{ $('Webhook').item.json.body.fromChain }}" }, { "name": "fromToken", "value": "={{ $('Webhook').item.json.body.fromToken }}" }, { "name": "fromAddress", "value": "={{ $('Webhook').item.json.body.fromAddress }}" }, { "name": "toChain", "value": "={{ $('Webhook').item.json.body.toChain }}" }, { "name": "toToken", "value": "=0x0000000000000000000000000000000000000000" }, { "name": "toAddress", "value": "={{ $('Webhook').item.json.body.fromAddress }}" }, { "name": "slippage", "value": "0.05" }, { "name": "integrator", "value": "oneshot-gas-station" }, { "name": "=fromAmount", "value": "={{ $('Webhook').item.json.body.fromAmount }}" }, { "name": "allowBridges", "value": "gasZipBridge" }, { "name": "fee", "value": "0.005" } ] }, "headerParameters": { "parameters": [ { "name": "x-lifi-api-key" } ] } }, "retryOnFail": true, "typeVersion": 4.2 }, { "id": "a6e7de73-8e9c-49fb-b172-47e98695de17", "name": "Response: Missing or Invalid Request Body Params", "type": "n8n-nodes-base.respondToWebhook", "position": [ -1184, 992 ], "parameters": { "options": { "responseCode": 402 }, "respondWith": "json", "responseBody": "={\n \"x402Version\": \"1\",\n \"error\": \"{{ $('Validate & Verify POST Body').item.json.error.errorMessage }}\",\n \"accepts\": {{ JSON.stringify($('Validate & Verify POST Body').item.json.error.paymentConfigs) }}\n}" }, "typeVersion": 1.3 }, { "id": "b226d9e6-8963-4556-a6be-16b98486a326", "name": "Response: Failed to Get Quote", "type": "n8n-nodes-base.respondToWebhook", "position": [ -960, 896 ], "parameters": { "options": { "responseCode": 402 }, "respondWith": "json", "responseBody": "={\n \"x402Version\": \"1\",\n \"error\": {{ JSON.stringify($json.error.message) }},\n \"accepts\": {{ JSON.stringify($('Validate & Verify POST Body').item.json.accepts) }}\n}" }, "typeVersion": 1.3 }, { "id": "1f92afa5-ae85-41ce-9d2d-b868a37d5a03", "name": "Sticky Note", "type": "n8n-nodes-base.stickyNote", "position": [ -1280, 384 ], "parameters": { "color": 5, "width": 272, "height": 576, "content": "## Fetch Swap Route & Quote form Li.Fi\n\nThis block fetches a quote from the Li.Fi Route API that retuns the `callData` needed to call the Li.FI Diamond Proxy contract.\n\nYou'll need to get a Li.Fi API key so you don't get rate limited and put it in the Li.Fi node for the `x-lifi-api-key`.\n\nAdditionally, if you want to collect integrator fees, you'll need to change the `integrator` to point at your Li.Fi integrator account." }, "typeVersion": 1 }, { "id": "466fed72-b4fa-4f50-ab71-e3701d2e88a8", "name": "Sticky Note1", "type": "n8n-nodes-base.stickyNote", "position": [ -784, 352 ], "parameters": { "color": 6, "width": 672, "height": 416, "content": "## Use 1Shot API to Simulate and Submit the Swap \n\n[1Shot API](https://1shotapi.com) handles simulating the transaction and submitting it the the appropriate blockchain network. " }, "typeVersion": 1 }, { "id": "fd5beb2b-9129-4d89-8ec2-9e20c1d303a4", "name": "Sticky Note2", "type": "n8n-nodes-base.stickyNote", "position": [ -1264, 1184 ], "parameters": { "width": 752, "height": 352, "content": "## Payment Token Configs\n\nYou must edit the \"Payment Token Configs\" node with the tokens you wish to support for swaps.\n\nYou need:\n\n1. The token address\n2. The EVM chain id\n3. The x402 name of the `toChain` (like `base` or `avalanche`)\n3. The token `name`\n4. Token `version`\n5. The `contractMethodId` of the `callDiamondWithEIP3009SignatureToNative` method that you've imported into your 1Shot API account on the same chain as the token. " }, "typeVersion": 1 }, { "id": "fefb995e-d5ee-4a4f-99ee-6e2c90d08d9d", "name": "Validate & Verify X-Payment Header", "type": "n8n-nodes-base.code", "onError": "continueErrorOutput", "position": [ -960, 704 ], "parameters": { "jsCode": "const payTo = $('Payment Token Configs').first().json.gasStationContract;\nconst timeOut = $('Payment Token Configs').first().json.timeOut;\nconst paymentTokens = $('Payment Token Configs').first().json.paymentTokens;\nconst selectedToken = $('Validate & Verify POST Body').first().json.selectedToken;\nconst gasLimit = $('Fetch Li.Fi Quote').first().json.transactionRequest.gasLimit;\nconst estimate = {\n swapFee: $('Fetch Li.Fi Quote').first().json.estimate.feeCosts[0].amountUSD,\n gasCostUSD: $('Fetch Li.Fi Quote').first().json.estimate.gasCosts[0].amountUSD,\n toAmountUSD: $('Fetch Li.Fi Quote').first().json.estimate.toAmountUSD,\n toAmountETH: $('Fetch Li.Fi Quote').first().json.estimate.toAmount,\n gasEstimateETH: $('Fetch Li.Fi Quote').first().json.estimate.gasCosts[0].estimate,\n waitTime: $('Fetch Li.Fi Quote').first().json.estimate.executionDuration\n}\n\n\n// this function will split the signature from the user into r,s & v components\nfunction splitSignature(sigHex) {\n // Remove \"0x\" prefix if present\n const hex = sigHex.startsWith(\"0x\") ? sigHex.slice(2) : sigHex;\n\n // Convert hex to byte array\n const bytes = new Uint8Array(hex.length / 2);\n for (let i = 0; i < bytes.length; i++) {\n bytes[i] = parseInt(hex.substr(i * 2, 2), 16);\n }\n\n if (bytes.length !== 65) {\n throw new Error(`Invalid signature length: got ${bytes.length} bytes`);\n }\n\n // Convert byte ranges to hex strings\n const toHex = (arr) =>\n \"0x\" + Array.from(arr).map(b => b.toString(16).padStart(2, \"0\")).join(\"\");\n\n const r = toHex(bytes.slice(0, 32));\n const s = toHex(bytes.slice(32, 64));\n\n // Normalize v\n let v = bytes[64];\n if (v === 0) v = 27;\n else if (v === 1) v = 28;\n else if (v !== 27 && v !== 28 && v >= 35) {\n v = (v & 1) ? 27 : 28; // EIP-155\n }\n\n const vHex = \"0x\" + v.toString(16).padStart(2, \"0\");\n\n return { r, s, v: vHex };\n}\n\n// this will make sure our x-payment header contains all necessary components\nfunction validateXPayment(obj) {\n // Define the expected structure and types\n const requiredShape = {\n x402Version: \"number\",\n scheme: \"string\",\n network: \"string\",\n payload: {\n authorization: {\n from: \"string\",\n to: \"string\",\n value: \"string\",\n validAfter: \"string\",\n validBefore: \"string\",\n nonce: \"string\"\n },\n signature: \"string\"\n }\n };\n\n let missing = [];\n function checkShape(expected, actual, path) {\n for (const key in expected) {\n const currentPath = path ? path + \".\" + key : key;\n\n if (!(key in actual)) {\n missing.push(\"Missing field: \" + currentPath);\n } else if (typeof expected[key] === \"object\") {\n if (typeof actual[key] !== \"object\" || actual[key] === null) {\n missing.push(\"Invalid type at \" + currentPath + \": expected object\");\n } else {\n checkShape(expected[key], actual[key], currentPath);\n }\n } else {\n if (typeof actual[key] !== expected[key]) {\n missing.push(\n \"Invalid type at \" + currentPath +\n \": expected \" + expected[key] +\n \", got \" + typeof actual[key]\n );\n }\n }\n }\n }\n\n checkShape(requiredShape, obj, \"\");\n if (missing.length > 0) {\n return missing.join(\"; \");\n }\n return \"valid\";\n}\n\n// this function will ensure the x-payment header is for one of our supported\n// networks, is for the correct amount, and pays the right address\nfunction verifyPaymentDetails(obj, config, payTo) {\n const errors = [];\n\n // 1. Check that network exists in config\n const network = obj.network;\n const configEntry = Object.values(config).find(\n (entry) => entry.network.toLowerCase() === (network || \"\").toLowerCase()\n );\n\n if (!configEntry) {\n errors.push(\"Invalid or unsupported network: \" + network);\n }\n\n // 2. Check value >= maxAmountRequired\n if (configEntry) {\n const required = BigInt(configEntry.maxAmountRequired);\n let actual;\n\n try {\n actual = BigInt(obj.payload.authorization.value);\n } catch (e) {\n errors.push(\"Invalid value: must be numeric string\");\n }\n\n if (typeof actual !== \"undefined\" && actual < required) {\n errors.push(\n `Value too low: got ${actual}, requires at least ${required}`\n );\n }\n }\n\n // 3. Check 'to' matches payTo (case-insensitive)\n const toAddr = obj.payload?.authorization?.to;\n if (!toAddr) {\n errors.push(\"Missing 'to' field in authorization\");\n } else if (toAddr.toLowerCase() !== payTo.toLowerCase()) {\n errors.push(`Invalid 'to' address: expected ${payTo}, got ${toAddr}`);\n }\n\n return errors.length > 0 ? errors.join(\"; \") : \"valid\";\n}\n\n\n\n// try to decode the x-payment header if it exists\ntry {\n // Decode the x-payment header from base64\n const xPaymentHeader = $('Webhook').first().json.headers['x-payment'];\n const decodedXPayment = Buffer.from(xPaymentHeader, 'base64').toString('utf-8');\n // Parse the decoded value into a JSON object\n const decodedXPaymentJson = JSON.parse(decodedXPayment);\n\n const validation = validateXPayment(decodedXPaymentJson)\n\n if (validation !== \"valid\") {\n return { \n error: {\n errorMessage: JSON.stringify(validation), \n paymentConfigs: [$('Validate & Verify POST Body').first().json.accepts[selectedToken]]\n } \n };\n }\n\n const verification = verifyPaymentDetails(decodedXPaymentJson, [paymentTokens[selectedToken]], payTo[paymentTokens[selectedToken].chain]);\n\n if (verification !== \"valid\") {\n return {\n error: {\n errorMessage: JSON.stringify(verification),\n paymentConfigs: [$('Validate & Verify POST Body').first().json.accepts[selectedToken]]\n }\n }\n }\n\n // make sure the quote amount is the same as the authorization amount or the tx will revert\n if (BigInt(decodedXPaymentJson[\"payload\"][\"authorization\"][\"value\"]) !== BigInt($('Payment Token Configs').first().json.body.fromAmount)) {\n return {\n error: {\n errorMessage: JSON.stringify(`fromAmount (${$('Payment Token Configs').first().json.body.fromAmount}) not equal to authorization value (${decodedXPaymentJson[\"payload\"][\"authorization\"][\"value\"]})`),\n paymentConfigs: [$('Validate & Verify POST Body').first().json.accepts[selectedToken]]\n }\n }\n }\n\n // make sure the fromAddress is the same address the authorization\n if (decodedXPaymentJson[\"payload\"][\"authorization\"][\"from\"].toLowerCase() !== $('Payment Token Configs').first().json.body.fromAddress.toLowerCase()) {\n return {\n error: {\n errorMessage: JSON.stringify(`fromAddress (${$('Payment Token Configs').first().json.body.fromAddress}) not equal to authorization address (${decodedXPaymentJson[\"payload\"][\"authorization\"][\"from\"]})`),\n paymentConfigs: [$('Validate & Verify POST Body').first().json.accepts[selectedToken]]\n }\n }\n }\n\n \n // Add the parsed JSON object to the input\n $input.first().json.decodedXPayment = decodedXPaymentJson;\n\n const splitSig = splitSignature(decodedXPaymentJson.payload.signature);\n $input.first().json.decodedXPayment.payload.r = splitSig.r;\n $input.first().json.decodedXPayment.payload.s = splitSig.s;\n $input.first().json.decodedXPayment.payload.v = splitSig.v;\n\n $input.first().json.contractMethodId = Object.values(paymentTokens).find(\n (entry) => entry.network.toLowerCase() === (decodedXPaymentJson.network || \"\").toLowerCase()\n ).contractMethodId;\n\n $input.first().json.gasLimit = gasLimit;\n\n $input.first().json.paymentConfigs = [($('Validate & Verify POST Body').first().json.accepts)[selectedToken]];\n\n return $input.all();\n} catch (error) {\n // Return an error object if the token format is invalid\n return {\n error: {\n errorMessage: JSON.stringify(estimate), \n paymentConfigs: [($('Validate & Verify POST Body').first().json.accepts)[selectedToken]]\n } \n };\n}\n\nreturn $input.all();\n\n" }, "typeVersion": 2 }, { "id": "dad98431-090b-49f3-b35f-81ee8344ecad", "name": "Payment Token Configs", "type": "n8n-nodes-base.code", "onError": "continueRegularOutput", "position": [ -1632, 896 ], "parameters": { "jsCode": "// put your X402 resource description here\nconst resourceDescription = \"Swap stablecoins for native tokens cross-chain.\"; \n// the amount of time in seconds the authorization should be good for\nconst timeOut = 60;\n\n// the gas station contract is the same on base, avalanche, and arbitrum\n// Latest version is V2: https://github.com/UXlySoftware/1shot-gas-station\n// This is the \"payTo\" address for x402\nconst gasStationContract = {\n \"8453\": \"0x949EBD97b770bcA5146F24f4F9De815b3F457680\",\n \"43114\": \"0x949EBD97b770bcA5146F24f4F9De815b3F457680\",\n \"42161\": \"0x949EBD97b770bcA5146F24f4F9De815b3F457680\",\n \"59144\": \"0x87435C81ef97D608E426f1f0e2185410C9Ba362A\",\n}\n\n// Got to 1Shot Prompts (https://app.1shotapi.com/1shot-prompts) and import the \n// callDiamondWithEIP3009SignatureToNative function, get its contract method id\n// and put it here\nconst gasStationContractMethodIds = {\n \"base\": \"\",\n \"arbitrum\": \"\",\n \"avalanche\": \"\",\n \"linea\": \"\"\n}\n\n// configure addiotional payment tokens here\nconst paymentTokens = [\n {\n tokenAddress: \"0x833589fcd6edb6e08f4c7c32d4f71b54bda02913\",\n maxAmountRequired: 1000,\n chain: \"8453\",\n name: \"USD Coin\",\n version: \"2\",\n network: \"base\",\n contractMethodId: gasStationContractMethodIds[\"base\"]\n },\n {\n tokenAddress: \"0xb97ef9ef8734c71904d8002f8b6bc66dd9c48a6e\",\n maxAmountRequired: 1000000,\n chain: \"43114\",\n name: \"USD Coin\",\n version: \"2\",\n network: \"avalanche\",\n contractMethodId: gasStationContractMethodIds[\"avalanche\"]\n },\n {\n tokenAddress: \"0xaf88d065e77c8cc2239327c5edb3a432268e5831\",\n maxAmountRequired: 100000,\n chain: \"42161\",\n name: \"USD Coin\",\n version: \"2\",\n network: \"arbitrum\",\n contractMethodId: gasStationContractMethodIds[\"arbitrum\"]\n },\n {\n tokenAddress: \"0xACYOUR_TWILIO_ACCOUNT_SID2435DA\",\n maxAmountRequired: 10000,\n chain: \"59144\",\n name: \"MetaMask USD\",\n version: \"1\",\n network: \"linea\",\n contractMethodId: gasStationContractMethodIds[\"linea\"]\n },\n {\n tokenAddress: \"0x46850aD61C2B7d64d08c9C754F45254596696984\",\n maxAmountRequired: 10000,\n chain: \"42161\",\n name: \"PayPal USD\",\n version: \"1\",\n network: \"arbitrum\",\n contractMethodId: gasStationContractMethodIds[\"arbitrum\"]\n }\n];\n\n$input.first().json.resourceDescription = resourceDescription;\n$input.first().json.timeOut = timeOut;\n$input.first().json.paymentTokens = paymentTokens;\n$input.first().json.gasStationContract = gasStationContract;\n\nreturn $input.all();" }, "typeVersion": 2 }, { "id": "dd5f6fd4-f74b-48cd-ab8a-66852214929c", "name": "Validate & Verify POST Body", "type": "n8n-nodes-base.code", "onError": "continueErrorOutput", "position": [ -1408, 896 ], "parameters": { "jsCode": "const timeOut = $input.first().json.timeOut;\nconst resourceDescription = $input.first().json.resourceDescription;\nconst paymentTokens = $input.first().json.paymentTokens;\n\n// this helper function will convert our simple payment configs into an x402 \n// error response \nfunction transformConfig(config, payTo, maxAmountRequired, timeout, resource, resourceDescription) {\n return Object.values(config).map(entry => ({\n scheme: \"exact\",\n network: entry.network,\n maxAmountRequired: maxAmountRequired,\n resource: resource, \n description: resourceDescription,\n mimeType: \"\",\n payTo: payTo,\n maxTimeoutSeconds: timeout, // passed in as argument\n asset: entry.tokenAddress,\n extra: {\n name: entry.name,\n version: entry.version\n }\n }));\n}\n\nfunction requireField(name, value) {\n if (value === null || value === undefined || value === \"\") {\n throw new Error(`Missing or empty required field: ${name}`);\n }\n return value;\n}\n\n// this will look up if the requested payment token is one we support\nfunction findPaymentTokenIndex(paymentTokens, fromToken, fromChain) {\n const index = paymentTokens.findIndex(\n (token) =>\n token.tokenAddress.toLowerCase() === (fromToken || \"\").toLowerCase() &&\n token.chain === String(fromChain)\n );\n\n if (index === -1) {\n throw new Error(\n `No matching payment token found for token=${fromToken}, chain=${fromChain}`\n );\n }\n\n return index;\n}\n\nlet fromChain;\nlet fromToken;\nlet fromAmount;\nlet fromAddress;\nlet toChain;\nlet accepts; \n\n// Validate the required input parameters\ntry {\n fromChain = requireField(\"fromChain\", $input.first().json.body.fromChain);\n fromToken = requireField(\"fromToken\", $input.first().json.body.fromToken);\n fromAmount = requireField(\"fromAmount\", $input.first().json.body.fromAmount);\n fromAddress = requireField(\"fromAddress\", $input.first().json.body.fromAddress);\n toChain = requireField(\"toChain\", $input.first().json.body.toChain);\n \n accepts = transformConfig(paymentTokens, $input.first().json.gasStationContract[$('Webhook').first().json.body.fromChain], $('Webhook').first().json.body.fromAmount,timeOut, $input.first().json.webhookUrl, resourceDescription);\n $input.first().json.accepts = accepts;\n} catch (error) {\n console.log(\"asdf: \", accepts)\n return { \n error: {\n errorMessage: \"Missing POST Body Parameters - requires: fromChain, fromToken, fromAmount, fromAddress, tochain\", \n paymentConfigs: (fromAddress && fromAddress !== \"\") ? transformConfig(paymentTokens, fromAddress, $('Webhook').first().json.body.fromAmount,timeOut, $input.first().json.webhookUrl, resourceDescription) : []\n } \n };\n}\n\n// Be ensure the fromToken is one we accept\ntry {\n // find the token & get its contract method id\n const selectedToken = findPaymentTokenIndex(paymentTokens, fromToken, fromChain);\n $input.first().json.selectedToken = selectedToken;\n} catch (error) {\n return { \n error: {\n errorMessage: \"fromToken & fromChain must match one of the supported payment tokens.\", \n paymentConfigs: accepts\n } \n };\n}\n\nreturn $input.all();\n\n" }, "typeVersion": 2 }, { "id": "f8f41400-ca0f-410d-a53b-f41d2730c9cc", "name": "Response: No X-Payment Header2", "type": "n8n-nodes-base.respondToWebhook", "position": [ -736, 800 ], "parameters": { "options": { "responseCode": 402 }, "respondWith": "json", "responseBody": "={\n \"x402Version\": \"1\",\n \"error\": {{ $('Validate & Verify X-Payment Header').item.json.error.errorMessage }},\n \"accepts\": {{ JSON.stringify($('Validate & Verify X-Payment Header').item.json.error.paymentConfigs) }}\n}" }, "typeVersion": 1.3 }, { "id": "2a50dbb1-5078-4b0d-9415-23c418c68b81", "name": "Sticky Note4", "type": "n8n-nodes-base.stickyNote", "position": [ -2560, 496 ], "parameters": { "color": 6, "width": 616, "height": 524, "content": "## x402 Payment Endpoint \n\nThis workflow fragment can be used to monetize any workflow you can build in n8n by accepting stablecoin payments via an API call.\n\nLearn more about the [x402 payment](https://www.x402.org/) protocol. \n\nWatch the [YouTube tutorial](https://youtu.be/SHb5WkggQR4) for a complete walkthrough.\n@[youtube](SHb5WkggQR4)" }, "typeVersion": 1 }, { "id": "b05cea5a-9e77-4f85-b98a-2a7c40b2d12b", "name": "Response: Verify Failed", "type": "n8n-nodes-base.respondToWebhook", "position": [ -288, 800 ], "parameters": { "options": { "responseCode": 402 }, "respondWith": "json", "responseBody": "={\n \"x402Version\": \"1\",\n \"error\": {{ JSON.stringify($('Simulate Payment').item.json.error.message) }},\n \"accepts\": {{ JSON.stringify($('Validate & Verify POST Body').item.json.accepts) }}\n}" }, "typeVersion": 1.3 }, { "id": "f81d3b66-2a3a-4a8f-936f-41da1d86127e", "name": "Response: Settle Failed", "type": "n8n-nodes-base.respondToWebhook", "position": [ -64, 608 ], "parameters": { "options": { "responseCode": 402 }, "respondWith": "json", "responseBody": "={\n \"x402Version\": \"1\",\n \"error\": \"Payment Settlement Failed\",\n \"accepts\": {{ JSON.stringify($('Validate & Verify POST Body').item.json.accepts) }}\n}" }, "typeVersion": 1.3 } ], "active": false, "settings": { "executionOrder": "v1" }, "versionId": "b62f044b-b5cb-4fef-a6c6-445915dbed9a", "connections": { "Webhook": { "main": [ [ { "node": "Payment Token Configs", "type": "main", "index": 0 } ] ] }, "Simulate Payment": { "main": [ [ { "node": "On Successful Payment Simulation", "type": "main", "index": 0 } ], [] ] }, "Fetch Li.Fi Quote": { "main": [ [ { "node": "Validate & Verify X-Payment Header", "type": "main", "index": 0 } ], [ { "node": "Response: Failed to Get Quote", "type": "main", "index": 0 } ] ] }, "Payment Token Configs": { "main": [ [ { "node": "Validate & Verify POST Body", "type": "main", "index": 0 } ], [] ] }, "1Shot API Submit & Wait": { "main": [ [ { "node": "Response: 200 - Payment Successful", "type": "main", "index": 0 } ], [ { "node": "Response: Settle Failed", "type": "main", "index": 0 } ] ] }, "Validate & Verify POST Body": { "main": [ [ { "node": "Fetch Li.Fi Quote", "type": "main", "index": 0 } ], [ { "node": "Response: Missing or Invalid Request Body Params", "type": "main", "index": 0 } ] ] }, "On Successful Payment Simulation": { "main": [ [ { "node": "1Shot API Submit & Wait", "type": "main", "index": 0 } ], [ { "node": "Response: Verify Failed", "type": "main", "index": 0 } ] ] }, "Validate & Verify X-Payment Header": { "main": [ [ { "node": "Simulate Payment", "type": "main", "index": 0 } ], [ { "node": "Response: No X-Payment Header2", "type": "main", "index": 0 } ] ] } } }