feat: add support for base paymaster

.eslintrc.json

@@ -12,6 +12,7 @@
   ],
   "rules": {
     "@typescript-eslint/no-non-null-assertion": "off",
-    "@typescript-eslint/no-var-requires": "off"
+    "@typescript-eslint/no-var-requires": "off",
+    "@typescript-eslint/no-unused-vars": "off"
   }
 }

src/gasless-provider.ts

@@ -8,7 +8,7 @@ import { PimlicoBundlerClient } from 'permissionless/clients/pimlico';
 import { UserOperation } from 'permissionless/types';
 import { getSenderAddress, signUserOperationHashWithECDSA } from 'permissionless';
 import * as constants from '../src/constants';
-import { BasePaymaster } from './paymasters';
+import { Paymaster } from './paymasters';
 import { PartialBy } from 'viem/types/utils';
 import { SponsorUserOperationReturnType } from 'permissionless/actions/pimlico';
 
@@ -24,7 +24,7 @@ export class GaslessProvider extends ProviderWrapper {
     protected readonly _wrappedProvider: EIP1193Provider,
     public readonly chain: string,
     protected readonly bundlerClient: PimlicoBundlerClient,
-    protected readonly paymasterClient: BasePaymaster,
+    protected readonly paymasterClient: Paymaster,
     protected readonly publicClient: ReturnType<typeof createPublicClient>,
     protected readonly _initCode: `0x${string}`,
     protected readonly senderAddress: `0x${string}`,
@@ -41,7 +41,7 @@ export class GaslessProvider extends ProviderWrapper {
     _wrappedProvider: EIP1193Provider,
     chain: string,
     bundlerClient: PimlicoBundlerClient,
-    paymasterClient: BasePaymaster,
+    paymasterClient: Paymaster,
     publicClient: ReturnType<typeof createPublicClient>,
   ) {
     // NOTE: Bundlers can support many entry points, but currently they only support one, we use this method so if they ever add a new one the entry point will still work
@@ -146,7 +146,7 @@ export class GaslessProvider extends ProviderWrapper {
     };
 
     const paymasterAndData: `0x${string}` | SponsorUserOperationReturnType =
-      await this.paymasterClient.sponsorUserOperation(userOperation, this._entryPoint);
+      await this.paymasterClient.sponsorUserOperation(userOperation, this._entryPoint, this.bundlerClient);
 
     let sponsoredUserOperation: UserOperation;
 

src/paymaster.ts

@@ -1,13 +1,15 @@
 import { PaymasterType } from './types';
-import { BasePaymaster } from './paymasters/BasePaymaster';
+import { Paymaster } from './paymasters/Paymaster';
 import * as Pm from './paymasters';
 
-export function createPaymasterClient(paymasterType: PaymasterType, paymasterUrl: string): BasePaymaster {
+export function createPaymasterClient(paymasterType: PaymasterType, paymasterUrl: string): Paymaster {
   switch (paymasterType) {
     case PaymasterType.Pimlico:
       return new Pm.PimlicoPaymaster(paymasterUrl);
     case PaymasterType.StackUp:
       return new Pm.StackUpPaymaster(paymasterUrl);
+    case PaymasterType.Base:
+      return new Pm.BasePaymaster(paymasterUrl);
 
     default:
       throw new Error(`Unknown paymaster type ${paymasterType}`);

src/paymasters/BasePaymaster.ts

@@ -1,19 +1,83 @@
 import { SponsorUserOperationReturnType } from 'permissionless/actions/pimlico';
 import { PartialUserOperation } from '../types';
+import { Paymaster } from './Paymaster';
+import { PimlicoBundlerClient } from 'permissionless/clients/pimlico';
 
-export class BasePaymaster {
-  public endpoint: string;
-
+export class BasePaymaster extends Paymaster {
   constructor(endpoint: string) {
-    this.endpoint = endpoint;
+    super(endpoint);
   }
 
-  // eslint-disable
   public async sponsorUserOperation(
-    userOp: PartialUserOperation,
+    userOperation: PartialUserOperation,
     entryPoint: `0x${string}`,
+    bundlerClient: PimlicoBundlerClient,
   ): Promise<`0x${string}` | SponsorUserOperationReturnType> {
-    throw new Error('This is a base class and should not be called directly.');
+    const userOp = this.convertBigIntsToString(userOperation);
+
+    const chainIdAsNumber = await bundlerClient.chainId();
+    const chainId = '0x' + chainIdAsNumber.toString(16);
+
+    const data = {
+      id: 1,
+      jsonrpc: '2.0',
+      method: 'eth_paymasterAndDataForEstimateGas',
+      params: [userOp, entryPoint, chainId],
+    };
+
+    const response = await fetch(this.endpoint, {
+      method: 'POST',
+      body: JSON.stringify(data),
+      headers: { 'Content-Type': 'application/json' },
+    });
+
+    const json = await response.json();
+
+    const paymasterAndData = json.result;
+
+    const gasConfig = await bundlerClient.estimateUserOperationGas({
+      userOperation: Object.assign(userOperation, { paymasterAndData: paymasterAndData }),
+      entryPoint,
+    });
+
+    // Adding gas headroom for safety margin to ensure paymaster signs for enough gas based on estimations
+    gasConfig.preVerificationGas = gasConfig.preVerificationGas + 2000n;
+    gasConfig.verificationGasLimit = gasConfig.verificationGasLimit + 4000n;
+
+    const stringifyGasConfig = this.convertBigIntsToString(gasConfig);
+
+    const finalCallData = {
+      id: 1,
+      jsonrpc: '2.0',
+      method: 'eth_paymasterAndDataForUserOperation',
+      params: [Object.assign(userOp, stringifyGasConfig), entryPoint, chainId],
+    };
+
+    const finalResponse = await fetch(this.endpoint, {
+      method: 'POST',
+      body: JSON.stringify(finalCallData),
+      headers: { 'Content-Type': 'application/json' },
+    });
+
+    const finalJson = await finalResponse.json();
+
+    return {
+      ...gasConfig,
+      paymasterAndData: finalJson.result,
+    };
+  }
+
+  // Helper function to convert bigints to hexadecimal strings, which is what base api expects
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  private convertBigIntsToString(obj: any) {
+    for (const key in obj) {
+      if (typeof obj[key] === 'bigint') {
+        // Convert 0n to '0x', and other BigInts to their string representation
+        // NOTE: base expects gas values to be non-zero, but nonce might be zero so we need to be sure to exclude it
+        obj[key] = obj[key] === 0n && key !== 'nonce' ? '0x1' : '0x' + obj[key].toString(16);
+      }
+    }
+
+    return obj;
   }
-  // eslint-enable
 }

src/paymasters/Paymaster.ts

@@ -0,0 +1,19 @@
+import { SponsorUserOperationReturnType } from 'permissionless/actions/pimlico';
+import { PartialUserOperation } from '../types';
+import { PimlicoBundlerClient } from 'permissionless/clients/pimlico';
+
+export class Paymaster {
+  public endpoint: string;
+
+  constructor(endpoint: string) {
+    this.endpoint = endpoint;
+  }
+
+  public async sponsorUserOperation(
+    userOp: PartialUserOperation,
+    entryPoint: `0x${string}`,
+    bundlierClient: PimlicoBundlerClient,
+  ): Promise<`0x${string}` | SponsorUserOperationReturnType> {
+    throw new Error('This is a base class and should not be called directly.');
+  }
+}

src/paymasters/PimlicoPaymaster.ts

@@ -1,10 +1,11 @@
-import { BasePaymaster } from './BasePaymaster';
+import { Paymaster } from './Paymaster';
 import { PartialUserOperation } from '../types';
 import { http } from 'viem';
 import { createPimlicoPaymasterClient } from 'permissionless/clients/pimlico';
 import { SponsorUserOperationReturnType } from 'permissionless/actions/pimlico';
+import { PimlicoBundlerClient } from 'permissionless/clients/pimlico';
 
-export class PimlicoPaymaster extends BasePaymaster {
+export class PimlicoPaymaster extends Paymaster {
   public paymasterClient: ReturnType<typeof createPimlicoPaymasterClient>;
 
   constructor(endpoint: string) {
@@ -17,6 +18,7 @@ export class PimlicoPaymaster extends BasePaymaster {
   public async sponsorUserOperation(
     userOperation: PartialUserOperation,
     entryPoint: `0x${string}`,
+    bundlerClient: PimlicoBundlerClient,
   ): Promise<`0x${string}` | SponsorUserOperationReturnType> {
     return await this.paymasterClient.sponsorUserOperation({
       userOperation,

src/paymasters/StackUpPaymaster.ts

@@ -1,11 +1,12 @@
-import { BasePaymaster } from './BasePaymaster';
+import { Paymaster } from './Paymaster';
 import { PartialUserOperation } from '../types';
 import { http } from 'viem';
 import { createStackupPaymasterClient } from 'permissionless/clients/stackup';
 import { SponsorUserOperationReturnType } from 'permissionless/actions/stackup';
 import { StackupPaymasterContext } from 'permissionless/types/stackup';
+import { PimlicoBundlerClient } from 'permissionless/clients/pimlico';
 
-export class StackUpPaymaster extends BasePaymaster {
+export class StackUpPaymaster extends Paymaster {
   public paymasterClient: ReturnType<typeof createStackupPaymasterClient>;
 
   constructor(endpoint: string) {
@@ -18,6 +19,7 @@ export class StackUpPaymaster extends BasePaymaster {
   public async sponsorUserOperation(
     userOperation: PartialUserOperation,
     entryPoint: `0x${string}`,
+    bundlerClient: PimlicoBundlerClient,
   ): Promise<`0x${string}` | SponsorUserOperationReturnType> {
     return await this.paymasterClient.sponsorUserOperation({
       userOperation,

src/paymasters/index.ts

@@ -1,3 +1,4 @@
-export * from './BasePaymaster';
+export * from './Paymaster';
 export * from './PimlicoPaymaster';
 export * from './StackUpPaymaster';
+export * from './BasePaymaster';

src/types.ts

@@ -10,7 +10,7 @@ export type PartialUserOperation = {
 
 export enum PaymasterType {
   Pimlico = 'pimlico',
-  Biconomy = 'biconomy',
+  Base = 'base',
   StackUp = 'stackup',
 }