@colony/purser-metamask/es/staticMethods.js.flow

A javascript library to interact with a Metamask based Ethereum wallet

/* @flow */

import { Transaction as EthereumTx } from 'ethereumjs-tx';
import BigNumber from 'bn.js';
import { awaitTx } from 'await-transaction-mined';

import { warning } from '@colony/purser-core/utils';
import {
  hexSequenceValidator,
  addressValidator,
  safeIntegerValidator,
} from '@colony/purser-core/validators';
import {
  addressNormalizer,
  hexSequenceNormalizer,
} from '@colony/purser-core/normalizers';
import {
  transactionObjectValidator,
  messageVerificationObjectValidator,
  messageOrDataValidator,
  getChainDefinition,
} from '@colony/purser-core/helpers';

import { HEX_HASH_TYPE } from '@colony/purser-core/defaults';

import { methodCaller } from './helpers';
import {
  getTransaction as getTransactionMethodLink,
  signTransaction as signTransactionMethodLink,
  signMessage as signMessageMethodLink,
  verifyMessage as verifyMessageMethodLink,
} from './methodLinks';

import { STD_ERRORS } from './defaults';
import { staticMethods as messages } from './messages';

import type { Web3TransactionType } from './flowtypes';

/**
 * Get a transaction, with a workaround for some providers not returning
 * a pending transaction.
 *
 * If the transaction was not immediately returned, it's possible that
 * Infura is being used, and it isn't responding to `eth_getTransaction`
 * in the expected way (i.e. it isn't returning anything because the
 * transaction is not yet confirmed).
 *
 * This method uses a web3 0.20.x-compatible means of waiting for the
 * transaction to be confirmed (which will resolve to the receipt,
 * or reject if the transaction could not be confirmed.
 *
 * This can probably be removed when MetaMask has its own workaround.
 * See https://github.com/MetaMask/metamask-extension/issues/6704
 */
export const getTransaction = async (
  transactionHash: string,
): Promise<Web3TransactionType> => {
  const receiptPromise = awaitTx(global.web3, transactionHash, {
    blocksToWait: 1,
  });

  const transaction = await getTransactionMethodLink(transactionHash);
  if (transaction) {
    return transaction;
  }

  await receiptPromise;

  return getTransactionMethodLink(transactionHash);
};

export const signTransactionCallback = (
  chainId: number,
  resolve: (string) => void,
  reject: (Error) => void,
) =>
  async (error: Error, transactionHash: string) => {
    try {
      if (error) {
        /*
         * If the user cancels signing the transaction we still throw,
         * but we customize the message.
         */
        if (error.message.includes(STD_ERRORS.CANCEL_TX_SIGN)) {
          throw new Error(messages.cancelTransactionSign);
        }
        throw new Error(error.message);
      }

      /*
       * Validate that the signature hash is in the correct format
       */
      hexSequenceValidator(transactionHash);
      /*
       * Add the `0x` prefix to the signed transaction hash
       */
      const normalizedTransactionHash: string = hexSequenceNormalizer(
        transactionHash,
      );
      /*
       * Get signed transaction object with transaction hash using Web3
       * Include signature + any values MetaMask may have changed.
       */
      const {
        gas,
        gasPrice: signedGasPrice,
        input: signedData,
        nonce,
        r,
        s,
        to: signedTo,
        v,
        value: signedValue,
      } = await getTransaction(normalizedTransactionHash);
      /*
       * RLP encode (to hex string) with ethereumjs-tx, prefix with
       * `0x` and return. Convert to BN all the numbers-as-strings.
       */
      const signedTransaction = new EthereumTx(
        {
          data: signedData,
          gasLimit: new BigNumber(gas),
          gasPrice: new BigNumber(signedGasPrice),
          nonce: new BigNumber(nonce),
          r,
          s,
          to: signedTo,
          v,
          value: new BigNumber(signedValue),
        },
        getChainDefinition(chainId),
      );
      const serializedSignedTransaction = signedTransaction
        .serialize()
        .toString(HEX_HASH_TYPE);
      const normalizedSignedTransaction = hexSequenceNormalizer(
        serializedSignedTransaction,
      );
      return resolve(normalizedSignedTransaction);
    } catch (caughtError) {
      return reject(caughtError);
    }
  };

/**
 * Sign (and send) a transaction object and return the serialized signature (as a hex string)
 *
 * @TODO Refactor to only sign the transaction
 * This is only after Metamask will allow us that functionality (see below)
 *
 * Metamask doesn't currently allow us to sign a transaction without also broadcasting it to
 * the network. See this issue for context:
 * https://github.com/MetaMask/metamask-extension/issues/3475
 *
 * @method signTransaction
 *
 * @param {string} from the sender address (provided by the Wallet instance)
 * @param {bigNumber} gasPrice gas price for the transaction in WEI (as an instance of bigNumber), defaults to 9000000000 (9 GWEI)
 * @param {bigNumber} gasLimit gas limit for the transaction (as an instance of bigNumber), defaults to 21000
 * @param {number} nonce the nonce to use for the transaction (as a number)
 * @param {string} to the address to which to the transaction is sent
 * @param {bigNumber} value the value of the transaction in WEI (as an instance of bigNumber), defaults to 1
 * @param {string} inputData data appended to the transaction (as a `hex` string)
 *
 * All the above params are sent in as props of an object.
 *
 * @return {Promise<string>} the hex signature string
 */
export const signTransaction = async ({
  from,
  nonce: manualNonce,
  ...transactionObject
}: Object = {}): Promise<string | void> => {
  const {
    chainId,
    gasPrice,
    gasLimit,
    to,
    value,
    inputData,
  } = transactionObjectValidator(transactionObject);
  addressValidator(from);
  /*
   * Metamask auto-sets the nonce based on the next one available. You can manually
   * override it, but it's best to omit it.
   *
   * So we only validate if there is one, otherwise we just pass undefined
   * to the transaction object.
   *
   * We also notify (in dev mode) the user about not setting the nonce.
   */
  if (manualNonce) {
    safeIntegerValidator(manualNonce);
    warning(messages.dontSetNonce);
  }
  /*
   * We must check for the Metamask injected in-page proxy every time we
   * try to access it. This is because something can change it from the time
   * of last detection until now.
   */
  return methodCaller(
    /*
     * @TODO Move into own (non-anonymous) method
     * This way we could better test it
     */
    () =>
      new Promise((resolve, reject) =>
        signTransactionMethodLink(
          Object.assign(
            {},
            {
              from: addressNormalizer(from),
              /*
              * We don't need to normalize these three values since Metamask accepts
              * number values directly, so we don't need to convert them to hex
              */
              value: value.toString(),
              gas: gasLimit.toString(),
              gasPrice: gasPrice.toString(),
              data: hexSequenceNormalizer(inputData),
              chainId,
              /*
               * Most likely this value is `undefined`, but that is good (see above)
               */
              nonce: manualNonce,
            },
            /*
             * Only send (and normalize) the destination address if one was
             * provided in the initial transaction object.
             */
            to ? { to: addressNormalizer(to) } : {},
          ),
          signTransactionCallback(chainId, resolve, reject),
        ),
      ),
    messages.cannotSendTransaction,
  );
};

export const signMessageCallback = (
  resolve: (string | void) => void,
  reject: (Error) => void,
) =>
  (error: Error, messageSignature: string) => {
    try {
      if (error) {
        /*
         * If the user cancels signing the message we still throw,
         * but we customize the message
         */
        if (error.message.includes(STD_ERRORS.CANCEL_MSG_SIGN)) {
          throw new Error(messages.cancelMessageSign);
        }
        throw new Error(error.message);
      }

      /*
       * Validate that the signature is in the correct format
       */
      hexSequenceValidator(messageSignature);
      /*
       * Add the `0x` prefix to the message's signature
       */
      const normalizedSignature: string = hexSequenceNormalizer(
        messageSignature,
      );
      return resolve(normalizedSignature);
    } catch (caughtError) {
      return reject(caughtError);
    }
  };

/**
 * Sign a message and return the signature. Useful for verifying identities.
 *
 * @method signMessage
 *
 * @param {string} currentAddress The current selected address (in the UI)
 * @param {string} message the message you want to sign
 * @param {any} messageData the message data (hex string or UInt8Array) you want to sign
 *
 * All the above params are sent in as props of an {object.
 *
 * @return {Promise<string>} The signed message `hex` string (wrapped inside a `Promise`)
 */
export const signMessage = async ({
  currentAddress,
  message,
  messageData,
}: Object = {}): Promise<string | void> => {
  addressValidator(currentAddress);
  const toSign = messageOrDataValidator({ message, messageData });
  /*
   * We must check for the Metamask injected in-page proxy every time we
   * try to access it. This is because something can change it from the time
   * of last detection until now.
   */
  return methodCaller(
    /*
     * @TODO Move into own (non-anonymous) method
     * This way we could better test it
     */
    () =>
      new Promise((resolve, reject) => {
        /*
         * Sign the message. This will prompt the user via Metamask's UI
         */
        signMessageMethodLink(
          /*
           * Ensure the hex string has the `0x` prefix
           */
          hexSequenceNormalizer(
            /*
             * We could really do with default Flow types for Buffer...
             */
            /* $FlowFixMe */
            Buffer.from(toSign).toString(HEX_HASH_TYPE),
          ),
          currentAddress,
          signMessageCallback(resolve, reject),
        );
      }),
    messages.cannotSignMessage,
  );
};

export const verifyMessageCallback = (
  currentAddress: string,
  resolve: (boolean) => void,
  reject: (Error) => void,
) =>
  (error: Error, recoveredAddress: string) => {
    try {
      if (error) {
        throw new Error(error.message);
      }

      /*
       * Validate that the recovered address is correct
       */
      addressValidator(recoveredAddress);
      /*
       * Add the `0x` prefix to the recovered address
       */
      const normalizedRecoveredAddress: string = addressNormalizer(
        recoveredAddress,
      );
      /*
       * Add the `0x` prefix to the current address
       */
      const normalizedCurrentAddress: string = addressNormalizer(
        currentAddress,
      );
      return resolve(
        normalizedRecoveredAddress === normalizedCurrentAddress,
      );
    } catch (caughtError) {
      return reject(caughtError);
    }
  };

/**
 * Verify a signed message. Useful for verifying identity. (In conjunction with `signMessage`)
 *
 * @method verifyMessage
 *
 * @param {string} message The message to verify if it was signed correctly
 * @param {string} signature The message signature as a `hex` string (you usually get this via `signMessage`)
 * @param {string} currentAddress The current selected address (in the UI)
 *
 * All the above params are sent in as props of an object.
 *
 * @return {Promise<boolean>} A boolean to indicate if the message/signature pair are valid (wrapped inside a `Promise`)
 */
export const verifyMessage = async ({
  currentAddress,
  ...messageVerificationObject
}: Object = {}) => {
  /*
   * Validate the current address
   */
  addressValidator(currentAddress);
  /*
   * Validate the rest of the pros using the core helper
   */
  const { message, signature } = messageVerificationObjectValidator(
    messageVerificationObject,
  );
  /*
   * We must check for the Metamask injected in-page proxy every time we
   * try to access it. This is because something can change it from the time
   * of last detection until now.
   */
  return methodCaller(
    /*
     * @TODO Move into own (non-anonymous) method
     * This way we could better test it
     */
    () =>
      new Promise((resolve, reject) => {
        /*
         * Verify the message
         */
        verifyMessageMethodLink(
          message,
          /*
           * Ensure the signature has the `0x` prefix
           */
          hexSequenceNormalizer(signature),
          verifyMessageCallback(currentAddress, resolve, reject),
        );
      }),
    messages.cannotSignMessage,
  );
};