Use Electrs API instead of Electrum

package.json

@@ -36,6 +36,7 @@
     "bcrypto": "git+https://github.com/bcoin-org/bcrypto.git#semver:~5.3.0",
     "bufio": "^1.0.6",
     "electrum-client-js": "git+https://github.com/keep-network/electrum-client-js.git#v0.1.1",
+    "node-fetch": "^2.6.1",
     "p-wait-for": "^3.1.0",
     "web3-utils": "^1.2.8"
   },

src/BitcoinHelpers.js

@@ -290,7 +290,10 @@ const BitcoinHelpers = {
       throw new Error("Electrum client not configured.")
     }
 
-    const electrumClient = new ElectrumClient(BitcoinHelpers.electrumConfig)
+    const electrumClient = new ElectrumClient(
+      BitcoinHelpers.electrumConfig,
+      BitcoinHelpers.electrsConfig
+    )
 
     await electrumClient.connect()
 
@@ -661,26 +664,6 @@ const BitcoinHelpers = {
 
       return transaction.toRaw().toString("hex")
     },
-    /**
-     * Finds all transactions containing unspent outputs received
-     * by the `bitcoinAddress`.
-     *
-     * @param {string} bitcoinAddress Bitcoin address to check.
-     *
-     * @return {Promise<TransactionInBlock[]>} A promise to an array of
-     *         transactions with accompanying information about the output
-     *         position and value pointed at the specified receiver script.
-     *         Resolves with an empty array if no such transactions exist.
-     */
-    findAllUnspent: async function(bitcoinAddress) {
-      return await BitcoinHelpers.withElectrumClient(async electrumClient => {
-        const script = BitcoinHelpers.Address.toScript(bitcoinAddress)
-        return BitcoinHelpers.Transaction.findAllUnspentWithClient(
-          electrumClient,
-          script
-        )
-      })
-    },
     /**
      * Gets the confirmed balance of the `bitcoinAddress`.
      *
@@ -798,35 +781,6 @@ const BitcoinHelpers = {
       })
 
       return transactions.length > 0 ? transactions[0] : null
-    },
-    /**
-     * Finds all transactions to the given `receiverScript` using the
-     * given `electrumClient`.
-     *
-     * @param {ElectrumClient} electrumClient An already-initialized Electrum client.
-     * @param {string} receiverScript A receiver script.
-     *
-     * @return {Promise<TransactionInBlock[]>} A promise to an array of
-     *         transactions with accompanying information about the output
-     *         position and value pointed at the specified receiver script.
-     *         Resolves with an empty array if no such transactions exist.
-     */
-    findAllUnspentWithClient: async function(electrumClient, receiverScript) {
-      const unspentTransactions = await electrumClient.getUnspentToScript(
-        receiverScript
-      )
-
-      const result = []
-
-      for (const tx of unspentTransactions.reverse()) {
-        result.push({
-          transactionID: tx.tx_hash,
-          outputPosition: tx.tx_pos,
-          value: tx.value
-        })
-      }
-
-      return result
     }
   }
 }

src/lib/BitcoinSPV.js

@@ -1,10 +1,6 @@
 // JS implementation of merkle.py script from [summa-tx/bitcoin-spv] repository.
 //
 // [summa-tx/bitcoin-spv]: https://github.com/summa-tx/bitcoin-spv/
-import Hash256 from "bcrypto/lib/hash256-browser.js"
-import BcryptoMerkle from "bcrypto/lib/merkle.js"
-const { deriveRoot } = BcryptoMerkle
-
 /** @typedef { import("./ElectrumClient.js").default } ElectrumClient */
 
 /**
@@ -103,43 +99,4 @@ export class BitcoinSPV {
 
     return { proof: proof.toString("hex"), position: merkle.pos }
   }
-
-  /**
-   * Verifies merkle proof of transaction inclusion in the block. It expects proof
-   * as a concatenation of 32-byte values in a hexadecimal form. The proof should
-   * include the merkle tree branches, with transaction hash merkle tree root omitted.
-   * @param {string} proofHex hexadecimal representation of the proof
-   * @param {string} txHash Transaction hash.
-   * @param {number} index is transaction index in the block (1-indexed)
-   * @param {number} blockHeight Height of the block where transaction was confirmed.
-   * @return {Promise<boolean>} true if verification passed, else false
-   */
-  async verifyMerkleProof(proofHex, txHash, index, blockHeight) {
-    const proof = Buffer.from(proofHex, "hex")
-
-    // Retrieve merkle tree root.
-    const actualRoot = await this.client
-      .getMerkleRoot(blockHeight)
-      .catch(err => {
-        throw new Error(`failed to get merkle root: [${err}]`)
-      })
-
-    // Extract tree branches
-    const branches = []
-    for (let i = 0; i < Math.floor(proof.length / 32); i++) {
-      const branch = proof.slice(i * 32, (i + 1) * 32)
-      branches.push(branch)
-    }
-
-    // Derive expected root from branches and transaction.
-    const txHashBuffer = Buffer.from(txHash, "hex").reverse()
-    const expectedRoot = deriveRoot(Hash256, txHashBuffer, branches, index)
-
-    // Validate if calculated root is equal to the one returned from client.
-    if (actualRoot.equals(expectedRoot)) {
-      return true
-    } else {
-      return false
-    }
-  }
 }

src/lib/ElectrumClient.js

@@ -1,3 +1,4 @@
+import fetch from "node-fetch"
 import ElectrumClient from "electrum-client-js"
 import sha256 from "bcrypto/lib/sha256-browser.js"
 const { digest } = sha256
@@ -63,20 +64,26 @@ export default class Client {
   /**
    * Initializes Electrum Client instance with provided configuration.
    * @param {Config} config Electrum client connection configuration.
+   * @param {string} apiUrl Url to the electrs server
    */
-  constructor(config) {
+  constructor(config, apiUrl) {
+    // TODO: config will be removed once all ported
     this.electrumClient = new ElectrumClient(
       config.server,
       config.port,
       config.protocol,
       config.options
     )
+
+    this.apiUrl = apiUrl
+    // TODO: Check connectivity here
   }
 
   /**
    * Establish connection with the server.
    */
   async connect() {
+    // TODO: Remove when done with electrum client
     console.log("Connecting to electrum server...")
 
     await this.electrumClient.connect("tbtc", "1.4.2").catch(err => {
@@ -88,6 +95,7 @@ export default class Client {
    * Disconnect from the server.
    */
   async close() {
+    // TODO: Remove when done with electrum client
     console.log("Closing connection to electrum server...")
     this.electrumClient.close()
   }
@@ -106,17 +114,59 @@ export default class Client {
     return header.height
   }
 
+  /**
+   * Get details of the transaction.
+   * @param {string} txHash Hash of a transaction.
+   * @return {Promise<TransactionData>} Transaction details.
+   */
+  // async getTransaction(txHash) {
+  //   const tx = await this.electrumClient
+  //     .blockchain_transaction_get(txHash, true)
+  //     .catch(err => {
+  //       throw new Error(`failed to get transaction ${txHash}: [${err}]`)
+  //     })
+
+  //   return tx
+  // }
+
   /**
    * Get details of the transaction.
    * @param {string} txHash Hash of a transaction.
    * @return {Promise<TransactionData>} Transaction details.
    */
   async getTransaction(txHash) {
-    const tx = await this.electrumClient
-      .blockchain_transaction_get(txHash, true)
-      .catch(err => {
-        throw new Error(`failed to get transaction ${txHash}: [${err}]`)
+    const getTxUrl = `${this.apiUrl}/tx/${txHash}`
+    const tx = await fetch(getTxUrl).then(resp => {
+      if (!resp.ok) {
+        throw new Error(`failed to get transaction ${txHash} at ${getTxUrl}`)
+      }
+      return resp.json()
+    })
+
+    // append hex data to transaction
+    const getTxRawUrl = `${this.apiUrl}/tx/${txHash}/hex`
+    tx.hex = await fetch(getTxRawUrl).then(resp => {
+      if (!resp.ok) {
+        throw new Error(
+          `failed to get hex transaction ${txHash} at ${getTxRawUrl}`
+        )
+      }
+      return resp.text()
+    })
+
+    // append confirmations
+    if (tx.status.confirmed) {
+      const heightUrl = `${this.apiUrl}/blocks/tip/height`
+      const height = await fetch(heightUrl).then(resp => {
+        if (!resp.ok) {
+          throw new Error(`failed to get blockchain height at ${heightUrl}`)
+        }
+        return resp.text()
       })
+      tx.confirmations = parseInt(height) - tx.status.block_height + 1
+    } else {
+      tx.confirmations = 0
+    }
 
     return tx
   }
@@ -150,24 +200,6 @@ export default class Client {
    * @property {number} value The value of the unspent output in satoshis.
    */
 
-  /**
-   * Get unspent outputs sent to a script.
-   * @param {string} script ScriptPubKey in a hexadecimal format.
-   * @return {Promise<UnspentOutputData[]>} List of unspent outputs. It includes
-   *         transactions in the mempool.
-   */
-  async getUnspentToScript(script) {
-    const scriptHash = Client.scriptToHash(script)
-
-    const listUnspent = await this.electrumClient
-      .blockchain_scripthash_listunspent(scriptHash)
-      .catch(err => {
-        throw new Error(JSON.stringify(err))
-      })
-
-    return listUnspent
-  }
-
   /**
    * Get balance of a script.
    *
@@ -350,21 +382,6 @@ export default class Client {
     })
   }
 
-  /**
-   * Get merkle root hash for block.
-   * @param {number} blockHeight Block height.
-   * @return {Promise<Buffer>} Merkle root hash.
-   */
-  async getMerkleRoot(blockHeight) {
-    const header = await this.electrumClient
-      .blockchain_block_header(blockHeight)
-      .catch(err => {
-        throw new Error(`failed to get block header: [${err}]`)
-      })
-
-    return Buffer.from(header, "hex").slice(36, 68)
-  }
-
   /**
    * Get concatenated chunk of block headers built on a starting block.
    * @param {number} blockHeight Starting block height.
@@ -412,30 +429,6 @@ export default class Client {
       }))
   }
 
-  /**
-   * Finds index of output in a transaction for a given address.
-   * @param {string} txHash Hash of a transaction.
-   * @param {string} address Bitcoin address for the output.
-   * @return {Promise<number>} Index of output in the transaction (0-indexed).
-   */
-  async findOutputForAddress(txHash, address) {
-    const tx = await this.getTransaction(txHash).catch(err => {
-      throw new Error(`failed to get transaction: [${err}]`)
-    })
-
-    const outputs = tx.vout
-
-    for (let index = 0; index < outputs.length; index++) {
-      for (const a of outputs[index].scriptPubKey.addresses) {
-        if (a == address) {
-          return index
-        }
-      }
-    }
-
-    throw new Error(`output for address ${address} not found`)
-  }
-
   /**
    * Gets a history of all transactions the script is involved in.
    * @param {string} script The script in raw hexadecimal format.

test/BitcoinSPVTest.js

@@ -1,6 +1,6 @@
 import { BitcoinSPV } from "../src/lib/BitcoinSPV.js"
 import ElectrumClient from "../src/lib/ElectrumClient.js"
-import { electrumConfig } from "./config/network.js"
+import { electrsConfig, electrumConfig } from "./config/network.js"
 import { readFileSync } from "fs"
 import { assert } from "chai"
 
@@ -12,7 +12,10 @@ describe("BitcoinSPV", async () => {
   before(async () => {
     const txData = readFileSync("./test/data/tx.json", "utf8")
     tx = JSON.parse(txData)
-    electrumClient = new ElectrumClient(electrumConfig["testnet"])
+    electrumClient = new ElectrumClient(
+      electrumConfig["testnet"],
+      electrsConfig["testnet"]
+    )
     bitcoinSPV = new BitcoinSPV(electrumClient)
     await electrumClient.connect()
   })
@@ -37,21 +40,6 @@ describe("BitcoinSPV", async () => {
     assert.deepEqual(result, expectedResult)
   })
 
-  it("verifyMerkleProof", async () => {
-    const proofHex = tx.merkleProof
-    const index = tx.indexInBlock
-    const txHash = tx.hash
-    const blockHeight = tx.blockHeight
-    const result = await bitcoinSPV.verifyMerkleProof(
-      proofHex,
-      txHash,
-      index,
-      blockHeight
-    )
-
-    assert.isTrue(result)
-  })
-
   it("getMerkleProofInfo", async () => {
     const expectedResult = tx.merkleProof
     const expectedPosition = tx.indexInBlock