From f8087ae39ce7631425b6b4763347a4f9618f9730 Mon Sep 17 00:00:00 2001
From: Richard Moore <github@ricmoo.com>
Date: Fri, 3 Jan 2020 18:20:15 -0500
Subject: [PATCH] Added utility function to compute CREATE2 addresses (#697).

---
 src.ts/utils/address.ts | 46 ++++++++++++++++++++++++++++++-
 src.ts/utils/index.ts   |  3 +-
 tests/test-account.js   | 61 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 108 insertions(+), 2 deletions(-)

diff --git a/src.ts/utils/address.ts b/src.ts/utils/address.ts
index 63a3fa9b4..c6501c79b 100644
--- a/src.ts/utils/address.ts
+++ b/src.ts/utils/address.ts
@@ -3,7 +3,7 @@
 // We use this for base 36 maths
 import BN from 'bn.js';
 
-import { arrayify, stripZeros, hexlify } from './bytes';
+import { arrayify, concat, stripZeros, hexlify } from './bytes';
 import { BigNumber } from './bignumber';
 import { keccak256 } from './keccak256';
 import { encode } from './rlp';
@@ -140,3 +140,47 @@ export function getContractAddress(transaction: { from: string, nonce: Arrayish
     ])).substring(26));
 }
 
+export type Create2Options = {
+    from: string,
+    salt: Arrayish,
+    initCode?: Arrayish,
+    initCodeHash?: Arrayish,
+};
+
+// See: https://eips.ethereum.org/EIPS/eip-1014
+export function getCreate2Address(options: Create2Options): string {
+    let initCodeHash = options.initCodeHash;
+    if (options.initCode) {
+        if (initCodeHash) {
+            if (keccak256(options.initCode) !== initCodeHash) {
+                errors.throwError("initCode/initCodeHash mismatch", errors.INVALID_ARGUMENT, {
+                    arg: "options", value: options
+                });
+            }
+        } else {
+            initCodeHash = keccak256(options.initCode);
+        }
+    }
+
+    if (!initCodeHash) {
+        errors.throwError("missing initCode or initCodeHash", errors.INVALID_ARGUMENT, {
+            arg: "options", value: options
+        });
+    }
+
+    const from = getAddress(options.from);
+
+    const salt = arrayify(options.salt);
+    if (salt.length !== 32) {
+        errors.throwError("invalid salt", errors.INVALID_ARGUMENT, {
+            arg: "options", value: options
+        });
+    }
+
+    return getAddress("0x" + keccak256(concat([
+        "0xff",
+        from,
+        salt,
+        initCodeHash
+    ])).substring(26));
+}
diff --git a/src.ts/utils/index.ts b/src.ts/utils/index.ts
index f2a82e05d..f224ba6d6 100644
--- a/src.ts/utils/index.ts
+++ b/src.ts/utils/index.ts
@@ -1,7 +1,7 @@
 'use strict';
 
 import { AbiCoder, defaultAbiCoder, formatSignature, formatParamType, parseSignature, parseParamType } from './abi-coder';
-import { getAddress, getContractAddress, getIcapAddress } from './address';
+import { getAddress, getContractAddress, getCreate2Address, getIcapAddress } from './address';
 import * as base64 from './base64';
 import { BigNumber, bigNumberify } from './bignumber';
 import { arrayify, concat, hexDataSlice, hexDataLength, hexlify, hexStripZeros, hexZeroPad, isHexString, joinSignature, padZeros, splitSignature, stripZeros } from './bytes';
@@ -103,6 +103,7 @@ export {
     getAddress,
     getIcapAddress,
     getContractAddress,
+    getCreate2Address,
 
     formatEther,
     parseEther,
diff --git a/tests/test-account.js b/tests/test-account.js
index e78bf251a..64ea7bc8d 100644
--- a/tests/test-account.js
+++ b/tests/test-account.js
@@ -36,3 +36,64 @@ describe('Checksum and ICAP address generation', function() {
         });
     });
 });
+
+describe("Create2 Address Generation", function() {
+    var tests = [
+        {
+            name: "Example 0",
+            from: "0x0000000000000000000000000000000000000000",
+            salt: "0x0000000000000000000000000000000000000000000000000000000000000000",
+            initCode: "0x00",
+            expected: "0x4D1A2e2bB4F88F0250f26Ffff098B0b30B26BF38"
+        },
+        {
+            name: "Example 1",
+            from: "0xdeadbeef00000000000000000000000000000000",
+            salt: "0x0000000000000000000000000000000000000000000000000000000000000000",
+            initCode: "0x00",
+            expected: "0xB928f69Bb1D91Cd65274e3c79d8986362984fDA3"
+        },
+        {
+            name: "Example 2",
+            from: "0xdeadbeef00000000000000000000000000000000",
+            salt: "0x000000000000000000000000feed000000000000000000000000000000000000",
+            initCode: "0x00",
+            expected: "0xD04116cDd17beBE565EB2422F2497E06cC1C9833"
+        },
+        {
+            name: "Example 3",
+            from: "0x0000000000000000000000000000000000000000",
+            salt: "0x0000000000000000000000000000000000000000000000000000000000000000",
+            initCode: "0xdeadbeef",
+            expected: "0x70f2b2914A2a4b783FaEFb75f459A580616Fcb5e"
+        },
+        {
+            name: "Example 4",
+            from: "0x00000000000000000000000000000000deadbeef",
+            salt: "0x00000000000000000000000000000000000000000000000000000000cafebabe",
+            initCode: "0xdeadbeef",
+            expected: "0x60f3f640a8508fC6a86d45DF051962668E1e8AC7"
+        },
+        {
+            name: "Example 5",
+            from: "0x00000000000000000000000000000000deadbeef",
+            salt: "0x00000000000000000000000000000000000000000000000000000000cafebabe",
+            initCode: "0xdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeef",
+            expected: "0x1d8bfDC5D46DC4f61D6b6115972536eBE6A8854C"
+        },
+        {
+            name: "Example 6",
+            from: "0x0000000000000000000000000000000000000000",
+            salt: "0x0000000000000000000000000000000000000000000000000000000000000000",
+            initCode: "0x",
+            expected: "0xE33C0C7F7df4809055C3ebA6c09CFe4BaF1BD9e0"
+        },
+    ];
+
+    tests.forEach(function(test) {
+        it("correctly computes the Create2 address - " + test.name, function() {
+            const address = ethers.utils.getCreate2Address(test);
+            assert.equal(address, test.expected, "correctly computes Create2 address");
+        });
+    });
+});