From 7adcf3b154669d9d1a0a66d5e15dabfbf6618180 Mon Sep 17 00:00:00 2001
From: Richard Moore <github@ricmoo.com>
Date: Mon, 31 May 2021 18:16:30 -0400
Subject: [PATCH] Fixed ENS namehash with leading and trailing dots (#1605).

---
 packages/hash/src.ts/namehash.ts    | 12 ++++++---
 packages/tests/src.ts/test-utils.ts | 39 ++++++++++++++++++++++++++---
 2 files changed, 44 insertions(+), 7 deletions(-)

diff --git a/packages/hash/src.ts/namehash.ts b/packages/hash/src.ts/namehash.ts
index d4b683bd2a..856a0be5a8 100644
--- a/packages/hash/src.ts/namehash.ts
+++ b/packages/hash/src.ts/namehash.ts
@@ -27,16 +27,20 @@ export function isValidName(name: string): boolean {
 export function namehash(name: string): string {
     /* istanbul ignore if */
     if (typeof(name) !== "string") {
-        logger.throwArgumentError("invalid address - " + String(name), "name", name);
+        logger.throwArgumentError("invalid ENS name; not a string", "name", name);
     }
 
+    let current = name;
     let result: string | Uint8Array = Zeros;
-    while (name.length) {
-        const partition = name.match(Partition);
+    while (current.length) {
+        const partition = current.match(Partition);
+        if (partition == null || partition[2] === "") {
+            logger.throwArgumentError("invalid ENS address; missing component", "name", name);
+        }
         const label = toUtf8Bytes(nameprep(partition[3]));
         result = keccak256(concat([result, keccak256(label)]));
 
-        name = partition[2] || "";
+        current = partition[2] || "";
     }
 
     return hexlify(result);
diff --git a/packages/tests/src.ts/test-utils.ts b/packages/tests/src.ts/test-utils.ts
index fe25bcf97a..61adbd955c 100644
--- a/packages/tests/src.ts/test-utils.ts
+++ b/packages/tests/src.ts/test-utils.ts
@@ -242,11 +242,44 @@ describe('Test Namehash', function() {
         });
     });
 
-    it("isValidName", function() {
-        assert.ok(ethers.utils.isValidName("ricmoo.eth"));
+    const goodNames = [
+        "ricmoo.eth",
+        "foo",
+        "foo.bar",
+    ];
+
+    const badNames = [
+        ".",
+        "..",
+        "ricmoo..eth",
+        "ricmoo...eth",
+        ".foo",
+        "foo.",
+    ];
 
+    // The empty string is not a valid name, but has the zero hash
+    // as its namehash, which may be used for recursive purposes
+    it("empty ENS name", function() {
         assert.ok(!ethers.utils.isValidName(""));
-        assert.ok(!ethers.utils.isValidName("ricmoo..eth"));
+    });
+
+    goodNames.forEach((name) => {
+        it(`ENS namehash ok - ${ name }`, function() {
+            assert.ok(ethers.utils.isValidName(name));
+            ethers.utils.namehash(name);
+        });
+    });
+
+    badNames.forEach((name) => {
+        it(`ENS namehash fails - ${ name }`, function() {
+            assert.ok(!ethers.utils.isValidName(name));
+            assert.throws(() => {
+                const namehash = ethers.utils.namehash(name);
+                console.log(name, namehash);
+            }, (error: Error) => {
+                return !!error.message.match(/invalid ENS address/);
+            });
+        });
     });
 });