From 243beffa4f83c910f5f1c5e0554531e5dcf3ab93 Mon Sep 17 00:00:00 2001
From: Richard Moore <github@ricmoo.com>
Date: Fri, 12 Feb 2021 18:25:25 -0500
Subject: [PATCH] Prevent unconfigured ENS names from making an init tx
 (#1290).

---
 packages/abstract-signer/src.ts/index.ts | 11 ++++++++-
 packages/tests/src.ts/test-providers.ts  | 31 ++++++++++++++++++++++++
 2 files changed, 41 insertions(+), 1 deletion(-)

diff --git a/packages/abstract-signer/src.ts/index.ts b/packages/abstract-signer/src.ts/index.ts
index 6f018d5521..9a77e64cf9 100644
--- a/packages/abstract-signer/src.ts/index.ts
+++ b/packages/abstract-signer/src.ts/index.ts
@@ -191,7 +191,16 @@ export abstract class Signer {
 
         const tx: Deferrable<TransactionRequest> = await resolveProperties(this.checkTransaction(transaction))
 
-        if (tx.to != null) { tx.to = Promise.resolve(tx.to).then((to) => this.resolveName(to)); }
+        if (tx.to != null) {
+            tx.to = Promise.resolve(tx.to).then(async (to) => {
+                if (to == null) { return null; }
+                const address = await this.resolveName(to);
+                if (address == null) {
+                    logger.throwArgumentError("provided ENS name resolves to null", "tx.to", to);
+                }
+                return address;
+            });
+        }
         if (tx.gasPrice == null) { tx.gasPrice = this.getGasPrice(); }
         if (tx.nonce == null) { tx.nonce = this.getTransactionCount("pending"); }
 
diff --git a/packages/tests/src.ts/test-providers.ts b/packages/tests/src.ts/test-providers.ts
index a40066fc74..09bd8c84d2 100644
--- a/packages/tests/src.ts/test-providers.ts
+++ b/packages/tests/src.ts/test-providers.ts
@@ -1113,3 +1113,34 @@ describe("Test Events", function() {
         await testBlockEvent(provider);
     });
 });
+
+describe("Bad ENS resolution", function() {
+    const provider = providerFunctions[0].create("ropsten");
+
+    it("signer has a bad ENS name", async function() {
+        this.timeout(300000);
+
+        const wallet = new ethers.Wallet(ethers.utils.id("random-wallet"), provider);
+
+        // If "to" is specified as an ENS name, it cannot resolve to null
+        try {
+            const tx = await wallet.sendTransaction({ to: "junk", value: 1 });
+            console.log("TX", tx);
+        } catch (error) {
+            assert.ok(error.argument === "tx.to" && error.value === "junk");
+        }
+
+        // But promises that resolve to null are ok
+        const tos = [ null, Promise.resolve(null) ];
+        for (let i = 0; i < tos.length; i++) {
+            const to = tos[i];
+            try {
+                const tx = await wallet.sendTransaction({ to, value: 1 });
+                console.log("TX", tx);
+            } catch (error) {
+                assert.ok(error.code === "INSUFFICIENT_FUNDS");
+            }
+        }
+    });
+
+});