From 119725680e1cc1417ecb348fa06335d810c57add Mon Sep 17 00:00:00 2001
From: Felipe Selmo <fselmo2@gmail.com>
Date: Fri, 8 Apr 2022 14:58:06 -0600
Subject: [PATCH] Validate forward resolution for reverse resolution by default

- As outlined in the warning in the ENS docs, for the reverse resolution of a name for an address to be accurate, the forward resolution address must also match. Source at the time of this commit is here: https://docs.ens.domains/dapp-developer-guide/resolving-names#reverse-resolution.
---
 ens/main.py                    |  6 +++++-
 newsfragments/2420.feature.rst |  1 +
 tests/ens/test_setup_name.py   | 11 +++++++++++
 3 files changed, 17 insertions(+), 1 deletion(-)
 create mode 100644 newsfragments/2420.feature.rst

diff --git a/ens/main.py b/ens/main.py
index 5cc4e98fb6..465f640af6 100644
--- a/ens/main.py
+++ b/ens/main.py
@@ -152,7 +152,11 @@ def name(self, address: ChecksumAddress) -> Optional[str]:
         :type address: hex-string
         """
         reversed_domain = address_to_reverse_domain(address)
-        return self.resolve(reversed_domain, get='name')
+        name = self.resolve(reversed_domain, get='name')
+
+        # To be absolutely certain of the name, via reverse resolution, the address must match in
+        # the forward resolution
+        return name if to_checksum_address(address) == self.address(name) else None
 
     def setup_address(
         self,
diff --git a/newsfragments/2420.feature.rst b/newsfragments/2420.feature.rst
new file mode 100644
index 0000000000..f81eb8df89
--- /dev/null
+++ b/newsfragments/2420.feature.rst
@@ -0,0 +1 @@
+For ``ENS.name()``, validate that the forward resolution returns the same address as provided by the user as per the ENS documentation recommendation for Reverse Resolution.
diff --git a/tests/ens/test_setup_name.py b/tests/ens/test_setup_name.py
index 26fb0a7e3b..e81b73d9ae 100644
--- a/tests/ens/test_setup_name.py
+++ b/tests/ens/test_setup_name.py
@@ -69,6 +69,17 @@ def test_setup_name(ens, name, normalized_name, namehash_hex):
     # check that the correct owner is set:
     assert ens.owner(name) == owner
 
+    # setup name to point to new address
+    new_address = ens.w3.eth.accounts[4]
+    ens.setup_address(name, None)
+    ens.setup_name(name, new_address)
+
+    # validate that ens.name() only returns a name if the forward resolution also returns the
+    # address
+    assert ens.name(new_address) == normalized_name  # reverse resolution
+    assert ens.address(name) == new_address  # forward resolution
+    assert not ens.name(address)
+
     ens.setup_name(None, address)
     ens.setup_address(name, None)
     assert not ens.name(address)