From 8ab3d6d1efb5fdaaa406413adf39d0c1079a7eb4 Mon Sep 17 00:00:00 2001
From: Alex Martsinovich <alex@slab.com>
Date: Fri, 10 Jan 2025 11:04:50 -0800
Subject: [PATCH] Updte DNS module and DNSResolver behaviour

---
 guides/migrating_to_1.0.md  | 12 ++++++++++++
 lib/safeurl/dns_resolver.ex |  3 +--
 lib/safeurl/safeurl.ex      |  2 +-
 mix.exs                     |  2 +-
 4 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/guides/migrating_to_1.0.md b/guides/migrating_to_1.0.md
index d83203c..d584824 100644
--- a/guides/migrating_to_1.0.md
+++ b/guides/migrating_to_1.0.md
@@ -28,3 +28,15 @@ iex> Application.put_env(:safeurl, :detailed_error, false)
 iex> SafeURL.validate("http://localhost")
 {:error, :restricted}
 ```
+
+### Change modules implementing `SafeURL.DNSResolver` behaviour
+
+If you have a module that implements `SafeURL.DNSResolver` behaviour, note that
+`DNSResolver.resolve/1` signature has changed. Specifically, the ok tuple should now
+always return a list of IPs. A single IP is not a valid return type:
+
+```elixir
+# DNS is the default implementation
+iex> DNS.resolve("wikipedia.org")
+{:ok, [{198, 35, 26, 96}]}
+```
\ No newline at end of file
diff --git a/lib/safeurl/dns_resolver.ex b/lib/safeurl/dns_resolver.ex
index a5747db..14648f1 100644
--- a/lib/safeurl/dns_resolver.ex
+++ b/lib/safeurl/dns_resolver.ex
@@ -69,6 +69,5 @@ defmodule SafeURL.DNSResolver do
 
   """
 
-  @type resolution :: :inet.ip() | [:inet.ip()]
-  @callback resolve(host :: binary()) :: {:ok, resolution()} | {:error, atom()}
+  @callback resolve(host :: String.t()) :: {:ok, list()} | {:error, :inet_res.res_error()}
 end
diff --git a/lib/safeurl/safeurl.ex b/lib/safeurl/safeurl.ex
index 95b820c..14f7ff4 100644
--- a/lib/safeurl/safeurl.ex
+++ b/lib/safeurl/safeurl.ex
@@ -239,7 +239,7 @@ defmodule SafeURL do
       {:error, :einval} ->
         # TODO: safely handle multiple IPs/round-robin DNS
         case dns_module.resolve(hostname) do
-          {:ok, ips} -> ips |> List.wrap() |> List.first()
+          {:ok, [ip | _]} -> ip
           {:error, _reason} -> nil
         end
     end
diff --git a/mix.exs b/mix.exs
index 5e5c15f..3793174 100644
--- a/mix.exs
+++ b/mix.exs
@@ -54,7 +54,7 @@ defmodule SafeURL.MixProject do
     [
       {:httpoison, "~> 1.0 or ~> 2.0", optional: true},
       {:inet_cidr, "~> 1.0 and >= 1.0.6"},
-      {:dns, "~> 2.2"},
+      {:dns, "~> 2.4"},
       {:tesla, "~> 1.0", optional: true},
       {:ex_doc, ">= 0.0.0", only: :dev, runtime: false}
     ]