Change parse_recipient_value regex

I’ve broken the regular expression to match three distinct types of address

1. Quoted name with address
2. Non-quoted name with address
3. address on it’s own

I have also changed to expanded notation to make it a little clearer.

Author: andrewtimberlake

lib/mail/parsers/rfc_2822.ex

@@ -318,10 +318,49 @@ defmodule Mail.Parsers.RFC2822 do
   @spec parse_recipient_value(value :: String.t()) ::
           [{String.t(), String.t()} | String.t()]
   def parse_recipient_value(value) do
-    Regex.scan(~r/\s*("?)(.*?)\1\s*?<?([^<\s]+@[^\s>,]+)>?,?/, value)
+    Regex.scan(
+      ~r/
+    \s*
+    (?:
+      # Quoted name
+      ((?<!\\)")
+      (?<name>.*?)
+      \1
+      \s*
+      <
+      (?<email>[^<\s,]+@[^\s>,]+)
+      >
+    |
+      # Non-quoted name
+      (?<name2>[^\\",@]+?)
+      \s*?
+      <
+      (?<email2>[^<\s,]+@[^\s>,]+)
+      >
+    |
+      # Only email
+      <?(?<email3>[^<\s,]+@[^\s>,]+)>?
+    )
+    ,?
+    /x,
+      value,
+      capture: :all_names
+    )
     |> Enum.map(fn
-      [_, _, "", address] -> address
-      [_, _, name, address] -> {name, address}
+      # Scan is matching on named captures sorted alphabetically:
+      # [email, email2, email3, name, name2]
+      ["", "", address, "", ""] ->
+        {"", address}
+
+      [address, "", "", name, ""] ->
+        {name, address}
+
+      ["", address, "", "", name] ->
+        {name, address}
+    end)
+    |> Enum.map(fn
+      {"", address} -> address
+      {name, address} -> {String.replace(name, "\\", ""), address}
     end)
   end
 

test/mail/parsers/rfc_2822_test.exs

@@ -303,30 +303,59 @@ defmodule Mail.Parsers.RFC2822Test do
     assert to_datetime("invalid date string") == {:error, "invalid date string"}
   end
 
-  test "parse_recipient_value retrieves a list of name and addresses" do
-    recipient =
-      "The Dude <dude@example.com>, batman@example.com, super<compact@recipi.ent>, \"an@email.com\" <an@email.com>"
-
-    retrieved_recipients = [
-      {"The Dude", "dude@example.com"},
-      "batman@example.com",
-      {"super", "compact@recipi.ent"},
-      {"an@email.com", "an@email.com"}
-    ]
-
-    assert parse_recipient(recipient) == retrieved_recipients
-  end
+  describe "parse_recipient_value/1" do
+    test "parse_recipient_value retrieves a list of name and addresses" do
+      recipient =
+        ~S|The Dude <dude@example.com>, batman@example.com, super<compact@recipi.ent>, "an@email.com" <an@email.com>|
+
+      retrieved_recipients = [
+        {"The Dude", "dude@example.com"},
+        "batman@example.com",
+        {"super", "compact@recipi.ent"},
+        {"an@email.com", "an@email.com"}
+      ]
+
+      assert parse_recipient(recipient) == retrieved_recipients
+    end
+
+    test "parse_recipient_value retrieves an empty list when recipient is empty" do
+      assert parse_recipient("") == []
+    end
+
+    test "parse_recipient_value retrieves an empty list when no \"address\" found" do
+      assert parse_recipient("NoEmail") == []
+    end
+
+    test "parse_recipient_value retrieves a list when only one \"address\" found" do
+      assert parse_recipient("dude@example.com") == ["dude@example.com"]
+      assert parse_recipient("<dude@example.com>") == ["dude@example.com"]
+    end
+
+    test "parse_recipient_value quoted name" do
+      assert parse_recipient(~S|"dude" <dude@example.com>|) == [{"dude", "dude@example.com"}]
+
+      assert parse_recipient(~S|"First, Second" <dude@example.com>|) == [
+               {"First, Second", "dude@example.com"}
+             ]
+    end
 
-  test "parse_recipient_value retrieves an empty list when recipient is empty" do
-    assert parse_recipient("") == []
-  end
+    test "parse_recipient_value non-quoted name" do
+      assert parse_recipient(~S|The Dude <dude@example.com>|) == [
+               {"The Dude", "dude@example.com"}
+             ]
+    end
 
-  test "parse_recipient_value retrieves an empty list when no \"address\" found" do
-    assert parse_recipient("NoEmail") == []
-  end
+    test "parse_recipient_value extra quoted name" do
+      assert parse_recipient(~S|"\"dude\"" <dude@example.com>|) == [
+               {"\"dude\"", "dude@example.com"}
+             ]
+    end
 
-  test "parse_recipient_value retrieves a list when only one \"address\" found" do
-    assert parse_recipient("dude@example.com") == ["dude@example.com"]
+    test "parse_recipient_value extra test" do
+      assert parse_recipient(~S|"\"service@service.com\" " <service@service.com>|) == [
+               {~S|"service@service.com" |, "service@service.com"}
+             ]
+    end
   end
 
   test "parses a nested multipart message with encoded part" do