From cf7a16c70fbb979b4407dc71ef73c2691ad18c8b Mon Sep 17 00:00:00 2001
From: Garrett Hayes <60194316+pr0fg@users.noreply.github.com>
Date: Sun, 4 Oct 2020 21:03:07 -0400
Subject: [PATCH] Updated domain validator coverage

Updated domain validator to support domains that start with an underscore. These domains are quite common in the wild.

For example:
_jabber._tcp.gmail.com
_sip._udp.apnic.net

See RFC 2181, section 11, "Name syntax" and RFC 1034, section 3.5 "Preferred name syntax" for more info.
---
 validators/domain.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/validators/domain.py b/validators/domain.py
index 1c1ce232..258f3b7f 100644
--- a/validators/domain.py
+++ b/validators/domain.py
@@ -11,7 +11,7 @@
     text_type = unicode
 
 pattern = re.compile(
-    r'^(?:[a-zA-Z0-9]'  # First character of the domain
+    r'^(?:[a-zA-Z0-9_]'  # First character of the domain
     r'(?:[a-zA-Z0-9-_]{0,61}[A-Za-z0-9])?\.)'  # Sub domain + hostname
     r'+[A-Za-z0-9][A-Za-z0-9-_]{0,61}'  # First 61 characters of the gTLD
     r'[A-Za-z]$'  # Last character of the gTLD