From 2ca58464e185625cc922cb1549ae96df1c3e7ca4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fr=C3=A9d=C3=A9ric=20P=C3=A9ters?= <fpeters@entrouvert.com>
Date: Tue, 24 Mar 2020 20:31:25 +0100
Subject: [PATCH 1/2] validators: use only dnspython to resolve domains
 (#40989)

Also fix SMTP error value check when testing email adresses with an RCPT
check.
---
 src/authentic2/validators.py | 84 ++++++++++++++++++------------------
 1 file changed, 41 insertions(+), 43 deletions(-)

diff --git a/src/authentic2/validators.py b/src/authentic2/validators.py
index dc992b09..8856f2fc 100644
--- a/src/authentic2/validators.py
+++ b/src/authentic2/validators.py
@@ -19,11 +19,9 @@ from __future__ import unicode_literals
 import smtplib
 
 from django.utils.translation import ugettext_lazy as _
-from django.utils.encoding import force_text
 from django.core.exceptions import ValidationError
-from django.core.validators import RegexValidator
+from django.core.validators import RegexValidator, EmailValidator as DjangoEmailValidator
 
-import socket
 import dns.resolver
 import dns.exception
 
@@ -42,55 +40,55 @@ class EmailValidator(object):
             mxs = dns.resolver.query(domain, 'MX')
             mxs = [str(mx.exchange).rstrip('.') for mx in mxs]
             return mxs
+        except dns.resolver.NXDOMAIN:
+            return []
+        except dns.resolver.NoAnswer:
+            pass
         except dns.exception.DNSException:
+            pass
+
+        for record_type in ('AAAA', 'A'):
             try:
-                idna_encoded = force_text(domain).encode('idna')
-            except UnicodeError:
+                mxs = dns.resolver.query(domain, 'MX')
+                mxs = [str(mx.address).rstrip('.') for mx in mxs]
+                return mxs
+            except dns.resolver.NXDOMAIN:
                 return []
-            try:
-                socket.gethostbyname(idna_encoded)
-                return [domain]
-            except socket.error:
+            except dns.resolver.NoAnswer:
+                pass
+            except dns.exception.DNSException:
                 pass
         return []
 
-    def __call__(self, value):
-        try:
-            hostname = value.split('@')[-1]
-        except KeyError:
-            raise ValidationError(_('Enter a valid email address.'), code='invalid-email')
-        if not app_settings.A2_VALIDATE_EMAIL_DOMAIN:
-            return True
+    def check_rcpt(self, value, mxs):
+        for server in mxs:
+            try:
+                smtp = smtplib.SMTP()
+                smtp.connect(server)
+                status = smtp.helo()
+                if status[0] != 250:
+                    continue
+                smtp.mail('')
+                status = smtp.rcpt(value)
+                if status[0] // 100 == 5:
+                    raise ValidationError(_('Invalid email address.'), code='rcpt-check-failed')
+                break
+            except smtplib.SMTPServerDisconnected:
+                break
+            except smtplib.SMTPConnectError:
+                continue
 
-        mxs = self.check_mxs(hostname)
-        if not mxs:
-            raise ValidationError(_('Email domain is invalid'), code='invalid-domain')
+    def __call__(self, value):
+        DjangoEmailValidator()(value)
 
-        if not self.rcpt_check or not app_settings.A2_VALIDATE_EMAIL:
-            return
+        localpart, hostname = value.split('@', 1)
+        if app_settings.A2_VALIDATE_EMAIL_DOMAIN:
+            mxs = self.check_mxs(hostname)
+            if not mxs:
+                raise ValidationError(_('Email domain is invalid'), code='invalid-domain')
+            if self.rcpt_check and app_settings.A2_VALIDATE_EMAIL:
+                self.check_rcpt(value, mxs)
 
-        try:
-            for server in mxs:
-                try:
-                    smtp = smtplib.SMTP()
-                    smtp.connect(server)
-                    status = smtp.helo()
-                    if status[0] != 250:
-                        continue
-                    smtp.mail('')
-                    status = smtp.rcpt(value)
-                    if status[0] % 100 == 5:
-                        raise ValidationError(_('Invalid email address.'), code='rcpt-check-failed')
-                    break
-                except smtplib.SMTPServerDisconnected:
-                    break
-                except smtplib.SMTPConnectError:
-                    continue
-        # Should not happen !
-        except dns.resolver.NXDOMAIN:
-            raise ValidationError(_('Nonexistent domain.'))
-        except dns.resolver.NoAnswer:
-            raise ValidationError(_('Nonexistent email address.'))
 
 email_validator = EmailValidator()
 
-- 
2.24.0