fix import and missing license-header

src/pretix/base/email.py

@@ -19,7 +19,6 @@
 # You should have received a copy of the GNU Affero General Public License along with this program.  If not, see
 # <https://www.gnu.org/licenses/>.
 #
-import ipaddress
 import logging
 import smtplib
 import socket
@@ -43,6 +42,7 @@ from pretix.base.templatetags.rich_text import (
     markdown_compile_email, truelink_callback,
 )
 from pretix.helpers.format import FormattedString, SafeFormatter, format_map
+from pretix.helpers.ssrf import should_block_access
 
 from pretix.base.services.placeholders import (  # noqa
     get_available_placeholders, PlaceholderContext
@@ -57,8 +57,6 @@ logger = logging.getLogger('pretix.base.email')
 
 T = TypeVar("T", bound=EmailBackend)
 
-_cgnat_net = ipaddress.ip_network('100.64.0.0/10')
-
 
 def test_custom_smtp_backend(backend: T, from_addr: str) -> None:
     try:
@@ -254,16 +252,9 @@ def create_connection(address, timeout=socket.getdefaulttimeout(),
         af, socktype, proto, canonname, sa = res
 
         if not getattr(settings, "MAIL_CUSTOM_SMTP_ALLOW_PRIVATE_NETWORKS", False):
-            ip_addr = ipaddress.ip_address(sa[0])
-            check_ip4 = ip_addr.ipv4_mapped if getattr(ip_addr, "ipv4_mapped", None) else ip_addr
-            if ip_addr.is_multicast:
-                raise socket.error(f"Request to multicast address {sa[0]} blocked")
-            if ip_addr.is_loopback or ip_addr.is_link_local:
-                raise socket.error(f"Request to local address {sa[0]} blocked")
-            if ip_addr.is_private:
-                raise socket.error(f"Request to private address {sa[0]} blocked")
-            if check_ip4 in _cgnat_net:
-                raise socket.error(f"Request to RFC 6598 address {sa[0]} blocked")
+            is_private, msg = should_block_access(sa)
+            if is_private:
+                raise socket.error(msg)
 
         sock = None
         try:

src/pretix/helpers/monkeypatching.py

@@ -19,7 +19,6 @@
 # You should have received a copy of the GNU Affero General Public License along with this program.  If not, see
 # <https://www.gnu.org/licenses/>.
 #
-import ipaddress
 import socket
 import sys
 import types
@@ -42,8 +41,7 @@ from urllib3.util.connection import (
 from urllib3.util.timeout import _DEFAULT_TIMEOUT
 
 from pretix.helpers.reportlab import ThumbnailingImageReader
-
-_cgnat_net = ipaddress.ip_network('100.64.0.0/10')
+from pretix.helpers.ssrf import should_block_access
 
 
 def monkeypatch_vobject_performance():
@@ -150,16 +148,9 @@ def monkeypatch_urllib3_ssrf_protection():
             af, socktype, proto, canonname, sa = res
 
             if not getattr(settings, "ALLOW_HTTP_TO_PRIVATE_NETWORKS", False):
-                ip_addr = ipaddress.ip_address(sa[0])
-                check_ip4 = ip_addr.ipv4_mapped if getattr(ip_addr, "ipv4_mapped", None) else ip_addr
-                if ip_addr.is_multicast:
-                    raise HTTPError(f"Request to multicast address {sa[0]} blocked")
-                if ip_addr.is_loopback or ip_addr.is_link_local:
-                    raise HTTPError(f"Request to local address {sa[0]} blocked")
-                if ip_addr.is_private:
-                    raise HTTPError(f"Request to private address {sa[0]} blocked")
-                if check_ip4 in _cgnat_net:
-                    raise HTTPError(f"Request to RFC 6598 address {sa[0]} blocked")
+                is_private, msg = should_block_access(sa)
+                if is_private:
+                    raise HTTPError(msg)
 
             sock = None
             try:

src/pretix/helpers/ssrf.py

@@ -0,0 +1,40 @@
+#
+# This file is part of pretix (Community Edition).
+#
+# Copyright (C) 2014-2020  Raphael Michel and contributors
+# Copyright (C) 2020-today pretix GmbH and contributors
+#
+# This program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General
+# Public License as published by the Free Software Foundation in version 3 of the License.
+#
+# ADDITIONAL TERMS APPLY: Pursuant to Section 7 of the GNU Affero General Public License, additional terms are
+# applicable granting you additional permissions and placing additional restrictions on your usage of this software.
+# Please refer to the pretix LICENSE file to obtain the full terms applicable to this work. If you did not receive
+# this file, see <https://pretix.eu/about/en/license>.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
+# warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Affero General Public License for more
+# details.
+#
+# You should have received a copy of the GNU Affero General Public License along with this program.  If not, see
+# <https://www.gnu.org/licenses/>.
+#
+
+import ipaddress
+
+_cgnat_net = ipaddress.ip_network('100.64.0.0/10')
+
+
+def should_block_access(sa):
+    ip_addr = ipaddress.ip_address(sa[0])
+    check_ip4 = ip_addr.ipv4_mapped if getattr(ip_addr, "ipv4_mapped", None) else ip_addr
+    if ip_addr.is_multicast:
+        return True, f"Request to multicast address {sa[0]} blocked"
+    if ip_addr.is_loopback or ip_addr.is_link_local:
+        return True, f"Request to local address {sa[0]} blocked"
+    if ip_addr.is_private:
+        return True, f"Request to private address {sa[0]} blocked"
+    if check_ip4 in _cgnat_net:
+        return True, f"Request to RFC 6598 address {sa[0]} blocked"
+
+    return False, None