diff --git a/synapse/util/stringutils.py b/synapse/util/stringutils.py
index f029432191..ea1032b4fc 100644
--- a/synapse/util/stringutils.py
+++ b/synapse/util/stringutils.py
@@ -19,6 +19,8 @@ import string
from collections.abc import Iterable
from typing import Optional, Tuple
+from netaddr import valid_ipv6
+
from synapse.api.errors import Codes, SynapseError
_string_with_symbols = string.digits + string.ascii_letters + ".,;:^&*-_+=#~@"
@@ -97,7 +99,10 @@ def parse_server_name(server_name: str) -> Tuple[str, Optional[int]]:
raise ValueError("Invalid server name '%s'" % server_name)
-VALID_HOST_REGEX = re.compile("\\A[0-9a-zA-Z.-]+\\Z")
+# An approximation of the domain name syntax in RFC 1035, section 2.3.1.
+# NB: "\Z" is not equivalent to "$".
+# The latter will match the position before a "\n" at the end of a string.
+VALID_HOST_REGEX = re.compile("\\A[0-9a-zA-Z-]+(?:\\.[0-9a-zA-Z-]+)*\\Z")
def parse_and_validate_server_name(server_name: str) -> Tuple[str, Optional[int]]:
@@ -122,13 +127,15 @@ def parse_and_validate_server_name(server_name: str) -> Tuple[str, Optional[int]
if host[0] == "[":
if host[-1] != "]":
raise ValueError("Mismatched [...] in server name '%s'" % (server_name,))
- return host, port
- # otherwise it should only be alphanumerics.
- if not VALID_HOST_REGEX.match(host):
- raise ValueError(
- "Server name '%s' contains invalid characters" % (server_name,)
- )
+ # valid_ipv6 raises when given an empty string
+ ipv6_address = host[1:-1]
+ if not ipv6_address or not valid_ipv6(ipv6_address):
+ raise ValueError(
+ "Server name '%s' is not a valid IPv6 address" % (server_name,)
+ )
+ elif not VALID_HOST_REGEX.match(host):
+ raise ValueError("Server name '%s' has an invalid format" % (server_name,))
return host, port
|
