Fix parsing of IPv6 addresses in the connection URI (MagicStack#845)

Plain IPv6 addresses specified in square brackets in the connection URI
are now parsed correctly.

Fixes: MagicStack#838.

asyncpg/connect_utils.py

@@ -197,11 +197,25 @@ def _parse_hostlist(hostlist, port, *, unquote=False):
  port = _validate_port_spec(hostspecs, port)
 
  for i, hostspec in enumerate(hostspecs):
- if not hostspec.startswith('/'):
- addr, _, hostspec_port = hostspec.partition(':')
- else:
+ if hostspec[0] == '/':
+ # Unix socket
  addr = hostspec
  hostspec_port = ''
+ elif hostspec[0] == '[':
+ # IPv6 address
+ m = re.match(r'(?:\[([^\]]+)\])(?::([0-9]+))?', hostspec)
+ if m:
+ addr = m.group(1)
+ hostspec_port = m.group(2)
+ else:
+ raise ValueError(
+ 'invalid IPv6 address in the connection URI: {!r}'.format(
+ hostspec
+ )
+ )
+ else:
+ # IPv4 address
+ addr, _, hostspec_port = hostspec.partition(':')
 
  if unquote:
  addr = urllib.parse.unquote(addr)

asyncpg/connection.py

@@ -1813,7 +1813,13 @@ async def connect(dsn=None, *,
  .. note::
 
  The URI must be *valid*, which means that all components must
- be properly quoted with :py:func:`urllib.parse.quote`.
+ be properly quoted with :py:func:`urllib.parse.quote`, and
+ any literal IPv6 addresses must be enclosed in square brackets.
+ For example:
+
+ .. code-block:: text
+
+ postgres:https://dbuser@[fe80::1ff:fe23:4567:890a%25eth0]/dbname
 
  :param host:
  Database host address as one of the following:

tests/test_connect.py

@@ -511,6 +511,34 @@ class TestConnectParams(tb.TestCase):
  })
  },
 
+ {
+ 'name': 'dsn_ipv6_multi_host',
+ 'dsn': 'postgresql:https://user@[2001:db8::1234%25eth0],[::1]/db',
+ 'result': ([('2001:db8::1234%eth0', 5432), ('::1', 5432)], {
+ 'database': 'db',
+ 'user': 'user',
+ })
+ },
+
+ {
+ 'name': 'dsn_ipv6_multi_host_port',
+ 'dsn': 'postgresql:https://user@[2001:db8::1234]:1111,[::1]:2222/db',
+ 'result': ([('2001:db8::1234', 1111), ('::1', 2222)], {
+ 'database': 'db',
+ 'user': 'user',
+ })
+ },
+
+ {
+ 'name': 'dsn_ipv6_multi_host_query_part',
+ 'dsn': 'postgresql:https:///db?user=user&host=[2001:db8::1234],[::1]',
+ 'result': ([('2001:db8::1234', 5432), ('::1', 5432)], {
+ 'database': 'db',
+ 'user': 'user',
+ })
+ },
+
+
  {
  'name': 'dsn_combines_env_multi_host',
  'env': {