Unquote connection string components properly

When a connection string component contains characters that have a
special meaning in the URI (e.g. '@' or '='), percent-encoding must be
used.  asyncpg must take care to unquote the parsed components
correctly, and it doesn't currently.

Additionally, this makes asyncpg follow the libpq's behavior of parsing
the authentication part of netloc, i.e. split on the first '@' and not
the last.

Fixes: #418
Fixes: #471

asyncpg/connect_utils.py

@@ -153,7 +153,7 @@ def _validate_port_spec(hosts, port):
     return port
 
 
-def _parse_hostlist(hostlist, port):
+def _parse_hostlist(hostlist, port, *, unquote=False):
     if ',' in hostlist:
         # A comma-separated list of host addresses.
         hostspecs = hostlist.split(',')
@@ -185,9 +185,14 @@ def _parse_hostlist(hostlist, port):
             addr = hostspec
             hostspec_port = ''
 
+        if unquote:
+            addr = urllib.parse.unquote(addr)
+
         hosts.append(addr)
         if not port:
             if hostspec_port:
+                if unquote:
+                    hostspec_port = urllib.parse.unquote(hostspec_port)
                 hostlist_ports.append(int(hostspec_port))
             else:
                 hostlist_ports.append(default_port[i])
@@ -213,25 +218,34 @@ def _parse_connect_dsn_and_args(*, dsn, host, port, user,
                 'invalid DSN: scheme is expected to be either '
                 '"postgresql" or "postgres", got {!r}'.format(parsed.scheme))
 
-        if not host and parsed.netloc:
+        if parsed.netloc:
             if '@' in parsed.netloc:
-                auth, _, hostspec = parsed.netloc.partition('@')
+                dsn_auth, _, dsn_hostspec = parsed.netloc.partition('@')
             else:
-                hostspec = parsed.netloc
+                dsn_hostspec = parsed.netloc
+                dsn_auth = ''
+        else:
+            dsn_auth = dsn_hostspec = ''
+
+        if dsn_auth:
+            dsn_user, _, dsn_password = dsn_auth.partition(':')
+        else:
+            dsn_user = dsn_password = ''
 
-            if hostspec:
-                host, port = _parse_hostlist(hostspec, port)
+        if not host and dsn_hostspec:
+            host, port = _parse_hostlist(dsn_hostspec, port, unquote=True)
 
         if parsed.path and database is None:
-            database = parsed.path
-            if database.startswith('/'):
-                database = database[1:]
+            dsn_database = parsed.path
+            if dsn_database.startswith('/'):
+                dsn_database = dsn_database[1:]
+            database = urllib.parse.unquote(dsn_database)
 
-        if parsed.username and user is None:
-            user = parsed.username
+        if user is None and dsn_user:
+            user = urllib.parse.unquote(dsn_user)
 
-        if parsed.password and password is None:
-            password = parsed.password
+        if password is None and dsn_password:
+            password = urllib.parse.unquote(dsn_password)
 
         if parsed.query:
             query = urllib.parse.parse_qs(parsed.query, strict_parsing=True)

tests/test_connect.py

@@ -453,6 +453,41 @@ class TestConnectParams(tb.TestCase):
                 'database': 'dbname'})
         },
 
+        {
+            'dsn': 'postgresql://us%40r:p%40ss@h%40st1,h%40st2:543%33/d%62',
+            'result': (
+                [('h@st1', 5432), ('h@st2', 5433)],
+                {
+                    'user': 'us@r',
+                    'password': 'p@ss',
+                    'database': 'db',
+                }
+            )
+        },
+
+        {
+            'dsn': 'postgresql://user:p@ss@host/db',
+            'result': (
+                [('ss@host', 5432)],
+                {
+                    'user': 'user',
+                    'password': 'p',
+                    'database': 'db',
+                }
+            )
+        },
+
+        {
+            'dsn': 'postgresql:///d%62?user=us%40r&host=h%40st&port=543%33',
+            'result': (
+                [('h@st', 5433)],
+                {
+                    'user': 'us@r',
+                    'database': 'db',
+                }
+            )
+        },
+
         {
             'dsn': 'pq:///dbname?host=/unix_sock/test&user=spam',
             'error': (ValueError, 'invalid DSN')