Content server: Listen for all incoming IPv4 and v6 connections by default

Clean up previous PR. Remains to do something about zeroconf, it should
advertise both IP addresses when the server is listening on both.

src/calibre/gui2/actions/device.py

@@ -17,23 +17,15 @@ from calibre.utils.smtp import config as email_config
 
 def local_url_for_content_server():
     from calibre.srv.opts import server_config
-    from calibre.utils.network import is_ipv6_addr, get_fallback_server_addr
+    from calibre.utils.network import format_addr_for_url, get_fallback_server_addr
 
     opts = server_config()
-    interface = opts.listen_on or get_fallback_server_addr()
+    addr = opts.listen_on or get_fallback_server_addr()
-
+    addr = {'0.0.0.0': '127.0.0.1', '::': '::1'}.get(addr, addr)
-    addr_map = {'0.0.0.0': '127.0.0.1',
-                '::':      '::1'}
-    if interface in addr_map:
-        interface = addr_map[interface]
-
     protocol = 'https' if opts.ssl_certfile and opts.ssl_keyfile else 'http'
     prefix = opts.url_prefix or ''
-
     port = opts.port
-    addr = f'[{interface}]' if is_ipv6_addr(interface) else f'{interface}'
+    return f'{protocol}://{format_addr_for_url(addr)}:{port}{prefix}'
-
-    return f'{protocol}://{addr}:{port}{prefix}'
 
 
 def open_in_browser():

src/calibre/gui2/preferences/server.py

@@ -1299,23 +1299,12 @@ class ConfigWidget(ConfigWidgetBase):
         self.stopping_msg.accept()
 
     def test_server(self):
-        from calibre.utils.network import is_ipv6_addr, get_fallback_server_addr
+        from calibre.utils.network import format_addr_for_url, get_fallback_server_addr
-
         prefix = self.advanced_tab.get('url_prefix') or ''
         protocol = 'https' if self.advanced_tab.has_ssl else 'http'
-        lo = self.advanced_tab.get('listen_on') or get_fallback_server_addr()
+        addr = self.advanced_tab.get('listen_on') or get_fallback_server_addr()
-
+        addr = {'0.0.0.0': '127.0.0.1', '::': '::1'}.get(addr, addr)
-        addr_map = {'0.0.0.0': '127.0.0.1',
+        url = f'{protocol}://{format_addr_for_url(addr)}:{self.main_tab.opt_port.value()}{prefix}'
-                    '::':      '::1'}
-        if lo in addr_map:
-            lo = addr_map[lo]
-
-        if is_ipv6_addr(lo):
-            lo = f'[{lo}]'
-
-        url = '{protocol}://{interface}:{port}{prefix}'.format(
-            protocol=protocol, interface=lo,
-            port=self.main_tab.opt_port.value(), prefix=prefix)
         open_url(QUrl(url))
 
     def view_server_logs(self):

src/calibre/srv/loop.py

@@ -509,17 +509,14 @@ class ServerLoop:
             self.setup_socket()
 
     def serve(self):
-        from calibre.utils.network import is_ipv6_addr
+        from calibre.utils.network import format_addr_for_url
 
         self.connection_map = {}
         if not self.socket_was_preactivated:
             self.socket.listen(min(socket.SOMAXCONN, 128))
         self.bound_address = ba = self.socket.getsockname()
         if isinstance(ba, tuple):
-            if is_ipv6_addr(ba[0]):
+            addr = format_addr_for_url(str(ba[0]))
-                addr = f'[{ba[0]}]'
-            else:
-                addr = f'{ba[0]}'
             ba_str = f'{addr}:' + ':'.join(map(str, ba[1:]))
         self.pool.start()
         with TemporaryDirectory(prefix='srv-') as tdir:

src/calibre/srv/opts.py

@@ -112,8 +112,8 @@ raw_options = (
     _('The interface on which to listen for connections'),
     'listen_on', None,
     _('The default is to listen on all available IPv6 and IPv4 interfaces. You can change this to, for'
-    ' example, "127.0.0.1" to only listen for connections from the local machine, or'
+    ' example, "127.0.0.1" to only listen for IPv4 connections from the local machine, or'
-    ' to "::" to listen to all incoming IPv6 and IPv4 connections.'),
+    ' to "0.0.0.0" to listen to all incoming IPv4 connections.'),
 
     _('Fallback to auto-detected interface'),
     'fallback_to_detected_interface', True,

src/calibre/utils/mdns.py

@@ -77,9 +77,6 @@ def _get_external_ip():
 
 
 def verify_ipV4_address(ip_address):
-    if ip_address == None:
-        return None
-
     result = None
     if ip_address != '0.0.0.0' and ip_address != '::':
         # do some more sanity checks on the address
@@ -87,7 +84,7 @@ def verify_ipV4_address(ip_address):
             socket.inet_aton(ip_address)
             if len(ip_address.split('.')) == 4:
                 result = ip_address
-        except OSError:
+        except Exception:
             # Not legal ip address
             pass
     return result

src/calibre/utils/network.py

@@ -113,13 +113,17 @@ def is_ipv6_addr(addr):
     import socket
     try:
         socket.inet_pton(socket.AF_INET6, addr)
-        return True
+    except Exception:
-    except OSError:
         return False
+    return True
+
+
+def format_addr_for_url(addr):
+    if is_ipv6_addr(addr):
+        addr = f'[{addr}]'
+    return addr
+
 
 def get_fallback_server_addr():
     from socket import has_dualstack_ipv6
-    if has_dualstack_ipv6():
+    return '::' if has_dualstack_ipv6() else '0.0.0.0'
-        return '::'
-    else:
-        return '0.0.0.0'