IPv6: improvments based on review notes

 * don't enable ipv6 by default due to privacy concerns
 * move list of board support for ipv6 to socketpool documentation
 * removed wifi.supports_ipvx properties
 * throw an exception when start_dhcp_client(ipv6=True) but not supported

Author: jepler

docs/shared_bindings_matrix.py

@@ -85,7 +85,7 @@
     "sys": "CIRCUITPY_SYS",
     "terminalio": "CIRCUITPY_DISPLAYIO",
     "usb": "CIRCUITPY_PYUSB",
-    "wifi.supports_ipv6": "CIRCUITPY_SOCKETPOOL_IPV6",
+    "socketpool.socketpool.AF_INET6": "CIRCUITPY_SOCKETPOOL_IPV6",
 }
 
 MODULES_NOT_IN_BINDINGS = ["binascii", "errno", "json", "re", "ulab"]

ports/espressif/common-hal/wifi/Radio.c

@@ -551,6 +551,10 @@ void common_hal_wifi_radio_start_dhcp_client(wifi_radio_obj_t *self, bool ipv4,
     } else {
         dhcp6_disable(esp_netif_get_netif_impl(self->netif));
     }
+    #else
+    if (ipv6) {
+        mp_raise_NotImplementedError_varg(MP_ERROR_TEXT("%q"), MP_QSTR_ipv6);
+    }
     #endif
 }
 

ports/espressif/common-hal/wifi/__init__.c

@@ -136,8 +136,6 @@ void common_hal_wifi_init(bool user_initiated) {
     if (wifi_inited) {
         if (user_initiated && !wifi_user_initiated) {
             common_hal_wifi_radio_set_enabled(self, true);
-            // explicitly start dhcp
-            common_hal_wifi_radio_start_dhcp_client(self, true, true);
         }
         return;
     }
@@ -203,8 +201,6 @@ void common_hal_wifi_init(bool user_initiated) {
     common_hal_wifi_radio_start_station(self);
     // start wifi
     common_hal_wifi_radio_set_enabled(self, true);
-    // explicitly start dhcp
-    common_hal_wifi_radio_start_dhcp_client(self, true, true);
 }
 
 void wifi_user_reset(void) {

ports/raspberrypi/common-hal/wifi/Radio.c

@@ -412,6 +412,9 @@ void common_hal_wifi_radio_start_dhcp_client(wifi_radio_obj_t *self, bool ipv4,
     } else {
         dhcp_stop(NETIF_STA);
     }
+    if (ipv6) {
+        mp_raise_NotImplementedError_varg(MP_ERROR_TEXT("%q"), MP_QSTR_ipv6);
+    }
 }
 
 void common_hal_wifi_radio_stop_dhcp_client(wifi_radio_obj_t *self) {

shared-bindings/socketpool/__init__.c

@@ -18,6 +18,21 @@
 //|
 //| For more information about the `socket` module, see the CPython documentation:
 //| https://docs.python.org/3/library/socket.html
+//|
+//| .. jinja
+//|
+//| .. raw:: html
+//|
+//|     <p>
+//|     <details>
+//|     <summary>AF_INET6 (IPv6) supported on these boards</summary>
+//|     <ul>
+//|     {% for board in support_matrix_reverse["socketpool.socketpool.AF_INET6"] %}
+//|     <li> {{ board }}
+//|     {% endfor %}
+//|     </ul>
+//|     </details>
+//|     </p>
 //| """
 
 static const mp_rom_map_elem_t socketpool_globals_table[] = {

shared-bindings/wifi/Radio.c

@@ -693,19 +693,19 @@ MP_DEFINE_CONST_FUN_OBJ_1(wifi_radio_get_stations_ap_obj, wifi_radio_get_station
 MP_PROPERTY_GETTER(wifi_radio_stations_ap_obj,
     (mp_obj_t)&wifi_radio_get_stations_ap_obj);
 
-//|     def start_dhcp(self, *, ipv4: bool = supports_ipv4, ipv6: bool = supports_ipv6) -> None:
+//|     def start_dhcp(self, *, ipv4: bool = True, ipv6: bool = False) -> None:
 //|         """Starts the station DHCP client.
 //|
-//|         By default, calling this function starts all supported types of DHCP.
-//|         If the ``ipv4`` and ``ipv6`` arguments are specified as `False` then
-//|         the corresponding DHCP client is stopped if it was active.
+//|         By default, calling this function starts DHCP for IPv4 networks but not
+//|         IPv6 networks. When the the ``ipv4`` and ``ipv6`` arguments are `False`
+//|         then the corresponding DHCP client is stopped if it was active.
 //|         """
 //|         ...
 static mp_obj_t wifi_radio_start_dhcp_client(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
     enum { ARG_ipv4, ARG_ipv6 };
     static const mp_arg_t allowed_args[] = {
         { MP_QSTR_ipv4, MP_ARG_KW_ONLY | MP_ARG_BOOL, { .u_bool = MP_ROM_TRUE } },
-        { MP_QSTR_ipv6, MP_ARG_KW_ONLY | MP_ARG_BOOL, { .u_bool = CIRCUITPY_SOCKETPOOL_IPV6 ? MP_ROM_TRUE : MP_ROM_FALSE } },
+        { MP_QSTR_ipv6, MP_ARG_KW_ONLY | MP_ARG_BOOL, { .u_bool = MP_ROM_FALSE } },
     };
 
     wifi_radio_obj_t *self = MP_OBJ_TO_PTR(pos_args[0]);

shared-bindings/wifi/__init__.c

@@ -14,31 +14,8 @@
 //| """
 //| The `wifi` module provides necessary low-level functionality for managing
 //| wifi connections. Use `socketpool` for communicating over the network.
-//|
-//| .. jinja
 //| """
 
-//| supports_ipv6: bool
-//| """``True`` when ipv6 is supported.  Read-only
-//|
-//| .. raw:: html
-//|
-//|     <p>
-//|     <details>
-//|     <summary>True on these boards</summary>
-//|     <ul>
-//|     {% for board in support_matrix_reverse["wifi.supports_ipv6"] %}
-//|     <li> {{ board }}
-//|     {% endfor %}
-//|     </ul>
-//|     </details>
-//|     </p>
-//|
-//| """
-
-//| supports_ipv4: bool
-//| """``True`` when ipv4 is supported.  Read-only"""
-
 //| radio: Radio
 //| """Wifi radio used to manage both station and AP modes.
 //| This object is the sole instance of `wifi.Radio`."""
@@ -67,9 +44,6 @@ static const mp_rom_map_elem_t wifi_module_globals_table[] = {
 
     // Properties
     { MP_ROM_QSTR(MP_QSTR_radio),       MP_ROM_PTR(&common_hal_wifi_radio_obj) },
-
-    { MP_ROM_QSTR(MP_QSTR_supports_ipv6), MP_ROM_PTR(CIRCUITPY_SOCKETPOOL_IPV6 ? MP_ROM_TRUE : MP_ROM_FALSE) },
-    { MP_ROM_QSTR(MP_QSTR_supports_ipv4), MP_ROM_TRUE },
 };
 static MP_DEFINE_CONST_DICT(wifi_module_globals, wifi_module_globals_table);