MDNS hostname match DHCP. Fix collision mangling

MDNS defaults to the hostname used by DHCP/LWIP since it is now
unique. This makes it the same either way.

This also updates esp-protocols (used for mdns) with a patch to
ensure that mangled names are the ones that collide.
(circuitpython.local collides but was causing cpy- to be mangled.)

Fixes #6869 again.

Author: tannewt

.gitmodules

@@ -146,7 +146,8 @@
 	branch = circuitpython-v5.3.1
 [submodule "ports/espressif/esp-protocols"]
 	path = ports/espressif/esp-protocols
-	url = https://github.com/espressif/esp-protocols.git
+	url = https://github.com/adafruit/esp-protocols.git
+	branch = circuitpython
 [submodule "ports/espressif/esp-camera"]
 	path = ports/espressif/esp-camera
 	url = https://github.com/adafruit/esp32-camera.git

ports/espressif/common-hal/mdns/Server.c

@@ -33,10 +33,9 @@ void mdns_server_construct(mdns_server_obj_t *self, bool workflow) {
     }
     _active_object = self;
 
-    uint8_t mac[6];
-    esp_netif_get_mac(common_hal_wifi_radio_obj.netif, mac);
-    snprintf(self->default_hostname, sizeof(self->default_hostname), "cpy-%02x%02x%02x", mac[3], mac[4], mac[5]);
-    common_hal_mdns_server_set_hostname(self, self->default_hostname);
+    // Match the netif hostname set when `import wifi` was called.
+    esp_netif_get_hostname(common_hal_wifi_radio_obj.netif, &self->hostname);
+    common_hal_mdns_server_set_hostname(self, self->hostname);
 
     self->inited = true;
 

ports/espressif/common-hal/mdns/Server.h

@@ -12,7 +12,6 @@ typedef struct {
     mp_obj_base_t base;
     const char *hostname;
     const char *instance_name;
-    char default_hostname[sizeof("cpy-XXXXXX")];
     // Track if this object owns access to the underlying MDNS service.
     bool inited;
 } mdns_server_obj_t;

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

@@ -199,11 +199,20 @@ void common_hal_wifi_init(bool user_initiated) {
         ESP_LOGE(TAG, "WiFi error code: %x", result);
         return;
     }
-    // set the default lwip_local_hostname
-    char cpy_default_hostname[strlen(CIRCUITPY_BOARD_ID) + (MAC_ADDRESS_LENGTH * 2) + 6];
+    // Set the default lwip_local_hostname capped at 32 characters. We trim off
+    // the start of the board name (likely manufacturer) because the end is
+    // often more unique to the board.
+    size_t board_len = MIN(32 - ((MAC_ADDRESS_LENGTH * 2) + 6), strlen(CIRCUITPY_BOARD_ID));
+    size_t board_trim = strlen(CIRCUITPY_BOARD_ID) - board_len;
+    // Avoid double _ in the hostname.
+    if (CIRCUITPY_BOARD_ID[board_trim] == '_') {
+        board_trim++;
+    }
+
+    char cpy_default_hostname[board_len + (MAC_ADDRESS_LENGTH * 2) + 6];
     uint8_t mac[MAC_ADDRESS_LENGTH];
     esp_wifi_get_mac(ESP_IF_WIFI_STA, mac);
-    sprintf(cpy_default_hostname, "cpy_%s_%x", CIRCUITPY_BOARD_ID, (unsigned int)mac);
+    snprintf(cpy_default_hostname, sizeof(cpy_default_hostname), "cpy-%s-%x", CIRCUITPY_BOARD_ID + board_trim, (unsigned int)mac);
     const char *default_lwip_local_hostname = cpy_default_hostname;
     ESP_ERROR_CHECK(esp_netif_set_hostname(self->netif, default_lwip_local_hostname));
     // set station mode to avoid the default SoftAP