Matter auto-fix IPv6 link-local zone id when network reconnects

CHANGELOG.md

@@ -30,6 +30,7 @@ All notable changes to this project will be documented in this file.
 - Webradio crash with invalid url (#21446)
 - Zigbee crash when removing `ZbName` (#21449)
 - ESP32 BLE fix scanning (#21451)
+- Matter auto-fix IPv6 link-local zone id when network reconnects
 
 ### Removed
 - Support of old insecure fingerprint algorithm. Deprecated since v8.4.0 (#21417)

lib/default/WiFiHelper/src/WiFiHelper.h

@@ -83,6 +83,13 @@ class WiFiHelper {
   // With ESP32 Core3, the WiFi mac address is not valid until the wifi is actually started
   // this helper function always provide a valid mac address
   static String macAddress(void);
+
+  // Auto-fix zone
+  //
+  // After a reconnect, the zone id may not be valid anymore
+  // In such case we detect any "%st<n>" or "%en<n>" zone identifier
+  // and replace with the current zone id
+  static void IPv6ZoneAutoFix(IPAddress &addr, const char* aHostname);
 };
 
 

lib/default/WiFiHelper/src/WiFiHelper_ESP32.cpp

@@ -240,6 +240,44 @@ static void wifi32_dns_found_callback(const char *name, const ip_addr_t *ipaddr,
   // AddLog(LOG_LEVEL_DEBUG, "WIF: dns_found=%s", ipaddr ? IPAddress(*ipaddr).toString().c_str() : "<null>");
 }
 
+// Auto-fix zone
+//
+// After a reconnect, the zone id may not be valid anymore
+// In such case we detect any "%st<n>" or "%en<n>" zone identifier
+// and replace with the current zone id
+extern bool WifiGetIPv6LinkLocal(IPAddress *ip);
+extern bool EthernetGetIPv6LinkLocal(IPAddress *ip);
+void WiFiHelper::IPv6ZoneAutoFix(IPAddress &addr, const char* aHostname) {
+#ifdef USE_IPV6
+  if ((addr.type() == IPv6) && (addr.zone() == 0)) {
+    // check if hostname contains '%'
+    const char *zone_identifier = strchr(aHostname, '%');
+    if (zone_identifier != nullptr) {
+      uint8_t zone_id = 0;
+      // check if zone id is valid
+      if (strncmp(zone_identifier, "%st", 3) == 0) {
+        IPAddress wifi_link_local;
+        if (WifiGetIPv6LinkLocal(&wifi_link_local)) {
+          zone_id = wifi_link_local.zone();
+        }
+      } else if (strncmp(zone_identifier, "%en", 3) == 0) {
+        IPAddress eth_link_local;
+        if (EthernetGetIPv6LinkLocal(&eth_link_local)) {
+          zone_id = eth_link_local.zone();
+        }
+      }
+      if (zone_id) {
+        // convert to ip_addr_t which is currently the only way to change the zone_id
+        ip_addr_t ip_addr;
+        addr.to_ip_addr_t(&ip_addr);
+        ip_addr.u_addr.ip6.zone = zone_id;
+        addr = IPAddress(&ip_addr);
+      }
+    }
+  }
+#endif
+}
+
 /**
  * Resolve the given hostname to an IP address.
  * @param aHostname     Name to be resolved
@@ -281,6 +319,7 @@ int WiFiHelper::hostByName(const char* aHostname, IPAddress& aResult, int32_t ti
   if (!ip_addr_isany_val(dns_ipaddr)) {
 #ifdef USE_IPV6
     aResult.from_ip_addr_t(&dns_ipaddr);
+    WiFiHelper::IPv6ZoneAutoFix(aResult, aHostname);
 #else // USE_IPV6
     aResult = ip_addr_get_ip4_u32(&dns_ipaddr);
 #endif // USE_IPV6

lib/default/WiFiHelper/src/WiFiHelper_ESP8266.cpp

@@ -77,4 +77,6 @@ String WiFiHelper::macAddress(void) {
   return WiFi.macAddress();
 }
 
+void WiFiHelper::IPv6ZoneAutoFix(IPAddress &addr, const char* aHostname) {
+}
 #endif // ESP8266

tasmota/tasmota_support/support_wifi.ino

@@ -1278,6 +1278,7 @@ bool WifiHostByName(const char* aHostname, IPAddress& aResult) {
 #if ESP_IDF_VERSION_MAJOR >= 5
   // try converting directly to IP
   if (aResult.fromString(aHostname)) {
+    WiFiHelper::IPv6ZoneAutoFix(aResult, aHostname);
     return true;   // we're done
   }
 #endif