mdns: workarround in 3.1 to fix missing netif re-probing when ip changed in link-local addressing

components/mdns/mdns.c

@@ -3005,6 +3005,9 @@ clear_rx_packet:
  */
 void _mdns_enable_pcb(tcpip_adapter_if_t tcpip_if, mdns_ip_protocol_t ip_protocol)
 {
+    if (_mdns_server->interfaces[tcpip_if].pcbs[ip_protocol].pcb && _mdns_pcb_is_ip_updated(tcpip_if, ip_protocol)) {
+        _mdns_pcb_deinit(tcpip_if, ip_protocol);
+    }
     if (!_mdns_server->interfaces[tcpip_if].pcbs[ip_protocol].pcb) {
         if (_mdns_pcb_init(tcpip_if, ip_protocol)) {
             return;

components/mdns/mdns_networking.c

@@ -7,7 +7,6 @@
 #include "mdns_networking.h"
 #include "esp_log.h"
 
-
 extern mdns_server_t * _mdns_server;
 
 /*
@@ -109,6 +108,7 @@ static void _udp_pcb_deinit(tcpip_adapter_if_t tcpip_if, mdns_ip_protocol_t ip_p
     }
 }
 
+
 /**
  * @brief  Start PCB V4
  */
@@ -147,6 +147,7 @@ static esp_err_t _udp_pcb_v4_init(tcpip_adapter_if_t tcpip_if)
     pcb->remote_port = MDNS_SERVICE_PORT;
     ip_addr_copy(pcb->multicast_ip, interface_addr);
     ip_addr_copy(pcb->remote_ip, multicast_addr);
+    ip_addr_copy(_mdns_server->interfaces[tcpip_if].pcbs[MDNS_IP_PROTOCOL_V4].if_addr, interface_addr);
 
     _mdns_server->interfaces[tcpip_if].pcbs[MDNS_IP_PROTOCOL_V4].pcb = pcb;
     _mdns_server->interfaces[tcpip_if].pcbs[MDNS_IP_PROTOCOL_V4].failed_probes = 0;
@@ -188,6 +189,7 @@ static esp_err_t _udp_pcb_v6_init(tcpip_adapter_if_t tcpip_if)
 
     pcb->remote_port = MDNS_SERVICE_PORT;
     ip_addr_copy(pcb->remote_ip, multicast_addr);
+    ip_addr_copy(_mdns_server->interfaces[tcpip_if].pcbs[MDNS_IP_PROTOCOL_V6].if_addr, interface_addr);
 
     _mdns_server->interfaces[tcpip_if].pcbs[MDNS_IP_PROTOCOL_V6].pcb = pcb;
     _mdns_server->interfaces[tcpip_if].pcbs[MDNS_IP_PROTOCOL_V6].failed_probes = 0;
@@ -304,3 +306,28 @@ size_t _mdns_udp_pcb_write(tcpip_adapter_if_t tcpip_if, mdns_ip_protocol_t ip_pr
     }
     return len;
 }
+
+bool _mdns_pcb_is_ip_updated(tcpip_adapter_if_t tcpip_if, mdns_ip_protocol_t ip_protocol)
+{
+    tcpip_adapter_ip_info_t if_ip_info;
+    if (!_mdns_server || !_mdns_server->interfaces[tcpip_if].pcbs[ip_protocol].pcb) {
+        return false;
+    }
+    mdns_pcb_t pcb = _mdns_server->interfaces[tcpip_if].pcbs[ip_protocol];
+
+    if (ip_protocol == MDNS_IP_PROTOCOL_V4) {
+        if (tcpip_adapter_get_ip_info(tcpip_if, &if_ip_info) || if_ip_info.ip.addr == 0) {
+            return false;
+        }
+        ip_addr_t interface_addr = IPADDR4_INIT(if_ip_info.ip.addr);
+        return !ip_addr_cmp(&interface_addr, &pcb.if_addr);
+    } else if (ip_protocol == MDNS_IP_PROTOCOL_V6) {
+        ip_addr_t interface_addr;
+        interface_addr.type = IPADDR_TYPE_V6;
+        if (tcpip_adapter_get_ip6_linklocal(tcpip_if, &interface_addr.u_addr.ip6)) {
+            return false;
+        }
+        return !ip_addr_cmp(&interface_addr, &pcb.if_addr);
+    }
+    return false;
+}

components/mdns/private_include/mdns_networking.h

@@ -49,4 +49,17 @@ esp_err_t _mdns_pcb_deinit(tcpip_adapter_if_t tcpip_if, mdns_ip_protocol_t ip_pr
  */
 size_t _mdns_udp_pcb_write(tcpip_adapter_if_t tcpip_if, mdns_ip_protocol_t ip_protocol, const ip_addr_t *ip, uint16_t port, uint8_t * data, size_t len);
 
+/**
+ * @brief  Compares currently opened pcb's interface ip address with currently assigned tcpip address
+ *
+ * When new IP address is assigned this function can be called if current pcb uses the same IP address
+ * and thus can be reused. Otherwise pcb needs to be reinitialized as it is tightly coupled with it's IP
+ *
+ * @param  tcpip_if    interface type
+ * @param  ip_protocol protocol type
+ *
+ * @return true if current address if different from the one used in pcb
+ */
+bool _mdns_pcb_is_ip_updated(tcpip_adapter_if_t tcpip_if, mdns_ip_protocol_t ip_protocol);
+
 #endif /* ESP_MDNS_NETWORKING_H_ */

components/mdns/private_include/mdns_private.h

@@ -297,6 +297,7 @@ typedef struct {
     uint8_t probe_ip;
     uint8_t probe_running;
     uint16_t failed_probes;
+    ip_addr_t if_addr;
 } mdns_pcb_t;
 
 typedef enum {