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MDNS
Modules | Functions

MDNS
[Applications]

RFC 6762 - Multicast DNS
RFC 6763 - DNS-Based Service Discovery
. More...

Modules

 Options

Functions

void mdns_resp_init (void)
 Initiate MDNS responder.
void mdns_resp_netif_settings_changed (struct netif *netif)
 Announce IP settings have changed on netif.
err_t mdns_resp_add_netif (struct netif *netif, const char *hostname, u32_t dns_ttl)
 Activate MDNS responder for a network interface and send announce packets.
err_t mdns_resp_remove_netif (struct netif *netif)
 Stop responding to MDNS queries on this interface, leave multicast groups, and free the helper structure and any of its services.
err_t mdns_resp_add_service (struct netif *netif, const char *name, const char *service, enum mdns_sd_proto proto, u16_t port, u32_t dns_ttl, service_get_txt_fn_t txt_fn, void *txt_data)
 Add a service to the selected network interface.
err_t mdns_resp_add_service_txtitem (struct mdns_service *service, const char *txt, u8_t txt_len)
 Call this function from inside the service_get_txt_fn_t callback to add text data.

Detailed Description

RFC 6762 - Multicast DNS
RFC 6763 - DNS-Based Service Discovery
. 

Things left to implement: -------------------------


    

  • Probing/conflict resolution
    • 

  • Sending goodbye messages (zero ttl) - shutdown, DHCP lease about to expire, DHCP turned off...
    • 

  • Checking that source address of unicast requests are on the same network
    • 

  • Limiting multicast responses to 1 per second per resource record
    • 

  • Fragmenting replies if required
    • 

  • Subscribe to netif address/link change events and act on them (currently needs to be done manually)
    • 

  • Handling multi-packet known answers
    • 

  • Individual known answer detection for all local IPv6 addresses
    • 

  • Dynamic size of outgoing packet 
    • 



Function Documentation






      

        

          err_t mdns_resp_add_netif 
          (
          struct netif * 
           netif, 
        

        

          
          
          const char * 
           hostname, 
        

        

          
          
          u32_t 
           dns_ttl 
        

        

          
          )
          
        

      







Activate MDNS responder for a network interface and send announce packets. 


Parameters:

  

    
netifThe network interface to activate. 

    
hostnameName to use. Queries for <hostname>.local will be answered with the IP addresses of the netif. The hostname will be copied, the given pointer can be on the stack. 

    
dns_ttlValidity time in seconds to send out for IP address data in DNS replies 

  

  




Returns:
ERR_OK if netif was added, an err_t otherwise 



Definition at line 1867 of file lwip_mdns.c.











      

        

          err_t mdns_resp_add_service 
          (
          struct netif * 
           netif, 
        

        

          
          
          const char * 
           name, 
        

        

          
          
          const char * 
           service, 
        

        

          
          
          enum mdns_sd_proto 
           proto, 
        

        

          
          
          u16_t 
           port, 
        

        

          
          
          u32_t 
           dns_ttl, 
        

        

          
          
          service_get_txt_fn_t 
           txt_fn, 
        

        

          
          
          void * 
           txt_data 
        

        

          
          )
          
        

      







Add a service to the selected network interface. 


Parameters:

  

    
netifThe network interface to publish this service on 

    
nameThe name of the service 

    
serviceThe service type, like "_http" 

    
protoThe service protocol, DNSSD_PROTO_TCP for TCP ("_tcp") and DNSSD_PROTO_UDP for others ("_udp") 

    
portThe port the service listens to 

    
dns_ttlValidity time in seconds to send out for service data in DNS replies 

    
txt_fnCallback to get TXT data. Will be called each time a TXT reply is created to allow dynamic replies. 

    
txt_dataUserdata pointer for txt_fn 

  

  




Returns:
ERR_OK if the service was added to the netif, an err_t otherwise 



Definition at line 1961 of file lwip_mdns.c.











      

        

          err_t mdns_resp_add_service_txtitem 
          (
          struct mdns_service * 
           service, 
        

        

          
          
          const char * 
           txt, 
        

        

          
          
          u8_t 
           txt_len 
        

        

          
          )
          
        

      







Call this function from inside the service_get_txt_fn_t callback to add text data. 


Buffer for TXT data is 256 bytes, and each field is prefixed with a length byte. 


Parameters:

  

    
serviceThe service provided to the get_txt callback 

    
txtString to add to the TXT field. 

    
txt_lenLength of string 

  

  




Returns:
ERR_OK if the string was added to the reply, an err_t otherwise 



Definition at line 2020 of file lwip_mdns.c.











      

        

          void mdns_resp_init 
          (
          void 
           )
          
        

      







Initiate MDNS responder. 


Will open UDP sockets on port 5353 



Definition at line 1811 of file lwip_mdns.c.











      

        

          void mdns_resp_netif_settings_changed 
          (
          struct netif * 
           netif )
          
        

      







Announce IP settings have changed on netif. 


Call this in your callback registered by netif_set_status_callback(). This function may go away in the future when netif supports registering multiple callback functions. 


Parameters:

  

    
netifThe network interface where settings have changed. 

  

  





Definition at line 1839 of file lwip_mdns.c.











      

        

          err_t mdns_resp_remove_netif 
          (
          struct netif * 
           netif )
          
        

      







Stop responding to MDNS queries on this interface, leave multicast groups, and free the helper structure and any of its services. 


Parameters:

  

    
netifThe network interface to remove. 

  

  




Returns:
ERR_OK if netif was removed, an err_t otherwise 



Definition at line 1916 of file lwip_mdns.c.









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