Multicast DNS#

This module defines platform APIs for Multicast DNS (mDNS) socket.

Modules#

otPlatMdnsAddressInfo

Typedefs#

typedef struct otPlatMdnsAddressInfo

Represents a socket address info.

Functions#

otPlatMdnsSetListeningEnabled(otInstance *aInstance, bool aEnable, uint32_t aInfraIfIndex)

Enables or disables listening for mDNS messages sent to mDNS port 5353.

void
otPlatMdnsSendMulticast(otInstance *aInstance, otMessage *aMessage, uint32_t aInfraIfIndex)

Sends an mDNS message as multicast.

void
otPlatMdnsSendUnicast(otInstance *aInstance, otMessage *aMessage, const otPlatMdnsAddressInfo *aAddress)

Sends an mDNS message as unicast.

void
otPlatMdnsHandleReceive(otInstance *aInstance, otMessage *aMessage, bool aIsUnicast, const otPlatMdnsAddressInfo *aAddress)

Callback to notify OpenThread mDNS module of a received message on UDP port 5353.

Typedef Documentation#

otPlatMdnsAddressInfo#

typedef struct otPlatMdnsAddressInfo otPlatMdnsAddressInfo

Represents a socket address info.


Definition at line 65 of file include/openthread/platform/mdns_socket.h

Function Documentation#

otPlatMdnsSetListeningEnabled#

otError otPlatMdnsSetListeningEnabled (otInstance * aInstance, bool aEnable, uint32_t aInfraIfIndex)

Enables or disables listening for mDNS messages sent to mDNS port 5353.

Parameters
[in]aInstance

The OpernThread instance.

[in]aEnable

Indicate whether to enable or disable.

[in]aInfraIfIndex

The infrastructure network interface index.

When listening is enabled, the platform MUST listen for multicast messages sent to UDP destination port 5353 at the mDNS link-local multicast address 224.0.0.251 and its IPv6 equivalent ff02::fb.

The platform SHOULD also listen for any unicast messages sent to UDP destination port 5353. If this is not possible, then OpenThread mDNS module can be configured to not use any "QU" questions requesting unicast response.

While enabled, all received messages MUST be reported back using otPlatMdnsHandleReceive() callback.


Definition at line 85 of file include/openthread/platform/mdns_socket.h

otPlatMdnsSendMulticast#

void otPlatMdnsSendMulticast (otInstance * aInstance, otMessage * aMessage, uint32_t aInfraIfIndex)

Sends an mDNS message as multicast.

Parameters
[in]aInstance

The OpenThread instance.

[in]aMessage

The mDNS message to multicast. Ownership is transferred to the platform layer.

[in]aInfraIfIndex

The infrastructure network interface index.

The platform MUST multicast the prepared mDNS message in aMessage as a UDP message using the mDNS well-known port number 5353 for both source and destination ports. The message MUST be sent to the mDNS link-local multicast address 224.0.0.251 and/or its IPv6 equivalent ff02::fb.

aMessage contains the mDNS message starting with DNS header at offset zero. It does not include IP or UDP headers. This function passes the ownership of aMessage to the platform layer and platform implementation MUST free aMessage once sent and no longer needed.

The platform MUST allow multicast loopback, i.e., the multicast message aMessage MUST also be received and passed back to OpenThread stack using otPlatMdnsHandleReceive() callback. This behavior is essential for the OpenThread mDNS stack to process and potentially respond to its own queries, while allowing other mDNS receivers to also receive the query and its response.


Definition at line 107 of file include/openthread/platform/mdns_socket.h

otPlatMdnsSendUnicast#

void otPlatMdnsSendUnicast (otInstance * aInstance, otMessage * aMessage, const otPlatMdnsAddressInfo * aAddress)

Sends an mDNS message as unicast.

Parameters
[in]aInstance

The OpenThread instance.

[in]aMessage

The mDNS message to multicast. Ownership is transferred to platform layer.

[in]aAddress

The destination address info.

The platform MUST send the prepared mDNS message in aMessage as a UDP message using source UDP port 5353 to the destination address and port number specified by aAddress.

aMessage contains the DNS message starting with the DNS header at offset zero. It does not include IP or UDP headers. This function passes the ownership of aMessage to the platform layer and platform implementation MUST free aMessage once sent and no longer needed.

The aAddress fields are as follows:

  • mAddress specifies the destination address. IPv4-mapped IPv6 format is used to represent an IPv4 destination.

  • mPort specifies the destination port.

  • mInfraIndex specifies the interface index.

If the @aAddress matches this devices address, the platform MUST ensure to receive and pass the message back to the OpenThread stack using otPlatMdnsHandleReceive() for processing.


Definition at line 132 of file include/openthread/platform/mdns_socket.h

otPlatMdnsHandleReceive#

void otPlatMdnsHandleReceive (otInstance * aInstance, otMessage * aMessage, bool aIsUnicast, const otPlatMdnsAddressInfo * aAddress)

Callback to notify OpenThread mDNS module of a received message on UDP port 5353.

Parameters
[in]aInstance

The OpenThread instance.

[in]aMessage

The received mDNS message. Ownership is transferred to the OpenThread stack.

[in]aIsUnicast

Indicates whether the received message is unicast or multicast.

[in]aAddress

The sender's address info.

aMessage MUST contain DNS message starting with the DNS header at offset zero. This function passes the ownership of aMessage from the platform layer to the OpenThread stack. The OpenThread stack will free the message once processed.

The aAddress fields are as follows:

  • mAddress specifies the sender's address. IPv4-mapped IPv6 format is used to represent an IPv4 destination.

  • mPort specifies the sender's port.

  • mInfraIndex specifies the interface index.


Definition at line 152 of file include/openthread/platform/mdns_socket.h