TREL - Platform

This module includes the platform abstraction for Thread Radio Encapsulation Link (TREL) using DNS-SD and UDP/IPv6.

Summary

Typedefs
otPlatTrelCounters typedef
Represents a group of TREL related counters in the platform layer.
otPlatTrelPeerInfo typedef
Represents a TREL peer info discovered using DNS-SD browse on the service name "_trel._udp".

Functions
otPlatTrelDisable(otInstance *aInstance)
void
Disables TREL platform layer.
otPlatTrelEnable(otInstance *aInstance, uint16_t *aUdpPort)
void
Initializes and enables TREL platform layer.
otPlatTrelGetCounters(otInstance *aInstance)
Gets the pointer to the TREL counters in the platform layer.
otPlatTrelHandleDiscoveredPeerInfo(otInstance *aInstance, const otPlatTrelPeerInfo *aInfo)
void
This is a callback function from platform layer to report a discovered TREL peer info.
otPlatTrelHandleReceived(otInstance *aInstance, uint8_t *aBuffer, uint16_t aLength)
void
Is a callback from platform to notify of a received TREL UDP packet.
otPlatTrelRegisterService(otInstance *aInstance, uint16_t aPort, const uint8_t *aTxtData, uint8_t aTxtLength)
void
Registers a new service to be advertised using DNS-SD [RFC6763].
otPlatTrelResetCounters(otInstance *aInstance)
void
Resets the TREL counters in the platform layer.
otPlatTrelSend(otInstance *aInstance, const uint8_t *aUdpPayload, uint16_t aUdpPayloadLen, const otSockAddr *aDestSockAddr)
void
Requests a TREL UDP packet to be sent to a given destination.

Structs
otPlatTrelCounters

Represents a group of TREL related counters in the platform layer.

otPlatTrelPeerInfo

Represents a TREL peer info discovered using DNS-SD browse on the service name "_trel._udp".

Typedefs

otPlatTrelCounters

struct otPlatTrelCounters otPlatTrelCounters

Represents a group of TREL related counters in the platform layer.

otPlatTrelPeerInfo

struct otPlatTrelPeerInfo otPlatTrelPeerInfo

Represents a TREL peer info discovered using DNS-SD browse on the service name "_trel._udp".

Functions

otPlatTrelDisable

void otPlatTrelDisable(
  otInstance *aInstance
)

Disables TREL platform layer.

After this call, the platform layer MUST stop DNS-SD browse on the service name "_trel._udp", stop advertising the TREL DNS-SD service (from otPlatTrelRegisterService()) and MUST close the UDP socket used to receive TREL messages.

[in] aInstance The OpenThread instance.

otPlatTrelEnable

void otPlatTrelEnable(
  otInstance *aInstance,
  uint16_t *aUdpPort
)

Initializes and enables TREL platform layer.

Upon this call, the platform layer MUST perform the following:

1) TREL platform layer MUST open a UDP socket to listen for and receive TREL messages from peers. The socket is bound to an ephemeral port number chosen by the platform layer. The port number MUST be returned in aUdpPort. The socket is also bound to network interface(s) on which TREL is to be supported. The socket and the chosen port should stay valid while TREL is enabled.

2) Platform layer MUST initiate an ongoing DNS-SD browse on the service name "_trel._udp" within the local browsing domain to discover other devices supporting TREL. The ongoing browse will produce two different types of events: "add" events and "remove" events. When the browse is started, it should produce an "add" event for every TREL peer currently present on the network. Whenever a TREL peer goes offline, a "remove" event should be produced. "remove" events are not guaranteed, however. When a TREL service instance is discovered, a new ongoing DNS-SD query for an AAAA record should be started on the hostname indicated in the SRV record of the discovered instance. If multiple host IPv6 addressees are discovered for a peer, one with highest scope among all addresses MUST be reported (if there are multiple address at same scope, one must be selected randomly).

TREL platform MUST signal back the discovered peer info using otPlatTrelHandleDiscoveredPeerInfo() callback. This callback MUST be invoked when a new peer is discovered, when there is a change in an existing entry (e.g., new TXT record or new port number or new IPv6 address), or when the peer is removed.

Details
Parameters
[in] aInstance
The OpenThread instance.
[out] aUdpPort
A pointer to return the selected port number by platform layer.

otPlatTrelGetCounters

const otPlatTrelCounters * otPlatTrelGetCounters(
  otInstance *aInstance
)

Gets the pointer to the TREL counters in the platform layer.

Details
Parameters
[in] aInstance
The OpenThread instance structure.

otPlatTrelHandleDiscoveredPeerInfo

void otPlatTrelHandleDiscoveredPeerInfo(
  otInstance *aInstance,
  const otPlatTrelPeerInfo *aInfo
)

This is a callback function from platform layer to report a discovered TREL peer info.

Details
Parameters
[in] aInstance
The OpenThread instance.
[in] aInfo
A pointer to the TREL peer info.

otPlatTrelHandleReceived

void otPlatTrelHandleReceived(
  otInstance *aInstance,
  uint8_t *aBuffer,
  uint16_t aLength
)

Is a callback from platform to notify of a received TREL UDP packet.

Details
Parameters
[in] aInstance
The OpenThread instance structure.
[in] aBuffer
A buffer containing the received UDP payload.
[in] aLength
UDP payload length (number of bytes).

otPlatTrelRegisterService

void otPlatTrelRegisterService(
  otInstance *aInstance,
  uint16_t aPort,
  const uint8_t *aTxtData,
  uint8_t aTxtLength
)

Registers a new service to be advertised using DNS-SD [RFC6763].

The service name is "_trel._udp". The platform should use its own hostname, which when combined with the service name and the local DNS-SD domain name will produce the full service instance name, for example "example-host._trel._udp.local.".

The domain under which the service instance name appears will be 'local' for mDNS, and will be whatever domain is used for service registration in the case of a non-mDNS local DNS-SD service.

A subsequent call to this function updates the previous service. It is used to update the TXT record data and/or the port number.

The aTxtData buffer is not persisted after the return from this function. The platform layer MUST NOT keep the pointer and instead copy the content if needed.

Details
Parameters
[in] aInstance
The OpenThread instance.
[in] aPort
The port number to include in the SRV record of the advertised service.
[in] aTxtData
A pointer to the TXT record data (encoded) to be include in the advertised service.
[in] aTxtLength
The length of aTxtData (number of bytes).

otPlatTrelResetCounters

void otPlatTrelResetCounters(
  otInstance *aInstance
)

Resets the TREL counters in the platform layer.

Details
Parameters
[in] aInstance
The OpenThread instance structure.

otPlatTrelSend

void otPlatTrelSend(
  otInstance *aInstance,
  const uint8_t *aUdpPayload,
  uint16_t aUdpPayloadLen,
  const otSockAddr *aDestSockAddr
)

Requests a TREL UDP packet to be sent to a given destination.

Details
Parameters
[in] aInstance
The OpenThread instance structure.
[in] aUdpPayload
A pointer to UDP payload.
[in] aUdpPayloadLen
The payload length (number of bytes).
[in] aDestSockAddr
The destination socket address.

Resources

OpenThread API Reference topics originate from the source code, available on GitHub. For more information, or to contribute to our documentation, refer to Resources.