ot::Coap::Option::Iterator::InitOrAdvance() method

Initializes the iterator to iterate over CoAP Options in a CoAP message. The iterator MUST be initialized before any other methods are used, otherwise its behavior is undefined. After initialization, the iterator is either updated to point to the first option, or it is marked as done (i.e., `IsDone()` returns `true`) when there is no option or if there is a parse error.

Sends a CoAP message with custom transmission parameters. If a response for a request is expected, respective function and context information should be provided. If no response is expected, these arguments should be `nullptr` pointers. If Message ID was not set in the header (equal to 0), this method will assign unique Message ID to the message.

Adds a message to the end of the queue.

Sets the Token value and length by copying it from another given message.

Removes a message from the queue.

Removes a message from the queue and frees it.

Sends a CoAP ACK message on which a dummy CoAP response is piggybacked.

Sends a CoAP message over secure DTLS connection. If a response for a request is expected, respective function and context information should be provided. If no response is expected, these arguments should be nullptr pointers. If Message Id was not set in the header (equal to 0), this function will assign unique Message Id to the message.

Gets the next Network Diagnostic TLV in a given message.

Checks if Tokens in two CoAP headers are equal.

Sets a default response header based on request header.

Sends a CoAP reset message.

Sends header-only CoAP response message.

Processes a MGMT_GET request message and prepares the response.

Sends a CoAP ACK empty message which is used in Separate Response for confirmable requests.

Sends a header-only CoAP message to indicate no resource matched for the request.

Processes a MGMT_COMMISSIONER_GET request message and prepares the response.

Appends a CoAP option reading Option value from another or potentially the same message.

Adds a given response to the cache. If matching response (the same Message ID, source endpoint address and port) exists in the cache given response is not added. The CoAP response is copied before it is added to the cache.

Gets a copy of CoAP response from the cache that matches a given Message ID and source endpoint.

Allocates and initializes a new CoAP response message with Network Control priority level for a given request message. The CoAP header is initialized as `kTypeAck` with `kCodeChanged`. The token and message ID is copied from @p aRequest. This method also sets the payload marker (calling `SetPayloadMarker()`). Even if message has no payload, calling `SetPayloadMarker()` is harmless, since `SendMessage()` will check and remove the payload marker when there is no payload.

Allocates and initializes a new CoAP response message with regular priority level for a given request message. The CoAP header is initialized as `kTypeAck` with `kCodeChanged`. The token and message ID is copied from @p aRequest. This method also sets the payload marker (calling `SetPayloadMarker()`). Even if message has no payload, calling `SetPayloadMarker()` is harmless, since `SendMessage()` will check and remove the payload marker when there is no payload.