Struct EncodedMessage

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pub struct EncodedMessage<'data> { /* private fields */ }

Expand description

Encoded CoAP Message as it will be transmitted/received

Implementations§

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impl<'data> EncodedMessage<'data>

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pub fn try_new(data: &'data [u8]) -> Result<Self, Error>

Make a new Message from the data. This method only fails if the message is shorter than 4 bytes, i.e. the 4-bytes header is not even complete. This is checked here first because like that, some of the accessor methods do not need to return a Result but can access the header directly in a safe way.

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pub fn new_ack(message_id: u16, buf: &'data mut [u8; 4]) -> Self

Convenience constructor for encoded ACKs (can not be used for piggybacked responses)

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pub fn new_rst(message_id: u16, buf: &'data mut [u8; 4]) -> Self

Convenience constructor for encoded RSTs

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pub fn new_ping(message_id: u16, buf: &'data mut [u8; 4]) -> Self

Convenience constructor for encoded pings

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pub fn ack(message_id: u16) -> [u8; 4]

Convenience method for creating an encoded ACK

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pub fn rst(message_id: u16) -> [u8; 4]

Convenience method for creating an encoded RST

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pub fn ping(message_id: u16) -> [u8; 4]

Convenience method for creating an encoded ping

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pub fn message_length(&self) -> usize

Length of the message

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pub fn version(&self) -> u8

CoAP Protocol Version

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pub fn message_type(&self) -> Type

Type of the message

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pub fn code(&self) -> Result<Code, Error>

Code of the message

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pub fn message_id(&self) -> u16

Id of the message

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pub fn token(&self) -> Result<Token, Error>

Token of the message

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pub fn options_iter<'encmsg>( &'encmsg self, ) -> Result<OptionIterator<'encmsg, 'data>, Error>

Iterator over all options in this message. This parses the message options every time it is called, so be careful with calls to this iterator.

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pub fn payload(&self) -> Result<Option<&'data [u8]>, Error>

Return a reference to the payload of the message, if there is any

To determine the payload offset (i.e. find the payload marker after the options), all options must be iterated. Since the OptionIterator is generic on the maximum option size and this requirement bubbles up, this method requires a MAX_OPTION_SIZE, too. Specify a large enough value here (the same as for accessing the options), otherwise iterating the options will fail.

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pub fn is_empty(&self) -> Result<bool, Error>

Checks if the message has Code::Empty

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pub fn is_request(&self) -> Result<bool, Error>

Checks if the message has a RequestCode

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pub fn is_response(&self) -> Result<bool, Error>

Checks if the message has a ResponseCode

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pub fn is_empty_ack(&self) -> Result<bool, Error>

Checks if the message is an empty ACK (an ACK which is not a piggybacked response)

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pub fn is_rst(&self) -> Result<bool, Error>

Checks if the message is a RST (checks that the type is RST and the message is empty)

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pub fn is_ping(&self) -> Result<bool, Error>

Checks if the message is a ping (an empty CON message)

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pub fn check_msg_format<const MAX_OPTION_SIZE: usize>( &self, ) -> Result<(), Error>

Checks that a valid code and token length is used. If this method succeeds, EncodedMessage::code, EncodedMessage::is_empty, EncodedMessage::is_request, EncodedMessage::is_response and EncodedMessage::token are guaranteed to succeed and the results can safely be unwrapped.
Checks that “Table 1. Usage of Message Types from RFC 7252” is not violated:

+----------+-----+-----+-----+-----+
|          | CON | NON | ACK | RST |
+----------+-----+-----+-----+-----+
| Request  | X   | X   | -   | -   |
| Response | X   | X   | X   | -   |
| Empty    | *   | -   | X   | X   |
+----------+-----+-----+-----+-----+

Checks that “empty” messages are actually empty (only the 4-bytes header is present, i.e. zero-length token, no options, no payload).

For efficiency, this method only does cheap checks. Specifically, it does not iterate the options (after all, we are not decoding the full message here). So even if this check succeeds, iterating the options or getting the payload may still fail.