satcat5::coap::Writer Class Reference

Detailed Description

Message formatting for the Constrained Applications Protocol (CoAP).

This class implements message formatting for the Constrained Applications Protocol (CoAP) defined in IETF RFC-7252: https://www.rfc-editor.org/rfc/rfc7252

The coap::Writer object is typically ephemeral:

• Create a coap::Writer object, attached to any Writeable sink.
• Call write_header(...) to write the CoAP header.
• Call write_option(...) for each desired option field.
• Call write_data(...) to write data and finalize the message.

Definition at line 26 of file coap_writer.h.

#include <coap_writer.h>

Collaboration diagram for satcat5::coap::Writer:

Public Member Functions
constexpr	Writer (satcat5::io::Writeable *dst, bool write_max_age=true)
	Create this object and set the destination. More...
bool	ready () const
	Is this object ready for writing? Note: This is the only safe method if m_dst is null.
bool	write_header (u8 type, Code code, u16 msg_id, u64 token=0, u8 tkl=0)
	Always start by writing the header, with optional token. More...
bool	write_header (Code code, Connection *request)
	Alternate version of write_header for responding to a query. More...
bool	write_uri (u16 id, const char *str)
	Convert a URI to consecutive Uri-Path options.
satcat5::io::Writeable *	write_data ()
	After the last option, start writing message data. More...
bool	write_finalize ()
	After the last option, finish with an empty message.
bool	write_option (u16 id, unsigned len, const void *data)
	Write option(s) one at a time, in various formats. More...
bool	write_option (u16 id, const char *str)
	Write option(s) one at a time, in various formats. More...
bool	write_option (u16 id, u64 value)
	Write option(s) one at a time, in various formats. More...

Protected Member Functions
bool	write_optid (u16 id, unsigned len)
void	write_varint (u64 x, unsigned len)
void	insert_max_age (u16 next_id=0)

Protected Attributes
satcat5::io::Writeable *const	m_dst
u16	m_last_opt
	Previous option-ID.
bool	m_insert_max_age
	Add Max-Age=0 to disable caching.

Constructor & Destructor Documentation

Writer()

constexpr satcat5::coap::Writer::Writer ( satcat5::io::Writeable *  dst, bool  write_max_age = true  )

inlineconstexpr

Create this object and set the destination.

Note: The resulting object is safe to use even if dst is null.

Definition at line 30 of file coap_writer.h.

Member Function Documentation

write_data()

satcat5::io::Writeable * Writer::write_data

(

)

After the last option, start writing message data.

Call this method exactly once, then finalize when ready.

Definition at line 88 of file coap_writer.cc.

write_header() [1/2]

bool Writer::write_header	(	Code	code,
		Connection *	request
	)

Alternate version of write_header for responding to a query.

Automatically determines the response type, then copies the message-ID and token directly from the incoming request.

Definition at line 43 of file coap_writer.cc.

write_header() [2/2]

bool Writer::write_header	(	u8	type,
		Code	code,
		u16	msg_id,
		u64	token = 0,
		u8	tkl = 0
	)

Always start by writing the header, with optional token.

Token length can be set manually (tkl > 0) or automatically.

Definition at line 25 of file coap_writer.cc.

write_option() [1/3]

bool Writer::write_option	(	u16	id,
		const char *	str
	)

Write option(s) one at a time, in various formats.

Note: Options MUST be written in ascending-ID order.

Definition at line 57 of file coap_writer.cc.

write_option() [2/3]

bool Writer::write_option	(	u16	id,
		u64	value
	)

Write option(s) one at a time, in various formats.

Note: Options MUST be written in ascending-ID order.

Definition at line 61 of file coap_writer.cc.

write_option() [3/3]

bool Writer::write_option	(	u16	id,
		unsigned	len,
		const void *	data
	)

Write option(s) one at a time, in various formats.

Note: Options MUST be written in ascending-ID order.

Definition at line 49 of file coap_writer.cc.

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The documentation for this class was generated from the following files:

• coap_writer.h
• coap_writer.cc