satcat5::net::Dispatch Class Reference

Detailed Description

The "Dispatch" is a generic interface that knows how to read a designated protocol layer and sort incoming packets to one of several protocols.

For example, the udp::Dispatch class (udp_dispatch.h) sorts packets by the UDP destination port. Most Dispatch implementations, including eth::Dispatch and ip::Dispatch, further provide a means for Protocols to send messages to an arbitrary address. However, this requires protocol-specific arguments that cannot be provided in the generic API.

Network "Dispatch" objects:

• Know their own address, and any other required parameters.
• Allow registration of one or more Protocols, each tied to a specific traffic stream (e.g., an EtherType or UDP port).
• Accept incoming frames and read header information.
• Apply filtering as needed for invalid frame headers.
• Route the remaining data to one of several Protocol objects, comparing header field(s) until a suitable match is found.
• Allow Protocol objects to send simple replies.

Definition at line 36 of file net_dispatch.h.

#include <net_dispatch.h>

Inheritance diagram for satcat5::net::Dispatch:

Collaboration diagram for satcat5::net::Dispatch:

Public Member Functions
virtual satcat5::io::Writeable *	open_reply (const satcat5::net::Type &type, unsigned len)=0
	Open a reply to the sender of the most recent message by writing frame header(s) and returning a stream where the caller should write frame data, then call write_finalize(). More...
void	add (satcat5::net::Protocol *proto)
	Register a Protocol object.
void	remove (satcat5::net::Protocol *proto)
	Unregister a Protocol object.
bool	bound (const satcat5::net::Type &type) const
	Check if a given net::Type has a matching Protocol.

Protected Member Functions
bool	deliver (const satcat5::net::Type &type, satcat5::io::Readable *src, unsigned len)
	Deliver current message by calling Protocol::frame_rcvd(...). More...
	Dispatch ()
	Constructor and destructor access restricted to children.
	~Dispatch ()
	Constructor and destructor access restricted to children.

Protected Attributes
satcat5::util::List< satcat5::net::Protocol >	m_list
	Linked list of Protocol objects.

Member Function Documentation

deliver()

bool Dispatch::deliver ( const satcat5::net::Type &  type, satcat5::io::Readable *  src, unsigned  len  )

protected

Deliver current message by calling Protocol::frame_rcvd(...).

Note: Caller is responsible for read_finalize(), if required.

Returns

True if a matching Protocol is found.

Definition at line 25 of file net_dispatch.cc.

open_reply()

virtual satcat5::io::Writeable* satcat5::net::Dispatch::open_reply ( const satcat5::net::Type &  type, unsigned  len  )

pure virtual

Open a reply to the sender of the most recent message by writing frame header(s) and returning a stream where the caller should write frame data, then call write_finalize().

The length argument is the number of bytes that will be written by the caller. (IPv4 and UDP require this information up-front.)

Returns zero if sending a reply is not currently possible.

Child MUST implement this method. Child SHOULD also provide an equivalent open_write(...) method for sending messages to other recipients, when practical. Child MAY ignore the "type" argument at its discretion.

Implemented in satcat5::udp::Dispatch, satcat5::ip::Dispatch, satcat5::eth::Dispatch, satcat5::ccsds_spp::Dispatch, and satcat5::ccsds_aos::Dispatch.

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

• net_dispatch.h
• net_dispatch.cc