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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#pragma once
#include "context.h"
class FNET_DataBuffer;
class FNET_Packet;
/**
* Class used to do custom streaming of packets on network
* connections. The application is responsible for implementing the
* functionality of the packet streamer. It is recommended that it is
* backed by a packet factory object.
**/
class FNET_IPacketStreamer
{
public:
/**
* Destructor. No cleanup needed for base class.
*/
virtual ~FNET_IPacketStreamer() { }
/**
* This method is called to obtain information about the next packet
* located in the databuffer. The information obtained by calling
* this method is used to resolve the application context of the
* channel that should receive the packet and to ensure that the
* entire packet is read into the databuffer before the @ref Decode
* method is invoked. If this method returns true, the 'plen' output
* value will contain the number of bytes required to be located in
* the databuffer before the @ref Decode method is invoked. This
* method is also the place for packet header syncing, as it is
* allowed to discard data from the source databuffer. If this
* method returns false, it should be called again after more data
* is read into the source databuffer.
*
* If the contents of the source databuffer is not a valid packet
* header, the 'broken' flag may be raised to indicate that the
* connection should be closed due to illegal data being sent.
*
* @return true on success/false on fail
* @param src databuffer to read packet information from
* @param plen where to store packet length
* @param pcode where to store the packet code
* @param chid where to store the packet chid
* @param broken where to signal broken data
**/
virtual bool GetPacketInfo(FNET_DataBuffer *src, uint32_t *plen,
uint32_t *pcode, uint32_t *chid,
bool *broken) = 0;
/**
* This method is called to un-stream a packet from the given
* databuffer. This method will only be called after a call to the
* @ref GetPacketInfo returns true and a number of bytes equal the
* packet size indicated by that method is available in the
* databuffer. The context of the channel that will receive the
* packet is given as a parameter to this method in order to allow
* application-layer customizations such as using memory pools. The
* packet length and packet code output values from the @ref
* GetPacketInfo method are given as parameters to this method to
* avoid the need to parse the packet header twice.
*
* @return packet decoded from 'buf' or nullptr on failure
* @param src buffer with the serialized packet
* @param plen packet length as reported by @ref GetPacketInfo
* @param pcode packet code as reported by @ref GetPacketInfo
* @param context application context for target channel
**/
virtual FNET_Packet *Decode(FNET_DataBuffer *src, uint32_t plen,
uint32_t pcode, FNET_Context context) = 0;
/**
* This method is called to stream a packet to the given databuffer.
*
* @param packet the packet to stream
* @param chid channel id for packet
* @param dst the target buffer for streaming
**/
virtual void Encode(FNET_Packet *packet, uint32_t chid,
FNET_DataBuffer *dst) = 0;
};
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