/*
* Copyright (c) 2001-2004 Swedish Institute of Computer Science.
* All rights reserved. 
* 
* Redistribution and use in source and binary forms, with or without modification, 
* are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
*    this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice,
*    this list of conditions and the following disclaimer in the documentation
*    and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
*    derived from this software without specific prior written permission. 
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED 
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT 
* SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT 
* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING 
* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY 
* OF SUCH DAMAGE.
*
* This file is part of and a contribution to the lwIP TCP/IP stack.
*
* Credits go to Adam Dunkels (and the current maintainers) of this software.
*
* Christiaan Simons rewrote this file to get a more stable echo example.
*/

/**
* @file
* TCP echo server example using raw API.
*
* Echos all bytes sent by connecting client,
* and passively closes when client is done.
*
*/

#include "C:\Program Files (x86)\Arduino\libraries\Lwip\lwip\src\include\lwip\opt.h"
#include "C:\Program Files (x86)\Arduino\libraries\Lwip\lwip\src\include\lwip\debug.h"
#include "C:\Program Files (x86)\Arduino\libraries\Lwip\lwip\src\include\lwip\stats.h"
#include "C:\Program Files (x86)\Arduino\libraries\Lwip\lwip\src\include\lwip\tcp.h"
#include "C:\Program Files (x86)\Arduino\libraries\Lwip\lwip\apps\tcpecho_raw\echo.h"

#if LWIP_TCP

static struct tcp_pcb *echo_pcb;

enum echo_states
{
	ES_NONE = 0,
	ES_ACCEPTED,
	ES_RECEIVED,
	ES_CLOSING
};

struct echo_state
{
	u8_t state;
	u8_t retries;
	struct tcp_pcb *pcb;
	/* pbuf (chain) to recycle */
	struct pbuf *p;
};

err_t echo_accept(void *arg, struct tcp_pcb *newpcb, err_t err);
err_t echo_recv(void *arg, struct tcp_pcb *tpcb, struct pbuf *p, err_t err);
void echo_error(void *arg, err_t err);
err_t echo_poll(void *arg, struct tcp_pcb *tpcb);
err_t echo_sent(void *arg, struct tcp_pcb *tpcb, u16_t len);
void echo_send(struct tcp_pcb *tpcb, struct echo_state *es);
void echo_close(struct tcp_pcb *tpcb, struct echo_state *es);

void
	echo_init(void)
{
	echo_pcb = tcp_new();
	if (echo_pcb != NULL)
	{
		err_t err;
		
		err = tcp_bind(echo_pcb, IP_ADDR_ANY, 7);
		if (err == ERR_OK)
		{
			echo_pcb = tcp_listen(echo_pcb);
			tcp_accept(echo_pcb, echo_accept);
		}
		else 
		{
			//DEBUG_MSG("TCP Bind fail! \r\n");
		}
	}
	else
	{
		//DEBUG_MSG("TCP new PCB fail! \r\n");
	}
}


err_t
	echo_accept(void *arg, struct tcp_pcb *newpcb, err_t err)
{
	err_t ret_err;
	struct echo_state *es;

	LWIP_UNUSED_ARG(arg);
	LWIP_UNUSED_ARG(err);

	/* Unless this pcb should have NORMAL priority, set its priority now.
	When running out of pcbs, low priority pcbs can be aborted to create
	new pcbs of higher priority. */
	tcp_setprio(newpcb, TCP_PRIO_MIN);

	es = (struct echo_state *)mem_malloc(sizeof(struct echo_state));
	if (es != NULL)
	{
		es->state = ES_ACCEPTED;
		es->pcb = newpcb;
		es->retries = 0;
		es->p = NULL;
		/* pass newly allocated es to our callbacks */
		tcp_arg(newpcb, es);
		tcp_recv(newpcb, echo_recv);
		tcp_err(newpcb, echo_error);
		tcp_poll(newpcb, echo_poll, 0);
		ret_err = ERR_OK;
	}
	else
	{
		ret_err = ERR_MEM;
	}
	return ret_err;  
}

err_t
	echo_recv(void *arg, struct tcp_pcb *tpcb, struct pbuf *p, err_t err)
{
	struct echo_state *es;
	err_t ret_err;

	LWIP_ASSERT("arg != NULL",arg != NULL);
	es = (struct echo_state *)arg;
	if (p == NULL)
	{
		/* remote host closed connection */
		es->state = ES_CLOSING;
		if(es->p == NULL)
		{
			/* we're done sending, close it */
			echo_close(tpcb, es);
		}
		else
		{
			/* we're not done yet */
			tcp_sent(tpcb, echo_sent);
			echo_send(tpcb, es);
		}
		ret_err = ERR_OK;
	}
	else if(err != ERR_OK)
	{
		/* cleanup, for unkown reason */
		if (p != NULL)
		{
			es->p = NULL;
			pbuf_free(p);
		}
		ret_err = err;
	}
	else if(es->state == ES_ACCEPTED)
	{
		/* first data chunk in p->payload */
		es->state = ES_RECEIVED;
		/* store reference to incoming pbuf (chain) */
		es->p = p;
		/* install send completion notifier */
		tcp_sent(tpcb, echo_sent);
		echo_send(tpcb, es);
		ret_err = ERR_OK;
	}
	else if (es->state == ES_RECEIVED)
	{
		/* read some more data */
		if(es->p == NULL)
		{
			es->p = p;
			tcp_sent(tpcb, echo_sent);
			echo_send(tpcb, es);
		}
		else
		{
			struct pbuf *ptr;

			/* chain pbufs to the end of what we recv'ed previously  */
			ptr = es->p;
			pbuf_chain(ptr,p);
		}
		ret_err = ERR_OK;
	}
	else if(es->state == ES_CLOSING)
	{
		/* odd case, remote side closing twice, trash data */
		tcp_recved(tpcb, p->tot_len);
		es->p = NULL;
		pbuf_free(p);
		ret_err = ERR_OK;
	}
	else
	{
		/* unkown es->state, trash data  */
		tcp_recved(tpcb, p->tot_len);
		es->p = NULL;
		pbuf_free(p);
		ret_err = ERR_OK;
	}
	return ret_err;
}

void
	echo_error(void *arg, err_t err)
{
	struct echo_state *es;

	LWIP_UNUSED_ARG(err);

	es = (struct echo_state *)arg;
	if (es != NULL)
	{
		mem_free(es);
	}
}

err_t
	echo_poll(void *arg, struct tcp_pcb *tpcb)
{
	err_t ret_err;
	struct echo_state *es;

	es = (struct echo_state *)arg;
	if (es != NULL)
	{
		if (es->p != NULL)
		{
			/* there is a remaining pbuf (chain)  */
			tcp_sent(tpcb, echo_sent);
			echo_send(tpcb, es);
		}
		else
		{
			/* no remaining pbuf (chain)  */
			if(es->state == ES_CLOSING)
			{
				echo_close(tpcb, es);
			}
		}
		ret_err = ERR_OK;
	}
	else
	{
		/* nothing to be done */
		tcp_abort(tpcb);
		ret_err = ERR_ABRT;
	}
	return ret_err;
}

err_t
	echo_sent(void *arg, struct tcp_pcb *tpcb, u16_t len)
{
	struct echo_state *es;

	LWIP_UNUSED_ARG(len);

	es = (struct echo_state *)arg;
	es->retries = 0;

	if(es->p != NULL)
	{
		/* still got pbufs to send */
		tcp_sent(tpcb, echo_sent);
		echo_send(tpcb, es);
	}
	else
	{
		/* no more pbufs to send */
		if(es->state == ES_CLOSING)
		{
			echo_close(tpcb, es);
		}
	}
	return ERR_OK;
}

void
	echo_send(struct tcp_pcb *tpcb, struct echo_state *es)
{
	struct pbuf *ptr;
	err_t wr_err = ERR_OK;

	while ((wr_err == ERR_OK) &&
		(es->p != NULL) && 
		(es->p->len <= tcp_sndbuf(tpcb)))
	{
		ptr = es->p;

		/* enqueue data for transmission */
		wr_err = tcp_write(tpcb, ptr->payload, ptr->len, 1);
		if (wr_err == ERR_OK)
		{
			u16_t plen;
			u8_t freed;

			plen = ptr->len;
			/* continue with next pbuf in chain (if any) */
			es->p = ptr->next;
			if(es->p != NULL)
			{
				/* new reference! */
				pbuf_ref(es->p);
			}
			/* chop first pbuf from chain */
			do
			{
				/* try hard to free pbuf */
				freed = pbuf_free(ptr);
			}
			while(freed == 0);
			/* we can read more data now */
			tcp_recved(tpcb, plen);
		}
		else if(wr_err == ERR_MEM)
		{
			/* we are low on memory, try later / harder, defer to poll */
			es->p = ptr;
		}
		else
		{
			/* other problem ?? */
		}
	}
}

void
	echo_close(struct tcp_pcb *tpcb, struct echo_state *es)
{
	tcp_arg(tpcb, NULL);
	tcp_sent(tpcb, NULL);
	tcp_recv(tpcb, NULL);
	tcp_err(tpcb, NULL);
	tcp_poll(tpcb, NULL, 0);

	if (es != NULL)
	{
		mem_free(es);
	}  
	tcp_close(tpcb);
}

#endif /* LWIP_TCP */