espconn_tcp.c

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/******************************************************************************
 * Copyright 2013-2014 Espressif Systems (Wuxi)
 *
 * FileName: espconn_tcp.c
 *
 * Description: tcp proto interface
 *
 * Modification history:
 *     2014/3/31, v1.0 create this file.
*******************************************************************************/

#include "lwip/netif.h"
#include "lwip/inet.h"
#include "netif/etharp.h"
#include "lwip/tcp.h"
#include "lwip/ip.h"
#include "lwip/init.h"
#include "lwip/tcp_impl.h"
#include "lwip/memp.h"

#include "ets_sys.h"
#include "os_type.h"
//#include "os.h"
#include "lwip/mem.h"
#include "lwip/app/espconn_tcp.h"

#ifdef MEMLEAK_DEBUG
static const char mem_debug_file[] ICACHE_RODATA_ATTR = __FILE__;
#endif

extern espconn_msg *plink_active;
extern espconn_msg *pserver_list;
extern struct espconn_packet pktinfo[2];
extern struct tcp_pcb ** const tcp_pcb_lists[];

os_event_t espconn_TaskQueue[espconn_TaskQueueLen];

static err_t
espconn_client_recv(void *arg, struct tcp_pcb *pcb, struct pbuf *p, err_t err);
static void
espconn_client_close(void *arg, struct tcp_pcb *pcb,u8 type);

static err_t
espconn_server_recv(void *arg, struct tcp_pcb *pcb, struct pbuf *p, err_t err);
static void
espconn_server_close(void *arg, struct tcp_pcb *pcb,u8 type);

///////////////////////////////common function/////////////////////////////////
/******************************************************************************
 * FunctionName : espconn_kill_oldest
 * Description  : kill the oldest TCP block
 * Parameters   : none
 * Returns      : none
*******************************************************************************/
static void ICACHE_FLASH_ATTR
espconn_kill_oldest(void)
{
    struct tcp_pcb *pcb, *inactive;
    u32_t inactivity;

    inactivity = 0;
    inactive = NULL;
    /* Go through the list of TIME_WAIT pcbs and get the oldest pcb. */
    for (pcb = tcp_tw_pcbs; pcb != NULL; pcb = pcb->next) {
        if ((u32_t) (tcp_ticks - pcb->tmr) >= inactivity) {
            inactivity = tcp_ticks - pcb->tmr;
            inactive = pcb;
        }
    }
    if (inactive != NULL) {
        tcp_abort(inactive);
    }

    /* Go through the list of FIN_WAIT_2 pcbs and get the oldest pcb. */
    inactivity = 0;
    inactive = NULL;
    for (pcb = tcp_active_pcbs; pcb != NULL; pcb = pcb->next) {
        if (pcb->state == FIN_WAIT_1 || pcb->state == FIN_WAIT_2){
            if ((u32_t) (tcp_ticks - pcb->tmr) >= inactivity) {
                inactivity = tcp_ticks - pcb->tmr;
                inactive = pcb;
            }
        }
    }
    /*Purges the PCB, removes it from a PCB list and frees the memory*/
    if (inactive != NULL) {
        tcp_pcb_remove(&tcp_active_pcbs, inactive);
        memp_free(MEMP_TCP_PCB, inactive);
    }

    /* Go through the list of LAST_ACK pcbs and get the oldest pcb. */
    inactivity = 0;
    inactive = NULL;
    for (pcb = tcp_active_pcbs; pcb != NULL; pcb = pcb->next) {
        if (pcb->state == LAST_ACK) {
            if ((u32_t) (tcp_ticks - pcb->tmr) >= inactivity) {
                inactivity = tcp_ticks - pcb->tmr;
                inactive = pcb;
            }
        }
    }
    /*Purges the PCB, removes it from a PCB list and frees the memory*/
    if (inactive != NULL) {
        tcp_pcb_remove(&tcp_active_pcbs, inactive);
        memp_free(MEMP_TCP_PCB, inactive);
    }
}

/******************************************************************************
 * FunctionName : espconn_kill_oldest_pcb
 * Description  : find the oldest TCP block by state
 * Parameters   : none
 * Returns      : none
*******************************************************************************/
void ICACHE_FLASH_ATTR espconn_kill_oldest_pcb(void)
{
    struct tcp_pcb *cpcb = NULL;
    uint8 i = 0;
    uint8 num_tcp_fin = 0;
    for(i = 2; i < 4; i ++){
        for (cpcb = *tcp_pcb_lists[i]; cpcb != NULL; cpcb = cpcb->next) {
            if (cpcb->state == TIME_WAIT){
                num_tcp_fin ++;
                if (num_tcp_fin == MEMP_NUM_TCP_PCB)
                    break;
            }

            if (cpcb->state == FIN_WAIT_1 || cpcb->state == FIN_WAIT_2 || cpcb->state == LAST_ACK){
                num_tcp_fin++;
                if (num_tcp_fin == MEMP_NUM_TCP_PCB)
                    break;
            }
        }

        if (num_tcp_fin == MEMP_NUM_TCP_PCB){
            num_tcp_fin = 0;
            espconn_kill_oldest();
        } else if (cpcb == NULL){
            num_tcp_fin = 0;
        }
    }
}

/******************************************************************************
 * FunctionName : espconn_kill_pcb
 * Description  : kill all the TCP block by port
 * Parameters   : none
 * Returns      : none
*******************************************************************************/
void ICACHE_FLASH_ATTR espconn_kill_pcb(u16_t port)
{
    struct tcp_pcb *cpcb = NULL;
    uint8 i = 0;
    struct tcp_pcb *inactive = NULL;
    struct tcp_pcb *prev = NULL;
    u8_t pcb_remove;
    /* Check if the address already is in use (on all lists) */
    for (i = 1; i < 4; i++) {
        cpcb = *tcp_pcb_lists[i];
        while(cpcb != NULL){
            pcb_remove = 0;
            if (cpcb->local_port == port) {
                ++pcb_remove;
            }
            /* If the PCB should be removed, do it. */
            if (pcb_remove) {
                /* Remove PCB from tcp_pcb_lists list. */
                inactive = cpcb;
                cpcb = inactive->next;
                tcp_pcb_remove(tcp_pcb_lists[i], inactive);
                memp_free(MEMP_TCP_PCB, inactive);
            } else {
                cpcb = cpcb->next;
            }
        }
    }
}

/******************************************************************************
 * FunctionName : espconn_find_current_pcb
 * Description  : find the TCP block which option
 * Parameters   : pcurrent_msg -- the node in the list which active
 * Returns      : TCP block point
*******************************************************************************/
struct tcp_pcb *ICACHE_FLASH_ATTR espconn_find_current_pcb(espconn_msg *pcurrent_msg)
{
    uint16 local_port = pcurrent_msg->pcommon.local_port;
    uint32 local_ip = pcurrent_msg->pcommon.local_ip;
    uint16 remote_port = pcurrent_msg->pcommon.remote_port;
    uint32 remote_ip = *((uint32*)&pcurrent_msg->pcommon.remote_ip);
    struct tcp_pcb *find_pcb = NULL;
    if (pcurrent_msg ->preverse == NULL){/*Find the server's TCP block*/
        if (local_ip == 0|| local_port == 0) return pcurrent_msg->pcommon.pcb;

        for (find_pcb = tcp_active_pcbs; find_pcb != NULL; find_pcb = find_pcb->next){
            if ((find_pcb->remote_port == remote_port) && (find_pcb->remote_ip.addr == remote_ip) &&
                (find_pcb->local_port == local_port) && (find_pcb->local_ip.addr == local_ip))
                return find_pcb;
        }

        for (find_pcb = tcp_tw_pcbs; find_pcb != NULL; find_pcb = find_pcb->next){
            if ((find_pcb->remote_port == remote_port) && (find_pcb->remote_ip.addr == remote_ip) &&
                (find_pcb->local_port == local_port) && (find_pcb->local_ip.addr == local_ip))
                return find_pcb;
        }
    } else {/*Find the client's TCP block*/
        if (remote_ip == 0|| remote_port == 0) return pcurrent_msg->pcommon.pcb;

        for (find_pcb = tcp_active_pcbs; find_pcb != NULL; find_pcb = find_pcb->next){
            if ((find_pcb->remote_port == remote_port) && (find_pcb->remote_ip.addr == remote_ip))
                return find_pcb;
        }

        for (find_pcb = tcp_tw_pcbs; find_pcb != NULL; find_pcb = find_pcb->next){
            if ((find_pcb->remote_port == remote_port) && (find_pcb->remote_ip.addr == remote_ip))
                return find_pcb;
        }
    }
    return NULL;
}

/******************************************************************************
 * FunctionName : espconn_tcp_reconnect
 * Description  : reconnect with host
 * Parameters   : arg -- Additional argument to pass to the callback function
 * Returns      : none
*******************************************************************************/
static void ICACHE_FLASH_ATTR
espconn_tcp_reconnect(void *arg)
{
    espconn_msg *precon_cb = arg;
    sint8 re_err = 0;
    espconn_buf *perr_buf = NULL;
    espconn_buf *perr_back = NULL;
    espconn_kill_oldest_pcb();
    if (precon_cb != NULL) {
        struct espconn *espconn = precon_cb->preverse;
        re_err = precon_cb->pcommon.err;
        if (precon_cb->pespconn != NULL){
            if (espconn != NULL){/*Process the server's message block*/
                if (precon_cb->pespconn->proto.tcp != NULL){
                    espconn_copy_partial(espconn, precon_cb->pespconn);
                    espconn_printf("server: %d.%d.%d.%d : %d reconnection\n", espconn->proto.tcp->remote_ip[0],
                            espconn->proto.tcp->remote_ip[1],espconn->proto.tcp->remote_ip[2],
                            espconn->proto.tcp->remote_ip[3],espconn->proto.tcp->remote_port);
                    os_free(precon_cb->pespconn->proto.tcp);
                    precon_cb->pespconn->proto.tcp = NULL;
                }
                os_free(precon_cb->pespconn);
                precon_cb->pespconn = NULL;
            } else {/*Process the client's message block*/
                espconn = precon_cb->pespconn;
                espconn_printf("client: %d.%d.%d.%d : %d reconnection\n", espconn->proto.tcp->local_ip[0],
                                        espconn->proto.tcp->local_ip[1],espconn->proto.tcp->local_ip[2],
                                        espconn->proto.tcp->local_ip[3],espconn->proto.tcp->local_port);
            }
        }

        /*to prevent memory leaks, ensure that each allocated is deleted*/
        perr_buf = precon_cb->pcommon.pbuf;
        while (perr_buf != NULL){
            perr_back = perr_buf;
            perr_buf = perr_back->pnext;
            espconn_pbuf_delete(&precon_cb->pcommon.pbuf,perr_back);
            os_free(perr_back);
            perr_back = NULL;
        }
        os_bzero(&pktinfo[1], sizeof(struct espconn_packet));
        os_memcpy(&pktinfo[1], (void*)&precon_cb->pcommon.packet_info, sizeof(struct espconn_packet));
        os_free(precon_cb);
        precon_cb = NULL;
        if (espconn && espconn->proto.tcp && espconn->proto.tcp->reconnect_callback != NULL) {
            espconn->proto.tcp->reconnect_callback(espconn, re_err);
        }
    } else {
        espconn_printf("espconn_tcp_reconnect err\n");
    }
}

/******************************************************************************
 * FunctionName : espconn_tcp_disconnect
 * Description  : disconnect with host
 * Parameters   : arg -- Additional argument to pass to the callback function
 * Returns      : none
*******************************************************************************/
static void ICACHE_FLASH_ATTR
espconn_tcp_disconnect_successful(void *arg)
{
    espconn_msg *pdiscon_cb = arg;
    sint8 dis_err = 0;
    espconn_buf *pdis_buf = NULL;
    espconn_buf *pdis_back = NULL;
    espconn_kill_oldest_pcb();
    if (pdiscon_cb != NULL) {
        struct espconn *espconn = pdiscon_cb->preverse;

        dis_err = pdiscon_cb->pcommon.err;
        if (pdiscon_cb->pespconn != NULL){
            struct tcp_pcb *pcb = NULL;
            if (espconn != NULL){/*Process the server's message block*/
                if (pdiscon_cb->pespconn->proto.tcp != NULL && espconn->proto.tcp){
                    espconn_copy_partial(espconn, pdiscon_cb->pespconn);
                    espconn_printf("server: %d.%d.%d.%d : %d disconnect\n", espconn->proto.tcp->remote_ip[0],
                            espconn->proto.tcp->remote_ip[1],espconn->proto.tcp->remote_ip[2],
                            espconn->proto.tcp->remote_ip[3],espconn->proto.tcp->remote_port);
                    os_free(pdiscon_cb->pespconn->proto.tcp);
                    pdiscon_cb->pespconn->proto.tcp = NULL;
                }
                os_free(pdiscon_cb->pespconn);
                pdiscon_cb->pespconn = NULL;
            } else {/*Process the client's message block*/
                espconn = pdiscon_cb->pespconn;
                espconn_printf("client: %d.%d.%d.%d : %d disconnect\n", espconn->proto.tcp->local_ip[0],
                        espconn->proto.tcp->local_ip[1],espconn->proto.tcp->local_ip[2],
                        espconn->proto.tcp->local_ip[3],espconn->proto.tcp->local_port);
            }
            /*process the current TCP block*/
            pcb = espconn_find_current_pcb(pdiscon_cb);
            if (pcb != NULL){
                if (espconn_reuse_disabled(pdiscon_cb)) {
                    struct tcp_pcb *cpcb = NULL;
                    struct tcp_pcb *prev = NULL;
                    u8_t pcb_remove;
                    espconn_printf("espconn_tcp_disconnect_successful %d, %d\n",    pcb->state, pcb->local_port);
                    cpcb = tcp_tw_pcbs;
                    while (cpcb != NULL) {
                        pcb_remove = 0;
                        if (cpcb->local_port == pcb->local_port) {
                            ++pcb_remove;
                        }
                        /* If the PCB should be removed, do it. */
                        if (pcb_remove) {
                            struct tcp_pcb *backup_pcb = NULL;
                            tcp_pcb_purge(cpcb);
                            /* Remove PCB from tcp_tw_pcbs list. */
                            if (prev != NULL) {
                                LWIP_ASSERT("espconn_tcp_delete: middle cpcb != tcp_tw_pcbs",cpcb != tcp_tw_pcbs);
                                prev->next = cpcb->next;
                            } else {
                                /* This PCB was the first. */
                                LWIP_ASSERT("espconn_tcp_delete: first cpcb == tcp_tw_pcbs",tcp_tw_pcbs == cpcb);
                                tcp_tw_pcbs = cpcb->next;
                            }
                            backup_pcb = cpcb;
                            cpcb = cpcb->next;
                            memp_free(MEMP_TCP_PCB, backup_pcb);
                        } else {
                            prev = cpcb;
                            cpcb = cpcb->next;
                        }
                    }

                } else {
                    tcp_arg(pcb, NULL);
                    tcp_err(pcb, NULL);
                }
            }
        }

        /*to prevent memory leaks, ensure that each allocated is deleted*/
        pdis_buf = pdiscon_cb->pcommon.pbuf;
        while (pdis_buf != NULL) {
            pdis_back = pdis_buf;
            pdis_buf = pdis_back->pnext;
            espconn_pbuf_delete(&pdiscon_cb->pcommon.pbuf, pdis_back);
            os_free(pdis_back);
            pdis_back = NULL;
        }
        os_bzero(&pktinfo[0], sizeof(struct espconn_packet));
        os_memcpy(&pktinfo[0], (void*)&pdiscon_cb->pcommon.packet_info, sizeof(struct espconn_packet));
        os_free(pdiscon_cb);
        pdiscon_cb = NULL;
        if (espconn->proto.tcp && espconn->proto.tcp->disconnect_callback != NULL) {
            espconn->proto.tcp->disconnect_callback(espconn);
        }
    } else {
        espconn_printf("espconn_tcp_disconnect err\n");
    }
}

/******************************************************************************
 * FunctionName : espconn_Task
 * Description  : espconn processing task
 * Parameters   : events -- contain the espconn processing data
 * Returns      : none
*******************************************************************************/
static void ICACHE_FLASH_ATTR
espconn_Task(os_event_t *events)
{
    espconn_msg *task_msg = NULL;
    struct espconn *pespconn = NULL;

    task_msg = (espconn_msg *) events->par;
    switch (events->sig) {
        case SIG_ESPCONN_WRITE: {
            pespconn = task_msg->pespconn;
            if (pespconn == NULL) {
                return;
            }

            if (pespconn->proto.tcp->write_finish_fn != NULL) {
                pespconn->proto.tcp->write_finish_fn(pespconn);
            }
        }
            break;
        case SIG_ESPCONN_ERRER:
            /*remove the node from the client's active connection list*/
            espconn_list_delete(&plink_active, task_msg);
            espconn_tcp_reconnect(task_msg);
            break;
        case SIG_ESPCONN_CLOSE:
            /*remove the node from the client's active connection list*/
            espconn_list_delete(&plink_active, task_msg);
            espconn_tcp_disconnect_successful(task_msg);
            break;
        default:
            break;
    }
}

/******************************************************************************
 * FunctionName : espconn_tcp_sent
 * Description  : sent data for client or server
 * Parameters   : void *arg -- client or server to send
 *                uint8* psent -- Data to send
 *                uint16 length -- Length of data to send
 * Returns      : return espconn error code.
 * - ESPCONN_OK. Successful. No error occured.
 * - ESPCONN_MEM. Out of memory.
 * - ESPCONN_RTE. Could not find route to destination address.
 * - More errors could be returned by lower protocol layers.
*******************************************************************************/
err_t ICACHE_FLASH_ATTR
espconn_tcp_sent(void *arg, uint8 *psent, uint16 length)
{
    espconn_msg *ptcp_sent = arg;
    struct tcp_pcb *pcb = NULL;
    err_t err = 0;
    u16_t len = 0;
    u8_t data_to_send = false;

    espconn_printf("espconn_tcp_sent ptcp_sent %p psent %p length %d\n", ptcp_sent, psent, length);

    /*Check the parameters*/
    if (ptcp_sent == NULL || psent == NULL || length == 0) {
        return ESPCONN_ARG;
    }

    /*Set the packet length depend on the sender buffer space*/
    pcb = ptcp_sent->pcommon.pcb;
    if (tcp_sndbuf(pcb) < length) {
        len = tcp_sndbuf(pcb);
    } else {
        len = length;
        LWIP_ASSERT("length did not fit into uint16!", (len == length));
    }

    if (len > (2*pcb->mss)) {
        len = 2*pcb->mss;
    }

    /*Write data for sending, but does not send it immediately*/
    do {
        espconn_printf("espconn_tcp_sent writing %d bytes %p\n", len, pcb);
        if (espconn_copy_disabled(ptcp_sent))
            err = tcp_write(pcb, psent, len, 1);
        else
            err = tcp_write(pcb, psent, len, 0);

        if (err == ERR_MEM) {
            len /= 2;
        }
    } while (err == ERR_MEM && len > 1);

    /*Find out what we can send and send it, offset the buffer point for next send*/
    if (err == ERR_OK) {
        ptcp_sent->pcommon.ptail->punsent = psent + len;
        ptcp_sent->pcommon.ptail->unsent = length - len;
        err = tcp_output(pcb);
        /*If enable the copy option, change the flag for next write*/
        if (espconn_copy_disabled(ptcp_sent)){
            if (ptcp_sent->pcommon.ptail->unsent == 0) {
                ptcp_sent->pcommon.write_flag = true;
                ets_post(espconn_TaskPrio, SIG_ESPCONN_WRITE, (uint32_t)ptcp_sent);
            }
        }
        espconn_printf("espconn_tcp_sent %d\n", err);
    }
    return err;
}

/******************************************************************************
 * FunctionName : espconn_close
 * Description  : The connection has been successfully closed.
 * Parameters   : arg -- Additional argument to pass to the callback function
 * Returns      : none
*******************************************************************************/
void ICACHE_FLASH_ATTR espconn_tcp_disconnect(espconn_msg *pdiscon,u8 type)
{
    if (pdiscon != NULL){
        /*disconnect with the host by send the FIN frame*/
        if (pdiscon->preverse != NULL)
            espconn_server_close(pdiscon, pdiscon->pcommon.pcb,type);
        else
            espconn_client_close(pdiscon, pdiscon->pcommon.pcb,type);
    } else{
        espconn_printf("espconn_tcp_disconnect err.\n");
    }
}

///////////////////////////////client function/////////////////////////////////
/******************************************************************************
 * FunctionName : espconn_client_close
 * Description  : The connection shall be actively closed.
 * Parameters   : pcb -- Additional argument to pass to the callback function
 *                pcb -- the pcb to close
 * Returns      : none
*******************************************************************************/
static void ICACHE_FLASH_ATTR
espconn_client_close(void *arg, struct tcp_pcb *pcb, u8 type)
{
    err_t err;
    espconn_msg *pclose = arg;

    pclose->pcommon.pcb = pcb;
    /*avoid recalling the disconnect function*/
    tcp_recv(pcb, NULL);

    if(type == 0)
        err = tcp_close(pcb);
    else
        {tcp_abort(pcb); err = ERR_OK;}

    if (err != ERR_OK) {
        /* closing failed, try again later */
        tcp_recv(pcb, espconn_client_recv);
    } else {
        /* closing succeeded */
        tcp_sent(pcb, NULL);
        tcp_err(pcb, NULL);
        /*switch the state of espconn for application process*/
        pclose->pespconn->state = ESPCONN_CLOSE;
        ets_post(espconn_TaskPrio, SIG_ESPCONN_CLOSE, (uint32_t)pclose);
    }
}

//***********Code for WIFI_BLOCK from upper**************
sint8 ICACHE_FLASH_ATTR
espconn_recv_hold(struct espconn *pespconn)
{
    //1st, according to espconn code, have to find out the escpconn_msg by pespconn;
    espconn_msg *pnode = NULL;
    bool value = false;
    if (pespconn == NULL) {
        return ESPCONN_ARG;
    }
    value = espconn_find_connection(pespconn, &pnode);
    if(value != true)
    {
        os_printf("RecvHold, By pespconn,find conn_msg fail\n");
        return ESPCONN_ARG;
    }

    //2nd, the actual operation
    if(pnode->recv_hold_flag == 0)
    {
        pnode->recv_hold_flag = 1;
        pnode->recv_holded_buf_Len = 0;
    }
    return ESPCONN_OK;
}

sint8 ICACHE_FLASH_ATTR
espconn_recv_unhold(struct espconn *pespconn)
{
    //1st, according to espconn code, have to find out the escpconn_msg by pespconn;
    espconn_msg *pnode = NULL;
    bool value = false;
    if (pespconn == NULL) {
        return ESPCONN_ARG;
    }
    value = espconn_find_connection(pespconn, &pnode);
    if(value != true)
    {
        os_printf("RecvHold, By pespconn,find conn_msg fail\n");
        return ESPCONN_ARG;
    }

    //2nd, the actual operation
    if(pnode->recv_hold_flag == 1)
    {
        if(pespconn->type == ESPCONN_TCP) {
            tcp_recved(pnode->pcommon.pcb, pnode->recv_holded_buf_Len);
        }
        pnode->recv_holded_buf_Len = 0;
        pnode->recv_hold_flag = 0;
    }
    return ESPCONN_OK;
}

//***********Code for WIFI_BLOCK from upper**************

/******************************************************************************
 * FunctionName : espconn_client_recv
 * Description  : Data has been received on this pcb.
 * Parameters   : arg -- Additional argument to pass to the callback function
 *                pcb -- The connection pcb which received data
 *                p -- The received data (or NULL when the connection has been closed!)
 *                err -- An error code if there has been an error receiving
 * Returns      : ERR_ABRT: if you have called tcp_abort from within the function!
*******************************************************************************/
static err_t ICACHE_FLASH_ATTR
espconn_client_recv(void *arg, struct tcp_pcb *pcb, struct pbuf *p, err_t err)
{
    espconn_msg *precv_cb = arg;

    tcp_arg(pcb, arg);

    if (p != NULL) {
        /*To update and advertise a larger window*/
        if(precv_cb->recv_hold_flag == 0)
            tcp_recved(pcb, p->tot_len);
        else
            precv_cb->recv_holded_buf_Len += p->tot_len;
    }

    if (err == ERR_OK && p != NULL) {
        char *pdata = NULL;
        u16_t length = 0;
        /*Copy the contents of a packet buffer to an application buffer.
         *to prevent memory leaks, ensure that each allocated is deleted*/
        pdata = (char *)os_zalloc(p ->tot_len + 1);
        length = pbuf_copy_partial(p, pdata, p ->tot_len, 0);
        pbuf_free(p);

        if (length != 0) {
            /*switch the state of espconn for application process*/
            precv_cb->pespconn ->state = ESPCONN_READ;
            precv_cb->pcommon.pcb = pcb;
            if (precv_cb->pespconn->recv_callback != NULL) {
                precv_cb->pespconn->recv_callback(precv_cb->pespconn, pdata, length);
            }
            /*switch the state of espconn for next packet copy*/
            if (pcb->state == ESTABLISHED)
                precv_cb->pespconn ->state = ESPCONN_CONNECT;
        }

        /*to prevent memory leaks, ensure that each allocated is deleted*/
        os_free(pdata);
        pdata = NULL;
    }

    if (err == ERR_OK && p == NULL) {
        espconn_client_close(precv_cb, pcb,0);
    }

    return ERR_OK;
}

/******************************************************************************
 * FunctionName : espconn_tcp_write
 * Description  : write the packet which in the active connection's list.
 * Parameters   : arg -- the node pointer which reverse the packet
 * Returns      : ESPCONN_MEM: memory error
 *                ESPCONN_OK:have enough space for write packet
*******************************************************************************/
err_t ICACHE_FLASH_ATTR espconn_tcp_write(void *arg)
{
    espconn_msg *pwrite = arg;
    err_t err = ERR_OK;
    struct tcp_pcb *pcb = pwrite->pcommon.pcb;
    /*for one active connection,limit the sender buffer space*/
    if (tcp_nagle_disabled(pcb) && (pcb->snd_queuelen >= TCP_SND_QUEUELEN))
        return ESPCONN_MEM;

    while (tcp_sndbuf(pcb) != 0){
        if (pwrite->pcommon.ptail != NULL) {
            /*Find the node whether in the list's tail or not*/
            if (pwrite->pcommon.ptail->unsent == 0) {
                pwrite->pcommon.ptail = pwrite->pcommon.ptail->pnext;
                continue;
            }

            /*Send the packet for the active connection*/
            err = espconn_tcp_sent(pwrite, pwrite->pcommon.ptail->punsent,pwrite->pcommon.ptail->unsent);
            if (err != ERR_OK)
                break;
        } else
            break;
    }
    return err;
}

/******************************************************************************
 * FunctionName : espconn_tcp_reconnect
 * Description  : reconnect with host
 * Parameters   : arg -- Additional argument to pass to the callback function
 * Returns      : none
*******************************************************************************/
static void ICACHE_FLASH_ATTR espconn_tcp_finish(void *arg)
{
    espconn_msg *pfinish = arg;
    espconn_buf *premove = NULL;
    uint16 len = 0;
    espconn_tcp_write(pfinish);
    while (pfinish->pcommon.pbuf != NULL){
        premove = pfinish->pcommon.pbuf;
        pfinish->pcommon.pbuf->tot_len += len;
        /*application packet has been sent and acknowledged by the remote host,
         * to prevent memory leaks, ensure that each allocated is deleted*/
        if (premove->tot_len >= premove->len){
            espconn_pbuf_delete(&pfinish->pcommon.pbuf,premove);
            len = premove->tot_len - premove->len;
            pfinish->pcommon.packet_info.sent_length = premove->len;
            os_free(premove);
            premove = NULL;
            pfinish->pespconn->state = ESPCONN_CONNECT;
            if (pfinish->pespconn->sent_callback != NULL) {
                pfinish->pespconn->sent_callback(pfinish->pespconn);
            }
            pfinish->pcommon.packet_info.sent_length = len;
        } else
            break;
    }
}

/******************************************************************************
 * FunctionName : espconn_client_sent
 * Description  : Data has been sent and acknowledged by the remote host.
 *                This means that more data can be sent.
 * Parameters   : arg -- Additional argument to pass to the callback function
 *                pcb -- The connection pcb for which data has been acknowledged
 *                len -- The amount of bytes acknowledged
 * Returns      : ERR_OK: try to send some data by calling tcp_output
 *                ERR_ABRT: if you have called tcp_abort from within the function!
*******************************************************************************/
static err_t ICACHE_FLASH_ATTR
espconn_client_sent(void *arg, struct tcp_pcb *pcb, u16_t len)
{
    espconn_msg *psent_cb = arg;

    psent_cb->pcommon.pcb = pcb;
    psent_cb->pcommon.pbuf->tot_len += len;
    psent_cb->pcommon.packet_info.sent_length = len;

    /*Send more data for one active connection*/
    espconn_tcp_finish(psent_cb);

    return ERR_OK;
}

/******************************************************************************
 * FunctionName : espconn_client_err
 * Description  : The pcb had an error and is already deallocated.
 *                The argument might still be valid (if != NULL).
 * Parameters   : arg -- Additional argument to pass to the callback function
 *                err -- Error code to indicate why the pcb has been closed
 * Returns      : none
*******************************************************************************/
static void ICACHE_FLASH_ATTR
espconn_client_err(void *arg, err_t err)
{
    espconn_msg *perr_cb = arg;
    struct tcp_pcb *pcb = NULL;
    LWIP_UNUSED_ARG(err);

    if (perr_cb != NULL) {
        pcb = perr_cb->pcommon.pcb;
        perr_cb->pespconn->state = ESPCONN_CLOSE;
        espconn_printf("espconn_client_err %d %d %d\n", pcb->state, pcb->nrtx, err);

//        /*remove the node from the client's active connection list*/
//        espconn_list_delete(&plink_active, perr_cb);

        /*Set the error code depend on the error type and control block state*/
        if (err == ERR_ABRT) {
            switch (pcb->state) {
                    case SYN_SENT:
                        if (pcb->nrtx == TCP_SYNMAXRTX) {
                            perr_cb->pcommon.err = ESPCONN_CONN;
                        } else {
                            perr_cb->pcommon.err = err;
                        }

                        break;

                    case ESTABLISHED:
                        if (pcb->nrtx == TCP_MAXRTX) {
                            perr_cb->pcommon.err = ESPCONN_TIMEOUT;
                        } else {
                            perr_cb->pcommon.err = err;
                        }
                        break;

                    case FIN_WAIT_1:
                        if (pcb->nrtx == TCP_MAXRTX) {
                            perr_cb->pcommon.err = ESPCONN_CLSD;
                        } else {
                            perr_cb->pcommon.err = err;
                        }
                        break;
                    case FIN_WAIT_2:
                        perr_cb->pcommon.err = ESPCONN_CLSD;
                        break;
                    case CLOSED:
                        perr_cb->pcommon.err = ESPCONN_CONN;
                        break;
                }
            } else {
                perr_cb->pcommon.err = err;
            }
            /*post the singer to the task for processing the connection*/
            ets_post(espconn_TaskPrio, SIG_ESPCONN_ERRER, (uint32_t)perr_cb);
        }
}

/******************************************************************************
 * FunctionName : espconn_client_connect
 * Description  : A new incoming connection has been connected.
 * Parameters   : arg -- Additional argument to pass to the callback function
 *                tpcb -- The connection pcb which is connected
 *                err -- An unused error code, always ERR_OK currently
 * Returns      : connection result
*******************************************************************************/
static err_t ICACHE_FLASH_ATTR
espconn_client_connect(void *arg, struct tcp_pcb *tpcb, err_t err)
{
    espconn_msg *pcon = arg;

    espconn_printf("espconn_client_connect pcon %p tpcb %p\n", pcon, tpcb);
    if (err == ERR_OK){
        /*Reserve the remote information for current active connection*/
        pcon->pespconn->state = ESPCONN_CONNECT;
        pcon->pcommon.err = err;
        pcon->pcommon.pcb = tpcb;
        pcon->pcommon.local_port = tpcb->local_port;
        pcon->pcommon.local_ip = tpcb->local_ip.addr;
        pcon->pcommon.remote_port = tpcb->remote_port;
        pcon->pcommon.remote_ip[0] = ip4_addr1_16(&tpcb->remote_ip);
        pcon->pcommon.remote_ip[1] = ip4_addr2_16(&tpcb->remote_ip);
        pcon->pcommon.remote_ip[2] = ip4_addr3_16(&tpcb->remote_ip);
        pcon->pcommon.remote_ip[3] = ip4_addr4_16(&tpcb->remote_ip);
        pcon->pcommon.write_flag = true;
        tcp_arg(tpcb, (void *) pcon);

        /*Set the specify function that should be called
         * when TCP data has been successfully delivered,
         * when active connection receives data*/
        tcp_sent(tpcb, espconn_client_sent);
        tcp_recv(tpcb, espconn_client_recv);
        /*Disable Nagle algorithm default*/
        tcp_nagle_disable(tpcb);
        /*Default set the total number of espconn_buf on the unsent lists for one*/
        espconn_tcp_set_buf_count(pcon->pespconn, 1);

        if (pcon->pespconn->proto.tcp->connect_callback != NULL) {
            pcon->pespconn->proto.tcp->connect_callback(pcon->pespconn);
        }

        /*Enable keep alive option*/
        if (espconn_keepalive_disabled(pcon))
            espconn_keepalive_enable(tpcb);

    } else{
        os_printf("err in host connected (%s)\n",lwip_strerr(err));
    }
    return err;
}

/******************************************************************************
 * FunctionName : espconn_tcp_client
 * Description  : Initialize the client: set up a connect PCB and bind it to
 *                the defined port
 * Parameters   : espconn -- the espconn used to build client
 * Returns      : none
*******************************************************************************/
sint8 ICACHE_FLASH_ATTR
espconn_tcp_client(struct espconn *espconn)
{
    struct tcp_pcb *pcb = NULL;
    struct ip_addr ipaddr;
    espconn_msg *pclient = NULL;

    /*Creates a new client control message*/
    pclient = (espconn_msg *)os_zalloc(sizeof(espconn_msg));
    if (pclient == NULL){
        return ESPCONN_MEM;
    }

    /*Set an IP address given for Little-endian.*/
    IP4_ADDR(&ipaddr, espconn->proto.tcp->remote_ip[0],
            espconn->proto.tcp->remote_ip[1],
            espconn->proto.tcp->remote_ip[2],
            espconn->proto.tcp->remote_ip[3]);

    /*Creates a new TCP protocol control block*/
    pcb = tcp_new();

    if (pcb == NULL) {
        /*to prevent memory leaks, ensure that each allocated is deleted*/
        os_free(pclient);
        pclient = NULL;
        return ESPCONN_MEM;
    } else {

        /*insert the node to the active connection list*/
        espconn_list_creat(&plink_active, pclient);
        tcp_arg(pcb, (void *)pclient);
        tcp_err(pcb, espconn_client_err);
        pclient->preverse = NULL;
        pclient->pespconn = espconn;
        pclient->pespconn->state = ESPCONN_WAIT;
        pclient->pcommon.pcb = pcb;
        tcp_bind(pcb, IP_ADDR_ANY, pclient->pespconn->proto.tcp->local_port);
#if 0
        pclient->pcommon.err = tcp_bind(pcb, IP_ADDR_ANY, pclient->pespconn->proto.tcp->local_port);
        if (pclient->pcommon.err != ERR_OK){
            /*remove the node from the client's active connection list*/
            espconn_list_delete(&plink_active, pclient);
            memp_free(MEMP_TCP_PCB, pcb);
            os_free(pclient);
            pclient = NULL;
            return ERR_USE;
        }
#endif
        /*Establish the connection*/
        pclient->pcommon.err = tcp_connect(pcb, &ipaddr,
                pclient->pespconn->proto.tcp->remote_port, espconn_client_connect);
        if (pclient->pcommon.err == ERR_RTE){
            /*remove the node from the client's active connection list*/
            espconn_list_delete(&plink_active, pclient);
            espconn_kill_pcb(pcb->local_port);
            os_free(pclient);
            pclient = NULL;
            return ESPCONN_RTE;
        }
        return pclient->pcommon.err;
    }
}

///////////////////////////////server function/////////////////////////////////
/******************************************************************************
 * FunctionName : espconn_server_close
 * Description  : The connection shall be actively closed.
 * Parameters   : arg -- Additional argument to pass to the callback function
 *                pcb -- the pcb to close
 * Returns      : none
*******************************************************************************/
static void ICACHE_FLASH_ATTR
espconn_server_close(void *arg, struct tcp_pcb *pcb,u8 type)
{
    err_t err;
    espconn_msg *psclose = arg;

    psclose->pcommon.pcb = pcb;
    /*avoid recalling the disconnect function*/
    tcp_recv(pcb, NULL);

    if(type ==0)
        err = tcp_close(pcb);
    else
        {tcp_abort(pcb); err = ERR_OK;}

    if (err != ERR_OK) {
        /* closing failed, try again later */
        tcp_recv(pcb, espconn_server_recv);
    } else {
        /* closing succeeded */
        tcp_poll(pcb, NULL, 0);
        tcp_sent(pcb, NULL);
        tcp_err(pcb, NULL);
        /*switch the state of espconn for application process*/
        psclose->pespconn->state = ESPCONN_CLOSE;
        ets_post(espconn_TaskPrio, SIG_ESPCONN_CLOSE, (uint32_t)psclose);
    }
}

/******************************************************************************
 * FunctionName : espconn_server_recv
 * Description  : Data has been received on this pcb.
 * Parameters   : arg -- Additional argument to pass to the callback function
 *                pcb -- The connection pcb which received data
 *                p -- The received data (or NULL when the connection has been closed!)
 *                err -- An error code if there has been an error receiving
 * Returns      : ERR_ABRT: if you have called tcp_abort from within the function!
*******************************************************************************/
static err_t ICACHE_FLASH_ATTR
espconn_server_recv(void *arg, struct tcp_pcb *pcb, struct pbuf *p, err_t err)
{
    espconn_msg *precv_cb = arg;

    tcp_arg(pcb, arg);
    espconn_printf("server has application data received: %d\n", system_get_free_heap_size());
    if (p != NULL) {
        /*To update and advertise a larger window*/
        if(precv_cb->recv_hold_flag == 0)
            tcp_recved(pcb, p->tot_len);
        else
            precv_cb->recv_holded_buf_Len += p->tot_len;
    }

    if (err == ERR_OK && p != NULL) {
        u8_t *data_ptr = NULL;
        u32_t data_cntr = 0;
        /*clear the count for connection timeout*/
        precv_cb->pcommon.recv_check = 0;
        /*Copy the contents of a packet buffer to an application buffer.
         *to prevent memory leaks, ensure that each allocated is deleted*/
        data_ptr = (u8_t *)os_zalloc(p ->tot_len + 1);
        data_cntr = pbuf_copy_partial(p, data_ptr, p ->tot_len, 0);
        pbuf_free(p);

        if (data_cntr != 0) {
            /*switch the state of espconn for application process*/
            precv_cb->pespconn ->state = ESPCONN_READ;
            precv_cb->pcommon.pcb = pcb;
            if (precv_cb->pespconn->recv_callback != NULL) {
                precv_cb->pespconn->recv_callback(precv_cb->pespconn, data_ptr, data_cntr);
            }

            /*switch the state of espconn for next packet copy*/
            if (pcb->state == ESTABLISHED)
                precv_cb->pespconn ->state = ESPCONN_CONNECT;
        }

        /*to prevent memory leaks, ensure that each allocated is deleted*/
        os_free(data_ptr);
        data_ptr = NULL;
        espconn_printf("server's application data has been processed: %d\n", system_get_free_heap_size());
    } else {
        if (p != NULL) {
            pbuf_free(p);
        }

        espconn_server_close(precv_cb, pcb,0);
    }

    return ERR_OK;
}

/******************************************************************************
 * FunctionName : espconn_server_sent
 * Description  : Data has been sent and acknowledged by the remote host.
 * This means that more data can be sent.
 * Parameters   : arg -- Additional argument to pass to the callback function
 *                pcb -- The connection pcb for which data has been acknowledged
 *                len -- The amount of bytes acknowledged
 * Returns      : ERR_OK: try to send some data by calling tcp_output
 *                ERR_ABRT: if you have called tcp_abort from within the function!
*******************************************************************************/
static err_t ICACHE_FLASH_ATTR
espconn_server_sent(void *arg, struct tcp_pcb *pcb, u16_t len)
{
    espconn_msg *psent_cb = arg;

    psent_cb->pcommon.pcb = pcb;
    psent_cb->pcommon.recv_check = 0;
    psent_cb->pcommon.pbuf->tot_len += len;
    psent_cb->pcommon.packet_info.sent_length = len;

    /*Send more data for one active connection*/
    espconn_tcp_finish(psent_cb);
    return ERR_OK;
}

/******************************************************************************
 * FunctionName : espconn_server_poll
 * Description  : The poll function is called every 3nd second.
 * If there has been no data sent (which resets the retries) in 3 seconds, close.
 * If the last portion of a file has not been sent in 3 seconds, close.
 *
 * This could be increased, but we don't want to waste resources for bad connections.
 * Parameters   : arg -- Additional argument to pass to the callback function
 *                pcb -- The connection pcb for which data has been acknowledged
 * Returns      : ERR_OK: try to send some data by calling tcp_output
 *                ERR_ABRT: if you have called tcp_abort from within the function!
*******************************************************************************/
static err_t ICACHE_FLASH_ATTR
espconn_server_poll(void *arg, struct tcp_pcb *pcb)
{
    espconn_msg *pspoll_cb = arg;

    /*exception calling abandon the connection for send a RST frame*/
    if (arg == NULL) {
        tcp_abandon(pcb, 0);
        tcp_poll(pcb, NULL, 0);
        return ERR_OK;
    }

    espconn_printf("espconn_server_poll %d %d\n", pspoll_cb->pcommon.recv_check, pcb->state);
    pspoll_cb->pcommon.pcb = pcb;
    if (pcb->state == ESTABLISHED) {
        pspoll_cb->pcommon.recv_check++;
        if (pspoll_cb->pcommon.timeout != 0){/*no data sent in one active connection's set timeout, close.*/
            if (pspoll_cb->pcommon.recv_check >= pspoll_cb->pcommon.timeout) {
                pspoll_cb->pcommon.recv_check = 0;
                espconn_server_close(pspoll_cb, pcb,0);
            }
        } else {
            espconn_msg *ptime_msg = pserver_list;
            while (ptime_msg != NULL) {
                if (ptime_msg->pespconn == pspoll_cb->preverse){
                    if (ptime_msg->pcommon.timeout != 0){/*no data sent in server's set timeout, close.*/
                        if (pspoll_cb->pcommon.recv_check >= ptime_msg->pcommon.timeout){
                            pspoll_cb->pcommon.recv_check = 0;
                            espconn_server_close(pspoll_cb, pcb,0);
                        }
                    } else {/*don't close for ever*/
                        pspoll_cb->pcommon.recv_check = 0;
                    }
                    break;
                }
                ptime_msg = ptime_msg->pnext;
            }
        }
    } else {
        espconn_server_close(pspoll_cb, pcb,0);
    }

    return ERR_OK;
}

/******************************************************************************
 * FunctionName : esponn_server_err
 * Description  : The pcb had an error and is already deallocated.
 *                The argument might still be valid (if != NULL).
 * Parameters   : arg -- Additional argument to pass to the callback function
 *                err -- Error code to indicate why the pcb has been closed
 * Returns      : none
*******************************************************************************/
static void ICACHE_FLASH_ATTR
esponn_server_err(void *arg, err_t err)
{
    espconn_msg *pserr_cb = arg;
    struct tcp_pcb *pcb = NULL;
    if (pserr_cb != NULL) {

        pcb = pserr_cb->pcommon.pcb;
        pserr_cb->pespconn->state = ESPCONN_CLOSE;

//      /*remove the node from the server's active connection list*/
//      espconn_list_delete(&plink_active, pserr_cb);

        /*Set the error code depend on the error type and control block state*/
        if (err == ERR_ABRT) {
            switch (pcb->state) {
                case SYN_RCVD:
                    if (pcb->nrtx == TCP_SYNMAXRTX) {
                        pserr_cb->pcommon.err = ESPCONN_CONN;
                    } else {
                        pserr_cb->pcommon.err = err;
                    }

                    break;

                case ESTABLISHED:
                    if (pcb->nrtx == TCP_MAXRTX) {
                        pserr_cb->pcommon.err = ESPCONN_TIMEOUT;
                    } else {
                        pserr_cb->pcommon.err = err;
                    }

                    break;

                case CLOSE_WAIT:
                    if (pcb->nrtx == TCP_MAXRTX) {
                        pserr_cb->pcommon.err = ESPCONN_CLSD;
                    } else {
                        pserr_cb->pcommon.err = err;
                    }
                    break;
                case LAST_ACK:
                    pserr_cb->pcommon.err = ESPCONN_CLSD;
                    break;

                case CLOSED:
                    pserr_cb->pcommon.err = ESPCONN_CONN;
                    break;
                default :
                    break;
            }
        } else {
            pserr_cb->pcommon.err = err;
        }
        /*post the singer to the task for processing the connection*/
        ets_post(espconn_TaskPrio, SIG_ESPCONN_ERRER, (uint32_t)pserr_cb);
    }
}

/******************************************************************************
 * FunctionName : espconn_tcp_accept
 * Description  : A new incoming connection has been accepted.
 * Parameters   : arg -- Additional argument to pass to the callback function
 *                pcb -- The connection pcb which is accepted
 *                err -- An unused error code, always ERR_OK currently
 * Returns      : acception result
*******************************************************************************/
static err_t ICACHE_FLASH_ATTR
espconn_tcp_accept(void *arg, struct tcp_pcb *pcb, err_t err)
{
    struct espconn *espconn = arg;
    espconn_msg *paccept = NULL;
    remot_info *pinfo = NULL;
    LWIP_UNUSED_ARG(err);

    if (!espconn || !espconn->proto.tcp) {
        return ERR_ARG;
    }

    tcp_arg(pcb, paccept);
    tcp_err(pcb, esponn_server_err);
    /*Ensure the active connection is less than the count of active connections on the server*/
    espconn_get_connection_info(espconn, &pinfo , 0);
    espconn_printf("espconn_tcp_accept link_cnt: %d\n", espconn->link_cnt);
    if (espconn->link_cnt == espconn_tcp_get_max_con_allow(espconn))
        return ERR_ISCONN;

    /*Creates a new active connect control message*/
    paccept = (espconn_msg *)os_zalloc(sizeof(espconn_msg));
    tcp_arg(pcb, paccept);

    if (paccept == NULL)
        return ERR_MEM;
    /*Insert the node to the active connection list*/
    espconn_list_creat(&plink_active, paccept);

    paccept->preverse = espconn;
    paccept->pespconn = (struct espconn *)os_zalloc(sizeof(struct espconn));
    if (paccept->pespconn == NULL)
        return ERR_MEM;
    paccept->pespconn->proto.tcp = (esp_tcp *)os_zalloc(sizeof(esp_tcp));
    if (paccept->pespconn->proto.tcp == NULL)
        return ERR_MEM;

    /*Reserve the remote information for current active connection*/
    paccept->pcommon.pcb = pcb;

    paccept->pcommon.remote_port = pcb->remote_port;
    paccept->pcommon.remote_ip[0] = ip4_addr1_16(&pcb->remote_ip);
    paccept->pcommon.remote_ip[1] = ip4_addr2_16(&pcb->remote_ip);
    paccept->pcommon.remote_ip[2] = ip4_addr3_16(&pcb->remote_ip);
    paccept->pcommon.remote_ip[3] = ip4_addr4_16(&pcb->remote_ip);
    paccept->pcommon.write_flag = true;

    os_memcpy(espconn->proto.tcp->remote_ip, paccept->pcommon.remote_ip, 4);
    espconn->proto.tcp->remote_port = pcb->remote_port;
    espconn->state = ESPCONN_CONNECT;
    espconn_copy_partial(paccept->pespconn, espconn);

    /*Set the specify function that should be called
     * when TCP data has been successfully delivered,
     * when active connection receives data,
     * or periodically from active connection*/
    tcp_sent(pcb, espconn_server_sent);
    tcp_recv(pcb, espconn_server_recv);
    tcp_poll(pcb, espconn_server_poll, 8); /* every 1 seconds */
    /*Disable Nagle algorithm default*/
    tcp_nagle_disable(pcb);
    /*Default set the total number of espconn_buf on the unsent lists for one*/
    espconn_tcp_set_buf_count(paccept->pespconn, 1);

    if (paccept->pespconn->proto.tcp->connect_callback != NULL) {
        paccept->pespconn->proto.tcp->connect_callback(paccept->pespconn);
    }

    /*Enable keep alive option*/
    if (espconn_keepalive_disabled(paccept))
        espconn_keepalive_enable(pcb);

    return ERR_OK;
}

/******************************************************************************
 * FunctionName : espconn_tcp_server
 * Description  : Initialize the server: set up a listening PCB and bind it to
 *                the defined port
 * Parameters   : espconn -- the espconn used to build server
 * Returns      : none
*******************************************************************************/
sint8 ICACHE_FLASH_ATTR
espconn_tcp_server(struct espconn *espconn)
{
    struct tcp_pcb *pcb = NULL;
    espconn_msg *pserver = NULL;

    /*Creates a new server control message*/
    pserver = (espconn_msg *)os_zalloc(sizeof(espconn_msg));
    if (pserver == NULL){
        return ESPCONN_MEM;
    }

    /*Creates a new TCP protocol control block*/
    pcb = tcp_new();
    if (pcb == NULL) {
        /*to prevent memory leaks, ensure that each allocated is deleted*/
        os_free(pserver);
        pserver = NULL;
        return ESPCONN_MEM;
    } else {
        struct tcp_pcb *lpcb = NULL;
        /*Binds the connection to a local port number and any IP address*/
        tcp_bind(pcb, IP_ADDR_ANY, espconn->proto.tcp->local_port);
        lpcb = pcb;
        /*malloc and set the state of the connection to be LISTEN*/
        pcb = tcp_listen(pcb);
        if (pcb != NULL) {
            /*insert the node to the active connection list*/
            espconn_list_creat(&pserver_list, pserver);
            pserver->preverse = pcb;
            pserver->pespconn = espconn;
            pserver->count_opt = MEMP_NUM_TCP_PCB;
            pserver->pcommon.timeout = 0x0a;
            espconn ->state = ESPCONN_LISTEN;
            /*set the specify argument that should be passed callback function*/
            tcp_arg(pcb, (void *)espconn);
            /*accept callback function to call for this control block*/
            tcp_accept(pcb, espconn_tcp_accept);
            return ESPCONN_OK;
        } else {
            /*to prevent memory leaks, ensure that each allocated is deleted*/
            memp_free(MEMP_TCP_PCB,lpcb);
            os_free(pserver);
            pserver = NULL;
            return ESPCONN_MEM;
        }
    }
}

/******************************************************************************
 * FunctionName : espconn_tcp_delete
 * Description  : delete the server: delete a listening PCB and free it
 * Parameters   : pdeletecon -- the espconn used to delete a server
 * Returns      : none
*******************************************************************************/
sint8 ICACHE_FLASH_ATTR espconn_tcp_delete(struct espconn *pdeletecon)
{
    err_t err;
    remot_info *pinfo = NULL;
    espconn_msg *pdelete_msg = NULL;
    struct tcp_pcb *pcb = NULL;

    if (pdeletecon == NULL)
        return ESPCONN_ARG;

    espconn_get_connection_info(pdeletecon, &pinfo , 0);
    /*make sure all the active connection have been disconnect*/
    if (pdeletecon->link_cnt != 0)
        return ESPCONN_INPROGRESS;
    else {
        espconn_printf("espconn_tcp_delete %p\n",pdeletecon);
        pdelete_msg = pserver_list;
        while (pdelete_msg != NULL){
            if (pdelete_msg->pespconn == pdeletecon){
                /*remove the node from the client's active connection list*/
                espconn_list_delete(&pserver_list, pdelete_msg);
                pcb = pdelete_msg->preverse;
                os_printf("espconn_tcp_delete %d, %d\n",pcb->state, pcb->local_port);
                espconn_kill_pcb(pcb->local_port);
                err = tcp_close(pcb);
                os_free(pdelete_msg);
                pdelete_msg = NULL;
                break;
            }
            pdelete_msg = pdelete_msg->pnext;
        }
        if (err == ERR_OK)
            return err;
        else
            return ESPCONN_ARG;
    }
}

/******************************************************************************
 * FunctionName : espconn_init
 * Description  : used to init the function that should be used when
 * Parameters   : none
 * Returns      : none
*******************************************************************************/
void ICACHE_FLASH_ATTR espconn_init(void)
{
  ets_task(espconn_Task, espconn_TaskPrio, espconn_TaskQueue, espconn_TaskQueueLen);
}