AsyncTCP/src/AsyncTCP.cpp

/*
  Asynchronous TCP library for Espressif MCUs

  Copyright (c) 2016 Hristo Gochkov. All rights reserved.
  This file is part of the esp8266 core for Arduino environment.

  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 2.1 of the License, or (at your option) any later version.

  This library is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public
  License along with this library; if not, write to the Free Software
  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */

#include "Arduino.h"

#include "AsyncTCP.h"

extern "C" {
#include "lwip/dns.h"
#include "lwip/err.h"
#include "lwip/inet.h"
#include "lwip/opt.h"
#include "lwip/tcp.h"
}

#if CONFIG_ASYNC_TCP_USE_WDT
  #include "esp_task_wdt.h"
#endif

// Required for:
// https://github.com/espressif/arduino-esp32/blob/3.0.3/libraries/Network/src/NetworkInterface.cpp#L37-L47
#if ESP_IDF_VERSION_MAJOR >= 5
  #include <NetworkInterface.h>
#endif

#define TAG "AsyncTCP"

// https://github.com/espressif/arduino-esp32/issues/10526
#ifdef CONFIG_LWIP_TCPIP_CORE_LOCKING
  #define TCP_MUTEX_LOCK()                                \
    if (!sys_thread_tcpip(LWIP_CORE_LOCK_QUERY_HOLDER)) { \
      LOCK_TCPIP_CORE();                                  \
    }

  #define TCP_MUTEX_UNLOCK()                             \
    if (sys_thread_tcpip(LWIP_CORE_LOCK_QUERY_HOLDER)) { \
      UNLOCK_TCPIP_CORE();                               \
    }
#else // CONFIG_LWIP_TCPIP_CORE_LOCKING
  #define TCP_MUTEX_LOCK()
  #define TCP_MUTEX_UNLOCK()
#endif // CONFIG_LWIP_TCPIP_CORE_LOCKING

#define INVALID_CLOSED_SLOT -1

/*
  TCP poll interval is specified in terms of the TCP coarse timer interval, which is called twice a second
  https://github.com/espressif/esp-lwip/blob/2acf959a2bb559313cd2bf9306c24612ba3d0e19/src/core/tcp.c#L1895
*/
#define CONFIG_ASYNC_TCP_POLL_TIMER 1

/*
 * TCP/IP Event Task
 * */

typedef enum {
  LWIP_TCP_SENT,
  LWIP_TCP_RECV,
  LWIP_TCP_FIN,
  LWIP_TCP_ERROR,
  LWIP_TCP_POLL,
  LWIP_TCP_CLEAR,
  LWIP_TCP_ACCEPT,
  LWIP_TCP_CONNECTED,
  LWIP_TCP_DNS
} lwip_event_t;

typedef struct {
    lwip_event_t event;
    void* arg;
    union {
        struct {
            tcp_pcb* pcb;
            int8_t err;
        } connected;
        struct {
            int8_t err;
        } error;
        struct {
            tcp_pcb* pcb;
            uint16_t len;
        } sent;
        struct {
            tcp_pcb* pcb;
            pbuf* pb;
            int8_t err;
        } recv;
        struct {
            tcp_pcb* pcb;
            int8_t err;
        } fin;
        struct {
            tcp_pcb* pcb;
        } poll;
        struct {
            AsyncClient* client;
        } accept;
        struct {
            const char* name;
            ip_addr_t addr;
        } dns;
    };
} lwip_event_packet_t;

static QueueHandle_t _async_queue;
static TaskHandle_t _async_service_task_handle = NULL;

SemaphoreHandle_t _slots_lock;
const int _number_of_closed_slots = CONFIG_LWIP_MAX_ACTIVE_TCP;
static uint32_t _closed_slots[_number_of_closed_slots];
static uint32_t _closed_index = []() {
  _slots_lock = xSemaphoreCreateBinary();
  xSemaphoreGive(_slots_lock);
  for (int i = 0; i < _number_of_closed_slots; ++i) {
    _closed_slots[i] = 1;
  }
  return 1;
}();

static inline bool _init_async_event_queue() {
  if (!_async_queue) {
    _async_queue = xQueueCreate(CONFIG_ASYNC_TCP_QUEUE_SIZE, sizeof(lwip_event_packet_t*));
    if (!_async_queue) {
      return false;
    }
  }
  return true;
}

static inline bool _send_async_event(lwip_event_packet_t** e, TickType_t wait = portMAX_DELAY) {
  return _async_queue && xQueueSend(_async_queue, e, wait) == pdPASS;
}

static inline bool _prepend_async_event(lwip_event_packet_t** e, TickType_t wait = portMAX_DELAY) {
  return _async_queue && xQueueSendToFront(_async_queue, e, wait) == pdPASS;
}

static inline bool _get_async_event(lwip_event_packet_t** e) {
  if (!_async_queue) {
    return false;
  }

#if CONFIG_ASYNC_TCP_USE_WDT
  // need to return periodically to feed the dog
  if (xQueueReceive(_async_queue, e, pdMS_TO_TICKS(1000)) != pdPASS)
    return false;
#else
  if (xQueueReceive(_async_queue, e, portMAX_DELAY) != pdPASS)
    return false;
#endif

  if ((*e)->event != LWIP_TCP_POLL)
    return true;

  /*
    Let's try to coalesce two (or more) consecutive poll events into one
    this usually happens with poor implemented user-callbacks that are runs too long and makes poll events to stack in the queue
    if consecutive user callback for a same connection runs longer that poll time then it will fill the queue with events until it deadlocks.
    This is a workaround to mitigate such poor designs and won't let other events/connections to starve the task time.
    It won't be effective if user would run multiple simultaneous long running callbacks due to message interleaving.
    todo: implement some kind of fair dequeing or (better) simply punish user for a bad designed callbacks by resetting hog connections
  */
  lwip_event_packet_t* next_pkt = NULL;
  while (xQueuePeek(_async_queue, &next_pkt, 0) == pdPASS) {
    if (next_pkt->arg == (*e)->arg && next_pkt->event == LWIP_TCP_POLL) {
      if (xQueueReceive(_async_queue, &next_pkt, 0) == pdPASS) {
        free(next_pkt);
        next_pkt = NULL;
        log_d("coalescing polls, network congestion or async callbacks might be too slow!");
        continue;
      }
    } else {
      /*
        poor designed apps using asynctcp without proper dataflow control could flood the queue with interleaved pool/ack events.
        We can try to mitigate it by discarding poll events when queue grows too much.
        Let's discard poll events using linear probability curve starting from 3/4 of queue length
        Poll events are periodic and connection could get another chance next time
      */
      if (uxQueueMessagesWaiting(_async_queue) > (rand() % CONFIG_ASYNC_TCP_QUEUE_SIZE / 4 + CONFIG_ASYNC_TCP_QUEUE_SIZE * 3 / 4)) {
        free(next_pkt);
        next_pkt = NULL;
        log_d("discarding poll due to queue congestion");
        // evict next event from a queue
        return _get_async_event(e);
      }
    }
    return true;
  }
  // last resort return
  return true;
}

static bool _remove_events_with_arg(void* arg) {
  lwip_event_packet_t* first_packet = NULL;
  lwip_event_packet_t* packet = NULL;

  if (!_async_queue) {
    return false;
  }
  // figure out which is the first packet so we can keep the order
  while (!first_packet) {
    if (xQueueReceive(_async_queue, &first_packet, 0) != pdPASS) {
      return false;
    }
    // discard packet if matching
    if ((int)first_packet->arg == (int)arg) {
      free(first_packet);
      first_packet = NULL;

      // try to return first packet to the back of the queue
    } else if (xQueueSend(_async_queue, &first_packet, 0) != pdPASS) {
      // we can't wait here if queue is full, because this call has been done from the only consumer task of this queue
      // otherwise it would deadlock, we have to discard the event
      return false;
    }
  }

  while (xQueuePeek(_async_queue, &packet, 0) == pdPASS && packet != first_packet) {
    if (xQueueReceive(_async_queue, &packet, 0) != pdPASS) {
      return false;
    }
    if ((int)packet->arg == (int)arg) {
      free(packet);
      packet = NULL;
    } else if (xQueueSend(_async_queue, &packet, 0) != pdPASS) {
      // we can't wait here if queue is full, because this call has been done from the only consumer task of this queue
      // otherwise it would deadlock, we have to discard the event
      return false;
    }
  }
  return true;
}

static void _handle_async_event(lwip_event_packet_t* e) {
  if (e->arg == NULL) {
    // do nothing when arg is NULL
    // ets_printf("event arg == NULL: 0x%08x\n", e->recv.pcb);
  } else if (e->event == LWIP_TCP_CLEAR) {
    _remove_events_with_arg(e->arg);
  } else if (e->event == LWIP_TCP_RECV) {
    // ets_printf("-R: 0x%08x\n", e->recv.pcb);
    AsyncClient::_s_recv(e->arg, e->recv.pcb, e->recv.pb, e->recv.err);
  } else if (e->event == LWIP_TCP_FIN) {
    // ets_printf("-F: 0x%08x\n", e->fin.pcb);
    AsyncClient::_s_fin(e->arg, e->fin.pcb, e->fin.err);
  } else if (e->event == LWIP_TCP_SENT) {
    // ets_printf("-S: 0x%08x\n", e->sent.pcb);
    AsyncClient::_s_sent(e->arg, e->sent.pcb, e->sent.len);
  } else if (e->event == LWIP_TCP_POLL) {
    // ets_printf("-P: 0x%08x\n", e->poll.pcb);
    AsyncClient::_s_poll(e->arg, e->poll.pcb);
  } else if (e->event == LWIP_TCP_ERROR) {
    // ets_printf("-E: 0x%08x %d\n", e->arg, e->error.err);
    AsyncClient::_s_error(e->arg, e->error.err);
  } else if (e->event == LWIP_TCP_CONNECTED) {
    // ets_printf("C: 0x%08x 0x%08x %d\n", e->arg, e->connected.pcb, e->connected.err);
    AsyncClient::_s_connected(e->arg, e->connected.pcb, e->connected.err);
  } else if (e->event == LWIP_TCP_ACCEPT) {
    // ets_printf("A: 0x%08x 0x%08x\n", e->arg, e->accept.client);
    AsyncServer::_s_accepted(e->arg, e->accept.client);
  } else if (e->event == LWIP_TCP_DNS) {
    // ets_printf("D: 0x%08x %s = %s\n", e->arg, e->dns.name, ipaddr_ntoa(&e->dns.addr));
    AsyncClient::_s_dns_found(e->dns.name, &e->dns.addr, e->arg);
  }
  free((void*)(e));
}

static void _async_service_task(void* pvParameters) {
#if CONFIG_ASYNC_TCP_USE_WDT
  if (esp_task_wdt_add(NULL) != ESP_OK) {
    log_w("Failed to add async task to WDT");
  }
#endif
  lwip_event_packet_t* packet = NULL;
  for (;;) {
    if (_get_async_event(&packet)) {
      _handle_async_event(packet);
    }
#if CONFIG_ASYNC_TCP_USE_WDT
    esp_task_wdt_reset();
#endif
  }
#if CONFIG_ASYNC_TCP_USE_WDT
  esp_task_wdt_delete(NULL);
#endif
  vTaskDelete(NULL);
  _async_service_task_handle = NULL;
}
/*
static void _stop_async_task(){
    if(_async_service_task_handle){
        vTaskDelete(_async_service_task_handle);
        _async_service_task_handle = NULL;
    }
}
*/

static bool customTaskCreateUniversal(
  TaskFunction_t pxTaskCode,
  const char* const pcName,
  const uint32_t usStackDepth,
  void* const pvParameters,
  UBaseType_t uxPriority,
  TaskHandle_t* const pxCreatedTask,
  const BaseType_t xCoreID) {
#ifndef CONFIG_FREERTOS_UNICORE
  if (xCoreID >= 0 && xCoreID < 2) {
    return xTaskCreatePinnedToCore(pxTaskCode, pcName, usStackDepth, pvParameters, uxPriority, pxCreatedTask, xCoreID);
  } else {
#endif
    return xTaskCreate(pxTaskCode, pcName, usStackDepth, pvParameters, uxPriority, pxCreatedTask);
#ifndef CONFIG_FREERTOS_UNICORE
  }
#endif
}

static bool _start_async_task() {
  if (!_init_async_event_queue()) {
    return false;
  }
  if (!_async_service_task_handle) {
    customTaskCreateUniversal(_async_service_task, "async_tcp", CONFIG_ASYNC_TCP_STACK_SIZE, NULL, CONFIG_ASYNC_TCP_PRIORITY, &_async_service_task_handle, CONFIG_ASYNC_TCP_RUNNING_CORE);
    if (!_async_service_task_handle) {
      return false;
    }
  }
  return true;
}

/*
 * LwIP Callbacks
 * */

static int8_t _tcp_clear_events(void* arg) {
  lwip_event_packet_t* e = (lwip_event_packet_t*)malloc(sizeof(lwip_event_packet_t));
  e->event = LWIP_TCP_CLEAR;
  e->arg = arg;
  if (!_prepend_async_event(&e)) {
    free((void*)(e));
  }
  return ERR_OK;
}

static int8_t _tcp_connected(void* arg, tcp_pcb* pcb, int8_t err) {
  // ets_printf("+C: 0x%08x\n", pcb);
  lwip_event_packet_t* e = (lwip_event_packet_t*)malloc(sizeof(lwip_event_packet_t));
  e->event = LWIP_TCP_CONNECTED;
  e->arg = arg;
  e->connected.pcb = pcb;
  e->connected.err = err;
  if (!_prepend_async_event(&e)) {
    free((void*)(e));
  }
  return ERR_OK;
}

static int8_t _tcp_poll(void* arg, struct tcp_pcb* pcb) {
  // throttle polling events queing when event queue is getting filled up, let it handle _onack's
  // log_d("qs:%u", uxQueueMessagesWaiting(_async_queue));
  if (uxQueueMessagesWaiting(_async_queue) > (rand() % CONFIG_ASYNC_TCP_QUEUE_SIZE / 2 + CONFIG_ASYNC_TCP_QUEUE_SIZE / 4)) {
    log_d("throttling");
    return ERR_OK;
  }

  // ets_printf("+P: 0x%08x\n", pcb);
  lwip_event_packet_t* e = (lwip_event_packet_t*)malloc(sizeof(lwip_event_packet_t));
  e->event = LWIP_TCP_POLL;
  e->arg = arg;
  e->poll.pcb = pcb;
  // poll events are not critical 'cause those are repetitive, so we may not wait the queue in any case
  if (!_send_async_event(&e, 0)) {
    free((void*)(e));
  }
  return ERR_OK;
}

static int8_t _tcp_recv(void* arg, struct tcp_pcb* pcb, struct pbuf* pb, int8_t err) {
  lwip_event_packet_t* e = (lwip_event_packet_t*)malloc(sizeof(lwip_event_packet_t));
  e->arg = arg;
  if (pb) {
    // ets_printf("+R: 0x%08x\n", pcb);
    e->event = LWIP_TCP_RECV;
    e->recv.pcb = pcb;
    e->recv.pb = pb;
    e->recv.err = err;
  } else {
    // ets_printf("+F: 0x%08x\n", pcb);
    e->event = LWIP_TCP_FIN;
    e->fin.pcb = pcb;
    e->fin.err = err;
    // close the PCB in LwIP thread
    AsyncClient::_s_lwip_fin(e->arg, e->fin.pcb, e->fin.err);
  }
  if (!_send_async_event(&e)) {
    free((void*)(e));
  }
  return ERR_OK;
}

static int8_t _tcp_sent(void* arg, struct tcp_pcb* pcb, uint16_t len) {
  // ets_printf("+S: 0x%08x\n", pcb);
  lwip_event_packet_t* e = (lwip_event_packet_t*)malloc(sizeof(lwip_event_packet_t));
  e->event = LWIP_TCP_SENT;
  e->arg = arg;
  e->sent.pcb = pcb;
  e->sent.len = len;
  if (!_send_async_event(&e)) {
    free((void*)(e));
  }
  return ERR_OK;
}

static void _tcp_error(void* arg, int8_t err) {
  // ets_printf("+E: 0x%08x\n", arg);
  lwip_event_packet_t* e = (lwip_event_packet_t*)malloc(sizeof(lwip_event_packet_t));
  e->event = LWIP_TCP_ERROR;
  e->arg = arg;
  e->error.err = err;
  if (!_send_async_event(&e)) {
    free((void*)(e));
  }
}

static void _tcp_dns_found(const char* name, struct ip_addr* ipaddr, void* arg) {
  lwip_event_packet_t* e = (lwip_event_packet_t*)malloc(sizeof(lwip_event_packet_t));
  // ets_printf("+DNS: name=%s ipaddr=0x%08x arg=%x\n", name, ipaddr, arg);
  e->event = LWIP_TCP_DNS;
  e->arg = arg;
  e->dns.name = name;
  if (ipaddr) {
    memcpy(&e->dns.addr, ipaddr, sizeof(struct ip_addr));
  } else {
    memset(&e->dns.addr, 0, sizeof(e->dns.addr));
  }
  if (!_send_async_event(&e)) {
    free((void*)(e));
  }
}

// Used to switch out from LwIP thread
static int8_t _tcp_accept(void* arg, AsyncClient* client) {
  lwip_event_packet_t* e = (lwip_event_packet_t*)malloc(sizeof(lwip_event_packet_t));
  e->event = LWIP_TCP_ACCEPT;
  e->arg = arg;
  e->accept.client = client;
  if (!_prepend_async_event(&e)) {
    free((void*)(e));
  }
  return ERR_OK;
}

/*
 * TCP/IP API Calls
 * */

#include "lwip/priv/tcpip_priv.h"

typedef struct {
    struct tcpip_api_call_data call;
    tcp_pcb* pcb;
    int8_t closed_slot;
    int8_t err;
    union {
        struct {
            const char* data;
            size_t size;
            uint8_t apiflags;
        } write;
        size_t received;
        struct {
            ip_addr_t* addr;
            uint16_t port;
            tcp_connected_fn cb;
        } connect;
        struct {
            ip_addr_t* addr;
            uint16_t port;
        } bind;
        uint8_t backlog;
    };
} tcp_api_call_t;

static err_t _tcp_output_api(struct tcpip_api_call_data* api_call_msg) {
  tcp_api_call_t* msg = (tcp_api_call_t*)api_call_msg;
  msg->err = ERR_CONN;
  if (msg->closed_slot == INVALID_CLOSED_SLOT || !_closed_slots[msg->closed_slot]) {
    msg->err = tcp_output(msg->pcb);
  }
  return msg->err;
}

static esp_err_t _tcp_output(tcp_pcb* pcb, int8_t closed_slot) {
  if (!pcb) {
    return ERR_CONN;
  }
  tcp_api_call_t msg;
  msg.pcb = pcb;
  msg.closed_slot = closed_slot;
  tcpip_api_call(_tcp_output_api, (struct tcpip_api_call_data*)&msg);
  return msg.err;
}

static err_t _tcp_write_api(struct tcpip_api_call_data* api_call_msg) {
  tcp_api_call_t* msg = (tcp_api_call_t*)api_call_msg;
  msg->err = ERR_CONN;
  if (msg->closed_slot == INVALID_CLOSED_SLOT || !_closed_slots[msg->closed_slot]) {
    msg->err = tcp_write(msg->pcb, msg->write.data, msg->write.size, msg->write.apiflags);
  }
  return msg->err;
}

static esp_err_t _tcp_write(tcp_pcb* pcb, int8_t closed_slot, const char* data, size_t size, uint8_t apiflags) {
  if (!pcb) {
    return ERR_CONN;
  }
  tcp_api_call_t msg;
  msg.pcb = pcb;
  msg.closed_slot = closed_slot;
  msg.write.data = data;
  msg.write.size = size;
  msg.write.apiflags = apiflags;
  tcpip_api_call(_tcp_write_api, (struct tcpip_api_call_data*)&msg);
  return msg.err;
}

static err_t _tcp_recved_api(struct tcpip_api_call_data* api_call_msg) {
  tcp_api_call_t* msg = (tcp_api_call_t*)api_call_msg;
  msg->err = ERR_CONN;
  if (msg->closed_slot == INVALID_CLOSED_SLOT || !_closed_slots[msg->closed_slot]) {
    // if(msg->closed_slot != INVALID_CLOSED_SLOT && !_closed_slots[msg->closed_slot]) {
    // if(msg->closed_slot != INVALID_CLOSED_SLOT) {
    msg->err = 0;
    tcp_recved(msg->pcb, msg->received);
  }
  return msg->err;
}

static esp_err_t _tcp_recved(tcp_pcb* pcb, int8_t closed_slot, size_t len) {
  if (!pcb) {
    return ERR_CONN;
  }
  tcp_api_call_t msg;
  msg.pcb = pcb;
  msg.closed_slot = closed_slot;
  msg.received = len;
  tcpip_api_call(_tcp_recved_api, (struct tcpip_api_call_data*)&msg);
  return msg.err;
}

static err_t _tcp_close_api(struct tcpip_api_call_data* api_call_msg) {
  tcp_api_call_t* msg = (tcp_api_call_t*)api_call_msg;
  msg->err = ERR_CONN;
  if (msg->closed_slot == INVALID_CLOSED_SLOT || !_closed_slots[msg->closed_slot]) {
    msg->err = tcp_close(msg->pcb);
  }
  return msg->err;
}

static esp_err_t _tcp_close(tcp_pcb* pcb, int8_t closed_slot) {
  if (!pcb) {
    return ERR_CONN;
  }
  tcp_api_call_t msg;
  msg.pcb = pcb;
  msg.closed_slot = closed_slot;
  tcpip_api_call(_tcp_close_api, (struct tcpip_api_call_data*)&msg);
  return msg.err;
}

static err_t _tcp_abort_api(struct tcpip_api_call_data* api_call_msg) {
  tcp_api_call_t* msg = (tcp_api_call_t*)api_call_msg;
  msg->err = ERR_CONN;
  if (msg->closed_slot == INVALID_CLOSED_SLOT || !_closed_slots[msg->closed_slot]) {
    tcp_abort(msg->pcb);
  }
  return msg->err;
}

static esp_err_t _tcp_abort(tcp_pcb* pcb, int8_t closed_slot) {
  if (!pcb) {
    return ERR_CONN;
  }
  tcp_api_call_t msg;
  msg.pcb = pcb;
  msg.closed_slot = closed_slot;
  tcpip_api_call(_tcp_abort_api, (struct tcpip_api_call_data*)&msg);
  return msg.err;
}

static err_t _tcp_connect_api(struct tcpip_api_call_data* api_call_msg) {
  tcp_api_call_t* msg = (tcp_api_call_t*)api_call_msg;
  msg->err = tcp_connect(msg->pcb, msg->connect.addr, msg->connect.port, msg->connect.cb);
  return msg->err;
}

static esp_err_t _tcp_connect(tcp_pcb* pcb, int8_t closed_slot, ip_addr_t* addr, uint16_t port, tcp_connected_fn cb) {
  if (!pcb) {
    return ESP_FAIL;
  }
  tcp_api_call_t msg;
  msg.pcb = pcb;
  msg.closed_slot = closed_slot;
  msg.connect.addr = addr;
  msg.connect.port = port;
  msg.connect.cb = cb;
  tcpip_api_call(_tcp_connect_api, (struct tcpip_api_call_data*)&msg);
  return msg.err;
}

static err_t _tcp_bind_api(struct tcpip_api_call_data* api_call_msg) {
  tcp_api_call_t* msg = (tcp_api_call_t*)api_call_msg;
  msg->err = tcp_bind(msg->pcb, msg->bind.addr, msg->bind.port);
  return msg->err;
}

static esp_err_t _tcp_bind(tcp_pcb* pcb, ip_addr_t* addr, uint16_t port) {
  if (!pcb) {
    return ESP_FAIL;
  }
  tcp_api_call_t msg;
  msg.pcb = pcb;
  msg.closed_slot = -1;
  msg.bind.addr = addr;
  msg.bind.port = port;
  tcpip_api_call(_tcp_bind_api, (struct tcpip_api_call_data*)&msg);
  return msg.err;
}

static err_t _tcp_listen_api(struct tcpip_api_call_data* api_call_msg) {
  tcp_api_call_t* msg = (tcp_api_call_t*)api_call_msg;
  msg->err = 0;
  msg->pcb = tcp_listen_with_backlog(msg->pcb, msg->backlog);
  return msg->err;
}

static tcp_pcb* _tcp_listen_with_backlog(tcp_pcb* pcb, uint8_t backlog) {
  if (!pcb) {
    return NULL;
  }
  tcp_api_call_t msg;
  msg.pcb = pcb;
  msg.closed_slot = -1;
  msg.backlog = backlog ? backlog : 0xFF;
  tcpip_api_call(_tcp_listen_api, (struct tcpip_api_call_data*)&msg);
  return msg.pcb;
}

/*
  Async TCP Client
 */

AsyncClient::AsyncClient(tcp_pcb* pcb)
    : _connect_cb(0), _connect_cb_arg(0), _discard_cb(0), _discard_cb_arg(0), _sent_cb(0), _sent_cb_arg(0), _error_cb(0), _error_cb_arg(0), _recv_cb(0), _recv_cb_arg(0), _pb_cb(0), _pb_cb_arg(0), _timeout_cb(0), _timeout_cb_arg(0), _ack_pcb(true), _tx_last_packet(0), _rx_timeout(0), _rx_last_ack(0), _ack_timeout(CONFIG_ASYNC_TCP_MAX_ACK_TIME), _connect_port(0), prev(NULL), next(NULL) {
  _pcb = pcb;
  _closed_slot = INVALID_CLOSED_SLOT;
  if (_pcb) {
    _rx_last_packet = millis();
    tcp_arg(_pcb, this);
    tcp_recv(_pcb, &_tcp_recv);
    tcp_sent(_pcb, &_tcp_sent);
    tcp_err(_pcb, &_tcp_error);
    tcp_poll(_pcb, &_tcp_poll, CONFIG_ASYNC_TCP_POLL_TIMER);
    if (!_allocate_closed_slot()) {
      _close();
    }
  }
}

AsyncClient::~AsyncClient() {
  if (_pcb) {
    _close();
  }
  _free_closed_slot();
}

/*
 * Operators
 * */

AsyncClient& AsyncClient::operator=(const AsyncClient& other) {
  if (_pcb) {
    _close();
  }

  _pcb = other._pcb;
  _closed_slot = other._closed_slot;
  if (_pcb) {
    _rx_last_packet = millis();
    tcp_arg(_pcb, this);
    tcp_recv(_pcb, &_tcp_recv);
    tcp_sent(_pcb, &_tcp_sent);
    tcp_err(_pcb, &_tcp_error);
    tcp_poll(_pcb, &_tcp_poll, CONFIG_ASYNC_TCP_POLL_TIMER);
  }
  return *this;
}

bool AsyncClient::operator==(const AsyncClient& other) {
  return _pcb == other._pcb;
}

AsyncClient& AsyncClient::operator+=(const AsyncClient& other) {
  if (next == NULL) {
    next = (AsyncClient*)(&other);
    next->prev = this;
  } else {
    AsyncClient* c = next;
    while (c->next != NULL) {
      c = c->next;
    }
    c->next = (AsyncClient*)(&other);
    c->next->prev = c;
  }
  return *this;
}

/*
 * Callback Setters
 * */

void AsyncClient::onConnect(AcConnectHandler cb, void* arg) {
  _connect_cb = cb;
  _connect_cb_arg = arg;
}

void AsyncClient::onDisconnect(AcConnectHandler cb, void* arg) {
  _discard_cb = cb;
  _discard_cb_arg = arg;
}

void AsyncClient::onAck(AcAckHandler cb, void* arg) {
  _sent_cb = cb;
  _sent_cb_arg = arg;
}

void AsyncClient::onError(AcErrorHandler cb, void* arg) {
  _error_cb = cb;
  _error_cb_arg = arg;
}

void AsyncClient::onData(AcDataHandler cb, void* arg) {
  _recv_cb = cb;
  _recv_cb_arg = arg;
}

void AsyncClient::onPacket(AcPacketHandler cb, void* arg) {
  _pb_cb = cb;
  _pb_cb_arg = arg;
}

void AsyncClient::onTimeout(AcTimeoutHandler cb, void* arg) {
  _timeout_cb = cb;
  _timeout_cb_arg = arg;
}

void AsyncClient::onPoll(AcConnectHandler cb, void* arg) {
  _poll_cb = cb;
  _poll_cb_arg = arg;
}

/*
 * Main Public Methods
 * */

bool AsyncClient::_connect(ip_addr_t addr, uint16_t port) {
  if (_pcb) {
    log_d("already connected, state %d", _pcb->state);
    return false;
  }
  if (!_start_async_task()) {
    log_e("failed to start task");
    return false;
  }

  if (!_allocate_closed_slot()) {
    log_e("failed to allocate: closed slot full");
    return false;
  }

  TCP_MUTEX_LOCK();
  tcp_pcb* pcb = tcp_new_ip_type(addr.type);
  if (!pcb) {
    TCP_MUTEX_UNLOCK();
    log_e("pcb == NULL");
    return false;
  }
  tcp_arg(pcb, this);
  tcp_err(pcb, &_tcp_error);
  tcp_recv(pcb, &_tcp_recv);
  tcp_sent(pcb, &_tcp_sent);
  tcp_poll(pcb, &_tcp_poll, CONFIG_ASYNC_TCP_POLL_TIMER);
  TCP_MUTEX_UNLOCK();

  esp_err_t err = _tcp_connect(pcb, _closed_slot, &addr, port, (tcp_connected_fn)&_tcp_connected);
  return err == ESP_OK;
}

bool AsyncClient::connect(const IPAddress& ip, uint16_t port) {
  ip_addr_t addr;
#if ESP_IDF_VERSION_MAJOR < 5
  addr.u_addr.ip4.addr = ip;
  addr.type = IPADDR_TYPE_V4;
#else
  ip.to_ip_addr_t(&addr);
#endif

  return _connect(addr, port);
}

#if LWIP_IPV6 && ESP_IDF_VERSION_MAJOR < 5
bool AsyncClient::connect(const IPv6Address& ip, uint16_t port) {
  auto ipaddr = static_cast<const uint32_t*>(ip);
  ip_addr_t addr = IPADDR6_INIT(ipaddr[0], ipaddr[1], ipaddr[2], ipaddr[3]);

  return _connect(addr, port);
}
#endif

bool AsyncClient::connect(const char* host, uint16_t port) {
  ip_addr_t addr;

  if (!_start_async_task()) {
    log_e("failed to start task");
    return false;
  }

  TCP_MUTEX_LOCK();
  err_t err = dns_gethostbyname(host, &addr, (dns_found_callback)&_tcp_dns_found, this);
  TCP_MUTEX_UNLOCK();
  if (err == ERR_OK) {
#if ESP_IDF_VERSION_MAJOR < 5
  #if LWIP_IPV6
    if (addr.type == IPADDR_TYPE_V6) {
      return connect(IPv6Address(addr.u_addr.ip6.addr), port);
    }
    return connect(IPAddress(addr.u_addr.ip4.addr), port);
  #else
    return connect(IPAddress(addr.addr), port);
  #endif
#else
    return _connect(addr, port);
#endif
  } else if (err == ERR_INPROGRESS) {
    _connect_port = port;
    return true;
  }
  log_d("error: %d", err);
  return false;
}

void AsyncClient::close(bool now) {
  if (_pcb) {
    _tcp_recved(_pcb, _closed_slot, _rx_ack_len);
  }
  _close();
}

int8_t AsyncClient::abort() {
  if (_pcb) {
    _tcp_abort(_pcb, _closed_slot);
    _pcb = NULL;
  }
  return ERR_ABRT;
}

size_t AsyncClient::space() {
  if ((_pcb != NULL) && (_pcb->state == ESTABLISHED)) {
    return tcp_sndbuf(_pcb);
  }
  return 0;
}

size_t AsyncClient::add(const char* data, size_t size, uint8_t apiflags) {
  if (!_pcb || size == 0 || data == NULL) {
    return 0;
  }
  size_t room = space();
  if (!room) {
    return 0;
  }
  size_t will_send = (room < size) ? room : size;
  int8_t err = ERR_OK;
  err = _tcp_write(_pcb, _closed_slot, data, will_send, apiflags);
  if (err != ERR_OK) {
    return 0;
  }
  return will_send;
}

bool AsyncClient::send() {
  auto backup = _tx_last_packet;
  _tx_last_packet = millis();
  if (_tcp_output(_pcb, _closed_slot) == ERR_OK) {
    return true;
  }
  _tx_last_packet = backup;
  return false;
}

size_t AsyncClient::ack(size_t len) {
  if (len > _rx_ack_len)
    len = _rx_ack_len;
  if (len) {
    _tcp_recved(_pcb, _closed_slot, len);
  }
  _rx_ack_len -= len;
  return len;
}

void AsyncClient::ackPacket(struct pbuf* pb) {
  if (!pb) {
    return;
  }
  _tcp_recved(_pcb, _closed_slot, pb->len);
  pbuf_free(pb);
}

/*
 * Main Private Methods
 * */

int8_t AsyncClient::_close() {
  // ets_printf("X: 0x%08x\n", (uint32_t)this);
  int8_t err = ERR_OK;
  if (_pcb) {
    TCP_MUTEX_LOCK();
    tcp_arg(_pcb, NULL);
    tcp_sent(_pcb, NULL);
    tcp_recv(_pcb, NULL);
    tcp_err(_pcb, NULL);
    tcp_poll(_pcb, NULL, 0);
    TCP_MUTEX_UNLOCK();
    _tcp_clear_events(this);
    err = _tcp_close(_pcb, _closed_slot);
    if (err != ERR_OK) {
      err = abort();
    }
    _free_closed_slot();
    _pcb = NULL;
    if (_discard_cb) {
      _discard_cb(_discard_cb_arg, this);
    }
  }
  return err;
}

bool AsyncClient::_allocate_closed_slot() {
  if (_closed_slot != INVALID_CLOSED_SLOT) {
    return true;
  }
  xSemaphoreTake(_slots_lock, portMAX_DELAY);
  uint32_t closed_slot_min_index = 0;
  for (int i = 0; i < _number_of_closed_slots; ++i) {
    if ((_closed_slot == INVALID_CLOSED_SLOT || _closed_slots[i] <= closed_slot_min_index) && _closed_slots[i] != 0) {
      closed_slot_min_index = _closed_slots[i];
      _closed_slot = i;
    }
  }
  if (_closed_slot != INVALID_CLOSED_SLOT) {
    _closed_slots[_closed_slot] = 0;
  }
  xSemaphoreGive(_slots_lock);
  return (_closed_slot != INVALID_CLOSED_SLOT);
}

void AsyncClient::_free_closed_slot() {
  xSemaphoreTake(_slots_lock, portMAX_DELAY);
  if (_closed_slot != INVALID_CLOSED_SLOT) {
    _closed_slots[_closed_slot] = _closed_index;
    _closed_slot = INVALID_CLOSED_SLOT;
    ++_closed_index;
  }
  xSemaphoreGive(_slots_lock);
}

/*
 * Private Callbacks
 * */

int8_t AsyncClient::_connected(tcp_pcb* pcb, int8_t err) {
  _pcb = reinterpret_cast<tcp_pcb*>(pcb);
  if (_pcb) {
    _rx_last_packet = millis();
  }
  if (_connect_cb) {
    _connect_cb(_connect_cb_arg, this);
  }
  return ERR_OK;
}

void AsyncClient::_error(int8_t err) {
  if (_pcb) {
    TCP_MUTEX_LOCK();
    tcp_arg(_pcb, NULL);
    if (_pcb->state == LISTEN) {
      tcp_sent(_pcb, NULL);
      tcp_recv(_pcb, NULL);
      tcp_err(_pcb, NULL);
      tcp_poll(_pcb, NULL, 0);
    }
    TCP_MUTEX_UNLOCK();
    _free_closed_slot();
    _pcb = NULL;
  }
  if (_error_cb) {
    _error_cb(_error_cb_arg, this, err);
  }
  if (_discard_cb) {
    _discard_cb(_discard_cb_arg, this);
  }
}

// In LwIP Thread
int8_t AsyncClient::_lwip_fin(tcp_pcb* pcb, int8_t err) {
  if (!_pcb || pcb != _pcb) {
    log_d("0x%08x != 0x%08x", (uint32_t)pcb, (uint32_t)_pcb);
    return ERR_OK;
  }
  tcp_arg(_pcb, NULL);
  if (_pcb->state == LISTEN) {
    tcp_sent(_pcb, NULL);
    tcp_recv(_pcb, NULL);
    tcp_err(_pcb, NULL);
    tcp_poll(_pcb, NULL, 0);
  }
  if (tcp_close(_pcb) != ERR_OK) {
    tcp_abort(_pcb);
  }
  _free_closed_slot();
  _pcb = NULL;
  return ERR_OK;
}

// In Async Thread
int8_t AsyncClient::_fin(tcp_pcb* pcb, int8_t err) {
  _tcp_clear_events(this);
  if (_discard_cb) {
    _discard_cb(_discard_cb_arg, this);
  }
  return ERR_OK;
}

int8_t AsyncClient::_sent(tcp_pcb* pcb, uint16_t len) {
  _rx_last_ack = _rx_last_packet = millis();
  if (_sent_cb) {
    _sent_cb(_sent_cb_arg, this, len, (_rx_last_packet - _tx_last_packet));
  }
  return ERR_OK;
}

int8_t AsyncClient::_recv(tcp_pcb* pcb, pbuf* pb, int8_t err) {
  while (pb != NULL) {
    _rx_last_packet = millis();
    // we should not ack before we assimilate the data
    _ack_pcb = true;
    pbuf* b = pb;
    pb = b->next;
    b->next = NULL;
    if (_pb_cb) {
      _pb_cb(_pb_cb_arg, this, b);
    } else {
      if (_recv_cb) {
        _recv_cb(_recv_cb_arg, this, b->payload, b->len);
      }
      if (!_ack_pcb) {
        _rx_ack_len += b->len;
      } else if (_pcb) {
        _tcp_recved(_pcb, _closed_slot, b->len);
      }
    }
    pbuf_free(b);
  }
  return ERR_OK;
}

int8_t AsyncClient::_poll(tcp_pcb* pcb) {
  if (!_pcb) {
    // log_d("pcb is NULL");
    return ERR_OK;
  }
  if (pcb != _pcb) {
    log_d("0x%08x != 0x%08x", (uint32_t)pcb, (uint32_t)_pcb);
    return ERR_OK;
  }

  uint32_t now = millis();

  // ACK Timeout
  if (_ack_timeout) {
    const uint32_t one_day = 86400000;
    bool last_tx_is_after_last_ack = (_rx_last_ack - _tx_last_packet + one_day) < one_day;
    if (last_tx_is_after_last_ack && (now - _tx_last_packet) >= _ack_timeout) {
      log_d("ack timeout %d", pcb->state);
      if (_timeout_cb)
        _timeout_cb(_timeout_cb_arg, this, (now - _tx_last_packet));
      return ERR_OK;
    }
  }
  // RX Timeout
  if (_rx_timeout && (now - _rx_last_packet) >= (_rx_timeout * 1000)) {
    log_d("rx timeout %d", pcb->state);
    _close();
    return ERR_OK;
  }
  // Everything is fine
  if (_poll_cb) {
    _poll_cb(_poll_cb_arg, this);
  }
  return ERR_OK;
}

void AsyncClient::_dns_found(struct ip_addr* ipaddr) {
#if ESP_IDF_VERSION_MAJOR < 5
  if (ipaddr && IP_IS_V4(ipaddr)) {
    connect(IPAddress(ip_addr_get_ip4_u32(ipaddr)), _connect_port);
  #if LWIP_IPV6
  } else if (ipaddr && ipaddr->u_addr.ip6.addr) {
    connect(IPv6Address(ipaddr->u_addr.ip6.addr), _connect_port);
  #endif
#else
  if (ipaddr) {
    IPAddress ip;
    ip.from_ip_addr_t(ipaddr);
    connect(ip, _connect_port);
#endif
  } else {
    if (_error_cb) {
      _error_cb(_error_cb_arg, this, -55);
    }
    if (_discard_cb) {
      _discard_cb(_discard_cb_arg, this);
    }
  }
}

/*
 * Public Helper Methods
 * */

bool AsyncClient::free() {
  if (!_pcb) {
    return true;
  }
  if (_pcb->state == CLOSED || _pcb->state > ESTABLISHED) {
    return true;
  }
  return false;
}

size_t AsyncClient::write(const char* data, size_t size, uint8_t apiflags) {
  size_t will_send = add(data, size, apiflags);
  if (!will_send || !send()) {
    return 0;
  }
  return will_send;
}

void AsyncClient::setRxTimeout(uint32_t timeout) {
  _rx_timeout = timeout;
}

uint32_t AsyncClient::getRxTimeout() {
  return _rx_timeout;
}

uint32_t AsyncClient::getAckTimeout() {
  return _ack_timeout;
}

void AsyncClient::setAckTimeout(uint32_t timeout) {
  _ack_timeout = timeout;
}

void AsyncClient::setNoDelay(bool nodelay) {
  if (!_pcb) {
    return;
  }
  if (nodelay) {
    tcp_nagle_disable(_pcb);
  } else {
    tcp_nagle_enable(_pcb);
  }
}

bool AsyncClient::getNoDelay() {
  if (!_pcb) {
    return false;
  }
  return tcp_nagle_disabled(_pcb);
}

void AsyncClient::setKeepAlive(uint32_t ms, uint8_t cnt) {
  if (ms != 0) {
    _pcb->so_options |= SOF_KEEPALIVE; // Turn on TCP Keepalive for the given pcb
    // Set the time between keepalive messages in milli-seconds
    _pcb->keep_idle = ms;
    _pcb->keep_intvl = ms;
    _pcb->keep_cnt = cnt; // The number of unanswered probes required to force closure of the socket
  } else {
    _pcb->so_options &= ~SOF_KEEPALIVE; // Turn off TCP Keepalive for the given pcb
  }
}

uint16_t AsyncClient::getMss() {
  if (!_pcb) {
    return 0;
  }
  return tcp_mss(_pcb);
}

uint32_t AsyncClient::getRemoteAddress() {
  if (!_pcb) {
    return 0;
  }
#if LWIP_IPV4 && LWIP_IPV6
  return _pcb->remote_ip.u_addr.ip4.addr;
#else
  return _pcb->remote_ip.addr;
#endif
}

#if LWIP_IPV6
ip6_addr_t AsyncClient::getRemoteAddress6() {
  if (!_pcb) {
    ip6_addr_t nulladdr;
    ip6_addr_set_zero(&nulladdr);
    return nulladdr;
  }
  return _pcb->remote_ip.u_addr.ip6;
}

ip6_addr_t AsyncClient::getLocalAddress6() {
  if (!_pcb) {
    ip6_addr_t nulladdr;
    ip6_addr_set_zero(&nulladdr);
    return nulladdr;
  }
  return _pcb->local_ip.u_addr.ip6;
}
  #if ESP_IDF_VERSION_MAJOR < 5
IPv6Address AsyncClient::remoteIP6() {
  return IPv6Address(getRemoteAddress6().addr);
}

IPv6Address AsyncClient::localIP6() {
  return IPv6Address(getLocalAddress6().addr);
}
  #else
IPAddress AsyncClient::remoteIP6() {
  if (!_pcb) {
    return IPAddress(IPType::IPv6);
  }
  IPAddress ip;
  ip.from_ip_addr_t(&(_pcb->remote_ip));
  return ip;
}

IPAddress AsyncClient::localIP6() {
  if (!_pcb) {
    return IPAddress(IPType::IPv6);
  }
  IPAddress ip;
  ip.from_ip_addr_t(&(_pcb->local_ip));
  return ip;
}
  #endif
#endif

uint16_t AsyncClient::getRemotePort() {
  if (!_pcb) {
    return 0;
  }
  return _pcb->remote_port;
}

uint32_t AsyncClient::getLocalAddress() {
  if (!_pcb) {
    return 0;
  }
#if LWIP_IPV4 && LWIP_IPV6
  return _pcb->local_ip.u_addr.ip4.addr;
#else
  return _pcb->local_ip.addr;
#endif
}

uint16_t AsyncClient::getLocalPort() {
  if (!_pcb) {
    return 0;
  }
  return _pcb->local_port;
}

IPAddress AsyncClient::remoteIP() {
#if ESP_IDF_VERSION_MAJOR < 5
  return IPAddress(getRemoteAddress());
#else
  if (!_pcb) {
    return IPAddress();
  }
  IPAddress ip;
  ip.from_ip_addr_t(&(_pcb->remote_ip));
  return ip;
#endif
}

uint16_t AsyncClient::remotePort() {
  return getRemotePort();
}

IPAddress AsyncClient::localIP() {
#if ESP_IDF_VERSION_MAJOR < 5
  return IPAddress(getLocalAddress());
#else
  if (!_pcb) {
    return IPAddress();
  }
  IPAddress ip;
  ip.from_ip_addr_t(&(_pcb->local_ip));
  return ip;
#endif
}

uint16_t AsyncClient::localPort() {
  return getLocalPort();
}

uint8_t AsyncClient::state() {
  if (!_pcb) {
    return 0;
  }
  return _pcb->state;
}

bool AsyncClient::connected() {
  if (!_pcb) {
    return false;
  }
  return _pcb->state == ESTABLISHED;
}

bool AsyncClient::connecting() {
  if (!_pcb) {
    return false;
  }
  return _pcb->state > CLOSED && _pcb->state < ESTABLISHED;
}

bool AsyncClient::disconnecting() {
  if (!_pcb) {
    return false;
  }
  return _pcb->state > ESTABLISHED && _pcb->state < TIME_WAIT;
}

bool AsyncClient::disconnected() {
  if (!_pcb) {
    return true;
  }
  return _pcb->state == CLOSED || _pcb->state == TIME_WAIT;
}

bool AsyncClient::freeable() {
  if (!_pcb) {
    return true;
  }
  return _pcb->state == CLOSED || _pcb->state > ESTABLISHED;
}

bool AsyncClient::canSend() {
  return space() > 0;
}

const char* AsyncClient::errorToString(int8_t error) {
  switch (error) {
    case ERR_OK:
      return "OK";
    case ERR_MEM:
      return "Out of memory error";
    case ERR_BUF:
      return "Buffer error";
    case ERR_TIMEOUT:
      return "Timeout";
    case ERR_RTE:
      return "Routing problem";
    case ERR_INPROGRESS:
      return "Operation in progress";
    case ERR_VAL:
      return "Illegal value";
    case ERR_WOULDBLOCK:
      return "Operation would block";
    case ERR_USE:
      return "Address in use";
    case ERR_ALREADY:
      return "Already connected";
    case ERR_CONN:
      return "Not connected";
    case ERR_IF:
      return "Low-level netif error";
    case ERR_ABRT:
      return "Connection aborted";
    case ERR_RST:
      return "Connection reset";
    case ERR_CLSD:
      return "Connection closed";
    case ERR_ARG:
      return "Illegal argument";
    case -55:
      return "DNS failed";
    default:
      return "UNKNOWN";
  }
}

const char* AsyncClient::stateToString() {
  switch (state()) {
    case 0:
      return "Closed";
    case 1:
      return "Listen";
    case 2:
      return "SYN Sent";
    case 3:
      return "SYN Received";
    case 4:
      return "Established";
    case 5:
      return "FIN Wait 1";
    case 6:
      return "FIN Wait 2";
    case 7:
      return "Close Wait";
    case 8:
      return "Closing";
    case 9:
      return "Last ACK";
    case 10:
      return "Time Wait";
    default:
      return "UNKNOWN";
  }
}

/*
 * Static Callbacks (LwIP C2C++ interconnect)
 * */

void AsyncClient::_s_dns_found(const char* name, struct ip_addr* ipaddr, void* arg) {
  reinterpret_cast<AsyncClient*>(arg)->_dns_found(ipaddr);
}

int8_t AsyncClient::_s_poll(void* arg, struct tcp_pcb* pcb) {
  return reinterpret_cast<AsyncClient*>(arg)->_poll(pcb);
}

int8_t AsyncClient::_s_recv(void* arg, struct tcp_pcb* pcb, struct pbuf* pb, int8_t err) {
  return reinterpret_cast<AsyncClient*>(arg)->_recv(pcb, pb, err);
}

int8_t AsyncClient::_s_fin(void* arg, struct tcp_pcb* pcb, int8_t err) {
  return reinterpret_cast<AsyncClient*>(arg)->_fin(pcb, err);
}

int8_t AsyncClient::_s_lwip_fin(void* arg, struct tcp_pcb* pcb, int8_t err) {
  return reinterpret_cast<AsyncClient*>(arg)->_lwip_fin(pcb, err);
}

int8_t AsyncClient::_s_sent(void* arg, struct tcp_pcb* pcb, uint16_t len) {
  return reinterpret_cast<AsyncClient*>(arg)->_sent(pcb, len);
}

void AsyncClient::_s_error(void* arg, int8_t err) {
  reinterpret_cast<AsyncClient*>(arg)->_error(err);
}

int8_t AsyncClient::_s_connected(void* arg, struct tcp_pcb* pcb, int8_t err) {
  return reinterpret_cast<AsyncClient*>(arg)->_connected(pcb, err);
}

/*
  Async TCP Server
 */

AsyncServer::AsyncServer(IPAddress addr, uint16_t port)
    : _port(port)
#if ESP_IDF_VERSION_MAJOR < 5
      ,
      _bind4(true), _bind6(false)
#else
      ,
      _bind4(addr.type() != IPType::IPv6), _bind6(addr.type() == IPType::IPv6)
#endif
      ,
      _addr(addr), _noDelay(false), _pcb(0), _connect_cb(0), _connect_cb_arg(0) {
}

#if ESP_IDF_VERSION_MAJOR < 5
AsyncServer::AsyncServer(IPv6Address addr, uint16_t port)
    : _port(port), _bind4(false), _bind6(true), _addr6(addr), _noDelay(false), _pcb(0), _connect_cb(0), _connect_cb_arg(0) {}
#endif

AsyncServer::AsyncServer(uint16_t port)
    : _port(port), _bind4(true), _bind6(false), _addr((uint32_t)IPADDR_ANY)
#if ESP_IDF_VERSION_MAJOR < 5
      ,
      _addr6()
#endif
      ,
      _noDelay(false), _pcb(0), _connect_cb(0), _connect_cb_arg(0) {
}

AsyncServer::~AsyncServer() {
  end();
}

void AsyncServer::onClient(AcConnectHandler cb, void* arg) {
  _connect_cb = cb;
  _connect_cb_arg = arg;
}

void AsyncServer::begin() {
  if (_pcb) {
    return;
  }

  if (!_start_async_task()) {
    log_e("failed to start task");
    return;
  }
  int8_t err;
  TCP_MUTEX_LOCK();
  _pcb = tcp_new_ip_type(_bind4 && _bind6 ? IPADDR_TYPE_ANY : (_bind6 ? IPADDR_TYPE_V6 : IPADDR_TYPE_V4));
  TCP_MUTEX_UNLOCK();
  if (!_pcb) {
    log_e("_pcb == NULL");
    return;
  }

  ip_addr_t local_addr;
#if ESP_IDF_VERSION_MAJOR < 5
  if (_bind6) { // _bind6 && _bind4 both at the same time is not supported on Arduino 2 in this lib API
    local_addr.type = IPADDR_TYPE_V6;
    memcpy(local_addr.u_addr.ip6.addr, static_cast<const uint32_t*>(_addr6), sizeof(uint32_t) * 4);
  } else {
    local_addr.type = IPADDR_TYPE_V4;
    local_addr.u_addr.ip4.addr = _addr;
  }
#else
  _addr.to_ip_addr_t(&local_addr);
#endif
  err = _tcp_bind(_pcb, &local_addr, _port);

  if (err != ERR_OK) {
    _tcp_close(_pcb, -1);
    log_e("bind error: %d", err);
    return;
  }

  static uint8_t backlog = 5;
  _pcb = _tcp_listen_with_backlog(_pcb, backlog);
  if (!_pcb) {
    log_e("listen_pcb == NULL");
    return;
  }
  TCP_MUTEX_LOCK();
  tcp_arg(_pcb, (void*)this);
  tcp_accept(_pcb, &_s_accept);
  TCP_MUTEX_UNLOCK();
}

void AsyncServer::end() {
  if (_pcb) {
    TCP_MUTEX_LOCK();
    tcp_arg(_pcb, NULL);
    tcp_accept(_pcb, NULL);
    if (tcp_close(_pcb) != ERR_OK) {
      TCP_MUTEX_UNLOCK();
      _tcp_abort(_pcb, -1);
    } else {
      TCP_MUTEX_UNLOCK();
    }
    _pcb = NULL;
  }
}

// runs on LwIP thread
int8_t AsyncServer::_accept(tcp_pcb* pcb, int8_t err) {
  // ets_printf("+A: 0x%08x\n", pcb);
  if (_connect_cb) {
    AsyncClient* c = new AsyncClient(pcb);
    if (c) {
      c->setNoDelay(_noDelay);
      return _tcp_accept(this, c);
    }
  }
  if (tcp_close(pcb) != ERR_OK) {
    tcp_abort(pcb);
  }
  log_d("FAIL");
  return ERR_OK;
}

int8_t AsyncServer::_accepted(AsyncClient* client) {
  if (_connect_cb) {
    _connect_cb(_connect_cb_arg, client);
  }
  return ERR_OK;
}

void AsyncServer::setNoDelay(bool nodelay) {
  _noDelay = nodelay;
}

bool AsyncServer::getNoDelay() {
  return _noDelay;
}

uint8_t AsyncServer::status() {
  if (!_pcb) {
    return 0;
  }
  return _pcb->state;
}

int8_t AsyncServer::_s_accept(void* arg, tcp_pcb* pcb, int8_t err) {
  return reinterpret_cast<AsyncServer*>(arg)->_accept(pcb, err);
}

int8_t AsyncServer::_s_accepted(void* arg, AsyncClient* client) {
  return reinterpret_cast<AsyncServer*>(arg)->_accepted(client);
}