Fix improper recv callback return when ssl layer returned SSL_CLOSE_NOTIFY (#84)

Author: Adam5Wu

src/ESPAsyncTCP.cpp

@@ -399,7 +399,7 @@ err_t AsyncClient::_recv(tcp_pcb* pcb, pbuf* pb, err_t err) {
         ASYNC_TCP_DEBUG("_recv err: %d\n", read_bytes);
         _close();
       }
-      return read_bytes;
+      //return read_bytes;
     }
     return ERR_OK;
   }

src/tcp_axtls.c

@@ -406,6 +406,7 @@ int tcp_ssl_read(struct tcp_pcb *tcp, struct pbuf *p) {
   } while (p->tot_len - fd_data->pbuf_offset > 0);
 
   tcp_recved(tcp, p->tot_len);
+  fd_data->tcp_pbuf = NULL;
   pbuf_free(p);
 
   return total_bytes;

src/tcp_axtls.h

@@ -40,6 +40,7 @@
 extern "C" {
 #endif
 
+#include <stdbool.h>
 #include "include/ssl.h"
 
 #define ERR_TCP_SSL_INVALID_SSL           -101