diff --git a/cores/esp8266/core_esp8266_timer.c b/cores/esp8266/core_esp8266_timer.c
index 9edee3671..bfdd3692c 100644
--- a/cores/esp8266/core_esp8266_timer.c
+++ b/cores/esp8266/core_esp8266_timer.c
@@ -30,39 +30,32 @@ void timer1_isr_handler(void *para){
     if(timer1_user_cb) timer1_user_cb();
 }
 
-extern void __timer1_isr_init(){
+void timer1_isr_init(){
     ETS_FRC_TIMER1_INTR_ATTACH(timer1_isr_handler, NULL);
 }
 
-extern void __timer1_attachInterrupt(void (*userFunc)(void)) {
+void timer1_attachInterrupt(void (*userFunc)(void)) {
     timer1_user_cb = userFunc;
     ETS_FRC1_INTR_ENABLE();
 }
 
-extern void __timer1_detachInterrupt() {
+void timer1_detachInterrupt() {
     timer1_user_cb = 0;
     TEIE &= ~TEIE1;//edge int disable
     ETS_FRC1_INTR_DISABLE();
 }
 
-extern void __timer1_enable(uint8_t divider, uint8_t int_type, uint8_t reload){
+void timer1_enable(uint8_t divider, uint8_t int_type, uint8_t reload){
     T1C = (1 << TCTE) | ((divider & 3) << TCPD) | ((int_type & 1) << TCIT) | ((reload & 1) << TCAR);
     T1I = 0;
 }
 
-extern void __timer1_write(uint32_t ticks){
+void timer1_write(uint32_t ticks){
     T1L = ((ticks) & 0x7FFFFF);
     if((T1C & (1 << TCIT)) == 0) TEIE |= TEIE1;//edge int enable
 }
 
-extern void __timer1_disable(){
+void timer1_disable(){
     T1C = 0;
     T1I = 0;
 }
-
-extern void timer1_isr_init(void) __attribute__ ((weak, alias("__timer1_isr_init")));
-extern void timer1_detachInterrupt(void) __attribute__ ((weak, alias("__timer1_detachInterrupt")));
-extern void timer1_disable(void) __attribute__ ((weak, alias("__timer1_disable")));
-extern void timer1_attachInterrupt(void (*userFunc)(void)) __attribute__ ((weak, alias("__timer1_attachInterrupt")));
-extern void timer1_write(uint32_t ticks) __attribute__ ((weak, alias("__timer1_write")));
-extern void timer1_enable(uint8_t divider, uint8_t int_type, uint8_t reload) __attribute__ ((weak, alias("__timer1_enable")));
\ No newline at end of file
diff --git a/cores/esp8266/libc_replacements.c b/cores/esp8266/libc_replacements.c
index 0554184d5..c1abbcf6f 100644
--- a/cores/esp8266/libc_replacements.c
+++ b/cores/esp8266/libc_replacements.c
@@ -175,6 +175,9 @@ char* ICACHE_FLASH_ATTR strtok_r(char * str, const char * delimiters, char ** te
     uint32_t size = 0;
 
     if(str == NULL) {
+        if(temp == NULL) {
+            return NULL;
+        }
         start = *temp;
     } else {
         start = str;
@@ -184,6 +187,10 @@ char* ICACHE_FLASH_ATTR strtok_r(char * str, const char * delimiters, char ** te
         return NULL;
     }
 
+    if(delimiters == NULL) {
+        return NULL;
+    }
+
     end = start;
 
     while(1) {
@@ -211,7 +218,9 @@ char* ICACHE_FLASH_ATTR strtok_r(char * str, const char * delimiters, char ** te
 }
 
 char* ICACHE_FLASH_ATTR strtok(char * str, const char * delimiters) {
-    return strtok_r(str, delimiters, NULL);
+    static char * ret = NULL;
+    ret = strtok_r(str, delimiters, &ret);
+    return ret;
 }
 
 int strcasecmp(const char * str1, const char * str2) {
diff --git a/libraries/ESP8266WiFi/src/WiFiServer.cpp b/libraries/ESP8266WiFi/src/WiFiServer.cpp
index ec61b424b..1ed2a64c1 100644
--- a/libraries/ESP8266WiFi/src/WiFiServer.cpp
+++ b/libraries/ESP8266WiFi/src/WiFiServer.cpp
@@ -75,6 +75,11 @@ void WiFiServer::begin()
 
 extern "C" uint32_t esp_micros_at_task_start();
 
+bool WiFiServer::hasClient(){
+  if (_unclaimed) return true;
+  return false;
+}
+
 WiFiClient WiFiServer::available(byte* status)
 {
     static uint32_t lastPollTime = 0;
diff --git a/libraries/ESP8266WiFi/src/WiFiServer.h b/libraries/ESP8266WiFi/src/WiFiServer.h
index 0bd427e2f..7e7b0491b 100644
--- a/libraries/ESP8266WiFi/src/WiFiServer.h
+++ b/libraries/ESP8266WiFi/src/WiFiServer.h
@@ -44,6 +44,7 @@ private:
 public:
   WiFiServer(uint16_t port);
   WiFiClient available(uint8_t* status = NULL);
+  bool hasClient();
   void begin();
   virtual size_t write(uint8_t);
   virtual size_t write(const uint8_t *buf, size_t size);
diff --git a/libraries/ESP8266WiFi/src/include/ClientContext.h b/libraries/ESP8266WiFi/src/include/ClientContext.h
index f9fd4e524..0001ef08b 100644
--- a/libraries/ESP8266WiFi/src/include/ClientContext.h
+++ b/libraries/ESP8266WiFi/src/include/ClientContext.h
@@ -39,7 +39,39 @@ class ClientContext {
             tcp_sent(pcb, &_s_sent);
             tcp_err(pcb, &_s_error);
         }
-
+        
+        err_t abort(){
+          if(_pcb) {
+              DEBUGV(":abort\r\n");
+              tcp_arg(_pcb, NULL);
+              tcp_sent(_pcb, NULL);
+              tcp_recv(_pcb, NULL);
+              tcp_err(_pcb, NULL);
+              tcp_abort(_pcb);
+              _pcb = 0;
+          }
+          return ERR_ABRT;
+        }
+        
+        err_t close(){
+          err_t err = ERR_OK;
+          if(_pcb) {
+              DEBUGV(":close\r\n");
+              tcp_arg(_pcb, NULL);
+              tcp_sent(_pcb, NULL);
+              tcp_recv(_pcb, NULL);
+              tcp_err(_pcb, NULL);
+              err = tcp_close(_pcb);
+              if(err != ERR_OK) {
+                  DEBUGV(":tc err %d\r\n", err);
+                  tcp_abort(_pcb);
+                  err = ERR_ABRT;
+              }
+              _pcb = 0;
+          }
+          return err;
+        }
+        
         ~ClientContext() {
         }
 
@@ -58,22 +90,11 @@ class ClientContext {
         }
 
         void unref() {
-            err_t err;
             DEBUGV(":ur %d\r\n", _refcnt);
             if(--_refcnt == 0) {
                 flush();
-                if(_pcb) {
-                    tcp_arg(_pcb, NULL);
-                    tcp_sent(_pcb, NULL);
-                    tcp_recv(_pcb, NULL);
-                    tcp_err(_pcb, NULL);
-                    err = tcp_close(_pcb);
-                    if(err != ERR_OK) {
-                        DEBUGV(":tc err %d\r\n", err);
-                        tcp_abort(_pcb);
-                    }
-                    _pcb = 0;
-                }
+                close();
+                if(_discard_cb) _discard_cb(_discard_cb_arg, this);
                 delete this;
             }
         }
@@ -179,6 +200,13 @@ class ClientContext {
 
     private:
 
+        err_t _sent(tcp_pcb* pcb, uint16_t len) {
+            DEBUGV(":sent %d\r\n", len);
+            _size_sent -= len;
+            if(_size_sent == 0 && _send_waiting) esp_schedule();
+            return ERR_OK;
+        }
+
         void _consume(size_t size) {
             ptrdiff_t left = _rx_buf->len - _rx_buf_offset - size;
             if(left > 0) {
@@ -204,21 +232,8 @@ class ClientContext {
 
             if(pb == 0) // connection closed
             {
-                DEBUGV(":rcl\r\n");
-                tcp_arg(pcb, NULL);
-                tcp_sent(pcb, NULL);
-                tcp_recv(pcb, NULL);
-                tcp_err(pcb, NULL);
-                // int error = tcp_close(pcb);
-                // if (error != ERR_OK)
-                {
-                    DEBUGV(":rcla\r\n");
-                    tcp_abort(pcb);
-                    _pcb = 0;
-                    return ERR_ABRT;
-                }
-                _pcb = 0;
-                return ERR_OK;
+                DEBUGV(":rcla\r\n");
+                return abort();
             }
 
             if(_rx_buf) {
@@ -231,27 +246,12 @@ class ClientContext {
                 _rx_buf = pb;
                 _rx_buf_offset = 0;
             }
-            // tcp_recved(pcb, received);
-            // pbuf_free(pb);
             return ERR_OK;
         }
 
         void _error(err_t err) {
             DEBUGV(":er %d\r\n", err);
-
-            if(_pcb) {
-                tcp_arg(_pcb, NULL);
-                tcp_sent(_pcb, NULL);
-                tcp_recv(_pcb, NULL);
-                tcp_err(_pcb, NULL);
-                err = tcp_close(_pcb);
-                if(err != ERR_OK) {
-                    DEBUGV(":tc err %d\r\n", err);
-                    tcp_abort(_pcb);
-                }
-            }
-            _pcb = 0;
-
+            close();
             if(_size_sent && _send_waiting) {
                 esp_schedule();
             }
@@ -261,13 +261,6 @@ class ClientContext {
             return ERR_OK;
         }
 
-        err_t _sent(tcp_pcb* pcb, uint16_t len) {
-            DEBUGV(":sent %d\r\n", len);
-            _size_sent -= len;
-            if(_size_sent == 0 && _send_waiting) esp_schedule();
-            return ERR_OK;
-        }
-
         static err_t _s_recv(void *arg, struct tcp_pcb *tpcb, struct pbuf *pb, err_t err) {
             return reinterpret_cast<ClientContext*>(arg)->_recv(tpcb, pb, err);
         }
diff --git a/libraries/SD/src/SD.cpp b/libraries/SD/src/SD.cpp
index d426dbe8e..6862daed8 100644
--- a/libraries/SD/src/SD.cpp
+++ b/libraries/SD/src/SD.cpp
@@ -326,7 +326,13 @@ boolean callback_rmdir(SdFile& parentDir, char *filePathComponent,
   return true;
 }
 
-boolean SDClass::begin(uint8_t csPin, uint32_t sckRateID) {
+
+
+/* Implementation of class used to create `SDCard` object. */
+
+
+
+boolean SDClass::begin(uint8_t csPin, uint32_t speed) {
   /*
 
     Performs the initialisation required by the sdfatlib library.
@@ -334,7 +340,7 @@ boolean SDClass::begin(uint8_t csPin, uint32_t sckRateID) {
     Return true if initialization succeeds, false otherwise.
 
    */
-  return card.init(sckRateID, csPin) &&
+  return card.init(speed, csPin) &&
          volume.init(card) &&
          root.openRoot(volume);
 }
diff --git a/libraries/SD/src/SD.h b/libraries/SD/src/SD.h
index e229cf8ad..449984219 100644
--- a/libraries/SD/src/SD.h
+++ b/libraries/SD/src/SD.h
@@ -65,7 +65,7 @@ private:
 public:
   // This needs to be called to set up the connection to the SD card
   // before other methods are used.
-  boolean begin(uint8_t csPin = SD_CHIP_SELECT_PIN, uint32_t sckRateID = SPI_FULL_SPEED);
+  boolean begin(uint8_t csPin = SD_CHIP_SELECT_PIN, uint32_t speed = SPI_HALF_SPEED);
 
   // Open the specified file/directory with the supplied mode (e.g. read or
   // write, etc). Returns a File object for interacting with the file.