add function peekBytes to WiFiClient/WiFiClientSecure to allow to peek multiple bytes if possible

libraries/ESP8266WiFi/src/WiFiClient.cpp

@@ -239,6 +239,27 @@ int WiFiClient::peek()
     return _client->peek();
 }
 
+size_t WiFiClient::peekBytes(uint8_t *buffer, size_t length) {
+    size_t count = 0;
+
+    if(!_client) {
+        return 0;
+    }
+
+    _startMillis = millis();
+    while((available() < (int) length) && ((millis() - _startMillis) < _timeout)) {
+        yield();
+    }
+
+    if(available() < (int) length) {
+        count = available();
+    } else {
+        count = length;
+    }
+
+    return _client->peekBytes((char *)buffer, count);
+}
+
 void WiFiClient::flush()
 {
     if (_client)

libraries/ESP8266WiFi/src/WiFiClient.h

@@ -56,6 +56,10 @@ public:
   virtual int read();
   virtual int read(uint8_t *buf, size_t size);
   virtual int peek();
+  virtual size_t peekBytes(uint8_t *buffer, size_t length);
+  size_t peekBytes(char *buffer, size_t length) {
+    return peekBytes((uint8_t *) buffer, length);
+  }
   virtual void flush();
   virtual void stop();
   virtual uint8_t connected();

libraries/ESP8266WiFi/src/WiFiClientSecure.cpp

@@ -133,6 +133,17 @@ public:
         return _read_ptr[0];
     }
 
+    size_t peekBytes(char *dst, size_t size) {
+        if(!_available) {
+            if(!_readAll())
+                return -1;
+        }
+
+        size_t will_copy = (_available < size) ? _available : size;
+        memcpy(dst, _read_ptr, will_copy);
+        return will_copy;
+    }
+
     int available() {
         auto cb = _available;
         if (cb == 0) {
@@ -278,6 +289,27 @@ int WiFiClientSecure::peek() {
     return _ssl->peek();
 }
 
+size_t WiFiClientSecure::peekBytes(uint8_t *buffer, size_t length) {
+    size_t count = 0;
+
+    if(!_ssl) {
+        return 0;
+    }
+
+    _startMillis = millis();
+    while((available() < (int) length) && ((millis() - _startMillis) < _timeout)) {
+        yield();
+    }
+
+    if(available() < (int) length) {
+        count = available();
+    } else {
+        count = length;
+    }
+
+    return _ssl->peekBytes((char *)buffer, count);
+}
+
 int WiFiClientSecure::available() {
     if (!_ssl)
         return 0;

libraries/ESP8266WiFi/src/WiFiClientSecure.h

@@ -46,6 +46,7 @@ public:
   int available() override;
   int read() override;
   int peek() override;
+  size_t peekBytes(uint8_t *buffer, size_t length) override;
   void stop() override;
 
   void setCertificate(const uint8_t* cert_data, size_t size);

libraries/ESP8266WiFi/src/include/ClientContext.h

@@ -179,6 +179,20 @@ class ClientContext {
             return reinterpret_cast<char*>(_rx_buf->payload)[_rx_buf_offset];
         }
 
+        size_t peekBytes(char *dst, size_t size) {
+            if(!_rx_buf) return 0;
+
+            size_t max_size = _rx_buf->tot_len - _rx_buf_offset;
+            size = (size < max_size) ? size : max_size;
+
+            DEBUGV(":pd %d, %d, %d\r\n", size, _rx_buf->tot_len, _rx_buf_offset);
+            size_t buf_size = _rx_buf->len - _rx_buf_offset;
+            size_t copy_size = (size < buf_size) ? size : buf_size;
+            DEBUGV(":rpi %d, %d\r\n", buf_size, copy_size);
+            os_memcpy(dst, reinterpret_cast<char*>(_rx_buf->payload) + _rx_buf_offset, copy_size);
+            return copy_size;
+        }
+
         void flush() {
             if(!_rx_buf) {
                 return;