ESP8266HTTPClient: allow getString() more than once (#5091)

fixes #4951

libraries/ESP8266HTTPClient/src/ESP8266HTTPClient.cpp

@@ -33,7 +33,7 @@
 class TransportTraits
 {
 public:
-    virtual ~TransportTraits() 
+    virtual ~TransportTraits()
     {
     }
 
@@ -126,6 +126,7 @@ void HTTPClient::clear()
     _returnCode = 0;
     _size = -1;
     _headers = "";
+    _payload.reset();
 }
 
 
@@ -281,6 +282,16 @@ bool HTTPClient::begin(String host, uint16_t port, String uri, const uint8_t htt
  * called after the payload is handled
  */
 void HTTPClient::end(void)
+{
+    disconnect();
+    clear();
+}
+
+/**
+ * disconnect
+ * close the TCP socket
+ */
+void HTTPClient::disconnect()
 {
     if(connected()) {
         if(_tcp->available() > 0) {
@@ -734,7 +745,7 @@ int HTTPClient::writeToStream(Stream * stream)
         return returnError(HTTPC_ERROR_ENCODING);
     }
 
-    end();
+    disconnect();
     return ret;
 }
 
@@ -742,20 +753,24 @@ int HTTPClient::writeToStream(Stream * stream)
  * return all payload as String (may need lot of ram or trigger out of memory!)
  * @return String
  */
-String HTTPClient::getString(void)
+const String& HTTPClient::getString(void)
 {
-    StreamString sstring;
+    if (_payload) {
+        return *_payload;
+    }
+
+    _payload.reset(new StreamString());
 
     if(_size) {
         // try to reserve needed memmory
-        if(!sstring.reserve((_size + 1))) {
+        if(!_payload->reserve((_size + 1))) {
             DEBUG_HTTPCLIENT("[HTTP-Client][getString] not enough memory to reserve a string! need: %d\n", (_size + 1));
-            return "";
+            return *_payload;
         }
     }
 
-    writeToStream(&sstring);
-    return sstring;
+    writeToStream(_payload.get());
+    return *_payload;
 }
 
 /**

libraries/ESP8266HTTPClient/src/ESP8266HTTPClient.h

@@ -127,6 +127,8 @@ typedef enum {
 class TransportTraits;
 typedef std::unique_ptr<TransportTraits> TransportTraitsPtr;
 
+class StreamString;
+
 class HTTPClient
 {
 public:
@@ -185,7 +187,7 @@ public:
     WiFiClient& getStream(void);
     WiFiClient* getStreamPtr(void);
     int writeToStream(Stream* stream);
-    String getString(void);
+    const String& getString(void);
 
     static String errorToString(int error);
 
@@ -196,6 +198,7 @@ protected:
     };
 
     bool beginInternal(String url, const char* expectedProtocol);
+    void disconnect();
     void clear();
     int returnError(int error);
     bool connect(void);
@@ -228,6 +231,7 @@ protected:
     int _size = -1;
     bool _canReuse = false;
     transferEncoding_t _transferEncoding = HTTPC_TE_IDENTITY;
+    std::unique_ptr<StreamString> _payload;
 };