ESP8266WebServer: fix handling of empty POST

Fix handling of case when Content-Length is 0.
Change do {} while() loop into while(){} so that we don't wait 1000ms for data in case Content-Length is 0.
Also fix handling of cases when malloc or realloc return null.

Author: igrr

libraries/ESP8266WebServer/src/ESP8266WebServer.h

@@ -34,6 +34,7 @@ enum HTTPClientStatus { HC_NONE, HC_WAIT_READ, HC_WAIT_CLOSE };
 #define HTTP_DOWNLOAD_UNIT_SIZE 1460
 #define HTTP_UPLOAD_BUFLEN 2048
 #define HTTP_MAX_DATA_WAIT 1000 //ms to wait for the client to send the request
+#define HTTP_MAX_POST_WAIT 1000 //ms to wait for POST data to arrive
 #define HTTP_MAX_CLOSE_WAIT 2000 //ms to wait for the client to close the connection
 
 #define CONTENT_LENGTH_UNKNOWN ((size_t) -1)
@@ -66,13 +67,13 @@ class ESP8266WebServer
 
   void begin();
   void handleClient();
-  
+
   void close();
   void stop();
 
   bool authenticate(const char * username, const char * password);
   void requestAuthentication();
-  
+
   typedef std::function<void(void)> THandlerFunction;
   void on(const char* uri, THandlerFunction handler);
   void on(const char* uri, HTTPMethod method, THandlerFunction fn);

libraries/ESP8266WebServer/src/Parsing.cpp

@@ -31,6 +31,38 @@
 #define DEBUG_OUTPUT Serial
 #endif
 
+static char* readBytesWithTimeout(WiFiClient& client, size_t maxLength, size_t& dataLength, int timeout_ms)
+{
+  char *buf = nullptr;
+  dataLength = 0;
+  while (dataLength < maxLength) {
+    int tries = timeout_ms;
+    size_t newLength;
+    while (!(newLength = client.available()) && tries--) delay(1);
+    if (!newLength) {
+      break;
+    }
+    if (!buf) {
+      buf = (char *) malloc(newLength + 1);
+      if (!buf) {
+        return nullptr;
+      }
+    }
+    else {
+      char* newBuf = (char *) realloc(buf, dataLength + newLength + 1);
+      if (!newBuf) {
+        free(buf);
+        return nullptr;
+      }
+      buf = newBuf;
+    }
+    client.readBytes(buf + dataLength, newLength);
+    dataLength += newLength;
+    buf[dataLength] = '\0';
+  }
+  return buf;
+}
+
 bool ESP8266WebServer::_parseRequest(WiFiClient& client) {
   // Read the first line of HTTP request
   String req = client.readStringUntil('\r');
@@ -114,14 +146,14 @@ bool ESP8266WebServer::_parseRequest(WiFiClient& client) {
       headerValue = req.substring(headerDiv + 1);
       headerValue.trim();
        _collectHeader(headerName.c_str(),headerValue.c_str());
-	  
+
 	  #ifdef DEBUG_ESP_HTTP_SERVER
 	  DEBUG_OUTPUT.print("headerName: ");
 	  DEBUG_OUTPUT.println(headerName);
 	  DEBUG_OUTPUT.print("headerValue: ");
 	  DEBUG_OUTPUT.println(headerValue);
 	  #endif
-	  
+
       if (headerName == "Content-Type"){
         if (headerValue.startsWith("text/plain")){
           isForm = false;
@@ -137,41 +169,27 @@ bool ESP8266WebServer::_parseRequest(WiFiClient& client) {
     }
 
     if (!isForm){
-      if (searchStr != "") searchStr += '&';
-      char *plainBuf = nullptr;
-      size_t plainLen = 0;
-      do
-      {
-        //some clients send headers first and data after (like we do)
-        //give them a chance
-        int tries = 1000;//1000ms max wait
-        size_t newLen;
-        while( !(newLen = client.available()) && tries--) delay(1);
-        if (!newLen) break;
-        plainBuf = (plainBuf == nullptr) ?  (char *) malloc(newLen + 1) : (char *) realloc(plainBuf, plainLen + newLen + 1);
-        client.readBytes(&plainBuf[plainLen], newLen);
-        plainLen += newLen;
-        plainBuf[plainLen] = '\0';
-      } while (plainLen < contentLength);
-      /* if data loss,  exit */
-      if (plainBuf == nullptr) return false;
-      if (plainLen < contentLength)
-      {
+      size_t plainLength;
+      char* plainBuf = readBytesWithTimeout(client, contentLength, plainLength, HTTP_MAX_POST_WAIT);
+      if (plainLength < contentLength) {
       	free(plainBuf);
       	return false;
       }
 #ifdef DEBUG_ESP_HTTP_SERVER
       DEBUG_OUTPUT.print("Plain: ");
       DEBUG_OUTPUT.println(plainBuf);
 #endif
-      if(plainBuf[0] == '{' || plainBuf[0] == '[' || strstr(plainBuf, "=") == NULL){
-        //plain post json or other data
-        searchStr += "plain=";
-        searchStr += plainBuf;
-      } else {
-        searchStr += plainBuf;
+      if (contentLength > 0) {
+        if (searchStr != "") searchStr += '&';
+        if(plainBuf[0] == '{' || plainBuf[0] == '[' || strstr(plainBuf, "=") == NULL){
+          //plain post json or other data
+          searchStr += "plain=";
+          searchStr += plainBuf;
+        } else {
+          searchStr += plainBuf;
+        }
+        free(plainBuf);
       }
-      free(plainBuf);
     }
     _parseArguments(searchStr);
     if (isForm){
@@ -194,14 +212,14 @@ bool ESP8266WebServer::_parseRequest(WiFiClient& client) {
       headerName = req.substring(0, headerDiv);
       headerValue = req.substring(headerDiv + 2);
       _collectHeader(headerName.c_str(),headerValue.c_str());
-	  
+
 	  #ifdef DEBUG_ESP_HTTP_SERVER
 	  DEBUG_OUTPUT.print("headerName: ");
 	  DEBUG_OUTPUT.println(headerName);
 	  DEBUG_OUTPUT.print("headerValue: ");
 	  DEBUG_OUTPUT.println(headerValue);
 	  #endif
-	  
+
 	  if (headerName == "Host"){
         _hostHeader = headerValue;
       }