- Move all serialization code to separate Serializer namespace and files.

- Generalize and improve JSON processing code.

- Prevent mesh passwords from containing " characters to avoid messing up the JSON processing.

- Improve documentation.

libraries/ESP8266WiFiMesh/src/Serializer.cpp

@@ -0,0 +1,122 @@
+/*
+ * Copyright (C) 2020 Anders Löfgren
+ *
+ * License (MIT license):
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+ 
+#include "Serializer.h"
+#include "JsonTranslator.h"
+#include "TypeConversionFunctions.h"
+#include "MeshCryptoInterface.h" 
+
+namespace
+{
+  namespace TypeCast = MeshTypeConversionFunctions;
+
+  String createJsonEndPair(const String &valueIdentifier, const String &value)
+  {
+    const String q = String('"');
+    return q + valueIdentifier + q + ':' + q + value + F("\"}}");
+  }
+}
+
+namespace Serializer
+{
+  /*
+   * NOTE: The internal states may be changed in future updates, so the function signatures here are not guaranteed to be stable.
+   */
+  
+  String serializeMeshState(const String &unsyncMsgID, const String &meshMsgCount)
+  {
+    using namespace JsonTranslator;
+
+    // Returns: {"meshState":{"connectionState":{"unsyncMsgID":"123"},"meshMsgCount":"123"}}
+    return encode({FPSTR(jsonMeshState), encode({FPSTR(jsonConnectionState), encode({FPSTR(jsonUnsynchronizedMessageID), unsyncMsgID}), FPSTR(jsonMeshMessageCount), meshMsgCount})});
+  }
+
+  String serializeUnencryptedConnection(const String &unsyncMsgID)
+  {
+    using namespace JsonTranslator;
+
+    // Returns: {"connectionState":{"unsyncMsgID":"123"}}
+    return encode({FPSTR(jsonConnectionState), encode({FPSTR(jsonUnsynchronizedMessageID), unsyncMsgID})});
+  }
+
+  String serializeEncryptedConnection(const String &duration, const String &desync, const String &ownSK, const String &peerSK, const String &peerStaMac, const String &peerApMac)
+  {
+    using namespace JsonTranslator;
+
+    if(duration.isEmpty())
+    {
+      // Returns: {"connectionState":{"desync":"0","ownSK":"1A2","peerSK":"3B4","peerStaMac":"F2","peerApMac":"E3"}}
+      return encode({FPSTR(jsonConnectionState), encode({FPSTR(jsonDesync), desync, FPSTR(jsonOwnSessionKey), ownSK, FPSTR(jsonPeerSessionKey), peerSK, 
+                     FPSTR(jsonPeerStaMac), peerStaMac, FPSTR(jsonPeerApMac), peerApMac})});
+    }
+    
+    // Returns: {"connectionState":{"duration":"123","desync":"0","ownSK":"1A2","peerSK":"3B4","peerStaMac":"F2","peerApMac":"E3"}}
+    return encode({FPSTR(jsonConnectionState), encode({FPSTR(jsonDuration), duration, FPSTR(jsonDesync), desync, FPSTR(jsonOwnSessionKey), ownSK, FPSTR(jsonPeerSessionKey), peerSK, 
+                   FPSTR(jsonPeerStaMac), peerStaMac, FPSTR(jsonPeerApMac), peerApMac})});
+  }
+    
+  String createEncryptedConnectionInfo(const String &infoHeader, const String &requestNonce, const String &authenticationPassword, const uint64_t ownSessionKey, const uint64_t peerSessionKey)
+  {
+    using namespace JsonTranslator;
+
+    const String q = String('"');
+
+    // Returns: infoHeader{"arguments":{"nonce":"1F2","password":"abc","ownSK":"3B4","peerSK":"1A2"}}
+    return 
+    infoHeader + 
+    encode({FPSTR(jsonArguments), 
+    encodeLiterally({FPSTR(jsonNonce), q + requestNonce + q, 
+                     FPSTR(jsonPassword), q + authenticationPassword + q, 
+                     FPSTR(jsonOwnSessionKey), q + TypeCast::uint64ToString(peerSessionKey) + q,   // Exchanges session keys since it should be valid for the receiver.
+                     FPSTR(jsonPeerSessionKey), q + TypeCast::uint64ToString(ownSessionKey) + q})});
+  }
+  
+  String createEncryptionRequestHmacMessage(const String &requestHeader, const String &requestNonce, const uint8_t *hashKey, const uint8_t hashKeyLength, const uint32_t duration)
+  {
+    using namespace JsonTranslator;
+
+    String mainMessage = requestHeader;
+
+    if(requestHeader == FPSTR(EspnowProtocolInterpreter::temporaryEncryptionRequestHeader))
+    {
+      mainMessage += encode({FPSTR(jsonArguments), encode({FPSTR(jsonDuration), String(duration), FPSTR(jsonNonce), requestNonce})});
+    }
+    else
+    {
+      mainMessage += encode({FPSTR(jsonArguments), encode({FPSTR(jsonNonce), requestNonce})});
+    }
+
+    // We need to have an open JSON object so we can add the HMAC later.
+    mainMessage.remove(mainMessage.length() - 2);
+    mainMessage += ',';
+
+    uint8_t staMac[6] {0};
+    uint8_t apMac[6] {0};
+    String requesterStaApMac = TypeCast::macToString(WiFi.macAddress(staMac)) + TypeCast::macToString(WiFi.softAPmacAddress(apMac));
+    String hmac = MeshCryptoInterface::createMeshHmac(requesterStaApMac + mainMessage, hashKey, hashKeyLength);
+
+    // Returns: requestHeader{"arguments":{"duration":"123","nonce":"1F2","hmac":"3B4"}}
+    return mainMessage + createJsonEndPair(FPSTR(jsonHmac), hmac);
+  }
+}