messageHandler function

Future<void> messageHandler(String jwe, String mnemonic, String did, InfraDIDCommAgent agent, bool didAuthCallback(String peerDID)?, dynamic didConnectedCallback(String peerDID)?, dynamic didAuthFailedCallback(String peerDID)?, Future<Map<String, dynamic>> vpRequestCallback(List<RequestVC> requestVCs, String challenge)?, bool vpVerifyCallback(Map<String, dynamic> vp)?, dynamic vpSubmitResCallback(SubmitVPResponseMessage message)?, dynamic vpSubmitLaterResCallback(SubmitVPLaterResponseMessage message)?, dynamic vpRejectCallback(RejectRequestVPMessage message)?,)

Handles incoming messages and performs necessary actions based on the message type.

The messageHandler function takes in the following parameters:

• jwe: The JWE (JSON Web Encryption) string representing the incoming message.
• mnemonic: The mnemonic string used for key generation.
• did: The DID (Decentralized Identifier) string.
• agent: An instance of the InfraDIDCommAgent class representing the agent.
• didAuthCallback: An optional callback function that is called when a DID Auth message is received.
• didConnectedCallback: An optional callback function that is called when a DID Connected message is received.
• didAuthFailedCallback: An optional callback function that is called when a DID Auth Failed message is received.

The messageHandler function handles different types of messages based on the algorithm specified in the JWE header. If the algorithm is "ECDH-ES", it handles the DIDAuthInit message and sends a DID Auth message if successful. If the algorithm is "dir", it handles both DIDAuth and DIDConnected messages.

Throws an exception if an error occurs during message handling.

Implementation

Future<void> messageHandler(
  String jwe,
  String mnemonic,
  String did,
  InfraDIDCommAgent agent,
  bool Function(String peerDID)? didAuthCallback,
  Function(String peerDID)? didConnectedCallback,
  Function(String peerDID)? didAuthFailedCallback,
  Future<Map<String, dynamic>> Function(
    List<RequestVC> requestVCs,
    String challenge,
  )? vpRequestCallback,
  bool Function(Map<String, dynamic> vp)? vpVerifyCallback,
  Function(SubmitVPResponseMessage message)? vpSubmitResCallback,
  Function(SubmitVPLaterResponseMessage message)? vpSubmitLaterResCallback,
  Function(RejectRequestVPMessage message)? vpRejectCallback,
) async {
  try {
    Map<String, dynamic> header = extractJWEHeader(jwe);
    String alg = header["alg"];
    if (alg == "ECDH-ES") {
      // Handle DIDAuthInit Message
      Map<String, dynamic> epk = header["epk"];
      List<int> privatekey = await privateKeyFromUri(mnemonic);
      Map<String, dynamic> x25519JwkPrivateKey =
          await x25519JwkFromEd25519PrivateKey(privatekey);
      List<int> sharedKey = await makeSharedKey(
        privateKeyfromX25519Jwk(x25519JwkPrivateKey),
        publicKeyfromX25519Jwk(epk),
      );
      String jwsFromJwe = await decryptJWE(jwe, jwkFromSharedKey(sharedKey));
      var payload = decodeJWS(jwsFromJwe);
      String fromDID = payload["from"];
      String fromAddress = fromDID.split(":").last;
      List<int> fromPublicKey = publicKeyFromAddress(fromAddress);
      Map<String, dynamic> jwsPayload =
          verifyJWS(jwsFromJwe, hex.encode(fromPublicKey));
      agent.peerInfo = {
        "did": jwsPayload["from"],
        "socketId": jwsPayload["body"]["socketId"],
      };
      agent.isReceivedDIDAuthInit = true;
      // If Success, Send DID Auth Message
      if (didAuthCallback != null) didAuthCallback(fromDID);
      sendDIDAuthMessage(mnemonic, jwsPayload, agent);
    }
    if (alg == "dir") {
      // Handle DIDAuth && DIDConnected Message
      List<int> privatekey = await privateKeyFromUri(mnemonic);
      Map<String, dynamic> x25519JwkPrivateKey =
          await x25519JwkFromEd25519PrivateKey(privatekey);
      if (agent.peerInfo.containsKey("did")) {
        String? fromDID = agent.peerInfo["did"];
        String fromAddress = fromDID!.split(":").last;
        List<int> fromPublicKey = publicKeyFromAddress(fromAddress);
        Map<String, dynamic> x25519JwkPublicKey =
            x25519JwkFromEd25519PublicKey(fromPublicKey);

        List<int> sharedKey = await makeSharedKey(
          privateKeyfromX25519Jwk(x25519JwkPrivateKey),
          publicKeyfromX25519Jwk(x25519JwkPublicKey),
        );
        String jwsFromJwe = await decryptJWE(jwe, jwkFromSharedKey(sharedKey));
        Map<String, dynamic> jwsPayload =
            verifyJWS(jwsFromJwe, hex.encode(fromPublicKey));

        if (jwsPayload["type"] == "DIDAuth") {
          // If Success, Send DID Connected Message
          if (didAuthCallback != null) didAuthCallback(fromDID);
          sendDIDConnectedMessage(
            mnemonic,
            jwsPayload,
            agent,
          );
          if (agent.role == "VERIFIER") {
            agent.isDIDConnected = true;
          }
        }
        if (jwsPayload["type"] == "DIDConnected") {
          print("DIDConnected Message Received");
          if (didConnectedCallback != null) didConnectedCallback(fromDID);
          agent.isDIDConnected = true;
          if (agent.role == "VERIFIER") {
            sendDIDConnectedMessage(
              mnemonic,
              jwsPayload,
              agent,
            );
          }
        }
        if (jwsPayload["type"] == "DIDAuthFailed") {
          if (didAuthFailedCallback != null) didAuthFailedCallback(fromDID);
          print("DIDAuthFailed Message Received");
          agent.disconnect();
        }
        if (jwsPayload["type"] == "VPReq") {
          print("VPRequestMessage Message Received");
          if (vpRequestCallback != null) {
            Map<String, dynamic> result = await vpRequestCallback(
              (jwsPayload["body"]["vcRequirements"] as List<dynamic>)
                  .map<RequestVC>((vc) => RequestVC.fromJson(vc))
                  .toList(),
              jwsPayload["body"]["challenge"],
            );
            var status = result["status"] as String;
            if (status == VPRequestResponseType.submit.name) {
              var vp = result["vp"] as String;
              await sendSubmitVPMessage(
                mnemonic,
                did,
                agent,
                VPRequestMessage.fromJson(jwsPayload),
                vp,
              );
            } else if (status == VPRequestResponseType.reject.name) {
              var reason = result.containsKey("reason")
                  ? result["reason"] as String
                  : "Rejected";

              await sendRejectRequestVPMessage(
                mnemonic,
                did,
                agent,
                VPRequestMessage.fromJson(jwsPayload),
                reason,
              );
            } else if (status == VPRequestResponseType.submitLater.name) {
              await sendSubmitVPLaterMessage(
                mnemonic,
                did,
                agent,
                VPRequestMessage.fromJson(jwsPayload),
              );
            }
          }
        }
        if (jwsPayload["type"] == "VPSubmit") {
          bool isVerified = await verifyVP(
            jwsPayload["body"]["vp"],
            agent.vpChallenge,
          );

          if (vpVerifyCallback != null) {
            String jsonStringVP =
                utf8.decode(base64Url.decode(jwsPayload["body"]["vp"]));
            Map<String, dynamic> vp = json.decode(jsonStringVP);

            bool customVerification = vpVerifyCallback(vp);
            if (!customVerification) {
              isVerified = false;
            }
          }

          await sendSubmitVPResponseMessage(
            mnemonic,
            did,
            agent,
            SubmitVPMessage.fromJson(jwsPayload),
            isVerified,
          );
        }
        if (jwsPayload["type"] == "VPSubmitRes") {
          print("SubmitVPRes Message Received");
          if (vpSubmitResCallback != null) {
            vpSubmitResCallback(SubmitVPResponseMessage.fromJson(jwsPayload));
          }
        }
        if (jwsPayload["type"] == "VPReqReject") {
          if (vpRejectCallback != null) {
            vpRejectCallback(
              RejectRequestVPMessage.fromJson(jwsPayload),
            );
          }
          await sendRejectRequestVPResponseMessage(
            mnemonic,
            did,
            agent,
            RejectRequestVPMessage.fromJson(jwsPayload),
          );
        }
        if (jwsPayload["type"] == "VPReqRejectRes") {
          print("RejectReqVPRes Message Received");
        }
        if (jwsPayload["type"] == "VPSubmitLater") {
          await sendSubmitVPLaterResponseMessage(
            mnemonic,
            did,
            agent,
            SubmitVPLaterMessage.fromJson(jwsPayload),
            agent.vpLaterCallbackEndpoint,
          );
        }
        if (jwsPayload["type"] == "VPSubmitLaterRes") {
          print("SubmitVPLaterRes Message Received");
          if (vpSubmitLaterResCallback != null) {
            vpSubmitLaterResCallback(
              SubmitVPLaterResponseMessage.fromJson(jwsPayload),
            );
          }
        }
      }
    }
  } catch (e) {
    sendDIDAuthFailedMessage(mnemonic, did, agent);
    agent.disconnect();
    throw Exception("Error in message handling: $e");
  }
}