Here’s a well-structured and informative article on the issue:
Ethereum: WebSocket Handshake Declined by Remote Peer
When building blockchain applications, particularly those involving Ethereum (ERC-20 tokens), it’s not uncommon to encounter issues with WebSocket connections, including the handshake. This process is crucial for establishing real-time communication between a client application (e.g., a web interface) and a server or API. In this article, we’ll explore why the WebSocket handshake may be declined by remote peers and provide guidance on troubleshooting and resolving the issue.
What is a WebSocket Handshake?
A WebSocket handshake is a protocol used for establishing a bi-directional communication channel between two parties over the web. It involves several steps:
- Handshake Initiation: The client (e.g., your web interface) sends a
WebSocketconnection request to the server.
- Server Verification: The server verifies the identity of the client and checks for any potential security vulnerabilities.
- Handshake Negotiation: If verification is successful, the client and server negotiate on the WebSocket version and encryption method.
- Connection Establishment: Once agreed upon, the connection is established.
Ethereum’s Specifics
In Ethereum, the WebSocket handshake involves several custom steps:
- ERC-20 Token Connection Request: When a user initiates a WebSocket connection to access an ERC-20 token or smart contract, the client sends a
WebSocketconnection request.
- ERC-20 Token Verification
: The server verifies the identity of the user and checks for any potential security vulnerabilities related to ERC-20 tokens.
- Handshake Negotiation: If verification is successful, the client and server negotiate on the WebSocket version and encryption method using custom keys (e.g.,
x-ecDSA-256).
- Connection Establishment: Once agreed upon, the connection is established.
Why is the WebSocket Handshake Declined?
When encountering issues during the handshake process, there are several potential causes:
- Invalid Server Certificate: The server’s certificate may not match the client’s expected verification criteria.
- Insufficient Trust Anchor: The server may not have a trust anchor (e.g., a list of trusted certificates) that allows it to verify the identity of clients.
- Certificate Validation Error: The validation process for the server’s certificate may fail, causing the handshake to decline.
Troubleshooting Steps
To resolve issues during the WebSocket handshake, follow these steps:
- Verify Server Certificate: Ensure that the server’s certificate matches your expected verification criteria using tools like OpenSSL or Certbot.
- Install Trust Anchor: Install a list of trusted certificates on your server (e.g., the Bearer Trust Anchor) to enable trust anchor verification.
- Configure WebSocket Connection: Review and update your client application code to ensure proper configuration for the custom keys used during the handshake.
Conclusion
Establishing a reliable WebSocket connection with Ethereum requires attention to detail and a thorough understanding of the protocol involved. By following these steps and troubleshooting common issues, you should be able to resolve the WebSocket handshake decline error and successfully establish real-time communication between your client application and server or API.
Remember to regularly review and update your code to ensure compliance with evolving security standards and best practices for blockchain applications.