使用Starscream建立WebSocket连接时出现Invalid HTTP upgrade错误

Hey there, let's work through that "Invalid HTTP upgrade" error you're hitting with your WebSocket connection. After looking over your code, I can spot a couple of critical issues that are almost certainly causing this problem:

1. Wrong HTTP Method for WebSocket Handshake #

WebSocket connections require a GET request for the initial handshake, but you've set request.httpMethod = "POST" in your code. This directly breaks the WebSocket protocol specification, which expects a GET request to trigger the HTTP upgrade to WebSocket.

2. Missing WebSocket Protocol Headers #

While most WebSocket libraries auto-add the mandatory handshake headers, using a POST method would prevent this from working correctly. The required headers for a valid WebSocket upgrade include:

• Upgrade: websocket
• Connection: Upgrade
• Sec-WebSocket-Key (auto-generated by libraries like Starscream)
• Sec-WebSocket-Version: 13

Switching to GET should let your WebSocket class (I’m guessing this is the Starscream library, a popular Swift WebSocket implementation) handle these headers automatically.

3. Verify Your URL Scheme #

Make sure your WebSocket URL uses the correct protocol prefix:

• Use ws:// for unencrypted connections
• Use wss:// for encrypted (SSL/TLS) connections

Avoid http:// or https://—those are for regular HTTP requests, not WebSocket.

Corrected Code Example #

Here’s how to adjust your code to fix these issues:

// Replace with your actual WebSocket URL (ws:// or wss://)
guard let socketUrl = URL(string: "ws://your-server-url.com/websocket-endpoint") else {
    print("Invalid WebSocket URL provided")
    return
}

var request = URLRequest(url: socketUrl)
request.timeoutInterval = 2.0
// WebSocket handshake requires GET method
request.httpMethod = "GET"
// Keep your Authorization header as needed
request.setValue("header", forHTTPHeaderField: "Authorization")

socket = WebSocket(request: request)
socket.delegate = self
socket.connect()

Additional Troubleshooting Tips #

• Check Server Configuration: Ensure your backend server is set up to handle WebSocket upgrade requests. It should accept GET requests on your target endpoint and support the WebSocket protocol.
• Library Version: If you’re using Starscream, make sure you’re on the latest version—older releases might have handshake-related bugs.
• Network Restrictions: Some firewalls or proxies block WebSocket traffic. Test your connection on a different network (like mobile data) to rule this out.

内容的提问来源于stack exchange，提问作者Sandip Gill