I want to use LSP(Language Server Protocol) in local IDE(VScode) to get line number of specific function

Question

(First of all, I'm not aware of concept of LSP server in VScode) I want to get the line number of specific function in the local project in IDE.

I'm using mac m2 / Vscode.

I tried 'sudo lsof -iTCP -sTCP:LISTEN -nP | grep :49421' and got 'Code\x20H 4056 123412 42u IPv4 0x93bc3373368d4b7d 0t0 TCP 127.0.0.1:49421 (LISTEN)'. It seems 49421 port is local LSP server in VScode.

I sent request by code below, and doesn't get answer with time running.

import json
import socket

def send_lsp_request(sock, request):
    request_str = json.dumps(request)
    content_length = len(request_str.encode('utf-8'))
    full_message = f"Content-Length: {content_length}\r\n\r\n{request_str}"
    print(f"Sending: {full_message}")  # Logging the request being sent
    sock.sendall(full_message.encode('utf-8'))

def receive_lsp_response(sock):
    headers = ''
    while '\r\n\r\n' not in headers:
        headers += sock.recv(1).decode('utf-8')

    content_length = 0
    for header in headers.split('\r\n'):
        if header.startswith('Content-Length'):
            content_length = int(header.split(': ')[1])
            break

    content = sock.recv(content_length).decode('utf-8')
    print(f"Received: {content}")  # Logging the received response
    return json.loads(content)

# Adjust the timeout as needed
TIMEOUT_SECONDS = 10


def receive_lsp_response(sock):
    """
    Receives a response from the LSP server via a socket.
    Parameters:
        sock (socket.socket): The socket connected to the server.
    Returns:
        dict: The parsed LSP response.
    """
    # Read headers
    headers = ''
    while '\r\n\r\n' not in headers:
        headers += sock.recv(1).decode('utf-8')

    # Extract content length
    content_length = 0
    for header in headers.split('\r\n'):
        if header.startswith('Content-Length'):
            content_length = int(header.split(': ')[1])
            break

    # Read the content
    content = sock.recv(content_length).decode('utf-8')

    return json.loads(content)

# Example LSP initialize request
initialize_request = {
    "jsonrpc": "2.0",
    "id": 1,
    "method": "initialize",
    "params": {
        "processId": None,
        "rootUri": "file:///Path/to/project/folder",
        "capabilities": {},
    }
}

# Example LSP document symbol request
document_symbol_request = {
    "jsonrpc": "2.0",
    "id": 2,
    "method": "textDocument/documentSymbol",
    "params": {
        "textDocument": {
            "uri": "file:///Path/to/student.py"
        }
    }
}
# Connect to the LSP server
with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
    s.settimeout(TIMEOUT_SECONDS)  # Setting a timeout for socket operations
    try:
        s.connect(('127.0.0.1', 49421))
        
        # Initialize request (make sure this matches your LSP server's requirements)
        send_lsp_request(s, initialize_request)
        response = receive_lsp_response(s)
        print("Initialize Response:", json.dumps(response, indent=4))

        # Document symbol request (adjust as needed)
        send_lsp_request(s, document_symbol_request)
        response = receive_lsp_response(s)
        print("Document Symbol Response:", json.dumps(response, indent=4))

    except socket.timeout:
        print("The request timed out")
    except Exception as e:
        print(f"An error occurred: {e}")
        

Expected answers are such as

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": [
    {
      "name": "MyClass",
      "kind": 5,  // Class
      "range": {
        "start": { "line": 0, "character": 0 },
        "end": { "line": 10, "character": 1 }
      },
      "children": [
        {
          "name": "myFunction",
          "kind": 6,  // Function
          "range": {
            "start": { "line": 2, "character": 4 },
            "end": { "line": 4, "character": 5 }
          }
        }
      ]
    }
  ]
}