XMLSyntaxError when server response starts with whitespace before XML declaration

[kurujega]

Description

The decode_xml method in api.py fails with XMLSyntaxError: XML declaration allowed only at the start of the document when the server prepends whitespace (e.g., newlines) before the <?xml ...?> declaration. This happens with some BroadWorks servers.

Root Cause

lxml.etree.fromstring strictly requires the XML declaration at position 0. Servers may send responses starting with whitespace, causing the error:

lxml.etree.XMLSyntaxError: XML declaration allowed only at the start of the document, line 2, column 6

Example problematic response (starts with newline before XML):

\n<?xml version="1.0" encoding="ISO-8859-1"?><BroadsoftDocument xmlns="C" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" protocol="OCI"><sessionId xmlns="">session-id-here</sessionId><command xmlns="" xsi:type="SomeResponseType">...</command></BroadsoftDocument>\n

Proposed Fix

Strip leading whitespace in decode_xml before parsing:

# In api.py, decode_xml method
if isinstance(xml, (bytes, bytearray)):
    xml = xml.lstrip()
elif isinstance(xml, str):
    xml = xml.lstrip()

Steps to Reproduce

1. Connect to a BroadWorks server that sends whitespace-prefixed responses.
2. Call api.command("UserGetRegistrationListRequest", user_id="some_id").
3. Observe the XMLSyntaxError.

Environment

• broadworks_ocip version: 3.0.0
• Python version: 3.9
• Server: BroadWorks OCI-P