85 lines
3.0 KiB
Python
85 lines
3.0 KiB
Python
import importlib
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from twisted.web.http_headers import Headers
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def import_by_path(path):
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"""
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Given a dotted/colon path, like project.module:ClassName.callable,
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returns the object at the end of the path.
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"""
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module_path, object_path = path.split(":", 1)
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target = importlib.import_module(module_path)
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for bit in object_path.split("."):
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target = getattr(target, bit)
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return target
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def header_value(headers, header_name):
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value = headers[header_name]
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if isinstance(value, list):
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value = value[0]
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return value.decode("utf-8")
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def parse_x_forwarded_for(
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headers,
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address_header_name="X-Forwarded-For",
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port_header_name="X-Forwarded-Port",
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proto_header_name="X-Forwarded-Proto",
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original_addr=None,
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original_scheme=None,
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):
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"""
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Parses an X-Forwarded-For header and returns a host/port pair as a list.
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@param headers: The twisted-style object containing a request's headers
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@param address_header_name: The name of the expected host header
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@param port_header_name: The name of the expected port header
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@param proto_header_name: The name of the expected proto header
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@param original_addr: A host/port pair that should be returned if the headers are not in the request
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@param original_scheme: A scheme that should be returned if the headers are not in the request
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@return: A list containing a host (string) as the first entry and a port (int) as the second.
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"""
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if not address_header_name:
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return original_addr, original_scheme
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# Convert twisted-style headers into dicts
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if isinstance(headers, Headers):
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headers = dict(headers.getAllRawHeaders())
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# Lowercase all header names in the dict
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headers = {name.lower(): values for name, values in headers.items()}
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# Make sure header names are bytes (values are checked in header_value)
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assert all(isinstance(name, bytes) for name in headers.keys())
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address_header_name = address_header_name.lower().encode("utf-8")
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result_addr = original_addr
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result_scheme = original_scheme
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if address_header_name in headers:
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address_value = header_value(headers, address_header_name)
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if "," in address_value:
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address_value = address_value.split(",")[0].strip()
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result_addr = [address_value, 0]
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if port_header_name:
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# We only want to parse the X-Forwarded-Port header if we also parsed the X-Forwarded-For
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# header to avoid inconsistent results.
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port_header_name = port_header_name.lower().encode("utf-8")
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if port_header_name in headers:
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port_value = header_value(headers, port_header_name)
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try:
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result_addr[1] = int(port_value)
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except ValueError:
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pass
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if proto_header_name:
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proto_header_name = proto_header_name.lower().encode("utf-8")
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if proto_header_name in headers:
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result_scheme = header_value(headers, proto_header_name)
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return result_addr, result_scheme
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