monkey patch h11 to enable proxy server usage

[synodriver]

目前,h11的Request没有Host头就会报错。但是，在作为代理的时候，是可以不需要host头部的。

def monkey_patch_h11():
    from h11 import Request, LocalProtocolError
    from h11._util import validate
    from h11._events import request_target_re
    def _validate(self):
        # "A server MUST respond with a 400 (Bad Request) status code to any
        # HTTP/1.1 request message that lacks a Host header field and to any
        # request message that contains more than one Host header field or a
        # Host header field with an invalid field-value."
        # -- https://tools.ietf.org/html/rfc7230#section-5.4
        host_count = 0
        for name, value in self.headers:
            if name == b"host":
                host_count += 1
        if self.http_version == b"1.1" and host_count == 0 and self.method != b"connect":  # CONNECT method without host
            raise LocalProtocolError("Missing mandatory Host: header")
        if host_count > 1:
            raise LocalProtocolError("Found multiple Host: headers")

        validate(request_target_re, self.target, "Illegal target characters")

    Request._validate = _validate

使用以上猴子补丁来搞