来自请求 Python 库的 HTTP 请求中缺少主机标头

Question

Python 库生成的 HTTP 请求消息中的HTTP/1.1 强制 Host 头字段在哪里？requestsimport requestsresponse = requests.get("https://www.google.com/")print(response.request.headers)输出：{'User-Agent': 'python-requests/2.22.0', 'Accept-Encoding': 'gzip, deflate', 'Accept': '*/*', 'Connection': 'keep-alive'}

Answer 1

默认情况下，HOST标头不会添加到请求中requests。如果没有明确添加，则将决策委托给底层http模块。

请参阅以下部分http/client.py：

（如果在then is'Host'中明确提供了标题）requests.getskip_hostTrue

    if self._http_vsn == 11:

        # Issue some standard headers for better HTTP/1.1 compliance

        if not skip_host:

            # this header is issued *only* for HTTP/1.1

            # connections. more specifically, this means it is

            # only issued when the client uses the new

            # HTTPConnection() class. backwards-compat clients

            # will be using HTTP/1.0 and those clients may be

            # issuing this header themselves. we should NOT issue

            # it twice; some web servers (such as Apache) barf

            # when they see two Host: headers

            # If we need a non-standard port,include it in the

            # header.  If the request is going through a proxy,

            # but the host of the actual URL, not the host of the

            # proxy.

            netloc = ''

            if url.startswith('http'):

                nil, netloc, nil, nil, nil = urlsplit(url)

            if netloc:

                try:

                    netloc_enc = netloc.encode("ascii")

                except UnicodeEncodeError:

                    netloc_enc = netloc.encode("idna")

                self.putheader('Host', netloc_enc)

            else:

                if self._tunnel_host:

                    host = self._tunnel_host

                    port = self._tunnel_port

                else:

                    host = self.host

                    port = self.port

                try:

                    host_enc = host.encode("ascii")

                except UnicodeEncodeError:

                    host_enc = host.encode("idna")

                # As per RFC 273, IPv6 address should be wrapped with []

                # when used as Host header

                if host.find(':') >= 0:

                    host_enc = b'[' + host_enc + b']'

                if port == self.default_port:

                    self.putheader('Host', host_enc)

                else:

                    host_enc = host_enc.decode("ascii")

                    self.putheader('Host', "%s:%s" % (host_enc, port)) 

因此，'Host'在检查requests发送到服务器的标头时，我们看不到标头。

如果我们向http://httpbin/get发送请求并打印响应，我们可以看到Host标头确实已发送。

import requests

response = requests.get("http://httpbin.org/get")

print('Response from httpbin/get')

print(response.json())

print()

print('response.request.headers')

print(response.request.headers)

输出

Response from httpbin/get

{'args': {}, 'headers': {'Accept': '*/*', 'Accept-Encoding': 'gzip, deflate', 

 'Host': 'httpbin.org', 'User-Agent': 'python-requests/2.20.0'},

 'origin': 'XXXXXX', 'url': 'https://httpbin.org/get'}

response.request.headers

{'User-Agent': 'python-requests/2.20.0', 'Accept-Encoding': 'gzip, deflate', 

 'Accept': '*/*', 'Connection': 'keep-alive'}