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？requests

import requests

response = 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 requestsresponse = 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'}