Value request.META["HTTP_HOST"] was lost

[Pavel Studeník]

I found problem - I hope, that is a bug. I don't know how, but sometimes (one times from ten) the value request.META["HTTP_HOST"] was lost. It's possible? I trust that this value must exist always.

There is report:

===============================================================

Traceback (most recent call last):

  File "/usr/local/lib/python2.6/dist-packages/django/core/handlers/base.py", line 89, in get_response
    response = middleware_method(request)

  File "/var/www/hlplyn_cz/www/./middleware.py", line 18, in process_request
    if not request.META["HTTP_HOST"] in ("www.<doamin>","localhost:8000",):

KeyError: 'HTTP_HOST'


<WSGIRequest
GET:<QueryDict: {}>,
POST:<QueryDict: {}>,
COOKIES:{},
META:{'DOCUMENT_ROOT': '<path>/',
 'GATEWAY_INTERFACE': 'CGI/1.1',
 'HTTP_USER_AGENT': 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10.7; rv:8.0.1) Gecko/20100101 Firefox/8.0.1',
 'PATH_INFO': u'/',
 'PATH_TRANSLATED': '<path>/.run.wsgi/',
 'QUERY_STRING': '',
 'REMOTE_ADDR': '85.17.213.242',
 'REMOTE_PORT': '55876',
 'REQUEST_METHOD': 'GET',
 'REQUEST_URI': 'http://www.DOMENA.NET/',
 'SCRIPT_FILENAME': '<path>/.run.wsgi',
 'SCRIPT_NAME': u'',
 'SERVER_ADDR': '<ip>',
 'SERVER_ADMIN': '[no address given]',
 'SERVER_NAME': '<domain>',
 'SERVER_PORT': '80',
 'SERVER_PROTOCOL': 'HTTP/1.0',
 'SERVER_SIGNATURE': '<address>Apache/2.2.16 (Debian) Server at <domain> Port 80</address>\n',
 'SERVER_SOFTWARE': 'Apache/2.2.16 (Debian)',
 'mod_wsgi.application_group': '<domain>|',
 'mod_wsgi.callable_object': 'application',
 'mod_wsgi.handler_script': '',
 'mod_wsgi.input_chunked': '0',
 'mod_wsgi.listener_host': '',
 'mod_wsgi.listener_port': '80',
 'mod_wsgi.process_group': 'wsgi_<domain>',
 'mod_wsgi.request_handler': 'wsgi-script',
 'mod_wsgi.script_reloading': '1',
 'mod_wsgi.version': (3, 3),
 'wsgi.errors': <mod_wsgi.Log object at 0x7f84a37809b0>,
 'wsgi.file_wrapper': <built-in method file_wrapper of mod_wsgi.Adapter object at 0x7f84a311eeb8>,
 'wsgi.input': <mod_wsgi.Input object at 0x7f84a3780970>,
 'wsgi.multiprocess': True,
 'wsgi.multithread': True,
 'wsgi.run_once': False,
 'wsgi.url_scheme': 'http',
 'wsgi.version': (1, 1)}>

[Claude Paroz]

The Host header is mandatory in HTTP 1.1 (​http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.23), however it might happen that older user agents still use the 1.0 protocol with no Host. You can either choose to return an error (400) if you don't want to support those, or use request.META.get('HTTP_HOST') and handle the None value. Django itself is not responsible to guarantee that HTTP_HOST will be filled in all requests.

[Claude Paroz]

Forgot to mention the get_host method: ​https://docs.djangoproject.com/en/dev/ref/request-response/#django.http.HttpRequest.get_host