The real difference between $host and $http_host

The wiki page of “$host” says $host and $host_addr are different only
when there is no “Host” header or the “Host” header is empty. But I
found when “Host” contains port number, $host never contains the port
number while $http_host is equal to the value of “Host” header.

That is, if “Host: foo:8080”, then
$http_host = foo:8080
$host = foo

So in this case, they are different.

Tested in nginx 1.0.3

I want the official confirmation of this difference. And if it’s
confirmed, could you correct the illustration in wiki page?

Thanks.

Posted at Nginx Forum:

Hello!

On Mon, Aug 15, 2011 at 03:30:20AM -0400, speedfirst wrote:

Tested in nginx 1.0.3

I want the official confirmation of this difference.

Yes, $host variable represents host part of a Host header[1].
Moreover, in 0.8.17+ $host will be additionally lowercased. That
is, for

Host: FOO:8080

$host will be “foo” (while $http_host will be “FOO:8080” as it
just reflects the whole header).

Additionally, $host will be set to one from request uri, if
request request used absolute uri (as per RFC2616, section 5.2,
see [2]).

And if it’s
confirmed, could you correct the illustration in wiki page?

Probably wiki as well as docs should say something like “$host
represents http host requested”. The full description above is
clearly a bit too many for just a variable description.

Anyway, feel free to update wiki if you think you know what to
write there.

[1] RFC 2616 - Hypertext Transfer Protocol -- HTTP/1.1
[2] RFC 2616 - Hypertext Transfer Protocol -- HTTP/1.1

Maxim D.