CODEWITHSUNDEEP
httpnginxhttp-headershttprequest
cnst
cnst

Reputation: 27218

nginx server name regex when "Host" header has a trailing dot

I've considered potential trailing hostname dot handling in two contexts in nginx, and was curious whether usage in either one is necessary for an entirely correct configuration:

Upvotes: 1

Views: 1584

Answers (1)

cnst
cnst

Reputation: 27218

No, it is not necessary in either context — nginx automatically takes care of the trailing dot, both in the context of the $host variable, as well as the server_name directive, leaving only the $http_host variable with the extra dot (if present in the request).

I believe it is implemented in http/ngx_http_request.c#ngx_http_validate_host:

1925    if (dot_pos == host_len - 1) {
1926        host_len--;
1927    }

It can be verified with the following minimal config:

server {
    listen  [::]:7325;
    server_name ~^(\w*)\.?(example\.com\.?)$;
    return  200 C:$2\tH:$host\tHH:$http_host\tSN:$server_name\n;
}

Running the following tests against nginx/1.2.1:

%printf 'GET / HTTP/1.0\nHost: head.example.com.\n\n' | nc localhost 7325 | fgrep example
C:example.com   H:head.example.com  HH:head.example.com.    SN:~^(\w*)\.?(example\.com\.?)$
%
%printf 'GET http://line.example.com./ HTTP/1.0\n\n' | nc localhost 7325 | fgrep example
C:example.com   H:line.example.com  HH: SN:~^(\w*)\.?(example\.com\.?)$
%
%printf 'GET http://line.example.com./ HTTP/1.0\nHost: head.example.com.\n\n' | nc localhost 7325 | fgrep example
C:example.com   H:line.example.com  HH:head.example.com.    SN:~^(\w*)\.?(example\.com\.?)$
%

Note that neither the regexp capture from within the server_name directive, nor the $host variable, ever has a trailing dot. As such, it is pointless to account for it in above contexts.

Upvotes: 1

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