SWI-Prolog -- http_public

Documentation
- Reference manual
- Packages
  - SWI-Prolog HTTP support
    - The HTTP server libraries
      - library(http/http_host): Obtain public server location
        
        http_public_url/2
        
        http_public_host_url/2
        
        http_public_host/4
        
        http_current_host/4

Availability::- use_module(library(http/http_host)).

[det]http_public_host(?Request, -Hostname, -Port, +Options)

Current global host and port of the HTTP server. This is the basis to form absolute address, which we need for redirection based interaction such as the OpenID protocol. Options are:

global(+Bool): If true (default false), try to replace a local hostname by a world-wide accessible name.

This predicate performs the following steps to find the host and port:

Use the settings http:public_host and http:public_port
Use X-Forwarded-Host header, which applies if this server runs behind a proxy.
Use the Host header, which applies for HTTP 1.1 if we are contacted directly.
Use gethostname/1 to find the host and http_current_server/2 to find the port.

Request

is the current request. If it is left unbound, and the request is needed, it is obtained with http_current_request/1.