HTTP CONNECT proxy.tunnel

HTTP CONNECT method is now supported in HTTP/1 connections.  It's disabled
in all currently existing standard modules.  A new variable $port is added
that contains the port passed by client in HTTP CONNECT.  The $host
variable contains the host part.

A new module ngx_http_tunnel module is added which establishes a tunnel
to a backend.  It supports the newly added HTTP CONNECT method and can be
used to set up an HTTP CONNECT proxy.

As recommended by RFC 9110, proxy target should be restricted to ensure
safe proxying:

: Proxies that support CONNECT SHOULD restrict its use to a limited set
: of known ports or a configurable list of safe request targets.

Example config:

    server {
        listen 8000;

        resolver dns.example.com;

        map $port $tun_port {
            80             1;
            443            1;
        }

        map $host $tun_host {
            hostnames;

            example.com    1;
            *.example.org  1;
        }

        map $tun_port$tun_host $tun {
            11             $host:$port;
        }

        location / {
            tunnel_pass $tun;
        }
    }

Request:

    $ curl -px 127.0.0.1:8000 http://example.com

1 files changed, 3 insertions, 0 deletions

diff --git a/src/http/ngx_http_request.h b/src/http/ngx_http_request.h
index 9407f46ae..c5c8f939f 100644
--- a/src/http/ngx_http_request.h
+++ b/src/http/ngx_http_request.h
@@ -238,6 +238,7 @@ typedef struct {
     ngx_str_t                         passwd;
 
     ngx_str_t                         server;
+    ngx_str_t                         port;
     off_t                             content_length_n;
     time_t                            keep_alive_n;
 
@@ -600,6 +601,8 @@ struct ngx_http_request_s {
     u_char                           *schema_end;
     u_char                           *host_start;
     u_char                           *host_end;
+    u_char                           *port_start;
+    u_char                           *port_end;
 
     unsigned                          http_minor:16;
     unsigned                          http_major:16;