HAProxy 1.5-dev7 attempting to connect to real server port of twice virtual server port

From: Nick Chalk <nick#loadbalancer.org>
Date: Wed, 21 Sep 2011 16:30:05 +0100

Afternoon all.

We have come across an interesting problem with HAProxy 1.5-dev7: with the config below, the proxy attempts to connect to a real server port of twice the virtual server's port.

listen v1

	bind 192.168.69.32:80
	mode http
	balance leastconn
	server backup 127.0.0.1:9081 backup
	option httpclose
	option redispatch
	option abortonclose
	maxconn 40000
	log global
	option httplog
	server r41 192.168.68.41  weight 1  check port 80  inter 2000  rise 2

 fall 3 minconn 0 maxconn 0

In this example, the client's requests to 192.168.69.32:80 are forwarded to 192.168.68.41:160.

A bit of digging in the source has led to the assign_server_address() function in backend.c, in particular the following section:

                 if (target_srv(&s->target)->state & SRV_MAPPORTS) {
                        int base_port;

                        if (!(s->be->options & PR_O_TRANSP) &&
!(s->flags & SN_FRT_ADDR_SET))
                                get_frt_addr(s);



                        /* First, retrieve the port from the incoming

connection */
                        base_port = get_host_port(&s->req->prod->addr.c.to);



                        /* Second, assign the outgoing connection's port */

                        base_port += get_host_port(&s->req->prod->addr.s.to);
                        set_host_port(&s->req->cons->addr.s.to, base_port);
                }

cfg_parse_listen() appears to set the SRV_MAPPORTS flag, as there is no destination port specified in the server directive. The proxy therefore uses the port from s->req->prod->addr.c.to plus s->req->prod->addr.s.to. With the configuration above, both of these structure elements have the value 80, resulting in a destination port of 160.

At that point, I hit a dead end in my understanding of the code. It would appear that either s->req->prod->addr.c.to or s->req->prod->addr.s.to are holding the wrong port value, or one of these structures is being used incorrectly in the sum.

Any pointers for further investigation would be appreciated.

Thanks,
Nick.

-- 
Nick Chalk.

Loadbalancer.org Ltd.
Phone: +44 (0)870 443 8779
http://www.loadbalancer.org/

Received on 2011/09/21 17:30