From: Lloyd <ng2d68@proton.me>
Subject: Re: relayd: set User-Agent for HTTP healthchecks
To: Rafael Sadowski <rafael@sizeofvoid.org>
Cc: tech@openbsd.org, Joel Carnat <joel@carnat.net>, Kirill Bychkov <kirby@linklevel.net>
Date: Fri, 27 Feb 2026 18:44:20 +0000

I checked and indeed RELAYD_SERVERNAME is defined in relayd.h.

It would be cleaner IMO to reference that here vs hard-coding.

Regards
Lloyd

Lloyd wrote:

> Personal style preference, but I would define the user-agent in a macro rather than hard-code it in multiple places.
> 
> Doesn't relayd spit out error pages with an identifier string? Perhaps it's already defined elsewhere.
> 
> Regards
> Lloyd
> 
> Rafael Sadowski wrote:
> 
> > Joel Carnat notice that GoToSocial does not like it when we sent no
> > User-Agent and returns an HTTP/418. This simple diff adds User-Agent to
> > all HTTP/HTTPS checks.
> >
> > As I see it, we use "User Agents" in other places (ftp,acme-client...).
> > When I look at all my (aws) load balancers and checks, I get a user
> > agent from all of them.
> >
> > diff --git a/usr.sbin/relayd/parse.y b/usr.sbin/relayd/parse.y
> > index fcdfb8e92e3..44ec18cbcfc 100644
> > --- a/usr.sbin/relayd/parse.y
> > +++ b/usr.sbin/relayd/parse.y
> > @@ -921,7 +921,7 @@ tablecheck	: ICMP			{ table->conf.check = CHECK_ICMP; }
> >  				YYERROR;
> >  			}
> >  			if (asprintf(&table->sendbuf,
> > -			    "HEAD %s HTTP/1.%c\r\n%s\r\n",
> > +			    "HEAD %s HTTP/1.%c\r\nUser-Agent: relayd\r\n%s\r\n",
> >  			    $2, strlen($3) ? '1' : '0', $3) == -1)
> >  				fatal("asprintf");
> >  			free($2);
> > @@ -936,7 +936,7 @@ tablecheck	: ICMP			{ table->conf.check = CHECK_ICMP; }
> >  			}
> >  			table->conf.check = CHECK_HTTP_DIGEST;
> >  			if (asprintf(&table->sendbuf,
> > -			    "GET %s HTTP/1.%c\r\n%s\r\n",
> > +			    "GET %s HTTP/1.%c\r\nUser-Agent: relayd\r\n%s\r\n",
> >  			    $2, strlen($3) ? '1' : '0', $3) == -1)
> >  				fatal("asprintf");
> >  			free($2);
> > diff --git a/usr.sbin/relayd/relayd.conf.5 b/usr.sbin/relayd/relayd.conf.5
> > index 5ae11c5ac01..943926a448a 100644
> > --- a/usr.sbin/relayd/relayd.conf.5
> > +++ b/usr.sbin/relayd/relayd.conf.5
> > @@ -279,6 +279,9 @@ If
> >  is specified, it is used as the
> >  .Dq Host:
> >  header to query a specific hostname at the target host.
> > +A
> > +.Dq User-Agent: relayd
> > +header is always included in the request.
> >  To validate the HTTP return code, use this shell command:
> >  .Bd -literal -offset indent
> >  $ echo -n "HEAD <path> HTTP/1.0\er\en\er\en" | \e
> >
> >