From: Florian Obser <florian@openbsd.org>
Subject: Re: diff httpd: avoid misleading syslog warnings
To: tech@openbsd.org
Date: Tue, 13 Feb 2024 14:35:47 +0100

On 2024-02-13 13:17 +01, "Carsten Reith" <carsten.reith@t-online.de> wrote:
> Dear all,
>
> Currently httpd writes a misleading error (log_warn)  message to syslog in the following
> scenario:
>
> The user defined the errdoc directive in the httpd.conf.
> The user created custom error pages for some http error codes, let's say
> 404.html.
> The user created a custom generic error page err.html.
>
> Now, if an error occurs _without_ a specific custom error page, httpd
> writes an error message to syslog:
>
> serv1 httpd[23368]: read_errdoc: open: No such file or directory
>
> Then it delivers the custom error page correctly. (or the builtin one,
> in case no custom err.html exists, resulting in another syslog warning.)
>
> The following diff avoids this confusing error message (it is
> misleading as the specific error page is not supposed to exist from a
> user point of view.)
>
> cheers,
>
> Carsten
>
> Index: server_http.c
> ===================================================================
> RCS file: /cvs/src/usr.sbin/httpd/server_http.c,v
> retrieving revision 1.153
> diff -u -p -u -p -r1.153 server_http.c
> --- server_http.c	21 Sep 2022 05:55:18 -0000	1.153
> +++ server_http.c	13 Feb 2024 12:08:49 -0000
> @@ -1766,6 +1766,8 @@ read_errdoc(const char *root, const char
>  
>  	if (asprintf(&path, "%s/%s.html", root, file) == -1)
>  		fatal("asprintf");
> +	if (access(path, R_OK) == -1)
> +		return (NULL);

what do you do if err.html gets deleted between access(2) and open(2)?

>  	if ((fd = open(path, O_RDONLY)) == -1) {
>  		free(path);
>  		log_warn("%s: open", __func__);
>

-- 
In my defence, I have been left unsupervised.