From: Rafael Sadowski <rafael@sizeofvoid.org>
Subject: Re: httpd: add timestamps to fastcgi error log
To: tech@openbsd.org
Cc: Claudio Jeker <cjeker@diehard.n-r-g.com>
Date: Mon, 2 Nov 2026 09:58:09 +0100

On Sun Nov 01, 2026 at 06:59:48PM +0100, Rafael Sadowski wrote:
> I don't suppose anyone has ever tried to debug their error logs.
> 
> This diff changes the log from:
> 
> error.cgi: lab test error, GET /cgi-bin/error.cgi
> 
> to:
> 
> 01/Nov/2026:18:53:55 +0100: error.cgi: lab test error, GET /cgi-bin/error.cgi
> 
> Does anyone have a better idea for a syntax? OK?
> 
> Rafael
> 

Following feedback, here is the next iteration. This time, ONLY the
error log, including the format as per "syslogd -Z":

2026-11-02T08:49:40.036Z: error.cgi: lab test error, GET /cgi-bin/error.cgi

I don’t want to change the access log at the moment!

commit 8496842a679db367ba919ba9e4ee1b16565b506f
Author: Rafael Sadowski <rafael@sizeofvoid.org>
Date:   Sun Nov 1 15:18:04 2026 +0100

    httpd: add timestamps to fastcgi error log
    
    When not logging to syslog, prefix FastCGI stderr output with a UTC
    timestamp in the same format syslogd -Z uses.

diff --git a/httpd.h b/httpd.h
index a2defd9..0fbad1b 100644
--- a/httpd.h
+++ b/httpd.h
@@ -696,6 +696,7 @@ int			 server_foreach(int (*)(struct server *,
 	struct server_config *, void *), void *);
 struct server		*server_byname(struct server *);
 struct server		*server_bysocket(struct server *);
+int			 server_current_time(char *, size_t);
 
 SPLAY_PROTOTYPE(client_tree, client, clt_nodes, server_client_cmp);
 
diff --git a/server.c b/server.c
index b32a077..ea53802 100644
--- a/server.c
+++ b/server.c
@@ -1560,4 +1560,26 @@ server_client_cmp(struct client *a, struct client *b)
 	return ((int)a->clt_id - b->clt_id);
 }
 
+int
+server_current_time(char *timestamp, size_t len)
+{
+	struct tm	 tm;
+	struct timeval	 now;
+	size_t		 l;
+	int		 n;
+
+	if (gettimeofday(&now, NULL) == -1)
+		return (-1);
+	if (gmtime_r(&now.tv_sec, &tm) == NULL)
+		return (-1);
+	if ((l = strftime(timestamp, len, "%FT%T", &tm)) == 0)
+		return (-1);
+	n = snprintf(timestamp + l, len - l, ".%03ldZ",
+	    (long)now.tv_usec / 1000);
+	if (n < 0 || (size_t)n >= len - l)
+		return (-1);
+
+	return (0);
+}
+
 SPLAY_GENERATE(client_tree, client, clt_nodes, server_client_cmp);
diff --git a/server_fcgi.c b/server_fcgi.c
index 2428adb..ef58c3f 100644
--- a/server_fcgi.c
+++ b/server_fcgi.c
@@ -85,6 +85,7 @@ int	server_fcgi_writechunk(struct client *);
 int	server_fcgi_getheaders(struct client *);
 int	fcgi_add_param(struct server_fcgi_param *, const char *, const char *,
     struct client *);
+void	server_fcgi_err_log(struct client *);
 
 int
 server_fcgi(struct httpd *env, struct client *clt)
@@ -512,6 +513,32 @@ server_fcgi_error(struct bufferevent *bev, short error, void *arg)
 	server_file_error(bev, error, arg);
 }
 
+void
+server_fcgi_err_log(struct client *clt)
+{
+	char				 tstamp[33];
+	struct server_config		*srv_conf;
+	size_t				 len;
+	char				*msg;
+
+	if ((srv_conf = clt->clt_srv_conf) == NULL)
+		return;
+
+	if ((len = EVBUFFER_LENGTH(clt->clt_srvevb)) == 0)
+		return;
+
+	if ((msg = get_string(EVBUFFER_DATA(clt->clt_srvevb), len)) == NULL)
+		return;
+
+	if ((srv_conf->flags & SRVFLAG_SYSLOG) == 0 &&
+	    server_current_time(tstamp, sizeof(tstamp)) == 0) {
+		server_sendlog(srv_conf, IMSG_LOG_ERROR, "%s: %s", tstamp, msg);
+	} else {
+		server_sendlog(srv_conf, IMSG_LOG_ERROR, "%s", msg);
+	}
+	free(msg);
+}
+
 void
 server_fcgi_read(struct bufferevent *bev, void *arg)
 {
@@ -519,7 +546,6 @@ server_fcgi_read(struct bufferevent *bev, void *arg)
 	struct client			*clt = (struct client *)arg;
 	struct fcgi_record_header	*h;
 	size_t				 len;
-	char				*ptr;
 
 	do {
 		len = bufferevent_read(bev, buf, clt->clt_fcgi.toread);
@@ -561,15 +587,7 @@ server_fcgi_read(struct bufferevent *bev, void *arg)
 		case FCGI_READ_CONTENT:
 			switch (clt->clt_fcgi.type) {
 			case FCGI_STDERR:
-				if (EVBUFFER_LENGTH(clt->clt_srvevb) > 0 &&
-				    (ptr = get_string(
-				     EVBUFFER_DATA(clt->clt_srvevb),
-				     EVBUFFER_LENGTH(clt->clt_srvevb))) !=
-				    NULL) {
-					server_sendlog(clt->clt_srv_conf,
-					    IMSG_LOG_ERROR, "%s", ptr);
-					free(ptr);
-				}
+				server_fcgi_err_log(clt);
 				break;
 			case FCGI_STDOUT:
 				++clt->clt_chunk;