Add support for reloading configuration on SIGHUP

Fixes #323.

configlexer.lex

@@ -267,6 +267,7 @@ rrl-ipv4-prefix-length{COLON}	{ LEXOUT(("v(%s) ", yytext)); return VAR_RRL_IPV4_
 rrl-ipv6-prefix-length{COLON}	{ LEXOUT(("v(%s) ", yytext)); return VAR_RRL_IPV6_PREFIX_LENGTH;}
 rrl-whitelist-ratelimit{COLON}	{ LEXOUT(("v(%s) ", yytext)); return VAR_RRL_WHITELIST_RATELIMIT;}
 rrl-whitelist{COLON}	{ LEXOUT(("v(%s) ", yytext)); return VAR_RRL_WHITELIST;}
+reload-config{COLON}	{ LEXOUT(("v(%s) ", yytext)); return VAR_RELOAD_CONFIG; }
 zonefiles-check{COLON}	{ LEXOUT(("v(%s) ", yytext)); return VAR_ZONEFILES_CHECK;}
 zonefiles-write{COLON}	{ LEXOUT(("v(%s) ", yytext)); return VAR_ZONEFILES_WRITE;}
 dnstap{COLON}		{ LEXOUT(("v(%s) ", yytext)); return VAR_DNSTAP;}

configparser.y

@@ -115,6 +115,7 @@ struct component {
 %token VAR_MINIMAL_RESPONSES
 %token VAR_CONFINE_TO_ZONE
 %token VAR_REFUSE_ANY
+%token VAR_RELOAD_CONFIG
 %token VAR_ZONEFILES_CHECK
 %token VAR_ZONEFILES_WRITE
 %token VAR_RRL_SIZE
@@ -445,6 +446,8 @@ server_option:
       cfg_parser->opt->rrl_whitelist_ratelimit = (size_t)$2;
 #endif
     }
+  | VAR_RELOAD_CONFIG boolean
+    { cfg_parser->opt->reload_config = $2; }
   | VAR_ZONEFILES_CHECK boolean
     { cfg_parser->opt->zonefiles_check = $2; }
   | VAR_ZONEFILES_WRITE number

nsd.conf.5.in

@@ -458,6 +458,9 @@ the response with one RRset. Popular and not large types, like A, AAAA and
 MX are preferred, and large types, like DNSKEY and RRSIG are picked with a
 lower preference than other types. This makes the response smaller.
 .TP
+.B reload\-config:\fR <yes or no>
+Reload configuration file and update TSIG keys and zones on SIGHUP.
+Default is no.
 .B zonefiles\-check:\fR <yes or no>
 Make NSD check the mtime of zone files on start and sighup.  If you
 disable it it starts faster (less disk activity in case of a lot of zones).
@@ -468,6 +471,7 @@ regardless of this option.
 Write updated secondary zones to their zonefile every N seconds.  If the
 zone or pattern's "zonefile" option is set to "" (empty string), no zonefile
 is written. The default is 3600 (1 hour).
+.TP
 .\" rrlstart
 .TP
 .B rrl\-size:\fR <numbuckets>

nsd.conf.sample.in

@@ -216,6 +216,9 @@ server:
 	# default is 3600.
 	# zonefiles-write: 3600
 
+	# Reload nsd.conf and update TSIG keys and zones on SIGHUP.
+	# reload-config: no
+
 	# RRLconfig
 	# Response Rate Limiting, size of the hashtable. Default 1000000.
 	# rrl-size: 1000000

options.c

@@ -137,6 +137,7 @@ nsd_options_create(region_type* region)
 	opt->dnstap_log_auth_query_messages = 0;
 	opt->dnstap_log_auth_response_messages = 0;
 #endif
+	opt->reload_config = 0;
 	opt->zonefiles_check = 1;
 	opt->zonefiles_write = ZONEFILES_WRITE_INTERVAL;
 	opt->xfrd_reload_timeout = 1;

options.h

@@ -116,6 +116,7 @@ struct nsd_options {
 	const char* zonelistfile;
 	const char* nsid;
 	int xfrd_reload_timeout;
+	int reload_config;
 	int zonefiles_check;
 	int zonefiles_write;
 	int log_time_ascii;

remote.c

@@ -71,7 +71,6 @@
 #else
 #  include "mini_event.h"
 #endif
-#include "remote.h"
 #include "util.h"
 #include "xfrd.h"
 #include "xfrd-catalog-zones.h"
@@ -81,6 +80,7 @@
 #include "options.h"
 #include "difffile.h"
 #include "ipc.h"
+#include "remote.h"
 
 #ifdef HAVE_SYS_TYPES_H
 #  include <sys/types.h>
@@ -2038,6 +2038,46 @@ do_repattern(RES* ssl, xfrd_state_type* xfrd)
 	region_destroy(region);
 }
 
+static void print_cfg_err(void *unused, const char *message)
+{
+	(void)unused;
+	log_msg(LOG_ERR, "%s", message);
+}
+
+/* mostly identical to do_repattern */
+void xfrd_reload_config(xfrd_state_type *xfrd)
+{
+	const char *chrootdir = xfrd->nsd->chrootdir;
+	const char *file = xfrd->nsd->options->configfile;
+
+	if (chrootdir && !file_inside_chroot(file, chrootdir))
+	{
+		log_msg(LOG_ERR, "%s is not relative to %s: %s",
+			xfrd->nsd->options->configfile, xfrd->nsd->chrootdir,
+			"chroot prevents reread of config");
+		goto error_chroot;
+	}
+
+	region_type *region = region_create(xalloc, free);
+	struct nsd_options *options = nsd_options_create(region);
+
+	if (!parse_options_file(
+		options, file, print_cfg_err, NULL, xfrd->nsd->options))
+	{
+		goto error_parse;
+	}
+
+	repat_keys(xfrd, options);
+	repat_patterns(xfrd, options); /* adds/deletes zones too */
+	repat_options(xfrd, options);
+	zonestat_inc_ifneeded(xfrd);
+
+error_parse:
+	region_destroy(region);
+error_chroot:
+	return;
+}
+
 /** do the serverpid command: printout pid of server process */
 static void
 do_serverpid(RES* ssl, xfrd_state_type* xfrd)

remote.h

@@ -101,4 +101,6 @@ void daemon_remote_attach(struct daemon_remote* rc, struct xfrd_state* xfrd);
  */
 int create_local_accept_sock(const char* path, int* noproto);
 
+void xfrd_reload_config(struct xfrd_state *xfrd);
+
 #endif /* DAEMON_REMOTE_H */

tpkg/reload-config.tdir/example.com.zone

@@ -0,0 +1,4 @@
+@ IN SOA ns1.example.com. hostmaster 2024080900 1800 900 604800 86400
+  IN NS ns1.example.com.
+  IN NS ns2.example.com.
+  IN A 192.0.2.1

tpkg/reload-config.tdir/example.net.zone

@@ -0,0 +1,4 @@
+@ IN SOA ns1.example.net. hostmaster 2024090900 1800 900 604800 86400
+  IN NS ns1.example.net.
+  IN NS ns2.example.net.
+  IN A 192.0.2.2

tpkg/reload-config.tdir/reload-config.1.conf

@@ -0,0 +1,13 @@
+server:
+	xfrdfile: "xfrd.state"
+	logfile: "/dev/stderr"
+	zonesdir: ""
+	username: ""
+	chroot: ""
+	verbosity: 1
+	ip-address: 127.0.0.1
+	reload-config: yes
+
+zone:
+	name: example.com
+	zonefile: example.com.zone

tpkg/reload-config.tdir/reload-config.2.conf

@@ -0,0 +1,17 @@
+server:
+	xfrdfile: "xfrd.state"
+	logfile: "/dev/stderr"
+	zonesdir: ""
+	username: ""
+	chroot: ""
+	verbosity: 1
+	ip-address: 127.0.0.1
+	reload-config: yes
+
+zone:
+	name: example.com
+	zonefile: example.com.zone
+
+zone:
+	name: example.net
+	zonefile: example.net.zone

tpkg/reload-config.tdir/reload-config.dsc

@@ -0,0 +1,16 @@
+BaseName: reload-config
+Version: 1.0
+Description: Test reread of nsd.conf on SIGHUP
+CreationDate: Fri Aug  9 13:47:00 CEST 2024
+Maintainer: Jeroen Koekkoek
+Category:
+Component:
+CmdDepends:
+Depends: 0000_nsd-compile.tpkg
+Help:
+Pre: reload-config.pre
+Post: reload-config.post
+Test: reload-config.test
+AuxFiles:
+Passed:
+Failure:

tpkg/reload-config.tdir/reload-config.post

@@ -0,0 +1,19 @@
+# #-- reload-config.post --#
+# source the master var file when it's there
+[ -f ../.tpkg.var.master ] && source ../.tpkg.var.master
+# source the test var file when it's there
+[ -f .tpkg.var.test ] && source .tpkg.var.test
+#
+# do your teardown here
+. ../common.sh
+
+cat nsd.log
+
+rm -f nsd.log
+rm -f xfrd.state
+rm -f nsd.zonelist
+
+if test -f $NSD_PID; then
+	# the test must have failed
+	kill_pid `cat $NSD_PID`
+fi

tpkg/reload-config.tdir/reload-config.pre

@@ -0,0 +1,16 @@
+# #-- reload-config.pre --#
+# source the master var file when it's there
+[ -f ../.tpkg.var.master ] && source ../.tpkg.var.master
+# use .tpkg.var.test for in test variable passing
+[ -f .tpkg.var.test ] && source .tpkg.var.test
+. ../common.sh
+
+# start NSD
+get_random_port 1
+NSD_PORT=$RND_PORT
+
+NSD_PID="nsd.pid.$$"
+
+# share the vars
+echo "export NSD_PORT=$NSD_PORT" >> .tpkg.var.test
+echo "export NSD_PID=$NSD_PID" >> .tpkg.var.test

tpkg/reload-config.tdir/reload-config.test

@@ -0,0 +1,37 @@
+# #-- reload-config.test --#
+# source the master var file when it's there
+[ -f ../.tpkg.var.master ] && source ../.tpkg.var.master
+# use .tpkg.var.test for in test variable passing
+[ -f .tpkg.var.test ] && source .tpkg.var.test
+. ../common.sh
+
+NSD="../../nsd"
+
+cp reload-config.1.conf nsd.conf
+$NSD -p $NSD_PORT -P $NSD_PID -V 5 -c nsd.conf > nsd.log 2>&1
+wait_nsd_up nsd.log
+
+dig @127.0.0.1 -p $NSD_PORT example.com. SOA | tee result
+if ! grep hostmaster.example.com result; then
+	echo "zone example.com should be available" >&2
+	exit 1
+fi
+
+dig @127.0.0.1 -p $NSD_PORT example.net. SOA | tee result
+if grep hostmaster.example.net result; then
+	echo "zone example.net should not be available" >&2
+	exit 1
+fi
+
+cp reload-config.2.conf nsd.conf
+kill -SIGHUP $(head -n1 ${NSD_PID})
+
+wait_logfile nsd.log "zone example.net read"
+
+dig @127.0.0.1 -p $NSD_PORT example.net. SOA | tee result
+if ! grep hostmaster.example.net result; then
+	echo "zone example.net should be available" >&2
+	exit 1
+fi
+
+exit 0

xfrd.c

@@ -272,6 +272,9 @@ xfrd_sig_process(void)
 	} else if(xfrd->nsd->signal_hint_reload_hup) {
 		log_msg(LOG_WARNING, "SIGHUP received, reloading...");
 		xfrd->nsd->signal_hint_reload_hup = 0;
+		if(xfrd->nsd->options->reload_config) {
+			xfrd_reload_config(xfrd);
+		}
 		if(xfrd->nsd->options->zonefiles_check) {
 			task_new_check_zonefiles(xfrd->nsd->task[
 				xfrd->nsd->mytask], xfrd->last_task, NULL);
@@ -316,6 +319,7 @@ xfrd_main(void)
 	xfrd->shutdown = 0;
 	while(!xfrd->shutdown)
 	{
+		/* xfrd_sig_process takes care of reading zones on SIGHUP */
 		xfrd_process_catalog_producer_zones();
 		xfrd_process_catalog_consumer_zones();
 		/* process activated zones before blocking in select again */