- Fix #4112: Fix that unbound-anchor -f /etc/resolv.conf will not pass

if DNSSEC is not enabled.  New option -R allows fallback from
  resolv.conf to direct queries.


git-svn-id: file:///svn/unbound/trunk@4770 be551aaa-1e26-0410-a405-d3ace91eadb9

doc/Changelog

@@ -1,3 +1,8 @@
+4 July 2018: Wouter
+	- Fix #4112: Fix that unbound-anchor -f /etc/resolv.conf will not pass
+	  if DNSSEC is not enabled.  New option -R allows fallback from
+	  resolv.conf to direct queries.
+
 3 July 2018: Wouter
 	- Better documentation for unblock-lan-zones and insecure-lan-zones
 	  config statements.

doc/unbound-anchor.8.in

@@ -109,6 +109,11 @@ It does so, because the tool when used for bootstrapping the recursive
 resolver, cannot use that recursive resolver itself because it is bootstrapping
 that server.
 .TP
+.B \-R
+Allow fallback from \-f resolv.conf file to direct root servers query.
+It allows you to prefer local resolvers, but fallback automatically
+to direct root query if they do not respond or do not support DNSSEC.
+.TP
 .B \-v
 More verbose. Once prints informational messages, multiple times may enable
 large debug amounts (such as full certificates or byte\-dumps of downloaded

smallapp/unbound-anchor.c

@@ -192,9 +192,10 @@ usage(void)
 	printf("-n name		signer's subject emailAddress, default %s\n", P7SIGNER);
 	printf("-4		work using IPv4 only\n");
 	printf("-6		work using IPv6 only\n");
-	printf("-f resolv.conf	use given resolv.conf to resolve -u name\n");
-	printf("-r root.hints	use given root.hints to resolve -u name\n"
+	printf("-f resolv.conf	use given resolv.conf\n");
+	printf("-r root.hints	use given root.hints\n"
 		"		builtin root hints are used by default\n");
+	printf("-R		fallback from -f to root query on error\n");
 	printf("-v		more verbose\n");
 	printf("-C conf		debug, read config\n");
 	printf("-P port		use port for https connect, default 443\n");
@@ -1920,8 +1921,7 @@ static int
 do_certupdate(const char* root_anchor_file, const char* root_cert_file,
 	const char* urlname, const char* xmlname, const char* p7sname,
 	const char* p7signer, const char* res_conf, const char* root_hints,
-	const char* debugconf, int ip4only, int ip6only, int port,
-	struct ub_result* dnskey)
+	const char* debugconf, int ip4only, int ip6only, int port)
 {
 	STACK_OF(X509)* cert;
 	BIO *xml, *p7s;
@@ -1961,7 +1961,6 @@ do_certupdate(const char* root_anchor_file, const char* root_cert_file,
 #ifndef S_SPLINT_S
 	sk_X509_pop_free(cert, X509_free);
 #endif
-	ub_resolve_free(dnskey);
 	ip_list_free(ip_list);
 	return 1;
 }
@@ -2199,16 +2198,33 @@ probe_date_allows_certupdate(const char* root_anchor_file)
 	return 0;
 }
 
+static struct ub_result *
+fetch_root_key(const char* root_anchor_file, const char* res_conf,
+	const char* root_hints, const char* debugconf,
+	int ip4only, int ip6only)
+{
+	struct ub_ctx* ctx;
+	struct ub_result* dnskey;
+
+	ctx = create_unbound_context(res_conf, root_hints, debugconf,
+		ip4only, ip6only);
+	add_5011_probe_root(ctx, root_anchor_file);
+	dnskey = prime_root_key(ctx);
+	ub_ctx_delete(ctx);
+	return dnskey;
+}
+
 /** perform the unbound-anchor work */
 static int
 do_root_update_work(const char* root_anchor_file, const char* root_cert_file,
 	const char* urlname, const char* xmlname, const char* p7sname,
 	const char* p7signer, const char* res_conf, const char* root_hints,
-	const char* debugconf, int ip4only, int ip6only, int force, int port)
+	const char* debugconf, int ip4only, int ip6only, int force,
+	int res_conf_fallback, int port)
 {
-	struct ub_ctx* ctx;
 	struct ub_result* dnskey;
 	int used_builtin = 0;
+	int rcode;
 
 	/* see if builtin rootanchor needs to be provided, or if
 	 * rootanchor is 'revoked-trust-point' */
@@ -2217,12 +2233,22 @@ do_root_update_work(const char* root_anchor_file, const char* root_cert_file,
 
 	/* make unbound context with 5011-probe for root anchor,
 	 * and probe . DNSKEY */
-	ctx = create_unbound_context(res_conf, root_hints, debugconf,
-		ip4only, ip6only);
-	add_5011_probe_root(ctx, root_anchor_file);
-	dnskey = prime_root_key(ctx);
-	ub_ctx_delete(ctx);
-	
+	dnskey = fetch_root_key(root_anchor_file, res_conf,
+		root_hints, debugconf, ip4only, ip6only);
+	rcode = dnskey->rcode;
+
+	if (res_conf_fallback && res_conf && !dnskey->secure) {
+		if (verb) printf("%s failed, retrying direct\n", res_conf);
+		ub_resolve_free(dnskey);
+		/* try direct query without res_conf */
+		dnskey = fetch_root_key(root_anchor_file, NULL,
+			root_hints, debugconf, ip4only, ip6only);
+		if (rcode != 0 && dnskey->rcode == 0) {
+			res_conf = NULL;
+			rcode = 0;
+		}
+	}
+
 	/* if secure: exit */
 	if(dnskey->secure && !force) {
 		if(verb) printf("success: the anchor is ok\n");
@@ -2230,18 +2256,18 @@ do_root_update_work(const char* root_anchor_file, const char* root_cert_file,
 		return used_builtin;
 	}
 	if(force && verb) printf("debug cert update forced\n");
+	ub_resolve_free(dnskey);
 
 	/* if not (and NOERROR): check date and do certupdate */
-	if((dnskey->rcode == 0 &&
+	if((rcode == 0 &&
 		probe_date_allows_certupdate(root_anchor_file)) || force) {
 		if(do_certupdate(root_anchor_file, root_cert_file, urlname,
 			xmlname, p7sname, p7signer, res_conf, root_hints,
-			debugconf, ip4only, ip6only, port, dnskey))
+			debugconf, ip4only, ip6only, port))
 			return 1;
 		return used_builtin;
 	}
 	if(verb) printf("fail: the anchor is NOT ok and could not be fixed\n");
-	ub_resolve_free(dnskey);
 	return used_builtin;
 }
 
@@ -2264,8 +2290,9 @@ int main(int argc, char* argv[])
 	const char* root_hints = NULL;
 	const char* debugconf = NULL;
 	int dolist=0, ip4only=0, ip6only=0, force=0, port = HTTPS_PORT;
+	int res_conf_fallback = 0;
 	/* parse the options */
-	while( (c=getopt(argc, argv, "46C:FP:a:c:f:hln:r:s:u:vx:")) != -1) {
+	while( (c=getopt(argc, argv, "46C:FRP:a:c:f:hln:r:s:u:vx:")) != -1) {
 		switch(c) {
 		case 'l':
 			dolist = 1;
@@ -2300,6 +2327,9 @@ int main(int argc, char* argv[])
 		case 'r':
 			root_hints = optarg;
 			break;
+		case 'R':
+			res_conf_fallback = 1;
+			break;
 		case 'C':
 			debugconf = optarg;
 			break;
@@ -2346,5 +2376,5 @@ int main(int argc, char* argv[])
 
 	return do_root_update_work(root_anchor_file, root_cert_file, urlname,
 		xmlname, p7sname, p7signer, res_conf, root_hints, debugconf,
-		ip4only, ip6only, force, port);
+		ip4only, ip6only, force, res_conf_fallback, port);
 }