add "dig +tls"

- add "+[no]tls" option to dig to enable TLS mode
- override the default port number in dig from 53 to 853 when using TLS

bin/dig/dig.c

@@ -287,6 +287,7 @@ help(void) {
 	       "(+[no]tcflag))\n"
 	       "                 +[no]tcp            (TCP mode (+[no]vc))\n"
 	       "                 +timeout=###        (Set query timeout) [5]\n"
+	       "                 +[no]tls            (DNS over TLS mode)\n"
 	       "                 +[no]trace          (Trace delegation down "
 	       "from root "
 	       "[+dnssec])\n"
@@ -1726,6 +1727,13 @@ plus_option(char *option, bool is_batchfile, dig_lookup_t *lookup) {
 				timeout = 1;
 			}
 			break;
+		case 'l':
+			FULLCHECK("tls");
+			lookup->tls_mode = state;
+			if (!lookup->tcp_mode_set) {
+				lookup->tcp_mode = state;
+			}
+			break;
 		case 'o':
 			FULLCHECK("topdown");
 			fprintf(stderr, ";; +topdown option is deprecated");
@@ -2027,6 +2035,7 @@ dash_option(char *option, char *next, dig_lookup_t **lookup,
 			fatal("Couldn't parse port number");
 		}
 		port = num;
+		port_set = true;
 		return (value_from_next);
 	case 'q':
 		if (!config_only) {

bin/dig/dig.rst

@@ -506,14 +506,19 @@ abbreviation is unambiguous; for example, ``+cd`` is equivalent to
    ``+notcflag``. This bit is ignored by the server for QUERY.
 
 ``+[no]tcp``
-   This option uses [or does not use] TCP when querying name servers. The default behavior
-   is to use UDP unless a type ``any`` or ``ixfr=N`` query is requested,
-   in which case the default is TCP. AXFR queries always use TCP.
+   This option indicates whether to use TCP when querying name servers.
+   The default behavior is to use UDP unless a type ``any`` or ``ixfr=N``
+   query is requested, in which case the default is TCP. AXFR queries
+   always use TCP.
 
 ``+timeout=T``
    This option sets the timeout for a query to ``T`` seconds. The default timeout is
    5 seconds. An attempt to set ``T`` to less than 1 is silently set to 1.
 
+``+[no]tls``
+   This option indicates whether to use DNS over TLS (DoT) when querying
+   name servers.
+
 ``+[no]topdown``
    This feature is related to ``dig +sigchase``, which is obsolete and
    has been removed. Use ``delv`` instead.

bin/dig/dighost.c

@@ -101,6 +101,7 @@ bool check_ra = false, have_ipv4 = false, have_ipv6 = false,
      showsearch = false, is_dst_up = false, keep_open = false, verbose = false,
      yaml = false;
 in_port_t port = 53;
+bool port_set = false;
 unsigned int timeout = 0;
 unsigned int extrabytes;
 isc_mem_t *mctx = NULL;
@@ -678,6 +679,7 @@ make_empty_lookup(void) {
 	looknew->nsfound = 0;
 	looknew->tcp_mode = false;
 	looknew->tcp_mode_set = false;
+	looknew->tls_mode = false;
 	looknew->comments = true;
 	looknew->stats = true;
 	looknew->section_question = true;
@@ -823,6 +825,7 @@ clone_lookup(dig_lookup_t *lookold, bool servers) {
 	looknew->ns_search_only = lookold->ns_search_only;
 	looknew->tcp_mode = lookold->tcp_mode;
 	looknew->tcp_mode_set = lookold->tcp_mode_set;
+	looknew->tls_mode = lookold->tls_mode;
 	looknew->comments = lookold->comments;
 	looknew->stats = lookold->stats;
 	looknew->section_question = lookold->section_question;
@@ -2756,6 +2759,13 @@ start_tcp(dig_query_t *query) {
 	debug("start_tcp(%p)", query);
 
 	query_attach(query, &query->lookup->current_query);
+
+	/*
+	 * For TLS connections, we want to override the default
+	 * port number.
+	 */
+	port = port_set ? port : (query->lookup->tls_mode ? 853 : 53);
+
 	result = get_address(query->servname, port, &query->sockaddr);
 	if (result != ISC_R_SUCCESS) {
 		/*
@@ -2821,11 +2831,20 @@ start_tcp(dig_query_t *query) {
 
 		REQUIRE(query != NULL);
 
-		result = isc_nm_tcpdnsconnect(
-			netmgr, (isc_nmiface_t *)&localaddr,
-			(isc_nmiface_t *)&query->sockaddr, tcp_connected, query,
-			local_timeout, 0);
-		check_result(result, "isc_nm_tcpdnsconnect");
+		if (query->lookup->tls_mode) {
+			result = isc_nm_tlsdnsconnect(
+				netmgr, (isc_nmiface_t *)&localaddr,
+				(isc_nmiface_t *)&query->sockaddr,
+				tcp_connected, query, local_timeout, 0);
+			check_result(result, "isc_nm_tcpdnsconnect");
+		} else {
+			result = isc_nm_tcpdnsconnect(
+				netmgr, (isc_nmiface_t *)&localaddr,
+				(isc_nmiface_t *)&query->sockaddr,
+				tcp_connected, query, local_timeout, 0);
+			check_result(result, "isc_nm_tcpdnsconnect");
+		}
+
 		/* XXX: set DSCP */
 	}
 
@@ -2871,6 +2890,7 @@ send_udp(dig_query_t *query) {
 
 	isc_nm_send(query->handle, &r, send_done, sendquery);
 	isc_refcount_increment0(&sendcount);
+	debug("sendcount=%" PRIuFAST32, isc_refcount_current(&sendcount));
 
 	/* XXX qrflag, print_query, etc... */
 	if (!ISC_LIST_EMPTY(query->lookup->q) && query->lookup->qr) {
@@ -3176,6 +3196,7 @@ launch_next_query(dig_query_t *query) {
 		if (keep != NULL) {
 			query->handle = keep;
 		}
+
 		isc_nmhandle_attach(query->handle, &query->sendhandle);
 		isc_nm_send(query->handle, &r, send_done, sendquery);
 		isc_refcount_increment0(&sendcount);

bin/dig/dighost.h

@@ -120,7 +120,8 @@ struct dig_lookup {
 		tcp_keepalive, header_only, ednsneg, mapped,
 		print_unknown_format, multiline, nottl, noclass, onesoa,
 		use_usec, nocrypto, ttlunits, idnin, idnout, expandaaaa, qr,
-		setqid;	       /*% use a specified query ID */
+		setqid,	       /*% use a specified query ID */
+		tls_mode;      /*% connect using TLS */
 	char textname[MXNAME]; /*% Name we're going to be
 				* looking up */
 	char cmdline[MXNAME];
@@ -228,6 +229,7 @@ extern unsigned int extrabytes;
 extern bool check_ra, have_ipv4, have_ipv6, specified_source, usesearch,
 	showsearch, yaml;
 extern in_port_t port;
+extern bool port_set;
 extern unsigned int timeout;
 extern isc_mem_t *mctx;
 extern isc_refcount_t sendcount;