[master] Optimized if and when DNS client context and ports are initted

    Merges in rt45290.

9 files changed, 100 insertions, 45 deletions

diff --git a/RELNOTES b/RELNOTES
index 2a2465ed..acd341a6 100644
--- a/RELNOTES
+++ b/RELNOTES
@@ -144,6 +144,15 @@ by Eric Young (eay@cryptsoft.com).
   freebsd, linux, macos, netbsd, openbsd.
   [ISC-Bugs #36169]
 
+- Modified DDNS support initialization such DNS related ports will only be
+  opened by the server (dhcpd) at startup if ddns-update-style is not "none";
+  by dhclient only if and when the it first attempts an update; and never by
+  dhcrelay.  Prior to this all three always did the initialization at startup
+  which causes them to always open on and listen for traffic on two random
+  ports.
+  [ISC-Bugs #45290]
+  [ISC-Bugs #33377]
+
 			Changes since 4.3.0 (bug fixes)
 
 - Tidy up several small tickets.
diff --git a/client/dhclient.8 b/client/dhclient.8
index a00f1f77..24f8f122 100644
--- a/client/dhclient.8
+++ b/client/dhclient.8
@@ -493,8 +493,9 @@ port will be used for the established connection.
 
 When DDNS is enabled at compile time (see includes/site.h)
 the client will open both a v4 and a v6 UDP socket on
-random ports.  These ports are opened even if DDNS is disabled
-in the configuration file.
+random ports.  These ports are not opened unless/until the
+client first attempts to do an update.  If the client is not
+configured to do updates, the ports will never be opened.
 .PP
 .SH CONFIGURATION
 The syntax of the \fBdhclient.conf(5)\fR file is discussed separately.
diff --git a/client/dhclient.c b/client/dhclient.c
index 129aba72..40fd876a 100644
--- a/client/dhclient.c
+++ b/client/dhclient.c
@@ -315,8 +315,8 @@ main(int argc, char **argv) {
 	}
 
 	/* Set up the isc and dns library managers */
-	status = dhcp_context_create(DHCP_CONTEXT_PRE_DB | DHCP_CONTEXT_POST_DB,
-				     NULL, NULL);
+	status = dhcp_context_create(DHCP_CONTEXT_PRE_DB | DHCP_CONTEXT_POST_DB
+				     | DHCP_DNS_CLIENT_LAZY_INIT, NULL, NULL);
 	if (status != ISC_R_SUCCESS)
 		log_fatal("Can't initialize context: %s",
 			  isc_result_totext(status));
diff --git a/common/dns.c b/common/dns.c
index 0f8be80d..2ca4ba8b 100644
--- a/common/dns.c
+++ b/common/dns.c
@@ -3,8 +3,7 @@
    Domain Name Service subroutines. */
 
 /*
- * Copyright (c) 2009-2015 by Internet Systems Consortium, Inc. ("ISC")
- * Copyright (c) 2004-2007 by Internet Systems Consortium, Inc. ("ISC")
+ * Copyright (c) 2004-2017 by Internet Systems Consortium, Inc. ("ISC")
  * Copyright (c) 2001-2003 by Internet Software Consortium
  *
  * Permission to use, copy, modify, and distribute this software for any
@@ -2151,6 +2150,12 @@ ddns_modify_fwd(dhcp_ddns_cb_t *ddns_cb, const char *file, int line)
 
 	isc_sockaddrlist_t *zlist = NULL;
 
+	/* Creates client context if we need to */
+	result = dns_client_init();
+	if (result != ISC_R_SUCCESS) {
+		return result;
+	}
+
 	/* Get a pointer to the clientname to make things easier. */
 	clientname = (unsigned char *)ddns_cb->fwd_name.data;
 
@@ -2359,6 +2364,12 @@ ddns_modify_ptr(dhcp_ddns_cb_t *ddns_cb, const char *file, int line)
 	unsigned char buf[256];
 	int buflen;
 
+	/* Creates client context if we need to */
+	result = dns_client_init();
+	if (result != ISC_R_SUCCESS) {
+		return result;
+	}
+
 	/*
 	 * Try to lookup the zone in the zone cache.  As with the forward
 	 * case it's okay if we don't have one, the DNS code will try to
diff --git a/includes/omapip/isclib.h b/includes/omapip/isclib.h
index caa388ad..e2963089 100644
--- a/includes/omapip/isclib.h
+++ b/includes/omapip/isclib.h
@@ -3,7 +3,7 @@
    connections to the isc and dns libraries */
 
 /*
- * Copyright (c) 2009,2013,2014 by Internet Systems Consortium, Inc. ("ISC")
+ * Copyright (c) 2009-2017 by Internet Systems Consortium, Inc. ("ISC")
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -98,6 +98,10 @@ typedef struct dhcp_context {
 	isc_timermgr_t	*timermgr;
 #if defined (NSUPDATE)
   	dns_client_t    *dnsclient;
+	int use_local4;
+	isc_sockaddr_t local4_sockaddr;
+	int use_local6;
+	isc_sockaddr_t local6_sockaddr;
 #endif
 } dhcp_context_t;
 
@@ -125,6 +129,7 @@ isclib_make_dst_key(char          *inname,
 
 #define DHCP_CONTEXT_PRE_DB  1
 #define DHCP_CONTEXT_POST_DB 2
+#define DHCP_DNS_CLIENT_LAZY_INIT 4
 isc_result_t dhcp_context_create(int              flags,
 				 struct in_addr  *local4,
 				 struct in6_addr *local6);
@@ -133,4 +138,6 @@ void isclib_cleanup(void);
 void dhcp_signal_handler(int signal);
 extern int shutdown_signal;
 
+isc_result_t dns_client_init();
+
 #endif /* ISCLIB_H */
diff --git a/omapip/isclib.c b/omapip/isclib.c
index 781db848..3c9c3590 100644
--- a/omapip/isclib.c
+++ b/omapip/isclib.c
@@ -1,5 +1,5 @@
 /*
- * Copyright(c) 2009-2010,2013-2014 by Internet Systems Consortium, Inc.("ISC")
+ * Copyright(c) 2009-2017 by Internet Systems Consortium, Inc.("ISC")
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -226,39 +226,24 @@ dhcp_context_create(int flags,
 
 #if defined (NSUPDATE)
 	if ((flags & DHCP_CONTEXT_POST_DB) != 0) {
-		isc_sockaddr_t localaddr4, *localaddr4_ptr = NULL;
-		isc_sockaddr_t localaddr6, *localaddr6_ptr = NULL;
+		/* Setting addresses only.
+		 * All real work will be done later on if needed to avoid
+		 * listening on ddns port if client/server was compiled with
+		 * ddns support but not using it. */
 		if (local4 != NULL) {
-			isc_sockaddr_fromin(&localaddr4, local4, 0);
-			localaddr4_ptr = &localaddr4;
+			dhcp_gbl_ctx.use_local4 = 1;
+			isc_sockaddr_fromin(&dhcp_gbl_ctx.local4_sockaddr,
+					    local4, 0);
 		}
+
 		if (local6 != NULL) {
-			isc_sockaddr_fromin6(&localaddr6, local6, 0);
-			localaddr6_ptr = &localaddr6;
+			dhcp_gbl_ctx.use_local6 = 1;
+			isc_sockaddr_fromin6(&dhcp_gbl_ctx.local6_sockaddr,
+					     local6, 0);
 		}
 
-		result = dns_client_createx2(dhcp_gbl_ctx.mctx,
-					     dhcp_gbl_ctx.actx,
-					     dhcp_gbl_ctx.taskmgr,
-					     dhcp_gbl_ctx.socketmgr,
-					     dhcp_gbl_ctx.timermgr,
-					     0,
-					     &dhcp_gbl_ctx.dnsclient,
-					     localaddr4_ptr,
-					     localaddr6_ptr);
-		if (result != ISC_R_SUCCESS)
-			goto cleanup;
-
-		/*
-		 * If we can't set up the servers we may not be able to
-		 * do DDNS but we should continue to try and perform
-		 * our basic functions and let the user sort it out.
-		 */
-		result = dhcp_dns_client_setservers();
-		if (result != ISC_R_SUCCESS) {
-			log_error("Unable to set resolver from resolv.conf; "
-				  "startup continuing but DDNS support "
-				  "may be affected");
+		if (!(flags & DHCP_DNS_CLIENT_LAZY_INIT)) {
+			result = dns_client_init();
 		}
 	}
 #endif
@@ -365,3 +350,40 @@ void dhcp_signal_handler(int signal) {
 		(void) isc_app_ctxsuspend(ctx);
 	}
 }
+
+isc_result_t dns_client_init() {
+	isc_result_t result;
+	if (dhcp_gbl_ctx.dnsclient == NULL) {
+		result = dns_client_createx2(dhcp_gbl_ctx.mctx,
+					     dhcp_gbl_ctx.actx,
+					     dhcp_gbl_ctx.taskmgr,
+					     dhcp_gbl_ctx.socketmgr,
+					     dhcp_gbl_ctx.timermgr,
+					     0,
+					     &dhcp_gbl_ctx.dnsclient,
+					     (dhcp_gbl_ctx.use_local4 ?
+					      &dhcp_gbl_ctx.local4_sockaddr
+					      : NULL),
+					     (dhcp_gbl_ctx.use_local6 ?
+					      &dhcp_gbl_ctx.local6_sockaddr
+					      : NULL));
+
+		if (result != ISC_R_SUCCESS) {
+			log_error("Unable to create DNS client context:"
+				  " result: %d", result);
+			return result;
+		}
+
+		/* If we can't set up the servers we may not be able to
+		 * do DDNS but we should continue to try and perform
+		 * our basic functions and let the user sort it out. */
+		result = dhcp_dns_client_setservers();
+		if (result != ISC_R_SUCCESS) {
+			log_error("Unable to set resolver from resolv.conf; "
+				  "startup continuing but DDNS support "
+				  "may be affected: result %d", result);
+		}
+	}
+
+	return ISC_R_SUCCESS;
+}
diff --git a/relay/dhcrelay.c b/relay/dhcrelay.c
index f4943879..3f1b3d04 100644
--- a/relay/dhcrelay.c
+++ b/relay/dhcrelay.c
@@ -308,8 +308,7 @@ main(int argc, char **argv) {
 
 
 	/* Set up the isc and dns library managers */
-	status = dhcp_context_create(DHCP_CONTEXT_PRE_DB | DHCP_CONTEXT_POST_DB,
-				     NULL, NULL);
+	status = dhcp_context_create(DHCP_CONTEXT_PRE_DB, NULL, NULL);
 	if (status != ISC_R_SUCCESS)
 		log_fatal("Can't initialize context: %s",
 			  isc_result_totext(status));
diff --git a/server/dhcpd.8 b/server/dhcpd.8
index 6ca79402..d27a1ea7 100644
--- a/server/dhcpd.8
+++ b/server/dhcpd.8
@@ -1,6 +1,6 @@
 .\"	dhcpd.8
 .\"
-.\" Copyright (c) 2004-2016 by Internet Systems Consortium, Inc. ("ISC")
+.\" Copyright (c) 2004-2017 by Internet Systems Consortium, Inc. ("ISC")
 .\" Copyright (c) 1996-2003 by Internet Software Consortium
 .\"
 .\" Permission to use, copy, modify, and distribute this software for any
@@ -369,8 +369,8 @@ port will be used for the established connection.
 
 When DDNS is enabled at compile time (see includes/site.h)
 the server will open both a v4 and a v6 UDP socket on
-random ports.  These ports are opened even if DDNS is disabled
-in the configuration file.
+random ports, unless DDNS updates are globally disabled by
+setting ddns-update-style to none in the configuration file.
 .PP
 .SH CONFIGURATION
 The syntax of the dhcpd.conf(5) file is discussed separately.  This
diff --git a/server/dhcpd.c b/server/dhcpd.c
index 910f374f..ce33587c 100644
--- a/server/dhcpd.c
+++ b/server/dhcpd.c
@@ -1253,10 +1253,16 @@ void postconf_initialization (int quiet)
 		}
 	}
 
-	if (dhcp_context_create(DHCP_CONTEXT_POST_DB, local4_ptr, local6_ptr)
-	    != ISC_R_SUCCESS)
-		log_fatal("Unable to complete ddns initialization");
-
+	/* Don't init DNS client if update style is none. This avoids
+	 * listening ports that aren't needed.  We don't use ddns-udpates
+	 * as that has multiple levels of scope. */
+	if (ddns_update_style != DDNS_UPDATE_STYLE_NONE) {
+		if (dhcp_context_create(DHCP_CONTEXT_POST_DB,
+					local4_ptr, local6_ptr)
+			!= ISC_R_SUCCESS) {
+			log_fatal("Unable to complete ddns initialization");
+		}
+	}
 #else
 	/* If we don't have support for updates compiled in tell the user */
 	if (ddns_update_style != DDNS_UPDATE_STYLE_NONE) {