Add IMSG_SET_RESOLV_CONF and keep the cached contents

in the priv process, so that they do not have to be
continually retransmitted. IMSG_WRITE_RESOLV_CONF
now just triggers a write of the cached info.

Simplifies a bunch of logic.

5 files changed, 63 insertions, 52 deletions

diff --git a/sbin/dhclient/dhclient.c b/sbin/dhclient/dhclient.c
index a6f42c894f7..6c018fd4cce 100644
--- a/sbin/dhclient/dhclient.c
+++ b/sbin/dhclient/dhclient.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: dhclient.c,v 1.491 2017/08/09 19:35:59 krw Exp $	*/
+/*	$OpenBSD: dhclient.c,v 1.492 2017/08/10 17:15:05 krw Exp $	*/
 
 /*
  * Copyright 2004 Henning Brauer <henning@openbsd.org>
@@ -416,10 +416,8 @@ routehandler(struct interface_info *ifi, int routefd)
 	}
 
 	/* Something has happened. Try to write out the resolv.conf. */
-	if (ifi->active != NULL && ifi->active->resolv_conf != NULL &&
-	    (ifi->flags & IFI_IN_CHARGE) != 0)
-		write_resolv_conf(ifi->active->resolv_conf,
-		    strlen(ifi->active->resolv_conf));
+	if (ifi->active != NULL && (ifi->flags & IFI_IN_CHARGE) != 0)
+		write_resolv_conf();
 
 done:
 	free(rtmmsg);
@@ -989,13 +987,6 @@ bind_lease(struct interface_info *ifi)
 	time_t			 cur_time;
 	int			 seen;
 
-	/*
-	 * Clear out any old resolv_conf in case the lease has been here
-	 * before (e.g. static lease).
-	 */
-	free(ifi->offer->resolv_conf);
-	ifi->offer->resolv_conf = NULL;
-
 	lease = apply_defaults(ifi->offer);
 
 	set_lease_times(lease);
@@ -1013,8 +1004,6 @@ bind_lease(struct interface_info *ifi)
 		offered_proposal = lease_as_proposal(ifi->offer);
 		if (memcmp(active_proposal, offered_proposal,
 		    sizeof(*active_proposal)) == 0) {
-			ifi->offer->resolv_conf = ifi->active->resolv_conf;
-			ifi->active->resolv_conf = NULL;
 			ifi->active = ifi->offer;
 			ifi->offer = NULL;
 			goto newlease;
@@ -1026,7 +1015,7 @@ bind_lease(struct interface_info *ifi)
 	ifi->offer = NULL;
 	effective_proposal = lease_as_proposal(lease);
 
-	ifi->active->resolv_conf = resolv_conf_contents(ifi->name,
+	set_resolv_conf(ifi->name,
 	    effective_proposal->rtsearch,
 	    effective_proposal->rtsearch_len,
 	    effective_proposal->rtdns,
@@ -1041,6 +1030,7 @@ bind_lease(struct interface_info *ifi)
 	    effective_proposal->rtstatic, effective_proposal->rtstatic_len);
 
 newlease:
+	write_resolv_conf();
 	log_info("bound to %s -- renewal in %lld seconds.",
 	    inet_ntoa(ifi->active->address),
 	    (long long)(ifi->active->renewal - time(NULL)));
@@ -1722,7 +1712,6 @@ free_client_lease(struct client_lease *lease)
 
 	free(lease->server_name);
 	free(lease->filename);
-	free(lease->resolv_conf);
 	for (i = 0; i < DHO_COUNT; i++)
 		free(lease->options[i].data);
 
@@ -2385,11 +2374,6 @@ clone_lease(struct client_lease *oldlease)
 		if (newlease->filename == NULL)
 			goto cleanup;
 	}
-	if (oldlease->resolv_conf != NULL) {
-		newlease->resolv_conf = strdup(oldlease->resolv_conf);
-		if (newlease->resolv_conf == NULL)
-			goto cleanup;
-	}
 
 	for (i = 0; i < DHO_COUNT; i++) {
 		if (oldlease->options[i].len == 0)
diff --git a/sbin/dhclient/dhcpd.h b/sbin/dhclient/dhcpd.h
index 856a258dccc..47a1e63bc59 100644
--- a/sbin/dhclient/dhcpd.h
+++ b/sbin/dhclient/dhcpd.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: dhcpd.h,v 1.221 2017/08/09 19:57:54 krw Exp $	*/
+/*	$OpenBSD: dhcpd.h,v 1.222 2017/08/10 17:15:05 krw Exp $	*/
 
 /*
  * Copyright (c) 2004 Henning Brauer <henning@openbsd.org>
@@ -61,7 +61,6 @@ struct client_lease {
 	struct in_addr		 next_server;
 	char			*server_name;
 	char			*filename;
-	char			*resolv_conf;
 	char			 ssid[32];
 	uint8_t			 ssid_len;
 	unsigned int		 is_static;
@@ -234,7 +233,9 @@ void		 read_client_leases(char *, struct client_lease_tq *);
 
 /* kroute.c */
 void		 delete_address(struct in_addr);
-void		 write_resolv_conf(uint8_t *, size_t);
+void		 set_resolv_conf(char *, uint8_t *, unsigned int,
+    uint8_t *, unsigned int);
+void		 write_resolv_conf(void);
 void		 set_mtu(int, uint16_t);
 void		 set_address(char *, struct in_addr, struct in_addr);
 void		 set_routes(struct in_addr, struct in_addr, uint8_t *,
diff --git a/sbin/dhclient/kroute.c b/sbin/dhclient/kroute.c
index 6b737ef5b28..ef32b7a41e4 100644
--- a/sbin/dhclient/kroute.c
+++ b/sbin/dhclient/kroute.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: kroute.c,v 1.135 2017/08/09 19:57:54 krw Exp $	*/
+/*	$OpenBSD: kroute.c,v 1.136 2017/08/10 17:15:05 krw Exp $	*/
 
 /*
  * Copyright 2012 Kenneth R Westerback <krw@openbsd.org>
@@ -648,21 +648,22 @@ priv_set_address(char *name, int ioctlfd, struct imsg_set_address *imsg)
  * [priv_]write_resolv_conf write out a new resolv.conf.
  */
 void
-write_resolv_conf(uint8_t *contents, size_t sz)
+write_resolv_conf(void)
 {
 	int	 rslt;
 
 	rslt = imsg_compose(unpriv_ibuf, IMSG_WRITE_RESOLV_CONF,
-	    0, 0, -1, contents, sz);
+	    0, 0, -1, NULL, 0);
 	if (rslt == -1)
 		log_warn("write_resolv_conf: imsg_compose");
 }
 
 void
-priv_write_resolv_conf(uint8_t *contents, size_t sz)
+priv_write_resolv_conf(char *contents)
 {
 	const char	*path = "/etc/resolv.conf";
 	ssize_t		 n;
+	size_t		 sz;
 	int		 fd;
 
 	fd = open(path, O_WRONLY | O_CREAT | O_TRUNC,
@@ -673,12 +674,15 @@ priv_write_resolv_conf(uint8_t *contents, size_t sz)
 		return;
 	}
 
-	n = write(fd, contents, sz);
-	if (n == -1)
-		log_warn("Couldn't write contents to '%s'", path);
-	else if ((size_t)n < sz)
-		log_warnx("Short contents write to '%s' (%zd vs %zu)",
-		    path, n, sz);
+	if (contents != NULL) {
+		sz = strlen(contents);
+		n = write(fd, contents, sz);
+		if (n == -1)
+			log_warn("Couldn't write contents to '%s'", path);
+		else if ((size_t)n < sz)
+			log_warnx("Short contents write to '%s' (%zd vs %zu)",
+			    path, n, sz);
+	}
 
 	close(fd);
 }
@@ -760,13 +764,12 @@ done:
 }
 
 /*
- * resolv_conf_contents creates a string that are the resolv.conf contents
+ * set_resolv_conf creates a string that are the resolv.conf contents
  * that should be used when the interface is determined to be the one to
  * create /etc/resolv.conf
  */
-char *
-resolv_conf_contents(char *name,
-    uint8_t *rtsearch, unsigned int rtsearch_len,
+void
+set_resolv_conf(char *name, uint8_t *rtsearch, unsigned int rtsearch_len,
     uint8_t *rtdns, unsigned int rtdns_len)
 {
 	char		*dn, *nss[MAXNS], *contents, *courtesy;
@@ -814,7 +817,7 @@ resolv_conf_contents(char *name,
 
 	if (len == 0) {
 		free(dn);
-		return NULL;
+		return;
 	}
 
 	rslt = asprintf(&courtesy, "# Generated by %s dhclient\n", name);
@@ -843,7 +846,10 @@ resolv_conf_contents(char *name,
 	if (config->resolv_tail != NULL)
 		strlcat(contents, config->resolv_tail, len);
 
-	return contents;
+	rslt = imsg_compose(unpriv_ibuf, IMSG_SET_RESOLV_CONF,
+	    0, 0, -1, contents, len);
+	if (rslt == -1)
+		log_warn("set_resolv_conf: imsg_compose");
 }
 
 /*
diff --git a/sbin/dhclient/privsep.c b/sbin/dhclient/privsep.c
index a2d48687d0a..7d77fc1662b 100644
--- a/sbin/dhclient/privsep.c
+++ b/sbin/dhclient/privsep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: privsep.c,v 1.62 2017/08/08 17:54:24 krw Exp $ */
+/*	$OpenBSD: privsep.c,v 1.63 2017/08/10 17:15:05 krw Exp $ */
 
 /*
  * Copyright (c) 2004 Henning Brauer <henning@openbsd.org>
@@ -28,6 +28,7 @@
 #include <imsg.h>
 #include <signal.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 
 #include "dhcp.h"
@@ -39,9 +40,11 @@ int
 dispatch_imsg(char *name, int rdomain, int ioctlfd, int routefd,
     struct imsgbuf *ibuf)
 {
-	struct imsg	imsg;
-	ssize_t		n;
-	int		index;
+	static char	*resolv_conf;
+	struct imsg	 imsg;
+	ssize_t		 n;
+	size_t		 sz;
+	int		 index;
 
 	index = if_nametoindex(name);
 	if (index == 0)
@@ -95,13 +98,31 @@ dispatch_imsg(char *name, int rdomain, int ioctlfd, int routefd,
 				priv_set_mtu(name, ioctlfd, imsg.data);
 			break;
 
+		case IMSG_SET_RESOLV_CONF:
+			if (imsg.hdr.len < IMSG_HEADER_SIZE)
+				log_warnx("bad IMSG_SET_RESOLV_CONF");
+			else {
+				free(resolv_conf);
+				resolv_conf = NULL;
+				sz = imsg.hdr.len - IMSG_HEADER_SIZE;
+				if (sz > 0) {
+					resolv_conf = malloc(sz);
+					if (resolv_conf == NULL)
+						log_warnx("no memory for "
+						    "resolv_conf");
+					else
+						strlcpy(resolv_conf,
+						    imsg.data, sz);
+				}
+			}
+			break;
+
 		case IMSG_WRITE_RESOLV_CONF:
-			if (imsg.hdr.len <= IMSG_HEADER_SIZE)
-				log_warnx("short IMSG_WRITE_RESOLV_CONF");
+			if (imsg.hdr.len != IMSG_HEADER_SIZE)
+				log_warnx("bad IMSG_WRITE_RESOLV_CONF");
 			else if (default_route_index(rdomain, routefd) ==
 			    index)
-				priv_write_resolv_conf(imsg.data,
-				    imsg.hdr.len - IMSG_HEADER_SIZE);
+				priv_write_resolv_conf(resolv_conf);
 			break;
 
 		case IMSG_HUP:
diff --git a/sbin/dhclient/privsep.h b/sbin/dhclient/privsep.h
index 2a67b607344..15a3300cd3a 100644
--- a/sbin/dhclient/privsep.h
+++ b/sbin/dhclient/privsep.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: privsep.h,v 1.52 2017/08/08 17:54:24 krw Exp $ */
+/*	$OpenBSD: privsep.h,v 1.53 2017/08/10 17:15:05 krw Exp $ */
 
 /*
  * Copyright (c) 2004 Henning Brauer <henning@openbsd.org>
@@ -24,6 +24,7 @@ enum imsg_code {
 	IMSG_FLUSH_ROUTES,
 	IMSG_ADD_ROUTE,
 	IMSG_SET_MTU,
+	IMSG_SET_RESOLV_CONF,
 	IMSG_WRITE_RESOLV_CONF
 };
 
@@ -53,9 +54,7 @@ int	default_route_index(int, int);
 void	priv_add_route(char *, int, int, struct imsg_add_route *);
 void	priv_flush_routes(char *, int, int);
 
-char	*resolv_conf_contents(char *, uint8_t *, unsigned int, uint8_t *,
-    unsigned int);
-void	priv_write_resolv_conf(uint8_t *, size_t);
+void	priv_write_resolv_conf(char *);
 
 void	priv_delete_address(char *, int, struct imsg_delete_address *);
 void	priv_set_address(char *, int, struct imsg_set_address *);