Use the libutil imsg framework rather than a hand-rolled local

version. This is the last hand-rolled imsg implementation I could
spot. Doesn't seem to break sparc64.

Suggested by chris@, tweaks from brad@ and reyk@.

ok reyk@

7 files changed, 251 insertions, 487 deletions

diff --git a/distrib/special/dhclient/Makefile b/distrib/special/dhclient/Makefile
index fc5a3014d75..e8cc7af8524 100644
--- a/distrib/special/dhclient/Makefile
+++ b/distrib/special/dhclient/Makefile
@@ -1,4 +1,4 @@
-#	$OpenBSD: Makefile,v 1.12 2012/11/09 18:51:56 krw Exp $
+#	$OpenBSD: Makefile,v 1.13 2012/11/23 15:25:47 krw Exp $
 
 .include <bsd.own.mk>
 
@@ -10,6 +10,8 @@ SRCS=	dhclient.c clparse.c dispatch.c bpf.c options.c \
 	conflex.c errwarn.c kroute.c packet.c convert.c \
 	tables.c parse.c privsep.c
 PROG=	dhclient
+LDADD+=	-lutil
+DPADD+= ${LIBUTIL}
 
 .include <bsd.prog.mk>
 .include <bsd.subdir.mk>
diff --git a/sbin/dhclient/dhclient.c b/sbin/dhclient/dhclient.c
index fc2bfcc1d83..038b74dfed6 100644
--- a/sbin/dhclient/dhclient.c
+++ b/sbin/dhclient/dhclient.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: dhclient.c,v 1.178 2012/11/16 16:46:18 krw Exp $	*/
+/*	$OpenBSD: dhclient.c,v 1.179 2012/11/23 15:25:47 krw Exp $	*/
 
 /*
  * Copyright 2004 Henning Brauer <henning@openbsd.org>
@@ -69,7 +69,6 @@ char *path_dhclient_conf = _PATH_DHCLIENT_CONF;
 char *path_dhclient_db = NULL;
 
 int log_perror = 1;
-int privfd;
 int nullfd = -1;
 int no_daemon;
 int unknown_ok = 1;
@@ -84,6 +83,7 @@ struct sockaddr_in sockaddr_broadcast;
 struct interface_info *ifi;
 struct client_state *client;
 struct client_config *config;
+struct imsgbuf *unpriv_ibuf;
 
 int		 findproto(char *, int);
 struct sockaddr	*get_ifa(char *, int);
@@ -97,6 +97,7 @@ void		 get_ifname(char *, char *);
 void		 new_resolv_conf(char *, char *, char *);
 struct client_lease *apply_defaults(struct client_lease *);
 struct client_lease *clone_lease(struct client_lease *);
+void		 socket_nonblockmode(int);
 
 #define	ROUNDUP(a) \
 	    ((a) > 0 ? (1 + (((a) - 1) | (sizeof(long) - 1))) : sizeof(long))
@@ -259,7 +260,7 @@ die:
 int
 main(int argc, char *argv[])
 {
-	int	 ch, fd, quiet = 0, i = 0, pipe_fd[2];
+	int	 ch, fd, quiet = 0, i = 0, socket_fd[2];
 	extern char *__progname;
 	struct passwd *pw;
 	int rtfilter;
@@ -356,16 +357,20 @@ main(int argc, char *argv[])
 	if ((pw = getpwnam("_dhcp")) == NULL)
 		error("no such user: _dhcp");
 
-	if (pipe(pipe_fd) == -1)
-		error("pipe");
-
 	/* set up the interface */
 	discover_interface();
 
-	fork_privchld(pipe_fd[0], pipe_fd[1]);
+	if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socket_fd) == -1)
+		error("socketpair: %m");
+	socket_nonblockmode(socket_fd[0]);
+	socket_nonblockmode(socket_fd[1]);
+
+	fork_privchld(socket_fd[0], socket_fd[1]);
 
-	close(pipe_fd[0]);
-	privfd = pipe_fd[1];
+	close(socket_fd[0]);
+	if ((unpriv_ibuf = malloc(sizeof(struct imsgbuf))) == NULL)
+		error("no memory for unpriv_ibuf");
+	imsg_init(unpriv_ibuf, socket_fd[1]);
 
 	if ((fd = open(path_dhclient_db, O_RDONLY|O_EXLOCK|O_CREAT, 0)) == -1)
 		error("can't open and lock %s: %m", path_dhclient_db);
@@ -1688,6 +1693,8 @@ int
 fork_privchld(int fd, int fd2)
 {
 	struct pollfd pfd[1];
+	struct imsgbuf *priv_ibuf;
+	ssize_t n;
 	int nfds;
 
 	switch (fork()) {
@@ -1714,17 +1721,29 @@ fork_privchld(int fd, int fd2)
 	close(nullfd);
 	close(fd2);
 
+	if ((priv_ibuf = malloc(sizeof(struct imsgbuf))) == NULL)
+		error("no memory for priv_ibuf");
+
+	imsg_init(priv_ibuf, fd);
+
 	for (;;) {
-		pfd[0].fd = fd;
+		pfd[0].fd = priv_ibuf->fd;
 		pfd[0].events = POLLIN;
-		if ((nfds = poll(pfd, 1, INFTIM)) == -1)
+		if ((nfds = poll(pfd, 1, INFTIM)) == -1) {
 			if (errno != EINTR)
-				error("poll error");
+				error("poll error: %m");
+		} 
 
 		if (nfds == 0 || !(pfd[0].revents & POLLIN))
 			continue;
 
-		dispatch_imsg(fd);
+		if ((n = imsg_read(priv_ibuf)) == -1)
+			error("imsg_read(priv_ibuf): %m");
+
+		if (n == 0)	/* connection closed */
+			error("dispatch_imsg in main: pipe closed");
+
+		dispatch_imsg(priv_ibuf);
 	}
 }
 
@@ -1774,52 +1793,40 @@ get_ifname(char *ifname, char *arg)
  * Update resolv.conf.
  */
 
-#define MAXRESOLVCONFSIZE 2048
-
 void
 new_resolv_conf(char *ifname, char *domainname, char *nameservers)
 {
-	size_t		 len;
-	struct imsg_hdr	 hdr;
-	struct buf	*buf;
-	char		*contents, *p;
+	struct imsg_resolv_conf  imsg;
+	char			*p;
+	int			 rslt;
 
-	contents = calloc(1, MAXRESOLVCONFSIZE);
+	memset(&imsg, 0, sizeof(imsg));
 
 	/* Build string of contents of new resolv.conf. */
 	if (domainname && strlen(domainname)) {
-		strlcat(contents, "search ", MAXRESOLVCONFSIZE);
-		strlcat(contents, domainname, MAXRESOLVCONFSIZE);
-		strlcat(contents, "\n", MAXRESOLVCONFSIZE);
+		strlcat(imsg.contents, "search ", MAXRESOLVCONFSIZE);
+		strlcat(imsg.contents, domainname, MAXRESOLVCONFSIZE);
+		strlcat(imsg.contents, "\n", MAXRESOLVCONFSIZE);
 	}
 
 	for (p = strsep(&nameservers, " "); p != NULL;
 	    p = strsep(&nameservers, " ")) {
 		if (*p == '\0')
 			continue;
-		strlcat(contents, "nameserver ", MAXRESOLVCONFSIZE);
-		strlcat(contents, p, MAXRESOLVCONFSIZE);
-		strlcat(contents, "\n", MAXRESOLVCONFSIZE);
+		strlcat(imsg.contents, "nameserver ", MAXRESOLVCONFSIZE);
+		strlcat(imsg.contents, p, MAXRESOLVCONFSIZE);
+		strlcat(imsg.contents, "\n", MAXRESOLVCONFSIZE);
 	}
 
-	hdr.code = IMSG_NEW_RESOLV_CONF;
-	hdr.len = sizeof(hdr) +
-	    sizeof(len) + strlen(contents);
-
-	buf = buf_open(hdr.len);
-	buf_add(buf, &hdr, sizeof(hdr));
+	rslt = imsg_compose(unpriv_ibuf, IMSG_NEW_RESOLV_CONF, 0, 0, -1, &imsg,
+	    sizeof(imsg));
 
-	len = strlen(contents);
-	buf_add(buf, &len, sizeof(len));
-	buf_add(buf, contents, len);
-
-	buf_close(privfd, buf);
-
-	free(contents);
+	if (rslt == -1)
+		warning("new_resolv_conf: imsg_compose: %m");
 }
 
 void
-priv_resolv_conf(char *contents)
+priv_resolv_conf(struct imsg_resolv_conf *imsg)
 {
 	ssize_t n;
 	int conffd, tailfd, tailn;
@@ -1833,15 +1840,15 @@ priv_resolv_conf(char *contents)
 		return;
 	}
 
-	if (contents) {
-		n = write(conffd, contents, strlen(contents));
+	if (strlen(imsg->contents)) {
+		n = write(conffd, imsg->contents, strlen(imsg->contents));
 		if (n == -1)
 			note("Couldn't write contents to resolv.conf: %m");
 		else if (n == 0)
 			note("Couldn't write contents to resolv.conf");
-		else if (n < strlen(contents))
+		else if (n < strlen(imsg->contents))
 			note("Short contents write to resolv.conf (%zd vs %zd)",
-			    n, strlen(contents));
+			    n, strlen(imsg->contents));
 	}
 
 	tailfd = open("/etc/resolv.conf.tail", O_RDONLY);
@@ -1871,7 +1878,7 @@ priv_resolv_conf(char *contents)
 		free(buf);
 	}
 
-	if ((!contents || strlen(contents) == 0) && (tailn < 1 || n < 1)) {
+	if ((strlen(imsg->contents) == 0) && (tailn < 1 || n < 1)) {
 		note("No contents for resolv.conf");
 		unlink("/etc/resolv.conf");
 		close(conffd);
@@ -1988,3 +1995,17 @@ clone_lease(struct client_lease *oldlease)
 
 	return (newlease);
 }
+
+void
+socket_nonblockmode(int fd)
+{
+	int	flags;
+
+	if ((flags = fcntl(fd, F_GETFL, 0)) == -1)
+		error("fcntl F_GETF: %m");
+
+	flags |= O_NONBLOCK;
+
+	if ((flags = fcntl(fd, F_SETFL, flags)) == -1)
+		error("fcntl F_SETFL: %m");
+}
diff --git a/sbin/dhclient/dhcpd.h b/sbin/dhclient/dhcpd.h
index 4a34af62311..a3b2bcdb1b2 100644
--- a/sbin/dhclient/dhcpd.h
+++ b/sbin/dhclient/dhcpd.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: dhcpd.h,v 1.92 2012/11/14 15:47:41 krw Exp $	*/
+/*	$OpenBSD: dhcpd.h,v 1.93 2012/11/23 15:25:47 krw Exp $	*/
 
 /*
  * Copyright (c) 2004 Henning Brauer <henning@openbsd.org>
@@ -191,7 +191,7 @@ struct dhcp_timeout {
 extern struct interface_info *ifi;
 extern struct client_state *client;
 extern struct client_config *config;
-extern int privfd;
+extern struct imsgbuf *unpriv_ibuf;
 extern struct in_addr deleting;
 extern struct in_addr adding;
 
@@ -295,8 +295,6 @@ void go_daemon(void);
 
 void routehandler(void);
 
-void priv_resolv_conf(char *);
-
 /* packet.c */
 void assemble_hw_header(unsigned char *, int *, struct hardware *);
 void assemble_udp_ip_header(unsigned char *, int *, u_int32_t, u_int32_t,
@@ -320,13 +318,9 @@ void parse_reject_statement(FILE *);
 /* kroute.c */
 void delete_addresses(char *, int);
 void delete_address(char *, int, struct in_addr);
-void priv_delete_address(char *, int, struct in_addr);
 
 void add_address(char *, int, struct in_addr, struct in_addr);
-void priv_add_address(char *, int, struct in_addr, struct in_addr);
 
 void flush_routes_and_arp_cache(int);
-void priv_flush_routes_and_arp_cache(int);
 
 void add_default_route(int, struct in_addr, struct in_addr);
-void priv_add_default_route(int, struct in_addr, struct in_addr);
diff --git a/sbin/dhclient/dispatch.c b/sbin/dhclient/dispatch.c
index 3b0d17128f9..cd73f79d7d1 100644
--- a/sbin/dhclient/dispatch.c
+++ b/sbin/dhclient/dispatch.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: dispatch.c,v 1.65 2012/11/08 21:32:55 krw Exp $	*/
+/*	$OpenBSD: dispatch.c,v 1.66 2012/11/23 15:25:47 krw Exp $	*/
 
 /*
  * Copyright 2004 Henning Brauer <henning@openbsd.org>
@@ -40,6 +40,7 @@
  */
 
 #include "dhcpd.h"
+#include "privsep.h"
 
 #include <sys/ioctl.h>
 
@@ -154,10 +155,13 @@ another:
 
 		fds[0].fd = ifi->rfdesc;
 		fds[1].fd = routefd; /* Could be -1, which will be ignored. */
-		fds[2].fd = privfd;
+		fds[2].fd = unpriv_ibuf->fd;
 		fds[0].events = fds[1].events = fds[2].events = POLLIN;
 
-		/* Wait for a packet or a timeout or privfd ... XXX */
+		if (unpriv_ibuf->w.queued)
+			fds[2].events |= POLLOUT;
+
+		/* Wait for a packet or a timeout or unpriv_ibuf->fd ... XXX */
 		count = poll(fds, 3, to_msec);
 
 		/* Not likely to be transitory... */
@@ -176,6 +180,10 @@ another:
 			if (ifi)
 				routehandler();
 		}
+		if (fds[2].revents & POLLOUT) {
+			if (msgbuf_write(&unpriv_ibuf->w) == -1)
+				error("pipe write error to [priv]");
+		}
 		if ((fds[2].revents & (POLLIN | POLLHUP))) {
 			error("lost connection to [priv]");
 		}
diff --git a/sbin/dhclient/kroute.c b/sbin/dhclient/kroute.c
index a991f7574c2..03b201cebda 100644
--- a/sbin/dhclient/kroute.c
+++ b/sbin/dhclient/kroute.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: kroute.c,v 1.18 2012/11/17 10:39:24 krw Exp $	*/
+/*	$OpenBSD: kroute.c,v 1.19 2012/11/23 15:25:47 krw Exp $	*/
 
 /*
  * Copyright 2012 Kenneth R Westerback <krw@openbsd.org>
@@ -36,26 +36,26 @@
 void
 flush_routes_and_arp_cache(int rdomain)
 {
-	size_t		 len;
-	struct imsg_hdr	 hdr;
-	struct buf	*buf;
+	struct imsg_flush_routes imsg;
+	int			 rslt;
 
-	hdr.code = IMSG_FLUSH_ROUTES;
-	hdr.len = sizeof(hdr) +
-	    sizeof(len) + sizeof(rdomain);
+	memset(&imsg, 0, sizeof(imsg));
 
-	buf = buf_open(hdr.len);
-	buf_add(buf, &hdr, sizeof(hdr));
+	imsg.rdomain = rdomain;
 
-	len = sizeof(rdomain);
-	buf_add(buf, &len, sizeof(len));
-	buf_add(buf, &rdomain, len);
+	rslt = imsg_compose(unpriv_ibuf, IMSG_FLUSH_ROUTES, 0, 0, -1,
+	    &imsg, sizeof(imsg));
+	if (rslt == -1)
+		warning("flush_routes_and_arp_cache: imsg_compose: %m");
 
-	buf_close(privfd, buf);
+	/* Do flush to maximize chances of cleaning up routes on exit. */
+	rslt = imsg_flush(unpriv_ibuf);
+	if (rslt == -1)
+		warning("flush_routes_and_arp_cache: imsg_flush: %m");
 }
 
 void
-priv_flush_routes_and_arp_cache(int rdomain)
+priv_flush_routes_and_arp_cache(struct imsg_flush_routes *imsg)
 {
 	struct sockaddr *rti_info[RTAX_MAX];
 	int mib[7];
@@ -74,10 +74,10 @@ priv_flush_routes_and_arp_cache(int rdomain)
 	mib[3] = 0;
 	mib[4] = NET_RT_DUMP;
 	mib[5] = 0;
-	mib[6] = rdomain;
+	mib[6] = imsg->rdomain;
 
 	if (sysctl(mib, 7, NULL, &needed, NULL, 0) == -1) {
-		if (rdomain != 0 && errno == EINVAL)
+		if (imsg->rdomain != 0 && errno == EINVAL)
 			return;
 		error("could not get routes");
 	}
@@ -155,7 +155,7 @@ priv_flush_routes_and_arp_cache(int rdomain)
 
 		rtm->rtm_type = RTM_DELETE;
 		rtm->rtm_seq = seqno;
-		rtm->rtm_tableid = rdomain;
+		rtm->rtm_tableid = imsg->rdomain;
 
 		rlen = write(s, next, rtm->rtm_msglen);
 		if (rlen == -1) {
@@ -185,40 +185,26 @@ priv_flush_routes_and_arp_cache(int rdomain)
  * depending on the contents of the gateway parameter.
  */
 void
-add_default_route(int rdomain, struct in_addr addr,
-    struct in_addr gateway)
+add_default_route(int rdomain, struct in_addr addr, struct in_addr gateway)
 {
-	size_t		 len;
-	struct imsg_hdr	 hdr;
-	struct buf	*buf;
+	struct imsg_add_default_route	 imsg;
+	int				 rslt;
 
-	hdr.code = IMSG_ADD_DEFAULT_ROUTE;
-	hdr.len = sizeof(hdr) +
-	    sizeof(len) + sizeof(rdomain) +
-	    sizeof(len) + sizeof(addr) +
-	    sizeof(len) + sizeof(gateway);
+	memset(&imsg, 0, sizeof(imsg));
 
-	buf = buf_open(hdr.len);
-	buf_add(buf, &hdr, sizeof(hdr));
+	imsg.rdomain = rdomain;
+	imsg.addr = addr;
+	imsg.gateway = gateway;
 
-	len = sizeof(rdomain);
-	buf_add(buf, &len, sizeof(len));
-	buf_add(buf, &rdomain, len);
+	rslt = imsg_compose(unpriv_ibuf, IMSG_ADD_DEFAULT_ROUTE, 0, 0, -1,
+	    &imsg, sizeof(imsg));
 
-	len = sizeof(addr);
-	buf_add(buf, &len, sizeof(len));
-	buf_add(buf, &addr, len);
-
-	len = sizeof(gateway);
-	buf_add(buf, &len, sizeof(len));
-	buf_add(buf, &gateway, len);
-
-	buf_close(privfd, buf);
+	if (rslt == -1)
+		warning("add_default_route: imsg_compose: %m");
 }
 
 void
-priv_add_default_route(int rdomain, struct in_addr addr,
-    struct in_addr router)
+priv_add_default_route(struct imsg_add_default_route *imsg)
 {
 	struct rt_msghdr rtm;
 	struct sockaddr_in dest, gateway, mask;
@@ -239,7 +225,7 @@ priv_add_default_route(int rdomain, struct in_addr addr,
 
 	rtm.rtm_version = RTM_VERSION;
 	rtm.rtm_type = RTM_ADD;
-	rtm.rtm_tableid = rdomain;
+	rtm.rtm_tableid = imsg->rdomain;
 	rtm.rtm_priority = 0;
 	rtm.rtm_msglen = sizeof(rtm);
 
@@ -265,10 +251,10 @@ priv_add_default_route(int rdomain, struct in_addr addr,
 	 */
 
 	memset(&gateway, 0, sizeof(gateway));
-	if (bcmp(&router, &addr, sizeof(addr)) != 0) {
+	if (bcmp(&imsg->gateway, &imsg->addr, sizeof(imsg->addr)) != 0) {
 		gateway.sin_len = sizeof(gateway);
 		gateway.sin_family = AF_INET;
-		gateway.sin_addr.s_addr = router.s_addr;
+		gateway.sin_addr.s_addr = imsg->gateway.s_addr;
 
 		rtm.rtm_flags |= RTF_GATEWAY | RTF_STATIC;
 		rtm.rtm_addrs |= RTA_GATEWAY;
@@ -360,39 +346,27 @@ delete_addresses(char *ifname, int rdomain)
 void
 delete_address(char *ifname, int rdomain, struct in_addr addr)
 {
-	size_t		 len;
-	struct imsg_hdr	 hdr;
-	struct buf	*buf;
+	struct imsg_delete_address	 imsg;
+	int				 rslt;
+
+	memset(&imsg, 0, sizeof(imsg));
 
 	/* Note the address we are deleting for RTM_DELADDR filtering! */
 	deleting.s_addr = addr.s_addr;
 
-	hdr.code = IMSG_DELETE_ADDRESS;
-	hdr.len = sizeof(hdr) +
-	    sizeof(len) + strlen(ifname) +
-	    sizeof(len) + sizeof(rdomain) +
-	    sizeof(len) + sizeof(addr);
-
-	buf = buf_open(hdr.len);
-	buf_add(buf, &hdr, sizeof(hdr));
-
-	len = strlen(ifname);
-	buf_add(buf, &len, sizeof(len));
-	buf_add(buf, ifname, len);
-
-	len = sizeof(rdomain);
-	buf_add(buf, &len, sizeof(len));
-	buf_add(buf, &rdomain, len);
+	strlcpy(imsg.ifname, ifname, sizeof(imsg.ifname));
+	imsg.rdomain = rdomain;
+	imsg.addr = addr;
 
-	len = sizeof(addr);
-	buf_add(buf, &len, sizeof(len));
-	buf_add(buf, &addr, len);
+	rslt = imsg_compose(unpriv_ibuf, IMSG_DELETE_ADDRESS, 0, 0 , -1, &imsg,
+	    sizeof(imsg));
 
-	buf_close(privfd, buf);
+	if (rslt == -1)
+		warning("delete_address: imsg_compose: %m");
 }
 
 void
-priv_delete_address(char *ifname, int rdomain, struct in_addr addr)
+priv_delete_address(struct imsg_delete_address *imsg)
 {
 	struct ifaliasreq ifaliasreq;
 	struct rt_msghdr rtm;
@@ -409,16 +383,17 @@ priv_delete_address(char *ifname, int rdomain, struct in_addr addr)
 		error("socket open failed: %m");
 
 	memset(&ifaliasreq, 0, sizeof(ifaliasreq));
-	strncpy(ifaliasreq.ifra_name, ifname, sizeof(ifaliasreq.ifra_name));
+	strncpy(ifaliasreq.ifra_name, imsg->ifname,
+	    sizeof(ifaliasreq.ifra_name));
 
 	in = (struct sockaddr_in *)&ifaliasreq.ifra_addr;
 	in->sin_family = AF_INET;
 	in->sin_len = sizeof(ifaliasreq.ifra_addr);
-	in->sin_addr.s_addr = addr.s_addr;
+	in->sin_addr.s_addr = imsg->addr.s_addr;
 
 	/* SIOCDIFADDR will result in a RTM_DELADDR message we must catch! */
 	if (ioctl(s, SIOCDIFADDR, &ifaliasreq) == -1) {
-		warning("SIOCDIFADDR failed (%s): %m", inet_ntoa(addr));
+		warning("SIOCDIFADDR failed (%s): %m", inet_ntoa(imsg->addr));
 		close(s);
 		return;
 	}
@@ -438,7 +413,7 @@ priv_delete_address(char *ifname, int rdomain, struct in_addr addr)
 
 	rtm.rtm_version = RTM_VERSION;
 	rtm.rtm_type = RTM_DELETE;
-	rtm.rtm_tableid = rdomain;
+	rtm.rtm_tableid = imsg->rdomain;
 	rtm.rtm_priority = 0;
 	rtm.rtm_msglen = sizeof(rtm);
 
@@ -451,7 +426,7 @@ priv_delete_address(char *ifname, int rdomain, struct in_addr addr)
 
 	dest.sin_len = sizeof(dest);
 	dest.sin_family = AF_INET;
-	dest.sin_addr.s_addr = addr.s_addr;
+	dest.sin_addr.s_addr = imsg->addr.s_addr;
 
 	rtm.rtm_addrs |= RTA_DST;
 	rtm.rtm_msglen += sizeof(dest);
@@ -491,44 +466,28 @@ void
 add_address(char *ifname, int rdomain, struct in_addr addr,
     struct in_addr mask)
 {
-	struct buf	*buf;
-	size_t		 len;
-	struct imsg_hdr	 hdr;
+	struct imsg_add_address imsg;
+	int			rslt;
+ 
+	memset(&imsg, 0, sizeof(imsg));
 
+	/* Note the address we are adding for RTM_NEWADDR filtering! */
 	adding = addr;
 
-	hdr.code = IMSG_ADD_ADDRESS;
-	hdr.len = sizeof(hdr) +
-	    sizeof(len) + strlen(ifname) +
-	    sizeof(len) + sizeof(rdomain) +
-	    sizeof(len) + sizeof(addr) +
-	    sizeof(len) + sizeof(mask);
+	strlcpy(imsg.ifname, ifname, sizeof(imsg.ifname));
+	imsg.rdomain = rdomain;
+	imsg.addr = addr;
+	imsg.mask = mask;
+ 
+	rslt = imsg_compose(unpriv_ibuf, IMSG_ADD_ADDRESS, 0, 0, -1, &imsg,
+	    sizeof(imsg));
 
-	buf = buf_open(hdr.len);
-	buf_add(buf, &hdr, sizeof(hdr));
-
-	len = strlen(ifname);
-	buf_add(buf, &len, sizeof(len));
-	buf_add(buf, ifname, len);
-
-	len = sizeof(rdomain);
-	buf_add(buf, &len, sizeof(len));
-	buf_add(buf, &rdomain, len);
-
-	len = sizeof(addr);
-	buf_add(buf, &len, sizeof(len));
-	buf_add(buf, &addr, len);
-
-	len = sizeof(mask);
-	buf_add(buf, &len, sizeof(len));
-	buf_add(buf, &mask, len);
-
-	buf_close(privfd, buf);
+	if (rslt == -1)
+		warning("add_address: imsg_compose: %m");
 }
 
 void
-priv_add_address(char *ifname, int rdomain, struct in_addr addr,
-    struct in_addr mask)
+priv_add_address(struct imsg_add_address *imsg)
 {
 	struct ifaliasreq ifaliasreq;
 	struct rt_msghdr rtm;
@@ -546,24 +505,25 @@ priv_add_address(char *ifname, int rdomain, struct in_addr addr,
 		error("socket open failed: %m");
 
 	memset(&ifaliasreq, 0, sizeof(ifaliasreq));
-	strncpy(ifaliasreq.ifra_name, ifname, sizeof(ifaliasreq.ifra_name));
+	strncpy(ifaliasreq.ifra_name, imsg->ifname,
+	    sizeof(ifaliasreq.ifra_name));
 
 	/* The actual address in ifra_addr. */
 	in = (struct sockaddr_in *)&ifaliasreq.ifra_addr;
 	in->sin_family = AF_INET;
 	in->sin_len = sizeof(ifaliasreq.ifra_addr);
-	in->sin_addr.s_addr = addr.s_addr;
+	in->sin_addr.s_addr = imsg->addr.s_addr;
 
 	/* And the netmask in ifra_mask. */
 	in = (struct sockaddr_in *)&ifaliasreq.ifra_mask;
 	in->sin_family = AF_INET;
 	in->sin_len = sizeof(ifaliasreq.ifra_mask);
-	memcpy(&in->sin_addr.s_addr, &mask, sizeof(mask));
+	memcpy(&in->sin_addr.s_addr, &imsg->mask, sizeof(imsg->mask));
 
 	/* No need to set broadcast address. Kernel can figure it out. */
 
 	if (ioctl(s, SIOCAIFADDR, &ifaliasreq) == -1)
-		warning("SIOCAIFADDR failed (%s): %m", inet_ntoa(addr));
+		warning("SIOCAIFADDR failed (%s): %m", inet_ntoa(imsg->addr));
 
 	close(s);
 
@@ -580,7 +540,7 @@ priv_add_address(char *ifname, int rdomain, struct in_addr addr,
 
 	rtm.rtm_version = RTM_VERSION;
 	rtm.rtm_type = RTM_ADD;
-	rtm.rtm_tableid = rdomain;
+	rtm.rtm_tableid = imsg->rdomain;
 	rtm.rtm_priority = 0;
 	rtm.rtm_msglen = sizeof(rtm);
 
@@ -593,7 +553,7 @@ priv_add_address(char *ifname, int rdomain, struct in_addr addr,
 
 	dest.sin_len = sizeof(dest);
 	dest.sin_family = AF_INET;
-	dest.sin_addr.s_addr = addr.s_addr;
+	dest.sin_addr.s_addr = imsg->addr.s_addr;
 
 	rtm.rtm_addrs |= RTA_DST;
 	rtm.rtm_msglen += sizeof(dest);
diff --git a/sbin/dhclient/privsep.c b/sbin/dhclient/privsep.c
index 5ab2c2a6759..e6f6dd0fb86 100644
--- a/sbin/dhclient/privsep.c
+++ b/sbin/dhclient/privsep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: privsep.c,v 1.23 2012/11/14 15:47:41 krw Exp $ */
+/*	$OpenBSD: privsep.c,v 1.24 2012/11/23 15:25:47 krw Exp $ */
 
 /*
  * Copyright (c) 2004 Henning Brauer <henning@openbsd.org>
@@ -19,311 +19,68 @@
 #include "dhcpd.h"
 #include "privsep.h"
 
-struct buf *
-buf_open(size_t len)
-{
-	struct buf	*buf;
-
-	if ((buf = calloc(1, sizeof(struct buf))) == NULL)
-		error("buf_open: %m");
-	if ((buf->buf = malloc(len)) == NULL) {
-		free(buf);
-		error("buf_open: %m");
-	}
-	buf->size = len;
-
-	return (buf);
-}
-
-void
-buf_add(struct buf *buf, void *data, size_t len)
-{
-	if (len == 0)
-		return;
-
-	if (buf->wpos + len > buf->size)
-		error("buf_add: %m");
-
-	memcpy(buf->buf + buf->wpos, data, len);
-	buf->wpos += len;
-}
-
-void
-buf_close(int sock, struct buf *buf)
-{
-	ssize_t	n;
-
-	do {
-		n = write(sock, buf->buf + buf->rpos, buf->size - buf->rpos);
-		if (n == 0)			/* connection closed */
-			error("buf_close (connection closed)");
-		if (n != -1 && n < buf->size - buf->rpos)
-			error("buf_close (short write): %m");
-
-	} while (n == -1 && (errno == EAGAIN || errno == EINTR));
-
-	if (n == -1)
-		error("buf_close: %m");
-
-	free(buf->buf);
-	free(buf);
-}
-
-void
-buf_read(int sock, void *buf, size_t nbytes)
-{
-	ssize_t	n;
-
-	do {
-		n = read(sock, buf, nbytes);
-		if (n == 0) {			/* connection closed */
-#ifdef DEBUG
-			debug("buf_read (connection closed)");
-#endif
-			exit(1);
-		}
-		if (n != -1 && n < nbytes)
-			error("buf_read (short read): %m");
-	} while (n == -1 && (errno == EINTR || errno == EAGAIN));
-
-	if (n == -1)
-		error("buf_read: %m");
-}
+#include <sys/queue.h>
+#include <sys/uio.h>
 
 void
-dispatch_imsg(int fd)
+dispatch_imsg(struct imsgbuf *ibuf)
 {
-	struct imsg_hdr		 hdr;
-	struct in_addr		*addr, *mask, *gateway;
-	char			*ifname, *contents;
-	size_t			 totlen, len;
-	int			 rdomain;
-
-	buf_read(fd, &hdr, sizeof(hdr));
-
-	switch (hdr.code) {
-	case IMSG_DELETE_ADDRESS:
-		totlen = sizeof(hdr);
-		ifname = NULL;
-		addr = NULL;
-		if (hdr.len < totlen + sizeof(len))
-			error("IMSG_DELETE_ADDRESS missing ifname length");
-		buf_read(fd, &len, sizeof(len));
-		totlen += sizeof(len);
-		if (len == SIZE_T_MAX) {
-			error("IMSG_DELETE_ADDRESS invalid ifname length");
-		} else if (len > 0) {
-			if (hdr.len < totlen + len)
-				error("IMSG_DELETE_ADDRESS short ifname");
-			if ((ifname = calloc(1, len + 1)) == NULL)
-				error("%m");
-			buf_read(fd, ifname, len);
-			totlen += len;
-		} else
-			error("IMSG_DELETE_ADDRESS ifname missing");
-
-		if (hdr.len < totlen + sizeof(len))
-			error("IMSG_DELETE_ADDRESS missing rdomain length");
-		buf_read(fd, &len, sizeof(len));
-		totlen += sizeof(len);
-		if (len == SIZE_T_MAX) {
-			error("IMSG_DELETE_ADDRESS invalid rdomain length");
-		} else if (len > 0) {
-			if (hdr.len < totlen + len)
-				error("IMSG_DELETE_ADDRESS short rdomain");
-			buf_read(fd, &rdomain, len);
-			totlen += len;
-		} else
-			error("IMSG_DELETE_ADDRESS rdomain missing");
-
-		if (hdr.len < totlen + sizeof(len))
-			error("IMSG_DELETE_ADDRESS missing addr length");
-		buf_read(fd, &len, sizeof(len));
-		totlen += sizeof(len);
-		if (len == SIZE_T_MAX) {
-			error("IMSG_DELETE_ADDRESS invalid addr");
-		} else if (len == sizeof(*addr)) {
-			if ((addr = calloc(1, len)) == NULL)
-				error("%m");
-			buf_read(fd, addr, len);
-			totlen += len;
-		} else {
-			error("IMSG_DELETE_ADDRESS addr missing %zu", len);
-		}
-
-		priv_delete_address(ifname, rdomain, *addr);
-		free(ifname);
-		free(addr);
-		break;
-
-	case IMSG_ADD_ADDRESS:
-		totlen = sizeof(hdr);
-		ifname = NULL;
-		addr = NULL;
-		mask = NULL;
-		if (hdr.len < totlen + sizeof(len))
-			error("IMSG_ADD_ADDRESS missing ifname length");
-		buf_read(fd, &len, sizeof(len));
-		totlen += sizeof(len);
-		if (len == SIZE_T_MAX) {
-			error("IMSG_ADD_ADDRESS invalid ifname length");
-		} else if (len > 0) {
-			if (hdr.len < totlen + len)
-				error("IMSG_ADD_ADDRESS short ifname");
-			if ((ifname = calloc(1, len + 1)) == NULL)
-				error("%m");
-			buf_read(fd, ifname, len);
-			totlen += len;
-		} else
-			error("IMSG_ADD_ADDRESS ifname missing");
-
-		if (hdr.len < totlen + sizeof(len))
-			error("IMSG_ADD_ADDRESS missing rdomain length");
-		buf_read(fd, &len, sizeof(len));
-		totlen += sizeof(len);
-		if (len == SIZE_T_MAX) {
-			error("IMSG_ADD_ADDRESS invalid rdomain length");
-		} else if (len > 0) {
-			if (hdr.len < totlen + len)
-				error("IMSG_ADD_ADDRESS short rdomain");
-			buf_read(fd, &rdomain, len);
-			totlen += len;
-		} else
-			error("IMSG_ADD_ADDRESS rdomain missing");
-
-		if (hdr.len < totlen + sizeof(len))
-			error("IMSG_ADD_ADDRESS missing addr length");
-		buf_read(fd, &len, sizeof(len));
-		totlen += sizeof(len);
-		if (len == SIZE_T_MAX) {
-			error("IMSG_ADD_ADDRESS invalid addr");
-		} else if (len == sizeof(*addr)) {
-			if ((addr = calloc(1, len)) == NULL)
-				error("%m");
-			buf_read(fd, addr, len);
-			totlen += len;
-		} else {
-			error("IMSG_ADD_ADDRESS addr missing %zu", len);
-		}
-
-		if (hdr.len < totlen + sizeof(len))
-			error("IMSG_ADD_ADDRESS missing mask length");
-		buf_read(fd, &len, sizeof(len));
-		totlen += sizeof(len);
-		mask = NULL;
-		if (len == SIZE_T_MAX) {
-			error("IMSG_ADD_ADDRESS invalid mask");
-		} else if (len == sizeof(*mask)) {
-			if ((mask = calloc(1, len)) == NULL)
-				error("%m");
-			buf_read(fd, mask, len);
-			totlen += len;
-		} else {
-			error("IMSG_ADD_ADDRESS mask missing %zu", len);
-		}
-
-		priv_add_address(ifname, rdomain, *addr, *mask);
-		free(ifname);
-		free(addr);
-		free(mask);
-		break;
-
-	case IMSG_FLUSH_ROUTES:
-		totlen = sizeof(hdr);
-		if (hdr.len < totlen + sizeof(len))
-			error("IMSG_FLUSH_ROUTES missing rdomain length");
-		buf_read(fd, &len, sizeof(len));
-		totlen += sizeof(len);
-		if (len == SIZE_T_MAX) {
-			error("IMSG_FLUSH_ROUTES invalid rdomain length");
-		} else if (len > 0) {
-			if (hdr.len < totlen + len)
-				error("IMSG_FLUSH_ROUTES short rdomain");
-			buf_read(fd, &rdomain, len);
-			totlen += len;
-		} else
-			error("IMSG_FLUSH_ROUTES rdomain missing");
-
-		priv_flush_routes_and_arp_cache(rdomain);
-		break;
-
-	case IMSG_ADD_DEFAULT_ROUTE:
-		totlen = sizeof(hdr);
-		addr = NULL;
-		gateway = NULL;
-		if (hdr.len < totlen + sizeof(len))
-			error("IMSG_ADD_DEFAULT_ROUTE missing rdomain length");
-		buf_read(fd, &len, sizeof(len));
-		totlen += sizeof(len);
-		if (len == SIZE_T_MAX) {
-			error("IMSG_ADD_DEFAULT_ROUTE invalid rdomain length");
-		} else if (len > 0) {
-			if (hdr.len < totlen + len)
-				error("IMSG_FLUSH_ROUTES short rdomain");
-			buf_read(fd, &rdomain, len);
-			totlen += len;
-		} else
-			error("IMSG_ADD_DEFAULT_ROUTE rdomain missing");
-
-		if (hdr.len < totlen + sizeof(len))
-			error("IMSG_ADD_DEFAULT_ROUTE missing addr length");
-		buf_read(fd, &len, sizeof(len));
-		totlen += sizeof(len);
-		if (len == SIZE_T_MAX) {
-			error("IMSG_ADD_DEFAULT_ROUTE invalid addr");
-		} else if (len == sizeof(*addr)) {
-			if ((addr = calloc(1, len)) == NULL)
-				error("%m");
-			buf_read(fd, addr, len);
-			totlen += len;
-		} else {
-			error("IMSG_ADD_DEFAULT_ROUTE addr missing %zu",
-			    len);
-		}
-
-		if (hdr.len < totlen + sizeof(len))
-			error("IMSG_ADD_DEFAULT_ROUTE missing gateway length");
-		buf_read(fd, &len, sizeof(len));
-		totlen += sizeof(len);
-		if (len == SIZE_T_MAX) {
-			error("IMSG_ADD_DEFAULT_ROUTE invalid gateway");
-		} else if (len == sizeof(*gateway)) {
-			if ((gateway = calloc(1, len)) == NULL)
-				error("%m");
-			buf_read(fd, gateway, len);
-			totlen += len;
-		} else {
-			error("IMSG_ADD_DEFAULT_ROUTE gateway missing %zu",
-			    len);
-		}
-
-		priv_add_default_route(rdomain, *addr, *gateway);
-		free(addr);
-		free(gateway);
-		break;
-	case IMSG_NEW_RESOLV_CONF:
-		totlen = sizeof(hdr);
-		contents = NULL;
-
-		if (hdr.len < totlen + sizeof(len))
-			error("IMSG_NEW_RESOLV_CONF missing contents length");
-		buf_read(fd, &len, sizeof(len));
-		totlen += sizeof(len);
-		if (len == SIZE_T_MAX) {
-			error("IMSG_NEW_RESOLV_CONF invalid contents length");
-		} else if (len > 0) {
-			if (hdr.len < totlen + len)
-				error("IMSG_NEW_RESOLV_CONF short contents");
-			if ((contents = calloc(1, len + 1)) == NULL)
-				error("%m");
-			buf_read(fd, contents, len);
-			totlen += len;
+	struct imsg	 imsg;
+	ssize_t		 n;
+
+	for (;;) {
+		if ((n = imsg_get(ibuf, &imsg)) == -1)
+			error("dispatch_imsg: imsg_get failure: %m");
+
+		if (n == 0)
+			break;
+
+		switch (imsg.hdr.type) {
+		case IMSG_DELETE_ADDRESS:
+			if (imsg.hdr.len != IMSG_HEADER_SIZE +
+			    sizeof(struct imsg_delete_address))
+				warning("bad IMSG_DELETE_ADDRESS");
+			else
+				priv_delete_address(imsg.data);
+			break;
+
+		case IMSG_ADD_ADDRESS:
+			if (imsg.hdr.len != IMSG_HEADER_SIZE +
+			    sizeof(struct imsg_add_address))
+				warning("bad IMSG_ADD_ADDRESS");
+			else
+				priv_add_address(imsg.data);
+			break;
+
+		case IMSG_FLUSH_ROUTES:
+			if (imsg.hdr.len != IMSG_HEADER_SIZE +
+			    sizeof(struct imsg_flush_routes))
+				warning("bad IMSG_FLUSH_ROUTES");
+			else
+				priv_flush_routes_and_arp_cache(imsg.data);
+			break;
+
+		case IMSG_ADD_DEFAULT_ROUTE:
+			if (imsg.hdr.len != IMSG_HEADER_SIZE +
+			    sizeof(struct imsg_add_default_route))
+				warning("bad IMSG_ADD_DEFAULT_ROUTE");
+			else
+				priv_add_default_route(imsg.data);
+			break;
+
+		case IMSG_NEW_RESOLV_CONF:
+			if (imsg.hdr.len != IMSG_HEADER_SIZE +
+			    sizeof(struct imsg_resolv_conf))
+				warning("bad IMSG_NEW_RESOLV_CONF");
+			else
+				priv_resolv_conf(imsg.data);
+			break;
+
+		default:
+			warning("received unknown message, code %d",
+			    imsg.hdr.type);
 		}
 
-		priv_resolv_conf(contents);
-		free(contents);
-		break;
-	default:
-		error("received unknown message, code %d", hdr.code);
+		imsg_free(&imsg);
 	}
 }
diff --git a/sbin/dhclient/privsep.h b/sbin/dhclient/privsep.h
index 59300e00f53..a72294bb910 100644
--- a/sbin/dhclient/privsep.h
+++ b/sbin/dhclient/privsep.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: privsep.h,v 1.6 2012/10/30 18:39:44 krw Exp $ */
+/*	$OpenBSD: privsep.h,v 1.7 2012/11/23 15:25:47 krw Exp $ */
 
 /*
  * Copyright (c) 2004 Henning Brauer <henning@openbsd.org>
@@ -16,14 +16,13 @@
  * OF OR IN CONNECTION WITH THE USE, ABUSE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
-#include <sys/types.h>
+#include <arpa/inet.h>
 
-struct buf {
-	u_char			*buf;
-	size_t			 size;
-	size_t			 wpos;
-	size_t			 rpos;
-};
+#include <imsg.h>
+
+#define MAXRESOLVCONFSIZE	2048
+
+extern struct imsgbuf *ibuf;
 
 enum imsg_code {
 	IMSG_NONE,
@@ -34,13 +33,36 @@ enum imsg_code {
 	IMSG_NEW_RESOLV_CONF
 };
 
-struct imsg_hdr {
-	enum imsg_code	code;
-	size_t		len;
+struct imsg_delete_address {
+	char	ifname[IFNAMSIZ];
+	int	rdomain;
+	struct in_addr addr;
+};
+
+struct imsg_add_address {
+	char 	ifname[IFNAMSIZ];
+	int	rdomain;
+	struct	in_addr	addr;
+	struct	in_addr mask;
+};
+
+struct imsg_flush_routes {
+	int	rdomain;
+};
+
+struct imsg_add_default_route {
+	int		rdomain;
+	struct in_addr	addr;
+	struct in_addr	gateway;
+};
+
+struct imsg_resolv_conf {
+	char	contents[MAXRESOLVCONFSIZE];
 };
 
-struct buf	*buf_open(size_t);
-void		 buf_add(struct buf *, void *, size_t);
-void		 buf_close(int, struct buf *);
-void		 buf_read(int, void *, size_t);
-void		 dispatch_imsg(int);
+void	dispatch_imsg(struct imsgbuf *);
+void	priv_resolv_conf(struct imsg_resolv_conf *);
+void	priv_delete_address(struct imsg_delete_address *);
+void	priv_add_address(struct imsg_add_address *);
+void	priv_flush_routes_and_arp_cache(struct imsg_flush_routes *);
+void	priv_add_default_route(struct imsg_add_default_route *);