From: Roy Marples <roy@marples.name>
Date: Sun, 17 Feb 2019 09:36:11 +0000 (+0000)
Subject: Remove the send/recv structures from dhcpcd context and allocate
X-Git-Tag: v7.2.0~34
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5fed9d4382316708ce6042e5707b6bb9be05c214;p=thirdparty%2Fdhcpcd.git

Remove the send/recv structures from dhcpcd context and allocate
on stack as and when required.
Rather than peaking and checking for truncation for receiving,
just allocate a large enough buffer upfront.
---

diff --git a/src/common.c b/src/common.c
index 6d06604d..0214af2c 100644
--- a/src/common.c
+++ b/src/common.c
@@ -200,51 +200,3 @@ read_hwaddr_aton(uint8_t **data, const char *path)
 	fclose(fp);
 	return len;
 }
-
-ssize_t
-recvmsg_realloc(int fd, struct msghdr *msg, int flags)
-{
-	struct iovec *iov;
-	ssize_t slen;
-	size_t len;
-	void *n;
-
-	assert(msg != NULL);
-	assert(msg->msg_iov != NULL && msg->msg_iovlen > 0);
-	assert((flags & (MSG_PEEK | MSG_TRUNC)) == 0);
-
-	/* Assume we are reallocing the last iovec. */
-	iov = &msg->msg_iov[msg->msg_iovlen - 1];
-
-	for (;;) {
-		/* Passing MSG_TRUNC should return the actual size needed. */
-		slen = recvmsg(fd, msg, flags | MSG_PEEK | MSG_TRUNC);
-		if (slen == -1)
-			return -1;
-		if (!(msg->msg_flags & MSG_TRUNC))
-			break;
-
-		len = (size_t)slen;
-
-		/* Some kernels return the size of the receive buffer
-		 * on truncation, not the actual size needed.
-		 * So grow the buffer and try again. */
-		if (iov->iov_len == len)
-			len++;
-		else if (iov->iov_len > len)
-			break;
-		len = roundup(len, IOVEC_BUFSIZ);
-		if ((n = realloc(iov->iov_base, len)) == NULL)
-			return -1;
-		iov->iov_base = n;
-		iov->iov_len = len;
-	}
-
-	slen = recvmsg(fd, msg, flags);
-	if (slen != -1 && msg->msg_flags & MSG_TRUNC) {
-		/* This should not be possible ... */
-		errno = ENOBUFS;
-		return -1;
-	}
-	return slen;
-}
diff --git a/src/common.h b/src/common.h
index 713dd1d3..8dfd251c 100644
--- a/src/common.h
+++ b/src/common.h
@@ -181,6 +181,4 @@ ssize_t addvard(char ***, const char *, const char *, size_t);
 const char *hwaddr_ntoa(const void *, size_t, char *, size_t);
 size_t hwaddr_aton(uint8_t *, const char *);
 size_t read_hwaddr_aton(uint8_t **, const char *);
-
-ssize_t recvmsg_realloc(int, struct msghdr *, int);
 #endif
diff --git a/src/dhcp6.c b/src/dhcp6.c
index b5b035f2..c50efb66 100644
--- a/src/dhcp6.c
+++ b/src/dhcp6.c
@@ -168,7 +168,7 @@ static const char * const dhcp6_statuses[] = {
 	"No Prefix Available"
 };
 
-static void dhcp6_bind(struct interface *, const char *);
+static void dhcp6_bind(struct interface *, const char *, const char *);
 static void dhcp6_failinform(void *);
 static int dhcp6_listen(struct dhcpcd_ctx *, struct ipv6_addr *);
 static void dhcp6_recvaddr(void *);
@@ -1157,9 +1157,12 @@ dhcp6_update_auth(struct interface *ifp, struct dhcp6_message *m, size_t len)
 static int
 dhcp6_sendmessage(struct interface *ifp, void (*callback)(void *))
 {
-	struct dhcp6_state *state;
-	struct dhcpcd_ctx *ctx;
-	struct sockaddr_in6 dst;
+	struct dhcp6_state *state = D6_STATE(ifp);
+	struct dhcpcd_ctx *ctx = ifp->ctx;
+	struct sockaddr_in6 dst = {
+	    .sin6_family = AF_INET6,
+	    .sin6_port = htons(DHCP6_SERVER_PORT),
+	};
 	struct timespec RTprev;
 	double rnd;
 	time_t ms;
@@ -1168,18 +1171,22 @@ dhcp6_sendmessage(struct interface *ifp, void (*callback)(void *))
 	const struct in6_addr alldhcp = IN6ADDR_LINKLOCAL_ALLDHCP_INIT;
 	struct ipv6_addr *lla;
 	int s;
+	struct iovec iov = {
+	    .iov_base = state->send, .iov_len = state->send_len,
+	};
+	unsigned char ctl[CMSG_SPACE(sizeof(struct in6_pktinfo))] = { 0 };
+	struct msghdr msg = {
+	    .msg_name = &dst, .msg_namelen = sizeof(dst),
+	    .msg_iov = &iov, .msg_iovlen = 1,
+	};
 
 	if (!callback && ifp->carrier <= LINK_DOWN)
 		return 0;
 
-	memset(&dst, 0, sizeof(dst));
-	dst.sin6_family = AF_INET6;
-	dst.sin6_port = htons(DHCP6_SERVER_PORT);
 #ifdef HAVE_SA_LEN
 	dst.sin6_len = sizeof(dst);
 #endif
 
-	state = D6_STATE(ifp);
 	lla = ipv6_linklocal(ifp);
 	/* We need to ensure we have sufficient scope to unicast the address */
 	/* XXX FIXME: We should check any added addresses we have like from
@@ -1280,7 +1287,7 @@ logsend:
 		/* Wait the initial delay */
 		if (state->IMD != 0) {
 			state->IMD = 0;
-			eloop_timeout_add_tv(ifp->ctx->eloop,
+			eloop_timeout_add_tv(ctx->eloop,
 			    &state->RT, callback, ifp);
 			return 0;
 		}
@@ -1301,31 +1308,21 @@ logsend:
 	}
 #endif
 
-	ctx = ifp->ctx;
-	ctx->sndhdr.msg_name = (void *)&dst;
-	ctx->sndhdr.msg_iov[0].iov_base = state->send;
-	ctx->sndhdr.msg_iov[0].iov_len = state->send_len;
-
 	/* Set the outbound interface */
 	if (IN6_ARE_ADDR_EQUAL(&dst.sin6_addr, &alldhcp)) {
 		struct cmsghdr *cm;
-		struct in6_pktinfo pi;
+		struct in6_pktinfo pi = { .ipi6_ifindex = ifp->index };
 
 		dst.sin6_scope_id = ifp->index;
-		cm = CMSG_FIRSTHDR(&ctx->sndhdr);
+		msg.msg_control = ctl;
+		msg.msg_controllen = sizeof(ctl);
+		cm = CMSG_FIRSTHDR(&msg);
 		if (cm == NULL) /* unlikely */
 			return -1;
 		cm->cmsg_level = IPPROTO_IPV6;
 		cm->cmsg_type = IPV6_PKTINFO;
 		cm->cmsg_len = CMSG_LEN(sizeof(pi));
-		memset(&pi, 0, sizeof(pi));
-		pi.ipi6_ifindex = ifp->index;
 		memcpy(CMSG_DATA(cm), &pi, sizeof(pi));
-	} else {
-		/* Remove the control buffer as we're not dictating
-		 * which interface to use for outgoing messages. */
-		ctx->sndhdr.msg_control = NULL;
-		ctx->sndhdr.msg_controllen = 0;
 	}
 
 	if (ctx->dhcp6_fd != -1)
@@ -1337,7 +1334,7 @@ logsend:
 		return -1;
 	}
 
-	if (sendmsg(s, &ctx->sndhdr, 0) == -1) {
+	if (sendmsg(s, &msg, 0) == -1) {
 		logerr("%s: %s: sendmsg", __func__, ifp->name);
 		/* Allow DHCPv6 to continue .... the errors
 		 * would be rate limited by the protocol.
@@ -1345,19 +1342,13 @@ logsend:
 		 * associate with an access point. */
 	}
 
-	/* Restore the control buffer assignment. */
-	if (!IN6_ARE_ADDR_EQUAL(&dst.sin6_addr, &alldhcp)) {
-		ctx->sndhdr.msg_control = ctx->sndbuf;
-		ctx->sndhdr.msg_controllen = sizeof(ctx->sndbuf);
-	}
-
 	state->RTC++;
 	if (callback) {
 		if (state->MRC == 0 || state->RTC < state->MRC)
-			eloop_timeout_add_tv(ifp->ctx->eloop,
+			eloop_timeout_add_tv(ctx->eloop,
 			    &state->RT, callback, ifp);
 		else if (state->MRC != 0 && state->MRCcallback)
-			eloop_timeout_add_tv(ifp->ctx->eloop,
+			eloop_timeout_add_tv(ctx->eloop,
 			    &state->RT, state->MRCcallback, ifp);
 		else
 			logwarnx("%s: sent %d times with no reply",
@@ -1650,7 +1641,7 @@ dhcp6_fail(struct interface *ifp)
 		break;
 	}
 
-	dhcp6_bind(ifp, NULL);
+	dhcp6_bind(ifp, NULL, NULL);
 
 	switch (state->state) {
 	case DH6S_BOUND:
@@ -2927,7 +2918,7 @@ dhcp6_find_delegates(struct interface *ifp)
 #endif
 
 static void
-dhcp6_bind(struct interface *ifp, const char *op)
+dhcp6_bind(struct interface *ifp, const char *op, const char *sfrom)
 {
 	struct dhcp6_state *state = D6_STATE(ifp);
 	bool has_new = false;
@@ -2943,8 +2934,7 @@ dhcp6_bind(struct interface *ifp, const char *op)
 	}
 	lognewinfo = has_new ? loginfox : logdebugx;
 	if (op != NULL)
-		lognewinfo("%s: %s received from %s",
-		    ifp->name, op, ifp->ctx->sfrom);
+		lognewinfo("%s: %s received from %s", ifp->name, op, sfrom);
 
 	state->reason = NULL;
 	if (state->state != DH6S_ITIMEDOUT)
@@ -3176,7 +3166,8 @@ dhcp6_bind(struct interface *ifp, const char *op)
 }
 
 static void
-dhcp6_recvif(struct interface *ifp, struct dhcp6_message *r, size_t len)
+dhcp6_recvif(struct interface *ifp, const char *sfrom,
+    struct dhcp6_message *r, size_t len)
 {
 	struct dhcpcd_ctx *ctx;
 	size_t i;
@@ -3211,8 +3202,7 @@ dhcp6_recvif(struct interface *ifp, struct dhcp6_message *r, size_t len)
 	}
 
 	if (dhcp6_findmoption(r, len, D6_OPTION_SERVERID, NULL) == NULL) {
-		logdebugx("%s: no DHCPv6 server ID from %s",
-		    ifp->name, ctx->sfrom);
+		logdebugx("%s: no DHCPv6 server ID from %s", ifp->name, sfrom);
 		return;
 	}
 
@@ -3225,14 +3215,14 @@ dhcp6_recvif(struct interface *ifp, struct dhcp6_message *r, size_t len)
 		    !dhcp6_findmoption(r, len, (uint16_t)opt->option, NULL))
 		{
 			logwarnx("%s: reject DHCPv6 (no option %s) from %s",
-			    ifp->name, opt->var, ctx->sfrom);
+			    ifp->name, opt->var, sfrom);
 			return;
 		}
 		if (has_option_mask(ifo->rejectmask6, opt->option) &&
 		    dhcp6_findmoption(r, len, (uint16_t)opt->option, NULL))
 		{
 			logwarnx("%s: reject DHCPv6 (option %s) from %s",
-			    ifp->name, opt->var, ctx->sfrom);
+			    ifp->name, opt->var, sfrom);
 			return;
 		}
 	}
@@ -3245,7 +3235,7 @@ dhcp6_recvif(struct interface *ifp, struct dhcp6_message *r, size_t len)
 		    (uint8_t *)r, len, 6, r->type, auth, auth_len) == NULL)
 		{
 			logerr("%s: authentication failed from %s",
-			    ifp->name, ctx->sfrom);
+			    ifp->name, sfrom);
 			return;
 		}
 		if (state->auth.token)
@@ -3256,11 +3246,10 @@ dhcp6_recvif(struct interface *ifp, struct dhcp6_message *r, size_t len)
 	} else if (ifo->auth.options & DHCPCD_AUTH_SEND) {
 		if (ifo->auth.options & DHCPCD_AUTH_REQUIRE) {
 			logerr("%s: no authentication from %s",
-			    ifp->name, ctx->sfrom);
+			    ifp->name, sfrom);
 			return;
 		}
-		logwarnx("%s: no authentication from %s",
-		    ifp->name, ctx->sfrom);
+		logwarnx("%s: no authentication from %s", ifp->name, sfrom);
 	}
 #endif
 
@@ -3274,8 +3263,7 @@ dhcp6_recvif(struct interface *ifp, struct dhcp6_message *r, size_t len)
 				return;
 			break;
 		case DH6S_CONFIRM:
-			if (dhcp6_validatelease(ifp, r, len,
-						ctx->sfrom, NULL) == -1)
+			if (dhcp6_validatelease(ifp, r, len, sfrom, NULL) == -1)
 			{
 				dhcp6_startdiscover(ifp);
 				return;
@@ -3297,8 +3285,7 @@ dhcp6_recvif(struct interface *ifp, struct dhcp6_message *r, size_t len)
 		case DH6S_REQUEST: /* FALLTHROUGH */
 		case DH6S_RENEW: /* FALLTHROUGH */
 		case DH6S_REBIND:
-			if (dhcp6_validatelease(ifp, r, len,
-			    ctx->sfrom, NULL) == -1)
+			if (dhcp6_validatelease(ifp, r, len, sfrom, NULL) == -1)
 			{
 				/*
 				 * If we can't use the lease, fallback to
@@ -3366,7 +3353,7 @@ dhcp6_recvif(struct interface *ifp, struct dhcp6_message *r, size_t len)
 				logerrx("%s: invalid INF_MAX_RT %u",
 				    ifp->name, max_rt);
 		}
-		if (dhcp6_validatelease(ifp, r, len, ctx->sfrom, NULL) == -1)
+		if (dhcp6_validatelease(ifp, r, len, sfrom, NULL) == -1)
 			return;
 		break;
 	case DHCP6_RECONFIGURE:
@@ -3374,12 +3361,12 @@ dhcp6_recvif(struct interface *ifp, struct dhcp6_message *r, size_t len)
 		if (auth == NULL) {
 #endif
 			logerrx("%s: unauthenticated %s from %s",
-			    ifp->name, op, ctx->sfrom);
+			    ifp->name, op, sfrom);
 			if (ifo->auth.options & DHCPCD_AUTH_REQUIRE)
 				return;
 #ifdef AUTH
 		}
-		loginfox("%s: %s from %s", ifp->name, op, ctx->sfrom);
+		loginfox("%s: %s from %s", ifp->name, op, sfrom);
 		o = dhcp6_findmoption(r, len, D6_OPTION_RECONF_MSG, &ol);
 		if (o == NULL) {
 			logerrx("%s: missing Reconfigure Message option",
@@ -3456,10 +3443,10 @@ dhcp6_recvif(struct interface *ifp, struct dhcp6_message *r, size_t len)
 			ia = TAILQ_FIRST(&state->addrs);
 		if (ia == NULL)
 			loginfox("%s: ADV (no address) from %s",
-			    ifp->name, ctx->sfrom);
+			    ifp->name, sfrom);
 		else
 			loginfox("%s: ADV %s from %s",
-			    ifp->name, ia->saddr, ctx->sfrom);
+			    ifp->name, ia->saddr, sfrom);
 		if (ifp->ctx->options & DHCPCD_TEST)
 			break;
 		dhcp6_startrequest(ifp);
@@ -3467,33 +3454,44 @@ dhcp6_recvif(struct interface *ifp, struct dhcp6_message *r, size_t len)
 	}
 	}
 
-	dhcp6_bind(ifp, op);
+	dhcp6_bind(ifp, op, sfrom);
 }
 
 static void
 dhcp6_recv(struct dhcpcd_ctx *ctx, struct ipv6_addr *ia)
 {
+	struct sockaddr_in6 from;
+	unsigned char buf[64 * 1024]; /* Maximum UDP message size */
+	struct iovec iov = {
+		.iov_base = buf,
+		.iov_len = sizeof(buf),
+	};
+	unsigned char ctl[CMSG_SPACE(sizeof(struct in6_pktinfo))] = { 0 };
+	struct msghdr msg = {
+	    .msg_name = &from, .msg_namelen = sizeof(from),
+	    .msg_iov = &iov, .msg_iovlen = 1,
+	    .msg_control = ctl, .msg_controllen = sizeof(ctl),
+	};
 	int s;
 	size_t len;
 	ssize_t bytes;
+	char sfrom[INET6_ADDRSTRLEN];
 	struct interface *ifp;
 	struct dhcp6_message *r;
 	const struct dhcp6_state *state;
 	uint8_t *o;
 	uint16_t ol;
 
-	ctx->rcvhdr.msg_controllen = CMSG_SPACE(sizeof(struct in6_pktinfo));
 	s = ia != NULL ? ia->dhcp6_fd : ctx->dhcp6_fd;
-	bytes = recvmsg_realloc(s, &ctx->rcvhdr, 0);
+	bytes = recvmsg(s, &msg, 0);
 	if (bytes == -1) {
-		logerr("%s: recvmsg_realloc", __func__);
+		logerr(__func__);
 		return;
 	}
 	len = (size_t)bytes;
-	ctx->sfrom = inet_ntop(AF_INET6, &ctx->from.sin6_addr,
-	    ctx->ntopbuf, sizeof(ctx->ntopbuf));
+	inet_ntop(AF_INET6, &from.sin6_addr, sfrom, sizeof(sfrom));
 	if (len < sizeof(struct dhcp6_message)) {
-		logerrx("DHCPv6 packet too short from %s", ctx->sfrom);
+		logerrx("DHCPv6 packet too short from %s", sfrom);
 		return;
 	}
 
@@ -3504,9 +3502,9 @@ dhcp6_recv(struct dhcpcd_ctx *ctx, struct ipv6_addr *ia)
 		struct in6_pktinfo pi;
 
 		pi.ipi6_ifindex = 0;
-		for (cm = (struct cmsghdr *)CMSG_FIRSTHDR(&ctx->rcvhdr);
+		for (cm = (struct cmsghdr *)CMSG_FIRSTHDR(&msg);
 		    cm;
-		    cm = (struct cmsghdr *)CMSG_NXTHDR(&ctx->rcvhdr, cm))
+		    cm = (struct cmsghdr *)CMSG_NXTHDR(&msg, cm))
 		{
 			if (cm->cmsg_level != IPPROTO_IPV6)
 				continue;
@@ -3519,7 +3517,7 @@ dhcp6_recv(struct dhcpcd_ctx *ctx, struct ipv6_addr *ia)
 		}
 		if (pi.ipi6_ifindex == 0) {
 			logerrx("DHCPv6 reply did not contain index from %s",
-			    ctx->sfrom);
+			    sfrom);
 			return;
 		}
 
@@ -3529,35 +3527,35 @@ dhcp6_recv(struct dhcpcd_ctx *ctx, struct ipv6_addr *ia)
 		}
 		if (ifp == NULL) {
 			logerrx("DHCPv6 reply for unexpected interface from %s",
-			    ctx->sfrom);
+			    sfrom);
 			return;
 		}
 	}
 
-	r = (struct dhcp6_message *)ctx->rcvhdr.msg_iov[0].iov_base;
+	r = (struct dhcp6_message *)buf;
 	o = dhcp6_findmoption(r, len, D6_OPTION_CLIENTID, &ol);
 	if (o == NULL || ol != ctx->duid_len ||
 	    memcmp(o, ctx->duid, ol) != 0)
 	{
 		logdebugx("%s: incorrect client ID from %s",
-		    ifp->name, ctx->sfrom);
+		    ifp->name, sfrom);
 		return;
 	}
 
 	if (dhcp6_findmoption(r, len, D6_OPTION_SERVERID, NULL) == NULL) {
 		logdebugx("%s: no DHCPv6 server ID from %s",
-		    ifp->name, ctx->sfrom);
+		    ifp->name, sfrom);
 		return;
 	}
 
 	if (r->type == DHCP6_RECONFIGURE) {
 		logdebugx("%s: RECONFIGURE6 recv from %s,"
 		    " sending to all interfaces",
-		    ifp->name, ctx->sfrom);
+		    ifp->name, sfrom);
 		TAILQ_FOREACH(ifp, ctx->ifaces, next) {
 			state = D6_CSTATE(ifp);
 			if (state != NULL && state->send != NULL)
-				dhcp6_recvif(ifp, r, len);
+				dhcp6_recvif(ifp, sfrom, r, len);
 		}
 		return;
 	}
@@ -3591,7 +3589,7 @@ dhcp6_recv(struct dhcpcd_ctx *ctx, struct ipv6_addr *ia)
 				    state->send->xid[0],
 				    state->send->xid[1],
 				    state->send->xid[2],
-				    ctx->sfrom);
+				    sfrom);
 			return;
 		}
 		logdebugx("%s: redirecting DHCP6 message to %s",
@@ -3599,7 +3597,7 @@ dhcp6_recv(struct dhcpcd_ctx *ctx, struct ipv6_addr *ia)
 		ifp = ifp1;
 	}
 
-	dhcp6_recvif(ifp, r, len);
+	dhcp6_recvif(ifp, sfrom, r, len);
 }
 
 static void
diff --git a/src/dhcpcd.c b/src/dhcpcd.c
index 6fe60ea1..6d86baa4 100644
--- a/src/dhcpcd.c
+++ b/src/dhcpcd.c
@@ -2143,7 +2143,6 @@ exit1:
 #endif
 	dev_stop(&ctx);
 	eloop_free(ctx.eloop);
-	free(ctx.iov[0].iov_base);
 
 	if (ctx.options & DHCPCD_STARTED && !(ctx.options & DHCPCD_FORKED))
 		loginfox(PACKAGE " exited");
diff --git a/src/dhcpcd.h b/src/dhcpcd.h
index 39577006..b135f1b7 100644
--- a/src/dhcpcd.h
+++ b/src/dhcpcd.h
@@ -149,7 +149,6 @@ struct dhcpcd_ctx {
 	int link_fd;
 	int seq;	/* route message sequence no */
 	int sseq;	/* successful seq no sent */
-	struct iovec iov[1];	/* generic iovec buffer */
 
 #ifdef USE_SIGNALS
 	sigset_t sigset;
@@ -184,15 +183,6 @@ struct dhcpcd_ctx {
 	uint8_t *secret;
 	size_t secret_len;
 
-	unsigned char ctlbuf[IP6BUFLEN];
-	struct sockaddr_in6 from;
-	struct msghdr sndhdr;
-	struct iovec sndiov[1];
-	unsigned char sndbuf[CMSG_SPACE(sizeof(struct in6_pktinfo))];
-	struct msghdr rcvhdr;
-	char ntopbuf[INET6_ADDRSTRLEN];
-	const char *sfrom;
-
 	int nd_fd;
 	struct ra_head *ra_routers;
 
diff --git a/src/if-bsd.c b/src/if-bsd.c
index 0fe6d200..f638c641 100644
--- a/src/if-bsd.c
+++ b/src/if-bsd.c
@@ -1229,18 +1229,19 @@ if_dispatch(struct dhcpcd_ctx *ctx, const struct rt_msghdr *rtm)
 int
 if_handlelink(struct dhcpcd_ctx *ctx)
 {
-	struct msghdr msg;
+	union {
+		struct rt_msghdr rtmsg;
+		unsigned char buf[2048];
+	} u;
+	struct iovec iov = { .iov_base = u.buf, .iov_len = sizeof(u) };
+	struct msghdr msg = { .msg_iov = &iov, .msg_iovlen = 1 };
 	ssize_t len;
 
-	memset(&msg, 0, sizeof(msg));
-	msg.msg_iov = ctx->iov;
-	msg.msg_iovlen = 1;
-
-	len = recvmsg_realloc(ctx->link_fd, &msg, 0);
+	len = recvmsg(ctx->link_fd, &msg, 0);
 	if (len == -1)
 		return -1;
 	if (len != 0)
-		if_dispatch(ctx, ctx->iov[0].iov_base);
+		if_dispatch(ctx, &u.rtmsg);
 	return 0;
 }
 
diff --git a/src/if-linux.c b/src/if-linux.c
index 99d3ed6a..1e55d672 100644
--- a/src/if-linux.c
+++ b/src/if-linux.c
@@ -105,7 +105,6 @@ int if_getssid_wext(const char *ifname, uint8_t *ssid);
 struct priv {
 	int route_fd;
 	uint32_t route_pid;
-	struct iovec sndrcv_iov[1];
 };
 
 /* We need this to send a broadcast for InfiniBand.
@@ -346,7 +345,6 @@ if_closesockets_os(struct dhcpcd_ctx *ctx)
 
 	if (ctx->priv != NULL) {
 		priv = (struct priv *)ctx->priv;
-		free(priv->sndrcv_iov[0].iov_base);
 		close(priv->route_fd);
 	}
 }
@@ -356,21 +354,18 @@ get_netlink(struct dhcpcd_ctx *ctx, struct iovec *iov,
     struct interface *ifp, int fd, int flags,
     int (*callback)(struct dhcpcd_ctx *, struct interface *, struct nlmsghdr *))
 {
-	struct msghdr msg;
-	struct sockaddr_nl nladdr;
+	struct sockaddr_nl nladdr = { .nl_pid = 0 };
+	struct msghdr msg = {
+	    .msg_name = &nladdr, .msg_namelen = sizeof(nladdr),
+	    .msg_iov = iov, .msg_iovlen = 1,
+	};
 	ssize_t len;
 	struct nlmsghdr *nlm;
 	int r;
 	unsigned int again;
 
-	memset(&msg, 0, sizeof(msg));
-	msg.msg_name = &nladdr;
-	msg.msg_namelen = sizeof(nladdr);
-	memset(&nladdr, 0, sizeof(nladdr));
-	msg.msg_iov = iov;
-	msg.msg_iovlen = 1;
 recv_again:
-	if ((len = recvmsg_realloc(fd, &msg, flags)) == -1)
+	if ((len = recvmsg(fd, &msg, flags)) == -1)
 		return -1;
 	if (len == 0)
 		return 0;
@@ -816,8 +811,13 @@ link_netlink(struct dhcpcd_ctx *ctx, struct interface *ifp,
 int
 if_handlelink(struct dhcpcd_ctx *ctx)
 {
+	unsigned char buf[16 * 1024];
+	struct iovec iov = {
+		.iov_base = buf,
+		.iov_len = sizeof(buf),
+	};
 
-	return get_netlink(ctx, ctx->iov, NULL,
+	return get_netlink(ctx, &iov, NULL,
 	    ctx->link_fd, MSG_DONTWAIT, &link_netlink);
 }
 
@@ -827,12 +827,12 @@ send_netlink(struct dhcpcd_ctx *ctx, struct interface *ifp,
     int (*callback)(struct dhcpcd_ctx *, struct interface *, struct nlmsghdr *))
 {
 	int s, r;
-	struct sockaddr_nl snl;
-	struct iovec iov[1];
-	struct msghdr msg;
-
-	memset(&snl, 0, sizeof(snl));
-	snl.nl_family = AF_NETLINK;
+	struct sockaddr_nl snl = { .nl_family = AF_NETLINK };
+	struct iovec iov = { .iov_base = hdr, .iov_len = hdr->nlmsg_len };
+	struct msghdr msg = {
+	    .msg_name = &snl, .msg_namelen = sizeof(snl),
+	    .msg_iov = &iov, .msg_iovlen = 1
+	};
 
 	if (protocol == NETLINK_ROUTE) {
 		struct priv *priv;
@@ -844,22 +844,17 @@ send_netlink(struct dhcpcd_ctx *ctx, struct interface *ifp,
 			return -1;
 	}
 
-	memset(&msg, 0, sizeof(msg));
-	msg.msg_name = &snl;
-	msg.msg_namelen = sizeof(snl);
-	memset(&iov, 0, sizeof(iov));
-	iov[0].iov_base = hdr;
-	iov[0].iov_len = hdr->nlmsg_len;
-	msg.msg_iov = iov;
-	msg.msg_iovlen = 1;
 	/* Request a reply */
 	hdr->nlmsg_flags |= NLM_F_ACK;
 	hdr->nlmsg_seq = (uint32_t)++ctx->seq;
 	if (sendmsg(s, &msg, 0) != -1) {
-		struct priv *priv;
+		unsigned char buf[16 * 1024];
+		struct iovec riov = {
+			.iov_base = buf,
+			.iov_len = sizeof(buf),
+		};
 
-		priv = (struct priv *)ctx->priv;
-		r = get_netlink(ctx, priv->sndrcv_iov, ifp, s, 0, callback);
+		r = get_netlink(ctx, &riov, ifp, s, 0, callback);
 	} else
 		r = -1;
 	if (protocol != NETLINK_ROUTE)
@@ -1304,17 +1299,15 @@ _if_initrt(struct dhcpcd_ctx *ctx, __unused struct interface *ifp,
 int
 if_initrt(struct dhcpcd_ctx *ctx, int af)
 {
-	struct nlmr nlm;
+	struct nlmr nlm = {
+	    .hdr.nlmsg_len = NLMSG_LENGTH(sizeof(struct rtmsg)),
+	    .hdr.nlmsg_type = RTM_GETROUTE,
+	    .hdr.nlmsg_flags = NLM_F_REQUEST | NLM_F_MATCH,
+	    .rt.rtm_table = RT_TABLE_MAIN,
+	    .rt.rtm_family = (unsigned char)af,
+	};
 
 	rt_headclear(&ctx->kroutes, af);
-
-	memset(&nlm, 0, sizeof(nlm));
-	nlm.hdr.nlmsg_len = NLMSG_LENGTH(sizeof(struct rtmsg));
-	nlm.hdr.nlmsg_type = RTM_GETROUTE;
-	nlm.hdr.nlmsg_flags = NLM_F_REQUEST | NLM_F_MATCH;
-	nlm.rt.rtm_table = RT_TABLE_MAIN;
-	nlm.rt.rtm_family = (unsigned char)af;
-
 	return send_netlink(ctx, NULL, NETLINK_ROUTE, &nlm.hdr, &_if_initrt);
 }
 
@@ -1401,7 +1394,7 @@ bpf_read(struct interface *ifp, int s, void *data, size_t len,
 	};
 	struct msghdr msg = { .msg_iov = &iov, .msg_iovlen = 1 };
 #ifdef PACKET_AUXDATA
-	unsigned char cmsgbuf[CMSG_LEN(sizeof(struct tpacket_auxdata))];
+	unsigned char cmsgbuf[CMSG_LEN(sizeof(struct tpacket_auxdata))] = { 0 };
 	struct cmsghdr *cmsg;
 	struct tpacket_auxdata *aux;
 #endif
diff --git a/src/if-sun.c b/src/if-sun.c
index d7c2e9c6..76111f4e 100644
--- a/src/if-sun.c
+++ b/src/if-sun.c
@@ -752,17 +752,18 @@ if_dispatch(struct dhcpcd_ctx *ctx, const struct rt_msghdr *rtm)
 int
 if_handlelink(struct dhcpcd_ctx *ctx)
 {
-	struct msghdr msg;
+	union {
+		struct rt_msghdr rtmsg;
+		unsigned char buf[2048];
+	} u;
+	struct iovec iov = { .iov_base = u.buf, .iov_len = sizeof(u) };
+	struct msghdr msg = { .msg_iov = &iov, .msg_iovlen = 1 };
 	ssize_t len;
 
-	memset(&msg, 0, sizeof(msg));
-	msg.msg_iov = ctx->iov;
-	msg.msg_iovlen = 1;
-
-	if ((len = recvmsg_realloc(ctx->link_fd, &msg, 0)) == -1)
+	if ((len = recvmsg(ctx->link_fd, &msg, 0)) == -1)
 		return -1;
 	if (len != 0)
-		if_dispatch(ctx, ctx->iov[0].iov_base);
+		if_dispatch(ctx, &u.rtmsg);
 	return 0;
 }
 
diff --git a/src/ipv6.c b/src/ipv6.c
index 62ce9cc6..d7c73c22 100644
--- a/src/ipv6.c
+++ b/src/ipv6.c
@@ -129,29 +129,14 @@ int
 ipv6_init(struct dhcpcd_ctx *ctx)
 {
 
-	if (ctx->sndhdr.msg_iovlen == 1)
+	if (ctx->ra_routers != NULL)
 		return 0;
 
-	if (ctx->ra_routers == NULL) {
-		ctx->ra_routers = malloc(sizeof(*ctx->ra_routers));
-		if (ctx->ra_routers == NULL)
-			return -1;
-	}
+	ctx->ra_routers = malloc(sizeof(*ctx->ra_routers));
+	if (ctx->ra_routers == NULL)
+		return -1;
 	TAILQ_INIT(ctx->ra_routers);
 
-	ctx->sndhdr.msg_namelen = sizeof(struct sockaddr_in6);
-	ctx->sndhdr.msg_iov = ctx->sndiov;
-	ctx->sndhdr.msg_iovlen = 1;
-	ctx->sndhdr.msg_control = ctx->sndbuf;
-	ctx->sndhdr.msg_controllen = sizeof(ctx->sndbuf);
-	ctx->rcvhdr.msg_name = &ctx->from;
-	ctx->rcvhdr.msg_namelen = sizeof(ctx->from);
-	ctx->rcvhdr.msg_iov = ctx->iov;
-	ctx->rcvhdr.msg_iovlen = 1;
-	ctx->rcvhdr.msg_control = ctx->ctlbuf;
-	// controllen is set at recieve
-	//ctx->rcvhdr.msg_controllen = sizeof(ctx->rcvbuf);
-
 	ctx->nd_fd = -1;
 	ctx->dhcp6_fd = -1;
 	return 0;
diff --git a/src/ipv6nd.c b/src/ipv6nd.c
index 5a248486..7f67287c 100644
--- a/src/ipv6nd.c
+++ b/src/ipv6nd.c
@@ -274,10 +274,17 @@ ipv6nd_sendrsprobe(void *arg)
 {
 	struct interface *ifp = arg;
 	struct dhcpcd_ctx *ctx;
-	struct rs_state *state;
-	struct sockaddr_in6 dst;
+	struct rs_state *state = RS_STATE(ifp);
+	struct sockaddr_in6 dst = { .sin6_family = AF_INET6 };
+	struct iovec iov = { .iov_base = state->rs, .iov_len = state->rslen };
+	unsigned char ctl[CMSG_SPACE(sizeof(struct in6_pktinfo))] = { 0 };
+	struct msghdr msg = {
+	    .msg_name = &dst, .msg_namelen = sizeof(dst),
+	    .msg_iov = &iov, .msg_iovlen = 1,
+	    .msg_control = ctl, .msg_controllen = sizeof(ctl),
+	};
 	struct cmsghdr *cm;
-	struct in6_pktinfo pi;
+	struct in6_pktinfo pi = { .ipi6_ifindex = ifp->index };
 
 	if (ipv6_linklocal(ifp) == NULL) {
 		logdebugx("%s: delaying Router Solicitation for LL address",
@@ -286,8 +293,6 @@ ipv6nd_sendrsprobe(void *arg)
 		return;
 	}
 
-	memset(&dst, 0, sizeof(dst));
-	dst.sin6_family = AF_INET6;
 #ifdef HAVE_SA_LEN
 	dst.sin6_len = sizeof(dst);
 #endif
@@ -297,25 +302,19 @@ ipv6nd_sendrsprobe(void *arg)
 		return;
 	}
 
-	state = RS_STATE(ifp);
 	ctx = ifp->ctx;
-	ctx->sndhdr.msg_name = (void *)&dst;
-	ctx->sndhdr.msg_iov[0].iov_base = state->rs;
-	ctx->sndhdr.msg_iov[0].iov_len = state->rslen;
 
 	/* Set the outbound interface */
-	cm = CMSG_FIRSTHDR(&ctx->sndhdr);
+	cm = CMSG_FIRSTHDR(&msg);
 	if (cm == NULL) /* unlikely */
 		return;
 	cm->cmsg_level = IPPROTO_IPV6;
 	cm->cmsg_type = IPV6_PKTINFO;
 	cm->cmsg_len = CMSG_LEN(sizeof(pi));
-	memset(&pi, 0, sizeof(pi));
-	pi.ipi6_ifindex = ifp->index;
 	memcpy(CMSG_DATA(cm), &pi, sizeof(pi));
 
 	logdebugx("%s: sending Router Solicitation", ifp->name);
-	if (sendmsg(ctx->nd_fd, &ctx->sndhdr, 0) == -1) {
+	if (sendmsg(ctx->nd_fd, &msg, 0) == -1) {
 		logerr(__func__);
 		/* Allow IPv6ND to continue .... at most a few errors
 		 * would be logged.
@@ -341,41 +340,42 @@ ipv6nd_sendadvertisement(void *arg)
 	struct ipv6_addr *ia = arg;
 	struct interface *ifp = ia->iface;
 	struct dhcpcd_ctx *ctx = ifp->ctx;
-	struct sockaddr_in6 dst;
+	struct sockaddr_in6 dst = {
+	    .sin6_family = AF_INET6,
+	    .sin6_scope_id = ifp->index,
+	};
+	struct iovec iov = { .iov_base = ia->na, .iov_len = ia->na_len };
+	unsigned char ctl[CMSG_SPACE(sizeof(struct in6_pktinfo))] = { 0 };
+	struct msghdr msg = {
+	    .msg_name = &dst, .msg_namelen = sizeof(dst),
+	    .msg_iov = &iov, .msg_iovlen = 1,
+	    .msg_control = ctl, .msg_controllen = sizeof(ctl),
+	};
 	struct cmsghdr *cm;
-	struct in6_pktinfo pi;
+	struct in6_pktinfo pi = { .ipi6_ifindex = ifp->index };
 	const struct rs_state *state = RS_CSTATE(ifp);
 
 	if (state == NULL || ifp->carrier <= LINK_DOWN)
 		goto freeit;
 
-	memset(&dst, 0, sizeof(dst));
-	dst.sin6_family = AF_INET6;
 #ifdef SIN6_LEN
 	dst.sin6_len = sizeof(dst);
 #endif
-	dst.sin6_scope_id = ifp->index;
 	if (inet_pton(AF_INET6, ALLNODES, &dst.sin6_addr) != 1) {
 		logerr(__func__);
 		return;
 	}
 
-	ctx->sndhdr.msg_name = (void *)&dst;
-	ctx->sndhdr.msg_iov[0].iov_base = ia->na;
-	ctx->sndhdr.msg_iov[0].iov_len = ia->na_len;
-
 	/* Set the outbound interface. */
-	cm = CMSG_FIRSTHDR(&ctx->sndhdr);
+	cm = CMSG_FIRSTHDR(&msg);
 	assert(cm != NULL);
 	cm->cmsg_level = IPPROTO_IPV6;
 	cm->cmsg_type = IPV6_PKTINFO;
 	cm->cmsg_len = CMSG_LEN(sizeof(pi));
-	memset(&pi, 0, sizeof(pi));
-	pi.ipi6_ifindex = ifp->index;
 	memcpy(CMSG_DATA(cm), &pi, sizeof(pi));
 
 	logdebugx("%s: sending NA for %s", ifp->name, ia->saddr);
-	if (sendmsg(ctx->nd_fd, &ctx->sndhdr, 0) == -1)
+	if (sendmsg(ctx->nd_fd, &msg, 0) == -1)
 		logerr(__func__);
 
 	if (++ia->na_count < MAX_NEIGHBOR_ADVERTISEMENT) {
@@ -872,8 +872,9 @@ dhcp6_start(__unused struct interface *ifp, __unused enum DH6S init_state)
 #endif
 
 static void
-ipv6nd_handlera(struct dhcpcd_ctx *ctx, struct interface *ifp,
-    struct icmp6_hdr *icp, size_t len, int hoplimit)
+ipv6nd_handlera(struct dhcpcd_ctx *ctx,
+    const struct sockaddr_in6 *from, const char *sfrom,
+    struct interface *ifp, struct icmp6_hdr *icp, size_t len, int hoplimit)
 {
 	size_t i, olen;
 	struct nd_router_advert *nd_ra;
@@ -895,33 +896,29 @@ ipv6nd_handlera(struct dhcpcd_ctx *ctx, struct interface *ifp,
 
 	if (ifp == NULL) {
 #ifdef DEBUG_RS
-		logdebugx("RA for unexpected interface from %s",
-		    ctx->sfrom);
+		logdebugx("RA for unexpected interface from %s", sfrom);
 #endif
 		return;
 	}
 
 	if (len < sizeof(struct nd_router_advert)) {
-		logerrx("IPv6 RA packet too short from %s", ctx->sfrom);
+		logerrx("IPv6 RA packet too short from %s", sfrom);
 		return;
 	}
 
 	/* RFC 4861 7.1.2 */
 	if (hoplimit != 255) {
-		logerrx("invalid hoplimit(%d) in RA from %s",
-		    hoplimit, ctx->sfrom);
+		logerrx("invalid hoplimit(%d) in RA from %s", hoplimit, sfrom);
 		return;
 	}
-
-	if (!IN6_IS_ADDR_LINKLOCAL(&ctx->from.sin6_addr)) {
-		logerrx("RA from non local address %s", ctx->sfrom);
+	if (!IN6_IS_ADDR_LINKLOCAL(&from->sin6_addr)) {
+		logerrx("RA from non local address %s", sfrom);
 		return;
 	}
 
 	if (!(ifp->options->options & DHCPCD_IPV6RS)) {
 #ifdef DEBUG_RS
-		logerrx("%s: unexpected RA from %s",
-		    ifp->name, ctx->sfrom);
+		logerrx("%s: unexpected RA from %s", ifp->name, sfrom);
 #endif
 		return;
 	}
@@ -930,20 +927,20 @@ ipv6nd_handlera(struct dhcpcd_ctx *ctx, struct interface *ifp,
 	if (ipv6_linklocal(ifp) == NULL) {
 #ifdef DEBUG_RS
 		logdebugx("%s: received RA from %s (no link-local)",
-		    ifp->name, ctx->sfrom);
+		    ifp->name, sfrom);
 #endif
 		return;
 	}
 
-	if (ipv6_iffindaddr(ifp, &ctx->from.sin6_addr, IN6_IFF_TENTATIVE)) {
+	if (ipv6_iffindaddr(ifp, &from->sin6_addr, IN6_IFF_TENTATIVE)) {
 		logdebugx("%s: ignoring RA from ourself %s",
-		    ifp->name, ctx->sfrom);
+		    ifp->name, sfrom);
 		return;
 	}
 
 	TAILQ_FOREACH(rap, ctx->ra_routers, next) {
 		if (ifp == rap->iface &&
-		    IN6_ARE_ADDR_EQUAL(&rap->from, &ctx->from.sin6_addr))
+		    IN6_ARE_ADDR_EQUAL(&rap->from, &from->sin6_addr))
 			break;
 	}
 
@@ -968,8 +965,8 @@ ipv6nd_handlera(struct dhcpcd_ctx *ctx, struct interface *ifp,
 			return;
 		}
 		rap->iface = ifp;
-		rap->from = ctx->from.sin6_addr;
-		strlcpy(rap->sfrom, ctx->sfrom, sizeof(rap->sfrom));
+		rap->from = from->sin6_addr;
+		strlcpy(rap->sfrom, sfrom, sizeof(rap->sfrom));
 		TAILQ_INIT(&rap->addrs);
 		new_rap = true;
 	} else
@@ -991,8 +988,7 @@ ipv6nd_handlera(struct dhcpcd_ctx *ctx, struct interface *ifp,
 	 * in accordance with the own prefix times which would result in too
 	 * much needless log spam. */
 	logfunc = new_rap ? loginfox : logdebugx,
-	logfunc("%s: Router Advertisement from %s",
-	    ifp->name, ctx->sfrom);
+	logfunc("%s: Router Advertisement from %s", ifp->name, rap->sfrom);
 
 	clock_gettime(CLOCK_MONOTONIC, &rap->acquired);
 	rap->flags = nd_ra->nd_ra_flags_reserved;
@@ -1053,10 +1049,10 @@ ipv6nd_handlera(struct dhcpcd_ctx *ctx, struct interface *ifp,
 			}
 			if (dho != NULL)
 				logwarnx("%s: reject RA (option %s) from %s",
-				    ifp->name, dho->var, ctx->sfrom);
+				    ifp->name, dho->var, rap->sfrom);
 			else
 				logwarnx("%s: reject RA (option %d) from %s",
-				    ifp->name, ndo.nd_opt_type, ctx->sfrom);
+				    ifp->name, ndo.nd_opt_type, rap->sfrom);
 			if (new_rap)
 				ipv6nd_removefreedrop_ra(rap, 0, 0);
 			else
@@ -1196,7 +1192,7 @@ ipv6nd_handlera(struct dhcpcd_ctx *ctx, struct interface *ifp,
 		    dho->option))
 		{
 			logwarnx("%s: reject RA (no option %s) from %s",
-			    ifp->name, dho->var, ctx->sfrom);
+			    ifp->name, dho->var, rap->sfrom);
 			if (new_rap)
 				ipv6nd_removefreedrop_ra(rap, 0, 0);
 			else
@@ -1584,8 +1580,8 @@ ipv6nd_drop(struct interface *ifp)
 }
 
 static void
-ipv6nd_handlena(struct dhcpcd_ctx *ctx, struct interface *ifp,
-    struct icmp6_hdr *icp, size_t len, int hoplimit)
+ipv6nd_handlena(struct dhcpcd_ctx *ctx, const char *sfrom,
+    struct interface *ifp, struct icmp6_hdr *icp, size_t len, int hoplimit)
 {
 	struct nd_neighbor_advert *nd_na;
 	struct in6_addr nd_na_target;
@@ -1596,22 +1592,20 @@ ipv6nd_handlena(struct dhcpcd_ctx *ctx, struct interface *ifp,
 
 	if (ifp == NULL) {
 #ifdef DEBUG_NS
-		logdebugx("NA for unexpected interface from %s",
-		    ctx->sfrom);
+		logdebugx("NA for unexpected interface from %s", sfrom);
 #endif
 		return;
 	}
 
 	if ((size_t)len < sizeof(struct nd_neighbor_advert)) {
-		logerrx("%s: IPv6 NA too short from %s",
-		    ifp->name, ctx->sfrom);
+		logerrx("%s: IPv6 NA too short from %s", ifp->name, sfrom);
 		return;
 	}
 
 	/* RFC 4861 7.1.2 */
 	if (hoplimit != 255) {
 		logerrx("invalid hoplimit(%d) in NA from %s",
-		    hoplimit, ctx->sfrom);
+		    hoplimit, sfrom);
 		return;
 	}
 
@@ -1625,7 +1619,7 @@ ipv6nd_handlena(struct dhcpcd_ctx *ctx, struct interface *ifp,
 	memcpy(&nd_na_target, &nd_na->nd_na_target, sizeof(nd_na_target));
 	if (IN6_IS_ADDR_MULTICAST(&nd_na_target)) {
 		logerrx("%s: NA multicast address %s (%s)",
-		    ifp->name, taddr, ctx->sfrom);
+		    ifp->name, taddr, sfrom);
 		return;
 	}
 
@@ -1637,20 +1631,20 @@ ipv6nd_handlena(struct dhcpcd_ctx *ctx, struct interface *ifp,
 	if (rap == NULL) {
 #ifdef DEBUG_NS
 		logdebugx("%s: unexpected NA from %s for %s",
-		    ifp->name, ctx->sfrom, taddr);
+		    ifp->name, sfrom, taddr);
 #endif
 		return;
 	}
 
 #ifdef DEBUG_NS
 	logdebugx("%s: %sNA for %s from %s",
-	    ifp->name, is_solicited ? "solicited " : "", taddr, ctx->sfrom);
+	    ifp->name, is_solicited ? "solicited " : "", taddr, sfrom);
 #endif
 
 	/* Node is no longer a router, so remove it from consideration */
 	if (!is_router && !rap->expired) {
 		loginfox("%s: %s not a router (%s)",
-		    ifp->name, taddr, ctx->sfrom);
+		    ifp->name, taddr, sfrom);
 		rap->expired = 1;
 		rt_build(ifp->ctx,  AF_INET6);
 		script_runreason(ifp, "ROUTERADVERT");
@@ -1665,33 +1659,43 @@ static void
 ipv6nd_handledata(void *arg)
 {
 	struct dhcpcd_ctx *ctx;
+	struct sockaddr_in6 from;
+	unsigned char buf[64 * 1024]; /* Maximum ICMPv6 size */
+	struct iovec iov = {
+		.iov_base = buf,
+		.iov_len = sizeof(buf),
+	};
+	unsigned char ctl[CMSG_SPACE(sizeof(struct in6_pktinfo)) + CMSG_SPACE(sizeof(int))] = { 0 };
+	struct msghdr msg = {
+	    .msg_name = &from, .msg_namelen = sizeof(from),
+	    .msg_iov = &iov, .msg_iovlen = 1,
+	    .msg_control = ctl, .msg_controllen = sizeof(ctl),
+	};
 	ssize_t len;
 	struct cmsghdr *cm;
+	char sfrom[INET6_ADDRSTRLEN];
 	int hoplimit;
 	struct in6_pktinfo pkt;
 	struct icmp6_hdr *icp;
 	struct interface *ifp;
 
 	ctx = arg;
-	ctx->rcvhdr.msg_controllen = CMSG_SPACE(sizeof(struct in6_pktinfo)) +
-	    CMSG_SPACE(sizeof(int));
-	len = recvmsg_realloc(ctx->nd_fd, &ctx->rcvhdr, 0);
+	len = recvmsg(ctx->nd_fd, &msg, 0);
 	if (len == -1) {
 		logerr(__func__);
 		return;
 	}
-	ctx->sfrom = inet_ntop(AF_INET6, &ctx->from.sin6_addr,
-	    ctx->ntopbuf, INET6_ADDRSTRLEN);
+	inet_ntop(AF_INET6, &from.sin6_addr, sfrom, sizeof(sfrom));
 	if ((size_t)len < sizeof(struct icmp6_hdr)) {
-		logerrx("IPv6 ICMP packet too short from %s", ctx->sfrom);
+		logerrx("IPv6 ICMP packet too short from %s", sfrom);
 		return;
 	}
 
 	pkt.ipi6_ifindex = 0;
 	hoplimit = 0;
-	for (cm = (struct cmsghdr *)CMSG_FIRSTHDR(&ctx->rcvhdr);
+	for (cm = (struct cmsghdr *)CMSG_FIRSTHDR(&msg);
 	     cm;
-	     cm = (struct cmsghdr *)CMSG_NXTHDR(&ctx->rcvhdr, cm))
+	     cm = (struct cmsghdr *)CMSG_NXTHDR(&msg, cm))
 	{
 		if (cm->cmsg_level != IPPROTO_IPV6)
 			continue;
@@ -1708,7 +1712,7 @@ ipv6nd_handledata(void *arg)
 	}
 
 	if (pkt.ipi6_ifindex == 0) {
-		logerrx("IPv6 RA/NA did not contain index from %s", ctx->sfrom);
+		logerrx("IPv6 RA/NA did not contain index from %s", sfrom);
 		return;
 	}
 
@@ -1724,22 +1728,22 @@ ipv6nd_handledata(void *arg)
 	    !(ifp->options->options & DHCPCD_IPV6)))
 		return;
 
-	icp = (struct icmp6_hdr *)ctx->rcvhdr.msg_iov[0].iov_base;
+	icp = (struct icmp6_hdr *)buf;
 	if (icp->icmp6_code == 0) {
 		switch(icp->icmp6_type) {
 			case ND_NEIGHBOR_ADVERT:
-				ipv6nd_handlena(ctx, ifp, icp, (size_t)len,
-				   hoplimit);
+				ipv6nd_handlena(ctx, sfrom,
+				    ifp, icp, (size_t)len, hoplimit);
 				return;
 			case ND_ROUTER_ADVERT:
-				ipv6nd_handlera(ctx, ifp, icp, (size_t)len,
-				   hoplimit);
+				ipv6nd_handlera(ctx, &from, sfrom,
+				    ifp, icp, (size_t)len, hoplimit);
 				return;
 		}
 	}
 
 	logerrx("invalid IPv6 type %d or code %d from %s",
-	    icp->icmp6_type, icp->icmp6_code, ctx->sfrom);
+	    icp->icmp6_type, icp->icmp6_code, sfrom);
 }
 
 static void