From: Rafael Sadowski <rafael@sizeofvoid.org>
Subject: relayd: check imsg_compose_event return values
To: tech@openbsd.org
Date: Sun, 26 Jul 2026 11:14:47 +0200

Also remove double imsg_compose_event declaration. OK?

commit 05b0b40200dd6d68728f133742e0e7bed8b5f28e
Author: Rafael Sadowski <rafael@sizeofvoid.org>
Date:   Sun Jul 26 09:49:41 2026 +0200

    relayd: check imsg_compose_event return values

diff --git a/control.c b/control.c
index 3757bd0..54e9227 100644
--- a/control.c
+++ b/control.c
@@ -283,78 +283,102 @@ control_dispatch_imsg(int fd, short event, void *arg)
 			if (imsg_get_data(&imsg, &id, sizeof(id)) == -1)
 				fatalx("%s: imsg_get_data", __func__);

-			if (disable_rdr(c, &id))
-				imsg_compose_event(&c->iev, IMSG_CTL_FAIL,
-				    0, ps->ps_instance + 1, -1, NULL, 0);
-			else {
+			if (disable_rdr(c, &id)) {
+				if (imsg_compose_event(&c->iev, IMSG_CTL_FAIL,
+				    0, ps->ps_instance + 1, -1, NULL, 0) == -1)
+					log_warn("%s: imsg_compose_event",
+					    __func__);
+			} else {
 				control_imsg_forward(&imsg);
-				imsg_compose_event(&c->iev, IMSG_CTL_OK,
-				    0, ps->ps_instance + 1, -1, NULL, 0);
+				if (imsg_compose_event(&c->iev, IMSG_CTL_OK,
+				    0, ps->ps_instance + 1, -1, NULL, 0) == -1)
+					log_warn("%s: imsg_compose_event",
+					    __func__);
 			}
 			break;
 		case IMSG_CTL_RDR_ENABLE:
 			if (imsg_get_data(&imsg, &id, sizeof(id)) == -1)
 				fatalx("%s: imsg_get_data", __func__);

-			if (enable_rdr(c, &id))
-				imsg_compose_event(&c->iev, IMSG_CTL_FAIL,
-				    0, ps->ps_instance + 1, -1, NULL, 0);
-			else {
+			if (enable_rdr(c, &id)) {
+				if (imsg_compose_event(&c->iev, IMSG_CTL_FAIL,
+				    0, ps->ps_instance + 1, -1, NULL, 0) == -1)
+					log_warn("%s: imsg_compose_event",
+					    __func__);
+			} else {
 				control_imsg_forward(&imsg);
-				imsg_compose_event(&c->iev, IMSG_CTL_OK,
-				    0, ps->ps_instance + 1, -1, NULL, 0);
+				if (imsg_compose_event(&c->iev, IMSG_CTL_OK,
+				    0, ps->ps_instance + 1, -1, NULL, 0) == -1)
+					log_warn("%s: imsg_compose_event",
+					    __func__);
 			}
 			break;
 		case IMSG_CTL_TABLE_DISABLE:
 			if (imsg_get_data(&imsg, &id, sizeof(id)) == -1)
 				fatalx("%s: imsg_get_data", __func__);

-			if (disable_table(c, &id))
-				imsg_compose_event(&c->iev, IMSG_CTL_FAIL,
-				    0, ps->ps_instance + 1, -1, NULL, 0);
-			else {
+			if (disable_table(c, &id)) {
+				if (imsg_compose_event(&c->iev, IMSG_CTL_FAIL,
+				    0, ps->ps_instance + 1, -1, NULL, 0) == -1)
+					log_warn("%s: imsg_compose_event",
+					    __func__);
+			} else {
 				control_imsg_forward(&imsg);
-				imsg_compose_event(&c->iev, IMSG_CTL_OK,
-				    0, ps->ps_instance + 1, -1, NULL, 0);
+				if (imsg_compose_event(&c->iev, IMSG_CTL_OK,
+				    0, ps->ps_instance + 1, -1, NULL, 0) == -1)
+					log_warn("%s: imsg_compose_event",
+					    __func__);
 			}
 			break;
 		case IMSG_CTL_TABLE_ENABLE:
 			if (imsg_get_data(&imsg, &id, sizeof(id)) == -1)
 				fatalx("%s: imsg_get_data", __func__);

-			if (enable_table(c, &id))
-				imsg_compose_event(&c->iev, IMSG_CTL_FAIL,
-				    0, ps->ps_instance + 1, -1, NULL, 0);
-			else {
+			if (enable_table(c, &id)) {
+				if (imsg_compose_event(&c->iev, IMSG_CTL_FAIL,
+				    0, ps->ps_instance + 1, -1, NULL, 0) == -1)
+					log_warn("%s: imsg_compose_event",
+					    __func__);
+			} else {
 				control_imsg_forward(&imsg);
-				imsg_compose_event(&c->iev, IMSG_CTL_OK,
-				    0, ps->ps_instance + 1, -1, NULL, 0);
+				if (imsg_compose_event(&c->iev, IMSG_CTL_OK,
+				    0, ps->ps_instance + 1, -1, NULL, 0) == -1)
+					log_warn("%s: imsg_compose_event",
+					    __func__);
 			}
 			break;
 		case IMSG_CTL_HOST_DISABLE:
 			if (imsg_get_data(&imsg, &id, sizeof(id)) == -1)
 				fatalx("%s: imsg_get_data", __func__);

-			if (disable_host(c, &id, NULL))
-				imsg_compose_event(&c->iev, IMSG_CTL_FAIL,
-				    0, ps->ps_instance + 1, -1, NULL, 0);
-			else {
+			if (disable_host(c, &id, NULL)) {
+				if (imsg_compose_event(&c->iev, IMSG_CTL_FAIL,
+				    0, ps->ps_instance + 1, -1, NULL, 0) == -1)
+					log_warn("%s: imsg_compose_event",
+					    __func__);
+			} else {
 				control_imsg_forward(&imsg);
-				imsg_compose_event(&c->iev, IMSG_CTL_OK,
-				    0, ps->ps_instance + 1, -1, NULL, 0);
+				if (imsg_compose_event(&c->iev, IMSG_CTL_OK,
+				    0, ps->ps_instance + 1, -1, NULL, 0) == -1)
+					log_warn("%s: imsg_compose_event",
+					    __func__);
 			}
 			break;
 		case IMSG_CTL_HOST_ENABLE:
 			if (imsg_get_data(&imsg, &id, sizeof(id)) == -1)
 				fatalx("%s: imsg_get_data", __func__);

-			if (enable_host(c, &id, NULL))
-				imsg_compose_event(&c->iev, IMSG_CTL_FAIL,
-				    0, ps->ps_instance + 1, -1, NULL, 0);
-			else {
+			if (enable_host(c, &id, NULL)) {
+				if (imsg_compose_event(&c->iev, IMSG_CTL_FAIL,
+				    0, ps->ps_instance + 1, -1, NULL, 0) == -1)
+					log_warn("%s: imsg_compose_event",
+					    __func__);
+			} else {
 				control_imsg_forward(&imsg);
-				imsg_compose_event(&c->iev, IMSG_CTL_OK,
-				    0, ps->ps_instance + 1, -1, NULL, 0);
+				if (imsg_compose_event(&c->iev, IMSG_CTL_OK,
+				    0, ps->ps_instance + 1, -1, NULL, 0) == -1)
+					log_warn("%s: imsg_compose_event",
+					    __func__);
 			}
 			break;
 		case IMSG_CTL_SHUTDOWN:
@@ -365,16 +389,19 @@ control_dispatch_imsg(int fd, short event, void *arg)
 			if (proc_compose(env->sc_ps, PROC_HCE, IMSG_CTL_POLL,
 			    NULL, 0) == -1)
 				log_warn("%s: proc_compose", __func__);
-			imsg_compose_event(&c->iev, IMSG_CTL_OK,
-			    0, ps->ps_instance + 1, -1, NULL, 0);
+			if (imsg_compose_event(&c->iev, IMSG_CTL_OK,
+			    0, ps->ps_instance + 1, -1, NULL, 0) == -1)
+				log_warn("%s: imsg_compose_event", __func__);
 			break;
 		case IMSG_CTL_NOTIFY:
 			if (c->flags & CTL_CONN_NOTIFY) {
 				log_debug("%s: "
 				    "client requested notify more than once",
 				    __func__);
-				imsg_compose_event(&c->iev, IMSG_CTL_FAIL,
-				    0, ps->ps_instance + 1, -1, NULL, 0);
+				if (imsg_compose_event(&c->iev, IMSG_CTL_FAIL,
+				    0, ps->ps_instance + 1, -1, NULL, 0) == -1)
+					log_warn("%s: imsg_compose_event",
+					    __func__);
 				break;
 			}
 			c->flags |= CTL_CONN_NOTIFY;
diff --git a/pfe.c b/pfe.c
index d527e3c..e62ed05 100644
--- a/pfe.c
+++ b/pfe.c
@@ -303,9 +303,9 @@ pfe_dispatch_relay(int fd, struct privsep_proc *p, struct imsg *imsg)
 			    __func__, con.se_cid);
 			return (0);
 		}
-		imsg_compose_event(&c->iev,
-		    IMSG_CTL_SESSION, 0, 0, -1,
-		    &con, sizeof(con));
+		if (imsg_compose_event(&c->iev, IMSG_CTL_SESSION, 0, 0, -1,
+		    &con, sizeof(con)) == -1)
+			log_warn("%s: imsg_compose_event", __func__);
 		break;
 	case IMSG_CTL_END:
 		if (imsg_get_data(imsg, &cid, sizeof(cid)) == -1)
@@ -320,8 +320,9 @@ pfe_dispatch_relay(int fd, struct privsep_proc *p, struct imsg *imsg)
 			return (0);
 		} else if (--c->waiting == 0) {
 			/* Last ack for a previous request */
-			imsg_compose_event(&c->iev, IMSG_CTL_END,
-			    0, 0, -1, NULL, 0);
+			if (imsg_compose_event(&c->iev, IMSG_CTL_END, 0, 0, -1,
+			    NULL, 0) == -1)
+				log_warn("%s: imsg_compose_event", __func__);
 		}
 		break;
 	case IMSG_SESS_PUBLISH:
@@ -376,49 +377,64 @@ show(struct ctl_conn *c)
 	if (env->sc_rdrs == NULL)
 		goto relays;
 	TAILQ_FOREACH(rdr, env->sc_rdrs, entry) {
-		imsg_compose_event(&c->iev, IMSG_CTL_RDR, 0, 0, -1,
-		    rdr, sizeof(*rdr));
+		if (imsg_compose_event(&c->iev, IMSG_CTL_RDR, 0, 0, -1,
+		    rdr, sizeof(*rdr)) == -1)
+			log_warn("%s: imsg_compose_event", __func__);
 		if (rdr->conf.flags & F_DISABLE)
 			continue;

-		imsg_compose_event(&c->iev, IMSG_CTL_RDR_STATS, 0, 0, -1,
-		    &rdr->stats, sizeof(rdr->stats));
+		if (imsg_compose_event(&c->iev, IMSG_CTL_RDR_STATS, 0, 0, -1,
+		    &rdr->stats, sizeof(rdr->stats)) == -1)
+			log_warn("%s: imsg_compose_event", __func__);
+
+		if (imsg_compose_event(&c->iev, IMSG_CTL_TABLE, 0, 0, -1,
+		    rdr->table, sizeof(*rdr->table)) == -1)
+			log_warn("%s: imsg_compose_event", __func__);

-		imsg_compose_event(&c->iev, IMSG_CTL_TABLE, 0, 0, -1,
-		    rdr->table, sizeof(*rdr->table));
 		if (!(rdr->table->conf.flags & F_DISABLE))
 			TAILQ_FOREACH(host, &rdr->table->hosts, entry)
-				imsg_compose_event(&c->iev, IMSG_CTL_HOST,
-				    0, 0, -1, host, sizeof(*host));
+				if (imsg_compose_event(&c->iev, IMSG_CTL_HOST,
+				    0, 0, -1, host, sizeof(*host)) == -1)
+					log_warn("%s: imsg_compose_event",
+					    __func__);

 		if (rdr->backup->conf.id == EMPTY_TABLE)
 			continue;
-		imsg_compose_event(&c->iev, IMSG_CTL_TABLE, 0, 0, -1,
-		    rdr->backup, sizeof(*rdr->backup));
+		if (imsg_compose_event(&c->iev, IMSG_CTL_TABLE, 0, 0, -1,
+		    rdr->backup, sizeof(*rdr->backup)) == -1)
+			log_warn("%s: imsg_compose_event", __func__);
 		if (!(rdr->backup->conf.flags & F_DISABLE))
 			TAILQ_FOREACH(host, &rdr->backup->hosts, entry)
-				imsg_compose_event(&c->iev, IMSG_CTL_HOST,
-				    0, 0, -1, host, sizeof(*host));
+				if (imsg_compose_event(&c->iev, IMSG_CTL_HOST,
+				    0, 0, -1, host, sizeof(*host)) == -1)
+					log_warn("%s: imsg_compose_event",
+					    __func__);
 	}
 relays:
 	if (env->sc_relays == NULL)
 		goto routers;
 	TAILQ_FOREACH(rlay, env->sc_relays, rl_entry) {
 		rlay->rl_stats[env->sc_conf.prefork_relay].id = EMPTY_ID;
-		imsg_compose_event(&c->iev, IMSG_CTL_RELAY, 0, 0, -1,
-		    rlay, sizeof(*rlay));
-		imsg_compose_event(&c->iev, IMSG_CTL_RELAY_STATS, 0, 0, -1,
-		    &rlay->rl_stats, sizeof(rlay->rl_stats));
+		if (imsg_compose_event(&c->iev, IMSG_CTL_RELAY, 0, 0, -1,
+		    rlay, sizeof(*rlay)) == -1)
+			log_warn("%s: imsg_compose_event", __func__);
+
+		if (imsg_compose_event(&c->iev, IMSG_CTL_RELAY_STATS, 0, 0, -1,
+		    &rlay->rl_stats, sizeof(rlay->rl_stats)) == -1)
+			log_warn("%s: imsg_compose_event", __func__);

 		TAILQ_FOREACH(rlt, &rlay->rl_tables, rlt_entry) {
-			imsg_compose_event(&c->iev, IMSG_CTL_TABLE, 0, 0, -1,
-			    rlt->rlt_table, sizeof(*rlt->rlt_table));
+			if (imsg_compose_event(&c->iev, IMSG_CTL_TABLE, 0, 0,
+			    -1, rlt->rlt_table, sizeof(*rlt->rlt_table)) == -1)
+				log_warn("%s: imsg_compose_event", __func__);
 			if (!(rlt->rlt_table->conf.flags & F_DISABLE))
 				TAILQ_FOREACH(host,
 				    &rlt->rlt_table->hosts, entry)
-					imsg_compose_event(&c->iev,
+					if (imsg_compose_event(&c->iev,
 					    IMSG_CTL_HOST, 0, 0, -1,
-					    host, sizeof(*host));
+					    host, sizeof(*host)) == -1)
+						log_warn("%s: imsg_compose_event",
+						    __func__);
 		}
 	}

@@ -426,24 +442,31 @@ routers:
 	if (env->sc_rts == NULL)
 		goto end;
 	TAILQ_FOREACH(rt, env->sc_rts, rt_entry) {
-		imsg_compose_event(&c->iev, IMSG_CTL_ROUTER, 0, 0, -1,
-		    rt, sizeof(*rt));
+		if (imsg_compose_event(&c->iev, IMSG_CTL_ROUTER, 0, 0, -1,
+		    rt, sizeof(*rt)) == -1)
+			log_warn("%s: imsg_compose_event", __func__);
 		if (rt->rt_conf.flags & F_DISABLE)
 			continue;

 		TAILQ_FOREACH(nr, &rt->rt_netroutes, nr_entry)
-			imsg_compose_event(&c->iev, IMSG_CTL_NETROUTE,
-			    0, 0, -1, nr, sizeof(*nr));
-		imsg_compose_event(&c->iev, IMSG_CTL_TABLE, 0, 0, -1,
-		    rt->rt_gwtable, sizeof(*rt->rt_gwtable));
+			if (imsg_compose_event(&c->iev, IMSG_CTL_NETROUTE,
+			    0, 0, -1, nr, sizeof(*nr)) == -1)
+				log_warn("%s: imsg_compose_event", __func__);
+		if (imsg_compose_event(&c->iev, IMSG_CTL_TABLE, 0, 0, -1,
+		    rt->rt_gwtable, sizeof(*rt->rt_gwtable)) == -1)
+			log_warn("%s: imsg_compose_event", __func__);
+
 		if (!(rt->rt_gwtable->conf.flags & F_DISABLE))
 			TAILQ_FOREACH(host, &rt->rt_gwtable->hosts, entry)
-				imsg_compose_event(&c->iev, IMSG_CTL_HOST,
-				    0, 0, -1, host, sizeof(*host));
+				if (imsg_compose_event(&c->iev, IMSG_CTL_HOST,
+				    0, 0, -1, host, sizeof(*host)) == -1)
+					log_warn("%s: imsg_compose_event",
+					    __func__);
 	}

 end:
-	imsg_compose_event(&c->iev, IMSG_CTL_END, 0, 0, -1, NULL, 0);
+	if (imsg_compose_event(&c->iev, IMSG_CTL_END, 0, 0, -1, NULL, 0) == -1)
+		log_warn("%s: imsg_compose_event", __func__);
 }

 void
diff --git a/relayd.h b/relayd.h
index 2aa6eab..4716091 100644
--- a/relayd.h
+++ b/relayd.h
@@ -1332,9 +1332,6 @@ int			 map6to4(struct sockaddr_storage *);
 int			 map4to6(struct sockaddr_storage *,
     struct sockaddr_storage *);
 void			 imsg_event_add(struct imsgev *);
-int			 imsg_compose_event(struct imsgev *, u_int16_t,
-    u_int32_t,
-    pid_t, int, void *, u_int16_t);
 void			 socket_rlimit(int);
 void			*get_data(struct ibuf *, size_t);
 int			 sockaddr_cmp(struct sockaddr *, struct sockaddr *,
@@ -1342,8 +1339,7 @@ int			 sockaddr_cmp(struct sockaddr *, struct sockaddr *,
 struct in6_addr		*prefixlen2mask6(u_int8_t, u_int32_t *);
 u_int32_t		 prefixlen2mask(u_int8_t);
 int			 accept_reserve(int, struct sockaddr *, socklen_t *,
-    int,
-    volatile int *);
+    int, volatile int *);
 struct kv		*kv_add(struct kvtree *, char *, char *, int);
 int			 kv_set(struct kv *, char *, ...)
 	__attribute__((__format__(printf, 2, 3)));
@@ -1430,8 +1426,7 @@ void			 imsg_event_add(struct imsgev *);
 int			 imsg_compose_event(struct imsgev *, uint16_t, uint32_t,
     pid_t, int, void *, uint16_t);
 int			 imsg_composev_event(struct imsgev *, uint16_t,
-    uint32_t,
-    pid_t, int, const struct iovec *, int);
+    uint32_t, pid_t, int, const struct iovec *, int);

 /* config.c */
 int	 config_init(struct relayd *);