Extend imsg and ibuf API with useful getter methods

For ibufs:
- various getters for ibufs (ibuf_get* and ibuf_skip)
- additional ibuf set/add functions that don't alter byte order
- ibuf_truncate and ibuf_rewind
- ibuf_from_buffer and ibuf_from_ibuf to populate a reader ibuf
- a getter for the msgbuf queuelen

For imsg:
- various getters for imsg (especially imsg_get_data() which can be used
  in most cases as a simple one call api with all error checks).
  All the imsg.hdr fields can also be accessed by getters.
- The imsg data is now actually an ibuf but the old imsg.data pointer is
  kept for now to not break every imsg application.
- Introduce imsg_forward to simply forward a message from one channel to
  an other (used in the control socket code).

Since this requires a major bump take the oportunity to also cleanup some
function signatures to use size_t for length fields. Also internal data
structures are removed from the public header.

With and OK tb@

5 files changed, 452 insertions, 67 deletions

diff --git a/lib/libutil/Symbols.map b/lib/libutil/Symbols.map
index 00472fbb33f..c1bac13aa21 100644
--- a/lib/libutil/Symbols.map
+++ b/lib/libutil/Symbols.map
@@ -19,10 +19,14 @@
 		getrawpartition;
 		ibuf_add;
 		ibuf_add_buf;
-		ibuf_add_n8;
+		ibuf_add_ibuf;
+		ibuf_add_h16;
+		ibuf_add_h32;
+		ibuf_add_h64;
 		ibuf_add_n16;
 		ibuf_add_n32;
 		ibuf_add_n64;
+		ibuf_add_n8;
 		ibuf_add_zero;
 		ibuf_close;
 		ibuf_data;
@@ -31,28 +35,53 @@
 		ibuf_fd_get;
 		ibuf_fd_set;
 		ibuf_free;
+		ibuf_from_buffer;
+		ibuf_from_ibuf;
+		ibuf_get;
+		ibuf_get_ibuf;
+		ibuf_get_h16;
+		ibuf_get_h32;
+		ibuf_get_h64;
+		ibuf_get_n16;
+		ibuf_get_n32;
+		ibuf_get_n64;
+		ibuf_get_n8;
 		ibuf_left;
 		ibuf_open;
 		ibuf_reserve;
+		ibuf_rewind;
 		ibuf_seek;
 		ibuf_set;
-		ibuf_set_n8;
+		ibuf_set_h16;
+		ibuf_set_h32;
+		ibuf_set_h64;
 		ibuf_set_n16;
 		ibuf_set_n32;
 		ibuf_set_n64;
+		ibuf_set_n8;
 		ibuf_size;
+		ibuf_skip;
+		ibuf_truncate;
 		ibuf_write;
 		imsg_add;
 		imsg_clear;
 		imsg_close;
 		imsg_compose;
-		imsg_composev;
 		imsg_compose_ibuf;
+		imsg_composev;
 		imsg_create;
 		imsg_fd_overhead;
 		imsg_flush;
+		imsg_forward;
 		imsg_free;
 		imsg_get;
+		imsg_get_ibuf;
+		imsg_get_data;
+		imsg_get_fd;
+		imsg_get_id;
+		imsg_get_len;
+		imsg_get_pid;
+		imsg_get_type;
 		imsg_init;
 		imsg_read;
 		isduid;
@@ -64,6 +93,7 @@
 		logwtmp;
 		msgbuf_clear;
 		msgbuf_init;
+		msgbuf_queuelen;
 		msgbuf_write;
 		ober_add_bitstring;
 		ober_add_boolean;
diff --git a/lib/libutil/imsg-buffer.c b/lib/libutil/imsg-buffer.c
index e54904226eb..0708f486ee1 100644
--- a/lib/libutil/imsg-buffer.c
+++ b/lib/libutil/imsg-buffer.c
@@ -1,6 +1,7 @@
-/*	$OpenBSD: imsg-buffer.c,v 1.17 2023/10/24 14:05:23 claudio Exp $	*/
+/*	$OpenBSD: imsg-buffer.c,v 1.18 2023/12/12 15:47:41 claudio Exp $	*/
 
 /*
+ * Copyright (c) 2023 Claudio Jeker <claudio@openbsd.org>
  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
  *
  * Permission to use, copy, modify, and distribute this software for any
@@ -24,6 +25,7 @@
 #include <limits.h>
 #include <errno.h>
 #include <endian.h>
+#include <stdint.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
@@ -61,7 +63,7 @@ ibuf_dynamic(size_t len, size_t max)
 {
 	struct ibuf	*buf;
 
-	if (max < len) {
+	if (max == 0 || max < len) {
 		errno = EINVAL;
 		return (NULL);
 	}
@@ -106,7 +108,7 @@ ibuf_reserve(struct ibuf *buf, size_t len)
 {
 	void	*b;
 
-	if (len > SIZE_MAX - buf->wpos) {
+	if (len > SIZE_MAX - buf->wpos || buf->max == 0) {
 		errno = ERANGE;
 		return (NULL);
 	}
@@ -117,7 +119,6 @@ ibuf_reserve(struct ibuf *buf, size_t len)
 
 	b = buf->buf + buf->wpos;
 	buf->wpos += len;
-	memset(b, 0, len);
 	return (b);
 }
 
@@ -134,9 +135,16 @@ ibuf_add(struct ibuf *buf, const void *data, size_t len)
 }
 
 int
+ibuf_add_ibuf(struct ibuf *buf, const struct ibuf *from)
+{
+	return ibuf_add(buf, ibuf_data(from), ibuf_size(from));
+}
+
+/* remove after tree is converted */
+int
 ibuf_add_buf(struct ibuf *buf, const struct ibuf *from)
 {
-	return ibuf_add(buf, from->buf, from->wpos);
+	return ibuf_add_ibuf(buf, from);
 }
 
 int
@@ -186,25 +194,59 @@ ibuf_add_n64(struct ibuf *buf, uint64_t value)
 }
 
 int
+ibuf_add_h16(struct ibuf *buf, uint64_t value)
+{
+	uint16_t v;
+
+	if (value > UINT16_MAX) {
+		errno = EINVAL;
+		return (-1);
+	}
+	v = value;
+	return ibuf_add(buf, &v, sizeof(v));
+}
+
+int
+ibuf_add_h32(struct ibuf *buf, uint64_t value)
+{
+	uint32_t v;
+
+	if (value > UINT32_MAX) {
+		errno = EINVAL;
+		return (-1);
+	}
+	v = value;
+	return ibuf_add(buf, &v, sizeof(v));
+}
+
+int
+ibuf_add_h64(struct ibuf *buf, uint64_t value)
+{
+	return ibuf_add(buf, &value, sizeof(value));
+}
+
+int
 ibuf_add_zero(struct ibuf *buf, size_t len)
 {
 	void *b;
 
 	if ((b = ibuf_reserve(buf, len)) == NULL)
 		return (-1);
+	memset(b, 0, len);
 	return (0);
 }
 
 void *
 ibuf_seek(struct ibuf *buf, size_t pos, size_t len)
 {
-	/* only allowed to seek in already written parts */
-	if (len > SIZE_MAX - pos || pos + len > buf->wpos) {
+	/* only allow seeking between rpos and wpos */
+	if (ibuf_size(buf) < pos || SIZE_MAX - pos < len ||
+	    ibuf_size(buf) < pos + len) {
 		errno = ERANGE;
 		return (NULL);
 	}
 
-	return (buf->buf + pos);
+	return (buf->buf + buf->rpos + pos);
 }
 
 int
@@ -265,24 +307,79 @@ ibuf_set_n64(struct ibuf *buf, size_t pos, uint64_t value)
 	return (ibuf_set(buf, pos, &value, sizeof(value)));
 }
 
+int
+ibuf_set_h16(struct ibuf *buf, size_t pos, uint64_t value)
+{
+	uint16_t v;
+
+	if (value > UINT16_MAX) {
+		errno = EINVAL;
+		return (-1);
+	}
+	v = value;
+	return (ibuf_set(buf, pos, &v, sizeof(v)));
+}
+
+int
+ibuf_set_h32(struct ibuf *buf, size_t pos, uint64_t value)
+{
+	uint32_t v;
+
+	if (value > UINT32_MAX) {
+		errno = EINVAL;
+		return (-1);
+	}
+	v = value;
+	return (ibuf_set(buf, pos, &v, sizeof(v)));
+}
+
+int
+ibuf_set_h64(struct ibuf *buf, size_t pos, uint64_t value)
+{
+	return (ibuf_set(buf, pos, &value, sizeof(value)));
+}
+
 void *
-ibuf_data(struct ibuf *buf)
+ibuf_data(const struct ibuf *buf)
 {
-	return (buf->buf);
+	return (buf->buf + buf->rpos);
 }
 
 size_t
-ibuf_size(struct ibuf *buf)
+ibuf_size(const struct ibuf *buf)
 {
-	return (buf->wpos);
+	return (buf->wpos - buf->rpos);
 }
 
 size_t
-ibuf_left(struct ibuf *buf)
+ibuf_left(const struct ibuf *buf)
 {
+	if (buf->max == 0)
+		return (0);
 	return (buf->max - buf->wpos);
 }
 
+int
+ibuf_truncate(struct ibuf *buf, size_t len)
+{
+	if (ibuf_size(buf) >= len) {
+		buf->wpos = buf->rpos + len;
+		return (0);
+	}
+	if (buf->max == 0) {
+		/* only allow to truncate down */
+		errno = ERANGE;
+		return (-1);
+	}
+	return ibuf_add_zero(buf, len - ibuf_size(buf));
+}
+
+void
+ibuf_rewind(struct ibuf *buf)
+{
+	buf->rpos = 0;
+}
+
 void
 ibuf_close(struct msgbuf *msgbuf, struct ibuf *buf)
 {
@@ -290,10 +387,119 @@ ibuf_close(struct msgbuf *msgbuf, struct ibuf *buf)
 }
 
 void
+ibuf_from_buffer(struct ibuf *buf, void *data, size_t len)
+{
+	memset(buf, 0, sizeof(*buf));
+	buf->buf = data;
+	buf->size = buf->wpos = len;
+	buf->fd = -1;
+}
+
+void
+ibuf_from_ibuf(struct ibuf *buf, const struct ibuf *from)
+{
+	ibuf_from_buffer(buf, ibuf_data(from), ibuf_size(from));
+}
+
+int
+ibuf_get(struct ibuf *buf, void *data, size_t len)
+{
+	if (ibuf_size(buf) < len) {
+		errno = EBADMSG;
+		return (-1);
+	}
+
+	memcpy(data, ibuf_data(buf), len);
+	buf->rpos += len;
+	return (0);
+}
+
+int
+ibuf_get_ibuf(struct ibuf *buf, size_t len, struct ibuf *new)
+{
+	if (ibuf_size(buf) < len) {
+		errno = EBADMSG;
+		return (-1);
+	}
+
+	ibuf_from_buffer(new, ibuf_data(buf), len);
+	buf->rpos += len;
+	return (0);
+}
+
+int
+ibuf_get_n8(struct ibuf *buf, uint8_t *value)
+{
+	return ibuf_get(buf, value, sizeof(*value));
+}
+
+int
+ibuf_get_n16(struct ibuf *buf, uint16_t *value)
+{
+	int rv;
+
+	rv = ibuf_get(buf, value, sizeof(*value));
+	*value = be16toh(*value);
+	return (rv);
+}
+
+int
+ibuf_get_n32(struct ibuf *buf, uint32_t *value)
+{
+	int rv;
+
+	rv = ibuf_get(buf, value, sizeof(*value));
+	*value = be32toh(*value);
+	return (rv);
+}
+
+int
+ibuf_get_n64(struct ibuf *buf, uint64_t *value)
+{
+	int rv;
+
+	rv = ibuf_get(buf, value, sizeof(*value));
+	*value = be64toh(*value);
+	return (rv);
+}
+
+int
+ibuf_get_h16(struct ibuf *buf, uint16_t *value)
+{
+	return ibuf_get(buf, value, sizeof(*value));
+}
+
+int
+ibuf_get_h32(struct ibuf *buf, uint32_t *value)
+{
+	return ibuf_get(buf, value, sizeof(*value));
+}
+
+int
+ibuf_get_h64(struct ibuf *buf, uint64_t *value)
+{
+	return ibuf_get(buf, value, sizeof(*value));
+}
+
+int
+ibuf_skip(struct ibuf *buf, size_t len)
+{
+	if (ibuf_size(buf) < len) {
+		errno = EBADMSG;
+		return (-1);
+	}
+
+	buf->rpos += len;
+	return (0);
+}
+
+void
 ibuf_free(struct ibuf *buf)
 {
 	if (buf == NULL)
 		return;
+	if (buf->max == 0)	/* if buf lives on the stack */
+		abort();	/* abort before causing more harm */
 	if (buf->fd != -1)
 		close(buf->fd);
 	freezero(buf->buf, buf->size);
@@ -319,6 +525,8 @@ ibuf_fd_get(struct ibuf *buf)
 void
 ibuf_fd_set(struct ibuf *buf, int fd)
 {
+	if (buf->max == 0)	/* if buf lives on the stack */
+		abort();	/* abort before causing more harm */
 	if (buf->fd != -1)
 		close(buf->fd);
 	buf->fd = fd;
@@ -336,8 +544,8 @@ ibuf_write(struct msgbuf *msgbuf)
 	TAILQ_FOREACH(buf, &msgbuf->bufs, entry) {
 		if (i >= IOV_MAX)
 			break;
-		iov[i].iov_base = buf->buf + buf->rpos;
-		iov[i].iov_len = buf->wpos - buf->rpos;
+		iov[i].iov_base = ibuf_data(buf);
+		iov[i].iov_len = ibuf_size(buf);
 		i++;
 	}
 
@@ -376,8 +584,8 @@ msgbuf_drain(struct msgbuf *msgbuf, size_t n)
 	for (buf = TAILQ_FIRST(&msgbuf->bufs); buf != NULL && n > 0;
 	    buf = next) {
 		next = TAILQ_NEXT(buf, entry);
-		if (n >= buf->wpos - buf->rpos) {
-			n -= buf->wpos - buf->rpos;
+		if (n >= ibuf_size(buf)) {
+			n -= ibuf_size(buf);
 			ibuf_dequeue(msgbuf, buf);
 		} else {
 			buf->rpos += n;
@@ -417,8 +625,8 @@ msgbuf_write(struct msgbuf *msgbuf)
 			break;
 		if (i > 0 && buf->fd != -1)
 			break;
-		iov[i].iov_base = buf->buf + buf->rpos;
-		iov[i].iov_len = buf->wpos - buf->rpos;
+		iov[i].iov_base = ibuf_data(buf);
+		iov[i].iov_len = ibuf_size(buf);
 		i++;
 		if (buf->fd != -1)
 			buf0 = buf;
@@ -465,9 +673,17 @@ again:
 	return (1);
 }
 
+uint32_t
+msgbuf_queuelen(struct msgbuf *msgbuf)
+{
+	return (msgbuf->queued);
+}
+
 static void
 ibuf_enqueue(struct msgbuf *msgbuf, struct ibuf *buf)
 {
+	if (buf->max == 0)	/* if buf lives on the stack */
+		abort();	/* abort before causing more harm */
 	TAILQ_INSERT_TAIL(&msgbuf->bufs, buf, entry);
 	msgbuf->queued++;
 }
@@ -476,7 +692,6 @@ static void
 ibuf_dequeue(struct msgbuf *msgbuf, struct ibuf *buf)
 {
 	TAILQ_REMOVE(&msgbuf->bufs, buf, entry);
-
 	msgbuf->queued--;
 	ibuf_free(buf);
 }
diff --git a/lib/libutil/imsg.c b/lib/libutil/imsg.c
index b6cc37ee1b7..0aff226bfc9 100644
--- a/lib/libutil/imsg.c
+++ b/lib/libutil/imsg.c
@@ -1,6 +1,7 @@
-/*	$OpenBSD: imsg.c,v 1.22 2023/11/18 07:14:13 claudio Exp $	*/
+/*	$OpenBSD: imsg.c,v 1.23 2023/12/12 15:47:41 claudio Exp $	*/
 
 /*
+ * Copyright (c) 2023 Claudio Jeker <claudio@openbsd.org>
  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
  *
  * Permission to use, copy, modify, and distribute this software for any
@@ -28,6 +29,11 @@
 
 #include "imsg.h"
 
+struct imsg_fd {
+	TAILQ_ENTRY(imsg_fd)	entry;
+	int			fd;
+};
+
 int	 imsg_fd_overhead = 0;
 
 static int	 imsg_dequeue_fd(struct imsgbuf *);
@@ -123,6 +129,7 @@ fail:
 ssize_t
 imsg_get(struct imsgbuf *imsgbuf, struct imsg *imsg)
 {
+	struct imsg		 m;
 	size_t			 av, left, datalen;
 
 	av = imsgbuf->r.wpos;
@@ -130,42 +137,108 @@ imsg_get(struct imsgbuf *imsgbuf, struct imsg *imsg)
 	if (IMSG_HEADER_SIZE > av)
 		return (0);
 
-	memcpy(&imsg->hdr, imsgbuf->r.buf, sizeof(imsg->hdr));
-	if (imsg->hdr.len < IMSG_HEADER_SIZE ||
-	    imsg->hdr.len > MAX_IMSGSIZE) {
+	memcpy(&m.hdr, imsgbuf->r.buf, sizeof(m.hdr));
+	if (m.hdr.len < IMSG_HEADER_SIZE ||
+	    m.hdr.len > MAX_IMSGSIZE) {
 		errno = ERANGE;
 		return (-1);
 	}
-	if (imsg->hdr.len > av)
+	if (m.hdr.len > av)
 		return (0);
-	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
-	imsgbuf->r.rptr = imsgbuf->r.buf + IMSG_HEADER_SIZE;
-	if (datalen == 0)
-		imsg->data = NULL;
-	else if ((imsg->data = malloc(datalen)) == NULL)
-		return (-1);
 
-	if (imsg->hdr.flags & IMSGF_HASFD)
-		imsg->fd = imsg_dequeue_fd(imsgbuf);
-	else
-		imsg->fd = -1;
+	m.fd = -1;
+	m.buf = NULL;
+	m.data = NULL;
+
+	datalen = m.hdr.len - IMSG_HEADER_SIZE;
+	imsgbuf->r.rptr = imsgbuf->r.buf + IMSG_HEADER_SIZE;
+	if (datalen != 0) {
+		if ((m.buf = ibuf_open(datalen)) == NULL)
+			return (-1);
+		if (ibuf_add(m.buf, imsgbuf->r.rptr, datalen) == -1) {
+			/* this should never fail */
+			ibuf_free(m.buf);
+			return (-1);
+		}
+		m.data = ibuf_data(m.buf);
+	}
 
-	if (datalen != 0)
-		memcpy(imsg->data, imsgbuf->r.rptr, datalen);
+	if (m.hdr.flags & IMSGF_HASFD)
+		m.fd = imsg_dequeue_fd(imsgbuf);
 
-	if (imsg->hdr.len < av) {
-		left = av - imsg->hdr.len;
-		memmove(&imsgbuf->r.buf, imsgbuf->r.buf + imsg->hdr.len, left);
+	if (m.hdr.len < av) {
+		left = av - m.hdr.len;
+		memmove(&imsgbuf->r.buf, imsgbuf->r.buf + m.hdr.len, left);
 		imsgbuf->r.wpos = left;
 	} else
 		imsgbuf->r.wpos = 0;
 
+	*imsg = m;
 	return (datalen + IMSG_HEADER_SIZE);
 }
 
 int
+imsg_get_ibuf(struct imsg *imsg, struct ibuf *ibuf)
+{
+	if (imsg->buf == NULL) {
+		errno = EBADMSG;
+		return (-1);
+	}
+	return ibuf_get_ibuf(imsg->buf, ibuf_size(imsg->buf), ibuf);
+}
+
+int
+imsg_get_data(struct imsg *imsg, void *data, size_t len)
+{
+	if (len == 0) {
+		errno = EINVAL;
+		return (-1);
+	}
+	if (imsg->buf == NULL || ibuf_size(imsg->buf) != len) {
+		errno = EBADMSG;
+		return (-1);
+	}
+	return ibuf_get(imsg->buf, data, len);
+}
+
+int
+imsg_get_fd(struct imsg *imsg)
+{
+	int fd = imsg->fd;
+
+	imsg->fd = -1;
+	return fd;
+}
+
+uint32_t
+imsg_get_id(struct imsg *imsg)
+{
+	return (imsg->hdr.peerid);
+}
+
+size_t
+imsg_get_len(struct imsg *imsg)
+{
+	if (imsg->buf == NULL)
+		return 0;
+	return ibuf_size(imsg->buf);
+}
+
+pid_t
+imsg_get_pid(struct imsg *imsg)
+{
+	return (imsg->hdr.pid);
+}
+
+uint32_t
+imsg_get_type(struct imsg *imsg)
+{
+	return (imsg->hdr.type);
+}
+
+int
 imsg_compose(struct imsgbuf *imsgbuf, uint32_t type, uint32_t id, pid_t pid,
-    int fd, const void *data, uint16_t datalen)
+    int fd, const void *data, size_t datalen)
 {
 	struct ibuf	*wbuf;
 
@@ -186,7 +259,8 @@ imsg_composev(struct imsgbuf *imsgbuf, uint32_t type, uint32_t id, pid_t pid,
     int fd, const struct iovec *iov, int iovcnt)
 {
 	struct ibuf	*wbuf;
-	int		 i, datalen = 0;
+	int		 i;
+	size_t		 datalen = 0;
 
 	for (i = 0; i < iovcnt; i++)
 		datalen += iov[i].iov_len;
@@ -204,11 +278,15 @@ imsg_composev(struct imsgbuf *imsgbuf, uint32_t type, uint32_t id, pid_t pid,
 	return (1);
 }
 
+/*
+ * Enqueue imsg with payload from ibuf buf. fd passing is not possible 
+ * with this function.
+ */
 int
 imsg_compose_ibuf(struct imsgbuf *imsgbuf, uint32_t type, uint32_t id,
     pid_t pid, struct ibuf *buf)
 {
-	struct ibuf	*wbuf = NULL;
+	struct ibuf	*hdrbuf = NULL;
 	struct imsg_hdr	 hdr;
 	int save_errno;
 
@@ -224,26 +302,60 @@ imsg_compose_ibuf(struct imsgbuf *imsgbuf, uint32_t type, uint32_t id,
 	if ((hdr.pid = pid) == 0)
 		hdr.pid = imsgbuf->pid;
 
-	if ((wbuf = ibuf_open(IMSG_HEADER_SIZE)) == NULL)
+	if ((hdrbuf = ibuf_open(IMSG_HEADER_SIZE)) == NULL)
 		goto fail;
-	if (imsg_add(wbuf, &hdr, sizeof(hdr)) == -1)
+	if (imsg_add(hdrbuf, &hdr, sizeof(hdr)) == -1)
 		goto fail;
 
-	ibuf_close(&imsgbuf->w, wbuf);
+	ibuf_close(&imsgbuf->w, hdrbuf);
 	ibuf_close(&imsgbuf->w, buf);
 	return (1);
 
  fail:
 	save_errno = errno;
 	ibuf_free(buf);
-	ibuf_free(wbuf);
+	ibuf_free(hdrbuf);
 	errno = save_errno;
 	return (-1);
 }
 
+/*
+ * Forward imsg to another channel. Any attached fd is closed.
+ */
+int
+imsg_forward(struct imsgbuf *imsgbuf, struct imsg *msg)
+{
+	struct ibuf	*wbuf;
+	size_t		 len = 0;
+
+	if (msg->fd != -1) {
+		close(msg->fd);
+		msg->fd = -1;
+	}
+
+	if (msg->buf != NULL) {
+		ibuf_rewind(msg->buf);
+		len = ibuf_size(msg->buf);
+	}
+
+	if ((wbuf = imsg_create(imsgbuf, msg->hdr.type, msg->hdr.peerid,
+	    msg->hdr.pid, len)) == NULL)
+		return (-1);
+
+	if (msg->buf != NULL) {
+		if (ibuf_add_buf(wbuf, msg->buf) == -1) {
+			ibuf_free(wbuf);
+			return (-1);
+		}
+	}
+
+	imsg_close(imsgbuf, wbuf);
+	return (1);
+}
+
 struct ibuf *
 imsg_create(struct imsgbuf *imsgbuf, uint32_t type, uint32_t id, pid_t pid,
-    uint16_t datalen)
+    size_t datalen)
 {
 	struct ibuf	*wbuf;
 	struct imsg_hdr	 hdr;
@@ -269,7 +381,7 @@ imsg_create(struct imsgbuf *imsgbuf, uint32_t type, uint32_t id, pid_t pid,
 }
 
 int
-imsg_add(struct ibuf *msg, const void *data, uint16_t datalen)
+imsg_add(struct ibuf *msg, const void *data, size_t datalen)
 {
 	if (datalen)
 		if (ibuf_add(msg, data, datalen) == -1) {
@@ -297,7 +409,7 @@ imsg_close(struct imsgbuf *imsgbuf, struct ibuf *msg)
 void
 imsg_free(struct imsg *imsg)
 {
-	freezero(imsg->data, imsg->hdr.len - IMSG_HEADER_SIZE);
+	ibuf_free(imsg->buf);
 }
 
 static int
diff --git a/lib/libutil/imsg.h b/lib/libutil/imsg.h
index fb516e30287..dd47b1889da 100644
--- a/lib/libutil/imsg.h
+++ b/lib/libutil/imsg.h
@@ -1,6 +1,7 @@
-/*	$OpenBSD: imsg.h,v 1.7 2023/06/19 17:19:50 claudio Exp $	*/
+/*	$OpenBSD: imsg.h,v 1.8 2023/12/12 15:47:41 claudio Exp $	*/
 
 /*
+ * Copyright (c) 2023 Claudio Jeker <claudio@openbsd.org>
  * Copyright (c) 2006, 2007 Pierre-Yves Ritschard <pyr@openbsd.org>
  * Copyright (c) 2006, 2007, 2008 Reyk Floeter <reyk@openbsd.org>
  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -21,7 +22,7 @@
 #ifndef _IMSG_H_
 #define _IMSG_H_
 
-#include <stdint.h>
+#include <sys/types.h>
 
 #define IBUF_READ_SIZE		65535
 #define IMSG_HEADER_SIZE	sizeof(struct imsg_hdr)
@@ -49,11 +50,7 @@ struct ibuf_read {
 	size_t			 wpos;
 };
 
-struct imsg_fd {
-	TAILQ_ENTRY(imsg_fd)	entry;
-	int			fd;
-};
-
+struct imsg_fd;
 struct imsgbuf {
 	TAILQ_HEAD(, imsg_fd)	 fds;
 	struct ibuf_read	 r;
@@ -76,6 +73,7 @@ struct imsg {
 	struct imsg_hdr	 hdr;
 	int		 fd;
 	void		*data;
+	struct ibuf	*buf;
 };
 
 struct iovec;
@@ -85,11 +83,15 @@ struct ibuf	*ibuf_open(size_t);
 struct ibuf	*ibuf_dynamic(size_t, size_t);
 int		 ibuf_add(struct ibuf *, const void *, size_t);
 int		 ibuf_add_buf(struct ibuf *, const struct ibuf *);
+int		 ibuf_add_ibuf(struct ibuf *, const struct ibuf *);
 int		 ibuf_add_zero(struct ibuf *, size_t);
 int		 ibuf_add_n8(struct ibuf *, uint64_t);
 int		 ibuf_add_n16(struct ibuf *, uint64_t);
 int		 ibuf_add_n32(struct ibuf *, uint64_t);
 int		 ibuf_add_n64(struct ibuf *, uint64_t);
+int		 ibuf_add_h16(struct ibuf *, uint64_t);
+int		 ibuf_add_h32(struct ibuf *, uint64_t);
+int		 ibuf_add_h64(struct ibuf *, uint64_t);
 void		*ibuf_reserve(struct ibuf *, size_t);
 void		*ibuf_seek(struct ibuf *, size_t, size_t);
 int		 ibuf_set(struct ibuf *, size_t, const void *, size_t);
@@ -97,10 +99,27 @@ int		 ibuf_set_n8(struct ibuf *, size_t, uint64_t);
 int		 ibuf_set_n16(struct ibuf *, size_t, uint64_t);
 int		 ibuf_set_n32(struct ibuf *, size_t, uint64_t);
 int		 ibuf_set_n64(struct ibuf *, size_t, uint64_t);
-void		*ibuf_data(struct ibuf *);
-size_t		 ibuf_size(struct ibuf *);
-size_t		 ibuf_left(struct ibuf *);
+int		 ibuf_set_h16(struct ibuf *, size_t, uint64_t);
+int		 ibuf_set_h32(struct ibuf *, size_t, uint64_t);
+int		 ibuf_set_h64(struct ibuf *, size_t, uint64_t);
+void		*ibuf_data(const struct ibuf *);
+size_t		 ibuf_size(const struct ibuf *);
+size_t		 ibuf_left(const struct ibuf *);
+int		 ibuf_truncate(struct ibuf *, size_t);
+void		 ibuf_rewind(struct ibuf *);
 void		 ibuf_close(struct msgbuf *, struct ibuf *);
+void		 ibuf_from_buffer(struct ibuf *, void *, size_t);
+void		 ibuf_from_ibuf(struct ibuf *, const struct ibuf *);
+int		 ibuf_get(struct ibuf *, void *, size_t);
+int		 ibuf_get_ibuf(struct ibuf *, size_t, struct ibuf *);
+int		 ibuf_get_n8(struct ibuf *, uint8_t *);
+int		 ibuf_get_n16(struct ibuf *, uint16_t *);
+int		 ibuf_get_n32(struct ibuf *, uint32_t *);
+int		 ibuf_get_n64(struct ibuf *, uint64_t *);
+int		 ibuf_get_h16(struct ibuf *, uint16_t *);
+int		 ibuf_get_h32(struct ibuf *, uint32_t *);
+int		 ibuf_get_h64(struct ibuf *, uint64_t *);
+int		 ibuf_skip(struct ibuf *, size_t);
 void		 ibuf_free(struct ibuf *);
 int		 ibuf_fd_avail(struct ibuf *);
 int		 ibuf_fd_get(struct ibuf *);
@@ -108,20 +127,29 @@ void		 ibuf_fd_set(struct ibuf *, int);
 int		 ibuf_write(struct msgbuf *);
 void		 msgbuf_init(struct msgbuf *);
 void		 msgbuf_clear(struct msgbuf *);
+uint32_t	 msgbuf_queuelen(struct msgbuf *);
 int		 msgbuf_write(struct msgbuf *);
 
 /* imsg.c */
 void	 imsg_init(struct imsgbuf *, int);
 ssize_t	 imsg_read(struct imsgbuf *);
 ssize_t	 imsg_get(struct imsgbuf *, struct imsg *);
+int	 imsg_get_ibuf(struct imsg *, struct ibuf *);
+int	 imsg_get_data(struct imsg *, void *, size_t);
+int	 imsg_get_fd(struct imsg *);
+uint32_t imsg_get_id(struct imsg *);
+size_t	 imsg_get_len(struct imsg *);
+pid_t	 imsg_get_pid(struct imsg *);
+uint32_t imsg_get_type(struct imsg *);
+int	 imsg_forward(struct imsgbuf *, struct imsg *);
 int	 imsg_compose(struct imsgbuf *, uint32_t, uint32_t, pid_t, int,
-	    const void *, uint16_t);
+	    const void *, size_t);
 int	 imsg_composev(struct imsgbuf *, uint32_t, uint32_t,  pid_t, int,
 	    const struct iovec *, int);
 int	 imsg_compose_ibuf(struct imsgbuf *, uint32_t, uint32_t, pid_t,
 	    struct ibuf *);
-struct ibuf *imsg_create(struct imsgbuf *, uint32_t, uint32_t, pid_t, uint16_t);
-int	 imsg_add(struct ibuf *, const void *, uint16_t);
+struct ibuf *imsg_create(struct imsgbuf *, uint32_t, uint32_t, pid_t, size_t);
+int	 imsg_add(struct ibuf *, const void *, size_t);
 void	 imsg_close(struct imsgbuf *, struct ibuf *);
 void	 imsg_free(struct imsg *);
 int	 imsg_flush(struct imsgbuf *);
diff --git a/lib/libutil/shlib_version b/lib/libutil/shlib_version
index ffdd3d2d569..94727e17b3a 100644
--- a/lib/libutil/shlib_version
+++ b/lib/libutil/shlib_version
@@ -1,2 +1,2 @@
-major=17
+major=18
 minor=0