Implement buf_left() to make some some more buffer handling easier.

buf_left() returns the bytes left in a buffer. This makes the check to
keep MD5_DIGEST_LENGTH bytes unallocated in some messages easier.
From the buf cleanup diff that was OK norby@ and henning@

5 files changed, 21 insertions, 14 deletions

diff --git a/usr.sbin/ospfd/buffer.c b/usr.sbin/ospfd/buffer.c
index 3d5c69d6623..87890529185 100644
--- a/usr.sbin/ospfd/buffer.c
+++ b/usr.sbin/ospfd/buffer.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: buffer.c,v 1.9 2008/10/03 15:20:29 eric Exp $ */
+/*	$OpenBSD: buffer.c,v 1.10 2009/01/31 11:44:49 claudio Exp $ */
 
 /*
  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -121,6 +121,12 @@ buf_seek(struct buf *buf, size_t pos, size_t len)
 	return (buf->buf + pos);
 }
 
+size_t
+buf_left(struct buf *buf)
+{
+	return (buf->max - buf->wpos);
+}
+
 int
 buf_close(struct msgbuf *msgbuf, struct buf *buf)
 {
diff --git a/usr.sbin/ospfd/database.c b/usr.sbin/ospfd/database.c
index 27634437968..960c39c9e12 100644
--- a/usr.sbin/ospfd/database.c
+++ b/usr.sbin/ospfd/database.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: database.c,v 1.25 2009/01/31 08:55:00 claudio Exp $ */
+/*	$OpenBSD: database.c,v 1.26 2009/01/31 11:44:49 claudio Exp $ */
 
 /*
  * Copyright (c) 2005 Claudio Jeker <claudio@openbsd.org>
@@ -91,8 +91,8 @@ send_db_description(struct nbr *nbr)
 
 		/* build LSA list, keep space for a possible md5 sum */
 		for (le = TAILQ_FIRST(&nbr->db_sum_list); le != NULL &&
-		    buf->wpos + sizeof(struct lsa_hdr) < buf->max -
-		    MD5_DIGEST_LENGTH; le = nle) {
+		    buf_left(buf) >= MD5_DIGEST_LENGTH + sizeof(struct lsa_hdr);
+		    le = nle) {
 			nbr->dd_end = nle = TAILQ_NEXT(le, entry);
 			if (buf_add(buf, le->le_lsa, sizeof(struct lsa_hdr)))
 				goto fail;
diff --git a/usr.sbin/ospfd/lsreq.c b/usr.sbin/ospfd/lsreq.c
index a7cc9358c43..757e1f0ca4f 100644
--- a/usr.sbin/ospfd/lsreq.c
+++ b/usr.sbin/ospfd/lsreq.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: lsreq.c,v 1.15 2009/01/31 08:55:00 claudio Exp $ */
+/*	$OpenBSD: lsreq.c,v 1.16 2009/01/31 11:44:49 claudio Exp $ */
 
 /*
  * Copyright (c) 2004, 2005 Esben Norby <norby@openbsd.org>
@@ -66,8 +66,8 @@ send_ls_req(struct nbr *nbr)
 
 	/* LSA header(s), keep space for a possible md5 sum */
 	for (le = TAILQ_FIRST(&nbr->ls_req_list); le != NULL &&
-	    buf->wpos + sizeof(struct ls_req_hdr) < buf->max -
-	    MD5_DIGEST_LENGTH; le = nle) {
+	    buf_left(buf) >= sizeof(struct ls_req_hdr) + MD5_DIGEST_LENGTH;
+	    le = nle) {
 		nbr->ls_req = nle = TAILQ_NEXT(le, entry);
 		ls_req_hdr.type = htonl(le->le_lsa->type);
 		ls_req_hdr.ls_id = le->le_lsa->ls_id;
diff --git a/usr.sbin/ospfd/lsupdate.c b/usr.sbin/ospfd/lsupdate.c
index de564db2da6..ee9a67552b0 100644
--- a/usr.sbin/ospfd/lsupdate.c
+++ b/usr.sbin/ospfd/lsupdate.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: lsupdate.c,v 1.34 2009/01/31 08:55:00 claudio Exp $ */
+/*	$OpenBSD: lsupdate.c,v 1.35 2009/01/31 11:44:49 claudio Exp $ */
 
 /*
  * Copyright (c) 2005 Claudio Jeker <claudio@openbsd.org>
@@ -173,13 +173,13 @@ int
 add_ls_update(struct buf *buf, struct iface *iface, void *data, int len,
     u_int16_t older)
 {
-	size_t		pos;
-	u_int16_t	age;
+	void		*lsage;
+	u_int16_t	 age;
 
-	if (buf->wpos + len >= buf->max - MD5_DIGEST_LENGTH)
+	if (buf_left(buf) < MD5_DIGEST_LENGTH)
 		return (0);
 
-	pos = buf->wpos;
+	lsage = buf_reserve(buf, 0);
 	if (buf_add(buf, data, len)) {
 		log_warn("add_ls_update");
 		return (0);
@@ -191,7 +191,7 @@ add_ls_update(struct buf *buf, struct iface *iface, void *data, int len,
 	if ((age += older + iface->transmit_delay) >= MAX_AGE)
 		age = MAX_AGE;
 	age = htons(age);
-	memcpy(buf_seek(buf, pos, sizeof(age)), &age, sizeof(age));
+	memcpy(lsage, &age, sizeof(age));
 
 	return (1);
 }
diff --git a/usr.sbin/ospfd/ospfd.h b/usr.sbin/ospfd/ospfd.h
index 2b63edb9e21..b164d1d674f 100644
--- a/usr.sbin/ospfd/ospfd.h
+++ b/usr.sbin/ospfd/ospfd.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ospfd.h,v 1.74 2009/01/07 21:16:36 claudio Exp $ */
+/*	$OpenBSD: ospfd.h,v 1.75 2009/01/31 11:44:49 claudio Exp $ */
 
 /*
  * Copyright (c) 2004 Esben Norby <norby@openbsd.org>
@@ -561,6 +561,7 @@ struct buf	*buf_dynamic(size_t, size_t);
 int		 buf_add(struct buf *, void *, size_t);
 void		*buf_reserve(struct buf *, size_t);
 void		*buf_seek(struct buf *, size_t, size_t);
+size_t		 buf_left(struct buf *);
 int		 buf_close(struct msgbuf *, struct buf *);
 void		 buf_free(struct buf *);
 void		 msgbuf_init(struct msgbuf *);