diff options
| author |   otto <otto@openbsd.org> | 2017-04-03 19:42:04 +0000 |
|---|---|---|
| committer | otto <otto@openbsd.org> | 2017-04-03 19:42:04 +0000 |
| commit | 4229d575b34e5024b34c29ae4b8851aecc64b0d8 (patch) | |
| tree | 8503712e64dc4f0cb76c423a0a234c10684e6fe5 /lib/libc | |
| parent | Send and receive 1 byte of data in addition to the control message. This is (diff) | |
| download | wireguard-openbsd-4229d575b34e5024b34c29ae4b8851aecc64b0d8.tar.xz wireguard-openbsd-4229d575b34e5024b34c29ae4b8851aecc64b0d8.zip | |
Add caveat telling it's better to always read a data byte when passing
control messages.
Problem noted by Luke Small; ok deraadt@
Diffstat (limited to 'lib/libc')
| -rw-r--r-- | lib/libc/sys/recv.2 | 16 |
1 files changed, 14 insertions, 2 deletions
diff --git a/lib/libc/sys/recv.2 b/lib/libc/sys/recv.2 index 5f9c51fd7ef..7b312b2ba8d 100644 --- a/lib/libc/sys/recv.2 +++ b/lib/libc/sys/recv.2 @@ -1,4 +1,4 @@ -.\" $OpenBSD: recv.2,v 1.43 2015/02/16 16:20:15 tedu Exp $ +.\" $OpenBSD: recv.2,v 1.44 2017/04/03 19:42:04 otto Exp $ .\" $NetBSD: recv.2,v 1.6 1995/02/27 12:36:08 cgd Exp $ .\" .\" Copyright (c) 1983, 1990, 1991, 1993 @@ -30,7 +30,7 @@ .\" .\" @(#)recv.2 8.3 (Berkeley) 2/21/94 .\" -.Dd $Mdocdate: February 16 2015 $ +.Dd $Mdocdate: April 3 2017 $ .Dt RECV 2 .Os .Sh NAME @@ -364,3 +364,15 @@ The .Fn recv function call appeared in .Bx 4.2 . +.Sh CAVEATS +Calling +.Fn recvmsg +with a control message having no or an empty scatter/gather array +exposes variations in implementations. +To avoid these, always use an +.Fa iovec +with at least a one byte buffer and set +.Fa msg_iov +and an +.Fa msg_iovlen +to use this vector. |