Let listen() return EDESTADDRREQ when not bound.

We currently return EINVAL when calling listen() on a UNIX socket that
has not been bound to a pathname. If my interpretation of POSIX is
correct, we should return EDESTADDRREQ: "The socket is not bound to a
local address, and the protocol does not support listening on an unbound
socket."

Return EDESTADDRREQ instead when not bound and not connected.

Differential Revision:	https://reviews.freebsd.org/D3038
Reviewed by:	gnn, network

1 files changed, 3 insertions, 1 deletions

diff --git a/sys/kern/uipc_usrreq.c b/sys/kern/uipc_usrreq.c
index acf9fe9..7b2984c 100644
--- a/sys/kern/uipc_usrreq.c
+++ b/sys/kern/uipc_usrreq.c
@@ -736,8 +736,10 @@ uipc_listen(struct socket *so, int backlog, struct thread *td)
 
 	UNP_PCB_LOCK(unp);
 	if (unp->unp_vnode == NULL) {
+		/* Already connected or not bound to an address. */
+		error = unp->unp_conn != NULL ? EINVAL : EDESTADDRREQ;
 		UNP_PCB_UNLOCK(unp);
-		return (EINVAL);
+		return (error);
 	}
 
 	SOCK_LOCK(so);