From d34caa2aee1d84597ae610ffd209c1a558ad1fb0 Mon Sep 17 00:00:00 2001 From: Bernard Pidoux Date: Fri, 21 Nov 2008 18:48:26 +0100 Subject: [PATCH] [ROSE] zero length frame filtering in af_rose.c Since changeset e79ad711a0108475c1b3a03815527e7237020b08 from mainline. From David S. Miller. empty packet can be transmitted on connected socket for datagram protocols. However, this patch broke a high level application using ROSE network protocol with connected datagram. Bulletin Board Stations perform bulletins forwarding between BBS stations via ROSE network using a forward protocol. Now, if for some reason, a buffer in the application software happens to be empty at a specific moment, ROSE sends an empty packet via unfiltred packet socket. When received, this ROSE packet introduces perturbations of data exchange of BBS forwarding, for the application message forwarding protocol is waiting for something else. We agree that a more carefull programming of the application protocole would avoid this situation and we are willing to debug it. But, as an empty frame is no use and does not have any meaning for ROSE protocol, we may consider filtering zero length data both when sending and receiving socket data. The proposed patch repaired BBS data exchange through ROSE network that were broken since 2.6.22.11 kernel. Signed-off-by: Bernard Pidoux --- net/rose/af_rose.c | 10 ++++++++++ 1 files changed, 10 insertions(+), 0 deletions(-) diff --git a/net/rose/af_rose.c b/net/rose/af_rose.c index 8a54cff..92af3a6 100644 --- a/net/rose/af_rose.c +++ b/net/rose/af_rose.c @@ -1075,6 +1075,10 @@ static int rose_sendmsg(struct kiocb *iocb, struct socket *sock, unsigned char *asmptr; int n, size, qbit = 0; + /* ROSE empty frame has no meaning : don't send */ + if (len == 0) + return 0; + if (msg->msg_flags & ~(MSG_DONTWAIT|MSG_EOR|MSG_CMSG_COMPAT)) return -EINVAL; @@ -1268,6 +1272,12 @@ static int rose_recvmsg(struct kiocb *iocb, struct socket *sock, skb_reset_transport_header(skb); copied = skb->len; + /* ROSE empty frame has no meaning : ignore it */ + if (copied == 0) { + skb_free_datagram(sk, skb); + return copied; + } + if (copied > size) { copied = size; msg->msg_flags |= MSG_TRUNC; -- 1.5.5