From c6b607b6e100fc98c1c009be7d94a2e251bc606e Mon Sep 17 00:00:00 2001
From: Michal Sojka <sojkam1@fel.cvut.cz>
Date: Thu, 20 Dec 2012 16:12:50 +0100
Subject: [PATCH] Add type field to UDP datagrams

This will allow future extensions
---
 net/can/canethgw.c | 37 ++++++++++++++++++++++++++-----------
 1 file changed, 26 insertions(+), 11 deletions(-)

diff --git a/net/can/canethgw.c b/net/can/canethgw.c
index 6dda6f36dcdd..635383de66e8 100644
--- a/net/can/canethgw.c
+++ b/net/can/canethgw.c
@@ -24,6 +24,10 @@
 
 MODULE_LICENSE("GPL");
 
+enum msg_types {
+	CAN_FRAME,
+};
+
 struct cegw_job
 {
 	struct kref refcount;
@@ -45,8 +49,9 @@ static void cegw_job_release(struct kref *ref);
 static int cegw_udp_send(struct socket *udp_sock, struct can_frame *cf, struct sockaddr_in* addr)
 {
 	struct msghdr mh;
-	struct kvec vec;
+	struct kvec vec[2];
 	int err;
+	__u16 type = CAN_FRAME;
 
 	mh.msg_name = addr;
 	mh.msg_namelen = sizeof(*addr);
@@ -54,10 +59,12 @@ static int cegw_udp_send(struct socket *udp_sock, struct can_frame *cf, struct s
 	mh.msg_controllen = 0;
 	mh.msg_flags = 0;
 
-	vec.iov_base = cf;
-	vec.iov_len = sizeof(*cf);
+	type = cpu_to_be16(type);
+	vec[0].iov_base = &type;
+	vec[1].iov_base = cf;
+	vec[1].iov_len = sizeof(*cf);
 
-	err = kernel_sendmsg(udp_sock, &mh, &vec, 1, sizeof(*cf));
+	err = kernel_sendmsg(udp_sock, &mh, vec, 2, sizeof(*cf));
 
 	return err;
 }
@@ -90,26 +97,34 @@ static int cegw_can_send(struct socket* can_sock, struct can_frame* cf)
 static int cegw_udp2can(void *data)
 {
 	struct can_frame cf;
-	struct kvec vec;
+	struct kvec vec[2];
 	struct msghdr mh;
 	struct cegw_job *job = (struct cegw_job *)data;
 	struct socket *udp_sock = NULL, *can_sock = NULL;
 	int ret = 0;
+	__u16 type;
 
 	memset(&mh, 0, sizeof(mh));
 	udp_sock = job->udp_sock;
 	can_sock = job->can_sock;
 
 	while (1) {
-		vec.iov_base = &cf;
-		vec.iov_len = sizeof(cf);
-		ret = kernel_recvmsg(udp_sock, &mh, &vec, 1,
+		vec[0].iov_base = &type;
+		vec[0].iov_len = sizeof(type);
+		vec[1].iov_base = &cf;
+		vec[1].iov_len = sizeof(cf);
+		ret = kernel_recvmsg(udp_sock, &mh, vec, 2,
 				     sizeof(cf), 0);
-		if (ret < 1)
+		if (ret != sizeof(type) + sizeof(cf))
 			break;
 
-		cf.can_id = be32_to_cpu(cf.can_id);
-		cegw_can_send(can_sock, &cf);
+		type = be16_to_cpu(type);
+		switch (type) {
+		case CAN_FRAME:
+			cf.can_id = be32_to_cpu(cf.can_id);
+			cegw_can_send(can_sock, &cf);
+		default:;
+		}
 	}
 
 	cegw_thread_stop(job);
-- 
2.39.2