8 files changed, 413 insertions, 311 deletions

diff --git a/Documentation/virtual/uml/UserModeLinux-HOWTO.txt b/Documentation/virtual/uml/UserModeLinux-HOWTO.txt
index 9b7e1904db1..5d0fc8bfcdb 100644
--- a/Documentation/virtual/uml/UserModeLinux-HOWTO.txt
+++ b/Documentation/virtual/uml/UserModeLinux-HOWTO.txt
@@ -1182,6 +1182,16 @@
   forge.net/>  and explains these in detail, as well as
   some other issues.
 
+  There is also a related point-to-point only "ucast" transport.
+  This is useful when your network does not support multicast, and
+  all network connections are simple point to point links.
+
+  The full set of command line options for this transport are
+
+
+       ethn=ucast,ethernet address,remote address,listen port,remote port
+
+
 
 
   66..66..  TTUUNN//TTAAPP wwiitthh tthhee uummll__nneett hheellppeerr
diff --git a/arch/um/drivers/Makefile b/arch/um/drivers/Makefile
index 1d9b6ae967b..e7582e1d248 100644
--- a/arch/um/drivers/Makefile
+++ b/arch/um/drivers/Makefile
@@ -9,7 +9,7 @@
 slip-objs := slip_kern.o slip_user.o
 slirp-objs := slirp_kern.o slirp_user.o
 daemon-objs := daemon_kern.o daemon_user.o
-mcast-objs := mcast_kern.o mcast_user.o
+umcast-objs := umcast_kern.o umcast_user.o
 net-objs := net_kern.o net_user.o
 mconsole-objs := mconsole_kern.o mconsole_user.o
 hostaudio-objs := hostaudio_kern.o
@@ -44,7 +44,7 @@ obj-$(CONFIG_UML_NET_SLIP) += slip.o slip_common.o
 obj-$(CONFIG_UML_NET_SLIRP) += slirp.o slip_common.o
 obj-$(CONFIG_UML_NET_DAEMON) += daemon.o 
 obj-$(CONFIG_UML_NET_VDE) += vde.o
-obj-$(CONFIG_UML_NET_MCAST) += mcast.o 
+obj-$(CONFIG_UML_NET_MCAST) += umcast.o
 obj-$(CONFIG_UML_NET_PCAP) += pcap.o
 obj-$(CONFIG_UML_NET) += net.o 
 obj-$(CONFIG_MCONSOLE) += mconsole.o
diff --git a/arch/um/drivers/mcast.h b/arch/um/drivers/mcast.h
deleted file mode 100644
index 6fa282e896b..00000000000
--- a/arch/um/drivers/mcast.h
+++ /dev/null
@@ -1,24 +0,0 @@
-/* 
- * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
- */
-
-#ifndef __DRIVERS_MCAST_H
-#define __DRIVERS_MCAST_H
-
-#include "net_user.h"
-
-struct mcast_data {
-	char *addr;
-	unsigned short port;
-	void *mcast_addr;
-	int ttl;
-	void *dev;
-};
-
-extern const struct net_user_info mcast_user_info;
-
-extern int mcast_user_write(int fd, void *buf, int len, 
-			    struct mcast_data *pri);
-
-#endif
diff --git a/arch/um/drivers/mcast_kern.c b/arch/um/drivers/mcast_kern.c
deleted file mode 100644
index ffc6416d5ed..00000000000
--- a/arch/um/drivers/mcast_kern.c
+++ /dev/null
@@ -1,120 +0,0 @@
-/*
- * user-mode-linux networking multicast transport
- * Copyright (C) 2001 by Harald Welte <laforge@gnumonks.org>
- * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- *
- * based on the existing uml-networking code, which is
- * Copyright (C) 2001 Lennert Buytenhek (buytenh@gnu.org) and
- * James Leu (jleu@mindspring.net).
- * Copyright (C) 2001 by various other people who didn't put their name here.
- *
- * Licensed under the GPL.
- */
-
-#include "linux/init.h"
-#include <linux/netdevice.h>
-#include "mcast.h"
-#include "net_kern.h"
-
-struct mcast_init {
-	char *addr;
-	int port;
-	int ttl;
-};
-
-static void mcast_init(struct net_device *dev, void *data)
-{
-	struct uml_net_private *pri;
-	struct mcast_data *dpri;
-	struct mcast_init *init = data;
-
-	pri = netdev_priv(dev);
-	dpri = (struct mcast_data *) pri->user;
-	dpri->addr = init->addr;
-	dpri->port = init->port;
-	dpri->ttl = init->ttl;
-	dpri->dev = dev;
-
-	printk("mcast backend multicast address: %s:%u, TTL:%u\n",
-	       dpri->addr, dpri->port, dpri->ttl);
-}
-
-static int mcast_read(int fd, struct sk_buff *skb, struct uml_net_private *lp)
-{
-	return net_recvfrom(fd, skb_mac_header(skb),
-			    skb->dev->mtu + ETH_HEADER_OTHER);
-}
-
-static int mcast_write(int fd, struct sk_buff *skb, struct uml_net_private *lp)
-{
-	return mcast_user_write(fd, skb->data, skb->len,
-				(struct mcast_data *) &lp->user);
-}
-
-static const struct net_kern_info mcast_kern_info = {
-	.init			= mcast_init,
-	.protocol		= eth_protocol,
-	.read			= mcast_read,
-	.write			= mcast_write,
-};
-
-static int mcast_setup(char *str, char **mac_out, void *data)
-{
-	struct mcast_init *init = data;
-	char *port_str = NULL, *ttl_str = NULL, *remain;
-	char *last;
-
-	*init = ((struct mcast_init)
-		{ .addr 	= "239.192.168.1",
-		  .port 	= 1102,
-		  .ttl 		= 1 });
-
-	remain = split_if_spec(str, mac_out, &init->addr, &port_str, &ttl_str,
-			       NULL);
-	if (remain != NULL) {
-		printk(KERN_ERR "mcast_setup - Extra garbage on "
-		       "specification : '%s'\n", remain);
-		return 0;
-	}
-
-	if (port_str != NULL) {
-		init->port = simple_strtoul(port_str, &last, 10);
-		if ((*last != '\0') || (last == port_str)) {
-			printk(KERN_ERR "mcast_setup - Bad port : '%s'\n",
-			       port_str);
-			return 0;
-		}
-	}
-
-	if (ttl_str != NULL) {
-		init->ttl = simple_strtoul(ttl_str, &last, 10);
-		if ((*last != '\0') || (last == ttl_str)) {
-			printk(KERN_ERR "mcast_setup - Bad ttl : '%s'\n",
-			       ttl_str);
-			return 0;
-		}
-	}
-
-	printk(KERN_INFO "Configured mcast device: %s:%u-%u\n", init->addr,
-	       init->port, init->ttl);
-
-	return 1;
-}
-
-static struct transport mcast_transport = {
-	.list 		= LIST_HEAD_INIT(mcast_transport.list),
-	.name 		= "mcast",
-	.setup  	= mcast_setup,
-	.user 		= &mcast_user_info,
-	.kern 		= &mcast_kern_info,
-	.private_size 	= sizeof(struct mcast_data),
-	.setup_size 	= sizeof(struct mcast_init),
-};
-
-static int register_mcast(void)
-{
-	register_transport(&mcast_transport);
-	return 0;
-}
-
-late_initcall(register_mcast);
diff --git a/arch/um/drivers/mcast_user.c b/arch/um/drivers/mcast_user.c
deleted file mode 100644
index ee19e91568a..00000000000
--- a/arch/um/drivers/mcast_user.c
+++ /dev/null
@@ -1,165 +0,0 @@
-/*
- * user-mode-linux networking multicast transport
- * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Copyright (C) 2001 by Harald Welte <laforge@gnumonks.org>
- *
- * based on the existing uml-networking code, which is
- * Copyright (C) 2001 Lennert Buytenhek (buytenh@gnu.org) and
- * James Leu (jleu@mindspring.net).
- * Copyright (C) 2001 by various other people who didn't put their name here.
- *
- * Licensed under the GPL.
- *
- */
-
-#include <unistd.h>
-#include <errno.h>
-#include <netinet/in.h>
-#include "kern_constants.h"
-#include "mcast.h"
-#include "net_user.h"
-#include "um_malloc.h"
-#include "user.h"
-
-static struct sockaddr_in *new_addr(char *addr, unsigned short port)
-{
-	struct sockaddr_in *sin;
-
-	sin = uml_kmalloc(sizeof(struct sockaddr_in), UM_GFP_KERNEL);
-	if (sin == NULL) {
-		printk(UM_KERN_ERR "new_addr: allocation of sockaddr_in "
-		       "failed\n");
-		return NULL;
-	}
-	sin->sin_family = AF_INET;
-	sin->sin_addr.s_addr = in_aton(addr);
-	sin->sin_port = htons(port);
-	return sin;
-}
-
-static int mcast_user_init(void *data, void *dev)
-{
-	struct mcast_data *pri = data;
-
-	pri->mcast_addr = new_addr(pri->addr, pri->port);
-	pri->dev = dev;
-	return 0;
-}
-
-static void mcast_remove(void *data)
-{
-	struct mcast_data *pri = data;
-
-	kfree(pri->mcast_addr);
-	pri->mcast_addr = NULL;
-}
-
-static int mcast_open(void *data)
-{
-	struct mcast_data *pri = data;
-	struct sockaddr_in *sin = pri->mcast_addr;
-	struct ip_mreq mreq;
-	int fd, yes = 1, err = -EINVAL;
-
-
-	if ((sin->sin_addr.s_addr == 0) || (sin->sin_port == 0))
-		goto out;
-
-	fd = socket(AF_INET, SOCK_DGRAM, 0);
-
-	if (fd < 0) {
-		err = -errno;
-		printk(UM_KERN_ERR "mcast_open : data socket failed, "
-		       "errno = %d\n", errno);
-		goto out;
-	}
-
-	if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(yes)) < 0) {
-		err = -errno;
-		printk(UM_KERN_ERR "mcast_open: SO_REUSEADDR failed, "
-		       "errno = %d\n", errno);
-		goto out_close;
-	}
-
-	/* set ttl according to config */
-	if (setsockopt(fd, SOL_IP, IP_MULTICAST_TTL, &pri->ttl,
-		       sizeof(pri->ttl)) < 0) {
-		err = -errno;
-		printk(UM_KERN_ERR "mcast_open: IP_MULTICAST_TTL failed, "
-		       "error = %d\n", errno);
-		goto out_close;
-	}
-
-	/* set LOOP, so data does get fed back to local sockets */
-	if (setsockopt(fd, SOL_IP, IP_MULTICAST_LOOP, &yes, sizeof(yes)) < 0) {
-		err = -errno;
-		printk(UM_KERN_ERR "mcast_open: IP_MULTICAST_LOOP failed, "
-		       "error = %d\n", errno);
-		goto out_close;
-	}
-
-	/* bind socket to mcast address */
-	if (bind(fd, (struct sockaddr *) sin, sizeof(*sin)) < 0) {
-		err = -errno;
-		printk(UM_KERN_ERR "mcast_open : data bind failed, "
-		       "errno = %d\n", errno);
-		goto out_close;
-	}
-
-	/* subscribe to the multicast group */
-	mreq.imr_multiaddr.s_addr = sin->sin_addr.s_addr;
-	mreq.imr_interface.s_addr = 0;
-	if (setsockopt(fd, SOL_IP, IP_ADD_MEMBERSHIP,
-		       &mreq, sizeof(mreq)) < 0) {
-		err = -errno;
-		printk(UM_KERN_ERR "mcast_open: IP_ADD_MEMBERSHIP failed, "
-		       "error = %d\n", errno);
-		printk(UM_KERN_ERR "There appears not to be a multicast-"
-		       "capable network interface on the host.\n");
-		printk(UM_KERN_ERR "eth0 should be configured in order to use "
-		       "the multicast transport.\n");
-		goto out_close;
-	}
-
-	return fd;
-
- out_close:
-	close(fd);
- out:
-	return err;
-}
-
-static void mcast_close(int fd, void *data)
-{
-	struct ip_mreq mreq;
-	struct mcast_data *pri = data;
-	struct sockaddr_in *sin = pri->mcast_addr;
-
-	mreq.imr_multiaddr.s_addr = sin->sin_addr.s_addr;
-	mreq.imr_interface.s_addr = 0;
-	if (setsockopt(fd, SOL_IP, IP_DROP_MEMBERSHIP,
-		       &mreq, sizeof(mreq)) < 0) {
-		printk(UM_KERN_ERR "mcast_open: IP_DROP_MEMBERSHIP failed, "
-		       "error = %d\n", errno);
-	}
-
-	close(fd);
-}
-
-int mcast_user_write(int fd, void *buf, int len, struct mcast_data *pri)
-{
-	struct sockaddr_in *data_addr = pri->mcast_addr;
-
-	return net_sendto(fd, buf, len, data_addr, sizeof(*data_addr));
-}
-
-const struct net_user_info mcast_user_info = {
-	.init		= mcast_user_init,
-	.open		= mcast_open,
-	.close	 	= mcast_close,
-	.remove	 	= mcast_remove,
-	.add_address	= NULL,
-	.delete_address = NULL,
-	.mtu		= ETH_MAX_PACKET,
-	.max_packet	= ETH_MAX_PACKET + ETH_HEADER_OTHER,
-};
diff --git a/arch/um/drivers/umcast.h b/arch/um/drivers/umcast.h
new file mode 100644
index 00000000000..6f8c0fe890f
--- /dev/null
+++ b/arch/um/drivers/umcast.h
@@ -0,0 +1,27 @@
+/*
+ * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ * Licensed under the GPL
+ */
+
+#ifndef __DRIVERS_UMCAST_H
+#define __DRIVERS_UMCAST_H
+
+#include "net_user.h"
+
+struct umcast_data {
+	char *addr;
+	unsigned short lport;
+	unsigned short rport;
+	void *listen_addr;
+	void *remote_addr;
+	int ttl;
+	int unicast;
+	void *dev;
+};
+
+extern const struct net_user_info umcast_user_info;
+
+extern int umcast_user_write(int fd, void *buf, int len,
+			     struct umcast_data *pri);
+
+#endif
diff --git a/arch/um/drivers/umcast_kern.c b/arch/um/drivers/umcast_kern.c
new file mode 100644
index 00000000000..42dab11d2ec
--- /dev/null
+++ b/arch/um/drivers/umcast_kern.c
@@ -0,0 +1,188 @@
+/*
+ * user-mode-linux networking multicast transport
+ * Copyright (C) 2001 by Harald Welte <laforge@gnumonks.org>
+ * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ *
+ * based on the existing uml-networking code, which is
+ * Copyright (C) 2001 Lennert Buytenhek (buytenh@gnu.org) and
+ * James Leu (jleu@mindspring.net).
+ * Copyright (C) 2001 by various other people who didn't put their name here.
+ *
+ * Licensed under the GPL.
+ */
+
+#include "linux/init.h"
+#include <linux/netdevice.h>
+#include "umcast.h"
+#include "net_kern.h"
+
+struct umcast_init {
+	char *addr;
+	int lport;
+	int rport;
+	int ttl;
+	bool unicast;
+};
+
+static void umcast_init(struct net_device *dev, void *data)
+{
+	struct uml_net_private *pri;
+	struct umcast_data *dpri;
+	struct umcast_init *init = data;
+
+	pri = netdev_priv(dev);
+	dpri = (struct umcast_data *) pri->user;
+	dpri->addr = init->addr;
+	dpri->lport = init->lport;
+	dpri->rport = init->rport;
+	dpri->unicast = init->unicast;
+	dpri->ttl = init->ttl;
+	dpri->dev = dev;
+
+	if (dpri->unicast) {
+		printk(KERN_INFO "ucast backend address: %s:%u listen port: "
+		       "%u\n", dpri->addr, dpri->rport, dpri->lport);
+	} else {
+		printk(KERN_INFO "mcast backend multicast address: %s:%u, "
+		       "TTL:%u\n", dpri->addr, dpri->lport, dpri->ttl);
+	}
+}
+
+static int umcast_read(int fd, struct sk_buff *skb, struct uml_net_private *lp)
+{
+	return net_recvfrom(fd, skb_mac_header(skb),
+			    skb->dev->mtu + ETH_HEADER_OTHER);
+}
+
+static int umcast_write(int fd, struct sk_buff *skb, struct uml_net_private *lp)
+{
+	return umcast_user_write(fd, skb->data, skb->len,
+				(struct umcast_data *) &lp->user);
+}
+
+static const struct net_kern_info umcast_kern_info = {
+	.init			= umcast_init,
+	.protocol		= eth_protocol,
+	.read			= umcast_read,
+	.write			= umcast_write,
+};
+
+static int mcast_setup(char *str, char **mac_out, void *data)
+{
+	struct umcast_init *init = data;
+	char *port_str = NULL, *ttl_str = NULL, *remain;
+	char *last;
+
+	*init = ((struct umcast_init)
+		{ .addr	= "239.192.168.1",
+		  .lport	= 1102,
+		  .ttl	= 1 });
+
+	remain = split_if_spec(str, mac_out, &init->addr, &port_str, &ttl_str,
+			       NULL);
+	if (remain != NULL) {
+		printk(KERN_ERR "mcast_setup - Extra garbage on "
+		       "specification : '%s'\n", remain);
+		return 0;
+	}
+
+	if (port_str != NULL) {
+		init->lport = simple_strtoul(port_str, &last, 10);
+		if ((*last != '\0') || (last == port_str)) {
+			printk(KERN_ERR "mcast_setup - Bad port : '%s'\n",
+			       port_str);
+			return 0;
+		}
+	}
+
+	if (ttl_str != NULL) {
+		init->ttl = simple_strtoul(ttl_str, &last, 10);
+		if ((*last != '\0') || (last == ttl_str)) {
+			printk(KERN_ERR "mcast_setup - Bad ttl : '%s'\n",
+			       ttl_str);
+			return 0;
+		}
+	}
+
+	init->unicast = false;
+	init->rport = init->lport;
+
+	printk(KERN_INFO "Configured mcast device: %s:%u-%u\n", init->addr,
+	       init->lport, init->ttl);
+
+	return 1;
+}
+
+static int ucast_setup(char *str, char **mac_out, void *data)
+{
+	struct umcast_init *init = data;
+	char *lport_str = NULL, *rport_str = NULL, *remain;
+	char *last;
+
+	*init = ((struct umcast_init)
+		{ .addr		= "",
+		  .lport	= 1102,
+		  .rport	= 1102 });
+
+	remain = split_if_spec(str, mac_out, &init->addr,
+			       &lport_str, &rport_str, NULL);
+	if (remain != NULL) {
+		printk(KERN_ERR "ucast_setup - Extra garbage on "
+		       "specification : '%s'\n", remain);
+		return 0;
+	}
+
+	if (lport_str != NULL) {
+		init->lport = simple_strtoul(lport_str, &last, 10);
+		if ((*last != '\0') || (last == lport_str)) {
+			printk(KERN_ERR "ucast_setup - Bad listen port : "
+			       "'%s'\n", lport_str);
+			return 0;
+		}
+	}
+
+	if (rport_str != NULL) {
+		init->rport = simple_strtoul(rport_str, &last, 10);
+		if ((*last != '\0') || (last == rport_str)) {
+			printk(KERN_ERR "ucast_setup - Bad remote port : "
+			       "'%s'\n", rport_str);
+			return 0;
+		}
+	}
+
+	init->unicast = true;
+
+	printk(KERN_INFO "Configured ucast device: :%u -> %s:%u\n",
+	       init->lport, init->addr, init->rport);
+
+	return 1;
+}
+
+static struct transport mcast_transport = {
+	.list	= LIST_HEAD_INIT(mcast_transport.list),
+	.name	= "mcast",
+	.setup	= mcast_setup,
+	.user	= &umcast_user_info,
+	.kern	= &umcast_kern_info,
+	.private_size	= sizeof(struct umcast_data),
+	.setup_size	= sizeof(struct umcast_init),
+};
+
+static struct transport ucast_transport = {
+	.list	= LIST_HEAD_INIT(ucast_transport.list),
+	.name	= "ucast",
+	.setup	= ucast_setup,
+	.user	= &umcast_user_info,
+	.kern	= &umcast_kern_info,
+	.private_size	= sizeof(struct umcast_data),
+	.setup_size	= sizeof(struct umcast_init),
+};
+
+static int register_umcast(void)
+{
+	register_transport(&mcast_transport);
+	register_transport(&ucast_transport);
+	return 0;
+}
+
+late_initcall(register_umcast);
diff --git a/arch/um/drivers/umcast_user.c b/arch/um/drivers/umcast_user.c
new file mode 100644
index 00000000000..59c56fd6f52
--- /dev/null
+++ b/arch/um/drivers/umcast_user.c
@@ -0,0 +1,186 @@
+/*
+ * user-mode-linux networking multicast transport
+ * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ * Copyright (C) 2001 by Harald Welte <laforge@gnumonks.org>
+ *
+ * based on the existing uml-networking code, which is
+ * Copyright (C) 2001 Lennert Buytenhek (buytenh@gnu.org) and
+ * James Leu (jleu@mindspring.net).
+ * Copyright (C) 2001 by various other people who didn't put their name here.
+ *
+ * Licensed under the GPL.
+ *
+ */
+
+#include <unistd.h>
+#include <errno.h>
+#include <netinet/in.h>
+#include "kern_constants.h"
+#include "umcast.h"
+#include "net_user.h"
+#include "um_malloc.h"
+#include "user.h"
+
+static struct sockaddr_in *new_addr(char *addr, unsigned short port)
+{
+	struct sockaddr_in *sin;
+
+	sin = uml_kmalloc(sizeof(struct sockaddr_in), UM_GFP_KERNEL);
+	if (sin == NULL) {
+		printk(UM_KERN_ERR "new_addr: allocation of sockaddr_in "
+		       "failed\n");
+		return NULL;
+	}
+	sin->sin_family = AF_INET;
+	if (addr)
+		sin->sin_addr.s_addr = in_aton(addr);
+	else
+		sin->sin_addr.s_addr = INADDR_ANY;
+	sin->sin_port = htons(port);
+	return sin;
+}
+
+static int umcast_user_init(void *data, void *dev)
+{
+	struct umcast_data *pri = data;
+
+	pri->remote_addr = new_addr(pri->addr, pri->rport);
+	if (pri->unicast)
+		pri->listen_addr = new_addr(NULL, pri->lport);
+	else
+		pri->listen_addr = pri->remote_addr;
+	pri->dev = dev;
+	return 0;
+}
+
+static void umcast_remove(void *data)
+{
+	struct umcast_data *pri = data;
+
+	kfree(pri->listen_addr);
+	if (pri->unicast)
+		kfree(pri->remote_addr);
+	pri->listen_addr = pri->remote_addr = NULL;
+}
+
+static int umcast_open(void *data)
+{
+	struct umcast_data *pri = data;
+	struct sockaddr_in *lsin = pri->listen_addr;
+	struct sockaddr_in *rsin = pri->remote_addr;
+	struct ip_mreq mreq;
+	int fd, yes = 1, err = -EINVAL;
+
+
+	if ((!pri->unicast && lsin->sin_addr.s_addr == 0) ||
+	    (rsin->sin_addr.s_addr == 0) ||
+	    (lsin->sin_port == 0) || (rsin->sin_port == 0))
+		goto out;
+
+	fd = socket(AF_INET, SOCK_DGRAM, 0);
+
+	if (fd < 0) {
+		err = -errno;
+		printk(UM_KERN_ERR "umcast_open : data socket failed, "
+		       "errno = %d\n", errno);
+		goto out;
+	}
+
+	if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(yes)) < 0) {
+		err = -errno;
+		printk(UM_KERN_ERR "umcast_open: SO_REUSEADDR failed, "
+		       "errno = %d\n", errno);
+		goto out_close;
+	}
+
+	if (!pri->unicast) {
+		/* set ttl according to config */
+		if (setsockopt(fd, SOL_IP, IP_MULTICAST_TTL, &pri->ttl,
+			       sizeof(pri->ttl)) < 0) {
+			err = -errno;
+			printk(UM_KERN_ERR "umcast_open: IP_MULTICAST_TTL "
+			       "failed, error = %d\n", errno);
+			goto out_close;
+		}
+
+		/* set LOOP, so data does get fed back to local sockets */
+		if (setsockopt(fd, SOL_IP, IP_MULTICAST_LOOP,
+			       &yes, sizeof(yes)) < 0) {
+			err = -errno;
+			printk(UM_KERN_ERR "umcast_open: IP_MULTICAST_LOOP "
+			       "failed, error = %d\n", errno);
+			goto out_close;
+		}
+	}
+
+	/* bind socket to the address */
+	if (bind(fd, (struct sockaddr *) lsin, sizeof(*lsin)) < 0) {
+		err = -errno;
+		printk(UM_KERN_ERR "umcast_open : data bind failed, "
+		       "errno = %d\n", errno);
+		goto out_close;
+	}
+
+	if (!pri->unicast) {
+		/* subscribe to the multicast group */
+		mreq.imr_multiaddr.s_addr = lsin->sin_addr.s_addr;
+		mreq.imr_interface.s_addr = 0;
+		if (setsockopt(fd, SOL_IP, IP_ADD_MEMBERSHIP,
+			       &mreq, sizeof(mreq)) < 0) {
+			err = -errno;
+			printk(UM_KERN_ERR "umcast_open: IP_ADD_MEMBERSHIP "
+			       "failed, error = %d\n", errno);
+			printk(UM_KERN_ERR "There appears not to be a "
+			       "multicast-capable network interface on the "
+			       "host.\n");
+			printk(UM_KERN_ERR "eth0 should be configured in order "
+			       "to use the multicast transport.\n");
+			goto out_close;
+		}
+	}
+
+	return fd;
+
+ out_close:
+	close(fd);
+ out:
+	return err;
+}
+
+static void umcast_close(int fd, void *data)
+{
+	struct umcast_data *pri = data;
+
+	if (!pri->unicast) {
+		struct ip_mreq mreq;
+		struct sockaddr_in *lsin = pri->listen_addr;
+
+		mreq.imr_multiaddr.s_addr = lsin->sin_addr.s_addr;
+		mreq.imr_interface.s_addr = 0;
+		if (setsockopt(fd, SOL_IP, IP_DROP_MEMBERSHIP,
+			       &mreq, sizeof(mreq)) < 0) {
+			printk(UM_KERN_ERR "umcast_close: IP_DROP_MEMBERSHIP "
+			       "failed, error = %d\n", errno);
+		}
+	}
+
+	close(fd);
+}
+
+int umcast_user_write(int fd, void *buf, int len, struct umcast_data *pri)
+{
+	struct sockaddr_in *data_addr = pri->remote_addr;
+
+	return net_sendto(fd, buf, len, data_addr, sizeof(*data_addr));
+}
+
+const struct net_user_info umcast_user_info = {
+	.init	= umcast_user_init,
+	.open	= umcast_open,
+	.close	= umcast_close,
+	.remove	= umcast_remove,
+	.add_address	= NULL,
+	.delete_address = NULL,
+	.mtu	= ETH_MAX_PACKET,
+	.max_packet	= ETH_MAX_PACKET + ETH_HEADER_OTHER,
+};