neigh: Add helper function neigh_xmit

For MPLS I am building the code so that either the neighbour mac
address can be specified or we can have a next hop in ipv4 or ipv6.

The kind of next hop we have is indicated by the neighbour table
pointer.  A neighbour table pointer of NULL is a link layer address.
A non-NULL neighbour table pointer indicates which neighbour table and
thus which address family the next hop address is in that we need to
look up.

The code either sends a packet directly or looks up the appropriate
neighbour table entry and sends the packet.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 34 insertions, 0 deletions

diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index fe3c6eac5805..cffaf00561e7 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -2391,6 +2391,40 @@ void __neigh_for_each_release(struct neigh_table *tbl,
 }
 EXPORT_SYMBOL(__neigh_for_each_release);
 
+int neigh_xmit(int family, struct net_device *dev,
+               const void *addr, struct sk_buff *skb)
+{
+        int err;
+        if (family == AF_PACKET) {
+                err = dev_hard_header(skb, dev, ntohs(skb->protocol),
+                                      addr, NULL, skb->len);
+                if (err < 0)
+                        goto out_kfree_skb;
+                err = dev_queue_xmit(skb);
+        } else {
+                struct neigh_table *tbl;
+                struct neighbour *neigh;
+
+                err = -ENETDOWN;
+                tbl = neigh_find_table(family);
+                if (!tbl)
+                        goto out;
+                neigh = __neigh_lookup_noref(tbl, addr, dev);
+                if (!neigh)
+                        neigh = __neigh_create(tbl, addr, dev, false);
+                err = PTR_ERR(neigh);
+                if (IS_ERR(neigh))
+                        goto out_kfree_skb;
+                err = neigh->output(neigh, skb);
+        }
+out:
+        return err;
+out_kfree_skb:
+        kfree_skb(skb);
+        goto out;
+}
+EXPORT_SYMBOL(neigh_xmit);
+
 #ifdef CONFIG_PROC_FS
 
 static struct neighbour *neigh_get_first(struct seq_file *seq)