[LLC]: add multicast support for datagrams

Allow mulitcast reception of datagrams (similar to UDP).
All sockets bound to the same SAP receive a clone.

Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 51 insertions, 8 deletions

diff --git a/net/llc/llc_sap.c b/net/llc/llc_sap.c
index 4029ceee9b91..20c4eb5c1ac6 100644
--- a/net/llc/llc_sap.c
+++ b/net/llc/llc_sap.c
@@ -282,7 +282,7 @@ static void llc_sap_rcv(struct llc_sap *sap, struct sk_buff *skb)
  *      mac, and local sap. Returns pointer for socket found, %NULL otherwise.
  */
 static struct sock *llc_lookup_dgram(struct llc_sap *sap,
-                                     struct llc_addr *laddr)
+                                     const struct llc_addr *laddr)
 {
         struct sock *rc;
         struct hlist_node *node;
@@ -304,19 +304,62 @@ found:
         return rc;
 }
 
+/**
+ *      llc_sap_mcast - Deliver multicast PDU's to all matching datagram sockets.
+ *      @sap: SAP
+ *      @laddr: address of local LLC (MAC + SAP)
+ *
+ *      Search socket list of the SAP and finds connections with same sap.
+ *      Deliver clone to each.
+ */
+static void llc_sap_mcast(struct llc_sap *sap,
+                          const struct llc_addr *laddr,
+                          struct sk_buff *skb)
+{
+        struct sock *sk;
+        struct hlist_node *node;
+
+        read_lock_bh(&sap->sk_list.lock);
+        sk_for_each(sk, node, &sap->sk_list.list) {
+                struct llc_sock *llc = llc_sk(sk);
+                struct sk_buff *skb1;
+
+                if (sk->sk_type != SOCK_DGRAM)
+                        continue;
+
+                if (llc->laddr.lsap != laddr->lsap)
+                        continue;
+
+                skb1 = skb_clone(skb, GFP_ATOMIC);
+                if (!skb1)
+                        break;
+
+                sock_hold(sk);
+                skb_set_owner_r(skb1, sk);
+                llc_sap_rcv(sap, skb1);
+                sock_put(sk);
+        }
+        read_unlock_bh(&sap->sk_list.lock);
+}
+
+
 void llc_sap_handler(struct llc_sap *sap, struct sk_buff *skb)
 {
         struct llc_addr laddr;
-        struct sock *sk;
 
         llc_pdu_decode_da(skb, laddr.mac);
         llc_pdu_decode_dsap(skb, &laddr.lsap);
 
-        sk = llc_lookup_dgram(sap, &laddr);
-        if (sk) {
-                skb_set_owner_r(skb, sk);
-                llc_sap_rcv(sap, skb);
-                sock_put(sk);
-        } else
+        if (llc_mac_multicast(laddr.mac)) {
+                llc_sap_mcast(sap, &laddr, skb);
                 kfree_skb(skb);
+        } else {
+                struct sock *sk = llc_lookup_dgram(sap, &laddr);
+                if (sk) {
+                        skb_set_owner_r(skb, sk);
+                        llc_sap_rcv(sap, skb);
+                        sock_put(sk);
+                } else
+                        kfree_skb(skb);
+        }
 }