sctp: Implement socket option SCTP_GET_ASSOC_NUMBER

Implement socket option SCTP_GET_ASSOC_NUMBER of the latest ietf socket
extensions API draft.

  8.2.5.  Get the Current Number of Associations (SCTP_GET_ASSOC_NUMBER)

   This option gets the current number of associations that are attached
   to a one-to-many style socket.  The option value is an uint32_t.

Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 37 insertions, 0 deletions

diff --git a/include/net/sctp/user.h b/include/net/sctp/user.h
index f205b10f0ab9..b259fc5798fb 100644
--- a/include/net/sctp/user.h
+++ b/include/net/sctp/user.h
@@ -118,6 +118,8 @@ enum sctp_optname {
 #define SCTP_PEER_AUTH_CHUNKS SCTP_PEER_AUTH_CHUNKS
         SCTP_LOCAL_AUTH_CHUNKS,         /* Read only */
 #define SCTP_LOCAL_AUTH_CHUNKS SCTP_LOCAL_AUTH_CHUNKS
+        SCTP_GET_ASSOC_NUMBER,          /* Read only */
+#define SCTP_GET_ASSOC_NUMBER SCTP_GET_ASSOC_NUMBER
 
 
         /* Internal Socket Options. Some of the sctp library functions are 
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index e432927310c9..9f5fe23773a9 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -5460,6 +5460,38 @@ num:
         return 0;
 }
 
+/*
+ * 8.2.5.  Get the Current Number of Associations (SCTP_GET_ASSOC_NUMBER)
+ * This option gets the current number of associations that are attached
+ * to a one-to-many style socket.  The option value is an uint32_t.
+ */
+static int sctp_getsockopt_assoc_number(struct sock *sk, int len,
+                                    char __user *optval, int __user *optlen)
+{
+        struct sctp_sock *sp = sctp_sk(sk);
+        struct sctp_association *asoc;
+        u32 val = 0;
+
+        if (sctp_style(sk, TCP))
+                return -EOPNOTSUPP;
+
+        if (len < sizeof(u32))
+                return -EINVAL;
+
+        len = sizeof(u32);
+
+        list_for_each_entry(asoc, &(sp->ep->asocs), asocs) {
+                val++;
+        }
+
+        if (put_user(len, optlen))
+                return -EFAULT;
+        if (copy_to_user(optval, &val, len))
+                return -EFAULT;
+
+        return 0;
+}
+
 SCTP_STATIC int sctp_getsockopt(struct sock *sk, int level, int optname,
                                 char __user *optval, int __user *optlen)
 {
@@ -5602,6 +5634,9 @@ SCTP_STATIC int sctp_getsockopt(struct sock *sk, int level, int optname,
                 retval = sctp_getsockopt_local_auth_chunks(sk, len, optval,
                                                         optlen);
                 break;
+        case SCTP_GET_ASSOC_NUMBER:
+                retval = sctp_getsockopt_assoc_number(sk, len, optval, optlen);
+                break;
         default:
                 retval = -ENOPROTOOPT;
                 break;