sctp: add sockopt SCTP_EVENT

This patch adds sockopt SCTP_EVENT described in rfc6525#section-6.2.
With this sockopt users can subscribe to an event from a specified
asoc.
Signed-off-by: NXin Long <lucien.xin@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/uapi/linux/sctp.h

@@ -129,6 +129,7 @@ typedef __s32 sctp_assoc_t;
 #define SCTP_STREAM_SCHEDULER_VALUE	124
 #define SCTP_INTERLEAVING_SUPPORTED	125
 #define SCTP_SENDMSG_CONNECT	126
+#define SCTP_EVENT	127
 
 /* PR-SCTP policies */
 #define SCTP_PR_SCTP_NONE	0x0000
@@ -1154,6 +1155,12 @@ struct sctp_add_streams {
 	uint16_t sas_outstrms;
 };
 
+struct sctp_event {
+	sctp_assoc_t se_assoc_id;
+	uint16_t se_type;
+	uint8_t se_on;
+};
+
 /* SCTP Stream schedulers */
 enum sctp_sched_type {
 	SCTP_SS_FCFS,

net/sctp/socket.c

@@ -4288,6 +4288,57 @@ static int sctp_setsockopt_reuse_port(struct sock *sk, char __user *optval,
 	return 0;
 }
 
+static int sctp_setsockopt_event(struct sock *sk, char __user *optval,
+				 unsigned int optlen)
+{
+	struct sctp_association *asoc;
+	struct sctp_ulpevent *event;
+	struct sctp_event param;
+	int retval = 0;
+
+	if (optlen < sizeof(param)) {
+		retval = -EINVAL;
+		goto out;
+	}
+
+	optlen = sizeof(param);
+	if (copy_from_user(&param, optval, optlen)) {
+		retval = -EFAULT;
+		goto out;
+	}
+
+	if (param.se_type < SCTP_SN_TYPE_BASE ||
+	    param.se_type > SCTP_SN_TYPE_MAX) {
+		retval = -EINVAL;
+		goto out;
+	}
+
+	asoc = sctp_id2assoc(sk, param.se_assoc_id);
+	if (!asoc) {
+		sctp_ulpevent_type_set(&sctp_sk(sk)->subscribe,
+				       param.se_type, param.se_on);
+		goto out;
+	}
+
+	sctp_ulpevent_type_set(&asoc->subscribe, param.se_type, param.se_on);
+
+	if (param.se_type == SCTP_SENDER_DRY_EVENT && param.se_on) {
+		if (sctp_outq_is_empty(&asoc->outqueue)) {
+			event = sctp_ulpevent_make_sender_dry_event(asoc,
+					GFP_USER | __GFP_NOWARN);
+			if (!event) {
+				retval = -ENOMEM;
+				goto out;
+			}
+
+			asoc->stream.si->enqueue_event(&asoc->ulpq, event);
+		}
+	}
+
+out:
+	return retval;
+}
+
 /* API 6.2 setsockopt(), getsockopt()
  *
  * Applications use setsockopt() and getsockopt() to set or retrieve
@@ -4485,6 +4536,9 @@ static int sctp_setsockopt(struct sock *sk, int level, int optname,
 	case SCTP_REUSE_PORT:
 		retval = sctp_setsockopt_reuse_port(sk, optval, optlen);
 		break;
+	case SCTP_EVENT:
+		retval = sctp_setsockopt_event(sk, optval, optlen);
+		break;
 	default:
 		retval = -ENOPROTOOPT;
 		break;
@@ -7430,6 +7484,37 @@ static int sctp_getsockopt_reuse_port(struct sock *sk, int len,
 	return 0;
 }
 
+static int sctp_getsockopt_event(struct sock *sk, int len, char __user *optval,
+				 int __user *optlen)
+{
+	struct sctp_association *asoc;
+	struct sctp_event param;
+	__u16 subscribe;
+
+	if (len < sizeof(param))
+		return -EINVAL;
+
+	len = sizeof(param);
+	if (copy_from_user(&param, optval, len))
+		return -EFAULT;
+
+	if (param.se_type < SCTP_SN_TYPE_BASE ||
+	    param.se_type > SCTP_SN_TYPE_MAX)
+		return -EINVAL;
+
+	asoc = sctp_id2assoc(sk, param.se_assoc_id);
+	subscribe = asoc ? asoc->subscribe : sctp_sk(sk)->subscribe;
+	param.se_on = sctp_ulpevent_type_enabled(subscribe, param.se_type);
+
+	if (put_user(len, optlen))
+		return -EFAULT;
+
+	if (copy_to_user(optval, &param, len))
+		return -EFAULT;
+
+	return 0;
+}
+
 static int sctp_getsockopt(struct sock *sk, int level, int optname,
 			   char __user *optval, int __user *optlen)
 {
@@ -7628,6 +7713,9 @@ static int sctp_getsockopt(struct sock *sk, int level, int optname,
 	case SCTP_REUSE_PORT:
 		retval = sctp_getsockopt_reuse_port(sk, len, optval, optlen);
 		break;
+	case SCTP_EVENT:
+		retval = sctp_getsockopt_event(sk, len, optval, optlen);
+		break;
 	default:
 		retval = -ENOPROTOOPT;
 		break;