This feature is actually already supported by sk->sk_reuse which can be
set by SO_REUSEADDR. But it's not working exactly as RFC6458 demands in
section 8.1.27, like:
- This option only supports one-to-one style SCTP sockets
- This socket option must not be used after calling bind()
or sctp_bindx().
Besides, SCTP_REUSE_PORT sockopt should be provided for user's programs.
Otherwise, the programs with SCTP_REUSE_PORT from other systems will not
work in linux.
This patch reuses sk->sk_reuse and works pretty much as SO_REUSEADDR,
just with some extra setup limitations that are neeeded when it is being
enabled.
"It should be noted that the behavior of the socket-level socket option
to reuse ports and/or addresses for SCTP sockets is unspecified", so it
leaves SO_REUSEADDR as is for the compatibility.
Signed-off-by: Xin Long <lucien.xin@xxxxxxxxx>
---
include/uapi/linux/sctp.h | 1 +
net/sctp/socket.c | 48 +++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 49 insertions(+)
diff --git a/include/uapi/linux/sctp.h b/include/uapi/linux/sctp.h
index b64d583..c02986a 100644
--- a/include/uapi/linux/sctp.h
+++ b/include/uapi/linux/sctp.h
@@ -100,6 +100,7 @@ typedef __s32 sctp_assoc_t;
#define SCTP_RECVNXTINFO 33
#define SCTP_DEFAULT_SNDINFO 34
#define SCTP_AUTH_DEACTIVATE_KEY 35
+#define SCTP_REUSE_PORT 36
/* Internal Socket Options. Some of the sctp library functions are
* implemented using these socket options.
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 1b4593b..8dfcc79 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -4170,6 +4170,28 @@ static int sctp_setsockopt_interleaving_supported(struct sock *sk,
return retval;
}
+static int sctp_setsockopt_reuse_port(struct sock *sk, char __user *optval,
+ unsigned int optlen)
+{
+ int val;
+
+ if (!sctp_style(sk, TCP))
+ return -EOPNOTSUPP;
+
+ if (sctp_sk(sk)->ep->base.bind_addr.port)
+ return -EFAULT;
+
+ if (optlen < sizeof(int))
+ return -EINVAL;
+
+ if (get_user(val, (int __user *)optval))
+ return -EFAULT;
+
+ sk->sk_reuse = val ? SK_CAN_REUSE : SK_NO_REUSE;
+
+ return 0;
+}
+
/* API 6.2 setsockopt(), getsockopt()
*
* Applications use setsockopt() and getsockopt() to set or retrieve
@@ -4364,6 +4386,9 @@ static int sctp_setsockopt(struct sock *sk, int level, int optname,
retval = sctp_setsockopt_interleaving_supported(sk, optval,
optlen);
break;
+ case SCTP_REUSE_PORT:
+ retval = sctp_setsockopt_reuse_port(sk, optval, optlen);
+ break;
default:
retval = -ENOPROTOOPT;
break;
@@ -7175,6 +7200,26 @@ static int sctp_getsockopt_interleaving_supported(struct sock *sk, int len,
return retval;
}
+static int sctp_getsockopt_reuse_port(struct sock *sk, int len,
+ char __user *optval,
+ int __user *optlen)
+{
+ int val = 0;
+
+ if (len < sizeof(int))
+ return -EINVAL;
+
+ len = sizeof(int);
+ if (sk->sk_reuse != SK_NO_REUSE)
+ val = 1;
+ if (put_user(len, optlen))
+ return -EFAULT;
+ if (copy_to_user(optval, &val, len))
+ return -EFAULT;
+
+ return 0;
+}
+
static int sctp_getsockopt(struct sock *sk, int level, int optname,
char __user *optval, int __user *optlen)
{
@@ -7370,6 +7415,9 @@ static int sctp_getsockopt(struct sock *sk, int level, int optname,
retval = sctp_getsockopt_interleaving_supported(sk, len, optval,
optlen);
break;
+ case SCTP_REUSE_PORT:
+ retval = sctp_getsockopt_reuse_port(sk, len, optval, optlen);
+ break;
default:
retval = -ENOPROTOOPT;
break;
--
2.1.0
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