[RFC PATCH] [SCTP]: Support the new specification of sctp_connectx()

[RFC PATCH] [SCTP]: Support the new specification of sctp_connectx()

[Vlad Yasevich]

Hi All

Here is an update to the connectx() implementation the way
Ivan proposed.

The hard part to figure out is how to not break the library
ABI.  Right now there is really no way to do that without making
it a compile time feature for the library.  That is not really
an acceptable solution though.  So any ifdefs tricks will not
really solve the issue.

-vlad
--

The specification of sctp_connectx() has been changed to return
an association id.  Sence it is guaranteed the association id will
be a positive 32 bit integer, we can simply return that from our
setsockopt() in the case of success.  The library that implements
sctp_connectx() will re-interpret the call.

Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
---
 include/net/sctp/user.h |    6 +++-
 net/sctp/socket.c       |   70 +++++++++++++++++++++++++++++++++++++++-------
 2 files changed, 63 insertions(+), 13 deletions(-)

diff --git a/include/net/sctp/user.h b/include/net/sctp/user.h
index 9619b9d..41496f1 100644
--- a/include/net/sctp/user.h
+++ b/include/net/sctp/user.h
@@ -136,12 +136,14 @@ enum sctp_optname {
 #define SCTP_GET_LOCAL_ADDRS_NUM_OLD	SCTP_GET_LOCAL_ADDRS_NUM_OLD
 	SCTP_GET_LOCAL_ADDRS_OLD, 	/* Get all local addresss. */
 #define SCTP_GET_LOCAL_ADDRS_OLD	SCTP_GET_LOCAL_ADDRS_OLD
-	SCTP_SOCKOPT_CONNECTX, /* CONNECTX requests. */
-#define SCTP_SOCKOPT_CONNECTX	SCTP_SOCKOPT_CONNECTX
+	SCTP_SOCKOPT_CONNECTX_OLD, /* CONNECTX old requests. */
+#define SCTP_SOCKOPT_CONNECTX_OLD	SCTP_SOCKOPT_CONNECTX_OLD
 	SCTP_GET_PEER_ADDRS, 	/* Get all peer addresss. */
 #define SCTP_GET_PEER_ADDRS	SCTP_GET_PEER_ADDRS
 	SCTP_GET_LOCAL_ADDRS, 	/* Get all local addresss. */
 #define SCTP_GET_LOCAL_ADDRS	SCTP_GET_LOCAL_ADDRS
+	SCTP_SOCKOPT_CONNECTX, /* CONNECTX requests. */
+#define SCTP_SOCKOPT_CONNECTX	SCTP_SOCKOPT_CONNECTX
 };
 
 /*
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 8c90289..6b6ed19 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -956,7 +956,8 @@ out:
  */
 static int __sctp_connect(struct sock* sk,
 			  struct sockaddr *kaddrs,
-			  int addrs_size)
+			  int addrs_size,
+			  sctp_assoc_t *assoc_id)
 {
 	struct sctp_sock *sp;
 	struct sctp_endpoint *ep;
@@ -1111,6 +1112,8 @@ static int __sctp_connect(struct sock* sk,
 	timeo = sock_sndtimeo(sk, f_flags & O_NONBLOCK);
 
 	err = sctp_wait_for_connect(asoc, &timeo);
+	if (!err && assoc_id)
+		*assoc_id = asoc->assoc_id;
 
 	/* Don't free association on exit. */
 	asoc = NULL;
@@ -1128,7 +1131,8 @@ out_free:
 /* Helper for tunneling sctp_connectx() requests through sctp_setsockopt()
  *
  * API 8.9
- * int sctp_connectx(int sd, struct sockaddr *addrs, int addrcnt);
+ * int sctp_connectx(int sd, struct sockaddr *addrs, int addrcnt,
+ * 			sctp_assoc_t *asoc);
  *
  * If sd is an IPv4 socket, the addresses passed must be IPv4 addresses.
  * If the sd is an IPv6 socket, the addresses passed can either be IPv4
@@ -1144,8 +1148,10 @@ out_free:
  * representation is termed a "packed array" of addresses). The caller
  * specifies the number of addresses in the array with addrcnt.
  *
- * On success, sctp_connectx() returns 0. On failure, sctp_connectx() returns
- * -1, and sets errno to the appropriate error code.
+ * On success, sctp_connectx() returns 0. It also sets the assoc_id to
+ * the association id of the new association.  On failure, sctp_connectx()
+ * returns -1, and sets errno to the appropriate error code.  The assoc_id
+ * is not touched by the kernel.
  *
  * For SCTP, the port given in each socket address must be the same, or
  * sctp_connectx() will fail, setting errno to EINVAL.
@@ -1182,11 +1188,12 @@ out_free:
  * addrs     The pointer to the addresses in user land
  * addrssize Size of the addrs buffer
  *
- * Returns 0 if ok, <0 errno code on error.
+ * Returns >=0 if ok, <0 errno code on error.
  */
-SCTP_STATIC int sctp_setsockopt_connectx(struct sock* sk,
+SCTP_STATIC int __sctp_setsockopt_connectx(struct sock* sk,
 				      struct sockaddr __user *addrs,
-				      int addrs_size)
+				      int addrs_size,
+				      sctp_assoc_t *assoc_id)
 {
 	int err = 0;
 	struct sockaddr *kaddrs;
@@ -1209,13 +1216,46 @@ SCTP_STATIC int sctp_setsockopt_connectx(struct sock* sk,
 	if (__copy_from_user(kaddrs, addrs, addrs_size)) {
 		err = -EFAULT;
 	} else {
-		err = __sctp_connect(sk, kaddrs, addrs_size);
+		err = __sctp_connect(sk, kaddrs, addrs_size, assoc_id);
 	}
 
 	kfree(kaddrs);
+
 	return err;
 }
 
+/*
+ * This is an older interface.  It's kept for backward compatibility
+ * to the option that doesn't provide association id.
+ */
+SCTP_STATIC int sctp_setsockopt_connectx_old(struct sock* sk,
+				      struct sockaddr __user *addrs,
+				      int addrs_size)
+{
+	return __sctp_setsockopt_connectx(sk, addrs, addrs_size, NULL);
+}
+
+/*
+ * New interface for the API.  The since the API is done with a socket
+ * option, to make it simple we feed back the association id is as a return
+ * indication to the call.  Error is always negative and association id is
+ * always positive.
+ */
+SCTP_STATIC int sctp_setsockopt_connectx(struct sock* sk,
+				      struct sockaddr __user *addrs,
+				      int addrs_size)
+{
+	sctp_assoc_t assoc_id = 0;
+	int err = 0;
+
+	err = __sctp_setsockopt_connectx(sk, addrs, addrs_size, &assoc_id);
+
+	if (err)
+		return err;
+	else
+		return assoc_id;
+}
+
 /* API 3.1.4 close() - UDP Style Syntax
  * Applications use close() to perform graceful shutdown (as described in
  * Section 10.1 of [SCTP]) on ALL the associations currently represented
@@ -3164,10 +3204,18 @@ SCTP_STATIC int sctp_setsockopt(struct sock *sk, int level, int optname,
 					       optlen, SCTP_BINDX_REM_ADDR);
 		break;
 
+	case SCTP_SOCKOPT_CONNECTX_OLD:
+		/* 'optlen' is the size of the addresses buffer. */
+		retval = sctp_setsockopt_connectx_old(sk,
+					    (struct sockaddr __user *)optval,
+					    optlen);
+		break;
+
 	case SCTP_SOCKOPT_CONNECTX:
 		/* 'optlen' is the size of the addresses buffer. */
-		retval = sctp_setsockopt_connectx(sk, (struct sockaddr __user *)optval,
-					       optlen);
+		retval = sctp_setsockopt_connectx(sk,
+					    (struct sockaddr __user *)optval,
+					    optlen);
 		break;
 
 	case SCTP_DISABLE_FRAGMENTS:
@@ -3294,7 +3342,7 @@ SCTP_STATIC int sctp_connect(struct sock *sk, struct sockaddr *addr,
 		/* Pass correct addr len to common routine (so it knows there
 		 * is only one address being passed.
 		 */
-		err = __sctp_connect(sk, addr, af->sockaddr_len);
+		err = __sctp_connect(sk, addr, af->sockaddr_len, NULL);
 	}
 
 	sctp_release_sock(sk);
-- 
1.5.3.5