xnu-3789.70.16.tar.gz

[apple/xnu.git] / bsd / man / man4 / tcp.4

diff --git a/bsd/man/man4/tcp.4 b/bsd/man/man4/tcp.4
index 05584e2557b27888ab65b7420fa81bf7bbebcf86..9f011e793e0b5e523993419aaa55d5e0e3c4a112 100644 (file)
--- a/bsd/man/man4/tcp.4
+++ b/bsd/man/man4/tcp.4
@@ -33,7 +33,7 @@
 .\"
 .\"     @(#)tcp.4      8.1 (Berkeley) 6/5/93
 .\"
-.Dd April 16, 2014
+.Dd March 18, 2015
 .Dt TCP 4
 .Os BSD 4.2
 .Sh NAME
@@ -87,6 +87,8 @@ Only passive sockets may use the
 call to accept incoming connections.
 Only active sockets may use the
 .Xr connect 2
+or
+.Xr connectx 2
 call to initiate connections.
 .Pp
 Passive sockets may
@@ -200,7 +202,7 @@ acknowledgement for every other data packet.
 .It Dv TCP_ENABLE_ECN
 Using Explicit Congestion Notification (ECN) on
 .Tn TCP
-allows end-to-end notification of congestion without dropping packets. Conventionally TCP/IP networks signal congestion by dropping packets. When ECN is successfully negotiated, an ECN-aware router may set a mark in the IP header instead of dropping a packet in order to signal impending congestion. The 
+allows bi-directional end-to-end notification of congestion without dropping packets. Conventionally TCP/IP networks signal congestion by dropping packets. When ECN is successfully negotiated, an ECN-aware router may set a mark in the IP header instead of dropping a packet in order to signal impending congestion. The
 .Tn TCP
 receiver of the packet echoes congestion indication to the 
 .Tn TCP
@@ -209,6 +211,15 @@ sender, which reduces it's transmission rate as if it detected a dropped packet.
 The send socket buffer of a
 .Tn TCP sender has unsent and unacknowledged data. This option allows a 
 .Tn TCP sender to control the amount of unsent data kept in the send socket buffer. The value of the option should be the maximum amount of unsent data in bytes. Kevent, poll and select will generate a write notification when the unsent data falls below the amount given by this option. This will allow an application to generate just-in-time fresh updates for real-time communication.
+.It Dv TCP_FASTOPEN
+The TCP listener can set this option to use TCP Fast Open feature. After
+setting this option, an
+.Xr accept 2
+may return a socket that is in SYN_RECEIVED state but is readable and writable.
+.It Dv TCP_CONNECTION_INFO
+This socket option can be used to obtain TCP connection level statistics. The
+"struct tcp_connection_info" defined in <netinet/tcp_var.h> is copied to the
+user buffer.
 .El
 .Pp
 The option level for the
@@ -236,6 +247,8 @@ When a
 .Tn TCP
 socket is set non-blocking, and the connection cannot be established immediately, 
 .Xr connect 2
+or
+.Xr connectx 2
 returns with the error
 .Dv EINPROGRESS ,
 and the connection is established asynchronously.
@@ -255,6 +268,8 @@ can be retrieved via the socket option
 Note that even if the socket is non-blocking, it is possible for the connection 
 to be established immediately. In that case 
 .Xr connect 2
+or
+.Xr connectx 2
 does not return with 
 .Dv EINPROGRESS .
 .Sh DIAGNOSTICS
@@ -290,16 +305,29 @@ address;
 .It Bq Er EINPROGRESS
 returned by
 .Xr connect 2
+or
+.Xr connectx 2
 when the socket is set nonblocking, and the connection cannot be 
 immediately established;
 .It Bq Er EALREADY
 returned by
 .Xr connect 2
+or
+.Xr connectx 2
 when connection request is already in progress for the specified socket.
+.It Bq Er ENODATA
+returned by
+.Xr recv 2
+or
+.Xr send 2
+in case a connection is experiencing a data-stall (probably due to a middlebox issue).
+It is advised that the current connection gets closed by the application and a
+new attempt is being made.
 .
 .El
 .Sh SEE ALSO
 .Xr connect 2 ,
+.Xr connectx 2 ,
 .Xr getsockopt 2 ,
 .Xr kqueue 2 ,
 .Xr poll 2 ,