xti_tcp.3.man

This a separate release of the OpenSS7 X/Open XTI/TLI library, TLI modules (timod, tirdwr) and the I

.I qlen
of zero and can be negotiated with
.BR t_optmgmt (3)
or
.BR t_connect (3).
.PP
This options is formatted as a
.BR t_uscalar_t .
It can take on any positive, non-zero value.
This options is not an
.IR "absolute requirement" .
The implementation may impose upper and lower limits on the value.  Proposed
values less than the lower limit will be negotiated to the lower limit.
.RE
.TP
.B T_TCP_LINGER2
Life time of orphaned FIN-WAIT-2 state.
This option determines the amount of time (in seconds) that a TCP connection
will be allowed to persist in the half-closed state before aborting the
connection.  It is useful for servers that may otherwise accumulate a large
number of half-closed TCP connections, exhausting system or network resources.
.RS
.PP
This option may be negotiated in any state; however, the value will not be
effective until an orderly release is initiated with a
.BR t_sndrel (3)
call.
.PP
This options is formatted as a
.BR t_uscalar_t .
It can take on any positive, or zero value.
This options is not an
.IR "absolute requirement" .
The implementation may impose upper and lower limits on the value.  Proposed
values less than the lower limit will be negotiated to the lower limit.
.RE
.TP
.B T_TCP_DEFER_ACCEPT
Wake up listener only when data arrives.
This option controls the behaviour of the implementation in response to the
.BR t_listen (3)
call.  When set to
.BR T_NO ,
as is normally the case,
.BR t_listen (3)
will return a connection indication as soon as an incoming TCP connection is
established.  When negotiated to
.BR T_YES ,
.BR t_listen (3)
will return a connection indication only after data is first received on an
established incoming TCP connection.
.RS
.PP
This option can only be negotiated in the
.BR T_IDLE
state for a stream bound with
.I qlen
greater than zero.  This option may be set on a listening stream using
.BR t_optmgmt (3)
prior to a call to
.BR t_listen (3)
in fitting with
.B XTI-TCP
connection indication options negotiation.
.PP
This option is formatted as a
.BR t_uscalar_t .
It can take on values
.BR T_YES " and " T_NO .
This option is not an
.IR "absolute requirement" .
.RE
.TP
.B T_TCP_WINDOW_CLAMP
Bound advertised window.
This option specifies an upper bound on the advertised receive window.  Values
greater that the actual or effective receive window size will be ignored.
.RS
.PP
This options is formatted as a
.BR t_uscalar_t .
It can take on any positive, non-zero value.
This options is not an
.IR "absolute requirement" .
The implementation may impose upper and lower limits on the value.  Proposed
values less than the lower limit will be negotiated to the lower limit.
.RE
.TP
.B T_TCP_INFO
Information about this connection.
.RS
.PP
This option is read-only and can be read with a call to
.BR t_optmgmt (3)
in any state.
.PP
This option is formatted as a
.B t_tcp_info
structure, formatted as follows:
.PP
.nf
\fC\s-1\
struct t_tcp_info {
    u_char_t tcpi_state;
    u_char_t tcpi_ca_state;
    u_char_t tcpi_retransmits;
    u_char_t tcpi_probes;
    u_char_t tcpi_backoff;
    u_char_t tcpi_options;
    u_char_t tcpi_snd_wscale:4, tcpi_rcv_wscale:4;
    uint32_t tcpi_rto;
    uint32_t tcpi_ato;
    uint32_t tcpi_snd_mss;
    uint32_t tcpi_rcv_mss;
    uint32_t tcpi_unacked;
    uint32_t tcpi_sacked;
    uint32_t tcpi_lost;
    uint32_t tcpi_retrans;
    uint32_t tcpi_fackets;
    /* Times. */
    uint32_t tcpi_last_data_sent;
    uint32_t tcpi_last_ack_sent; /* Not remembered, sorry. */
    uint32_t tcpi_last_data_recv;
    uint32_t tcpi_last_ack_recv;
    /* Metrics. */
    uint32_t tcpi_pmtu;
    uint32_t tcpi_rcv_ssthresh;
    uint32_t tcpi_rtt;
    uint32_t tcpi_rttvar;
    uint32_t tcpi_snd_ssthresh;
    uint32_t tcpi_snd_cwnd;
    uint32_t tcpi_advmss;
    uint32_t tcpi_reordering;
};
\s+1\fP
.fi
.TP
.I tcpi_state
.PD 0
.TP
.I tcpi_ca_state
.RS
.TP
.B TCP_CA_Open
.TP
.B TCP_CA_Disorder
.TP
.B TCP_CA_CWR
.TP
.B TCP_CA_Recovery
.TP
.B TCP_CA_Loss
.RE
.TP
.I tcpi_retransmits
.TP
.I tcpi_probes
.TP
.I tcpi_backoff
.TP
.I tcpi_options
.TP
.I tcpi_snd_wscale
.TP
.I tcpi_rcv_wscale
.TP
.I tcpi_rto
.TP
.I tcpi_ato
.TP
.I tcpi_snd_mss
.TP
.I tcpi_rcv_mss
.TP
.I tcpi_unacked
.TP
.I tcpi_sacked
.TP
.I tcpi_lost
.TP
.I tcpi_retrans
.TP
.I tcpi_fackets
.TP
.I tcpi_last_data_sent
.TP
.I tcpi_last_ack_sent
.TP
.I tcpi_last_data_recv
.TP
.I tcpi_last_ack_recv
.TP
.I tcpi_pmtu
.TP
.I tcpi_rcv_ssthresh
.TP
.I tcpi_rtt
.TP
.I tcpi_rttvar
.TP
.I tcpi_snd_ssthresh
.TP
.I tcpi_snd_cwnd
.TP
.I tcpi_advmss
.TP
.I tcpi_reordering
.PD
.RE
.TP
.B T_TCP_QUICKACK
Block or reenable quick acks.
.RS
.PP
This option is formatted as a
.BR t_uscalar_t .
It can take on values
.BR T_YES " or " T_NO .
This option is not an
.IR "absolute requirement" .
.RE
.\"
.\"
.SH FUNCTIONS
.PP
.B XTI-TCP
supports the XTI/TLI library functions as described in this section.  All
connection-oriented XTI/TLI library calls are supported for TCP; however, some
features of the connection-oriented XTI/TLI library calls are supported by the
underlying transport service provider and some are not.
.\"
.\"
.SS t_accept\fR(3)
.PP
.B XTI-TCP
supports this XTI/TLI library call as described in
.BR t_accept (3),
with the additional considerations described here.
.PP
Issuing
.BR t_accept (3)
assigns an already established connection to
.IR resfd .
.PP
Since user data cannot be exchanged during the connection establishment phase,
.I call->udata.len
must be set to zero.
.PP
When
.RI ( "resfd != fd" ),
the function
.BR t_accept (3)
is recommended to be called with
.I resfd
in the
.B T_UNBND
state, though an endpoint which is bound to any local address (in the
.B T_IDLE
state) can also be used.
.PP
After
.BR t_accept (3)
completes, the endpoint
.I resfd
will represent a connected TCP endpoint whose complete binding essentially has
both local and remote address components.
.PP
If file descriptor
.I resfd
was unbound before calling
.BR t_accept (3),
after the call completes its local address binding would be to the same
protocol address bound to
.IR fd .
If the file descriptor
.I resfd
was bound to a local address before calling
.BR t_accept (3),
that local address binding is dissolved and the local address part of the
binding after
.BR t_accept (3)
completes would become the same as the address bound to
.IR fd .
.PP
If options with end-to-end significance
.RB ( T_IP_OPTIONS " and " T_IP_TOS )
are to be sent with the connection confirmation, the values of these options
must be set with
.BR t_optmgmt (3)
prior to the
.B T_LISTEN
event occurs.  When the transport user detects a
.B T_LISTEN
event, TCP has already established the connection.  Association-related
options passed with
.BR t_accept (3)
become effective at once, but since the connection is already established,
they are transmitted with subsequent IP datagrams sent out in the
.B T_DATAXFER
state.
.PP
.B XTI-TCP
provides a number of options, described in
.RI \*(lq OPTIONS \*(rq,
above, that may be included in this XTI/TLI call in the
.I call->opt
parameter to change local and end-to-end characteristics of the transport
endpoint accepting the connection.  The options of end-to-end significance
that can be included in this XTI/TLI library call are:
.TP
.I T_IP_OPTIONS
.TP
.I T_IP_TOS
.PP
The options of local significance that can be included in this XTI/TLI call
include (other options of local significance may also be included):
.TP
.I XTI_DEBUG
.TP
.I XTI_LINGER
.TP
.I XTI_RCVBUF
.TP
.I XTI_RCVLOWAT
.TP
.I XTI_SNDBUF
.TP
.I XTI_SNDLOWAT
.TP
.I T_IP_TTL
.TP
.I T_IP_REUSEADDR
.TP
.I T_IP_DONTROUTE
.TP
.I T_TCP_NODELAY
.TP
.I T_TCP_MAXSEG
.TP
.I T_TCP_KEEPALIVE
.TP
.I T_TCP_KEEPIDLE
.TP
.I T_TCP_KEEPCNT
.TP
.I T_TCP_WINDOW_CLAMP
.TP
.I T_TCP_QUICKACK
.\"
.\"
.SS t_bind\fR(3)
.PP
.B XTI-TCP
supports this XTI/TLI library call as described in
.BR t_bind (3),
with the additional considerations described here.
.PP
The
.I addr
field of the
.B t_bind
structure represents the local socket; that is, an address which specifically
includes a port identifier.
.PP
The
.BR INET (4)
implementation treats port number zero (0) as a request to bind to any
unused port.  Other than that value, the
.I req->addr.sin_port
part of the binding is specific.  The
.I req->addr.sin_addr.in_addr
part of the binding can represent a single IP address or a wildcard binding to
an address that could represent multiple IP addresses that are legal for the
host
.RB ( INADDR_ANY ).
.PP
Under recent versions of
.BR INET (4),
.BR t_bind (3)
called with a
.B NULL
.I req
argument is equivalent to binding to a wildcard port number with a wildcard IP
address.
.PP
Under
.BR INET (4),
when bound to a wildcard port or IP address, assignment of a specific port
number and IP address can be deferred until an incoming or outgoing connection
is initiated.  Under these situations, any address returned in the
.I ret
argument to
.BR t_bind (3)
or the
.I loc
argument to
.BR t_getprotaddr (3)
will return the wildcard address and port number instead of an assigned
address and port number.
Only once a connection has been established will the local address returned by
.BR t_getprotaddr (3)
be assured to be an assigned address rather than a wildcard address.
.\"
.\"
.SS t_close\fR(3)
.PP
.B XTI-TCP
supports this XTI/TLI library call as described in
.BR t_close (3)
without modification.
.PP
The
.BR t_close (3)
call will result in a
.BR close (2)
call on the descriptor of this XTI/TLI communication endpoint.  If there are no
other descriptors in this process which reference the communications endpoint,
the
.BR close (2)
call will perform an orderly connection termination according to the rules of
a TCP CLOSE call on this transport endpoint as specified in the standards
.I RFC 793
.[
rfc 793
.]
and
.IR "RFC 1122" .
.[
rfc 1122
.]
If the
.B XTI_LINGER
option is supported and is used to enable the linger option, the linger time
will affect the time an implementation lingers in the execution of
.BR t_close (3)
or
.BR close (2).
A linger time of zero (0) specified with the
.B XTI_LINGER
option may cause an abortive release of a TCP connection, resulting in lost
data.
.\"
.\"
.SS t_connect\fR(3)
.PP
.B XTI-TCP
supports this XTI/TLI library call as describe din
.BR t_connect (3),
with the additional considerations described here.
.PP
The
.I sndcall->addr
structure specifies the remote socket.  In the present version, the returned
address set in
.I rcvcall->addr
will have the same value.  Since user data cannot be exchanged during the
connection establishment phase,
.I sndcall->udata.len
must be set to zero (0).
Note that the peer TCP, and not the peer transport user, confirms the
connection.
.PP
.B XTI-TCP
provides a number of options, described in
.RI \*(lq OPTIONS \*(rq,
above, that may be included in this XTI/TLI call in the
.I sndcall->opt
parameter to change local and end-to-end characteristics of the transport
endpoint accepting the connection.  The option of end-to-end significance that
can be included in this XTI/TLI library call are:
.TP
.I T_IP_OPTIONS
.TP
.I T_IP_TOS
.PP
The options of local significance that cne be included in this XTI/TLI call
include (other options of local significance may also be included):
.TP
.I XTI_DEBUG
.TP
.I XTI_LINGER
.TP
.I XTI_RCVBUF
.TP
.I XTI_RCVLOWAT
.TP
.I XTI_SNDBUF
.TP
.I XTI_SNDLOWAT
.TP
.I T_IP_TTL
.TP
.I T_IP_REUSEADDR
.TP
.I T_IP_DONTROUTE
.TP
.I T_TCP_NODELAY
.TP
.I T_TCP_MAXSEG
.TP
.I T_TCP_KEEPALIVE
.TP
.I T_TCP_KEEPIDLE
.TP
.I T_TCP_KEEPCNT
.TP
.I T_TCP_WINDOW_CLAMP
.TP
.I T_TCP_QUICKACK
.\"
.\"
.SS t_getinfo\fR(3)
.PP
.B XTI-TCP
supports this XTI/TLI library call as describe din
.BR t_connect (3)
with the additional considerations described here.
.TP \w'servtype\(em'u
.I addr
For compatibility with the
.BR sockets (3)
library,
.B TCP
uses a
.BR sockaddr_in
structured address (see
.RI \*(lq "ADDRESS FORMAT" \*(rq,
above).  This size will be the size of a
.B sockaddr_in
structure.
.TP
.I options
The maximum size of options is provider specific.
The
.B OpenSS7
TCP driver
.RB ( tcp (4))
returns the maximum size of an option structure containing all TCP options.
.TP
.I tsdu
The maximum size of a transport service data unit.  For TCP this is the
maximum size of a message, considering that it may be segmented and sent in
multiple packets.  For TCP this value could be
.BR T_INFINITE .
.TP
.I etsdu
TCB supports the concept of sending expedited data as out-of-band data.  TCP
conforming transport providers will not return
.B T_INVALID
for this field.  The maximum ETSDU size is a single character or 1 octet.
.TP
.I connect
.B XTI-TCP
does not support the concept of connection data.  TCP conforming transport
providers will always return
.B T_INVALID
for this field.
.TP
.I discon
.B XTI-TCP
does not support the concept of diconnection data.  TCP conforming