xti_tcp.3.man

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

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.\"
.\"
.\"
.\"
.TH XTI-TCP 3 "2004/05/16 02:35:38" "strxnet-0_9_2-4" "X/Open Transport Interface"
.\"
.\"
.SH "NAME"
.B xti_tcp
\- X/Open Transport Interface \- Corrigendum for Transmission Control Protocol (TCP) Conformance
.\"
.\"
.SH SYNOPSIS
.PP
.B #include <xti.h>
.br
.B #include <xti_ip.h>
.br
.B #include <xti_tcp.h>
.HP
.BI "int " tcp_xtistr " = t_open(" \fR\*(lq/dev/tcp\*(rq\fI ", " flags );
.\"
.\"
.SH DESCRIPTION
.PP
This manual section describes the protocol-specific information that is
relevant for TCP transport providers.  This section also describes the
protocol-specific information that is relevant when TCP services are provided
over an IP network using TCP.
.PP
This section also defines the data structures and constants required for TCP
transport providers that are exposed through the
.B <xti_tcp.h>
header file.
.\"
.\"
.SH "ADDRESS FORMAT"
.PP
The TCP address format is structured as follows:
.PP
.nf
\fC\s-1\
struct sockaddr_in {
    sa_family_t         sin_family;  /* Address family */
    unsigned short int  sin_port;    /* Port number */
    struct in_addr      sin_addr;    /* Interned address */
    /* padding */
};
\s+1\fP
.fi
.PP
The
.B sockaddr_in
structure contains the following members:
.TP \w'sin_family\(em'u
.I sin_family
The address family.  Always set to
.BR AF_INET " or " AF_UNSPEC .
.PD 0
.TP
.I sin_port
The port number of the transport endpoint.
.TP
.I sin_addr
The IP address of the transport endpoint.
.TP
.I (padding)
Padding to pad the size of the
.B sockaddr_in
structure to the size of a
.B sockaddr
structure.
.PD
.PP
The structure is padded to the size of a
.BR sockaddr
structure.
.\"
.\"
.SH OPTIONS
.PP
Options are formatted according to the
.B t_opthdr
structure as described in
.BR xti (3).
An TCP transport provider compliant to this specification supports none, all
or any subset of the options defined here.  An implementation may restrict the
use of any of these options by offering them only in a priviledged read-only
mode.
.PP
An TCP transport provider supports three levels of options.  These three levels
are described below.
.\"
.\"
.SS "XTI_GENERIC"
.PP
Options with this level are specific to the X/Open Transport Interface (XTI/TLI)
.[
xti
.]
and are common to all transport providers.  For more information see
.BR xti (3).
.PP
The options defined with the option level
.B XTI_GENERIC
are as follows:
.TP
.B XTI_DEBUG
Sets debugging flags for the stream.
This option is formatted as an array of
.BR t_uscalar_t .
Legal values are implementation defined.
For more information, see
.BR xti (3).
.TP
.B XTI_LINGER
Sets whether, and the amount of time if, the stream will linger waiting for
unsent data to be delivered.
This option is formatted as a
.B t_linger
structure as follows:
.RS
.PP
.nf
\fC\s-1\
struct t_linger {
    t_scalar_t l_onoff;   /* option on/off */
    t_scalar_t l_linger;  /* linger time */
};
\s+1\fP
.fi
.TP \w'l_linger\(em'u
.I l_onoff
Specifies whether to linger
.RB ( T_YES )
or not
.RB ( T_NO ).
Legal values are
.BR T_YES " and " T_NO .
.TP
.I l_linger
Specifies the amount of time (in seconds) to linger.
Legal values are
.BR T_INFINITE ", " T_UNSPEC
and all positive numbers including zero.
.PP
For more information, see
.BR xti (3).
.RE
.TP
.B XTI_RCVBUF
Specifies the size, in bytes, of the receive buffer.
This option is formatted as a
.BR t_uscalar_t .
Legal values are all positive, non-zero numbers.
For more information, see
.BR xti (3).
.TP
.B XTI_RCVLOWAT
Specifies the low water mark above which received data will be indicated and
delivered to the user.
This option is formatted as a
.BR t_uscalar_t .
Legal values are all positive, non-zero numbers.
For more information, see
.BR xti (3).
.TP
.B XTI_SNDBUF
Specifies the size, in bytes, of the transmit buffer.
This option is formatted as a
.BR t_uscalar_t .
Legal values are all positive, non-zero numbers.
For more information, see
.BR xti (3).
.TP
.B XTI_SNDLOWAT
Specifies the low water mark above which queued data will be transmitted to
the peer.
This option is formatted as a
.BR t_uscalar_t .
Legal values are all positive, non-zero numbers.
For more information, see
.BR xti (3).
.\"
.\"
.SS "T_INET_IP"
.PP
Options within this level are specific to the Internet Protocol (IP) and are
common to all the protocol levels in IP.  For more information, see
.BR xti_ip (3).
.PP
The options defined with the option level
.B T_INET_IP
are as follows:
.TP
.B T_IP_OPTIONS
Provides control for the T_IP OPTIONS field.  Used for debugging.
This option is formatted as an array of
.BR "unsigned char" ,
up to 40 elements.
For more information, see
.BR xti_ip (3).
.TP
.B T_IP_TOS
Provides control of the type-of-service byte present in each transmited T_IP
packet.
This option is formated as an
.BR "unsigned char" .
Legal values can be generated with the
.BR SET_TOS ()
macro described in
.BR xti_ip (3).
For more information, see
.BR xti_ip (3).
.TP
.B T_IP_TTL
Provides control of the time-to-live byte present in each transmitted T_IP
packet.
This option is formatted as an
.BR "unsigned char" .
Legal values are from 0 to 255.
For more information, see
.BR xti_ip (3).
.TP
.B T_IP_REUSEADDR
Allows multiple non-listening binds to the same address.
This option is format as a
.BR "unsigned int" .
Legal values are
.BR T_YES " and " T_NO .
For more information, see
.BR xti_ip (3).
.TP
.B T_IP_DONTROUTE
Bypasses routing tables and routes directly to an interface.  Used for
debugging.
This option is format as a
.BR "unsigned int" .
Legal values are
.BR T_YES " and " T_NO .
For more information, see
.BR xti_ip (3).
.TP
.B T_IP_BROADCAST
Allows broadcast addresses to be used.  This option is not applicable to TCP
and is always set to
.BR T_NO .
This option is format as a
.BR "unsigned int" .
Legal values are
.BR T_YES " and " T_NO .
For more information, see
.BR xti_ip (3).
.\"
.\"
.SS "T_INET_TCP"
.PP
Options within this level are specific to the Transmission Control
Protocol (TCP) yet are used by protocol levels using TCP transport.
.PP
The options defined with the option level
.B T_INET_TCP
are as follows:
.TP
.B T_TCP_NODELAY
Under most circumstances, TCP sends data as soon as it is presented.  When
outstanding data hs not yet been acknowledged, it gathers small amounts of
output to be sent in a single packet once an acknowledgment is received.  For
a small number of clients, such a window system (for example,
.IR "MIT X Window System" )
that send a stream of mouse events which receive no replies, this
packetisation may cause significant delays. 
.B T_TCP_NODELAY
is used to defeat this algorithm.  Legal option values are
.B T_YES
("don't delay") and
.B T_NO
("delay").
.RS
.PP
This option can be negotiated in any state; however, this option will not take
effect until data is sent with
.BR t_snd "(3) or " t_sndv (3),
or unless data is already queued for transmission at the time that the option
is negotiated.  A value for this option can be proposed in
.BR t_optmgmt "(3), " t_connect "(3) or " t_accept (3).
.PP
This option is mutually exclusive with
.BR T_TCP_CORK .
Attempts to negotiate this option to
.BR T_YES
when
.B T_TCP_CORK
has already been negotiated to
.B T_YES
will fail.
.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 an
.IR "absolute requirement" .
.RE
.TP
.B T_TCP_MAXSEG
This option determines the maximum segment size for outgoing packets.  Values
greater than the association MTU are ignored and have no effect.  The value
determines the maximum size (in octets) above which TCP will fragment larger
data segments into smaller ones.  Normally this value is the connection MTU
value minus the size of the current IP and TCP headers  If the transport user
negotiates this value to a lower value, the lower value will be used.
.RS
.PP
Per
.IR "XNS 5.2" ,
.[
xns 5.2
%P Appendix B
.]
this option is read-only.  It is used only to retrieve the maximum TCP segment
size.  The write behavior described here is for compatibility with the
.B Linux
.BR tcp (7)
implementation.
.PP
This option is formatted as a
.BR t_uscalar_t .
It can take on any positive value.
This option is not an
.IR "absolute requirement" .
The implementation may impose lower and upper bounds on the value.  If the
proposed value is less than the lower bound, the option will be negotiated to
the lower bound.
.RE
.TP
.B T_TCP_KEEPALIVE
If this option is set, a keep-alive timer is activated to monitor idle
connections that might no longer exist.  If a connection has been idle since
the last keep-alive timeout, a keep-alive packet is sent to check if the
connection is still alive or broken.
.RS
.PP
Keep-alive packets are not an explicit feature of TCP, and this practice is
not universally accepted.  According to
.I RFC 1122
.[
rfc 1122
.]
\*(lqa keep-alive mechanism should only be invoked in service applications that
might otherwise hang indefinitely and consume resources unnecessarily if a
client crashes or aborts a connection during a network failure.\*(rq
.PP
The option value consists of a
.B t_kpalive
structure, with the following members:
.PP
.nf
\fC\s-1\
struct t_kpalive {
    t_scalar_t kp_onoff;    /* option on/off */
    t_scalar_t kp_timeout;  /* timeout in minutes */
};
\s+1\fP
.fi
.TP \w'kp_timeout\(em'u
.I kp_onoff
The
.I kp_onoff
field determines whether keep-alive is activated and can assume values
.BR T_NO " or " T_YES .
.TP
.I kp_timeout
The
.I kp_timeout
field determines the frequency of keep-alive packets being sent, in minutes.
The transport user can request the default value by setting the field to
.BR T_UNSPEC .
The default is implementation-dependent, but at least
.B 120
minutes (see
.IR "RFC 1122" ).
.[
rfc 1122
.]
Legal values for this field are
.B T_UNSPEC
and all positive numbers.
.PP
The timeout value is not an
.IR "absolute requirement" .
The implementation may impose upper and lower limits on this value.  Requests
that fall short of the lower limit may be negotiated to the lower limit.  The
use of this option might be restricted to privileged users.
.PP
This option is formatted as
.B t_kpalive
structure.  This option is an
.IR "absolute requirement" .
.RE
.PP
The following options are not described in XTI/TLI
.[
xti
.]
or XNS 5.2
.[
xns 5.2
.]
literature, however, they are provided for compatibility with the socket
options of the
.B Linux
socket implementation (see
.BR tcp (7)).
.TP
.B T_TCP_CORK
Never send partially complete segments.
This option determines whether to cork the transmission stream waiting for
subsequent transmission requewsts.  When set
.RB ( T_YES ),
this option permits a number of
.BR t_snd (3)
operations to be peformed without send the data subsequent to the cork.  When
the cork is released
.RB ( T_NO ),
all data will be permitted to proceed to tranmsission.
.RS
.PP
This option can only be negotiated to
.B T_YES
if the option
.B T_TCP_NODELAY
has been negotiated to
.BR T_NO .
Otherwise, negotiation will fail.
.PP
This option is formatted as a
.BR t_uscalar_t .
It can take on values
.BR T_YES ,
conveying that the transmission is corked, or,
.BR T_NO ,
conveying that transmission is uncorked.
This option is not an
.IR "absolute requirement" .
.RE
.TP
.B T_TCP_KEEPIDLE
Start keepalives after this period.
This option determines the period of time, in seconds, that the endpoint will
allow the connection to remain idle util initiating sending of keepalive
packets.
Valid values are any positive value greater than zero (0).
.RS
.PP
This option is formatted as a
.BR t_uscalar_t .
It can take on any positive, non-zero value.
This option 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_KEEPCNT
Number of keepalives before death.
This option determines the number of keepalives that will be sent without
response before aborting the connection.
Valid values are any positive value greater than zero (0).
.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_SYNCNT
Number of SYN retransmits.
This option determines the number of times that a SYN will be resent before
abandoning transport connection establishment.
Valid values are any positive value greater than zero (0).
.RS
.PP
This option is valid in state
.B T_IDLE
with a