freebsd/lib/libgssapi/gss_wrap_size_limit.3

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.Dd January 26, 2010
.Dt GSS_WRAP_SIZE_LIMIT 3 PRM
.Os
.Sh NAME
.Nm gss_wrap_size_limit
.Nd Determine maximum message sizes
.\" This next command is for sections 2 and 3 only.
.\" .Sh LIBRARY
.Sh SYNOPSIS
.In "gssapi/gssapi.h"
.Ft OM_uint32
.Fo gss_wrap_size_limit
.Fa "OM_uint32 *minor_status"
.Fa "const gss_ctx_id_t context_handle"
.Fa "int conf_req_flag"
.Fa "gss_qop_t qop_req"
.Fa "OM_uint32 req_output_size"
.Fa "OM_uint32 *max_input_size"
.Fc
.Sh DESCRIPTION
Allows an application to determine the maximum message size that,
if presented to
.Xr gss_wrap 3
with the same
.Dv conf_req_flag
and
.Dv qop_req
parameters,
will result in an output token containing no more than
.Dv req_output_size
bytes.
.Pp
This call is intended for use by applications that
communicate over protocols that impose a maximum message size.
It enables the application to fragment messages prior to applying protection.
.Pp
GSS-API implementations are recommended but not required to detect
invalid QOP values when
.Fn gss_wrap_size_limit
is called.
This routine guarantees only a maximum message size,
not the availability of specific QOP values for message protection.
.Pp
Successful completion of this call does not guarantee that
.Xr gss_wrap 3
will be able to protect a message of length max_input_size bytes,
since this ability may depend on the availability of system resources
at the time that
.Xr gss_wrap 3
is called.
However, if the implementation itself imposes an upper limit on
the length of messages that may be processed by gss_wrap,
the implementation should not return a value via
.Dv max_input_bytes
that is greater than this length.
.Sh PARAMETERS
.Bl -tag -width ".It req_output_size"
.It minor_status
Mechanism specific status code.
.It context_handle
A handle that refers to the security over which the messages will be sent.
.It conf_req_flag
Indicates whether
.Xr gss_wrap 3
will be asked to apply confidentiality protection
in addition to integrity protection.
.It qop_req
Indicates the level of protection that
.Xr gss_wrap 3
will be asked to provide.
.It req_output_size
The desired maximum size for tokens emitted by
.Xr gss_wrap 3 .
.It max_input_size
The maximum input message size that may be presented to
.Xr gss_wrap 3
in order to guarantee that the emitted token shall
be no larger than
.Dv req_output_size
bytes.
.El
.Sh RETURN VALUES
.Bl -tag -width ".It GSS_S_CONTEXT_EXPIRED"
.It GSS_S_COMPLETE
Successful completion.
.It GSS_S_NO_CONTEXT
The referenced context could not be accessed.
.It GSS_S_CONTEXT_EXPIRED
The context has expired.
.It GSS_S_BAD_QOP
The specified QOP is not supported by the mechanism.
.El
.Sh SEE ALSO
.Xr gss_wrap 3
.Sh STANDARDS
.Bl -tag -width ".It RFC 2743"
.It RFC 2743
Generic Security Service Application Program Interface Version 2, Update 1
.It RFC 2744
Generic Security Service API Version 2 : C-bindings
.El
.Sh HISTORY
The
.Nm
function first appeared in
.Fx 7.0 .
.Sh AUTHORS
John Wray, Iris Associates
.Sh COPYRIGHT
Copyright (C) The Internet Society (2000).  All Rights Reserved.
.Pp
This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works.  However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than
English.
.Pp
The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns.
.Pp
This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.