NAME

gss_wrap_size_limit — Determine maximum message sizes

SYNOPSIS

#include <gssapi/gssapi.h>

OM_uint32
gss_wrap_size_limit(OM_uint32 *minor_status, const gss_ctx_id_t context_handle, int conf_req_flag, gss_qop_t qop_req, OM_uint32 req_output_size, OM_uint32 *max_input_size);

DESCRIPTION

Allows an application to determine the maximum message size that, if presented to gss_wrap(3) with the same conf_req_flag and qop_req parameters, will result in an output token containing no more than req_output_size bytes.

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.

GSS-API implementations are recommended but not required to detect invalid QOP values when gss_wrap_size_limit() is called. This routine guarantees only a maximum message size, not the availability of specific QOP values for message protection.

Successful completion of this call does not guarantee that 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 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 max_input_bytes that is greater than this length.

PARAMETERS

minor_status: Mechanism specific status code.
context_handle: A handle that refers to the security over which the messages will be sent.
conf_req_flag: Indicates whether gss_wrap(3) will be asked to apply confidentiality protection in addition to integrity protection.
qop_req: Indicates the level of protection that gss_wrap(3) will be asked to provide.
req_output_size: The desired maximum size for tokens emitted by gss_wrap(3).
max_input_size: The maximum input message size that may be presented to gss_wrap(3) in order to guarantee that the emitted token shall be no larger than req_output_size bytes.

RETURN VALUES

GSS_S_COMPLETE: Successful completion.
GSS_S_NO_CONTEXT: The referenced context could not be accessed.
GSS_S_CONTEXT_EXPIRED: The context has expired.
GSS_S_BAD_QOP: The specified QOP is not supported by the mechanism.

STANDARDS

RFC 2743: Generic Security Service Application Program Interface Version 2, Update 1
RFC 2744: Generic Security Service API Version 2 : C-bindings

HISTORY

The gss_wrap_size_limit function first appeared in FreeBSD 7.0.

AUTHORS

John Wray, Iris Associates

COPYRIGHT

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