The gss_wrap_size_limit() function allows an application to determine the maximum message size that, if presented to gss_wrap() with the same conf_req_flag and qop_req parameters, results 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. The GSS-API detects 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 gss_wrap_size_limit() does not guarantee that gss_wrap() will be able to protect a message of length max_input_size bytes, since this ability might depend on the availability of system resources at the time that gss_wrap() is called.

The parameter descriptions for gss_wrap_size_limit() are as follows:

minor_status

A 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() will be asked to apply confidential protection in addition to integrity protection. See gss_wrap(3GSS) for more details.

qop_req

Indicates the level of protection that gss_wrap() will be asked to provide. See gss_wrap(3GSS) for more details.

req_output_size

The desired maximum size for tokens emitted by gss_wrap().

max_input_size

The maximum input message size that can be presented to gss_wrap() to guarantee that the emitted token will be no larger than req_output_size bytes.

gss_wrap_size_limit() returns one of the following status codes:

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.

GSS_S_FAILURE

The underlying mechanism detected an error for which no specific GSS status code is defined. The mechanism-specific status code reported by means of the minor_status parameter details the error condition.

See attributes(5) for descriptions of the following attributes:

gss_wrap(3GSS), attributes(5)

GSS-API Programming Guide