rpc_gss_set_callback(3N)

NAME

rpc_gss_set_callback() — specify callback for context

SYNOPSIS

#include <rpc/rpcsec_gss.h>

bool_t rpc_gss_set_callback(
struct rpc_gss_callback_t *cb);

DESCRIPTION

A server may want to specify a callback routine so that it knows when a context gets first used. This user-defined callback may be specified through the rpc_gss_set_callback() routine. The callback routine is invoked the first time a context is used for data exchanges, after the context is established for the specified program and version.

The user-defined callback routine should take the following form:

bool_t callback(
struct svc_req *req,
gss_cred_id_t deleg,
gss_ctx_id_t gss_context,
rpc_gss_lock_t *lock,
void **cookie);

PARAMETERS

rpc_gss_set_callback() takes one argument: a pointer to a rpc_gss_callback_t structure. This structure contains the RPC program and version number as well as a pointer to a user-defined callback() routine. For a description of rpc_gss_callback_t and other RPCSEC_GSS data types, see the rpcsec_gss(3N) manpage.

The user-defined callback() routine itself takes the following arguments:

req: Pointer to the received service request. svc_req is an RPC structure containing information on the context of an RPC invocation, such as program, version, and transport information.
deleg: Delegated credentials, if any. (See WARNING, below.)
gss_context: GSS context (allows the server to do GSS operations on the context to test for acceptance criteria). (See WARNING, below.)
lock: This parameter is used to enforce a particular QOP and service for a session. This parameter points to a RPCSEC_GSS rpc_gss_lock_t structure. When the call-back is invoked, the rpc_gss_lock_t.locked field is set to TRUE, thus locking the context. A locked context will reject all requests having different values for QOP or service than those specified by the raw_cred field of the rpc_gss_lock_t structure.
cookie: A four-byte quantity that an application may use in any manner because RPC does not interpret it. For example, the cookie could be a pointer or index to a structure that represents a context initiator. The cookie is returned, along with the caller's credentials, with each invocation of rpc_gss_getcred().

MULTITHREAD USAGE

Thread Safe:: Yes
Cancel Safe:: Yes
Fork Safe:: No
Async-cancel Safe:: No
Async-signal Safe:: No

These functions can be called safely in a multithreaded environment. They may be cancellation points in that they call functions that are cancel points.

In a multithreaded environment, these functions are not safe to be called by a child process after fork() and before exec(). These functions should not be called by a multithreaded application that supports asynchronous cancellation or asynchronous signals.

RETURN VALUE

rpc_gss_set_callback() returns TRUE if the use of the context is accepted; FALSE otherwise.

WARNING

If a server does not specify a callback, all incoming contexts will be accepted.

Because the GSS-API is not currently exposed, the deleg and gss_context arguments are mentioned for informational purposes only, and the user-defined callback function may choose to do nothing with them.

rpc_gss_set_callback(3N)

Technical documentation

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