NAME

nis_groups, nis_ismember, nis_addmember, nis_removemember, nis_creategroup, nis_destroygroup, nis_verifygroup, nis_print_group_entry, nis_map_group, __nis_map_group - NIS+ group manipulation functions

SYNOPSIS

cc [ flag . . . ] file. . . -lnsl [ library. . . ]

#include <rpcsvc/nis.h>
bool_t nis_ismember(const nis_name principal, const nis_name group);
nis_error nis_addmember(const nis_name member, const nis_name group);
nis_error nis_removemember(const nis_name member, const nis_name group);
nis_error nis_creategroup(const nis_name group, const u_long flags);
nis_error nis_destroygroup(const nis_name group);
void nis_print_group_entry(const nis_name group);
nis_error nis_verifygroup(const nis_name group);

MT-LEVEL

MT-Safe

DESCRIPTION

These functions manipulate NIS+ groups. They are used by NIS+ clients and servers, and are the interfaces to the group authorization object.

The names of NIS+ groups are syntactically similar to names of NIS+ objects but they occupy a separate namespace. A group named "a.b.c.d." is represented by a NIS+ group object named "a.groups_dir.b.c.d."; the functions described here all expect the name of the group, not the name of the corresponding group object.

There are three types of group members:

An explicit member is just a NIS+ principal-name, for example "wickedwitch.west.oz."

An implicit ("domain") member, written "* .west.oz.",means that all principals in the given domain belong to this member. No other forms of wildcarding are allowed: "wickedwitch. * .oz."is invalid, as is "wickedwitch.west.* .". Note that principals in subdomains of the given domain are not included.

A recursive ("group") member, written "@cowards.oz.", refers to another group; all principals that belong to that group are considered to belong here.

Any member may be made negative by prefixing it with a minus sign ('-'). A group may thus contain explicit, implicit, recursive, negative explicit, negative implicit, and negative recursive members.

A principal is considered to belong to a group if it belongs to at least one non-negative group member of the group and belongs to no negative group members.

The nis_ismember( ) function returns TRUE if it can establish that principal belongs to group; otherwise it returns FALSE.

The nis_addmember( ) and nis_removemember( ) functions add or remove a member. They do not check whether the member is valid. The user must have read and modify rights for the group in question.

The nis_creategroup( ) and nis_destroygroup( ) functions create and destroy group objects. The user must have create or destroy rights, respectively, for the groups_dir directory in the appropriate domain. The parameter flags to nis_creategroup( ) is currently unused and should be set to zero.

The nis_print_group_entry( ) function lists a group's members on the standard output.

The nis_verifygroup( ) function returns NIS_SUCCESS if the given group exists, otherwise it returns an error code.

EXAMPLES

Simple Memberships

Given a group sadsouls.oz. with members tinman.oz., lion.oz., and scarecrow.oz., the function call

bool_var = nis_ismember("lion.oz.", "sadsouls.oz.");

will return 1 (TRUE) and the function call

bool_var = nis_ismember("toto.oz.", "sadsouls.oz.");

will return 0 (FALSE).

Implicit Memberships

Given a group baddies.oz., with members wickedwitch.west.oz. and * .monkeys.west.oz., the function call

        bool_var = nis_ismember("hogan.monkeys.west.oz.", "baddies.oz.");
will return 1 (TRUE) because any principal from the monkeys.west.oz. domain belongs
to the implicit group * .monkeys.west.oz., but the function call
        bool_var = nis_ismember("hogan.big.monkeys.west.oz.", "baddies.oz.");

will return 0 (FALSE).

Recursive Memberships

Given a group goodandbad.oz., with members toto.kansas, @sadsouls.oz., and @baddies.oz., and the groups sadsouls.oz. and baddies.oz. defined above, the function call

bool_var = nis_ismember("wickedwitch.west.oz.", "goodandbad.oz.");

will return 1 (TRUE), because wickedwitch.west.oz. is a member of the baddies.oz. group which is recursively included in the goodandbad.oz. group.

SEE ALSO

nisgrpadm(1), nis_objects(3N)

NOTES

These functions only accept fully-qualified NIS+ names.

A group is represented by a NIS+ object (see nis_objects(3N)) with a variant part that is defined in the group_obj structure. It contains the following fields:

u_long

gr_flags;

/* Interpretation Flags

(currently unused) * /

struct {
     u_int      gr_members_len;
     nis_name * gr_members_val;
} gr_members;                       /* Array of members * /

NIS+ servers and clients maintain a local cache of expanded groups to enhance their performance when checking for group membership. Should the membership of a group change, servers and clients with that group cached will not see the change until either the group cache has expired or it is explicitly flushed. A server's cache may be flushed programmatically by calling the nis_servstate( ) function with tag TAG_GCACHE and a value of 1.

There are currently no known methods for nis_ismember( ), nis_print_group_entry( ), and nis_verifygroup( ) to get their answers from only the master server.