Networking Services Library Functions ypclnt(3NSL)
NAME
ypclnt, ypgetdefaultdomain, ypbind, ypunbind, ypmatch,
ypfirst, ypnext, ypall, yporder, ypmaster,
yperrstring, ypproterr - NIS Version 2 client interface
SYNOPSIS
cc [ -flag... ] file... -lnsl [ library...]
#include
#include
int ypbind(char *indomain);
void ypunbind (char *indomain);
int ypgetdefaultdomain(char **outdomain);
int ypmatch(char *indomain, char *inmap, char *inkey, int inkeylen,
char *char **outval, int *outvallen);
int ypfirst(char *indomain, char *inmap, char **outkey, int *outkeylen,
char **outval, int *outvallen);
int ypnext(char *indomain, char *inmap, char *inkey, int *inkeylen,
char **outkey, int *outkeylen, char **outval,
int *outvallen);
int ypall(char *indomain, char *inmap, struct ypallcallback *incallback);
int yporder(char *indomain, char *inmap, unsigned long *outorder);
int ypmaster(char *indomain, char *inmap, char **outname);
char *yperrstring(int incode);
int ypproterr(char *domain);
DESCRIPTION
This package of functions provides an interface to NIS, Net-
work Information Service Version 2, formerly referred to as
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Networking Services Library Functions ypclnt(3NSL)
YP. In this version of SunOS, NIS version 2 is supported
only for compatibility with previous versions. The recom-
mended enterprise level information service is NIS] or NIS
version 3. See NIS](1). The current SunOS supports only the
client interface to NIS version 2. This client interface
will in turn be served either by an existing ypserv process
running on another machine on the network that has an ear-
lier version of SunOS, or by a NIS] server running in "YP-
compatibility mode". See rpc.nisd(1M). The NOTES section in
ypfiles(4) discusses the implications of being an NIS client
of an NIS] server in YP-compatibility mode. For commands
used to access NIS from a client machine, see ypbind(1M),
ypwhich(1), ypmatch(1), and ypcat(1). The package can be
loaded from the standard library, /usr/lib/libnsl.so.1.
All input parameter names begin with in. Output parameters
begin with out. Output parameters of type char ** should be
addresses of uninitialized character pointers. Memory is
allocated by the NIS client package using malloc(3C) and can
be freed by the user code if it has no continuing need for
it. For each outkey and outval, two extra bytes of memory
are allocated at the end that contain NEWLINE and null,
respectively, but these two bytes are not reflected in
outkeylen or outvallen. The indomain and inmap strings must
be non-null and null-terminated. String parameters that are
accompanied by a count parameter may not be null, but they
may point to null strings, with the count parameter indicat-
ing this. Counted strings need not be null-terminated.
All functions in this package of type int return 0 if they
succeed. Otherwise, they return a failure code (YPERxxxx).
Failure codes are described in the ERORS section.
Routines
ypbind() To use the NIS name services, the
client process must be "bound" to
an NIS server that serves the
appropriate domain using
ypbind(). Binding need not be
done explicitly by user code.
Binding is done automatically
whenever an NIS lookup function
is called. The ypbind() function
can be called directly for
processes that make use of a
backup strategy , for example, a
local file in cases when NIS ser-
vices are not available. A pro-
cess should call ypunbind() when
it is finished using NIS in order
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Networking Services Library Functions ypclnt(3NSL)
to free up resources.
ypunbind() Each binding allocates or uses up
one client process socket
descriptor. Each bound domain
costs one socket descriptor. How-
ever, multiple requests to the
same domain use that same
descriptor. The ypunbind() func-
tion is available at the client
interface for processes that
explicitly manage their socket
descriptors while accessing mul-
tiple domains. The call to
ypunbind() makes the domain
unbound, and frees all per-
process and per-node resources
used to bind it.
If an RPC failure results upon
use of a binding, that domain
will be unbound automatically. At
that point, the ypclnt() layer
will retry a few more times or
until the operation succeeds,
provided that rpcbind(1M) and
ypbind(1M) are running, and
either:
o The client process can-
not bind a server for
the proper domain; or
o RPC requests to the
server fail.
Under the following cir-
cumstances, the ypclnt layer will
return control to the user code,
with either an error or success
code and the results:
o If an error is not RPC-
related.
o If rpcbind is not run-
ning.
o If ypbind is not run-
ning.
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Networking Services Library Functions ypclnt(3NSL)
o If a bound ypserv pro-
cess returns any answer
(success or failure).
ypgetdefaultdomain() NIS lookup calls require a map
name and a domain name, at
minimum. The client process
should know the name of the map
of interest. Client processes
fetch the node's default domain
by calling
ypgetdefaultdomain() and use
the returned outdomain as the
indomain parameter to successive
NIS name service calls. The
domain returned is the same as
that returned using the
SISRPCDOMAIN command to the
sysinfo(2) system call. The value
returned in outdomain should not
be freed.
ypmatch() The ypmatch() function returns
the value associated with a
passed key. This key must be
exact because no pattern matching
is available. ypmatch() requires
a full YP map name, such as
hosts.byname, instead of the
nickname hosts.
ypfirst() The ypfirst() function returns
the first key-value pair from the
named map in the named domain.
ypnext() The ypnext() function returns
the next key-value pair in a
named map. The inkey parameter
must be the outkey returned from
an initial call to ypfirst() (to
get the second key-value pair) or
the one returned from the nth
call to ypnext() (to get the nth
] second key-value pair). Simi-
larly, the inkeylen parameter
must be the outkeylen returned
from the earlier ypfirst() or
ypnext() call.
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Networking Services Library Functions ypclnt(3NSL)
The concept of first and next is
particular to the structure of
the NIS map being processed.
Retrieval order is not related to
either the lexical order within
any original (non-NIS name ser-
vice) data base, or to any obvi-
ous numerical sorting order on
the keys, values, or key-value
pairs. The only ordering guaran-
tee is that if the ypfirst()
function is called on a particu-
lar map, and then the ypnext()
function is repeatedly called on
the same map at the same server
until the call fails with a rea-
son of YPERNOMORE, every entry
in the data base is seen exactly
once. Further, if the same
sequence of operations is per-
formed on the same map at the
same server, the entries are seen
in the same order.
Under conditions of heavy server
load or server failure, the
domain can become unbound, then
bound once again (perhaps to a
different server) while a client
is running. This binding can
cause a break in one of the
enumeration rules. Specific
entries may be seen twice by the
client, or not at all. This
approach protects the client from
error messages that would other-
wise be returned in the midst of
the enumeration. For a better
solution to enumerating all
entries in a map, see ypall().
ypall() The ypall() function provides a
way to transfer an entire map
from server to client in a single
request using TCP (rather than
UDP as with other functions in
this package). The entire tran-
saction takes place as a single
RPC request and response. The
ypall() function can be used
just like any other NIS name
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Networking Services Library Functions ypclnt(3NSL)
service procedure to identify the
map in the normal manner and to
supply the name of a function
that will be called to process
each key-value pair within the
map. The call to ypall() returns
only when the transaction is com-
pleted (successfully or unsuc-
cessfully), or the foreach()
function decides that it does not
want to see any more key-value
pairs.
The third parameter to ypall()
is:
struct ypallcallback *incallback {
int (*foreach)();
char *data;
};
The function foreach() is called:
foreach(int instatus, char *inkey,
int inkeylen, char *inval,
int invallen, char *indata);
The instatus parameter holds one
of the return status values
defined in ,
either YPTRUE or an error code.
See ypproterr(), for a function
that converts an NIS name service
protocol error code to a ypclnt
layer error code.
The key and value parameters are
somewhat different than defined
in the synopsis section above.
First, the memory pointed to by
the inkey and inval parameters is
private to the ypall() function,
and is overwritten with the
arrival of each new key-value
pair. The foreach() function must
do something useful with the con-
tents of that memory, but it does
not own the memory itself. Key
and value objects presented to
the foreach() function look
exactly as they do in the
server's map. If they were not
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Networking Services Library Functions ypclnt(3NSL)
NEWLINE-terminated or null-
terminated in the map, they would
not be here either.
The indata parameter is the con-
tents of the incallback->data
element passed to ypall(). The
data element of the callback
structure can be used to share
state information between the
foreach() function and the main-
line code. Its use is optional,
and no part of the NIS client
package inspects its contents;
cast it to something useful, or
ignore it. The foreach() function
is Boolean. It should return 0 to
indicate that it wants to be
called again for further received
key-value pairs, or non-zero to
stop the flow of key-value pairs.
If foreach() returns a non-zero
value, it is not called again.
The functional value of ypall()
is then 0.
yporder() The yporder() function returns
the order number for a map. The
function is not supported if the
ypbind process on the client's
system is bound to an NIS] server
running in "YP-compatibility
mode".
ypmaster() The ypmaster() function returns
the machine name of the master
NIS server for a map.
yperrstring() The yperrstring() function
returns a pointer to an error
message string that is null-
terminated but contains no period
or NEWLINE.
ypproterr() The ypproterr() function takes
an NIS name service protocol
error code as input, and returns
a ypclnt() layer error code,
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Networking Services Library Functions ypclnt(3NSL)
which can be used as an input to
yperrstring().
RETURN VALUES
All integer functions return 0 if the requested operation is
successful, or one of the following errors if the operation
fails:
YPERACES Access violation.
YPERBADARGS The arguments to the function are bad.
YPERBADB The YP database is bad.
YPERBUSY The database is busy.
YPERDOMAIN Cannot bind to server on this domain.
YPERKEY No such key in map.
YPERMAP No such map in server's domain.
YPERNODOM Local domain name not set.
YPERNOMORE No more records in map database.
YPERPMAP Cannot communicate with rpcbind.
YPERESRC Resource allocation failure.
YPERPC RPC failure; domain has been unbound.
YPERYPBIND Cannot communicate with ypbind.
YPERYPER Internal YP server or client error.
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Networking Services Library Functions ypclnt(3NSL)
YPERYPSERV Cannot communicate with ypserv.
YPERVERS YP version mismatch.
FILES
/usr/lib/libnsl.so.1
ATRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
ATRIBUTE TYPE ATRIBUTE VALUE
MT-Level Safe
SEE ALSO
NIS](1), ypcat(1), ypmatch(1), ypwhich(1), rpc.nisd(1M),
rpcbind(1M), ypbind(1M), ypserv(1M), sysinfo(2), malloc(3C),
ypfiles(4), attributes(5)
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