Networking Services Library Functions ypclnt(3NSL)
NAME
ypclnt, yp_get_default_domain, yp_bind, yp_unbind, yp_match,
yp_first, yp_next, yp_all, yp_order, yp_master,
yperr_string, ypprot_err - NIS Version 2 client interface
SYNOPSIS
cc [ -flag... ] file... -lnsl [ library...]
#include
#include
int yp_bind(char *indomain);
void yp_unbind (char *indomain);
int yp_get_default_domain(char **outdomain);
int yp_match(char *indomain, char *inmap, char *inkey, int inkeylen,
char *char **outval, int *outvallen);int yp_first(char *indomain, char *inmap, char **outkey, int *outkeylen,
char **outval, int *outvallen);int yp_next(char *indomain, char *inmap, char *inkey, int *inkeylen,
char **outkey, int *outkeylen, char **outval, int *outvallen);int yp_all(char *indomain, char *inmap, struct ypall_callback *incallback);
int yp_order(char *indomain, char *inmap, unsigned long *outorder);
int yp_master(char *indomain, char *inmap, char **outname);
char *yperr_string(int incode);
int ypprot_err(char *domain);
DESCRIPTION
This package of functions provides an interface to NIS, Net-
work Information Service Version 2, formerly referred to asSunOS 5.11 Last change: 10 Dec 2009 1
Networking Services Library Functions ypclnt(3NSL) YP. In this version of SunOS, NIS version 2 is supported only for compatibility with previous versions. The current SunOS supports the client interface to NIS version 2. Thisclient interface will be served by an existing ypserv pro-
cess running on another machine on the network. 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 mustbe non-null and null-terminated. String parameters that are
accompanied by a count parameter may not be null, but theymay 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 theysucceed. Otherwise, they return a failure code (YPERR_xxxx).
Failure codes are described in the ERRORS section.
Routinesyp_bind() To use the NIS name services, the
client process must be "bound" to an NIS server that serves the appropriate domain usingyp_bind(). Binding need not be
done explicitly by user code. Binding is done automatically whenever an NIS lookup functionis called. The yp_bind() function
can be called directly for processes that make use of a backup strategy , for example, alocal file in cases when NIS ser-
vices are not available. A pro-
cess should call yp_unbind() when
it is finished using NIS in order to free up resources.yp_unbind() Each binding allocates or uses up
one client process socket descriptor. Each bound domainSunOS 5.11 Last change: 10 Dec 2009 2
Networking Services Library Functions ypclnt(3NSL)costs one socket descriptor. How-
ever, multiple requests to the same domain use that samedescriptor. The yp_unbind() func-
tion is available at the client interface for processes that explicitly manage their socketdescriptors while accessing mul-
tiple domains. The call toyp_unbind() 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.o If a bound ypserv pro-
cess returns any answer (success or failure).SunOS 5.11 Last change: 10 Dec 2009 3
Networking Services Library Functions ypclnt(3NSL)yp_get_default_domain() 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 callingyp_get_default_domain() 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 theSI_SRPC_DOMAIN command to the
sysinfo(2) system call. The value returned in outdomain should not be freed.yp_match() The yp_match() function returns
the value associated with a passed key. This key must be exact because no pattern matchingis available. yp_match() requires
a full YP map name, such as hosts.byname, instead of the nickname hosts.yp_first() The yp_first() function returns
the first key-value pair from the
named map in the named domain.yp_next() The yp_next() function returns
the next key-value pair in a
named map. The inkey parameter must be the outkey returned froman initial call to yp_first() (to
get the second key-value pair) or
the one returned from the nthcall to yp_next() (to get the nth
+ second key-value pair). Simi-
larly, the inkeylen parameter must be the outkeylen returnedfrom the earlier yp_first() or
yp_next() call.
The concept of first and next is particular to the structure of the NIS map being processed. Retrieval order is not related toSunOS 5.11 Last change: 10 Dec 2009 4
Networking Services Library Functions ypclnt(3NSL) either the lexical order withinany original (non-NIS name ser-
vice) data base, or to any obvi-
ous numerical sorting order onthe keys, values, or key-value
pairs. The only ordering guaran-
tee is that if the yp_first()
function is called on a particu-
lar map, and then the yp_next()
function is repeatedly called on the same map at the same serveruntil the call fails with a rea-
son of YPERR_NOMORE, every entry
in the data base is seen exactly once. Further, if the samesequence 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 fromerror messages that would other-
wise be returned in the midst of the enumeration. For a better solution to enumerating allentries in a map, see yp_all().
yp_all() The yp_all() 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 inthis package). The entire tran-
saction takes place as a single RPC request and response. Theyp_all() function can be used
just like any other NIS name ser-
vice procedure to identify the map in the normal manner and to supply the name of a function that will be called to processSunOS 5.11 Last change: 10 Dec 2009 5
Networking Services Library Functions ypclnt(3NSL)each key-value pair within the
map. The call to yp_all() returns
only when the transaction is com-
pleted (successfully or unsuc-
cessfully), or the foreach() function decides that it does notwant to see any more key-value
pairs.The third parameter to yp_all()
is:struct ypall_callback *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 valuesdefined in
, either YP_TRUE or an error code.
See ypprot_err(), 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 isprivate to the yp_all() function,
and is overwritten with thearrival of each new key-value
pair. The foreach() function mustdo 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 notNEWLINE-terminated or null-
terminated in the map, they would not be here either.SunOS 5.11 Last change: 10 Dec 2009 6
Networking Services Library Functions ypclnt(3NSL)The indata parameter is the con-
tents of the incallback->data
element passed to yp_all(). The
data element of the callback structure can be used to share state information between theforeach() 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 receivedkey-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 yp_all()
is then 0.yp_order() The yp_order() function returns
the order number for a map.yp_master() The yp_master() function returns
the machine name of the master NIS server for a map.yperr_string() The yperr_string() function
returns a pointer to an errormessage string that is null-
terminated but contains no period or NEWLINE.ypprot_err() The ypprot_err() function takes
an NIS name service protocol error code as input, and returns a ypclnt() layer error code, which can be used as an input toyperr_string().
RETURN VALUES
All integer functions return 0 if the requested operation is successful, or one of the following errors if the operation fails:SunOS 5.11 Last change: 10 Dec 2009 7
Networking Services Library Functions ypclnt(3NSL)YPERR_ACCESS Access violation.
YPERR_BADARGS The arguments to the function are bad.
YPERR_BADDB The YP database is bad.
YPERR_BUSY The database is busy.
YPERR_DOMAIN Cannot bind to server on this domain.
YPERR_KEY No such key in map.
YPERR_MAP No such map in server's domain.
YPERR_NODOM Local domain name not set.
YPERR_NOMORE No more records in map database.
YPERR_PMAP Cannot communicate with rpcbind.
YPERR_RESRC Resource allocation failure.
YPERR_RPC RPC failure; domain has been unbound.
YPERR_YPBIND Cannot communicate with ypbind.
YPERR_YPERR Internal YP server or client error.
YPERR_YPSERV Cannot communicate with ypserv.
YPERR_VERS YP version mismatch.
FILES /usr/lib/libnsl.so.1SunOS 5.11 Last change: 10 Dec 2009 8
Networking Services Library Functions ypclnt(3NSL)ATTRIBUTES
See attributes(5) for descriptions of the following attri-
butes:____________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|_____________________________|_____________________________|
| MT-Level | Safe |
|_____________________________|_____________________________|
SEE ALSO
ypcat(1), ypmatch(1), ypwhich(1), rpcbind(1M), ypbind(1M),ypserv(1M), sysinfo(2), malloc(3C), ypfiles(4), attri-
butes(5)SunOS 5.11 Last change: 10 Dec 2009 9