ypclnt(3N) ypclnt(3N)NAME yp_bind, yp_unbind, yp_get_default_domain, yp_match, yp_first, yp_next, yp_all, yp_order, yp_master, yperr_string, ypprot_err - provide a Network Information Service (NIS) client interface SYNOPSIS #include <rpcsvc/ypclnt.h> yp_bind(indomain); char *indomain; void yp_unbind(indomain) char *indomain; yp_get_default_domain(outdomain); char **outdomain; yp_match(indomain, inmap, inkey, inkeylen, outval, outvallen) char *indomain; char *inmap; char *inkey; int inkeylen; char **outval; int *outvallen; yp_first(indomain, inmap, outkey, outkeylen, outval, outvallen) char *indomain; char *inmap; char **outkey; int *outkeylen; char **outval; int *outvallen; yp_next(indomain, inmap, inkey, inkeylen, outkey, outkeylen, outval, outvallen); char *indomain; char *inmap; char *inkey; int inkeylen; char **outkey; int *outkeylen; char **outval; int *outvallen; yp_all(indomain, inmap, incallback); char *indomain; char *inmap; struct ypall_callback incallback; January 1992 1
ypclnt(3N) ypclnt(3N)yp_order(indomain, inmap, outorder); char *indomain; char *inmap; int *outorder; yp_master(indomain, inmap, outname); char *indomain; char *inmap; char **outname; char *yperr_string(incode) int incode; ypprot_err(incode) unsigned int incode; DESCRIPTION This package of functions provides an interface to the Network Information Service (NIS) network lookup service (formerly called ``Yellow Pages''). The package can be loaded from the standard library /lib/libc.a. Refer to ypfiles(4) and ypserv(1M) for an overview of NIS, including the definitions of map and domain, and a description of the various servers, databases, and commands that make up NIS. All input parameters names begin with in. Output parameters begin with out. Output parameters of type char ** should be addresses of uninitialized character pointers. The NIS client package uses malloc(3) to allocate memory; memory can be freed if the user code has no continuing need for it. For each outkey and outval arguments, two extra bytes of memory are allocated at the end of the arguments that contain the newline and null characters, respectively. These two bytes are not reflected in outkeylen or outvallen. indomain and inmap strings must be non-null and null- terminated. String parameters that are accompanied by a count parameter cannot be null, but can point to null strings, with the count parameter indicating this fact. Counted strings need not be null-terminated. All functions in this package of type int return 0 if they succeed, and a failure code (YPERR_xxxx) otherwise. Failure codes are described in the ``Status Messages and Values'' section later in this manual page. The NIS look-up calls require a map name and a domain name, at minimum. It is assumed that the client process knows the name of the map of interest. Client processes should fetch the node's default domain by calling yp_get_default_domain() and use the returned outdomain as the indomain parameter to successive NIS calls. 2 January 1992
ypclnt(3N) ypclnt(3N)To use NIS, the client process must be ``bound'' to an NIS server that serves the appropriate domain using yp_bind. Binding need not be done explicitly by user code; it is done automatically whenever an NIS lookup function is called. yp_bind can be called directly for processes that make use of a backup strategy (such as a local file) in cases when the NIS is not available. Each binding allocates (uses up) one client process socket descriptor; each bound domain costs one socket descriptor. However, multiple requests to the same domain use that same descriptor. yp_unbind() is available at the client interface for processes that explicitly manage their socket descriptors while accessing multiple domains. The call to yp_unbind() makes the domain ``unbound'' and frees all per- process and per-node resources used to bind it. If a Remote Procedure Call (RPC) failure results upon use of a binding, that domain will be unbound automatically. At that point, the ypclnt layer will retry forever or until the operation succeeds, provided that ypbind is running and either of the following conditions exists: ⊕ The client process cannot bind a server for the proper domain. ⊕ RPC requests to the server fail. If an error is not RPC-related, or if ypbind is not running, or if a bound ypserv process returns any answer (success or failure), the ypclnt layer will return control to the user code, either with an error code or with a success code and any results. yp_match() returns the value associated with a passed key. This key must be exact; no pattern-matching is available. yp_first() returns the first key-value pair from the named map in the named domain. yp_next() returns the next key-value pair in a named map. The inkey parameter should be the outkey value returned from an initial call to yp_first() (to get the second key-value pair) or the one returned from the nth call to yp_next() (to get the nth + second key-value pair). The concept of ``first'' (and, for that matter, of ``next'') is peculiar to the structure of the NIS map being processed; there is no relation in retrieval order to either the lexical order within any original (non-NIS) database, or to any obvious numerical sorting order on the keys, values, or key-value pairs. The only ordering guarantee made is that January 1992 3
ypclnt(3N) ypclnt(3N)if the yp_first() function is called on a particular map, and then the yp_next() function is repeatedly called on the same map at the same server until the call fails with a reason of YPERR_NOMORE, every entry in the database will be seen exactly once. Further, if the same sequence of operations is performed on the same map at the same server, the entries will be seen in the same order. Under conditions of heavy server load or server failure, it is possible for the domain to become unbound, then bound once again (perhaps to a different server) while a client is running. This situation 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 otherwise be returned in the midst of the enumeration. The next paragraph describes a better solution to enumerating all entries in a map. yp_all() provides a way to transfer an entire map from server to client in a single request by using the Transmission Control Protocol (TCP), rather than the User Datagram Protocol (UDP) as with other functions in this package. The entire transaction takes place as a single RPC request and response. You can use yp_all() just as you would any other NIS procedure, identify the map in the normal manner, and supply the name of a function that will be called to process each key-value pair within the map. You return from the call to yp_all() only when the transaction is completed (successfully or unsuccessfully), or when your foreach function decides that it doesn't want 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 as follows: foreach(instatus, inkey, inkeylen, inval, invallen, indata); int instatus; char *inkey; int inkeylen; char *inval; int invallen; char *indata; The instatus parameter will hold one of the return status values defined in <rpcsvc/yp_prot.h>; either YP_TRUE or an error code. See the description of ypprot_err, later in 4 January 1992
ypclnt(3N) ypclnt(3N)this section, for a function that converts an NIS protocol error code to a ypclnt layer error code. The key and value parameters for foreach are somewhat different from those defined earlier in the ``Synopsis'' section. First, the memory pointed to by the inkey and inval parameters is private to the yp_all function and is overwritten with the arrival of each new key-value pair. It is the responsibility of the foreach function to do something useful with the contents 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 newline-terminated or null-terminated in the map, they won't be here either. The indata parameter is the contents of the incallback->data element passed to yp_all. The data element of the callback structure can be used to share state information between the foreach function and the mainline code. Its use is optional, and no part of the NIS client package inspects its contents; cast it to something useful, or ignore it as you see fit. The foreach function is a Boolean. It should return zero to indicate that it wants to be called again for further received key-value pairs or nonzero to stop the flow of key-value pairs. If foreach returns a nonzero value, it is not called again; the functional value of yp_all is then 0. yp_order returns the order number for a map. yp_master returns the machine name of the master NIS server for a map. yperr_string returns a pointer to an error message string that is null-terminated but contains no period or newline. ypprot_err takes an NIS protocol error code as input and returns a ypclnt layer error code, which can be used in turn as input to yperr_string. STATUS MESSAGES AND VALUES All integer functions return 0 if the requested operation is successful or one of the following errors if the operation fails. #define YPERR_BADARGS 1 /* args to function are bad */ #define YPERR_RPC 2 /* RPC failure - domain has been unbound */ #define YPERR_DOMAIN 3 /* can't bind to server on this domain */ #define YPERR_MAP 4 /* no such map in server's January 1992 5
ypclnt(3N) ypclnt(3N)domain */ #define YPERR_KEY 5 /* no such key in map */ #define YPERR_YPERR 6 /* internal yp server or client error */ #define YPERR_RESRC 7 /* resource allocation failure */ #define YPERR_NOMORE 8 /* no more records in map database */ #define YPERR_PMAP 9 /* can't communicate with portmapper */ #define YPERR_YPBIND 10 /* can't communicate with ypbind */ #define YPERR_YPSERV 11 /* can't communicate with ypserv */ #define YPERR_NODOM 12 /* local domain name not set */ FILES /usr/include/rpcsvc/ypclnt.h Header file /usr/include/rpcsvc/yp_prot.h Header file SEE ALSO ypfiles(4) ypserv(1M) in A/UX System Administrator's Reference 6 January 1992