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NDB(3)			   Library Functions Manual			NDB(3)

NAME
       ndbopen,	 ndbcat, ndbchanged, ndbclose, ndbreopen, ndbsearch, ndbsnext,
       ndbgetvalue, ndbfree, ipattr, ndbgetipaddr,  ndbipinfo,	ndbhash,  ndb-
       parse,  ndbfindattr, ndbdiscard,	ndbconcatenate,	ndbreorder, ndbsubsti-
       tute, ndbgetval,	ndblookval - network database

SYNOPSIS
       #include	<u.h>
       #include	<libc.h>
       #include	<bio.h>
       #include	<ndb.h>

       Ndb*	  ndbopen(char *file)

       Ndb*	  ndbcat(Ndb *db1, Ndb *db2)

       Ndb*	  ndbchanged(Ndb *db)

       int	  ndbreopen(Ndb	*db)

       void	  ndbclose(Ndb *db)

       Ndbtuple*  ndbsearch(Ndb	*db, Ndbs *s, char *attr, char *val)

       Ndbtuple*  ndbsnext(Ndbs	*s, char *attr,	char *val)

       char*	  ndbgetvalue(Ndb *db, Ndbs *s,	char *attr, char *val,
		  char *rattr, Ndbtuple	**tp)

       char*	  ipattr(char *name)

       Ndbtuple*  ndbgetipaddr(Ndb *db,	char *sys);

       Ndbtuple*  ndbipinfo(Ndb	*db, char *attr, char *val, char **attrs,
		  int nattr)

       ulong	  ndbhash(char *val, int hlen)

       Ndbtuple*  ndbparse(Ndb *db)

       Ndbtuple*  ndbfindattr(Ndbtuple *entry, Ndbtuple	*line, char *attr)

       void	  ndbfree(Ndbtuple *db)

       Ndbtuple*  ndbdiscard(Ndbtuple  *t, Ndbtuple *a)

       Ndbtuple*  ndbconcatenate(Ndbtuple *a, Ndbtuple *b);

       Ndbtuple*  ndbreorder(Ndbtuple *t, Ndbtuple *a);

       Ndbtuple*  ndbsubstitute(Ndbtuple *t, Ndbtuple *from, Ndbtuple *to);

DESCRIPTION
       These routines are used by network administrative  programs  to	search
       the  network database.  They operate on the database files described in
       ndb(7).

       Ndbopen opens the database file and calls malloc(3) to allocate a  buf-
       fer for it.  If file is zero, all network database files	are opened.

       Ndbcat concatenates two open databases.	Either argument	may be nil.

       Ndbreopen  checks if the	database files associated with db have changed
       and if so throws	out any	cached information and reopens the files.

       Ndbclose	closes any database files associated with  db  and  frees  all
       storage associated with them.

       Ndbsearch  and  ndbsnext	 search	a database for an entry	containing the
       attribute/value pair, attr=val.	Ndbsearch is used to  find  the	 first
       match  and  ndbsnext  is	used to	find each successive match.  On	a suc-
       cessful search both return a linked list	 of  Ndbtuple  structures  ac-
       quired by malloc(3) that	represent the attribute/value pairs in the en-
       try.  On	failure	they return zero.

	      typedef struct Ndbtuple Ndbtuple;
	      struct Ndbtuple {
		      char	attr[Ndbalen];
		      char	*val;
		      Ndbtuple	*entry;
		      Ndbtuple	*line;
		      ulong	ptr;	/* for the application;	starts 0 */
		      char	valbuf[Ndbvlen];  /* initial allocation	for val	*/
	      };

       The entry pointers chain	together all pairs in the entry	in a null-ter-
       minated	list.	The line pointers chain	together all pairs on the same
       line in a circular list.	 Thus, a program can  implement	 2  levels  of
       binding	for pairs in an	entry.	In general, pairs on the same line are
       bound tighter than pairs	on different lines.

       The argument s of ndbsearch has type Ndbs  and  should  be  pointed  to
       valid  storage before calling ndbsearch,	which will fill	it with	infor-
       mation used by ndbsnext to link	successive  searches.	The  structure
       Ndbs looks like:

	      typedef struct Ndbs Ndbs;
	      struct Ndbs {
		      Ndb      *db;   /* data base file	being searched */
		      ...
		      Ndbtuple *t;    /* last attribute	value pair found */
	      };

       The  t  field  points  to the pair within the entry matched by the ndb-
       search or ndbsnext.

       Ndbgetvalue searches the	database for an	entry containing not  only  an
       attribute/value	pair,  attr=val,  but  also  a pair with the attribute
       rattr.  If successful, it returns a malloced copy of  the  null	termi-
       nated value associated with rattr.  If tp is non	nil, *tp will point to
       the entry.  Otherwise the entry will be freeed.

       Ndbfree frees a list of tuples returned by one of the other routines.

       Ipattr takes the	name of	an IP system and returns the attribute it cor-
       responds	to:

	      dom    domain name

	      ip     Internet number

	      sys    system name

       Ndbgetipaddr  looks  in	db for an entry	matching sys as	the value of a
       sys= or dom= attribute/value pair and returns all IP addresses  in  the
       entry.	If  sys	is already an IP address, a tuple containing just that
       address is returned.

       Ndbipinfo looks up Internet protocol information	about a	system.	  This
       is  an IP aware search.	It looks first for information in the system's
       database	entry and then in the database entries for any IP  subnets  or
       networks	containing the system.	The system is identified by the	attri-
       bute/value pair,	attr=val.  Ndbipinfo returns a list  of	 tuples	 whose
       attributes  match the attributes	in the n element array attrs.  For ex-
       ample, consider the following database entries describing a network,  a
       subnetwork, and a system.

       ipnet=big ip=10.0.0.0
		  dns=dns.big.com
		  smtp=smtp.big.com
       ipnet=dept ip=10.1.1.0 ipmask=255.255.255.0
		  smtp=smtp1.big.com
       ip=10.1.1.4 dom=x.big.com
		  bootf=/386/9pc

       Calling

	  ndbipinfo(db,	"dom", "x.big.com", ["bootf" "smtp" "dns"], 3)

       will   return   the   tuples  bootf=/386/9pc,  smtp=smtp1.big.com,  and
       dns=dns.big.com.

       The next	three routines are used	by programs that create	the  hash  ta-
       bles  and  database files.  Ndbhash computes a hash offset into a table
       of length hlen for the string val.  Ndbparse reads and parses the  next
       entry from the database file.  Multiple calls to	ndbparse parse sequen-
       tial entries in the database file.  A zero is returned at end of	file.

       Ndbfindattr searches entry for the tuple	with attribute	attr  and  re-
       turns  a	 pointer to the	tuple.	If line	points to a particular line in
       the entry, the search starts there and then wraps around	to the	begin-
       ning of the entry.

       All  of	the routines provided to search	the database provide an	always
       consistent view of the relevant files.  However,	it may be advantageous
       for an application to read in the whole database	using ndbopen and ndb-
       parse and provide its own search	routines.  The ndbchanged routine  can
       be used by the application to periodicly	check for changes.  It returns
       zero if none of the files comprising the	database have changes and non-
       zero if they have.

       Finally,	a number of routines are provided for manipulating tuples.

       Ndbdiscard  removes  attr/val  pair  a from tuple t and frees it.  If a
       isn't in	t it is	just freed.

       Ndbconcatenate concatenates two tuples and returns the result.	Either
       or both tuples may be nil.

       Ndbreorder reorders a tuple t to	make the line containing attr/val pair
       a first in the entry and	making a first in its line.

       Ndbsubstitute replaces a	single att/val pair from in t with  the	 tuple
       to.  All	attr/val pairs in to end up on the same	line.  from is freed.

FILES
       /usr/local/plan9/ndb
	      directory	of network database files

SOURCE
       /usr/local/plan9/src/libndb

SEE ALSO
       ndb(1) ndb(7)

DIAGNOSTICS
       Ndbgetvalue and ndblookvalue set	errstr to buffer too short if the buf-
       fer provided isn't long enough for the returned value.

BUGS
       Ndbgetval and ndblookval	are deprecated versions	of ndbgetvalue and nd-
       blookvalue.  They expect	a fixed	64 byte	long result buffer and existed
       when the	values of a Ndbtuple structure where fixed length.

									NDB(3)

NAME | SYNOPSIS | DESCRIPTION | FILES | SOURCE | SEE ALSO | DIAGNOSTICS | BUGS

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