NDB(2) NDB(2)
NAME
ndbopen, ndbcat, ndbclose, ndbreopen, ndbsearch, ndbsnext,
ndbgetval, ndbfree, ipattr, ndbipinfo, csipinfo, ndbhash,
ndbparse, csgetval, ndblookval, dnsquery - 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)
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)
Ndbtuple* ndbgetval(Ndb *db, Ndbs *s, char *attr, char
*val,
char *rattr, char *buf)
Ndbtuple* csgetval(char *netroot, char *attr, char *val,
char *rattr, char *buf)
void ndbfree(Ndbtuple *db)
char* ipattr(char *name)
Ndbtuple* ndbipinfo(Ndb *db, char *attr, char *val, char
**attrs,
int nattr)
Ndbtuple* csipinfo(char *netroot, char *attr, char *val,
char **attrs,
int nattr)
ulong ndbhash(char *val, int hlen)
Ndbtuple* ndbparse(Ndb *db)
Ndbtuple* dnsquery(char *netroot, char *domainname, char
*type)
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Ndbtuple* ndblookval(Ndbtuple *entry, Ndbtuple *line, char
*attr, char *to)
DESCRIPTION
These routines are used by network administrative programs
to search the network database. They operate on the data-
base files described in ndb(6).
Ndbopen opens the database file and calls malloc(2) to allo-
cate a buffer 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 con-
taining 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 successful search both return a
linked list of Ndbtuple structures acquired by malloc(2)
that represent the attribute/value pairs in the entry. On
failure they return zero.
typedef struct Ndbtuple Ndbtuple;
struct Ndbtuple {
char attr[Ndbalen];
char val[Ndbvlen];
Ndbtuple *entry;
Ndbtuple *line;
ulong ptr; /* for the application; starts 0 */
};
The entry pointers chain together all pairs in the entry in
a null-terminated list. The line pointers chain together
all pairs on the same line in a circular list. Thus, a pro-
gram 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 information used by ndbsnext to link suc-
cessive searches. The structure Ndbs looks like:
typedef struct Ndbs Ndbs;
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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 ndbsearch or ndbsnext.
Ndbgetval 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 copies the value
associated with rattr into buf. Buf must point to an area at
least Ndbvlen long. Csgetval is like ndbgetval but queries
the connection server instead of looking directly at the
database. It's first argument specifies the network root to
use. If the argument is 0, it defaults to "/net".
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 corresponds to:
dom domain name
ip Internet number
sys system name
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 attribute/value
pair, attr=val. Ndbipinfo returns a list of tuples whose
attributes match the attributes in the n element array
attrs. For example, consider the following database entries
describing a network, a subnetwork, and a system.
ipnet=big ip=10.0.0.0 ipsubmask=255.255.255.0
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)
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will return the tuples bootf=/386/9pc, smtp=smtp1.big.com,
and dns=dns.big.com.
Csipinfo is to ndbipinfo as csgetval is to ndbgetval.
The last three calls are used by programs that create the
hash tables 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 sequential entries
in the database file. A zero is returned at end of file.
Dnsquery submits a query about domainname to the ndb/dns
mounted at netroot/dns. It returns a linked list of
Ndbtuple's representing a single database entry. The tuples
are logicly arranged into lines using the line fieldin the
structure. The possible type's of query are and the
attributes on each returned tuple line is:
ip find the IP addresses. Returns domain name (dom) and
ip address (ip)
mx look up the mail exchangers. Returns preference (pref)
and exchanger (mx)
ptr do a reverse query. Here domainname must be an ASCII
IP address. Returns reverse name (ptr) and domain name
(dom)
cname
get the system that this name is a nickname for.
Returns the nickname (dom) and the real name (cname)
soa return the start of area record for this field.
Returns area name (dom), primary name server (ns),
serial number (serial), refresh time in seconds
(refresh), retry time in seconds (retry), expiration
time in seconds (expire), and minimum time to lie
(ttl).
ns name servers. Returns domain name (dom) and name
server (ns)
Ndblookval searches entry for the tuple with attribute attr,
copies the value into to, and returns 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.
FILES
/lib/ndb directory of network database files
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SOURCE
/sys/src/libndb
SEE ALSO
ndb(6) ndb(8)
DIAGNOSTICS
These routines set errstr.
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