This version of BIND 9 "exports" its internal libraries so
that they can be used by third-party applications more easily (we
call them "export" libraries in this document). Certain library
functions are altered from specific BIND-only behavior to more generic
behavior when used by other applications; to enable this generic behavior,
the calling program initializes the libraries by calling
isc_lib_register().
In addition to DNS-related APIs that are used within BIND 9, the
libraries provide the following features:
$ make install
Normal installation of BIND also installs library object
and header files. Root privilege is normally required.
To see how to build a custom application after the installation, see
lib/samples/Makefile-postinstall.in.
The IRS library supports an "advanced" configuration file related to
the DNS library, for configuration parameters that would be beyond the
capability of the resolv.conf file.
Specifically, it is intended to provide DNSSEC-related configuration
parameters. By default the path to this configuration file is
/etc/dns.conf. This module is very experimental
and the configuration syntax or library interfaces may change in
future versions. Currently, only the trusted-keys
statement is supported, whose syntax is the same as the same
statement in named.conf. (See
the section called “trusted-keys Statement Grammar” for details.)
Some sample application programs using this API are provided for
reference. The following is a brief description of these
applications.
sample: a simple stub resolver utility
This sends a query of a given name (of a given optional RR type) to a
specified recursive server and prints the result as a list of RRs.
It can also act as a validating stub resolver if a trust anchor is
given via a set of command-line options.
Usage: sample [options] server_address hostname
Options and Arguments:
- -t RRtype
specifies the RR type of the query. The default is the A RR.
- [-a algorithm] [-e] -k keyname -K keystring
-
specifies a command-line DNS key to validate the answer. For
example, to specify the following DNSKEY of example.com:
example.com. 3600 IN DNSKEY 257 3 5 xxx
specify the options as follows:
-e -k example.com -K "xxx"
-e means that this key is a zone's "key signing key" (also known
as "secure entry point").
When -a is omitted rsasha1 is used by default.
- -s domain:alt_server_address
specifies a separate recursive server address for the specific
"domain". Example: -s example.com:2001:db8::1234
- server_address
is an IP(v4/v6) address of the recursive server to which queries
are sent.
- hostname
is the domain name for the query
sample-async: a simple stub resolver, working asynchronously
This is similar to "sample", but accepts a list
of (query) domain names as a separate file and resolves the names
asynchronously.
Usage: sample-async [-s server_address] [-t RR_type] input_file
Options and Arguments:
- -s server_address
-
is an IPv4 address of the recursive server to which queries are sent.
(IPv6 addresses are not supported in this implementation.)
- -t RR_type
-
specifies the RR type of the queries. The default is the A
RR.
- input_file
-
is a list of domain names to be resolved; each line consists of a
single domain name. For example:
www.example.com
mx.example.net
ns.xxx.example
sample-request: a simple DNS transaction client
sends a query to a specified server, and prints the response with
minimal processing. It does not act as a "stub resolver": it stops
the processing once it gets any response from the server, whether
it's a referral or an alias (CNAME or DNAME) that would require
further queries to get the ultimate answer. In other words, this
utility acts as a very simplified dig.
Usage: sample-request [-t RRtype] server_address hostname
Options and Arguments:
- -t RRtype
specifies the RR type of the queries. The default is the A RR.
- server_address
is an IP(v4/v6) address of the recursive server to which
the query is sent.
- hostname
is the domain name for the query
sample-gai: getaddrinfo() and getnameinfo() test code
is a test program to check getaddrinfo() and
getnameinfo() behavior. It takes a host name as an
argument, calls getaddrinfo() with the given host
name, and calls getnameinfo() with the resulting
IP addresses returned by getaddrinfo(). If the
dns.conf file exists and defines a trust anchor, the underlying
resolver acts as a validating resolver, and
getaddrinfo()/getnameinfo()
fails with an EAI_INSECUREDATA error when DNSSEC validation
fails.
Usage: sample-gai hostname
sample-update: a simple dynamic update client program
accepts a single update command as a command-line argument, sends
an update request message to the authoritative server, and shows
the response from the server. In other words, this is a simplified
nsupdate.
Usage: sample-update [options] (add|delete) "update data"
Options and Arguments:
- -a auth_server
is an IP address of the authoritative server that has authority
for the zone containing the update name. This should
normally be the primary authoritative server that accepts
dynamic updates. It can also be a secondary server that is
configured to forward update requests to the primary server.
- -k keyfile
is a TSIG key file to secure the update transaction. The
keyfile format is the same as that for the nsupdate utility.
- -p prerequisite
is a prerequisite for the update; only one prerequisite can be
specified. The prerequisite format is the same as that
accepted by the nsupdate utility.
- -r recursive_server
is an IP address of a recursive server that this utility
uses. A recursive server may be necessary to identify the
authoritative server address to which the update request is
sent.
- -z zonename
is the domain name of the zone that it contains.
- (add|delete)
specifies the type of update operation. Either "add" or
"delete" must be specified.
- "update data"
specifies the data to be updated. A typical example of the
data looks like "name TTL RRtype RDATA".
Note
In practice, either -a or -r must be specified. Others can be
optional; the underlying library routine tries to identify the
appropriate server and the zone name for the update.
Examples: assuming the primary authoritative server of the
dynamic.example.com zone has an IPv6 address 2001:db8::1234,
$ sample-update -a sample-update -k Kxxx.+nnn+mmmm.key add "foo.dynamic.example.com 30 IN A 192.168.2.1"
adds an A RR for foo.dynamic.example.com using the given key.
$ sample-update -a sample-update -k Kxxx.+nnn+mmmm.key delete "foo.dynamic.example.com 30 IN A"
removes all A RRs for foo.dynamic.example.com using the given key.
$ sample-update -a sample-update -k Kxxx.+nnn+mmmm.key delete "foo.dynamic.example.com"
removes all RRs for foo.dynamic.example.com using the given key.
nsprobe: domain/name server checker in terms of RFC 4074
checks a set of domains to ensure the name servers of the domains
behave correctly in terms of RFC 4074. This is included in the set
of sample programs to show how the export library can be used in a
DNS-related application.
Usage: nsprobe [-d] [-v [-v...]] [-c cache_address] [input_file]
Options
- -d
runs in "debug" mode. With this option, nsprobe dumps
every RR it receives.
- -v
increases verbosity of other normal log messages. This can be
specified multiple times.
- -c cache_address
specifies an IP address of a recursive (caching) name server.
nsprobe uses this server to get the NS RRset of each domain
and the A and/or AAAA RRsets for the name servers. The
default value is 127.0.0.1.
- input_file
is a file name containing a list of domain (zone) names to be
probed. when omitted the standard input is used. Each
line of the input file specifies a single domain name, such as
"example.com". In general, this domain name must be the apex
name of some DNS zone, unlike normal "host names" such as
"www.example.com". nsprobe first identifies the NS RRsets
for the given domain name, and sends A and AAAA queries to
these servers for some widely used names under the zone;
specifically, adding "www" and "ftp" to the zone name.
As of this writing, there is no formal "manual" for the libraries,
except this document, header files (some of which provide pretty
detailed explanations), and sample application programs.