Tag Archives: software

Net_DNS2 Version 1.2.1

I’ve released version 1.2.1 of the PEAR Net_DNS2 library- you can install it now through the command line PEAR installer:

pear install Net_DNS2

Or download it directly from the Google Code page here.

This is just a small maintenance release to fix a few bugs:

  • changed the Net_DNS2_Sockets::_sock property from private to protected; this was causing some problems when the request was failing.
  • PHP doesn’t support unsigned integers, but many of the RR’s return unsigned values (like SOA), so there is the possibility that the value will overrun on 32bit systems, and you’ll end up with a negative value. So a new function was added to convert the negative value to a string with the correct unsigned value.

Net_DNS2 Version 1.2.0

I’ve released a new version of the PEAR Net_DNS2 library- you can install it now through the command line PEAR installer:

pear install Net_DNS2

Or download it directly from the Google Code page here.

This release includes a significant speed-up with the local cache by using JSON to encode the cache data, rather then the PHP serialize function. Using JSON loses the class information of the objects, but the data remains the same, and the serialization time is about half.

A Query lookup against Google DNS- NO cache

time: 0.0340800285339

        Net_DNS2_RR_A Object
            [address] =>
            [name] => twitter.com
            [type] => A
            [class] => IN
            [ttl] => 28
            [rdlength] => 4
            [rdata] => 

with cache + serialize

time: 0.00258994102478

        Net_DNS2_RR_A Object
            [address] =>
            [name] => twitter.com
            [type] => A
            [class] => IN
            [ttl] => 28
            [rdlength] => 4
            [rdata] => 

with cache + json

time: 0.00178384780884

        stdClass Object
            [address] =>
            [name] => twitter.com
            [type] => A
            [class] => IN
            [ttl] => 28
            [rdlength] => 4
            [rdata] => 

Version 1.2.0

This version changes the way some exceptions are thrown, and may break your code!

  • added numeric error codes to the Lookups class, and had each method that throws an exception throw a numeric error code along with the message.
  • dropped all references to InvalidArgumentException; we only use the Net_DNS2_Exception from now on.
  • added the CAA, URI, TALINK, CDS and TA resource records. Some of these are experimental, but are pretty straight forward.
  • fixed a bug in formatString(); my version was only putting double quotes around strings that have spaces, but apparently ALL strings should have double quotes around them. This is how BIND does it.
  • re-organized the Net_DNS2_Lookups initialization code; it no longer creates a global object of itself.
  • fixed a bug in the caching code; in some cases it wouldn’t cache the same content more then once.
  • added an option to use JSON to serialize the cache data rather than using the PHP serialize function. JSON is much faster, but loses the class definition, and becomes a stdClass object.
  • fixed a handful of cases where I was using double quotes (“) where a single quote (‘) would be fine.

Net_DNS2 Version 1.1.0

Net_DNS2 version 1.1.0 is now available for download from the PEAR site, or can be installed using the “pear” command line client like:

pear install Net_DNS2

This release includes support for signing DNS updates and zone transfers (AXFR’s) using SIG(0), a private/public key authentication mechanism. The OpenSSL PHP extension is required for this feature to work.

// create a new Updater object
$u = new Net_DNS2_Updater('example.com', array('nameservers' => array('')));

// add a SIG(0) to authenticate the request

// send the update rquest.

Support for the ATMA resource record- a method for publishing ATM addresses via DNS.

@      IN    SOA    name1.data.example.com.  name4.data.example.com. (
                                  1994041800   ; Serial  - date
                                  1800         ; Refresh - 30 minutes
                                  300          ; Retry   - 5 minutes
                                  604800       ; Expire  - 7 days
                                  3600 )       ; Minimum - 1 hour
       IN    NS     name1.data.example.com.
       IN    NS     ns.example.com.

salmon IN    ATMA   39.246f.000e7c9c031200010001.000012345678.00

And a new simple local cache system, using shared memory (using the PHP Shmop Extension), or using a flat file.

$r = new Net_DNS2_Resolver(array(

        'cache_type'    => 'shared',
        'cache_file'    => '/tmp/net_dns2.cache',
        'cache_size'    => 100000

Caching is disabled by default, and is only used for DNS queries (and not for updates), but can drastically improve query performance.

For more details, see the Net_DNS2 Google Code Page.

Automatic Dial Resource Fail-over in Asterisk

Asterisk is generally pretty reliable, but termination providers aren’t always so good; in a market where anybody can re-sell an upstream provider, or setup a few Asterisk boxes and start routing calls for people, it’s generally a good idea to have a “backup” provider (or three) to route your calls through.

You can easily setup an Asterisk system, to fail-over to secondary systems, if your primary provider fails for some reason- and this can all be done right in the dial plan, using a simple MACRO.

Add this MACRO to your dial plan:

exten => s,1,Set(CALL_ATTEMPT=1)
exten => s,3,Dial(${TERM_PROVIDER}/${ARG1},60)
exten => s,4,GotoIf($["${CALL_ATTEMPT}" >= "${MAX_PROVIDERS}"]?s-CANCEL,1)
exten => s,5,Set(CALL_ATTEMPT=$[${CALL_ATTEMPT} + 1])
exten => s,6,Goto(s-${DIALSTATUS},1)

exten => s-BUSY,1,Noop()
exten => s-NOANSWER,1,Noop()
exten => s-CANCEL,1,Hangup()
exten => s-HANGUP,1,Hangup()

exten => s-CHANUNAVAIL,2,Goto(s,3)

exten => s-CONGESTION,2,Goto(s,3)

Now you’ll need to route your calls into this MACRO; this can vary by dial plan, as you may have a special configuration for different area codes, or country codes, or based on some least-cost-routing business decisions, but a simple example would be something like this:

exten => _1NXXNXXXXXX,1,Answer()
exten => _1NXXNXXXXXX,2,Macro(direct-dial,${EXTEN})
exten => _1NXXNXXXXXX,3,Hangup()

This routes any NANPA numbers through the direct-dial MACRO above, passing in the phone number as the first argument to the MACRO.

Now, before this will work, you’ll need to configure some variables; this can be done in many places- in my working configuration, I have these variables dynamically generated via an AGI script, based on the phone number being dialed. This way I can control dial-groups, by phone number, based on a cost/preference/etc.

In this example, we’ll simply set these values in the globals section of the extensions.conf file:

TERM_PROVIDER1 = SIP/first_provider
TERM_PROVIDER2 = IAX/second_provider
TERM_PROVIDER3 = SIP/last_provider

So I’ve configured three fictitious termination providers; you can specify as many as you like, as long as the TERM_PROVIDER increments one for each, and you set the MAX_PROVIDERS value to the total number of providers listed.

This is obviously more useful if this list is automatically generated somehow, or changed based on the phone number being dialed, otherwise the retries could simply be hard-coded into the dial plan.

Now when you dial your number, it will start with the first (default) provider; if the dial() function returns a congestion or channel un-available error, the MACRO will cycle to the next provider, until it as gone through all of the providers listed.