We have done two new releases of Halon since last time we updated the blog with release matters. In Halon 4.1 “teamy”, released just before this summer, we introduced modules. A month later we followed up with 4.2 “classy” that added proper object orientation to the language (which works great in combination with modules). It spawned a few rewrites of our script examples (modules) to reflect this awesomeness. We initially added instance and class methods and variables (static), and in 4.3 “cody” we added the private keyword to functions and variables as well.

class HelloWorld
{
	private $name = "Dr Who?";
	constructor($name)
	{
		$this->name = $name;
	}
	function sayHello()
	{
		return "Hello ".$this->name";
	}
	static function ...()
	{
		...
	}
}

We’ve created a lot of modules and script examples. Some of those, such as the PostgreSQL and MongoDB modules, rely heavily on byte packed data structures. In order to better support those, we’ve added built-in functions such as pack() and unpack(). Upcoming modules and rewrites will also benefit from the new TLSSocket() class.

Here are some new additions to our module collection:

• PostgreSQL
• MongoDB
• Redis
• Memcached
• SMTP client
• spamd client (spamc)
• Milter client
• URL rewrite

Other notable features from the changelog includes

• FreeBSD 11.1 and new quarterly packages
• sha2 hash functions
• Added status and NDR codes to Reject, Defer and Deliver functions
• SetTLS support CA name verification
• DLP engine now support file hashes of SHA2-256 and SHA2-512
• Added $sourceip variable to post-delivery script to easily determine which IP address that was used to send the mail

Geek out corner

One major change that only we can see and fully appreciate is the (both automated and manual) code migration to C++11 (and forward), using the truly awesome clang-tidy tool.

On another note; while we researched pack and unpack implementations by looking at other languages’ documentation (such as PHP, Perl and Python), we found a bug in PHP, which was fixed in 7.2, and backported to 7.1.9. The overall consensus of syntax and conventions amongst languages regarding how pack and unpack should work seems to reflect and mimic Perl.

Some scripting languages like JavaScript and HSL has the notion of class constructors but no destructors. The HSL memory model uses references counted automatic garbage collection to determine when objects should be removed.

“In a language with an automatic garbage collection mechanism, it would be difficult to deterministically ensure the invocation of a destructor, and hence these languages are generally considered unsuitable for RAII [Resource Acquisition Is Initialization]” – Wikipedia on destructors

MongoDB does unlike many other databases use little endian and not big endian (network byte order) in its wire protocol. This will let you send and receive data structures in native machine endian (for most people) since both x86 and amd64 use this convention. I highly recommend reading up on the fun historic trivia about endianness.

Want more in-depth info on the new releases? Get in touch with the support team.