IPv6Regex

Author(s)

• Chris Warwick

Tags

Regex PowerShell IPv6 IpAddress Network Address rfc4291 rfc5952 rfc3986 rfc4007

Functions

IPv6Regex

Dependencies

This module has no dependencies.

Release Notes

IPv6Regex

Chris Warwick, @cjwarwickps, October 2015

This PowerShell script tests a number of regular expressions that match text representations of IPv6 addresses.  
The script also runs the sample test cases against the [System.Net.IpAddress]::TryParse() method to illustrate
some subtle considerations with address validation.

See the comments at the end of the script file for further detailed notes and references.

Script Structure
----------------

This script is split into four sections:

1. The first section defines an IPv6 regex to the tested against a set of sample addresses. A number of other
Regexs gathered from across the web are also defined here.  
  
2. Following the regex definitions, an array of test script-blocks is defined.  Each script block takes a test
IPv6 address as a parameter and tests this address against a specific regex or against the IpAddress.TryParse()
method.  The script blocks return true if the address is considered valid by the test or false otherwise.

3. The next (largest) section of the script defines sample IPv6 addresses to be tested. There are a large number
of both valid and invalid address representations defined.
  
4. The final section of the script runs the tests. Each test script block is selected in turn and the test
addresses are matched against the script blocks. Each test returns a test result object containing details of the
individual test.  The tests are timed to allow comparison of the performance of each test method (use the -Verbose
switch to view timings).

**NOTE**: The output of this script is most useful as a consolidated report.  Consequently, the script 'breaks the
rules' somewhat by including output formatting.  This behaviour can be changed by specifying the '-NoFormat'
switch parameter to instruct the script to pass test-result objects to the output pipeline (these can then be
formatted or collected as required).


Results
-------

Unsurprisingly, a number of regexs found on the web are invalid (only one is included here, others have been
omitted).  Beware of using random regexs without testing them.

There are some subtleties with the operation of the IpAddress.TestParse() method:

1. The IpAddress.TryParse() methods allow leading zeroes in the IPv4 octets.  This is actually explicitly invalid
in the definition in rfc3986 (apparently some systems(?) use a leading zero to denote an Octal number in the IPv4
Octet).

2. The IpAddress::TryParse method does not accept leading elided-zeroes syntax: ('::....')  if there is only one
group (the first group) of the address mising - although this is valid according to the RFC. So, for example,
::2:3:4:5:6:7 is considered valid by IpAddress.TryParse(), but ::2:3:4:5:6:7:8 isn't

3. The IpAddress.TryParse() method by default accepts IPv4 addresses; these can be qualified by checking the
address against the [System.Net.Sockets.AddressFamily]::InterNetworkV6 type

Compiling regexs is an expensive operation, and even for the relatively large number of tests defined here it can
be seen from the timing information that the investment is not warranted in this case.

Although the IpAddress.TryParse() method has some idiosyncrasies it may be preferred to the regex matching methods
given the complexity of these regexs (IpAddress.TryParse() is probably equally as complex but the at least the
complexity is hidden :-)

Script Help
-----------
````

<#
.SYNOPSIS
  Tests IPv6 Regex patterns against a large number of sample test addresses.
.DESCRIPTION
  This function tests a number of IPv6 regexs against a selection of valid and invalid
  IPv6 addresses to verify that the regexs perform as expected.  The function also tests
  the sample addresses using the [System.Net.IpAddress]::TryParse() method to illustrate
  the performance and conformance of this method.
.NOTES
  The script will time the relative performance of the various regexs; use the -Verbose
  switch to display the timimg information.
.PARAMETER TestName
  If specified, only run tests with names matching this.
.PARAMETER NoFormat
  Provide raw output objects for each test.  The default is to select only failing test
  result objects and to format the resulting output.  Use this parameter if you wish to
  use a different selection or formatting option to the default provided here.
.EXAMPLE
  IPv6Regex
  Run all tests and display those that fail.
.EXAMPLE
  IPv6Regex -Verbose
  Run all tests; additionally display relative performance timings.
.EXAMPLE
  IPv6Regex -TestName 'compiled'
  Only run tests where the test name includes the string 'compiled'.
.EXAMPLE
  IPv6Regex -NoFormat
  Run all tests and output a raw RegexMatchResult object for each test.
.INPUTS
  None
.OUTPUTS
  By default, outputs formated table of failing tests.  Use -NoFormat to output raw objects.
.FUNCTIONALITY
  Test IPv6 Regexs against sample IPv6 Addresses.
.LINK
  https://github.com/ChrisWarwick/IPv6Regex
#>


````


Sample Output
-------------
**Note:** By default the script will only output results of failed tests (use the -NoFormat parameter to change
this behaviour).  As illustrated below, use the -Verbose switch to display relative timing information.

````

PS:\> Import-Module IPv6Regex
PS:\> IPv6Regex -Verbose
VERBOSE:  0 of 470 unique tests failed in   75ms for 'IPv6 Regex'
VERBOSE:  0 of 470 unique tests failed in  174ms for 'Compiled IPv6 Regex'
VERBOSE: 19 of 470 unique tests failed in   88ms for 'Php1'
VERBOSE:  0 of 470 unique tests failed in   98ms for 'RegexBuddy'
VERBOSE:  0 of 470 unique tests failed in  142ms for 'Compiled RegexBuddy'
VERBOSE: 11 of 470 unique tests failed in  120ms for 'Net IpAddress TryParse() Method'
VERBOSE:  8 of 470 unique tests failed in  180ms for 'Qualified Net IpAddress TryParse() Method'
VERBOSE:  0 of 470 unique tests failed in  202ms for 'Aeron Regex'

TestName                                  TestAddress                                   ExpectedResult ActualResult
--------                                  -----------                                   -------------- ------------
Php1                                      ::0:0:0:0:0:0:0                                         True        False
Php1                                      ::0:a:b:c:d:e:f                                         True        False
Php1                                      ::2:3:4:5:6:7:8                                         True        False
Php1                                      ::2222:3333:4444:5555:6666:123.123.123.123              True        False
Php1                                      ::2222:3333:4444:5555:6666:7777:8888                    True        False
Php1                                      :1.2.3.4                                               False         True
Php1                                      :10.0.0.1                                              False         True
Php1                                      :2222:3333:4444:5555:6666:1.2.3.4                      False         True
Php1                                      :3333:4444:5555:6666:1.2.3.4                           False         True
Php1                                      :4444:5555:6666:1.2.3.4                                False         True
Php1                                      :5555:6666:1.2.3.4                                     False         True
Php1                                      :6666:1.2.3.4                                          False         True
Php1                                      0:0:0:0:0:0:0::                                         True        False
Php1                                      0:a:b:c:d:e:f::                                         True        False
Php1                                      1111:2222:3333:4444:5555:6666:00.00.00.00              False         True
Php1                                      1111:2222:3333:4444:5555:6666:000.000.000.000          False         True
Php1                                      1111:2222:3333:4444:5555:6666:7777::                    True        False
Php1                                      a:b:c:d:e:f:0::                                         True        False
Php1                                      fe80:0000:0000:0000:0204:61ff:254.157.241.086          False         True
Net IpAddress TryParse() Method           ::0:0:0:0:0:0:0                                         True        False
Net IpAddress TryParse() Method           ::0:a:b:c:d:e:f                                         True        False
Net IpAddress TryParse() Method           ::2:3:4:5:6:7:8                                         True        False
Net IpAddress TryParse() Method           ::2222:3333:4444:5555:6666:123.123.123.123              True        False
Net IpAddress TryParse() Method           ::2222:3333:4444:5555:6666:7777:8888                    True        False
Net IpAddress TryParse() Method           1.2.3.4                                                False         True
Net IpAddress TryParse() Method           1111                                                   False         True
Net IpAddress TryParse() Method           1111:2222:3333:4444:5555:6666:00.00.00.00              False         True
Net IpAddress TryParse() Method           1111:2222:3333:4444:5555:6666:000.000.000.000          False         True
Net IpAddress TryParse() Method           123                                                    False         True
Net IpAddress TryParse() Method           fe80:0000:0000:0000:0204:61ff:254.157.241.086          False         True
Qualified Net IpAddress TryParse() Method ::0:0:0:0:0:0:0                                         True        False
Qualified Net IpAddress TryParse() Method ::0:a:b:c:d:e:f                                         True        False
Qualified Net IpAddress TryParse() Method ::2:3:4:5:6:7:8                                         True        False
Qualified Net IpAddress TryParse() Method ::2222:3333:4444:5555:6666:123.123.123.123              True        False
Qualified Net IpAddress TryParse() Method ::2222:3333:4444:5555:6666:7777:8888                    True        False
Qualified Net IpAddress TryParse() Method 1111:2222:3333:4444:5555:6666:00.00.00.00              False         True
Qualified Net IpAddress TryParse() Method 1111:2222:3333:4444:5555:6666:000.000.000.000          False         True
Qualified Net IpAddress TryParse() Method fe80:0000:0000:0000:0204:61ff:254.157.241.086          False         True



Version History:

V1.1.1 (This version)
 - Updated inline help and Readme

V1.0 (Original Published Version)
 - Initial release to the PowerShell Gallery and TechNet Script Center

V0.1-0.9 Dev versions