Category: Coding

VSCode Search/Replace Using Regex Capture Groups

Regex adds a lot of flexibility to search/replace operations. Capture groups allow you to manipulate the found data in the replacement text. As an example, I have simple mathematical equations that are not spaced out reasonably. I could replace “+” with ” + “, “-” with ” – “, “*” with ” * “, “/” with ” / “, and “=” with ” = “, but using a capture group to identify non-whitespace characters and the range of operators allows a single search/replace operation to add spaces to my equations.

Selecting the regex option (in blue below), I can use the regular expression (\S+)([\+,\-,\*,\/])(\S+)=(\S+) as my search string. This means the first capture group is one or more non-whitespace characters, the second capture group is one of the characters +,-,*,/, the third capture group is one or more non-whitespace characters, there’s an equal sign (which I could make into a fourth capture group), and the fourth capture group is one or more non-whitespace characters.

An alternate regex finds zero or more whitespace characters — (\S*)([\+,\-,\*,\/])(\S*)=(\S*)

The replacement text then uses each capture group — $1 $2 $3 = $4 — to add spaces around the operators and around the equal sign.

 

Updating JQuery

We’ve got to upgrade some Javascript modules at work — JQuery, Bootstrap, etc. Problem is that changes between the versions mean there’s a lot of rewriting required before we can update. And we pull in these modules using a shared header file. While we could stage all of the changes and update the entire website at once … that means we’re all dedicated to updating our components & are delaying the update until we’re finished.

That’s not ideal — and has the potential to break a lot of things at once. I plan, instead, of putting a default version in the shared header file. And some mechanism to source in a newer version by setting a variable in the individual tool’s PHP code before the header is pulled in. So each tool within the site has a $strJQueryRev, $strBootstrapRev, etc variable. Then the shared header file looks for that variable — loads a newer version when requested or loads the currently used older version when no version is indicated.

if($strJQueryRev == "3.5.1"){
 echo "<script src=\"https://code.jquery.com/jquery-3.5.1.min.js\">\n";   
}
elseif($strJQueryRev == "3.1.1"){
 echo "<script src=\"https://code.jquery.com/jquery-3.1.1.min.js\">\n";   
}
else{
 echo "<script src=\"https://code.jquery.com/jquery-2.2.4.min.js\">\n";        # Old, in use, version is default
}

Or even

if(!$strRevisionNumber){$strRevisionNumber="2.2.4";}
echo "<script src=\"https://code.jquery.com/jquery-$strRevisionNumber.min.js\">

Each developer can add a version number to a single tool, test it, push it up through production using the newest modules. Move on to the next tool. The site still isn’t done until we’re all done, but we can slowly roll out the update as people are able to test their tools.

Cyberark — Error Listing Accounts

I was getting an odd error from my attempt to list accounts in Cyberark — “Object reference not set to an instance of an object”. Searching the Internet yielded a lot of issues that weren’t my problem (ampersands in account names in an older version, issues with SSL {and, seriously, someone says disable SSL on the connection they use to retrieve passwords!?! And not just random someone, but RAND?!?}). My issue turned out to be that I was copy/pasting code and used requests.post instead of requests.get — attempting to POST to a GET URL generates this error too.

DEBUG:urllib3.connectionpool:Starting new HTTPS connection (1): cyberark.example.com:443
DEBUG:urllib3.connectionpool:https://cyberark.example.com:443 “POST /PasswordVault/API/auth/Cyberark/Logon HTTP/1.1” 200 182
Before request, header is {‘Content-Type’: ‘application/json’, ‘Authorization’: ‘5TQz5WVjYm5tMjBh5C00M5YyLT50MjYt5Tc2Y5I2ZDI5…AwMDA5MDA7’}
DEBUG:urllib3.connectionpool:Starting new HTTPS connection (1): cyberark.example.com:443
DEBUG:urllib3.connectionpool:https://cyberark.example.com:443 “POST /PasswordVault/api/Accounts?search=sample_account&searchType=contains HTTP/1.1” 500 97
{“ErrorCode”:”CAWS00001E”,”ErrorMessage”:”Object reference not set to an instance of an object.”} 500 Internal Server Error

Python Time-Expiring Cache

I needed to post information into a SharePoint Online list. There’s an auth header required to post data, but the authentication expires every couple of minutes. Obviously, I could just get a new auth string each time … but that’s terribly inefficient. I could also use what I had and refresh it when it fails … inelegant but effective. I wanted, instead, to have a value cached for a duration slightly less than the server-side expiry on the auth string. This decorator allows me to use the cached auth header string for some period of time and actually run the function that grabs the auth header string before the string is invalidated.

import functools
import time
from datetime import datetime

def timed_cache(iMaxAge, iMaxSize=128, boolTyped=False):
    #######################################
    # LRU cache decorator with expiry time
    #
    # Args:
    #    iMaxAge: Seconds to live for cached results. 
    #    iMaxSize: Maximum cache size (see functools.lru_cache).
    #    boolTyped: Cache on distinct input types (see functools.lru_cache).
    #######################################
    def _decorator(fn):
        @functools.lru_cache(maxsize=iMaxSize, typed=boolTyped)
        def _new(*args, __time_salt, **kwargs):
            return fn(*args, **kwargs)

        @functools.wraps(fn)
        def _wrapped(*args, **kwargs):
            return _new(*args, **kwargs, __time_salt=int(time.time() / iMaxAge))
        return _wrapped

    return _decorator

# Usage example -- 23 second cache expiry
@timed_cache(23)
def slow_function(iSleepTime: int):
    datetimeStart = datetime.now()
    time.sleep(iSleepTime)
    return f"test started at {datetimeStart} and ended at at {datetime.now()}"


print(f"Start at {datetime.now()}")

for i in range(1, 50):
    print(slow_function(5))
    
    if i % 5 is 0:
        print(f"sleeping 5 at {datetime.now()}")
        time.sleep(5)
        print(f"done sleeping at {datetime.now()}\n\n")

print(f"Ended at at {datetime.now()}")

VSCode — Shortcut for Uppercase and Lowercase Conversion

While you can run a command to convert the selected text to upper (or lower) case, there doesn’t appear to be a quick way to do it. Luckily, you can define your own keyboard shortcuts and map those shortcuts to commands. From the File menu, select “Preferences” and “Keyboard Shortcuts” (or use the Ctrl-K Ctrl-S combo).

In the upper right-hand corner, click this icon to open the custom keyboard shortcut JSON file

Add JSON elements for the shortcuts you want to define — the key combination, the command to run, and on what to run the command

Sample key command bindings:

[
 {
    "key": "ctrl+shift+u",
    "command": "editor.action.transformToUppercase",
    "when": "editorTextFocus"
 },
 {
    "key": "ctrl+shift+l",
    "command": "editor.action.transformToLowercase",
    "when": "editorTextFocus"
 }
]

Save … voila, a keyboard shortcut to change to upper and lower case.

Listing Modules In Dynamically Linked Shared Object Libraries

We had to rebuild a server over the weekend — it’s a lot harder to get Apache and PHP set up when you don’t have root access to just install things from the yum repository. And, unlike the servers where I built httpd and php from source … we basically relayed requests to the Unix admin to have packages installed. One of the confusions during the whole process was that we didn’t know what to use as the module name for PHP to load in the httpd.conf file. The line from our old server (LoadModule php5_module /etc/httpd/modules/libphp5.so) produced an error that there was no such thing to load.

When a library fails to load with some error, I know to use ldd … but I didn’t know there was a way to list out the modules in a library. Fortunately, one of my coworkers had already run nm and listed out the modules — nm -D –defined-only sharedLibraryFile | grep module — and we were able to identify that the libphp5.so that we had wasn’t anything like the one on the old server. By listing the modules for each of the shared object libraries installed by the php package, we got the proper module name for httpd.conf

Dynamically determining AD Page Size

Question — is it possible to dynamically determine the maximum page size when communicating with AD via LDAP? Since the page size (1) changed between versions and (2) can be user-customized … a guess is sub-optimal.

Answer — yes. If only the default query policy is used, search at
CN=Default Query Policy,CN=Query-Policies,CN=Directory Service,CN=Windows NT,CN=Services,CN=Configuration,*domain naming context* (e.g.
CN=Default Query Policy,CN=Query-Policies,CN=Directory Service,CN=Windows NT,CN=Services,CN=Configuration,DC=example,DC=com) with a filter like “(&(cn=*))”

Return the ldapAdminLimits attribute. Parse MaxPageSize out of the attribute:

lDAPAdminLimits (13): MaxValRange=1500; MaxReceiveBuffer=10485760; MaxDatagramRecv=4096; MaxPoolThreads=4; MaxResultSetSize=262144; MaxTempTableSize=10000; MaxQueryDuration=120; **MaxPageSize=1000**; MaxNotificationPerConn=5; MaxActiveQueries=20; MaxConnIdleTime=900; InitRecvTimeout=120; MaxConnections=5000;

To find all of the query policies, search at CN=Query-Policies,CN=Directory Service,CN=Windows NT,CN=Services,CN=Configuration,*domain naming context* for (&(objectClass=queryPolicy)) … either research a lot about query policies and figure out how to determine which applies to your connection or take the lowest value and know you’re safe.

ADO Notifications

I’ve been underwhelmed with the notifications I get from Azure DevOps – there are a lot of build-centric notifications, but I don’t use ADO for builds or deployment apart from playing around. And I really don’t care if the silly test project I set up to build and deploy a website worked, failed, or whatever. I was thinking about hooking whatever they’re calling Flow this week up to ADO and building notification workflows.

Fortunately, a coworker mentioned that you can customize notifications in ADO … which, I’d spent a few seconds poking around and didn’t see anything. But I spent more than a few seconds this time and happened across this little ellipsis on the card that pops up when I click the circle with my initials in it. More options!

A new menu flies out; and, look, there’s “Notifications”

Exactly as I’ve observed, there are a lot of build-centric alerts. So I created a new subscription.

Here’s a subscription that I hope will notify me when items assigned to me have updates to activity or comments.

HTML Checkbox Adding and Removing Table Row

Here’s the JavaScript code I ended up using to add and remove rows from a table based on a checkbox selection (and only allowing one checkbox per group to be selected). The biggest change is that I added a name and ID to my TR for easier identification.

$(document).on("change", "input[type='checkbox']", function () {
    var $objCheckbox = $(this);
    if ($objCheckbox.is(":checked")) {			// When checked, deactivate other checkboxes and add to sets to create table
        var objCheckboxGroup = "input:checkbox[tableselector='" + $objCheckbox.attr("tableselector") + "']";

        $(objCheckboxGroup).prop("disabled", true);
        $objCheckbox.prop("disabled", false);		// Allow checked box to be unchecked

        addSetToCreatingTable($objCheckbox.attr("setname"), $objCheckbox.attr("settype"), $objCheckbox.attr("goodcircuits") + "|" + $objCheckbox.attr("value"), $objCheckbox.attr("tableselector"));

    }
    else {							// When unchecked, active checkboxes and remove from sets to create table
        var objCheckboxGroup = "input:checkbox[name='" + $objCheckbox.attr("name") + "']";
        $(objCheckboxGroup).prop("disabled", false);	

        $("#" + $objCheckbox.attr('tableselector')).each(function(){ $(this).remove();})
}
});