Debugging Ajax’ed JavaScript and jQuery val() calls

June 8, 2017

I develop a web application which displays data in a read-only form, and loads the edit form upon pressing a button

$(function () {
  $(".btnEdit").click(function () {
    $.ajax({
      url: '@Url.Action("Form", new { id = Model.ID })',
      type: 'post'
    });
  });
});

Now I needed to debug the JavaScript code loaded by the call to $.ajax(), but Chrome does not seem to display the loaded response in its tree of Sources.

An answer on SO provided me with the solution: Simply add the line

//# sourceURL=@Url.Action("Form", new { id = Model.ID })

inside a <script> block in the AJAX-loaded HTML. This will add the requested URL under the (no domain) node

chrome ajax js

Now that I have access to the source file, I needed to find all invocations of the jQuery val() function, since I was tracking down a wrong value in an <input>.

Again SO provided a solution, which I added to my code

(function($){
  var originalVal = $.fn.val;
  $.fn.val = function(){
    var selectorPath = $(this).parents().map(function () {return this.tagName;}).get().reverse().join("->");
    console.log("val( #" + $(this).attr("id") + " " + selectorPath + " , " + JSON.stringify(arguments) + ")");
    var result =originalVal.apply(this,arguments);
    return result;
  };
})(jQuery);

Now that the calls to val() were logged to the Console, it was easy to find where the wrong value was set.


Adding SSL Wildcard Certificates to IIS Webs

March 21, 2017

As web browsers start to issue warnings on plain http websites if you are asked to input username/password, it’s time to add SSL certificates even on dev/test servers. We can expect more aggressive warnings in the future 😉

Apparently there is a way to create a self-signed certificate built into IIS (screenshot from Windows Server 2008)

iis create certificate

but this seems to create cerficates only for the host name, not for any domain hosted on the machine.

Back to square one, start up a current Linux machine, and make sure your openssl is newer than version 1.0.1f. (Remember Heartbeed?).

The instructions I found to create self-signed certificates are nearly identical (source, source, source)

openssl genrsa 2048 > my-host.key
openssl req -new -x509 -nodes -sha1 -days 3650 -key my-host.key > my-host.cert
# make sure Common Name starts with "*.", e.g. *.my-host.com
openssl x509 -noout -fingerprint -text < my-host.cert > my-host.info
cat my-host.cert my-host.key > my-host.pem

For use in IIS, you need to create a .pfx from these certificate files:

openssl pkcs12 -inkey my-host.pem -in my-host.cert -export -out my-host.pfx

Copy the .pfx to your IIS machine.

In IIS Manager, select “Server Certificates” on the server node, click “Import…” to import the .pfx certificate.

Start up mmc, “File”, “Add/Remove Snap-in”, select “Certificates”, “Add”, “Computer account”, “Finish”, “OK”, (this click orgy shows you how important certificates were in 2008, as compared to Start/Administrative Tools/Data Sources (ODBC) 😉 ) and find the imported certificate(s) under

Console Root\Certificates\Personal\Certificates

Right-click each of them, select Properties, and make sure that the Friendly Name starts with “*.” for wild-card certificates. Otherwise, you cannot assign a host name for https web sites.

Back in IIS Manager, select each site you want to add https support, click Bindings, Add, select Type: https and select the wild-card SSL certificate. Only if the friendly name starts with *, you can/must set the site’s Host name. Click OK and you are done.

If you want your sites to redirect http to https automatically, make sure the Require SSL box is not checked in the site’s SSL Settings.

The minimal web.config to perform these redirects looks like this (source, source)

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
  <system.webServer>
    <rewrite>
      <rules>
        <rule name="Redirect-HTTP-HTTPS-IIS">
          <match url="(.*)" />
          <conditions>
            <add input="{HTTPS}" pattern="^OFF$" ignoreCase="true" />
          </conditions>
          <action type="Redirect" url="https://{HTTP_HOST}/{R:1}" 
            redirectType="Permanent" />
        </rule>
      </rules>
    </rewrite>
  </system.webServer>
</configuration>

Be aware that while these steps enable https for your IIS sites, self-signed certificates still require the users to explicitly accept the certificates in their browsers, which will raise an “Unknown issuer” warning at their first visit.

Update: There also seems to be a Powershell way to do it 😉


Installing AWStats on Windows Server 2012

March 7, 2017

To install AWStats on Windows, first download the current version from awstats.org. If you don’t have Perl on your machine, get Strawberry Perl for Windows, as ActivePerl requires an annual Business License for production use.

On the server, create a web directory and a data directory for awstats. Follow the steps in the AWStats Setup Guide.

To access the log files of a remote IIS, I created a read-only share on c:\inetpub\LogFiles, and had to run

icacls c:\inetpub\LogFiles /reset /t

to allow non-admin access to the IIS log files.

To get Strawberry Perl to run on IIS, follow this Installation Guide:

  • In the Web Server role, you need to have the CGI feature installed.
  • In IIS Administrator, create a web site or application hosting AWStats. In the site or application, you need to add a Script Map for *.pl executing
C:\path\to\perl.exe "%s" %s

Things should be running by now if you browse to

http://myHost/awstats/cgi-bin/awstats.pl?config=mySite

I noticed that the stats only included data from the installation date (IIS logs are configured to daily log files).

Answers on the internetz suggest to merge old log files using logresolvemerg.pl, a script that ships with awstats.

C:\awstats\tools>perl logresolvemerge.pl [all my log files] > merged.log

Replace the LogFile entry in your config file(s) to point to the merged log file

LogFile="C:\awstats-data\merged.log"
#LogFile="\\path\to\LogFiles\W3SVC1\u_ex%YY-1%MM-1%DD-1.log"

and run

perl awstats.pl -config=mySite

again after deleting the previously generated data files.

Unfortunately, the merged log only resulted in “dropped” and “corrupted” records:

Phase 1 : First bypass old records, searching new record...
Searching new records from beginning of log file...
Jumped lines in file: 0
Parsed lines in file: 30376
Found 16100 dropped records,
Found 0 comments,
Found 0 blank records,
Found 14276 corrupted records,
Found 0 old records,
Found 0 new qualified records.

This may be caused by a number of reasons, but it turned out that the merged log requires a specific LogFormat:

LogFormat="%time2 %other %method %url %query %other %logname %host %ua %code %other %other %other"

Finally, I created a batch file awstats.cmd to update all my statistics

net use z: \\host\LogFiles awstats /user:awstats
d:
cd D:\wwwroot\awstats\wwwroot\cgi-bin
perl awstats.pl -update -config=mySite1
perl awstats.pl -update -config=mySite2
...
net use z: /delete

and created a scheduled task to automatically execute the script every day.


Finding Spammers in hMailServer Log Files

February 4, 2016

hMailServer has a couple of spam protection measures built in, such as DNS blacklists and SURBL support. Among other features, you can also ban single IP adresses or IP ranges from connecting to your mail server.

While recently browsing through the log files, I noticed a couple of IP addresses which repeatedly connected to the mail server to log in, but kept their rate over the default 30 minutes auto-ban timer.

Interestingly those addresses chose to authenticate via AUTH LOGIN, but failed every time to provide a valid password. This results in a

535 Authentication failed

answer by the server, thus closing the conversation.

In the log file, the status code 535 looks like this

"SMTPD" 3228 21101 "2016-02-03 00:05:19.743" "xxx.xx.xx.xxx" 
  "SENT: 535 Authentication failed. Too many invalid logon attempts."

To find the conversations ending in status code 535, we can simply grep or findstr the relevant log files

grep "SENT: 535" *.log

In the log files, IP address is logged in the sixth column, so we can iterate over the resulting lines with the shell’s for command with option /f “tokens=6”.

Then we sort and count

(for /f "tokens=6" %i in ('grep "SENT: 535" *.log') do @echo %i) 
  | sort | uniq -c

To count the resulting IP addresses, I use my tool uniq, implemented after the Unix command uniq.

Similarly, one could also search for “550 Unknown user”.


ASCII(), UNICODE() and the Replacement Character

June 3, 2013

This is a follow-up article on my previous post about string equality and collations.

We know, simply from looking at them, that the characters 'ܐ' and 'አ' are different, but the collation you use may treat them as equal.

Well, we can still compare their code point value by using the UNICODE() function, as in

select unicode(N'ܐ'), unicode(N'አ')

returning 1808 and 4768.

The reason I write this is because I discovered a fallacy in a comment on SO, resulting from mixing Unicode and non-Unicode literals and functions.

Take the statement

select ascii('ܐ'), ascii('አ')

Note that the Unicode characters are not given as Unicode strings (N” notation), but as non-Unicode strings.

Since both characters cannot be mapped onto Latin ASCII (or whatever your collation is), they are replaced by a Replacement Character, which is the question mark ‘?’ in ASCII.

Wikipedia tells us

The question mark character is also often used in place of missing or unknown data. In Unicode, it is encoded at U+003F ? question mark (HTML: ?).

and

In many web browsers and other computer programs, “?” is used to show a character not found in the program’s character set. […] Some fonts will instead use the Unicode Replacement Glyph (U+FFFD, �), which is commonly rendered as a white question mark in a black diamond (see replacement character).

So we can see where the question mark comes from, and thus both functions return 63.

In a similar, but nonetheless different case

select ascii(N'ܐ'), ascii(N'አ')

the characters are defined as Unicode strings, but passed to a function that only accepts non-Unicode strings. In this case, the mapping according to the current collation is performed by the ASCII() function, again resulting in the value 63.

As for the Unicode Replacement Character, you’ll encounter them if you decode a byte array to Unicode, and the decoder encounters a byte sequence that cannot be converted to Unicode given the selected encoding.