正则表达式匹配除字符以外的所有内容

Question

I have a payload that contains the following:

\\ p a t r i c k - t e s t - f i l e . t x t x SMB2

I'm looking to extract the file name of patrick-test-file.txt

I can get close by using this, but it continues to include everything (including ascii characters)

[\\\\](.*?)x�SMB2

With a result of this: p a t r i c k - t e s t - f i l e . t x t for the capture group.

How would I just match the characters of the file name, which could be anything of variable length, and could contain alphanumeric characters? Is this possible with pure regex?

Any help is much appreciated.

Answer 1

Sometimes you just can't do a single language-agnostic Regular Expression to accomplish something. And sometimes (usually) it is more performant to do a series of string functions.

I wouldn't personally accept any solution which has hard-coded values, such as x SMB2 .

If you want to use Regular Expressions only, you can first select the File-Name portion like so: (([-\\w\\d.\\\\]+)[^-\\w\\d.\\\\]?)+ , then go ahead and replace [^-\\w\\d.\\\\] with nothing "" .

Honestly, given the limited detail, the best function is like so:

var fileName = "\patrick-test-file.txt";

But half-joking aside, and with that limited detail, your best bet is to do a couple string functions:

var yuckyString = @"����\�p�a�t�r�i�c�k�-�t�e�s�t�-�f�i�l�e�.�t�x�t������x�SMB2";
var fileNameArea = yuckyString.Split(new[] { "��" }, StringSplitOptions.RemoveEmptyEntries)[0];
var fileName = fileNameArea.Replace("�", "");

Granted, there was no language listed, so I'm using C#. Also, the answer would change if there were irregularities with those special characters. With the limited info, the pattern seems clear.