I'm trying to write a regex for x509 CN/SAN validation and have just learned that apparently partial wildcards are possible in theory. How would I build a regex to handle this when I want to make sure that it captures all certificates that might be issued for example.org?
My naive approach would be
\**e\**x\**a\**m\**p\**l\**e\**.\**o\**r\**g\**
not including possible subdomains of course. This looks pretty bad though and really inflates the term longer than I'd like it to be. Is there a more concise way to get the behaviour I described?
Edit: I also just realised that my naive regex wouldn't even catch when someone uses the asterisk to replace a part of the domain, e.g. exa*.org.
Since I feel like there's a possibility that this is not easily expressible in a concise regex, I solved my use case within the Python code that surrounds my previous regex check.
Instead of mapping a regex to the domains appearing in a certificate, I instead convert the certificate domain into a regex pattern, replace the literal dots with escaped dots and the asterisk with [a-zA-Z0-9-]{0,63}. I then compare it to the list of domains I manage and if the regex matches, I know that the certificate is applicable to the managed domain.
If someone manages to express this in a concise regex I'd still be interested.
Related
I'm trying to create a regex for validating URLs. I know there are many advanced ones out there, but I want to create my own for learning purposes.
So far I have a regex that works quite well, however I want to improve the validation for the TLD part of the URI because I feel it's not quite there yet.
Here's my regex (or find it on regexr):
/^[(http(s)?):\/\/(www\.)?a-zA-Z0-9#:._\+~#=]{2,256}\.[a-zA-Z]{2,6}\b([/#?]{0,1}([A-Za-z0-9-._~:?#[\]#!$&''()*+,;=]|(%[A-Fa-f0-9]{2}))*)$/
It works well for links such as foo.com or http://foo.com or foo.co.uk
The problem appears when you introduce subdomains or second-level domains such as co.uk because the regex will accept foo.co.u or foo.co..
I did try using the following to select the substring after the last .:
/[(http(s)?):\/\/(www\.)?a-zA-Z0-9#:._\+~#=]{2,256}[^.]{2,}$/
but this prevents me from defining the path rules of the URI.
How can I ensure that the substring after the last . but before the first /, ? or # is at least 2 characters long?
From what I can see, you're almost there. Made some modification and it seems to work.
^(http(s)?:\/\/)?(www\.)?[a-zA-Z0-9#:._\+~#=]{2,256}\.[a-zA-Z]{2,6}([/#?;]([A-Za-z0-9-._~:?#[\]#!$&''()*+,;=]|(%[A-Fa-f0-9]{2}))*)?$
Can be somewhat shortened by doing
^(http(s)?:\/\/)?(www\.)?[\w#:.\+~#=]{2,256}\.[a-zA-Z]{2,6}([/#?;]([-\w.~:?#[\]#!$&''()*+,;=]|(%[A-Fa-f0-9]{2}))*)?$
(basically just tweaked your regex)
The main difference is that the parameter part is optional, but if it is there it has to start with one of /#?;. That part could probably be simplified as well.
Check it out here.
Edit:
After some experimenting I think this one is about as simple it'll get:
^(http(?:s)?:\/\/)?([-.~\w]+\.[a-zA-Z]{2,6})(:\d+)?(\/[-.~\w]*)?([#/#?;].*)?$
It also captures the separate parts - scheme, host, port, path and query/params.
Example here.
I am a email spam quarantine administrator and I can write regular expression rules to block email messages. There is a common classification of email spam hitting our domain such that the username of any of our email addresses is spoofed in front of some other domain.
For example, suppose my email address is jwclark#domain.com. In that case, spammers are writing to me from all kinds of other domains that start with my username such as:
jwclark1234#whatever.com
jwclark#wrongdomain.com
jwclark#a.domain.com
How can I write a regular expression rule to match everything including jwclark and any wildcards, but not match the original jwclark#domain.com? I would like a regex that matches everything above except for my actual example email address jwclark#domain.com.
I've made this regexp here
^jwclark.*[#](?!domain\.com).*$
it's in javascript format, but it should be easy to adapt to php or something else.
Given the nature of your problem, you might be better off making a regex builder function that makes the proper regexp for you, given the parameters.
Or, actually use a different approach. I recently found out how to parse ranges of floating point numbers with regexp, but that doesn't make it the proper solution to finding numbers within ranges. :P
edit - fixed silly redundancy thanks to zx81
edit - change to comply with strange limitations:
^jwclark.{0,25}[#][^d][^o][^m][^a][^i][^n].{0,25}\.com.{0,25}$
demo for the strange one
I'm trying to configure my Foxy Proxy program and one of the features is to provide a regular expression for an exclusion list.
I'm trying to blacklist the local sites (ending in .local), but it doesn't seem to work.
This is what I attempted:
^(?:https?://)?\d+\.(?!local)+/.*$
^(?:https?://)?\d+\.(?!local)(\d)+/.*$
I also researched on Google and Stack Exchange with no success.
Since you indicate in the comments that you actually need a whitelist solution, I went with that:
Try: ^(?:https?://)?[\w.-]+\\.(?!local)\w+/.*$
http://regex101.com/r/xV4gS0
Your regex expressions match host names which start with a series of digits followed by a period and then not followed by the string "local". If this is a "blacklist", then that hardly seems like what you want.
If you're trying to match all hostnames which end in .local, you'd want something like the following for the hostname portion:
[^/]*\.local(?:/|$)
with appropriate escapes inserted depending on regex context.
If your original question was incorrect and you really need a whitelist, then you'd want something like:
^(?:(?!\.local)[^\/])*(?:\/|$)
as illustrated in http://regex101.com/r/yB0uY4
Thank you everyone to help. Indeed, it turns out that for this program, enlisting "not .local" as blacklist, it's not the same as "all .local" as whitelist.
I also had a rookie mistake on my pattern. I meant "\w" instead of "\d". Thank you Peter Alfvin for catching that.
So my final working solution is what Bart suggested:
^(?:https?://)?[\w.-]+\.(?!local)\w+/.*$ as a whitelist.
Sorry if this has been asked elsewhere, I've been looking and can't find it for the life of me. I am attempting at tackling regular expressions, I've ALWAYS had problems with the more advanced scenarios... well, others find them quite easy, so maybe there's something wrong with me.
Anyway, I am attempting to write a RegEx that matches www.domain.com OR domain.com but NO OTHER SUBDOMAINS or anything. The only two strings I want to pass the regex are "domain.com" and "www.domain.com" and I haven't been able to find exactly what I am looking for other than including all subdomain matching, which I find easy.
The closest I have come is this: regex for matching something if it is not preceded by something else but in that case its failing only for one preceding string, I want it to succeed for only one preceding string/subdomain. Note, "domain.com" will always be static, meaning it will always be that exact string "domain.com" not various domains.
Thanks so much for shedding light on this!
Tyler
Just put the optional part in a non-capturing group, and make it optional.
/^(?:www\.)?example.com$/
I have a regex pattern for URL's that I use to check for links in a body of text. The only problem is that the pattern will match this link
stackoverflow.com
And this sentence
I'm a sentence.Next Sentence.
Obviously this would make sense because my pattern doesn't strong check .com, .co.uk, .com.au etc
I want it to match stackoverflow.com and not the latter.
As I'm no Regex expert, does anyone know of any good Regex patterns for checking for all types of URL's in a body text, while not matching the sentences like above?
If I have to strong check the domain extension, I suppose I'll have to settle.
Here's my pattern, but i don't think it help.
(([\w]+:)?\/\/)?(([\d\w]|%[a-fA-f\d]{2,2})+(:([\d\w]|%[a-fA-f\d]{2,2})+)?#)?([\d\w][-\d\w]{0,253}[\d\w]\.)+[\w]{2,4}(:[\d]+)?(\/([-+_~.\d\w]|%[a-fA-f\d]{2,2})*)*(\?(&?([-+_~.\d\w]|%[a-fA-f\d]{2,2})=?)*)?(#([-+_~.\d\w]|%[a-fA-f\d]{2,2})*)?
I would definitely suggest finding a working regex that someone else has made (which would probably include a strong check on the domain extension), but here is one possible way to just modify your existing regex.
It requires that you make the assumption that usually links will not mix case in the domain extension, for example you might see .COM or .com but probably not .Com, if you only match domain extensions that don't mix case then you would avoid matching most sentences.
In the middle of your regex you have [\w]{2,4}, try changing this to ([A-Z]{2,4}|[a-z]{2,4}) (or (?:[A-Z]{2,4}|[a-z]{2,4}) if you don't want a new captured group).