bugGNU Wget - Bugs: bug #62586, Warning given every time wget...

 
 

bug #62586: Warning given every time wget runs: “.netrc:..: unknown token” when a password contains quotes

Submitter:  Eo Koochu <eokoochu>
Submitted:  Sun 05 Jun 2022 04:46:28 PM UTC
 
Category:  Program Logic Severity:  3 - Normal
Priority:  5 - Normal Status:  None
Privacy:  Public Assigned to:  None
Originator Name:  Open/Closed:  Open
Release:  trunk Operating System:  GNU/Linux
Reproducibility:  Every Time Fixed Release:  None
Planned Release:  None Regression:  None
Work Required:  None Patch Included:  No
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Thu 09 Jun 2022 07:59:14 PM UTC, comment #3: 

I should also mention that the password that’s reported as being an unknown token contains these special characters:

"',%@!/;=<\

(not necessarily in that order)

Eo Koochu <eokoochu>
Tue 07 Jun 2022 06:19:24 PM UTC, comment #2: 

comment #1:

> As you mention, there is no standard/spec. And this puts this issue into an unsolvable state. Too many clients have their own, slightly diverting implementation. Whatever any client will change, it likely breaks backwards compatibility.
>


I believe there’s been a misunderstanding about what the bug actually is. The fact that wget parses .netrc differently than other apps is not the bug (as every app is free to choose their own syntax, unfortunately).

I see two bugs in wget:

bug 1) wget incorrectly assumes that all other apps require the same syntax for the password string.  So when a record appears in .netrc that exists for fetchmail (not for wget), wget should not be making noise about it (unless perhaps wget is asked to use a password it can’t parse for a host it’s connecting to). 

bug 2) the wget man page neglects to specify the syntax of the .netrc file. So not only is wget enforcing a particular syntax, it doesn’t document what syntax it expects.

bug 3?) wget treats a password with many quote chars as a syntax error, when cURL (for example) would not. (see below)

> I looked into netkit and GNU inetutils' ftp command. In both cases, the .netrc parser allows surrounding double quotes and supports primitive escaping using \ (the following char is taken as-is). No hint for a support of bash-style quoting.
>


Someone is wrong here. The fetchmail man page states that fetchmail follows the same syntax rules as netkit-ftp. And the developer confirms this here:

https://bugs.launchpad.net/ubuntu/+source/fetchmail/+bug/1976361

I can also say for certain that using a backslash to escape quote characters does not work for fetchmail.

> Wget (and nowadays also curl) does basically the same thing (but not 100% identical).
>


cURL simply takes all chars in the linefeed-terminated password field to be the literals. So if a password is simple but has surrounding double quotes, even then cURL treats the quotes themselves as part of the password. There is also no concept of escaping characters with cURL’s parser.

If that’s similar to wget’s netrc parser, then perhaps whoever updates the man page of one might consider updating the man page of the other.  (Because cURL is also undocumented in this regard IIRC).

But I suspect there must be a significant difference between cURL and wget’s parser because the password that wget said was a syntax error is one that cURL would consider syntactically correct. cURL would simply treat all the quote chars as literally being part of the password.  So if wget is expected to behave the same in that regard, then there is a 3rd bug in wget.

> Interestingly, both ftp clients I looked at use a character/stream based parser. This implies that quoted password can span multiple lines - the only way to include e.g. a linefeed into the password (\ escaping doesn't allow this).
>
> Fetchmail (and also wget) uses a line-oriented parser that doesn't allow linefeed in a password at all. And it uses what you call 'bash-style' quoting
>


This seems contradictory. That is, with the bash-style quoting it would certainly be possible to include linefeeds. But I should clarify that fetchmail does not document the password spec rules. It’s merely my experimentation & testing that led me to characterize fetchmail as expecting “bash-style quoting”. So it’s quite possible that you’re right on that… that fetchmail quits when a linefeed is encountered, in which case it’s wrong for me to call it bash—style quoting. Not sure what else to call it then. But notibly, just as there are many ways to quote a string in bash, the same password can also have many different representations.  E.g. the following are the same result in fetchmail IIUC:

compl3x"'"p4SS'"w0rd%here'
"compl3x'"p4SS'"'w0rd%here
compl3x"'"p4SS'"'w0rd%here

> - something that is absolutely unneeded when it comes to embedding quotes in passwords.
>


There are two typical ways to represent embedded quotes:

1) Surrounding all single quotes with double quotes, and all double quotes with single quotes.

2) Using an escape character, such as a backslash. But if the escape character chosen is valid in a password string (such as backslash), then the parser must also make an exception for the escape char itself (\\ → \).

Using one approach means you don’t need the other approach.

> My conclusion is that it is too late to set up a spec, and that fetchmail is at least incompatible with other netrc parsers (to say it nicely).
>


I disagree, but it doesn’t matter because the purpose of this bug report was not to get a standard spec.

It would be possible for the netrc-ftp project to declare a spec in order to get all future apps consistent. Existing apps could be regarded as non-conformant but it wouldn’t necessarily require action; they would likely be grandfathered & tolerated.

In any case, wget should document its own spec for what’s expected in the .netrc file.

Eo Koochu <eokoochu>
Mon 06 Jun 2022 10:15:30 AM UTC, comment #1: 

As you mention, there is no standard/spec. And this puts this issue into an unsolvable state. Too many clients have their own, slightly diverting implementation. Whatever any client will change, it likely breaks backwards compatibility.

I looked into netkit and GNU inetutils' ftp command. In both cases, the .netrc parser allows surrounding double quotes and supports primitive escaping using \ (the following char is taken as-is). No hint for a support of bash-style quoting.

Wget (and nowadays also curl) does basically the same thing (but not 100% identical).

Interestingly, both ftp clients I looked at use a character/stream based parser. This implies that quoted password can span multiple lines - the only way to include e.g. a linefeed into the password (\ escaping doesn't allow this).

Fetchmail (and also wget) uses a line-oriented parser that doesn't allow linefeed in a password at all. And it uses what you call 'bash-style' quoting - something that is absolutely unneeded when it comes to embedding quotes in passwords.

My conclusion is that it is too late to set up a spec, and that fetchmail is at least incompatible with other netrc parsers (to say it nicely).

Tim Ruehsen <rockdaboot>
Project Administrator
Sun 05 Jun 2022 04:46:28 PM UTC, original submission:  

Background:

Different applications expect a different password syntax in ~/.netrc due to lack of standards & specs. It’s a messy state of affairs which is documented here:

https://bugs.launchpad.net/ubuntu/+source/netkit-ftp/+bug/1976341

The problem at hand:

When a password /contains/ quotes, such as the following password:

  compl3x'p4SS"w0rd%here

FTP & Fetchmail both require that password to be entered in .netrc using bash-style quoting, as follows:

  compl3x"'"p4SS'"w0rd%here'

That password must be entered with all those extra quotes when the password itself contains quotes, and FTP or Fetchmail will use that record.  The problem is wget has a noisey parser which parses the `.netrc` file even when no credentials are needed for the fetch. The parser then complains about a .netrc record for which the syntax is for a different application.

Yes, it sucks that there is no standard spec and that different apps expect a different password syntax.  I believe FTP was the first app to use .netrc and so the FTP syntax style should be at least respected by the parser as far as announcing syntax errors to the user.

The wget version is 1.21. I chose “trunk” on the pulldown because 1.20 is the latest in the list.

Eo Koochu <eokoochu>

 

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