getent services enumeration glitch

getent services enumeration glitch

[Mark Geisert]

There is a glitch when getent enumerates all services; it shows an incorrect
port number.  Providing a service name on invocation shows the correct port
number.  Examples:

$ getent services man
man                   9535/tcp

$ getent services | grep man
man                   16165/tcp

It looks like when all services are enumerated there is an extra or missing
byte swap call to htons() or ntohs().  This can be observed by comparing the
hex values of the two port numbers shown above, giving 0x253F and 0x3F25.

..mark


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Re: getent services enumeration glitch

[Corinna Vinschen]

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Hi Mark,

On Aug 18 09:40, Mark Geisert wrote:
> There is a glitch when getent enumerates all services; it shows an incorrect
> port number.  Providing a service name on invocation shows the correct port
> number.  Examples:
> 
> $ getent services man
> man                   9535/tcp
> 
> $ getent services | grep man
> man                   16165/tcp
> 
> It looks like when all services are enumerated there is an extra or missing
> byte swap call to htons() or ntohs().  This can be observed by comparing the
> hex values of the two port numbers shown above, giving 0x253F and 0x3F25.

Congratulations!  You found a 13 years old bug in Cygwin's getservent
implementation, which returned the port number in host byte order
instead of in network byte order for all this time.  Makes me wonder
how often getservent is used in the wild...

Since I uploaded 2.2.1-0.2 just before your bug report, I quickly
created a new snapshot with the patch on https://cygwin.com/snapshots/
Please give it a try.


Thanks,
Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat

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Re: getent services enumeration glitch

[Mark Geisert]

Corinna Vinschen writes:
> On Aug 18 09:40, Mark Geisert wrote:
> > $ getent services man
> > man                   9535/tcp
> > 
> > $ getent services | grep man
> > man                   16165/tcp
> > 
> Congratulations!  You found a 13 years old bug in Cygwin's getservent
> implementation, which returned the port number in host byte order
> instead of in network byte order for all this time.  Makes me wonder
> how often getservent is used in the wild...
> 
> Since I uploaded 2.2.1-0.2 just before your bug report, I quickly
> created a new snapshot with the patch on https://cygwin.com/snapshots/
> Please give it a try.
> 
> Thanks,
> Corinna

The new snapshot solves the issue for me.  I'll see if I can stumble upon a
more substantial bug next time :)
Cheers,

..mark

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captcha: schussing




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Re: getent services enumeration glitch

[Corinna Vinschen]

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On Aug 18 17:27, Mark Geisert wrote:
> Corinna Vinschen writes:
> > On Aug 18 09:40, Mark Geisert wrote:
> > > $ getent services man
> > > man                   9535/tcp
> > > 
> > > $ getent services | grep man
> > > man                   16165/tcp
> > > 
> > Congratulations!  You found a 13 years old bug in Cygwin's getservent
> > implementation, which returned the port number in host byte order
> > instead of in network byte order for all this time.  Makes me wonder
> > how often getservent is used in the wild...
> > 
> > Since I uploaded 2.2.1-0.2 just before your bug report, I quickly
> > created a new snapshot with the patch on https://cygwin.com/snapshots/
> > Please give it a try.
> > 
> > Thanks,
> > Corinna
> 
> The new snapshot solves the issue for me.  I'll see if I can stumble upon a
> more substantial bug next time :)

Haha, yeah, but I think it's substantial enough.  I'm just puzzled that
this bug could live all this time unhampered.


Thanks,
Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat

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Re: getent services enumeration glitch

[Warren Young]

On Aug 18, 2015, at 5:24 AM, Corinna Vinschen <corinna-cygwin@cygwin.com> wrote:
> 
> Makes me wonder
> how often getservent is used in the wild…

I’d bet getservbyname() is used far more often.
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Re: getent services enumeration glitch

[Corinna Vinschen]

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On Aug 18 12:43, Warren Young wrote:
> On Aug 18, 2015, at 5:24 AM, Corinna Vinschen <corinna-cygwin@cygwin.com> wrote:
> > 
> > Makes me wonder
> > how often getservent is used in the wild…
> 
> I’d bet getservbyname() is used far more often.

I won't bet against you.


Corinna

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Corinna Vinschen                  Please, send mails regarding Cygwin to
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RE: getent services enumeration glitch

[Buchbinder, Barry (NIH/NIAID) [E]]

Corinna Vinschen sent the following at Tuesday, August 18, 2015 7:24 AM
>On Aug 18 09:40, Mark Geisert wrote:
>Congratulations! You found a 13 years old bug in Cygwin's getservent
>implementation, which returned the port number in host byte order
>instead of in network byte order for all this time. Makes me wonder how
>often getservent is used in the wild...

Not that I know what getent is, let alone having ever used it, shouldn't
finding a bug that old merit a gold star?

- Barry
  Disclaimer: Statements made herein are not made on behalf of NIAID.

Re: getent services enumeration glitch

[Mark Geisert]

Buchbinder, Barry writes:
> Corinna Vinschen sent the following at Tuesday, August 18, 2015 7:24 AM
> >On Aug 18 09:40, Mark Geisert wrote:
> >Congratulations! You found a 13 years old bug in Cygwin's getservent
> >implementation, which returned the port number in host byte order
> >instead of in network byte order for all this time. Makes me wonder how
> >often getservent is used in the wild...
> 
> Not that I know what getent is, let alone having ever used it, shouldn't
> finding a bug that old merit a gold star?

Oh, please no.  A tin star if you must.  Let's keep gold stars for folks
doing the heavy lifting around here.

..mark


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[SILVERY GOLDSTAR] Re: getent services enumeration glitch

[Corinna Vinschen]

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On Aug 18 23:43, Mark Geisert wrote:
> Buchbinder, Barry writes:
> > Corinna Vinschen sent the following at Tuesday, August 18, 2015 7:24 AM
> > >On Aug 18 09:40, Mark Geisert wrote:
> > >Congratulations! You found a 13 years old bug in Cygwin's getservent
> > >implementation, which returned the port number in host byte order
> > >instead of in network byte order for all this time. Makes me wonder how
> > >often getservent is used in the wild...
> > 
> > Not that I know what getent is, let alone having ever used it, shouldn't
> > finding a bug that old merit a gold star?
> 
> Oh, please no.  A tin star if you must.  Let's keep gold stars for folks
> doing the heavy lifting around here.

Oh, come one, don't be shy.  A silver star at least,

Andrew, do we have silver stars in the vaults?


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
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Red Hat

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Re: [SILVERY GOLDSTAR] Re: getent services enumeration glitch

[Andrew Schulman]

> On Aug 18 23:43, Mark Geisert wrote:
> > Buchbinder, Barry writes:
> > > Corinna Vinschen sent the following at Tuesday, August 18, 2015 7:24 AM
> > > >On Aug 18 09:40, Mark Geisert wrote:
> > > >Congratulations! You found a 13 years old bug in Cygwin's getservent
> > > >implementation, which returned the port number in host byte order
> > > >instead of in network byte order for all this time. Makes me wonder how
> > > >often getservent is used in the wild...
> > > 
> > > Not that I know what getent is, let alone having ever used it, shouldn't
> > > finding a bug that old merit a gold star?
> > 
> > Oh, please no.  A tin star if you must.  Let's keep gold stars for folks
> > doing the heavy lifting around here.
> 
> Oh, come one, don't be shy.  A silver star at least,
> 
> Andrew, do we have silver stars in the vaults?

But of course!  https://cygwin.com/goldstars/#MG


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Re: [SILVERY GOLDSTAR] Re: getent services enumeration glitch

[Corinna Vinschen]

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On Aug 19 08:22, Andrew Schulman wrote:
> > On Aug 18 23:43, Mark Geisert wrote:
> > > Buchbinder, Barry writes:
> > > > Corinna Vinschen sent the following at Tuesday, August 18, 2015 7:24 AM
> > > > >On Aug 18 09:40, Mark Geisert wrote:
> > > > >Congratulations! You found a 13 years old bug in Cygwin's getservent
> > > > >implementation, which returned the port number in host byte order
> > > > >instead of in network byte order for all this time. Makes me wonder how
> > > > >often getservent is used in the wild...
> > > > 
> > > > Not that I know what getent is, let alone having ever used it, shouldn't
> > > > finding a bug that old merit a gold star?
> > > 
> > > Oh, please no.  A tin star if you must.  Let's keep gold stars for folks
> > > doing the heavy lifting around here.
> > 
> > Oh, come one, don't be shy.  A silver star at least,
> > 
> > Andrew, do we have silver stars in the vaults?
> 
> But of course!  https://cygwin.com/goldstars/#MG

Thanks a lot!


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat

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Re: [SILVERY GOLDSTAR] Re: getent services enumeration glitch

[Andrey Repin]

Greetings, Andrew Schulman!

>> On Aug 18 23:43, Mark Geisert wrote:
>> > Buchbinder, Barry writes:
>> > > Corinna Vinschen sent the following at Tuesday, August 18, 2015 7:24 AM
>> > > >On Aug 18 09:40, Mark Geisert wrote:
>> > > >Congratulations! You found a 13 years old bug in Cygwin's getservent
>> > > >implementation, which returned the port number in host byte order
>> > > >instead of in network byte order for all this time. Makes me wonder how
>> > > >often getservent is used in the wild...
>> > > 
>> > > Not that I know what getent is, let alone having ever used it, shouldn't
>> > > finding a bug that old merit a gold star?
>> > 
>> > Oh, please no.  A tin star if you must.  Let's keep gold stars for folks
>> > doing the heavy lifting around here.
>> 
>> Oh, come one, don't be shy.  A silver star at least,
>> 
>> Andrew, do we have silver stars in the vaults?

> But of course!  https://cygwin.com/goldstars/#MG

s/fixing/finding/ ?


-- 
With best regards,
Andrey Repin
Wednesday, August 19, 2015 19:47:37

Sorry for my terrible english...


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Re: [SILVERY GOLDSTAR] Re: getent services enumeration glitch

[Andrew Schulman]

> s/fixing/finding/ ?

Right, thanks.  Fixed.


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