[asterisk-dev] asterisk 1.4 rtp port exhaustion fix

[Tilghman Lesher]

On Monday 16 May 2011 15:26:29 Paul Albrecht wrote:
> On Mon, 2011-05-16 at 13:53 -0500, Paul Belanger wrote:
> > On 11-05-16 02:02 PM, Paul Albrecht wrote:
> > > Hi,
> > > 
> > > When I run the mp3 application I sometimes run out of rtp ports
> > > because asterisk doesn't close open files and sockets before
> > > exec'ing the mpg123
> > 
> > > process. Here's a fix:
> > If there is not already an issue on the tracker, please create one.
> > Also, uploading your patch to reviewboard would be recommended.
> 
> There must be an issue already because someone "fixed" the problem for
> later asterisk releases. The thing is I don't think the "fix" makes
> sense for linux which I thought was the preferred platform for asterisk.
> The linuxy way to close open descriptors before exec'ing a script would
> be to set the "close on exec" whenever a file is opened or a socket is
> created. As for the review board, I simply fixed the stuff that affected
> the applications that I support so the codes not finished and not ready
> for review.

We opted in the later releases to make it part of the API and standardize
the various methods to ensure that all file descriptors were closed (as well
as fixing signal races and other issues).  No, it's not Linux-specific, but
it should work fine on all platforms where fork is available (as opposed to
vfork).

As to the CLOEXEC method, it's very difficult to make that method work
reliably, because many calls that open file descriptors do not have flags
to ensure that the CLOEXEC flag is set atomically.  Additionally, linked
libraries may open file descriptors at various intervals, and it would be
impossible to ensure that each of those libraries also used the CLOEXEC
flag.  It was definitely considered at the time, but it was rejected, because
it's not a reliable method.

-- 
Tilghman