Date: Mon, 21 Oct 96 23:07:27 +0100 From: Jean-Marc Zucconi <jmz@cabri.obs-besancon.fr> To: wollman@lcs.mit.edu Cc: freebsd-current@freebsd.org Subject: Re: socket (AF_UNIX) bug Message-ID: <9610212207.AA15621@cabri.obs-besancon.fr> In-Reply-To: <9610211430.AA13042@halloran-eldar.lcs.mit.edu> (message from Garrett Wollman on Mon, 21 Oct 1996 10:30:07 -0400)
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>>>>> Garrett Wollman writes:
> <<On Mon, 21 Oct 96 03:18:14 +0100, Jean-Marc Zucconi <jmz@cabri.obs-besancon.fr> said:
>> The following code creates a socket whose name is 1 char too
>> short. A workaround is to add 1 to addrlen before calling bind, but I
>> think that the code should work as is.
> The code is wrong.
>> strncpy (sockaddr.sun_path, path, sizeof(sockaddr.sun_path));
>> addrlen = sizeof(sockaddr.sun_family) + strlen(path);
> sizeof(sockaddr.sun_family) == 1
> offsetof(struct sockaddr_un, sun_path) == 2
> This would be clearer if the sockaddr were properly initialized; i.e.:
>> strncpy (sockaddr.sun_path, path, sizeof(sockaddr.sun_path));
> sockaddr.sun_len = offsetof(struct sockaddr_un, sun_path)
> + min(strlen(path), sizeof(sockaddr.sun_path));
>> addrlen = sizeof(sockaddr.sun_family)
> + min(strlen(path), sizeof(sockaddr.sun_path));
> /* alternatively, addrlen = sockaddr.sun_len */
OK, I thought it was a bug because
1 - I do not wrote it :-) - it comes from a package I ported to
freebsd.
2 - I looked in the Stevens book and he gives the same expression for
addrlen (see p294)
3 - this works on the machines on which I tried (ultrix, osf, sunos)
I think that bind() should be modified so that it does not ignore the
extra byte, if the rest of the string is padded with nuls. This for
compatibility reasons.
Jean-Marc
_____________________________________________________________________________
Jean-Marc Zucconi Observatoire de Besancon F 25010 Besancon cedex
PGP Key: finger jmz@cabri.obs-besancon.fr
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