On Wed, May 25, 2011 at 02:31:05PM +0200, Jan Engelhardt wrote:
> On Wednesday 2011-05-25 14:16, Lutz Jaenicke wrote:
>
> >getaddrinfo() will fail for numeric port numbers if neither
> >the socket type (stream/datagram) nor the protocol is
> >provided.
> >Since matches on ports only make sense if the protocol is known
> >we "just" have to derive the protocol number from the information
> >already collected.
>
> Not quite; ports are also possible with -m ipvs and -m conntrack, which
> do not require -p tcp/udp.
>
>
> If someone speicifies a numeric port to getaddrinfo, I just want the
> thing encoded in struct sockaddr_XX.sXX_port - it does not need to know
> the particular L4 proto, or the service's text-based name to do that -
> which is most likely why glibc allows it.
Manual pages may not be the ultimate reference about the reasoning
on why something is implemented which way. Nevertheless let's see:
Given node and service, which identify an Internet host and a service,
getaddrinfo() returns one or more addrinfo structures, each of which
contains an Internet address that can be specified in a call to bind(2)
or connect(2).
Taking this information "as is" actually means that using getaddrinfo()
the way it is done is at least stretching the functionality...
As I wrote in my introduction for the patch (which has not yet made it to the
mailing list), other C libraries behave like uClibc:
* http://gitorious.org/0xdroid/bionic/blobs/9ab75d4cc803e91b7f1b656ffbe2ad32c52a86f9/libc/netbsd/net/getaddrinfo.c
-> look for "ANDROID-SPECIFIC CHANGE TO MATCH GLIBC" :-)
* http://www.freebsd.org/cgi/query-pr.cgi?pr=51827
* Especially I like
http://www.openbsd.org/cgi-bin/cvsweb/~checkout~/src/lib/libc/net/getaddrinfo.c?rev=1.72;content-type=text%2Fplain
which in the text says
/*
* check for special cases. (1) numeric servname is disallowed if
* socktype/protocol are left unspecified. (2) servname is disallowed
* for raw and other inet{,6} sockets.
*/
(and I took this as a reference until now) but later in get_portmatch():
case SOCK_DGRAM:
case SOCK_STREAM:
case ANY:
allownumeric = 1;
> I would like to have an opinion on that from µclibc preferably..
Seems uClibc is outdated wrt adjusting the behavior with other C libraries...
Best regards,
Lutz
--
Dr.-Ing. Lutz Jänicke
CTO
Innominate Security Technologies AG /protecting industrial networks/
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