From mboxrd@z Thu Jan  1 00:00:00 1970
From: Patrick McHardy <kaber@trash.net>
Subject: Re: ip_nat_mangle_udp_packet problems
Date: Fri, 06 May 2005 18:24:24 +0200
Message-ID: <427B9A38.2040602@trash.net>
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To: Christian Hentschel <chentschel@arnet.com.ar>
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Christian Hentschel wrote:
> Hi, 
> 	i hope someone could answer this problem i'm experimenting. I'm writing
> a SIP/RTP conntrack/NAT helper, and i need to mangle packets multiple
> times, since there are lots of fields to be mangled.
> 	I'm using new conntrack/nat framework (>2.6.11) and the way i took to
> do it is causing me some problems.
> 	Basically, i just look for string into the packet, mangle it and call
> ip_nat_mangle_udp_packet(). The problem is when i try to search the
> nexts strings, i get the wrong offsets. 
> I saw ip_nat_mangle_udp_packet() does not do it manipulation
> immediatelly. Please could someone explain this ?.

enlarge_skb() called from ip_nat_mangle_udp_packet() might replace the
packet if it doesn't fit. You need to reload all pointers to the skb
after calling ip_nat_mangle_udp_packet().

Regards
Patrick