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From: Don Lewis <Don.Lewis@tsc.tdk.com>
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Date: Wed, 10 Jan 2001 01:48:46 -0800
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To: Jesper Skriver <jesper@skriver.dk>,
	Don Lewis <Don.Lewis@tsc.tdk.com>
Subject: Re: ICMP error processing (was: Re: what to do now ?  Was: cvs commit: src/sys/netinet ip_icmp.c tcp_subr.c tcp_var.h)
Cc: freebsd-net@FreeBSD.ORG
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On Jan 9,  6:16pm, Jesper Skriver wrote:
} Subject: Re: ICMP error processing (was: Re: what to do now ?  Was: cvs co
} On Mon, Jan 08, 2001 at 11:02:17PM -0800, Don Lewis wrote:

} > In the current code, it looks like an ICMP error that the addresses
} > and ports zeroed out will erroneously affect many sessions (what do
} > the RFCs say?).
} 
} rfc793 doesn't mention any specific range for port numbers apart form
} being a 16 bit number, but it does say explicitly (in section 3.3) that
} the sequence number is a range from 0 to 2**32 - 1
} 
} If the port numbers and/or addresses are zero we affect many (or even all)
} sessions, I don't have anything near a full overview of the kernel, so I 
} don't know if there is any check anywhere else for zero in those addresses 
} and/or port numbers.

There's none that I'm aware of.  We just blindly copy whatever is in
the payload of the ICMP error packet and feed that to in_pcbnotify().
If the data happens to be zero, then in_pcbnotify() treats it as a wildcard.

} > Another bit of strangeness is pfctlinput(PRC_IF{UP,DOWN}, ...) which
} > is passed the interface address, which is matched against the
} > *destination* address in the TCP and UDP PCBs.  Fortunately these
} > protocols seem to ignore these commands ...
} 
} As I see this we need a new function to do the same just for the source
} address in TCP and UDP PCBs, right ?

Or an API change to the wildcard version of PCB lookup allows the
destination address to be wildcarded.  The PRC_IF{UP,DOWN} handlers
in the raw IP stack would need to be tweaked to compensate, and we'd
need to sweep the source for other pieces of code that might be affected.


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