Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ukma!xanth!lll-winken!uunet!lupine!djm
From: djm@lupine.UUCP (Dave Mackie)
Newsgroups: comp.protocols.tcp-ip
Subject: Re: Follow-up to my ICMP_UNREACH_PORT question
Summary: Answer to where is EPORTUNREACH
Message-ID: <363@lupine.UUCP>
Date: 8 May 89 19:26:15 GMT
References: <8905032253.AA00554@lear.ultra.com>
Organization: Network Computing Devices
Lines: 19

> PS:  Actually, I do have one continuing question:  Could some BSD guru
> out there please tell me if the BSD UDP in fact DOES notify anyone
> when it gets an ICMP_UNREACH_PORT, and how?  I've got the 4.3 source
> but not the familiarity to answer this definitively.  I don't SEE any
> such notification, and there is no EPORTUNREACH sys/errno.h, but ...

        This isn't pretty! IP receives the ICMP message and eventually
        calls udp_ctlinput(). UDP then use inetctlerrmap[] (ip_input.c)
        to map the ICMP type to a BSD error number. In this case ICMP
        PORT UNREACHABLE gets mapped to ECONNREFUSED. The routine
        in_pcbnotify() then gets called to find the correct pcb to
        deliver the error to. If your just using sendto() then there is
        no pcb with the correct source/destination address pair in the pcb
        list, and so the error message gets dropped.
 
                                                Dave Mackie
                                                Network Computing Devices
                                                djm@ncd.com