• Gerhard Sittig's avatar
    net: dns: fix for DNS queries sent to the wrong MAC address · f395e75e
    Gerhard Sittig authored
    When a DNS query is sent out, the ethernet packet can get directed to
    the MAC address of a server that was communicated to before.  This is
    wrong when the previously stored MAC address corresponds to a different
    server's IP address, i.e. when the IP address of the previous and the
    current communication are different.
    
    The error can get reproduced by running a sequence of e.g. a TFTP
    download and a DNS query, where the TFTP and DNS servers reside on
    individual machines.
    
    The fix is to clear the server's MAC address that might be left from a
    previous operation, and to fetch the peer's MAC address in a new ARP
    lookup, before the DNS query is sent.  This is the approach taken in
    other network services, like 8e52533d ("net: tftpsrv: Get correct
    client MAC address").
    Reported-by: default avatarDirk Zimoch <dirk.zimoch@psi.ch>
    Signed-off-by: default avatarGerhard Sittig <gsi@denx.de>
    f395e75e
dns.c 4.67 KB