• Erik Kline's avatar
    net: ipv6: Add a sysctl to make optimistic addresses useful candidates · 7fd2561e
    Erik Kline authored
    Add a sysctl that causes an interface's optimistic addresses
    to be considered equivalent to other non-deprecated addresses
    for source address selection purposes.  Preferred addresses
    will still take precedence over optimistic addresses, subject
    to other ranking in the source address selection algorithm.
    
    This is useful where different interfaces are connected to
    different networks from different ISPs (e.g., a cell network
    and a home wifi network).
    
    The current behaviour complies with RFC 3484/6724, and it
    makes sense if the host has only one interface, or has
    multiple interfaces on the same network (same or cooperating
    administrative domain(s), but not in the multiple distinct
    networks case.
    
    For example, if a mobile device has an IPv6 address on an LTE
    network and then connects to IPv6-enabled wifi, while the wifi
    IPv6 address is undergoing DAD, IPv6 connections will try use
    the wifi default route with the LTE IPv6 address, and will get
    stuck until they time out.
    
    Also, because optimistic nodes can receive frames, issue
    an RTM_NEWADDR as soon as DAD starts (with the IFA_F_OPTIMSTIC
    flag appropriately set).  A second RTM_NEWADDR is sent if DAD
    completes (the address flags have changed), otherwise an
    RTM_DELADDR is sent.
    
    Also: add an entry in ip-sysctl.txt for optimistic_dad.
    Signed-off-by: default avatarErik Kline <ek@google.com>
    Acked-by: default avatarLorenzo Colitti <lorenzo@google.com>
    Acked-by: default avatarHannes Frederic Sowa <hannes@stressinduktion.org>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    7fd2561e
addrconf.c 132 KB