• Sebastian Ottlik's avatar
    util: add socket_set_fast_reuse function which will replace setting SO_REUSEADDR · 606600a1
    Sebastian Ottlik authored
    If a socket is closed it remains in TIME_WAIT state for some time. On operating
    systems using BSD sockets the endpoint of the socket may not be reused while in
    this state unless SO_REUSEADDR was set on the socket. On windows on the other
    hand the default behaviour is to allow reuse (i.e. identical to SO_REUSEADDR on
    other operating systems) and setting SO_REUSEADDR on a socket allows it to be
    bound to a endpoint even if the endpoint is already used by another socket
    independently of the other sockets state. This can even result in undefined
    behaviour.
    
    Many sockets used by QEMU should not block the use of their endpoint after being
    closed while they are still in TIME_WAIT state. Currently QEMU sets SO_REUSEADDR
    for such sockets, which can lead to problems on Windows. This patch introduces
    the function socket_set_fast_reuse that should be used instead of setting
    SO_REUSEADDR when fast socket reuse is desired and behaves correctly on all
    operating systems.
    
    As a failure of this function can only be caused by bad QEMU internal errors, an
    assertion handles these situations. The return value is still passed on, to
    minimize changes in client code and prevent unused variable warnings if NDEBUG
    is defined.
    Signed-off-by: default avatarSebastian Ottlik <ottlik@fzi.de>
    Reviewed-by: default avatarEric Blake <eblake@redhat.com>
    Signed-off-by: default avatarStefan Weil <sw@weilnetz.de>
    606600a1
oslib-posix.c 6.38 KB