cvs commit: src/sys/net if_vlan.c

[Bill Paul]

wpaul       2003/07/05 20:24:25 PDT

  FreeBSD src repository

  Modified files:
    sys/net              if_vlan.c 
  Log:
  Testing VLANs with the new 8139C+ chip (which does hardware tag
  insertion and extraction) has revealed two bugs:
  
  - In vlan_start(), we're supposed to check the underlying interface to
    see if it has the IFCAP_VLAN_HWTAGGING cabability set and, if so, set
    things up for the VLAN_OUTPUT_TAG() routine. However the code checks
    ifp->if_capabilities, which is the vlan pseudo-interface's capabilities
    when it should be checking p->if_capabilities, which relates to the
    underlying physical interface. Change ifp->if_capabilities to
    p->if_capabilities so this works.
  
  - In vlan_input(), we have to extract the 16-bit tag value from the
    received frame and use it to figure out which vlan interface gets
    the frame. The code that we use to track down the desired vlan
    pseudo-interface is:
  
         for (ifv = LIST_FIRST(&ifv_list); ifv != NULL;
              ifv = LIST_NEXT(ifv, ifv_list))
                  if (ifp == ifv->ifv_p && tag == ifv->ifv_tag)
                          break;
  
    The problem is that 'tag' is not computed consistently. In the case
    where the interface supports hardware VLAN tag extraction and calls
    VLAN_INPUT_TAG(), we do this:
  
                  tag = *(u_int*)(mtag+1);
  
    But in the software emulation case, we do this
  
                  tag = EVL_VLANOFTAG(ntohs(evl->evl_tag));
  
    The problem here is the EVL_VLANOFTAG() macro is only ever applied
    in this one case. It's never applied to ifv->ifv_tag or anwhere else.
    We must be consistent: either it's applied everywhere or nowhere.
    To see how this can be a problem, do something like
    ifconfig vlan0 vlan 12345 vlandev foo0 and observe the results.
  
    I'm not quite sure what the right thing is to do here. Neither the
    vlan(4) nor ifconfig(8) man pages suggest which way to go. For now,
    I've removed this use of EVL_VLANOFTAG() so that the tag will match
    correctly in all cases. I will not get upset if somebody makes a
    compelling argument for using EVL_VLANOFTAG() everywhere instead,
    as long as the use is consistent.
  
  Revision  Changes    Path
  1.50      +2 -2      src/sys/net/if_vlan.c