On Fri, Jan 26, 2007 at 09:13:31AM +0900, YOSHIFUJI Hideaki / 吉藤英明 wrote:
> In article <[EMAIL PROTECTED]> (at Thu, 25 Jan 2007 14:45:00 -0500), Neil 
> Horman <[EMAIL PROTECTED]> says:


New patch attached with most of your suggestions incorporated.  I've a few
comments mixed in for some of the suggestions that I think need further
discussion

> If optimistic_dad is disabled, flags should be IFA_F_TEMPORARY,
> not IFA_F_TEMPORARY|IFA_F_OPTIMISTIC.
> 
> Another idea is to use IFA_F_OPTIMISTIC not
> IFA_F_OPTIMISTIC|IFA_F_TENTATIVE until the DAD has been finished.
> 

I'm currently setting the OPTIMISTIC flag in every location that its possibly
needed, and then clearing it in addrconf_dad_start if that interface is not
participating in optimistic dad.  I do this because the RFC in section 3.1
indicates that manually configured addresses should not set the optimistic flag.
If I removed the OPTIMISTIC flag from the locations it gets set in the patch and
then only set it for participating interfaces in addrconf_dad_start, I would
need to have some way to tell if the address in question was manually configured
(to avoid setting it in that case).  At present I see no clear way to do that,
but if you have a suggestion, I'll happily change this around.

<snip>
> 
>                                     ((ifa_result->flags & 
> (IFA_F_DEPRECATED|IFA_F_OPTIMISTIC)) == 0)
<snip>
> ditto.
> 
Done

> > @@ -2123,7 +2133,8 @@ static void addrconf_add_linklocal(struct inet6_dev 
> > *idev, struct in6_addr *addr
> >  {
> >     struct inet6_ifaddr * ifp;
> >  
> > -   ifp = ipv6_add_addr(idev, addr, 64, IFA_LINK, IFA_F_PERMANENT);
> > +   ifp = ipv6_add_addr(idev, addr, 64, IFA_LINK, 
> > +                       IFA_F_PERMANENT|IFA_F_OPTIMISTIC);
> >     if (!IS_ERR(ifp)) {
> >             addrconf_dad_start(ifp, 0);
> >             in6_ifa_put(ifp);
> 
> Please do not always put IFA_F_OPTIMISTIC.
> 
Again, same reasoning as above for why I set optimistic in this way.

> >  
> > +   /*
> > +    * Optimistic nodes need to joing the anycast address
> > +    * right away
> > +    */
> > +   if (ifp->flags & IFA_F_OPTIMISTIC)
> > +           addrconf_join_anycast(ifp);
> > +
> >     if (ifp->prefix_len != 128 && (ifp->flags&IFA_F_PERMANENT))
> >             addrconf_prefix_route(&ifp->addr, ifp->prefix_len, dev, 0,
> >                                     flags);
> 
> Should we join anycast even if the node is a host (not a router)?!
> 
I've moved this to the spot below where we check if we are forwarding, so the
new patch attached does not join anycast if we are a router.

> When you add a call to "addrconf_join_anycast()", 
> you must consider when to leave this.
> 
I think addrconf_dad_completed is appropriate for this.  New patch leaves
anycast group when we are no longer optimistic

> 
> > @@ -2573,6 +2594,18 @@ static void addrconf_dad_start(struct inet6_ifaddr 
> > *ifp, u32 flags)
> >             addrconf_dad_stop(ifp);
> >             return;
> >     }
> > +
> > +   /*
> > +    * Forwarding devices (routers) should not use
> > +    * optimistic addresses
> > +    * Nor should interfaces that don't know the 
> > +    * Source address for their default gateway
> > +    * RFC 4429 Sec 3.3
> > +    */
> > +   if ((ipv6_devconf.forwarding) ||
> > +      (ifp->rt == NULL))
> > +           ifp->flags &= ~IFA_F_OPTIMISTIC;
> > +
> >     addrconf_dad_kick(ifp);
> >     spin_unlock_bh(&ifp->lock);
> >  out:
> 
> Please test this condition when you are adding the
> address.
> 
Are you sure?  There are several locations where we add an address that we start
dad on.  Shall I test this in all of those places?  It would seem more
appropriate to do it in addrconf_dad_start, as I do.  Or am I missing something?


> BTW, you have not implemented the later condition,
> right?   Sefault gatewa is not tested.
> 
I thought I was testing it.  I was under the impression from my reading of the
code the ifp->rt held the rt6_info pointer for the default gateway, so if its
not set, we don't know the default gateway.  I may well be missing something
here though.  Please let me know.

> > index 6a9f616..fcd22e3 100644
> > --- a/net/ipv6/ndisc.c
> > +++ b/net/ipv6/ndisc.c
> > @@ -498,7 +498,21 @@ static void ndisc_send_na(struct net_device *dev, 
> > struct neighbour *neigh,
> >          msg->icmph.icmp6_unused = 0;
> >          msg->icmph.icmp6_router    = router;
> >          msg->icmph.icmp6_solicited = solicited;
> > -        msg->icmph.icmp6_override  = override;
> > +   if (!ifp || !(ifp->flags & IFA_F_OPTIMISTIC))
> > +           msg->icmph.icmp6_override  = override;
> > +   else {
> > +           /*
> > +            * We must clear the override flag on all
> > +            * neighbor advertisements from source 
> > +            * addresses that are OPTIMISTIC - RFC 4429
> > +            * section 2.2
> > +            */
> > +           if (override)
> > +                   printk(KERN_WARNING
> > +                           "Disallowing override flag for OPTIMISTIC 
> > addr\n");
> > +           msg->icmph.icmp6_override = 0;
> > +   }
> > +
> 
> Ifp is already put.  Please clear "override" in the code
> where we try getting temporary source address for NS.
> 
Done.  I've moved the check to before the in6_ifa_put, and added a flag to skip
adding the sllao option if we find we are optimistic.

> > @@ -622,9 +637,20 @@ void ndisc_send_rs(struct net_device *dev, struct 
> > in6_addr *saddr,
> > +   /*
> > +    * Check the source address.  If its OPTIMISTIC
> > +    * and addr_len is non-zero (implying the sllao option)
> > +    * then don't send the RS (RFC 4429, section 2.2)
> > +    */
> > +   ifp = ipv6_get_ifaddr(saddr, dev, 1);
> > +
> > +   if ((!ifp) || ((ifp->flags & IFA_F_OPTIMISTIC) && dev->addr_len))
> > +           return;
> > +
> >     ndisc_flow_init(&fl, NDISC_ROUTER_SOLICITATION, saddr, daddr,
> >                     dev->ifindex);
> >  
> 
> I disagree. Please send RS in other way.
> Choose another address, or send it without SLLAO.
> 
Done



More thoughts/comments appreciated.

Thanks & Regards
Neil


Signed-off-by: Neil Horman <[EMAIL PROTECTED]>


 include/linux/if_addr.h |    1 
 include/linux/ipv6.h    |    2 +
 include/linux/sysctl.h  |    1 
 include/net/addrconf.h  |    4 +-
 net/ipv6/addrconf.c     |   78 +++++++++++++++++++++++++++++++++++++++---------
 net/ipv6/mcast.c        |    4 +-
 net/ipv6/ndisc.c        |   74 +++++++++++++++++++++++++++++++--------------
 7 files changed, 124 insertions(+), 40 deletions(-)



diff --git a/include/linux/if_addr.h b/include/linux/if_addr.h
index d557e4c..43f3bed 100644
--- a/include/linux/if_addr.h
+++ b/include/linux/if_addr.h
@@ -39,6 +39,7 @@ enum
 #define IFA_F_TEMPORARY                IFA_F_SECONDARY
 
 #define        IFA_F_NODAD             0x02
+#define IFA_F_OPTIMISTIC       0x04
 #define        IFA_F_HOMEADDRESS       0x10
 #define IFA_F_DEPRECATED       0x20
 #define IFA_F_TENTATIVE                0x40
diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
index f824113..5d37abf 100644
--- a/include/linux/ipv6.h
+++ b/include/linux/ipv6.h
@@ -177,6 +177,7 @@ struct ipv6_devconf {
 #endif
 #endif
        __s32           proxy_ndp;
+       __s32           optimistic_dad;
        void            *sysctl;
 };
 
@@ -205,6 +206,7 @@ enum {
        DEVCONF_RTR_PROBE_INTERVAL,
        DEVCONF_ACCEPT_RA_RT_INFO_MAX_PLEN,
        DEVCONF_PROXY_NDP,
+       DEVCONF_OPTIMISTIC_DAD,
        DEVCONF_MAX
 };
 
diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 81480e6..972a33a 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -570,6 +570,7 @@ enum {
        NET_IPV6_RTR_PROBE_INTERVAL=21,
        NET_IPV6_ACCEPT_RA_RT_INFO_MAX_PLEN=22,
        NET_IPV6_PROXY_NDP=23,
+       NET_IPV6_OPTIMISTIC_DAD=24,
        __NET_IPV6_MAX
 };
 
diff --git a/include/net/addrconf.h b/include/net/addrconf.h
index 88df8fc..d248a19 100644
--- a/include/net/addrconf.h
+++ b/include/net/addrconf.h
@@ -73,7 +73,9 @@ extern int                    ipv6_get_saddr(struct dst_entry 
*dst,
 extern int                     ipv6_dev_get_saddr(struct net_device *dev, 
                                               struct in6_addr *daddr,
                                               struct in6_addr *saddr);
-extern int                     ipv6_get_lladdr(struct net_device *dev, struct 
in6_addr *);
+extern int                     ipv6_get_lladdr(struct net_device *dev, 
+                                               struct in6_addr *,
+                                               unsigned char banned_flags);
 extern int                     ipv6_rcv_saddr_equal(const struct sock *sk, 
                                                      const struct sock *sk2);
 extern void                    addrconf_join_solict(struct net_device *dev,
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 2a7e461..fc29815 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -830,7 +830,8 @@ retry:
        ift = !max_addresses ||
              ipv6_count_addresses(idev) < max_addresses ? 
                ipv6_add_addr(idev, &addr, tmp_plen,
-                             ipv6_addr_type(&addr)&IPV6_ADDR_SCOPE_MASK, 
IFA_F_TEMPORARY) : NULL;
+                             ipv6_addr_type(&addr)&IPV6_ADDR_SCOPE_MASK, 
+                             IFA_F_TEMPORARY|IFA_F_OPTIMISTIC) : NULL;
        if (!ift || IS_ERR(ift)) {
                in6_ifa_put(ifp);
                in6_dev_put(idev);
@@ -962,13 +963,14 @@ int ipv6_dev_get_saddr(struct net_device *daddr_dev,
                         * - Tentative Address (RFC2462 section 5.4)
                         *  - A tentative address is not considered
                         *    "assigned to an interface" in the traditional
-                        *    sense.
+                        *    sense, unless it is also flagged as optimistic.
                         * - Candidate Source Address (section 4)
                         *  - In any case, anycast addresses, multicast
                         *    addresses, and the unspecified address MUST
                         *    NOT be included in a candidate set.
                         */
-                       if (ifa->flags & IFA_F_TENTATIVE)
+                       if ((ifa->flags & IFA_F_TENTATIVE) &&
+                           (!(ifa->flags & IFA_F_OPTIMISTIC)))
                                continue;
                        if (unlikely(score.addr_type == IPV6_ADDR_ANY ||
                                     score.addr_type & IPV6_ADDR_MULTICAST)) {
@@ -1027,15 +1029,17 @@ int ipv6_dev_get_saddr(struct net_device *daddr_dev,
                                }
                        }
 
-                       /* Rule 3: Avoid deprecated address */
+                       /* Rule 3: Avoid deprecated and optimistic address */
                        if (hiscore.rule < 3) {
                                if (ipv6_saddr_preferred(hiscore.addr_type) ||
-                                   !(ifa_result->flags & IFA_F_DEPRECATED))
+                                  ((ifa_result->flags &
+                                   (IFA_F_DEPRECATED|IFA_F_OPTIMISTIC) == 0)))
                                        hiscore.attrs |= 
IPV6_SADDR_SCORE_PREFERRED;
                                hiscore.rule++;
                        }
                        if (ipv6_saddr_preferred(score.addr_type) ||
-                           !(ifa->flags & IFA_F_DEPRECATED)) {
+                          ((ifa_result->flags &
+                           (IFA_F_DEPRECATED|IFA_F_OPTIMISTIC) == 0))) {
                                score.attrs |= IPV6_SADDR_SCORE_PREFERRED;
                                if (!(hiscore.attrs & 
IPV6_SADDR_SCORE_PREFERRED)) {
                                        score.rule = 3;
@@ -1174,7 +1178,8 @@ int ipv6_get_saddr(struct dst_entry *dst,
 }
 
 
-int ipv6_get_lladdr(struct net_device *dev, struct in6_addr *addr)
+int ipv6_get_lladdr(struct net_device *dev, struct in6_addr *addr, 
+                   unsigned char banned_flags)
 {
        struct inet6_dev *idev;
        int err = -EADDRNOTAVAIL;
@@ -1185,7 +1190,7 @@ int ipv6_get_lladdr(struct net_device *dev, struct 
in6_addr *addr)
 
                read_lock_bh(&idev->lock);
                for (ifp=idev->addr_list; ifp; ifp=ifp->if_next) {
-                       if (ifp->scope == IFA_LINK && 
!(ifp->flags&IFA_F_TENTATIVE)) {
+                       if (ifp->scope == IFA_LINK && !(ifp->flags & 
banned_flags)) {
                                ipv6_addr_copy(addr, &ifp->addr);
                                err = 0;
                                break;
@@ -1751,6 +1756,7 @@ ok:
 
                        update_lft = create = 1;
                        ifp->cstamp = jiffies;
+                       ifp->flags |= IFA_F_OPTIMISTIC;
                        addrconf_dad_start(ifp, RTF_ADDRCONF|RTF_PREFIX_RT);
                }
 
@@ -1945,7 +1951,11 @@ static int inet6_addr_add(int ifindex, struct in6_addr 
*pfx, int plen,
                ifp->prefered_lft = prefered_lft;
                ifp->tstamp = jiffies;
                spin_unlock_bh(&ifp->lock);
-
+               /*
+                * Note that section 3.1 of RFC 4429 indicates
+                * That the Optimistic flag should not be set for
+                * manually configured addresses
+                */
                addrconf_dad_start(ifp, 0);
                in6_ifa_put(ifp);
                addrconf_verify(0);
@@ -2123,7 +2133,8 @@ static void addrconf_add_linklocal(struct inet6_dev 
*idev, struct in6_addr *addr
 {
        struct inet6_ifaddr * ifp;
 
-       ifp = ipv6_add_addr(idev, addr, 64, IFA_LINK, IFA_F_PERMANENT);
+       ifp = ipv6_add_addr(idev, addr, 64, IFA_LINK, 
+                           IFA_F_PERMANENT|IFA_F_OPTIMISTIC);
        if (!IS_ERR(ifp)) {
                addrconf_dad_start(ifp, 0);
                in6_ifa_put(ifp);
@@ -2190,7 +2201,7 @@ ipv6_inherit_linklocal(struct inet6_dev *idev, struct 
net_device *link_dev)
 {
        struct in6_addr lladdr;
 
-       if (!ipv6_get_lladdr(link_dev, &lladdr)) {
+       if (!ipv6_get_lladdr(link_dev, &lladdr, IFA_F_TENTATIVE)) {
                addrconf_add_linklocal(idev, &lladdr);
                return 0;
        }
@@ -2527,7 +2538,11 @@ static void addrconf_dad_kick(struct inet6_ifaddr *ifp)
        unsigned long rand_num;
        struct inet6_dev *idev = ifp->idev;
 
-       rand_num = net_random() % (idev->cnf.rtr_solicit_delay ? : 1);
+       if (ifp->flags & IFA_F_OPTIMISTIC)
+               rand_num = 0;
+       else
+               rand_num = net_random() % (idev->cnf.rtr_solicit_delay ? : 1);
+
        ifp->probes = idev->cnf.dad_transmits;
        addrconf_mod_timer(ifp, AC_DAD, rand_num);
 }
@@ -2537,6 +2552,9 @@ static void addrconf_dad_start(struct inet6_ifaddr *ifp, 
u32 flags)
        struct inet6_dev *idev = ifp->idev;
        struct net_device *dev = idev->dev;
 
+       if (!idev->cnf.optimistic_dad)
+               ifp->flags &= ~IFA_F_OPTIMISTIC;
+
        addrconf_join_solict(dev, &ifp->addr);
 
        if (ifp->prefix_len != 128 && (ifp->flags&IFA_F_PERMANENT))
@@ -2553,7 +2571,7 @@ static void addrconf_dad_start(struct inet6_ifaddr *ifp, 
u32 flags)
        if (dev->flags&(IFF_NOARP|IFF_LOOPBACK) ||
            !(ifp->flags&IFA_F_TENTATIVE) ||
            ifp->flags & IFA_F_NODAD) {
-               ifp->flags &= ~IFA_F_TENTATIVE;
+               ifp->flags &= ~(IFA_F_TENTATIVE|IFA_F_OPTIMISTIC);
                spin_unlock_bh(&ifp->lock);
                read_unlock_bh(&idev->lock);
 
@@ -2573,6 +2591,25 @@ static void addrconf_dad_start(struct inet6_ifaddr *ifp, 
u32 flags)
                addrconf_dad_stop(ifp);
                return;
        }
+
+       /*
+        * Forwarding devices (routers) should not use
+        * optimistic addresses
+        * Nor should interfaces that don't know the 
+        * Source address for their default gateway
+        * RFC 4429 Sec 3.3
+        */
+       if ((ipv6_devconf.forwarding) ||
+          (ifp->rt == NULL))
+               ifp->flags &= ~IFA_F_OPTIMISTIC;
+
+       /*
+        * Optimistic nodes need to join the anycast address
+        * right away
+        */
+       if (ifp->flags & IFA_F_OPTIMISTIC)
+               addrconf_join_anycast(ifp);
+
        addrconf_dad_kick(ifp);
        spin_unlock_bh(&ifp->lock);
 out:
@@ -2597,7 +2634,7 @@ static void addrconf_dad_timer(unsigned long data)
                 * DAD was successful
                 */
 
-               ifp->flags &= ~IFA_F_TENTATIVE;
+               ifp->flags &= ~(IFA_F_TENTATIVE|IFA_F_OPTIMISTIC);
                spin_unlock_bh(&ifp->lock);
                read_unlock_bh(&idev->lock);
 
@@ -2627,6 +2664,9 @@ static void addrconf_dad_completed(struct inet6_ifaddr 
*ifp)
         *      Configure the address for reception. Now it is valid.
         */
 
+       if (ifp->flags & IFA_F_OPTIMISTIC)
+               addrconf_leave_anycast(ifp);
+
        ipv6_ifa_notify(RTM_NEWADDR, ifp);
 
        /* If added prefix is link local and forwarding is off,
@@ -3398,6 +3438,7 @@ static void inline ipv6_store_devconf(struct ipv6_devconf 
*cnf,
 #endif
 #endif
        array[DEVCONF_PROXY_NDP] = cnf->proxy_ndp;
+       array[DEVCONF_OPTIMISTIC_DAD] = cnf->optimistic_dad;
 }
 
 static inline size_t inet6_if_nlmsg_size(void)
@@ -3918,6 +3959,15 @@ static struct addrconf_sysctl_table
                        .proc_handler   =       &proc_dointvec,
                },
                {
+                       .ctl_name       =       NET_IPV6_OPTIMISTIC_DAD,
+                       .procname       =       "optimistic_dad",
+                       .data           =       &ipv6_devconf.optimistic_dad,
+                       .maxlen         =       sizeof(int),
+                       .mode           =       0644,
+                       .proc_handler   =       &proc_dointvec,
+
+               },
+               {
                        .ctl_name       =       0,      /* sentinel */
                }
        },
diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
index 882cde4..9c5273c 100644
--- a/net/ipv6/mcast.c
+++ b/net/ipv6/mcast.c
@@ -1411,7 +1411,7 @@ static struct sk_buff *mld_newpack(struct net_device 
*dev, int size)
 
        skb_reserve(skb, LL_RESERVED_SPACE(dev));
 
-       if (ipv6_get_lladdr(dev, &addr_buf)) {
+       if (ipv6_get_lladdr(dev, &addr_buf, IFA_F_TENTATIVE)) {
                /* <draft-ietf-magma-mld-source-05.txt>:
                 * use unspecified address as the source address 
                 * when a valid link-local address is not available.
@@ -1789,7 +1789,7 @@ static void igmp6_send(struct in6_addr *addr, struct 
net_device *dev, int type)
 
        skb_reserve(skb, LL_RESERVED_SPACE(dev));
 
-       if (ipv6_get_lladdr(dev, &addr_buf)) {
+       if (ipv6_get_lladdr(dev, &addr_buf, IFA_F_TENTATIVE)) {
                /* <draft-ietf-magma-mld-source-05.txt>:
                 * use unspecified address as the source address 
                 * when a valid link-local address is not available.
diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
index 6a9f616..6ed0357 100644
--- a/net/ipv6/ndisc.c
+++ b/net/ipv6/ndisc.c
@@ -447,6 +447,8 @@ static void ndisc_send_na(struct net_device *dev, struct 
neighbour *neigh,
        ifp = ipv6_get_ifaddr(solicited_addr, dev, 1);
        if (ifp) {
                src_addr = solicited_addr;
+               if (ifp->flags & IFA_F_OPTIMISTIC)
+                       override = 0;
                in6_ifa_put(ifp);
        } else {
                if (ipv6_dev_get_saddr(dev, daddr, &tmpaddr))
@@ -498,7 +500,8 @@ static void ndisc_send_na(struct net_device *dev, struct 
neighbour *neigh,
         msg->icmph.icmp6_unused = 0;
         msg->icmph.icmp6_router    = router;
         msg->icmph.icmp6_solicited = solicited;
-        msg->icmph.icmp6_override  = override;
+       msg->icmph.icmp6_override  = override;
+
 
         /* Set the target address. */
        ipv6_addr_copy(&msg->target, solicited_addr);
@@ -542,7 +545,8 @@ void ndisc_send_ns(struct net_device *dev, struct neighbour 
*neigh,
        int send_llinfo;
 
        if (saddr == NULL) {
-               if (ipv6_get_lladdr(dev, &addr_buf))
+               if (ipv6_get_lladdr(dev, &addr_buf,
+                                   (IFA_F_TENTATIVE|IFA_F_OPTIMISTIC)))
                        return;
                saddr = &addr_buf;
        }
@@ -622,9 +626,21 @@ void ndisc_send_rs(struct net_device *dev, struct in6_addr 
*saddr,
         struct sk_buff *skb;
         struct icmp6hdr *hdr;
        __u8 * opt;
+       struct inet6_ifaddr *ifp;
+       int include_sllao_option = 1;
         int len;
        int err;
 
+       /*
+        * Check the source address.  If its OPTIMISTIC
+        * and addr_len is non-zero (implying the sllao option)
+        * then don't send the RS (RFC 4429, section 2.2)
+        */
+       ifp = ipv6_get_ifaddr(saddr, dev, 1);
+
+       if ((!ifp) || ((ifp->flags & IFA_F_OPTIMISTIC) && dev->addr_len))
+               include_sllao_option=0;
+
        ndisc_flow_init(&fl, NDISC_ROUTER_SOLICITATION, saddr, daddr,
                        dev->ifindex);
 
@@ -664,7 +680,7 @@ void ndisc_send_rs(struct net_device *dev, struct in6_addr 
*saddr,
 
        opt = (u8*) (hdr + 1);
 
-       if (dev->addr_len)
+       if (dev->addr_len && include_sllao_option)
                ndisc_fill_addr_option(opt, ND_OPT_SOURCE_LL_ADDR, 
dev->dev_addr,
                                       dev->addr_len, dev->type);
 
@@ -746,6 +762,7 @@ static void ndisc_recv_ns(struct sk_buff *skb)
        int dad = ipv6_addr_any(saddr);
        int inc;
        int is_router;
+       int type;
 
        if (ipv6_addr_is_multicast(&msg->target)) {
                ND_PRINTK2(KERN_WARNING 
@@ -796,28 +813,39 @@ static void ndisc_recv_ns(struct sk_buff *skb)
        inc = ipv6_addr_is_multicast(daddr);
 
        if ((ifp = ipv6_get_ifaddr(&msg->target, dev, 1)) != NULL) {
-               if (ifp->flags & IFA_F_TENTATIVE) {
-                       /* Address is tentative. If the source
-                          is unspecified address, it is someone
-                          does DAD, otherwise we ignore solicitations
-                          until DAD timer expires.
-                        */
-                       if (!dad)
+
+               if (ifp->flags & (IFA_F_TENTATIVE|IFA_F_OPTIMISTIC)) {
+                       if (dad) {
+                               if (dev->type == ARPHRD_IEEE802_TR) {
+                                       unsigned char *sadr = skb->mac.raw;
+                                       if (((sadr[8] ^ dev->dev_addr[0]) & 
0x7f) == 0 &&
+                                           sadr[9] == dev->dev_addr[1] &&
+                                           sadr[10] == dev->dev_addr[2] &&
+                                           sadr[11] == dev->dev_addr[3] &&
+                                           sadr[12] == dev->dev_addr[4] &&
+                                           sadr[13] == dev->dev_addr[5]) {
+                                               /* looped-back to us */
+                                               goto out;
+                                       }
+                               }
+
+                               /*
+                                * We are colliding with another node
+                                * who is doing DAD
+                                * so fail our DAD process
+                                */
+                               addrconf_dad_failure(ifp);
                                goto out;
-                       if (dev->type == ARPHRD_IEEE802_TR) {
-                               unsigned char *sadr = skb->mac.raw;
-                               if (((sadr[8] ^ dev->dev_addr[0]) & 0x7f) == 0 
&&
-                                   sadr[9] == dev->dev_addr[1] &&
-                                   sadr[10] == dev->dev_addr[2] &&
-                                   sadr[11] == dev->dev_addr[3] &&
-                                   sadr[12] == dev->dev_addr[4] &&
-                                   sadr[13] == dev->dev_addr[5]) {
-                                       /* looped-back to us */
+                       } else {
+                               /*
+                                * This is not a dad solicitation.
+                                * If we are an optimistic node, 
+                                * we should respond.  
+                                * Otherwise, we should ignore it. 
+                                */
+                               if (!(ifp->flags & IFA_F_OPTIMISTIC))
                                        goto out;
-                               }
                        }
-                       addrconf_dad_failure(ifp); 
-                       return;
                }
 
                idev = ifp->idev;
@@ -1406,7 +1434,7 @@ void ndisc_send_redirect(struct sk_buff *skb, struct 
neighbour *neigh,
 
        dev = skb->dev;
 
-       if (ipv6_get_lladdr(dev, &saddr_buf)) {
+       if (ipv6_get_lladdr(dev, &saddr_buf, IFA_F_TENTATIVE)) {
                ND_PRINTK2(KERN_WARNING
                           "ICMPv6 Redirect: no link-local address on %s\n",
                           dev->name);
-
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