Author: hrs
Date: Thu Mar  5 21:27:49 2015
New Revision: 279676
URL: https://svnweb.freebsd.org/changeset/base/279676

Log:
  - Implement loopback probing state in enhanced DAD algorithm.
  
  - Add no_dad and ignoreloop per-IF knob.  no_dad disables DAD completely,
    and ignoreloop is to prevent infinite loop in loopback probing state when
    loopback is permanently expected.

Modified:
  head/sbin/ifconfig/af_inet6.c
  head/sbin/ifconfig/af_nd6.c
  head/sbin/ifconfig/ifconfig.8
  head/sys/netinet6/in6.c
  head/sys/netinet6/nd6.h
  head/sys/netinet6/nd6_nbr.c

Modified: head/sbin/ifconfig/af_inet6.c
==============================================================================
--- head/sbin/ifconfig/af_inet6.c       Thu Mar  5 20:29:18 2015        
(r279675)
+++ head/sbin/ifconfig/af_inet6.c       Thu Mar  5 21:27:49 2015        
(r279676)
@@ -485,6 +485,10 @@ static struct cmd inet6_cmds[] = {
        DEF_CMD("-auto_linklocal",-ND6_IFF_AUTO_LINKLOCAL,setnd6flags),
        DEF_CMD("no_prefer_iface",ND6_IFF_NO_PREFER_IFACE,setnd6flags),
        DEF_CMD("-no_prefer_iface",-ND6_IFF_NO_PREFER_IFACE,setnd6flags),
+       DEF_CMD("no_dad",       ND6_IFF_NO_DAD,         setnd6flags),
+       DEF_CMD("-no_dad",      -ND6_IFF_NO_DAD,        setnd6flags),
+       DEF_CMD("ignoreloop",   ND6_IFF_IGNORELOOP,     setnd6flags),
+       DEF_CMD("-ignoreloop",  -ND6_IFF_IGNORELOOP,    setnd6flags),
        DEF_CMD_ARG("pltime",                           setip6pltime),
        DEF_CMD_ARG("vltime",                           setip6vltime),
        DEF_CMD("eui64",        0,                      setip6eui64),

Modified: head/sbin/ifconfig/af_nd6.c
==============================================================================
--- head/sbin/ifconfig/af_nd6.c Thu Mar  5 20:29:18 2015        (r279675)
+++ head/sbin/ifconfig/af_nd6.c Thu Mar  5 21:27:49 2015        (r279676)
@@ -58,7 +58,8 @@ static const char rcsid[] =
 #define        MAX_SYSCTL_TRY  5
 #define        ND6BITS "\020\001PERFORMNUD\002ACCEPT_RTADV\003PREFER_SOURCE" \
                "\004IFDISABLED\005DONT_SET_IFROUTE\006AUTO_LINKLOCAL" \
-               "\007NO_RADR\010NO_PREFER_IFACE\020DEFAULTIF"
+               "\007NO_RADR\010NO_PREFER_IFACE\011IGNORELOOP\012NO_DAD" \
+               "\020DEFAULTIF"
 
 static int isnd6defif(int);
 void setnd6flags(const char *, int, int, const struct afswtch *);

Modified: head/sbin/ifconfig/ifconfig.8
==============================================================================
--- head/sbin/ifconfig/ifconfig.8       Thu Mar  5 20:29:18 2015        
(r279675)
+++ head/sbin/ifconfig/ifconfig.8       Thu Mar  5 21:27:49 2015        
(r279676)
@@ -28,7 +28,7 @@
 .\"     From: @(#)ifconfig.8   8.3 (Berkeley) 1/5/94
 .\" $FreeBSD$
 .\"
-.Dd December 16, 2014
+.Dd March 6, 2015
 .Dt IFCONFIG 8
 .Os
 .Sh NAME
@@ -687,6 +687,20 @@ policy table, configurable with
 .It Cm -no_prefer_iface
 Clear a flag
 .Cm no_prefer_iface .
+.It Cm no_dad
+Set a flag to disable Duplicate Address Detection.
+.It Cm -no_dad
+Clear a flag
+.Cm no_dad .
+.It Cm ignoreloop
+Set a flag to disable loopback detection in Enhanced Duplicate Address
+Detection Algorithm.
+When this flag is set,
+Duplicate Address Detection will stop in a finite number of probings
+even if a loopback configuration is detected.
+.It Cm -ignoreloop
+Clear a flag
+.Cm ignoreloop .
 .El
 .Pp
 The following parameters are specific for IPv6 addresses.

Modified: head/sys/netinet6/in6.c
==============================================================================
--- head/sys/netinet6/in6.c     Thu Mar  5 20:29:18 2015        (r279675)
+++ head/sys/netinet6/in6.c     Thu Mar  5 21:27:49 2015        (r279676)
@@ -1910,7 +1910,8 @@ in6if_do_dad(struct ifnet *ifp)
        if ((ifp->if_flags & IFF_LOOPBACK) != 0)
                return (0);
 
-       if (ND_IFINFO(ifp)->flags & ND6_IFF_IFDISABLED)
+       if ((ND_IFINFO(ifp)->flags & ND6_IFF_IFDISABLED) ||
+           (ND_IFINFO(ifp)->flags & ND6_IFF_NO_DAD))
                return (0);
 
        /*

Modified: head/sys/netinet6/nd6.h
==============================================================================
--- head/sys/netinet6/nd6.h     Thu Mar  5 20:29:18 2015        (r279675)
+++ head/sys/netinet6/nd6.h     Thu Mar  5 21:27:49 2015        (r279676)
@@ -87,6 +87,8 @@ struct nd_ifinfo {
 #define ND6_IFF_AUTO_LINKLOCAL 0x20
 #define        ND6_IFF_NO_RADR         0x40
 #define ND6_IFF_NO_PREFER_IFACE        0x80 /* XXX: not related to ND. */
+#define ND6_IFF_IGNORELOOP     0x100
+#define ND6_IFF_NO_DAD         0x200
 
 #define        ND6_CREATE              LLE_CREATE
 #define        ND6_EXCLUSIVE           LLE_EXCLUSIVE

Modified: head/sys/netinet6/nd6_nbr.c
==============================================================================
--- head/sys/netinet6/nd6_nbr.c Thu Mar  5 20:29:18 2015        (r279675)
+++ head/sys/netinet6/nd6_nbr.c Thu Mar  5 21:27:49 2015        (r279676)
@@ -1182,6 +1182,7 @@ struct dadq {
        int dad_ns_icount;
        int dad_na_icount;
        int dad_ns_lcount;      /* looped back NS */
+       int dad_loopbackprobe;  /* probing state for loopback detection */
        struct callout dad_timer_ch;
        struct vnet *dad_vnet;
        u_int dad_refcnt;
@@ -1223,7 +1224,6 @@ static struct dadq *
 nd6_dad_find(struct ifaddr *ifa, struct nd_opt_nonce *n)
 {
        struct dadq *dp;
-       char ip6buf[INET6_ADDRSTRLEN];
 
        DADQ_RLOCK();
        TAILQ_FOREACH(dp, &V_dadq, dad_list) {
@@ -1238,10 +1238,6 @@ nd6_dad_find(struct ifaddr *ifa, struct 
                    n->nd_opt_nonce_len == (ND_OPT_NONCE_LEN + 2) / 8 &&
                    memcmp(&n->nd_opt_nonce[0], &dp->dad_nonce[0],
                        ND_OPT_NONCE_LEN) == 0) {
-                       log(LOG_ERR, "%s: a looped back NS message is "
-                           "detected during DAD for %s.\n",
-                           if_name(ifa->ifa_ifp),
-                           ip6_sprintf(ip6buf, IFA_IN6(ifa)));
                        dp->dad_ns_lcount++;
                        continue;
                }
@@ -1357,7 +1353,7 @@ nd6_dad_start(struct ifaddr *ifa, int de
        dp->dad_count = V_ip6_dad_count;
        dp->dad_ns_icount = dp->dad_na_icount = 0;
        dp->dad_ns_ocount = dp->dad_ns_tcount = 0;
-       dp->dad_ns_lcount = 0;
+       dp->dad_ns_lcount = dp->dad_loopbackprobe = 0;
        refcount_init(&dp->dad_refcnt, 1);
        nd6_dad_add(dp);
        if (delay == 0) {
@@ -1432,8 +1428,10 @@ nd6_dad_timer(struct dadq *dp)
                goto err;
        }
 
-       /* timeouted with IFF_{RUNNING,UP} check */
-       if (dp->dad_ns_tcount > V_dad_maxtry) {
+       /* Stop DAD if the interface is down even after dad_maxtry attempts. */
+       if ((dp->dad_ns_tcount > V_dad_maxtry) &&
+           (((ifp->if_flags & IFF_UP) == 0) ||
+            ((ifp->if_drv_flags & IFF_DRV_RUNNING) == 0))) {
                nd6log((LOG_INFO, "%s: could not run DAD, driver problem?\n",
                    if_name(ifa->ifa_ifp)));
                goto err;
@@ -1456,7 +1454,42 @@ nd6_dad_timer(struct dadq *dp)
                if (dp->dad_ns_icount > 0 || dp->dad_na_icount > 0)
                        /* We've seen NS or NA, means DAD has failed. */
                        nd6_dad_duplicated(ifa, dp);
-               else {
+               else if (V_dad_enhanced != 0 &&
+                   dp->dad_ns_lcount > 0 &&
+                   dp->dad_ns_lcount > dp->dad_loopbackprobe) {
+                       /*
+                        * A looped back probe is detected,
+                        * Sec. 4.1 in draft-ietf-6man-enhanced-dad-13
+                        * requires transmission of additional probes until
+                        * the loopback condition becomes clear.
+                        */
+                       log(LOG_ERR, "%s: a looped back NS message is "
+                           "detected during DAD for %s.  "
+                           "Another DAD probes are being sent.\n",
+                           if_name(ifa->ifa_ifp),
+                           ip6_sprintf(ip6buf, IFA_IN6(ifa)));
+                       dp->dad_loopbackprobe = dp->dad_ns_lcount;
+                       /*
+                        * An interface with IGNORELOOP is one which a
+                        * loopback is permanently expected while regular
+                        * traffic works.  In that case, stop DAD after
+                        * MAX_MULTICAST_SOLICIT number of NS messages
+                        * regardless of the number of received loopback NS
+                        * by increasing dad_loopbackprobe in advance.
+                        */
+                       if (ND_IFINFO(ifa->ifa_ifp)->flags & ND6_IFF_IGNORELOOP)
+                               dp->dad_loopbackprobe += V_nd6_mmaxtries;
+                       /*
+                        * Send an NS immediately and increase dad_count by
+                        * V_nd6_mmaxtries - 1.
+                        */
+                       nd6_dad_ns_output(dp, ifa);
+                       dp->dad_count =
+                           dp->dad_ns_ocount + V_nd6_mmaxtries - 1;
+                       nd6_dad_starttimer(dp,
+                           (long)ND_IFINFO(ifa->ifa_ifp)->retrans * hz / 1000);
+                       goto done;
+               } else {
                        /*
                         * We are done with DAD.  No NA came, no NS came.
                         * No duplicate address found.  Check IFDISABLED flag
@@ -1470,6 +1503,12 @@ nd6_dad_timer(struct dadq *dp)
                            "%s: DAD complete for %s - no duplicates found\n",
                            if_name(ifa->ifa_ifp),
                            ip6_sprintf(ip6buf, &ia->ia_addr.sin6_addr)));
+                       if (dp->dad_ns_lcount > 0)
+                               log(LOG_ERR, "%s: DAD completed while "
+                                   "a looped back NS message is detected "
+                                   "during DAD for %s.\n",
+                                   if_name(ifa->ifa_ifp),
+                                   ip6_sprintf(ip6buf, IFA_IN6(ifa)));
                }
        }
 err:
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