zebra: justify some IPv6 ND RA timers wrt RFC
There was a regression introduced with the previous commit:
"ipv6 nd home-agent-lifetime 1800000" appeared by default in every
interface section of running-config, although this command is
invalid in this context. Troubleshooting and bugfixing of the issue
tracked out several bugs in router advertisement procedures, some of
which are fixed in this commit.
* zebra/interface.c
* if_zebra_new_hook(): update to treat -1 as "uninitialized"
* nd_dump_vty(): idem
* zebra/rtadv.c
* rtadv_send_packet(): update processing of "router lifetime" field,
"home agent" option and "home agent lifetime" field to conform to
RFC6275 better
* ipv6_nd_ra_interval_msec(): update MaxRtrAdvInterval range check,
make sure it never exceeds (initialized) AdvDefaultLifetime
* ipv6_nd_ra_interval(): idem
* ipv6_nd_ra_lifetime(): update AdvDefaultLifetime range check, make
sure it never falls below MaxRtrAdvInterval
* ipv6_nd_homeagent_lifetime(): update HomeAgentLifetime range check
* no_ipv6_nd_ra_lifetime(): update to treat -1 as "uninitialized"
* no_ipv6_nd_homeagent_lifetime(): idem
* rtadv_config_write(): idem
diff --git a/zebra/rtadv.c b/zebra/rtadv.c
index bc1abca..01f8833 100644
--- a/zebra/rtadv.c
+++ b/zebra/rtadv.c
@@ -163,6 +163,7 @@
struct rtadv_prefix *rprefix;
u_char all_nodes_addr[] = {0xff,0x02,0,0,0,0,0,0,0,0,0,0,0,0,0,1};
struct listnode *node;
+ u_int16_t pkt_RouterLifetime;
/*
* Allocate control message bufffer. This is dynamic because
@@ -215,13 +216,32 @@
rtadv->nd_ra_flags_reserved |= ND_RA_FLAG_OTHER;
if (zif->rtadv.AdvHomeAgentFlag)
rtadv->nd_ra_flags_reserved |= ND_RA_FLAG_HOME_AGENT;
- rtadv->nd_ra_router_lifetime = htons (zif->rtadv.AdvDefaultLifetime);
+ /* Note that according to Neighbor Discovery (RFC 4861 [18]),
+ * AdvDefaultLifetime is by default based on the value of
+ * MaxRtrAdvInterval. AdvDefaultLifetime is used in the Router Lifetime
+ * field of Router Advertisements. Given that this field is expressed
+ * in seconds, a small MaxRtrAdvInterval value can result in a zero
+ * value for this field. To prevent this, routers SHOULD keep
+ * AdvDefaultLifetime in at least one second, even if the use of
+ * MaxRtrAdvInterval would result in a smaller value. -- RFC6275, 7.5 */
+ pkt_RouterLifetime = zif->rtadv.AdvDefaultLifetime != -1 ?
+ zif->rtadv.AdvDefaultLifetime :
+ MAX (1, 0.003 * zif->rtadv.MaxRtrAdvInterval);
+ rtadv->nd_ra_router_lifetime = htons (pkt_RouterLifetime);
rtadv->nd_ra_reachable = htonl (zif->rtadv.AdvReachableTime);
rtadv->nd_ra_retransmit = htonl (0);
len = sizeof (struct nd_router_advert);
- if (zif->rtadv.AdvHomeAgentFlag)
+ /* If both the Home Agent Preference and Home Agent Lifetime are set to
+ * their default values specified above, this option SHOULD NOT be
+ * included in the Router Advertisement messages sent by this home
+ * agent. -- RFC6275, 7.4 */
+ if
+ (
+ zif->rtadv.AdvHomeAgentFlag &&
+ (zif->rtadv.HomeAgentPreference || zif->rtadv.HomeAgentLifetime != -1)
+ )
{
struct nd_opt_homeagent_info *ndopt_hai =
(struct nd_opt_homeagent_info *)(buf + len);
@@ -229,7 +249,17 @@
ndopt_hai->nd_opt_hai_len = 1;
ndopt_hai->nd_opt_hai_reserved = 0;
ndopt_hai->nd_opt_hai_preference = htons(zif->rtadv.HomeAgentPreference);
- ndopt_hai->nd_opt_hai_lifetime = htons(zif->rtadv.HomeAgentLifetime);
+ /* 16-bit unsigned integer. The lifetime associated with the home
+ * agent in units of seconds. The default value is the same as the
+ * Router Lifetime, as specified in the main body of the Router
+ * Advertisement. The maximum value corresponds to 18.2 hours. A
+ * value of 0 MUST NOT be used. -- RFC6275, 7.5 */
+ ndopt_hai->nd_opt_hai_lifetime = htons
+ (
+ zif->rtadv.HomeAgentLifetime != -1 ?
+ zif->rtadv.HomeAgentLifetime :
+ MAX (1, pkt_RouterLifetime) /* 0 is OK for RL, but not for HAL*/
+ );
len += sizeof(struct nd_opt_homeagent_info);
}
@@ -389,6 +419,8 @@
zif->rtadv.AdvIntervalTimer -= period;
if (zif->rtadv.AdvIntervalTimer <= 0)
{
+ /* FIXME: using MaxRtrAdvInterval each time isn't what section
+ 6.2.4 of RFC4861 tells to do. */
zif->rtadv.AdvIntervalTimer = zif->rtadv.MaxRtrAdvInterval;
rtadv_send_packet (rtadv->sock, ifp);
}
@@ -707,7 +739,11 @@
interval = atoi (argv[0]);
- if (interval <= 0)
+ if
+ (
+ interval < 70 || interval > 1800000 ||
+ (zif->rtadv.AdvDefaultLifetime != -1 && interval > zif->rtadv.AdvDefaultLifetime * 1000)
+ )
{
vty_out (vty, "Invalid Router Advertisement Interval%s", VTY_NEWLINE);
return CMD_WARNING;
@@ -743,7 +779,11 @@
interval = atoi (argv[0]);
- if (interval <= 0)
+ if
+ (
+ interval < 1 || interval > 1800 ||
+ (zif->rtadv.AdvDefaultLifetime != -1 && interval > zif->rtadv.AdvDefaultLifetime)
+ )
{
vty_out (vty, "Invalid Router Advertisement Interval%s", VTY_NEWLINE);
return CMD_WARNING;
@@ -803,7 +843,15 @@
lifetime = atoi (argv[0]);
- if (lifetime < 0 || lifetime > 0xffff)
+ /* The value to be placed in the Router Lifetime field
+ * of Router Advertisements sent from the interface,
+ * in seconds. MUST be either zero or between
+ * MaxRtrAdvInterval and 9000 seconds. -- RFC4861, 6.2.1 */
+ if
+ (
+ lifetime > RTADV_MAX_RTRLIFETIME ||
+ (lifetime != 0 && lifetime * 1000 < zif->rtadv.MaxRtrAdvInterval)
+ )
{
vty_out (vty, "Invalid Router Lifetime%s", VTY_NEWLINE);
return CMD_WARNING;
@@ -828,7 +876,7 @@
ifp = (struct interface *) vty->index;
zif = ifp->info;
- zif->rtadv.AdvDefaultLifetime = RTADV_ADV_DEFAULT_LIFETIME;
+ zif->rtadv.AdvDefaultLifetime = -1;
return CMD_SUCCESS;
}
@@ -944,7 +992,7 @@
ha_ltime = (u_int32_t) atol (argv[0]);
- if (ha_ltime > RTADV_MAX_HALIFETIME)
+ if (ha_ltime < 1 || ha_ltime > RTADV_MAX_HALIFETIME)
{
vty_out (vty, "Invalid Home Agent Lifetime time%s", VTY_NEWLINE);
return CMD_WARNING;
@@ -969,7 +1017,7 @@
ifp = (struct interface *) vty->index;
zif = ifp->info;
- zif->rtadv.HomeAgentLifetime = 0;
+ zif->rtadv.HomeAgentLifetime = -1;
return CMD_SUCCESS;
}
@@ -1514,7 +1562,7 @@
if (zif->rtadv.AdvIntervalOption)
vty_out (vty, " ipv6 nd adv-interval-option%s", VTY_NEWLINE);
- if (zif->rtadv.AdvDefaultLifetime != RTADV_ADV_DEFAULT_LIFETIME)
+ if (zif->rtadv.AdvDefaultLifetime != -1)
vty_out (vty, " ipv6 nd ra-lifetime %d%s", zif->rtadv.AdvDefaultLifetime,
VTY_NEWLINE);
@@ -1522,7 +1570,7 @@
vty_out (vty, " ipv6 nd home-agent-preference %u%s",
zif->rtadv.HomeAgentPreference, VTY_NEWLINE);
- if (zif->rtadv.HomeAgentLifetime)
+ if (zif->rtadv.HomeAgentLifetime != -1)
vty_out (vty, " ipv6 nd home-agent-lifetime %u%s",
zif->rtadv.HomeAgentLifetime, VTY_NEWLINE);