DHCP6: Persist configuration on confirm/rebind failure

only expire the lease once the last address has expired.
This is more in accordance with RFC8415 18.2.
Note, we still require an initial confirm/rebind on link state
change to ensure the configuration for link is valid.

Extending the lastlease in DHCP6 has been removed.

Fixes #174.

diff --git a/src/dhcp6.c b/src/dhcp6.c
index 217f82b9a12a075ae379bca87ea6598bb9b2b6a7..30300ce38caa1d49fffd07f87ce47e7383915af5 100644 (file)
--- a/src/dhcp6.c
+++ b/src/dhcp6.c
@@ -1745,40 +1745,13 @@ dhcp6_startdiscoinform(struct interface *ifp)
 }
 
 static void
-dhcp6_leaseextend(struct interface *ifp)
-{
-       struct dhcp6_state *state = D6_STATE(ifp);
-       struct ipv6_addr *ia;
-
-       logwarnx("%s: extending DHCPv6 lease", ifp->name);
-       TAILQ_FOREACH(ia, &state->addrs, next) {
-               ia->flags |= IPV6_AF_EXTENDED;
-               /* Set infinite lifetimes. */
-               ia->prefix_pltime = ND6_INFINITE_LIFETIME;
-               ia->prefix_vltime = ND6_INFINITE_LIFETIME;
-       }
-}
-
-static void
-dhcp6_fail(struct interface *ifp)
+dhcp6_fail(struct interface *ifp, bool drop)
 {
        struct dhcp6_state *state = D6_STATE(ifp);
 
        state->failed = true;
 
-       /* RFC3315 18.1.2 says that prior addresses SHOULD be used on failure.
-        * RFC2131 3.2.3 says that MAY chose to use the prior address.
-        * Because dhcpcd was written first for RFC2131, we have the LASTLEASE
-        * option which defaults to off as that makes the most sense for
-        * mobile clients.
-        * dhcpcd also has LASTLEASE_EXTEND to extend this lease past it's
-        * expiry, but this is strictly not RFC compliant in any way or form. */
-       if (state->new != NULL &&
-           ifp->options->options & DHCPCD_LASTLEASE_EXTEND)
-       {
-               dhcp6_leaseextend(ifp);
-               dhcp6_bind(ifp, NULL, NULL);
-       } else {
+       if (drop) {
                dhcp6_freedrop_addrs(ifp, 1, IPV6_AF_ANYDELEGATED, NULL);
 #ifndef SMALL
                dhcp6_delete_delegates(ifp);
@@ -1792,7 +1765,8 @@ dhcp6_fail(struct interface *ifp)
                        script_runreason(ifp, "EXPIRE6");
                dhcp_unlink(ifp->ctx, state->leasefile);
                dhcp6_addrequestedaddrs(ifp);
-       }
+       } else if (state->new)
+               script_runreason(ifp, "TIMEOUT6");
 
        if (!dhcp6_startdiscoinform(ifp)) {
                logwarnx("%s: no advertising IPv6 router wants DHCP",ifp->name);
@@ -1817,7 +1791,9 @@ dhcp6_failconfirm(void *arg)
 
        logmessage(llevel, "%s: failed to confirm prior DHCPv6 address",
            ifp->name);
-       dhcp6_fail(ifp);
+
+       /* RFC8415 18.2.3 says that prior addresses SHOULD be used on failure. */
+       dhcp6_fail(ifp, false);
 }
 
 static void
@@ -1827,7 +1803,7 @@ dhcp6_failrequest(void *arg)
        int llevel = dhcp6_failloglevel(ifp);
 
        logmessage(llevel, "%s: failed to request DHCPv6 address", ifp->name);
-       dhcp6_fail(ifp);
+       dhcp6_fail(ifp, true);
 }
 
 static void
@@ -1838,17 +1814,20 @@ dhcp6_failinform(void *arg)
 
        logmessage(llevel, "%s: failed to request DHCPv6 information",
            ifp->name);
-       dhcp6_fail(ifp);
+       dhcp6_fail(ifp, true);
 }
 
 #ifndef SMALL
 static void
-dhcp6_failrebind(void *arg)
+dhcp6_failrebindpd(void *arg)
 {
        struct interface *ifp = arg;
 
        logerrx("%s: failed to rebind prior DHCPv6 delegation", ifp->name);
-       dhcp6_fail(ifp);
+
+       /* RFC8415 18.2.3 says that prior addresses SHOULD be used on failure.
+        * 18.2 says REBIND rather than CONFIRM with PD but use CONFIRM timings. */
+       dhcp6_fail(ifp, false);
 }
 
 static int
@@ -1875,47 +1854,39 @@ dhcp6_startrebind(void *arg)
 {
        struct interface *ifp;
        struct dhcp6_state *state;
-#ifndef SMALL
-       int pd;
-#endif
 
        ifp = arg;
        eloop_timeout_delete(ifp->ctx->eloop, dhcp6_sendrenew, ifp);
        state = D6_STATE(ifp);
+
+       state->IMD = REB_MAX_DELAY;
+       state->IRT = REB_TIMEOUT;
+       state->MRT = REB_MAX_RT;
+       state->RTC = 0;
+       state->MRC = 0;
+
        if (state->state == DH6S_RENEW)
                logwarnx("%s: failed to renew DHCPv6, rebinding", ifp->name);
-       else
+       else {
                loginfox("%s: rebinding prior DHCPv6 lease", ifp->name);
-       state->state = DH6S_REBIND;
-       state->RTC = 0;
-       state->MRC = 0;
 
 #ifndef SMALL
-       /* RFC 3633 section 12.1 */
-       pd = dhcp6_hasprefixdelegation(ifp);
-       if (pd) {
-               state->IMD = CNF_MAX_DELAY;
-               state->IRT = CNF_TIMEOUT;
-               state->MRT = CNF_MAX_RT;
-       } else
+               /* RFC 8415 18.2.5 */
+               if (dhcp6_hasprefixdelegation(ifp)) {
+                       state->IMD = CNF_MAX_DELAY;
+                       state->IRT = CNF_TIMEOUT;
+                       state->MRT = CNF_MAX_RT;
+                       eloop_timeout_add_sec(ifp->ctx->eloop,
+                           CNF_MAX_RD, dhcp6_failrebindpd, ifp);
+               }
 #endif
-       {
-               state->IMD = REB_MAX_DELAY;
-               state->IRT = REB_TIMEOUT;
-               state->MRT = REB_MAX_RT;
        }
 
+       state->state = DH6S_REBIND;
        if (dhcp6_makemessage(ifp) == -1)
                logerr("%s: %s", __func__, ifp->name);
        else
                dhcp6_sendrebind(ifp);
-
-#ifndef SMALL
-       /* RFC 3633 section 12.1 */
-       if (pd)
-               eloop_timeout_add_sec(ifp->ctx->eloop,
-                   CNF_MAX_RD, dhcp6_failrebind, ifp);
-#endif
 }
 
 static void
@@ -1984,7 +1955,7 @@ dhcp6_startexpire(void *arg)
        eloop_timeout_delete(ifp->ctx->eloop, dhcp6_sendrebind, ifp);
 
        logerrx("%s: DHCPv6 lease expired", ifp->name);
-       dhcp6_fail(ifp);
+       dhcp6_fail(ifp, true);
 }
 
 static void
@@ -1993,7 +1964,7 @@ dhcp6_faildecline(void *arg)
        struct interface *ifp = arg;
 
        logerrx("%s: failed to decline duplicated DHCPv6 addresses", ifp->name);
-       dhcp6_fail(ifp);
+       dhcp6_fail(ifp, true);
 }
 
 static void
@@ -2686,8 +2657,7 @@ dhcp6_readlease(struct interface *ifp, int validate)
        }
 
        if (state->expire != ND6_INFINITE_LIFETIME &&
-           (time_t)state->expire < now - mtime &&
-           !(ifp->options->options & DHCPCD_LASTLEASE_EXTEND))
+           (time_t)state->expire < now - mtime)
        {
                logdebugx("%s: discarding expired lease", ifp->name);
                bytes = 0;
@@ -3475,7 +3445,7 @@ dhcp6_recvif(struct interface *ifp, const char *sfrom,
                         * acknowledgement of one. */
                        loginfox("%s: %s acknowledged DECLINE6",
                            ifp->name, sfrom);
-                       dhcp6_fail(ifp);
+                       dhcp6_fail(ifp, true);
                        return;
                default:
                        valid_op = false;