dhcpv6: fix handling of infinite lifetimes

[project/odhcpd.git] / src / dhcpv6-ia.c

diff --git a/src/dhcpv6-ia.c b/src/dhcpv6-ia.c
index c97a079..de44581 100644 (file)
--- a/src/dhcpv6-ia.c
+++ b/src/dhcpv6-ia.c
@@ -219,7 +219,7 @@ void dhcpv6_write_statefile(void)
                        return;
 
                lockf(fd, F_LOCK, 0);
-               ftruncate(fd, 0);
+               if (ftruncate(fd, 0) < 0) {}
 
                FILE *fp = fdopen(fd, "w");
                if (!fp) {
@@ -254,11 +254,18 @@ void dhcpv6_write_statefile(void)
                                        struct in6_addr addr;
                                        struct odhcpd_ipaddr *addrs = (c->managed) ? c->managed : iface->ia_addr;
                                        size_t addrlen = (c->managed) ? (size_t)c->managed_size : iface->ia_addr_len;
+                                       size_t m = 0;
+
+                                       for (size_t i = 0; i < addrlen; ++i)
+                                               if (addrs[i].preferred > addrs[m].preferred ||
+                                                               (addrs[i].preferred == addrs[m].preferred &&
+                                                                               memcmp(&addrs[i].addr, &addrs[m].addr, 16) > 0))
+                                                       m = i;
 
                                        for (size_t i = 0; i < addrlen; ++i) {
-                                               if (addrs[i].prefix > 96)
-                                                       continue;
-                                               if (c->valid_until <= now)
+                                               if (addrs[i].prefix > 96 || c->valid_until <= now ||
+                                                               (iface->managed < RELAYD_MANAGED_NO_AFLAG && i != m &&
+                                                                               addrs[i].prefix == 64))
                                                        continue;
 
                                                addr = addrs[i].addr;
@@ -712,20 +719,28 @@ static size_t append_reply(uint8_t *buf, size_t buflen, uint16_t status,
 
                        struct odhcpd_ipaddr *addrs = (a->managed) ? a->managed : iface->ia_addr;
                        size_t addrlen = (a->managed) ? (size_t)a->managed_size : iface->ia_addr_len;
-                       size_t mostpref = 0;
+                       size_t m = 0;
 
                        for (size_t i = 0; i < addrlen; ++i)
-                               if (addrs[i].preferred > addrs[mostpref].preferred)
-                                       mostpref = i;
+                               if (addrs[i].preferred > addrs[m].preferred ||
+                                               (addrs[i].preferred == addrs[m].preferred &&
+                                                               memcmp(&addrs[i].addr, &addrs[m].addr, 16) > 0))
+                                       m = i;
 
                        for (size_t i = 0; i < addrlen; ++i) {
-                               uint32_t prefix_pref = addrs[i].preferred - now;
-                               uint32_t prefix_valid = addrs[i].valid - now;
+                               uint32_t prefix_pref = addrs[i].preferred;
+                               uint32_t prefix_valid = addrs[i].valid;
 
                                if (addrs[i].prefix > 96 ||
                                                addrs[i].preferred <= (uint32_t)now)
                                        continue;
 
+                               if (prefix_pref != UINT32_MAX)
+                                       prefix_pref -= now;
+
+                               if (prefix_valid != UINT32_MAX)
+                                       prefix_valid -= now;
+
                                if (a->length < 128) {
                                        struct dhcpv6_ia_prefix p = {
                                                .type = htons(DHCPV6_OPT_IA_PREFIX),
@@ -756,7 +771,8 @@ static size_t append_reply(uint8_t *buf, size_t buflen, uint16_t status,
                                        n.addr.s6_addr32[3] = htonl(a->assigned);
                                        size_t entrlen = sizeof(n) - 4;
 
-                                       if (iface->managed < RELAYD_MANAGED_NO_AFLAG && i != mostpref)
+                                       if (iface->managed < RELAYD_MANAGED_NO_AFLAG && i != m &&
+                                                       addrs[i].prefix == 64)
                                                continue;
 
                                        if (datalen + entrlen + 4 > buflen || a->assigned == 0)