]> git.decadent.org.uk Git - odhcp6c.git/blobdiff - src/dhcpv6.c
Switch to a leaner MD5 library
[odhcp6c.git] / src / dhcpv6.c
index 1deb10e4b1efd11f5f9e3b70c68be60fcdcfb0ce..5a6fd8303646a8f1902ba9d8ff42c4e8642cef6b 100644 (file)
 #define DHCPV6_DUID_LLADDR 3
 #define DHCPV6_REQ_DELAY 1
 
+#define DHCPV6_SOL_MAX_RT_MIN 60
+#define DHCPV6_SOL_MAX_RT_MAX 86400
+#define DHCPV6_INF_MAX_RT_MIN 60
+#define DHCPV6_INF_MAX_RT_MAX 86400
 
 static bool dhcpv6_response_is_valid(const void *buf, ssize_t len,
-               const uint8_t transaction[3], enum dhcpv6_msg type);
+               const uint8_t transaction[3], enum dhcpv6_msg type,
+               const struct in6_addr *daddr);
 
 static int dhcpv6_parse_ia(void *opt, void *end);
 
@@ -57,6 +62,8 @@ static void dhcpv6_handle_ia_status_code(const enum dhcpv6_msg orig,
                const void *status_msg, const int len,
                bool handled_status_codes[_DHCPV6_Status_Max],
                int *ret);
+static void dhcpv6_add_server_cand(const struct dhcpv6_server_cand *cand);
+static void dhcpv6_clear_all_server_cand(void);
 
 static reply_handler dhcpv6_handle_reply;
 static reply_handler dhcpv6_handle_advert;
@@ -70,17 +77,17 @@ static int dhcpv6_commit_advert(void);
 static struct dhcpv6_retx dhcpv6_retx[_DHCPV6_MSG_MAX] = {
        [DHCPV6_MSG_UNKNOWN] = {false, 1, 120, 0, "<POLL>",
                        dhcpv6_handle_reconfigure, NULL},
-       [DHCPV6_MSG_SOLICIT] = {true, 1, 3600, 0, "SOLICIT",
+       [DHCPV6_MSG_SOLICIT] = {true, 1, DHCPV6_SOL_MAX_RT, 0, "SOLICIT",
                        dhcpv6_handle_advert, dhcpv6_commit_advert},
-       [DHCPV6_MSG_REQUEST] = {true, 1, 30, 10, "REQUEST",
+       [DHCPV6_MSG_REQUEST] = {true, 1, DHCPV6_REQ_MAX_RT, 10, "REQUEST",
                        dhcpv6_handle_reply, NULL},
-       [DHCPV6_MSG_RENEW] = {false, 10, 600, 0, "RENEW",
+       [DHCPV6_MSG_RENEW] = {false, 10, DHCPV6_REN_MAX_RT, 0, "RENEW",
                        dhcpv6_handle_reply, NULL},
-       [DHCPV6_MSG_REBIND] = {false, 10, 600, 0, "REBIND",
+       [DHCPV6_MSG_REBIND] = {false, 10, DHCPV6_REB_MAX_RT, 0, "REBIND",
                        dhcpv6_handle_rebind_reply, NULL},
        [DHCPV6_MSG_RELEASE] = {false, 1, 0, 5, "RELEASE", NULL, NULL},
        [DHCPV6_MSG_DECLINE] = {false, 1, 0, 5, "DECLINE", NULL, NULL},
-       [DHCPV6_MSG_INFO_REQ] = {true, 1, 120, 0, "INFOREQ",
+       [DHCPV6_MSG_INFO_REQ] = {true, 1, DHCPV6_INF_MAX_RT, 0, "INFOREQ",
                        dhcpv6_handle_reply, NULL},
 };
 
@@ -99,18 +106,19 @@ static bool accept_reconfig = false;
 static uint8_t reconf_key[16];
 
 
-
 int init_dhcpv6(const char *ifname, int request_pd, int sol_timeout)
 {
        request_prefix = request_pd;
        dhcpv6_retx[DHCPV6_MSG_SOLICIT].max_timeo = sol_timeout;
 
        sock = socket(AF_INET6, SOCK_DGRAM | SOCK_CLOEXEC, IPPROTO_UDP);
+       if (sock < 0)
+               return -1;
 
        // Detect interface
        struct ifreq ifr;
        strncpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
-       if (ioctl(sock, SIOCGIFINDEX, &ifr))
+       if (ioctl(sock, SIOCGIFINDEX, &ifr) < 0)
                return -1;
        ifindex = ifr.ifr_ifindex;
 
@@ -118,10 +126,11 @@ int init_dhcpv6(const char *ifname, int request_pd, int sol_timeout)
        size_t client_id_len;
        odhcp6c_get_state(STATE_CLIENT_ID, &client_id_len);
        if (client_id_len == 0) {
-               ioctl(sock, SIOCGIFHWADDR, &ifr);
                uint8_t duid[14] = {0, DHCPV6_OPT_CLIENTID, 0, 10, 0,
                                DHCPV6_DUID_LLADDR, 0, 1};
-               memcpy(&duid[8], ifr.ifr_hwaddr.sa_data, ETHER_ADDR_LEN);
+
+               if (ioctl(sock, SIOCGIFHWADDR, &ifr) >= 0)
+                       memcpy(&duid[8], ifr.ifr_hwaddr.sa_data, ETHER_ADDR_LEN);
 
                uint8_t zero[ETHER_ADDR_LEN] = {0, 0, 0, 0, 0, 0};
                struct ifreq ifs[100], *ifp, *ifend;
@@ -134,10 +143,12 @@ int init_dhcpv6(const char *ifname, int request_pd, int sol_timeout)
                        // If our interface doesn't have an address...
                        ifend = ifs + (ifc.ifc_len / sizeof(struct ifreq));
                        for (ifp = ifc.ifc_req; ifp < ifend &&
-                                       !memcmp(&duid[8], zero, 6); ifp++) {
+                                       !memcmp(&duid[8], zero, ETHER_ADDR_LEN); ifp++) {
                                memcpy(ifr.ifr_name, ifp->ifr_name,
                                                sizeof(ifr.ifr_name));
-                               ioctl(sock, SIOCGIFHWADDR, &ifr);
+                               if (ioctl(sock, SIOCGIFHWADDR, &ifr) < 0)
+                                       continue;
+
                                memcpy(&duid[8], ifr.ifr_hwaddr.sa_data,
                                                ETHER_ADDR_LEN);
                        }
@@ -153,27 +164,28 @@ int init_dhcpv6(const char *ifname, int request_pd, int sol_timeout)
                        htons(DHCPV6_OPT_DNS_SERVERS),
                        htons(DHCPV6_OPT_DNS_DOMAIN),
                        htons(DHCPV6_OPT_NTP_SERVER),
-                       htons(DHCPV6_OPT_SIP_SERVER_A),
                        htons(DHCPV6_OPT_AFTR_NAME),
                        htons(DHCPV6_OPT_PD_EXCLUDE),
+                       htons(DHCPV6_OPT_SOL_MAX_RT),
+                       htons(DHCPV6_OPT_INF_MAX_RT),
 #ifdef EXT_PREFIX_CLASS
                        htons(DHCPV6_OPT_PREFIX_CLASS),
 #endif
        };
        odhcp6c_add_state(STATE_ORO, oro, sizeof(oro));
 
-
        // Configure IPv6-options
        int val = 1;
        setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, &val, sizeof(val));
        setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &val, sizeof(val));
+       setsockopt(sock, IPPROTO_IPV6, IPV6_RECVPKTINFO, &val, sizeof(val));
        val = 0;
        setsockopt(sock, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &val, sizeof(val));
        setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE, ifname, strlen(ifname));
 
        struct sockaddr_in6 client_addr = { .sin6_family = AF_INET6,
                .sin6_port = htons(DHCPV6_CLIENT_PORT), .sin6_flowinfo = 0 };
-       if (bind(sock, (struct sockaddr*)&client_addr, sizeof(client_addr)))
+       if (bind(sock, (struct sockaddr*)&client_addr, sizeof(client_addr)) < 0)
                return -1;
 
        return 0;
@@ -372,7 +384,7 @@ static int64_t dhcpv6_rand_delay(int64_t time)
 
 int dhcpv6_request(enum dhcpv6_msg type)
 {
-       uint8_t buf[1536], rc = 0;
+       uint8_t rc = 0;
        uint64_t timeout = UINT32_MAX;
        struct dhcpv6_retx *retx = &dhcpv6_retx[type];
 
@@ -439,8 +451,14 @@ int dhcpv6_request(enum dhcpv6_msg type)
                }
 
                // Receive rounds
-               for (; len < 0 && round_start < round_end;
+               for (; len < 0 && (round_start < round_end);
                                round_start = odhcp6c_get_milli_time()) {
+                       uint8_t buf[1536], cmsg_buf[CMSG_SPACE(sizeof(struct in6_pktinfo))];
+                       struct iovec iov = {buf, sizeof(buf)};
+                       struct msghdr msg = {NULL, 0, &iov, 1,
+                                       cmsg_buf, sizeof(cmsg_buf), 0};
+                       struct in6_pktinfo *pktinfo = NULL;
+
                        // Check for pending signal
                        if (odhcp6c_signal_process())
                                return -1;
@@ -452,27 +470,43 @@ int dhcpv6_request(enum dhcpv6_msg type)
                                        &timeout, sizeof(timeout));
 
                        // Receive cycle
-                       len = recv(sock, buf, sizeof(buf), 0);
+                       len = recvmsg(sock, &msg, 0);
+                       if (len < 0)
+                               continue;
 
-                       if (!dhcpv6_response_is_valid(buf, len, trid, type))
+                       for (struct cmsghdr *ch = CMSG_FIRSTHDR(&msg); ch != NULL;
+                               ch = CMSG_NXTHDR(&msg, ch)) {
+                               if (ch->cmsg_level == SOL_IPV6 &&
+                                       ch->cmsg_type == IPV6_PKTINFO) {
+                                       pktinfo = (struct in6_pktinfo *)CMSG_DATA(ch);
+                                       break;
+                               }
+                       }
+
+                       if (pktinfo == NULL) {
                                len = -1;
+                               continue;
+                       }
 
-                       if (len > 0) {
-                               uint8_t *opt = &buf[4];
-                               uint8_t *opt_end = opt + len - 4;
+                       if (!dhcpv6_response_is_valid(buf, len, trid,
+                                                       type, &pktinfo->ipi6_addr)) {
+                               len = -1;
+                               continue;
+                       }
 
-                               round_start = odhcp6c_get_milli_time();
-                               elapsed = round_start - start;
-                               syslog(LOG_NOTICE, "Got a valid reply after "
-                                               "%llums", (unsigned long long)elapsed);
+                       uint8_t *opt = &buf[4];
+                       uint8_t *opt_end = opt + len - 4;
 
-                               if (retx->handler_reply)
-                                       len = retx->handler_reply(
-                                                       type, rc, opt, opt_end);
+                       round_start = odhcp6c_get_milli_time();
+                       elapsed = round_start - start;
+                       syslog(LOG_NOTICE, "Got a valid reply after "
+                                       "%llums", (unsigned long long)elapsed);
 
-                               if (len > 0 && round_end - round_start > 1000)
-                                       round_end = 1000 + round_start;
-                       }
+                       if (retx->handler_reply)
+                               len = retx->handler_reply(type, rc, opt, opt_end);
+
+                       if (len > 0 && round_end - round_start > 1000)
+                               round_end = 1000 + round_start;
                }
 
                // Allow
@@ -483,9 +517,10 @@ int dhcpv6_request(enum dhcpv6_msg type)
        return len;
 }
 
-
+// Message validation checks according to RFC3315 chapter 15
 static bool dhcpv6_response_is_valid(const void *buf, ssize_t len,
-               const uint8_t transaction[3], enum dhcpv6_msg type)
+               const uint8_t transaction[3], enum dhcpv6_msg type,
+               const struct in6_addr *daddr)
 {
        const struct dhcpv6_header *rep = buf;
        if (len < (ssize_t)sizeof(*rep) || memcmp(rep->tr_id,
@@ -503,9 +538,11 @@ static bool dhcpv6_response_is_valid(const void *buf, ssize_t len,
                return false;
        }
 
-       uint8_t *end = ((uint8_t*)buf) + len, *odata;
-       uint16_t otype, olen;
-       bool clientid_ok = false, serverid_ok = false, rcauth_ok = false;
+       uint8_t *end = ((uint8_t*)buf) + len, *odata = NULL,
+               rcmsg = DHCPV6_MSG_UNKNOWN;
+       uint16_t otype, olen = UINT16_MAX;
+       bool clientid_ok = false, serverid_ok = false, rcauth_ok = false,
+               ia_present = false, options_valid = true;
 
        size_t client_id_len, server_id_len;
        void *client_id = odhcp6c_get_state(STATE_CLIENT_ID, &client_id_len);
@@ -516,15 +553,18 @@ static bool dhcpv6_response_is_valid(const void *buf, ssize_t len,
                        clientid_ok = (olen + 4U == client_id_len) && !memcmp(
                                        &odata[-4], client_id, client_id_len);
                } else if (otype == DHCPV6_OPT_SERVERID) {
-                       serverid_ok = (olen + 4U == server_id_len) && !memcmp(
-                                       &odata[-4], server_id, server_id_len);
+                       if (server_id_len)
+                               serverid_ok = (olen + 4U == server_id_len) && !memcmp(
+                                               &odata[-4], server_id, server_id_len);
+                       else
+                               serverid_ok = true;
                } else if (otype == DHCPV6_OPT_AUTH && olen == -4 +
                                sizeof(struct dhcpv6_auth_reconfigure)) {
                        struct dhcpv6_auth_reconfigure *r = (void*)&odata[-4];
                        if (r->protocol != 3 || r->algorithm != 1 || r->reconf_type != 2)
                                continue;
 
-                       md5_state_t md5;
+                       md5_ctx_t md5;
                        uint8_t serverhash[16], secretbytes[16], hash[16];
                        memcpy(serverhash, r->key, sizeof(serverhash));
                        memset(r->key, 0, sizeof(r->key));
@@ -533,29 +573,50 @@ static bool dhcpv6_response_is_valid(const void *buf, ssize_t len,
                        for (size_t i = 0; i < sizeof(secretbytes); ++i)
                                secretbytes[i] ^= 0x36;
 
-                       md5_init(&md5);
-                       md5_append(&md5, secretbytes, sizeof(secretbytes));
-                       md5_append(&md5, buf, len);
-                       md5_finish(&md5, hash);
+                       md5_begin(&md5);
+                       md5_hash(secretbytes, sizeof(secretbytes), &md5);
+                       md5_hash(buf, len, &md5);
+                       md5_end(hash, &md5);
 
                        for (size_t i = 0; i < sizeof(secretbytes); ++i) {
                                secretbytes[i] ^= 0x36;
                                secretbytes[i] ^= 0x5c;
                        }
 
-                       md5_init(&md5);
-                       md5_append(&md5, secretbytes, sizeof(secretbytes));
-                       md5_append(&md5, hash, 16);
-                       md5_finish(&md5, hash);
+                       md5_begin(&md5);
+                       md5_hash(secretbytes, sizeof(secretbytes), &md5);
+                       md5_hash(hash, 16, &md5);
+                       md5_end(hash, &md5);
 
                        rcauth_ok = !memcmp(hash, serverhash, sizeof(hash));
+               } else if (otype == DHCPV6_OPT_RECONF_MESSAGE && olen == 1) {
+                       rcmsg = odata[0];
+               } else if ((otype == DHCPV6_OPT_IA_PD || otype == DHCPV6_OPT_IA_NA)) {
+                       ia_present = true;
+                       if (olen < sizeof(struct dhcpv6_ia_hdr))
+                               options_valid = false;
+               }
+               else if ((otype == DHCPV6_OPT_IA_ADDR) || (otype == DHCPV6_OPT_IA_PREFIX) ||
+                               (otype == DHCPV6_OPT_PD_EXCLUDE)) {
+                       // Options are not allowed on global level
+                       options_valid = false;
                }
        }
 
-       if (rep->msg_type == DHCPV6_MSG_RECONF && !rcauth_ok)
+       if (!options_valid || ((odata + olen) > end))
                return false;
 
-       return clientid_ok && (serverid_ok || server_id_len == 0);
+       if (type == DHCPV6_MSG_INFO_REQ && ia_present)
+               return false;
+
+       if (rep->msg_type == DHCPV6_MSG_RECONF) {
+               if ((rcmsg != DHCPV6_MSG_RENEW && rcmsg != DHCPV6_MSG_INFO_REQ) ||
+                       (rcmsg == DHCPV6_MSG_INFO_REQ && ia_present) ||
+                       !rcauth_ok || IN6_IS_ADDR_MULTICAST(daddr))
+                       return false;
+       }
+
+       return clientid_ok && serverid_ok;
 }
 
 
@@ -572,7 +633,6 @@ int dhcpv6_poll_reconfigure(void)
 static int dhcpv6_handle_reconfigure(_unused enum dhcpv6_msg orig, const int rc,
                const void *opt, const void *end)
 {
-       // TODO: should verify the reconfigure message
        uint16_t otype, olen;
        uint8_t *odata, msg = DHCPV6_MSG_RENEW;
        dhcpv6_for_each_option(opt, end, otype, olen, odata)
@@ -592,7 +652,9 @@ static int dhcpv6_handle_advert(enum dhcpv6_msg orig, const int rc,
 {
        uint16_t olen, otype;
        uint8_t *odata, pref = 0;
-       struct dhcpv6_server_cand cand = {false, false, 0, 0, {0}, NULL, NULL, 0, 0};
+       struct dhcpv6_server_cand cand = {false, false, 0, 0, {0},
+                                       DHCPV6_SOL_MAX_RT,
+                                       DHCPV6_INF_MAX_RT, NULL, NULL, 0, 0};
        bool have_na = false;
        int have_pd = 0;
 
@@ -613,17 +675,9 @@ static int dhcpv6_handle_advert(enum dhcpv6_msg orig, const int rc,
                        switch (error) {
                        case DHCPV6_NoPrefixAvail:
                                // Status code on global level
-                               if (pd_mode == IA_MODE_FORCE)
-                                       return -1;
                                cand.preference -= 2000;
                                break;
 
-                       case DHCPV6_NoAddrsAvail:
-                               // Status code on global level
-                               if (na_mode == IA_MODE_FORCE)
-                                       return -1;
-                               break;
-
                        default :
                                break;
                        }
@@ -632,6 +686,16 @@ static int dhcpv6_handle_advert(enum dhcpv6_msg orig, const int rc,
                        cand.preference = pref = odata[0];
                } else if (otype == DHCPV6_OPT_RECONF_ACCEPT) {
                        cand.wants_reconfigure = true;
+               } else if (otype == DHCPV6_OPT_SOL_MAX_RT && olen == 4) {
+                       uint32_t sol_max_rt = ntohl(*((uint32_t *)odata));
+                       if (sol_max_rt >= DHCPV6_SOL_MAX_RT_MIN && 
+                                       sol_max_rt <= DHCPV6_SOL_MAX_RT_MAX)
+                               cand.sol_max_rt = sol_max_rt;
+               } else if (otype == DHCPV6_OPT_INF_MAX_RT && olen == 4) {
+                       uint32_t inf_max_rt = ntohl(*((uint32_t *)odata));
+                       if (inf_max_rt >= DHCPV6_INF_MAX_RT_MIN && 
+                                       inf_max_rt <= DHCPV6_INF_MAX_RT_MAX)
+                               cand.inf_max_rt = inf_max_rt;
                } else if (otype == DHCPV6_OPT_IA_PD && request_prefix) {
                        struct dhcpv6_ia_hdr *h = (struct dhcpv6_ia_hdr*)&odata[-4];
                        uint8_t *oend = odata + olen, *d;
@@ -652,8 +716,16 @@ static int dhcpv6_handle_advert(enum dhcpv6_msg orig, const int rc,
        }
 
        if ((!have_na && na_mode == IA_MODE_FORCE) ||
-                       (!have_pd && pd_mode == IA_MODE_FORCE))
+                       (!have_pd && pd_mode == IA_MODE_FORCE)) {
+               /* 
+                * RFC7083 states to process the SOL_MAX_RT and 
+                * INF_MAX_RT options even if the DHCPv6 server
+                * did not propose any IA_NA and/or IA_PD
+                */
+               dhcpv6_retx[DHCPV6_MSG_SOLICIT].max_timeo = cand.sol_max_rt;
+               dhcpv6_retx[DHCPV6_MSG_INFO_REQ].max_timeo = cand.inf_max_rt;
                return -1;
+       }
 
        if (na_mode != IA_MODE_NONE && !have_na) {
                cand.has_noaddravail = true;
@@ -670,12 +742,7 @@ static int dhcpv6_handle_advert(enum dhcpv6_msg orig, const int rc,
        if (cand.duid_len > 0) {
                cand.ia_na = odhcp6c_move_state(STATE_IA_NA, &cand.ia_na_len);
                cand.ia_pd = odhcp6c_move_state(STATE_IA_PD, &cand.ia_pd_len);
-               odhcp6c_add_state(STATE_SERVER_CAND, &cand, sizeof(cand));
-       }
-
-       if (orig == DHCPV6_MSG_SOLICIT) {
-               odhcp6c_clear_state(STATE_IA_NA);
-               odhcp6c_clear_state(STATE_IA_PD);
+               dhcpv6_add_server_cand(&cand);
        }
 
        return (rc > 1 || (pref == 255 && cand.preference > 0)) ? 1 : -1;
@@ -684,49 +751,7 @@ static int dhcpv6_handle_advert(enum dhcpv6_msg orig, const int rc,
 
 static int dhcpv6_commit_advert(void)
 {
-       size_t cand_len;
-       struct dhcpv6_server_cand *c = NULL, *cand =
-                       odhcp6c_get_state(STATE_SERVER_CAND, &cand_len);
-
-       bool retry = false;
-       for (size_t i = 0; i < cand_len / sizeof(*c); ++i) {
-               if (cand[i].has_noaddravail)
-                       retry = true; // We want to try again
-
-               if (!c || c->preference < cand[i].preference)
-                       c = &cand[i];
-       }
-
-       if (retry && na_mode == IA_MODE_TRY) {
-               // We give it a second try without the IA_NA
-               na_mode = IA_MODE_NONE;
-               return dhcpv6_request(DHCPV6_MSG_SOLICIT);
-       }
-
-       if (c) {
-               uint16_t hdr[2] = {htons(DHCPV6_OPT_SERVERID),
-                               htons(c->duid_len)};
-               odhcp6c_add_state(STATE_SERVER_ID, hdr, sizeof(hdr));
-               odhcp6c_add_state(STATE_SERVER_ID, c->duid, c->duid_len);
-               accept_reconfig = c->wants_reconfigure;
-               if (c->ia_na_len)
-                       odhcp6c_add_state(STATE_IA_NA, c->ia_na, c->ia_na_len);
-               if (c->ia_pd_len)
-                       odhcp6c_add_state(STATE_IA_PD, c->ia_pd, c->ia_pd_len);
-       }
-
-       for (size_t i = 0; i < cand_len / sizeof(*c); ++i) {
-               free(cand[i].ia_na);
-               free(cand[i].ia_pd);
-       }
-       odhcp6c_clear_state(STATE_SERVER_CAND);
-
-       if (!c)
-               return -1;
-       else if ((request_prefix && c->ia_pd_len) || (na_mode != IA_MODE_NONE && c->ia_na_len))
-               return DHCPV6_STATEFUL;
-       else
-               return DHCPV6_STATELESS;
+       return dhcpv6_promote_server_cand();
 }
 
 
@@ -734,10 +759,8 @@ static int dhcpv6_handle_rebind_reply(enum dhcpv6_msg orig, const int rc,
                const void *opt, const void *end)
 {
        dhcpv6_handle_advert(orig, rc, opt, end);
-       if (dhcpv6_commit_advert() < 0) {
-               dhcpv6_handle_reply(DHCPV6_MSG_UNKNOWN, rc, NULL, NULL);
+       if (dhcpv6_commit_advert() < 0)
                return -1;
-       }
 
        return dhcpv6_handle_reply(orig, rc, opt, end);
 }
@@ -874,7 +897,17 @@ static int dhcpv6_handle_reply(enum dhcpv6_msg orig, _unused const int rc,
                        odhcp6c_get_state(STATE_AFTR_NAME, &cur_len);
                        if (cur_len == 0)
                                odhcp6c_add_state(STATE_AFTR_NAME, odata, olen);
-               } else if (otype != DHCPV6_OPT_CLIENTID &&
+               } else if (otype == DHCPV6_OPT_SOL_MAX_RT && olen == 4) {
+                       uint32_t sol_max_rt = ntohl(*((uint32_t *)odata));
+                       if (sol_max_rt >= DHCPV6_SOL_MAX_RT_MIN && 
+                                       sol_max_rt <= DHCPV6_SOL_MAX_RT_MAX)
+                               dhcpv6_retx[DHCPV6_MSG_SOLICIT].max_timeo = sol_max_rt;
+               } else if (otype == DHCPV6_OPT_INF_MAX_RT && olen == 4) {
+                       uint32_t inf_max_rt = ntohl(*((uint32_t *)odata));
+                       if (inf_max_rt >= DHCPV6_INF_MAX_RT_MIN && 
+                                       inf_max_rt <= DHCPV6_INF_MAX_RT_MAX)
+                               dhcpv6_retx[DHCPV6_MSG_INFO_REQ].max_timeo = inf_max_rt;
+               }else if (otype != DHCPV6_OPT_CLIENTID &&
                                otype != DHCPV6_OPT_SERVERID) {
                        odhcp6c_add_state(STATE_CUSTOM_OPTS,
                                        &odata[-4], olen + 4);
@@ -896,13 +929,23 @@ static int dhcpv6_handle_reply(enum dhcpv6_msg orig, _unused const int rc,
                                        ret = -1;
                                break;
 
+                       case DHCPV6_MSG_REQUEST:
+                               // All server candidates can be cleared if not yet bound
+                               if (!odhcp6c_is_bound())
+                                       dhcpv6_clear_all_server_cand();
+
                        default :
                                break;
                        }
                }
        }
-       else if (ret > 0)
+       else if (ret > 0) {
+               // All server candidates can be cleared if not yet bound
+               if (!odhcp6c_is_bound())
+                       dhcpv6_clear_all_server_cand();
+
                t1 = refresh;
+       }
 
        return ret;
 }
@@ -1073,6 +1116,8 @@ static int dhcpv6_calc_refresh_timers(void)
                t1 = l_t1;
                t2 = l_t2;
                t3 = l_t3;
+       } else {
+               t1 = 600;
        }
 
        return (int)(ia_pd_entries + ia_na_entries);
@@ -1166,3 +1211,92 @@ static void dhcpv6_handle_ia_status_code(const enum dhcpv6_msg orig,
                break;
        }
 }
+
+static void dhcpv6_add_server_cand(const struct dhcpv6_server_cand *cand)
+{
+       size_t cand_len, i;
+       struct dhcpv6_server_cand *c = odhcp6c_get_state(STATE_SERVER_CAND, &cand_len);
+
+       // Remove identical duid server candidate
+       for (i = 0; i < cand_len / sizeof(*c); ++i) {
+               if (cand->duid_len == c[i].duid_len &&
+                               !memcmp(cand->duid, c[i].duid, cand->duid_len)) {
+                       free(c[i].ia_na);
+                       free(c[i].ia_pd);
+                       odhcp6c_remove_state(STATE_SERVER_CAND, i * sizeof(*c), sizeof(*c));
+                       break;
+               }
+       }
+
+       for (i = 0, c = odhcp6c_get_state(STATE_SERVER_CAND, &cand_len);
+               i < cand_len / sizeof(*c); ++i) {
+               if (c[i].preference < cand->preference)
+                       break;
+       }
+
+       odhcp6c_insert_state(STATE_SERVER_CAND, i * sizeof(*c), cand, sizeof(*cand));
+}
+
+static void dhcpv6_clear_all_server_cand(void)
+{
+       size_t cand_len, i;
+       struct dhcpv6_server_cand *c = odhcp6c_get_state(STATE_SERVER_CAND, &cand_len);
+
+       // Server candidates need deep delete for IA_NA/IA_PD
+       for (i = 0; i < cand_len / sizeof(*c); ++i) {
+               free(c[i].ia_na);
+               free(c[i].ia_pd);
+       }
+       odhcp6c_clear_state(STATE_SERVER_CAND);
+}
+
+int dhcpv6_promote_server_cand(void)
+{
+       size_t cand_len;
+       struct dhcpv6_server_cand *cand = odhcp6c_get_state(STATE_SERVER_CAND, &cand_len);
+       uint16_t hdr[2];
+       int ret = (na_mode == IA_MODE_NONE && pd_mode == IA_MODE_NONE) ?
+                       DHCPV6_STATELESS : DHCPV6_STATEFUL;
+
+       // Clear lingering candidate state info
+       odhcp6c_clear_state(STATE_SERVER_ID);
+       odhcp6c_clear_state(STATE_IA_NA);
+       odhcp6c_clear_state(STATE_IA_PD);
+
+       if (!cand_len)
+               return -1;
+
+       if (cand->has_noaddravail && na_mode == IA_MODE_TRY) {
+               na_mode = IA_MODE_NONE;
+
+               dhcpv6_retx[DHCPV6_MSG_SOLICIT].max_timeo = cand->sol_max_rt;
+               dhcpv6_retx[DHCPV6_MSG_INFO_REQ].max_timeo = cand->inf_max_rt;
+
+               return dhcpv6_request(DHCPV6_MSG_SOLICIT);
+       }
+
+       hdr[0] = htons(DHCPV6_OPT_SERVERID);
+       hdr[1] = htons(cand->duid_len);
+       odhcp6c_add_state(STATE_SERVER_ID, hdr, sizeof(hdr));
+       odhcp6c_add_state(STATE_SERVER_ID, cand->duid, cand->duid_len);
+       accept_reconfig = cand->wants_reconfigure;
+       if (cand->ia_na_len) {
+               odhcp6c_add_state(STATE_IA_NA, cand->ia_na, cand->ia_na_len);
+               free(cand->ia_na);
+               if (na_mode != IA_MODE_NONE)
+                       ret = DHCPV6_STATEFUL;
+       }
+       if (cand->ia_pd_len) {
+               odhcp6c_add_state(STATE_IA_PD, cand->ia_pd, cand->ia_pd_len);
+               free(cand->ia_pd);
+               if (request_prefix)
+                       ret = DHCPV6_STATEFUL;
+       }
+
+       dhcpv6_retx[DHCPV6_MSG_SOLICIT].max_timeo = cand->sol_max_rt;
+       dhcpv6_retx[DHCPV6_MSG_INFO_REQ].max_timeo = cand->inf_max_rt;
+       
+       odhcp6c_remove_state(STATE_SERVER_CAND, 0, sizeof(*cand));
+
+       return ret;
+}