dhcpv6: server unicast option support
[project/odhcp6c.git] / src / dhcpv6.c
index 2a9f8a2..6389052 100644 (file)
@@ -27,6 +27,7 @@
 #include <sys/time.h>
 #include <sys/ioctl.h>
 #include <sys/socket.h>
+#include <arpa/inet.h>
 #include <netinet/in.h>
 
 #include <net/if.h>
@@ -106,6 +107,8 @@ static int64_t t1 = 0, t2 = 0, t3 = 0;
 static int request_prefix = -1;
 static enum odhcp6c_ia_mode na_mode = IA_MODE_NONE, pd_mode = IA_MODE_NONE;
 static bool accept_reconfig = false;
+// Server unicast address
+static struct in6_addr server_addr = IN6ADDR_ANY_INIT;
 
 // Reconfigure key
 static uint8_t reconf_key[16];
@@ -180,6 +183,7 @@ int init_dhcpv6(const char *ifname, unsigned int options, int sol_timeout)
                        htons(DHCPV6_OPT_SIP_SERVER_A),
                        htons(DHCPV6_OPT_DNS_SERVERS),
                        htons(DHCPV6_OPT_DNS_DOMAIN),
+                       htons(DHCPV6_OPT_UNICAST),
                        htons(DHCPV6_OPT_SNTP_SERVERS),
                        htons(DHCPV6_OPT_NTP_SERVER),
                        htons(DHCPV6_OPT_AFTR_NAME),
@@ -501,7 +505,29 @@ static void dhcpv6_send(enum dhcpv6_msg type, uint8_t trid[3], uint32_t ecs)
        struct msghdr msg = {.msg_name = &srv, .msg_namelen = sizeof(srv),
                        .msg_iov = iov, .msg_iovlen = cnt};
 
-       sendmsg(sock, &msg, 0);
+       switch (type) {
+       case DHCPV6_MSG_REQUEST:
+       case DHCPV6_MSG_RENEW:
+       case DHCPV6_MSG_RELEASE:
+       case DHCPV6_MSG_DECLINE:
+               if (!IN6_IS_ADDR_UNSPECIFIED(&server_addr) &&
+                       odhcp6c_addr_in_scope(&server_addr)) {
+                       srv.sin6_addr = server_addr;
+                       if (!IN6_IS_ADDR_LINKLOCAL(&server_addr))
+                               srv.sin6_scope_id = 0;
+               }
+               break;
+       default:
+               break;
+       }
+
+       if (sendmsg(sock, &msg, 0) < 0) {
+               char in6_str[INET6_ADDRSTRLEN];
+
+               syslog(LOG_ERR, "Failed to send DHCPV6 message to %s (%s)",
+                       inet_ntop(AF_INET6, (const void *)&srv.sin6_addr,
+                               in6_str, sizeof(in6_str)), strerror(errno));
+       }
 }
 
 
@@ -799,7 +825,7 @@ 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},
-                                       DHCPV6_SOL_MAX_RT,
+                                       IN6ADDR_ANY_INIT, DHCPV6_SOL_MAX_RT,
                                        DHCPV6_INF_MAX_RT, NULL, NULL, 0, 0};
        bool have_na = false;
        int have_pd = 0;
@@ -818,6 +844,8 @@ static int dhcpv6_handle_advert(enum dhcpv6_msg orig, const int rc,
                } else if (otype == DHCPV6_OPT_PREF && olen >= 1 &&
                                cand.preference >= 0) {
                        cand.preference = pref = odata[0];
+               } else if (otype == DHCPV6_OPT_UNICAST && olen == sizeof(cand.server_addr)) {
+                       cand.server_addr = *(struct in6_addr *)odata;
                } else if (otype == DHCPV6_OPT_RECONF_ACCEPT) {
                        cand.wants_reconfigure = true;
                } else if (otype == DHCPV6_OPT_SOL_MAX_RT && olen == 4) {
@@ -1008,6 +1036,9 @@ static int dhcpv6_handle_reply(enum dhcpv6_msg orig, _unused const int rc,
 
                                dhcpv6_parse_ia(ia_hdr, odata + olen);
                                passthru = false;
+                       } else if (otype == DHCPV6_OPT_UNICAST && olen == sizeof(server_addr)) {
+                               server_addr = *(struct in6_addr *)odata;
+                               passthru = false;
                        } else if (otype == DHCPV6_OPT_STATUS && olen >= 2) {
                                uint8_t *mdata = (olen > 2) ? &odata[2] : NULL;
                                uint16_t mlen = (olen > 2) ? olen - 2 : 0;
@@ -1015,8 +1046,7 @@ static int dhcpv6_handle_reply(enum dhcpv6_msg orig, _unused const int rc,
 
                                dhcpv6_handle_status_code(orig, code, mdata, mlen, &ret);
                                passthru = false;
-                       }
-                       else if (otype == DHCPV6_OPT_DNS_SERVERS) {
+                       } else if (otype == DHCPV6_OPT_DNS_SERVERS) {
                                if (olen % 16 == 0)
                                        odhcp6c_add_state(STATE_DNS, odata, olen);
                        } else if (otype == DHCPV6_OPT_DNS_DOMAIN) {
@@ -1345,7 +1375,18 @@ static void dhcpv6_handle_status_code(const enum dhcpv6_msg orig,
                break;
 
        case DHCPV6_UseMulticast:
-               // TODO handle multicast status code
+               switch(orig) {
+               case DHCPV6_MSG_REQUEST:
+               case DHCPV6_MSG_RENEW:
+               case DHCPV6_MSG_RELEASE:
+               case DHCPV6_MSG_DECLINE:
+                       // Message needs to be retransmitted according to RFC3315 chapter 18.1.8
+                       server_addr = in6addr_any;
+                       *ret = 0;
+                       break;
+               default:
+                       break;
+               }
                break;
 
        case DHCPV6_NoAddrsAvail: