router: Add PREF64 (RFC 8781) support

[project/odhcpd.git] / src / router.c

diff --git a/src/router.c b/src/router.c
index eca0bf7a282278fed0489bfabf8448003ad3bef3..d5ef7f8a4f582ef3466024da3ff2981a41c2787c 100644 (file)
--- a/src/router.c
+++ b/src/router.c
@@ -390,6 +390,7 @@ enum {
        IOV_RA_ROUTES,
        IOV_RA_DNS,
        IOV_RA_SEARCH,
+       IOV_RA_PREF64,
        IOV_RA_ADV_INTERVAL,
        IOV_RA_TOTAL,
 };
@@ -427,6 +428,13 @@ struct nd_opt_route_info {
        uint32_t addr[4];
 };
 
+struct nd_opt_pref64_info {
+       uint8_t type;
+       uint8_t len;
+       uint16_t lifetime_plc;
+       uint32_t addr[3];
+};
+
 /* Router Advert server mode */
 static int send_router_advert(struct interface *iface, const struct in6_addr *from)
 {
@@ -437,10 +445,12 @@ static int send_router_advert(struct interface *iface, const struct in6_addr *fr
        struct nd_opt_dns_server *dns = NULL;
        struct nd_opt_search_list *search = NULL;
        struct nd_opt_route_info *routes = NULL;
+       struct nd_opt_pref64_info *pref64 = NULL;
        struct nd_opt_adv_interval adv_interval;
        struct iovec iov[IOV_RA_TOTAL];
        struct sockaddr_in6 dest;
-       size_t dns_sz = 0, search_sz = 0, pfxs_cnt = 0, routes_cnt = 0;
+       size_t dns_sz = 0, search_sz = 0, pref64_sz = 0;
+       size_t pfxs_cnt = 0, routes_cnt = 0;
        ssize_t valid_addr_cnt = 0, invalid_addr_cnt = 0;
        uint32_t minvalid = UINT32_MAX, maxival, lifetime;
        int msecs, mtu = iface->ra_mtu, hlim = iface->ra_hoplimit;
@@ -698,6 +708,65 @@ static int send_router_advert(struct interface *iface, const struct in6_addr *fr
        iov[IOV_RA_SEARCH].iov_base = (char *)search;
        iov[IOV_RA_SEARCH].iov_len = search_sz;
 
+       if (iface->pref64_length) {
+               /* RFC 8781 § 4.1 rounding up lifetime to multiply of 8 */
+               uint16_t pref64_lifetime = lifetime < (UINT16_MAX - 7) ? lifetime + 7 : UINT16_MAX;
+               uint8_t prefix_length_code;
+               uint32_t mask_a1, mask_a2;
+
+               switch (iface->pref64_length) {
+               case 96:
+                       prefix_length_code = 0;
+                       mask_a1 = 0xffffffff;
+                       mask_a2 = 0xffffffff;
+                       break;
+               case 64:
+                       prefix_length_code = 1;
+                       mask_a1 = 0xffffffff;
+                       mask_a2 = 0x00000000;
+                       break;
+               case 56:
+                       prefix_length_code = 2;
+                       mask_a1 = 0xffffff00;
+                       mask_a2 = 0x00000000;
+                       break;
+               case 48:
+                       prefix_length_code = 3;
+                       mask_a1 = 0xffff0000;
+                       mask_a2 = 0x00000000;
+                       break;
+               case 40:
+                       prefix_length_code = 4;
+                       mask_a1 = 0xff000000;
+                       mask_a2 = 0x00000000;
+                       break;
+               case 32:
+                       prefix_length_code = 5;
+                       mask_a1 = 0x00000000;
+                       mask_a2 = 0x00000000;
+                       break;
+               default:
+                       syslog(LOG_WARNING, "Invalid PREF64 prefix size (%d), "
+                                       "ignoring ra_pref64 option!", iface->pref64_length);
+                       goto pref64_out;
+                       break;
+               }
+
+               pref64_sz = sizeof(*pref64);
+               pref64 = alloca(pref64_sz);
+               memset(pref64, 0, pref64_sz);
+               pref64->type = ND_OPT_PREF64;
+               pref64->len = 2;
+               pref64->lifetime_plc = htons((0xfff8 & pref64_lifetime) |
+                                               (0x7 & prefix_length_code));
+               pref64->addr[0] = iface->pref64_addr.s6_addr32[0];
+               pref64->addr[1] = iface->pref64_addr.s6_addr32[1] & htonl(mask_a1);
+               pref64->addr[2] = iface->pref64_addr.s6_addr32[2] & htonl(mask_a2);
+       }
+pref64_out:
+       iov[IOV_RA_PREF64].iov_base = (char *)pref64;
+       iov[IOV_RA_PREF64].iov_len = pref64_sz;
+
        /*
         * RFC7084 § 4.3 :
         *    L-3:   An IPv6 CE router MUST advertise itself as a router for the