/* * BIRD -- RAdv Packet Processing * * * Can be freely distributed and used under the terms of the GNU GPL. */ #include <stdlib.h> #include "radv.h" struct radv_ra_packet { u8 type; u8 code; u16 checksum; u8 current_hop_limit; u8 flags; u16 router_lifetime; u32 reachable_time; u32 retrans_timer; }; #define OPT_RA_MANAGED 0x80 #define OPT_RA_OTHER_CFG 0x40 #define OPT_PREFIX 3 #define OPT_MTU 5 #define OPT_RDNSS 25 #define OPT_DNSSL 31 struct radv_opt_prefix { u8 type; u8 length; u8 pxlen; u8 flags; u32 valid_lifetime; u32 preferred_lifetime; u32 reserved; ip6_addr prefix; }; #define OPT_PX_ONLINK 0x80 #define OPT_PX_AUTONOMOUS 0x40 struct radv_opt_mtu { u8 type; u8 length; u16 reserved; u32 mtu; }; struct radv_opt_rdnss { u8 type; u8 length; u16 reserved; u32 lifetime; ip6_addr servers[]; }; struct radv_opt_dnssl { u8 type; u8 length; u16 reserved; u32 lifetime; char domain[]; }; static struct radv_prefix_config default_prefix = { .onlink = 1, .autonomous = 1, .valid_lifetime = DEFAULT_VALID_LIFETIME, .preferred_lifetime = DEFAULT_PREFERRED_LIFETIME }; static struct radv_prefix_config * radv_prefix_match(struct radv_iface *ifa, struct ifa *a) { struct proto *p = &ifa->ra->p; struct radv_config *cf = (struct radv_config *) (p->cf); struct radv_prefix_config *pc; if (a->scope <= SCOPE_LINK) return NULL; WALK_LIST(pc, ifa->cf->pref_list) if (net_in_netX(&a->prefix, (net_addr *) &pc->prefix)) return pc; WALK_LIST(pc, cf->pref_list) if (net_in_netX(&a->prefix, (net_addr *) &pc->prefix)) return pc; return &default_prefix; } static int radv_prepare_rdnss(struct radv_iface *ifa, list *rdnss_list, char **buf, char *bufend) { struct radv_rdnss_config *rcf = HEAD(*rdnss_list); while(NODE_VALID(rcf)) { struct radv_rdnss_config *rcf_base = rcf; struct radv_opt_rdnss *op = (void *) *buf; int max_i = (bufend - *buf - sizeof(struct radv_opt_rdnss)) / sizeof(ip6_addr); int i = 0; if (max_i < 1) goto too_much; op->type = OPT_RDNSS; op->reserved = 0; if (rcf->lifetime_mult) op->lifetime = htonl(rcf->lifetime_mult * ifa->cf->max_ra_int); else op->lifetime = htonl(rcf->lifetime); while(NODE_VALID(rcf) && (rcf->lifetime == rcf_base->lifetime) && (rcf->lifetime_mult == rcf_base->lifetime_mult)) { if (i >= max_i) goto too_much; op->servers[i] = ip6_hton(rcf->server); i++; rcf = NODE_NEXT(rcf); } op->length = 1+2*i; *buf += 8 * op->length; } return 0; too_much: log(L_WARN "%s: Too many RA options on interface %s", ifa->ra->p.name, ifa->iface->name); return -1; } int radv_process_domain(struct radv_dnssl_config *cf) { /* Format of domain in search list is <size> <label> <size> <label> ... 0 */ char *dom = cf->domain; char *dom_end = dom; /* Just to */ u8 *dlen_save = &cf->dlen_first; uint len; while (dom_end) { dom_end = strchr(dom, '.'); len = dom_end ? (uint)(dom_end - dom) : strlen(dom); if (len < 1 || len > 63) return -1; *dlen_save = len; dlen_save = (u8 *) dom_end; dom += len + 1; } len = dom - cf->domain; if (len > 254) return -1; cf->dlen_all = len; return 0; } static int radv_prepare_dnssl(struct radv_iface *ifa, list *dnssl_list, char **buf, char *bufend) { struct radv_dnssl_config *dcf = HEAD(*dnssl_list); while(NODE_VALID(dcf)) { struct radv_dnssl_config *dcf_base = dcf; struct radv_opt_dnssl *op = (void *) *buf; int bsize = bufend - *buf - sizeof(struct radv_opt_dnssl); int bpos = 0; if (bsize < 0) goto too_much; bsize = bsize & ~7; /* Round down to multiples of 8 */ op->type = OPT_DNSSL; op->reserved = 0; if (dcf->lifetime_mult) op->lifetime = htonl(dcf->lifetime_mult * ifa->cf->max_ra_int); else op->lifetime = htonl(dcf->lifetime); while(NODE_VALID(dcf) && (dcf->lifetime == dcf_base->lifetime) && (dcf->lifetime_mult == dcf_base->lifetime_mult)) { if (bpos + dcf->dlen_all + 1 > bsize) goto too_much; op->domain[bpos++] = dcf->dlen_first; memcpy(op->domain + bpos, dcf->domain, dcf->dlen_all); bpos += dcf->dlen_all; dcf = NODE_NEXT(dcf); } int blen = (bpos + 7) / 8; bzero(op->domain + bpos, 8 * blen - bpos); op->length = 1 + blen; *buf += 8 * op->length; } return 0; too_much: log(L_WARN "%s: Too many RA options on interface %s", ifa->ra->p.name, ifa->iface->name); return -1; } static void radv_prepare_ra(struct radv_iface *ifa) { struct proto_radv *ra = ifa->ra; struct radv_config *cf = (struct radv_config *) (ra->p.cf); struct radv_iface_config *ic = ifa->cf; char *buf = ifa->sk->tbuf; char *bufstart = buf; char *bufend = buf + ifa->sk->tbsize; struct radv_ra_packet *pkt = (void *) buf; pkt->type = ICMPV6_RA; pkt->code = 0; pkt->checksum = 0; pkt->current_hop_limit = ic->current_hop_limit; pkt->router_lifetime = (ra->active || !ic->default_lifetime_sensitive) ? htons(ic->default_lifetime) : 0; pkt->flags = (ic->managed ? OPT_RA_MANAGED : 0) | (ic->other_config ? OPT_RA_OTHER_CFG : 0) | (pkt->router_lifetime ? ic->default_preference : 0); pkt->reachable_time = htonl(ic->reachable_time); pkt->retrans_timer = htonl(ic->retrans_timer); buf += sizeof(*pkt); if (ic->link_mtu) { struct radv_opt_mtu *om = (void *) buf; om->type = OPT_MTU; om->length = 1; om->reserved = 0; om->mtu = htonl(ic->link_mtu); buf += sizeof (*om); } struct ifa *addr; WALK_LIST(addr, ifa->iface->addrs) { if (addr->prefix.type != NET_IP6) continue; struct radv_prefix_config *pc; pc = radv_prefix_match(ifa, addr); if (!pc || pc->skip) continue; if (buf + sizeof(struct radv_opt_prefix) > bufend) { log(L_WARN "%s: Too many prefixes on interface %s", ra->p.name, ifa->iface->name); goto done; } struct radv_opt_prefix *op = (void *) buf; op->type = OPT_PREFIX; op->length = 4; op->pxlen = net6_pxlen(&addr->prefix); op->flags = (pc->onlink ? OPT_PX_ONLINK : 0) | (pc->autonomous ? OPT_PX_AUTONOMOUS : 0); op->valid_lifetime = (ra->active || !pc->valid_lifetime_sensitive) ? htonl(pc->valid_lifetime) : 0; op->preferred_lifetime = (ra->active || !pc->preferred_lifetime_sensitive) ? htonl(pc->preferred_lifetime) : 0; op->reserved = 0; op->prefix = ip6_hton(net6_prefix(&addr->prefix)); buf += sizeof(*op); } if (! ic->rdnss_local) if (radv_prepare_rdnss(ifa, &cf->rdnss_list, &buf, bufend) < 0) goto done; if (radv_prepare_rdnss(ifa, &ic->rdnss_list, &buf, bufend) < 0) goto done; if (! ic->dnssl_local) if (radv_prepare_dnssl(ifa, &cf->dnssl_list, &buf, bufend) < 0) goto done; if (radv_prepare_dnssl(ifa, &ic->dnssl_list, &buf, bufend) < 0) goto done; done: ifa->plen = buf - bufstart; } void radv_send_ra(struct radv_iface *ifa, int shutdown) { struct proto_radv *ra = ifa->ra; /* We store prepared RA in tbuf */ if (!ifa->plen) radv_prepare_ra(ifa); if (shutdown) { /* * Modify router lifetime to 0, it is not restored because we suppose that * the iface will be removed. The preference value also has to be zeroed. * (RFC 4191 2.2: If router lifetime is 0, the preference value must be 0.) */ struct radv_ra_packet *pkt = (void *) ifa->sk->tbuf; pkt->router_lifetime = 0; pkt->flags &= ~RA_PREF_MASK; } RADV_TRACE(D_PACKETS, "Sending RA via %s", ifa->iface->name); sk_send_to(ifa->sk, ifa->plen, IP6_ALL_NODES, 0); } static int radv_rx_hook(sock *sk, uint size) { struct radv_iface *ifa = sk->data; struct proto_radv *ra = ifa->ra; /* We want just packets from sk->iface */ if (sk->lifindex != sk->iface->index) return 1; if (ipa_equal(sk->faddr, ifa->addr->ip)) return 1; if (size < 8) return 1; byte *buf = sk->rbuf; if (buf[1] != 0) return 1; /* Validation is a bit sloppy - Hop Limit is not checked and length of options is ignored for RS and left to later for RA */ switch (buf[0]) { case ICMPV6_RS: RADV_TRACE(D_PACKETS, "Received RS from %I via %s", sk->faddr, ifa->iface->name); radv_iface_notify(ifa, RA_EV_RS); return 1; case ICMPV6_RA: RADV_TRACE(D_PACKETS, "Received RA from %I via %s", sk->faddr, ifa->iface->name); /* FIXME - there should be some checking of received RAs, but we just ignore them */ return 1; default: return 1; } } static void radv_tx_hook(sock *sk) { struct radv_iface *ifa = sk->data; log(L_WARN "%s: TX hook called", ifa->ra->p.name); } static void radv_err_hook(sock *sk, int err) { struct radv_iface *ifa = sk->data; log(L_ERR "%s: Socket error on %s: %M", ifa->ra->p.name, ifa->iface->name, err); } int radv_sk_open(struct radv_iface *ifa) { sock *sk = sk_new(ifa->ra->p.pool); sk->type = SK_IP; sk->subtype = SK_IPV6; sk->dport = ICMPV6_PROTO; sk->saddr = ifa->addr->ip; sk->ttl = 255; /* Mandatory for Neighbor Discovery packets */ sk->rx_hook = radv_rx_hook; sk->tx_hook = radv_tx_hook; sk->err_hook = radv_err_hook; sk->iface = ifa->iface; sk->rbsize = 1024; // bufsize(ifa); sk->tbsize = 1024; // bufsize(ifa); sk->data = ifa; sk->flags = SKF_LADDR_RX; if (sk_open(sk) < 0) goto err; /* We want listen just to ICMPv6 messages of type RS and RA */ if (sk_set_icmp6_filter(sk, ICMPV6_RS, ICMPV6_RA) < 0) goto err; if (sk_setup_multicast(sk) < 0) goto err; if (sk_join_group(sk, IP6_ALL_ROUTERS) < 0) goto err; ifa->sk = sk; return 1; err: sk_log_error(sk, ifa->ra->p.name); rfree(sk); return 0; }