diff options
Diffstat (limited to 'proto/radv/packets.c')
| -rw-r--r-- | proto/radv/packets.c | 268 |
1 files changed, 268 insertions, 0 deletions
diff --git a/proto/radv/packets.c b/proto/radv/packets.c new file mode 100644 index 00000000..8aa487b0 --- /dev/null +++ b/proto/radv/packets.c @@ -0,0 +1,268 @@ +/* + * 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 + +struct radv_opt_prefix +{ + u8 type; + u8 length; + u8 pxlen; + u8 flags; + u32 valid_lifetime; + u32 preferred_lifetime; + u32 reserved; + ip_addr prefix; +}; + +#define OPT_PX_ONLINK 0x80 +#define OPT_PX_AUTONOMOUS 0x40 + +struct radv_opt_mtu +{ + u8 type; + u8 length; + u16 reserved; + u32 mtu; +}; + +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 ((a->pxlen >= pc->pxlen) && ipa_in_net(a->prefix, pc->prefix, pc->pxlen)) + return pc; + + WALK_LIST(pc, cf->pref_list) + if ((a->pxlen >= pc->pxlen) && ipa_in_net(a->prefix, pc->prefix, pc->pxlen)) + return pc; + + return &default_prefix; +} + +static void +radv_prepare_ra(struct radv_iface *ifa) +{ + struct proto_radv *ra = ifa->ra; + + 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 = ifa->cf->current_hop_limit; + pkt->flags = (ifa->cf->managed ? OPT_RA_MANAGED : 0) | + (ifa->cf->other_config ? OPT_RA_OTHER_CFG : 0); + pkt->router_lifetime = htons(ifa->cf->default_lifetime); + pkt->reachable_time = htonl(ifa->cf->reachable_time); + pkt->retrans_timer = htonl(ifa->cf->retrans_timer); + buf += sizeof(*pkt); + + if (ifa->cf->link_mtu) + { + struct radv_opt_mtu *om = (void *) buf; + om->type = OPT_MTU; + om->length = 1; + om->reserved = 0; + om->mtu = htonl(ifa->cf->link_mtu); + buf += sizeof (*om); + } + + struct ifa *addr; + WALK_LIST(addr, ifa->iface->addrs) + { + 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); + break; + } + + struct radv_opt_prefix *op = (void *) buf; + op->type = OPT_PREFIX; + op->length = 4; + op->pxlen = addr->pxlen; + op->flags = (pc->onlink ? OPT_PX_ONLINK : 0) | + (pc->autonomous ? OPT_PX_AUTONOMOUS : 0); + op->valid_lifetime = htonl(pc->valid_lifetime); + op->preferred_lifetime = htonl(pc->preferred_lifetime); + op->reserved = 0; + op->prefix = addr->prefix; + ipa_hton(op->prefix); + buf += sizeof(*op); + } + + 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 */ + struct radv_ra_packet *pkt = (void *) ifa->sk->tbuf; + pkt->router_lifetime = 0; + } + + RADV_TRACE(D_PACKETS, "Sending RA via %s", ifa->iface->name); + sk_send_to(ifa->sk, ifa->plen, AllNodes, 0); +} + + +static int +radv_rx_hook(sock *sk, int 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: %m", ifa->ra->p.name, err); +} + +int +radv_sk_open(struct radv_iface *ifa) +{ + sock *sk = sk_new(ifa->ra->p.pool); + sk->type = SK_IP; + sk->dport = ICMPV6_PROTO; + sk->saddr = IPA_NONE; + + 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; + + sk->saddr = ifa->addr->ip; + + /* 2 is an offset of the checksum in an ICMPv6 packet */ + if (sk_set_ipv6_checksum(sk, 2) < 0) + goto err; + + /* We want listen just to ICMPv6 messages of type RS and RA */ + if (sk_set_icmp_filter(sk, ICMPV6_RS, ICMPV6_RA) < 0) + goto err; + + if (sk_setup_multicast(sk) < 0) + goto err; + + if (sk_join_group(sk, AllRouters) < 0) + goto err; + + ifa->sk = sk; + return 1; + + err: + rfree(sk); + return 0; +} + |