mirror of
https://gitlab.nic.cz/labs/bird.git
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265 lines
5.6 KiB
C
265 lines
5.6 KiB
C
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/*
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* BIRD -- RAdv Packet Processing
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*
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*
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* Can be freely distributed and used under the terms of the GNU GPL.
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*/
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#include <stdlib.h>
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#include "radv.h"
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struct radv_ra_packet
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{
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u8 type;
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u8 code;
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u16 checksum;
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u8 current_hop_limit;
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u8 flags;
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u16 router_lifetime;
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u32 reachable_time;
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u32 retrans_timer;
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};
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#define OPT_RA_MANAGED 0x80
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#define OPT_RA_OTHER_CFG 0x40
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#define OPT_PREFIX 3
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#define OPT_MTU 5
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struct radv_opt_prefix
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{
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u8 type;
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u8 length;
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u8 pxlen;
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u8 flags;
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u32 valid_lifetime;
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u32 preferred_lifetime;
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u32 reserved;
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ip_addr prefix;
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};
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#define OPT_PX_ONLINK 0x80
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#define OPT_PX_AUTONOMOUS 0x40
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struct radv_opt_mtu
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{
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u8 type;
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u8 length;
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u16 reserved;
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u32 mtu;
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};
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static struct radv_prefix_config default_prefix = {
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.onlink = 1,
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.autonomous = 1,
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.valid_lifetime = DEFAULT_VALID_LIFETIME,
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.preferred_lifetime = DEFAULT_PREFERRED_LIFETIME
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};
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static struct radv_prefix_config *
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radv_prefix_match(struct radv_iface *ifa, struct ifa *a)
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{
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struct proto *p = &ifa->ra->p;
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struct radv_config *cf = (struct radv_config *) (p->cf);
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struct radv_prefix_config *pc;
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if (a->scope <= SCOPE_LINK)
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return NULL;
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WALK_LIST(pc, ifa->cf->pref_list)
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if ((a->pxlen >= pc->pxlen) && ipa_in_net(a->prefix, pc->prefix, pc->pxlen))
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return pc;
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WALK_LIST(pc, cf->pref_list)
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if ((a->pxlen >= pc->pxlen) && ipa_in_net(a->prefix, pc->prefix, pc->pxlen))
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return pc;
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return &default_prefix;
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}
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static void
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radv_prepare_ra(struct radv_iface *ifa)
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{
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struct proto_radv *ra = ifa->ra;
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char *buf = ifa->sk->tbuf;
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char *bufstart = buf;
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char *bufend = buf + ifa->sk->tbsize;
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struct radv_ra_packet *pkt = (void *) buf;
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pkt->type = ICMPV6_RA;
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pkt->code = 0;
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pkt->checksum = 0;
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pkt->current_hop_limit = ifa->cf->current_hop_limit;
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pkt->flags = (ifa->cf->managed ? OPT_RA_MANAGED : 0) |
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(ifa->cf->other_config ? OPT_RA_OTHER_CFG : 0);
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pkt->router_lifetime = htons(ifa->cf->default_lifetime);
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pkt->reachable_time = htonl(ifa->cf->reachable_time);
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pkt->retrans_timer = htonl(ifa->cf->retrans_timer);
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buf += sizeof(*pkt);
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if (ifa->cf->link_mtu)
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{
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struct radv_opt_mtu *om = (void *) buf;
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om->type = OPT_MTU;
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om->length = 1;
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om->reserved = 0;
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om->mtu = htonl(ifa->cf->link_mtu);
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buf += sizeof (*om);
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}
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struct ifa *addr;
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WALK_LIST(addr, ifa->iface->addrs)
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{
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struct radv_prefix_config *pc;
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pc = radv_prefix_match(ifa, addr);
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if (!pc || pc->skip)
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continue;
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if (buf + sizeof(struct radv_opt_prefix) > bufend)
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{
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log(L_WARN "%s: Too many prefixes on interface %s", ra->p.name, ifa->iface->name);
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break;
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}
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struct radv_opt_prefix *op = (void *) buf;
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op->type = OPT_PREFIX;
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op->length = 4;
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op->pxlen = addr->pxlen;
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op->flags = (pc->onlink ? OPT_PX_ONLINK : 0) |
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(pc->autonomous ? OPT_PX_AUTONOMOUS : 0);
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op->valid_lifetime = htonl(pc->valid_lifetime);
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op->preferred_lifetime = htonl(pc->preferred_lifetime);
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op->reserved = 0;
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op->prefix = addr->prefix;
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ipa_hton(op->prefix);
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buf += sizeof(*op);
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}
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ifa->plen = buf - bufstart;
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}
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void
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radv_send_ra(struct radv_iface *ifa, int shutdown)
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{
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struct proto_radv *ra = ifa->ra;
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/* We store prepared RA in tbuf */
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if (!ifa->plen)
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radv_prepare_ra(ifa);
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if (shutdown)
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{
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/* Modify router lifetime to 0, it is not restored because
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we suppose that the iface will be removed */
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struct radv_ra_packet *pkt = (void *) ifa->sk->tbuf;
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pkt->router_lifetime = 0;
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}
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RADV_TRACE(D_PACKETS, "Sending RA via %s", ifa->iface->name);
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sk_send_to(ifa->sk, ifa->plen, AllNodes, 0);
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}
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static int
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radv_rx_hook(sock *sk, int size)
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{
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struct radv_iface *ifa = sk->data;
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struct proto_radv *ra = ifa->ra;
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/* We want just packets from sk->iface */
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if (sk->lifindex != sk->iface->index)
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return 1;
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if (ipa_equal(sk->faddr, ifa->addr->ip))
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return 1;
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if (size < 8)
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return 1;
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byte *buf = sk->rbuf;
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if (buf[1] != 0)
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return 1;
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/* Validation is a bit sloppy - Hop Limit is not checked and
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length of options is ignored for RS and left to later for RA */
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switch (buf[0])
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{
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case ICMPV6_RS:
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RADV_TRACE(D_PACKETS, "Received RS from %I via %s",
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sk->faddr, ifa->iface->name);
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radv_iface_notify(ifa, RA_EV_RS);
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return 1;
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case ICMPV6_RA:
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RADV_TRACE(D_PACKETS, "Received RA from %I via %s",
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sk->faddr, ifa->iface->name);
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/* FIXME - there should be some checking of received RAs, but we just ignore them */
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return 1;
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default:
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return 1;
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}
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}
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static void
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radv_tx_hook(sock *sk)
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{
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struct radv_iface *ifa = sk->data;
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log(L_WARN "%s: TX hook called", ifa->ra->p.name);
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}
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static void
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radv_err_hook(sock *sk, int err)
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{
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struct radv_iface *ifa = sk->data;
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log(L_ERR "%s: Socket error: %m", ifa->ra->p.name, err);
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}
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int
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radv_sk_open(struct radv_iface *ifa)
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{
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sock *sk = sk_new(ifa->ra->p.pool);
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sk->type = SK_IP;
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sk->dport = ICMPV6_PROTO;
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sk->saddr = IPA_NONE;
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sk->ttl = 255; /* Mandatory for Neighbor Discovery packets */
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sk->rx_hook = radv_rx_hook;
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sk->tx_hook = radv_tx_hook;
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sk->err_hook = radv_err_hook;
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sk->iface = ifa->iface;
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sk->rbsize = 1024; // bufsize(ifa);
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sk->tbsize = 1024; // bufsize(ifa);
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sk->data = ifa;
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sk->flags = SKF_LADDR_RX;
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if (sk_open(sk) != 0)
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goto err;
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sk->saddr = ifa->addr->ip;
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/* We want listen just to ICMPv6 messages of type RS and RA */
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if (sk_set_icmp_filter(sk, ICMPV6_RS, ICMPV6_RA) < 0)
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goto err;
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if (sk_setup_multicast(sk) < 0)
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goto err;
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if (sk_join_group(sk, AllRouters) < 0)
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goto err;
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ifa->sk = sk;
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return 1;
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err:
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rfree(sk);
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return 0;
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}
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