bird/proto/ospf/packet.c

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/*
* BIRD -- OSPF
*
* (c) 1999--2005 Ondrej Filip <feela@network.cz>
*
* Can be freely distributed and used under the terms of the GNU GPL.
*/
#include "ospf.h"
#include "nest/password.h"
#include "lib/md5.h"
void
ospf_pkt_fill_hdr(struct ospf_iface *ifa, void *buf, u8 h_type)
{
struct proto_ospf *po = ifa->oa->po;
struct proto *p = &po->proto;
struct ospf_packet *pkt;
pkt = (struct ospf_packet *) buf;
pkt->version = OSPF_VERSION;
pkt->type = h_type;
pkt->routerid = htonl(po->router_id);
pkt->areaid = htonl(ifa->oa->areaid);
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#ifdef OSPFv3
pkt->instance_id = ifa->instance_id;
#endif
#ifdef OSPFv2
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pkt->autype = htons(ifa->autype);
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#endif
pkt->checksum = 0;
}
unsigned
ospf_pkt_maxsize(struct ospf_iface *ifa)
{
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/* For virtual links use mtu=576, can be mtu < 576? */
unsigned mtu = (ifa->type == OSPF_IT_VLINK) ? OSPF_VLINK_MTU : ifa->iface->mtu;
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unsigned add = 0;
#ifdef OSPFv2
add = ((ifa->autype == OSPF_AUTH_CRYPT) ? OSPF_AUTH_CRYPT_SIZE : 0);
#endif
return ((mtu <= ifa->iface->mtu) ? mtu : ifa->iface->mtu) -
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SIZE_OF_IP_HEADER - add;
}
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#ifdef OSPFv2
static void
ospf_pkt_finalize(struct ospf_iface *ifa, struct ospf_packet *pkt)
{
struct password_item *passwd = NULL;
void *tail;
struct MD5Context ctxt;
char password[OSPF_AUTH_CRYPT_SIZE];
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pkt->autype = htons(ifa->autype);
switch(ifa->autype)
{
case OSPF_AUTH_SIMPLE:
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bzero(&pkt->u, sizeof(union ospf_auth));
passwd = password_find(ifa->passwords, 1);
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if (!passwd)
{
log( L_ERR "No suitable password found for authentication" );
return;
}
password_cpy(pkt->u.password, passwd->password, sizeof(union ospf_auth));
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case OSPF_AUTH_NONE:
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pkt->checksum = ipsum_calculate(pkt, sizeof(struct ospf_packet) -
sizeof(union ospf_auth), (pkt + 1),
ntohs(pkt->length) -
sizeof(struct ospf_packet), NULL);
break;
case OSPF_AUTH_CRYPT:
passwd = password_find(ifa->passwords, 0);
if (!passwd)
{
log( L_ERR "No suitable password found for authentication" );
return;
}
pkt->checksum = 0;
/* Perhaps use random value to prevent replay attacks after
reboot when system does not have independent RTC? */
if (!ifa->csn)
{
ifa->csn = (u32) now;
ifa->csn_use = now;
}
/* We must have sufficient delay between sending a packet and increasing
CSN to prevent reordering of packets (in a network) with different CSNs */
if ((now - ifa->csn_use) > 1)
ifa->csn++;
ifa->csn_use = now;
pkt->u.md5.keyid = passwd->id;
pkt->u.md5.len = OSPF_AUTH_CRYPT_SIZE;
pkt->u.md5.zero = 0;
pkt->u.md5.csn = htonl(ifa->csn);
tail = ((void *)pkt) + ntohs(pkt->length);
MD5Init(&ctxt);
MD5Update(&ctxt, (char *) pkt, ntohs(pkt->length));
password_cpy(password, passwd->password, OSPF_AUTH_CRYPT_SIZE);
MD5Update(&ctxt, password, OSPF_AUTH_CRYPT_SIZE);
MD5Final(tail, &ctxt);
break;
default:
bug("Unknown authentication type");
}
}
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static int
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ospf_pkt_checkauth(struct ospf_neighbor *n, struct ospf_iface *ifa, struct ospf_packet *pkt, int size)
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{
struct proto_ospf *po = ifa->oa->po;
struct proto *p = &po->proto;
struct password_item *pass = NULL, *ptmp;
void *tail;
char md5sum[OSPF_AUTH_CRYPT_SIZE];
char password[OSPF_AUTH_CRYPT_SIZE];
struct MD5Context ctxt;
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if (pkt->autype != htons(ifa->autype))
{
OSPF_TRACE(D_PACKETS, "OSPF_auth: Method differs (%d)", ntohs(pkt->autype));
return 0;
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}
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if (n && (ifa != n->ifa))
{
OSPF_TRACE(D_PACKETS, "OSPF_auth: received packet from strange interface (%s/%s)",
ifa->iface->name, n->ifa->iface->name);
return 0;
}
switch(ifa->autype)
{
case OSPF_AUTH_NONE:
return 1;
break;
case OSPF_AUTH_SIMPLE:
pass = password_find(ifa->passwords, 1);
if (!pass)
{
OSPF_TRACE(D_PACKETS, "OSPF_auth: no password found");
return 0;
}
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password_cpy(password, pass->password, sizeof(union ospf_auth));
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if (memcmp(pkt->u.password, password, sizeof(union ospf_auth)))
{
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char ppass[sizeof(union ospf_auth) + 1];
bzero(ppass, (sizeof(union ospf_auth) + 1));
memcpy(ppass, pkt->u.password, sizeof(union ospf_auth));
OSPF_TRACE(D_PACKETS, "OSPF_auth: different passwords (%s)", ppass);
return 0;
}
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return 1;
break;
case OSPF_AUTH_CRYPT:
if (pkt->u.md5.len != OSPF_AUTH_CRYPT_SIZE)
{
OSPF_TRACE(D_PACKETS, "OSPF_auth: wrong size of md5 digest");
return 0;
}
if (ntohs(pkt->length) + OSPF_AUTH_CRYPT_SIZE != size)
{
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OSPF_TRACE(D_PACKETS, "OSPF_auth: size mismatch (%d vs %d)",
ntohs(pkt->length) + OSPF_AUTH_CRYPT_SIZE, size);
return 0;
}
if (pkt->u.md5.zero)
{
OSPF_TRACE(D_PACKETS, "OSPF_auth: \"zero\" area is non-zero");
return 0;
}
tail = ((void *)pkt) + ntohs(pkt->length);
if (ifa->passwords)
{
WALK_LIST(ptmp, *(ifa->passwords))
{
if (pkt->u.md5.keyid != ptmp->id) continue;
if ((ptmp->accfrom > now_real) || (ptmp->accto < now_real)) continue;
pass = ptmp;
break;
}
}
if (!pass)
{
OSPF_TRACE(D_PACKETS, "OSPF_auth: no suitable md5 password found");
return 0;
}
if (n)
{
u32 rcv_csn = ntohl(pkt->u.md5.csn);
if(rcv_csn < n->csn)
{
OSPF_TRACE(D_PACKETS, "OSPF_auth: lower sequence number (rcv %d, old %d)", rcv_csn, n->csn);
return 0;
}
n->csn = rcv_csn;
}
MD5Init(&ctxt);
MD5Update(&ctxt, (char *) pkt, ntohs(pkt->length));
password_cpy(password, pass->password, OSPF_AUTH_CRYPT_SIZE);
MD5Update(&ctxt, password, OSPF_AUTH_CRYPT_SIZE);
MD5Final(md5sum, &ctxt);
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if (memcmp(md5sum, tail, OSPF_AUTH_CRYPT_SIZE))
{
OSPF_TRACE(D_PACKETS, "OSPF_auth: wrong md5 digest");
return 0;
}
return 1;
break;
default:
OSPF_TRACE(D_PACKETS, "OSPF_auth: unknown auth type");
return 0;
}
}
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#else
/* OSPFv3 authentication not yet supported */
static inline void
ospf_pkt_finalize(struct ospf_iface *ifa, struct ospf_packet *pkt)
{ }
static int
ospf_pkt_checkauth(struct ospf_neighbor *n, struct ospf_iface *ifa, struct ospf_packet *pkt, int size)
{ return 1; }
#endif
static struct ospf_iface *
find_matching_iface(struct ospf_packet *ps, unsigned ifindex, ip_addr faddr)
{
u32 areaid = ntohl(ps->areaid);
u32 rid = ntohl(ps->routerid);
node *nd;
/* First, we will try to match real ifaces */
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WALK_LIST(nd, ospf_ifaces)
{
struct ospf_iface *ifa = SKIP_BACK(struct ospf_iface, sk_node, nd);
struct ifa *addr = ifa->addr;
if ((ifa->iface->index == ifindex) &&
(ifa->oa->areaid == areaid) &&
#ifdef OSPFv2
((addr->flags & IA_UNNUMBERED) ?
ipa_equal(faddr, addr->opposite) :
ipa_in_net(faddr, addr->prefix, addr->pxlen))
#else /* OSPFv3 */
(ifa->instance_id == ps->instance_id)
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#endif
)
return ifa;
}
/* Second, we will try to match vlinks */
if (areaid != 0)
return NULL;
/* FIXME: There should be some more checks to distinquish parallel
vlinks to the same ABR. */
WALK_LIST(nd, ospf_vlinks)
{
struct ospf_iface *ifa = SKIP_BACK(struct ospf_iface, sk_node, nd);
if ((ifa->vid == rid)
#ifdef OSPFv3
&& (ifa->instance_id == ps->instance_id)
#endif
)
return ifa;
}
return NULL;
}
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/**
* ospf_rx_hook
* @sk: socket we received the packet.
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* @size: size of the packet
*
* This is the entry point for messages from neighbors. Many checks (like
* authentication, checksums, size) are done before the packet is passed to
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* non generic functions.
*/
int
ospf_rx_hook(sock *sk, int size)
{
char *mesg = "OSPF: Bad packet from ";
DBG("OSPF: RX_Hook called (from %I)\n", sk->faddr);
/* First, we check packet size, checksum, and the protocol version */
struct ospf_packet *ps = (struct ospf_packet *) ip_skip_header(sk->rbuf, &size);
if (ps == NULL)
{
log(L_ERR "%s%I - bad IP header", mesg, sk->faddr);
return 1;
}
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if ((unsigned) size < sizeof(struct ospf_packet))
{
log(L_ERR "%s%I - too short (%u bytes)", mesg, sk->faddr, size);
return 1;
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}
int osize = ntohs(ps->length);
if ((osize > size) || ((osize % 4) != 0))
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{
log(L_ERR "%s%I - size field does not match (%d/%d)", mesg, sk->faddr, osize, size);
return 1;
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}
if ((unsigned) size > sk->rbsize)
{
log(L_ERR "%s%I - too large (%d vs %d)", mesg, sk->faddr, size, sk->rbsize);
return 1;
}
if (ps->version != OSPF_VERSION)
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{
log(L_ERR "%s%I - version %u", mesg, sk->faddr, ps->version);
return 1;
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}
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#ifdef OSPFv2
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if ((ps->autype != htons(OSPF_AUTH_CRYPT)) &&
(!ipsum_verify(ps, 16, (void *) ps + sizeof(struct ospf_packet),
osize - sizeof(struct ospf_packet), NULL)))
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{
log(L_ERR "%s%I - bad checksum", mesg, sk->faddr);
return 1;
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}
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#endif
/* Now, we would like to associate the packet with an OSPF iface */
struct ospf_iface *ifa = find_matching_iface(ps, sk->lifindex, sk->faddr);
if (ifa == NULL)
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{
/* We limit logging of unmatched packets as it may be perfectly OK */
if (unmatched_count < 8)
{
struct iface *ifc = if_find_by_index(sk->lifindex);
log(L_WARN "OSPF: Received unmatched packet (src %I, iface %s, rtid %R, area %R)",
sk->faddr, ifc ? ifc->name : "?", ntohl(ps->routerid), ntohl(ps->areaid));
unmatched_count++;
}
return 1;
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}
struct proto_ospf *po = ifa->oa->po;
struct proto *p = &po->proto;
if (ifa->stub) /* This shouldn't happen */
return 1;
if (ipa_equal(sk->laddr, AllDRouters) && (ifa->sk_dr == 0))
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return 1;
if (ntohl(ps->routerid) == po->router_id)
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{
log(L_ERR "%s%I - received my own router ID!", mesg, sk->faddr);
return 1;
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}
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if (ntohl(ps->routerid) == 0)
{
log(L_ERR "%s%I - router id = 0.0.0.0", mesg, sk->faddr);
return 1;
}
/* This is deviation from RFC 2328 - neighbours should be identified by
* IP address on broadcast and NBMA networks.
*/
struct ospf_neighbor *n = find_neigh(ifa, ntohl(ps->routerid));
if(!n && (ps->type != HELLO_P))
{
log(L_WARN "OSPF: Received non-hello packet from uknown neighbor (src %I, iface %s)",
sk->faddr, ifa->iface->name);
return 1;
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}
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if (!ospf_pkt_checkauth(n, ifa, ps, size))
{
log(L_ERR "%s%I - authentification failed", mesg, sk->faddr);
return 1;
}
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/* Dump packet
pu8=(u8 *)(sk->rbuf+5*4);
for(i=0;i<ntohs(ps->length);i+=4)
DBG("%s: received %u,%u,%u,%u\n",p->name, pu8[i+0], pu8[i+1], pu8[i+2],
pu8[i+3]);
DBG("%s: received size: %u\n",p->name,size);
*/
switch (ps->type)
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{
case HELLO_P:
DBG("%s: Hello received.\n", p->name);
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ospf_hello_receive(ps, ifa, n, sk->faddr);
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break;
case DBDES_P:
DBG("%s: Database description received.\n", p->name);
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ospf_dbdes_receive(ps, ifa, n);
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break;
case LSREQ_P:
DBG("%s: Link state request received.\n", p->name);
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ospf_lsreq_receive(ps, ifa, n);
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break;
case LSUPD_P:
DBG("%s: Link state update received.\n", p->name);
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ospf_lsupd_receive(ps, ifa, n);
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break;
case LSACK_P:
DBG("%s: Link state ack received.\n", p->name);
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ospf_lsack_receive(ps, ifa, n);
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break;
default:
log(L_ERR "%s%I - wrong type %u", mesg, sk->faddr, ps->type);
return 1;
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};
return 1;
}
void
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ospf_tx_hook(sock * sk)
{
// struct ospf_iface *ifa= (struct ospf_iface *) (sk->data);
// struct proto *p = (struct proto *) (ifa->oa->po);
log(L_ERR "OSPF: TX_Hook called");
}
void
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ospf_err_hook(sock * sk, int err)
{
// struct ospf_iface *ifa= (struct ospf_iface *) (sk->data);
// struct proto *p = (struct proto *) (ifa->oa->po);
log(L_ERR "OSPF: Socket error: %m", err);
}
void
ospf_send_to_agt(struct ospf_iface *ifa, u8 state)
{
struct ospf_neighbor *n;
WALK_LIST(n, ifa->neigh_list)
if (n->state >= state)
ospf_send_to(ifa, n->ip);
}
void
ospf_send_to_bdr(struct ospf_iface *ifa)
{
if (!ipa_equal(ifa->drip, IPA_NONE))
ospf_send_to(ifa, ifa->drip);
if (!ipa_equal(ifa->bdrip, IPA_NONE))
ospf_send_to(ifa, ifa->bdrip);
}
void
ospf_send_to(struct ospf_iface *ifa, ip_addr dst)
{
sock *sk = ifa->sk;
struct ospf_packet *pkt = (struct ospf_packet *) sk->tbuf;
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int len = ntohs(pkt->length);
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#ifdef OSPFv2
if (ifa->autype == OSPF_AUTH_CRYPT)
len += OSPF_AUTH_CRYPT_SIZE;
#endif
ospf_pkt_finalize(ifa, pkt);
if (sk->tbuf != sk->tpos)
log(L_ERR "Aiee, old packet was overwritten in TX buffer");
sk_send_to(sk, len, dst, 0);
}