/* 
 * xfrm4_policy.c
 *
 * Changes:
 *      Kazunori MIYAZAWA @USAGI
 *      YOSHIFUJI Hideaki @USAGI
 *              Split up af-specific portion
 *      
 */

#include <linux/config.h>
#include <net/xfrm.h>
#include <net/ip.h>

extern struct dst_ops xfrm4_dst_ops;
extern struct xfrm_policy_afinfo xfrm4_policy_afinfo;

static struct xfrm_type_map xfrm4_type_map = { .lock = RW_LOCK_UNLOCKED };

static int xfrm4_dst_lookup(struct xfrm_dst **dst, struct flowi *fl)
{
        return __ip_route_output_key((struct rtable**)dst, fl);
}

/* Check that the bundle accepts the flow and its components are
 * still valid.
 */

static int __xfrm4_bundle_ok(struct xfrm_dst *xdst, struct flowi *fl)
{
        do {
                if (xdst->u.dst.ops != &xfrm4_dst_ops)
                        return 1;

                if (!xfrm_selector_match(&xdst->u.dst.xfrm->sel, fl, AF_INET))
                        return 0;
                if (xdst->u.dst.xfrm->km.state != XFRM_STATE_VALID ||
                    xdst->u.dst.path->obsolete > 0)
                        return 0;
                xdst = (struct xfrm_dst*)xdst->u.dst.child;
        } while (xdst);
        return 0;
}

static struct dst_entry *
__xfrm4_find_bundle(struct flowi *fl, struct rtable *rt, struct xfrm_policy *policy)
{
        struct dst_entry *dst;

        if (!fl->fl4_src)
                fl->fl4_src = rt->rt_src;
        if (!fl->fl4_dst)
                fl->fl4_dst = rt->rt_dst;
        read_lock_bh(&policy->lock);
        for (dst = policy->bundles; dst; dst = dst->next) {
                struct xfrm_dst *xdst = (struct xfrm_dst*)dst;
                if (xdst->u.rt.fl.oif == fl->oif &&     /*XXX*/
                    xdst->u.rt.fl.fl4_dst == fl->fl4_dst &&
                    xdst->u.rt.fl.fl4_src == fl->fl4_src &&
                    __xfrm4_bundle_ok(xdst, fl)) {
                        dst_clone(dst);
                        break;
                }
        }
        read_unlock_bh(&policy->lock);
        return dst;
}

/* Allocate chain of dst_entry's, attach known xfrm's, calculate
 * all the metrics... Shortly, bundle a bundle.
 */

static int
__xfrm4_bundle_create(struct xfrm_policy *policy, struct xfrm_state **xfrm, int nx,
                      struct flowi *fl, struct dst_entry **dst_p)
{
        struct dst_entry *dst, *dst_prev;
        struct rtable *rt0 = (struct rtable*)(*dst_p);
        struct rtable *rt = rt0;
        u32 remote = fl->fl4_dst;
        u32 local  = fl->fl4_src;
        int i;
        int err;
        int header_len = 0;
        int trailer_len = 0;

        dst = dst_prev = NULL;

        for (i = 0; i < nx; i++) {
                struct dst_entry *dst1 = dst_alloc(&xfrm4_dst_ops);

                if (unlikely(dst1 == NULL)) {
                        err = -ENOBUFS;
                        goto error;
                }

                dst1->xfrm = xfrm[i];
                if (!dst)
                        dst = dst1;
                else {
                        dst_prev->child = dst1;
                        dst1->flags |= DST_NOHASH;
                        dst_clone(dst1);
                }
                dst_prev = dst1;
                if (xfrm[i]->props.mode) {
                        remote = xfrm[i]->id.daddr.a4;
                        local  = xfrm[i]->props.saddr.a4;
                }
                header_len += xfrm[i]->props.header_len;
                trailer_len += xfrm[i]->props.trailer_len;
        }

        if (remote != fl->fl4_dst) {
                struct flowi fl_tunnel = { .nl_u = { .ip4_u =
                                                     { .daddr = remote,
                                                       .saddr = local }
                                                   }
                                         };
                err = xfrm_dst_lookup((struct xfrm_dst**)&rt, &fl_tunnel, AF_INET);
                if (err)
                        goto error;
        } else {
                dst_hold(&rt->u.dst);
        }
        dst_prev->child = &rt->u.dst;
        for (dst_prev = dst; dst_prev != &rt->u.dst; dst_prev = dst_prev->child) {
                struct xfrm_dst *x = (struct xfrm_dst*)dst_prev;
                x->u.rt.fl = *fl;

                dst_prev->dev = rt->u.dst.dev;
                if (rt->u.dst.dev)
                        dev_hold(rt->u.dst.dev);
                dst_prev->obsolete      = -1;
                dst_prev->flags        |= DST_HOST;
                dst_prev->lastuse       = jiffies;
                dst_prev->header_len    = header_len;
                dst_prev->trailer_len   = trailer_len;
                memcpy(&dst_prev->metrics, &rt->u.dst.metrics, sizeof(dst_prev->metrics));
                dst_prev->path          = &rt->u.dst;

                /* Copy neighbout for reachability confirmation */
                dst_prev->neighbour     = neigh_clone(rt->u.dst.neighbour);
                dst_prev->input         = rt->u.dst.input;
                dst_prev->output        = dst_prev->xfrm->type->output;
                if (rt->peer)
                        atomic_inc(&rt->peer->refcnt);
                x->u.rt.peer = rt->peer;
                /* Sheit... I remember I did this right. Apparently,
                 * it was magically lost, so this code needs audit */
                x->u.rt.rt_flags = rt0->rt_flags&(RTCF_BROADCAST|RTCF_MULTICAST|RTCF_LOCAL);
                x->u.rt.rt_type = rt->rt_type;
                x->u.rt.rt_src = rt0->rt_src;
                x->u.rt.rt_dst = rt0->rt_dst;
                x->u.rt.rt_gateway = rt->rt_gateway;
                x->u.rt.rt_spec_dst = rt0->rt_spec_dst;
                header_len -= x->u.dst.xfrm->props.header_len;
                trailer_len -= x->u.dst.xfrm->props.trailer_len;
        }
        *dst_p = dst;
        return 0;

error:
        if (dst)
                dst_free(dst);
        return err;
}

static void
_decode_session4(struct sk_buff *skb, struct flowi *fl)
{
        struct iphdr *iph = skb->nh.iph;
        u8 *xprth = skb->nh.raw + iph->ihl*4;

        memset(fl, 0, sizeof(struct flowi));
        if (!(iph->frag_off & htons(IP_MF | IP_OFFSET))) {
                switch (iph->protocol) {
                case IPPROTO_UDP:
                case IPPROTO_TCP:
                case IPPROTO_SCTP:
                        if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
                                u16 *ports = (u16 *)xprth;

                                fl->fl_ip_sport = ports[0];
                                fl->fl_ip_dport = ports[1];
                        }
                        break;

                case IPPROTO_ESP:
                        if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
                                u32 *ehdr = (u32 *)xprth;

                                fl->fl_ipsec_spi = ehdr[0];
                        }
                        break;

                case IPPROTO_AH:
                        if (pskb_may_pull(skb, xprth + 8 - skb->data)) {
                                u32 *ah_hdr = (u32*)xprth;

                                fl->fl_ipsec_spi = ah_hdr[1];
                        }
                        break;

                case IPPROTO_COMP:
                        if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
                                u16 *ipcomp_hdr = (u16 *)xprth;

                                fl->fl_ipsec_spi = ntohl(ntohs(ipcomp_hdr[1]));
                        }
                        break;
                default:
                        fl->fl_ipsec_spi = 0;
                        break;
                };
        }
        fl->proto = iph->protocol;
        fl->fl4_dst = iph->daddr;
        fl->fl4_src = iph->saddr;
}

static inline int xfrm4_garbage_collect(void)
{
        read_lock(&xfrm4_policy_afinfo.lock);
        xfrm4_policy_afinfo.garbage_collect();
        read_unlock(&xfrm4_policy_afinfo.lock);
        return (atomic_read(&xfrm4_dst_ops.entries) > xfrm4_dst_ops.gc_thresh*2);
}

static void xfrm4_update_pmtu(struct dst_entry *dst, u32 mtu)
{
        struct dst_entry *path = dst->path;

        if (mtu < 68 + dst->header_len)
                return;

        path->ops->update_pmtu(path, mtu);
}

struct dst_ops xfrm4_dst_ops = {
        .family =               AF_INET,
        .protocol =             __constant_htons(ETH_P_IP),
        .gc =                   xfrm4_garbage_collect,
        .update_pmtu =          xfrm4_update_pmtu,
        .gc_thresh =            1024,
        .entry_size =           sizeof(struct xfrm_dst),
};

struct xfrm_policy_afinfo xfrm4_policy_afinfo = {
        .family =               AF_INET,
        .lock =                 RW_LOCK_UNLOCKED,
        .type_map =             &xfrm4_type_map,
        .dst_ops =              &xfrm4_dst_ops,
        .dst_lookup =           xfrm4_dst_lookup,
        .find_bundle =          __xfrm4_find_bundle,
        .bundle_create =        __xfrm4_bundle_create,
        .decode_session =       _decode_session4,
};

void __init xfrm4_policy_init(void)
{
        xfrm_policy_register_afinfo(&xfrm4_policy_afinfo);
}

void __exit xfrm4_policy_fini(void)
{
        xfrm_policy_unregister_afinfo(&xfrm4_policy_afinfo);
}

void __init xfrm4_init(void)
{
        xfrm4_state_init();
        xfrm4_policy_init();
}

void __exit xfrm4_fini(void)
{
        //xfrm4_input_fini();
        xfrm4_policy_fini();
        xfrm4_state_fini();
}