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ipv6.c

/*
 *    DCCP over IPv6
 *    Linux INET6 implementation
 *
 *    Based on net/dccp6/ipv6.c
 *
 *    Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
 *
 *    This program is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU General Public License
 *      as published by the Free Software Foundation; either version
 *      2 of the License, or (at your option) any later version.
 */

#include <linux/module.h>
#include <linux/random.h>
#include <linux/xfrm.h>

#include <net/addrconf.h>
#include <net/inet_common.h>
#include <net/inet_hashtables.h>
#include <net/inet_sock.h>
#include <net/inet6_connection_sock.h>
#include <net/inet6_hashtables.h>
#include <net/ip6_route.h>
#include <net/ipv6.h>
#include <net/protocol.h>
#include <net/transp_v6.h>
#include <net/ip6_checksum.h>
#include <net/xfrm.h>

#include "dccp.h"
#include "ipv6.h"
#include "feat.h"

/* Socket used for sending RSTs and ACKs */
static struct socket *dccp_v6_ctl_socket;

static struct inet_connection_sock_af_ops dccp_ipv6_mapped;
static struct inet_connection_sock_af_ops dccp_ipv6_af_ops;

static int dccp_v6_get_port(struct sock *sk, unsigned short snum)
{
      return inet_csk_get_port(&dccp_hashinfo, sk, snum,
                         inet6_csk_bind_conflict);
}

static void dccp_v6_hash(struct sock *sk)
{
      if (sk->sk_state != DCCP_CLOSED) {
            if (inet_csk(sk)->icsk_af_ops == &dccp_ipv6_mapped) {
                  dccp_hash(sk);
                  return;
            }
            local_bh_disable();
            __inet6_hash(&dccp_hashinfo, sk);
            local_bh_enable();
      }
}

/* add pseudo-header to DCCP checksum stored in skb->csum */
static inline __sum16 dccp_v6_csum_finish(struct sk_buff *skb,
                              struct in6_addr *saddr,
                              struct in6_addr *daddr)
{
      return csum_ipv6_magic(saddr, daddr, skb->len, IPPROTO_DCCP, skb->csum);
}

static inline void dccp_v6_send_check(struct sock *sk, int unused_value,
                              struct sk_buff *skb)
{
      struct ipv6_pinfo *np = inet6_sk(sk);
      struct dccp_hdr *dh = dccp_hdr(skb);

      dccp_csum_outgoing(skb);
      dh->dccph_checksum = dccp_v6_csum_finish(skb, &np->saddr, &np->daddr);
}

static inline __u32 secure_dccpv6_sequence_number(__be32 *saddr, __be32 *daddr,
                                      __be16 sport, __be16 dport   )
{
      return secure_tcpv6_sequence_number(saddr, daddr, sport, dport);
}

static inline __u32 dccp_v6_init_sequence(struct sk_buff *skb)
{
      return secure_dccpv6_sequence_number(ipv6_hdr(skb)->daddr.s6_addr32,
                                   ipv6_hdr(skb)->saddr.s6_addr32,
                                   dccp_hdr(skb)->dccph_dport,
                                   dccp_hdr(skb)->dccph_sport     );

}

static void dccp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
                  int type, int code, int offset, __be32 info)
{
      struct ipv6hdr *hdr = (struct ipv6hdr *)skb->data;
      const struct dccp_hdr *dh = (struct dccp_hdr *)(skb->data + offset);
      struct ipv6_pinfo *np;
      struct sock *sk;
      int err;
      __u64 seq;

      sk = inet6_lookup(&dccp_hashinfo, &hdr->daddr, dh->dccph_dport,
                    &hdr->saddr, dh->dccph_sport, inet6_iif(skb));

      if (sk == NULL) {
            ICMP6_INC_STATS_BH(__in6_dev_get(skb->dev), ICMP6_MIB_INERRORS);
            return;
      }

      if (sk->sk_state == DCCP_TIME_WAIT) {
            inet_twsk_put(inet_twsk(sk));
            return;
      }

      bh_lock_sock(sk);
      if (sock_owned_by_user(sk))
            NET_INC_STATS_BH(LINUX_MIB_LOCKDROPPEDICMPS);

      if (sk->sk_state == DCCP_CLOSED)
            goto out;

      np = inet6_sk(sk);

      if (type == ICMPV6_PKT_TOOBIG) {
            struct dst_entry *dst = NULL;

            if (sock_owned_by_user(sk))
                  goto out;
            if ((1 << sk->sk_state) & (DCCPF_LISTEN | DCCPF_CLOSED))
                  goto out;

            /* icmp should have updated the destination cache entry */
            dst = __sk_dst_check(sk, np->dst_cookie);
            if (dst == NULL) {
                  struct inet_sock *inet = inet_sk(sk);
                  struct flowi fl;

                  /* BUGGG_FUTURE: Again, it is not clear how
                     to handle rthdr case. Ignore this complexity
                     for now.
                   */
                  memset(&fl, 0, sizeof(fl));
                  fl.proto = IPPROTO_DCCP;
                  ipv6_addr_copy(&fl.fl6_dst, &np->daddr);
                  ipv6_addr_copy(&fl.fl6_src, &np->saddr);
                  fl.oif = sk->sk_bound_dev_if;
                  fl.fl_ip_dport = inet->dport;
                  fl.fl_ip_sport = inet->sport;
                  security_sk_classify_flow(sk, &fl);

                  err = ip6_dst_lookup(sk, &dst, &fl);
                  if (err) {
                        sk->sk_err_soft = -err;
                        goto out;
                  }

                  err = xfrm_lookup(&dst, &fl, sk, 0);
                  if (err < 0) {
                        sk->sk_err_soft = -err;
                        goto out;
                  }
            } else
                  dst_hold(dst);

            if (inet_csk(sk)->icsk_pmtu_cookie > dst_mtu(dst)) {
                  dccp_sync_mss(sk, dst_mtu(dst));
            } /* else let the usual retransmit timer handle it */
            dst_release(dst);
            goto out;
      }

      icmpv6_err_convert(type, code, &err);

      seq = dccp_hdr_seq(dh);
      /* Might be for an request_sock */
      switch (sk->sk_state) {
            struct request_sock *req, **prev;
      case DCCP_LISTEN:
            if (sock_owned_by_user(sk))
                  goto out;

            req = inet6_csk_search_req(sk, &prev, dh->dccph_dport,
                                 &hdr->daddr, &hdr->saddr,
                                 inet6_iif(skb));
            if (req == NULL)
                  goto out;

            /*
             * ICMPs are not backlogged, hence we cannot get an established
             * socket here.
             */
            BUG_TRAP(req->sk == NULL);

            if (seq != dccp_rsk(req)->dreq_iss) {
                  NET_INC_STATS_BH(LINUX_MIB_OUTOFWINDOWICMPS);
                  goto out;
            }

            inet_csk_reqsk_queue_drop(sk, req, prev);
            goto out;

      case DCCP_REQUESTING:
      case DCCP_RESPOND:  /* Cannot happen.
                         It can, it SYNs are crossed. --ANK */
            if (!sock_owned_by_user(sk)) {
                  DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS);
                  sk->sk_err = err;
                  /*
                   * Wake people up to see the error
                   * (see connect in sock.c)
                   */
                  sk->sk_error_report(sk);
                  dccp_done(sk);
            } else
                  sk->sk_err_soft = err;
            goto out;
      }

      if (!sock_owned_by_user(sk) && np->recverr) {
            sk->sk_err = err;
            sk->sk_error_report(sk);
      } else
            sk->sk_err_soft = err;

out:
      bh_unlock_sock(sk);
      sock_put(sk);
}


static int dccp_v6_send_response(struct sock *sk, struct request_sock *req,
                         struct dst_entry *dst)
{
      struct inet6_request_sock *ireq6 = inet6_rsk(req);
      struct ipv6_pinfo *np = inet6_sk(sk);
      struct sk_buff *skb;
      struct ipv6_txoptions *opt = NULL;
      struct in6_addr *final_p = NULL, final;
      struct flowi fl;
      int err = -1;

      memset(&fl, 0, sizeof(fl));
      fl.proto = IPPROTO_DCCP;
      ipv6_addr_copy(&fl.fl6_dst, &ireq6->rmt_addr);
      ipv6_addr_copy(&fl.fl6_src, &ireq6->loc_addr);
      fl.fl6_flowlabel = 0;
      fl.oif = ireq6->iif;
      fl.fl_ip_dport = inet_rsk(req)->rmt_port;
      fl.fl_ip_sport = inet_sk(sk)->sport;
      security_req_classify_flow(req, &fl);

      if (dst == NULL) {
            opt = np->opt;

            if (opt != NULL && opt->srcrt != NULL) {
                  const struct rt0_hdr *rt0 = (struct rt0_hdr *)opt->srcrt;

                  ipv6_addr_copy(&final, &fl.fl6_dst);
                  ipv6_addr_copy(&fl.fl6_dst, rt0->addr);
                  final_p = &final;
            }

            err = ip6_dst_lookup(sk, &dst, &fl);
            if (err)
                  goto done;

            if (final_p)
                  ipv6_addr_copy(&fl.fl6_dst, final_p);

            err = xfrm_lookup(&dst, &fl, sk, 0);
            if (err < 0)
                  goto done;
      }

      skb = dccp_make_response(sk, dst, req);
      if (skb != NULL) {
            struct dccp_hdr *dh = dccp_hdr(skb);

            dh->dccph_checksum = dccp_v6_csum_finish(skb,
                                           &ireq6->loc_addr,
                                           &ireq6->rmt_addr);
            ipv6_addr_copy(&fl.fl6_dst, &ireq6->rmt_addr);
            err = ip6_xmit(sk, skb, &fl, opt, 0);
            err = net_xmit_eval(err);
      }

done:
      if (opt != NULL && opt != np->opt)
            sock_kfree_s(sk, opt, opt->tot_len);
      dst_release(dst);
      return err;
}

static void dccp_v6_reqsk_destructor(struct request_sock *req)
{
      if (inet6_rsk(req)->pktopts != NULL)
            kfree_skb(inet6_rsk(req)->pktopts);
}

static void dccp_v6_ctl_send_reset(struct sock *sk, struct sk_buff *rxskb)
{
      struct ipv6hdr *rxip6h;
      struct sk_buff *skb;
      struct flowi fl;

      if (dccp_hdr(rxskb)->dccph_type == DCCP_PKT_RESET)
            return;

      if (!ipv6_unicast_destination(rxskb))
            return;

      skb = dccp_ctl_make_reset(dccp_v6_ctl_socket, rxskb);
      if (skb == NULL)
            return;

      rxip6h = ipv6_hdr(rxskb);
      dccp_hdr(skb)->dccph_checksum = dccp_v6_csum_finish(skb, &rxip6h->saddr,
                                              &rxip6h->daddr);

      memset(&fl, 0, sizeof(fl));
      ipv6_addr_copy(&fl.fl6_dst, &rxip6h->saddr);
      ipv6_addr_copy(&fl.fl6_src, &rxip6h->daddr);

      fl.proto = IPPROTO_DCCP;
      fl.oif = inet6_iif(rxskb);
      fl.fl_ip_dport = dccp_hdr(skb)->dccph_dport;
      fl.fl_ip_sport = dccp_hdr(skb)->dccph_sport;
      security_skb_classify_flow(rxskb, &fl);

      /* sk = NULL, but it is safe for now. RST socket required. */
      if (!ip6_dst_lookup(NULL, &skb->dst, &fl)) {
            if (xfrm_lookup(&skb->dst, &fl, NULL, 0) >= 0) {
                  ip6_xmit(dccp_v6_ctl_socket->sk, skb, &fl, NULL, 0);
                  DCCP_INC_STATS_BH(DCCP_MIB_OUTSEGS);
                  DCCP_INC_STATS_BH(DCCP_MIB_OUTRSTS);
                  return;
            }
      }

      kfree_skb(skb);
}

static struct request_sock_ops dccp6_request_sock_ops = {
      .family           = AF_INET6,
      .obj_size   = sizeof(struct dccp6_request_sock),
      .rtx_syn_ack      = dccp_v6_send_response,
      .send_ack   = dccp_reqsk_send_ack,
      .destructor = dccp_v6_reqsk_destructor,
      .send_reset = dccp_v6_ctl_send_reset,
};

static struct sock *dccp_v6_hnd_req(struct sock *sk,struct sk_buff *skb)
{
      const struct dccp_hdr *dh = dccp_hdr(skb);
      const struct ipv6hdr *iph = ipv6_hdr(skb);
      struct sock *nsk;
      struct request_sock **prev;
      /* Find possible connection requests. */
      struct request_sock *req = inet6_csk_search_req(sk, &prev,
                                          dh->dccph_sport,
                                          &iph->saddr,
                                          &iph->daddr,
                                          inet6_iif(skb));
      if (req != NULL)
            return dccp_check_req(sk, skb, req, prev);

      nsk = __inet6_lookup_established(&dccp_hashinfo,
                               &iph->saddr, dh->dccph_sport,
                               &iph->daddr, ntohs(dh->dccph_dport),
                               inet6_iif(skb));
      if (nsk != NULL) {
            if (nsk->sk_state != DCCP_TIME_WAIT) {
                  bh_lock_sock(nsk);
                  return nsk;
            }
            inet_twsk_put(inet_twsk(nsk));
            return NULL;
      }

      return sk;
}

static int dccp_v6_conn_request(struct sock *sk, struct sk_buff *skb)
{
      struct request_sock *req;
      struct dccp_request_sock *dreq;
      struct inet6_request_sock *ireq6;
      struct ipv6_pinfo *np = inet6_sk(sk);
      const __be32 service = dccp_hdr_request(skb)->dccph_req_service;
      struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);

      if (skb->protocol == htons(ETH_P_IP))
            return dccp_v4_conn_request(sk, skb);

      if (!ipv6_unicast_destination(skb))
            return 0;   /* discard, don't send a reset here */

      if (dccp_bad_service_code(sk, service)) {
            dcb->dccpd_reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE;
            goto drop;
      }
      /*
       * There are no SYN attacks on IPv6, yet...
       */
      dcb->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
      if (inet_csk_reqsk_queue_is_full(sk))
            goto drop;

      if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1)
            goto drop;

      req = inet6_reqsk_alloc(&dccp6_request_sock_ops);
      if (req == NULL)
            goto drop;

      if (dccp_parse_options(sk, skb))
            goto drop_and_free;

      dccp_reqsk_init(req, skb);

      if (security_inet_conn_request(sk, skb, req))
            goto drop_and_free;

      ireq6 = inet6_rsk(req);
      ipv6_addr_copy(&ireq6->rmt_addr, &ipv6_hdr(skb)->saddr);
      ipv6_addr_copy(&ireq6->loc_addr, &ipv6_hdr(skb)->daddr);
      ireq6->pktopts    = NULL;

      if (ipv6_opt_accepted(sk, skb) ||
          np->rxopt.bits.rxinfo || np->rxopt.bits.rxoinfo ||
          np->rxopt.bits.rxhlim || np->rxopt.bits.rxohlim) {
            atomic_inc(&skb->users);
            ireq6->pktopts = skb;
      }
      ireq6->iif = sk->sk_bound_dev_if;

      /* So that link locals have meaning */
      if (!sk->sk_bound_dev_if &&
          ipv6_addr_type(&ireq6->rmt_addr) & IPV6_ADDR_LINKLOCAL)
            ireq6->iif = inet6_iif(skb);

      /*
       * Step 3: Process LISTEN state
       *
       *   Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
       *
       *   In fact we defer setting S.GSR, S.SWL, S.SWH to
       *   dccp_create_openreq_child.
       */
      dreq = dccp_rsk(req);
      dreq->dreq_isr       = dcb->dccpd_seq;
      dreq->dreq_iss       = dccp_v6_init_sequence(skb);
      dreq->dreq_service = service;

      if (dccp_v6_send_response(sk, req, NULL))
            goto drop_and_free;

      inet6_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT);
      return 0;

drop_and_free:
      reqsk_free(req);
drop:
      DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS);
      return -1;
}

static struct sock *dccp_v6_request_recv_sock(struct sock *sk,
                                    struct sk_buff *skb,
                                    struct request_sock *req,
                                    struct dst_entry *dst)
{
      struct inet6_request_sock *ireq6 = inet6_rsk(req);
      struct ipv6_pinfo *newnp, *np = inet6_sk(sk);
      struct inet_sock *newinet;
      struct dccp_sock *newdp;
      struct dccp6_sock *newdp6;
      struct sock *newsk;
      struct ipv6_txoptions *opt;

      if (skb->protocol == htons(ETH_P_IP)) {
            /*
             *    v6 mapped
             */
            newsk = dccp_v4_request_recv_sock(sk, skb, req, dst);
            if (newsk == NULL)
                  return NULL;

            newdp6 = (struct dccp6_sock *)newsk;
            newdp = dccp_sk(newsk);
            newinet = inet_sk(newsk);
            newinet->pinet6 = &newdp6->inet6;
            newnp = inet6_sk(newsk);

            memcpy(newnp, np, sizeof(struct ipv6_pinfo));

            ipv6_addr_set(&newnp->daddr, 0, 0, htonl(0x0000FFFF),
                        newinet->daddr);

            ipv6_addr_set(&newnp->saddr, 0, 0, htonl(0x0000FFFF),
                        newinet->saddr);

            ipv6_addr_copy(&newnp->rcv_saddr, &newnp->saddr);

            inet_csk(newsk)->icsk_af_ops = &dccp_ipv6_mapped;
            newsk->sk_backlog_rcv = dccp_v4_do_rcv;
            newnp->pktoptions  = NULL;
            newnp->opt     = NULL;
            newnp->mcast_oif   = inet6_iif(skb);
            newnp->mcast_hops  = ipv6_hdr(skb)->hop_limit;

            /*
             * No need to charge this sock to the relevant IPv6 refcnt debug socks count
             * here, dccp_create_openreq_child now does this for us, see the comment in
             * that function for the gory details. -acme
             */

            /* It is tricky place. Until this moment IPv4 tcp
               worked with IPv6 icsk.icsk_af_ops.
               Sync it now.
             */
            dccp_sync_mss(newsk, inet_csk(newsk)->icsk_pmtu_cookie);

            return newsk;
      }

      opt = np->opt;

      if (sk_acceptq_is_full(sk))
            goto out_overflow;

      if (dst == NULL) {
            struct in6_addr *final_p = NULL, final;
            struct flowi fl;

            memset(&fl, 0, sizeof(fl));
            fl.proto = IPPROTO_DCCP;
            ipv6_addr_copy(&fl.fl6_dst, &ireq6->rmt_addr);
            if (opt != NULL && opt->srcrt != NULL) {
                  const struct rt0_hdr *rt0 = (struct rt0_hdr *)opt->srcrt;

                  ipv6_addr_copy(&final, &fl.fl6_dst);
                  ipv6_addr_copy(&fl.fl6_dst, rt0->addr);
                  final_p = &final;
            }
            ipv6_addr_copy(&fl.fl6_src, &ireq6->loc_addr);
            fl.oif = sk->sk_bound_dev_if;
            fl.fl_ip_dport = inet_rsk(req)->rmt_port;
            fl.fl_ip_sport = inet_sk(sk)->sport;
            security_sk_classify_flow(sk, &fl);

            if (ip6_dst_lookup(sk, &dst, &fl))
                  goto out;

            if (final_p)
                  ipv6_addr_copy(&fl.fl6_dst, final_p);

            if ((xfrm_lookup(&dst, &fl, sk, 0)) < 0)
                  goto out;
      }

      newsk = dccp_create_openreq_child(sk, req, skb);
      if (newsk == NULL)
            goto out;

      /*
       * No need to charge this sock to the relevant IPv6 refcnt debug socks
       * count here, dccp_create_openreq_child now does this for us, see the
       * comment in that function for the gory details. -acme
       */

      __ip6_dst_store(newsk, dst, NULL, NULL);
      newsk->sk_route_caps = dst->dev->features & ~(NETIF_F_IP_CSUM |
                                          NETIF_F_TSO);
      newdp6 = (struct dccp6_sock *)newsk;
      newinet = inet_sk(newsk);
      newinet->pinet6 = &newdp6->inet6;
      newdp = dccp_sk(newsk);
      newnp = inet6_sk(newsk);

      memcpy(newnp, np, sizeof(struct ipv6_pinfo));

      ipv6_addr_copy(&newnp->daddr, &ireq6->rmt_addr);
      ipv6_addr_copy(&newnp->saddr, &ireq6->loc_addr);
      ipv6_addr_copy(&newnp->rcv_saddr, &ireq6->loc_addr);
      newsk->sk_bound_dev_if = ireq6->iif;

      /* Now IPv6 options...

         First: no IPv4 options.
       */
      newinet->opt = NULL;

      /* Clone RX bits */
      newnp->rxopt.all = np->rxopt.all;

      /* Clone pktoptions received with SYN */
      newnp->pktoptions = NULL;
      if (ireq6->pktopts != NULL) {
            newnp->pktoptions = skb_clone(ireq6->pktopts, GFP_ATOMIC);
            kfree_skb(ireq6->pktopts);
            ireq6->pktopts = NULL;
            if (newnp->pktoptions)
                  skb_set_owner_r(newnp->pktoptions, newsk);
      }
      newnp->opt    = NULL;
      newnp->mcast_oif  = inet6_iif(skb);
      newnp->mcast_hops = ipv6_hdr(skb)->hop_limit;

      /*
       * Clone native IPv6 options from listening socket (if any)
       *
       * Yes, keeping reference count would be much more clever, but we make
       * one more one thing there: reattach optmem to newsk.
       */
      if (opt != NULL) {
            newnp->opt = ipv6_dup_options(newsk, opt);
            if (opt != np->opt)
                  sock_kfree_s(sk, opt, opt->tot_len);
      }

      inet_csk(newsk)->icsk_ext_hdr_len = 0;
      if (newnp->opt != NULL)
            inet_csk(newsk)->icsk_ext_hdr_len = (newnp->opt->opt_nflen +
                                         newnp->opt->opt_flen);

      dccp_sync_mss(newsk, dst_mtu(dst));

      newinet->daddr = newinet->saddr = newinet->rcv_saddr = LOOPBACK4_IPV6;

      __inet6_hash(&dccp_hashinfo, newsk);
      inet_inherit_port(&dccp_hashinfo, sk, newsk);

      return newsk;

out_overflow:
      NET_INC_STATS_BH(LINUX_MIB_LISTENOVERFLOWS);
out:
      NET_INC_STATS_BH(LINUX_MIB_LISTENDROPS);
      if (opt != NULL && opt != np->opt)
            sock_kfree_s(sk, opt, opt->tot_len);
      dst_release(dst);
      return NULL;
}

/* The socket must have it's spinlock held when we get
 * here.
 *
 * We have a potential double-lock case here, so even when
 * doing backlog processing we use the BH locking scheme.
 * This is because we cannot sleep with the original spinlock
 * held.
 */
static int dccp_v6_do_rcv(struct sock *sk, struct sk_buff *skb)
{
      struct ipv6_pinfo *np = inet6_sk(sk);
      struct sk_buff *opt_skb = NULL;

      /* Imagine: socket is IPv6. IPv4 packet arrives,
         goes to IPv4 receive handler and backlogged.
         From backlog it always goes here. Kerboom...
         Fortunately, dccp_rcv_established and rcv_established
         handle them correctly, but it is not case with
         dccp_v6_hnd_req and dccp_v6_ctl_send_reset().   --ANK
       */

      if (skb->protocol == htons(ETH_P_IP))
            return dccp_v4_do_rcv(sk, skb);

      if (sk_filter(sk, skb))
            goto discard;

      /*
       * socket locking is here for SMP purposes as backlog rcv is currently
       * called with bh processing disabled.
       */

      /* Do Stevens' IPV6_PKTOPTIONS.

         Yes, guys, it is the only place in our code, where we
         may make it not affecting IPv4.
         The rest of code is protocol independent,
         and I do not like idea to uglify IPv4.

         Actually, all the idea behind IPV6_PKTOPTIONS
         looks not very well thought. For now we latch
         options, received in the last packet, enqueued
         by tcp. Feel free to propose better solution.
                                     --ANK (980728)
       */
      if (np->rxopt.all)
      /*
       * FIXME: Add handling of IPV6_PKTOPTIONS skb. See the comments below
       *        (wrt ipv6_pktopions) and net/ipv6/tcp_ipv6.c for an example.
       */
            opt_skb = skb_clone(skb, GFP_ATOMIC);

      if (sk->sk_state == DCCP_OPEN) { /* Fast path */
            if (dccp_rcv_established(sk, skb, dccp_hdr(skb), skb->len))
                  goto reset;
            if (opt_skb) {
                  /* XXX This is where we would goto ipv6_pktoptions. */
                  __kfree_skb(opt_skb);
            }
            return 0;
      }

      /*
       *  Step 3: Process LISTEN state
       *     If S.state == LISTEN,
       *     If P.type == Request or P contains a valid Init Cookie option,
       *          (* Must scan the packet's options to check for Init
       *           Cookies.  Only Init Cookies are processed here,
       *           however; other options are processed in Step 8.  This
       *           scan need only be performed if the endpoint uses Init
       *           Cookies *)
       *          (* Generate a new socket and switch to that socket *)
       *          Set S := new socket for this port pair
       *          S.state = RESPOND
       *          Choose S.ISS (initial seqno) or set from Init Cookies
       *          Initialize S.GAR := S.ISS
       *          Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies
       *          Continue with S.state == RESPOND
       *          (* A Response packet will be generated in Step 11 *)
       *     Otherwise,
       *          Generate Reset(No Connection) unless P.type == Reset
       *          Drop packet and return
       *
       * NOTE: the check for the packet types is done in
       *     dccp_rcv_state_process
       */
      if (sk->sk_state == DCCP_LISTEN) {
            struct sock *nsk = dccp_v6_hnd_req(sk, skb);

            if (nsk == NULL)
                  goto discard;
            /*
             * Queue it on the new socket if the new socket is active,
             * otherwise we just shortcircuit this and continue with
             * the new socket..
             */
            if (nsk != sk) {
                  if (dccp_child_process(sk, nsk, skb))
                        goto reset;
                  if (opt_skb != NULL)
                        __kfree_skb(opt_skb);
                  return 0;
            }
      }

      if (dccp_rcv_state_process(sk, skb, dccp_hdr(skb), skb->len))
            goto reset;
      if (opt_skb) {
            /* XXX This is where we would goto ipv6_pktoptions. */
            __kfree_skb(opt_skb);
      }
      return 0;

reset:
      dccp_v6_ctl_send_reset(sk, skb);
discard:
      if (opt_skb != NULL)
            __kfree_skb(opt_skb);
      kfree_skb(skb);
      return 0;
}

static int dccp_v6_rcv(struct sk_buff *skb)
{
      const struct dccp_hdr *dh;
      struct sock *sk;
      int min_cov;

      /* Step 1: Check header basics */

      if (dccp_invalid_packet(skb))
            goto discard_it;

      /* Step 1: If header checksum is incorrect, drop packet and return. */
      if (dccp_v6_csum_finish(skb, &ipv6_hdr(skb)->saddr,
                             &ipv6_hdr(skb)->daddr)) {
            DCCP_WARN("dropped packet with invalid checksum\n");
            goto discard_it;
      }

      dh = dccp_hdr(skb);

      DCCP_SKB_CB(skb)->dccpd_seq  = dccp_hdr_seq(dh);
      DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type;

      if (dccp_packet_without_ack(skb))
            DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ;
      else
            DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb);

      /* Step 2:
       *    Look up flow ID in table and get corresponding socket */
      sk = __inet6_lookup(&dccp_hashinfo, &ipv6_hdr(skb)->saddr,
                      dh->dccph_sport,
                      &ipv6_hdr(skb)->daddr, ntohs(dh->dccph_dport),
                      inet6_iif(skb));
      /*
       * Step 2:
       *    If no socket ...
       */
      if (sk == NULL) {
            dccp_pr_debug("failed to look up flow ID in table and "
                        "get corresponding socket\n");
            goto no_dccp_socket;
      }

      /*
       * Step 2:
       *    ... or S.state == TIMEWAIT,
       *          Generate Reset(No Connection) unless P.type == Reset
       *          Drop packet and return
       */
      if (sk->sk_state == DCCP_TIME_WAIT) {
            dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: do_time_wait\n");
            inet_twsk_put(inet_twsk(sk));
            goto no_dccp_socket;
      }

      /*
       * RFC 4340, sec. 9.2.1: Minimum Checksum Coverage
       *    o if MinCsCov = 0, only packets with CsCov = 0 are accepted
       *    o if MinCsCov > 0, also accept packets with CsCov >= MinCsCov
       */
      min_cov = dccp_sk(sk)->dccps_pcrlen;
      if (dh->dccph_cscov  &&  (min_cov == 0 || dh->dccph_cscov < min_cov))  {
            dccp_pr_debug("Packet CsCov %d does not satisfy MinCsCov %d\n",
                        dh->dccph_cscov, min_cov);
            /* FIXME: send Data Dropped option (see also dccp_v4_rcv) */
            goto discard_and_relse;
      }

      if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb))
            goto discard_and_relse;

      return sk_receive_skb(sk, skb, 1) ? -1 : 0;

no_dccp_socket:
      if (!xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb))
            goto discard_it;
      /*
       * Step 2:
       *    If no socket ...
       *          Generate Reset(No Connection) unless P.type == Reset
       *          Drop packet and return
       */
      if (dh->dccph_type != DCCP_PKT_RESET) {
            DCCP_SKB_CB(skb)->dccpd_reset_code =
                              DCCP_RESET_CODE_NO_CONNECTION;
            dccp_v6_ctl_send_reset(sk, skb);
      }

discard_it:
      kfree_skb(skb);
      return 0;

discard_and_relse:
      sock_put(sk);
      goto discard_it;
}

static int dccp_v6_connect(struct sock *sk, struct sockaddr *uaddr,
                     int addr_len)
{
      struct sockaddr_in6 *usin = (struct sockaddr_in6 *)uaddr;
      struct inet_connection_sock *icsk = inet_csk(sk);
      struct inet_sock *inet = inet_sk(sk);
      struct ipv6_pinfo *np = inet6_sk(sk);
      struct dccp_sock *dp = dccp_sk(sk);
      struct in6_addr *saddr = NULL, *final_p = NULL, final;
      struct flowi fl;
      struct dst_entry *dst;
      int addr_type;
      int err;

      dp->dccps_role = DCCP_ROLE_CLIENT;

      if (addr_len < SIN6_LEN_RFC2133)
            return -EINVAL;

      if (usin->sin6_family != AF_INET6)
            return -EAFNOSUPPORT;

      memset(&fl, 0, sizeof(fl));

      if (np->sndflow) {
            fl.fl6_flowlabel = usin->sin6_flowinfo & IPV6_FLOWINFO_MASK;
            IP6_ECN_flow_init(fl.fl6_flowlabel);
            if (fl.fl6_flowlabel & IPV6_FLOWLABEL_MASK) {
                  struct ip6_flowlabel *flowlabel;
                  flowlabel = fl6_sock_lookup(sk, fl.fl6_flowlabel);
                  if (flowlabel == NULL)
                        return -EINVAL;
                  ipv6_addr_copy(&usin->sin6_addr, &flowlabel->dst);
                  fl6_sock_release(flowlabel);
            }
      }
      /*
       * connect() to INADDR_ANY means loopback (BSD'ism).
       */
      if (ipv6_addr_any(&usin->sin6_addr))
            usin->sin6_addr.s6_addr[15] = 1;

      addr_type = ipv6_addr_type(&usin->sin6_addr);

      if (addr_type & IPV6_ADDR_MULTICAST)
            return -ENETUNREACH;

      if (addr_type & IPV6_ADDR_LINKLOCAL) {
            if (addr_len >= sizeof(struct sockaddr_in6) &&
                usin->sin6_scope_id) {
                  /* If interface is set while binding, indices
                   * must coincide.
                   */
                  if (sk->sk_bound_dev_if &&
                      sk->sk_bound_dev_if != usin->sin6_scope_id)
                        return -EINVAL;

                  sk->sk_bound_dev_if = usin->sin6_scope_id;
            }

            /* Connect to link-local address requires an interface */
            if (!sk->sk_bound_dev_if)
                  return -EINVAL;
      }

      ipv6_addr_copy(&np->daddr, &usin->sin6_addr);
      np->flow_label = fl.fl6_flowlabel;

      /*
       * DCCP over IPv4
       */
      if (addr_type == IPV6_ADDR_MAPPED) {
            u32 exthdrlen = icsk->icsk_ext_hdr_len;
            struct sockaddr_in sin;

            SOCK_DEBUG(sk, "connect: ipv4 mapped\n");

            if (__ipv6_only_sock(sk))
                  return -ENETUNREACH;

            sin.sin_family = AF_INET;
            sin.sin_port = usin->sin6_port;
            sin.sin_addr.s_addr = usin->sin6_addr.s6_addr32[3];

            icsk->icsk_af_ops = &dccp_ipv6_mapped;
            sk->sk_backlog_rcv = dccp_v4_do_rcv;

            err = dccp_v4_connect(sk, (struct sockaddr *)&sin, sizeof(sin));
            if (err) {
                  icsk->icsk_ext_hdr_len = exthdrlen;
                  icsk->icsk_af_ops = &dccp_ipv6_af_ops;
                  sk->sk_backlog_rcv = dccp_v6_do_rcv;
                  goto failure;
            } else {
                  ipv6_addr_set(&np->saddr, 0, 0, htonl(0x0000FFFF),
                              inet->saddr);
                  ipv6_addr_set(&np->rcv_saddr, 0, 0, htonl(0x0000FFFF),
                              inet->rcv_saddr);
            }

            return err;
      }

      if (!ipv6_addr_any(&np->rcv_saddr))
            saddr = &np->rcv_saddr;

      fl.proto = IPPROTO_DCCP;
      ipv6_addr_copy(&fl.fl6_dst, &np->daddr);
      ipv6_addr_copy(&fl.fl6_src, saddr ? saddr : &np->saddr);
      fl.oif = sk->sk_bound_dev_if;
      fl.fl_ip_dport = usin->sin6_port;
      fl.fl_ip_sport = inet->sport;
      security_sk_classify_flow(sk, &fl);

      if (np->opt != NULL && np->opt->srcrt != NULL) {
            const struct rt0_hdr *rt0 = (struct rt0_hdr *)np->opt->srcrt;

            ipv6_addr_copy(&final, &fl.fl6_dst);
            ipv6_addr_copy(&fl.fl6_dst, rt0->addr);
            final_p = &final;
      }

      err = ip6_dst_lookup(sk, &dst, &fl);
      if (err)
            goto failure;

      if (final_p)
            ipv6_addr_copy(&fl.fl6_dst, final_p);

      err = __xfrm_lookup(&dst, &fl, sk, 1);
      if (err < 0) {
            if (err == -EREMOTE)
                  err = ip6_dst_blackhole(sk, &dst, &fl);
            if (err < 0)
                  goto failure;
      }

      if (saddr == NULL) {
            saddr = &fl.fl6_src;
            ipv6_addr_copy(&np->rcv_saddr, saddr);
      }

      /* set the source address */
      ipv6_addr_copy(&np->saddr, saddr);
      inet->rcv_saddr = LOOPBACK4_IPV6;

      __ip6_dst_store(sk, dst, NULL, NULL);

      icsk->icsk_ext_hdr_len = 0;
      if (np->opt != NULL)
            icsk->icsk_ext_hdr_len = (np->opt->opt_flen +
                                np->opt->opt_nflen);

      inet->dport = usin->sin6_port;

      dccp_set_state(sk, DCCP_REQUESTING);
      err = inet6_hash_connect(&dccp_death_row, sk);
      if (err)
            goto late_failure;

      dp->dccps_iss = secure_dccpv6_sequence_number(np->saddr.s6_addr32,
                                          np->daddr.s6_addr32,
                                          inet->sport, inet->dport);
      err = dccp_connect(sk);
      if (err)
            goto late_failure;

      return 0;

late_failure:
      dccp_set_state(sk, DCCP_CLOSED);
      __sk_dst_reset(sk);
failure:
      inet->dport = 0;
      sk->sk_route_caps = 0;
      return err;
}

static struct inet_connection_sock_af_ops dccp_ipv6_af_ops = {
      .queue_xmit    = inet6_csk_xmit,
      .send_check    = dccp_v6_send_check,
      .rebuild_header      = inet6_sk_rebuild_header,
      .conn_request        = dccp_v6_conn_request,
      .syn_recv_sock       = dccp_v6_request_recv_sock,
      .net_header_len      = sizeof(struct ipv6hdr),
      .setsockopt    = ipv6_setsockopt,
      .getsockopt    = ipv6_getsockopt,
      .addr2sockaddr       = inet6_csk_addr2sockaddr,
      .sockaddr_len        = sizeof(struct sockaddr_in6),
#ifdef CONFIG_COMPAT
      .compat_setsockopt = compat_ipv6_setsockopt,
      .compat_getsockopt = compat_ipv6_getsockopt,
#endif
};

/*
 *    DCCP over IPv4 via INET6 API
 */
static struct inet_connection_sock_af_ops dccp_ipv6_mapped = {
      .queue_xmit    = ip_queue_xmit,
      .send_check    = dccp_v4_send_check,
      .rebuild_header      = inet_sk_rebuild_header,
      .conn_request        = dccp_v6_conn_request,
      .syn_recv_sock       = dccp_v6_request_recv_sock,
      .net_header_len      = sizeof(struct iphdr),
      .setsockopt    = ipv6_setsockopt,
      .getsockopt    = ipv6_getsockopt,
      .addr2sockaddr       = inet6_csk_addr2sockaddr,
      .sockaddr_len        = sizeof(struct sockaddr_in6),
#ifdef CONFIG_COMPAT
      .compat_setsockopt = compat_ipv6_setsockopt,
      .compat_getsockopt = compat_ipv6_getsockopt,
#endif
};

/* NOTE: A lot of things set to zero explicitly by call to
 *       sk_alloc() so need not be done here.
 */
static int dccp_v6_init_sock(struct sock *sk)
{
      static __u8 dccp_v6_ctl_sock_initialized;
      int err = dccp_init_sock(sk, dccp_v6_ctl_sock_initialized);

      if (err == 0) {
            if (unlikely(!dccp_v6_ctl_sock_initialized))
                  dccp_v6_ctl_sock_initialized = 1;
            inet_csk(sk)->icsk_af_ops = &dccp_ipv6_af_ops;
      }

      return err;
}

static int dccp_v6_destroy_sock(struct sock *sk)
{
      dccp_destroy_sock(sk);
      return inet6_destroy_sock(sk);
}

static struct timewait_sock_ops dccp6_timewait_sock_ops = {
      .twsk_obj_size    = sizeof(struct dccp6_timewait_sock),
};

DEFINE_PROTO_INUSE(dccp_v6)

static struct proto dccp_v6_prot = {
      .name          = "DCCPv6",
      .owner               = THIS_MODULE,
      .close               = dccp_close,
      .connect       = dccp_v6_connect,
      .disconnect    = dccp_disconnect,
      .ioctl               = dccp_ioctl,
      .init          = dccp_v6_init_sock,
      .setsockopt    = dccp_setsockopt,
      .getsockopt    = dccp_getsockopt,
      .sendmsg       = dccp_sendmsg,
      .recvmsg       = dccp_recvmsg,
      .backlog_rcv         = dccp_v6_do_rcv,
      .hash          = dccp_v6_hash,
      .unhash              = dccp_unhash,
      .accept              = inet_csk_accept,
      .get_port      = dccp_v6_get_port,
      .shutdown      = dccp_shutdown,
      .destroy       = dccp_v6_destroy_sock,
      .orphan_count        = &dccp_orphan_count,
      .max_header    = MAX_DCCP_HEADER,
      .obj_size      = sizeof(struct dccp6_sock),
      .rsk_prot      = &dccp6_request_sock_ops,
      .twsk_prot     = &dccp6_timewait_sock_ops,
#ifdef CONFIG_COMPAT
      .compat_setsockopt = compat_dccp_setsockopt,
      .compat_getsockopt = compat_dccp_getsockopt,
#endif
      REF_PROTO_INUSE(dccp_v6)
};

static struct inet6_protocol dccp_v6_protocol = {
      .handler    = dccp_v6_rcv,
      .err_handler      = dccp_v6_err,
      .flags            = INET6_PROTO_NOPOLICY | INET6_PROTO_FINAL,
};

static struct proto_ops inet6_dccp_ops = {
      .family              = PF_INET6,
      .owner               = THIS_MODULE,
      .release       = inet6_release,
      .bind          = inet6_bind,
      .connect       = inet_stream_connect,
      .socketpair    = sock_no_socketpair,
      .accept              = inet_accept,
      .getname       = inet6_getname,
      .poll          = dccp_poll,
      .ioctl               = inet6_ioctl,
      .listen              = inet_dccp_listen,
      .shutdown      = inet_shutdown,
      .setsockopt    = sock_common_setsockopt,
      .getsockopt    = sock_common_getsockopt,
      .sendmsg       = inet_sendmsg,
      .recvmsg       = sock_common_recvmsg,
      .mmap          = sock_no_mmap,
      .sendpage      = sock_no_sendpage,
#ifdef CONFIG_COMPAT
      .compat_setsockopt = compat_sock_common_setsockopt,
      .compat_getsockopt = compat_sock_common_getsockopt,
#endif
};

static struct inet_protosw dccp_v6_protosw = {
      .type       = SOCK_DCCP,
      .protocol   = IPPROTO_DCCP,
      .prot       = &dccp_v6_prot,
      .ops        = &inet6_dccp_ops,
      .capability = -1,
      .flags            = INET_PROTOSW_ICSK,
};

static int __init dccp_v6_init(void)
{
      int err = proto_register(&dccp_v6_prot, 1);

      if (err != 0)
            goto out;

      err = inet6_add_protocol(&dccp_v6_protocol, IPPROTO_DCCP);
      if (err != 0)
            goto out_unregister_proto;

      inet6_register_protosw(&dccp_v6_protosw);

      err = inet_csk_ctl_sock_create(&dccp_v6_ctl_socket, PF_INET6,
                               SOCK_DCCP, IPPROTO_DCCP);
      if (err != 0)
            goto out_unregister_protosw;
out:
      return err;
out_unregister_protosw:
      inet6_del_protocol(&dccp_v6_protocol, IPPROTO_DCCP);
      inet6_unregister_protosw(&dccp_v6_protosw);
out_unregister_proto:
      proto_unregister(&dccp_v6_prot);
      goto out;
}

static void __exit dccp_v6_exit(void)
{
      inet6_del_protocol(&dccp_v6_protocol, IPPROTO_DCCP);
      inet6_unregister_protosw(&dccp_v6_protosw);
      proto_unregister(&dccp_v6_prot);
}

module_init(dccp_v6_init);
module_exit(dccp_v6_exit);

/*
 * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33)
 * values directly, Also cover the case where the protocol is not specified,
 * i.e. net-pf-PF_INET6-proto-0-type-SOCK_DCCP
 */
MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET6, 33, 6);
MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET6, 0, 6);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>");
MODULE_DESCRIPTION("DCCPv6 - Datagram Congestion Controlled Protocol");

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