[DCCP]: Initial implementation
Development to this point was done on a subversion repository at:
http://oops.ghostprotocols.net:81/cgi-bin/viewcvs.cgi/dccp-2.6/
This repository will be kept at this site for the foreseable future,
so that interested parties can see the history of this code,
attributions, etc.
If I ever decide to take this offline I'll provide the full history at
some other suitable place.
Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c
new file mode 100644
index 0000000..083baca
--- /dev/null
+++ b/net/dccp/ipv4.c
@@ -0,0 +1,1289 @@
+/*
+ * net/dccp/ipv4.c
+ *
+ * An implementation of the DCCP protocol
+ * Arnaldo Carvalho de Melo <acme@conectiva.com.br>
+ *
+ * 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/config.h>
+#include <linux/dccp.h>
+#include <linux/icmp.h>
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/random.h>
+
+#include <net/icmp.h>
+#include <net/inet_hashtables.h>
+#include <net/sock.h>
+#include <net/tcp_states.h>
+#include <net/xfrm.h>
+
+#include "ccid.h"
+#include "dccp.h"
+
+struct inet_hashinfo __cacheline_aligned dccp_hashinfo = {
+ .lhash_lock = RW_LOCK_UNLOCKED,
+ .lhash_users = ATOMIC_INIT(0),
+ .lhash_wait = __WAIT_QUEUE_HEAD_INITIALIZER(dccp_hashinfo.lhash_wait),
+ .portalloc_lock = SPIN_LOCK_UNLOCKED,
+ .port_rover = 1024 - 1,
+};
+
+static int dccp_v4_get_port(struct sock *sk, const unsigned short snum)
+{
+ return inet_csk_get_port(&dccp_hashinfo, sk, snum);
+}
+
+static void dccp_v4_hash(struct sock *sk)
+{
+ inet_hash(&dccp_hashinfo, sk);
+}
+
+static void dccp_v4_unhash(struct sock *sk)
+{
+ inet_unhash(&dccp_hashinfo, sk);
+}
+
+/* called with local bh disabled */
+static int __dccp_v4_check_established(struct sock *sk, const __u16 lport,
+ struct inet_timewait_sock **twp)
+{
+ struct inet_sock *inet = inet_sk(sk);
+ const u32 daddr = inet->rcv_saddr;
+ const u32 saddr = inet->daddr;
+ const int dif = sk->sk_bound_dev_if;
+ INET_ADDR_COOKIE(acookie, saddr, daddr)
+ const __u32 ports = INET_COMBINED_PORTS(inet->dport, lport);
+ const int hash = inet_ehashfn(daddr, lport, saddr, inet->dport, dccp_hashinfo.ehash_size);
+ struct inet_ehash_bucket *head = &dccp_hashinfo.ehash[hash];
+ const struct sock *sk2;
+ const struct hlist_node *node;
+ struct inet_timewait_sock *tw;
+
+ write_lock(&head->lock);
+
+ /* Check TIME-WAIT sockets first. */
+ sk_for_each(sk2, node, &(head + dccp_hashinfo.ehash_size)->chain) {
+ tw = inet_twsk(sk2);
+
+ if (INET_TW_MATCH(sk2, acookie, saddr, daddr, ports, dif))
+ goto not_unique;
+ }
+ tw = NULL;
+
+ /* And established part... */
+ sk_for_each(sk2, node, &head->chain) {
+ if (INET_MATCH(sk2, acookie, saddr, daddr, ports, dif))
+ goto not_unique;
+ }
+
+ /* Must record num and sport now. Otherwise we will see
+ * in hash table socket with a funny identity. */
+ inet->num = lport;
+ inet->sport = htons(lport);
+ sk->sk_hashent = hash;
+ BUG_TRAP(sk_unhashed(sk));
+ __sk_add_node(sk, &head->chain);
+ sock_prot_inc_use(sk->sk_prot);
+ write_unlock(&head->lock);
+
+ if (twp != NULL) {
+ *twp = tw;
+ NET_INC_STATS_BH(LINUX_MIB_TIMEWAITRECYCLED);
+ } else if (tw != NULL) {
+ /* Silly. Should hash-dance instead... */
+ dccp_tw_deschedule(tw);
+ NET_INC_STATS_BH(LINUX_MIB_TIMEWAITRECYCLED);
+
+ inet_twsk_put(tw);
+ }
+
+ return 0;
+
+not_unique:
+ write_unlock(&head->lock);
+ return -EADDRNOTAVAIL;
+}
+
+/*
+ * Bind a port for a connect operation and hash it.
+ */
+static int dccp_v4_hash_connect(struct sock *sk)
+{
+ const unsigned short snum = inet_sk(sk)->num;
+ struct inet_bind_hashbucket *head;
+ struct inet_bind_bucket *tb;
+ int ret;
+
+ if (snum == 0) {
+ int rover;
+ int low = sysctl_local_port_range[0];
+ int high = sysctl_local_port_range[1];
+ int remaining = (high - low) + 1;
+ struct hlist_node *node;
+ struct inet_timewait_sock *tw = NULL;
+
+ local_bh_disable();
+
+ /* TODO. Actually it is not so bad idea to remove
+ * dccp_hashinfo.portalloc_lock before next submission to Linus.
+ * As soon as we touch this place at all it is time to think.
+ *
+ * Now it protects single _advisory_ variable dccp_hashinfo.port_rover,
+ * hence it is mostly useless.
+ * Code will work nicely if we just delete it, but
+ * I am afraid in contented case it will work not better or
+ * even worse: another cpu just will hit the same bucket
+ * and spin there.
+ * So some cpu salt could remove both contention and
+ * memory pingpong. Any ideas how to do this in a nice way?
+ */
+ spin_lock(&dccp_hashinfo.portalloc_lock);
+ rover = dccp_hashinfo.port_rover;
+
+ do {
+ rover++;
+ if ((rover < low) || (rover > high))
+ rover = low;
+ head = &dccp_hashinfo.bhash[inet_bhashfn(rover, dccp_hashinfo.bhash_size)];
+ spin_lock(&head->lock);
+
+ /* Does not bother with rcv_saddr checks,
+ * because the established check is already
+ * unique enough.
+ */
+ inet_bind_bucket_for_each(tb, node, &head->chain) {
+ if (tb->port == rover) {
+ BUG_TRAP(!hlist_empty(&tb->owners));
+ if (tb->fastreuse >= 0)
+ goto next_port;
+ if (!__dccp_v4_check_established(sk,
+ rover,
+ &tw))
+ goto ok;
+ goto next_port;
+ }
+ }
+
+ tb = inet_bind_bucket_create(dccp_hashinfo.bind_bucket_cachep, head, rover);
+ if (tb == NULL) {
+ spin_unlock(&head->lock);
+ break;
+ }
+ tb->fastreuse = -1;
+ goto ok;
+
+ next_port:
+ spin_unlock(&head->lock);
+ } while (--remaining > 0);
+ dccp_hashinfo.port_rover = rover;
+ spin_unlock(&dccp_hashinfo.portalloc_lock);
+
+ local_bh_enable();
+
+ return -EADDRNOTAVAIL;
+
+ok:
+ /* All locks still held and bhs disabled */
+ dccp_hashinfo.port_rover = rover;
+ spin_unlock(&dccp_hashinfo.portalloc_lock);
+
+ inet_bind_hash(sk, tb, rover);
+ if (sk_unhashed(sk)) {
+ inet_sk(sk)->sport = htons(rover);
+ __inet_hash(&dccp_hashinfo, sk, 0);
+ }
+ spin_unlock(&head->lock);
+
+ if (tw != NULL) {
+ dccp_tw_deschedule(tw);
+ inet_twsk_put(tw);
+ }
+
+ ret = 0;
+ goto out;
+ }
+
+ head = &dccp_hashinfo.bhash[inet_bhashfn(snum, dccp_hashinfo.bhash_size)];
+ tb = inet_csk(sk)->icsk_bind_hash;
+ spin_lock_bh(&head->lock);
+ if (sk_head(&tb->owners) == sk && sk->sk_bind_node.next == NULL) {
+ __inet_hash(&dccp_hashinfo, sk, 0);
+ spin_unlock_bh(&head->lock);
+ return 0;
+ } else {
+ spin_unlock(&head->lock);
+ /* No definite answer... Walk to established hash table */
+ ret = __dccp_v4_check_established(sk, snum, NULL);
+out:
+ local_bh_enable();
+ return ret;
+ }
+}
+
+static int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr,
+ int addr_len)
+{
+ struct inet_sock *inet = inet_sk(sk);
+ struct dccp_sock *dp = dccp_sk(sk);
+ const struct sockaddr_in *usin = (struct sockaddr_in *)uaddr;
+ struct rtable *rt;
+ u32 daddr, nexthop;
+ int tmp;
+ int err;
+
+ dp->dccps_role = DCCP_ROLE_CLIENT;
+
+ if (addr_len < sizeof(struct sockaddr_in))
+ return -EINVAL;
+
+ if (usin->sin_family != AF_INET)
+ return -EAFNOSUPPORT;
+
+ nexthop = daddr = usin->sin_addr.s_addr;
+ if (inet->opt != NULL && inet->opt->srr) {
+ if (daddr == 0)
+ return -EINVAL;
+ nexthop = inet->opt->faddr;
+ }
+
+ tmp = ip_route_connect(&rt, nexthop, inet->saddr,
+ RT_CONN_FLAGS(sk), sk->sk_bound_dev_if,
+ IPPROTO_DCCP,
+ inet->sport, usin->sin_port, sk);
+ if (tmp < 0)
+ return tmp;
+
+ if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) {
+ ip_rt_put(rt);
+ return -ENETUNREACH;
+ }
+
+ if (inet->opt == NULL || !inet->opt->srr)
+ daddr = rt->rt_dst;
+
+ if (inet->saddr == 0)
+ inet->saddr = rt->rt_src;
+ inet->rcv_saddr = inet->saddr;
+
+ inet->dport = usin->sin_port;
+ inet->daddr = daddr;
+
+ dp->dccps_ext_header_len = 0;
+ if (inet->opt != NULL)
+ dp->dccps_ext_header_len = inet->opt->optlen;
+ /*
+ * Socket identity is still unknown (sport may be zero).
+ * However we set state to DCCP_REQUESTING and not releasing socket
+ * lock select source port, enter ourselves into the hash tables and
+ * complete initialization after this.
+ */
+ dccp_set_state(sk, DCCP_REQUESTING);
+ err = dccp_v4_hash_connect(sk);
+ if (err != 0)
+ goto failure;
+
+ err = ip_route_newports(&rt, inet->sport, inet->dport, sk);
+ if (err != 0)
+ goto failure;
+
+ /* OK, now commit destination to socket. */
+ sk_setup_caps(sk, &rt->u.dst);
+
+ dp->dccps_gar =
+ dp->dccps_iss = secure_dccp_sequence_number(inet->saddr,
+ inet->daddr,
+ inet->sport,
+ usin->sin_port);
+ dccp_update_gss(sk, dp->dccps_iss);
+
+ inet->id = dp->dccps_iss ^ jiffies;
+
+ err = dccp_connect(sk);
+ rt = NULL;
+ if (err != 0)
+ goto failure;
+out:
+ return err;
+failure:
+ /* This unhashes the socket and releases the local port, if necessary. */
+ dccp_set_state(sk, DCCP_CLOSED);
+ ip_rt_put(rt);
+ sk->sk_route_caps = 0;
+ inet->dport = 0;
+ goto out;
+}
+
+/*
+ * This routine does path mtu discovery as defined in RFC1191.
+ */
+static inline void dccp_do_pmtu_discovery(struct sock *sk,
+ const struct iphdr *iph,
+ u32 mtu)
+{
+ struct dst_entry *dst;
+ const struct inet_sock *inet = inet_sk(sk);
+ const struct dccp_sock *dp = dccp_sk(sk);
+
+ /* We are not interested in DCCP_LISTEN and request_socks (RESPONSEs
+ * send out by Linux are always < 576bytes so they should go through
+ * unfragmented).
+ */
+ if (sk->sk_state == DCCP_LISTEN)
+ return;
+
+ /* We don't check in the destentry if pmtu discovery is forbidden
+ * on this route. We just assume that no packet_to_big packets
+ * are send back when pmtu discovery is not active.
+ * There is a small race when the user changes this flag in the
+ * route, but I think that's acceptable.
+ */
+ if ((dst = __sk_dst_check(sk, 0)) == NULL)
+ return;
+
+ dst->ops->update_pmtu(dst, mtu);
+
+ /* Something is about to be wrong... Remember soft error
+ * for the case, if this connection will not able to recover.
+ */
+ if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst))
+ sk->sk_err_soft = EMSGSIZE;
+
+ mtu = dst_mtu(dst);
+
+ if (inet->pmtudisc != IP_PMTUDISC_DONT &&
+ dp->dccps_pmtu_cookie > mtu) {
+ dccp_sync_mss(sk, mtu);
+
+ /*
+ * From: draft-ietf-dccp-spec-11.txt
+ *
+ * DCCP-Sync packets are the best choice for upward probing,
+ * since DCCP-Sync probes do not risk application data loss.
+ */
+ dccp_send_sync(sk, dp->dccps_gsr);
+ } /* else let the usual retransmit timer handle it */
+}
+
+static void dccp_v4_ctl_send_ack(struct sk_buff *rxskb)
+{
+ int err;
+ struct dccp_hdr *rxdh = dccp_hdr(rxskb), *dh;
+ const int dccp_hdr_ack_len = sizeof(struct dccp_hdr) +
+ sizeof(struct dccp_hdr_ext) +
+ sizeof(struct dccp_hdr_ack_bits);
+ struct sk_buff *skb;
+
+ if (((struct rtable *)rxskb->dst)->rt_type != RTN_LOCAL)
+ return;
+
+ skb = alloc_skb(MAX_DCCP_HEADER + 15, GFP_ATOMIC);
+ if (skb == NULL)
+ return;
+
+ /* Reserve space for headers. */
+ skb_reserve(skb, MAX_DCCP_HEADER);
+
+ skb->dst = dst_clone(rxskb->dst);
+
+ skb->h.raw = skb_push(skb, dccp_hdr_ack_len);
+ dh = dccp_hdr(skb);
+ memset(dh, 0, dccp_hdr_ack_len);
+
+ /* Build DCCP header and checksum it. */
+ dh->dccph_type = DCCP_PKT_ACK;
+ dh->dccph_sport = rxdh->dccph_dport;
+ dh->dccph_dport = rxdh->dccph_sport;
+ dh->dccph_doff = dccp_hdr_ack_len / 4;
+ dh->dccph_x = 1;
+
+ dccp_hdr_set_seq(dh, DCCP_SKB_CB(rxskb)->dccpd_ack_seq);
+ dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), DCCP_SKB_CB(rxskb)->dccpd_seq);
+
+ bh_lock_sock(dccp_ctl_socket->sk);
+ err = ip_build_and_send_pkt(skb, dccp_ctl_socket->sk,
+ rxskb->nh.iph->daddr, rxskb->nh.iph->saddr, NULL);
+ bh_unlock_sock(dccp_ctl_socket->sk);
+
+ if (err == NET_XMIT_CN || err == 0) {
+ DCCP_INC_STATS_BH(DCCP_MIB_OUTSEGS);
+ DCCP_INC_STATS_BH(DCCP_MIB_OUTRSTS);
+ }
+}
+
+static void dccp_v4_reqsk_send_ack(struct sk_buff *skb, struct request_sock *req)
+{
+ dccp_v4_ctl_send_ack(skb);
+}
+
+static int dccp_v4_send_response(struct sock *sk, struct request_sock *req,
+ struct dst_entry *dst)
+{
+ int err = -1;
+ struct sk_buff *skb;
+
+ /* First, grab a route. */
+
+ if (dst == NULL && (dst = inet_csk_route_req(sk, req)) == NULL)
+ goto out;
+
+ skb = dccp_make_response(sk, dst, req);
+ if (skb != NULL) {
+ const struct inet_request_sock *ireq = inet_rsk(req);
+
+ err = ip_build_and_send_pkt(skb, sk, ireq->loc_addr,
+ ireq->rmt_addr,
+ ireq->opt);
+ if (err == NET_XMIT_CN)
+ err = 0;
+ }
+
+out:
+ dst_release(dst);
+ return err;
+}
+
+/*
+ * This routine is called by the ICMP module when it gets some sort of error
+ * condition. If err < 0 then the socket should be closed and the error
+ * returned to the user. If err > 0 it's just the icmp type << 8 | icmp code.
+ * After adjustment header points to the first 8 bytes of the tcp header. We
+ * need to find the appropriate port.
+ *
+ * The locking strategy used here is very "optimistic". When someone else
+ * accesses the socket the ICMP is just dropped and for some paths there is no
+ * check at all. A more general error queue to queue errors for later handling
+ * is probably better.
+ */
+void dccp_v4_err(struct sk_buff *skb, u32 info)
+{
+ const struct iphdr *iph = (struct iphdr *)skb->data;
+ const struct dccp_hdr *dh = (struct dccp_hdr *)(skb->data + (iph->ihl << 2));
+ struct dccp_sock *dp;
+ struct inet_sock *inet;
+ const int type = skb->h.icmph->type;
+ const int code = skb->h.icmph->code;
+ struct sock *sk;
+ __u64 seq;
+ int err;
+
+ if (skb->len < (iph->ihl << 2) + 8) {
+ ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
+ return;
+ }
+
+ sk = inet_lookup(&dccp_hashinfo, iph->daddr, dh->dccph_dport,
+ iph->saddr, dh->dccph_sport, inet_iif(skb));
+ if (sk == NULL) {
+ ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
+ return;
+ }
+
+ if (sk->sk_state == DCCP_TIME_WAIT) {
+ inet_twsk_put((struct inet_timewait_sock *)sk);
+ return;
+ }
+
+ bh_lock_sock(sk);
+ /* If too many ICMPs get dropped on busy
+ * servers this needs to be solved differently.
+ */
+ if (sock_owned_by_user(sk))
+ NET_INC_STATS_BH(LINUX_MIB_LOCKDROPPEDICMPS);
+
+ if (sk->sk_state == DCCP_CLOSED)
+ goto out;
+
+ dp = dccp_sk(sk);
+ seq = dccp_hdr_seq(skb);
+ if (sk->sk_state != DCCP_LISTEN &&
+ !between48(seq, dp->dccps_swl, dp->dccps_swh)) {
+ NET_INC_STATS(LINUX_MIB_OUTOFWINDOWICMPS);
+ goto out;
+ }
+
+ switch (type) {
+ case ICMP_SOURCE_QUENCH:
+ /* Just silently ignore these. */
+ goto out;
+ case ICMP_PARAMETERPROB:
+ err = EPROTO;
+ break;
+ case ICMP_DEST_UNREACH:
+ if (code > NR_ICMP_UNREACH)
+ goto out;
+
+ if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */
+ if (!sock_owned_by_user(sk))
+ dccp_do_pmtu_discovery(sk, iph, info);
+ goto out;
+ }
+
+ err = icmp_err_convert[code].errno;
+ break;
+ case ICMP_TIME_EXCEEDED:
+ err = EHOSTUNREACH;
+ break;
+ default:
+ goto out;
+ }
+
+ switch (sk->sk_state) {
+ struct request_sock *req , **prev;
+ case DCCP_LISTEN:
+ if (sock_owned_by_user(sk))
+ goto out;
+ req = inet_csk_search_req(sk, &prev, dh->dccph_dport,
+ iph->daddr, iph->saddr);
+ if (!req)
+ goto out;
+
+ /*
+ * ICMPs are not backlogged, hence we cannot get an established
+ * socket here.
+ */
+ BUG_TRAP(!req->sk);
+
+ if (seq != dccp_rsk(req)->dreq_iss) {
+ NET_INC_STATS_BH(LINUX_MIB_OUTOFWINDOWICMPS);
+ goto out;
+ }
+ /*
+ * Still in RESPOND, just remove it silently.
+ * There is no good way to pass the error to the newly
+ * created socket, and POSIX does not want network
+ * errors returned from accept().
+ */
+ inet_csk_reqsk_queue_drop(sk, req, prev);
+ goto out;
+
+ case DCCP_REQUESTING:
+ case DCCP_RESPOND:
+ if (!sock_owned_by_user(sk)) {
+ DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS);
+ sk->sk_err = err;
+
+ sk->sk_error_report(sk);
+
+ dccp_done(sk);
+ } else
+ sk->sk_err_soft = err;
+ goto out;
+ }
+
+ /* If we've already connected we will keep trying
+ * until we time out, or the user gives up.
+ *
+ * rfc1122 4.2.3.9 allows to consider as hard errors
+ * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too,
+ * but it is obsoleted by pmtu discovery).
+ *
+ * Note, that in modern internet, where routing is unreliable
+ * and in each dark corner broken firewalls sit, sending random
+ * errors ordered by their masters even this two messages finally lose
+ * their original sense (even Linux sends invalid PORT_UNREACHs)
+ *
+ * Now we are in compliance with RFCs.
+ * --ANK (980905)
+ */
+
+ inet = inet_sk(sk);
+ if (!sock_owned_by_user(sk) && inet->recverr) {
+ sk->sk_err = err;
+ sk->sk_error_report(sk);
+ } else /* Only an error on timeout */
+ sk->sk_err_soft = err;
+out:
+ bh_unlock_sock(sk);
+ sock_put(sk);
+}
+
+extern struct sk_buff *dccp_make_reset(struct sock *sk, struct dst_entry *dst, enum dccp_reset_codes code);
+
+int dccp_v4_send_reset(struct sock *sk, enum dccp_reset_codes code)
+{
+ struct sk_buff *skb;
+ /*
+ * FIXME: what if rebuild_header fails?
+ * Should we be doing a rebuild_header here?
+ */
+ int err = inet_sk_rebuild_header(sk);
+
+ if (err != 0)
+ return err;
+
+ skb = dccp_make_reset(sk, sk->sk_dst_cache, code);
+ if (skb != NULL) {
+ const struct dccp_sock *dp = dccp_sk(sk);
+ const struct inet_sock *inet = inet_sk(sk);
+
+ err = ip_build_and_send_pkt(skb, sk,
+ inet->saddr, inet->daddr, NULL);
+ if (err == NET_XMIT_CN)
+ err = 0;
+
+ ccid_hc_rx_exit(dp->dccps_hc_rx_ccid, sk);
+ ccid_hc_tx_exit(dp->dccps_hc_tx_ccid, sk);
+ }
+
+ return err;
+}
+
+static inline u64 dccp_v4_init_sequence(const struct sock *sk,
+ const struct sk_buff *skb)
+{
+ return secure_dccp_sequence_number(skb->nh.iph->daddr,
+ skb->nh.iph->saddr,
+ dccp_hdr(skb)->dccph_dport,
+ dccp_hdr(skb)->dccph_sport);
+}
+
+int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
+{
+ struct inet_request_sock *ireq;
+ struct dccp_sock dp;
+ struct request_sock *req;
+ struct dccp_request_sock *dreq;
+ const __u32 saddr = skb->nh.iph->saddr;
+ const __u32 daddr = skb->nh.iph->daddr;
+ struct dst_entry *dst = NULL;
+
+ /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */
+ if (((struct rtable *)skb->dst)->rt_flags &
+ (RTCF_BROADCAST | RTCF_MULTICAST))
+ goto drop;
+
+ /*
+ * TW buckets are converted to open requests without
+ * limitations, they conserve resources and peer is
+ * evidently real one.
+ */
+ if (inet_csk_reqsk_queue_is_full(sk))
+ goto drop;
+
+ /*
+ * Accept backlog is full. If we have already queued enough
+ * of warm entries in syn queue, drop request. It is better than
+ * clogging syn queue with openreqs with exponentially increasing
+ * timeout.
+ */
+ if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1)
+ goto drop;
+
+ req = reqsk_alloc(sk->sk_prot->rsk_prot);
+ if (req == NULL)
+ goto drop;
+
+ /* FIXME: process options */
+
+ dccp_openreq_init(req, &dp, skb);
+
+ ireq = inet_rsk(req);
+ ireq->loc_addr = daddr;
+ ireq->rmt_addr = saddr;
+ /* FIXME: Merge Aristeu's option parsing code when ready */
+ req->rcv_wnd = 100; /* Fake, option parsing will get the right value */
+ ireq->opt = NULL;
+
+ /*
+ * 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 = DCCP_SKB_CB(skb)->dccpd_seq;
+ dreq->dreq_iss = dccp_v4_init_sequence(sk, skb);
+ dreq->dreq_service = dccp_hdr_request(skb)->dccph_req_service;
+
+ if (dccp_v4_send_response(sk, req, dst))
+ goto drop_and_free;
+
+ inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT);
+ return 0;
+
+drop_and_free:
+ /*
+ * FIXME: should be reqsk_free after implementing req->rsk_ops
+ */
+ __reqsk_free(req);
+drop:
+ DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS);
+ return -1;
+}
+
+/*
+ * The three way handshake has completed - we got a valid ACK or DATAACK -
+ * now create the new socket.
+ *
+ * This is the equivalent of TCP's tcp_v4_syn_recv_sock
+ */
+struct sock *dccp_v4_request_recv_sock(struct sock *sk, struct sk_buff *skb,
+ struct request_sock *req,
+ struct dst_entry *dst)
+{
+ struct inet_request_sock *ireq;
+ struct inet_sock *newinet;
+ struct dccp_sock *newdp;
+ struct sock *newsk;
+
+ if (sk_acceptq_is_full(sk))
+ goto exit_overflow;
+
+ if (dst == NULL && (dst = inet_csk_route_req(sk, req)) == NULL)
+ goto exit;
+
+ newsk = dccp_create_openreq_child(sk, req, skb);
+ if (newsk == NULL)
+ goto exit;
+
+ sk_setup_caps(newsk, dst);
+
+ newdp = dccp_sk(newsk);
+ newinet = inet_sk(newsk);
+ ireq = inet_rsk(req);
+ newinet->daddr = ireq->rmt_addr;
+ newinet->rcv_saddr = ireq->loc_addr;
+ newinet->saddr = ireq->loc_addr;
+ newinet->opt = ireq->opt;
+ ireq->opt = NULL;
+ newinet->mc_index = inet_iif(skb);
+ newinet->mc_ttl = skb->nh.iph->ttl;
+ newinet->id = jiffies;
+
+ dccp_sync_mss(newsk, dst_mtu(dst));
+
+ __inet_hash(&dccp_hashinfo, newsk, 0);
+ __inet_inherit_port(&dccp_hashinfo, sk, newsk);
+
+ return newsk;
+
+exit_overflow:
+ NET_INC_STATS_BH(LINUX_MIB_LISTENOVERFLOWS);
+exit:
+ NET_INC_STATS_BH(LINUX_MIB_LISTENDROPS);
+ dst_release(dst);
+ return NULL;
+}
+
+static struct sock *dccp_v4_hnd_req(struct sock *sk, struct sk_buff *skb)
+{
+ const struct dccp_hdr *dh = dccp_hdr(skb);
+ const struct iphdr *iph = skb->nh.iph;
+ struct sock *nsk;
+ struct request_sock **prev;
+ /* Find possible connection requests. */
+ struct request_sock *req = inet_csk_search_req(sk, &prev,
+ dh->dccph_sport,
+ iph->saddr, iph->daddr);
+ if (req != NULL)
+ return dccp_check_req(sk, skb, req, prev);
+
+ nsk = __inet_lookup_established(&dccp_hashinfo,
+ iph->saddr, dh->dccph_sport,
+ iph->daddr, ntohs(dh->dccph_dport),
+ inet_iif(skb));
+ if (nsk != NULL) {
+ if (nsk->sk_state != DCCP_TIME_WAIT) {
+ bh_lock_sock(nsk);
+ return nsk;
+ }
+ inet_twsk_put((struct inet_timewait_sock *)nsk);
+ return NULL;
+ }
+
+ return sk;
+}
+
+int dccp_v4_checksum(struct sk_buff *skb)
+{
+ struct dccp_hdr* dh = dccp_hdr(skb);
+ int checksum_len;
+ u32 tmp;
+
+ if (dh->dccph_cscov == 0)
+ checksum_len = skb->len;
+ else {
+ checksum_len = (dh->dccph_cscov + dh->dccph_x) * sizeof(u32);
+ checksum_len = checksum_len < skb->len ? checksum_len : skb->len;
+ }
+
+ tmp = csum_partial((unsigned char *)dh, checksum_len, 0);
+ return csum_fold(tmp);
+}
+
+static int dccp_v4_verify_checksum(struct sk_buff *skb)
+{
+ struct dccp_hdr *th = dccp_hdr(skb);
+ const u16 remote_checksum = th->dccph_checksum;
+ u16 local_checksum;
+
+ /* FIXME: don't mess with skb payload */
+ th->dccph_checksum = 0; /* zero it for computation */
+
+ local_checksum = dccp_v4_checksum(skb);
+
+ /* FIXME: don't mess with skb payload */
+ th->dccph_checksum = remote_checksum; /* put it back */
+
+ return remote_checksum == local_checksum ? 0 : -1;
+}
+
+static struct dst_entry* dccp_v4_route_skb(struct sock *sk,
+ struct sk_buff *skb)
+{
+ struct rtable *rt;
+ struct flowi fl = { .oif = ((struct rtable *)skb->dst)->rt_iif,
+ .nl_u = { .ip4_u =
+ { .daddr = skb->nh.iph->saddr,
+ .saddr = skb->nh.iph->daddr,
+ .tos = RT_CONN_FLAGS(sk) } },
+ .proto = sk->sk_protocol,
+ .uli_u = { .ports =
+ { .sport = dccp_hdr(skb)->dccph_dport,
+ .dport = dccp_hdr(skb)->dccph_sport } } };
+
+ if (ip_route_output_flow(&rt, &fl, sk, 0)) {
+ IP_INC_STATS_BH(IPSTATS_MIB_OUTNOROUTES);
+ return NULL;
+ }
+
+ return &rt->u.dst;
+}
+
+void dccp_v4_ctl_send_reset(struct sk_buff *rxskb)
+{
+ int err;
+ struct dccp_hdr *rxdh = dccp_hdr(rxskb), *dh;
+ const int dccp_hdr_reset_len = sizeof(struct dccp_hdr) +
+ sizeof(struct dccp_hdr_ext) +
+ sizeof(struct dccp_hdr_reset);
+ struct sk_buff *skb;
+ struct dst_entry *dst;
+
+ /* Never send a reset in response to a reset. */
+ if (rxdh->dccph_type == DCCP_PKT_RESET)
+ return;
+
+ if (((struct rtable *)rxskb->dst)->rt_type != RTN_LOCAL)
+ return;
+
+ dst = dccp_v4_route_skb(dccp_ctl_socket->sk, rxskb);
+ if (dst == NULL)
+ return;
+
+ skb = alloc_skb(MAX_DCCP_HEADER + 15, GFP_ATOMIC);
+ if (skb == NULL)
+ goto out;
+
+ /* Reserve space for headers. */
+ skb_reserve(skb, MAX_DCCP_HEADER);
+ skb->dst = dst_clone(dst);
+
+ skb->h.raw = skb_push(skb, dccp_hdr_reset_len);
+ dh = dccp_hdr(skb);
+ memset(dh, 0, dccp_hdr_reset_len);
+
+ /* Build DCCP header and checksum it. */
+ dh->dccph_type = DCCP_PKT_RESET;
+ dh->dccph_sport = rxdh->dccph_dport;
+ dh->dccph_dport = rxdh->dccph_sport;
+ dh->dccph_doff = dccp_hdr_reset_len / 4;
+ dh->dccph_x = 1;
+ dccp_hdr_reset(skb)->dccph_reset_code = DCCP_SKB_CB(rxskb)->dccpd_reset_code;
+
+ dccp_hdr_set_seq(dh, DCCP_SKB_CB(rxskb)->dccpd_ack_seq);
+ dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), DCCP_SKB_CB(rxskb)->dccpd_seq);
+
+ dh->dccph_checksum = dccp_v4_checksum(skb);
+
+ bh_lock_sock(dccp_ctl_socket->sk);
+ err = ip_build_and_send_pkt(skb, dccp_ctl_socket->sk,
+ rxskb->nh.iph->daddr, rxskb->nh.iph->saddr, NULL);
+ bh_unlock_sock(dccp_ctl_socket->sk);
+
+ if (err == NET_XMIT_CN || err == 0) {
+ DCCP_INC_STATS_BH(DCCP_MIB_OUTSEGS);
+ DCCP_INC_STATS_BH(DCCP_MIB_OUTRSTS);
+ }
+out:
+ dst_release(dst);
+}
+
+int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
+{
+ struct dccp_hdr *dh = dccp_hdr(skb);
+
+ if (sk->sk_state == DCCP_OPEN) { /* Fast path */
+ if (dccp_rcv_established(sk, skb, dh, skb->len))
+ goto reset;
+ 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 an Init
+ * Cookie. Only the Init Cookie is 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 Cookie
+ * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
+ * 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_v4_hnd_req(sk, skb);
+
+ if (nsk == NULL)
+ goto discard;
+
+ if (nsk != sk) {
+ if (dccp_child_process(sk, nsk, skb))
+ goto reset;
+ return 0;
+ }
+ }
+
+ if (dccp_rcv_state_process(sk, skb, dh, skb->len))
+ goto reset;
+ return 0;
+
+reset:
+ DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION;
+ dccp_v4_ctl_send_reset(skb);
+discard:
+ kfree_skb(skb);
+ return 0;
+}
+
+static inline int dccp_invalid_packet(struct sk_buff *skb)
+{
+ const struct dccp_hdr *dh;
+
+ if (skb->pkt_type != PACKET_HOST)
+ return 1;
+
+ if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) {
+ dccp_pr_debug("pskb_may_pull failed\n");
+ return 1;
+ }
+
+ dh = dccp_hdr(skb);
+
+ /* If the packet type is not understood, drop packet and return */
+ if (dh->dccph_type >= DCCP_PKT_INVALID) {
+ dccp_pr_debug("invalid packet type\n");
+ return 1;
+ }
+
+ /*
+ * If P.Data Offset is too small for packet type, or too large for
+ * packet, drop packet and return
+ */
+ if (dh->dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) {
+ dccp_pr_debug("Offset(%u) too small 1\n", dh->dccph_doff);
+ return 1;
+ }
+
+ if (!pskb_may_pull(skb, dh->dccph_doff * sizeof(u32))) {
+ dccp_pr_debug("P.Data Offset(%u) too small 2\n", dh->dccph_doff);
+ return 1;
+ }
+
+ dh = dccp_hdr(skb);
+
+ /*
+ * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet
+ * has short sequence numbers), drop packet and return
+ */
+ if (dh->dccph_x == 0 &&
+ dh->dccph_type != DCCP_PKT_DATA &&
+ dh->dccph_type != DCCP_PKT_ACK &&
+ dh->dccph_type != DCCP_PKT_DATAACK) {
+ dccp_pr_debug("P.type (%s) not Data, Ack nor DataAck and P.X == 0\n",
+ dccp_packet_name(dh->dccph_type));
+ return 1;
+ }
+
+ /* If the header checksum is incorrect, drop packet and return */
+ if (dccp_v4_verify_checksum(skb) < 0) {
+ dccp_pr_debug("header checksum is incorrect\n");
+ return 1;
+ }
+
+ return 0;
+}
+
+/* this is called when real data arrives */
+int dccp_v4_rcv(struct sk_buff *skb)
+{
+ const struct dccp_hdr *dh;
+ struct sock *sk;
+ int rc;
+
+ /* Step 1: Check header basics: */
+
+ if (dccp_invalid_packet(skb))
+ goto discard_it;
+
+ dh = dccp_hdr(skb);
+#if 0
+ /*
+ * Use something like this to simulate some DATA/DATAACK loss to test
+ * dccp_ackpkts_add, you'll get something like this on a session that
+ * sends 10 DATA/DATAACK packets:
+ *
+ * dccp_ackpkts_print: 281473596467422 |0,0|3,0|0,0|3,0|0,0|3,0|0,0|3,0|0,1|
+ *
+ * 0, 0 means: DCCP_ACKPKTS_STATE_RECEIVED, RLE == just this packet
+ * 0, 1 means: DCCP_ACKPKTS_STATE_RECEIVED, RLE == two adjacent packets with the same state
+ * 3, 0 means: DCCP_ACKPKTS_STATE_NOT_RECEIVED, RLE == just this packet
+ *
+ * So...
+ *
+ * 281473596467422 was received
+ * 281473596467421 was not received
+ * 281473596467420 was received
+ * 281473596467419 was not received
+ * 281473596467418 was received
+ * 281473596467417 was not received
+ * 281473596467416 was received
+ * 281473596467415 was not received
+ * 281473596467414 was received
+ * 281473596467413 was received (this one was the 3way handshake RESPONSE)
+ *
+ */
+ if (dh->dccph_type == DCCP_PKT_DATA || dh->dccph_type == DCCP_PKT_DATAACK) {
+ static int discard = 0;
+
+ if (discard) {
+ discard = 0;
+ goto discard_it;
+ }
+ discard = 1;
+ }
+#endif
+ DCCP_SKB_CB(skb)->dccpd_seq = dccp_hdr_seq(skb);
+ DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type;
+
+ dccp_pr_debug("%8.8s "
+ "src=%u.%u.%u.%u@%-5d "
+ "dst=%u.%u.%u.%u@%-5d seq=%llu",
+ dccp_packet_name(dh->dccph_type),
+ NIPQUAD(skb->nh.iph->saddr), ntohs(dh->dccph_sport),
+ NIPQUAD(skb->nh.iph->daddr), ntohs(dh->dccph_dport),
+ DCCP_SKB_CB(skb)->dccpd_seq);
+
+ if (dccp_packet_without_ack(skb)) {
+ DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ;
+ dccp_pr_debug_cat("\n");
+ } else {
+ DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb);
+ dccp_pr_debug_cat(", ack=%llu\n", DCCP_SKB_CB(skb)->dccpd_ack_seq);
+ }
+
+ /* Step 2:
+ * Look up flow ID in table and get corresponding socket */
+ sk = __inet_lookup(&dccp_hashinfo,
+ skb->nh.iph->saddr, dh->dccph_sport,
+ skb->nh.iph->daddr, ntohs(dh->dccph_dport),
+ inet_iif(skb));
+
+ /*
+ * Step 2:
+ * If no socket ...
+ * Generate Reset(No Connection) unless P.type == Reset
+ * Drop packet and return
+ */
+ 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: discard_and_relse\n");
+ goto discard_and_relse;
+ }
+
+ if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb)) {
+ dccp_pr_debug("xfrm4_policy_check failed\n");
+ goto discard_and_relse;
+ }
+
+ if (sk_filter(sk, skb, 0)) {
+ dccp_pr_debug("sk_filter failed\n");
+ goto discard_and_relse;
+ }
+
+ skb->dev = NULL;
+
+ bh_lock_sock(sk);
+ rc = 0;
+ if (!sock_owned_by_user(sk))
+ rc = dccp_v4_do_rcv(sk, skb);
+ else
+ sk_add_backlog(sk, skb);
+ bh_unlock_sock(sk);
+
+ sock_put(sk);
+ return rc;
+
+no_dccp_socket:
+ if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
+ goto discard_it;
+ /*
+ * Step 2:
+ * 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_v4_ctl_send_reset(skb);
+ }
+
+discard_it:
+ /* Discard frame. */
+ kfree_skb(skb);
+ return 0;
+
+discard_and_relse:
+ sock_put(sk);
+ goto discard_it;
+}
+
+static int dccp_v4_init_sock(struct sock *sk)
+{
+ struct dccp_sock *dp = dccp_sk(sk);
+ static int dccp_ctl_socket_init = 1;
+
+ dccp_options_init(&dp->dccps_options);
+
+ if (dp->dccps_options.dccpo_send_ack_vector) {
+ dp->dccps_hc_rx_ackpkts = dccp_ackpkts_alloc(DCCP_MAX_ACK_VECTOR_LEN,
+ GFP_KERNEL);
+
+ if (dp->dccps_hc_rx_ackpkts == NULL)
+ return -ENOMEM;
+ }
+
+ /*
+ * FIXME: We're hardcoding the CCID, and doing this at this point makes
+ * the listening (master) sock get CCID control blocks, which is not
+ * necessary, but for now, to not mess with the test userspace apps,
+ * lets leave it here, later the real solution is to do this in a
+ * setsockopt(CCIDs-I-want/accept). -acme
+ */
+ if (likely(!dccp_ctl_socket_init)) {
+ dp->dccps_hc_rx_ccid = ccid_init(dp->dccps_options.dccpo_ccid, sk);
+ dp->dccps_hc_tx_ccid = ccid_init(dp->dccps_options.dccpo_ccid, sk);
+ if (dp->dccps_hc_rx_ccid == NULL ||
+ dp->dccps_hc_tx_ccid == NULL) {
+ ccid_exit(dp->dccps_hc_rx_ccid, sk);
+ ccid_exit(dp->dccps_hc_tx_ccid, sk);
+ dccp_ackpkts_free(dp->dccps_hc_rx_ackpkts);
+ dp->dccps_hc_rx_ackpkts = NULL;
+ dp->dccps_hc_rx_ccid = dp->dccps_hc_tx_ccid = NULL;
+ return -ENOMEM;
+ }
+ } else
+ dccp_ctl_socket_init = 0;
+
+ dccp_init_xmit_timers(sk);
+ sk->sk_state = DCCP_CLOSED;
+ dp->dccps_mss_cache = 536;
+ dp->dccps_role = DCCP_ROLE_UNDEFINED;
+
+ return 0;
+}
+
+int dccp_v4_destroy_sock(struct sock *sk)
+{
+ struct dccp_sock *dp = dccp_sk(sk);
+
+ /*
+ * DCCP doesn't use sk_qrite_queue, just sk_send_head
+ * for retransmissions
+ */
+ if (sk->sk_send_head != NULL) {
+ kfree_skb(sk->sk_send_head);
+ sk->sk_send_head = NULL;
+ }
+
+ /* Clean up a referenced DCCP bind bucket. */
+ if (inet_csk(sk)->icsk_bind_hash != NULL)
+ inet_put_port(&dccp_hashinfo, sk);
+
+ dccp_ackpkts_free(dp->dccps_hc_rx_ackpkts);
+ dp->dccps_hc_rx_ackpkts = NULL;
+ ccid_exit(dp->dccps_hc_rx_ccid, sk);
+ ccid_exit(dp->dccps_hc_tx_ccid, sk);
+ dp->dccps_hc_rx_ccid = dp->dccps_hc_tx_ccid = NULL;
+
+ return 0;
+}
+
+static void dccp_v4_reqsk_destructor(struct request_sock *req)
+{
+ kfree(inet_rsk(req)->opt);
+}
+
+static struct request_sock_ops dccp_request_sock_ops = {
+ .family = PF_INET,
+ .obj_size = sizeof(struct dccp_request_sock),
+ .rtx_syn_ack = dccp_v4_send_response,
+ .send_ack = dccp_v4_reqsk_send_ack,
+ .destructor = dccp_v4_reqsk_destructor,
+ .send_reset = dccp_v4_ctl_send_reset,
+};
+
+struct proto dccp_v4_prot = {
+ .name = "DCCP",
+ .owner = THIS_MODULE,
+ .close = dccp_close,
+ .connect = dccp_v4_connect,
+ .disconnect = dccp_disconnect,
+ .ioctl = dccp_ioctl,
+ .init = dccp_v4_init_sock,
+ .setsockopt = dccp_setsockopt,
+ .getsockopt = dccp_getsockopt,
+ .sendmsg = dccp_sendmsg,
+ .recvmsg = dccp_recvmsg,
+ .backlog_rcv = dccp_v4_do_rcv,
+ .hash = dccp_v4_hash,
+ .unhash = dccp_v4_unhash,
+ .accept = inet_csk_accept,
+ .get_port = dccp_v4_get_port,
+ .shutdown = dccp_shutdown,
+ .destroy = dccp_v4_destroy_sock,
+ .orphan_count = &dccp_orphan_count,
+ .max_header = MAX_DCCP_HEADER,
+ .obj_size = sizeof(struct dccp_sock),
+ .rsk_prot = &dccp_request_sock_ops,
+ .twsk_obj_size = sizeof(struct inet_timewait_sock), /* FIXME! create dccp_timewait_sock */
+};