3 files changed, 131 insertions, 46 deletions

diff --git a/include/linux/dccp.h b/include/linux/dccp.h
index 8b3f9ad3cf04..312b989c7edb 100644
--- a/include/linux/dccp.h
+++ b/include/linux/dccp.h
@@ -260,7 +260,6 @@ enum dccp_state {
 };
 
 #define DCCP_STATE_MASK 0x1f
-#define DCCP_ACTION_FIN (1<<7)
 
 enum {
         DCCPF_OPEN            = TCPF_ESTABLISHED,
diff --git a/net/dccp/input.c b/net/dccp/input.c
index ef299fbd7c26..fe4b0fbfa508 100644
--- a/net/dccp/input.c
+++ b/net/dccp/input.c
@@ -32,16 +32,56 @@ static void dccp_fin(struct sock *sk, struct sk_buff *skb)
         sk->sk_data_ready(sk, 0);
 }
 
-static void dccp_rcv_close(struct sock *sk, struct sk_buff *skb)
+static int dccp_rcv_close(struct sock *sk, struct sk_buff *skb)
 {
-        dccp_send_reset(sk, DCCP_RESET_CODE_CLOSED);
-        dccp_fin(sk, skb);
-        dccp_set_state(sk, DCCP_CLOSED);
-        sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_HUP);
+        int queued = 0;
+
+        switch (sk->sk_state) {
+        /*
+         * We ignore Close when received in one of the following states:
+         *  - CLOSED            (may be a late or duplicate packet)
+         *  - PASSIVE_CLOSEREQ  (the peer has sent a CloseReq earlier)
+         *  - RESPOND           (already handled by dccp_check_req)
+         */
+        case DCCP_CLOSING:
+                /*
+                 * Simultaneous-close: receiving a Close after sending one. This
+                 * can happen if both client and server perform active-close and
+                 * will result in an endless ping-pong of crossing and retrans-
+                 * mitted Close packets, which only terminates when one of the
+                 * nodes times out (min. 64 seconds). Quicker convergence can be
+                 * achieved when one of the nodes acts as tie-breaker.
+                 * This is ok as both ends are done with data transfer and each
+                 * end is just waiting for the other to acknowledge termination.
+                 */
+                if (dccp_sk(sk)->dccps_role != DCCP_ROLE_CLIENT)
+                        break;
+                /* fall through */
+        case DCCP_REQUESTING:
+        case DCCP_ACTIVE_CLOSEREQ:
+                dccp_send_reset(sk, DCCP_RESET_CODE_CLOSED);
+                dccp_done(sk);
+                break;
+        case DCCP_OPEN:
+        case DCCP_PARTOPEN:
+                /* Give waiting application a chance to read pending data */
+                queued = 1;
+                dccp_fin(sk, skb);
+                dccp_set_state(sk, DCCP_PASSIVE_CLOSE);
+                /* fall through */
+        case DCCP_PASSIVE_CLOSE:
+                /*
+                 * Retransmitted Close: we have already enqueued the first one.
+                 */
+                sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_HUP);
+        }
+        return queued;
 }
 
-static void dccp_rcv_closereq(struct sock *sk, struct sk_buff *skb)
+static int dccp_rcv_closereq(struct sock *sk, struct sk_buff *skb)
 {
+        int queued = 0;
+
         /*
          *   Step 7: Check for unexpected packet types
          *      If (S.is_server and P.type == CloseReq)
@@ -50,12 +90,26 @@ static void dccp_rcv_closereq(struct sock *sk, struct sk_buff *skb)
          */
         if (dccp_sk(sk)->dccps_role != DCCP_ROLE_CLIENT) {
                 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, DCCP_PKT_SYNC);
-                return;
+                return queued;
         }
 
-        if (sk->sk_state != DCCP_CLOSING)
+        /* Step 13: process relevant Client states < CLOSEREQ */
+        switch (sk->sk_state) {
+        case DCCP_REQUESTING:
+                dccp_send_close(sk, 0);
                 dccp_set_state(sk, DCCP_CLOSING);
-        dccp_send_close(sk, 0);
+                break;
+        case DCCP_OPEN:
+        case DCCP_PARTOPEN:
+                /* Give waiting application a chance to read pending data */
+                queued = 1;
+                dccp_fin(sk, skb);
+                dccp_set_state(sk, DCCP_PASSIVE_CLOSEREQ);
+                /* fall through */
+        case DCCP_PASSIVE_CLOSEREQ:
+                sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_HUP);
+        }
+        return queued;
 }
 
 static u8 dccp_reset_code_convert(const u8 code)
@@ -247,11 +301,13 @@ static int __dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
                 dccp_rcv_reset(sk, skb);
                 return 0;
         case DCCP_PKT_CLOSEREQ:
-                dccp_rcv_closereq(sk, skb);
+                if (dccp_rcv_closereq(sk, skb))
+                        return 0;
                 goto discard;
         case DCCP_PKT_CLOSE:
-                dccp_rcv_close(sk, skb);
-                return 0;
+                if (dccp_rcv_close(sk, skb))
+                        return 0;
+                goto discard;
         case DCCP_PKT_REQUEST:
                 /* Step 7
                  *   or (S.is_server and P.type == Response)
@@ -590,11 +646,13 @@ int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
                 dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNC);
                 goto discard;
         } else if (dh->dccph_type == DCCP_PKT_CLOSEREQ) {
-                dccp_rcv_closereq(sk, skb);
+                if (dccp_rcv_closereq(sk, skb))
+                        return 0;
                 goto discard;
         } else if (dh->dccph_type == DCCP_PKT_CLOSE) {
-                dccp_rcv_close(sk, skb);
-                return 0;
+                if (dccp_rcv_close(sk, skb))
+                        return 0;
+                goto discard;
         }
 
         switch (sk->sk_state) {
diff --git a/net/dccp/proto.c b/net/dccp/proto.c
index 3489d3f21f50..60f40ec72ff3 100644
--- a/net/dccp/proto.c
+++ b/net/dccp/proto.c
@@ -71,7 +71,8 @@ void dccp_set_state(struct sock *sk, const int state)
                 break;
 
         case DCCP_CLOSED:
-                if (oldstate == DCCP_CLOSING || oldstate == DCCP_OPEN)
+                if (oldstate == DCCP_OPEN || oldstate == DCCP_ACTIVE_CLOSEREQ ||
+                    oldstate == DCCP_CLOSING)
                         DCCP_INC_STATS(DCCP_MIB_ESTABRESETS);
 
                 sk->sk_prot->unhash(sk);
@@ -92,6 +93,24 @@ void dccp_set_state(struct sock *sk, const int state)
 
 EXPORT_SYMBOL_GPL(dccp_set_state);
 
+static void dccp_finish_passive_close(struct sock *sk)
+{
+        switch (sk->sk_state) {
+        case DCCP_PASSIVE_CLOSE:
+                /* Node (client or server) has received Close packet. */
+                dccp_send_reset(sk, DCCP_RESET_CODE_CLOSED);
+                dccp_set_state(sk, DCCP_CLOSED);
+                break;
+        case DCCP_PASSIVE_CLOSEREQ:
+                /*
+                 * Client received CloseReq. We set the `active' flag so that
+                 * dccp_send_close() retransmits the Close as per RFC 4340, 8.3.
+                 */
+                dccp_send_close(sk, 1);
+                dccp_set_state(sk, DCCP_CLOSING);
+        }
+}
+
 void dccp_done(struct sock *sk)
 {
         dccp_set_state(sk, DCCP_CLOSED);
@@ -762,19 +781,26 @@ int dccp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 
                 dh = dccp_hdr(skb);
 
-                if (dh->dccph_type == DCCP_PKT_DATA ||
-                    dh->dccph_type == DCCP_PKT_DATAACK)
+                switch (dh->dccph_type) {
+                case DCCP_PKT_DATA:
+                case DCCP_PKT_DATAACK:
                         goto found_ok_skb;
 
-                if (dh->dccph_type == DCCP_PKT_RESET ||
-                    dh->dccph_type == DCCP_PKT_CLOSE) {
-                        dccp_pr_debug("found fin ok!\n");
+                case DCCP_PKT_CLOSE:
+                case DCCP_PKT_CLOSEREQ:
+                        if (!(flags & MSG_PEEK))
+                                dccp_finish_passive_close(sk);
+                        /* fall through */
+                case DCCP_PKT_RESET:
+                        dccp_pr_debug("found fin (%s) ok!\n",
+                                      dccp_packet_name(dh->dccph_type));
                         len = 0;
                         goto found_fin_ok;
+                default:
+                        dccp_pr_debug("packet_type=%s\n",
+                                      dccp_packet_name(dh->dccph_type));
+                        sk_eat_skb(sk, skb, 0);
                 }
-                dccp_pr_debug("packet_type=%s\n",
-                              dccp_packet_name(dh->dccph_type));
-                sk_eat_skb(sk, skb, 0);
 verify_sock_status:
                 if (sock_flag(sk, SOCK_DONE)) {
                         len = 0;
@@ -876,28 +902,30 @@ out:
 
 EXPORT_SYMBOL_GPL(inet_dccp_listen);
 
-static const unsigned char dccp_new_state[] = {
-        /* current state:   new state:      action:     */
-        [0]               = DCCP_CLOSED,
-        [DCCP_OPEN]       = DCCP_CLOSING | DCCP_ACTION_FIN,
-        [DCCP_REQUESTING] = DCCP_CLOSED,
-        [DCCP_PARTOPEN]   = DCCP_CLOSING | DCCP_ACTION_FIN,
-        [DCCP_LISTEN]     = DCCP_CLOSED,
-        [DCCP_RESPOND]    = DCCP_CLOSED,
-        [DCCP_CLOSING]    = DCCP_CLOSED,
-        [DCCP_TIME_WAIT]  = DCCP_CLOSED,
-        [DCCP_CLOSED]     = DCCP_CLOSED,
-};
-
-static int dccp_close_state(struct sock *sk)
+static void dccp_terminate_connection(struct sock *sk)
 {
-        const int next = dccp_new_state[sk->sk_state];
-        const int ns = next & DCCP_STATE_MASK;
+        u8 next_state = DCCP_CLOSED;
 
-        if (ns != sk->sk_state)
-                dccp_set_state(sk, ns);
+        switch (sk->sk_state) {
+        case DCCP_PASSIVE_CLOSE:
+        case DCCP_PASSIVE_CLOSEREQ:
+                dccp_finish_passive_close(sk);
+                break;
+        case DCCP_PARTOPEN:
+                dccp_pr_debug("Stop PARTOPEN timer (%p)\n", sk);
+                inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
+                /* fall through */
+        case DCCP_OPEN:
+                dccp_send_close(sk, 1);
 
-        return next & DCCP_ACTION_FIN;
+                if (dccp_sk(sk)->dccps_role == DCCP_ROLE_SERVER)
+                        next_state = DCCP_ACTIVE_CLOSEREQ;
+                else
+                        next_state = DCCP_CLOSING;
+                /* fall through */
+        default:
+                dccp_set_state(sk, next_state);
+        }
 }
 
 void dccp_close(struct sock *sk, long timeout)
@@ -940,8 +968,8 @@ void dccp_close(struct sock *sk, long timeout)
         } else if (sock_flag(sk, SOCK_LINGER) && !sk->sk_lingertime) {
                 /* Check zero linger _after_ checking for unread data. */
                 sk->sk_prot->disconnect(sk, 0);
-        } else if (dccp_close_state(sk)) {
-                dccp_send_close(sk, 1);
+        } else if (sk->sk_state != DCCP_CLOSED) {
+                dccp_terminate_connection(sk);
         }
 
         sk_stream_wait_close(sk, timeout);