/* RxRPC packet reception
 *
 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * 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/net.h>
#include <linux/skbuff.h>
#include <linux/errqueue.h>
#include <linux/udp.h>
#include <linux/in.h>
#include <linux/in6.h>
#include <linux/icmp.h>
#include <net/sock.h>
#include <net/af_rxrpc.h>
#include <net/ip.h>
#include <net/udp.h>
#include <net/net_namespace.h>
#include "ar-internal.h"

unsigned long rxrpc_ack_timeout = 1;

const char *rxrpc_pkts[] = {
        "?00",
        "DATA", "ACK", "BUSY", "ABORT", "ACKALL", "CHALL", "RESP", "DEBUG",
        "?09", "?10", "?11", "?12", "?13", "?14", "?15"
};

/*
 * queue a packet for recvmsg to pass to userspace
 * - the caller must hold a lock on call->lock
 * - must not be called with interrupts disabled (sk_filter() disables BH's)
 * - eats the packet whether successful or not
 * - there must be just one reference to the packet, which the caller passes to
 *   this function
 */
int rxrpc_queue_rcv_skb(struct rxrpc_call *call, struct sk_buff *skb,
                        bool force, bool terminal)
{
        struct rxrpc_skb_priv *sp;
        struct rxrpc_sock *rx = call->socket;
        struct sock *sk;
        int skb_len, ret;

        _enter(",,%d,%d", force, terminal);

        ASSERT(!irqs_disabled());

        sp = rxrpc_skb(skb);
        ASSERTCMP(sp->call, ==, call);

        /* if we've already posted the terminal message for a call, then we
         * don't post any more */
        if (test_bit(RXRPC_CALL_TERMINAL_MSG, &call->flags)) {
                _debug("already terminated");
                ASSERTCMP(call->state, >=, RXRPC_CALL_COMPLETE);
                skb->destructor = NULL;
                sp->call = NULL;
                rxrpc_put_call(call);
                rxrpc_free_skb(skb);
                return 0;
        }

        sk = &rx->sk;

        if (!force) {
                /* cast skb->rcvbuf to unsigned...  It's pointless, but
                 * reduces number of warnings when compiling with -W
                 * --ANK */
//              ret = -ENOBUFS;
//              if (atomic_read(&sk->sk_rmem_alloc) + skb->truesize >=
//                  (unsigned) sk->sk_rcvbuf)
//                      goto out;

                ret = sk_filter(sk, skb);
                if (ret < 0)
                        goto out;
        }

        spin_lock_bh(&sk->sk_receive_queue.lock);
        if (!test_bit(RXRPC_CALL_TERMINAL_MSG, &call->flags) &&
            !test_bit(RXRPC_CALL_RELEASED, &call->flags) &&
            call->socket->sk.sk_state != RXRPC_CLOSE) {
                skb->destructor = rxrpc_packet_destructor;
                skb->dev = NULL;
                skb->sk = sk;
                atomic_add(skb->truesize, &sk->sk_rmem_alloc);

                if (terminal) {
                        _debug("<<<< TERMINAL MESSAGE >>>>");
                        set_bit(RXRPC_CALL_TERMINAL_MSG, &call->flags);
                }

                /* allow interception by a kernel service */
                if (rx->interceptor) {
                        rx->interceptor(sk, call->user_call_ID, skb);
                        spin_unlock_bh(&sk->sk_receive_queue.lock);
                } else {

                        /* Cache the SKB length before we tack it onto the
                         * receive queue.  Once it is added it no longer
                         * belongs to us and may be freed by other threads of
                         * control pulling packets from the queue */
                        skb_len = skb->len;

                        _net("post skb %p", skb);
                        __skb_queue_tail(&sk->sk_receive_queue, skb);
                        spin_unlock_bh(&sk->sk_receive_queue.lock);

                        if (!sock_flag(sk, SOCK_DEAD))
                                sk->sk_data_ready(sk, skb_len);
                }
                skb = NULL;
        } else {
                spin_unlock_bh(&sk->sk_receive_queue.lock);
        }
        ret = 0;

out:
        /* release the socket buffer */
        if (skb) {
                skb->destructor = NULL;
                sp->call = NULL;
                rxrpc_put_call(call);
                rxrpc_free_skb(skb);
        }

        _leave(" = %d", ret);
        return ret;
}

/*
 * process a DATA packet, posting the packet to the appropriate queue
 * - eats the packet if successful
 */
static int rxrpc_fast_process_data(struct rxrpc_call *call,
                                   struct sk_buff *skb, u32 seq)
{
        struct rxrpc_skb_priv *sp;
        bool terminal;
        int ret, ackbit, ack;

        _enter("{%u,%u},,{%u}", call->rx_data_post, call->rx_first_oos, seq);

        sp = rxrpc_skb(skb);
        ASSERTCMP(sp->call, ==, NULL);

        spin_lock(&call->lock);

        if (call->state > RXRPC_CALL_COMPLETE)
                goto discard;

        ASSERTCMP(call->rx_data_expect, >=, call->rx_data_post);
        ASSERTCMP(call->rx_data_post, >=, call->rx_data_recv);
        ASSERTCMP(call->rx_data_recv, >=, call->rx_data_eaten);

        if (seq < call->rx_data_post) {
                _debug("dup #%u [-%u]", seq, call->rx_data_post);
                ack = RXRPC_ACK_DUPLICATE;
                ret = -ENOBUFS;
                goto discard_and_ack;
        }

        /* we may already have the packet in the out of sequence queue */
        ackbit = seq - (call->rx_data_eaten + 1);
        ASSERTCMP(ackbit, >=, 0);
        if (__test_and_set_bit(ackbit, call->ackr_window)) {
                _debug("dup oos #%u [%u,%u]",
                       seq, call->rx_data_eaten, call->rx_data_post);
                ack = RXRPC_ACK_DUPLICATE;
                goto discard_and_ack;
        }

        if (seq >= call->ackr_win_top) {
                _debug("exceed #%u [%u]", seq, call->ackr_win_top);
                __clear_bit(ackbit, call->ackr_window);
                ack = RXRPC_ACK_EXCEEDS_WINDOW;
                goto discard_and_ack;
        }

        if (seq == call->rx_data_expect) {
                clear_bit(RXRPC_CALL_EXPECT_OOS, &call->flags);
                call->rx_data_expect++;
        } else if (seq > call->rx_data_expect) {
                _debug("oos #%u [%u]", seq, call->rx_data_expect);
                call->rx_data_expect = seq + 1;
                if (test_and_set_bit(RXRPC_CALL_EXPECT_OOS, &call->flags)) {
                        ack = RXRPC_ACK_OUT_OF_SEQUENCE;
                        goto enqueue_and_ack;
                }
                goto enqueue_packet;
        }

        if (seq != call->rx_data_post) {
                _debug("ahead #%u [%u]", seq, call->rx_data_post);
                goto enqueue_packet;
        }

        if (test_bit(RXRPC_CALL_RCVD_LAST, &call->flags))
                goto protocol_error;

        /* if the packet need security things doing to it, then it goes down
         * the slow path */
        if (call->conn->security)
                goto enqueue_packet;

        sp->call = call;
        rxrpc_get_call(call);
        terminal = ((sp->hdr.flags & RXRPC_LAST_PACKET) &&
                    !(sp->hdr.flags & RXRPC_CLIENT_INITIATED));
        ret = rxrpc_queue_rcv_skb(call, skb, false, terminal);
        if (ret < 0) {
                if (ret == -ENOMEM || ret == -ENOBUFS) {
                        __clear_bit(ackbit, call->ackr_window);
                        ack = RXRPC_ACK_NOSPACE;
                        goto discard_and_ack;
                }
                goto out;
        }

        skb = NULL;

        _debug("post #%u", seq);
        ASSERTCMP(call->rx_data_post, ==, seq);
        call->rx_data_post++;

        if (sp->hdr.flags & RXRPC_LAST_PACKET)
                set_bit(RXRPC_CALL_RCVD_LAST, &call->flags);

        /* if we've reached an out of sequence packet then we need to drain
         * that queue into the socket Rx queue now */
        if (call->rx_data_post == call->rx_first_oos) {
                _debug("drain rx oos now");
                read_lock(&call->state_lock);
                if (call->state < RXRPC_CALL_COMPLETE &&
                    !test_and_set_bit(RXRPC_CALL_DRAIN_RX_OOS, &call->events))
                        rxrpc_queue_call(call);
                read_unlock(&call->state_lock);
        }

        spin_unlock(&call->lock);
        atomic_inc(&call->ackr_not_idle);
        rxrpc_propose_ACK(call, RXRPC_ACK_DELAY, sp->hdr.serial, false);
        _leave(" = 0 [posted]");
        return 0;

protocol_error:
        ret = -EBADMSG;
out:
        spin_unlock(&call->lock);
        _leave(" = %d", ret);
        return ret;

discard_and_ack:
        _debug("discard and ACK packet %p", skb);
        __rxrpc_propose_ACK(call, ack, sp->hdr.serial, true);
discard:
        spin_unlock(&call->lock);
        rxrpc_free_skb(skb);
        _leave(" = 0 [discarded]");
        return 0;

enqueue_and_ack:
        __rxrpc_propose_ACK(call, ack, sp->hdr.serial, true);
enqueue_packet:
        _net("defer skb %p", skb);
        spin_unlock(&call->lock);
        skb_queue_tail(&call->rx_queue, skb);
        atomic_inc(&call->ackr_not_idle);
        read_lock(&call->state_lock);
        if (call->state < RXRPC_CALL_DEAD)
                rxrpc_queue_call(call);
        read_unlock(&call->state_lock);
        _leave(" = 0 [queued]");
        return 0;
}

/*
 * assume an implicit ACKALL of the transmission phase of a client socket upon
 * reception of the first reply packet
 */
static void rxrpc_assume_implicit_ackall(struct rxrpc_call *call, u32 serial)
{
        write_lock_bh(&call->state_lock);

        switch (call->state) {
        case RXRPC_CALL_CLIENT_AWAIT_REPLY:
                call->state = RXRPC_CALL_CLIENT_RECV_REPLY;
                call->acks_latest = serial;

                _debug("implicit ACKALL %%%u", call->acks_latest);
                set_bit(RXRPC_CALL_RCVD_ACKALL, &call->events);
                write_unlock_bh(&call->state_lock);

                if (try_to_del_timer_sync(&call->resend_timer) >= 0) {
                        clear_bit(RXRPC_CALL_RESEND_TIMER, &call->events);
                        clear_bit(RXRPC_CALL_RESEND, &call->events);
                        clear_bit(RXRPC_CALL_RUN_RTIMER, &call->flags);
                }
                break;

        default:
                write_unlock_bh(&call->state_lock);
                break;
        }
}

/*
 * post an incoming packet to the nominated call to deal with
 * - must get rid of the sk_buff, either by freeing it or by queuing it
 */
void rxrpc_fast_process_packet(struct rxrpc_call *call, struct sk_buff *skb)
{
        struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
        __be32 _abort_code;
        u32 serial, hi_serial, seq, abort_code;

        _enter("%p,%p", call, skb);

        ASSERT(!irqs_disabled());

#if 0 // INJECT RX ERROR
        if (sp->hdr.type == RXRPC_PACKET_TYPE_DATA) {
                static int skip = 0;
                if (++skip == 3) {
                        printk("DROPPED 3RD PACKET!!!!!!!!!!!!!\n");
                        skip = 0;
                        goto free_packet;
                }
        }
#endif

        /* track the latest serial number on this connection for ACK packet
         * information */
        serial = ntohl(sp->hdr.serial);
        hi_serial = atomic_read(&call->conn->hi_serial);
        while (serial > hi_serial)
                hi_serial = atomic_cmpxchg(&call->conn->hi_serial, hi_serial,
                                           serial);

        /* request ACK generation for any ACK or DATA packet that requests
         * it */
        if (sp->hdr.flags & RXRPC_REQUEST_ACK) {
                _proto("ACK Requested on %%%u", serial);
                rxrpc_propose_ACK(call, RXRPC_ACK_REQUESTED, sp->hdr.serial,
                                  !(sp->hdr.flags & RXRPC_MORE_PACKETS));
        }

        switch (sp->hdr.type) {
        case RXRPC_PACKET_TYPE_ABORT:
                _debug("abort");

                if (skb_copy_bits(skb, 0, &_abort_code,
                                  sizeof(_abort_code)) < 0)
                        goto protocol_error;

                abort_code = ntohl(_abort_code);
                _proto("Rx ABORT %%%u { %x }", serial, abort_code);

                write_lock_bh(&call->state_lock);
                if (call->state < RXRPC_CALL_COMPLETE) {
                        call->state = RXRPC_CALL_REMOTELY_ABORTED;
                        call->abort_code = abort_code;
                        set_bit(RXRPC_CALL_RCVD_ABORT, &call->events);
                        rxrpc_queue_call(call);
                }
                goto free_packet_unlock;

        case RXRPC_PACKET_TYPE_BUSY:
                _proto("Rx BUSY %%%u", serial);

                if (call->conn->out_clientflag)
                        goto protocol_error;

                write_lock_bh(&call->state_lock);
                switch (call->state) {
                case RXRPC_CALL_CLIENT_SEND_REQUEST:
                        call->state = RXRPC_CALL_SERVER_BUSY;
                        set_bit(RXRPC_CALL_RCVD_BUSY, &call->events);
                        rxrpc_queue_call(call);
                case RXRPC_CALL_SERVER_BUSY:
                        goto free_packet_unlock;
                default:
                        goto protocol_error_locked;
                }

        default:
                _proto("Rx %s %%%u", rxrpc_pkts[sp->hdr.type], serial);
                goto protocol_error;

        case RXRPC_PACKET_TYPE_DATA:
                seq = ntohl(sp->hdr.seq);

                _proto("Rx DATA %%%u { #%u }", serial, seq);

                if (seq == 0)
                        goto protocol_error;

                call->ackr_prev_seq = sp->hdr.seq;

                /* received data implicitly ACKs all of the request packets we
                 * sent when we're acting as a client */
                if (call->state == RXRPC_CALL_CLIENT_AWAIT_REPLY)
                        rxrpc_assume_implicit_ackall(call, serial);

                switch (rxrpc_fast_process_data(call, skb, seq)) {
                case 0:
                        skb = NULL;
                        goto done;

                default:
                        BUG();

                        /* data packet received beyond the last packet */
                case -EBADMSG:
                        goto protocol_error;
                }

        case RXRPC_PACKET_TYPE_ACK:
                /* ACK processing is done in process context */
                read_lock_bh(&call->state_lock);
                if (call->state < RXRPC_CALL_DEAD) {
                        skb_queue_tail(&call->rx_queue, skb);
                        rxrpc_queue_call(call);
                        skb = NULL;
                }
                read_unlock_bh(&call->state_lock);
                goto free_packet;
        }

protocol_error:
        _debug("protocol error");
        write_lock_bh(&call->state_lock);
protocol_error_locked:
        if (call->state <= RXRPC_CALL_COMPLETE) {
                call->state = RXRPC_CALL_LOCALLY_ABORTED;
                call->abort_code = RX_PROTOCOL_ERROR;
                set_bit(RXRPC_CALL_ABORT, &call->events);
                rxrpc_queue_call(call);
        }
free_packet_unlock:
        write_unlock_bh(&call->state_lock);
free_packet:
        rxrpc_free_skb(skb);
done:
        _leave("");
}

/*
 * split up a jumbo data packet
 */
static void rxrpc_process_jumbo_packet(struct rxrpc_call *call,
                                       struct sk_buff *jumbo)
{
        struct rxrpc_jumbo_header jhdr;
        struct rxrpc_skb_priv *sp;
        struct sk_buff *part;

        _enter(",{%u,%u}", jumbo->data_len, jumbo->len);

        sp = rxrpc_skb(jumbo);

        do {
                sp->hdr.flags &= ~RXRPC_JUMBO_PACKET;

                /* make a clone to represent the first subpacket in what's left
                 * of the jumbo packet */
                part = skb_clone(jumbo, GFP_ATOMIC);
                if (!part) {
                        /* simply ditch the tail in the event of ENOMEM */
                        pskb_trim(jumbo, RXRPC_JUMBO_DATALEN);
                        break;
                }
                rxrpc_new_skb(part);

                pskb_trim(part, RXRPC_JUMBO_DATALEN);

                if (!pskb_pull(jumbo, RXRPC_JUMBO_DATALEN))
                        goto protocol_error;

                if (skb_copy_bits(jumbo, 0, &jhdr, sizeof(jhdr)) < 0)
                        goto protocol_error;
                if (!pskb_pull(jumbo, sizeof(jhdr)))
                        BUG();

                sp->hdr.seq     = htonl(ntohl(sp->hdr.seq) + 1);
                sp->hdr.serial  = htonl(ntohl(sp->hdr.serial) + 1);
                sp->hdr.flags   = jhdr.flags;
                sp->hdr._rsvd   = jhdr._rsvd;

                _proto("Rx DATA Jumbo %%%u", ntohl(sp->hdr.serial) - 1);

                rxrpc_fast_process_packet(call, part);
                part = NULL;

        } while (sp->hdr.flags & RXRPC_JUMBO_PACKET);

        rxrpc_fast_process_packet(call, jumbo);
        _leave("");
        return;

protocol_error:
        _debug("protocol error");
        rxrpc_free_skb(part);
        rxrpc_free_skb(jumbo);
        write_lock_bh(&call->state_lock);
        if (call->state <= RXRPC_CALL_COMPLETE) {
                call->state = RXRPC_CALL_LOCALLY_ABORTED;
                call->abort_code = RX_PROTOCOL_ERROR;
                set_bit(RXRPC_CALL_ABORT, &call->events);
                rxrpc_queue_call(call);
        }
        write_unlock_bh(&call->state_lock);
        _leave("");
}

/*
 * post an incoming packet to the appropriate call/socket to deal with
 * - must get rid of the sk_buff, either by freeing it or by queuing it
 */
static void rxrpc_post_packet_to_call(struct rxrpc_connection *conn,
                                      struct sk_buff *skb)
{
        struct rxrpc_skb_priv *sp;
        struct rxrpc_call *call;
        struct rb_node *p;
        __be32 call_id;

        _enter("%p,%p", conn, skb);

        read_lock_bh(&conn->lock);

        sp = rxrpc_skb(skb);

        /* look at extant calls by channel number first */
        call = conn->channels[ntohl(sp->hdr.cid) & RXRPC_CHANNELMASK];
        if (!call || call->call_id != sp->hdr.callNumber)
                goto call_not_extant;

        _debug("extant call [%d]", call->state);
        ASSERTCMP(call->conn, ==, conn);

        read_lock(&call->state_lock);
        switch (call->state) {
        case RXRPC_CALL_LOCALLY_ABORTED:
                if (!test_and_set_bit(RXRPC_CALL_ABORT, &call->events))
                        rxrpc_queue_call(call);
        case RXRPC_CALL_REMOTELY_ABORTED:
        case RXRPC_CALL_NETWORK_ERROR:
        case RXRPC_CALL_DEAD:
                goto free_unlock;
        default:
                break;
        }

        read_unlock(&call->state_lock);
        rxrpc_get_call(call);
        read_unlock_bh(&conn->lock);

        if (sp->hdr.type == RXRPC_PACKET_TYPE_DATA &&
            sp->hdr.flags & RXRPC_JUMBO_PACKET)
                rxrpc_process_jumbo_packet(call, skb);
        else
                rxrpc_fast_process_packet(call, skb);

        rxrpc_put_call(call);
        goto done;

call_not_extant:
        /* search the completed calls in case what we're dealing with is
         * there */
        _debug("call not extant");

        call_id = sp->hdr.callNumber;
        p = conn->calls.rb_node;
        while (p) {
                call = rb_entry(p, struct rxrpc_call, conn_node);

                if (call_id < call->call_id)
                        p = p->rb_left;
                else if (call_id > call->call_id)
                        p = p->rb_right;
                else
                        goto found_completed_call;
        }

dead_call:
        /* it's a either a really old call that we no longer remember or its a
         * new incoming call */
        read_unlock_bh(&conn->lock);

        if (sp->hdr.flags & RXRPC_CLIENT_INITIATED &&
            sp->hdr.seq == cpu_to_be32(1)) {
                _debug("incoming call");
                skb_queue_tail(&conn->trans->local->accept_queue, skb);
                rxrpc_queue_work(&conn->trans->local->acceptor);
                goto done;
        }

        _debug("dead call");
        skb->priority = RX_CALL_DEAD;
        rxrpc_reject_packet(conn->trans->local, skb);
        goto done;

        /* resend last packet of a completed call
         * - client calls may have been aborted or ACK'd
         * - server calls may have been aborted
         */
found_completed_call:
        _debug("completed call");

        if (atomic_read(&call->usage) == 0)
                goto dead_call;

        /* synchronise any state changes */
        read_lock(&call->state_lock);
        ASSERTIFCMP(call->state != RXRPC_CALL_CLIENT_FINAL_ACK,
                    call->state, >=, RXRPC_CALL_COMPLETE);

        if (call->state == RXRPC_CALL_LOCALLY_ABORTED ||
            call->state == RXRPC_CALL_REMOTELY_ABORTED ||
            call->state == RXRPC_CALL_DEAD) {
                read_unlock(&call->state_lock);
                goto dead_call;
        }

        if (call->conn->in_clientflag) {
                read_unlock(&call->state_lock);
                goto dead_call; /* complete server call */
        }

        _debug("final ack again");
        rxrpc_get_call(call);
        set_bit(RXRPC_CALL_ACK_FINAL, &call->events);
        rxrpc_queue_call(call);

free_unlock:
        read_unlock(&call->state_lock);
        read_unlock_bh(&conn->lock);
        rxrpc_free_skb(skb);
done:
        _leave("");
}

/*
 * post connection-level events to the connection
 * - this includes challenges, responses and some aborts
 */
static void rxrpc_post_packet_to_conn(struct rxrpc_connection *conn,
                                      struct sk_buff *skb)
{
        _enter("%p,%p", conn, skb);

        atomic_inc(&conn->usage);
        skb_queue_tail(&conn->rx_queue, skb);
        rxrpc_queue_conn(conn);
}

/*
 * handle data received on the local endpoint
 * - may be called in interrupt context
 */
void rxrpc_data_ready(struct sock *sk, int count)
{
        struct rxrpc_connection *conn;
        struct rxrpc_transport *trans;
        struct rxrpc_skb_priv *sp;
        struct rxrpc_local *local;
        struct rxrpc_peer *peer;
        struct sk_buff *skb;
        int ret;

        _enter("%p, %d", sk, count);

        ASSERT(!irqs_disabled());

        read_lock_bh(&rxrpc_local_lock);
        local = sk->sk_user_data;
        if (local && atomic_read(&local->usage) > 0)
                rxrpc_get_local(local);
        else
                local = NULL;
        read_unlock_bh(&rxrpc_local_lock);
        if (!local) {
                _leave(" [local dead]");
                return;
        }

        skb = skb_recv_datagram(sk, 0, 1, &ret);
        if (!skb) {
                rxrpc_put_local(local);
                if (ret == -EAGAIN)
                        return;
                _debug("UDP socket error %d", ret);
                return;
        }

        rxrpc_new_skb(skb);

        _net("recv skb %p", skb);

        /* we'll probably need to checksum it (didn't call sock_recvmsg) */
        if (skb_checksum_complete(skb)) {
                rxrpc_free_skb(skb);
                rxrpc_put_local(local);
                UDP_INC_STATS_BH(&init_net, UDP_MIB_INERRORS, 0);
                _leave(" [CSUM failed]");
                return;
        }

        UDP_INC_STATS_BH(&init_net, UDP_MIB_INDATAGRAMS, 0);

        /* the socket buffer we have is owned by UDP, with UDP's data all over
         * it, but we really want our own */
        skb_orphan(skb);
        sp = rxrpc_skb(skb);
        memset(sp, 0, sizeof(*sp));

        _net("Rx UDP packet from %08x:%04hu",
             ntohl(ip_hdr(skb)->saddr), ntohs(udp_hdr(skb)->source));

        /* dig out the RxRPC connection details */
        if (skb_copy_bits(skb, sizeof(struct udphdr), &sp->hdr,
                          sizeof(sp->hdr)) < 0)
                goto bad_message;
        if (!pskb_pull(skb, sizeof(struct udphdr) + sizeof(sp->hdr)))
                BUG();

        _net("Rx RxRPC %s ep=%x call=%x:%x",
             sp->hdr.flags & RXRPC_CLIENT_INITIATED ? "ToServer" : "ToClient",
             ntohl(sp->hdr.epoch),
             ntohl(sp->hdr.cid),
             ntohl(sp->hdr.callNumber));

        if (sp->hdr.type == 0 || sp->hdr.type >= RXRPC_N_PACKET_TYPES) {
                _proto("Rx Bad Packet Type %u", sp->hdr.type);
                goto bad_message;
        }

        if (sp->hdr.type == RXRPC_PACKET_TYPE_DATA &&
            (sp->hdr.callNumber == 0 || sp->hdr.seq == 0))
                goto bad_message;

        peer = rxrpc_find_peer(local, ip_hdr(skb)->saddr, udp_hdr(skb)->source);
        if (IS_ERR(peer))
                goto cant_route_call;

        trans = rxrpc_find_transport(local, peer);
        rxrpc_put_peer(peer);
        if (!trans)
                goto cant_route_call;

        conn = rxrpc_find_connection(trans, &sp->hdr);
        rxrpc_put_transport(trans);
        if (!conn)
                goto cant_route_call;

        _debug("CONN %p {%d}", conn, conn->debug_id);

        if (sp->hdr.callNumber == 0)
                rxrpc_post_packet_to_conn(conn, skb);
        else
                rxrpc_post_packet_to_call(conn, skb);
        rxrpc_put_connection(conn);
        rxrpc_put_local(local);
        return;

cant_route_call:
        _debug("can't route call");
        if (sp->hdr.flags & RXRPC_CLIENT_INITIATED &&
            sp->hdr.type == RXRPC_PACKET_TYPE_DATA) {
                if (sp->hdr.seq == cpu_to_be32(1)) {
                        _debug("first packet");
                        skb_queue_tail(&local->accept_queue, skb);
                        rxrpc_queue_work(&local->acceptor);
                        rxrpc_put_local(local);
                        _leave(" [incoming]");
                        return;
                }
                skb->priority = RX_INVALID_OPERATION;
        } else {
                skb->priority = RX_CALL_DEAD;
        }

        _debug("reject");
        rxrpc_reject_packet(local, skb);
        rxrpc_put_local(local);
        _leave(" [no call]");
        return;

bad_message:
        skb->priority = RX_PROTOCOL_ERROR;
        rxrpc_reject_packet(local, skb);
        rxrpc_put_local(local);
        _leave(" [badmsg]");
}