/* AF_RXRPC sendmsg() implementation.
 *
 * Copyright (C) 2007, 2016 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 Licence
 * as published by the Free Software Foundation; either version
 * 2 of the Licence, or (at your option) any later version.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/net.h>
#include <linux/gfp.h>
#include <linux/skbuff.h>
#include <linux/export.h>
#include <net/sock.h>
#include <net/af_rxrpc.h>
#include "ar-internal.h"

enum rxrpc_command {
        RXRPC_CMD_SEND_DATA,            /* send data message */
        RXRPC_CMD_SEND_ABORT,           /* request abort generation */
        RXRPC_CMD_ACCEPT,               /* [server] accept incoming call */
        RXRPC_CMD_REJECT_BUSY,          /* [server] reject a call as busy */
};

/*
 * wait for space to appear in the transmit/ACK window
 * - caller holds the socket locked
 */
static int rxrpc_wait_for_tx_window(struct rxrpc_sock *rx,
                                    struct rxrpc_call *call,
                                    long *timeo)
{
        DECLARE_WAITQUEUE(myself, current);
        int ret;

        _enter(",{%u,%u,%u}",
               call->tx_hard_ack, call->tx_top, call->tx_winsize);

        add_wait_queue(&call->waitq, &myself);

        for (;;) {
                set_current_state(TASK_INTERRUPTIBLE);
                ret = 0;
                if (call->tx_top - call->tx_hard_ack <
                    min_t(unsigned int, call->tx_winsize,
                          call->cong_cwnd + call->cong_extra))
                        break;
                if (call->state >= RXRPC_CALL_COMPLETE) {
                        ret = -call->error;
                        break;
                }
                if (signal_pending(current)) {
                        ret = sock_intr_errno(*timeo);
                        break;
                }

                trace_rxrpc_transmit(call, rxrpc_transmit_wait);
                release_sock(&rx->sk);
                *timeo = schedule_timeout(*timeo);
                lock_sock(&rx->sk);
        }

        remove_wait_queue(&call->waitq, &myself);
        set_current_state(TASK_RUNNING);
        _leave(" = %d", ret);
        return ret;
}

/*
 * Schedule an instant Tx resend.
 */
static inline void rxrpc_instant_resend(struct rxrpc_call *call, int ix)
{
        spin_lock_bh(&call->lock);

        if (call->state < RXRPC_CALL_COMPLETE) {
                call->rxtx_annotations[ix] = RXRPC_TX_ANNO_RETRANS;
                if (!test_and_set_bit(RXRPC_CALL_EV_RESEND, &call->events))
                        rxrpc_queue_call(call);
        }

        spin_unlock_bh(&call->lock);
}

/*
 * Queue a DATA packet for transmission, set the resend timeout and send the
 * packet immediately
 */
static void rxrpc_queue_packet(struct rxrpc_call *call, struct sk_buff *skb,
                               bool last)
{
        struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
        rxrpc_seq_t seq = sp->hdr.seq;
        int ret, ix;
        u8 annotation = RXRPC_TX_ANNO_UNACK;

        _net("queue skb %p [%d]", skb, seq);

        ASSERTCMP(seq, ==, call->tx_top + 1);

        if (last)
                annotation |= RXRPC_TX_ANNO_LAST;

        /* We have to set the timestamp before queueing as the retransmit
         * algorithm can see the packet as soon as we queue it.
         */
        skb->tstamp = ktime_get_real();

        ix = seq & RXRPC_RXTX_BUFF_MASK;
        rxrpc_get_skb(skb, rxrpc_skb_tx_got);
        call->rxtx_annotations[ix] = annotation;
        smp_wmb();
        call->rxtx_buffer[ix] = skb;
        call->tx_top = seq;
        if (last)
                trace_rxrpc_transmit(call, rxrpc_transmit_queue_last);
        else
                trace_rxrpc_transmit(call, rxrpc_transmit_queue);

        if (last || call->state == RXRPC_CALL_SERVER_ACK_REQUEST) {
                _debug("________awaiting reply/ACK__________");
                write_lock_bh(&call->state_lock);
                switch (call->state) {
                case RXRPC_CALL_CLIENT_SEND_REQUEST:
                        call->state = RXRPC_CALL_CLIENT_AWAIT_REPLY;
                        break;
                case RXRPC_CALL_SERVER_ACK_REQUEST:
                        call->state = RXRPC_CALL_SERVER_SEND_REPLY;
                        call->ack_at = call->expire_at;
                        if (call->ackr_reason == RXRPC_ACK_DELAY)
                                call->ackr_reason = 0;
                        __rxrpc_set_timer(call, rxrpc_timer_init_for_send_reply,
                                          ktime_get_real());
                        if (!last)
                                break;
                case RXRPC_CALL_SERVER_SEND_REPLY:
                        call->state = RXRPC_CALL_SERVER_AWAIT_ACK;
                        break;
                default:
                        break;
                }
                write_unlock_bh(&call->state_lock);
        }

        if (seq == 1 && rxrpc_is_client_call(call))
                rxrpc_expose_client_call(call);

        ret = rxrpc_send_data_packet(call, skb, false);
        if (ret < 0) {
                _debug("need instant resend %d", ret);
                rxrpc_instant_resend(call, ix);
        } else {
                ktime_t now = ktime_get_real(), resend_at;

                resend_at = ktime_add_ms(now, rxrpc_resend_timeout);

                if (ktime_before(resend_at, call->resend_at)) {
                        call->resend_at = resend_at;
                        rxrpc_set_timer(call, rxrpc_timer_set_for_send, now);
                }
        }

        rxrpc_free_skb(skb, rxrpc_skb_tx_freed);
        _leave("");
}

/*
 * send data through a socket
 * - must be called in process context
 * - caller holds the socket locked
 */
static int rxrpc_send_data(struct rxrpc_sock *rx,
                           struct rxrpc_call *call,
                           struct msghdr *msg, size_t len)
{
        struct rxrpc_skb_priv *sp;
        struct sk_buff *skb;
        struct sock *sk = &rx->sk;
        long timeo;
        bool more;
        int ret, copied;

        timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);

        /* this should be in poll */
        sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);

        if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
                return -EPIPE;

        more = msg->msg_flags & MSG_MORE;

        skb = call->tx_pending;
        call->tx_pending = NULL;
        rxrpc_see_skb(skb, rxrpc_skb_tx_seen);

        copied = 0;
        do {
                /* Check to see if there's a ping ACK to reply to. */
                if (call->ackr_reason == RXRPC_ACK_PING_RESPONSE)
                        rxrpc_send_ack_packet(call, false);

                if (!skb) {
                        size_t size, chunk, max, space;

                        _debug("alloc");

                        if (call->tx_top - call->tx_hard_ack >=
                            min_t(unsigned int, call->tx_winsize,
                                  call->cong_cwnd + call->cong_extra)) {
                                ret = -EAGAIN;
                                if (msg->msg_flags & MSG_DONTWAIT)
                                        goto maybe_error;
                                ret = rxrpc_wait_for_tx_window(rx, call,
                                                               &timeo);
                                if (ret < 0)
                                        goto maybe_error;
                        }

                        max = RXRPC_JUMBO_DATALEN;
                        max -= call->conn->security_size;
                        max &= ~(call->conn->size_align - 1UL);

                        chunk = max;
                        if (chunk > msg_data_left(msg) && !more)
                                chunk = msg_data_left(msg);

                        space = chunk + call->conn->size_align;
                        space &= ~(call->conn->size_align - 1UL);

                        size = space + call->conn->security_size;

                        _debug("SIZE: %zu/%zu/%zu", chunk, space, size);

                        /* create a buffer that we can retain until it's ACK'd */
                        skb = sock_alloc_send_skb(
                                sk, size, msg->msg_flags & MSG_DONTWAIT, &ret);
                        if (!skb)
                                goto maybe_error;

                        rxrpc_new_skb(skb, rxrpc_skb_tx_new);

                        _debug("ALLOC SEND %p", skb);

                        ASSERTCMP(skb->mark, ==, 0);

                        _debug("HS: %u", call->conn->security_size);
                        skb_reserve(skb, call->conn->security_size);
                        skb->len += call->conn->security_size;

                        sp = rxrpc_skb(skb);
                        sp->remain = chunk;
                        if (sp->remain > skb_tailroom(skb))
                                sp->remain = skb_tailroom(skb);

                        _net("skb: hr %d, tr %d, hl %d, rm %d",
                               skb_headroom(skb),
                               skb_tailroom(skb),
                               skb_headlen(skb),
                               sp->remain);

                        skb->ip_summed = CHECKSUM_UNNECESSARY;
                }

                _debug("append");
                sp = rxrpc_skb(skb);

                /* append next segment of data to the current buffer */
                if (msg_data_left(msg) > 0) {
                        int copy = skb_tailroom(skb);
                        ASSERTCMP(copy, >, 0);
                        if (copy > msg_data_left(msg))
                                copy = msg_data_left(msg);
                        if (copy > sp->remain)
                                copy = sp->remain;

                        _debug("add");
                        ret = skb_add_data(skb, &msg->msg_iter, copy);
                        _debug("added");
                        if (ret < 0)
                                goto efault;
                        sp->remain -= copy;
                        skb->mark += copy;
                        copied += copy;
                }

                /* check for the far side aborting the call or a network error
                 * occurring */
                if (call->state == RXRPC_CALL_COMPLETE)
                        goto call_terminated;

                /* add the packet to the send queue if it's now full */
                if (sp->remain <= 0 ||
                    (msg_data_left(msg) == 0 && !more)) {
                        struct rxrpc_connection *conn = call->conn;
                        uint32_t seq;
                        size_t pad;

                        /* pad out if we're using security */
                        if (conn->security_ix) {
                                pad = conn->security_size + skb->mark;
                                pad = conn->size_align - pad;
                                pad &= conn->size_align - 1;
                                _debug("pad %zu", pad);
                                if (pad)
                                        memset(skb_put(skb, pad), 0, pad);
                        }

                        seq = call->tx_top + 1;

                        sp->hdr.seq     = seq;
                        sp->hdr._rsvd   = 0;
                        sp->hdr.flags   = conn->out_clientflag;

                        if (msg_data_left(msg) == 0 && !more)
                                sp->hdr.flags |= RXRPC_LAST_PACKET;
                        else if (call->tx_top - call->tx_hard_ack <
                                 call->tx_winsize)
                                sp->hdr.flags |= RXRPC_MORE_PACKETS;

                        ret = conn->security->secure_packet(
                                call, skb, skb->mark, skb->head);
                        if (ret < 0)
                                goto out;

                        rxrpc_queue_packet(call, skb, !msg_data_left(msg) && !more);
                        skb = NULL;
                }
        } while (msg_data_left(msg) > 0);

success:
        ret = copied;
out:
        call->tx_pending = skb;
        _leave(" = %d", ret);
        return ret;

call_terminated:
        rxrpc_free_skb(skb, rxrpc_skb_tx_freed);
        _leave(" = %d", -call->error);
        return -call->error;

maybe_error:
        if (copied)
                goto success;
        goto out;

efault:
        ret = -EFAULT;
        goto out;
}

/*
 * extract control messages from the sendmsg() control buffer
 */
static int rxrpc_sendmsg_cmsg(struct msghdr *msg,
                              unsigned long *user_call_ID,
                              enum rxrpc_command *command,
                              u32 *abort_code,
                              bool *_exclusive)
{
        struct cmsghdr *cmsg;
        bool got_user_ID = false;
        int len;

        *command = RXRPC_CMD_SEND_DATA;

        if (msg->msg_controllen == 0)
                return -EINVAL;

        for_each_cmsghdr(cmsg, msg) {
                if (!CMSG_OK(msg, cmsg))
                        return -EINVAL;

                len = cmsg->cmsg_len - CMSG_ALIGN(sizeof(struct cmsghdr));
                _debug("CMSG %d, %d, %d",
                       cmsg->cmsg_level, cmsg->cmsg_type, len);

                if (cmsg->cmsg_level != SOL_RXRPC)
                        continue;

                switch (cmsg->cmsg_type) {
                case RXRPC_USER_CALL_ID:
                        if (msg->msg_flags & MSG_CMSG_COMPAT) {
                                if (len != sizeof(u32))
                                        return -EINVAL;
                                *user_call_ID = *(u32 *) CMSG_DATA(cmsg);
                        } else {
                                if (len != sizeof(unsigned long))
                                        return -EINVAL;
                                *user_call_ID = *(unsigned long *)
                                        CMSG_DATA(cmsg);
                        }
                        _debug("User Call ID %lx", *user_call_ID);
                        got_user_ID = true;
                        break;

                case RXRPC_ABORT:
                        if (*command != RXRPC_CMD_SEND_DATA)
                                return -EINVAL;
                        *command = RXRPC_CMD_SEND_ABORT;
                        if (len != sizeof(*abort_code))
                                return -EINVAL;
                        *abort_code = *(unsigned int *) CMSG_DATA(cmsg);
                        _debug("Abort %x", *abort_code);
                        if (*abort_code == 0)
                                return -EINVAL;
                        break;

                case RXRPC_ACCEPT:
                        if (*command != RXRPC_CMD_SEND_DATA)
                                return -EINVAL;
                        *command = RXRPC_CMD_ACCEPT;
                        if (len != 0)
                                return -EINVAL;
                        break;

                case RXRPC_EXCLUSIVE_CALL:
                        *_exclusive = true;
                        if (len != 0)
                                return -EINVAL;
                        break;
                default:
                        return -EINVAL;
                }
        }

        if (!got_user_ID)
                return -EINVAL;
        _leave(" = 0");
        return 0;
}

/*
 * Create a new client call for sendmsg().
 */
static struct rxrpc_call *
rxrpc_new_client_call_for_sendmsg(struct rxrpc_sock *rx, struct msghdr *msg,
                                  unsigned long user_call_ID, bool exclusive)
{
        struct rxrpc_conn_parameters cp;
        struct rxrpc_call *call;
        struct key *key;

        DECLARE_SOCKADDR(struct sockaddr_rxrpc *, srx, msg->msg_name);

        _enter("");

        if (!msg->msg_name)
                return ERR_PTR(-EDESTADDRREQ);

        key = rx->key;
        if (key && !rx->key->payload.data[0])
                key = NULL;

        memset(&cp, 0, sizeof(cp));
        cp.local                = rx->local;
        cp.key                  = rx->key;
        cp.security_level       = rx->min_sec_level;
        cp.exclusive            = rx->exclusive | exclusive;
        cp.service_id           = srx->srx_service;
        call = rxrpc_new_client_call(rx, &cp, srx, user_call_ID, GFP_KERNEL);

        _leave(" = %p\n", call);
        return call;
}

/*
 * send a message forming part of a client call through an RxRPC socket
 * - caller holds the socket locked
 * - the socket may be either a client socket or a server socket
 */
int rxrpc_do_sendmsg(struct rxrpc_sock *rx, struct msghdr *msg, size_t len)
{
        enum rxrpc_command cmd;
        struct rxrpc_call *call;
        unsigned long user_call_ID = 0;
        bool exclusive = false;
        u32 abort_code = 0;
        int ret;

        _enter("");

        ret = rxrpc_sendmsg_cmsg(msg, &user_call_ID, &cmd, &abort_code,
                                 &exclusive);
        if (ret < 0)
                return ret;

        if (cmd == RXRPC_CMD_ACCEPT) {
                if (rx->sk.sk_state != RXRPC_SERVER_LISTENING)
                        return -EINVAL;
                call = rxrpc_accept_call(rx, user_call_ID, NULL);
                if (IS_ERR(call))
                        return PTR_ERR(call);
                rxrpc_put_call(call, rxrpc_call_put);
                return 0;
        }

        call = rxrpc_find_call_by_user_ID(rx, user_call_ID);
        if (!call) {
                if (cmd != RXRPC_CMD_SEND_DATA)
                        return -EBADSLT;
                call = rxrpc_new_client_call_for_sendmsg(rx, msg, user_call_ID,
                                                         exclusive);
                if (IS_ERR(call))
                        return PTR_ERR(call);
        }

        _debug("CALL %d USR %lx ST %d on CONN %p",
               call->debug_id, call->user_call_ID, call->state, call->conn);

        if (call->state >= RXRPC_CALL_COMPLETE) {
                /* it's too late for this call */
                ret = -ESHUTDOWN;
        } else if (cmd == RXRPC_CMD_SEND_ABORT) {
                ret = 0;
                if (rxrpc_abort_call("CMD", call, 0, abort_code, ECONNABORTED))
                        ret = rxrpc_send_abort_packet(call);
        } else if (cmd != RXRPC_CMD_SEND_DATA) {
                ret = -EINVAL;
        } else if (rxrpc_is_client_call(call) &&
                   call->state != RXRPC_CALL_CLIENT_SEND_REQUEST) {
                /* request phase complete for this client call */
                ret = -EPROTO;
        } else if (rxrpc_is_service_call(call) &&
                   call->state != RXRPC_CALL_SERVER_ACK_REQUEST &&
                   call->state != RXRPC_CALL_SERVER_SEND_REPLY) {
                /* Reply phase not begun or not complete for service call. */
                ret = -EPROTO;
        } else {
                ret = rxrpc_send_data(rx, call, msg, len);
        }

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

/**
 * rxrpc_kernel_send_data - Allow a kernel service to send data on a call
 * @sock: The socket the call is on
 * @call: The call to send data through
 * @msg: The data to send
 * @len: The amount of data to send
 *
 * Allow a kernel service to send data on a call.  The call must be in an state
 * appropriate to sending data.  No control data should be supplied in @msg,
 * nor should an address be supplied.  MSG_MORE should be flagged if there's
 * more data to come, otherwise this data will end the transmission phase.
 */
int rxrpc_kernel_send_data(struct socket *sock, struct rxrpc_call *call,
                           struct msghdr *msg, size_t len)
{
        int ret;

        _enter("{%d,%s},", call->debug_id, rxrpc_call_states[call->state]);

        ASSERTCMP(msg->msg_name, ==, NULL);
        ASSERTCMP(msg->msg_control, ==, NULL);

        lock_sock(sock->sk);

        _debug("CALL %d USR %lx ST %d on CONN %p",
               call->debug_id, call->user_call_ID, call->state, call->conn);

        if (call->state >= RXRPC_CALL_COMPLETE) {
                ret = -ESHUTDOWN; /* it's too late for this call */
        } else if (call->state != RXRPC_CALL_CLIENT_SEND_REQUEST &&
                   call->state != RXRPC_CALL_SERVER_ACK_REQUEST &&
                   call->state != RXRPC_CALL_SERVER_SEND_REPLY) {
                ret = -EPROTO; /* request phase complete for this client call */
        } else {
                ret = rxrpc_send_data(rxrpc_sk(sock->sk), call, msg, len);
        }

        release_sock(sock->sk);
        _leave(" = %d", ret);
        return ret;
}
EXPORT_SYMBOL(rxrpc_kernel_send_data);

/**
 * rxrpc_kernel_abort_call - Allow a kernel service to abort a call
 * @sock: The socket the call is on
 * @call: The call to be aborted
 * @abort_code: The abort code to stick into the ABORT packet
 * @error: Local error value
 * @why: 3-char string indicating why.
 *
 * Allow a kernel service to abort a call, if it's still in an abortable state.
 */
void rxrpc_kernel_abort_call(struct socket *sock, struct rxrpc_call *call,
                             u32 abort_code, int error, const char *why)
{
        _enter("{%d},%d,%d,%s", call->debug_id, abort_code, error, why);

        lock_sock(sock->sk);

        if (rxrpc_abort_call(why, call, 0, abort_code, error))
                rxrpc_send_abort_packet(call);

        release_sock(sock->sk);
        _leave("");
}

EXPORT_SYMBOL(rxrpc_kernel_abort_call);