/*
 * net/tipc/msg.c: TIPC message header routines
 *
 * Copyright (c) 2000-2006, 2014, Ericsson AB
 * Copyright (c) 2005, 2010-2011, Wind River Systems
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the names of the copyright holders nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * Alternatively, this software may be distributed under the terms of the
 * GNU General Public License ("GPL") version 2 as published by the Free
 * Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <net/sock.h>
#include "core.h"
#include "msg.h"
#include "addr.h"
#include "name_table.h"

#define MAX_FORWARD_SIZE 1024

static unsigned int align(unsigned int i)
{
        return (i + 3) & ~3u;
}

/**
 * tipc_buf_acquire - creates a TIPC message buffer
 * @size: message size (including TIPC header)
 *
 * Returns a new buffer with data pointers set to the specified size.
 *
 * NOTE: Headroom is reserved to allow prepending of a data link header.
 *       There may also be unrequested tailroom present at the buffer's end.
 */
struct sk_buff *tipc_buf_acquire(u32 size)
{
        struct sk_buff *skb;
        unsigned int buf_size = (BUF_HEADROOM + size + 3) & ~3u;

        skb = alloc_skb_fclone(buf_size, GFP_ATOMIC);
        if (skb) {
                skb_reserve(skb, BUF_HEADROOM);
                skb_put(skb, size);
                skb->next = NULL;
        }
        return skb;
}

void tipc_msg_init(u32 own_node, struct tipc_msg *m, u32 user, u32 type,
                   u32 hsize, u32 dnode)
{
        memset(m, 0, hsize);
        msg_set_version(m);
        msg_set_user(m, user);
        msg_set_hdr_sz(m, hsize);
        msg_set_size(m, hsize);
        msg_set_prevnode(m, own_node);
        msg_set_type(m, type);
        if (hsize > SHORT_H_SIZE) {
                msg_set_orignode(m, own_node);
                msg_set_destnode(m, dnode);
        }
}

struct sk_buff *tipc_msg_create(uint user, uint type,
                                uint hdr_sz, uint data_sz, u32 dnode,
                                u32 onode, u32 dport, u32 oport, int errcode)
{
        struct tipc_msg *msg;
        struct sk_buff *buf;

        buf = tipc_buf_acquire(hdr_sz + data_sz);
        if (unlikely(!buf))
                return NULL;

        msg = buf_msg(buf);
        tipc_msg_init(onode, msg, user, type, hdr_sz, dnode);
        msg_set_size(msg, hdr_sz + data_sz);
        msg_set_origport(msg, oport);
        msg_set_destport(msg, dport);
        msg_set_errcode(msg, errcode);
        if (hdr_sz > SHORT_H_SIZE) {
                msg_set_orignode(msg, onode);
                msg_set_destnode(msg, dnode);
        }
        return buf;
}

/* tipc_buf_append(): Append a buffer to the fragment list of another buffer
 * @*headbuf: in:  NULL for first frag, otherwise value returned from prev call
 *            out: set when successful non-complete reassembly, otherwise NULL
 * @*buf:     in:  the buffer to append. Always defined
 *            out: head buf after successful complete reassembly, otherwise NULL
 * Returns 1 when reassembly complete, otherwise 0
 */
int tipc_buf_append(struct sk_buff **headbuf, struct sk_buff **buf)
{
        struct sk_buff *head = *headbuf;
        struct sk_buff *frag = *buf;
        struct sk_buff *tail;
        struct tipc_msg *msg;
        u32 fragid;
        int delta;
        bool headstolen;

        if (!frag)
                goto err;

        msg = buf_msg(frag);
        fragid = msg_type(msg);
        frag->next = NULL;
        skb_pull(frag, msg_hdr_sz(msg));

        if (fragid == FIRST_FRAGMENT) {
                if (unlikely(head))
                        goto err;
                if (unlikely(skb_unclone(frag, GFP_ATOMIC)))
                        goto err;
                head = *headbuf = frag;
                skb_frag_list_init(head);
                TIPC_SKB_CB(head)->tail = NULL;
                *buf = NULL;
                return 0;
        }

        if (!head)
                goto err;

        if (skb_try_coalesce(head, frag, &headstolen, &delta)) {
                kfree_skb_partial(frag, headstolen);
        } else {
                tail = TIPC_SKB_CB(head)->tail;
                if (!skb_has_frag_list(head))
                        skb_shinfo(head)->frag_list = frag;
                else
                        tail->next = frag;
                head->truesize += frag->truesize;
                head->data_len += frag->len;
                head->len += frag->len;
                TIPC_SKB_CB(head)->tail = frag;
        }

        if (fragid == LAST_FRAGMENT) {
                *buf = head;
                TIPC_SKB_CB(head)->tail = NULL;
                *headbuf = NULL;
                return 1;
        }
        *buf = NULL;
        return 0;

err:
        pr_warn_ratelimited("Unable to build fragment list\n");
        kfree_skb(*buf);
        kfree_skb(*headbuf);
        *buf = *headbuf = NULL;
        return 0;
}


/**
 * tipc_msg_build - create buffer chain containing specified header and data
 * @mhdr: Message header, to be prepended to data
 * @m: User message
 * @dsz: Total length of user data
 * @pktmax: Max packet size that can be used
 * @list: Buffer or chain of buffers to be returned to caller
 *
 * Returns message data size or errno: -ENOMEM, -EFAULT
 */
int tipc_msg_build(struct tipc_msg *mhdr, struct msghdr *m,
                   int offset, int dsz, int pktmax, struct sk_buff_head *list)
{
        int mhsz = msg_hdr_sz(mhdr);
        int msz = mhsz + dsz;
        int pktno = 1;
        int pktsz;
        int pktrem = pktmax;
        int drem = dsz;
        struct tipc_msg pkthdr;
        struct sk_buff *skb;
        char *pktpos;
        int rc;

        msg_set_size(mhdr, msz);

        /* No fragmentation needed? */
        if (likely(msz <= pktmax)) {
                skb = tipc_buf_acquire(msz);
                if (unlikely(!skb))
                        return -ENOMEM;
                skb_orphan(skb);
                __skb_queue_tail(list, skb);
                skb_copy_to_linear_data(skb, mhdr, mhsz);
                pktpos = skb->data + mhsz;
                if (copy_from_iter(pktpos, dsz, &m->msg_iter) == dsz)
                        return dsz;
                rc = -EFAULT;
                goto error;
        }

        /* Prepare reusable fragment header */
        tipc_msg_init(msg_prevnode(mhdr), &pkthdr, MSG_FRAGMENTER,
                      FIRST_FRAGMENT, INT_H_SIZE, msg_destnode(mhdr));
        msg_set_size(&pkthdr, pktmax);
        msg_set_fragm_no(&pkthdr, pktno);

        /* Prepare first fragment */
        skb = tipc_buf_acquire(pktmax);
        if (!skb)
                return -ENOMEM;
        skb_orphan(skb);
        __skb_queue_tail(list, skb);
        pktpos = skb->data;
        skb_copy_to_linear_data(skb, &pkthdr, INT_H_SIZE);
        pktpos += INT_H_SIZE;
        pktrem -= INT_H_SIZE;
        skb_copy_to_linear_data_offset(skb, INT_H_SIZE, mhdr, mhsz);
        pktpos += mhsz;
        pktrem -= mhsz;

        do {
                if (drem < pktrem)
                        pktrem = drem;

                if (copy_from_iter(pktpos, pktrem, &m->msg_iter) != pktrem) {
                        rc = -EFAULT;
                        goto error;
                }
                drem -= pktrem;

                if (!drem)
                        break;

                /* Prepare new fragment: */
                if (drem < (pktmax - INT_H_SIZE))
                        pktsz = drem + INT_H_SIZE;
                else
                        pktsz = pktmax;
                skb = tipc_buf_acquire(pktsz);
                if (!skb) {
                        rc = -ENOMEM;
                        goto error;
                }
                skb_orphan(skb);
                __skb_queue_tail(list, skb);
                msg_set_type(&pkthdr, FRAGMENT);
                msg_set_size(&pkthdr, pktsz);
                msg_set_fragm_no(&pkthdr, ++pktno);
                skb_copy_to_linear_data(skb, &pkthdr, INT_H_SIZE);
                pktpos = skb->data + INT_H_SIZE;
                pktrem = pktsz - INT_H_SIZE;

        } while (1);
        msg_set_type(buf_msg(skb), LAST_FRAGMENT);
        return dsz;
error:
        __skb_queue_purge(list);
        __skb_queue_head_init(list);
        return rc;
}

/**
 * tipc_msg_bundle(): Append contents of a buffer to tail of an existing one
 * @list: the buffer chain of the existing buffer ("bundle")
 * @skb:  buffer to be appended
 * @mtu:  max allowable size for the bundle buffer
 * Consumes buffer if successful
 * Returns true if bundling could be performed, otherwise false
 */
bool tipc_msg_bundle(struct sk_buff_head *list, struct sk_buff *skb, u32 mtu)
{
        struct sk_buff *bskb = skb_peek_tail(list);
        struct tipc_msg *bmsg = buf_msg(bskb);
        struct tipc_msg *msg = buf_msg(skb);
        unsigned int bsz = msg_size(bmsg);
        unsigned int msz = msg_size(msg);
        u32 start = align(bsz);
        u32 max = mtu - INT_H_SIZE;
        u32 pad = start - bsz;

        if (likely(msg_user(msg) == MSG_FRAGMENTER))
                return false;
        if (unlikely(msg_user(msg) == CHANGEOVER_PROTOCOL))
                return false;
        if (unlikely(msg_user(msg) == BCAST_PROTOCOL))
                return false;
        if (likely(msg_user(bmsg) != MSG_BUNDLER))
                return false;
        if (likely(!TIPC_SKB_CB(bskb)->bundling))
                return false;
        if (unlikely(skb_tailroom(bskb) < (pad + msz)))
                return false;
        if (unlikely(max < (start + msz)))
                return false;

        skb_put(bskb, pad + msz);
        skb_copy_to_linear_data_offset(bskb, start, skb->data, msz);
        msg_set_size(bmsg, start + msz);
        msg_set_msgcnt(bmsg, msg_msgcnt(bmsg) + 1);
        kfree_skb(skb);
        return true;
}

/**
 *  tipc_msg_extract(): extract bundled inner packet from buffer
 *  @skb: linear outer buffer, to be extracted from.
 *  @iskb: extracted inner buffer, to be returned
 *  @pos: position of msg to be extracted. Returns with pointer of next msg
 *  Consumes outer buffer when last packet extracted
 *  Returns true when when there is an extracted buffer, otherwise false
 */
bool tipc_msg_extract(struct sk_buff *skb, struct sk_buff **iskb, int *pos)
{
        struct tipc_msg *msg = buf_msg(skb);
        int imsz;
        struct tipc_msg *imsg = (struct tipc_msg *)(msg_data(msg) + *pos);

        /* Is there space left for shortest possible message? */
        if (*pos > (msg_data_sz(msg) - SHORT_H_SIZE))
                goto none;
        imsz = msg_size(imsg);

        /* Is there space left for current message ? */
        if ((*pos + imsz) > msg_data_sz(msg))
                goto none;
        *iskb = tipc_buf_acquire(imsz);
        if (!*iskb)
                goto none;
        skb_copy_to_linear_data(*iskb, imsg, imsz);
        *pos += align(imsz);
        return true;
none:
        kfree_skb(skb);
        *iskb = NULL;
        return false;
}

/**
 * tipc_msg_make_bundle(): Create bundle buf and append message to its tail
 * @list: the buffer chain
 * @skb: buffer to be appended and replaced
 * @mtu: max allowable size for the bundle buffer, inclusive header
 * @dnode: destination node for message. (Not always present in header)
 * Replaces buffer if successful
 * Returns true if success, otherwise false
 */
bool tipc_msg_make_bundle(struct sk_buff_head *list,
                          struct sk_buff *skb, u32 mtu, u32 dnode)
{
        struct sk_buff *bskb;
        struct tipc_msg *bmsg;
        struct tipc_msg *msg = buf_msg(skb);
        u32 msz = msg_size(msg);
        u32 max = mtu - INT_H_SIZE;

        if (msg_user(msg) == MSG_FRAGMENTER)
                return false;
        if (msg_user(msg) == CHANGEOVER_PROTOCOL)
                return false;
        if (msg_user(msg) == BCAST_PROTOCOL)
                return false;
        if (msz > (max / 2))
                return false;

        bskb = tipc_buf_acquire(max);
        if (!bskb)
                return false;

        skb_trim(bskb, INT_H_SIZE);
        bmsg = buf_msg(bskb);
        tipc_msg_init(msg_prevnode(msg), bmsg, MSG_BUNDLER, 0,
                      INT_H_SIZE, dnode);
        msg_set_seqno(bmsg, msg_seqno(msg));
        msg_set_ack(bmsg, msg_ack(msg));
        msg_set_bcast_ack(bmsg, msg_bcast_ack(msg));
        TIPC_SKB_CB(bskb)->bundling = true;
        __skb_queue_tail(list, bskb);
        return tipc_msg_bundle(list, skb, mtu);
}

/**
 * tipc_msg_reverse(): swap source and destination addresses and add error code
 * @buf:  buffer containing message to be reversed
 * @dnode: return value: node where to send message after reversal
 * @err:  error code to be set in message
 * Consumes buffer if failure
 * Returns true if success, otherwise false
 */
bool tipc_msg_reverse(u32 own_addr,  struct sk_buff *buf, u32 *dnode,
                      int err)
{
        struct tipc_msg *msg = buf_msg(buf);
        uint imp = msg_importance(msg);
        struct tipc_msg ohdr;
        uint rdsz = min_t(uint, msg_data_sz(msg), MAX_FORWARD_SIZE);

        if (skb_linearize(buf))
                goto exit;
        if (msg_dest_droppable(msg))
                goto exit;
        if (msg_errcode(msg))
                goto exit;

        memcpy(&ohdr, msg, msg_hdr_sz(msg));
        imp = min_t(uint, imp + 1, TIPC_CRITICAL_IMPORTANCE);
        if (msg_isdata(msg))
                msg_set_importance(msg, imp);
        msg_set_errcode(msg, err);
        msg_set_origport(msg, msg_destport(&ohdr));
        msg_set_destport(msg, msg_origport(&ohdr));
        msg_set_prevnode(msg, own_addr);
        if (!msg_short(msg)) {
                msg_set_orignode(msg, msg_destnode(&ohdr));
                msg_set_destnode(msg, msg_orignode(&ohdr));
        }
        msg_set_size(msg, msg_hdr_sz(msg) + rdsz);
        skb_trim(buf, msg_size(msg));
        skb_orphan(buf);
        *dnode = msg_orignode(&ohdr);
        return true;
exit:
        kfree_skb(buf);
        *dnode = 0;
        return false;
}

/**
 * tipc_msg_lookup_dest(): try to find new destination for named message
 * @skb: the buffer containing the message.
 * @dnode: return value: next-hop node, if destination found
 * @err: return value: error code to use, if message to be rejected
 * Does not consume buffer
 * Returns true if a destination is found, false otherwise
 */
bool tipc_msg_lookup_dest(struct net *net, struct sk_buff *skb,
                          u32 *dnode, int *err)
{
        struct tipc_msg *msg = buf_msg(skb);
        u32 dport;

        if (!msg_isdata(msg))
                return false;
        if (!msg_named(msg))
                return false;
        *err = -TIPC_ERR_NO_NAME;
        if (skb_linearize(skb))
                return false;
        if (msg_reroute_cnt(msg) > 0)
                return false;
        *dnode = addr_domain(net, msg_lookup_scope(msg));
        dport = tipc_nametbl_translate(net, msg_nametype(msg),
                                       msg_nameinst(msg), dnode);
        if (!dport)
                return false;
        msg_incr_reroute_cnt(msg);
        msg_set_destnode(msg, *dnode);
        msg_set_destport(msg, dport);
        *err = TIPC_OK;
        return true;
}

/* tipc_msg_reassemble() - clone a buffer chain of fragments and
 *                         reassemble the clones into one message
 */
struct sk_buff *tipc_msg_reassemble(struct sk_buff_head *list)
{
        struct sk_buff *skb;
        struct sk_buff *frag = NULL;
        struct sk_buff *head = NULL;
        int hdr_sz;

        /* Copy header if single buffer */
        if (skb_queue_len(list) == 1) {
                skb = skb_peek(list);
                hdr_sz = skb_headroom(skb) + msg_hdr_sz(buf_msg(skb));
                return __pskb_copy(skb, hdr_sz, GFP_ATOMIC);
        }

        /* Clone all fragments and reassemble */
        skb_queue_walk(list, skb) {
                frag = skb_clone(skb, GFP_ATOMIC);
                if (!frag)
                        goto error;
                frag->next = NULL;
                if (tipc_buf_append(&head, &frag))
                        break;
                if (!head)
                        goto error;
        }
        return frag;
error:
        pr_warn("Failed do clone local mcast rcv buffer\n");
        kfree_skb(head);
        return NULL;
}