/*
 * Copyright (c) 2005-2006 Network Appliance, Inc. All rights reserved.
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the BSD-type
 * license below:
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *      Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 *
 *      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.
 *
 *      Neither the name of the Network Appliance, Inc. nor the names of
 *      its contributors may be used to endorse or promote products
 *      derived from this software without specific prior written
 *      permission.
 *
 * 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.
 *
 * Author: Tom Tucker <tom@opengridcomputing.com>
 */

#include <linux/sunrpc/xdr.h>
#include <linux/sunrpc/debug.h>
#include <asm/unaligned.h>
#include <linux/sunrpc/rpc_rdma.h>
#include <linux/sunrpc/svc_rdma.h>

#define RPCDBG_FACILITY RPCDBG_SVCXPRT

/*
 * Decodes a read chunk list. The expected format is as follows:
 *    descrim  : xdr_one
 *    position : __be32 offset into XDR stream
 *    handle   : __be32 RKEY
 *    . . .
 *  end-of-list: xdr_zero
 */
static __be32 *decode_read_list(__be32 *va, __be32 *vaend)
{
        struct rpcrdma_read_chunk *ch = (struct rpcrdma_read_chunk *)va;

        while (ch->rc_discrim != xdr_zero) {
                if (((unsigned long)ch + sizeof(struct rpcrdma_read_chunk)) >
                    (unsigned long)vaend) {
                        dprintk("svcrdma: vaend=%p, ch=%p\n", vaend, ch);
                        return NULL;
                }
                ch++;
        }
        return &ch->rc_position;
}

/*
 * Decodes a write chunk list. The expected format is as follows:
 *    descrim  : xdr_one
 *    nchunks  : <count>
 *       handle   : __be32 RKEY           ---+
 *       length   : __be32 <len of segment>  |
 *       offset   : remove va                + <count>
 *       . . .                               |
 *                                        ---+
 */
static __be32 *decode_write_list(__be32 *va, __be32 *vaend)
{
        unsigned long start, end;
        int nchunks;

        struct rpcrdma_write_array *ary =
                (struct rpcrdma_write_array *)va;

        /* Check for not write-array */
        if (ary->wc_discrim == xdr_zero)
                return &ary->wc_nchunks;

        if ((unsigned long)ary + sizeof(struct rpcrdma_write_array) >
            (unsigned long)vaend) {
                dprintk("svcrdma: ary=%p, vaend=%p\n", ary, vaend);
                return NULL;
        }
        nchunks = be32_to_cpu(ary->wc_nchunks);

        start = (unsigned long)&ary->wc_array[0];
        end = (unsigned long)vaend;
        if (nchunks < 0 ||
            nchunks > (SIZE_MAX - start) / sizeof(struct rpcrdma_write_chunk) ||
            (start + (sizeof(struct rpcrdma_write_chunk) * nchunks)) > end) {
                dprintk("svcrdma: ary=%p, wc_nchunks=%d, vaend=%p\n",
                        ary, nchunks, vaend);
                return NULL;
        }
        /*
         * rs_length is the 2nd 4B field in wc_target and taking its
         * address skips the list terminator
         */
        return &ary->wc_array[nchunks].wc_target.rs_length;
}

static __be32 *decode_reply_array(__be32 *va, __be32 *vaend)
{
        unsigned long start, end;
        int nchunks;
        struct rpcrdma_write_array *ary =
                (struct rpcrdma_write_array *)va;

        /* Check for no reply-array */
        if (ary->wc_discrim == xdr_zero)
                return &ary->wc_nchunks;

        if ((unsigned long)ary + sizeof(struct rpcrdma_write_array) >
            (unsigned long)vaend) {
                dprintk("svcrdma: ary=%p, vaend=%p\n", ary, vaend);
                return NULL;
        }
        nchunks = be32_to_cpu(ary->wc_nchunks);

        start = (unsigned long)&ary->wc_array[0];
        end = (unsigned long)vaend;
        if (nchunks < 0 ||
            nchunks > (SIZE_MAX - start) / sizeof(struct rpcrdma_write_chunk) ||
            (start + (sizeof(struct rpcrdma_write_chunk) * nchunks)) > end) {
                dprintk("svcrdma: ary=%p, wc_nchunks=%d, vaend=%p\n",
                        ary, nchunks, vaend);
                return NULL;
        }
        return (__be32 *)&ary->wc_array[nchunks];
}

int svc_rdma_xdr_decode_req(struct rpcrdma_msg *rmsgp, struct svc_rqst *rqstp)
{
        __be32 *va, *vaend;
        unsigned int len;
        u32 hdr_len;

        /* Verify that there's enough bytes for header + something */
        if (rqstp->rq_arg.len <= RPCRDMA_HDRLEN_ERR) {
                dprintk("svcrdma: header too short = %d\n",
                        rqstp->rq_arg.len);
                return -EINVAL;
        }

        if (rmsgp->rm_vers != rpcrdma_version) {
                dprintk("%s: bad version %u\n", __func__,
                        be32_to_cpu(rmsgp->rm_vers));
                return -EPROTONOSUPPORT;
        }

        switch (be32_to_cpu(rmsgp->rm_type)) {
        case RDMA_MSG:
        case RDMA_NOMSG:
                break;

        case RDMA_DONE:
                /* Just drop it */
                dprintk("svcrdma: dropping RDMA_DONE message\n");
                return 0;

        case RDMA_ERROR:
                /* Possible if this is a backchannel reply.
                 * XXX: We should cancel this XID, though.
                 */
                dprintk("svcrdma: dropping RDMA_ERROR message\n");
                return 0;

        case RDMA_MSGP:
                /* Pull in the extra for the padded case, bump our pointer */
                rmsgp->rm_body.rm_padded.rm_align =
                        be32_to_cpu(rmsgp->rm_body.rm_padded.rm_align);
                rmsgp->rm_body.rm_padded.rm_thresh =
                        be32_to_cpu(rmsgp->rm_body.rm_padded.rm_thresh);

                va = &rmsgp->rm_body.rm_padded.rm_pempty[4];
                rqstp->rq_arg.head[0].iov_base = va;
                len = (u32)((unsigned long)va - (unsigned long)rmsgp);
                rqstp->rq_arg.head[0].iov_len -= len;
                if (len > rqstp->rq_arg.len)
                        return -EINVAL;
                return len;
        default:
                dprintk("svcrdma: bad rdma procedure (%u)\n",
                        be32_to_cpu(rmsgp->rm_type));
                return -EINVAL;
        }

        /* The chunk list may contain either a read chunk list or a write
         * chunk list and a reply chunk list.
         */
        va = &rmsgp->rm_body.rm_chunks[0];
        vaend = (__be32 *)((unsigned long)rmsgp + rqstp->rq_arg.len);
        va = decode_read_list(va, vaend);
        if (!va) {
                dprintk("svcrdma: failed to decode read list\n");
                return -EINVAL;
        }
        va = decode_write_list(va, vaend);
        if (!va) {
                dprintk("svcrdma: failed to decode write list\n");
                return -EINVAL;
        }
        va = decode_reply_array(va, vaend);
        if (!va) {
                dprintk("svcrdma: failed to decode reply chunk\n");
                return -EINVAL;
        }

        rqstp->rq_arg.head[0].iov_base = va;
        hdr_len = (unsigned long)va - (unsigned long)rmsgp;
        rqstp->rq_arg.head[0].iov_len -= hdr_len;

        return hdr_len;
}

int svc_rdma_xdr_encode_error(struct svcxprt_rdma *xprt,
                              struct rpcrdma_msg *rmsgp,
                              enum rpcrdma_errcode err, __be32 *va)
{
        __be32 *startp = va;

        *va++ = rmsgp->rm_xid;
        *va++ = rmsgp->rm_vers;
        *va++ = cpu_to_be32(xprt->sc_max_requests);
        *va++ = rdma_error;
        *va++ = cpu_to_be32(err);
        if (err == ERR_VERS) {
                *va++ = rpcrdma_version;
                *va++ = rpcrdma_version;
        }

        return (int)((unsigned long)va - (unsigned long)startp);
}

int svc_rdma_xdr_get_reply_hdr_len(struct rpcrdma_msg *rmsgp)
{
        struct rpcrdma_write_array *wr_ary;

        /* There is no read-list in a reply */

        /* skip write list */
        wr_ary = (struct rpcrdma_write_array *)
                &rmsgp->rm_body.rm_chunks[1];
        if (wr_ary->wc_discrim)
                wr_ary = (struct rpcrdma_write_array *)
                        &wr_ary->wc_array[be32_to_cpu(wr_ary->wc_nchunks)].
                        wc_target.rs_length;
        else
                wr_ary = (struct rpcrdma_write_array *)
                        &wr_ary->wc_nchunks;

        /* skip reply array */
        if (wr_ary->wc_discrim)
                wr_ary = (struct rpcrdma_write_array *)
                        &wr_ary->wc_array[be32_to_cpu(wr_ary->wc_nchunks)];
        else
                wr_ary = (struct rpcrdma_write_array *)
                        &wr_ary->wc_nchunks;

        return (unsigned long) wr_ary - (unsigned long) rmsgp;
}

void svc_rdma_xdr_encode_write_list(struct rpcrdma_msg *rmsgp, int chunks)
{
        struct rpcrdma_write_array *ary;

        /* no read-list */
        rmsgp->rm_body.rm_chunks[0] = xdr_zero;

        /* write-array discrim */
        ary = (struct rpcrdma_write_array *)
                &rmsgp->rm_body.rm_chunks[1];
        ary->wc_discrim = xdr_one;
        ary->wc_nchunks = cpu_to_be32(chunks);

        /* write-list terminator */
        ary->wc_array[chunks].wc_target.rs_handle = xdr_zero;

        /* reply-array discriminator */
        ary->wc_array[chunks].wc_target.rs_length = xdr_zero;
}

void svc_rdma_xdr_encode_reply_array(struct rpcrdma_write_array *ary,
                                 int chunks)
{
        ary->wc_discrim = xdr_one;
        ary->wc_nchunks = cpu_to_be32(chunks);
}

void svc_rdma_xdr_encode_array_chunk(struct rpcrdma_write_array *ary,
                                     int chunk_no,
                                     __be32 rs_handle,
                                     __be64 rs_offset,
                                     u32 write_len)
{
        struct rpcrdma_segment *seg = &ary->wc_array[chunk_no].wc_target;
        seg->rs_handle = rs_handle;
        seg->rs_offset = rs_offset;
        seg->rs_length = cpu_to_be32(write_len);
}

void svc_rdma_xdr_encode_reply_header(struct svcxprt_rdma *xprt,
                                  struct rpcrdma_msg *rdma_argp,
                                  struct rpcrdma_msg *rdma_resp,
                                  enum rpcrdma_proc rdma_type)
{
        rdma_resp->rm_xid = rdma_argp->rm_xid;
        rdma_resp->rm_vers = rdma_argp->rm_vers;
        rdma_resp->rm_credit = cpu_to_be32(xprt->sc_max_requests);
        rdma_resp->rm_type = cpu_to_be32(rdma_type);

        /* Encode <nul> chunks lists */
        rdma_resp->rm_body.rm_chunks[0] = xdr_zero;
        rdma_resp->rm_body.rm_chunks[1] = xdr_zero;
        rdma_resp->rm_body.rm_chunks[2] = xdr_zero;
}