/*
**  Licensed to the Apache Software Foundation (ASF) under one or more
** contributor license agreements.  See the NOTICE file distributed with
** this work for additional information regarding copyright ownership.
** The ASF licenses this file to You under the Apache License, Version 2.0
** (the "License"); you may not use this file except in compliance with
** the License.  You may obtain a copy of the License at
**
**      http://www.apache.org/licenses/LICENSE-2.0
**
**  Unless required by applicable law or agreed to in writing, software
**  distributed under the License is distributed on an "AS IS" BASIS,
**  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
**  See the License for the specific language governing permissions and
**  limitations under the License.
*/
#include <assert.h>
#include "apreq_parser.h"
#include "apreq_error.h"
#include "apreq_util.h"

#include "apr_lib.h" /* for apr_iscntrl() & co */

#define PARSER_STATUS_CHECK(PREFIX)   do {         \
    if (ctx->status == PREFIX##_ERROR)             \
        return APREQ_ERROR_GENERAL;                \
    else if (ctx->status == PREFIX##_COMPLETE)     \
        return APR_SUCCESS;                        \
    else if (bb == NULL)                           \
        return APR_INCOMPLETE;                     \
} while (0);


struct hdr_ctx {
    apr_bucket_brigade *bb;
    apr_size_t          nlen;
    apr_size_t          glen;
    apr_size_t          vlen;
    enum {
        HDR_NAME,
        HDR_GAP,
        HDR_VALUE,
        HDR_NEWLINE,
        HDR_ENDLINE,
        HDR_FOLDLINE,
        HDR_LASTLINE,
        HDR_COMPLETE,
        HDR_ERROR
    }                   status;
};

/********************* header parsing utils ********************/


static apr_bucket *split_header_line(apr_bucket *e, apr_size_t *off,
                                     const char **data, apr_size_t *dlen)
{
    if (*off > 1) {
        apr_bucket_split(e, *off - 1);
        e = APR_BUCKET_NEXT(e);
        *dlen -= *off - 1;
        *data += *off - 1;
        *off = 1;
    }
    return e;
}

static apr_status_t consume_header_line(apreq_param_t **p,
                                        apr_pool_t *pool,
                                        apr_bucket_brigade *bb,
                                        apr_size_t nlen,
                                        apr_size_t glen,
                                        apr_size_t vlen)
{
    apreq_param_t *param;
    apreq_value_t *v;
    apr_bucket *e, *f;
    apr_status_t s;
    struct iovec vec[APREQ_DEFAULT_NELTS], *iov;
    apr_array_header_t arr;
    char *dest;
    const char *data;
    apr_size_t dlen;
    int i, eol = 0;

    param = apreq_param_make(pool, NULL, nlen, NULL, vlen);
    *(const apreq_value_t **)&v = &param->v;

    arr.pool     = pool;
    arr.elt_size = sizeof(struct iovec);
    arr.nelts    = 0;
    arr.nalloc   = APREQ_DEFAULT_NELTS;
    arr.elts     = (char *)vec;

    e = APR_BRIGADE_FIRST(bb);

    /* store name in a temporary iovec array */
    do {
        apr_size_t len;

        assert(e != APR_BRIGADE_SENTINEL(bb));
        iov = (struct iovec *)apr_array_push(&arr);
        s = apr_bucket_read(e, (const char **)&iov->iov_base,
                            &len, APR_BLOCK_READ);
        if (s != APR_SUCCESS)
            return s;
        iov->iov_len = len;

        assert(nlen >= len);
        nlen -= len;

        e = APR_BUCKET_NEXT(e);
    } while (nlen > 0);

    /* skip gap */
    do {
        assert(e != APR_BRIGADE_SENTINEL(bb));
        s = apr_bucket_read(e, &data, &dlen, APR_BLOCK_READ);
        if (s != APR_SUCCESS)
            return s;

        assert(glen >= dlen);
        glen -= dlen;

        e = APR_BUCKET_NEXT(e);
    } while (glen > 0);

    /* copy value */
    dest = v->data;
    do {
        apr_size_t off;

        assert(e != APR_BRIGADE_SENTINEL(bb));
        s = apr_bucket_read(e, &data, &dlen, APR_BLOCK_READ);
        if (s != APR_SUCCESS)
            return s;

        for (off = 0; off < dlen; ++off) {
            const char ch = data[off];
            if (ch == '\r' || ch == '\n') {
                /* Eat [CR]LF of continuation or end of line */
                if (!vlen && ch == '\n')
                    eol = 1; /* done */
                continue;
            }
            assert(vlen > 0);
            *dest = ch;
            ++dest;
            --vlen;
        }

        e = APR_BUCKET_NEXT(e);
    } while (!eol);
    v->dlen = dest - v->data;
    *dest++ = 0;

    /* write name */
    v->name = dest;
    for (i = 0; i < arr.nelts; ++i) {
        iov = &((struct iovec *)arr.elts)[i];
        memcpy(dest, iov->iov_base, iov->iov_len);
        dest += iov->iov_len;
        ++iov;
    }
    v->nlen = dest - v->name;
    *dest = 0;

    while ((f = APR_BRIGADE_FIRST(bb)) != e)
        apr_bucket_delete(f);

    apreq_param_tainted_on(param);
    *p = param;
    return APR_SUCCESS;

}

#define IS_TOKEN_CHAR(c) (apr_isalnum(c) \
                          || ((c) && strchr("!#$%&'*+-.^_`|~", (c))))

APREQ_DECLARE_PARSER(apreq_parse_headers)
{
    apr_pool_t *pool = parser->pool;
    apr_bucket *e;
    struct hdr_ctx *ctx;
    char ch;

    if (parser->ctx == NULL) {
        ctx = apr_pcalloc(pool, sizeof *ctx);
        ctx->bb = apr_brigade_create(pool, parser->bucket_alloc);
        parser->ctx = ctx;
        ctx->status = HDR_NAME;
    }
    else
        ctx = parser->ctx;

    PARSER_STATUS_CHECK(HDR);
    e = APR_BRIGADE_LAST(ctx->bb);
    APR_BRIGADE_CONCAT(ctx->bb, bb);

    /* parse the brigade for CRLF_CRLF-terminated header block,
     * each time starting from the front of the brigade.
     */

    for (e = APR_BUCKET_NEXT(e);
         e != APR_BRIGADE_SENTINEL(ctx->bb);
         e = APR_BUCKET_NEXT(e))
    {
        apr_size_t off = 0, dlen;
        const char *data;
        apr_status_t s;
        apreq_param_t *param = NULL; /* silences gcc-4.0 warning */

        if (APR_BUCKET_IS_EOS(e)) {
            ctx->status = HDR_COMPLETE;
            APR_BRIGADE_CONCAT(bb, ctx->bb);
            return APR_SUCCESS;
        }

        s = apr_bucket_read(e, &data, &dlen, APR_BLOCK_READ);
        if ( s != APR_SUCCESS ) {
            ctx->status = HDR_ERROR;
            return s;
        }
        if (dlen == 0)
            continue;

    parse_hdr_bucket:

        /*              gap           nlen = 13
         *              vvv           glen =  3
         * Sample-Header:  grape      vlen =  5
         * ^^^^^^^^^^^^^   ^^^^^
         *     name        value
         */

        switch (ctx->status) {

        case HDR_NAME:

            while (off < dlen) {
                ch = data[off++];
                switch (ch) {
                case ':':
                    if (!ctx->nlen) {
                        ctx->status = HDR_ERROR;
                        return APREQ_ERROR_BADHEADER;
                    }
                    e = split_header_line(e, &off, &data, &dlen);
                    ++ctx->glen;
                    ctx->status = HDR_GAP;
                    goto parse_hdr_bucket;

                default:
                    if (!IS_TOKEN_CHAR(ch)) {
                        ctx->status = HDR_ERROR;
                        return APREQ_ERROR_BADCHAR;
                    }
                    ++ctx->nlen;
                }
            }
            break;


        case HDR_GAP:

            while (off < dlen) {
                ch = data[off++];
                switch (ch) {
                case ' ':
                case '\t':
                    ++ctx->glen;
                    break;

                case '\n':
                    e = split_header_line(e, &off, &data, &dlen);
                    ctx->status = HDR_NEWLINE;
                    goto parse_hdr_bucket;

                case '\r':
                    e = split_header_line(e, &off, &data, &dlen);
                    ctx->status = HDR_ENDLINE;
                    goto parse_hdr_bucket;

                default:
                    if (apr_iscntrl(ch)) {
                        ctx->status = HDR_ERROR;
                        return APREQ_ERROR_BADCHAR;
                    }
                    e = split_header_line(e, &off, &data, &dlen);
                    ++ctx->vlen;
                    ctx->status = HDR_VALUE;
                    goto parse_hdr_bucket;
                }
            }
            break;


        case HDR_VALUE:

            while (off < dlen) {
                ch = data[off++];
                switch (ch) {
                case '\n':
                    ctx->status = HDR_NEWLINE;
                    goto parse_hdr_bucket;

                case '\r':
                    ctx->status = HDR_ENDLINE;
                    goto parse_hdr_bucket;

                default:
                    if (apr_iscntrl(ch)) {
                        ctx->status = HDR_ERROR;
                        return APREQ_ERROR_BADCHAR;
                    }
                    ++ctx->vlen;
                }
            }
            break;


        case HDR_ENDLINE:
        case HDR_LASTLINE:

            if (off == dlen)
                break;

            if (data[off++] != '\n') {
                ctx->status = HDR_ERROR;
                return APREQ_ERROR_BADHEADER;
            }

            if (ctx->status == HDR_LASTLINE) {
                ctx->status = HDR_COMPLETE;
                goto parse_hdr_bucket;
            }

            /* fall thru */
            ctx->status = HDR_NEWLINE;

        case HDR_NEWLINE:

            if (off == dlen)
                break;

            ch = data[off++];
            switch (ch) {
            case ' ':
            case '\t':
                ++ctx->vlen;
                break;

            default:
                e = split_header_line(e, &off, &data, &dlen);

                /* consume from splitted brigade now */
                s = consume_header_line(&param, pool, ctx->bb,
                                        ctx->nlen, ctx->glen, ctx->vlen);
                if (parser->hook != NULL && s == APR_SUCCESS)
                    s = apreq_hook_run(parser->hook, param, NULL);
                if (s != APR_SUCCESS) {
                    ctx->status = HDR_ERROR;
                    return s;
                }
                apreq_value_table_add(&param->v, t);
                ctx->nlen = 0;
                ctx->vlen = 0;
                ctx->glen = 0;

                switch (ch) {
                case '\n':
                    ctx->status = HDR_COMPLETE;
                    break;

                case '\r':
                    ctx->status = HDR_LASTLINE;
                    break;

                default:
                    if (!IS_TOKEN_CHAR(ch)) {
                        ctx->status = HDR_ERROR;
                        return APREQ_ERROR_BADCHAR;
                    }
                    ++ctx->nlen;
                    ctx->status = HDR_NAME;
                    break;
                }
                goto parse_hdr_bucket;
            }

            /* fall thru */
            ctx->status = HDR_FOLDLINE;

        case HDR_FOLDLINE:

            while (off < dlen) {
                ch = data[off++];
                switch (ch) {
                case ' ':
                case '\t':
                    ++ctx->vlen;
                    break;

                case '\n':
                    ctx->status = HDR_NEWLINE;
                    goto parse_hdr_bucket;

                case '\r':
                    ctx->status = HDR_ENDLINE;
                    goto parse_hdr_bucket;

                default:
                    if (apr_iscntrl(ch)) {
                        ctx->status = HDR_ERROR;
                        return APREQ_ERROR_BADCHAR;
                    }
                    ctx->status = HDR_VALUE;
                    ++ctx->vlen;
                    goto parse_hdr_bucket;
                }
            }
            break;


        case HDR_COMPLETE:

            if (off < dlen)
                apr_bucket_split(e, off);

            e = APR_BUCKET_NEXT(e);
            do {
                apr_bucket *f = APR_BRIGADE_FIRST(ctx->bb);
                apr_bucket_delete(f);
            } while (e != APR_BRIGADE_FIRST(ctx->bb));

            APR_BRIGADE_CONCAT(bb, ctx->bb);
            return APR_SUCCESS;


        default:
            assert(0); /* not reached */
        }
    }
    apreq_brigade_setaside(ctx->bb,pool);
    return APR_INCOMPLETE;
}