/* 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 "apr_strings.h"
#include "ap_config.h"
#include "httpd.h"
#include "http_config.h"
#include "http_protocol.h"
#include "http_log.h"
#include "util_script.h"
#include "http_main.h"
#include "http_request.h"

#include "mod_core.h"

#define ASIS_MAGIC_TYPE "httpd/send-as-is"

static int asis_handler(request_rec *r)
{
    conn_rec *c = r->connection;
    apr_file_t *f = NULL;
    apr_status_t rv;
    const char *location;

    if(strcmp(r->handler,ASIS_MAGIC_TYPE) && strcmp(r->handler,"send-as-is"))
        return DECLINED;

    r->allowed |= (AP_METHOD_BIT << M_GET);
    if (r->method_number != M_GET)
        return DECLINED;
    if (r->finfo.filetype == 0) {
        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                    "File does not exist: %s", r->filename);
        return HTTP_NOT_FOUND;
    }

    if ((rv = apr_file_open(&f, r->filename, APR_READ,
                APR_OS_DEFAULT, r->pool)) != APR_SUCCESS) {
        ap_log_rerror(APLOG_MARK, APLOG_ERR, rv, r,
                    "file permissions deny server access: %s", r->filename);
        return HTTP_FORBIDDEN;
    }

    ap_scan_script_header_err(r, f, NULL);
    location = apr_table_get(r->headers_out, "Location");

    if (location && location[0] == '/' &&
        ((r->status == HTTP_OK) || ap_is_HTTP_REDIRECT(r->status))) {

        apr_file_close(f);

        /* Internal redirect -- fake-up a pseudo-request */
        r->status = HTTP_OK;

        /* This redirect needs to be a GET no matter what the original
         * method was.
         */
        r->method = apr_pstrdup(r->pool, "GET");
        r->method_number = M_GET;

        ap_internal_redirect_handler(location, r);
        return OK;
    }

    if (!r->header_only) {
        apr_bucket_brigade *bb;
        apr_bucket *b;
        apr_off_t pos = 0;

        rv = apr_file_seek(f, APR_CUR, &pos);
        if (rv != APR_SUCCESS) {
            ap_log_rerror(APLOG_MARK, APLOG_ERR, rv, r,
                          "mod_asis: failed to find end-of-headers position "
                          "for %s", r->filename);
            apr_file_close(f);
            return HTTP_INTERNAL_SERVER_ERROR;
        }

        bb = apr_brigade_create(r->pool, c->bucket_alloc);
#if APR_HAS_LARGE_FILES
        if (r->finfo.size - pos > AP_MAX_SENDFILE) {
            /* APR_HAS_LARGE_FILES issue; must split into mutiple buckets,
             * no greater than MAX(apr_size_t), and more granular than that
             * in case the brigade code/filters attempt to read it directly.
             */
            apr_off_t fsize = r->finfo.size - pos;
            b = apr_bucket_file_create(f, pos, AP_MAX_SENDFILE,
                                       r->pool, c->bucket_alloc);
            while (fsize > AP_MAX_SENDFILE) {
                APR_BRIGADE_INSERT_TAIL(bb, b);
                apr_bucket_copy(b, &b);
                b->start += AP_MAX_SENDFILE;
                fsize -= AP_MAX_SENDFILE;
            }
            b->length = (apr_size_t)fsize; /* Resize just the last bucket */
        }
        else
#endif
        b = apr_bucket_file_create(f, pos, (apr_size_t) (r->finfo.size - pos),
                                   r->pool, c->bucket_alloc);
        APR_BRIGADE_INSERT_TAIL(bb, b);
        b = apr_bucket_eos_create(c->bucket_alloc);
        APR_BRIGADE_INSERT_TAIL(bb, b);
        rv = ap_pass_brigade(r->output_filters, bb);
        if (rv != APR_SUCCESS) {
            ap_log_rerror(APLOG_MARK, APLOG_ERR, rv, r,
                          "mod_asis: ap_pass_brigade failed for file %s", r->filename);
            return HTTP_INTERNAL_SERVER_ERROR;
        }
    }
    else {
        apr_file_close(f);
    }

    return OK;
}

static void register_hooks(apr_pool_t *p)
{
    ap_hook_handler(asis_handler,NULL,NULL,APR_HOOK_MIDDLE);
}

module AP_MODULE_DECLARE_DATA asis_module =
{
    STANDARD20_MODULE_STUFF,
    NULL,              /* create per-directory config structure */
    NULL,              /* merge per-directory config structures */
    NULL,              /* create per-server config structure */
    NULL,              /* merge per-server config structures */
    NULL,              /* command apr_table_t */
    register_hooks     /* register hooks */
};