/* 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.h"

#include "apr_strings.h"

#include "ap_config.h"

#include "httpd.h"

#include "http_connection.h"

#include "http_request.h"

#include "http_protocol.h"

#include "ap_mpm.h"

#include "http_config.h"

#include "http_core.h"

#include "http_vhost.h"

#include "scoreboard.h"

#include "http_log.h"

#include "util_filter.h"

APR_HOOK_STRUCT(

            APR_HOOK_LINK(create_connection)

            APR_HOOK_LINK(process_connection)

            APR_HOOK_LINK(pre_connection)

            APR_HOOK_LINK(pre_close_connection)

            APR_HOOK_LINK(create_secondary_connection)

)

AP_IMPLEMENT_HOOK_RUN_FIRST(conn_rec *,create_connection,

                            (apr_pool_t *p, server_rec *server, apr_socket_t *csd, long conn_id, void *sbh, apr_bucket_alloc_t *alloc),

                            (p, server, csd, conn_id, sbh, alloc), NULL)

AP_IMPLEMENT_HOOK_RUN_FIRST(int,process_connection,(conn_rec *c),(c),DECLINED)

AP_IMPLEMENT_HOOK_RUN_ALL(int,pre_connection,(conn_rec *c, void *csd),(c, csd),OK,DECLINED)

AP_IMPLEMENT_HOOK_RUN_ALL(int,pre_close_connection,(conn_rec *c),(c),OK,DECLINED)

AP_IMPLEMENT_HOOK_RUN_FIRST(conn_rec *,create_secondary_connection,

                            (apr_pool_t *p, conn_rec *master, apr_bucket_alloc_t *alloc),

                            (p, master, alloc), NULL)

AP_DECLARE(conn_rec *) ap_create_connection(apr_pool_t *p,

                                            server_rec *server,

                                            apr_socket_t *csd,

                                            long conn_id, void *sbh,

                                            apr_bucket_alloc_t *alloc,

                                            unsigned int outgoing)

{

    conn_rec *c;

    /* Some day it may be flags, so deny anything but 0 or 1 for now */

    if (outgoing > 1) {

        return NULL;

    }

    c = ap_run_create_connection(p, server, csd, conn_id, sbh, alloc);

    if (c && outgoing) {

        c->outgoing = 1;

    }

    return c;

}

AP_DECLARE(conn_rec *) ap_create_secondary_connection(apr_pool_t *p,

                                                      conn_rec *master,

                                                      apr_bucket_alloc_t *alloc)

{

    return ap_run_create_secondary_connection(p, master, alloc);

}

/*

 * More machine-dependent networking gooo... on some systems,

 * you've got to be *really* sure that all the packets are acknowledged

 * before closing the connection, since the client will not be able

 * to see the last response if their TCP buffer is flushed by a RST

 * packet from us, which is what the server's TCP stack will send

 * if it receives any request data after closing the connection.

 *

 * In an ideal world, this function would be accomplished by simply

 * setting the socket option SO_LINGER and handling it within the

 * server's TCP stack while the process continues on to the next request.

 * Unfortunately, it seems that most (if not all) operating systems

 * block the server process on close() when SO_LINGER is used.

 * For those that don't, see USE_SO_LINGER below.  For the rest,

 * we have created a home-brew lingering_close.

 *

 * Many operating systems tend to block, puke, or otherwise mishandle

 * calls to shutdown only half of the connection.  You should define

 * NO_LINGCLOSE in ap_config.h if such is the case for your system.

 */

#ifndef MAX_SECS_TO_LINGER

#define MAX_SECS_TO_LINGER 30

#endif

AP_CORE_DECLARE(apr_status_t) ap_shutdown_conn(conn_rec *c, int flush)

{

    apr_status_t rv;

    apr_bucket_brigade *bb;

    apr_bucket *b;

    bb = apr_brigade_create(c->pool, c->bucket_alloc);

    if (flush) {

        /* FLUSH bucket */

        b = apr_bucket_flush_create(c->bucket_alloc);

        APR_BRIGADE_INSERT_TAIL(bb, b);

    }

    /* End Of Connection bucket */

    b = ap_bucket_eoc_create(c->bucket_alloc);

    APR_BRIGADE_INSERT_TAIL(bb, b);

    rv = ap_pass_brigade(c->output_filters, bb);

    apr_brigade_destroy(bb);

    return rv;

}

AP_CORE_DECLARE(void) ap_flush_conn(conn_rec *c)

{

    (void)ap_shutdown_conn(c, 1);

}

AP_DECLARE(int) ap_prep_lingering_close(conn_rec *c)

{

    /* Give protocol handlers one last chance to raise their voice */

    ap_run_pre_close_connection(c);

    if (c->sbh) {

        ap_update_child_status(c->sbh, SERVER_CLOSING, NULL);

    }

    return 0;

}

/* we now proceed to read from the client until we get EOF, or until

 * MAX_SECS_TO_LINGER has passed.  The reasons for doing this are

 * documented in a draft:

 *

 * http://tools.ietf.org/html/draft-ietf-http-connection-00.txt

 *

 * in a nutshell -- if we don't make this effort we risk causing

 * TCP RST packets to be sent which can tear down a connection before

 * all the response data has been sent to the client.

 */

#define SECONDS_TO_LINGER  2

AP_DECLARE(int) ap_start_lingering_close(conn_rec *c)

{

    apr_socket_t *csd = ap_get_conn_socket(c);

    ap_assert(csd != NULL);

    if (ap_prep_lingering_close(c)) {

        return 1;

    }

    /* Close the connection, being careful to send out whatever is still

     * in our buffers.  If possible, try to avoid a hard close until the

     * client has ACKed our FIN and/or has stopped sending us data.

     */

    /* Send any leftover data to the client, but never try to again */

    ap_flush_conn(c);

#ifdef NO_LINGCLOSE

    return 1;

#else

    /* Shut down the socket for write, which will send a FIN

     * to the peer.

     */

    return (c->aborted || apr_socket_shutdown(csd, APR_SHUTDOWN_WRITE));

#endif

}

AP_DECLARE(void) ap_lingering_close(conn_rec *c)

{

    char dummybuf[512];

    apr_size_t nbytes;

    apr_time_t now, timeup = 0;

    apr_socket_t *csd = ap_get_conn_socket(c);

    if (!csd) {

        /* Be safe with third-party modules that:

         *   ap_set_core_module_config(c->conn_config, NULL)

         * to no-op ap_lingering_close().

         */

        c->aborted = 1;

        return;

    }

    if (ap_start_lingering_close(c)) {

        apr_socket_close(csd);

        return;

    }

    /* Read available data from the client whilst it continues sending

     * it, for a maximum time of MAX_SECS_TO_LINGER.  If the client

     * does not send any data within 2 seconds (a value pulled from

     * Apache 1.3 which seems to work well), give up.

     */

    apr_socket_timeout_set(csd, apr_time_from_sec(SECONDS_TO_LINGER));

    apr_socket_opt_set(csd, APR_INCOMPLETE_READ, 1);

    /* The common path here is that the initial apr_socket_recv() call

     * will return 0 bytes read; so that case must avoid the expensive

     * apr_time_now() call and time arithmetic. */

    do {

        nbytes = sizeof(dummybuf);

        if (apr_socket_recv(csd, dummybuf, &nbytes) || nbytes == 0)

            break;

        now = apr_time_now();

        if (timeup == 0) {

            /*

             * First time through;

             * calculate now + 30 seconds (MAX_SECS_TO_LINGER).

             *

             * If some module requested a shortened waiting period, only wait for

             * 2s (SECONDS_TO_LINGER). This is useful for mitigating certain

             * DoS attacks.

             */

            if (apr_table_get(c->notes, "short-lingering-close")) {

                timeup = now + apr_time_from_sec(SECONDS_TO_LINGER);

            }

            else {

                timeup = now + apr_time_from_sec(MAX_SECS_TO_LINGER);

            }

            continue;

        }

    } while (now < timeup);

    apr_socket_close(csd);

}

AP_CORE_DECLARE(void) ap_process_connection(conn_rec *c, void *csd)

{

    ap_update_vhost_given_ip(c);

    ap_pre_connection(c, csd);

    if (!c->aborted) {

        ap_run_process_connection(c);

    }

}