connection.c revision 943016cae7a40f689cc0b65fd8cf8d4250a21352
7bb9ba8688ec1ca930d693eea05e936bc38f6d1bSumit Bose/* Licensed to the Apache Software Foundation (ASF) under one or more
7bb9ba8688ec1ca930d693eea05e936bc38f6d1bSumit Bose * contributor license agreements. See the NOTICE file distributed with
7bb9ba8688ec1ca930d693eea05e936bc38f6d1bSumit Bose * this work for additional information regarding copyright ownership.
7bb9ba8688ec1ca930d693eea05e936bc38f6d1bSumit Bose * The ASF licenses this file to You under the Apache License, Version 2.0
7bb9ba8688ec1ca930d693eea05e936bc38f6d1bSumit Bose * (the "License"); you may not use this file except in compliance with
7bb9ba8688ec1ca930d693eea05e936bc38f6d1bSumit Bose * the License. You may obtain a copy of the License at
7bb9ba8688ec1ca930d693eea05e936bc38f6d1bSumit Bose *
7bb9ba8688ec1ca930d693eea05e936bc38f6d1bSumit Bose * 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)
)
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)
/*
* 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(void) ap_flush_conn(conn_rec *c)
{
apr_bucket_brigade *bb;
apr_bucket *b;
bb = apr_brigade_create(c->pool, c->bucket_alloc);
/* 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);
ap_pass_brigade(c->output_filters, bb);
}
/* 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://www.ics.uci.edu/pub/ietf/http/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);
if (!csd) {
return 1;
}
if (c->sbh) {
ap_update_child_status(c->sbh, SERVER_CLOSING, NULL);
}
#ifdef NO_LINGCLOSE
ap_flush_conn(c); /* just close it */
apr_socket_close(csd);
return 1;
#endif
/* 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);
if (c->aborted) {
apr_socket_close(csd);
return 1;
}
/* Shut down the socket for write, which will send a FIN
* to the peer.
*/
if (apr_socket_shutdown(csd, APR_SHUTDOWN_WRITE) != APR_SUCCESS
|| c->aborted) {
apr_socket_close(csd);
return 1;
}
return 0;
}
AP_DECLARE(void) ap_lingering_close(conn_rec *c)
{
char dummybuf[512];
apr_size_t nbytes;
apr_time_t timeup = 0;
apr_socket_t *csd = ap_get_conn_socket(c);
if (ap_start_lingering_close(c)) {
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;
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 = apr_time_now() + apr_time_from_sec(SECONDS_TO_LINGER);
}
else {
timeup = apr_time_now() + apr_time_from_sec(MAX_SECS_TO_LINGER);
}
continue;
}
} while (apr_time_now() < timeup);
apr_socket_close(csd);
return;
}
AP_CORE_DECLARE(void) ap_process_connection(conn_rec *c, void *csd)
{
int rc;
ap_update_vhost_given_ip(c);
rc = ap_run_pre_connection(c, csd);
if (rc != OK && rc != DONE) {
c->aborted = 1;
}
if (!c->aborted) {
ap_run_process_connection(c);
}
}