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Diffstat (limited to 'server/connection.c')
| -rw-r--r-- | server/connection.c | 219 |
1 files changed, 219 insertions, 0 deletions
diff --git a/server/connection.c b/server/connection.c new file mode 100644 index 0000000..bbc94c4 --- /dev/null +++ b/server/connection.c @@ -0,0 +1,219 @@ +/* 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) +) +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) + +/* + * 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); + } +} |