http_request.c

/* 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.
 */

/*
 * http_request.c: functions to get and process requests
 *
 * Rob McCool 3/21/93
 *
 * Thoroughly revamped by rst for Apache.  NB this file reads
 * best from the bottom up.
 *
 */

#include "apr_strings.h"
#include "apr_file_io.h"
#include "apr_fnmatch.h"

#define APR_WANT_STRFUNC
#include "apr_want.h"

#include "ap_config.h"
#include "httpd.h"
#include "http_config.h"
#include "http_request.h"
#include "http_core.h"
#include "http_protocol.h"
#include "http_log.h"
#include "http_main.h"
#include "util_filter.h"
#include "util_charset.h"
#include "scoreboard.h"

#include "mod_core.h"

#if APR_HAVE_STDARG_H
#include <stdarg.h>
#endif

/*****************************************************************
 *
 * Mainline request processing...
 */

/* XXX A cleaner and faster way to do this might be to pass the request_rec
 * down the filter chain as a parameter.  It would need to change for
 * subrequest vs. main request filters; perhaps the subrequest filter could
 * make the switch.
 */
static void update_r_in_filters(ap_filter_t *f,
                                request_rec *from,
                                request_rec *to)
{
    while (f) {
        if (f->r == from) {
            f->r = to;
        }
        f = f->next;
    }
}

AP_DECLARE(void) ap_die(int type, request_rec *r)
{
    int error_index = ap_index_of_response(type);
    char *custom_response = ap_response_code_string(r, error_index);
    int recursive_error = 0;
    request_rec *r_1st_err = r;

    if (type == AP_FILTER_ERROR) {
        ap_filter_t *next;

        /*
         * Check if we still have the ap_http_header_filter in place. If
         * this is the case we should not ignore AP_FILTER_ERROR here because
         * it means that we have not sent any response at all and never
         * will. This is bad. Sent an internal server error instead.
         */
        next = r->output_filters;
        while (next && (next->frec != ap_http_header_filter_handle)) {
               next = next->next;
        }

        /*
         * If next != NULL then we left the while above because of
         * next->frec == ap_http_header_filter
         */
        if (next) {
            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                          "Custom error page caused AP_FILTER_ERROR");
            type = HTTP_INTERNAL_SERVER_ERROR;
        }
        else {
            return;
        }
    }

    if (type == DONE) {
        ap_finalize_request_protocol(r);
        return;
    }

    /*
     * The following takes care of Apache redirects to custom response URLs
     * Note that if we are already dealing with the response to some other
     * error condition, we just report on the original error, and give up on
     * any attempt to handle the other thing "intelligently"...
     */
    if (r->status != HTTP_OK) {
        recursive_error = type;

        while (r_1st_err->prev && (r_1st_err->prev->status != HTTP_OK))
            r_1st_err = r_1st_err->prev;  /* Get back to original error */

        if (r_1st_err != r) {
            /* The recursive error was caused by an ErrorDocument specifying
             * an internal redirect to a bad URI.  ap_internal_redirect has
             * changed the filter chains to point to the ErrorDocument's
             * request_rec.  Back out those changes so we can safely use the
             * original failing request_rec to send the canned error message.
             *
             * ap_send_error_response gets rid of existing resource filters
             * on the output side, so we can skip those.
             */
            update_r_in_filters(r_1st_err->proto_output_filters, r, r_1st_err);
            update_r_in_filters(r_1st_err->input_filters, r, r_1st_err);
        }

        custom_response = NULL; /* Do NOT retry the custom thing! */
    }

    r->status = type;

    /*
     * This test is done here so that none of the auth modules needs to know
     * about proxy authentication.  They treat it like normal auth, and then
     * we tweak the status.
     */
    if (HTTP_UNAUTHORIZED == r->status && PROXYREQ_PROXY == r->proxyreq) {
        r->status = HTTP_PROXY_AUTHENTICATION_REQUIRED;
    }

    /* If we don't want to keep the connection, make sure we mark that the
     * connection is not eligible for keepalive.  If we want to keep the
     * connection, be sure that the request body (if any) has been read.
     */
    if (ap_status_drops_connection(r->status)) {
        r->connection->keepalive = AP_CONN_CLOSE;
    }

    /*
     * Two types of custom redirects --- plain text, and URLs. Plain text has
     * a leading '"', so the URL code, here, is triggered on its absence
     */

    if (custom_response && custom_response[0] != '"') {

        if (ap_is_url(custom_response)) {
            /*
             * The URL isn't local, so lets drop through the rest of this
             * apache code, and continue with the usual REDIRECT handler.
             * But note that the client will ultimately see the wrong
             * status...
             */
            r->status = HTTP_MOVED_TEMPORARILY;
            apr_table_setn(r->headers_out, "Location", custom_response);
        }
        else if (custom_response[0] == '/') {
            const char *error_notes;
            r->no_local_copy = 1;       /* Do NOT send HTTP_NOT_MODIFIED for
                                         * error documents! */
            /*
             * This redirect needs to be a GET no matter what the original
             * method was.
             */
            apr_table_setn(r->subprocess_env, "REQUEST_METHOD", r->method);

            /*
             * Provide a special method for modules to communicate
             * more informative (than the plain canned) messages to us.
             * Propagate them to ErrorDocuments via the ERROR_NOTES variable:
             */
            if ((error_notes = apr_table_get(r->notes,
                                             "error-notes")) != NULL) {
                apr_table_setn(r->subprocess_env, "ERROR_NOTES", error_notes);
            }
            r->method = apr_pstrdup(r->pool, "GET");
            r->method_number = M_GET;
            ap_internal_redirect(custom_response, r);
            return;
        }
        else {
            /*
             * Dumb user has given us a bad url to redirect to --- fake up
             * dying with a recursive server error...
             */
            recursive_error = HTTP_INTERNAL_SERVER_ERROR;
            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                        "Invalid error redirection directive: %s",
                        custom_response);
        }
    }
    ap_send_error_response(r_1st_err, recursive_error);
}

static void check_pipeline(conn_rec *c)
{
    if (c->keepalive != AP_CONN_CLOSE) {
        apr_status_t rv;
        apr_bucket_brigade *bb = apr_brigade_create(c->pool, c->bucket_alloc);

        rv = ap_get_brigade(c->input_filters, bb, AP_MODE_SPECULATIVE,
                            APR_NONBLOCK_READ, 1);
        if (rv != APR_SUCCESS || APR_BRIGADE_EMPTY(bb)) {
            /*
             * Error or empty brigade: There is no data present in the input
             * filter
             */
            c->data_in_input_filters = 0;
        }
        else {
            c->data_in_input_filters = 1;
        }
        apr_brigade_destroy(bb);
    }
}


void ap_process_request_after_handler(request_rec *r)
{
    apr_bucket_brigade *bb;
    apr_bucket *b;
    conn_rec *c = r->connection;

    /* Send an EOR bucket through the output filter chain.  When
     * this bucket is destroyed, the request will be logged and
     * its pool will be freed
     */
    bb = apr_brigade_create(r->connection->pool, r->connection->bucket_alloc);
    b = ap_bucket_eor_create(r->connection->bucket_alloc, r);
    APR_BRIGADE_INSERT_HEAD(bb, b);
    
    ap_pass_brigade(r->connection->output_filters, bb);
    
    /* From here onward, it is no longer safe to reference r
     * or r->pool, because r->pool may have been destroyed
     * already by the EOR bucket's cleanup function.
     */
    
    c->cs->state = CONN_STATE_WRITE_COMPLETION;
    check_pipeline(c);
    AP_PROCESS_REQUEST_RETURN((uintptr_t)r, r->uri, r->status);
    if (ap_extended_status) {
        ap_time_process_request(c->sbh, STOP_PREQUEST);
    }
}

void ap_process_async_request(request_rec *r)
{
    conn_rec *c = r->connection;
    int access_status;

    /* Give quick handlers a shot at serving the request on the fast
     * path, bypassing all of the other Apache hooks.
     *
     * This hook was added to enable serving files out of a URI keyed
     * content cache ( e.g., Mike Abbott's Quick Shortcut Cache,
     * described here: http://oss.sgi.com/projects/apache/mod_qsc.html )
     *
     * It may have other uses as well, such as routing requests directly to
     * content handlers that have the ability to grok HTTP and do their
     * own access checking, etc (e.g. servlet engines).
     *
     * Use this hook with extreme care and only if you know what you are
     * doing.
     */
    AP_PROCESS_REQUEST_ENTRY((uintptr_t)r, r->uri);
    if (ap_extended_status) {
        ap_time_process_request(r->connection->sbh, START_PREQUEST);
    }

    apr_thread_mutex_create(&r->invoke_mtx, APR_THREAD_MUTEX_DEFAULT, r->pool);
    apr_thread_mutex_lock(r->invoke_mtx);
    access_status = ap_run_quick_handler(r, 0);  /* Not a look-up request */
    if (access_status == DECLINED) {
        access_status = ap_process_request_internal(r);
        if (access_status == OK) {
            access_status = ap_invoke_handler(r);
        }
    }

    if (access_status == SUSPENDED) {
        /* TODO: Should move these steps into a generic function, so modules
         * working on a suspended request can also call _ENTRY again.
         */
        AP_PROCESS_REQUEST_RETURN((uintptr_t)r, r->uri, access_status);
        if (ap_extended_status) {
            ap_time_process_request(c->sbh, STOP_PREQUEST);
        }
        c->cs->state = CONN_STATE_SUSPENDED;
        apr_thread_mutex_unlock(r->invoke_mtx);
        return;
    }
    apr_thread_mutex_unlock(r->invoke_mtx);

    if (access_status == DONE) {
        /* e.g., something not in storage like TRACE */
        access_status = OK;
    }

    if (access_status == OK) {
        ap_finalize_request_protocol(r);
    }
    else {
        r->status = HTTP_OK;
        ap_die(access_status, r);
    }

    ap_process_request_after_handler(r);
}

void ap_process_request(request_rec *r)
{
    apr_bucket_brigade *bb;
    apr_bucket *b;
    conn_rec *c = r->connection;
    apr_status_t rv;

    ap_process_async_request(r);

    if (!c->data_in_input_filters) {
        bb = apr_brigade_create(c->pool, c->bucket_alloc);
        b = apr_bucket_flush_create(c->bucket_alloc);
        APR_BRIGADE_INSERT_HEAD(bb, b);
        rv = ap_pass_brigade(c->output_filters, bb);
        if (APR_STATUS_IS_TIMEUP(rv)) {
            /*
             * Notice a timeout as an error message. This might be
             * valuable for detecting clients with broken network
             * connections or possible DoS attacks.
             *
             * It is still save to use r / r->pool here as the eor bucket
             * could not have been destroyed in the event of a timeout.
             */
            ap_log_rerror(APLOG_MARK, APLOG_ERR, rv, r,
                          "Timeout while writing data for URI %s to the"
                          " client", r->unparsed_uri);
        }
    }
    if (ap_extended_status) {
        ap_time_process_request(c->sbh, STOP_PREQUEST);
    }
}

static apr_table_t *rename_original_env(apr_pool_t *p, apr_table_t *t)
{
    const apr_array_header_t *env_arr = apr_table_elts(t);
    const apr_table_entry_t *elts = (const apr_table_entry_t *) env_arr->elts;
    apr_table_t *new = apr_table_make(p, env_arr->nalloc);
    int i;

    for (i = 0; i < env_arr->nelts; ++i) {
        if (!elts[i].key)
            continue;
        apr_table_setn(new, apr_pstrcat(p, "REDIRECT_", elts[i].key, NULL),
                  elts[i].val);
    }

    return new;
}

static request_rec *internal_internal_redirect(const char *new_uri,
                                               request_rec *r) {
    int access_status;
    request_rec *new;

    if (ap_is_recursion_limit_exceeded(r)) {
        ap_die(HTTP_INTERNAL_SERVER_ERROR, r);
        return NULL;
    }

    new = (request_rec *) apr_pcalloc(r->pool, sizeof(request_rec));

    new->connection = r->connection;
    new->server     = r->server;
    new->pool       = r->pool;

    /*
     * A whole lot of this really ought to be shared with http_protocol.c...
     * another missing cleanup.  It's particularly inappropriate to be
     * setting header_only, etc., here.
     */

    new->method          = r->method;
    new->method_number   = r->method_number;
    new->allowed_methods = ap_make_method_list(new->pool, 2);
    ap_parse_uri(new, new_uri);

    new->request_config = ap_create_request_config(r->pool);

    new->per_dir_config = r->server->lookup_defaults;

    new->prev = r;
    r->next   = new;

    /* Must have prev and next pointers set before calling create_request
     * hook.
     */
    ap_run_create_request(new);

    /* Inherit the rest of the protocol info... */

    new->the_request = r->the_request;

    new->allowed         = r->allowed;

    new->status          = r->status;
    new->assbackwards    = r->assbackwards;
    new->header_only     = r->header_only;
    new->protocol        = r->protocol;
    new->proto_num       = r->proto_num;
    new->hostname        = r->hostname;
    new->request_time    = r->request_time;
    new->main            = r->main;

    new->headers_in      = r->headers_in;
    new->headers_out     = apr_table_make(r->pool, 12);
    new->err_headers_out = r->err_headers_out;
    new->subprocess_env  = rename_original_env(r->pool, r->subprocess_env);
    new->notes           = apr_table_make(r->pool, 5);
    new->allowed_methods = ap_make_method_list(new->pool, 2);

    new->htaccess        = r->htaccess;
    new->no_cache        = r->no_cache;
    new->expecting_100   = r->expecting_100;
    new->no_local_copy   = r->no_local_copy;
    new->read_length     = r->read_length;     /* We can only read it once */
    new->vlist_validator = r->vlist_validator;

    new->proto_output_filters  = r->proto_output_filters;
    new->proto_input_filters   = r->proto_input_filters;

    new->output_filters  = new->proto_output_filters;
    new->input_filters   = new->proto_input_filters;

    if (new->main) {
        /* Add back the subrequest filter, which we lost when
         * we set output_filters to include only the protocol
         * output filters from the original request.
         */
        ap_add_output_filter_handle(ap_subreq_core_filter_handle,
                                    NULL, new, new->connection);
    }

    update_r_in_filters(new->input_filters, r, new);
    update_r_in_filters(new->output_filters, r, new);

    apr_table_setn(new->subprocess_env, "REDIRECT_STATUS",
                   apr_itoa(r->pool, r->status));

    /*
     * XXX: hmm.  This is because mod_setenvif and mod_unique_id really need
     * to do their thing on internal redirects as well.  Perhaps this is a
     * misnamed function.
     */
    if ((access_status = ap_run_post_read_request(new))) {
        ap_die(access_status, new);
        return NULL;
    }

    return new;
}

/* XXX: Is this function is so bogus and fragile that we deep-6 it? */
AP_DECLARE(void) ap_internal_fast_redirect(request_rec *rr, request_rec *r)
{
    /* We need to tell POOL_DEBUG that we're guaranteeing that rr->pool
     * will exist as long as r->pool.  Otherwise we run into troubles because
     * some values in this request will be allocated in r->pool, and others in
     * rr->pool.
     */
    apr_pool_join(r->pool, rr->pool);
    r->proxyreq = rr->proxyreq;
    r->no_cache = (r->no_cache && rr->no_cache);
    r->no_local_copy = (r->no_local_copy && rr->no_local_copy);
    r->mtime = rr->mtime;
    r->uri = rr->uri;
    r->filename = rr->filename;
    r->canonical_filename = rr->canonical_filename;
    r->path_info = rr->path_info;
    r->args = rr->args;
    r->finfo = rr->finfo;
    r->handler = rr->handler;
    ap_set_content_type(r, rr->content_type);
    r->content_encoding = rr->content_encoding;
    r->content_languages = rr->content_languages;
    r->per_dir_config = rr->per_dir_config;
    /* copy output headers from subrequest, but leave negotiation headers */
    r->notes = apr_table_overlay(r->pool, rr->notes, r->notes);
    r->headers_out = apr_table_overlay(r->pool, rr->headers_out,
                                       r->headers_out);
    r->err_headers_out = apr_table_overlay(r->pool, rr->err_headers_out,
                                           r->err_headers_out);
    r->subprocess_env = apr_table_overlay(r->pool, rr->subprocess_env,
                                          r->subprocess_env);

    r->output_filters = rr->output_filters;
    r->input_filters = rr->input_filters;

    if (r->main) {
        ap_add_output_filter_handle(ap_subreq_core_filter_handle,
                                    NULL, r, r->connection);
    }
    else if (r->output_filters->frec == ap_subreq_core_filter_handle) {
        ap_remove_output_filter(r->output_filters);
        r->output_filters = r->output_filters->next;
    }

    /* If any filters pointed at the now-defunct rr, we must point them
     * at our "new" instance of r.  In particular, some of rr's structures
     * will now be bogus (say rr->headers_out).  If a filter tried to modify
     * their f->r structure when it is pointing to rr, the real request_rec
     * will not get updated.  Fix that here.
     */
    update_r_in_filters(r->input_filters, rr, r);
    update_r_in_filters(r->output_filters, rr, r);
}

AP_DECLARE(void) ap_internal_redirect(const char *new_uri, request_rec *r)
{
    request_rec *new = internal_internal_redirect(new_uri, r);
    int access_status;

    AP_INTERNAL_REDIRECT(r->uri, new_uri);

    /* ap_die was already called, if an error occured */
    if (!new) {
        return;
    }

    access_status = ap_run_quick_handler(new, 0);  /* Not a look-up request */
    if (access_status == DECLINED) {
        access_status = ap_process_request_internal(new);
        if (access_status == OK) {
            access_status = ap_invoke_handler(new);
        }
    }
    if (access_status == OK) {
        ap_finalize_request_protocol(new);
    }
    else {
        ap_die(access_status, new);
    }
}

/* This function is designed for things like actions or CGI scripts, when
 * using AddHandler, and you want to preserve the content type across
 * an internal redirect.
 */
AP_DECLARE(void) ap_internal_redirect_handler(const char *new_uri, request_rec *r)
{
    int access_status;
    request_rec *new = internal_internal_redirect(new_uri, r);

    /* ap_die was already called, if an error occured */
    if (!new) {
        return;
    }

    if (r->handler)
        ap_set_content_type(new, r->content_type);
    access_status = ap_process_request_internal(new);
    if (access_status == OK) {
        if ((access_status = ap_invoke_handler(new)) != 0) {
            ap_die(access_status, new);
            return;
        }
        ap_finalize_request_protocol(new);
    }
    else {
        ap_die(access_status, new);
    }
}

AP_DECLARE(void) ap_allow_methods(request_rec *r, int reset, ...)
{
    const char *method;
    va_list methods;

    /*
     * Get rid of any current settings if requested; not just the
     * well-known methods but any extensions as well.
     */
    if (reset) {
        ap_clear_method_list(r->allowed_methods);
    }

    va_start(methods, reset);
    while ((method = va_arg(methods, const char *)) != NULL) {
        ap_method_list_add(r->allowed_methods, method);
    }
    va_end(methods);
}

AP_DECLARE(void) ap_allow_standard_methods(request_rec *r, int reset, ...)
{
    int method;
    va_list methods;
    apr_int64_t mask;

    /*
     * Get rid of any current settings if requested; not just the
     * well-known methods but any extensions as well.
     */
    if (reset) {
        ap_clear_method_list(r->allowed_methods);
    }

    mask = 0;
    va_start(methods, reset);
    while ((method = va_arg(methods, int)) != -1) {
        mask |= (AP_METHOD_BIT << method);
    }
    va_end(methods);

    r->allowed_methods->method_mask |= mask;
}