http_protocol.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_protocol.c --- routines which directly communicate with the client.
 *
 * Code originally by Rob McCool; much redone by Robert S. Thau
 * and the Apache Software Foundation.
 */

#include "apr.h"
#include "apr_strings.h"
#include "apr_buckets.h"
#include "apr_lib.h"
#include "apr_signal.h"

#define APR_WANT_STDIO          /* for sscanf */
#define APR_WANT_STRFUNC
#define APR_WANT_MEMFUNC
#include "apr_want.h"

#include "util_filter.h"
#include "ap_config.h"
#include "httpd.h"
#include "http_config.h"
#include "http_core.h"
#include "http_protocol.h"
#include "http_main.h"
#include "http_request.h"
#include "http_vhost.h"
#include "http_log.h"           /* For errors detected in basic auth common
                                 * support code... */
#include "apr_date.h"           /* For apr_date_parse_http and APR_DATE_BAD */
#include "util_charset.h"
#include "util_ebcdic.h"
#include "util_time.h"
#include "ap_mpm.h"

#include "mod_core.h"

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

APLOG_USE_MODULE(http);

/* New Apache routine to map status codes into array indicies
 *  e.g.  100 -> 0,  101 -> 1,  200 -> 2 ...
 * The number of status lines must equal the value of
 * RESPONSE_CODES (httpd.h) and must be listed in order.
 * No gaps are allowed between X00 and the largest Xnn
 * for any X (see ap_index_of_response).
 * When adding a new code here, add a define to httpd.h
 * as well.
 */

static const char * const status_lines[RESPONSE_CODES] =
{
    "100 Continue",
    "101 Switching Protocols",
    "102 Processing",
#define LEVEL_200  3
    "200 OK",
    "201 Created",
    "202 Accepted",
    "203 Non-Authoritative Information",
    "204 No Content",
    "205 Reset Content",
    "206 Partial Content",
    "207 Multi-Status",
    "208 Already Reported",
    NULL, /* 209 */
    NULL, /* 210 */
    NULL, /* 211 */
    NULL, /* 212 */
    NULL, /* 213 */
    NULL, /* 214 */
    NULL, /* 215 */
    NULL, /* 216 */
    NULL, /* 217 */
    NULL, /* 218 */
    NULL, /* 219 */
    NULL, /* 220 */
    NULL, /* 221 */
    NULL, /* 222 */
    NULL, /* 223 */
    NULL, /* 224 */
    NULL, /* 225 */
    "226 IM Used",
#define LEVEL_300 30
    "300 Multiple Choices",
    "301 Moved Permanently",
    "302 Found",
    "303 See Other",
    "304 Not Modified",
    "305 Use Proxy",
    NULL, /* 306 */
    "307 Temporary Redirect",
    "308 Permanent Redirect",
#define LEVEL_400 39
    "400 Bad Request",
    "401 Unauthorized",
    "402 Payment Required",
    "403 Forbidden",
    "404 Not Found",
    "405 Method Not Allowed",
    "406 Not Acceptable",
    "407 Proxy Authentication Required",
    "408 Request Timeout",
    "409 Conflict",
    "410 Gone",
    "411 Length Required",
    "412 Precondition Failed",
    "413 Request Entity Too Large",
    "414 Request-URI Too Long",
    "415 Unsupported Media Type",
    "416 Requested Range Not Satisfiable",
    "417 Expectation Failed",
    NULL, /* 418 */
    NULL, /* 419 */
    NULL, /* 420 */
    "421 Misdirected Request",
    "422 Unprocessable Entity",
    "423 Locked",
    "424 Failed Dependency",
    NULL, /* 425 */
    "426 Upgrade Required",
    NULL, /* 427 */
    "428 Precondition Required",
    "429 Too Many Requests",
    NULL, /* 430 */
    "431 Request Header Fields Too Large",
    NULL, /* 432 */
    NULL, /* 433 */
    NULL, /* 434 */
    NULL, /* 435 */
    NULL, /* 436 */
    NULL, /* 437 */
    NULL, /* 438 */
    NULL, /* 439 */
    NULL, /* 440 */
    NULL, /* 441 */
    NULL, /* 442 */
    NULL, /* 443 */
    NULL, /* 444 */
    NULL, /* 445 */
    NULL, /* 446 */
    NULL, /* 447 */
    NULL, /* 448 */
    NULL, /* 449 */
    NULL, /* 450 */
    "451 Unavailable For Legal Reasons",
#define LEVEL_500 91
    "500 Internal Server Error",
    "501 Not Implemented",
    "502 Bad Gateway",
    "503 Service Unavailable",
    "504 Gateway Timeout",
    "505 HTTP Version Not Supported",
    "506 Variant Also Negotiates",
    "507 Insufficient Storage",
    "508 Loop Detected",
    NULL, /* 509 */
    "510 Not Extended",
    "511 Network Authentication Required"
};

APR_HOOK_STRUCT(
    APR_HOOK_LINK(insert_error_filter)
)

AP_IMPLEMENT_HOOK_VOID(insert_error_filter, (request_rec *r), (r))

/* The index of the first bit field that is used to index into a limit
 * bitmask. M_INVALID + 1 to METHOD_NUMBER_LAST.
 */
#define METHOD_NUMBER_FIRST (M_INVALID + 1)

/* The max method number. Method numbers are used to shift bitmasks,
 * so this cannot exceed 63, and all bits high is equal to -1, which is a
 * special flag, so the last bit used has index 62.
 */
#define METHOD_NUMBER_LAST  62

static int is_mpm_running(void)
{
    int mpm_state = 0;

    if (ap_mpm_query(AP_MPMQ_MPM_STATE, &mpm_state)) {
      return 0;
    }

    if (mpm_state == AP_MPMQ_STOPPING) {
      return 0;
    }

    return 1;
}


AP_DECLARE(int) ap_set_keepalive(request_rec *r)
{
    int ka_sent = 0;
    int left = r->server->keep_alive_max - r->connection->keepalives;
    int wimpy = ap_find_token(r->pool,
                              apr_table_get(r->headers_out, "Connection"),
                              "close");
    const char *conn = apr_table_get(r->headers_in, "Connection");

    /* The following convoluted conditional determines whether or not
     * the current connection should remain persistent after this response
     * (a.k.a. HTTP Keep-Alive) and whether or not the output message
     * body should use the HTTP/1.1 chunked transfer-coding.  In English,
     *
     *   IF  we have not marked this connection as errored;
     *   and the client isn't expecting 100-continue (PR47087 - more
     *       input here could be the client continuing when we're
     *       closing the request).
     *   and the response body has a defined length due to the status code
     *       being 304 or 204, the request method being HEAD, already
     *       having defined Content-Length or Transfer-Encoding: chunked, or
     *       the request version being HTTP/1.1 and thus capable of being set
     *       as chunked [we know the (r->chunked = 1) side-effect is ugly];
     *   and the server configuration enables keep-alive;
     *   and the server configuration has a reasonable inter-request timeout;
     *   and there is no maximum # requests or the max hasn't been reached;
     *   and the response status does not require a close;
     *   and the response generator has not already indicated close;
     *   and the client did not request non-persistence (Connection: close);
     *   and    we haven't been configured to ignore the buggy twit
     *       or they're a buggy twit coming through a HTTP/1.1 proxy
     *   and    the client is requesting an HTTP/1.0-style keep-alive
     *       or the client claims to be HTTP/1.1 compliant (perhaps a proxy);
     *   and this MPM process is not already exiting
     *   THEN we can be persistent, which requires more headers be output.
     *
     * Note that the condition evaluation order is extremely important.
     */
    if ((r->connection->keepalive != AP_CONN_CLOSE)
        && !r->expecting_100
        && ((r->status == HTTP_NOT_MODIFIED)
            || (r->status == HTTP_NO_CONTENT)
            || r->header_only
            || apr_table_get(r->headers_out, "Content-Length")
            || ap_find_last_token(r->pool,
                                  apr_table_get(r->headers_out,
                                                "Transfer-Encoding"),
                                  "chunked")
            || ((r->proto_num >= HTTP_VERSION(1,1))
                && (r->chunked = 1))) /* THIS CODE IS CORRECT, see above. */
        && r->server->keep_alive
        && (r->server->keep_alive_timeout > 0)
        && ((r->server->keep_alive_max == 0)
            || (left > 0))
        && !ap_status_drops_connection(r->status)
        && !wimpy
        && !ap_find_token(r->pool, conn, "close")
        && (!apr_table_get(r->subprocess_env, "nokeepalive")
            || apr_table_get(r->headers_in, "Via"))
        && ((ka_sent = ap_find_token(r->pool, conn, "keep-alive"))
            || (r->proto_num >= HTTP_VERSION(1,1)))
        && is_mpm_running()) {

        r->connection->keepalive = AP_CONN_KEEPALIVE;
        r->connection->keepalives++;

        /* If they sent a Keep-Alive token, send one back */
        if (ka_sent) {
            if (r->server->keep_alive_max) {
                apr_table_setn(r->headers_out, "Keep-Alive",
                       apr_psprintf(r->pool, "timeout=%d, max=%d",
                            (int)apr_time_sec(r->server->keep_alive_timeout),
                            left));
            }
            else {
                apr_table_setn(r->headers_out, "Keep-Alive",
                      apr_psprintf(r->pool, "timeout=%d",
                            (int)apr_time_sec(r->server->keep_alive_timeout)));
            }
            apr_table_mergen(r->headers_out, "Connection", "Keep-Alive");
        }

        return 1;
    }

    /* Otherwise, we need to indicate that we will be closing this
     * connection immediately after the current response.
     *
     * We only really need to send "close" to HTTP/1.1 clients, but we
     * always send it anyway, because a broken proxy may identify itself
     * as HTTP/1.0, but pass our request along with our HTTP/1.1 tag
     * to a HTTP/1.1 client. Better safe than sorry.
     */
    if (!wimpy) {
        apr_table_mergen(r->headers_out, "Connection", "close");
    }

    /*
     * If we had previously been a keepalive connection and this
     * is the last one, then bump up the number of keepalives
     * we've had
     */
    if ((r->connection->keepalive != AP_CONN_CLOSE)
        && r->server->keep_alive_max
        && !left) {
        r->connection->keepalives++;
    }
    r->connection->keepalive = AP_CONN_CLOSE;

    return 0;
}

AP_DECLARE(ap_condition_e) ap_condition_if_match(request_rec *r,
        apr_table_t *headers)
{
    const char *if_match, *etag;

    /* A server MUST use the strong comparison function (see section 13.3.3)
     * to compare the entity tags in If-Match.
     */
    if ((if_match = apr_table_get(r->headers_in, "If-Match")) != NULL) {
        if (if_match[0] == '*'
                || ((etag = apr_table_get(headers, "ETag")) != NULL
                        && ap_find_etag_strong(r->pool, if_match, etag))) {
            return AP_CONDITION_STRONG;
        }
        else {
            return AP_CONDITION_NOMATCH;
        }
    }

    return AP_CONDITION_NONE;
}

AP_DECLARE(ap_condition_e) ap_condition_if_unmodified_since(request_rec *r,
        apr_table_t *headers)
{
    const char *if_unmodified;

    if_unmodified = apr_table_get(r->headers_in, "If-Unmodified-Since");
    if (if_unmodified) {
        apr_int64_t mtime, reqtime;

        apr_time_t ius = apr_time_sec(apr_date_parse_http(if_unmodified));

        /* All of our comparisons must be in seconds, because that's the
         * highest time resolution the HTTP specification allows.
         */
        mtime = apr_time_sec(apr_date_parse_http(
                        apr_table_get(headers, "Last-Modified")));
        if (mtime == APR_DATE_BAD) {
            mtime = apr_time_sec(r->mtime ? r->mtime : apr_time_now());
        }

        reqtime = apr_time_sec(apr_date_parse_http(
                        apr_table_get(headers, "Date")));
        if (!reqtime) {
            reqtime = apr_time_sec(r->request_time);
        }

        if ((ius != APR_DATE_BAD) && (mtime > ius)) {
            if (reqtime < mtime + 60) {
                if (apr_table_get(r->headers_in, "Range")) {
                    /* weak matches not allowed with Range requests */
                    return AP_CONDITION_NOMATCH;
                }
                else {
                    return AP_CONDITION_WEAK;
                }
            }
            else {
                return AP_CONDITION_STRONG;
            }
        }
        else {
            return AP_CONDITION_NOMATCH;
        }
    }

    return AP_CONDITION_NONE;
}

AP_DECLARE(ap_condition_e) ap_condition_if_none_match(request_rec *r,
        apr_table_t *headers)
{
    const char *if_nonematch, *etag;

    if_nonematch = apr_table_get(r->headers_in, "If-None-Match");
    if (if_nonematch != NULL) {

        if (if_nonematch[0] == '*') {
            return AP_CONDITION_STRONG;
        }

        /* See section 13.3.3 for rules on how to determine if two entities tags
         * match. The weak comparison function can only be used with GET or HEAD
         * requests.
         */
        if (r->method_number == M_GET) {
            if ((etag = apr_table_get(headers, "ETag")) != NULL) {
                if (apr_table_get(r->headers_in, "Range")) {
                    if (ap_find_etag_strong(r->pool, if_nonematch, etag)) {
                        return AP_CONDITION_STRONG;
                    }
                }
                else {
                    if (ap_find_etag_weak(r->pool, if_nonematch, etag)) {
                        return AP_CONDITION_WEAK;
                    }
                }
            }
        }

        else if ((etag = apr_table_get(headers, "ETag")) != NULL
                && ap_find_etag_strong(r->pool, if_nonematch, etag)) {
            return AP_CONDITION_STRONG;
        }
        return AP_CONDITION_NOMATCH;
    }

    return AP_CONDITION_NONE;
}

AP_DECLARE(ap_condition_e) ap_condition_if_modified_since(request_rec *r,
        apr_table_t *headers)
{
    const char *if_modified_since;

    if ((if_modified_since = apr_table_get(r->headers_in, "If-Modified-Since"))
            != NULL) {
        apr_int64_t mtime;
        apr_int64_t ims, reqtime;

        /* All of our comparisons must be in seconds, because that's the
         * highest time resolution the HTTP specification allows.
         */

        mtime = apr_time_sec(apr_date_parse_http(
                        apr_table_get(headers, "Last-Modified")));
        if (mtime == APR_DATE_BAD) {
            mtime = apr_time_sec(r->mtime ? r->mtime : apr_time_now());
        }

        reqtime = apr_time_sec(apr_date_parse_http(
                        apr_table_get(headers, "Date")));
        if (!reqtime) {
            reqtime = apr_time_sec(r->request_time);
        }

        ims = apr_time_sec(apr_date_parse_http(if_modified_since));

        if (ims >= mtime && ims <= reqtime) {
            if (reqtime < mtime + 60) {
                if (apr_table_get(r->headers_in, "Range")) {
                    /* weak matches not allowed with Range requests */
                    return AP_CONDITION_NOMATCH;
                }
                else {
                    return AP_CONDITION_WEAK;
                }
            }
            else {
                return AP_CONDITION_STRONG;
            }
        }
        else {
            return AP_CONDITION_NOMATCH;
        }
    }

    return AP_CONDITION_NONE;
}

AP_DECLARE(ap_condition_e) ap_condition_if_range(request_rec *r,
        apr_table_t *headers)
{
    const char *if_range, *etag;

    if ((if_range = apr_table_get(r->headers_in, "If-Range"))
            && apr_table_get(r->headers_in, "Range")) {
        if (if_range[0] == '"') {

            if ((etag = apr_table_get(headers, "ETag"))
                    && !strcmp(if_range, etag)) {
                return AP_CONDITION_STRONG;
            }
            else {
                return AP_CONDITION_NOMATCH;
            }

        }
        else {
            apr_int64_t mtime;
            apr_int64_t rtime, reqtime;

            /* All of our comparisons must be in seconds, because that's the
             * highest time resolution the HTTP specification allows.
             */

            mtime = apr_time_sec(apr_date_parse_http(
                            apr_table_get(headers, "Last-Modified")));
            if (mtime == APR_DATE_BAD) {
                mtime = apr_time_sec(r->mtime ? r->mtime : apr_time_now());
            }

            reqtime = apr_time_sec(apr_date_parse_http(
                            apr_table_get(headers, "Date")));
            if (!reqtime) {
                reqtime = apr_time_sec(r->request_time);
            }

            rtime = apr_time_sec(apr_date_parse_http(if_range));

            if (rtime == mtime) {
                if (reqtime < mtime + 60) {
                    /* weak matches not allowed with Range requests */
                    return AP_CONDITION_NOMATCH;
                }
                else {
                    return AP_CONDITION_STRONG;
                }
            }
            else {
                return AP_CONDITION_NOMATCH;
            }
        }
    }

    return AP_CONDITION_NONE;
}

AP_DECLARE(int) ap_meets_conditions(request_rec *r)
{
    int not_modified = -1; /* unset by default */
    ap_condition_e cond;

    /* Check for conditional requests --- note that we only want to do
     * this if we are successful so far and we are not processing a
     * subrequest or an ErrorDocument.
     *
     * The order of the checks is important, since ETag checks are supposed
     * to be more accurate than checks relative to the modification time.
     * However, not all documents are guaranteed to *have* ETags, and some
     * might have Last-Modified values w/o ETags, so this gets a little
     * complicated.
     */

    if (!ap_is_HTTP_SUCCESS(r->status) || r->no_local_copy) {
        return OK;
    }

    /* If an If-Match request-header field was given
     * AND the field value is not "*" (meaning match anything)
     * AND if our strong ETag does not match any entity tag in that field,
     *     respond with a status of 412 (Precondition Failed).
     */
    cond = ap_condition_if_match(r, r->headers_out);
    if (AP_CONDITION_NOMATCH == cond) {
        return HTTP_PRECONDITION_FAILED;
    }

    /* Else if a valid If-Unmodified-Since request-header field was given
     * AND the requested resource has been modified since the time
     * specified in this field, then the server MUST
     *     respond with a status of 412 (Precondition Failed).
     */
    cond = ap_condition_if_unmodified_since(r, r->headers_out);
    if (AP_CONDITION_NOMATCH == cond) {
        not_modified = 0;
    }
    else if (cond >= AP_CONDITION_WEAK) {
        return HTTP_PRECONDITION_FAILED;
    }

    /* If an If-None-Match request-header field was given
     * AND the field value is "*" (meaning match anything)
     *     OR our ETag matches any of the entity tags in that field, fail.
     *
     * If the request method was GET or HEAD, failure means the server
     *    SHOULD respond with a 304 (Not Modified) response.
     * For all other request methods, failure means the server MUST
     *    respond with a status of 412 (Precondition Failed).
     *
     * GET or HEAD allow weak etag comparison, all other methods require
     * strong comparison.  We can only use weak if it's not a range request.
     */
    cond = ap_condition_if_none_match(r, r->headers_out);
    if (AP_CONDITION_NOMATCH == cond) {
        not_modified = 0;
    }
    else if (cond >= AP_CONDITION_WEAK) {
        if (r->method_number == M_GET) {
            if (not_modified) {
                not_modified = 1;
            }
        }
        else {
            return HTTP_PRECONDITION_FAILED;
        }
    }

    /* If a valid If-Modified-Since request-header field was given
     * AND it is a GET or HEAD request
     * AND the requested resource has not been modified since the time
     * specified in this field, then the server MUST
     *    respond with a status of 304 (Not Modified).
     * A date later than the server's current request time is invalid.
     */
    cond = ap_condition_if_modified_since(r, r->headers_out);
    if (AP_CONDITION_NOMATCH == cond) {
        not_modified = 0;
    }
    else if (cond >= AP_CONDITION_WEAK) {
        if (r->method_number == M_GET) {
            if (not_modified) {
                not_modified = 1;
            }
        }
    }

    /* If an If-Range and an Range header is present, we must return
     * 200 OK. The byterange filter will convert it to a range response.
     */
    cond = ap_condition_if_range(r, r->headers_out);
    if (cond > AP_CONDITION_NONE) {
        return OK;
    }

    if (not_modified == 1) {
        return HTTP_NOT_MODIFIED;
    }

    return OK;
}

/**
 * Singleton registry of additional methods. This maps new method names
 * such as "MYGET" to methnums, which are int offsets into bitmasks.
 *
 * This follows the same technique as standard M_GET, M_POST, etc. These
 * are dynamically assigned when modules are loaded and <Limit GET MYGET>
 * directives are processed.
 */
static apr_hash_t *methods_registry = NULL;
static int cur_method_number = METHOD_NUMBER_FIRST;

/* internal function to register one method/number pair */
static void register_one_method(apr_pool_t *p, const char *methname,
                                int methnum)
{
    int *pnum = apr_palloc(p, sizeof(*pnum));

    *pnum = methnum;
    apr_hash_set(methods_registry, methname, APR_HASH_KEY_STRING, pnum);
}

/* This internal function is used to clear the method registry
 * and reset the cur_method_number counter.
 */
static apr_status_t ap_method_registry_destroy(void *notused)
{
    methods_registry = NULL;
    cur_method_number = METHOD_NUMBER_FIRST;
    return APR_SUCCESS;
}

AP_DECLARE(void) ap_method_registry_init(apr_pool_t *p)
{
    methods_registry = apr_hash_make(p);
    apr_pool_cleanup_register(p, NULL,
                              ap_method_registry_destroy,
                              apr_pool_cleanup_null);

    /* put all the standard methods into the registry hash to ease the
     * mapping operations between name and number
     * HEAD is a special-instance of the GET method and shares the same ID
     */
    register_one_method(p, "GET", M_GET);
    register_one_method(p, "HEAD", M_GET);
    register_one_method(p, "PUT", M_PUT);
    register_one_method(p, "POST", M_POST);
    register_one_method(p, "DELETE", M_DELETE);
    register_one_method(p, "CONNECT", M_CONNECT);
    register_one_method(p, "OPTIONS", M_OPTIONS);
    register_one_method(p, "TRACE", M_TRACE);
    register_one_method(p, "PATCH", M_PATCH);
    register_one_method(p, "PROPFIND", M_PROPFIND);
    register_one_method(p, "PROPPATCH", M_PROPPATCH);
    register_one_method(p, "MKCOL", M_MKCOL);
    register_one_method(p, "COPY", M_COPY);
    register_one_method(p, "MOVE", M_MOVE);
    register_one_method(p, "LOCK", M_LOCK);
    register_one_method(p, "UNLOCK", M_UNLOCK);
    register_one_method(p, "VERSION-CONTROL", M_VERSION_CONTROL);
    register_one_method(p, "CHECKOUT", M_CHECKOUT);
    register_one_method(p, "UNCHECKOUT", M_UNCHECKOUT);
    register_one_method(p, "CHECKIN", M_CHECKIN);
    register_one_method(p, "UPDATE", M_UPDATE);
    register_one_method(p, "LABEL", M_LABEL);
    register_one_method(p, "REPORT", M_REPORT);
    register_one_method(p, "MKWORKSPACE", M_MKWORKSPACE);
    register_one_method(p, "MKACTIVITY", M_MKACTIVITY);
    register_one_method(p, "BASELINE-CONTROL", M_BASELINE_CONTROL);
    register_one_method(p, "MERGE", M_MERGE);
}

AP_DECLARE(int) ap_method_register(apr_pool_t *p, const char *methname)
{
    int *methnum;

    if (methods_registry == NULL) {
        ap_method_registry_init(p);
    }

    if (methname == NULL) {
        return M_INVALID;
    }

    /* Check if the method was previously registered.  If it was
     * return the associated method number.
     */
    methnum = (int *)apr_hash_get(methods_registry, methname,
                                  APR_HASH_KEY_STRING);
    if (methnum != NULL)
        return *methnum;

    if (cur_method_number > METHOD_NUMBER_LAST) {
        /* The method registry  has run out of dynamically
         * assignable method numbers. Log this and return M_INVALID.
         */
        ap_log_perror(APLOG_MARK, APLOG_ERR, 0, p, APLOGNO(01610)
                      "Maximum new request methods %d reached while "
                      "registering method %s.",
                      METHOD_NUMBER_LAST, methname);
        return M_INVALID;
    }

    register_one_method(p, methname, cur_method_number);
    return cur_method_number++;
}

#define UNKNOWN_METHOD (-1)

static int lookup_builtin_method(const char *method, apr_size_t len)
{
    /* Note: the following code was generated by the "shilka" tool from
       the "cocom" parsing/compilation toolkit. It is an optimized lookup
       based on analysis of the input keywords. Postprocessing was done
       on the shilka output, but the basic structure and analysis is
       from there. Should new HTTP methods be added, then manual insertion
       into this code is fine, or simply re-running the shilka tool on
       the appropriate input. */

    /* Note: it is also quite reasonable to just use our method_registry,
       but I'm assuming (probably incorrectly) we want more speed here
       (based on the optimizations the previous code was doing). */

    switch (len)
    {
    case 3:
        switch (method[0])
        {
        case 'P':
            return (method[1] == 'U'
                    && method[2] == 'T'
                    ? M_PUT : UNKNOWN_METHOD);
        case 'G':
            return (method[1] == 'E'
                    && method[2] == 'T'
                    ? M_GET : UNKNOWN_METHOD);
        default:
            return UNKNOWN_METHOD;
        }

    case 4:
        switch (method[0])
        {
        case 'H':
            return (method[1] == 'E'
                    && method[2] == 'A'
                    && method[3] == 'D'
                    ? M_GET : UNKNOWN_METHOD);
        case 'P':
            return (method[1] == 'O'
                    && method[2] == 'S'
                    && method[3] == 'T'
                    ? M_POST : UNKNOWN_METHOD);
        case 'M':
            return (method[1] == 'O'
                    && method[2] == 'V'
                    && method[3] == 'E'
                    ? M_MOVE : UNKNOWN_METHOD);
        case 'L':
            return (method[1] == 'O'
                    && method[2] == 'C'
                    && method[3] == 'K'
                    ? M_LOCK : UNKNOWN_METHOD);
        case 'C':
            return (method[1] == 'O'
                    && method[2] == 'P'
                    && method[3] == 'Y'
                    ? M_COPY : UNKNOWN_METHOD);
        default:
            return UNKNOWN_METHOD;
        }

    case 5:
        switch (method[2])
        {
        case 'T':
            return (memcmp(method, "PATCH", 5) == 0
                    ? M_PATCH : UNKNOWN_METHOD);
        case 'R':
            return (memcmp(method, "MERGE", 5) == 0
                    ? M_MERGE : UNKNOWN_METHOD);
        case 'C':
            return (memcmp(method, "MKCOL", 5) == 0
                    ? M_MKCOL : UNKNOWN_METHOD);
        case 'B':
            return (memcmp(method, "LABEL", 5) == 0
                    ? M_LABEL : UNKNOWN_METHOD);
        case 'A':
            return (memcmp(method, "TRACE", 5) == 0
                    ? M_TRACE : UNKNOWN_METHOD);
        default:
            return UNKNOWN_METHOD;
        }

    case 6:
        switch (method[0])
        {
        case 'U':
            switch (method[5])
            {
            case 'K':
                return (memcmp(method, "UNLOCK", 6) == 0
                        ? M_UNLOCK : UNKNOWN_METHOD);
            case 'E':
                return (memcmp(method, "UPDATE", 6) == 0
                        ? M_UPDATE : UNKNOWN_METHOD);
            default:
                return UNKNOWN_METHOD;
            }
        case 'R':
            return (memcmp(method, "REPORT", 6) == 0
                    ? M_REPORT : UNKNOWN_METHOD);
        case 'D':
            return (memcmp(method, "DELETE", 6) == 0
                    ? M_DELETE : UNKNOWN_METHOD);
        default:
            return UNKNOWN_METHOD;
        }

    case 7:
        switch (method[1])
        {
        case 'P':
            return (memcmp(method, "OPTIONS", 7) == 0
                    ? M_OPTIONS : UNKNOWN_METHOD);
        case 'O':
            return (memcmp(method, "CONNECT", 7) == 0
                    ? M_CONNECT : UNKNOWN_METHOD);
        case 'H':
            return (memcmp(method, "CHECKIN", 7) == 0
                    ? M_CHECKIN : UNKNOWN_METHOD);
        default:
            return UNKNOWN_METHOD;
        }

    case 8:
        switch (method[0])
        {
        case 'P':
            return (memcmp(method, "PROPFIND", 8) == 0
                    ? M_PROPFIND : UNKNOWN_METHOD);
        case 'C':
            return (memcmp(method, "CHECKOUT", 8) == 0
                    ? M_CHECKOUT : UNKNOWN_METHOD);
        default:
            return UNKNOWN_METHOD;
        }

    case 9:
        return (memcmp(method, "PROPPATCH", 9) == 0
                ? M_PROPPATCH : UNKNOWN_METHOD);

    case 10:
        switch (method[0])
        {
        case 'U':
            return (memcmp(method, "UNCHECKOUT", 10) == 0
                    ? M_UNCHECKOUT : UNKNOWN_METHOD);
        case 'M':
            return (memcmp(method, "MKACTIVITY", 10) == 0
                    ? M_MKACTIVITY : UNKNOWN_METHOD);
        default:
            return UNKNOWN_METHOD;
        }

    case 11:
        return (memcmp(method, "MKWORKSPACE", 11) == 0
                ? M_MKWORKSPACE : UNKNOWN_METHOD);

    case 15:
        return (memcmp(method, "VERSION-CONTROL", 15) == 0
                ? M_VERSION_CONTROL : UNKNOWN_METHOD);

    case 16:
        return (memcmp(method, "BASELINE-CONTROL", 16) == 0
                ? M_BASELINE_CONTROL : UNKNOWN_METHOD);

    default:
        return UNKNOWN_METHOD;
    }

    /* NOTREACHED */
}

/* Get the method number associated with the given string, assumed to
 * contain an HTTP method.  Returns M_INVALID if not recognized.
 *
 * This is the first step toward placing method names in a configurable
 * list.  Hopefully it (and other routines) can eventually be moved to
 * something like a mod_http_methods.c, complete with config stuff.
 */
AP_DECLARE(int) ap_method_number_of(const char *method)
{
    int len = strlen(method);
    int which = lookup_builtin_method(method, len);

    if (which != UNKNOWN_METHOD)
        return which;

    /* check if the method has been dynamically registered */
    if (methods_registry != NULL) {
        int *methnum = apr_hash_get(methods_registry, method, len);

        if (methnum != NULL) {
            return *methnum;
        }
    }

    return M_INVALID;
}

/*
 * Turn a known method number into a name.
 */
AP_DECLARE(const char *) ap_method_name_of(apr_pool_t *p, int methnum)
{
    apr_hash_index_t *hi = apr_hash_first(p, methods_registry);

    /* scan through the hash table, looking for a value that matches
       the provided method number. */
    for (; hi; hi = apr_hash_next(hi)) {
        const void *key;
        void *val;

        apr_hash_this(hi, &key, NULL, &val);
        if (*(int *)val == methnum)
            return key;
    }

    /* it wasn't found in the hash */
    return NULL;
}

/* The index is found by its offset from the x00 code of each level.
 * Although this is fast, it will need to be replaced if some nutcase
 * decides to define a high-numbered code before the lower numbers.
 * If that sad event occurs, replace the code below with a linear search
 * from status_lines[shortcut[i]] to status_lines[shortcut[i+1]-1];
 * or use NULL to fill the gaps.
 */
AP_DECLARE(int) ap_index_of_response(int status)
{
    static int shortcut[6] = {0, LEVEL_200, LEVEL_300, LEVEL_400,
    LEVEL_500, RESPONSE_CODES};
    int i, pos;

    if (status < 100) {               /* Below 100 is illegal for HTTP status */
        return LEVEL_500;
    }