util_lock.c

Apache 2.0.63 is the current stable version of the 2.0 series, and is recommended over any previous

/* 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.
 */

/*
** DAV repository-independent lock functions
*/

#include "apr.h"
#include "apr_strings.h"

#if APR_HAVE_STDIO_H
#include <stdio.h>              /* for sprintf() */
#endif

#include "mod_dav.h"
#include "http_log.h"
#include "http_config.h"
#include "http_protocol.h"
#include "http_core.h"


/* ---------------------------------------------------------------
**
** Property-related lock functions
**
*/

/*
** dav_lock_get_activelock:  Returns a <lockdiscovery> containing
**    an activelock element for every item in the lock_discovery tree
*/
DAV_DECLARE(const char *) dav_lock_get_activelock(request_rec *r,
                                                  dav_lock *lock,
                                                  dav_buffer *pbuf)
{
    dav_lock *lock_scan;
    const dav_hooks_locks *hooks = DAV_GET_HOOKS_LOCKS(r);
    int count = 0;
    dav_buffer work_buf = { 0 };
    apr_pool_t *p = r->pool;

    /* If no locks or no lock provider, there are no locks */
    if (lock == NULL || hooks == NULL) {
        /*
        ** Since resourcediscovery is defined with (activelock)*, 
        ** <D:activelock/> shouldn't be necessary for an empty lock.
        */
        return "";
    }

    /*
    ** Note: it could be interesting to sum the lengths of the owners
    **       and locktokens during this loop. However, the buffer
    **       mechanism provides some rough padding so that we don't
    **       really need to have an exact size. Further, constructing
    **       locktoken strings could be relatively expensive.
    */
    for (lock_scan = lock; lock_scan != NULL; lock_scan = lock_scan->next)
        count++;

    /* if a buffer was not provided, then use an internal buffer */
    if (pbuf == NULL)
        pbuf = &work_buf;

    /* reset the length before we start appending stuff */
    pbuf->cur_len = 0;

    /* prep the buffer with a "good" size */
    dav_check_bufsize(p, pbuf, count * 300);

    for (; lock != NULL; lock = lock->next) {
        char tmp[100];

#if DAV_DEBUG
        if (lock->rectype == DAV_LOCKREC_INDIRECT_PARTIAL) {
            /* ### crap. design error */
            dav_buffer_append(p, pbuf,
                              "DESIGN ERROR: attempted to product an "
                              "activelock element from a partial, indirect "
                              "lock record. Creating an XML parsing error "
                              "to ease detection of this situation: <");
        }
#endif

        dav_buffer_append(p, pbuf, "<D:activelock>" DEBUG_CR "<D:locktype>");
        switch (lock->type) {
        case DAV_LOCKTYPE_WRITE:
            dav_buffer_append(p, pbuf, "<D:write/>");
            break;
        default:
            /* ### internal error. log something? */
            break;
        }
        dav_buffer_append(p, pbuf, "</D:locktype>" DEBUG_CR "<D:lockscope>");
        switch (lock->scope) {
        case DAV_LOCKSCOPE_EXCLUSIVE:
            dav_buffer_append(p, pbuf, "<D:exclusive/>");
            break;
        case DAV_LOCKSCOPE_SHARED:
            dav_buffer_append(p, pbuf, "<D:shared/>");
            break;
        default:
            /* ### internal error. log something? */
            break;
        }
        dav_buffer_append(p, pbuf, "</D:lockscope>" DEBUG_CR);
        sprintf(tmp, "<D:depth>%s</D:depth>" DEBUG_CR,
                lock->depth == DAV_INFINITY ? "infinity" : "0");
        dav_buffer_append(p, pbuf, tmp);

        if (lock->owner) {
            /*
            ** This contains a complete, self-contained <DAV:owner> element,
            ** with namespace declarations and xml:lang handling. Just drop
            ** it in.
            */
            dav_buffer_append(p, pbuf, lock->owner);
        }
                
        dav_buffer_append(p, pbuf, "<D:timeout>");
        if (lock->timeout == DAV_TIMEOUT_INFINITE) {
            dav_buffer_append(p, pbuf, "Infinite");
        }
        else {
            time_t now = time(NULL);
            sprintf(tmp, "Second-%lu", (long unsigned int)(lock->timeout - now));
            dav_buffer_append(p, pbuf, tmp);
        }

        dav_buffer_append(p, pbuf,
                          "</D:timeout>" DEBUG_CR
                          "<D:locktoken>" DEBUG_CR
                          "<D:href>");
        dav_buffer_append(p, pbuf,
                          (*hooks->format_locktoken)(p, lock->locktoken));
        dav_buffer_append(p, pbuf,
                          "</D:href>" DEBUG_CR
                          "</D:locktoken>" DEBUG_CR
                          "</D:activelock>" DEBUG_CR);
    }

    return pbuf->buf;
}

/*
** dav_lock_parse_lockinfo:  Validates the given xml_doc to contain a
**    lockinfo XML element, then populates a dav_lock structure
**    with its contents.
*/
DAV_DECLARE(dav_error *) dav_lock_parse_lockinfo(request_rec *r,
                                                 const dav_resource *resource,
                                                 dav_lockdb *lockdb,
                                                 const apr_xml_doc *doc,
                                                 dav_lock **lock_request)
{
    apr_pool_t *p = r->pool;
    dav_error *err;
    apr_xml_elem *child;
    dav_lock *lock;

    if (!dav_validate_root(doc, "lockinfo")) {
        return dav_new_error(p, HTTP_BAD_REQUEST, 0,
                             "The request body contains an unexpected "
                             "XML root element.");
    }

    if ((err = (*lockdb->hooks->create_lock)(lockdb, resource,
                                             &lock)) != NULL) {
        return dav_push_error(p, err->status, 0,
                              "Could not parse the lockinfo due to an "
                              "internal problem creating a lock structure.",
                              err);
    }

    lock->depth = dav_get_depth(r, DAV_INFINITY);
    if (lock->depth == -1) {
        return dav_new_error(p, HTTP_BAD_REQUEST, 0,
                             "An invalid Depth header was specified.");
    }
    lock->timeout = dav_get_timeout(r);

    /* Parse elements in the XML body */
    for (child = doc->root->first_child; child; child = child->next) {
        if (strcmp(child->name, "locktype") == 0
            && child->first_child
            && lock->type == DAV_LOCKTYPE_UNKNOWN) {
            if (strcmp(child->first_child->name, "write") == 0) {
                lock->type = DAV_LOCKTYPE_WRITE;
                continue;
            }
        }
        if (strcmp(child->name, "lockscope") == 0
            && child->first_child
            && lock->scope == DAV_LOCKSCOPE_UNKNOWN) {
            if (strcmp(child->first_child->name, "exclusive") == 0)
                lock->scope = DAV_LOCKSCOPE_EXCLUSIVE;
            else if (strcmp(child->first_child->name, "shared") == 0)
                lock->scope = DAV_LOCKSCOPE_SHARED;
            if (lock->scope != DAV_LOCKSCOPE_UNKNOWN)
                continue;
        }

        if (strcmp(child->name, "owner") == 0 && lock->owner == NULL) {
            const char *text;

            /* quote all the values in the <DAV:owner> element */
            apr_xml_quote_elem(p, child);

            /*
            ** Store a full <DAV:owner> element with namespace definitions
            ** and an xml:lang definition, if applicable.
            */
            apr_xml_to_text(p, child, APR_XML_X2T_FULL_NS_LANG, doc->namespaces, 
                            NULL, &text, NULL);
            lock->owner = text;

            continue;
        }

        return dav_new_error(p, HTTP_PRECONDITION_FAILED, 0,
                             apr_psprintf(p,
                                         "The server cannot satisfy the "
                                         "LOCK request due to an unknown XML "
                                         "element (\"%s\") within the "
                                         "DAV:lockinfo element.",
                                         child->name));
    }

    *lock_request = lock;
    return NULL;
}

/* ---------------------------------------------------------------
**
** General lock functions
**
*/

/* dav_lock_walker:  Walker callback function to record indirect locks */
static dav_error * dav_lock_walker(dav_walk_resource *wres, int calltype)
{
    dav_walker_ctx *ctx = wres->walk_ctx;
    dav_error *err;

    /* We don't want to set indirects on the target */
    if ((*wres->resource->hooks->is_same_resource)(wres->resource,
                                                   ctx->w.root))
        return NULL;

    if ((err = (*ctx->w.lockdb->hooks->append_locks)(ctx->w.lockdb,
                                                     wres->resource, 1,
                                                     ctx->lock)) != NULL) {
        if (ap_is_HTTP_SERVER_ERROR(err->status)) {
            /* ### add a higher-level description? */
            return err;
        }

        /* add to the multistatus response */
        dav_add_response(wres, err->status, NULL);

        /*
        ** ### actually, this is probably wrong: we want to fail the whole
        ** ### LOCK process if something goes bad. maybe the caller should
        ** ### do a dav_unlock() (e.g. a rollback) if any errors occurred.
        */
    }

    return NULL;
}

/*
** dav_add_lock:  Add a direct lock for resource, and indirect locks for
**    all children, bounded by depth.
**    ### assume request only contains one lock
*/
DAV_DECLARE(dav_error *) dav_add_lock(request_rec *r,
                                      const dav_resource *resource,
                                      dav_lockdb *lockdb, dav_lock *lock,
                                      dav_response **response)
{
    dav_error *err;
    int depth = lock->depth;

    *response = NULL;

    /* Requested lock can be:
     *   Depth: 0   for null resource, existing resource, or existing collection
     *   Depth: Inf for existing collection
     */

    /*
    ** 2518 9.2 says to ignore depth if target is not a collection (it has
    **   no internal children); pretend the client gave the correct depth.
    */
    if (!resource->collection) {
        depth = 0;
    }

    /* In all cases, first add direct entry in lockdb */

    /*
    ** Append the new (direct) lock to the resource's existing locks.
    **
    ** Note: this also handles locknull resources
    */
    if ((err = (*lockdb->hooks->append_locks)(lockdb, resource, 0,
                                              lock)) != NULL) {
        /* ### maybe add a higher-level description */
        return err;
    }

    if (depth > 0) {
        /* Walk existing collection and set indirect locks */
        dav_walker_ctx ctx = { { 0 } };
        dav_response *multi_status;

        ctx.w.walk_type = DAV_WALKTYPE_NORMAL | DAV_WALKTYPE_AUTH;
        ctx.w.func = dav_lock_walker;
        ctx.w.walk_ctx = &ctx;
        ctx.w.pool = r->pool;
        ctx.w.root = resource;
        ctx.w.lockdb = lockdb;

        ctx.r = r;
        ctx.lock = lock;

        err = (*resource->hooks->walk)(&ctx.w, DAV_INFINITY, &multi_status);
        if (err != NULL) {
            /* implies a 5xx status code occurred. screw the multistatus */
            return err;
        }

        if (multi_status != NULL) {
            /* manufacture a 207 error for the multistatus response */
            *response = multi_status;
            return dav_new_error(r->pool, HTTP_MULTI_STATUS, 0,
                                 "Error(s) occurred on resources during the "
                                 "addition of a depth lock.");
        }
    }

    return NULL;
}

/*
** dav_lock_query:  Opens the lock database. Returns a linked list of
**    dav_lock structures for all direct locks on path.
*/
DAV_DECLARE(dav_error*) dav_lock_query(dav_lockdb *lockdb, 
                                       const dav_resource *resource,
                                       dav_lock **locks)
{
    /* If no lock database, return empty result */
    if (lockdb == NULL) {
        *locks = NULL;
        return NULL;
    }

    /* ### insert a higher-level description? */
    return (*lockdb->hooks->get_locks)(lockdb, resource,
                                       DAV_GETLOCKS_RESOLVED,
                                       locks);
}

/* dav_unlock_walker:  Walker callback function to remove indirect locks */
static dav_error * dav_unlock_walker(dav_walk_resource *wres, int calltype)
{
    dav_walker_ctx *ctx = wres->walk_ctx;
    dav_error *err;

    /* Before removing the lock, do any auto-checkin required */
    if (wres->resource->working) {
        /* ### get rid of this typecast */
        if ((err = dav_auto_checkin(ctx->r, (dav_resource *) wres->resource,
                                    0 /*undo*/, 1 /*unlock*/, NULL))
            != NULL) {
            return err;
        }
    }

    if ((err = (*ctx->w.lockdb->hooks->remove_lock)(ctx->w.lockdb,
                                                    wres->resource,
                                                    ctx->locktoken)) != NULL) {