upload http

JIRA: BOTTLENECK-10

Change-Id: I7598427ff904df438ce77c2819ee48ac75ffa8da
Signed-off-by: hongbotian <hongbo.tianhongbo@huawei.com>

1 files changed, 2021 insertions, 0 deletions

diff --git a/rubbos/app/httpd-2.0.64/modules/dav/main/util.c b/rubbos/app/httpd-2.0.64/modules/dav/main/util.c
new file mode 100644
index 00000000..3ff3a19f
--- /dev/null
+++ b/rubbos/app/httpd-2.0.64/modules/dav/main/util.c
@@ -0,0 +1,2021 @@
+/* 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 extension module for Apache 2.0.*
+**  - various utilities, repository-independent
+*/
+
+#include "apr_strings.h"
+#include "apr_lib.h"
+
+#define APR_WANT_STRFUNC
+#include "apr_want.h"
+
+#include "mod_dav.h"
+
+#include "http_request.h"
+#include "http_config.h"
+#include "http_vhost.h"
+#include "http_log.h"
+#include "http_protocol.h"
+
+DAV_DECLARE(dav_error*) dav_new_error(apr_pool_t *p, int status, 
+                                      int error_id, const char *desc)
+{
+    int save_errno = errno;
+    dav_error *err = apr_pcalloc(p, sizeof(*err));
+
+    /* DBG3("dav_new_error: %d %d %s", status, error_id, desc ? desc : "(no desc)"); */
+
+    err->status = status;
+    err->error_id = error_id;
+    err->desc = desc;
+    err->save_errno = save_errno;
+
+    return err;
+}
+
+DAV_DECLARE(dav_error*) dav_new_error_tag(apr_pool_t *p, int status, 
+                                          int error_id, const char *desc,
+                                          const char *namespace,
+                                          const char *tagname)
+{
+    dav_error *err = dav_new_error(p, status, error_id, desc);
+
+    err->tagname = tagname;
+    err->namespace = namespace;
+
+    return err;
+}
+
+
+DAV_DECLARE(dav_error*) dav_push_error(apr_pool_t *p, int status, 
+                                       int error_id, const char *desc, 
+                                       dav_error *prev)
+{
+    dav_error *err = apr_pcalloc(p, sizeof(*err));
+
+    err->status = status;
+    err->error_id = error_id;
+    err->desc = desc;
+    err->prev = prev;
+
+    return err;
+}
+
+DAV_DECLARE(void) dav_check_bufsize(apr_pool_t * p, dav_buffer *pbuf, 
+                                    apr_size_t extra_needed)
+{
+    /* grow the buffer if necessary */
+    if (pbuf->cur_len + extra_needed > pbuf->alloc_len) {
+        char *newbuf;
+
+        pbuf->alloc_len += extra_needed + DAV_BUFFER_PAD;
+        newbuf = apr_palloc(p, pbuf->alloc_len);
+        memcpy(newbuf, pbuf->buf, pbuf->cur_len);
+        pbuf->buf = newbuf;
+    }
+}
+
+DAV_DECLARE(void) dav_set_bufsize(apr_pool_t * p, dav_buffer *pbuf, 
+                                  apr_size_t size)
+{
+    /* NOTE: this does not retain prior contents */
+
+    /* NOTE: this function is used to init the first pointer, too, since
+       the PAD will be larger than alloc_len (0) for zeroed structures */
+
+    /* grow if we don't have enough for the requested size plus padding */
+    if (size + DAV_BUFFER_PAD > pbuf->alloc_len) {
+        /* set the new length; min of MINSIZE */
+        pbuf->alloc_len = size + DAV_BUFFER_PAD;
+        if (pbuf->alloc_len < DAV_BUFFER_MINSIZE)
+            pbuf->alloc_len = DAV_BUFFER_MINSIZE;
+
+        pbuf->buf = apr_palloc(p, pbuf->alloc_len);
+    }
+    pbuf->cur_len = size;
+}
+
+
+/* initialize a buffer and copy the specified (null-term'd) string into it */
+DAV_DECLARE(void) dav_buffer_init(apr_pool_t *p, dav_buffer *pbuf, 
+                                  const char *str)
+{
+    dav_set_bufsize(p, pbuf, strlen(str));
+    memcpy(pbuf->buf, str, pbuf->cur_len + 1);
+}
+
+/* append a string to the end of the buffer, adjust length */
+DAV_DECLARE(void) dav_buffer_append(apr_pool_t *p, dav_buffer *pbuf, 
+                                    const char *str)
+{
+    apr_size_t len = strlen(str);
+
+    dav_check_bufsize(p, pbuf, len + 1);
+    memcpy(pbuf->buf + pbuf->cur_len, str, len + 1);
+    pbuf->cur_len += len;
+}
+
+/* place a string on the end of the buffer, do NOT adjust length */
+DAV_DECLARE(void) dav_buffer_place(apr_pool_t *p, dav_buffer *pbuf, 
+                                   const char *str)
+{
+    apr_size_t len = strlen(str);
+
+    dav_check_bufsize(p, pbuf, len + 1);
+    memcpy(pbuf->buf + pbuf->cur_len, str, len + 1);
+}
+
+/* place some memory on the end of a buffer; do NOT adjust length */
+DAV_DECLARE(void) dav_buffer_place_mem(apr_pool_t *p, dav_buffer *pbuf, 
+                                       const void *mem, apr_size_t amt, 
+                                       apr_size_t pad)
+{
+    dav_check_bufsize(p, pbuf, amt + pad);
+    memcpy(pbuf->buf + pbuf->cur_len, mem, amt);
+}
+
+/*
+** dav_lookup_uri()
+**
+** Extension for ap_sub_req_lookup_uri() which can't handle absolute
+** URIs properly.
+**
+** If NULL is returned, then an error occurred with parsing the URI or
+** the URI does not match the current server.
+*/
+DAV_DECLARE(dav_lookup_result) dav_lookup_uri(const char *uri,
+                                              request_rec * r,
+                                              int must_be_absolute)
+{
+    dav_lookup_result result = { 0 };
+    const char *scheme;
+    apr_port_t port;
+    apr_uri_t comp;
+    char *new_file;
+    const char *domain;
+
+    /* first thing to do is parse the URI into various components */
+    if (apr_uri_parse(r->pool, uri, &comp) != APR_SUCCESS) {
+        result.err.status = HTTP_BAD_REQUEST;
+        result.err.desc = "Invalid syntax in Destination URI.";
+        return result;
+    }
+
+    /* the URI must be an absoluteURI (WEBDAV S9.3) */
+    if (comp.scheme == NULL && must_be_absolute) {
+        result.err.status = HTTP_BAD_REQUEST;
+        result.err.desc = "Destination URI must be an absolute URI.";
+        return result;
+    }
+
+    /* the URI must not have a query (args) or a fragment */
+    if (comp.query != NULL || comp.fragment != NULL) {
+        result.err.status = HTTP_BAD_REQUEST;
+        result.err.desc =
+            "Destination URI contains invalid components "
+            "(a query or a fragment).";
+        return result;
+    }
+
+    /* If the scheme or port was provided, then make sure that it matches
+       the scheme/port of this request. If the request must be absolute,
+       then require the (explicit/implicit) scheme/port be matching.
+
+       ### hmm. if a port wasn't provided (does the parse return port==0?),
+       ### but we're on a non-standard port, then we won't detect that the
+       ### URI's port implies the wrong one.
+    */
+    if (comp.scheme != NULL || comp.port != 0 || must_be_absolute)
+    {
+        /* ### not sure this works if the current request came in via https: */
+        scheme = r->parsed_uri.scheme;
+        if (scheme == NULL)
+            scheme = ap_http_method(r);
+
+        /* insert a port if the URI did not contain one */
+        if (comp.port == 0)
+            comp.port = apr_uri_port_of_scheme(comp.scheme);
+
+        /* now, verify that the URI uses the same scheme as the current.
+           request. the port must match our port.
+        */
+        apr_sockaddr_port_get(&port, r->connection->local_addr);
+        if (strcasecmp(comp.scheme, scheme) != 0
+#ifdef APACHE_PORT_HANDLING_IS_BUSTED
+            || comp.port != port
+#endif
+            ) {
+            result.err.status = HTTP_BAD_GATEWAY;
+            result.err.desc = apr_psprintf(r->pool,
+                                           "Destination URI refers to "
+                                           "different scheme or port "
+                                           "(%s://hostname:%d)" APR_EOL_STR
+                                           "(want: %s://hostname:%d)",
+                                           comp.scheme ? comp.scheme : scheme,
+                                           comp.port ? comp.port : port,
+                                           scheme, port);
+            return result;
+        }
+    }
+
+    /* we have verified the scheme, port, and general structure */
+
+    /*
+    ** Hrm.  IE5 will pass unqualified hostnames for both the 
+    ** Host: and Destination: headers.  This breaks the
+    ** http_vhost.c::matches_aliases function.
+    **
+    ** For now, qualify unqualified comp.hostnames with
+    ** r->server->server_hostname.
+    **
+    ** ### this is a big hack. Apache should provide a better way.
+    ** ### maybe the admin should list the unqualified hosts in a
+    ** ### <ServerAlias> block?
+    */
+    if (comp.hostname != NULL
+        && strrchr(comp.hostname, '.') == NULL
+        && (domain = strchr(r->server->server_hostname, '.')) != NULL) {
+        comp.hostname = apr_pstrcat(r->pool, comp.hostname, domain, NULL);
+    }
+
+    /* now, if a hostname was provided, then verify that it represents the
+       same server as the current connection. note that we just use our
+       port, since we've verified the URI matches ours */
+#ifdef APACHE_PORT_HANDLING_IS_BUSTED
+    if (comp.hostname != NULL &&
+        !ap_matches_request_vhost(r, comp.hostname, port)) {
+        result.err.status = HTTP_BAD_GATEWAY;
+        result.err.desc = "Destination URI refers to a different server.";
+        return result;
+    }
+#endif
+
+    /* we have verified that the requested URI denotes the same server as
+       the current request. Therefore, we can use ap_sub_req_lookup_uri() */
+
+    /* reconstruct a URI as just the path */
+    new_file = apr_uri_unparse(r->pool, &comp, APR_URI_UNP_OMITSITEPART);
+
+    /*
+     * Lookup the URI and return the sub-request. Note that we use the
+     * same HTTP method on the destination. This allows the destination
+     * to apply appropriate restrictions (e.g. readonly).
+     */
+    result.rnew = ap_sub_req_method_uri(r->method, new_file, r, NULL);
+
+    return result;
+}
+
+/* ---------------------------------------------------------------
+**
+** XML UTILITY FUNCTIONS
+*/
+
+/* validate that the root element uses a given DAV: tagname (TRUE==valid) */
+DAV_DECLARE(int) dav_validate_root(const apr_xml_doc *doc,
+                                   const char *tagname)
+{
+    return doc->root &&
+        doc->root->ns == APR_XML_NS_DAV_ID &&
+        strcmp(doc->root->name, tagname) == 0;
+}
+
+/* find and return the (unique) child with a given DAV: tagname */
+DAV_DECLARE(apr_xml_elem *) dav_find_child(const apr_xml_elem *elem, 
+                                           const char *tagname)
+{
+    apr_xml_elem *child = elem->first_child;
+
+    for (; child; child = child->next)
+        if (child->ns == APR_XML_NS_DAV_ID && !strcmp(child->name, tagname))
+            return child;
+    return NULL;
+}
+
+/* gather up all the CDATA into a single string */
+DAV_DECLARE(const char *) dav_xml_get_cdata(const apr_xml_elem *elem, apr_pool_t *pool,
+                              int strip_white)
+{
+    apr_size_t len = 0;
+    apr_text *scan;
+    const apr_xml_elem *child;
+    char *cdata;
+    char *s;
+    apr_size_t tlen;
+    const char *found_text = NULL; /* initialize to avoid gcc warning */
+    int found_count = 0;
+
+    for (scan = elem->first_cdata.first; scan != NULL; scan = scan->next) {
+        found_text = scan->text;
+        ++found_count;
+        len += strlen(found_text);
+    }
+
+    for (child = elem->first_child; child != NULL; child = child->next) {
+        for (scan = child->following_cdata.first;
+             scan != NULL;
+             scan = scan->next) {
+            found_text = scan->text;
+            ++found_count;
+            len += strlen(found_text);
+        }
+    }
+
+    /* some fast-path cases:
+     * 1) zero-length cdata
+     * 2) a single piece of cdata with no whitespace to strip
+     */
+    if (len == 0)
+        return "";
+    if (found_count == 1) {
+        if (!strip_white
+            || (!apr_isspace(*found_text)
+                && !apr_isspace(found_text[len - 1])))
+            return found_text;
+    }
+
+    cdata = s = apr_palloc(pool, len + 1);
+
+    for (scan = elem->first_cdata.first; scan != NULL; scan = scan->next) {
+        tlen = strlen(scan->text);
+        memcpy(s, scan->text, tlen);
+        s += tlen;
+    }
+
+    for (child = elem->first_child; child != NULL; child = child->next) {
+        for (scan = child->following_cdata.first;
+             scan != NULL;
+             scan = scan->next) {
+            tlen = strlen(scan->text);
+            memcpy(s, scan->text, tlen);
+            s += tlen;
+        }
+    }
+
+    *s = '\0';
+
+    if (strip_white) {
+        /* trim leading whitespace */
+        while (apr_isspace(*cdata))     /* assume: return false for '\0' */
+            ++cdata;
+
+        /* trim trailing whitespace */
+        while (len-- > 0 && apr_isspace(cdata[len]))
+            continue;
+        cdata[len + 1] = '\0';
+    }
+
+    return cdata;
+}
+
+DAV_DECLARE(dav_xmlns_info *) dav_xmlns_create(apr_pool_t *pool)
+{
+    dav_xmlns_info *xi = apr_pcalloc(pool, sizeof(*xi));
+
+    xi->pool = pool;
+    xi->uri_prefix = apr_hash_make(pool);
+    xi->prefix_uri = apr_hash_make(pool);
+
+    return xi;
+}
+
+DAV_DECLARE(void) dav_xmlns_add(dav_xmlns_info *xi,
+                                const char *prefix, const char *uri)
+{
+    /* this "should" not overwrite a prefix mapping */
+    apr_hash_set(xi->prefix_uri, prefix, APR_HASH_KEY_STRING, uri);
+
+    /* note: this may overwrite an existing URI->prefix mapping, but it
+       doesn't matter -- any prefix is usuable to specify the URI. */
+    apr_hash_set(xi->uri_prefix, uri, APR_HASH_KEY_STRING, prefix);
+}
+
+DAV_DECLARE(const char *) dav_xmlns_add_uri(dav_xmlns_info *xi,
+                                            const char *uri)
+{
+    const char *prefix;
+
+    if ((prefix = apr_hash_get(xi->uri_prefix, uri,
+                               APR_HASH_KEY_STRING)) != NULL)
+        return prefix;
+
+    prefix = apr_psprintf(xi->pool, "g%d", xi->count++);
+    dav_xmlns_add(xi, prefix, uri);
+    return prefix;
+}
+
+DAV_DECLARE(const char *) dav_xmlns_get_uri(dav_xmlns_info *xi,
+                                            const char *prefix)
+{
+    return apr_hash_get(xi->prefix_uri, prefix, APR_HASH_KEY_STRING);
+}
+
+DAV_DECLARE(const char *) dav_xmlns_get_prefix(dav_xmlns_info *xi,
+                                               const char *uri)
+{
+    return apr_hash_get(xi->uri_prefix, uri, APR_HASH_KEY_STRING);
+}
+
+DAV_DECLARE(void) dav_xmlns_generate(dav_xmlns_info *xi,
+                                     apr_text_header *phdr)
+{
+    apr_hash_index_t *hi = apr_hash_first(xi->pool, xi->prefix_uri);
+
+    for (; hi != NULL; hi = apr_hash_next(hi)) {
+        const void *prefix;
+        void *uri;
+        const char *s;
+
+        apr_hash_this(hi, &prefix, NULL, &uri);
+
+        s = apr_psprintf(xi->pool, " xmlns:%s=\"%s\"",
+                         (const char *)prefix, (const char *)uri);
+        apr_text_append(xi->pool, phdr, s);
+    }
+}
+
+/* ---------------------------------------------------------------
+**
+** Timeout header processing
+**
+*/
+
+/* dav_get_timeout:  If the Timeout: header exists, return a time_t
+ *    when this lock is expected to expire.  Otherwise, return
+ *    a time_t of DAV_TIMEOUT_INFINITE.
+ *
+ *    It's unclear if DAV clients are required to understand
+ *    Seconds-xxx and Infinity time values.  We assume that they do.
+ *    In addition, for now, that's all we understand, too.
+ */
+DAV_DECLARE(time_t) dav_get_timeout(request_rec *r)
+{
+    time_t now, expires = DAV_TIMEOUT_INFINITE;
+
+    const char *timeout_const = apr_table_get(r->headers_in, "Timeout");
+    const char *timeout = apr_pstrdup(r->pool, timeout_const), *val;
+
+    if (timeout == NULL)
+        return DAV_TIMEOUT_INFINITE;
+
+    /* Use the first thing we understand, or infinity if
+     * we don't understand anything.
+     */
+
+    while ((val = ap_getword_white(r->pool, &timeout)) && strlen(val)) {
+        if (!strncmp(val, "Infinite", 8)) {
+            return DAV_TIMEOUT_INFINITE;
+        }
+
+        if (!strncmp(val, "Second-", 7)) {
+            val += 7;
+            /* ### We need to handle overflow better:
+             * ### timeout will be <= 2^32 - 1
+             */
+            expires = atol(val);
+            now     = time(NULL);
+            return now + expires;
+        }
+    }
+
+    return DAV_TIMEOUT_INFINITE;
+}
+
+/* ---------------------------------------------------------------
+**
+** If Header processing
+**
+*/
+
+/* add_if_resource returns a new if_header, linking it to next_ih.
+ */
+static dav_if_header *dav_add_if_resource(apr_pool_t *p, dav_if_header *next_ih,
+                                          const char *uri, apr_size_t uri_len)
+{
+    dav_if_header *ih;
+
+    if ((ih = apr_pcalloc(p, sizeof(*ih))) == NULL)
+        return NULL;
+
+    ih->uri = uri;
+    ih->uri_len = uri_len;
+    ih->next = next_ih;
+
+    return ih;
+}
+
+/* add_if_state adds a condition to an if_header.
+ */
+static dav_error * dav_add_if_state(apr_pool_t *p, dav_if_header *ih,
+                                    const char *state_token,
+                                    dav_if_state_type t, int condition,
+                                    const dav_hooks_locks *locks_hooks)
+{
+    dav_if_state_list *new_sl;
+
+    new_sl = apr_pcalloc(p, sizeof(*new_sl));
+
+    new_sl->condition = condition;
+    new_sl->type      = t;
+    
+    if (t == dav_if_opaquelock) {
+        dav_error *err;
+
+        if ((err = (*locks_hooks->parse_locktoken)(p, state_token,
+                                                   &new_sl->locktoken)) != NULL) {
+            /* In cases where the state token is invalid, we'll just skip
+             * it rather than return 400.
+             */
+            if (err->error_id == DAV_ERR_LOCK_UNK_STATE_TOKEN) {
+                return NULL;
+            }
+            else {
+                /* ### maybe add a higher-level description */
+                return err;
+            }
+        }
+    }
+    else
+        new_sl->etag = state_token;
+
+    new_sl->next = ih->state;
+    ih->state = new_sl;
+
+    return NULL;
+}
+
+/* fetch_next_token returns the substring from str+1
+ * to the next occurence of char term, or \0, whichever
+ * occurs first.  Leading whitespace is ignored.
+ */
+static char *dav_fetch_next_token(char **str, char term)
+{
+    char *sp;
+    char *token;
+        
+    token = *str + 1;
+
+    while (*token && (*token == ' ' || *token == '\t'))
+        token++;
+
+    if ((sp = strchr(token, term)) == NULL)
+        return NULL;
+
+    *sp = '\0';
+    *str = sp;
+    return token;
+}
+
+/* dav_process_if_header:
+ *
+ *   If NULL (no error) is returned, then **if_header points to the
+ *   "If" productions structure (or NULL if "If" is not present).
+ *
+ *   ### this part is bogus:
+ *   If an error is encountered, the error is logged.  Parent should
+ *   return err->status.
+ */
+static dav_error * dav_process_if_header(request_rec *r, dav_if_header **p_ih)
+{
+    dav_error *err;
+    char *str;
+    char *list;
+    const char *state_token;
+    const char *uri = NULL;        /* scope of current production; NULL=no-tag */
+    apr_size_t uri_len = 0;
+    dav_if_header *ih = NULL;
+    apr_uri_t parsed_uri;
+    const dav_hooks_locks *locks_hooks = DAV_GET_HOOKS_LOCKS(r);
+    enum {no_tagged, tagged, unknown} list_type = unknown;
+    int condition;
+        
+    *p_ih = NULL;
+
+    if ((str = apr_pstrdup(r->pool, apr_table_get(r->headers_in, "If"))) == NULL)
+        return NULL;
+
+    while (*str) {
+        switch(*str) {
+        case '<':
+            /* Tagged-list production - following states apply to this uri */
+            if (list_type == no_tagged
+                || ((uri = dav_fetch_next_token(&str, '>')) == NULL)) {
+                return dav_new_error(r->pool, HTTP_BAD_REQUEST,
+                                     DAV_ERR_IF_TAGGED,
+                                     "Invalid If-header: unclosed \"<\" or "
+                                     "unexpected tagged-list production.");
+            }
+            
+            /* 2518 specifies this must be an absolute URI; just take the
+             * relative part for later comparison against r->uri */
+            if (apr_uri_parse(r->pool, uri, &parsed_uri) != APR_SUCCESS
+                || !parsed_uri.path) {
+                return dav_new_error(r->pool, HTTP_BAD_REQUEST,
+                                     DAV_ERR_IF_TAGGED,
+                                     "Invalid URI in tagged If-header.");
+            }
+            /* note that parsed_uri.path is allocated; we can trash it */
+
+            /* clean up the URI a bit */
+            ap_getparents(parsed_uri.path);
+            uri_len = strlen(parsed_uri.path);
+            if (uri_len > 1 && parsed_uri.path[uri_len - 1] == '/')
+                parsed_uri.path[--uri_len] = '\0';
+
+            uri = parsed_uri.path;
+            list_type = tagged;
+            break;
+
+        case '(':
+            /* List production */
+
+            /* If a uri has not been encountered, this is a No-Tagged-List */
+            if (list_type == unknown)
+                list_type = no_tagged;
+
+            if ((list = dav_fetch_next_token(&str, ')')) == NULL) {
+                return dav_new_error(r->pool, HTTP_BAD_REQUEST,
+                                     DAV_ERR_IF_UNCLOSED_PAREN,
+                                     "Invalid If-header: unclosed \"(\".");
+            }
+
+            if ((ih = dav_add_if_resource(r->pool, ih, uri, uri_len)) == NULL) {
+                /* ### dav_add_if_resource() should return an error for us! */
+                return dav_new_error(r->pool, HTTP_BAD_REQUEST,
+                                     DAV_ERR_IF_PARSE,
+                                     "Internal server error parsing \"If:\" "
+                                     "header.");
+            }
+
+            condition = DAV_IF_COND_NORMAL;
+
+            while (*list) {
+                /* List is the entire production (in a uri scope) */
+
+                switch (*list) {
+                case '<':
+                    if ((state_token = dav_fetch_next_token(&list, '>')) == NULL) {
+                        /* ### add a description to this error */
+                        return dav_new_error(r->pool, HTTP_BAD_REQUEST,
+                                             DAV_ERR_IF_PARSE, NULL);
+                    }
+
+                    if ((err = dav_add_if_state(r->pool, ih, state_token, dav_if_opaquelock,
+                                                condition, locks_hooks)) != NULL) {
+                        /* ### maybe add a higher level description */
+                        return err;
+                    }
+                    condition = DAV_IF_COND_NORMAL;
+                    break;
+
+                case '[':
+                    if ((state_token = dav_fetch_next_token(&list, ']')) == NULL) {
+                        /* ### add a description to this error */
+                        return dav_new_error(r->pool, HTTP_BAD_REQUEST,
+                                             DAV_ERR_IF_PARSE, NULL);
+                    }
+
+                    if ((err = dav_add_if_state(r->pool, ih, state_token, dav_if_etag,
+                                                condition, locks_hooks)) != NULL) {
+                        /* ### maybe add a higher level description */
+                        return err;
+                    }
+                    condition = DAV_IF_COND_NORMAL;
+                    break;
+
+                case 'N':
+                    if (list[1] == 'o' && list[2] == 't') {
+                        if (condition != DAV_IF_COND_NORMAL) {
+                            return dav_new_error(r->pool, HTTP_BAD_REQUEST,
+                                                 DAV_ERR_IF_MULTIPLE_NOT,
+                                                 "Invalid \"If:\" header: "
+                                                 "Multiple \"not\" entries "
+                                                 "for the same state.");
+                        }
+                        condition = DAV_IF_COND_NOT;
+                    }
+                    list += 2;
+                    break;
+
+                case ' ':
+                case '\t':
+                    break;
+
+                default:
+                    return dav_new_error(r->pool, HTTP_BAD_REQUEST,
+                                         DAV_ERR_IF_UNK_CHAR,
+                                         apr_psprintf(r->pool,
+                                                     "Invalid \"If:\" "
+                                                     "header: Unexpected "
+                                                     "character encountered "
+                                                     "(0x%02x, '%c').",
+                                                     *list, *list));
+                }
+
+                list++;
+            }
+            break;
+
+        case ' ':
+        case '\t':
+            break;
+
+        default:
+            return dav_new_error(r->pool, HTTP_BAD_REQUEST,
+                                 DAV_ERR_IF_UNK_CHAR,
+                                 apr_psprintf(r->pool,
+                                             "Invalid \"If:\" header: "
+                                             "Unexpected character "
+                                             "encountered (0x%02x, '%c').",
+                                             *str, *str));
+        }
+
+        str++;
+    }
+
+    *p_ih = ih;
+    return NULL;
+}
+
+static int dav_find_submitted_locktoken(const dav_if_header *if_header,
+                                        const dav_lock *lock_list,
+                                        const dav_hooks_locks *locks_hooks)
+{
+    for (; if_header != NULL; if_header = if_header->next) {
+        const dav_if_state_list *state_list;
+
+        for (state_list = if_header->state;
+             state_list != NULL;
+             state_list = state_list->next) {
+
+            if (state_list->type == dav_if_opaquelock) {
+                const dav_lock *lock;
+
+                /* given state_list->locktoken, match it */
+
+                /*
+                ** The resource will have one or more lock tokens. We only
+                ** need to match one of them against any token in the
+                ** If: header.
+                **
+                ** One token case: It is an exclusive or shared lock. Either
+                **                 way, we must find it.
+                **
+                ** N token case: They are shared locks. By policy, we need
+                **               to match only one. The resource's other
+                **               tokens may belong to somebody else (so we
+                **               shouldn't see them in the If: header anyway)
+                */
+                for (lock = lock_list; lock != NULL; lock = lock->next) {
+
+                    if (!(*locks_hooks->compare_locktoken)(state_list->locktoken, lock->locktoken)) {
+                        return 1;
+                    }
+                }
+            }
+        }
+    }
+
+    return 0;
+}
+
+/* dav_validate_resource_state:
+ *    Returns NULL if path/uri meets if-header and lock requirements
+ */
+static dav_error * dav_validate_resource_state(apr_pool_t *p,
+                                               const dav_resource *resource,
+                                               dav_lockdb *lockdb,
+                                               const dav_if_header *if_header,
+                                               int flags,
+                                               dav_buffer *pbuf,
+                                               request_rec *r)
+{
+    dav_error *err;
+    const char *uri;
+    const char *etag;
+    const dav_hooks_locks *locks_hooks = (lockdb ? lockdb->hooks : NULL);
+    const dav_if_header *ifhdr_scan;
+    dav_if_state_list *state_list;
+    dav_lock *lock_list;
+    dav_lock *lock;
+    int num_matched;
+    int num_that_apply;
+    int seen_locktoken;
+    apr_size_t uri_len;
+    const char *reason = NULL;
+
+    /* DBG1("validate: <%s>", resource->uri); */
+
+    /*
+    ** The resource will have one of three states:
+    **
+    ** 1) No locks. We have no special requirements that the user supply
+    **    specific locktokens. One of the state lists must match, and
+    **    we're done.
+    **
+    ** 2) One exclusive lock. The locktoken must appear *anywhere* in the
+    **    If: header. Of course, asserting the token in a "Not" term will
+    **    quickly fail that state list :-). If the locktoken appears in
+    **    one of the state lists *and* one state list matches, then we're
+    **    done.
+    **
+    ** 3) One or more shared locks. One of the locktokens must appear
+    **    *anywhere* in the If: header. If one of the locktokens appears,
+    **    and we match one state list, then we are done.
+    **
+    ** The <seen_locktoken> variable determines whether we have seen one
+    ** of this resource's locktokens in the If: header.
+    */
+
+    /*
+    ** If this is a new lock request, <flags> will contain the requested
+    ** lock scope.  Three rules apply:
+    **
+    ** 1) Do not require a (shared) locktoken to be seen (when we are
+    **    applying another shared lock)
+    ** 2) If the scope is exclusive and we see any locks, fail.
+    ** 3) If the scope is shared and we see an exclusive lock, fail.
+    */
+
+    if (lockdb == NULL) {
+        /* we're in State 1. no locks. */
+        lock_list = NULL;
+    }
+    else {
+        /*
+        ** ### hrm... we don't need to have these fully
+        ** ### resolved since we're only looking at the
+        ** ### locktokens...
+        **
+        ** ### use get_locks w/ calltype=PARTIAL
+        */
+        if ((err = dav_lock_query(lockdb, resource, &lock_list)) != NULL) {
+            return dav_push_error(p,
+                                  HTTP_INTERNAL_SERVER_ERROR, 0,
+                                  "The locks could not be queried for "
+                                  "verification against a possible \"If:\" "
+                                  "header.",
+                                  err);
+        }
+
+        /* lock_list now determines whether we're in State 1, 2, or 3. */
+    }
+
+    /* 
+    ** For a new, exclusive lock: if any locks exist, fail.
+    ** For a new, shared lock:    if an exclusive lock exists, fail.
+    **                            else, do not require a token to be seen.
+    */
+    if (flags & DAV_LOCKSCOPE_EXCLUSIVE) {
+        if (lock_list != NULL) {
+            return dav_new_error(p, HTTP_LOCKED, 0, 
+                                 "Existing lock(s) on the requested resource "
+                                 "prevent an exclusive lock.");
+        }
+
+        /*
+        ** There are no locks, so we can pretend that we've already met
+        ** any requirement to find the resource's locks in an If: header.
+        */
+        seen_locktoken = 1;
+    }
+    else if (flags & DAV_LOCKSCOPE_SHARED) {
+        /*
+        ** Strictly speaking, we don't need this loop. Either the first
+        ** (and only) lock will be EXCLUSIVE, or none of them will be.
+        */
+        for (lock = lock_list; lock != NULL; lock = lock->next) {
+            if (lock->scope == DAV_LOCKSCOPE_EXCLUSIVE) {
+                return dav_new_error(p, HTTP_LOCKED, 0,
+                                     "The requested resource is already "
+                                     "locked exclusively.");
+            }
+        }
+
+        /*
+        ** The locks on the resource (if any) are all shared. Set the
+        ** <seen_locktoken> flag to indicate that we do not need to find
+        ** the locks in an If: header.
+        */
+        seen_locktoken = 1;
+    }
+    else {
+        /*
+        ** For methods other than LOCK:
+        **
+        ** If we have no locks, then <seen_locktoken> can be set to true --
+        ** pretending that we've already met the requirement of seeing one
+        ** of the resource's locks in the If: header.
+        **
+        ** Otherwise, it must be cleared and we'll look for one.
+        */
+        seen_locktoken = (lock_list == NULL);
+    }
+
+    /*
+    ** If there is no If: header, then we can shortcut some logic:
+    **
+    ** 1) if we do not need to find a locktoken in the (non-existent) If:
+    **    header, then we are successful.
+    **
+    ** 2) if we must find a locktoken in the (non-existent) If: header, then
+    **    we fail.
+    */
+    if (if_header == NULL) {
+        if (seen_locktoken)
+            return NULL;
+
+        return dav_new_error(p, HTTP_LOCKED, 0,
+                             "This resource is locked and an \"If:\" header "
+                             "was not supplied to allow access to the "
+                             "resource.");
+    }
+    /* the If: header is present */
+
+    /*
+    ** If a dummy header is present (because of a Lock-Token: header), then
+    ** we are required to find that token in this resource's set of locks.
+    ** If we have no locks, then we immediately fail.
+    **
+    ** This is a 400 (Bad Request) since they should only submit a locktoken
+    ** that actually exists.
+    **
+    ** Don't issue this response if we're talking about the parent resource.
+    ** It is okay for that resource to NOT have this locktoken.
+    ** (in fact, it certainly will not: a dummy_header only occurs for the
+    **  UNLOCK method, the parent is checked only for locknull resources,
+    **  and the parent certainly does not have the (locknull's) locktoken)
+    */
+    if (lock_list == NULL && if_header->dummy_header) {
+        if (flags & DAV_VALIDATE_IS_PARENT)
+            return NULL;
+        return dav_new_error(p, HTTP_BAD_REQUEST, 0,
+                             "The locktoken specified in the \"Lock-Token:\" "
+                             "header is invalid because this resource has no "
+                             "outstanding locks.");
+    }
+
+    /*
+    ** Prepare the input URI. We want the URI to never have a trailing slash.
+    **
+    ** When URIs are placed into the dav_if_header structure, they are
+    ** guaranteed to never have a trailing slash. If the URIs are equivalent,
+    ** then it doesn't matter if they both lack a trailing slash -- they're
+    ** still equivalent.
+    **
+    ** Note: we could also ensure that a trailing slash is present on both
+    ** URIs, but the majority of URIs provided to us via a resource walk
+    ** will not contain that trailing slash.
+    */
+    uri = resource->uri;
+    uri_len = strlen(uri);
+    if (uri[uri_len - 1] == '/') {
+        dav_set_bufsize(p, pbuf, uri_len);
+        memcpy(pbuf->buf, uri, uri_len);
+        pbuf->buf[--uri_len] = '\0';
+        uri = pbuf->buf;
+    }
+
+    /* get the resource's etag; we may need it during the checks */
+    etag = (*resource->hooks->getetag)(resource);
+
+    /* how many state_lists apply to this URI? */
+    num_that_apply = 0;
+
+    /* If there are if-headers, fail if this resource
+     * does not match at least one state_list.
+     */
+    for (ifhdr_scan = if_header;
+         ifhdr_scan != NULL;
+         ifhdr_scan = ifhdr_scan->next) {
+
+        /* DBG2("uri=<%s>  if_uri=<%s>", uri, ifhdr_scan->uri ? ifhdr_scan->uri : "(no uri)"); */
+
+        if (ifhdr_scan->uri != NULL
+            && (uri_len != ifhdr_scan->uri_len
+                || memcmp(uri, ifhdr_scan->uri, uri_len) != 0)) {
+            /*
+            ** A tagged-list's URI doesn't match this resource's URI.
+            ** Skip to the next state_list to see if it will match.
+            */
+            continue;
+        }
+
+        /* this state_list applies to this resource */
+
+        /*
+        ** ### only one state_list should ever apply! a no-tag, or a tagged
+        ** ### where S9.4.2 states only one can match.
+        **
+        ** ### revamp this code to loop thru ifhdr_scan until we find the
+        ** ### matching state_list. process it. stop.
+        */
+        ++num_that_apply;
+
+        /* To succeed, resource must match *all* of the states
+         * specified in the state_list.
+         */
+        for (state_list = ifhdr_scan->state;
+             state_list != NULL;
+             state_list = state_list->next) {
+
+            switch(state_list->type) {
+            case dav_if_etag:
+            {
+                int mismatch = strcmp(state_list->etag, etag);
+
+                if (state_list->condition == DAV_IF_COND_NORMAL && mismatch) {
+                    /*
+                    ** The specified entity-tag does not match the
+                    ** entity-tag on the resource. This state_list is
+                    ** not going to match. Bust outta here.
+                    */
+                    reason =
+                        "an entity-tag was specified, but the resource's "
+                        "actual ETag does not match.";
+                    goto state_list_failed;
+                }
+                else if (state_list->condition == DAV_IF_COND_NOT
+                         && !mismatch) {
+                    /*
+                    ** The specified entity-tag DOES match the
+                    ** entity-tag on the resource. This state_list is
+                    ** not going to match. Bust outta here.
+                    */
+                    reason =
+                        "an entity-tag was specified using the \"Not\" form, "
+                        "but the resource's actual ETag matches the provided "
+                        "entity-tag.";
+                    goto state_list_failed;
+                }
+                break;
+            }
+
+            case dav_if_opaquelock:
+                if (lockdb == NULL) {
+                    if (state_list->condition == DAV_IF_COND_NOT) {
+                        /* the locktoken is definitely not there! (success) */
+                        continue;
+                    }
+
+                    /* condition == DAV_IF_COND_NORMAL */
+
+                    /*
+                    ** If no lockdb is provided, then validation fails for
+                    ** this state_list (NORMAL means we were supposed to
+                    ** find the token, which we obviously cannot do without
+                    ** a lock database).
+                    **
+                    ** Go and try the next state list.
+                    */
+                    reason =
+                        "a State-token was supplied, but a lock database "
+                        "is not available for to provide the required lock.";
+                    goto state_list_failed;
+                }
+
+                /* Resource validation 'fails' if:
+                 *    ANY  of the lock->locktokens match
+                 *         a NOT state_list->locktoken,
+                 * OR
+                 *    NONE of the lock->locktokens match
+                 *         a NORMAL state_list->locktoken.
+                 */
+                num_matched = 0;
+                for (lock = lock_list; lock != NULL; lock = lock->next) {
+
+                    /*
+                    DBG2("compare: rsrc=%s  ifhdr=%s",
+                         (*locks_hooks->format_locktoken)(p, lock->locktoken),
+                         (*locks_hooks->format_locktoken)(p, state_list->locktoken));
+                    */
+
+                    /* nothing to do if the locktokens do not match. */
+                    if ((*locks_hooks->compare_locktoken)(state_list->locktoken, lock->locktoken)) {
+                        continue;
+                    }
+
+                    /*
+                    ** We have now matched up one of the resource's locktokens
+                    ** to a locktoken in a State-token in the If: header.
+                    ** Note this fact, so that we can pass the overall
+                    ** requirement of seeing at least one of the resource's
+                    ** locktokens.
+                    */
+                    seen_locktoken = 1;
+
+                    if (state_list->condition == DAV_IF_COND_NOT) {
+                        /*
+                        ** This state requires that the specified locktoken
+                        ** is NOT present on the resource. But we just found
+                        ** it. There is no way this state-list can now
+                        ** succeed, so go try another one.
+                        */
+                        reason =
+                            "a State-token was supplied, which used a "
+                            "\"Not\" condition. The State-token was found "
+                            "in the locks on this resource";
+                        goto state_list_failed;
+                    }
+
+                    /* condition == DAV_IF_COND_NORMAL */
+
+                    /* Validate auth_user:  If an authenticated user created
+                    ** the lock, only the same user may submit that locktoken
+                    ** to manipulate a resource.
+                    */
+                    if (lock->auth_user && 
+                        (!r->user ||
+                         strcmp(lock->auth_user, r->user))) {
+                        const char *errmsg;
+
+                        errmsg = apr_pstrcat(p, "User \"",
+                                            r->user, 
+                                            "\" submitted a locktoken created "
+                                            "by user \"",
+                                            lock->auth_user, "\".", NULL);
+                        return dav_new_error(p, HTTP_FORBIDDEN, 0, errmsg);
+                    }
+
+                    /*
+                    ** We just matched a specified State-Token to one of the
+                    ** resource's locktokens.
+                    **
+                    ** Break out of the lock scan -- we only needed to find
+                    ** one match (actually, there shouldn't be any other
+                    ** matches in the lock list).
+                    */
+                    num_matched = 1;
+                    break;
+                }
+
+                if (num_matched == 0
+                    && state_list->condition == DAV_IF_COND_NORMAL) {
+                    /*
+                    ** We had a NORMAL state, meaning that we should have
+                    ** found the State-Token within the locks on this
+                    ** resource. We didn't, so this state_list must fail.
+                    */
+                    reason =
+                        "a State-token was supplied, but it was not found "
+                        "in the locks on this resource.";
+                    goto state_list_failed;
+                }
+
+                break;
+
+            } /* switch */
+        } /* foreach ( state_list ) */
+
+        /*
+        ** We've checked every state in this state_list and none of them
+        ** have failed. Since all of them succeeded, then we have a matching
+        ** state list and we may be done.
+        **
+        ** The next requirement is that we have seen one of the resource's
+        ** locktokens (if any). If we have, then we can just exit. If we
+        ** haven't, then we need to keep looking.
+        */
+        if (seen_locktoken) {
+            /* woo hoo! */
+            return NULL;
+        }
+
+        /*
+        ** Haven't seen one. Let's break out of the search and just look
+        ** for a matching locktoken.
+        */
+        break;
+
+        /*
+        ** This label is used when we detect that a state_list is not
+        ** going to match this resource. We bust out and try the next
+        ** state_list.
+        */
+      state_list_failed:
+        ;
+
+    } /* foreach ( ifhdr_scan ) */
+
+    /*
+    ** The above loop exits for one of two reasons:
+    **   1) a state_list matched and seen_locktoken is false.
+    **   2) all if_header structures were scanned, without (1) occurring
+    */
+
+    if (ifhdr_scan == NULL) {
+        /*
+        ** We finished the loop without finding any matching state lists.
+        */
+
+        /*
+        ** If none of the state_lists apply to this resource, then we
+        ** may have succeeded. Note that this scenario implies a
+        ** tagged-list with no matching state_lists. If the If: header
+        ** was a no-tag-list, then it would have applied to this resource.
+        **
+        ** S9.4.2 states that when no state_lists apply, then the header
+        ** should be ignored.
+        **
+        ** If we saw one of the resource's locktokens, then we're done.
+        ** If we did not see a locktoken, then we fail.
+        */
+        if (num_that_apply == 0) {
+            if (seen_locktoken)
+                return NULL;
+
+            /*
+            ** We may have aborted the scan before seeing the locktoken.
+            ** Rescan the If: header to see if we can find the locktoken
+            ** somewhere.
+            **
+            ** Note that seen_locktoken == 0 implies lock_list != NULL
+            ** which implies locks_hooks != NULL.
+            */
+            if (dav_find_submitted_locktoken(if_header, lock_list,
+                                             locks_hooks)) {
+                /*
+                ** We found a match! We're set... none of the If: header
+                ** assertions apply (implicit success), and the If: header
+                ** specified the locktoken somewhere. We're done.
+                */
+                return NULL;
+            }
+
+            return dav_new_error(p, HTTP_LOCKED, 0 /* error_id */,
+                                 "This resource is locked and the \"If:\" "
+                                 "header did not specify one of the "
+                                 "locktokens for this resource's lock(s).");
+        }
+        /* else: one or more state_lists were applicable, but failed. */
+
+        /*
+        ** If the dummy_header did not match, then they specified an
+        ** incorrect token in the Lock-Token header. Forget whether the
+        ** If: statement matched or not... we'll tell them about the
+        ** bad Lock-Token first. That is considered a 400 (Bad Request).
+        */
+        if (if_header->dummy_header) {
+            return dav_new_error(p, HTTP_BAD_REQUEST, 0,
+                                 "The locktoken specified in the "
+                                 "\"Lock-Token:\" header did not specify one "
+                                 "of this resource's locktoken(s).");
+        }
+
+        if (reason == NULL) {
+            return dav_new_error(p, HTTP_PRECONDITION_FAILED, 0,
+                                 "The preconditions specified by the \"If:\" "
+                                 "header did not match this resource.");
+        }
+
+        return dav_new_error(p, HTTP_PRECONDITION_FAILED, 0,
+                             apr_psprintf(p,
+                                         "The precondition(s) specified by "
+                                         "the \"If:\" header did not match "
+                                         "this resource. At least one "
+                                         "failure is because: %s", reason));
+    }
+
+    /* assert seen_locktoken == 0 */
+
+    /*
+    ** ifhdr_scan != NULL implies we found a matching state_list.
+    **
+    ** Since we're still here, it also means that we have not yet found
+    ** one the resource's locktokens in the If: header.
+    **
+    ** Scan all the if_headers and states looking for one of this
+    ** resource's locktokens. Note that we need to go back and scan them
+    ** all -- we may have aborted a scan with a failure before we saw a
+    ** matching token.
+    **
+    ** Note that seen_locktoken == 0 implies lock_list != NULL which implies
+    ** locks_hooks != NULL.
+    */
+    if (dav_find_submitted_locktoken(if_header, lock_list, locks_hooks)) {
+        /*
+        ** We found a match! We're set... we have a matching state list,
+        ** and the If: header specified the locktoken somewhere. We're done.
+        */
+        return NULL;
+    }
+
+    /*
+    ** We had a matching state list, but the user agent did not specify one
+    ** of this resource's locktokens. Tell them so.
+    **
+    ** Note that we need to special-case the message on whether a "dummy"
+    ** header exists. If it exists, yet we didn't see a needed locktoken,
+    ** then that implies the dummy header (Lock-Token header) did NOT
+    ** specify one of this resource's locktokens. (this implies something
+    ** in the real If: header matched)
+    **
+    ** We want to note the 400 (Bad Request) in favor of a 423 (Locked).
+    */
+    if (if_header->dummy_header) {
+        return dav_new_error(p, HTTP_BAD_REQUEST, 0,
+                             "The locktoken specified in the "
+                             "\"Lock-Token:\" header did not specify one "
+                             "of this resource's locktoken(s).");
+    }
+
+    return dav_new_error(p, HTTP_LOCKED, 1 /* error_id */,
+                         "This resource is locked and the \"If:\" header "
+                         "did not specify one of the "
+                         "locktokens for this resource's lock(s).");
+}
+
+/* dav_validate_walker:  Walker callback function to validate resource state */
+static dav_error * dav_validate_walker(dav_walk_resource *wres, int calltype)
+{
+    dav_walker_ctx *ctx = wres->walk_ctx;
+    dav_error *err;
+
+    if ((err = dav_validate_resource_state(ctx->w.pool, wres->resource,
+                                           ctx->w.lockdb,
+                                           ctx->if_header, ctx->flags,
+                                           &ctx->work_buf, ctx->r)) == NULL) {
+        /* There was no error, so just bug out. */
+        return NULL;
+    }
+
+    /*
+    ** If we have a serious server error, or if the request itself failed,
+    ** then just return error (not a multistatus).
+    */
+    if (ap_is_HTTP_SERVER_ERROR(err->status)
+        || (*wres->resource->hooks->is_same_resource)(wres->resource,
+                                                      ctx->w.root)) {
+        /* ### maybe push a higher-level description? */
+        return err;
+    }
+
+    /* associate the error with the current URI */
+    dav_add_response(wres, err->status, NULL);
+
+    return NULL;
+}
+
+/*
+** dav_validate_request:  Validate if-headers (and check for locks) on:
+**    (1) r->filename @ depth;
+**    (2) Parent of r->filename if check_parent == 1
+**
+** The check of parent should be done when it is necessary to verify that
+** the parent collection will accept a new member (ie current resource
+** state is null).
+**
+** Return OK on successful validation.
+** On error, return appropriate HTTP_* code, and log error. If a multi-stat
+** error is necessary, response will point to it, else NULL.
+*/
+DAV_DECLARE(dav_error *) dav_validate_request(request_rec *r, 
+                                              dav_resource *resource,
+                                              int depth,
+                                              dav_locktoken *locktoken,
+                                              dav_response **response,
+                                              int flags,
+                                              dav_lockdb *lockdb)
+{
+    dav_error *err;
+    int result;
+    dav_if_header *if_header;
+    int lock_db_opened_locally = 0;
+    const dav_hooks_locks *locks_hooks = DAV_GET_HOOKS_LOCKS(r);
+    const dav_hooks_repository *repos_hooks = resource->hooks;
+    dav_buffer work_buf = { 0 };
+    dav_response *new_response;
+
+#if DAV_DEBUG
+    if (depth && response == NULL) {
+        /*
+        ** ### bleck. we can't return errors for other URIs unless we have
+        ** ### a "response" ptr.
+        */
+        return dav_new_error(r->pool, HTTP_INTERNAL_SERVER_ERROR, 0,
+                             "DESIGN ERROR: dav_validate_request called "
+                             "with depth>0, but no response ptr.");
+    }
+#endif
+
+    if (response != NULL)
+        *response = NULL;
+
+    /* Do the standard checks for conditional requests using 
+     * If-..-Since, If-Match etc */
+    if ((result = ap_meets_conditions(r)) != OK) {
+        /* ### fix this up... how? */
+        return dav_new_error(r->pool, result, 0, NULL);
+    }
+
+    /* always parse (and later process) the If: header */
+    if ((err = dav_process_if_header(r, &if_header)) != NULL) {
+        /* ### maybe add higher-level description */
+        return err;
+    }
+
+    /* If a locktoken was specified, create a dummy if_header with which
+     * to validate resources.  In the interim, figure out why DAV uses
+     * locktokens in an if-header without a Lock-Token header to refresh
+     * locks, but a Lock-Token header without an if-header to remove them.
+     */
+    if (locktoken != NULL) {
+        dav_if_header *ifhdr_new;
+
+        ifhdr_new = apr_pcalloc(r->pool, sizeof(*ifhdr_new));
+        ifhdr_new->uri = resource->uri;
+        ifhdr_new->uri_len = strlen(resource->uri);
+        ifhdr_new->dummy_header = 1;
+
+        ifhdr_new->state = apr_pcalloc(r->pool, sizeof(*ifhdr_new->state));
+        ifhdr_new->state->type = dav_if_opaquelock;
+        ifhdr_new->state->condition = DAV_IF_COND_NORMAL;
+        ifhdr_new->state->locktoken = locktoken;
+
+        ifhdr_new->next = if_header;
+        if_header = ifhdr_new;
+    }
+
+    /*
+    ** If necessary, open the lock database (read-only, lazily);
+    ** the validation process may need to retrieve or update lock info.
+    ** Otherwise, assume provided lockdb is valid and opened rw.
+    */
+    if (lockdb == NULL) {
+        if (locks_hooks != NULL) {
+            if ((err = (*locks_hooks->open_lockdb)(r, 0, 0, &lockdb)) != NULL) {
+                /* ### maybe insert higher-level comment */
+                return err;
+            }
+            lock_db_opened_locally = 1;
+        }
+    }
+
+    /* (1) Validate the specified resource, at the specified depth */
+    if (resource->exists && depth > 0) {
+        dav_walker_ctx ctx = { { 0 } };
+        dav_response *multi_status;
+
+        ctx.w.walk_type = DAV_WALKTYPE_NORMAL;
+        ctx.w.func = dav_validate_walker;
+        ctx.w.walk_ctx = &ctx;
+        ctx.w.pool = r->pool;
+        ctx.w.root = resource;
+
+        ctx.if_header = if_header;
+        ctx.r = r;
+        ctx.flags = flags;
+
+        if (lockdb != NULL) {
+            ctx.w.lockdb = lockdb;
+            ctx.w.walk_type |= DAV_WALKTYPE_LOCKNULL;
+        }
+
+        err = (*repos_hooks->walk)(&ctx.w, DAV_INFINITY, &multi_status);
+        if (err == NULL) {
+            *response = multi_status;;
+        }
+        /* else: implies a 5xx status code occurred. */
+    }
+    else {
+        err = dav_validate_resource_state(r->pool, resource, lockdb,
+                                          if_header, flags, &work_buf, r);
+    }
+
+    /* (2) Validate the parent resource if requested */
+    if (err == NULL && (flags & DAV_VALIDATE_PARENT)) {
+        dav_resource *parent_resource;
+
+        err = (*repos_hooks->get_parent_resource)(resource, &parent_resource);
+
+        if (err == NULL && parent_resource == NULL) {
+            err = dav_new_error(r->pool, HTTP_FORBIDDEN, 0,
+                                "Cannot access parent of repository root.");
+        }
+        else if (err == NULL) {
+            err = dav_validate_resource_state(r->pool, parent_resource, lockdb,
+                                              if_header,
+                                              flags | DAV_VALIDATE_IS_PARENT,
+                                              &work_buf, r);
+            
+            /*
+            ** This error occurred on the parent resource. This implies that
+            ** we have to create a multistatus response (to report the error
+            ** against a URI other than the Request-URI). "Convert" this error
+            ** into a multistatus response.
+            */
+            if (err != NULL) {
+                new_response = apr_pcalloc(r->pool, sizeof(*new_response));
+                
+                new_response->href = parent_resource->uri;
+                new_response->status = err->status;
+                new_response->desc =
+                    "A validation error has occurred on the parent resource, "
+                    "preventing the operation on the resource specified by "
+                    "the Request-URI.";
+                if (err->desc != NULL) {
+                    new_response->desc = apr_pstrcat(r->pool,
+                                                    new_response->desc,
+                                                    " The error was: ",
+                                                    err->desc, NULL);
+                }
+                
+                /* assert: DAV_VALIDATE_PARENT implies response != NULL */
+                new_response->next = *response;
+                *response = new_response;
+                
+                err = NULL;
+            }
+        }
+    }
+
+    if (lock_db_opened_locally)
+        (*locks_hooks->close_lockdb)(lockdb);
+
+    /*
+    ** If we don't have a (serious) error, and we have multistatus responses,
+    ** then we need to construct an "error". This error will be the overall
+    ** status returned, and the multistatus responses will go into its body.
+    **
+    ** For certain methods, the overall error will be a 424. The default is
+    ** to construct a standard 207 response.
+    */
+    if (err == NULL && response != NULL && *response != NULL) {
+        apr_text *propstat = NULL;
+
+        if ((flags & DAV_VALIDATE_USE_424) != 0) {
+            /* manufacture a 424 error to hold the multistatus response(s) */
+            return dav_new_error(r->pool, HTTP_FAILED_DEPENDENCY, 0,
+                                 "An error occurred on another resource, "
+                                 "preventing the requested operation on "
+                                 "this resource.");
+        }
+
+        /*
+        ** Whatever caused the error, the Request-URI should have a 424
+        ** associated with it since we cannot complete the method.
+        **
+        ** For a LOCK operation, insert an empty DAV:lockdiscovery property.
+        ** For other methods, return a simple 424.
+        */
+        if ((flags & DAV_VALIDATE_ADD_LD) != 0) {
+            propstat = apr_pcalloc(r->pool, sizeof(*propstat));
+            propstat->text =
+                "<D:propstat>" DEBUG_CR
+                "<D:prop><D:lockdiscovery/></D:prop>" DEBUG_CR
+                "<D:status>HTTP/1.1 424 Failed Dependency</D:status>" DEBUG_CR
+                "</D:propstat>" DEBUG_CR;
+        }
+
+        /* create the 424 response */
+        new_response = apr_pcalloc(r->pool, sizeof(*new_response));
+        new_response->href = resource->uri;
+        new_response->status = HTTP_FAILED_DEPENDENCY;
+        new_response->propresult.propstats = propstat;
+        new_response->desc =
+            "An error occurred on another resource, preventing the "
+            "requested operation on this resource.";
+
+        new_response->next = *response;
+        *response = new_response;
+
+        /* manufacture a 207 error for the multistatus response(s) */
+        return dav_new_error(r->pool, HTTP_MULTI_STATUS, 0,
+                             "Error(s) occurred on resources during the "
+                             "validation process.");
+    }
+
+    return err;
+}
+
+/* dav_get_locktoken_list:
+ *
+ * Sets ltl to a locktoken_list of all positive locktokens in header,
+ * else NULL if no If-header, or no positive locktokens.
+ */
+DAV_DECLARE(dav_error *) dav_get_locktoken_list(request_rec *r,
+                                                dav_locktoken_list **ltl) 
+{
+    dav_error *err;
+    dav_if_header *if_header;
+    dav_if_state_list *if_state;
+    dav_locktoken_list *lock_token = NULL;                
+        
+    *ltl = NULL;
+
+    if ((err = dav_process_if_header(r, &if_header)) != NULL) {
+        /* ### add a higher-level description? */
+        return err;
+    }
+                         
+    while (if_header != NULL) {
+        if_state = if_header->state;        /* Begining of the if_state linked list */
+        while (if_state != NULL)        {
+            if (if_state->condition == DAV_IF_COND_NORMAL
+                && if_state->type == dav_if_opaquelock) {
+                lock_token = apr_pcalloc(r->pool, sizeof(dav_locktoken_list));
+                lock_token->locktoken = if_state->locktoken;
+                lock_token->next = *ltl;
+                *ltl = lock_token;
+            }
+            if_state = if_state->next; 
+        }
+        if_header = if_header->next;
+    }
+    if (*ltl == NULL) {
+        /* No nodes added */
+        return dav_new_error(r->pool, HTTP_BAD_REQUEST, DAV_ERR_IF_ABSENT,
+                             "No locktokens were specified in the \"If:\" "
+                             "header, so the refresh could not be performed.");
+    }
+
+    return NULL;
+}
+
+#if 0 /* not needed right now... */
+
+static const char *strip_white(const char *s, apr_pool_t *pool)
+{
+    apr_size_t idx;
+
+    /* trim leading whitespace */
+    while (apr_isspace(*s))     /* assume: return false for '\0' */
+        ++s;
+
+    /* trim trailing whitespace */
+    idx = strlen(s) - 1;
+    if (apr_isspace(s[idx])) {
+        char *s2 = apr_pstrdup(pool, s);
+
+        while (apr_isspace(s2[idx]) && idx > 0)
+            --idx;
+        s2[idx + 1] = '\0';
+        return s2;
+    }
+
+    return s;
+}
+#endif
+
+#define DAV_LABEL_HDR "Label"
+
+/* dav_add_vary_header
+ *
+ * If there were any headers in the request which require a Vary header
+ * in the response, add it.
+ */
+DAV_DECLARE(void) dav_add_vary_header(request_rec *in_req,
+                                      request_rec *out_req,
+                                      const dav_resource *resource)
+{
+    const dav_hooks_vsn *vsn_hooks = DAV_GET_HOOKS_VSN(in_req);
+
+    /* ### this is probably all wrong... I think there is a function in
+       ### the Apache API to add things to the Vary header. need to check */
+
+    /* Only versioning headers require a Vary response header,
+     * so only do this check if there is a versioning provider */
+    if (vsn_hooks != NULL) {
+        const char *target = apr_table_get(in_req->headers_in, DAV_LABEL_HDR);
+        const char *vary = apr_table_get(out_req->headers_out, "Vary");
+
+        /* If Target-Selector specified, add it to the Vary header */
+        if (target != NULL) {
+            if (vary == NULL)
+                vary = DAV_LABEL_HDR;
+            else
+                vary = apr_pstrcat(out_req->pool, vary, "," DAV_LABEL_HDR,
+                                   NULL);
+
+            apr_table_setn(out_req->headers_out, "Vary", vary);
+        }
+    }
+}
+
+/* dav_can_auto_checkout
+ *
+ * Determine whether auto-checkout is enabled for a resource.
+ * r - the request_rec
+ * resource - the resource
+ * auto_version - the value of the auto_versionable hook for the resource
+ * lockdb - pointer to lock database (opened if necessary)
+ * auto_checkout - set to 1 if auto-checkout enabled
+ */
+static dav_error * dav_can_auto_checkout(
+    request_rec *r,                                         
+    dav_resource *resource,
+    dav_auto_version auto_version,
+    dav_lockdb **lockdb,
+    int *auto_checkout)
+{
+    dav_error *err;
+    dav_lock *lock_list;
+
+    *auto_checkout = 0;
+
+    if (auto_version == DAV_AUTO_VERSION_ALWAYS) {
+        *auto_checkout = 1;
+    }
+    else if (auto_version == DAV_AUTO_VERSION_LOCKED) {
+        if (*lockdb == NULL) {
+            const dav_hooks_locks *locks_hooks = DAV_GET_HOOKS_LOCKS(r);
+
+            if (locks_hooks == NULL) {
+                return dav_new_error(r->pool, HTTP_INTERNAL_SERVER_ERROR, 0,
+                                     "Auto-checkout is only enabled for locked resources, "
+                                     "but there is no lock provider.");
+            }
+
+            if ((err = (*locks_hooks->open_lockdb)(r, 0, 0, lockdb)) != NULL) {
+                return dav_push_error(r->pool, HTTP_INTERNAL_SERVER_ERROR, 0,
+                                      "Cannot open lock database to determine "
+                                      "auto-versioning behavior.",
+                                      err);
+            }
+        }
+
+        if ((err = dav_lock_query(*lockdb, resource, &lock_list)) != NULL) {
+            return dav_push_error(r->pool,
+                                  HTTP_INTERNAL_SERVER_ERROR, 0,
+                                  "The locks could not be queried for "
+                                  "determining auto-versioning behavior.",
+                                  err);
+        }
+
+        if (lock_list != NULL)
+            *auto_checkout = 1;
+    }
+
+    return NULL;
+}
+
+/* see mod_dav.h for docco */
+DAV_DECLARE(dav_error *) dav_auto_checkout(
+    request_rec *r,
+    dav_resource *resource,
+    int parent_only,
+    dav_auto_version_info *av_info)
+{
+    const dav_hooks_vsn *vsn_hooks = DAV_GET_HOOKS_VSN(r);
+    dav_lockdb *lockdb = NULL;
+    dav_error *err = NULL;
+
+    /* Initialize results */
+    memset(av_info, 0, sizeof(*av_info));
+
+    /* if no versioning provider, just return */
+    if (vsn_hooks == NULL)
+        return NULL;
+
+    /* check parent resource if requested or if resource must be created */
+    if (!resource->exists || parent_only) {
+        dav_resource *parent;
+
+        if ((err = (*resource->hooks->get_parent_resource)(resource,
+                                                           &parent)) != NULL)
+            goto done;
+
+        if (parent == NULL || !parent->exists) {
+            err = dav_new_error(r->pool, HTTP_CONFLICT, 0,
+                                apr_psprintf(r->pool,
+                                            "Missing one or more intermediate "
+                                            "collections. Cannot create resource %s.",
+                                            ap_escape_html(r->pool, resource->uri)));
+            goto done;
+        }
+
+        av_info->parent_resource = parent;
+
+        /* if parent versioned and not checked out, see if it can be */
+        if (parent->versioned && !parent->working) {
+            int checkout_parent;
+
+            if ((err = dav_can_auto_checkout(r, parent,
+                                             (*vsn_hooks->auto_versionable)(parent),
+                                             &lockdb, &checkout_parent))
+                != NULL) {
+                goto done;
+            }
+
+            if (!checkout_parent) {
+                err = dav_new_error(r->pool, HTTP_CONFLICT, 0,
+                                    "<DAV:cannot-modify-checked-in-parent>");
+                goto done;
+            }
+
+            /* Try to checkout the parent collection.
+             * Note that auto-versioning can only be applied to a version selector,
+             * so no separate working resource will be created.
+             */
+            if ((err = (*vsn_hooks->checkout)(parent, 1 /*auto_checkout*/,
+                                              0, 0, 0, NULL, NULL))
+                != NULL)
+            {
+                err = dav_push_error(r->pool, HTTP_CONFLICT, 0,
+                                     apr_psprintf(r->pool,
+                                                 "Unable to auto-checkout parent collection. "
+                                                 "Cannot create resource %s.",
+                                                 ap_escape_html(r->pool, resource->uri)),
+                                     err);
+                goto done;
+            }
+
+            /* remember that parent was checked out */
+            av_info->parent_checkedout = 1;
+        }
+    }
+
+    /* if only checking parent, we're done */
+    if (parent_only)
+        goto done;
+
+    /* if creating a new resource, see if it should be version-controlled */
+    if (!resource->exists
+        && (*vsn_hooks->auto_versionable)(resource) == DAV_AUTO_VERSION_ALWAYS) {
+
+        if ((err = (*vsn_hooks->vsn_control)(resource, NULL)) != NULL) {
+            err = dav_push_error(r->pool, HTTP_CONFLICT, 0,
+                                 apr_psprintf(r->pool,
+                                             "Unable to create versioned resource %s.",
+                                             ap_escape_html(r->pool, resource->uri)),
+                                 err);
+            goto done;
+        }
+
+        /* remember that resource was created */
+        av_info->resource_versioned = 1;
+    }
+
+    /* if resource is versioned, make sure it is checked out */
+    if (resource->versioned && !resource->working) {
+        int checkout_resource;
+
+        if ((err = dav_can_auto_checkout(r, resource,
+                                         (*vsn_hooks->auto_versionable)(resource),
+                                         &lockdb, &checkout_resource)) != NULL) {
+            goto done;
+        }
+
+        if (!checkout_resource) {
+            err = dav_new_error(r->pool, HTTP_CONFLICT, 0,
+                                "<DAV:cannot-modify-version-controlled-content>");
+            goto done;
+        }
+
+        /* Auto-versioning can only be applied to version selectors, so
+         * no separate working resource will be created. */
+        if ((err = (*vsn_hooks->checkout)(resource, 1 /*auto_checkout*/,
+                                          0, 0, 0, NULL, NULL))
+            != NULL)
+        {
+            err = dav_push_error(r->pool, HTTP_CONFLICT, 0,
+                                 apr_psprintf(r->pool,
+                                             "Unable to checkout resource %s.",
+                                             ap_escape_html(r->pool, resource->uri)),
+                                 err);
+            goto done;
+        }
+
+        /* remember that resource was checked out */
+        av_info->resource_checkedout = 1;
+    }
+
+done:
+
+    /* make sure lock database is closed */
+    if (lockdb != NULL)
+        (*lockdb->hooks->close_lockdb)(lockdb);
+
+    /* if an error occurred, undo any auto-versioning operations already done */
+    if (err != NULL) {
+        dav_auto_checkin(r, resource, 1 /*undo*/, 0 /*unlock*/, av_info);
+        return err;
+    }
+
+    return NULL;
+}
+
+/* see mod_dav.h for docco */
+DAV_DECLARE(dav_error *) dav_auto_checkin(
+    request_rec *r,
+    dav_resource *resource,
+    int undo,
+    int unlock,
+    dav_auto_version_info *av_info)
+{
+    const dav_hooks_vsn *vsn_hooks = DAV_GET_HOOKS_VSN(r);
+    dav_error *err = NULL;
+    dav_auto_version auto_version;
+
+    /* If no versioning provider, this is a no-op */
+    if (vsn_hooks == NULL)
+        return NULL;
+
+    /* If undoing auto-checkouts, then do uncheckouts */
+    if (undo) {
+        if (resource != NULL) {
+            if (av_info->resource_checkedout) {
+                if ((err = (*vsn_hooks->uncheckout)(resource)) != NULL) {
+                    return dav_push_error(r->pool, HTTP_INTERNAL_SERVER_ERROR, 0,
+                                          apr_psprintf(r->pool,
+                                                      "Unable to undo auto-checkout "
+                                                      "of resource %s.",
+                                                      ap_escape_html(r->pool, resource->uri)),
+                                          err);
+                }
+            }
+
+            if (av_info->resource_versioned) {
+                dav_response *response;
+
+                /* ### should we do anything with the response? */
+                if ((err = (*resource->hooks->remove_resource)(resource,
+                                                               &response)) != NULL) {
+                    return dav_push_error(r->pool, HTTP_INTERNAL_SERVER_ERROR, 0,
+                                          apr_psprintf(r->pool,
+                                                      "Unable to undo auto-version-control "
+                                                      "of resource %s.",
+                                                      ap_escape_html(r->pool, resource->uri)),
+                                          err);
+                }
+            }
+        }
+
+        if (av_info->parent_resource != NULL && av_info->parent_checkedout) {
+            if ((err = (*vsn_hooks->uncheckout)(av_info->parent_resource)) != NULL) {
+                return dav_push_error(r->pool, HTTP_INTERNAL_SERVER_ERROR, 0,
+                                      apr_psprintf(r->pool,
+                                                  "Unable to undo auto-checkout "
+                                                  "of parent collection %s.",
+                                                  ap_escape_html(r->pool, av_info->parent_resource->uri)),
+                                      err);
+            }
+        }
+
+        return NULL;
+    }
+
+    /* If the resource was checked out, and auto-checkin is enabled,
+     * then check it in.
+     */
+    if (resource != NULL && resource->working
+        && (unlock || av_info->resource_checkedout)) {
+
+        auto_version = (*vsn_hooks->auto_versionable)(resource);
+
+        if (auto_version == DAV_AUTO_VERSION_ALWAYS ||
+            (unlock && (auto_version == DAV_AUTO_VERSION_LOCKED))) {
+
+            if ((err = (*vsn_hooks->checkin)(resource,
+                                             0 /*keep_checked_out*/, NULL))
+                != NULL) {
+                return dav_push_error(r->pool, HTTP_INTERNAL_SERVER_ERROR, 0,
+                                      apr_psprintf(r->pool,
+                                                  "Unable to auto-checkin resource %s.",
+                                                  ap_escape_html(r->pool, resource->uri)),
+                                      err);
+            }
+        }
+    }
+
+    /* If parent resource was checked out, and auto-checkin is enabled,
+     * then check it in.
+     */
+    if (!unlock
+        && av_info->parent_checkedout
+        && av_info->parent_resource != NULL
+        && av_info->parent_resource->working) {
+
+        auto_version = (*vsn_hooks->auto_versionable)(av_info->parent_resource);
+
+        if (auto_version == DAV_AUTO_VERSION_ALWAYS) {
+            if ((err = (*vsn_hooks->checkin)(av_info->parent_resource,
+                                             0 /*keep_checked_out*/, NULL))
+                != NULL) {
+                return dav_push_error(r->pool, HTTP_INTERNAL_SERVER_ERROR, 0,
+                                      apr_psprintf(r->pool,
+                                                  "Unable to auto-checkin parent collection %s.",
+                                                  ap_escape_html(r->pool, av_info->parent_resource->uri)),
+                                                  err);
+            }
+        }
+    }
+
+    return NULL;
+}