Adding upstream version 2.4.57.upstream/2.4.57

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1983 insertions, 0 deletions

diff --git a/modules/aaa/mod_auth_digest.c b/modules/aaa/mod_auth_digest.c
new file mode 100644
index 0000000..791cec2
--- /dev/null
+++ b/modules/aaa/mod_auth_digest.c
@@ -0,0 +1,1983 @@
+/* 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.
+ */
+
+/*
+ * mod_auth_digest: MD5 digest authentication
+ *
+ * Originally by Alexei Kosut <akosut@nueva.pvt.k12.ca.us>
+ * Updated to RFC-2617 by Ronald Tschal�r <ronald@innovation.ch>
+ * based on mod_auth, by Rob McCool and Robert S. Thau
+ *
+ * This module an updated version of modules/standard/mod_digest.c
+ * It is still fairly new and problems may turn up - submit problem
+ * reports to the Apache bug-database, or send them directly to me
+ * at ronald@innovation.ch.
+ *
+ * Open Issues:
+ *   - qop=auth-int (when streams and trailer support available)
+ *   - nonce-format configurability
+ *   - Proxy-Authorization-Info header is set by this module, but is
+ *     currently ignored by mod_proxy (needs patch to mod_proxy)
+ *   - The source of the secret should be run-time directive (with server
+ *     scope: RSRC_CONF)
+ *   - shared-mem not completely tested yet. Seems to work ok for me,
+ *     but... (definitely won't work on Windoze)
+ *   - Sharing a realm among multiple servers has following problems:
+ *     o Server name and port can't be included in nonce-hash
+ *       (we need two nonce formats, which must be configured explicitly)
+ *     o Nonce-count check can't be for equal, or then nonce-count checking
+ *       must be disabled. What we could do is the following:
+ *       (expected < received) ? set expected = received : issue error
+ *       The only problem is that it allows replay attacks when somebody
+ *       captures a packet sent to one server and sends it to another
+ *       one. Should we add "AuthDigestNcCheck Strict"?
+ *   - expired nonces give amaya fits.
+ *   - MD5-sess and auth-int are not yet implemented. An incomplete
+ *     implementation has been removed and can be retrieved from svn history.
+ */
+
+#include "apr_sha1.h"
+#include "apr_base64.h"
+#include "apr_lib.h"
+#include "apr_time.h"
+#include "apr_errno.h"
+#include "apr_global_mutex.h"
+#include "apr_strings.h"
+
+#define APR_WANT_STRFUNC
+#include "apr_want.h"
+
+#include "ap_config.h"
+#include "httpd.h"
+#include "http_config.h"
+#include "http_core.h"
+#include "http_request.h"
+#include "http_log.h"
+#include "http_protocol.h"
+#include "apr_uri.h"
+#include "util_md5.h"
+#include "util_mutex.h"
+#include "apr_shm.h"
+#include "apr_rmm.h"
+#include "ap_provider.h"
+
+#include "mod_auth.h"
+
+#if APR_HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+
+/* struct to hold the configuration info */
+
+typedef struct digest_config_struct {
+    const char  *dir_name;
+    authn_provider_list *providers;
+    const char  *realm;
+    apr_array_header_t *qop_list;
+    apr_sha1_ctx_t  nonce_ctx;
+    apr_time_t    nonce_lifetime;
+    int          check_nc;
+    const char  *algorithm;
+    char        *uri_list;
+} digest_config_rec;
+
+
+#define DFLT_ALGORITHM  "MD5"
+
+#define DFLT_NONCE_LIFE apr_time_from_sec(300)
+#define NEXTNONCE_DELTA apr_time_from_sec(30)
+
+
+#define NONCE_TIME_LEN  (((sizeof(apr_time_t)+2)/3)*4)
+#define NONCE_HASH_LEN  (2*APR_SHA1_DIGESTSIZE)
+#define NONCE_LEN       (int )(NONCE_TIME_LEN + NONCE_HASH_LEN)
+
+#define SECRET_LEN          20
+#define RETAINED_DATA_ID    "mod_auth_digest"
+
+
+/* client list definitions */
+
+typedef struct hash_entry {
+    unsigned long      key;                     /* the key for this entry    */
+    struct hash_entry *next;                    /* next entry in the bucket  */
+    unsigned long      nonce_count;             /* for nonce-count checking  */
+    char               last_nonce[NONCE_LEN+1]; /* for one-time nonce's      */
+} client_entry;
+
+static struct hash_table {
+    client_entry  **table;
+    unsigned long   tbl_len;
+    unsigned long   num_entries;
+    unsigned long   num_created;
+    unsigned long   num_removed;
+    unsigned long   num_renewed;
+} *client_list;
+
+
+/* struct to hold a parsed Authorization header */
+
+enum hdr_sts { NO_HEADER, NOT_DIGEST, INVALID, VALID };
+
+typedef struct digest_header_struct {
+    const char           *scheme;
+    const char           *realm;
+    const char           *username;
+          char           *nonce;
+    const char           *uri;
+    const char           *method;
+    const char           *digest;
+    const char           *algorithm;
+    const char           *cnonce;
+    const char           *opaque;
+    unsigned long         opaque_num;
+    const char           *message_qop;
+    const char           *nonce_count;
+    /* the following fields are not (directly) from the header */
+    const char           *raw_request_uri;
+    apr_uri_t            *psd_request_uri;
+    apr_time_t            nonce_time;
+    enum hdr_sts          auth_hdr_sts;
+    int                   needed_auth;
+    const char           *ha1;
+    client_entry         *client;
+} digest_header_rec;
+
+
+/* (mostly) nonce stuff */
+
+typedef union time_union {
+    apr_time_t    time;
+    unsigned char arr[sizeof(apr_time_t)];
+} time_rec;
+
+static unsigned char *secret;
+
+/* client-list, opaque, and one-time-nonce stuff */
+
+static apr_shm_t      *client_shm =  NULL;
+static apr_rmm_t      *client_rmm = NULL;
+static unsigned long  *opaque_cntr;
+static apr_time_t     *otn_counter;     /* one-time-nonce counter */
+static apr_global_mutex_t *client_lock = NULL;
+static apr_global_mutex_t *opaque_lock = NULL;
+static const char     *client_mutex_type = "authdigest-client";
+static const char     *opaque_mutex_type = "authdigest-opaque";
+static const char     *client_shm_filename;
+
+#define DEF_SHMEM_SIZE  1000L           /* ~ 12 entries */
+#define DEF_NUM_BUCKETS 15L
+#define HASH_DEPTH      5
+
+static apr_size_t shmem_size  = DEF_SHMEM_SIZE;
+static unsigned long num_buckets = DEF_NUM_BUCKETS;
+
+
+module AP_MODULE_DECLARE_DATA auth_digest_module;
+
+/*
+ * initialization code
+ */
+
+static apr_status_t cleanup_tables(void *not_used)
+{
+    ap_log_error(APLOG_MARK, APLOG_INFO, 0, NULL, APLOGNO(01756)
+                  "cleaning up shared memory");
+
+    if (client_rmm) {
+        apr_rmm_destroy(client_rmm);
+        client_rmm = NULL;
+    }
+
+    if (client_shm) {
+        apr_shm_destroy(client_shm);
+        client_shm = NULL;
+    }
+
+    if (client_lock) {
+        apr_global_mutex_destroy(client_lock);
+        client_lock = NULL;
+    }
+
+    if (opaque_lock) {
+        apr_global_mutex_destroy(opaque_lock);
+        opaque_lock = NULL;
+    }
+
+    client_list = NULL;
+
+    return APR_SUCCESS;
+}
+
+static void log_error_and_cleanup(char *msg, apr_status_t sts, server_rec *s)
+{
+    ap_log_error(APLOG_MARK, APLOG_ERR, sts, s, APLOGNO(01760)
+                 "%s - all nonce-count checking and one-time nonces "
+                 "disabled", msg);
+
+    cleanup_tables(NULL);
+}
+
+/* RMM helper functions that behave like single-step malloc/free. */
+
+static void *rmm_malloc(apr_rmm_t *rmm, apr_size_t size)
+{
+    apr_rmm_off_t offset = apr_rmm_malloc(rmm, size);
+
+    if (!offset) {
+        return NULL;
+    }
+
+    return apr_rmm_addr_get(rmm, offset);
+}
+
+static apr_status_t rmm_free(apr_rmm_t *rmm, void *alloc)
+{
+    apr_rmm_off_t offset = apr_rmm_offset_get(rmm, alloc);
+
+    return apr_rmm_free(rmm, offset);
+}
+
+#if APR_HAS_SHARED_MEMORY
+
+static int initialize_tables(server_rec *s, apr_pool_t *ctx)
+{
+    unsigned long idx;
+    apr_status_t   sts;
+
+    /* set up client list */
+
+    /* Create the shared memory segment */
+
+    client_shm = NULL;
+    client_rmm = NULL;
+    client_lock = NULL;
+    opaque_lock = NULL;
+    client_list = NULL;
+
+    /*
+     * Create a unique filename using our pid. This information is
+     * stashed in the global variable so the children inherit it.
+     */
+    client_shm_filename = ap_runtime_dir_relative(ctx, "authdigest_shm");
+    client_shm_filename = ap_append_pid(ctx, client_shm_filename, ".");
+
+    /* Use anonymous shm by default, fall back on name-based. */
+    sts = apr_shm_create(&client_shm, shmem_size, NULL, ctx);
+    if (APR_STATUS_IS_ENOTIMPL(sts)) {
+        /* For a name-based segment, remove it first in case of a
+         * previous unclean shutdown. */
+        apr_shm_remove(client_shm_filename, ctx);
+
+        /* Now create that segment */
+        sts = apr_shm_create(&client_shm, shmem_size,
+                            client_shm_filename, ctx);
+    }
+
+    if (APR_SUCCESS != sts) {
+        ap_log_error(APLOG_MARK, APLOG_ERR, sts, s, APLOGNO(01762)
+                     "Failed to create shared memory segment on file %s",
+                     client_shm_filename);
+        log_error_and_cleanup("failed to initialize shm", sts, s);
+        return HTTP_INTERNAL_SERVER_ERROR;
+    }
+
+    sts = apr_rmm_init(&client_rmm,
+                       NULL, /* no lock, we'll do the locking ourselves */
+                       apr_shm_baseaddr_get(client_shm),
+                       shmem_size, ctx);
+    if (sts != APR_SUCCESS) {
+        log_error_and_cleanup("failed to initialize rmm", sts, s);
+        return !OK;
+    }
+
+    client_list = rmm_malloc(client_rmm, sizeof(*client_list) +
+                                         sizeof(client_entry *) * num_buckets);
+    if (!client_list) {
+        log_error_and_cleanup("failed to allocate shared memory", -1, s);
+        return !OK;
+    }
+    client_list->table = (client_entry**) (client_list + 1);
+    for (idx = 0; idx < num_buckets; idx++) {
+        client_list->table[idx] = NULL;
+    }
+    client_list->tbl_len     = num_buckets;
+    client_list->num_entries = 0;
+
+    sts = ap_global_mutex_create(&client_lock, NULL, client_mutex_type, NULL,
+                                 s, ctx, 0);
+    if (sts != APR_SUCCESS) {
+        log_error_and_cleanup("failed to create lock (client_lock)", sts, s);
+        return !OK;
+    }
+
+
+    /* setup opaque */
+
+    opaque_cntr = rmm_malloc(client_rmm, sizeof(*opaque_cntr));
+    if (opaque_cntr == NULL) {
+        log_error_and_cleanup("failed to allocate shared memory", -1, s);
+        return !OK;
+    }
+    *opaque_cntr = 1UL;
+
+    sts = ap_global_mutex_create(&opaque_lock, NULL, opaque_mutex_type, NULL,
+                                 s, ctx, 0);
+    if (sts != APR_SUCCESS) {
+        log_error_and_cleanup("failed to create lock (opaque_lock)", sts, s);
+        return !OK;
+    }
+
+
+    /* setup one-time-nonce counter */
+
+    otn_counter = rmm_malloc(client_rmm, sizeof(*otn_counter));
+    if (otn_counter == NULL) {
+        log_error_and_cleanup("failed to allocate shared memory", -1, s);
+        return !OK;
+    }
+    *otn_counter = 0;
+    /* no lock here */
+
+
+    /* success */
+    return OK;
+}
+
+#endif /* APR_HAS_SHARED_MEMORY */
+
+static int pre_init(apr_pool_t *pconf, apr_pool_t *plog, apr_pool_t *ptemp)
+{
+    apr_status_t rv;
+    void *retained;
+
+    rv = ap_mutex_register(pconf, client_mutex_type, NULL, APR_LOCK_DEFAULT, 0);
+    if (rv != APR_SUCCESS)
+        return !OK;
+    rv = ap_mutex_register(pconf, opaque_mutex_type, NULL, APR_LOCK_DEFAULT, 0);
+    if (rv != APR_SUCCESS)
+        return !OK;
+
+    retained = ap_retained_data_get(RETAINED_DATA_ID);
+    if (retained == NULL) {
+        retained = ap_retained_data_create(RETAINED_DATA_ID, SECRET_LEN);
+        ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, NULL, APLOGNO(01757)
+                     "generating secret for digest authentication");
+#if APR_HAS_RANDOM
+        rv = apr_generate_random_bytes(retained, SECRET_LEN);
+#else
+#error APR random number support is missing
+#endif
+        if (rv != APR_SUCCESS) {
+            ap_log_error(APLOG_MARK, APLOG_CRIT, rv, NULL, APLOGNO(01758)
+                         "error generating secret");
+            return !OK;
+        }
+    }
+    secret = retained;
+    return OK;
+}
+
+static int initialize_module(apr_pool_t *p, apr_pool_t *plog,
+                             apr_pool_t *ptemp, server_rec *s)
+{
+    /* initialize_module() will be called twice, and if it's a DSO
+     * then all static data from the first call will be lost. Only
+     * set up our static data on the second call. */
+    if (ap_state_query(AP_SQ_MAIN_STATE) == AP_SQ_MS_CREATE_PRE_CONFIG)
+        return OK;
+
+#if APR_HAS_SHARED_MEMORY
+    /* Note: this stuff is currently fixed for the lifetime of the server,
+     * i.e. even across restarts. This means that A) any shmem-size
+     * configuration changes are ignored, and B) certain optimizations,
+     * such as only allocating the smallest necessary entry for each
+     * client, can't be done. However, the alternative is a nightmare:
+     * we can't call apr_shm_destroy on a graceful restart because there
+     * will be children using the tables, and we also don't know when the
+     * last child dies. Therefore we can never clean up the old stuff,
+     * creating a creeping memory leak.
+     */
+    if (initialize_tables(s, p) != OK) {
+        return !OK;
+    }
+#endif  /* APR_HAS_SHARED_MEMORY */
+    return OK;
+}
+
+static void initialize_child(apr_pool_t *p, server_rec *s)
+{
+    apr_status_t sts;
+
+    if (!client_shm) {
+        return;
+    }
+
+    /* Get access to rmm in child */
+    sts = apr_rmm_attach(&client_rmm,
+                         NULL,
+                         apr_shm_baseaddr_get(client_shm),
+                         p);
+    if (sts != APR_SUCCESS) {
+        log_error_and_cleanup("failed to attach to rmm", sts, s);
+        return;
+    }
+
+    sts = apr_global_mutex_child_init(&client_lock,
+                                      apr_global_mutex_lockfile(client_lock),
+                                      p);
+    if (sts != APR_SUCCESS) {
+        log_error_and_cleanup("failed to create lock (client_lock)", sts, s);
+        return;
+    }
+    sts = apr_global_mutex_child_init(&opaque_lock,
+                                      apr_global_mutex_lockfile(opaque_lock),
+                                      p);
+    if (sts != APR_SUCCESS) {
+        log_error_and_cleanup("failed to create lock (opaque_lock)", sts, s);
+        return;
+    }
+}
+
+/*
+ * configuration code
+ */
+
+static void *create_digest_dir_config(apr_pool_t *p, char *dir)
+{
+    digest_config_rec *conf;
+
+    if (dir == NULL) {
+        return NULL;
+    }
+
+    conf = (digest_config_rec *) apr_pcalloc(p, sizeof(digest_config_rec));
+    if (conf) {
+        conf->qop_list       = apr_array_make(p, 2, sizeof(char *));
+        conf->nonce_lifetime = DFLT_NONCE_LIFE;
+        conf->dir_name       = apr_pstrdup(p, dir);
+        conf->algorithm      = DFLT_ALGORITHM;
+    }
+
+    return conf;
+}
+
+static const char *set_realm(cmd_parms *cmd, void *config, const char *realm)
+{
+    digest_config_rec *conf = (digest_config_rec *) config;
+#ifdef AP_DEBUG
+    int i;
+
+    /* check that we got random numbers */
+    for (i = 0; i < SECRET_LEN; i++) {
+        if (secret[i] != 0)
+            break;
+    }
+    ap_assert(i < SECRET_LEN);
+#endif
+
+    /* The core already handles the realm, but it's just too convenient to
+     * grab it ourselves too and cache some setups. However, we need to
+     * let the core get at it too, which is why we decline at the end -
+     * this relies on the fact that http_core is last in the list.
+     */
+    conf->realm = realm;
+
+    /* we precompute the part of the nonce hash that is constant (well,
+     * the host:port would be too, but that varies for .htaccess files
+     * and directives outside a virtual host section)
+     */
+    apr_sha1_init(&conf->nonce_ctx);
+    apr_sha1_update_binary(&conf->nonce_ctx, secret, SECRET_LEN);
+    apr_sha1_update_binary(&conf->nonce_ctx, (const unsigned char *) realm,
+                           strlen(realm));
+
+    return DECLINE_CMD;
+}
+
+static const char *add_authn_provider(cmd_parms *cmd, void *config,
+                                      const char *arg)
+{
+    digest_config_rec *conf = (digest_config_rec*)config;
+    authn_provider_list *newp;
+
+    newp = apr_pcalloc(cmd->pool, sizeof(authn_provider_list));
+    newp->provider_name = arg;
+
+    /* lookup and cache the actual provider now */
+    newp->provider = ap_lookup_provider(AUTHN_PROVIDER_GROUP,
+                                        newp->provider_name,
+                                        AUTHN_PROVIDER_VERSION);
+
+    if (newp->provider == NULL) {
+       /* by the time they use it, the provider should be loaded and
+           registered with us. */
+        return apr_psprintf(cmd->pool,
+                            "Unknown Authn provider: %s",
+                            newp->provider_name);
+    }
+
+    if (!newp->provider->get_realm_hash) {
+        /* if it doesn't provide the appropriate function, reject it */
+        return apr_psprintf(cmd->pool,
+                            "The '%s' Authn provider doesn't support "
+                            "Digest Authentication", newp->provider_name);
+    }
+
+    /* Add it to the list now. */
+    if (!conf->providers) {
+        conf->providers = newp;
+    }
+    else {
+        authn_provider_list *last = conf->providers;
+
+        while (last->next) {
+            last = last->next;
+        }
+        last->next = newp;
+    }
+
+    return NULL;
+}
+
+static const char *set_qop(cmd_parms *cmd, void *config, const char *op)
+{
+    digest_config_rec *conf = (digest_config_rec *) config;
+
+    if (!ap_cstr_casecmp(op, "none")) {
+        apr_array_clear(conf->qop_list);
+        *(const char **)apr_array_push(conf->qop_list) = "none";
+        return NULL;
+    }
+
+    if (!ap_cstr_casecmp(op, "auth-int")) {
+        return "AuthDigestQop auth-int is not implemented";
+    }
+    else if (ap_cstr_casecmp(op, "auth")) {
+        return apr_pstrcat(cmd->pool, "Unrecognized qop: ", op, NULL);
+    }
+
+    *(const char **)apr_array_push(conf->qop_list) = op;
+
+    return NULL;
+}
+
+static const char *set_nonce_lifetime(cmd_parms *cmd, void *config,
+                                      const char *t)
+{
+    char *endptr;
+    long  lifetime;
+
+    lifetime = strtol(t, &endptr, 10);
+    if (endptr < (t+strlen(t)) && !apr_isspace(*endptr)) {
+        return apr_pstrcat(cmd->pool,
+                           "Invalid time in AuthDigestNonceLifetime: ",
+                           t, NULL);
+    }
+
+    ((digest_config_rec *) config)->nonce_lifetime = apr_time_from_sec(lifetime);
+    return NULL;
+}
+
+static const char *set_nonce_format(cmd_parms *cmd, void *config,
+                                    const char *fmt)
+{
+    return "AuthDigestNonceFormat is not implemented";
+}
+
+static const char *set_nc_check(cmd_parms *cmd, void *config, int flag)
+{
+#if !APR_HAS_SHARED_MEMORY
+    if (flag) {
+        return "AuthDigestNcCheck: ERROR: nonce-count checking "
+                     "is not supported on platforms without shared-memory "
+                     "support";
+    }
+#endif
+
+    ((digest_config_rec *) config)->check_nc = flag;
+    return NULL;
+}
+
+static const char *set_algorithm(cmd_parms *cmd, void *config, const char *alg)
+{
+    if (!ap_cstr_casecmp(alg, "MD5-sess")) {
+        return "AuthDigestAlgorithm: ERROR: algorithm `MD5-sess' "
+                "is not implemented";
+    }
+    else if (ap_cstr_casecmp(alg, "MD5")) {
+        return apr_pstrcat(cmd->pool, "Invalid algorithm in AuthDigestAlgorithm: ", alg, NULL);
+    }
+
+    ((digest_config_rec *) config)->algorithm = alg;
+    return NULL;
+}
+
+static const char *set_uri_list(cmd_parms *cmd, void *config, const char *uri)
+{
+    digest_config_rec *c = (digest_config_rec *) config;
+    if (c->uri_list) {
+        c->uri_list[strlen(c->uri_list)-1] = '\0';
+        c->uri_list = apr_pstrcat(cmd->pool, c->uri_list, " ", uri, "\"", NULL);
+    }
+    else {
+        c->uri_list = apr_pstrcat(cmd->pool, ", domain=\"", uri, "\"", NULL);
+    }
+    return NULL;
+}
+
+static const char *set_shmem_size(cmd_parms *cmd, void *config,
+                                  const char *size_str)
+{
+    char *endptr;
+    long  size, min;
+
+    size = strtol(size_str, &endptr, 10);
+    while (apr_isspace(*endptr)) endptr++;
+    if (*endptr == '\0' || *endptr == 'b' || *endptr == 'B') {
+        ;
+    }
+    else if (*endptr == 'k' || *endptr == 'K') {
+        size *= 1024;
+    }
+    else if (*endptr == 'm' || *endptr == 'M') {
+        size *= 1048576;
+    }
+    else {
+        return apr_pstrcat(cmd->pool, "Invalid size in AuthDigestShmemSize: ",
+                          size_str, NULL);
+    }
+
+    min = sizeof(*client_list) + sizeof(client_entry*) + sizeof(client_entry);
+    if (size < min) {
+        return apr_psprintf(cmd->pool, "size in AuthDigestShmemSize too small: "
+                           "%ld < %ld", size, min);
+    }
+
+    shmem_size  = size;
+    num_buckets = (size - sizeof(*client_list)) /
+                  (sizeof(client_entry*) + HASH_DEPTH * sizeof(client_entry));
+    if (num_buckets == 0) {
+        num_buckets = 1;
+    }
+    ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, cmd->server, APLOGNO(01763)
+                 "Set shmem-size: %" APR_SIZE_T_FMT ", num-buckets: %ld",
+                 shmem_size, num_buckets);
+
+    return NULL;
+}
+
+static const command_rec digest_cmds[] =
+{
+    AP_INIT_TAKE1("AuthName", set_realm, NULL, OR_AUTHCFG,
+     "The authentication realm (e.g. \"Members Only\")"),
+    AP_INIT_ITERATE("AuthDigestProvider", add_authn_provider, NULL, OR_AUTHCFG,
+                     "specify the auth providers for a directory or location"),
+    AP_INIT_ITERATE("AuthDigestQop", set_qop, NULL, OR_AUTHCFG,
+     "A list of quality-of-protection options"),
+    AP_INIT_TAKE1("AuthDigestNonceLifetime", set_nonce_lifetime, NULL, OR_AUTHCFG,
+     "Maximum lifetime of the server nonce (seconds)"),
+    AP_INIT_TAKE1("AuthDigestNonceFormat", set_nonce_format, NULL, OR_AUTHCFG,
+     "The format to use when generating the server nonce"),
+    AP_INIT_FLAG("AuthDigestNcCheck", set_nc_check, NULL, OR_AUTHCFG,
+     "Whether or not to check the nonce-count sent by the client"),
+    AP_INIT_TAKE1("AuthDigestAlgorithm", set_algorithm, NULL, OR_AUTHCFG,
+     "The algorithm used for the hash calculation"),
+    AP_INIT_ITERATE("AuthDigestDomain", set_uri_list, NULL, OR_AUTHCFG,
+     "A list of URI's which belong to the same protection space as the current URI"),
+    AP_INIT_TAKE1("AuthDigestShmemSize", set_shmem_size, NULL, RSRC_CONF,
+     "The amount of shared memory to allocate for keeping track of clients"),
+    {NULL}
+};
+
+
+/*
+ * client list code
+ *
+ * Each client is assigned a number, which is transferred in the opaque
+ * field of the WWW-Authenticate and Authorization headers. The number
+ * is just a simple counter which is incremented for each new client.
+ * Clients can't forge this number because it is hashed up into the
+ * server nonce, and that is checked.
+ *
+ * The clients are kept in a simple hash table, which consists of an
+ * array of client_entry's, each with a linked list of entries hanging
+ * off it. The client's number modulo the size of the array gives the
+ * bucket number.
+ *
+ * The clients are garbage collected whenever a new client is allocated
+ * but there is not enough space left in the shared memory segment. A
+ * simple semi-LRU is used for this: whenever a client entry is accessed
+ * it is moved to the beginning of the linked list in its bucket (this
+ * also makes for faster lookups for current clients). The garbage
+ * collecter then just removes the oldest entry (i.e. the one at the
+ * end of the list) in each bucket.
+ *
+ * The main advantages of the above scheme are that it's easy to implement
+ * and it keeps the hash table evenly balanced (i.e. same number of entries
+ * in each bucket). The major disadvantage is that you may be throwing
+ * entries out which are in active use. This is not tragic, as these
+ * clients will just be sent a new client id (opaque field) and nonce
+ * with a stale=true (i.e. it will just look like the nonce expired,
+ * thereby forcing an extra round trip). If the shared memory segment
+ * has enough headroom over the current client set size then this should
+ * not occur too often.
+ *
+ * To help tune the size of the shared memory segment (and see if the
+ * above algorithm is really sufficient) a set of counters is kept
+ * indicating the number of clients held, the number of garbage collected
+ * clients, and the number of erroneously purged clients. These are printed
+ * out at each garbage collection run. Note that access to the counters is
+ * not synchronized because they are just indicaters, and whether they are
+ * off by a few doesn't matter; and for the same reason no attempt is made
+ * to guarantee the num_renewed is correct in the face of clients spoofing
+ * the opaque field.
+ */
+
+/*
+ * Get the client given its client number (the key). Returns the entry,
+ * or NULL if it's not found.
+ *
+ * Access to the list itself is synchronized via locks. However, access
+ * to the entry returned by get_client() is NOT synchronized. This means
+ * that there are potentially problems if a client uses multiple,
+ * simultaneous connections to access url's within the same protection
+ * space. However, these problems are not new: when using multiple
+ * connections you have no guarantee of the order the requests are
+ * processed anyway, so you have problems with the nonce-count and
+ * one-time nonces anyway.
+ */
+static client_entry *get_client(unsigned long key, const request_rec *r)
+{
+    int bucket;
+    client_entry *entry, *prev = NULL;
+
+
+    if (!key || !client_shm)  return NULL;
+
+    bucket = key % client_list->tbl_len;
+    entry  = client_list->table[bucket];
+
+    apr_global_mutex_lock(client_lock);
+
+    while (entry && key != entry->key) {
+        prev  = entry;
+        entry = entry->next;
+    }
+
+    if (entry && prev) {                /* move entry to front of list */
+        prev->next  = entry->next;
+        entry->next = client_list->table[bucket];
+        client_list->table[bucket] = entry;
+    }
+
+    apr_global_mutex_unlock(client_lock);
+
+    if (entry) {
+        ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(01764)
+                      "get_client(): client %lu found", key);
+    }
+    else {
+        ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(01765)
+                      "get_client(): client %lu not found", key);
+    }
+
+    return entry;
+}
+
+
+/* A simple garbage-collecter to remove unused clients. It removes the
+ * last entry in each bucket and updates the counters. Returns the
+ * number of removed entries.
+ */
+static long gc(server_rec *s)
+{
+    client_entry *entry, *prev;
+    unsigned long num_removed = 0, idx;
+
+    /* garbage collect all last entries */
+
+    for (idx = 0; idx < client_list->tbl_len; idx++) {
+        entry = client_list->table[idx];
+        prev  = NULL;
+
+        if (!entry) {
+            /* This bucket is empty. */
+            continue;
+        }
+
+        while (entry->next) {   /* find last entry */
+            prev  = entry;
+            entry = entry->next;
+        }
+        if (prev) {
+            prev->next = NULL;   /* cut list */
+        }
+        else {
+            client_list->table[idx] = NULL;
+        }
+        if (entry) {                    /* remove entry */
+            apr_status_t err;
+
+            err = rmm_free(client_rmm, entry);
+            num_removed++;
+
+            if (err) {
+                /* Nothing we can really do but log... */
+                ap_log_error(APLOG_MARK, APLOG_ERR, err, s, APLOGNO(10007)
+                             "Failed to free auth_digest client allocation");
+            }
+        }
+    }
+
+    /* update counters and log */
+
+    client_list->num_entries -= num_removed;
+    client_list->num_removed += num_removed;
+
+    return num_removed;
+}
+
+
+/*
+ * Add a new client to the list. Returns the entry if successful, NULL
+ * otherwise. This triggers the garbage collection if memory is low.
+ */
+static client_entry *add_client(unsigned long key, client_entry *info,
+                                server_rec *s)
+{
+    int bucket;
+    client_entry *entry;
+
+
+    if (!key || !client_shm) {
+        return NULL;
+    }
+
+    bucket = key % client_list->tbl_len;
+
+    apr_global_mutex_lock(client_lock);
+
+    /* try to allocate a new entry */
+
+    entry = rmm_malloc(client_rmm, sizeof(client_entry));
+    if (!entry) {
+        long num_removed = gc(s);
+        ap_log_error(APLOG_MARK, APLOG_INFO, 0, s, APLOGNO(01766)
+                     "gc'd %ld client entries. Total new clients: "
+                     "%ld; Total removed clients: %ld; Total renewed clients: "
+                     "%ld", num_removed,
+                     client_list->num_created - client_list->num_renewed,
+                     client_list->num_removed, client_list->num_renewed);
+        entry = rmm_malloc(client_rmm, sizeof(client_entry));
+        if (!entry) {
+            ap_log_error(APLOG_MARK, APLOG_ERR, 0, s, APLOGNO(01767)
+                         "unable to allocate new auth_digest client");
+            apr_global_mutex_unlock(client_lock);
+            return NULL;       /* give up */
+        }
+    }
+
+    /* now add the entry */
+
+    memcpy(entry, info, sizeof(client_entry));
+    entry->key  = key;
+    entry->next = client_list->table[bucket];
+    client_list->table[bucket] = entry;
+    client_list->num_created++;
+    client_list->num_entries++;
+
+    apr_global_mutex_unlock(client_lock);
+
+    ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, APLOGNO(01768)
+                 "allocated new client %lu", key);
+
+    return entry;
+}
+
+
+/*
+ * Authorization header parser code
+ */
+
+/* Parse the Authorization header, if it exists */
+static int get_digest_rec(request_rec *r, digest_header_rec *resp)
+{
+    const char *auth_line;
+    apr_size_t l;
+    int vk = 0, vv = 0;
+    char *key, *value;
+
+    auth_line = apr_table_get(r->headers_in,
+                             (PROXYREQ_PROXY == r->proxyreq)
+                                 ? "Proxy-Authorization"
+                                 : "Authorization");
+    if (!auth_line) {
+        resp->auth_hdr_sts = NO_HEADER;
+        return !OK;
+    }
+
+    resp->scheme = ap_getword_white(r->pool, &auth_line);
+    if (ap_cstr_casecmp(resp->scheme, "Digest")) {
+        resp->auth_hdr_sts = NOT_DIGEST;
+        return !OK;
+    }
+
+    l = strlen(auth_line);
+
+    key   = apr_palloc(r->pool, l+1);
+    value = apr_palloc(r->pool, l+1);
+
+    while (auth_line[0] != '\0') {
+
+        /* find key */
+
+        while (apr_isspace(auth_line[0])) {
+            auth_line++;
+        }
+        vk = 0;
+        while (auth_line[0] != '=' && auth_line[0] != ','
+               && auth_line[0] != '\0' && !apr_isspace(auth_line[0])) {
+            key[vk++] = *auth_line++;
+        }
+        key[vk] = '\0';
+        while (apr_isspace(auth_line[0])) {
+            auth_line++;
+        }
+
+        /* find value */
+
+        vv = 0;
+        if (auth_line[0] == '=') {
+            auth_line++;
+            while (apr_isspace(auth_line[0])) {
+                auth_line++;
+            }
+
+            if (auth_line[0] == '\"') {         /* quoted string */
+                auth_line++;
+                while (auth_line[0] != '\"' && auth_line[0] != '\0') {
+                    if (auth_line[0] == '\\' && auth_line[1] != '\0') {
+                        auth_line++;            /* escaped char */
+                    }
+                    value[vv++] = *auth_line++;
+                }
+                if (auth_line[0] != '\0') {
+                    auth_line++;
+                }
+            }
+            else {                               /* token */
+                while (auth_line[0] != ',' && auth_line[0] != '\0'
+                       && !apr_isspace(auth_line[0])) {
+                    value[vv++] = *auth_line++;
+                }
+            }
+        }
+        value[vv] = '\0';
+
+        while (auth_line[0] != ',' && auth_line[0] != '\0') {
+            auth_line++;
+        }
+        if (auth_line[0] != '\0') {
+            auth_line++;
+        }
+
+        if (!ap_cstr_casecmp(key, "username"))
+            resp->username = apr_pstrdup(r->pool, value);
+        else if (!ap_cstr_casecmp(key, "realm"))
+            resp->realm = apr_pstrdup(r->pool, value);
+        else if (!ap_cstr_casecmp(key, "nonce"))
+            resp->nonce = apr_pstrdup(r->pool, value);
+        else if (!ap_cstr_casecmp(key, "uri"))
+            resp->uri = apr_pstrdup(r->pool, value);
+        else if (!ap_cstr_casecmp(key, "response"))
+            resp->digest = apr_pstrdup(r->pool, value);
+        else if (!ap_cstr_casecmp(key, "algorithm"))
+            resp->algorithm = apr_pstrdup(r->pool, value);
+        else if (!ap_cstr_casecmp(key, "cnonce"))
+            resp->cnonce = apr_pstrdup(r->pool, value);
+        else if (!ap_cstr_casecmp(key, "opaque"))
+            resp->opaque = apr_pstrdup(r->pool, value);
+        else if (!ap_cstr_casecmp(key, "qop"))
+            resp->message_qop = apr_pstrdup(r->pool, value);
+        else if (!ap_cstr_casecmp(key, "nc"))
+            resp->nonce_count = apr_pstrdup(r->pool, value);
+    }
+
+    if (!resp->username || !resp->realm || !resp->nonce || !resp->uri
+        || !resp->digest
+        || (resp->message_qop && (!resp->cnonce || !resp->nonce_count))) {
+        resp->auth_hdr_sts = INVALID;
+        return !OK;
+    }
+
+    if (resp->opaque) {
+        resp->opaque_num = (unsigned long) strtol(resp->opaque, NULL, 16);
+    }
+
+    resp->auth_hdr_sts = VALID;
+    return OK;
+}
+
+
+/* Because the browser may preemptively send auth info, incrementing the
+ * nonce-count when it does, and because the client does not get notified
+ * if the URI didn't need authentication after all, we need to be sure to
+ * update the nonce-count each time we receive an Authorization header no
+ * matter what the final outcome of the request. Furthermore this is a
+ * convenient place to get the request-uri (before any subrequests etc
+ * are initiated) and to initialize the request_config.
+ *
+ * Note that this must be called after mod_proxy had its go so that
+ * r->proxyreq is set correctly.
+ */
+static int parse_hdr_and_update_nc(request_rec *r)
+{
+    digest_header_rec *resp;
+    int res;
+
+    if (!ap_is_initial_req(r)) {
+        return DECLINED;
+    }
+
+    resp = apr_pcalloc(r->pool, sizeof(digest_header_rec));
+    resp->raw_request_uri = r->unparsed_uri;
+    resp->psd_request_uri = &r->parsed_uri;
+    resp->needed_auth = 0;
+    resp->method = r->method;
+    ap_set_module_config(r->request_config, &auth_digest_module, resp);
+
+    res = get_digest_rec(r, resp);
+    resp->client = get_client(resp->opaque_num, r);
+    if (res == OK && resp->client) {
+        resp->client->nonce_count++;
+    }
+
+    return DECLINED;
+}
+
+
+/*
+ * Nonce generation code
+ */
+
+/* The hash part of the nonce is a SHA-1 hash of the time, realm, server host
+ * and port, opaque, and our secret.
+ */
+static void gen_nonce_hash(char *hash, const char *timestr, const char *opaque,
+                           const server_rec *server,
+                           const digest_config_rec *conf)
+{
+    unsigned char sha1[APR_SHA1_DIGESTSIZE];
+    apr_sha1_ctx_t ctx;
+
+    memcpy(&ctx, &conf->nonce_ctx, sizeof(ctx));
+    /*
+    apr_sha1_update_binary(&ctx, (const unsigned char *) server->server_hostname,
+                         strlen(server->server_hostname));
+    apr_sha1_update_binary(&ctx, (const unsigned char *) &server->port,
+                         sizeof(server->port));
+     */
+    apr_sha1_update_binary(&ctx, (const unsigned char *) timestr, strlen(timestr));
+    if (opaque) {
+        apr_sha1_update_binary(&ctx, (const unsigned char *) opaque,
+                             strlen(opaque));
+    }
+    apr_sha1_final(sha1, &ctx);
+
+    ap_bin2hex(sha1, APR_SHA1_DIGESTSIZE, hash);
+}
+
+
+/* The nonce has the format b64(time)+hash .
+ */
+static const char *gen_nonce(apr_pool_t *p, apr_time_t now, const char *opaque,
+                             const server_rec *server,
+                             const digest_config_rec *conf)
+{
+    char *nonce = apr_palloc(p, NONCE_LEN+1);
+    time_rec t;
+
+    if (conf->nonce_lifetime != 0) {
+        t.time = now;
+    }
+    else if (otn_counter) {
+        /* this counter is not synch'd, because it doesn't really matter
+         * if it counts exactly.
+         */
+        t.time = (*otn_counter)++;
+    }
+    else {
+        /* XXX: WHAT IS THIS CONSTANT? */
+        t.time = 42;
+    }
+    apr_base64_encode_binary(nonce, t.arr, sizeof(t.arr));
+    gen_nonce_hash(nonce+NONCE_TIME_LEN, nonce, opaque, server, conf);
+
+    return nonce;
+}
+
+
+/*
+ * Opaque and hash-table management
+ */
+
+/*
+ * Generate a new client entry, add it to the list, and return the
+ * entry. Returns NULL if failed.
+ */
+static client_entry *gen_client(const request_rec *r)
+{
+    unsigned long op;
+    client_entry new_entry = { 0, NULL, 0, "" }, *entry;
+
+    if (!opaque_cntr) {
+        return NULL;
+    }
+
+    apr_global_mutex_lock(opaque_lock);
+    op = (*opaque_cntr)++;
+    apr_global_mutex_unlock(opaque_lock);
+
+    if (!(entry = add_client(op, &new_entry, r->server))) {
+        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(01769)
+                      "failed to allocate client entry - ignoring client");
+        return NULL;
+    }
+
+    return entry;
+}
+
+
+/*
+ * Authorization challenge generation code (for WWW-Authenticate)
+ */
+
+static const char *ltox(apr_pool_t *p, unsigned long num)
+{
+    if (num != 0) {
+        return apr_psprintf(p, "%lx", num);
+    }
+    else {
+        return "";
+    }
+}
+
+static void note_digest_auth_failure(request_rec *r,
+                                     const digest_config_rec *conf,
+                                     digest_header_rec *resp, int stale)
+{
+    const char   *qop, *opaque, *opaque_param, *domain, *nonce;
+
+    /* Setup qop */
+    if (apr_is_empty_array(conf->qop_list)) {
+        qop = ", qop=\"auth\"";
+    }
+    else if (!ap_cstr_casecmp(*(const char **)(conf->qop_list->elts), "none")) {
+        qop = "";
+    }
+    else {
+        qop = apr_pstrcat(r->pool, ", qop=\"",
+                                   apr_array_pstrcat(r->pool, conf->qop_list, ','),
+                                   "\"",
+                                   NULL);
+    }
+
+    /* Setup opaque */
+
+    if (resp->opaque == NULL) {
+        /* new client */
+        if ((conf->check_nc || conf->nonce_lifetime == 0)
+            && (resp->client = gen_client(r)) != NULL) {
+            opaque = ltox(r->pool, resp->client->key);
+        }
+        else {
+            opaque = "";                /* opaque not needed */
+        }
+    }
+    else if (resp->client == NULL) {
+        /* client info was gc'd */
+        resp->client = gen_client(r);
+        if (resp->client != NULL) {
+            opaque = ltox(r->pool, resp->client->key);
+            stale = 1;
+            client_list->num_renewed++;
+        }
+        else {
+            opaque = "";                /* ??? */
+        }
+    }
+    else {
+        opaque = resp->opaque;
+        /* we're generating a new nonce, so reset the nonce-count */
+        resp->client->nonce_count = 0;
+    }
+
+    if (opaque[0]) {
+        opaque_param = apr_pstrcat(r->pool, ", opaque=\"", opaque, "\"", NULL);
+    }
+    else {
+        opaque_param = NULL;
+    }
+
+    /* Setup nonce */
+
+    nonce = gen_nonce(r->pool, r->request_time, opaque, r->server, conf);
+    if (resp->client && conf->nonce_lifetime == 0) {
+        memcpy(resp->client->last_nonce, nonce, NONCE_LEN+1);
+    }
+
+    /* setup domain attribute. We want to send this attribute wherever
+     * possible so that the client won't send the Authorization header
+     * unnecessarily (it's usually > 200 bytes!).
+     */
+
+
+    /* don't send domain
+     * - for proxy requests
+     * - if it's not specified
+     */
+    if (r->proxyreq || !conf->uri_list) {
+        domain = NULL;
+    }
+    else {
+        domain = conf->uri_list;
+    }
+
+    apr_table_mergen(r->err_headers_out,
+                     (PROXYREQ_PROXY == r->proxyreq)
+                         ? "Proxy-Authenticate" : "WWW-Authenticate",
+                     apr_psprintf(r->pool, "Digest realm=\"%s\", "
+                                  "nonce=\"%s\", algorithm=%s%s%s%s%s",
+                                  ap_auth_name(r), nonce, conf->algorithm,
+                                  opaque_param ? opaque_param : "",
+                                  domain ? domain : "",
+                                  stale ? ", stale=true" : "", qop));
+
+}
+
+static int hook_note_digest_auth_failure(request_rec *r, const char *auth_type)
+{
+    request_rec *mainreq;
+    digest_header_rec *resp;
+    digest_config_rec *conf;
+
+    if (ap_cstr_casecmp(auth_type, "Digest"))
+        return DECLINED;
+
+    /* get the client response and mark */
+
+    mainreq = r;
+    while (mainreq->main != NULL) {
+        mainreq = mainreq->main;
+    }
+    while (mainreq->prev != NULL) {
+        mainreq = mainreq->prev;
+    }
+    resp = (digest_header_rec *) ap_get_module_config(mainreq->request_config,
+                                                      &auth_digest_module);
+    resp->needed_auth = 1;
+
+
+    /* get our conf */
+
+    conf = (digest_config_rec *) ap_get_module_config(r->per_dir_config,
+                                                      &auth_digest_module);
+
+    note_digest_auth_failure(r, conf, resp, 0);
+
+    return OK;
+}
+
+
+/*
+ * Authorization header verification code
+ */
+
+static authn_status get_hash(request_rec *r, const char *user,
+                             digest_config_rec *conf, const char **rethash)
+{
+    authn_status auth_result;
+    char *password;
+    authn_provider_list *current_provider;
+
+    current_provider = conf->providers;
+    do {
+        const authn_provider *provider;
+
+        /* For now, if a provider isn't set, we'll be nice and use the file
+         * provider.
+         */
+        if (!current_provider) {
+            provider = ap_lookup_provider(AUTHN_PROVIDER_GROUP,
+                                          AUTHN_DEFAULT_PROVIDER,
+                                          AUTHN_PROVIDER_VERSION);
+
+            if (!provider || !provider->get_realm_hash) {
+                ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(01770)
+                              "No Authn provider configured");
+                auth_result = AUTH_GENERAL_ERROR;
+                break;
+            }
+            apr_table_setn(r->notes, AUTHN_PROVIDER_NAME_NOTE, AUTHN_DEFAULT_PROVIDER);
+        }
+        else {
+            provider = current_provider->provider;
+            apr_table_setn(r->notes, AUTHN_PROVIDER_NAME_NOTE, current_provider->provider_name);
+        }
+
+
+        /* We expect the password to be md5 hash of user:realm:password */
+        auth_result = provider->get_realm_hash(r, user, conf->realm,
+                                               &password);
+
+        apr_table_unset(r->notes, AUTHN_PROVIDER_NAME_NOTE);
+
+        /* Something occurred.  Stop checking. */
+        if (auth_result != AUTH_USER_NOT_FOUND) {
+            break;
+        }
+
+        /* If we're not really configured for providers, stop now. */
+        if (!conf->providers) {
+           break;
+        }
+
+        current_provider = current_provider->next;
+    } while (current_provider);
+
+    if (auth_result == AUTH_USER_FOUND) {
+        *rethash = password;
+    }
+
+    return auth_result;
+}
+
+static int check_nc(const request_rec *r, const digest_header_rec *resp,
+                    const digest_config_rec *conf)
+{
+    unsigned long nc;
+    const char *snc = resp->nonce_count;
+    char *endptr;
+
+    if (conf->check_nc && !client_shm) {
+        /* Shouldn't happen, but just in case... */
+        ap_log_rerror(APLOG_MARK, APLOG_WARNING, 0, r, APLOGNO(01771)
+                      "cannot check nonce count without shared memory");
+        return OK;
+    }
+
+    if (!conf->check_nc || !client_shm) {
+        return OK;
+    }
+
+    if (!apr_is_empty_array(conf->qop_list) &&
+        !ap_cstr_casecmp(*(const char **)(conf->qop_list->elts), "none")) {
+        /* qop is none, client must not send a nonce count */
+        if (snc != NULL) {
+            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(01772)
+                          "invalid nc %s received - no nonce count allowed when qop=none",
+                          snc);
+            return !OK;
+        }
+        /* qop is none, cannot check nonce count */
+        return OK;
+    }
+
+    nc = strtol(snc, &endptr, 16);
+    if (endptr < (snc+strlen(snc)) && !apr_isspace(*endptr)) {
+        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(01773)
+                      "invalid nc %s received - not a number", snc);
+        return !OK;
+    }
+
+    if (!resp->client) {
+        return !OK;
+    }
+
+    if (nc != resp->client->nonce_count) {
+        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(01774)
+                      "Warning, possible replay attack: nonce-count "
+                      "check failed: %lu != %lu", nc,
+                      resp->client->nonce_count);
+        return !OK;
+    }
+
+    return OK;
+}
+
+static int check_nonce(request_rec *r, digest_header_rec *resp,
+                       const digest_config_rec *conf)
+{
+    apr_time_t dt;
+    time_rec nonce_time;
+    char tmp, hash[NONCE_HASH_LEN+1];
+
+    /* Since the time part of the nonce is a base64 encoding of an
+     * apr_time_t (8 bytes), it should end with a '=', fail early otherwise.
+     */
+    if (strlen(resp->nonce) != NONCE_LEN
+            || resp->nonce[NONCE_TIME_LEN - 1] != '=') {
+        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(01775)
+                      "invalid nonce '%s' received - length is not %d "
+                      "or time encoding is incorrect",
+                      resp->nonce, NONCE_LEN);
+        note_digest_auth_failure(r, conf, resp, 1);
+        return HTTP_UNAUTHORIZED;
+    }
+
+    tmp = resp->nonce[NONCE_TIME_LEN];
+    resp->nonce[NONCE_TIME_LEN] = '\0';
+    apr_base64_decode_binary(nonce_time.arr, resp->nonce);
+    gen_nonce_hash(hash, resp->nonce, resp->opaque, r->server, conf);
+    resp->nonce[NONCE_TIME_LEN] = tmp;
+    resp->nonce_time = nonce_time.time;
+
+    if (strcmp(hash, resp->nonce+NONCE_TIME_LEN)) {
+        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(01776)
+                      "invalid nonce %s received - hash is not %s",
+                      resp->nonce, hash);
+        note_digest_auth_failure(r, conf, resp, 1);
+        return HTTP_UNAUTHORIZED;
+    }
+
+    dt = r->request_time - nonce_time.time;
+    if (conf->nonce_lifetime > 0 && dt < 0) {
+        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(01777)
+                      "invalid nonce %s received - user attempted "
+                      "time travel", resp->nonce);
+        note_digest_auth_failure(r, conf, resp, 1);
+        return HTTP_UNAUTHORIZED;
+    }
+
+    if (conf->nonce_lifetime > 0) {
+        if (dt > conf->nonce_lifetime) {
+            ap_log_rerror(APLOG_MARK, APLOG_INFO, 0,r, APLOGNO(01778)
+                          "user %s: nonce expired (%.2f seconds old "
+                          "- max lifetime %.2f) - sending new nonce",
+                          r->user, (double)apr_time_sec(dt),
+                          (double)apr_time_sec(conf->nonce_lifetime));
+            note_digest_auth_failure(r, conf, resp, 1);
+            return HTTP_UNAUTHORIZED;
+        }
+    }
+    else if (conf->nonce_lifetime == 0 && resp->client) {
+        if (memcmp(resp->client->last_nonce, resp->nonce, NONCE_LEN)) {
+            ap_log_rerror(APLOG_MARK, APLOG_INFO, 0, r, APLOGNO(01779)
+                          "user %s: one-time-nonce mismatch - sending "
+                          "new nonce", r->user);
+            note_digest_auth_failure(r, conf, resp, 1);
+            return HTTP_UNAUTHORIZED;
+        }
+    }
+    /* else (lifetime < 0) => never expires */
+
+    return OK;
+}
+
+/* The actual MD5 code... whee */
+
+/* RFC-2069 */
+static const char *old_digest(const request_rec *r,
+                              const digest_header_rec *resp)
+{
+    const char *ha2;
+
+    ha2 = ap_md5(r->pool, (unsigned char *)apr_pstrcat(r->pool, resp->method, ":",
+                                                       resp->uri, NULL));
+    return ap_md5(r->pool,
+                  (unsigned char *)apr_pstrcat(r->pool, resp->ha1, ":",
+                                               resp->nonce, ":", ha2, NULL));
+}
+
+/* RFC-2617 */
+static const char *new_digest(const request_rec *r,
+                              digest_header_rec *resp)
+{
+    const char *ha1, *ha2, *a2;
+
+    ha1 = resp->ha1;
+
+    a2 = apr_pstrcat(r->pool, resp->method, ":", resp->uri, NULL);
+    ha2 = ap_md5(r->pool, (const unsigned char *)a2);
+
+    return ap_md5(r->pool,
+                  (unsigned char *)apr_pstrcat(r->pool, ha1, ":", resp->nonce,
+                                               ":", resp->nonce_count, ":",
+                                               resp->cnonce, ":",
+                                               resp->message_qop, ":", ha2,
+                                               NULL));
+}
+
+static void copy_uri_components(apr_uri_t *dst,
+                                apr_uri_t *src, request_rec *r) {
+    if (src->scheme && src->scheme[0] != '\0') {
+        dst->scheme = src->scheme;
+    }
+    else {
+        dst->scheme = (char *) "http";
+    }
+
+    if (src->hostname && src->hostname[0] != '\0') {
+        dst->hostname = apr_pstrdup(r->pool, src->hostname);
+        ap_unescape_url(dst->hostname);
+    }
+    else {
+        dst->hostname = (char *) ap_get_server_name(r);
+    }
+
+    if (src->port_str && src->port_str[0] != '\0') {
+        dst->port = src->port;
+    }
+    else {
+        dst->port = ap_get_server_port(r);
+    }
+
+    if (src->path && src->path[0] != '\0') {
+        dst->path = apr_pstrdup(r->pool, src->path);
+        ap_unescape_url(dst->path);
+    }
+    else {
+        dst->path = src->path;
+    }
+
+    if (src->query && src->query[0] != '\0') {
+        dst->query = apr_pstrdup(r->pool, src->query);
+        ap_unescape_url(dst->query);
+    }
+    else {
+        dst->query = src->query;
+    }
+
+    dst->hostinfo = src->hostinfo;
+}
+
+/* These functions return 0 if client is OK, and proper error status
+ * if not... either HTTP_UNAUTHORIZED, if we made a check, and it failed, or
+ * HTTP_INTERNAL_SERVER_ERROR, if things are so totally confused that we
+ * couldn't figure out how to tell if the client is authorized or not.
+ *
+ * If they return DECLINED, and all other modules also decline, that's
+ * treated by the server core as a configuration error, logged and
+ * reported as such.
+ */
+
+/* Determine user ID, and check if the attributes are correct, if it
+ * really is that user, if the nonce is correct, etc.
+ */
+
+static int authenticate_digest_user(request_rec *r)
+{
+    digest_config_rec *conf;
+    digest_header_rec *resp;
+    request_rec       *mainreq;
+    const char        *t;
+    int                res;
+    authn_status       return_code;
+
+    /* do we require Digest auth for this URI? */
+
+    if (!(t = ap_auth_type(r)) || ap_cstr_casecmp(t, "Digest")) {
+        return DECLINED;
+    }
+
+    if (!ap_auth_name(r)) {
+        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(01780)
+                      "need AuthName: %s", r->uri);
+        return HTTP_INTERNAL_SERVER_ERROR;
+    }
+
+
+    /* get the client response and mark */
+
+    mainreq = r;
+    while (mainreq->main != NULL) {
+        mainreq = mainreq->main;
+    }
+    while (mainreq->prev != NULL) {
+        mainreq = mainreq->prev;
+    }
+    resp = (digest_header_rec *) ap_get_module_config(mainreq->request_config,
+                                                      &auth_digest_module);
+    resp->needed_auth = 1;
+
+
+    /* get our conf */
+
+    conf = (digest_config_rec *) ap_get_module_config(r->per_dir_config,
+                                                      &auth_digest_module);
+
+
+    /* check for existence and syntax of Auth header */
+
+    if (resp->auth_hdr_sts != VALID) {
+        if (resp->auth_hdr_sts == NOT_DIGEST) {
+            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(01781)
+                          "client used wrong authentication scheme `%s': %s",
+                          resp->scheme, r->uri);
+        }
+        else if (resp->auth_hdr_sts == INVALID) {
+            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(01782)
+                          "missing user, realm, nonce, uri, digest, "
+                          "cnonce, or nonce_count in authorization header: %s",
+                          r->uri);
+        }
+        /* else (resp->auth_hdr_sts == NO_HEADER) */
+        note_digest_auth_failure(r, conf, resp, 0);
+        return HTTP_UNAUTHORIZED;
+    }
+
+    r->user         = (char *) resp->username;
+    r->ap_auth_type = (char *) "Digest";
+
+    /* check the auth attributes */
+
+    if (strcmp(resp->uri, resp->raw_request_uri)) {
+        /* Hmm, the simple match didn't work (probably a proxy modified the
+         * request-uri), so lets do a more sophisticated match
+         */
+        apr_uri_t r_uri, d_uri;
+
+        copy_uri_components(&r_uri, resp->psd_request_uri, r);
+        if (apr_uri_parse(r->pool, resp->uri, &d_uri) != APR_SUCCESS) {
+            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(01783)
+                          "invalid uri <%s> in Authorization header",
+                          resp->uri);
+            return HTTP_BAD_REQUEST;
+        }
+
+        if (d_uri.hostname) {
+            ap_unescape_url(d_uri.hostname);
+        }
+        if (d_uri.path) {
+            ap_unescape_url(d_uri.path);
+        }
+
+        if (d_uri.query) {
+            ap_unescape_url(d_uri.query);
+        }
+        else if (r_uri.query) {
+            /* MSIE compatibility hack.  MSIE has some RFC issues - doesn't
+             * include the query string in the uri Authorization component
+             * or when computing the response component.  the second part
+             * works out ok, since we can hash the header and get the same
+             * result.  however, the uri from the request line won't match
+             * the uri Authorization component since the header lacks the
+             * query string, leaving us incompatible with a (broken) MSIE.
+             *
+             * the workaround is to fake a query string match if in the proper
+             * environment - BrowserMatch MSIE, for example.  the cool thing
+             * is that if MSIE ever fixes itself the simple match ought to
+             * work and this code won't be reached anyway, even if the
+             * environment is set.
+             */
+
+            if (apr_table_get(r->subprocess_env,
+                              "AuthDigestEnableQueryStringHack")) {
+
+                ap_log_rerror(APLOG_MARK, APLOG_INFO, 0, r, APLOGNO(01784)
+                              "applying AuthDigestEnableQueryStringHack "
+                              "to uri <%s>", resp->raw_request_uri);
+
+               d_uri.query = r_uri.query;
+            }
+        }
+
+        if (r->method_number == M_CONNECT) {
+            if (!r_uri.hostinfo || strcmp(resp->uri, r_uri.hostinfo)) {
+                ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(01785)
+                              "uri mismatch - <%s> does not match "
+                              "request-uri <%s>", resp->uri, r_uri.hostinfo);
+                return HTTP_BAD_REQUEST;
+            }
+        }
+        else if (
+            /* check hostname matches, if present */
+            (d_uri.hostname && d_uri.hostname[0] != '\0'
+              && strcasecmp(d_uri.hostname, r_uri.hostname))
+            /* check port matches, if present */
+            || (d_uri.port_str && d_uri.port != r_uri.port)
+            /* check that server-port is default port if no port present */
+            || (d_uri.hostname && d_uri.hostname[0] != '\0'
+                && !d_uri.port_str && r_uri.port != ap_default_port(r))
+            /* check that path matches */
+            || (d_uri.path != r_uri.path
+                /* either exact match */
+                && (!d_uri.path || !r_uri.path
+                    || strcmp(d_uri.path, r_uri.path))
+                /* or '*' matches empty path in scheme://host */
+                && !(d_uri.path && !r_uri.path && resp->psd_request_uri->hostname
+                    && d_uri.path[0] == '*' && d_uri.path[1] == '\0'))
+            /* check that query matches */
+            || (d_uri.query != r_uri.query
+                && (!d_uri.query || !r_uri.query
+                    || strcmp(d_uri.query, r_uri.query)))
+            ) {
+            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(01786)
+                          "uri mismatch - <%s> does not match "
+                          "request-uri <%s>", resp->uri, resp->raw_request_uri);
+            return HTTP_BAD_REQUEST;
+        }
+    }
+
+    if (resp->opaque && resp->opaque_num == 0) {
+        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(01787)
+                      "received invalid opaque - got `%s'",
+                      resp->opaque);
+        note_digest_auth_failure(r, conf, resp, 0);
+        return HTTP_UNAUTHORIZED;
+    }
+
+    if (!conf->realm) {
+        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(02533)
+                      "realm mismatch - got `%s' but no realm specified",
+                      resp->realm);
+        note_digest_auth_failure(r, conf, resp, 0);
+        return HTTP_UNAUTHORIZED;
+    }
+
+    if (!resp->realm || strcmp(resp->realm, conf->realm)) {
+        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(01788)
+                      "realm mismatch - got `%s' but expected `%s'",
+                      resp->realm, conf->realm);
+        note_digest_auth_failure(r, conf, resp, 0);
+        return HTTP_UNAUTHORIZED;
+    }
+
+    if (resp->algorithm != NULL
+        && ap_cstr_casecmp(resp->algorithm, "MD5")) {
+        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(01789)
+                      "unknown algorithm `%s' received: %s",
+                      resp->algorithm, r->uri);
+        note_digest_auth_failure(r, conf, resp, 0);
+        return HTTP_UNAUTHORIZED;
+    }
+
+    return_code = get_hash(r, r->user, conf, &resp->ha1);
+
+    if (return_code == AUTH_USER_NOT_FOUND) {
+        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(01790)
+                      "user `%s' in realm `%s' not found: %s",
+                      r->user, conf->realm, r->uri);
+        note_digest_auth_failure(r, conf, resp, 0);
+        return HTTP_UNAUTHORIZED;
+    }
+    else if (return_code == AUTH_USER_FOUND) {
+        /* we have a password, so continue */
+    }
+    else if (return_code == AUTH_DENIED) {
+        /* authentication denied in the provider before attempting a match */
+        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(01791)
+                      "user `%s' in realm `%s' denied by provider: %s",
+                      r->user, conf->realm, r->uri);
+        note_digest_auth_failure(r, conf, resp, 0);
+        return HTTP_UNAUTHORIZED;
+    }
+    else {
+        /* AUTH_GENERAL_ERROR (or worse)
+         * We'll assume that the module has already said what its error
+         * was in the logs.
+         */
+        return HTTP_INTERNAL_SERVER_ERROR;
+    }
+
+    if (resp->message_qop == NULL) {
+        /* old (rfc-2069) style digest */
+        if (strcmp(resp->digest, old_digest(r, resp))) {
+            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(01792)
+                          "user %s: password mismatch: %s", r->user,
+                          r->uri);
+            note_digest_auth_failure(r, conf, resp, 0);
+            return HTTP_UNAUTHORIZED;
+        }
+    }
+    else {
+        const char *exp_digest;
+        int match = 0, idx;
+        const char **tmp = (const char **)(conf->qop_list->elts);
+        for (idx = 0; idx < conf->qop_list->nelts; idx++) {
+            if (!ap_cstr_casecmp(*tmp, resp->message_qop)) {
+                match = 1;
+                break;
+            }
+            ++tmp;
+        }
+
+        if (!match
+            && !(apr_is_empty_array(conf->qop_list)
+                 && !ap_cstr_casecmp(resp->message_qop, "auth"))) {
+            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(01793)
+                          "invalid qop `%s' received: %s",
+                          resp->message_qop, r->uri);
+            note_digest_auth_failure(r, conf, resp, 0);
+            return HTTP_UNAUTHORIZED;
+        }
+
+        exp_digest = new_digest(r, resp);
+        if (!exp_digest) {
+            /* we failed to allocate a client struct */
+            return HTTP_INTERNAL_SERVER_ERROR;
+        }
+        if (strcmp(resp->digest, exp_digest)) {
+            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(01794)
+                          "user %s: password mismatch: %s", r->user,
+                          r->uri);
+            note_digest_auth_failure(r, conf, resp, 0);
+            return HTTP_UNAUTHORIZED;
+        }
+    }
+
+    if (check_nc(r, resp, conf) != OK) {
+        note_digest_auth_failure(r, conf, resp, 0);
+        return HTTP_UNAUTHORIZED;
+    }
+
+    /* Note: this check is done last so that a "stale=true" can be
+       generated if the nonce is old */
+    if ((res = check_nonce(r, resp, conf))) {
+        return res;
+    }
+
+    return OK;
+}
+
+/*
+ * Authorization-Info header code
+ */
+
+static int add_auth_info(request_rec *r)
+{
+    const digest_config_rec *conf =
+                (digest_config_rec *) ap_get_module_config(r->per_dir_config,
+                                                           &auth_digest_module);
+    digest_header_rec *resp =
+                (digest_header_rec *) ap_get_module_config(r->request_config,
+                                                           &auth_digest_module);
+    const char *ai = NULL, *nextnonce = "";
+
+    if (resp == NULL || !resp->needed_auth || conf == NULL) {
+        return OK;
+    }
+
+    /* 2069-style entity-digest is not supported (it's too hard, and
+     * there are no clients which support 2069 but not 2617). */
+
+    /* setup nextnonce
+     */
+    if (conf->nonce_lifetime > 0) {
+        /* send nextnonce if current nonce will expire in less than 30 secs */
+        if ((r->request_time - resp->nonce_time) > (conf->nonce_lifetime-NEXTNONCE_DELTA)) {
+            nextnonce = apr_pstrcat(r->pool, ", nextnonce=\"",
+                                   gen_nonce(r->pool, r->request_time,
+                                             resp->opaque, r->server, conf),
+                                   "\"", NULL);
+            if (resp->client)
+                resp->client->nonce_count = 0;
+        }
+    }
+    else if (conf->nonce_lifetime == 0 && resp->client) {
+        const char *nonce = gen_nonce(r->pool, 0, resp->opaque, r->server,
+                                      conf);
+        nextnonce = apr_pstrcat(r->pool, ", nextnonce=\"", nonce, "\"", NULL);
+        memcpy(resp->client->last_nonce, nonce, NONCE_LEN+1);
+    }
+    /* else nonce never expires, hence no nextnonce */
+
+
+    /* do rfc-2069 digest
+     */
+    if (!apr_is_empty_array(conf->qop_list) &&
+        !ap_cstr_casecmp(*(const char **)(conf->qop_list->elts), "none")
+        && resp->message_qop == NULL) {
+        /* use only RFC-2069 format */
+        ai = nextnonce;
+    }
+    else {
+        const char *resp_dig, *ha1, *a2, *ha2;
+
+        /* calculate rspauth attribute
+         */
+        ha1 = resp->ha1;
+
+        a2 = apr_pstrcat(r->pool, ":", resp->uri, NULL);
+        ha2 = ap_md5(r->pool, (const unsigned char *)a2);
+
+        resp_dig = ap_md5(r->pool,
+                          (unsigned char *)apr_pstrcat(r->pool, ha1, ":",
+                                                       resp->nonce, ":",
+                                                       resp->nonce_count, ":",
+                                                       resp->cnonce, ":",
+                                                       resp->message_qop ?
+                                                         resp->message_qop : "",
+                                                       ":", ha2, NULL));
+
+        /* assemble Authentication-Info header
+         */
+        ai = apr_pstrcat(r->pool,
+                         "rspauth=\"", resp_dig, "\"",
+                         nextnonce,
+                         resp->cnonce ? ", cnonce=\"" : "",
+                         resp->cnonce
+                           ? ap_escape_quotes(r->pool, resp->cnonce)
+                           : "",
+                         resp->cnonce ? "\"" : "",
+                         resp->nonce_count ? ", nc=" : "",
+                         resp->nonce_count ? resp->nonce_count : "",
+                         resp->message_qop ? ", qop=" : "",
+                         resp->message_qop ? resp->message_qop : "",
+                         NULL);
+    }
+
+    if (ai && ai[0]) {
+        apr_table_mergen(r->headers_out,
+                         (PROXYREQ_PROXY == r->proxyreq)
+                             ? "Proxy-Authentication-Info"
+                             : "Authentication-Info",
+                         ai);
+    }
+
+    return OK;
+}
+
+static void register_hooks(apr_pool_t *p)
+{
+    static const char * const cfgPost[]={ "http_core.c", NULL };
+    static const char * const parsePre[]={ "mod_proxy.c", NULL };
+
+    ap_hook_pre_config(pre_init, NULL, NULL, APR_HOOK_MIDDLE);
+    ap_hook_post_config(initialize_module, NULL, cfgPost, APR_HOOK_MIDDLE);
+    ap_hook_child_init(initialize_child, NULL, NULL, APR_HOOK_MIDDLE);
+    ap_hook_post_read_request(parse_hdr_and_update_nc, parsePre, NULL, APR_HOOK_MIDDLE);
+    ap_hook_check_authn(authenticate_digest_user, NULL, NULL, APR_HOOK_MIDDLE,
+                        AP_AUTH_INTERNAL_PER_CONF);
+
+    ap_hook_fixups(add_auth_info, NULL, NULL, APR_HOOK_MIDDLE);
+    ap_hook_note_auth_failure(hook_note_digest_auth_failure, NULL, NULL,
+                              APR_HOOK_MIDDLE);
+
+}
+
+AP_DECLARE_MODULE(auth_digest) =
+{
+    STANDARD20_MODULE_STUFF,
+    create_digest_dir_config,   /* dir config creater */
+    NULL,                       /* dir merger --- default is to override */
+    NULL,                       /* server config */
+    NULL,                       /* merge server config */
+    digest_cmds,                /* command table */
+    register_hooks              /* register hooks */
+};
+