prop224: Configure v3 service from options

This commit adds the support in the HS subsystem for loading a service from a
set of or_options_t and put them in a staging list.

To achieve this, service accessors have been created and a global hash map
containing service object indexed by master public key. However, this is not
used for now. It's ground work for registration process.

Signed-off-by: David Goulet <dgoulet@torproject.org>

8 files changed, 648 insertions, 107 deletions

diff --git a/src/or/circuitlist.h b/src/or/circuitlist.h
index d647062f46..2f76252563 100644
--- a/src/or/circuitlist.h
+++ b/src/or/circuitlist.h
@@ -48,6 +48,7 @@ origin_circuit_t *circuit_get_ready_rend_circ_by_rend_data(
 origin_circuit_t *circuit_get_next_by_pk_and_purpose(origin_circuit_t *start,
                                      const uint8_t *digest, uint8_t purpose);
 origin_circuit_t *circuit_get_next_service_intro_circ(origin_circuit_t *start);
+origin_circuit_t *circuit_get_next_service_hsdir_circ(origin_circuit_t *start);
 origin_circuit_t *circuit_find_to_cannibalize(uint8_t purpose,
                                               extend_info_t *info, int flags);
 void circuit_mark_all_unused_circs(void);
diff --git a/src/or/hs_common.h b/src/or/hs_common.h
index 8016535ca9..d1bc5ac7ef 100644
--- a/src/or/hs_common.h
+++ b/src/or/hs_common.h
@@ -22,7 +22,7 @@
 
 /** Try to maintain this many intro points per service by default. */
 #define NUM_INTRO_POINTS_DEFAULT 3
-/** Maximum number of intro points per service. */
+/** Maximum number of intro points per generic and version 2 service. */
 #define NUM_INTRO_POINTS_MAX 10
 /** Number of extra intro points we launch if our set of intro nodes is empty.
  * See proposal 155, section 4. */
diff --git a/src/or/hs_config.c b/src/or/hs_config.c
index 6326e90324..6bb422dbf1 100644
--- a/src/or/hs_config.c
+++ b/src/or/hs_config.c
@@ -31,20 +31,171 @@
 #include "hs_service.h"
 #include "rendservice.h"
 
-/* Configuration handler for a version 3 service. Return 0 on success else a
- * negative value. */
+/* Using the given list of services, stage them into our global state. Every
+ * service version are handled. This function can remove entries in the given
+ * service_list.
+ *
+ * Staging a service means that we take all services in service_list and we
+ * put them in the staging list (global) which acts as a temporary list that
+ * is used by the service loading key process. In other words, staging a
+ * service puts it in a list to be considered when loading the keys and then
+ * moved to the main global list. */
+static void
+stage_services(smartlist_t *service_list)
+{
+  tor_assert(service_list);
+
+  /* This is v2 specific. Trigger service pruning which will make sure the
+   * just configured services end up in the main global list. It should only
+   * be done in non validation mode because v2 subsystem handles service
+   * object differently. */
+  rend_service_prune_list();
+
+  /* Cleanup v2 service from the list, we don't need those object anymore
+   * because we validated them all against the others and we want to stage
+   * only >= v3 service. And remember, v2 has a different object type which is
+   * shadow copied from an hs_service_t type. */
+  SMARTLIST_FOREACH_BEGIN(service_list, hs_service_t *, s) {
+    if (s->version == HS_VERSION_TWO) {
+      SMARTLIST_DEL_CURRENT(service_list, s);
+      hs_service_free(s);
+    }
+  } SMARTLIST_FOREACH_END(s);
+
+  /* This is >= v3 specific. Using the newly configured service list, stage
+   * them into our global state. Every object ownership is lost after. */
+  hs_service_stage_services(service_list);
+}
+
+/* Validate the given service against all service in the given list. If the
+ * service is ephemeral, this function ignores it. Services with the same
+ * directory path aren't allowed and will return an error. If a duplicate is
+ * found, 1 is returned else 0 if none found. */
+static int
+service_is_duplicate_in_list(const smartlist_t *service_list,
+                             const hs_service_t *service)
+{
+  int ret = 0;
+
+  tor_assert(service_list);
+  tor_assert(service);
+
+  /* Ephemeral service don't have a directory configured so no need to check
+   * for a service in the list having the same path. */
+  if (service->config.is_ephemeral) {
+    goto end;
+  }
+
+  /* XXX: Validate if we have any service that has the given service dir path.
+   * This has two problems:
+   *
+   * a) It's O(n^2), but the same comment from the bottom of
+   *    rend_config_services() should apply.
+   *
+   * b) We only compare directory paths as strings, so we can't
+   *    detect two distinct paths that specify the same directory
+   *    (which can arise from symlinks, case-insensitivity, bind
+   *    mounts, etc.).
+   *
+   * It also can't detect that two separate Tor instances are trying
+   * to use the same HiddenServiceDir; for that, we would need a
+   * lock file.  But this is enough to detect a simple mistake that
+   * at least one person has actually made. */
+  SMARTLIST_FOREACH_BEGIN(service_list, const hs_service_t *, s) {
+    if (!strcmp(s->config.directory_path, service->config.directory_path)) {
+      log_warn(LD_REND, "Another hidden service is already configured "
+                        "for directory %s",
+               escaped(service->config.directory_path));
+      ret = 1;
+      goto end;
+    }
+  } SMARTLIST_FOREACH_END(s);
+
+ end:
+  return ret;
+}
+
+/* Validate service configuration. This is used when loading the configuration
+ * and once we've setup a service object, it's config object is passed to this
+ * function for further validation. This does not validate service key
+ * material. Return 0 if valid else -1 if invalid. */
+static int
+config_validate_service(const hs_service_config_t *config)
+{
+  tor_assert(config);
+
+  /* Amount of ports validation. */
+  if (!config->ports || smartlist_len(config->ports) == 0) {
+    log_warn(LD_CONFIG, "Hidden service (%s) with no ports configured.",
+             escaped(config->directory_path));
+    goto invalid;
+  }
+
+  /* Valid. */
+  return 0;
+ invalid:
+  return -1;
+}
+
+/* Configuration handler for a version 3 service. The line_ must be pointing
+ * to the directive directly after a HiddenServiceDir. That way, when hitting
+ * the next HiddenServiceDir line or reaching the end of the list of lines, we
+ * know that we have to stop looking for more options. The given service
+ * object must be already allocated and passed through
+ * config_generic_service() prior to calling this function.
+ *
+ * Return 0 on success else a negative value. */
 static int
-config_service_v3(const config_line_t *line,
-                  const or_options_t *options, int validate_only,
+config_service_v3(const config_line_t *line_,
+                  const or_options_t *options,
                   hs_service_t *service)
 {
-  (void) line;
-  (void) service;
-  (void) validate_only;
   (void) options;
-  /* XXX: Configure a v3 service with specific options. */
-  /* XXX: Add service to v3 list and pruning on reload. */
+  const config_line_t *line;
+  hs_service_config_t *config;
+
+  tor_assert(service);
+
+  config = &service->config;
+
+  for (line = line_; line; line = line->next) {
+    if (!strcasecmp(line->key, "HiddenServiceDir")) {
+      /* We just hit the next hidden service, stop right now. */
+      break;
+    }
+    /* Number of introduction points. */
+    if (!strcasecmp(line->key, "HiddenServiceNumIntroductionPoints")) {
+      int ok = 0;
+      config->num_intro_points =
+        (unsigned int) tor_parse_ulong(line->value, 10,
+                                       NUM_INTRO_POINTS_DEFAULT,
+                                       HS_CONFIG_V3_MAX_INTRO_POINTS,
+                                       &ok, NULL);
+      if (!ok) {
+        log_warn(LD_CONFIG, "HiddenServiceNumIntroductionPoints "
+                 "should be between %d and %d, not %s",
+                 NUM_INTRO_POINTS_DEFAULT, HS_CONFIG_V3_MAX_INTRO_POINTS,
+                 line->value);
+        goto err;
+      }
+      log_info(LD_CONFIG, "HiddenServiceNumIntroductionPoints=%d for %s",
+               config->num_intro_points, escaped(config->directory_path));
+      continue;
+    }
+  }
+
+  /* We do not load the key material for the service at this stage. This is
+   * done later once tor can confirm that it is in a running state. */
+
+  /* We are about to return a fully configured service so do one last pass of
+   * validation at it. */
+  if (config_validate_service(config) < 0) {
+    goto err;
+  }
+
   return 0;
+ err:
+  return -1;
 }
 
 /* Configure a service using the given options in line_ and options. This is
@@ -98,7 +249,7 @@ config_generic_service(const config_line_t *line_,
     /* Version of the service. */
     if (!strcasecmp(line->key, "HiddenServiceVersion")) {
       service->version = (uint32_t) tor_parse_ulong(line->value,
-                                                    10, HS_VERSION_TWO,
+                                                    10, HS_VERSION_MIN,
                                                     HS_VERSION_MAX,
                                                     &ok, NULL);
       if (!ok) {
@@ -164,13 +315,13 @@ config_generic_service(const config_line_t *line_,
     }
     /* Maximum streams per circuit. */
     if (!strcasecmp(line->key, "HiddenServiceMaxStreams")) {
-      config->max_streams_per_rdv_circuit = tor_parse_uint64(line->value,
-                                                             10, 0, 65535,
-                                                             &ok, NULL);
+      config->max_streams_per_rdv_circuit =
+        tor_parse_uint64(line->value, 10, 0,
+                         HS_CONFIG_MAX_STREAMS_PER_RDV_CIRCUIT, &ok, NULL);
       if (!ok) {
         log_warn(LD_CONFIG,
                  "HiddenServiceMaxStreams should be between 0 and %d, not %s",
-                 65535, line->value);
+                 HS_CONFIG_MAX_STREAMS_PER_RDV_CIRCUIT, line->value);
         goto err;
       }
       log_info(LD_CONFIG,
@@ -197,12 +348,6 @@ config_generic_service(const config_line_t *line_,
     }
   }
 
-  /* Check permission on service directory. */
-  if (hs_check_service_private_dir(options->User, config->directory_path,
-                                   config->dir_group_readable, 0) < 0) {
-    goto err;
-  }
-
   /* Check if we are configured in non anonymous mode and single hop mode
    * meaning every service become single onion. */
   if (rend_service_allow_non_anonymous_connection(options) &&
@@ -220,7 +365,6 @@ config_generic_service(const config_line_t *line_,
 static int
   (*config_service_handlers[])(const config_line_t *line,
                                const or_options_t *options,
-                               int validate_only,
                                hs_service_t *service) =
 {
   NULL, /* v0 */
@@ -229,64 +373,124 @@ static int
   config_service_v3, /* v3 */
 };
 
+/* Configure a service using the given line and options. This function will
+ * call the corresponding version handler and validate the service against the
+ * other one. On success, add the service to the given list and return 0. On
+ * error, nothing is added to the list and a negative value is returned. */
+static int
+config_service(const config_line_t *line, const or_options_t *options,
+               smartlist_t *service_list)
+{
+  hs_service_t *service = NULL;
+
+  tor_assert(line);
+  tor_assert(options);
+  tor_assert(service_list);
+
+  /* We have a new hidden service. */
+  service = hs_service_new(options);
+  /* We'll configure that service as a generic one and then pass it to the
+   * specific handler according to the configured version number. */
+  if (config_generic_service(line, options, service) < 0) {
+    goto err;
+  }
+  tor_assert(service->version <= HS_VERSION_MAX);
+  /* Check permission on service directory that was just parsed. And this must
+   * be done regardless of the service version. Do not ask for the directory
+   * to be created, this is done when the keys are loaded because we could be
+   * in validation mode right now. */
+  if (hs_check_service_private_dir(options->User,
+                                   service->config.directory_path,
+                                   service->config.dir_group_readable,
+                                   0) < 0) {
+    goto err;
+  }
+  /* The handler is in charge of specific options for a version. We start
+   * after this service directory line so once we hit another directory
+   * line, the handler knows that it has to stop. */
+  if (config_service_handlers[service->version](line->next, options,
+                                                service) < 0) {
+    goto err;
+  }
+  /* We'll check if this service can be kept depending on the others
+   * configured previously. */
+  if (service_is_duplicate_in_list(service_list, service)) {
+    goto err;
+  }
+  /* Passes, add it to the given list. */
+  smartlist_add(service_list, service);
+  return 0;
+
+ err:
+  hs_service_free(service);
+  return -1;
+}
+
 /* From a set of <b>options</b>, setup every hidden service found. Return 0 on
  * success or -1 on failure. If <b>validate_only</b> is set, parse, warn and
  * return as normal, but don't actually change the configured services. */
 int
 hs_config_service_all(const or_options_t *options, int validate_only)
 {
-  int dir_option_seen = 0;
-  hs_service_t *service = NULL;
+  int dir_option_seen = 0, ret = -1;
   const config_line_t *line;
+  smartlist_t *new_service_list = NULL;
 
   tor_assert(options);
 
+  /* Newly configured service are put in that list which is then used for
+   * validation and staging for >= v3. */
+  new_service_list = smartlist_new();
+
   for (line = options->RendConfigLines; line; line = line->next) {
-    if (!strcasecmp(line->key, "HiddenServiceDir")) {
-      /* We have a new hidden service. */
-      service = hs_service_new(options);
-      /* We'll configure that service as a generic one and then pass it to the
-       * specific handler according to the configured version number. */
-      if (config_generic_service(line, options, service) < 0) {
+    /* Ignore all directives that aren't the start of a service. */
+    if (strcasecmp(line->key, "HiddenServiceDir")) {
+      if (!dir_option_seen) {
+        log_warn(LD_CONFIG, "%s with no preceding HiddenServiceDir directive",
+                 line->key);
         goto err;
       }
-      tor_assert(service->version <= HS_VERSION_MAX);
-      /* The handler is in charge of specific options for a version. We start
-       * after this service directory line so once we hit another directory
-       * line, the handler knows that it has to stop. */
-      if (config_service_handlers[service->version](line->next, options,
-                                                    validate_only,
-                                                    service) < 0) {
-        goto err;
-      }
-      /* Whatever happens, on success we loose the ownership of the service
-       * object so we nullify the pointer to be safe. */
-      service = NULL;
-      /* Flag that we've seen a directory directive and we'll use that to make
-       * sure that the torrc options ordering are actually valid. */
-      dir_option_seen = 1;
       continue;
     }
-    /* The first line must be a directory option else tor is misconfigured. */
-    if (!dir_option_seen) {
-      log_warn(LD_CONFIG, "%s with no preceding HiddenServiceDir directive",
-               line->key);
+    /* Flag that we've seen a directory directive and we'll use it to make
+     * sure that the torrc options ordering is actually valid. */
+    dir_option_seen = 1;
+
+    /* Try to configure this service now. On success, it will be added to the
+     * list and validated against the service in that same list. */
+    if (config_service(line, options, new_service_list) < 0) {
       goto err;
     }
   }
 
+  /* In non validation mode, we'll stage those services we just successfully
+   * configured. Service ownership is transfered from the list to the global
+   * state. If any service is invalid, it will be removed from the list and
+   * freed. All versions are handled in that function. */
   if (!validate_only) {
-    /* Trigger service pruning which will make sure the just configured
-     * services end up in the main global list. This is v2 specific. */
-    rend_service_prune_list();
-    /* XXX: Need the v3 one. */
+    stage_services(new_service_list);
+  } else {
+    /* We've just validated that we were able to build a clean working list of
+     * services. We don't need those objects anymore. */
+    SMARTLIST_FOREACH(new_service_list, hs_service_t *, s,
+                      hs_service_free(s));
+    /* For the v2 subsystem, the configuration handler adds the service object
+     * to the staging list and it is transferred in the main list through the
+     * prunning process. In validation mode, we thus have to purge the staging
+     * list so it's not kept in memory as valid service. */
+    rend_service_free_staging_list();
   }
 
-  /* Success. */
-  return 0;
+  /* Success. Note that the service list has no ownership of its content. */
+  ret = 0;
+  goto end;
+
  err:
-  hs_service_free(service);
-  /* Tor main should call the free all function. */
-  return -1;
+  SMARTLIST_FOREACH(new_service_list, hs_service_t *, s, hs_service_free(s));
+
+ end:
+  smartlist_free(new_service_list);
+  /* Tor main should call the free all function on error. */
+  return ret;
 }
 
diff --git a/src/or/hs_config.h b/src/or/hs_config.h
index f4207917e5..2f8cbdc130 100644
--- a/src/or/hs_config.h
+++ b/src/or/hs_config.h
@@ -11,6 +11,8 @@
 
 #include "or.h"
 
+/* Max value for HiddenServiceMaxStreams */
+#define HS_CONFIG_MAX_STREAMS_PER_RDV_CIRCUIT 65535
 /* Maximum number of intro points per version 3 services. */
 #define HS_CONFIG_V3_MAX_INTRO_POINTS 20
 
diff --git a/src/or/hs_service.c b/src/or/hs_service.c
index 16ffc4885c..b267e1d028 100644
--- a/src/or/hs_service.c
+++ b/src/or/hs_service.c
@@ -7,18 +7,127 @@
  **/
 
 #include "or.h"
+#include "circuitlist.h"
+#include "config.h"
 #include "relay.h"
 #include "rendservice.h"
-#include "circuitlist.h"
-#include "circpathbias.h"
+#include "router.h"
 
+#include "hs_common.h"
+#include "hs_config.h"
 #include "hs_intropoint.h"
 #include "hs_service.h"
-#include "hs_common.h"
 
 #include "hs/cell_establish_intro.h"
 #include "hs/cell_common.h"
 
+/* Staging list of service object. When configuring service, we add them to
+ * this list considered a staging area and they will get added to our global
+ * map once the keys have been loaded. These two steps are seperated because
+ * loading keys requires that we are an actual running tor process. */
+static smartlist_t *hs_service_staging_list;
+
+/* Helper: Function to compare two objects in the service map. Return 1 if the
+ * two service have the same master public identity key. */
+static inline int
+hs_service_ht_eq(const hs_service_t *first, const hs_service_t *second)
+{
+  tor_assert(first);
+  tor_assert(second);
+  /* Simple key compare. */
+  return ed25519_pubkey_eq(&first->keys.identity_pk,
+                           &second->keys.identity_pk);
+}
+
+/* Helper: Function for the service hash table code below. The key used is the
+ * master public identity key which is ultimately the onion address. */
+static inline unsigned int
+hs_service_ht_hash(const hs_service_t *service)
+{
+  tor_assert(service);
+  return (unsigned int) siphash24g(service->keys.identity_pk.pubkey,
+                                   sizeof(service->keys.identity_pk.pubkey));
+}
+
+/* For the service global hash map, we define a specific type for it which
+ * will make it safe to use and specific to some controlled parameters such as
+ * the hashing function and how to compare services. */
+typedef HT_HEAD(hs_service_ht, hs_service_t) hs_service_ht;
+
+/* This is _the_ global hash map of hidden services which indexed the service
+ * contained in it by master public identity key which is roughly the onion
+ * address of the service. */
+static struct hs_service_ht *hs_service_map;
+
+/* Register the service hash table. */
+HT_PROTOTYPE(hs_service_ht,      /* Name of hashtable. */
+             hs_service_t,       /* Object contained in the map. */
+             hs_service_node,    /* The name of the HT_ENTRY member. */
+             hs_service_ht_hash, /* Hashing function. */
+             hs_service_ht_eq)   /* Compare function for objects. */
+
+HT_GENERATE2(hs_service_ht, hs_service_t, hs_service_node,
+             hs_service_ht_hash, hs_service_ht_eq,
+             0.6, tor_reallocarray, tor_free_)
+
+/* Query the given service map with a public key and return a service object
+ * if found else NULL. It is also possible to set a directory path in the
+ * search query. If pk is NULL, then it will be set to zero indicating the
+ * hash table to compare the directory path instead. */
+static hs_service_t *
+find_service(hs_service_ht *map, const ed25519_public_key_t *pk)
+{
+  hs_service_t dummy_service = {0};
+  tor_assert(map);
+  tor_assert(pk);
+  ed25519_pubkey_copy(&dummy_service.keys.identity_pk, pk);
+  return HT_FIND(hs_service_ht, map, &dummy_service);
+}
+
+/* Register the given service in the given map. If the service already exists
+ * in the map, -1 is returned. On success, 0 is returned and the service
+ * ownership has been transfered to the global map. */
+static int
+register_service(hs_service_ht *map, hs_service_t *service)
+{
+  tor_assert(map);
+  tor_assert(service);
+  tor_assert(!ed25519_public_key_is_zero(&service->keys.identity_pk));
+
+  if (find_service(map, &service->keys.identity_pk)) {
+    /* Existing service with the same key. Do not register it. */
+    return -1;
+  }
+  /* Taking ownership of the object at this point. */
+  HT_INSERT(hs_service_ht, map, service);
+  return 0;
+}
+
+/* Remove a given service from the given map. If service is NULL or the
+ * service key is unset, return gracefully. */
+static void
+remove_service(hs_service_ht *map, hs_service_t *service)
+{
+  hs_service_t *elm;
+
+  tor_assert(map);
+
+  /* Ignore if no service or key is zero. */
+  if (BUG(service == NULL) ||
+      BUG(ed25519_public_key_is_zero(&service->keys.identity_pk))) {
+    return;
+  }
+
+  elm = HT_REMOVE(hs_service_ht, map, service);
+  if (elm) {
+    tor_assert(elm == service);
+  } else {
+    log_warn(LD_BUG, "Could not find service in the global map "
+                     "while removing service %s",
+             escaped(service->config.directory_path));
+  }
+}
+
 /* Set the default values for a service configuration object <b>c</b>. */
 static void
 set_service_default_config(hs_service_config_t *c,
@@ -37,6 +146,239 @@ set_service_default_config(hs_service_config_t *c,
   c->is_ephemeral = 0;
 }
 
+/* Helper: Function that needs to return 1 for the HT for each loop which
+ * frees every service in an hash map. */
+static int
+ht_free_service_(struct hs_service_t *service, void *data)
+{
+  (void) data;
+  hs_service_free(service);
+  /* This function MUST return 1 so the given object is then removed from the
+   * service map leading to this free of the object being safe. */
+  return 1;
+}
+
+/* Free every service that can be found in the global map. Once done, clear
+ * and free the global map. */
+static void
+service_free_all(void)
+{
+  if (hs_service_map == NULL) {
+    return;
+  }
+  /* The free helper function returns 1 so this is safe. */
+  hs_service_ht_HT_FOREACH_FN(hs_service_map, ht_free_service_, NULL);
+  HT_CLEAR(hs_service_ht, hs_service_map);
+  tor_free(hs_service_map);
+  hs_service_map = NULL;
+  /* Cleanup staging list. */
+  SMARTLIST_FOREACH(hs_service_staging_list, hs_service_t *, s,
+                    hs_service_free(s));
+  smartlist_free(hs_service_staging_list);
+  hs_service_staging_list = NULL;
+}
+
+/* Close all rendezvous circuits for the given service. */
+static void
+close_service_rp_circuits(hs_service_t *service)
+{
+  tor_assert(service);
+  /* XXX: To implement. */
+  return;
+}
+
+/* Close the circuit(s) for the given map of introduction points. */
+static void
+close_intro_circuits(hs_service_intropoints_t *intro_points)
+{
+  tor_assert(intro_points);
+
+  DIGEST256MAP_FOREACH(intro_points->map, key,
+                       const hs_service_intro_point_t *, ip) {
+    origin_circuit_t *ocirc =
+      hs_circuitmap_get_intro_circ_v3_service_side(
+                                      &ip->auth_key_kp.pubkey);
+    if (ocirc) {
+      hs_circuitmap_remove_circuit(TO_CIRCUIT(ocirc));
+      /* Reason is FINISHED because service has been removed and thus the
+       * circuit is considered old/uneeded. */
+      circuit_mark_for_close(TO_CIRCUIT(ocirc), END_CIRC_REASON_FINISHED);
+    }
+  } DIGEST256MAP_FOREACH_END;
+}
+
+/* Close all introduction circuits for the given service. */
+static void
+close_service_intro_circuits(hs_service_t *service)
+{
+  tor_assert(service);
+
+  if (service->desc_current) {
+    close_intro_circuits(&service->desc_current->intro_points);
+  }
+  if (service->desc_next) {
+    close_intro_circuits(&service->desc_next->intro_points);
+  }
+}
+
+/* Close any circuits related to the given service. */
+static void
+close_service_circuits(hs_service_t *service)
+{
+  tor_assert(service);
+
+  /* Only support for version >= 3. */
+  if (BUG(service->version < HS_VERSION_THREE)) {
+    return;
+  }
+  /* Close intro points. */
+  close_service_intro_circuits(service);
+  /* Close rendezvous points. */
+  close_service_rp_circuits(service);
+}
+
+/* Move introduction points from the src descriptor to the dst descriptor. The
+ * destination service intropoints are wiped out if any before moving. */
+static void
+move_descriptor_intro_points(hs_service_descriptor_t *src,
+                             hs_service_descriptor_t *dst)
+{
+  tor_assert(src);
+  tor_assert(dst);
+
+  /* XXX: Free dst introduction points. */
+  dst->intro_points.map = src->intro_points.map;
+  /* Nullify the source. */
+  src->intro_points.map = NULL;
+}
+
+/* Move introduction points from the src service to the dst service. The
+ * destination service intropoints are wiped out if any before moving. */
+static void
+move_intro_points(hs_service_t *src, hs_service_t *dst)
+{
+  tor_assert(src);
+  tor_assert(dst);
+
+  /* Cleanup destination. */
+  if (src->desc_current && dst->desc_current) {
+    move_descriptor_intro_points(src->desc_current, dst->desc_current);
+  }
+  if (src->desc_next && dst->desc_next) {
+    move_descriptor_intro_points(src->desc_next, dst->desc_next);
+  }
+}
+
+/* Move every ephemeral services from the src service map to the dst service
+ * map. It is possible that a service can't be register to the dst map which
+ * won't stop the process of moving them all but will trigger a log warn. */
+static void
+move_ephemeral_services(hs_service_ht *src, hs_service_ht *dst)
+{
+  hs_service_t **iter, **next;
+
+  tor_assert(src);
+  tor_assert(dst);
+
+  /* Iterate over the map to find ephemeral service and move them to the other
+   * map. We loop using this method to have a safe removal process. */
+  for (iter = HT_START(hs_service_ht, src); iter != NULL; iter = next) {
+    hs_service_t *s = *iter;
+    if (!s->config.is_ephemeral) {
+      /* Yeah, we are in a very manual loop :). */
+      next = HT_NEXT(hs_service_ht, src, iter);
+      continue;
+    }
+    /* Remove service from map and then register to it to the other map.
+     * Reminder that "*iter" and "s" are the same thing. */
+    next = HT_NEXT_RMV(hs_service_ht, src, iter);
+    if (register_service(dst, s) < 0) {
+      log_warn(LD_BUG, "Ephemeral service key is already being used. "
+                       "Skipping.");
+    }
+  }
+}
+
+/* Register services that are in the list. Once this function returns, the
+ * global service map will be set with the right content and all non surviving
+ * services will be cleaned up. */
+void
+hs_service_register_services(smartlist_t *new_service_list)
+{
+  struct hs_service_ht *new_service_map;
+  hs_service_t *s, **iter;
+
+  tor_assert(new_service_list);
+
+  /* We'll save us some allocation and computing time. */
+  if (smartlist_len(new_service_list) == 0) {
+    return;
+  }
+
+  /* Allocate a new map that will replace the current one. */
+  new_service_map = tor_malloc_zero(sizeof(*new_service_map));
+  HT_INIT(hs_service_ht, new_service_map);
+
+  /* First step is to transfer all ephemeral services from the current global
+   * map to the new one we are constructing. We do not prune ephemeral
+   * services as the only way to kill them is by deleting it from the control
+   * port or stopping the tor daemon. */
+  move_ephemeral_services(hs_service_map, new_service_map);
+
+  SMARTLIST_FOREACH_BEGIN(new_service_list, hs_service_t *, snew) {
+    /* Check if that service is already in our global map and if so, we'll
+     * transfer the intro points to it. */
+    s = find_service(hs_service_map, &snew->keys.identity_pk);
+    if (s) {
+      /* Pass ownership of intro points from s (the current service) to snew
+       * (the newly configured one). */
+      move_intro_points(s, snew);
+      /* Remove the service from the global map because after this, we need to
+       * go over the remaining service in that map that aren't surviving the
+       * reload to close their circuits. */
+      remove_service(hs_service_map, s);
+    }
+    /* Great, this service is now ready to be added to our new map. */
+    if (BUG(register_service(new_service_map, snew) < 0)) {
+      /* This should never happen because prior to registration, we validate
+       * every service against the entire set. Not being able to register a
+       * service means we failed to validate correctly. In that case, don't
+       * break tor and ignore the service but tell user. */
+      log_warn(LD_BUG, "Unable to register service with directory %s",
+               snew->config.directory_path);
+      SMARTLIST_DEL_CURRENT(new_service_list, snew);
+      hs_service_free(snew);
+    }
+  } SMARTLIST_FOREACH_END(snew);
+
+  /* Close any circuits associated with the non surviving services. Every
+   * service in the current global map are roaming. */
+  HT_FOREACH(iter, hs_service_ht, hs_service_map) {
+    close_service_circuits(*iter);
+  }
+
+  /* Time to make the switch. We'll wipe the current list and switch. */
+  service_free_all();
+  hs_service_map = new_service_map;
+}
+
+/* Put all service object in the given service list. After this, the caller
+ * looses ownership of every elements in the list and responsible to free the
+ * list pointer. */
+void
+hs_service_stage_services(const smartlist_t *service_list)
+{
+  tor_assert(service_list);
+  /* This list is freed at registration time but this function can be called
+   * multiple time. */
+  if (hs_service_staging_list == NULL) {
+    hs_service_staging_list = smartlist_new();
+  }
+  /* Add all service object to our staging list. Caller is responsible for
+   * freeing the service_list. */
+  smartlist_add_all(hs_service_staging_list, service_list);
+}
+
 /* Allocate and initilize a service object. The service configuration will
  * contain the default values. Return the newly allocated object pointer. This
  * function can't fail. */
@@ -101,14 +443,22 @@ hs_service_free(hs_service_t *service)
 void
 hs_service_init(void)
 {
-  return;
+  /* Should never be called twice. */
+  tor_assert(!hs_service_map);
+  tor_assert(!hs_service_staging_list);
+
+  hs_service_map = tor_malloc_zero(sizeof(struct hs_service_ht));
+  HT_INIT(hs_service_ht, hs_service_map);
+
+  hs_service_staging_list = smartlist_new();
 }
 
-/* Release all global the storage of hidden service subsystem. */
+/* Release all global storage of the hidden service subsystem. */
 void
 hs_service_free_all(void)
 {
   rend_service_free_all();
+  service_free_all();
 }
 
 /* XXX We don't currently use these functions, apart from generating unittest
diff --git a/src/or/hs_service.h b/src/or/hs_service.h
index ec47cb72ae..8d92e75072 100644
--- a/src/or/hs_service.h
+++ b/src/or/hs_service.h
@@ -11,9 +11,10 @@
 
 #include "crypto_curve25519.h"
 #include "crypto_ed25519.h"
+#include "replaycache.h"
+
 #include "hs_descriptor.h"
 #include "hs_intropoint.h"
-#include "replaycache.h"
 
 /* Trunnel */
 #include "hs/cell_establish_intro.h"
@@ -171,6 +172,10 @@ typedef struct hs_service_t {
   /* Protocol version of the service. Specified by HiddenServiceVersion. */
   uint32_t version;
 
+  /* Hashtable node: use to look up the service by its master public identity
+   * key in the service global map. */
+  HT_ENTRY(hs_service_t) hs_service_node;
+
   /* Service state which contains various flags and counters. */
   hs_service_state_t state;
 
@@ -192,12 +197,16 @@ typedef struct hs_service_t {
 
 /* API */
 
-int hs_service_config_all(const or_options_t *options, int validate_only);
+/* Global initializer and cleanup function. */
 void hs_service_init(void);
 void hs_service_free_all(void);
 
-void hs_service_free(hs_service_t *service);
+/* Service new/free functions. */
 hs_service_t *hs_service_new(const or_options_t *options);
+void hs_service_free(hs_service_t *service);
+
+void hs_service_register_services(smartlist_t *new_service_list);
+void hs_service_stage_services(const smartlist_t *service_list);
 
 /* These functions are only used by unit tests and we need to expose them else
  * hs_service.o ends up with no symbols in libor.a which makes clang throw a
diff --git a/src/or/rendservice.c b/src/or/rendservice.c
index 695668bf60..e86119f2d0 100644
--- a/src/or/rendservice.c
+++ b/src/or/rendservice.c
@@ -231,8 +231,20 @@ rend_service_free(rend_service_t *service)
   tor_free(service);
 }
 
-/** Release all the storage held in rend_service_list.
- */
+/* Release all the storage held in rend_service_staging_list. */
+void
+rend_service_free_staging_list(void)
+{
+  if (rend_service_staging_list) {
+    SMARTLIST_FOREACH(rend_service_staging_list, rend_service_t*, ptr,
+                      rend_service_free(ptr));
+    smartlist_free(rend_service_staging_list);
+    rend_service_staging_list = NULL;
+  }
+}
+
+/** Release all the storage held in both rend_service_list and
+ * rend_service_staging_list. */
 void
 rend_service_free_all(void)
 {
@@ -242,12 +254,7 @@ rend_service_free_all(void)
     smartlist_free(rend_service_list);
     rend_service_list = NULL;
   }
-  if (rend_service_staging_list) {
-    SMARTLIST_FOREACH(rend_service_staging_list, rend_service_t*, ptr,
-                      rend_service_free(ptr));
-    smartlist_free(rend_service_staging_list);
-    rend_service_staging_list = NULL;
-  }
+  rend_service_free_staging_list();
 }
 
 /* Validate a <b>service</b>. Use the <b>service_list</b> to make sure there
@@ -257,8 +264,6 @@ static int
 rend_validate_service(const smartlist_t *service_list,
                       const rend_service_t *service)
 {
-  int dupe = 0;
-
   tor_assert(service_list);
   tor_assert(service);
 
@@ -291,34 +296,6 @@ rend_validate_service(const smartlist_t *service_list,
     goto invalid;
   }
 
-  /* XXX This duplicate check has two problems:
-   *
-   * a) It's O(n^2), but the same comment from the bottom of
-   *    rend_config_services() should apply.
-   *
-   * b) We only compare directory paths as strings, so we can't
-   *    detect two distinct paths that specify the same directory
-   *    (which can arise from symlinks, case-insensitivity, bind
-   *    mounts, etc.).
-   *
-   * It also can't detect that two separate Tor instances are trying
-   * to use the same HiddenServiceDir; for that, we would need a
-   * lock file.  But this is enough to detect a simple mistake that
-   * at least one person has actually made.
-   */
-  if (!rend_service_is_ephemeral(service)) {
-    /* Skip dupe for ephemeral services. */
-    SMARTLIST_FOREACH(service_list, rend_service_t *, ptr,
-                      dupe = dupe ||
-                      !strcmp(ptr->directory, service->directory));
-    if (dupe) {
-      log_warn(LD_REND, "Another hidden service is already configured for "
-                        "directory %s.",
-               rend_service_escaped_dir(service));
-      goto invalid;
-    }
-  }
-
   /* Valid. */
   return 0;
  invalid:
@@ -662,10 +639,8 @@ service_shadow_copy(rend_service_t *service, hs_service_t *hs_service)
 int
 rend_config_service(const config_line_t *line_,
                     const or_options_t *options,
-                    int validate_only,
                     hs_service_t *hs_service)
 {
-  (void) validate_only;
   const config_line_t *line;
   rend_service_t *service = NULL;
 
diff --git a/src/or/rendservice.h b/src/or/rendservice.h
index 90f854e4bc..361a119e49 100644
--- a/src/or/rendservice.h
+++ b/src/or/rendservice.h
@@ -143,9 +143,9 @@ STATIC void rend_service_prune_list_impl_(void);
 int num_rend_services(void);
 int rend_config_service(const config_line_t *line_,
                         const or_options_t *options,
-                        int validate_only,
                         hs_service_t *hs_service);
 void rend_service_prune_list(void);
+void rend_service_free_staging_list(void);
 int rend_service_load_all_keys(const smartlist_t *service_list);
 void rend_services_add_filenames_to_lists(smartlist_t *open_lst,
                                           smartlist_t *stat_lst);