1 files changed, 866 insertions, 0 deletions

diff --git a/src/service/messenger/gnunet-service-messenger_member_session.c b/src/service/messenger/gnunet-service-messenger_member_session.c
new file mode 100644
index 000000000..ed1fd75b7
--- /dev/null
+++ b/src/service/messenger/gnunet-service-messenger_member_session.c
@@ -0,0 +1,866 @@
+/*
+   This file is part of GNUnet.
+   Copyright (C) 2021--2023 GNUnet e.V.
+
+   GNUnet is free software: you can redistribute it and/or modify it
+   under the terms of the GNU Affero General Public License as published
+   by the Free Software Foundation, either version 3 of the License,
+   or (at your option) any later version.
+
+   GNUnet is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Affero General Public License for more details.
+
+   You should have received a copy of the GNU Affero General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+   SPDX-License-Identifier: AGPL3.0-or-later
+ */
+/**
+ * @author Tobias Frisch
+ * @file src/messenger/gnunet-service-messenger_member_session.c
+ * @brief GNUnet MESSENGER service
+ */
+
+#include "gnunet-service-messenger_member_session.h"
+
+#include "gnunet-service-messenger_room.h"
+#include "gnunet-service-messenger_message_store.h"
+
+#include "messenger_api_contact_store.h"
+
+struct GNUNET_MESSENGER_MemberSession*
+create_member_session (struct GNUNET_MESSENGER_Member *member,
+                       const struct GNUNET_CRYPTO_PublicKey *pubkey)
+{
+  if ((! member) || (! pubkey) || (! (member->store)))
+    return NULL;
+
+  struct GNUNET_MESSENGER_MemberSession *session = GNUNET_new (struct
+                                                               GNUNET_MESSENGER_MemberSession);
+  session->member = member;
+
+  GNUNET_memcpy (&(session->public_key), pubkey, sizeof(session->public_key));
+
+  get_context_from_member (
+    get_member_session_key (session),
+    get_member_session_id (session),
+    &(session->context)
+    );
+
+  struct GNUNET_MESSENGER_ContactStore *store = get_member_contact_store (
+    session->member->store);
+
+  session->contact = get_store_contact (
+    store,
+    get_member_session_context (session),
+    get_member_session_public_key (session)
+    );
+
+  if (! (session->contact))
+  {
+    GNUNET_free (session);
+    return NULL;
+  }
+
+  increase_contact_rc (session->contact);
+
+  session->history = GNUNET_CONTAINER_multihashmap_create (8, GNUNET_NO);
+
+  init_list_messages (&(session->messages));
+
+  session->prev = NULL;
+  session->next = NULL;
+
+  session->start = GNUNET_TIME_absolute_get ();
+
+  session->closed = GNUNET_NO;
+  session->completed = GNUNET_NO;
+
+  return session;
+}
+
+
+static void
+check_member_session_completion (struct GNUNET_MESSENGER_MemberSession *session)
+{
+  GNUNET_assert (session);
+
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+              "Check session history (%s) for completion.\n",
+              GNUNET_sh2s (get_member_session_id (session)));
+
+  if (! session->messages.tail)
+  {
+    session->completed = GNUNET_YES;
+    goto completion;
+  }
+
+  const struct GNUNET_HashCode *start = &(session->messages.head->hash);
+  const struct GNUNET_HashCode *end = &(session->messages.tail->hash);
+
+  struct GNUNET_MESSENGER_ListMessages level;
+  init_list_messages (&level);
+
+  add_to_list_messages (&level, end);
+
+  struct GNUNET_MESSENGER_MessageStore *store = get_srv_room_message_store (
+    session->member->store->room);
+
+  struct GNUNET_MESSENGER_ListMessages list;
+  init_list_messages (&list);
+
+  while (level.head)
+  {
+    struct GNUNET_MESSENGER_ListMessage *element;
+
+    for (element = level.head; element; element = element->next)
+    {
+      const struct GNUNET_MESSENGER_MessageLink *link = get_store_message_link (
+        store, &(element->hash), GNUNET_NO
+        );
+
+      if (! link)
+        continue;
+
+      add_to_list_messages (&list, &(link->first));
+
+      if (GNUNET_YES == link->multiple)
+        add_to_list_messages (&list, &(link->second));
+    }
+
+    clear_list_messages (&level);
+
+    for (element = list.head; element; element = element->next)
+      if (GNUNET_YES == check_member_session_history (session, &(element->hash),
+                                                      GNUNET_YES))
+        break;
+
+    if (element)
+      if (0 != GNUNET_CRYPTO_hash_cmp (&(element->hash), start))
+        add_to_list_messages (&level, &(element->hash));
+      else
+        session->completed = GNUNET_YES;
+    else
+      copy_list_messages (&level, &list);
+
+    clear_list_messages (&list);
+  }
+
+completion:
+  if (GNUNET_YES == is_member_session_completed (session))
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Completed session history (%s)\n",
+                GNUNET_sh2s (get_member_session_id (session)));
+
+    struct GNUNET_MESSENGER_ContactStore *store = get_member_contact_store (
+      session->member->store);
+
+    if ((session->contact) && (GNUNET_YES == decrease_contact_rc (
+                                 session->contact)))
+      remove_store_contact (
+        store,
+        session->contact,
+        get_member_session_context (session)
+        );
+
+    session->contact = NULL;
+  }
+}
+
+
+static enum GNUNET_GenericReturnValue
+iterate_copy_history (void *cls,
+                      const struct GNUNET_HashCode *key,
+                      void *value)
+{
+  struct GNUNET_MESSENGER_MemberSession *next = cls;
+
+  GNUNET_CONTAINER_multihashmap_put (next->history, key, (value? next : NULL),
+                                     GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_FAST);
+
+  return GNUNET_YES;
+}
+
+
+struct GNUNET_MESSENGER_MemberSession*
+switch_member_session (struct GNUNET_MESSENGER_MemberSession *session,
+                       const struct GNUNET_MESSENGER_Message *message,
+                       const struct GNUNET_HashCode *hash)
+{
+  if ((! session) || (! message) || (! hash))
+    return NULL;
+
+  GNUNET_assert ((GNUNET_MESSENGER_KIND_ID == message->header.kind) ||
+                 (GNUNET_MESSENGER_KIND_KEY == message->header.kind));
+
+  struct GNUNET_MESSENGER_MemberSession *next = GNUNET_new (struct
+                                                            GNUNET_MESSENGER_MemberSession);
+
+  if (GNUNET_MESSENGER_KIND_ID == message->header.kind)
+    next->member = add_store_member (session->member->store,
+                                     &(message->body.id.id));
+  else
+    next->member = session->member;
+
+  if (GNUNET_MESSENGER_KIND_KEY == message->header.kind)
+    GNUNET_memcpy (&(next->public_key), &(message->body.key.key),
+                   sizeof(next->public_key));
+  else
+    GNUNET_memcpy (&(next->public_key), get_member_session_public_key (session),
+                   sizeof(next->public_key));
+
+  get_context_from_member (
+    get_member_session_key (next),
+    get_member_session_id (next),
+    &(next->context)
+    );
+
+  update_store_contact (
+    get_member_contact_store (next->member->store),
+    get_member_session_contact (session),
+    get_member_session_context (session),
+    get_member_session_context (next),
+    get_member_session_public_key (next)
+    );
+
+  next->contact = get_member_session_contact (session);
+
+  if (! (next->contact))
+  {
+    GNUNET_free (next);
+    return NULL;
+  }
+
+  increase_contact_rc (next->contact);
+
+  next->history = GNUNET_CONTAINER_multihashmap_create (
+    GNUNET_CONTAINER_multihashmap_size (session->history), GNUNET_NO
+    );
+
+  GNUNET_CONTAINER_multihashmap_iterate (session->history, iterate_copy_history,
+                                         next);
+
+  init_list_messages (&(next->messages));
+  copy_list_messages (&(next->messages), &(session->messages));
+
+  session->next = next;
+  next->prev = session;
+  next->next = NULL;
+
+  next->start = GNUNET_TIME_absolute_get ();
+
+  session->closed = GNUNET_YES;
+  next->closed = GNUNET_NO;
+  next->completed = GNUNET_NO;
+
+  check_member_session_completion (session);
+
+  return next;
+}
+
+
+void
+destroy_member_session (struct GNUNET_MESSENGER_MemberSession *session)
+{
+  GNUNET_assert (session);
+
+  GNUNET_CONTAINER_multihashmap_destroy (session->history);
+
+  clear_list_messages (&(session->messages));
+
+  struct GNUNET_MESSENGER_Contact *contact = get_member_session_contact (
+    session);
+
+  if ((contact) && (GNUNET_YES == decrease_contact_rc (contact)))
+    remove_store_contact (
+      get_member_contact_store (session->member->store),
+      contact,
+      get_member_session_context (session)
+      );
+
+  GNUNET_free (session);
+}
+
+
+enum GNUNET_GenericReturnValue
+reset_member_session (struct GNUNET_MESSENGER_MemberSession *session,
+                      const struct GNUNET_HashCode *hash)
+{
+  GNUNET_assert ((session) && (hash));
+
+  struct GNUNET_MESSENGER_ContactStore *store = get_member_contact_store (
+    session->member->store);
+  struct GNUNET_MESSENGER_Contact *contact = get_store_contact (
+    store,
+    get_member_session_context (session),
+    get_member_session_public_key (session)
+    );
+
+  if (! contact)
+    return GNUNET_SYSERR;
+
+  if (contact == session->contact)
+    goto clear_messages;
+
+  session->contact = contact;
+  increase_contact_rc (session->contact);
+
+clear_messages:
+  clear_list_messages (&(session->messages));
+  add_to_list_messages (&(session->messages), hash);
+
+  session->next = NULL;
+  session->closed = GNUNET_NO;
+  session->completed = GNUNET_NO;
+
+  return GNUNET_OK;
+}
+
+
+void
+close_member_session (struct GNUNET_MESSENGER_MemberSession *session)
+{
+  GNUNET_assert (session);
+
+  session->closed = GNUNET_YES;
+  check_member_session_completion (session);
+}
+
+
+enum GNUNET_GenericReturnValue
+is_member_session_closed (const struct GNUNET_MESSENGER_MemberSession *session)
+{
+  GNUNET_assert (session);
+
+  return session->closed;
+}
+
+
+enum GNUNET_GenericReturnValue
+is_member_session_completed (const struct
+                             GNUNET_MESSENGER_MemberSession *session)
+{
+  GNUNET_assert (session);
+
+  return session->completed;
+}
+
+
+struct GNUNET_TIME_Absolute
+get_member_session_start (const struct GNUNET_MESSENGER_MemberSession *session)
+{
+  GNUNET_assert (session);
+
+  if (session->prev)
+    return get_member_session_start (session->prev);
+
+  return session->start;
+}
+
+
+const struct GNUNET_HashCode*
+get_member_session_key (const struct GNUNET_MESSENGER_MemberSession *session)
+{
+  GNUNET_assert ((session) && (session->member));
+
+  return get_member_store_key (session->member->store);
+}
+
+
+const struct GNUNET_ShortHashCode*
+get_member_session_id (const struct GNUNET_MESSENGER_MemberSession *session)
+{
+  GNUNET_assert (session);
+
+  return get_member_id (session->member);
+}
+
+
+const struct GNUNET_CRYPTO_PublicKey*
+get_member_session_public_key (const struct
+                               GNUNET_MESSENGER_MemberSession *session)
+{
+  GNUNET_assert (session);
+
+  return &(session->public_key);
+}
+
+
+const struct GNUNET_HashCode*
+get_member_session_context (const struct
+                            GNUNET_MESSENGER_MemberSession *session)
+{
+  GNUNET_assert (session);
+
+  return &(session->context);
+}
+
+
+struct GNUNET_MESSENGER_Contact*
+get_member_session_contact (struct GNUNET_MESSENGER_MemberSession *session)
+{
+  GNUNET_assert (session);
+
+  return session->contact;
+}
+
+
+enum GNUNET_GenericReturnValue
+verify_member_session_as_sender (const struct
+                                 GNUNET_MESSENGER_MemberSession *session,
+                                 const struct GNUNET_MESSENGER_Message *message,
+                                 const struct GNUNET_HashCode *hash)
+{
+  GNUNET_assert ((session) && (message) && (hash));
+
+  if (GNUNET_YES == is_member_session_completed (session))
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Check message (%s) using history!\n",
+                GNUNET_h2s (hash));
+
+    if (GNUNET_YES == check_member_session_history (session, hash, GNUNET_YES))
+      return GNUNET_OK;
+    else
+      return GNUNET_SYSERR;
+  }
+
+  if (0 != GNUNET_memcmp (get_member_session_id (session),
+                          &(message->header.sender_id)))
+    return GNUNET_SYSERR;
+
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Check message (%s) using key: %s\n",
+              GNUNET_h2s (hash),
+              GNUNET_CRYPTO_public_key_to_string (
+                get_member_session_public_key (session)));
+
+  return verify_message (message, hash, get_member_session_public_key (
+                           session));
+}
+
+
+enum GNUNET_GenericReturnValue
+check_member_session_history (const struct
+                              GNUNET_MESSENGER_MemberSession *session,
+                              const struct GNUNET_HashCode *hash,
+                              enum GNUNET_GenericReturnValue ownership)
+{
+  GNUNET_assert ((session) && (hash));
+
+  if (GNUNET_YES == ownership)
+    return (NULL != GNUNET_CONTAINER_multihashmap_get (session->history, hash)?
+            GNUNET_YES : GNUNET_NO);
+  else
+    return GNUNET_CONTAINER_multihashmap_contains (session->history, hash);
+}
+
+
+static void
+update_member_chain_history (struct GNUNET_MESSENGER_MemberSession *session,
+                             const struct GNUNET_HashCode *hash,
+                             enum GNUNET_GenericReturnValue ownership)
+{
+  GNUNET_assert ((session) && (hash));
+
+  if ((GNUNET_OK == GNUNET_CONTAINER_multihashmap_put (session->history, hash,
+                                                       (GNUNET_YES == ownership?
+                                                        session : NULL),
+                                                       GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_FAST))
+      && (session->next))
+    update_member_chain_history (session->next, hash, ownership);
+}
+
+
+void
+update_member_session_history (struct GNUNET_MESSENGER_MemberSession *session,
+                               const struct GNUNET_MESSENGER_Message *message,
+                               const struct GNUNET_HashCode *hash)
+{
+  GNUNET_assert ((session) && (message) && (hash));
+
+  if (GNUNET_YES == is_member_session_completed (session))
+    return;
+
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+              "Updating sessions history (%s) += (%s)\n",
+              GNUNET_sh2s (get_member_session_id (session)), GNUNET_h2s (hash));
+
+  if (GNUNET_OK == verify_member_session_as_sender (session, message, hash))
+  {
+    if (GNUNET_YES == is_message_session_bound (message))
+      add_to_list_messages (&(session->messages), hash);
+
+    update_member_chain_history (session, hash, GNUNET_YES);
+  }
+  else
+    update_member_chain_history (session, hash, GNUNET_NO);
+
+  if (GNUNET_YES == session->closed)
+    check_member_session_completion (session);
+}
+
+
+static void
+clear_member_chain_history (struct GNUNET_MESSENGER_MemberSession *session,
+                            const struct GNUNET_HashCode *hash)
+{
+  GNUNET_assert ((session) && (hash));
+
+  if ((0 < GNUNET_CONTAINER_multihashmap_remove_all (session->history, hash)) &&
+      (session->next))
+    clear_member_session_history (session->next, hash);
+}
+
+
+void
+clear_member_session_history (struct GNUNET_MESSENGER_MemberSession *session,
+                              const struct GNUNET_HashCode *hash)
+{
+  GNUNET_assert ((session) && (hash));
+
+  clear_member_chain_history (session, hash);
+}
+
+
+struct GNUNET_MESSENGER_MemberSessionHistoryEntry
+{
+  struct GNUNET_HashCode hash;
+  unsigned char ownership;
+};
+
+static void
+load_member_session_history (struct GNUNET_MESSENGER_MemberSession *session,
+                             const char *path)
+{
+  GNUNET_assert ((session) && (path));
+
+  if (GNUNET_YES != GNUNET_DISK_file_test (path))
+    return;
+
+  enum GNUNET_DISK_AccessPermissions permission = (GNUNET_DISK_PERM_USER_READ
+                                                   | GNUNET_DISK_PERM_USER_WRITE
+                                                   );
+
+  struct GNUNET_DISK_FileHandle *handle = GNUNET_DISK_file_open (
+    path, GNUNET_DISK_OPEN_READ, permission
+    );
+
+  if (! handle)
+    return;
+
+  GNUNET_DISK_file_seek (handle, 0, GNUNET_DISK_SEEK_SET);
+
+  struct GNUNET_MESSENGER_MemberSessionHistoryEntry entry;
+  ssize_t len;
+
+  enum GNUNET_GenericReturnValue status;
+
+  do {
+    len = GNUNET_DISK_file_read (handle, &(entry.hash), sizeof(entry.hash));
+
+    if (len != sizeof(entry.hash))
+      break;
+
+    len = GNUNET_DISK_file_read (handle, &(entry.ownership),
+                                 sizeof(entry.ownership));
+
+    if (len != sizeof(entry.ownership))
+      break;
+
+    status = GNUNET_CONTAINER_multihashmap_put (session->history, &(entry.hash),
+                                                (entry.ownership? session :
+                                                 NULL),
+                                                GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_FAST);
+  } while (status == GNUNET_OK);
+
+  GNUNET_DISK_file_close (handle);
+}
+
+
+void
+load_member_session (struct GNUNET_MESSENGER_Member *member,
+                     const char *directory)
+{
+  GNUNET_assert ((member) && (directory));
+
+  char *config_file;
+  GNUNET_asprintf (&config_file, "%s%s", directory, "session.cfg");
+
+  struct GNUNET_MESSENGER_MemberSession *session = NULL;
+
+  if (GNUNET_YES != GNUNET_DISK_file_test (config_file))
+    goto free_config;
+
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+              "Load session configuration of member: %s\n", config_file);
+
+  struct GNUNET_CONFIGURATION_Handle *cfg = GNUNET_CONFIGURATION_create ();
+
+  if (GNUNET_OK == GNUNET_CONFIGURATION_parse (cfg, config_file))
+  {
+    char *key_data;
+
+    if (GNUNET_OK != GNUNET_CONFIGURATION_get_value_string (cfg, "session",
+                                                            "key", &key_data))
+      goto destroy_config;
+
+    struct GNUNET_CRYPTO_PublicKey key;
+
+    enum GNUNET_GenericReturnValue key_return =
+      GNUNET_CRYPTO_public_key_from_string (key_data, &key);
+
+    GNUNET_free (key_data);
+
+    if (GNUNET_OK != key_return)
+      goto destroy_config;
+
+    session = create_member_session (member, &key);
+
+    unsigned long long numeric_value;
+
+    if (GNUNET_OK == GNUNET_CONFIGURATION_get_value_number (cfg, "session",
+                                                            "start",
+                                                            &numeric_value))
+      session->start.abs_value_us = numeric_value;
+
+    if (GNUNET_OK == GNUNET_CONFIGURATION_get_value_number (cfg, "session",
+                                                            "closed",
+                                                            &numeric_value))
+      session->closed = (GNUNET_YES == numeric_value? GNUNET_YES : GNUNET_NO);
+
+    if (GNUNET_OK == GNUNET_CONFIGURATION_get_value_number (cfg, "session",
+                                                            "completed",
+                                                            &numeric_value))
+      session->completed = (GNUNET_YES == numeric_value? GNUNET_YES :
+                            GNUNET_NO);
+  }
+
+destroy_config:
+  GNUNET_CONFIGURATION_destroy (cfg);
+
+free_config:
+  GNUNET_free (config_file);
+
+  if (! session)
+    return;
+
+  char *history_file;
+  GNUNET_asprintf (&history_file, "%s%s", directory, "history.map");
+
+  load_member_session_history (session, history_file);
+  GNUNET_free (history_file);
+
+  char *messages_file;
+  GNUNET_asprintf (&messages_file, "%s%s", directory, "messages.list");
+
+  load_list_messages (&(session->messages), messages_file);
+  GNUNET_free (messages_file);
+
+  add_member_session (member, session);
+}
+
+
+static struct GNUNET_MESSENGER_MemberSession*
+get_cycle_safe_next_session (struct GNUNET_MESSENGER_MemberSession *session,
+                             struct GNUNET_MESSENGER_MemberSession *next)
+{
+  if (! next)
+    return NULL;
+
+  struct GNUNET_MESSENGER_MemberSession *check = next;
+
+  do {
+    if (check == session)
+      return NULL;
+
+    check = check->next;
+  } while (check);
+
+  return next;
+}
+
+
+void
+load_member_session_next (struct GNUNET_MESSENGER_MemberSession *session,
+                          const char *directory)
+{
+  GNUNET_assert ((session) && (directory));
+
+  char *config_file;
+  GNUNET_asprintf (&config_file, "%s%s", directory, "session.cfg");
+
+  if (GNUNET_YES != GNUNET_DISK_file_test (config_file))
+    goto free_config;
+
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+              "Load next session configuration of member: %s\n", config_file);
+
+  struct GNUNET_CONFIGURATION_Handle *cfg = GNUNET_CONFIGURATION_create ();
+
+  if (GNUNET_OK == GNUNET_CONFIGURATION_parse (cfg, config_file))
+  {
+    char *key_data;
+
+    if (GNUNET_OK != GNUNET_CONFIGURATION_get_value_string (cfg, "session",
+                                                            "next_key",
+                                                            &key_data))
+      goto destroy_config;
+
+    struct GNUNET_CRYPTO_PublicKey next_key;
+
+    enum GNUNET_GenericReturnValue key_return =
+      GNUNET_CRYPTO_public_key_from_string (key_data, &next_key);
+
+    GNUNET_free (key_data);
+
+    if (GNUNET_OK != key_return)
+      goto destroy_config;
+
+    struct GNUNET_ShortHashCode next_id;
+
+    if (GNUNET_OK != GNUNET_CONFIGURATION_get_data (cfg, "session", "next_id",
+                                                    &next_id, sizeof(next_id)))
+      goto destroy_config;
+
+    struct GNUNET_MESSENGER_Member *member = get_store_member (
+      session->member->store, &next_id);
+
+    session->next = get_cycle_safe_next_session (
+      session, member? get_member_session (member, &next_key) : NULL
+      );
+
+    if (session->next)
+      session->next->prev = session;
+  }
+
+destroy_config:
+  GNUNET_CONFIGURATION_destroy (cfg);
+
+free_config:
+  GNUNET_free (config_file);
+}
+
+
+static enum GNUNET_GenericReturnValue
+iterate_save_member_session_history_hentries (void *cls,
+                                              const struct GNUNET_HashCode *key,
+                                              void *value)
+{
+  struct GNUNET_DISK_FileHandle *handle = cls;
+  unsigned char ownership = value? GNUNET_YES : GNUNET_NO;
+
+  GNUNET_DISK_file_write (handle, key, sizeof(*key));
+  GNUNET_DISK_file_write (handle, &ownership, sizeof(ownership));
+
+  return GNUNET_YES;
+}
+
+
+static void
+save_member_session_history (struct GNUNET_MESSENGER_MemberSession *session,
+                             const char *path)
+{
+  GNUNET_assert ((session) && (path));
+
+  enum GNUNET_DISK_AccessPermissions permission = (GNUNET_DISK_PERM_USER_READ
+                                                   | GNUNET_DISK_PERM_USER_WRITE
+                                                   );
+
+  struct GNUNET_DISK_FileHandle *handle = GNUNET_DISK_file_open (
+    path, GNUNET_DISK_OPEN_CREATE | GNUNET_DISK_OPEN_WRITE, permission
+    );
+
+  if (! handle)
+    return;
+
+  GNUNET_DISK_file_seek (handle, 0, GNUNET_DISK_SEEK_SET);
+
+  GNUNET_CONTAINER_multihashmap_iterate (
+    session->history,
+    iterate_save_member_session_history_hentries,
+    handle
+    );
+
+  GNUNET_DISK_file_sync (handle);
+  GNUNET_DISK_file_close (handle);
+}
+
+
+void
+save_member_session (struct GNUNET_MESSENGER_MemberSession *session,
+                     const char *directory)
+{
+  GNUNET_assert ((session) && (directory));
+
+  char *config_file;
+  GNUNET_asprintf (&config_file, "%s%s", directory, "session.cfg");
+
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+              "Save session configuration of member: %s\n", config_file);
+
+  struct GNUNET_CONFIGURATION_Handle *cfg = GNUNET_CONFIGURATION_create ();
+
+  char *key_data = GNUNET_CRYPTO_public_key_to_string (
+    get_member_session_public_key (session));
+
+  if (key_data)
+  {
+    GNUNET_CONFIGURATION_set_value_string (cfg, "session", "key", key_data);
+
+    GNUNET_free (key_data);
+  }
+
+  if (session->next)
+  {
+    const struct GNUNET_ShortHashCode *next_id = get_member_session_id (
+      session->next);
+
+    char *next_id_data = GNUNET_STRINGS_data_to_string_alloc (next_id,
+                                                              sizeof(*next_id));
+
+    if (next_id_data)
+    {
+      GNUNET_CONFIGURATION_set_value_string (cfg, "session", "next_id",
+                                             next_id_data);
+
+      GNUNET_free (next_id_data);
+    }
+
+    key_data = GNUNET_CRYPTO_public_key_to_string (
+      get_member_session_public_key (session->next));
+
+    if (key_data)
+    {
+      GNUNET_CONFIGURATION_set_value_string (cfg, "session", "next_key",
+                                             key_data);
+
+      GNUNET_free (key_data);
+    }
+  }
+
+  GNUNET_CONFIGURATION_set_value_number (cfg, "session", "start",
+                                         session->start.abs_value_us);
+
+  GNUNET_CONFIGURATION_set_value_number (cfg, "session", "closed",
+                                         session->closed);
+  GNUNET_CONFIGURATION_set_value_number (cfg, "session", "completed",
+                                         session->completed);
+
+  GNUNET_CONFIGURATION_write (cfg, config_file);
+  GNUNET_CONFIGURATION_destroy (cfg);
+
+  GNUNET_free (config_file);
+
+  char *history_file;
+  GNUNET_asprintf (&history_file, "%s%s", directory, "history.map");
+
+  save_member_session_history (session, history_file);
+  GNUNET_free (history_file);
+
+  char *messages_file;
+  GNUNET_asprintf (&messages_file, "%s%s", directory, "messages.list");
+
+  save_list_messages (&(session->messages), messages_file);
+  GNUNET_free (messages_file);
+}