/*
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   Copyright (C) 2011-2014 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
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   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
 */

/**
 * @file ats/gnunet-service-ats_addresses.h
 * @brief ats service address management
 * @author Matthias Wachs
 * @author Christian Grothoff
 */
#ifndef GNUNET_SERVICE_ATS_ADDRESSES_H
#define GNUNET_SERVICE_ATS_ADDRESSES_H

#include "gnunet_util_lib.h"
#include "gnunet_ats_service.h"
#include "gnunet-service-ats.h"
#include "ats.h"

/**
 * NOTE: Do not change this documentation. This documentation is based on
 * gnunet.org:/vcs/fsnsg/ats-paper.git/tech-doku/ats-tech-guide.tex
 * use build_txt.sh to generate plaintext output
 *
 *   1 ATS addresses : ATS address management
 *
 *    This ATS addresses ("addresses") component manages the addresses known to
 *    ATS service and suggests addresses to transport service when it is
 *    interested in address suggestion for a peer. ATS addresses also
 *    instantiates the bandwidth assignment mechanism (solver), notifies it
 *    about changes to addresses and forwards changes to bandwidth assignments
 *    to transport, depending if transport is interested in this change.
 *
 *     1.1 Input data
 *
 *       1.1.1 Addresses
 *
 *    Addresses are added by specifying peer ID, plugin, address, address length
 *    and session, if available. ATS information can be specified if available.
 *
 *       1.1.2 Networks
 *
 *    ATS specifies a fix set of networks an address can belong to. For each
 *    network an inbound and outbound quota will be specified. The available
 *    networks and addtional helper varaibles are defined in
 *    gnunet_ats_service.h. At the moment 5 networks are defined:
 *      * GNUNET_NT_UNSPECIFIED
 *      * GNUNET_NT_LOOPBACK
 *      * GNUNET_NT_LAN
 *      * GNUNET_NT_WAN
 *      * GNUNET_NT_WLAN
 *
 *    The total number of networks defined is stored in
 *    GNUNET_NT_COUNT GNUNET_ATS_NetworkType can be used array
 *    initializer for an int array, while GNUNET_ATS_NetworkType is an
 *    initializer for a char array containing a string description of all
 *    networks
 *
 *       1.1.3 Quotas
 *
 *    An inbound and outbound quota for each of the networks mentioned in 1.1.2
 *    is loaded from ats configuration during initialization. This quota defines
 *    to total amount of inbound and outbound traffic allowed for a specific
 *    network. The configuration values used are in section ats:
 *      * "NETWORK"_QUOTA_IN = <value>
 *      * "NETWORK"_QUOTA_IN = <value>
 *
 *    You can specify quotas by setting the <value> to a:
 *      * unrestricted: unlimited
 *      * number of bytes: e.g. 10240
 *      * fancy value: e.g. 64 Kib
 *
 *    unlimited is defined as GNUNET_ATS_MaxBandwidthString and equivalent to
 *    the value GNUNET_ATS_MaxBandwidth Important predefined values for quotas
 *    are:
 *      * GNUNET_ATS_DefaultBandwidth: 65536
 *      * GNUNET_ATS_MaxBandwidth: UINT32_MAX
 *      * GNUNET_CONSTANTS_DEFAULT_BW_IN_OUT: 1024
 *
 *    Details of loading quotas and default values will be described on
 *
 *       1.1.4 Preference values
 *
 *     1.2 Data structures used
 *
 *    Addresse uses struct ATS_Address for each address. The structs are stored
 *    in a linked list and provides a pointer void *solver_information for the
 *    solver to store address specific information. It provides the int values
 *    active which is set to GNUNET_YES if the address is select for transport
 *    use and used, representing that transport service is actively using this
 *    address. Address information are stored in peer, addr, addr_len, plugin.
 *
 *     1.3 Initialization
 *
 *    During initialization a hashmap to store addresses is created. The quotas
 *    for all networks defined for ATS are loaded from configuration. For each
 *    network first the logic will check if the string
 *    GNUNET_ATS_MaxBandwidthString is configured, if not it will try to convert
 *    the configured value as a fancy size and if this fails it will try to use
 *    it as a value_number. If no configuration value is found it will assign
 *    GNUNET_ATS_DefaultBandwidth. The most important step is to load the
 *    configured solver using configuration "[ats]:MODE". Current solvers are
 *    MODE_PROPORTIONAL, MODE_MLP. Interaction is done using a solver API
 *
 *     1.4 Solver API
 *
 *    Solver functions:
 *      * s_init: init the solver with required information
 *      * s_add: add a new address
 *      * s_update: update ATS values or session for an address
 *      * s_get: get prefered address for a peer
 *      * s_del: delete an address
 *      * s_pref: change preference value for a peer
 *      * s_done: shutdown solver
 *
 *    Callbacks: addresses provides a bandwidth_changed_cb callback to the
 *    solver which is called when bandwidth assigned to peer has changed
 *
 *     1.5 Shutdown
 *
 *    During shutdown all addresses are freed and the solver told to shutdown
 *
 *     1.6 Addresses and sessions
 *
 *    Addresses consist of the address itself and a numerical session. When a
 *    new address without a session is added it has no session, so it gets
 *    session 0 assigned. When an address with a session is added and an address
 *    object with session 0 is found, this object is updated with the session
 *    otherwise a new address object with this session assigned is created.
 *
 *       1.6.1 Terminology
 *
 *    Addresses a1,a2 with session s1, s2 are "exact" if:
 *    (a1 == a2)&&(s1 == s2)
 *    Addresses a1,a2 with session s1, s2 are "equivalent" if:
 *    (a1 == a2)&&((s1 == s2)||(s1 == 0)||(s2 == 0)
 *
 *     1.7 Address management
 *
 *    Transport service notifies ATS about changes to the addresses known to
 *    it.
 *
 *       1.7.1 Adding an address
 *
 *    When transport learns a new address it tells ATS and ATS is telling
 *    addresses about it using GAS_address_add. If not known to addresses it
 *    creates a new address object and calls solver's s_add. ATS information are
 *    deserialized and solver is notified about the session and ATS information
 *    using s_update.
 *
 *       1.7.2 Updating an address
 *
 *    Addresses does an lookup up for the existing address with the given
 *    session. If disassembles included ATS information and notifies the solver
 *    using s_update about the update.
 *
 *       1.7.3 Deleting an address
 *
 *    Addresses does an lookup for the exact address and session and if removes
 *    this address. If session != 0 the session is set to 0 and the address is
 *    kept. If session == 0, the addresses is removed.
 *
 *       1.7.4 Requesting an address suggestion
 *
 *    The address client issues a request address message to be notified about
 *    address suggestions for a specific peer. Addresses asks the solver with
 *    s_get. If no address is available, it will not send a response, otherwise
 *    it will respond with the choosen address.
 *
 *       1.7.5 Address suggestions
 *
 *    Addresses will notify the client automatically on any bandwidth_changed_cb
 *    by the solver if a address suggestion request is pending. If no address is
 *    available it will not respond at all If the client is not interested
 *    anymore, it has to cancel the address suggestion request.
 *
 *       1.7.6 Suggestions blocks and reset
 *
 *    After suggesting an address it is blocked for ATS_BLOCKING_DELTA sec. to
 *    prevent the client from being thrashed. If the client requires immediately
 *    it can reset this block using GAS_addresses_handle_backoff_reset.
 *
 *       1.7.7 Address lifecycle
 *
 *      * (add address)
 *      * (updated address)
 *      * (delete address)
 *
 *     1.8 Bandwidth assignment
 *
 *    The addresses are used to perform resource allocation operations. ATS
 *    addresses takes care of instantiating the solver configured and notifies
 *    the respective solver about address changes and receives changes to the
 *    bandwidth assignment from the solver. The current bandwidth assignment is
 *    sent to transport. The specific solvers will be described in the specific
 *    section.
 *
 *     1.9 Changing peer preferences
 *
 *    The bandwidth assigned to a peer can be influenced by setting a preference
 *    for a peer. The prefernce will be given to to the solver with s_pref which
 *    has to take care of the preference value
 */


/*
 * How long will address suggestions blocked after a suggestion
 */
#define ATS_BLOCKING_DELTA GNUNET_TIME_relative_multiply ( \
    GNUNET_TIME_UNIT_MILLISECONDS, 100)

/**
 * Information provided by ATS normalization
 */
struct GAS_NormalizationInfo
{
  /**
   * Next index to use in averaging queue
   */
  unsigned int avg_queue_index;

  /**
   * Averaging queue
   */
  uint64_t atsi_abs[GAS_normalization_queue_length];

  /**
   * Averaged ATSI values from queue
   */
  uint64_t avg;

  /**
   * Normalized values from queue to a range of values [1.0...2.0]
   */
  double norm;
};


/**
 * Address with additional information
 */
struct ATS_Address
{
  /**
   * Peer ID this address is for.
   */
  struct GNUNET_PeerIdentity peer;

  /**
   * Address (in plugin-specific binary format).
   */
  const void *addr;

  /**
   * Plugin name
   */
  char *plugin;

  /**
   * Solver-specific information for this address
   */
  void *solver_information;

  /**
   * ATS performance information for this address
   */
  struct GNUNET_ATS_Properties properties;

  /**
   * Time when address had last activity (update, in uses)
   */
  struct GNUNET_TIME_Absolute t_last_activity;

  /**
   * Time when address was added
   */
  struct GNUNET_TIME_Absolute t_added;

  /**
   * Address length, number of bytes in @e addr.
   */
  size_t addr_len;

  /**
   * Session ID, can never be 0.
   */
  uint32_t session_id;

  /**
   * Field to store local flags.
   */
  enum GNUNET_HELLO_AddressInfo local_address_info;

  /**
   * ATS performance information for this address, size of the @e atsi array.
   */
  uint32_t atsi_count;

  /**
   * Inbound bandwidth assigned by solver
   */
  uint32_t assigned_bw_in;

  /**
   * Outbound bandwidth assigned by solver
   */
  uint32_t assigned_bw_out;

  /**
   * Inbound bandwidth assigned by solver in NBO
   */
  uint32_t last_notified_bw_in;

  /**
   * Outbound bandwidth assigned by solver in NBO
   */
  uint32_t last_notified_bw_out;

  /**
   * Is this the active address for this peer?
   */
  int active;

  /**
   * Normalized delay information for this address.
   */
  struct GAS_NormalizationInfo norm_delay;

  /**
   * Normalized distance information for this address.
   */
  struct GAS_NormalizationInfo norm_distance;

  /**
   * Normalized utilization inbound for this address.
   */
  struct GAS_NormalizationInfo norm_utilization_in;

  /**
   * Normalized utilization outbound for this address.
   */
  struct GAS_NormalizationInfo norm_utilization_out;
};


/**
 * A multipeermap mapping peer identities to `struct ATS_Address`.
 */
extern struct GNUNET_CONTAINER_MultiPeerMap *GSA_addresses;


/**
 * Initialize address subsystem. The addresses subsystem manages the addresses
 * known and current performance information.
 */
void
GAS_addresses_init (void);


/**
 * Shutdown address subsystem.
 */
void
GAS_addresses_done (void);


/**
 * Add a new address for a peer.
 *
 * @param peer peer
 * @param plugin_name transport plugin name
 * @param plugin_addr plugin address
 * @param plugin_addr_len length of the @a plugin_addr
 * @param local_address_info the local address for the address
 * @param session_id session id, can never be 0.
 * @param prop performance information for this address
 */
void
GAS_addresses_add (const struct GNUNET_PeerIdentity *peer,
                   const char *plugin_name,
                   const void *plugin_addr,
                   size_t plugin_addr_len,
                   uint32_t local_address_info,
                   uint32_t session_id,
                   const struct GNUNET_ATS_Properties *prop);


/**
 * Update an address with new performance information for a peer.
 *
 * @param peer peer
 * @param session_id session id, can never be 0
 * @param prop performance information for this address
 */
void
GAS_addresses_update (const struct GNUNET_PeerIdentity *peer,
                      uint32_t session_id,
                      const struct GNUNET_ATS_Properties *prop);


/**
 * Remove an address for a peer.
 *
 * @param peer peer
 * @param session_id session id, can never be 0
 */
void
GAS_addresses_destroy (const struct GNUNET_PeerIdentity *peer,
                       uint32_t session_id);


/**
 * Remove all addresses.
 */
void
GAS_addresses_destroy_all (void);


/**
 * Iterator for #GAS_addresses_get_peer_info()
 *
 * @param cls closure
 * @param id the peer id
 * @param plugin_name plugin name
 * @param plugin_addr address
 * @param plugin_addr_len length of @a plugin_addr
 * @param address_active is address actively used
 * @param atsi ats performance information
 * @param local_address_info flags for the address
 * @param bandwidth_out current outbound bandwidth assigned to address
 * @param bandwidth_in current inbound bandwidth assigned to address
 */
typedef void
(*GNUNET_ATS_PeerInfo_Iterator) (void *cls,
                                 const struct GNUNET_PeerIdentity *id,
                                 const char *plugin_name,
                                 const void *plugin_addr,
                                 size_t plugin_addr_len,
                                 const int address_active,
                                 const struct GNUNET_ATS_Properties *prop,
                                 enum GNUNET_HELLO_AddressInfo
                                 local_address_info,
                                 struct GNUNET_BANDWIDTH_Value32NBO
                                 bandwidth_out,
                                 struct GNUNET_BANDWIDTH_Value32NBO
                                 bandwidth_in);


/**
 * Return information all peers currently known to ATS
 *
 * @param peer the respective peer
 * @param pi_it the iterator to call for every peer
 * @param pi_it_cls the closure for @a pi_it
 */
void
GAS_addresses_get_peer_info (const struct GNUNET_PeerIdentity *peer,
                             GNUNET_ATS_PeerInfo_Iterator pi_it,
                             void *pi_it_cls);


/**
 * Handle 'address list request' messages from clients.
 *
 * @param client client that sent the request
 * @param alrm the request message
 */
void
GAS_handle_request_address_list (struct GNUNET_SERVICE_Client *client,
                                 const struct AddressListRequestMessage *alrm);


#endif

/* end of gnunet-service-ats_addresses.h */
