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### 5.35 libnod

#### 5.35.1 Overview

View lcov test coverage results on http://www.gnu.org/software/liquidwar6/coverage/src/lib/nod/index.html.

#### 5.35.2 API

Function: int lw6nod_info_community_add (lw6nod_info_t * info, u_int64_t id, const char * url)

  info: node info object to modify

  id: ID of the new member

  url: URL of the new member, can be NULL

  Adds a new member to the community.

  Return value: 1 if new member could be added, 0 if not.

Function: int lw6nod_info_community_is_member (lw6nod_info_t * info, u_int64_t id, const char * url)

  info: node info object to test

  id: ID of the member we want to check

  url: URL of the member we want to check

  Tells wether a member is already in the community. Note that if there’s a member with the same URL but with a different ID, or a member with the same ID but a different URL, the function will fail, we need URLs and IDs to both be different for the peer to be added. Not respecting this would lead to confusion, while sharing an ID is conceivable over the whole network, it can’t be tolerated within a community. Same for the URL.

  Return value: 1 if new member could be added, 0 if not.

Function: int lw6nod_info_community_has_id (lw6nod_info_t * info, u_int64_t id)

  info: node info object to test

  id: ID of the member we want to check

  Tells wether a member exists with this ID. Will test both ourselves and remote peers.

  Return value: 1 if ID is already taken, 0 if available.

Function: int lw6nod_info_community_has_id_without_url (lw6nod_info_t * info, u_int64_t id)

  info: node info object to test

  id: ID of the member we want to check

  Tells wether a member exists with this ID, but for which we don’t know the URL, that is, url is NULL.

  Return value: 1 if ID is already taken and has NULL url, 0 else.

Function: int lw6nod_info_community_has_url (lw6nod_info_t * info, const char * url)

  info: node info object to test

  url: URL of the member we want to check

  Tells wether a member exists with this URL. Will test both ourselves and remote peers.

  Return value: 1 if URL is already taken, 0 if available.

Function: int lw6nod_info_community_remove_by_id (lw6nod_info_t * info, u_int64_t id)

  info: node info object to modify

  id: ID of the member we want to remove

  Removes a community member by ID.

  Return value: 1 if successfully removed, 0 if was not present.

Function: int lw6nod_info_community_remove_by_url (lw6nod_info_t * info, const char * url)

  info: node info object to modify

  url: URL of the member we want to remove

  Removes a community member by URL.

  Return value: 1 if successfully removed, 0 if was not present.

Function: int lw6nod_info_community_count (lw6nod_info_t * info)

  info: node info object to modify

  Tells how many members there are in a community. This include ourselves so this can never be 0, should at least be 1. Note that this is pretty much the same as the nb_nodes member of dyn_info, but this one is calculated dynamically from peer list, while the other one is updated from time to time from game_state information.

  Return value: number of community members, including this node (us).

Function: void lw6nod_info_community_reset (lw6nod_info_t * info)

  info: node info object to modify

  Resets all peers, set community to only one member, ourselves.

  Return value: none.

Function: char * lw6nod_info_community_get_peer_id_list_str (lw6nod_info_t * info)

  info: node to query

  Builds a string containing all peer ids, separated by a separator.

  Return value: newly allocated string

Function: void lw6nod_info_community_set_peer_id_list_str (lw6nod_info_t * info, const char * peer_id_list_str)

  info: node to modify

  peer_id_list_str: new value

  Interprets a peer_id_list_str and puts it into the node data structures. Note that this function won’t really copy the list, instead it will populate the dyn_info struct with the right values.

  Return value: none

Function: void lw6nod_info_community_id_without_url_map (lw6nod_info_t * info, lw6nod_id_callback_func_t func, void * func_data)

  info: node to process

  func: function to use as a callback

  func_data: data passed along with the function

  Applies function func to all the members of the community which have an id but not an URL...

  Return value: none.

Function: void lw6nod_dyn_info_free (lw6nod_dyn_info_t * dyn_info)

  dyn_info: the dyn info struct to free

  Frees a dyn info object, to be used after a call to `lw6nod_info_dup_dyn` for instance.

  Return value: none

Function: lw6nod_info_t * lw6nod_info_new (const char * program, const char * version, const char * codename, int stamp, u_int64_t id, const char * url, const char * title, const char * description, const char * password, int bench, int open_relay, int uptime, int idle_screenshot_size, void * idle_screenshot_data)

  program: the program (normally it’s liquidwar6)

  version: the version

  codename: the codename

  stamp: the stamp

  id: the node id

  url: the node public url

  title: the node title

  description: the node description

  password: the node password

  bench: the node bench

  open_relay: open relay or not

  uptime: uptime in seconds

  idle_screenshot_size: the size (bytes) of the image to display when game is idle

  idle_screenshot_data: the data (jpeg) of the image to display when game is idle

  Creates a node info object. The arguments correspond to the immutable node attributes, other properties such as how many players are connected or set in other functions like `lw6nod_info_update` which can be called later.

  Return value: newly allocated object, NULL on error.

Function: void lw6nod_info_free (lw6nod_info_t * info)

  info: the node info to free

  Frees a node info object.

  Return value: none

Function: int lw6nod_info_lock (lw6nod_info_t * info)

  info: the node info to lock

  Locks a node info object, this is usefull for some members, typically list of servers, can be accessed by separated threads, one reading, many writing, and these objects (chained lists) certainly do not want to be modified while being read.

  Return value: 1 if ok, 0 if not.

Function: int lw6nod_info_unlock (lw6nod_info_t * info)

  info: the node info to unlock

  Unlocks a node info object, this is the compation of the `lw6nod_info_lock` function.

  Return value: 1 if ok, 0 if not.

Function: void lw6nod_info_idle (lw6nod_info_t * info)

  info: the node info to modify

  Clears a node info object and sets all its variable attributes to NULL/default values. This is what we want when the node is idle, not playing.

  Return value: none.

Function: int lw6nod_info_update (lw6nod_info_t * info, u_int64_t community_id, int round, const char * level, int required_bench, int nb_colors, int max_nb_colors, int nb_cursors, int max_nb_cursors, int nb_nodes, int max_nb_nodes, const char * peer_id_list, int game_screenshot_size, void * game_screenshot_data)

  info: the node info to update

  community_id: the id of the community the node belongs to

  round: the current round (can have an offset with real round number)

  level: the name of the current level (map)

  required_bench: the bench required to connect

  nb_colors: number of colors playing

  max_nb_colors: max number of colors allowed

  nb_cursors: number of cursors playing

  max_nb_cursors: max number of cursors allowed

  nb_nodes: number of nodes playing

  max_nb_nodes: max number of nodes allowed

  peer_id_list: list of peers ids, can be NULL

  game_screenshot_size: size of screenshot (bytes)

  game_screenshot_data: screenshot data (byte buffer, contains JPEG)

  Set a node info object variable attributes. Call this whenever the node has changed some parameter. Not too often for it’s not needed and some operations such as modying the screenshot, can be time consuming.

  Return value: 1 if OK, 0 if error.

Function: lw6nod_dyn_info_t * lw6nod_info_dup_dyn (lw6nod_info_t * info)

  info: the node info containing the dyn info to duplicate

  Extracts the dynamic part of an info struct and duplicates it, this is to avoid protection fault error when concurrent threads access this info.

  Return value: newly allocated object, must be freed.

Function: lw6sys_hash_t * lw6nod_info_new_discovered_nodes ()

  Creates a new hash, to be used as a discovered nodes list. Using this function has the advantage of setting the hash options to their defaults. We use a hash to avoid having uselessly long lists containing always the same node due to multiple detections.

  Return value: an empty hash

Function: int lw6nod_info_add_discovered_node (lw6nod_info_t * info, const char * public_url)

  info: the node info to update

  public_url: the address of the discovered node

  Registers a new server, and queues it as something that should be checked later because it’s interesting. We can’t insert in the database all the servers we suspect to exist so network threads should use this, then main thread will process discovered servers afterwards. This is also a good way to avoid trivial DOS attacks.

  Return value: 1 if OK, O if error.

Function: lw6sys_list_t * lw6nod_info_pop_discovered_nodes (lw6nod_info_t * info)

  info: the node info to query

  Returns a list of all discovered nodes (their public URL) and empties the current queue as well.

  Return value: a list of dynamically allocated strings.

Function: lw6sys_list_t * lw6nod_info_new_verified_nodes ()

  Creates a new list, to be filled with nodes and typically passed to `lw6nod_info_set_verified_nodes`. Using this function has the advantage of setting the listh options to their defaults.

  Return value: an empty list

Function: int lw6nod_info_set_verified_nodes (lw6nod_info_t * info, lw6sys_list_t * list)

  info: the node info to modify

  list: the list of verified nodes, will be freed by this function

  Sets the list of verified nodes, that is, the list of nodes we are sure to exist, this is typically the list we will display later on a web page. We can’t directly display any discovered node, one needs to filter them through main thread. Something very important about this function is that `list` will be freed by function, that is, if you call this, then you can (you should) forget your object, it will disappear any time soon.

  Return value: 1 if OK, 0 on error.

Function: void lw6nod_info_map_verified_nodes (lw6nod_info_t * info, lw6sys_list_callback_func_t func, void * func_data)

  info: the node info concerned

  func: the function to apply

  func_data: arbitrary pointer holding data to pass to function

  Calls `lw6sys_hash_map` with `func` on every member of the list of verified nodes. The reason there’s a function for this is that it is very important that list object is locked when doing this. This function does perform a lock/unlock so it is safe.

  Return value: none.

Function: int lw6nod_test_register (int mode)

  mode: test mode (bitmask)

  Registers all tests for the libnod module.

  Return value: 1 if test is successfull, 0 on error.

Function: int lw6nod_test_run (int mode)

  mode: test mode (bitmask)

  Runs the `nod` module test suite, testing most (if not all...) functions.

  Return value: 1 if test is successfull, 0 on error.

Struct: lw6nod_const_info_s

  Constant informations about a node, these are informations that do not vary through the node’s life, so they are set object creation then left unchanged.

Member of lw6nod_const_info_s: program

  Type: `char *`

  Definition: `char* lw6nod_const_info_s::program`

  Program, this should be set to liquidwar6.

Member of lw6nod_const_info_s: version

  Type: `char *`

  Definition: `char* lw6nod_const_info_s::version`

  The version of the program.

Member of lw6nod_const_info_s: codename

  Type: `char *`

  Definition: `char* lw6nod_const_info_s::codename`

  The codename of the program.

Member of lw6nod_const_info_s: stamp

  Type: `int`

  Definition: `int lw6nod_const_info_s::stamp`

  The stamp of the program.

Member of lw6nod_const_info_s: ref_info

  Type: `lw6nod_ref_info_t`

  Definition: `lw6nod_ref_info_t lw6nod_const_info_s::ref_info`

  Reference information, how to uniquely identify node.

Member of lw6nod_const_info_s: title

  Type: `char *`

  Definition: `char* lw6nod_const_info_s::title`

  The title of the node, its readable short name.

Member of lw6nod_const_info_s: description

  Type: `char *`

  Definition: `char* lw6nod_const_info_s::description`

  More details about the node.

Member of lw6nod_const_info_s: has_password

  Type: `int`

  Definition: `int lw6nod_const_info_s::has_password`

  Wether the node is password protected or not.

Member of lw6nod_const_info_s: password

  Type: `char *`

  Definition: `char* lw6nod_const_info_s::password`

  The password used, cleartext.

Member of lw6nod_const_info_s: bench

  Type: `int`

  Definition: `int lw6nod_const_info_s::bench`

  The node bench.

Member of lw6nod_const_info_s: open_relay

  Type: `int`

  Definition: `int lw6nod_const_info_s::open_relay`

  Wether the node acts as an open relay or not.

Member of lw6nod_const_info_s: creation_timestamp

  Type: `int64_t`

  Definition: `int64_t lw6nod_const_info_s::creation_timestamp`

  The node creation timestamp.

Member of lw6nod_const_info_s: idle_screenshot_size

  Type: `int`

  Definition: `int lw6nod_const_info_s::idle_screenshot_size`

  Size of the screenshot (in bytes) when in idle mode.

Member of lw6nod_const_info_s: idle_screenshot_data

  Type: `void *`

  Definition: `void* lw6nod_const_info_s::idle_screenshot_data`

  Idle mode screenshot data. This is just a plain JPEG buffer, which will be used as a fallback if there’s no real screenshot available.

Struct: lw6nod_dyn_info_s

  Dynamic informations about a node, these are informations that vary through the node’s life, so they are unset at object creation and can then be updated from game context.

Member of lw6nod_dyn_info_s: community_id_int

  Type: `u_int64_t`

  Definition: `u_int64_t lw6nod_dyn_info_s::community_id_int`

  The ID of the community this node belongs to, as a 64-bit unsigned integer.

Member of lw6nod_dyn_info_s: community_id_str

  Type: `char *`

  Definition: `char* lw6nod_dyn_info_s::community_id_str`

  The ID of the community this node belongs to, as a string (64-bit integer converted to hexa).

Member of lw6nod_dyn_info_s: community_peers

  Type: `lw6nod_ref_info_t`

  Definition: `lw6nod_ref_info_t lw6nod_dyn_info_s::community_peers[LW6NOD_MAX_NB_PEERS]`

  The list of community members, you need to refer to the nb_nodes member to know quickly how many members they are but actually, in practice, there can be holes in this array, you need to check each slot, for instance 0 can be filled, 2 can be filled too, but 1 be empty. Note that we don’t count ourselves in this list.

Member of lw6nod_dyn_info_s: round

  Type: `int`

  Definition: `int lw6nod_dyn_info_s::round`

  The current round.

Member of lw6nod_dyn_info_s: level

  Type: `char *`

  Definition: `char* lw6nod_dyn_info_s::level`

  The current level.

Member of lw6nod_dyn_info_s: required_bench

  Type: `int`

  Definition: `int lw6nod_dyn_info_s::required_bench`

  The required bench to connect to this node.

Member of lw6nod_dyn_info_s: nb_colors

  Type: `int`

  Definition: `int lw6nod_dyn_info_s::nb_colors`

  Number of colors playing.

Member of lw6nod_dyn_info_s: max_nb_colors

  Type: `int`

  Definition: `int lw6nod_dyn_info_s::max_nb_colors`

  Maximum number of colors allowed to play.

Member of lw6nod_dyn_info_s: nb_cursors

  Type: `int`

  Definition: `int lw6nod_dyn_info_s::nb_cursors`

  Number of cursors playing.

Member of lw6nod_dyn_info_s: max_nb_cursors

  Type: `int`

  Definition: `int lw6nod_dyn_info_s::max_nb_cursors`

  Maximum number of cursors allowed to play.

Member of lw6nod_dyn_info_s: nb_nodes

  Type: `int`

  Definition: `int lw6nod_dyn_info_s::nb_nodes`

  Number of nodes playing.

Member of lw6nod_dyn_info_s: max_nb_nodes

  Type: `int`

  Definition: `int lw6nod_dyn_info_s::max_nb_nodes`

  Maximum number of nodes allowed to play.

Member of lw6nod_dyn_info_s: game_screenshot_size

  Type: `int`

  Definition: `int lw6nod_dyn_info_s::game_screenshot_size`

  Size of the screenshot, in bytes.

Member of lw6nod_dyn_info_s: game_screenshot_data

  Type: `void *`

  Definition: `void* lw6nod_dyn_info_s::game_screenshot_data`

  Game screenshot data. This is just a plain JPEG buffer, which will be served when peers and/or web clients want to gather informations about the game. This can be NULL, in that the fallback constant data will be used.

Struct: lw6nod_info_s

  Informations about a node. Note that in practice this structure is just used to describe our current node, there might be several instances of this if a program instanciates several nodes, but another data structure is used to store information about peers.typedef struct lw6nod_info_s

Member of lw6nod_info_s: mutex

  Type: `lw6sys_mutex_t *`

  Definition: `lw6sys_mutex_t* lw6nod_info_s::mutex`

  Mutex used to access dynamic informations.

Member of lw6nod_info_s: const_info

  Type: `lw6nod_const_info_t`

  Definition: `lw6nod_const_info_t lw6nod_info_s::const_info`

  Constant informations, never changes.

Member of lw6nod_info_s: dyn_info

  Type: `lw6nod_dyn_info_t`

  Definition: `lw6nod_dyn_info_t lw6nod_info_s::dyn_info`

  Dynamic informations, can be updated. Do not modify this directly, instead use appropriate functions which will use mutexes properly.

Member of lw6nod_info_s: discovered_nodes

  Type: `lw6sys_hash_t *`

  Definition: `lw6sys_hash_t* lw6nod_info_s::discovered_nodes`

  List of discovered nodes, do not access this directly, instead use proper query functions which, in turn, will use mutexes properly.

Member of lw6nod_info_s: verified_nodes

  Type: `lw6sys_list_t *`

  Definition: `lw6sys_list_t* lw6nod_info_s::verified_nodes`

  List of verified nodes, do not access this directly, instead use proper query functions which, in turn, will use mutexes properly.

Struct: lw6nod_ref_info_s

  Reference information about a node, this is all you need to uniquely identify a node. In theory, only the ID are only the URL are enough, in practice it’s not that bad to have some redundancy, plus it makes it easier and faster to connect to them and transmit informations.

Member of lw6nod_ref_info_s: id_int

  Type: `u_int64_t`

  Definition: `u_int64_t lw6nod_ref_info_s::id_int`

  The id of the node, as an integer (64-bit unsigned).

Member of lw6nod_ref_info_s: id_str

  Type: `char *`

  Definition: `char* lw6nod_ref_info_s::id_str`

  The id of the node, as a string (64-bit converted to hexa).

Member of lw6nod_ref_info_s: url

  Type: `char *`

  Definition: `char* lw6nod_ref_info_s::url`

  The public URL of the node.

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