(**************************************************************************) (* *) (* Copyright (c) 2014 - 2016. *) (* Dynamic Ledger Solutions, Inc. *) (* *) (* All rights reserved. No warranty, explicit or implicit, provided. *) (* *) (**************************************************************************) module LU = Lwt_unix module LC = Lwt_condition open Lwt.Infix open Logging.Net (* public types *) type addr = Ipaddr.t type port = int type version = { name : string ; major : int ; minor : int ; } let version_encoding = let open Data_encoding in conv (fun { name; major; minor } -> (name, major, minor)) (fun (name, major, minor) -> { name; major; minor }) (obj3 (req "name" string) (req "major" int8) (req "minor" int8)) type limits = { max_packet_size : int ; peer_answer_timeout : float ; expected_connections : int ; min_connections : int ; max_connections : int ; blacklist_time : float ; } type config = { incoming_port : port option ; discovery_port : port option ; known_peers : (addr * port) list ; peers_file : string ; closed_network : bool ; } (* The global net identificator. *) type gid = string let gid_length = 16 let pp_gid ppf gid = Format.pp_print_string ppf (Hex_encode.hex_encode gid) (* the common version for a pair of peers, if any, is the maximum one, in lexicographic order *) let common_version la lb = let la = List.sort (fun l r -> compare r l) la in let lb = List.sort (fun l r -> compare r l) lb in let rec find = function | [], _ | _, [] -> None | ((a :: ta) as la), ((b :: tb) as lb) -> if a = b then Some a else if a < b then find (ta, lb) else find (la, tb) in find (la, lb) (* A net point (address x port). *) type point = addr * port let point_encoding = let open Data_encoding in let open Ipaddr in conv (fun (addr, port) -> (match addr with | V4 v4 -> V4.to_bytes v4 | V6 v6 -> V6.to_bytes v6), port) (fun (addr, port) -> (match String.length addr with | 4 -> V4 (V4.of_bytes_exn addr) | 16 -> V6 (V6.of_bytes_exn addr) | _ -> Pervasives.failwith "point_encoding"), port) (obj2 (req "addr" string) (req "port" int16)) type 'msg encoding = Encoding : { tag: int ; encoding: 'a Data_encoding.t ; wrap: 'a -> 'msg ; unwrap: 'msg -> 'a option ; max_length: int option ; } -> 'msg encoding module type PARAMS = sig (** Type of message used by higher layers *) type msg val encodings : msg encoding list (** Type of metadata associated to an identity *) type metadata val initial_metadata : metadata val metadata_encoding : metadata Data_encoding.t val score : metadata -> float (** High level protocol(s) talked by the peer. When two peers initiate a connection, they exchange their list of supported versions. The chosen one, if any, is the maximum common one (in lexicographic order) *) val supported_versions : version list end module Make (P: PARAMS) = struct (* Low-level network protocol packets (internal). The protocol is completely symmetrical and asynchronous. First both peers must present their credentials with a [Connect] packet, then any combination of the other packets can be received at any time. An exception is the [Disconnect] message, which should mark the end of transmission (and needs not being replied). The [Unkown] packet is not a real kind of packet, it means that something indecypherable was transmitted. *) type msg = | Connect of { gid : string ; port : int option ; versions : version list ; public_key : Crypto_box.public_key ; proof_of_work : Crypto_box.nonce ; message_nonce : Crypto_box.nonce ; } | Disconnect | Bootstrap | Advertise of point list | Message of P.msg let msg_encoding = let open Data_encoding in union ~tag_size:`Uint16 ([ case ~tag:0x00 (obj6 (req "gid" (Fixed.string gid_length)) (req "port" uint16) (req "pubkey" Crypto_box.public_key_encoding) (req "proof_of_work" Crypto_box.nonce_encoding) (req "message_nonce" Crypto_box.nonce_encoding) (req "versions" (Variable.list version_encoding))) (function | Connect { gid ; port ; public_key ; proof_of_work ; message_nonce ; versions } -> let port = match port with None -> 0 | Some port -> port in Some (gid, port, public_key, proof_of_work, message_nonce, versions) | _ -> None) (fun (gid, port, public_key, proof_of_work, message_nonce, versions) -> let port = if port = 0 then None else Some port in Connect { gid ; port ; versions ; public_key ; proof_of_work ; message_nonce }); case ~tag:0x01 null (function Disconnect -> Some () | _ -> None) (fun () -> Disconnect); case ~tag:0x02 null (function Bootstrap -> Some () | _ -> None) (fun () -> Bootstrap); case ~tag:0x03 (Variable.list point_encoding) (function Advertise points -> Some points | _ -> None) (fun points -> Advertise points); ] @ ListLabels.map P.encodings ~f:(function Encoding { tag ; encoding ; wrap ; unwrap } -> case ~tag encoding (function Message msg -> unwrap msg | _ -> None) (fun msg -> Message (wrap msg)))) let hdrlen = 2 let maxlen = hdrlen + 2 lsl 16 (* read a message from a TCP socket *) let recv_msg ?(uncrypt = (fun buf -> Some buf)) fd buf = Lwt.catch begin fun () -> assert (MBytes.length buf >= 2 lsl 16) ; Lwt_utils.read_mbytes ~len:hdrlen fd buf >>= fun () -> let len = EndianBigstring.BigEndian.get_uint16 buf 0 in (* TODO timeout read ??? *) Lwt_utils.read_mbytes ~len fd buf >>= fun () -> let buf = MBytes.sub buf 0 len in match uncrypt buf with | None -> (* TODO track invalid message *) Lwt.return Disconnect | Some buf -> match Data_encoding.Binary.of_bytes msg_encoding buf with | None -> (* TODO track invalid message *) Lwt.return Disconnect | Some msg -> Lwt.return msg end (function | Unix.Unix_error _ | End_of_file -> Lwt.return Disconnect | e -> Lwt.fail e) (* send a message over a TCP socket *) let send_msg ?crypt fd buf msg = Lwt.catch begin fun () -> match Data_encoding.Binary.write msg_encoding msg buf hdrlen with | None -> Lwt.return_false | Some len -> match crypt with | None -> if len > maxlen then Lwt.return_false else begin EndianBigstring.BigEndian.set_int16 buf 0 (len - hdrlen) ; (* TODO timeout write ??? *) Lwt_utils.write_mbytes ~len fd buf >>= fun () -> Lwt.return_true end | Some crypt -> let encbuf = crypt (MBytes.sub buf hdrlen (len - hdrlen)) in let len = MBytes.length encbuf in if len > maxlen then Lwt.return_false else begin let lenbuf = MBytes.create 2 in EndianBigstring.BigEndian.set_int16 lenbuf 0 len ; Lwt_utils.write_mbytes fd lenbuf >>= fun () -> Lwt_utils.write_mbytes fd encbuf >>= fun () -> Lwt.return_true end end (function | Unix.Unix_error _ | End_of_file -> Lwt.return_false | e -> Lwt.fail e) (* The (internal) type of network events, those dispatched from peer workers to the net and others internal to net workers. *) type event = | Disconnected of peer | Bootstrap of peer | Recv of peer * P.msg | Peers of point list | Contact of point * LU.file_descr | Connected of peer | Shutdown (* A peer handle, as a record-encoded object, abstract from the outside world. A hidden Lwt worker is associated to a peer at its creation and is killed using the disconnect callback by net workers (on shutdown of during maintenance). *) and peer = { gid : gid ; public_key : Crypto_box.public_key ; point : point ; listening_port : port option ; version : version ; last_seen : unit -> float ; disconnect : unit -> unit Lwt.t; send : msg -> unit Lwt.t ; } type peer_info = { gid : gid ; addr : addr ; port : port ; version : version ; } (* A net handler, as a record-encoded object, abstract from the outside world. Hidden Lwt workers are associated to a net at its creation and can be killed using the shutdown callback. *) type net = { recv_from : unit -> (peer * P.msg) Lwt.t ; send_to : peer -> P.msg -> unit Lwt.t ; try_send : peer -> P.msg -> bool ; broadcast : P.msg -> unit ; blacklist : ?duration:float -> addr -> unit ; whitelist : peer -> unit ; maintain : unit -> unit Lwt.t ; roll : unit -> unit Lwt.t ; shutdown : unit -> unit Lwt.t ; peers : unit -> peer list ; find_peer : gid -> peer option ; peer_info : peer -> peer_info ; set_metadata : gid -> P.metadata -> unit ; get_metadata : gid -> P.metadata option ; } (* Run-time point-or-gid indexed storage, one point is bound to at most one gid, which is the invariant we want to keep both for the connected peers table and the known peers one *) module GidMap = Map.Make (struct type t = gid let compare = compare end) module GidSet = Set.Make (struct type t = gid let compare = compare end) module PointMap = Map.Make (struct type t = point let compare = compare end) module PointSet = Set.Make (struct type t = point let compare = compare end) module PeerMap : sig type 'a t val empty : 'a t val by_point : point -> 'a t -> 'a val by_gid : gid -> 'a t -> 'a val gid_by_point : point -> 'a t -> gid option val point_by_gid : gid -> 'a t -> point val mem_by_point : point -> 'a t -> bool val mem_by_gid : gid -> 'a t -> bool val remove_by_point : point -> 'a t -> 'a t val remove_by_gid : gid -> 'a t -> 'a t val update : point -> ?gid : gid -> 'a -> 'a t -> 'a t val fold : (point -> gid option -> 'a -> 'b -> 'b) -> 'a t -> 'b -> 'b val iter : (point -> gid option -> 'a -> unit) -> 'a t -> unit val bindings : 'a t -> (point * gid option * 'a) list val cardinal : 'a t -> int end = struct type 'a t = { by_point : (gid option * 'a) PointMap.t ; by_gid : (point * 'a) GidMap.t } let empty = { by_point = PointMap.empty ; by_gid = GidMap.empty } let by_point point { by_point } = let (_, v) = PointMap.find point by_point in v let by_gid gid { by_gid } = let (_, v) = GidMap.find gid by_gid in v let gid_by_point point { by_point } = let (gid, _) = PointMap.find point by_point in gid let point_by_gid gid { by_gid } = let (point, _) = GidMap.find gid by_gid in point let mem_by_point point { by_point } = PointMap.mem point by_point let mem_by_gid gid { by_gid } = GidMap.mem gid by_gid let remove_by_point point ({ by_point ; by_gid } as map) = try let (gid, _) = PointMap.find point by_point in { by_point = PointMap.remove point by_point ; by_gid = match gid with | None -> by_gid | Some gid -> GidMap.remove gid by_gid } with Not_found -> map let remove_by_gid gid ({ by_point ; by_gid } as map) = try let (point, _) = GidMap.find gid by_gid in { by_point = PointMap.remove point by_point ; by_gid = GidMap.remove gid by_gid } with Not_found -> map let update point ?gid v map = let { by_point ; by_gid } = let map = remove_by_point point map in match gid with Some gid -> remove_by_gid gid map | None -> map in { by_point = PointMap.add point (gid, v) by_point ; by_gid = match gid with Some gid -> GidMap.add gid (point, v) by_gid | None -> by_gid } let fold f { by_point } init = PointMap.fold (fun point (gid, v) r -> f point gid v r) by_point init let iter f { by_point } = PointMap.iter (fun point (gid, v) -> f point gid v) by_point let cardinal { by_point } = PointMap.cardinal by_point let bindings map = fold (fun point gid v l -> (point, gid, v) :: l) map [] end (* Builds a peer and launches its associated worker. Takes a push function for communicating with the main worker using events (including the one sent when the connection is alive). Returns a canceler. *) let connect_to_peer config limits my_gid my_public_key my_secret_key my_proof_of_work socket (addr, port) push white_listed = (* a non exception-based cancelation mechanism *) let cancelation, cancel, on_cancel = Lwt_utils.canceler () in (* a cancelable encrypted reception *) let recv ~uncrypt buf = Lwt.pick [ recv_msg ~uncrypt socket buf ; (cancelation () >>= fun () -> Lwt.return Disconnect) ] in (* First step: send and receive credentials, makes no difference whether we're trying to connect to a peer or checking an incoming connection, both parties must first present themselves. *) let rec connect buf = let local_nonce = Crypto_box.random_nonce () in send_msg socket buf (Connect { gid = my_gid ; public_key = my_public_key ; proof_of_work = my_proof_of_work ; message_nonce = local_nonce ; port = config.incoming_port ; versions = P.supported_versions }) >>= fun _ -> Lwt.pick [ ( LU.sleep limits.peer_answer_timeout >>= fun () -> Lwt.return Disconnect ) ; recv_msg socket buf ] >>= function | Connect { gid; port = listening_port; versions ; public_key ; proof_of_work ; message_nonce } -> debug "(%a) connection requested from %a @@ %a:%d" pp_gid my_gid pp_gid gid Ipaddr.pp_hum addr port ; let work_proved = Crypto_box.check_proof_of_work public_key proof_of_work Crypto_box.default_target in if not work_proved then begin debug "connection rejected (invalid proof of work)" ; cancel () end else begin match common_version P.supported_versions versions with | None -> debug "(%a) connection rejected (incompatible versions) from %a:%d" pp_gid my_gid Ipaddr.pp_hum addr port ; cancel () | Some version -> if config.closed_network then match listening_port with | Some port when white_listed (addr, port) -> connected buf local_nonce version gid public_key message_nonce listening_port | Some port -> debug "(%a) connection rejected (out of the closed network) from %a:%d" pp_gid my_gid Ipaddr.pp_hum addr port ; cancel () | None -> debug "(%a) connection rejected (out of the closed network) from %a:unknown" pp_gid my_gid Ipaddr.pp_hum addr ; cancel () else connected buf local_nonce version gid public_key message_nonce listening_port end | Advertise peers -> (* alternatively, one can refuse a connection but reply with some peers, so we accept this info *) debug "(%a) new peers received from %a:%d" pp_gid my_gid Ipaddr.pp_hum addr port ; push (Peers peers) ; cancel () | Disconnect -> debug "(%a) connection rejected (closed by peer or timeout) from %a:%d" pp_gid my_gid Ipaddr.pp_hum addr port ; cancel () | _ -> debug "(%a) connection rejected (bad connection request) from %a:%d" pp_gid my_gid Ipaddr.pp_hum addr port ; cancel () (* Them we can build the net object and launch the worker. *) and connected buf local_nonce version gid public_key nonce listening_port = (* net object state *) let last = ref (Unix.gettimeofday ()) in let local_nonce = ref local_nonce in let remote_nonce = ref nonce in (* net object callbaks *) let last_seen () = !last in let get_nonce nonce = let current_nonce = !nonce in nonce := Crypto_box.increment_nonce !nonce ; current_nonce in let disconnect () = cancel () in let crypt buf = let nonce = get_nonce remote_nonce in Crypto_box.box my_secret_key public_key buf nonce in let send p = send_msg ~crypt socket buf p >>= fun _ -> Lwt.return_unit in (* net object construction *) let peer = { gid ; public_key ; point = (addr, port) ; listening_port ; version ; last_seen ; disconnect ; send } in let uncrypt buf = let nonce = get_nonce local_nonce in match Crypto_box.box_open my_secret_key public_key buf nonce with | None -> debug "(%a) cannot decrypt message (from peer) %a @ %a:%d" pp_gid my_gid pp_gid gid Ipaddr.pp_hum addr port ; None | Some _ as res -> res in (* The packet reception loop. *) let rec receiver () = recv ~uncrypt buf >>= fun packet -> last := Unix.gettimeofday () ; match packet with | Connect _ | Disconnect -> debug "(%a) disconnected (by peer) %a @@ %a:%d" pp_gid my_gid pp_gid gid Ipaddr.pp_hum addr port ; cancel () | Bootstrap -> push (Bootstrap peer) ; receiver () | Advertise peers -> push (Peers peers) ; receiver () | Message msg -> push (Recv (peer, msg)) ; receiver () in (* Events for the main worker *) push (Connected peer) ; on_cancel (fun () -> push (Disconnected peer) ; Lwt.return_unit) ; (* Launch the worker *) receiver () in let buf = MBytes.create maxlen in on_cancel (fun () -> (* send_msg ~crypt socket buf Disconnect >>= fun _ -> *) LU.close socket >>= fun _ -> Lwt.return_unit) ; let worker_name = Format.asprintf "(%a) connection handler for %a:%d" pp_gid my_gid Ipaddr.pp_hum addr port in ignore (Lwt_utils.worker worker_name ~safe:true ~run:(fun () -> connect buf) ~cancel) ; (* return the canceler *) cancel (* JSON format for on-disk peers cache file *) let addr_encoding = let open Data_encoding in splitted ~json: (conv Ipaddr.to_string (Data_encoding.Json.wrap_error Ipaddr.of_string_exn) string) ~binary: (union ~tag_size:`Uint8 [ case ~tag:4 (Fixed.string 4) (fun ip -> Utils.map_option Ipaddr.V4.to_bytes (Ipaddr.to_v4 ip) ) (fun b -> Ipaddr.(V4 (V4.of_bytes_exn b))) ; case ~tag:6 (Fixed.string 32) (fun ip -> Some (Ipaddr.V6.to_bytes (Ipaddr.to_v6 ip))) (fun b -> Ipaddr.(V6 (V6.of_bytes_exn b))) ; ]) let peers_file_encoding = let open Data_encoding in obj5 (req "gid" string) (req "public_key" Crypto_box.public_key_encoding) (req "secret_key" Crypto_box.secret_key_encoding) (req "proof_of_work" Crypto_box.nonce_encoding) (req "peers" (obj3 (req "known" (list (obj3 (req "addr" addr_encoding) (req "port" int31) (opt "infos" (obj4 (req "connections" int31) (req "lastSeen" float) (req "gid" string) (req "public_key" Crypto_box.public_key_encoding)))))) (req "blacklisted" (list (obj2 (req "addr" addr_encoding) (req "until" float)))) (req "whitelisted" (list (obj2 (req "addr" addr_encoding) (req "port" int31)))))) (* Info on peers maintained between connections *) type source = { unreachable_since : float option; connections : (int * float * Crypto_box.public_key) option ; white_listed : bool ; meta : P.metadata ; } (* Ad hoc comparison on sources such as good source < bad source *) let compare_sources s1 s2 = match s1.white_listed, s2.white_listed with | true, false -> -1 | false, true -> 1 | _, _ -> match s1.unreachable_since, s2.unreachable_since with | None, Some _ -> -1 | Some _, None -> 1 | _, _ -> match s1.connections, s2.connections with | Some _, None -> -1 | None, Some _ -> 1 | None, None -> 0 | Some (n1, t1, _), Some (n2, t2, _) -> if n1 = n2 then compare t2 t1 else compare n2 n1 (* A store for blacklisted addresses (we ban any peer on a blacklisted address, which is the policy that seems to make the most sense) *) module BlackList = Map.Make (struct type t = addr let compare = compare end) (* A good random string so it is probably unique on the network *) let fresh_gid () = Bytes.to_string @@ Sodium.Random.Bytes.generate gid_length (* The (fixed size) broadcast frame. *) let discovery_message_encoding = let open Data_encoding in tup3 (Fixed.string 8) (Fixed.string gid_length) int16 let discovery_message gid port = Data_encoding.Binary.to_bytes discovery_message_encoding ("DISCOVER", gid, port) (* Broadcast frame verifier. *) let answerable_discovery_message msg my_gid when_ok when_not = match msg with | Some ("DISCOVER", gid, port) when gid <> my_gid -> when_ok gid port | _ -> when_not () let string_of_unix_exn = function | Unix.Unix_error (err, fn, _) -> "in " ^ fn ^ ", " ^ Unix.error_message err | exn -> Printexc.to_string exn (* Launch an answer machine for the discovery mechanism, takes a callback to fill the answers and returns a canceler function *) let discovery_answerer my_gid disco_port cancelation callback = (* init a UDP listening socket on the broadcast canal *) Lwt.catch begin fun () -> let main_socket = LU.(socket PF_INET SOCK_DGRAM 0) in LU.(setsockopt main_socket SO_BROADCAST true) ; LU.(setsockopt main_socket SO_REUSEADDR true) ; LU.(bind main_socket (ADDR_INET (Unix.inet_addr_any, disco_port))) ; Lwt.return (Some main_socket) end (fun exn -> debug "(%a) will not listen to discovery requests (%s)" pp_gid my_gid (string_of_unix_exn exn) ; Lwt.return_none) >>= function | None -> Lwt.return_unit | Some main_socket -> (* the answering function *) let rec step () = let buffer = discovery_message my_gid 0 in let len = MBytes.length buffer in Lwt.pick [ (cancelation () >>= fun () -> Lwt.return_none) ; (Lwt_bytes.recvfrom main_socket buffer 0 len [] >>= fun r -> Lwt.return (Some r)) ] >>= function | None -> Lwt.return_unit | Some (len', LU.ADDR_INET (addr, _)) when len' = len -> answerable_discovery_message (Data_encoding.Binary.of_bytes discovery_message_encoding buffer) my_gid (fun _ port -> Lwt.catch begin fun () -> let ipaddr = let open Ipaddr in match Ipaddr_unix.of_inet_addr addr with | V4 addr -> V6 (v6_of_v4 addr) | V6 _ as addr -> addr in let addr = Ipaddr_unix.to_inet_addr ipaddr in let socket = LU.(socket PF_INET6 SOCK_STREAM 0) in LU.connect socket LU.(ADDR_INET (addr, port)) >>= fun () -> callback ipaddr port socket >>= fun () -> Lwt.return_unit end (fun _ -> (* ignore errors *) Lwt.return_unit) >>= fun () -> step ()) step | Some _ -> step () in step () (* Sends dicover messages into space in an exponentially delayed loop, restartable using a condition *) let discovery_sender my_gid disco_port inco_port cancelation restart = let msg = discovery_message my_gid inco_port in let rec loop delay n = Lwt.catch begin fun () -> let socket = LU.(socket PF_INET SOCK_DGRAM 0) in LU.setsockopt socket LU.SO_BROADCAST true ; let broadcast_ipv4 = Unix.inet_addr_of_string "255.255.255.255" in LU.connect socket LU.(ADDR_INET (broadcast_ipv4, disco_port)) >>= fun () -> Lwt_utils.write_mbytes socket msg >>= fun _ -> LU.close socket end (fun _ -> debug "(%a) error broadcasting a discovery request" pp_gid my_gid ; Lwt.return_unit) >>= fun () -> Lwt.pick [ (LU.sleep delay >>= fun () -> Lwt.return (Some (delay, n + 1))) ; (cancelation () >>= fun () -> Lwt.return_none) ; (LC.wait restart >>= fun () -> Lwt.return (Some (0.1, 0))) ] >>= function | Some (delay, n) when n = 10 -> loop delay 9 | Some (delay, n) -> loop (delay *. 2.) n | None -> Lwt.return_unit in loop 0.2 1 (* Main network creation and initialisation function *) let bootstrap ~config ~limits = (* we need to ignore SIGPIPEs *) Sys.(set_signal sigpipe Signal_ignore) ; (* a non exception-based cancelation mechanism *) let cancelation, cancel, on_cancel = Lwt_utils.canceler () in (* create the internal event queue *) let enqueue_event, dequeue_event = let queue, enqueue = Lwt_stream.create () in (fun msg -> enqueue (Some msg)), (fun () -> Lwt_stream.next queue) in (* create the external message queue *) let enqueue_msg, dequeue_msg, close_msg_queue = let queue, enqueue = Lwt_stream.create () in (fun msg -> enqueue (Some msg)), (fun () -> Lwt_stream.next queue), (fun () -> enqueue None) in on_cancel (fun () -> close_msg_queue () ; Lwt.return_unit) ; (* fill the known peers pools from last time *) Data_encoding.Json.read_file config.peers_file >>= fun res -> let known_peers, black_list, my_gid, my_public_key, my_secret_key, my_proof_of_work = let init_peers () = let my_gid = fresh_gid () in let (my_secret_key, my_public_key) = Crypto_box.random_keypair () in let my_proof_of_work = Crypto_box.generate_proof_of_work my_public_key Crypto_box.default_target in let known_peers = let source = { unreachable_since = None ; connections = None ; white_listed = true ; meta = P.initial_metadata ; } in List.fold_left (fun r point -> PeerMap.update point source r) PeerMap.empty config.known_peers in let black_list = BlackList.empty in known_peers, black_list, my_gid, my_public_key, my_secret_key, my_proof_of_work in match res with | None -> let known_peers, black_list, my_gid, my_public_key, my_secret_key, my_proof_of_work = init_peers () in debug "(%a) peer cache initiated" pp_gid my_gid ; ref known_peers, ref black_list, my_gid, my_public_key, my_secret_key, my_proof_of_work | Some json -> match Data_encoding.Json.destruct peers_file_encoding json with | exception _ -> let known_peers, black_list, my_gid, my_public_key, my_secret_key, my_proof_of_work = init_peers () in debug "(%a) peer cache reset" pp_gid my_gid ; ref known_peers, ref black_list, my_gid, my_public_key, my_secret_key, my_proof_of_work | (my_gid, my_public_key, my_secret_key, my_proof_of_work, (k, b, w)) -> let white_list = List.fold_right PointSet.add w PointSet.empty in let known_peers = List.fold_left (fun r (addr, port, infos) -> match infos with | None -> let source = { unreachable_since = None ; connections = None ; white_listed = true ; meta = P.initial_metadata ; } in PeerMap.update (addr, port) source r | Some (c, t, gid, pk) -> let source = { unreachable_since = None ; connections = Some (c, t, pk) ; white_listed = PointSet.mem (addr, port) white_list ; meta = P.initial_metadata ; } in PeerMap.update (addr, port) ~gid source r) PeerMap.empty k in let black_list = List.fold_left (fun r (a, d) -> BlackList.add a d r) BlackList.empty b in debug "(%a) peer cache loaded" pp_gid my_gid ; ref known_peers, ref black_list, my_gid, my_public_key, my_secret_key, my_proof_of_work in (* some peer reachability predicates *) let black_listed (addr, _) = BlackList.mem addr !black_list in let white_listed point = try (PeerMap.by_point point !known_peers).white_listed with Not_found -> false in let grey_listed point = try match (PeerMap.by_point point !known_peers).unreachable_since with | None -> false | Some t -> Unix.gettimeofday () -. t > 5. with Not_found -> false in (* save the cache at exit *) on_cancel (fun () -> (* save the known peers cache *) let json = Data_encoding.Json.construct peers_file_encoding @@ (my_gid, my_public_key, my_secret_key, my_proof_of_work, PeerMap.fold (fun (addr, port) gid source (k, b, w) -> let infos = match gid, source.connections with | Some gid, Some (n, t, pk) -> Some (n, t, gid, pk) | _ -> None in ((addr, port, infos) :: k, b, if source.white_listed then (addr, port) :: w else w)) !known_peers ([], BlackList.bindings !black_list, [])) in Data_encoding.Json.write_file config.peers_file json >>= fun _ -> debug "(%a) peer cache saved" pp_gid my_gid ; Lwt.return_unit) ; (* storage of active and not yet active peers *) let incoming = ref PointMap.empty in let connected = ref PeerMap.empty in (* peer welcoming (accept) loop *) let welcome () = match config.incoming_port with | None -> (* no input port => no welcome worker *) Lwt.return_unit | Some port -> (* open port for incoming connexions *) let addr = Unix.inet6_addr_any in Lwt.catch begin fun () -> let main_socket = LU.(socket PF_INET6 SOCK_STREAM 0) in LU.(setsockopt main_socket SO_REUSEADDR true) ; LU.(bind main_socket (ADDR_INET (addr, port))) ; LU.listen main_socket limits.max_connections ; Lwt.return (Some main_socket) end (fun exn -> debug "(%a) cannot accept incoming peers (%s)" pp_gid my_gid (string_of_unix_exn exn) ; Lwt.return_none) >>= function | None -> (* FIXME: run in degraded mode, better exit ? *) Lwt.return_unit | Some main_socket -> (* then loop *) let rec step () = Lwt.pick [ ( LU.accept main_socket >>= fun (s, a) -> Lwt.return (Some (s, a)) ) ; ( cancelation () >>= fun _ -> Lwt.return_none ) ] >>= function | None -> LU.close main_socket | Some (socket, addr) -> match addr with | LU.ADDR_INET (addr, port) -> let addr = Ipaddr_unix.of_inet_addr addr in enqueue_event (Contact ((addr, port), socket)) ; step () | _ -> Lwt.async (fun () -> LU.close socket) ; step () in step () in (* input maintenance events *) let too_many_peers = LC.create () in let too_few_peers = LC.create () in let new_peer = LC.create () in let new_contact = LC.create () in let please_maintain = LC.create () in let restart_discovery = LC.create () in (* output maintenance events *) let just_maintained = LC.create () in (* maintenance worker, returns when [connections] peers are connected *) let rec maintenance () = Lwt.pick [ ( LU.sleep 120. >>= fun () -> Lwt.return_true) ; (* every two minutes *) ( LC.wait please_maintain >>= fun () -> Lwt.return_true) ; (* when asked *) ( LC.wait too_few_peers >>= fun () -> Lwt.return_true) ; (* limits *) ( LC.wait too_many_peers >>= fun () -> Lwt.return_true) ; ( cancelation () >>= fun () -> Lwt.return_false) ] >>= fun continue -> let rec maintain () = let n_connected = PeerMap.cardinal !connected in if n_connected >= limits.expected_connections && n_connected <= limits.max_connections then (* end of maintenance when enough users have been reached *) (LC.broadcast just_maintained () ; debug "(%a) maintenance step ended" pp_gid my_gid ; maintenance ()) else if n_connected < limits.expected_connections then (* too few peers, try and contact many peers *) let contact nb = let contactable = (* we sort sources by level (prefered first) *) PeerMap.bindings !known_peers |> List.sort (fun (_, _, s1) (_, _, s2) -> compare_sources s1 s2) |> (* remove the ones we're connect(ed/ing) to and the blacklisted *) List.filter (fun (point, gid, source) -> (not (black_listed point) || source.white_listed) && not (grey_listed point) && not (gid = Some my_gid) && not (PeerMap.mem_by_point point !connected) && not (PointMap.mem point !incoming) && match gid with | None -> true | Some gid -> not (PeerMap.mem_by_gid gid !connected)) in let rec do_contact_loop strec = match strec with | 0, _ -> Lwt.return_true | _, [] -> Lwt.return_false (* we didn't manage to contact enough peers *) | nb, ((addr, port), gid, source) :: tl -> (* we try to open a connection *) let socket = let open LU in let open Ipaddr in let family = match addr with V4 _ -> PF_INET | V6 _ -> PF_INET6 in socket family SOCK_STREAM 0 in let uaddr = Ipaddr_unix.to_inet_addr addr in Lwt.catch begin fun () -> debug "(%a) trying to connect to %a:%d" pp_gid my_gid Ipaddr.pp_hum addr port ; Lwt.pick [ (Lwt_unix.sleep 2.0 >>= fun _ -> Lwt.fail Not_found) ; LU.connect socket (LU.ADDR_INET (uaddr, port)) ] >>= fun () -> debug "(%a) connected to %a:%d" pp_gid my_gid Ipaddr.pp_hum addr port; enqueue_event (Contact ((addr, port), socket)) ; Lwt.return (nb - 1) end (fun exn -> debug "(%a) connection failed to %a:%d (%s)" pp_gid my_gid Ipaddr.pp_hum addr port (string_of_unix_exn exn); (* if we didn't succes, we greylist it *) let now = Unix.gettimeofday () in known_peers := PeerMap.update (addr, port) ?gid { source with unreachable_since = Some now } !known_peers ; LU.close socket >>= fun () -> Lwt.return nb) >>= fun nrec -> do_contact_loop (nrec, tl) in do_contact_loop (nb, contactable) in let to_contact = limits.max_connections - n_connected in debug "(%a) too few connections (%d)" pp_gid my_gid n_connected ; contact to_contact >>= function | true -> (* enough contacts, now wait for connections *) Lwt.pick [ (LC.wait new_peer >>= fun _ -> Lwt.return_true) ; (LU.sleep 1.0 >>= fun () -> Lwt.return_true) ; (cancelation () >>= fun () -> Lwt.return_false) ] >>= fun continue -> if continue then maintain () else Lwt.return_unit | false -> (* not enough contacts, ask the pals of our pals, discover the local network and then wait *) LC.broadcast restart_discovery () ; (PeerMap.iter (fun _ _ peer -> Lwt.async (fun () -> peer.send Bootstrap)) !connected ; Lwt.pick [ (LC.wait new_peer >>= fun _ -> Lwt.return_true) ; (LC.wait new_contact >>= fun _ -> Lwt.return_true) ; (LU.sleep 1.0 >>= fun () -> Lwt.return_true) ; (cancelation () >>= fun () -> Lwt.return_false) ] >>= fun continue -> if continue then maintain () else Lwt.return_unit) else (* too many peers, start the russian roulette *) let to_kill = n_connected - limits.max_connections in debug "(%a) too many connections, will kill %d" pp_gid my_gid to_kill ; snd (PeerMap.fold (fun _ _ peer (i, t) -> if i = 0 then (0, t) else (i - 1, t >>= fun () -> peer.disconnect ())) !connected (to_kill, Lwt.return_unit)) >>= fun () -> (* and directly skip to the next maintenance request *) LC.broadcast just_maintained () ; debug "(%a) maintenance step ended" pp_gid my_gid ; maintenance () in if continue then maintain () else Lwt.return_unit in (* select the peers to send on a bootstrap request *) let bootstrap_peers () = (* we sort peers by desirability *) PeerMap.bindings !known_peers |> List.filter (fun ((ip,_),_,_) -> not (Ipaddr.is_private ip)) |> List.sort (fun (_, _, s1) (_, _, s2) -> compare_sources s1 s2) |> (* we simply send the first 50 (or less) known peers *) List.fold_left (fun (n, l) (point, _, _) -> if n = 0 then (n, l) else (n - 1, point :: l)) (50, []) |> snd in (* main internal event handling worker *) let rec main () = Lwt.pick [ dequeue_event () ; cancelation () >>= fun () -> Lwt.return Shutdown ] >>= fun event -> match event with | Disconnected peer -> debug "(%a) disconnected peer %a" pp_gid my_gid pp_gid peer.gid ; (* remove it from the tables *) connected := PeerMap.remove_by_point peer.point !connected ; if PeerMap.cardinal !connected < limits.min_connections then LC.broadcast too_few_peers () ; incoming := PointMap.remove peer.point !incoming ; main () | Connected peer -> incoming := PointMap.remove peer.point !incoming ; let update_infos () = (* we update our knowledge table according to the reachable address given by the peer *) match peer.listening_port with | None -> () | Some port -> let point = (fst peer.point, port) in let update source = (* delete previous infos about this address / gid *) known_peers := PeerMap.remove_by_point point !known_peers ; known_peers := PeerMap.remove_by_gid peer.gid !known_peers ; (* then assign *) known_peers := PeerMap.update point ~gid:peer.gid source !known_peers in update @@ try match PeerMap.by_gid peer.gid !known_peers with | { connections = None ; white_listed } -> { connections = Some (1, Unix.gettimeofday (), peer.public_key) ; unreachable_since = None ; white_listed ; meta = P.initial_metadata } | { connections = Some (n, _, _) ; white_listed } -> { connections = Some (n + 1, Unix.gettimeofday (), peer.public_key) ; unreachable_since = None ; white_listed ; meta = P.initial_metadata } with Not_found -> { connections = Some (1, Unix.gettimeofday (), peer.public_key) ; unreachable_since = None ; white_listed = white_listed point ; meta = P.initial_metadata } in (* if it's me, it's probably not me *) if my_gid = peer.gid then begin debug "(%a) rejected myself from %a:%d" pp_gid my_gid Ipaddr.pp_hum (fst peer.point) (snd peer.point) ; (* now that I know my address, I can save this info to prevent future reconnections to myself *) update_infos () ; Lwt.async peer.disconnect end (* keep only one connection to each node by checking its gid *) else if PeerMap.mem_by_gid peer.gid !connected then begin debug "(%a) rejected already connected peer %a @@ %a:%d" pp_gid my_gid pp_gid peer.gid Ipaddr.pp_hum (fst peer.point) (snd peer.point) ; update_infos () ; Lwt.async peer.disconnect end else begin debug "(%a) connected peer %a @@ %a:%d" pp_gid my_gid pp_gid peer.gid Ipaddr.pp_hum (fst peer.point) (snd peer.point) ; update_infos () ; connected := PeerMap.update peer.point ~gid:peer.gid peer !connected ; if PeerMap.cardinal !connected > limits.max_connections then LC.broadcast too_many_peers () ; LC.broadcast new_peer peer end ; main () | Contact ((addr, port), socket) -> (* we do not check the credentials at this stage, since they could change from one connection to the next *) if PointMap.mem (addr, port) !incoming || PeerMap.mem_by_point (addr, port) !connected || BlackList.mem addr !black_list then LU.close socket >>= fun () -> main () else let canceler = connect_to_peer config limits my_gid my_public_key my_secret_key my_proof_of_work socket (addr, port) enqueue_event white_listed in debug "(%a) incoming peer @@ %a:%d" pp_gid my_gid Ipaddr.pp_hum addr port ; incoming := PointMap.add (addr, port) canceler !incoming ; main () | Bootstrap peer -> let sample = bootstrap_peers () in Lwt.async (fun () -> peer.send (Advertise sample)) ; main () | Recv (peer, msg) -> enqueue_msg (peer, msg) ; main () | Peers peers -> List.iter (fun point -> if not (PeerMap.mem_by_point point !known_peers) then let source = { unreachable_since = None ; connections = None ; white_listed = false ; meta = P.initial_metadata } in known_peers := PeerMap.update point source !known_peers ; LC.broadcast new_contact point) peers ; main () | Shutdown -> Lwt.return_unit in (* blacklist filter *) let rec unblock () = Lwt.pick [ (Lwt_unix.sleep 20. >>= fun _ -> Lwt.return_true) ; (cancelation () >>= fun () -> Lwt.return_false) ] >>= fun continue -> if continue then let now = Unix.gettimeofday () in black_list := BlackList.fold (fun addr d map -> if d < now then map else BlackList.add addr d map) !black_list BlackList.empty ; known_peers := PeerMap.fold (fun point gid source map -> let source = match source.unreachable_since with | Some t when now -. t < 20. -> source | _ -> { source with unreachable_since = None } in PeerMap.update point ?gid source map) !known_peers PeerMap.empty ; unblock () else Lwt.return_unit in (* launch all workers *) let welcome = Lwt_utils.worker (Format.asprintf "(%a) welcome" pp_gid my_gid) welcome cancel in let maintenance = Lwt_utils.worker (Format.asprintf "(%a) maintenance" pp_gid my_gid) maintenance cancel in let main = Lwt_utils.worker (Format.asprintf "(%a) reception" pp_gid my_gid) main cancel in let unblock = Lwt_utils.worker (Format.asprintf "(%a) unblacklister" pp_gid my_gid) unblock cancel in let discovery_answerer = let buf = MBytes.create 0x100_000 in match config.discovery_port with | Some disco_port -> let answerer () = discovery_answerer my_gid disco_port cancelation @@ fun addr port socket -> (* do not reply to ourselves or connected peers *) if not (PeerMap.mem_by_point (addr, port) !connected) && (try match PeerMap.gid_by_point (addr, port) !known_peers with | Some gid -> not (PeerMap.mem_by_gid gid !connected) && not (my_gid = gid) | None -> true with Not_found -> true) then (* either reply by a list of peer or connect if we need peers *) if PeerMap.cardinal !connected >= limits.expected_connections then begin enqueue_event (Peers [ addr, port ]) ; send_msg socket buf (Advertise (bootstrap_peers ())) >>= fun _ -> LU.close socket end else begin enqueue_event (Contact ((addr, port), socket)) ; Lwt.return_unit end else LU.close socket in Lwt_utils.worker (Format.asprintf "(%a) discovery answerer" pp_gid my_gid) answerer cancel | _ -> Lwt.return_unit in let discovery_sender = match config.incoming_port, config.discovery_port with | Some inco_port, Some disco_port -> let sender () = discovery_sender my_gid disco_port inco_port cancelation restart_discovery in Lwt_utils.worker (Format.asprintf "(%a) discovery sender" pp_gid my_gid) sender cancel | _ -> Lwt.return_unit in (* net manipulation callbacks *) let rec shutdown () = debug "(%a) starting network shutdown" pp_gid my_gid ; (* stop accepting clients *) cancel () >>= fun () -> (* wait for both workers to end *) Lwt.join [ welcome ; main ; maintenance ; unblock ; discovery_answerer ; discovery_sender ] >>= fun () -> (* properly shutdown all peers *) let cancelers = PeerMap.fold (fun point _ peer res -> (peer.disconnect () >>= fun () -> connected := PeerMap.remove_by_point point !connected ; Lwt.return_unit) :: res) !connected @@ PointMap.fold (fun point canceler res -> (canceler () >>= fun () -> incoming := PointMap.remove point !incoming ; Lwt.return_unit) :: res) !incoming @@ [] in Lwt.join cancelers >>= fun () -> debug "(%a) network shutdown complete" pp_gid my_gid ; Lwt.return_unit and peers () = PeerMap.fold (fun _ _ peer r -> peer :: r) !connected [] and find_peer gid = try Some (PeerMap.by_gid gid !connected) with Not_found -> None and peer_info (peer : peer) = { gid = peer.gid ; addr = fst peer.point ; port = snd peer.point ; version = peer.version ; } and recv_from () = dequeue_msg () and send_to peer msg = peer.send (Message msg) >>= fun _ -> Lwt.return_unit and try_send peer msg = Lwt.async (fun () -> peer.send (Message msg)); true and broadcast msg = PeerMap.iter (fun _ _ peer -> Lwt.async (fun () -> peer.send (Message msg))) !connected and blacklist ?(duration = limits.blacklist_time) addr = let t = Unix.gettimeofday () +. duration in black_list := BlackList.add addr t !black_list ; debug "(%a) address %a blacklisted" pp_gid my_gid Ipaddr.pp_hum addr ; (* we ban this peer, but also all the ones at this address, even when whitelisted (the blacklist operation wins) *) known_peers := PeerMap.fold (fun ((a, _) as point) gid p map -> if a = addr then map else PeerMap.update point ?gid p map) !known_peers PeerMap.empty ; (* we disconnect all peers at this address sur-le-champ *) PeerMap.iter (fun (a, _) _ p -> if addr = a then Lwt.async (fun () -> p.disconnect ())) !connected ; (* and prevent incoming connections *) PointMap.iter (fun (a, _) cancel -> if a = addr then Lwt.async cancel) !incoming and whitelist_point point = let source, gid = try { (PeerMap.by_point point !known_peers) with white_listed = true }, PeerMap.gid_by_point point !known_peers with Not_found -> { unreachable_since = None ; connections = None ; white_listed = true ; meta = P.initial_metadata }, None in known_peers := PeerMap.update point ?gid source !known_peers and whitelist peer = (* we promote this peer to the white list, if reachable *) match peer.listening_port with | Some port -> let point = fst peer.point, port in whitelist_point point | None -> () and maintain () = let waiter = LC.wait just_maintained in LC.broadcast please_maintain () ; waiter and roll () = Pervasives.failwith "roll" and get_metadata _gid = None (* TODO: implement *) and set_metadata _gid _meta = () (* TODO: implement *) in let net = { shutdown ; peers ; find_peer ; recv_from ; send_to ; try_send ; broadcast ; blacklist ; whitelist ; maintain ; roll ; peer_info ; get_metadata ; set_metadata } in (* main thread, returns after first successful maintenance *) maintain () >>= fun () -> debug "(%a) network succesfully bootstrapped" pp_gid my_gid ; Lwt.return net let faked_network = let infinity, wakeup = Lwt.wait () in let shutdown () = Lwt.wakeup_exn wakeup Lwt_stream.Empty; Lwt.return_unit in let peers () = [] in let find_peer _ = None in let recv_from () = infinity in let send_to _ _ = Lwt.return_unit in let try_send _ _ = true in let broadcast _ = () in let blacklist ?duration _ = ignore duration ; () in let whitelist _ = () in let maintain () = Lwt.return_unit in let roll () = Lwt.return_unit in let peer_info _ = assert false in let get_metadata _ = None in let set_metadata _ _ = () in { shutdown ; peers ; find_peer ; recv_from ; send_to ; try_send ; broadcast ; blacklist ; whitelist ; maintain ; roll ; peer_info ; get_metadata ; set_metadata } (* Plug toplevel functions to callback calls. *) let shutdown net = net.shutdown () let peers net = net.peers () let find_peer net gid = net.find_peer gid let peer_info net peer = net.peer_info peer let recv net = net.recv_from () let send net peer msg = net.send_to peer msg let try_send net peer = net.try_send peer let broadcast net msg = net.broadcast msg let maintain net = net.maintain () let roll net = net.roll () let blacklist _net _gid = () let whitelist _net _gid = () let get_metadata net gid = net.get_metadata gid let set_metadata net gid meta = net.set_metadata gid meta end