ligo/src/lib_crypto/chain_id.ml

(**************************************************************************)
(*                                                                        *)
(*    Copyright (c) 2014 - 2018.                                          *)
(*    Dynamic Ledger Solutions, Inc. <contact@tezos.com>                  *)
(*                                                                        *)
(*    All rights reserved. No warranty, explicit or implicit, provided.   *)
(*                                                                        *)
(**************************************************************************)

open Error_monad

type t = string

let name = "Chain_id"
let title = "Network identifier"

let extract bh =
  MBytes.substring (Block_hash.to_bytes bh) 0 4
let hash_bytes ?key l = extract (Block_hash.hash_bytes ?key l)
let hash_string ?key l = extract (Block_hash.hash_string ?key l)

let size = 4

let compare = String.compare
let equal = String.equal

let of_string s =
  if String.length s <> size then None else Some s
let of_string_exn s =
  match of_string s with
  | None ->
      let msg =
        Printf.sprintf "%s.of_string: wrong string size (%d)"
          name (String.length s) in
      raise (Invalid_argument msg)
  | Some h -> h

let to_string s = s
let of_hex s = of_string (Hex.to_string (`Hex s))
let of_hex_exn s = of_string_exn (Hex.to_string (`Hex s))
let to_hex s =
  let `Hex s = Hex.of_string (to_string s) in
  s


let of_bytes_opt b =
  if MBytes.length b <> size then
    None
  else
    Some (MBytes.to_string b)
let of_bytes_exn b =
  match of_bytes_opt b with
  | None ->
      let msg =
        Printf.sprintf "%s.of_bytes: wrong string size (%d)"
          name (MBytes.length b) in
      raise (Invalid_argument msg)
  | Some h -> h
let of_bytes s =
  match of_bytes_opt s with
  | Some x -> Ok x
  | None ->
      generic_error "Failed to deserialize a hash (%s)" name
let to_bytes = MBytes.of_string

let read src off = of_bytes_exn @@ MBytes.sub src off size
let write dst off h = MBytes.blit (to_bytes h) 0 dst off size

let path_length = 1
let to_path key l = to_hex key :: l
let of_path path =
  let path = String.concat "" path in
  of_hex path
let of_path_exn path =
  let path = String.concat "" path in
  of_hex_exn path

let prefix_path p =
  let `Hex p = Hex.of_string p in
  [ p ]

let zero =
  match of_hex (String.make (size * 2) '0') with
  | Some c -> c
  | None -> assert false

type Base58.data += Hash of t

let b58check_encoding =
  Base58.register_encoding
    ~prefix: Base58.Prefix.chain_id
    ~length: size
    ~wrap: (fun s -> Hash s)
    ~of_raw:of_string ~to_raw: (fun h -> h)

let raw_encoding =
  let open Data_encoding in
  conv to_bytes of_bytes_exn (Fixed.bytes size)

let hash h =
  Int32.to_int (MBytes.get_int32 (to_bytes h) 0)

let of_block_hash bh = hash_bytes [Block_hash.to_bytes bh]

include Hash.Make(struct
    type nonrec t = t
    let title = title
    let name = name
    let b58check_encoding = b58check_encoding
    let raw_encoding = raw_encoding
    let compare = compare
    let equal = equal
    let hash = hash
  end)