(**************************************************************************) (* *) (* Copyright (c) 2014 - 2018. *) (* Dynamic Ledger Solutions, Inc. *) (* *) (* All rights reserved. No warranty, explicit or implicit, provided. *) (* *) (**************************************************************************) open Binary_error let raise e = raise (Read_error e) (** Persistent state of the binary reader. *) type state = { stream : Binary_stream.t ; (** All the remaining data to be read. *) remaining_bytes : int option ; (** Total number of bytes that should be from 'stream' (None = illimited). Reading less bytes should raise [Extra_bytes] and trying to read more bytes should raise [Not_enough_data]. *) allowed_bytes : int option ; (** Maximum number of bytes that are allowed to be read from 'stream' before to fail (None = illimited). *) total_read : int ; (** Total number of bytes that has been read from [stream] since the beginning. *) } (** Return type for the function [read_rec]. See [Data_encoding] for its description. *) type 'ret status = | Success of { result : 'ret ; size : int ; stream : Binary_stream.t } | Await of (MBytes.t -> 'ret status) | Error of read_error let check_remaining_bytes state size = match state.remaining_bytes with | Some len when len < size -> raise Not_enough_data | Some len -> Some (len - size) | None -> None let check_allowed_bytes state size = match state.allowed_bytes with | Some len when len < size -> raise Size_limit_exceeded | Some len -> Some (len - size) | None -> None (** [read_atom resume size conv state k] reads [size] bytes from [state], pass it to [conv] to be decoded, and finally call the continuation [k] with the decoded value and the updated state. The function [conv] is also allowed to raise [Read_error err]. In that case the exception is catched and [Error err] is returned. If there is not enough [remaining_bytes] to be read in [state], the function returns [Error Not_enough_data] instead of calling the continuation. If there is not enough [allowed_bytes] to be read in [state], the function returns [Error Size_limit_exceeded] instead of calling the continuation. If there is not enough bytes to be read in [state], the function returns [Await resume] instead of calling the continuation. *) let read_atom resume size conv state k = match let remaining_bytes = check_remaining_bytes state size in let allowed_bytes = check_allowed_bytes state size in let res, stream = Binary_stream.read state.stream size in conv res.buffer res.ofs, { remaining_bytes ; allowed_bytes ; stream ; total_read = state.total_read + size } with | exception (Read_error error) -> Error error | exception Binary_stream.Need_more_data -> Await resume | v -> k v (* tail call *) (** Reader for all the atomic types. *) module Atom = struct let uint8 r = read_atom r Binary_size.uint8 MBytes.get_uint8 let uint16 r = read_atom r Binary_size.int16 MBytes.get_uint16 let int8 r = read_atom r Binary_size.int8 MBytes.get_int8 let int16 r = read_atom r Binary_size.int16 MBytes.get_int16 let int32 r = read_atom r Binary_size.int32 MBytes.get_int32 let int64 r = read_atom r Binary_size.int64 MBytes.get_int64 let float r = read_atom r Binary_size.float MBytes.get_double let bool resume state k = int8 resume state @@ fun (v, state) -> k (v <> 0, state) let uint30 r = read_atom r Binary_size.uint30 @@ fun buffer ofs -> let v = Int32.to_int (MBytes.get_int32 buffer ofs) in if v < 0 then raise (Invalid_int { min = 0 ; v ; max = (1 lsl 30) - 1 }) ; v let int31 r = read_atom r Binary_size.int31 @@ fun buffer ofs -> Int32.to_int (MBytes.get_int32 buffer ofs) let int = function | `Int31 -> int31 | `Int16 -> int16 | `Int8 -> int8 | `Uint30 -> uint30 | `Uint16 -> uint16 | `Uint8 -> uint8 let ranged_int ~minimum ~maximum resume state k = let read_int = match Binary_size.range_to_size ~minimum ~maximum with | `Int8 -> int8 | `Int16 -> int16 | `Int31 -> int31 | `Uint8 -> uint8 | `Uint16 -> uint16 | `Uint30 -> uint30 in read_int resume state @@ fun (ranged, state) -> let ranged = if minimum > 0 then ranged + minimum else ranged in if not (minimum <= ranged && ranged <= maximum) then Error (Invalid_int { min = minimum ; v =ranged ; max = maximum }) else k (ranged, state) let ranged_float ~minimum ~maximum resume state k = float resume state @@ fun (ranged, state) -> if not (minimum <= ranged && ranged <= maximum) then Error (Invalid_float { min = minimum ; v = ranged ; max = maximum }) else k (ranged, state) let rec read_z res value bit_in_value state k = let resume buffer = let stream = Binary_stream.push buffer state.stream in read_z res value bit_in_value { state with stream } k in uint8 resume state @@ fun (byte, state) -> let value = value lor ((byte land 0x7F) lsl bit_in_value) in let bit_in_value = bit_in_value + 7 in let bit_in_value, value = if bit_in_value < 8 then (bit_in_value, value) else begin Buffer.add_char res (Char.unsafe_chr (value land 0xFF)) ; bit_in_value - 8, value lsr 8 end in if byte land 0x80 = 0x80 then read_z res value bit_in_value state k else begin if bit_in_value > 0 then Buffer.add_char res (Char.unsafe_chr value) ; if byte = 0x00 then raise Trailing_zero ; k (Z.of_bits (Buffer.contents res), state) end let n resume state k = uint8 resume state @@ fun (first, state) -> let first_value = first land 0x7F in if first land 0x80 = 0x80 then read_z (Buffer.create 100) first_value 7 state k else k (Z.of_int first_value, state) let z resume state k = uint8 resume state @@ fun (first, state) -> let first_value = first land 0x3F in let sign = (first land 0x40) <> 0 in if first land 0x80 = 0x80 then read_z (Buffer.create 100) first_value 6 state @@ fun (n, state) -> k ((if sign then Z.neg n else n), state) else let n = Z.of_int first_value in k ((if sign then Z.neg n else n), state) let string_enum arr resume state k = let read_index = match Binary_size.enum_size arr with | `Uint8 -> uint8 | `Uint16 -> uint16 | `Uint30 -> uint30 in read_index resume state @@ fun (index, state) -> if index >= Array.length arr then Error No_case_matched else k (arr.(index), state) let fixed_length_bytes length r = read_atom r length @@ fun buf ofs -> MBytes.sub buf ofs length let fixed_length_string length r = read_atom r length @@ fun buf ofs -> MBytes.sub_string buf ofs length let tag = function | `Uint8 -> uint8 | `Uint16 -> uint16 end (** Main recursive reading function, in continuation passing style. *) let rec read_rec : type next ret. next Encoding.t -> state -> ((next * state) -> ret status) -> ret status = fun e state k -> let resume buffer = let stream = Binary_stream.push buffer state.stream in try read_rec e { state with stream }k with Read_error err -> Error err in let open Encoding in assert (Encoding.classify e <> `Variable || state.remaining_bytes <> None) ; match e.encoding with | Null -> k ((), state) | Empty -> k ((), state) | Constant _ -> k ((), state) | Ignore -> k ((), state) | Bool -> Atom.bool resume state k | Int8 -> Atom.int8 resume state k | Uint8 -> Atom.uint8 resume state k | Int16 -> Atom.int16 resume state k | Uint16 -> Atom.uint16 resume state k | Int31 -> Atom.int31 resume state k | Int32 -> Atom.int32 resume state k | Int64 -> Atom.int64 resume state k | N -> Atom.n resume state k | Z -> Atom.z resume state k | Float -> Atom.float resume state k | Bytes (`Fixed n) -> Atom.fixed_length_bytes n resume state k | Bytes `Variable -> let size = remaining_bytes state in Atom.fixed_length_bytes size resume state k | String (`Fixed n) -> Atom.fixed_length_string n resume state k | String `Variable -> let size = remaining_bytes state in Atom.fixed_length_string size resume state k | RangedInt { minimum ; maximum } -> Atom.ranged_int ~minimum ~maximum resume state k | RangedFloat { minimum ; maximum } -> Atom.ranged_float ~minimum ~maximum resume state k | String_enum (_, arr) -> Atom.string_enum arr resume state k | Array e -> read_list e state @@ fun (l, state) -> k (Array.of_list l, state) | List e -> read_list e state k | (Obj (Req { encoding = e })) -> read_rec e state k | (Obj (Dft { encoding = e })) -> read_rec e state k | (Obj (Opt { kind = `Dynamic ; encoding = e })) -> Atom.bool resume state @@ fun (present, state) -> if not present then k (None, state) else read_rec e state @@ fun (v, state) -> k (Some v, state) | (Obj (Opt { kind = `Variable ; encoding = e })) -> let size = remaining_bytes state in if size = 0 then k (None, state) else read_rec e state @@ fun (v, state) -> k (Some v, state) | Objs (`Fixed sz, e1, e2) -> ignore (check_remaining_bytes state sz : int option) ; ignore (check_allowed_bytes state sz : int option) ; read_rec e1 state @@ fun (left, state) -> read_rec e2 state @@ fun (right, state) -> k ((left, right), state) | Objs (`Dynamic, e1, e2) -> read_rec e1 state @@ fun (left, state) -> read_rec e2 state @@ fun (right, state) -> k ((left, right), state) | (Objs (`Variable, e1, e2)) -> read_variable_pair e1 e2 state k | Tup e -> read_rec e state k | Tups (`Fixed sz, e1, e2) -> ignore (check_remaining_bytes state sz : int option) ; ignore (check_allowed_bytes state sz : int option) ; read_rec e1 state @@ fun (left, state) -> read_rec e2 state @@ fun (right, state) -> k ((left, right), state) | Tups (`Dynamic, e1, e2) -> read_rec e1 state @@ fun (left, state) -> read_rec e2 state @@ fun (right, state) -> k ((left, right), state) | (Tups (`Variable, e1, e2)) -> read_variable_pair e1 e2 state k | Conv { inj ; encoding } -> read_rec encoding state @@ fun (v, state) -> k (inj v, state) | Union (_, sz, cases) -> begin Atom.tag sz resume state @@ fun (ctag, state) -> match List.find (function | Case { tag = Tag tag } -> tag = ctag | Case { tag = Json_only } -> false) cases with | exception Not_found -> Error (Unexpected_tag ctag) | Case { encoding ; inj } -> read_rec encoding state @@ fun (v, state) -> k (inj v, state) end | Dynamic_size { kind ; encoding = e } -> Atom.int kind resume state @@ fun (sz, state) -> let remaining = check_remaining_bytes state sz in let state = { state with remaining_bytes = Some sz } in ignore (check_allowed_bytes state sz : int option) ; read_rec e state @@ fun (v, state) -> if state.remaining_bytes <> Some 0 then Error Extra_bytes else k (v, { state with remaining_bytes = remaining }) | Check_size { limit ; encoding = e } -> let old_allowed_bytes = state.allowed_bytes in let limit = match state.allowed_bytes with | None -> limit | Some current_limit -> min current_limit limit in let state = { state with allowed_bytes = Some limit } in read_rec e state @@ fun (v, state) -> let allowed_bytes = match old_allowed_bytes with | None -> None | Some old_limit -> let remaining = match state.allowed_bytes with | None -> assert false | Some remaining -> remaining in let read = limit - remaining in Some (old_limit - read) in k (v, { state with allowed_bytes }) | Describe { encoding = e } -> read_rec e state k | Def { encoding = e } -> read_rec e state k | Splitted { encoding = e } -> read_rec e state k | Mu (_, _, self) -> read_rec (self e) state k | Delayed f -> read_rec (f ()) state k and remaining_bytes { remaining_bytes } = match remaining_bytes with | None -> (* This function should only be called with a variable encoding, for which the `remaining_bytes` should never be `None`. *) assert false | Some len -> len and read_variable_pair : type left right ret. left Encoding.t -> right Encoding.t -> state -> (((left * right) * state) -> ret status) -> ret status = fun e1 e2 state k -> let size = remaining_bytes state in match Encoding.classify e1, Encoding.classify e2 with | (`Dynamic | `Fixed _), `Variable -> read_rec e1 state @@ fun (left, state) -> read_rec e2 state @@ fun (right, state) -> k ((left, right), state) | `Variable, `Fixed n -> if n > size then Error Not_enough_data else let state = { state with remaining_bytes = Some (size - n) } in read_rec e1 state @@ fun (left, state) -> assert (state.remaining_bytes = Some 0) ; let state = { state with remaining_bytes = Some n } in read_rec e2 state @@ fun (right, state) -> assert (state.remaining_bytes = Some 0) ; k ((left, right), state) | _ -> assert false (* Should be rejected by [Encoding.Kind.combine] *) and read_list : type a ret. a Encoding.t -> state -> ((a list * state) -> ret status) -> ret status = fun e state k -> let rec loop state acc = let size = remaining_bytes state in if size = 0 then k (List.rev acc, state) else read_rec e state @@ fun (v, state) -> loop state (v :: acc) in loop state [] let read_rec e state k = try read_rec e state k with Read_error err -> Error err (** ******************** *) (** Various entry points *) let success (v, state) = Success { result = v ; size = state.total_read ; stream = state.stream } let read_stream ?(init = Binary_stream.empty) encoding = match Encoding.classify encoding with | `Variable -> invalid_arg "Data_encoding.Binary.read_stream: variable encoding" | `Dynamic | `Fixed _ -> (* No hardcoded read limit in a stream. *) let state = { remaining_bytes = None ; allowed_bytes = None ; stream = init ; total_read = 0 } in read_rec encoding state success