Source file sc_rollup_inbox_repr.ml
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(**
A Merkelized inbox represents a list of available messages. This
list is decomposed into sublist of messages, one for each Tezos
level greater than the level of the Last Cemented Commitment
(LCC).
This module is designed to:
1. give a constant-time access to the number of available messages ;
2. provide a space-efficient representation for proofs of inbox
inclusions (only for inboxes obtained at the end of block
validation) ;
3. offer an efficient function to add a new batch of messages in
the inbox at the current level.
To solve (1), we simply maintain the number of available messages
in a field.
To solve (2), we use a proof tree H which is implemented by a merkelized
skip list allowing for compact inclusion proofs
(See {!skip_list_repr.ml}).
To solve (3), we maintain a separate proof tree C witnessing the
contents of messages of the current level.
The protocol maintains the number of available messages, the
hashes of the head of H, and the root hash of C.
The rollup node needs to maintain a full representation for C and a
partial representation for H back to the level of the LCC.
*)
type error += Invalid_level_add_messages of Raw_level_repr.t
type error += Invalid_number_of_messages_to_consume of int64
let () =
let open Data_encoding in
register_error_kind
`Permanent
~id:"sc_rollup_inbox.invalid_level_add_messages"
~title:"Internal error: Trying to add a message to an inbox from the past"
~description:
"An inbox can only accept messages for its current level or for the next \
levels."
(obj1 (req "level" Raw_level_repr.encoding))
(function Invalid_level_add_messages level -> Some level | _ -> None)
(fun level -> Invalid_level_add_messages level) ;
register_error_kind
`Permanent
~id:"sc_rollup_inbox.consume_n_messages"
~title:"Internal error: Trying to consume a negative number of messages"
~description:
"Sc_rollup_inbox.consume_n_messages must be called with a non negative \
integer."
(obj1 (req "consume_n_messages" int64))
(function Invalid_number_of_messages_to_consume n -> Some n | _ -> None)
(fun n -> Invalid_number_of_messages_to_consume n)
let hash_prefix = "\003\250\174\238\208"
module Hash = struct
let prefix = "scib1"
let encoded_size = 55
module H =
Blake2B.Make
(Base58)
(struct
let name = "inbox_hash"
let title = "The hash of an inbox of a smart contract rollup"
let b58check_prefix = hash_prefix
let size = None
end)
include H
let () = Base58.check_encoded_prefix b58check_encoding prefix encoded_size
let of_context_hash context_hash =
hash_bytes [Context_hash.to_bytes context_hash]
include Path_encoding.Make_hex (H)
end
module Skip_list_parameters = struct
let basis = 2
end
module Skip_list = Skip_list_repr.Make (Skip_list_parameters)
type proof_hash = Hash.t
type history_proof_hash = Hash.t
type history_proof = (proof_hash, history_proof_hash) Skip_list.cell
let equal_history_proof = Skip_list.equal Hash.equal Hash.equal
let history_proof_encoding : history_proof Data_encoding.t =
Skip_list.encoding Hash.encoding Hash.encoding
let pp_history_proof fmt cell =
Format.fprintf
fmt
{|
content = %a
index = %d
back_pointers = %a
|}
Hash.pp
(Skip_list.content cell)
(Skip_list.index cell)
(Format.pp_print_list Hash.pp)
(Skip_list.back_pointers cell)
module V1 = struct
type t = {
rollup : Sc_rollup_repr.t;
level : Raw_level_repr.t;
nb_available_messages : int64;
nb_messages_in_commitment_period : int64;
starting_level_of_current_commitment_period : Raw_level_repr.t;
message_counter : Z.t;
current_messages_hash : unit -> Hash.t;
old_levels_messages : history_proof;
}
let equal inbox1 inbox2 =
let {
rollup;
level;
nb_available_messages;
nb_messages_in_commitment_period;
starting_level_of_current_commitment_period;
message_counter;
current_messages_hash;
old_levels_messages;
} =
inbox1
in
Sc_rollup_repr.Address.equal rollup inbox2.rollup
&& Raw_level_repr.equal level inbox2.level
&& Compare.Int64.(equal nb_available_messages inbox2.nb_available_messages)
&& Compare.Int64.(
equal
nb_messages_in_commitment_period
inbox2.nb_messages_in_commitment_period)
&& Raw_level_repr.(
equal
starting_level_of_current_commitment_period
inbox2.starting_level_of_current_commitment_period)
&& Z.equal message_counter inbox2.message_counter
&& Hash.equal (current_messages_hash ()) (inbox2.current_messages_hash ())
&& equal_history_proof old_levels_messages inbox2.old_levels_messages
let pp fmt
{
rollup;
level;
nb_available_messages;
nb_messages_in_commitment_period;
starting_level_of_current_commitment_period;
message_counter;
current_messages_hash;
old_levels_messages;
} =
Format.fprintf
fmt
{|
rollup = %a
level = %a
current messages hash = %a
nb_available_messages = %Ld
nb_messages_in_commitment_period = %s
starting_level_of_current_commitment_period = %a
message_counter = %a
old_levels_messages = %a
|}
Sc_rollup_repr.Address.pp
rollup
Raw_level_repr.pp
level
Hash.pp
(current_messages_hash ())
nb_available_messages
(Int64.to_string nb_messages_in_commitment_period)
Raw_level_repr.pp
starting_level_of_current_commitment_period
Z.pp_print
message_counter
pp_history_proof
old_levels_messages
let inbox_level inbox = inbox.level
let old_levels_messages_encoding =
Skip_list.encoding Hash.encoding Hash.encoding
let encoding =
Data_encoding.(
conv
(fun {
rollup;
message_counter;
nb_available_messages;
nb_messages_in_commitment_period;
starting_level_of_current_commitment_period;
level;
current_messages_hash;
old_levels_messages;
} ->
( rollup,
message_counter,
nb_available_messages,
nb_messages_in_commitment_period,
starting_level_of_current_commitment_period,
level,
current_messages_hash (),
old_levels_messages ))
(fun ( rollup,
message_counter,
nb_available_messages,
nb_messages_in_commitment_period,
starting_level_of_current_commitment_period,
level,
current_messages_hash,
old_levels_messages ) ->
{
rollup;
message_counter;
nb_available_messages;
nb_messages_in_commitment_period;
starting_level_of_current_commitment_period;
level;
current_messages_hash = (fun () -> current_messages_hash);
old_levels_messages;
})
(obj8
(req "rollup" Sc_rollup_repr.encoding)
(req "message_counter" n)
(req "nb_available_messages" int64)
(req "nb_messages_in_commitment_period" int64)
(req
"starting_level_of_current_commitment_period"
Raw_level_repr.encoding)
(req "level" Raw_level_repr.encoding)
(req "current_messages_hash" Hash.encoding)
(req "old_levels_messages" old_levels_messages_encoding)))
let number_of_available_messages inbox =
Z.of_int64 inbox.nb_available_messages
let number_of_messages_during_commitment_period inbox =
inbox.nb_messages_in_commitment_period
let start_new_commitment_period inbox level =
{
inbox with
starting_level_of_current_commitment_period = level;
nb_messages_in_commitment_period = 0L;
}
let starting_level_of_current_commitment_period inbox =
inbox.starting_level_of_current_commitment_period
let no_messages_hash = Hash.hash_bytes [Bytes.empty]
let empty rollup level =
{
rollup;
level;
message_counter = Z.zero;
nb_available_messages = 0L;
nb_messages_in_commitment_period = 0L;
starting_level_of_current_commitment_period = level;
current_messages_hash = (fun () -> no_messages_hash);
old_levels_messages = Skip_list.genesis no_messages_hash;
}
let consume_n_messages n ({nb_available_messages; _} as inbox) :
t option tzresult =
let n = Int64.of_int32 n in
if Compare.Int64.(n < 0L) then
error (Invalid_number_of_messages_to_consume n)
else if Compare.Int64.(n > nb_available_messages) then ok None
else
let nb_available_messages = Int64.(sub nb_available_messages n) in
ok (Some {inbox with nb_available_messages})
end
type versioned = V1 of V1.t
let versioned_encoding =
let open Data_encoding in
union
[
case
~title:"V1"
(Tag 0)
V1.encoding
(function V1 inbox -> Some inbox)
(fun inbox -> V1 inbox);
]
include V1
let of_versioned = function V1 inbox -> inbox [@@inline]
let to_versioned inbox = V1 inbox [@@inline]
let key_of_message = Data_encoding.Binary.to_string_exn Data_encoding.z
module type MerkelizedOperations = sig
type tree
type messages = tree
type message = tree
type history
val history_encoding : history Data_encoding.t
val pp_history : Format.formatter -> history -> unit
val history_at_genesis : bound:int64 -> history
val add_external_messages :
history ->
t ->
Raw_level_repr.t ->
string list ->
messages ->
(messages * history * t) tzresult Lwt.t
val add_messages_no_history :
t ->
Raw_level_repr.t ->
Sc_rollup_inbox_message_repr.serialized list ->
messages ->
(messages * t) tzresult Lwt.t
val get_message : messages -> Z.t -> message option Lwt.t
val get_message_payload : messages -> Z.t -> string option Lwt.t
type inclusion_proof
val inclusion_proof_encoding : inclusion_proof Data_encoding.t
val pp_inclusion_proof : Format.formatter -> inclusion_proof -> unit
val number_of_proof_steps : inclusion_proof -> int
val produce_inclusion_proof : history -> t -> t -> inclusion_proof option
val verify_inclusion_proof : inclusion_proof -> t -> t -> bool
end
module type TREE = sig
type t
type tree
type key = string list
type value = bytes
val find : tree -> key -> value option Lwt.t
val find_tree : tree -> key -> tree option Lwt.t
val add : tree -> key -> value -> tree Lwt.t
val is_empty : tree -> bool
val hash : tree -> Context_hash.t
end
module MakeHashingScheme (Tree : TREE) :
MerkelizedOperations with type tree = Tree.tree = struct
module Tree = Tree
type tree = Tree.tree
type messages = tree
type message = tree
let add_message inbox payload messages =
let open Lwt_tzresult_syntax in
let message_index = inbox.message_counter in
let message_counter = Z.succ message_index in
let key = key_of_message message_index in
let nb_available_messages = Int64.succ inbox.nb_available_messages in
let*! messages =
Tree.add
messages
[key; "payload"]
(Bytes.of_string
(payload : Sc_rollup_inbox_message_repr.serialized :> string))
in
let nb_messages_in_commitment_period =
Int64.succ inbox.nb_messages_in_commitment_period
in
let inbox =
{
inbox with
message_counter;
nb_available_messages;
nb_messages_in_commitment_period;
}
in
return (messages, inbox)
let get_message messages message_index =
let key = key_of_message message_index in
Tree.(find_tree messages [key])
let get_message_payload messages message_index =
let key = key_of_message message_index in
Tree.(find messages [key; "payload"]) >|= Option.map Bytes.to_string
let hash_old_levels_messages cell =
let current_messages_hash = Skip_list.content cell in
let back_pointers_hashes = Skip_list.back_pointers cell in
Hash.to_bytes current_messages_hash
:: List.map Hash.to_bytes back_pointers_hashes
|> Hash.hash_bytes
module Int64_map = Map.Make (Int64)
type history = {
events : history_proof Hash.Map.t;
sequence : Hash.t Int64_map.t;
bound : int64;
counter : int64;
}
let history_encoding : history Data_encoding.t =
let open Data_encoding in
let events_encoding = Hash.Map.encoding history_proof_encoding in
let sequence_encoding =
conv
(fun m -> Int64_map.bindings m)
(List.fold_left (fun m (k, v) -> Int64_map.add k v m) Int64_map.empty)
(list (tup2 int64 Hash.encoding))
in
conv
(fun {events; sequence; bound; counter} ->
(events, sequence, bound, counter))
(fun (events, sequence, bound, counter) ->
{events; sequence; bound; counter})
(obj4
(req "events" events_encoding)
(req "sequence" sequence_encoding)
(req "bound" int64)
(req "counter" int64))
let pp_history fmt history =
Hash.Map.bindings history.events |> fun bindings ->
let pp_binding fmt (hash, history_proof) =
Format.fprintf
fmt
"@[%a -> %a@]"
Hash.pp
hash
pp_history_proof
history_proof
in
Format.pp_print_list pp_binding fmt bindings
let history_at_genesis ~bound =
{events = Hash.Map.empty; sequence = Int64_map.empty; bound; counter = 0L}
type without_history_witness
type with_history_witness
type _ with_history =
| No_history : without_history_witness with_history
| With_history : history -> with_history_witness with_history
(** [remember_history ptr cell history] extends [history] with a new
mapping from [ptr] to [cell]. If [history] is full, the
oldest mapping is removed. If the history bound is less
or equal to zero, then this function returns [history]
untouched. *)
let remember_history ptr cell history =
if Compare.Int64.(history.bound <= 0L) then history
else
let events = Hash.Map.add ptr cell history.events in
let counter = Int64.succ history.counter in
let history =
{
events;
sequence = Int64_map.add history.counter ptr history.sequence;
bound = history.bound;
counter;
}
in
if Int64.(equal history.counter history.bound) then
match Int64_map.min_binding history.sequence with
| None -> history
| Some (l, h) ->
let sequence = Int64_map.remove l history.sequence in
let events = Hash.Map.remove h events in
{
counter = Int64.pred history.counter;
bound = history.bound;
sequence;
events;
}
else history
let remember :
type history_witness.
history_proof_hash ->
history_proof ->
history_witness with_history ->
history_witness with_history =
fun ptr cell history ->
match history with
| No_history -> No_history
| With_history history -> With_history (remember_history ptr cell history)
let archive_if_needed history inbox target_level =
let archive_level history inbox =
let prev_cell = inbox.old_levels_messages in
let prev_cell_ptr = hash_old_levels_messages prev_cell in
let history = remember prev_cell_ptr prev_cell history in
let old_levels_messages =
Skip_list.next
~prev_cell
~prev_cell_ptr
(inbox.current_messages_hash ())
in
let level = Raw_level_repr.succ inbox.level in
let current_messages_hash () = no_messages_hash in
let inbox =
{
rollup = inbox.rollup;
nb_available_messages = inbox.nb_available_messages;
nb_messages_in_commitment_period =
inbox.nb_messages_in_commitment_period;
starting_level_of_current_commitment_period =
inbox.starting_level_of_current_commitment_period;
old_levels_messages;
level;
current_messages_hash;
message_counter = Z.zero;
}
in
(history, inbox)
in
let rec aux (history, inbox) =
if Raw_level_repr.(inbox.level = target_level) then (history, inbox)
else aux (archive_level history inbox)
in
aux (history, inbox)
let hash_messages messages =
if Tree.is_empty messages then no_messages_hash
else Hash.of_context_hash @@ Tree.hash messages
let add_messages_aux history inbox level payloads messages =
let open Lwt_tzresult_syntax in
let* () =
fail_when
Raw_level_repr.(level < inbox.level)
(Invalid_level_add_messages level)
in
let history, inbox = archive_if_needed history inbox level in
let* messages, inbox =
List.fold_left_es
(fun (messages, inbox) payload -> add_message inbox payload messages)
(messages, inbox)
payloads
in
let current_messages_hash () = hash_messages messages in
return (messages, history, {inbox with current_messages_hash})
let add_external_messages history inbox level payloads messages =
let open Lwt_tzresult_syntax in
let*? payloads =
List.map_e
(fun payload ->
Sc_rollup_inbox_message_repr.(to_bytes @@ External payload))
payloads
in
let* messages, With_history history, inbox =
add_messages_aux (With_history history) inbox level payloads messages
in
return (messages, history, inbox)
let add_messages_no_history inbox level payloads messages =
let open Lwt_tzresult_syntax in
let* messages, No_history, inbox =
add_messages_aux No_history inbox level payloads messages
in
return (messages, inbox)
type inclusion_proof = history_proof list
let inclusion_proof_encoding =
let open Data_encoding in
list history_proof_encoding
let pp_inclusion_proof fmt proof =
Format.pp_print_list pp_history_proof fmt proof
let number_of_proof_steps proof = List.length proof
let lift_ptr_path history ptr_path =
let rec aux accu = function
| [] -> Some (List.rev accu)
| x :: xs -> Option.bind (history x) @@ fun c -> aux (c :: accu) xs
in
aux [] ptr_path
let produce_inclusion_proof history inbox1 inbox2 =
let cell_ptr = hash_old_levels_messages inbox2.old_levels_messages in
let target_index = Skip_list.index inbox1.old_levels_messages in
let (With_history history) =
remember cell_ptr inbox2.old_levels_messages (With_history history)
in
let deref ptr = Hash.Map.find_opt ptr history.events in
Skip_list.back_path ~deref ~cell_ptr ~target_index
|> Option.map (lift_ptr_path deref)
|> Option.join
let verify_inclusion_proof proof inbox1 inbox2 =
let assoc = List.map (fun c -> (hash_old_levels_messages c, c)) proof in
let path = List.split assoc |> fst in
let deref =
let open Hash.Map in
let map = of_seq (List.to_seq assoc) in
fun ptr -> find_opt ptr map
in
let cell_ptr = hash_old_levels_messages inbox2.old_levels_messages in
let target_ptr = hash_old_levels_messages inbox1.old_levels_messages in
Skip_list.valid_back_path
~equal_ptr:Hash.equal
~deref
~cell_ptr
~target_ptr
path
end
include (
MakeHashingScheme (struct
include Context.Tree
type t = Context.t
type tree = Context.tree
type value = bytes
type key = string list
end) :
MerkelizedOperations with type tree = Context.tree)
type inbox = t
module Proof = struct
type starting_point = {inbox_level : Raw_level_repr.t; message_counter : Z.t}
type t = {
skips : (inbox * inclusion_proof) list;
level : inbox;
inc : inclusion_proof;
message_proof : Context.Proof.tree Context.Proof.t;
}
let pp fmt proof =
Format.fprintf fmt "Inbox proof with %d skips" (List.length proof.skips)
let encoding =
let open Data_encoding in
conv
(fun {skips; level; inc; message_proof} ->
(skips, level, inc, message_proof))
(fun (skips, level, inc, message_proof) ->
{skips; level; inc; message_proof})
(obj4
(req "skips" (list (tup2 encoding inclusion_proof_encoding)))
(req "level" encoding)
(req "inc" inclusion_proof_encoding)
(req
"message_proof"
Context.Proof_encoding.V1.Tree32.tree_proof_encoding))
let split_proof proof =
match proof.skips with
| [] -> None
| (level, inc) :: rest -> Some (level, inc, {proof with skips = rest})
let bottom_level proof =
match proof.skips with [] -> proof.level | (level, _) :: _ -> level
let message_payload n tree =
let open Lwt_syntax in
let* r = get_message_payload tree n in
return (tree, r)
let check_hash hash kinded_hash =
match kinded_hash with
| `Node h -> Hash.(equal (of_context_hash h) hash)
| `Value h -> Hash.(equal (of_context_hash h) hash)
type error += Inbox_proof_error of string
let proof_error reason =
let open Lwt_result_syntax in
fail (Inbox_proof_error reason)
let drop_error promise reason =
let open Lwt_tzresult_syntax in
let*! result = promise in
match result with Ok r -> return r | Error _ -> proof_error reason
let rec valid {inbox_level = l; message_counter = n} inbox proof =
assert (Z.(geq n zero)) ;
let open Lwt_result_syntax in
match split_proof proof with
| None ->
if
verify_inclusion_proof proof.inc proof.level inbox
&& Raw_level_repr.equal (inbox_level proof.level) l
&& check_hash
(proof.level.current_messages_hash ())
proof.message_proof.before
then
let* (_ : Context.tree), payload =
drop_error
(Context.verify_tree_proof
proof.message_proof
(message_payload n))
"message_proof invalid"
in
match payload with
| None ->
if equal proof.level inbox then return None
else proof_error "payload is None, inbox proof.level not top"
| Some msg ->
return
@@ Some
Sc_rollup_PVM_sem.
{inbox_level = l; message_counter = n; payload = msg}
else proof_error "Inbox proof parameters don't match (message level)"
| Some (level, inc, remaining_proof) ->
if
verify_inclusion_proof inc level (bottom_level remaining_proof)
&& Raw_level_repr.equal (inbox_level level) l
&& Z.equal level.message_counter n
then
valid
{inbox_level = Raw_level_repr.succ l; message_counter = Z.zero}
inbox
remaining_proof
else proof_error "Inbox proof parameters don't match (lower level)"
let produce_proof _ _ = assert false
end