From 454090546f009310409653533d53296c363818eb Mon Sep 17 00:00:00 2001
From: swrup <swrup@protonmail.com>
Date: Tue, 7 Oct 2025 12:02:16 +0200
Subject: [PATCH] purpose rec sizeof

---
 src/binary_formats.ml | 36 +++++++++++++++++++++++++++++-------
 1 file changed, 29 insertions(+), 7 deletions(-)

diff --git a/src/binary_formats.ml b/src/binary_formats.ml
index fd9cafe2..6d42bd03 100644
--- a/src/binary_formats.ml
+++ b/src/binary_formats.ml
@@ -55,27 +55,38 @@ module Hash_code = struct
   (* usually SHA-512 *)
   type t = { hash: string (* = uint8_t hash[64] *) }
 
+  let size = 64
+
   let bin =
     let open Bin in
-    record (fun hash -> { hash }) |+ field (bytes 64) (fun t -> t.hash) |> sealr
+    record (fun hash -> { hash })
+    |+ field (bytes size) (fun t -> t.hash)
+    |> sealr
 end
 
 module Short_hash_code = struct
   type t = { hash: string }
 
+  let size = 32
+
   let bin =
     let open Bin in
-    record (fun hash -> { hash }) |+ field (bytes 32) (fun t -> t.hash) |> sealr
+    record (fun hash -> { hash })
+    |+ field (bytes size) (fun t -> t.hash)
+    |> sealr
 end
 
 module MAKE_H (H : sig
-  type t
+  type t = { hash: string }
 
+  val size : int
   val bin : t Bin.t
 end) =
 struct
   type t = { hash: H.t }
 
+  let size = H.size
+
   let bin =
     let open Bin in
     record (fun hash -> { hash }) |+ field H.bin (fun t -> t.hash) |> sealr
@@ -279,6 +290,8 @@ module Ecc_signature_purpose = struct
     |+ field beint32 (fun t -> t.size)
     |+ field beint32 (fun t -> t.purpose)
     |> sealr
+
+  let size = 4 + 4
 end
 
 (* This is the running SHA512-hash over all
@@ -473,7 +486,7 @@ module Withdraw_confirmation_ps = struct
   type t = {
     (* Purpose is #TALER_SIGNATURE_EXCHANGE_CONFIRM_WITHDRAW.
        Signed by a `struct TALER_ExchangePrivateKeyP` using EdDSA. *)
-    purpose: Ecc_signature_purpose.t;
+    (*purpose: Ecc_signature_purpose.t;*)
     (* Commitment made in the /withdraw request.
        Also needed for the /reveal-withdraw endpoint (in case
        of required proof of age restriction) and for /recoup *)
@@ -489,11 +502,20 @@ module Withdraw_confirmation_ps = struct
     noreveal_index: int32;
   }
 
+  let size = Ecc_signature_purpose.size + Hash_planchets_p.size + 4
+
+  let purpose =
+    Ecc_signature_purpose.
+      {
+        size= Int32.of_int size;
+        purpose= Include.Taler_signatures.exchange_confirm_withdraw;
+      }
+
   let bin =
     let open Bin in
-    record (fun purpose h_planchets noreveal_index ->
-        { purpose; h_planchets; noreveal_index })
-    |+ field Ecc_signature_purpose.bin (fun t -> t.purpose)
+    record (fun _purpose h_planchets noreveal_index ->
+        { h_planchets; noreveal_index })
+    |+ field Ecc_signature_purpose.bin (Fun.const purpose)
     |+ field Hash_planchets_p.bin (fun t -> t.h_planchets)
     |+ field beint32 (fun t -> t.noreveal_index)
     |> sealr