add signatures.ml

include/dune

@@ -0,0 +1,39 @@
+(library
+ (name include)
+ ; (wrapped false)
+ (modules taler_signatures)
+ (libraries))
+
+(rule
+ (targets taler_signatures.ml)
+ (deps ./gen_taler_signatures.exe)
+ (action
+  (with-stdout-to
+   %{targets}
+   (run ./gen_taler_signatures.exe))))
+
+(executable
+ (name gen_taler_signatures)
+ (modules gen_taler_signatures data)
+ (libraries fmt angstrom))
+
+(rule
+ (targets taler_signatures.h)
+ (action
+  (run
+   wget
+   -q
+   -O
+   %{targets}
+   "https://git.taler.net/exchange.git/plain/src/include/taler/taler_signatures.h")))
+
+(rule
+ (targets data.ml)
+ (deps taler_signatures.h)
+ (action
+  (with-stdout-to
+   %{targets}
+   (progn
+    (echo "let content = {|")
+    (cat taler_signatures.h)
+    (echo "|}")))))

include/gen_taler_signatures.ml

@@ -0,0 +1,50 @@
+(* script to generate signatures.ml module
+   get signatures definition form `exchange/src/include/taler/taler_signatures.h`
+   the make a ocaml value for each #define and print them in a
+   taler_signatures.ml module *)
+
+open Angstrom
+
+type define = {
+  name: string;
+  value: int;
+}
+
+let define_line : define t =
+  let is_ident_char = function
+    | 'A' .. 'Z' | '0' .. '9' | '_' -> true
+    | _ -> false
+  in
+  let p =
+    string "#define"
+    *> skip_while (( = ) ' ')
+    *> string "TALER_SIGNATURE_"
+    *> take_while1 is_ident_char
+    >>= fun name ->
+    skip_while (( = ) ' ')
+    *> take_while1 (function '0' .. '9' -> true | _ -> false)
+    >>| fun digits ->
+    let name = String.lowercase_ascii name in
+    let value = int_of_string digits in
+    { name; value }
+  in
+  p <* end_of_line
+
+let all_defines : define list t =
+  let any_line = take_till (Char.equal '\n') <* end_of_line in
+  many (choice [ define_line >>| Option.some; any_line *> return None ])
+  >>| List.filter_map Fun.id
+
+let parse input =
+  match parse_string ~consume:All all_defines input with
+  | Ok defs -> defs
+  | Error msg -> failwith msg
+
+let () =
+  let l = parse Data.content in
+  assert (List.length l = 74);
+
+  let pp ppf { name; value } = Fmt.pf ppf "let %s = %d@." name value in
+  Fmt.pr "%a" (Fmt.list pp) l;
+
+  ()

src/dune

@@ -11,6 +11,8 @@
  (libraries
   base_32
   ;
+  include
+  ;
   angstrom
   zarith ;
   mirage-crypto

src/signatures.ml

@@ -0,0 +1,23 @@
+(* https://docs.taler.net/core/api-common.html#id7 *)
+
+module Purpose = struct
+  (* defined in gnunet_crypto_lib.h *)
+  type t = {
+    (* This field equals the number of bytes being signed,
+       namely 'sizeof (struct Data)'. *)
+    size: Int32.t; (* = uint32_t *)
+    (* This field is used to express the context in
+       which the signature is made, ensuring that a
+       signature cannot be lifted from one part of the protocol
+       to another. See `src/include/taler/taler_signatures.h` within the
+       exchange's codebase (git://taler.net/exchange). *)
+    purpose: Int32.t; (* = uint32_t *)
+  }
+end
+
+module Data = struct
+  type t = {
+    purpose: Purpose.t;
+    payloads: string list;
+  }
+end