feat: support multihash as schema in zenroom given

this is now able to import a generic multihash type and recognize it
from its prefixes, it also operates some checks, then sets the schema
accordingly for the output. Given input can be specified or left
generic, then is autodetected.

src/lua/zencode_given.lua

@@ -201,6 +201,9 @@ function operate_conversion(guessed)
 			error("Could not read " .. guessed.name)
 		 end
 	  end
+      -- fun may return two values: val and optional param
+      -- which is used in ack() to set additional CODEC params
+      -- param is defined directly into the schema function!
 	  return fun(guessed.raw)
    end
 end
@@ -248,14 +251,20 @@ local function ack(what)
    local name <const> = _index_to_string(what)
    zencode_assert(t, 'No valid object found: ' .. name)
    empty(name)
-   local v <const> = operate_conversion(t)
-   ACK[name] = v
+   -- get value and optional additional parameters for codec
+   local val <const>, param <const> = operate_conversion(t)
+   ACK[name] = val
    if not CODEC[name].missing then
-	  local vt <const> = type(v)
-	  if iszen(vt) then
-		 CODEC[name].bintype = vt
+	  local valtype <const> = type(val)
+	  if iszen(valtype) then
+		 CODEC[name].bintype = valtype
 	  end
    end
+   if param then
+       for k,v in pairs(param) do
+           CODEC[name][k] = v
+       end
+   end
    -- name of schema may differ from name of object
    -- new_codec(name, { schema = ZEN.TMP.schema })
 

src/lua/zencode_hash.lua

@@ -48,16 +48,18 @@ end
 When("create hash of ''", _hash)
 When("create hash of '' using ''", _hash)
 
+-- global used by _mhout and _mhin
+local multihash_prefixes <const> = {
+    sha256 = OCTET.from_hex'12',
+    sha512 = OCTET.from_hex'13',
+    sha3_512 = OCTET.from_hex'14',
+    sha3_256 = OCTET.from_hex'16',
+    shake_256 = OCTET.from_hex'19',
+    keccak_256 = OCTET.from_hex'1b'
+}
+
 --https://github.com/multiformats/multicodec/blob/master/table.cs
-local function _multihash(n, obj)
-    local prefix <const> = {
-        sha256 = OCTET.from_hex'12',
-        sha512 = OCTET.from_hex'13',
-        sha3_512 = OCTET.from_hex'14',
-        sha3_256 = OCTET.from_hex'16',
-        shake_256 = OCTET.from_hex'19',
-        keccak_256 = OCTET.from_hex'1b'
-    }
+local function _mhout(n, obj)
     local _size <const> = {
         sha256 = OCTET.from_number(32):copy(15,1),
         sha512 = OCTET.from_number(64):copy(15,1),
@@ -66,20 +68,78 @@ local function _multihash(n, obj)
         shake_256 = OCTET.from_number(32):copy(15,1),
         keccak_256 = OCTET.from_number(32):copy(15,1)
     }
-    local pfx <const> = prefix[n]
+    local pfx <const> = multihash_prefixes[n]
     local sz <const> = _size[n]
     if not pfx then error("Multihash not supported: "..n,2) end
     if not sz  then error("Multihash not supported: "..n,2) end
     return pfx..sz..obj
 end
 
+local function _mhin(string_obj,hashtype)
+    if not type(string_obj) == 'string' then
+        error("Multihash invalid input: "..type(string_obj),3)
+    end
+    local obj <const> = CONF.input.encoding.fun(string_obj)
+    local prefixes <const> = {
+        ['12'] = 'sha256',
+        ['13'] = 'sha512',
+        ['14'] = 'sha3_512',
+        ['16'] = 'sha3_256',
+        ['19'] = 'shake_256',
+        ['1b'] = 'keccak_256'
+    }
+    local _pfx
+    local firstbyte <const> = obj:copy(0,1)
+    if hashtype then
+        _pfx = multihash_prefixes[hashtype]
+        if not _pfx then
+            error("Multihash not supported: "..hashtype,2) end
+        if firstbyte ~= _pfx then
+            error("Incorrect multihash found: "
+                  ..firstbyte:hex(),2) end
+        _pfx = hashtype
+    else
+        _pfx = prefixes[firstbyte:hex()]
+    end
+    if not _pfx then
+        error("Multihash not supported: ".._pfx,2) end
+    local sz <const> = tonumber(obj:copy(1,1):hex(),16)
+    if #obj ~= sz+2 then
+        error("Multihash invalid size: "..#obj,2) end
+    -- return additional params for the codec
+    return obj:copy(2,sz), {schema='multihash_'.._pfx}
+end
+
 ZEN:add_schema({
-        multihash_sha256   ={export=function(obj) return _multihash('sha256',obj) end},
-        multihash_sha512   ={export=function(obj) return _multihash('sha512',obj) end},
-        multihash_sha3_256 ={export=function(obj) return _multihash('sha3_256',obj) end},
-        multihash_sha3_512 ={export=function(obj) return _multihash('sha3_512',obj) end},
-        multihash_shake256 ={export=function(obj) return _multihash('shake_256',obj) end},
-        multihash_keccak256={export=function(obj) return _multihash('keccak_256',obj) end}
+        multihash = {
+            import=function(obj) return _mhin(obj) end,
+            export=function(obj)
+                error("Invalid multihash value",2) end
+        },
+        multihash_sha256   ={
+            import=function(obj) return _mhin(obj,'sha256') end,
+            export=function(obj) return _mhout('sha256',obj) end
+        },
+        multihash_sha512   ={
+            import=function(obj) return _mhin(obj,'sha512') end,
+            export=function(obj) return _mhout('sha512',obj) end
+        },
+        multihash_sha3_256 ={
+            import=function(obj) return _mhin(obj,'sha3_256') end,
+            export=function(obj) return _mhout('sha3_256',obj) end
+        },
+        multihash_sha3_512 ={
+            import=function(obj) return  _mhin(obj,'sha3_512') end,
+            export=function(obj) return _mhout('sha3_512',obj) end
+        },
+        multihash_shake256 ={
+            import=function(obj) return _mhin(obj,'shake_256') end,
+            export=function(obj) return _mhout('shake_256',obj) end
+        },
+        multihash_keccak256={
+            import=function(obj) return _mhin(obj,'keccak_256') end,
+            export=function(obj) return _mhout('keccak_256',obj) end
+        }
 })
 When("create multihash of ''",
      function(s)

test/zencode/hash.bats

@@ -267,3 +267,32 @@ EOF
     assert_output '{"multihash":"144098a2d34ebb5ab5452cc6211efd99715942c75210d0ee91f7e8897f777d2aed668c8dd9f7b52042b44514dc282e7c6b4da9c5e21ea14ef259ac29579918d4869d"}'
 }
 
+@test "Given I have a 'multihash'" {
+    cat << EOF > multihash_input.json
+{"multihash":"144098a2d34ebb5ab5452cc6211efd99715942c75210d0ee91f7e8897f777d2aed668c8dd9f7b52042b44514dc282e7c6b4da9c5e21ea14ef259ac29579918d4869d"}
+EOF
+    cat <<EOF | zexe multihash_input.zen multihash_input.json
+rule output encoding hex
+rule input encoding hex
+Given I have a 'multihash'
+and debug
+Then print the 'multihash'
+EOF
+    save_output 'multihash_input_3_512.json'
+    assert_output '{"multihash":"144098a2d34ebb5ab5452cc6211efd99715942c75210d0ee91f7e8897f777d2aed668c8dd9f7b52042b44514dc282e7c6b4da9c5e21ea14ef259ac29579918d4869d"}'
+}
+
+@test "Given I have a 'multihash_sha3_512'" {
+    cat << EOF > multihash_3_512_input.json
+{"multihash_sha3_512":"144098a2d34ebb5ab5452cc6211efd99715942c75210d0ee91f7e8897f777d2aed668c8dd9f7b52042b44514dc282e7c6b4da9c5e21ea14ef259ac29579918d4869d"}
+EOF
+    cat <<EOF | zexe multihash_3_512_input.zen multihash_3_512_input.json
+rule output encoding hex
+rule input encoding hex
+Given I have a 'multihash sha3 512'
+and debug
+Then print the 'multihash sha3 512'
+EOF
+    save_output 'multihash_defined_input_3_512.json'
+    assert_output '{"multihash_sha3_512":"144098a2d34ebb5ab5452cc6211efd99715942c75210d0ee91f7e8897f777d2aed668c8dd9f7b52042b44514dc282e7c6b4da9c5e21ea14ef259ac29579918d4869d"}'
+}