Add validated hex string type

tests/ethhexstrings.nim

@@ -0,0 +1,151 @@
+type
+  HexQuantityStr* = distinct string
+  HexDataStr* = distinct string
+
+# Hex validation
+
+template stripLeadingZeros(value: string): string =
+  var cidx = 0
+  # ignore the last character so we retain '0' on zero value
+  while cidx < value.len - 1 and value[cidx] == '0':
+    cidx.inc
+  value[cidx .. ^1]
+
+proc encodeQuantity*(value: SomeUnsignedInt): string =
+  var hValue = value.toHex.stripLeadingZeros
+  result = "0x" & hValue
+
+template hasHexHeader*(value: string | HexDataStr | HexQuantityStr): bool =
+  template strVal: untyped = value.string
+  if strVal[0] == '0' and strVal[1] in {'x', 'X'} and strVal.len > 2: true
+  else: false
+
+template isHexChar*(c: char): bool =
+  if  c notin {'0'..'9'} and
+      c notin {'a'..'f'} and
+      c notin {'A'..'F'}: false
+  else: true
+
+proc validate*(value: HexQuantityStr): bool =
+  template strVal: untyped = value.string
+  if not value.hasHexHeader:
+    return false
+  # No leading zeros
+  if strVal[2] == '0': return false
+  for i in 2..<strVal.len:
+    let c = strVal[i]
+    if not c.isHexChar:
+      return false
+  return true
+
+proc validate*(value: HexDataStr): bool =
+  template strVal: untyped = value.string
+  if not value.hasHexHeader:
+    return false
+  # Leading zeros are allowed
+  for i in 2..<strVal.len:
+    let c = strVal[i]
+    if not c.isHexChar:
+      return false
+  # Must be even number of digits
+  if strVal.len mod 2 != 0: return false
+  return true
+
+# Initialisation
+
+template hexDataStr*(value: string): HexDataStr = value.HexDataStr
+template hexQuantityStr*(value: string): HexQuantityStr = value.HexQuantityStr
+
+# Converters
+
+import json 
+from ../rpcserver import expect
+
+proc `%`*(value: HexDataStr): JsonNode =
+  if not value.validate:
+    raise newException(ValueError, "HexDataStr: Invalid hex for Ethereum: " & value.string)
+  else:
+    result = %(value.string)
+
+proc `%`*(value: HexQuantityStr): JsonNode =
+  if not value.validate:
+    raise newException(ValueError, "HexQuantityStr: Invalid hex for Ethereum: " & value.string)
+  else:
+    result = %(value.string)
+
+proc fromJson*(n: JsonNode, argName: string, result: var HexDataStr) =
+  # Note that '0x' is stripped after validation
+  n.kind.expect(JString, argName)
+  let hexStr = n.getStr()
+  if not hexStr.hexDataStr.validate:
+    raise newException(ValueError, "Parameter \"" & argName & "\" value is not valid as a Ethereum data \"" & hexStr & "\"")
+  result = hexStr[2..hexStr.high].hexDataStr
+
+proc fromJson*(n: JsonNode, argName: string, result: var HexQuantityStr) =
+  # Note that '0x' is stripped after validation
+  n.kind.expect(JString, argName)
+  let hexStr = n.getStr()
+  if not hexStr.hexQuantityStr.validate:
+    raise newException(ValueError, "Parameter \"" & argName & "\" value is not valid as an Ethereum hex quantity \"" & hexStr & "\"")
+  result = hexStr[2..hexStr.high].hexQuantityStr
+
+# testing
+
+when isMainModule:
+  import unittest
+  suite "Hex quantity":
+    test "Even length":
+      let
+        source = "0x123"
+        x = hexQuantityStr source
+      check %x == %source
+    test "Odd length":
+      let
+        source = "0x123"
+        x = hexQuantityStr"0x123"
+      check %x == %source
+    test "Missing header":
+      expect ValueError:
+        let
+          source = "1234"
+          x = hexQuantityStr source
+        check %x != %source
+      expect ValueError:
+        let
+          source = "01234"
+          x = hexQuantityStr source
+        check %x != %source
+      expect ValueError:
+        let
+          source = "x1234"
+          x = hexQuantityStr source
+        check %x != %source
+      
+  suite "Hex data":
+    test "Even length":
+      let
+        source = "0x1234"
+        x = hexDataStr source
+      check %x == %source
+    test "Odd length":
+      expect ValueError:
+        let
+          source = "0x123"
+          x = hexDataStr source
+        check %x != %source
+    test "Missing header":
+      expect ValueError:
+        let
+          source = "1234"
+          x = hexDataStr source
+        check %x != %source
+      expect ValueError:
+        let
+          source = "01234"
+          x = hexDataStr source
+        check %x != %source
+      expect ValueError:
+        let
+          source = "x1234"
+          x = hexDataStr source
+        check %x != %source

tests/ethprocs.nim

@@ -1,4 +1,4 @@
-import ../rpcserver, nimcrypto, json, stint, strutils, ethtypes, stintjson, ethutils
+import ../rpcserver, nimcrypto, json, stint, strutils, ethtypes, stintjson, ethhexstrings
 
 #[
   For details on available RPC calls, see: https://github.com/ethereum/wiki/wiki/JSON-RPC
@@ -31,19 +31,16 @@ proc addEthRpcs*(server: RpcServer) =
     ## Returns the current client version.
     result = "Nimbus-RPC-Test"
 
-  server.rpc("web3_sha3") do(data: string) -> string:
+  server.rpc("web3_sha3") do(data: HexDataStr) -> HexDataStr:
     ## Returns Keccak-256 (not the standardized SHA3-256) of the given data.
     ##
     ## data: the data to convert into a SHA3 hash.
     ## Returns the SHA3 result of the given string.
     # TODO: Capture error on malformed input
     var rawData: seq[byte]
-    if data.validateHexData:
+    rawData = data.string.fromHex
-      rawData = data[2..data.high].fromHex
-    else:
-      raise newException(ValueError, "Invalid hex format")
     # data will have 0x prefix
-    result = "0x" & $keccak_256.digest(rawData)
+    result = hexDataStr "0x" & $keccak_256.digest(rawData)
 
   server.rpc("net_version") do() -> string:
     ## Returns string of the current network id:

tests/ethutils.nim

@@ -1,43 +0,0 @@
-template stripLeadingZeros(value: string): string =
-  var cidx = 0
-  # ignore the last character so we retain '0' on zero value
-  while cidx < value.len - 1 and value[cidx] == '0':
-    cidx.inc
-  value[cidx .. ^1]
-
-proc encodeQuantity*(value: SomeUnsignedInt): string =
-  var hValue = value.toHex.stripLeadingZeros
-  result = "0x" & hValue
-
-template hasHexHeader*(value: string): bool =
-  if value[0] == '0' and value[1] in {'x', 'X'} and value.len > 2: true
-  else: false
-
-template isHexChar*(c: char): bool =
-  if  c notin {'0'..'9'} and
-      c notin {'a'..'f'} and
-      c notin {'A'..'F'}: false
-  else: true
-
-proc validateHexQuantity*(value: string): bool =
-  if not value.hasHexHeader:
-    return false
-  # No leading zeros
-  if value[2] == '0': return false
-  for i in 2..<value.len:
-    let c = value[i]
-    if not c.isHexChar:
-      return false
-  return true
-
-proc validateHexData*(value: string): bool =
-  if not value.hasHexHeader:
-    return false
-  # Leading zeros are allowed
-  for i in 2..<value.len:
-    let c = value[i]
-    if not c.isHexChar:
-      return false
-  # Must be even number of digits
-  if value.len mod 2 != 0: return false
-  return true

tests/testethcalls.nim

@@ -1,6 +1,6 @@
 import unittest, json, tables
 import ../rpcclient, ../rpcstreamservers
-import stint, ethtypes, ethprocs, stintjson, nimcrypto
+import stint, ethtypes, ethprocs, stintjson, nimcrypto, ethhexstrings
 
 from os import getCurrentDir, DirSep
 from strutils import rsplit