Add EthHashStr validation

nimbus/rpc/hexstrings.nim

@@ -13,11 +13,13 @@
 type
   HexQuantityStr* = distinct string
   HexDataStr* = distinct string
-  EthAddressStr* = distinct string
+  EthAddressStr* = distinct string  # Same as HexDataStr but must be less <= 20 bytes
+  EthHashStr* = distinct string     # Same as HexDataStr but must be exactly 32 bytes
 
-func len*(data: HexQuantityStr): int = data.string.len
+func len*(quantity: HexQuantityStr): int = quantity.string.len
 func len*(data: HexDataStr): int = data.string.len
 func len*(data: EthAddressStr): int = data.string.len
+func len*(data: EthHashStr): int = data.string.len
 
 # Hex validation
 
@@ -67,12 +69,20 @@ func isValidHexData*(value: string): bool =
 
 func isValidEthAddress*(value: string): bool =
   # 20 bytes for EthAddress plus "0x"
+  # Addresses are allowed to be shorter than 20 bytes for convenience
   result = value.len <= 42 and value.isValidHexData
 
+func isValidEthHash*(value: string): bool =
+  # 32 bytes for EthAddress plus "0x"
+  # Currently hashes are required to be exact lengths
+  # TODO: Allow shorter hashes (pad with zeros) for convenience?
+  result = value.len == 66 and value.isValidHexData
+
 const
   SInvalidQuantity = "Invalid hex quantity format for Ethereum"
   SInvalidData = "Invalid hex data format for Ethereum"
   SInvalidAddress = "Invalid address format for Ethereum"
+  SInvalidHash = "Invalid hash format for Ethereum"
 
 proc validateHexQuantity*(value: string) {.inline.} =
   if unlikely(not value.isValidHexQuantity):
@@ -86,6 +96,10 @@ proc validateHexAddressStr*(value: string) {.inline.} =
   if unlikely(not value.isValidEthAddress):
     raise newException(ValueError, SInvalidAddress & ": " & value)
 
+proc validateHashStr*(value: string) {.inline.} =
+  if unlikely(not value.isValidEthHash):
+    raise newException(ValueError, SInvalidHash & ": " & value)
+
 # Initialisation
 
 proc hexQuantityStr*(value: string): HexQuantityStr {.inline.} =
@@ -100,6 +114,10 @@ proc ethAddressStr*(value: string): EthAddressStr {.inline.} =
   value.validateHexAddressStr
   result = value.EthAddressStr
 
+proc ethHashStr*(value: string): EthHashStr {.inline.} =
+  value.validateHashStr
+  result = value.EthHashStr
+
 # Converters for use in RPC
 
 import json
@@ -114,6 +132,9 @@ proc `%`*(value: HexDataStr): JsonNode =
 proc `%`*(value: EthAddressStr): JsonNode =
   result = %(value.string)
 
+proc `%`*(value: EthHashStr): JsonNode =
+  result = %(value.string)
+
 proc fromJson*(n: JsonNode, argName: string, result: var HexQuantityStr) =
   # Note that '0x' is stripped after validation
   n.kind.expect(JString, argName)
@@ -138,3 +159,11 @@ proc fromJson*(n: JsonNode, argName: string, result: var EthAddressStr) =
     raise newException(ValueError, "Parameter \"" & argName & "\" is not valid as an Ethereum address \"" & hexStr & "\"")
   result = hexStr.EthAddressStr
 
+proc fromJson*(n: JsonNode, argName: string, result: var EthHashStr) =
+  # Note that '0x' is stripped after validation
+  n.kind.expect(JString, argName)
+  let hexStr = n.getStr()
+  if not hexStr.isValidEthHash:
+    raise newException(ValueError, "Parameter \"" & argName & "\" is not valid as an Ethereum hash \"" & hexStr & "\"")
+  result = hexStr.EthHashStr
+