Make EIP712Domain Fields Optional (#11103)

According to
https://github.com/ethereum/EIPs/blob/master/EIPS/eip-712.md#definition-
of-domainseparator “Protocol designers only need to include the fields
that make sense for their signing domain.”

util/EIP-712/src/eip712.rs

@@ -19,8 +19,7 @@ use serde_json::{Value};
 use std::collections::HashMap;
 use ethereum_types::{U256, H256, Address};
 use regex::Regex;
-use validator::Validate;
+use validator::{Validate, ValidationError, ValidationErrors};
-use validator::ValidationErrors;
 use lazy_static::lazy_static;
 
 pub(crate) type MessageTypes = HashMap<String, Vec<FieldType>>;
@@ -32,16 +31,28 @@ lazy_static! {
 }
 
 #[serde(rename_all = "camelCase")]
-#[serde(deny_unknown_fields)]
 #[derive(Deserialize, Serialize, Validate, Debug, Clone)]
+#[validate(schema(function = "validate_domain"))]
 pub(crate) struct EIP712Domain {
-	pub(crate) name: String,
+	#[serde(skip_serializing_if="Option::is_none")]
-	pub(crate) version: String,
+	pub(crate) name: Option<String>,
-	pub(crate) chain_id: U256,
+	#[serde(skip_serializing_if="Option::is_none")]
-	pub(crate) verifying_contract: Address,
+	pub(crate) version: Option<String>,
+	#[serde(skip_serializing_if="Option::is_none")]
+	pub(crate) chain_id: Option<U256>,
+	#[serde(skip_serializing_if="Option::is_none")]
+	pub(crate) verifying_contract: Option<Address>,
 	#[serde(skip_serializing_if="Option::is_none")]
 	pub(crate) salt: Option<H256>,
 }
+
+fn validate_domain(domain: &EIP712Domain) -> Result<(), ValidationError> {
+	match (domain.name.as_ref(), domain.version.as_ref(), domain.chain_id, domain.verifying_contract, domain.salt) {
+		(None, None, None, None, None) => Err(ValidationError::new("EIP712Domain must include at least one field")),
+		_ => Ok(())
+	}
+}
+
 /// EIP-712 struct
 #[serde(rename_all = "camelCase")]
 #[serde(deny_unknown_fields)]
@@ -55,6 +66,7 @@ pub struct EIP712 {
 
 impl Validate for EIP712 {
 	fn validate(&self) -> Result<(), ValidationErrors> {
+		self.domain.validate()?;
 		for field_types in self.types.values() {
 			for field_type in field_types {
 				field_type.validate()?;
@@ -159,7 +171,8 @@ mod tests {
 					{ "name": "name", "type": "string" },
 					{ "name": "version", "type": "string" },
 					{ "name": "chainId", "type": "7uint256[x] Seun" },
-					{ "name": "verifyingContract", "type": "address" }
+					{ "name": "verifyingContract", "type": "address" },
+					{ "name": "salt", "type": "bytes32" }
 				],
 				"Person": [
 					{ "name": "name", "type": "string" },
@@ -175,4 +188,59 @@ mod tests {
 		let data = from_str::<EIP712>(string).unwrap();
 		assert_eq!(data.validate().is_err(), true);
 	}
+
+    #[test]
+	fn test_valid_domain() {
+		let string = r#"{
+			"primaryType": "Test",
+			"domain": {
+				"name": "Ether Mail",
+				"version": "1",
+				"chainId": "0x1",
+				"verifyingContract": "0xCcCCccccCCCCcCCCCCCcCcCccCcCCCcCcccccccC",
+				"salt": "0x0000000000000000000000000000000000000000000000000000000000000001"
+			},
+			"message": {
+				"test": "It works!"
+			},
+			"types": {
+				"EIP712Domain": [
+					{ "name": "name", "type": "string" },
+					{ "name": "version", "type": "string" },
+					{ "name": "chainId", "type": "uint256" },
+					{ "name": "verifyingContract", "type": "address" },
+					{ "name": "salt", "type": "bytes32" }
+				],
+				"Test": [
+					{ "name": "test", "type": "string" }
+				]
+			}
+		}"#;
+		let data = from_str::<EIP712>(string).unwrap();
+		assert_eq!(data.validate().is_err(), false);
+	}
+
+	#[test]
+	fn domain_needs_at_least_one_field() {
+		let string = r#"{
+			"primaryType": "Test",
+			"domain": {},
+			"message": {
+				"test": "It works!"
+			},
+			"types": {
+				"EIP712Domain": [
+					{ "name": "name", "type": "string" },
+					{ "name": "version", "type": "string" },
+					{ "name": "chainId", "type": "uint256" },
+					{ "name": "verifyingContract", "type": "address" }
+				],
+				"Test": [
+					{ "name": "test", "type": "string" }
+				]
+			}
+		}"#;
+		let data = from_str::<EIP712>(string).unwrap();
+		assert_eq!(data.validate().is_err(), true);
+	}
 }