Build out the validation of google.protobuf.Any JSON support.

Sources/SwiftProtobuf/AnyMessageStorage.swift

@@ -411,6 +411,13 @@ extension AnyMessageStorage {
 
 // _CustomJSONCodable support for Google_Protobuf_Any
 extension AnyMessageStorage {
+    // Spec for Any says this should contain atleast one slash. Looking at upstream languages, most
+    // actually look up the value in their runtime registries, but since we do deferred parsing
+    // we can't assume the registry is complete, thus just do this minimal validation check.
+    fileprivate func isTypeURLValid() -> Bool {
+        _typeURL.contains("/")
+    }
+
     // Override the traversal-based JSON encoding
     // This builds an Any JSON representation from one of:
     //  * The message we were initialized with,
@@ -423,11 +430,18 @@ extension AnyMessageStorage {
         case .binary(let valueData):
             // Follow the C++ protostream_objectsource.cc's
             // ProtoStreamObjectSource::RenderAny() special casing of an empty value.
-            guard !valueData.isEmpty else {
+            if valueData.isEmpty && _typeURL.isEmpty {
+                return "{}"
+            }
+            guard isTypeURLValid() else {
                 if _typeURL.isEmpty {
-                    return "{}"
+                    throw SwiftProtobufError.JSONEncoding.emptyAnyTypeURL()
                 }
+                throw SwiftProtobufError.JSONEncoding.invalidAnyTypeURL(type_url: _typeURL)
+            }
+            if valueData.isEmpty {
                 var jsonEncoder = JSONEncoder()
+                jsonEncoder.startObject()
                 jsonEncoder.startField(name: "@type")
                 jsonEncoder.putStringValue(value: _typeURL)
                 jsonEncoder.endObject()
@@ -446,12 +460,21 @@ extension AnyMessageStorage {
             return try serializeAnyJSON(for: m, typeURL: _typeURL, options: options)
 
         case .message(let msg):
-            // We should have been initialized with a typeURL, but
-            // ensure it wasn't cleared.
+            // We should have been initialized with a typeURL, make sure it is valid.
+            if !_typeURL.isEmpty && !isTypeURLValid() {
+                throw SwiftProtobufError.JSONEncoding.invalidAnyTypeURL(type_url: _typeURL)
+            }
+            // If it was cleared, default it.
             let url = !_typeURL.isEmpty ? _typeURL : buildTypeURL(forMessage: msg, typePrefix: defaultAnyTypeURLPrefix)
             return try serializeAnyJSON(for: msg, typeURL: url, options: options)
 
         case .contentJSON(let contentJSON, _):
+            guard isTypeURLValid() else {
+                if _typeURL.isEmpty {
+                    throw SwiftProtobufError.JSONEncoding.emptyAnyTypeURL()
+                }
+                throw SwiftProtobufError.JSONEncoding.invalidAnyTypeURL(type_url: _typeURL)
+            }
             var jsonEncoder = JSONEncoder()
             jsonEncoder.startObject()
             jsonEncoder.startField(name: "@type")
@@ -488,11 +511,7 @@ extension AnyMessageStorage {
             try decoder.scanner.skipRequiredColon()
             if key == "@type" {
                 _typeURL = try decoder.scanner.nextQuotedString()
-                // Spec for Any says this should contain atleast one slash. Looking at
-                // upstream languages, most actually look up the value in their runtime
-                // registries, but since we do deferred parsing, just do this minimal
-                // validation check.
-                guard _typeURL.contains("/") else {
+                guard isTypeURLValid() else {
                     throw SwiftProtobufError.JSONDecoding.invalidAnyTypeURL(type_url: _typeURL)
                 }
             } else {
@@ -501,6 +520,9 @@ extension AnyMessageStorage {
                 jsonEncoder.append(text: keyValueJSON)
             }
             if decoder.scanner.skipOptionalObjectEnd() {
+                if _typeURL.isEmpty {
+                    throw SwiftProtobufError.JSONDecoding.emptyAnyTypeURL()
+                }
                 // Capture the options, but set the messageDepthLimit to be what
                 // was left right now, as that is the limit when the JSON is finally
                 // parsed.

Sources/SwiftProtobuf/Message+JSONAdditions.swift

@@ -24,7 +24,7 @@ extension Message {
     /// - Returns: A string containing the JSON serialization of the message.
     /// - Parameters:
     ///   - options: The JSONEncodingOptions to use.
-    /// - Throws: ``JSONEncodingError`` if encoding fails.
+    /// - Throws: ``SwiftProtobufError`` or ``JSONEncodingError`` if encoding fails.
     public func jsonString(
         options: JSONEncodingOptions = JSONEncodingOptions()
     ) throws -> String {
@@ -43,7 +43,7 @@ extension Message {
     /// - Returns: A `SwiftProtobufContiguousBytes` containing the JSON serialization of the message.
     /// - Parameters:
     ///   - options: The JSONEncodingOptions to use.
-    /// - Throws: ``JSONEncodingError`` if encoding fails.
+    /// - Throws: ``SwiftProtobufError`` or ``JSONEncodingError`` if encoding fails.
     public func jsonUTF8Bytes<Bytes: SwiftProtobufContiguousBytes>(
         options: JSONEncodingOptions = JSONEncodingOptions()
     ) throws -> Bytes {

Sources/SwiftProtobuf/Message+JSONAdditions_Data.swift

@@ -54,7 +54,7 @@ extension Message {
     /// - Returns: A Data containing the JSON serialization of the message.
     /// - Parameters:
     ///   - options: The JSONEncodingOptions to use.
-    /// - Throws: ``JSONEncodingError`` if encoding fails.
+    /// - Throws: ``SwiftProtobufError`` or ``JSONEncodingError`` if encoding fails.
     public func jsonUTF8Data(
         options: JSONEncodingOptions = JSONEncodingOptions()
     ) throws -> Data {

Sources/SwiftProtobuf/Message+JSONArrayAdditions.swift

@@ -25,7 +25,7 @@ extension Message {
     /// - Parameters:
     ///   - collection: The list of messages to encode.
     ///   - options: The JSONEncodingOptions to use.
-    /// - Throws: ``JSONEncodingError`` if encoding fails.
+    /// - Throws: ``SwiftProtobufError`` or ``JSONEncodingError`` if encoding fails.
     public static func jsonString<C: Collection>(
         from collection: C,
         options: JSONEncodingOptions = JSONEncodingOptions()
@@ -43,7 +43,7 @@ extension Message {
     /// - Parameters:
     ///   - collection: The list of messages to encode.
     ///   - options: The JSONEncodingOptions to use.
-    /// - Throws: ``JSONEncodingError`` if encoding fails.
+    /// - Throws: ``SwiftProtobufError`` or ``JSONEncodingError`` if encoding fails.
     public static func jsonUTF8Bytes<C: Collection, Bytes: SwiftProtobufContiguousBytes>(
         from collection: C,
         options: JSONEncodingOptions = JSONEncodingOptions()

Sources/SwiftProtobuf/Message+JSONArrayAdditions_Data.swift

@@ -65,7 +65,7 @@ extension Message {
     /// - Parameters:
     ///   - collection: The list of messages to encode.
     ///   - options: The JSONEncodingOptions to use.
-    /// - Throws: ``JSONEncodingError`` if encoding fails.
+    /// - Throws: ``SwiftProtobufError`` or ``JSONEncodingError`` if encoding fails.
     public static func jsonUTF8Data<C: Collection>(
         from collection: C,
         options: JSONEncodingOptions = JSONEncodingOptions()

Sources/SwiftProtobuf/SwiftProtobufError.swift

@@ -92,6 +92,7 @@ extension SwiftProtobufError {
             case binaryDecodingError
             case binaryStreamDecodingError
             case jsonDecodingError
+            case jsonEncodingError
 
             var description: String {
                 switch self {
@@ -101,6 +102,8 @@ extension SwiftProtobufError {
                     return "Stream decoding error"
                 case .jsonDecodingError:
                     return "JSON decoding error"
+                case .jsonEncodingError:
+                    return "JSON encoding error"
                 }
             }
         }
@@ -131,6 +134,10 @@ extension SwiftProtobufError {
             Self(.jsonDecodingError)
         }
 
+        /// Errors arising from JSON encoding of messages.
+        public static var jsonEncodingError: Self {
+            Self(.jsonEncodingError)
+        }
     }
 
     /// A location within source code.
@@ -264,6 +271,48 @@ extension SwiftProtobufError {
                 location: SourceLocation(function: function, file: file, line: line)
             )
         }
+
+        /// While decoding a `google.protobuf.Any` no `@type` field but the message had other fields.
+        public static func emptyAnyTypeURL(
+            function: String = #function,
+            file: String = #fileID,
+            line: Int = #line
+        ) -> SwiftProtobufError {
+            SwiftProtobufError(
+                code: .jsonDecodingError,
+                message: "google.protobuf.Any '@type' was must be present if if the object is not empty.",
+                location: SourceLocation(function: function, file: file, line: line)
+            )
+        }
     }
 
+    /// Errors arising from JSON encoding of messages.
+    public enum JSONEncoding {
+        /// While encoding a `google.protobuf.Any` encountered a malformed `type_url` field.
+        public static func invalidAnyTypeURL(
+            type_url: String,
+            function: String = #function,
+            file: String = #fileID,
+            line: Int = #line
+        ) -> SwiftProtobufError {
+            SwiftProtobufError(
+                code: .jsonEncodingError,
+                message: "google.protobuf.Any 'type_url' was invalid: \(type_url).",
+                location: SourceLocation(function: function, file: file, line: line)
+            )
+        }
+
+        /// While encoding a `google.protobuf.Any` encountered an empty `type_url` field.
+        public static func emptyAnyTypeURL(
+            function: String = #function,
+            file: String = #fileID,
+            line: Int = #line
+        ) -> SwiftProtobufError {
+            SwiftProtobufError(
+                code: .jsonEncodingError,
+                message: "google.protobuf.Any 'type_url' was empty, only allowed for empty objects.",
+                location: SourceLocation(function: function, file: file, line: line)
+            )
+        }
+    }
 }