Validate messages before sending

SessionMessagingKit/Messages/Control Message/ClosedGroupUpdate.swift

@@ -19,6 +19,9 @@ public final class ClosedGroupUpdate : ControlMessage {
         self.kind = kind
     }
 
+    // MARK: Validation
+    public override var isValidForSending: Bool { kind != nil }
+
     // MARK: Coding
     public required init?(coder: NSCoder) {
         super.init(coder: coder)

SessionMessagingKit/Messages/Control Message/ExpirationTimerUpdate.swift

@@ -10,6 +10,9 @@ public final class ExpirationTimerUpdate : ControlMessage {
         self.duration = duration
     }
 
+    // MARK: Validation
+    public override var isValidForSending: Bool { duration != nil }
+
     // MARK: Coding
     public required init?(coder: NSCoder) {
         super.init(coder: coder)

SessionMessagingKit/Messages/Control Message/ReadReceipt.swift

@@ -10,6 +10,12 @@ public final class ReadReceipt : ControlMessage {
         self.timestamps = timestamps
     }
 
+    // MARK: Validation
+    public override var isValidForSending: Bool {
+        if let timestamps = timestamps, !timestamps.isEmpty { return true }
+        return false
+    }
+
     // MARK: Coding
     public required init?(coder: NSCoder) {
         super.init(coder: coder)

SessionMessagingKit/Messages/Control Message/SessionRequest.swift

@@ -11,6 +11,9 @@ public final class SessionRequest : ControlMessage {
         self.preKeyBundle = preKeyBundle
     }
 
+    // MARK: Validation
+    public override var isValidForSending: Bool { preKeyBundle != nil }
+
     // MARK: Coding
     public required init?(coder: NSCoder) {
         super.init(coder: coder)

SessionMessagingKit/Messages/Control Message/TypingIndicator.swift

@@ -23,6 +23,9 @@ public final class TypingIndicator : ControlMessage {
         }
     }
 
+    // MARK: Validation
+    public override var isValidForSending: Bool { kind != nil }
+
     // MARK: Initialization
     internal init(kind: Kind) {
         super.init()

SessionMessagingKit/Messages/Message.swift

@@ -10,6 +10,9 @@ public class Message : NSObject, NSCoding { // Not a protocol for YapDatabase co
 
     public override init() { }
 
+    // MARK: Validation
+    public var isValidForSending: Bool { true }
+
     // MARK: Coding
     public required init?(coder: NSCoder) {
         if let id = coder.decodeObject(forKey: "id") as! String? { self.id = id }

SessionMessagingKit/Messages/Visible Message/VisibleMessage.swift

@@ -12,6 +12,13 @@ public final class VisibleMessage : Message {
     // MARK: Initialization
     public override init() { super.init() }
 
+    // MARK: Validation
+    public override var isValidForSending: Bool {
+        if !attachmentIDs.isEmpty { return true }
+        if let text = text?.trimmingCharacters(in: .whitespacesAndNewlines), !text.isEmpty { return true }
+        return false
+    }
+
     // MARK: Coding
     public required init?(coder: NSCoder) {
         super.init(coder: coder)

SessionMessagingKit/Pipelines/SendingPipeline.swift

@@ -3,6 +3,7 @@ import SessionSnodeKit
 import SessionUtilities
 
 public enum SendingPipeline {
+    private static let ttl: UInt64 = 2 * 24 * 60 * 60 * 1000
 
     public enum Destination {
         case contact(publicKey: String)
@@ -11,12 +12,14 @@ public enum SendingPipeline {
     }
 
     public enum Error : LocalizedError {
+        case invalidMessage
         case protoConversionFailed
         case protoSerializationFailed
         case proofOfWorkCalculationFailed
 
         public var errorDescription: String? {
             switch self {
+            case .invalidMessage: return "Invalid message."
             case .protoConversionFailed: return "Couldn't convert message to proto."
             case .protoSerializationFailed: return "Couldn't serialize proto."
             case .proofOfWorkCalculationFailed: return "Proof of work calculation failed."
@@ -25,19 +28,18 @@ public enum SendingPipeline {
     }
 
     public static func send(_ message: Message, to destination: Destination) -> Promise<Void> {
+        guard message.isValidForSending else { return Promise(error: Error.invalidMessage) }
         guard let proto = message.toProto() else { return Promise(error: Error.protoConversionFailed) }
-        let data: Data
+        let plaintext: Data
         do {
-            data = try proto.serializedData()
+            plaintext = try proto.serializedData()
         } catch {
             SNLog("Couldn't serialize proto due to error: \(error).")
             return Promise(error: Error.protoSerializationFailed)
         }
-        // TODO: Encryption
-        // TODO: Validation
-        let recipient = ""
-        let base64EncodedData = data.base64EncodedString()
-        let ttl: UInt64 = 2 * 24 * 60 * 60 * 1000
+        let ciphertext = plaintext // TODO: Encryption
+        let recipient = message.recipient!
+        let base64EncodedData = ciphertext.base64EncodedString()
         guard let (timestamp, nonce) = ProofOfWork.calculate(ttl: ttl, publicKey: recipient, data: base64EncodedData) else {
             SNLog("Proof of work calculation failed.")
             return Promise(error: Error.proofOfWorkCalculationFailed)