Add Reverse fix for TCP and xorptrpos overflow fix for UDP

Sources/CTunnelKitOpenVPNProtocol/PacketStream.m

@@ -31,7 +31,7 @@ @implementation PacketStream
 
 + (void)xormask:(uint8_t *)dst src:(uint8_t *)src xorMask:(NSData *)xorMask length:(int)length
 {
-    if (((uint8_t *)(xorMask.bytes))[0] != 0) {
+    if (xorMask.length > 0) {
         for (int i = 0; i < length; ++i) {
             dst[i] = src[i] ^ ((uint8_t *)(xorMask.bytes))[i % xorMask.length];
         }
@@ -49,12 +49,19 @@ + (void)xorptrpos:(uint8_t *)dst src:(uint8_t *)src length:(int)length
 
 + (void)reverse:(uint8_t *)dst src:(uint8_t *)src length:(int)length
 {
+    int start = 1;
+    int end = length - 1;
     uint8_t temp = 0;
     dst[0] = src[0];
-    for (int i = 1; i < length/2; ++i) {
-        temp = dst[length - 1 - i];
-        dst[length - 1 - i] = src[i];
-        dst[i] = temp;
+    while (start < end) {
+        temp = src[start];
+        dst[start] = src[end];
+        dst[end] = temp;
+        start++;
+        end--;
+    }
+    if (start == end) {
+        dst[start] = src[start];
     }
 }
 

Sources/TunnelKitOpenVPNAppExtension/NEUDPLink.swift

@@ -63,7 +63,7 @@ class NEUDPLink: LinkInterface {
                 return
             }
             var packetsToUse: [Data]?
-            if let packets = packets, [UInt8](self.xorMask)[0] != 0 {
+            if let packets = packets, self.xorMethod != 0 {
                 packetsToUse = packets.map { packet in
                     self.xorPacket(packet: packet, mode: .read)
                 }
@@ -85,7 +85,7 @@ class NEUDPLink: LinkInterface {
 
     func writePackets(_ packets: [Data], completionHandler: ((Error?) -> Void)?) {
         var packetsToUse: [Data]
-        if [UInt8](xorMask)[0] != 0 {
+        if xorMethod != 0 {
             packetsToUse = packets.map { packet in
                 xorPacket(packet: packet, mode: .write)
             }
@@ -119,7 +119,7 @@ class NEUDPLink: LinkInterface {
     }
 
     private func xormask(packet: Data) -> Data {
-        if [UInt8](xorMask)[0] != 0 {
+        if xorMask.count == 0 {
             return packet
         }
         return Data(packet.enumerated().map { (index, byte) in
@@ -129,7 +129,7 @@ class NEUDPLink: LinkInterface {
 
     private func xorptrpos(packet: Data) -> Data {
         return Data(packet.enumerated().map { (index, byte) in
-            byte ^ UInt8((index + 1))
+            byte ^ UInt8(truncatingIfNeeded: index &+ 1)
         })
     }