fix

.gitignore

 # Project exclude paths
 cmake-build-debug
-.idea
\ No newline at end of file
+.idea
+.DS_Store

main.cpp

@@ -11,22 +11,19 @@
 #include <arpa/inet.h>
 #include <boost/program_options.hpp>
 
+#define decrypt_package encrypt_package
+
 namespace po = boost::program_options;
 
 in_addr_t remote;
-auto cipher = (unsigned char *) "Mathematics is the art of giving the same name to different things";
+auto cipher = (unsigned char *) "Mathematics is the art of giving the same name to different things.";
 
-void encrypt(unsigned char *buffer, size_t length) {
+void encrypt_package(unsigned char *buffer, size_t length) {
     for (auto i = 0; i < length; i++) {
         buffer[i] ^= cipher[i];
     }
 }
 
-void decrypt(unsigned char *buffer, size_t length) {
-    // xor decrypt is same as encrypt
-    encrypt(buffer, length);
-}
-
 // internet -> tun
 void inbound(int raw, int tun) {
     unsigned char buffer[ETH_DATA_LEN];
@@ -39,7 +36,7 @@ void inbound(int raw, int tun) {
         auto overhead = packet->ihl * 4;
         auto payload = buffer + overhead;
         auto payload_length = packet_length - overhead;
-        decrypt(payload, payload_length);
+        decrypt_package(payload, payload_length);
         if (write(tun, payload, payload_length) < 0) {
             perror("inbound write");
         }
@@ -54,7 +51,7 @@ void outbound(int raw, int tun) {
     address.sin_addr.s_addr = remote;
     size_t packet_length;
     while ((packet_length = read(tun, buffer, sizeof(buffer))) >= 0) {
-        encrypt(buffer, packet_length);
+        encrypt_package(buffer, packet_length);
         if (sendto(raw, buffer, packet_length, 0, (sockaddr *) &address, sizeof(address)) < 0) {
             perror("outbound write");
         }
@@ -66,9 +63,9 @@ int main(int argc, char *argv[]) {
 
     po::options_description desc("Allowed options");
     desc.add_options()
-            ("help", "produce help message")
+            ("help,h", "see how to use me elegantly")
             ("IP,i", po::value<std::string>(), "IP to connect")
-            ("dev,d", po::value<std::string>(), "tun device name")
+            ("dev,d", po::value<std::string>(), "tunnel device's name")
             ("postup,p", po::value<std::string>(), "post up script");
 
     po::variables_map args;