Refactoring

cpp-server/.gitignore

@@ -0,0 +1,4 @@
+server
+.vscode
+build
+src/secret.h

cpp-server/Makefile

@@ -0,0 +1,35 @@
+# Compiler and flags
+CPPC = g++
+CPPC_FLAGS = -s -O3 -lasound -lcryptopp -Wall -Wextra 
+
+
+SRC_PATH := src
+OBJ_PATH := build/obj
+BIN_PATH := build/bin
+
+
+SRC_FILES := $(shell find $(SRC_PATH) -name '*.cpp')
+# Generate corresponding object file paths by replacing src/ with build/obj/
+OBJ_FILES := $(patsubst $(SRC_PATH)/%.cpp,$(OBJ_PATH)/%.o,$(SRC_FILES))
+
+
+all: make-build-dir $(BIN_PATH)/TabletPcControl-server
+
+
+make-build-dir:
+	mkdir -p $(OBJ_PATH)
+	mkdir -p $(BIN_PATH)
+
+
+$(BIN_PATH)/TabletPcControl-server: $(OBJ_FILES)
+	$(CPPC) $(CPPC_FLAGS) $^ -o $@
+
+
+$(OBJ_PATH)/%.o: $(SRC_PATH)/%.cpp
+	$(CPPC) $(CPPC_FLAGS) -c $< -o $@
+
+
+clean:
+	rm -fr build
+
+.PHONY: all clean

cpp-server/build.sh

@@ -0,0 +1,4 @@
+#!/bin/bash
+read -p "enter secret password: " SECRET
+echo "#define SECRET \"$SECRET\"" > src/secret.h
+make -j$(nproc)

cpp-server/src/alsa.cpp

@@ -0,0 +1,115 @@
+#include "helper_funcs.h"
+#include <alsa/asoundlib.h>
+#include <arpa/inet.h>
+#include <cerrno>
+#include <csignal>
+#include <cstdio>
+#include <cstdlib>
+#include <fcntl.h>
+#include <iostream>
+#include <netdb.h>
+#include <netinet/in.h>
+#include <sched.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <sys/uio.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+namespace alsa {
+int get_volume(const char *selem_name) {
+  long min, max, volume;
+  snd_mixer_t *handle;
+  snd_mixer_selem_id_t *sid;
+
+  // Open mixer
+  snd_mixer_open(&handle, 0);
+  snd_mixer_attach(handle,
+                   "default"); // Use "default" for the default sound card
+  snd_mixer_selem_register(handle, NULL, NULL);
+  snd_mixer_load(handle);
+
+  // Allocate and set mixer element ID
+  snd_mixer_selem_id_alloca(&sid);
+  snd_mixer_selem_id_set_name(sid, selem_name);
+
+  // Find the mixer element
+  snd_mixer_elem_t *elem = snd_mixer_find_selem(handle, sid);
+
+  int volume_percent;
+  if (elem) {
+    // Get the playback volume range
+    snd_mixer_selem_get_playback_volume_range(elem, &min, &max);
+
+    // Get the current playback volume for front left channel
+    snd_mixer_selem_get_playback_volume(elem, SND_MIXER_SCHN_FRONT_LEFT,
+                                        &volume);
+
+    // Calculate the volume percentage
+    volume_percent = (volume - min) * 100 / (max - min);
+
+  } else {
+    std::cerr << "Mixer element not found\n";
+    snd_mixer_close(handle);
+    safe_exit(ENODEV);
+  }
+
+  // Clean up
+  snd_mixer_close(handle);
+  return volume_percent;
+}
+
+void set_volume(const char *selem_name, long volume_percent) {
+  long min, max;
+  snd_mixer_t *handle;
+  snd_mixer_selem_id_t *sid;
+
+  // Open mixer
+  snd_mixer_open(&handle, 0);
+  snd_mixer_attach(handle, "default"); // Use "default" instead of hw:0
+  snd_mixer_selem_register(handle, NULL, NULL);
+  snd_mixer_load(handle);
+
+  // Allocate and set mixer element ID
+  snd_mixer_selem_id_alloca(&sid);
+  snd_mixer_selem_id_set_name(sid, selem_name);
+
+  // Find the mixer element
+  snd_mixer_elem_t *elem = snd_mixer_find_selem(handle, sid);
+
+  if (elem) {
+    // Get the playback volume range
+    snd_mixer_selem_get_playback_volume_range(elem, &min, &max);
+
+    // Calculate the new volume value
+    long volume = min + (volume_percent * (max - min) / 100);
+
+    // Set the playback volume
+    snd_mixer_selem_set_playback_volume_all(elem, volume);
+    printf("Volume set to %ld%%\n", volume_percent);
+  } else {
+    fprintf(stderr, "Mixer element not found\n");
+  }
+
+  // Clean up
+  snd_mixer_close(handle);
+}
+
+int main(int argc, char *argv[]) {
+  if (argc != 3) {
+    fprintf(stderr, "Usage: %s <selem_name> <volume_percent>\n", argv[0]);
+    return 1;
+  }
+
+  const char *selem_name = argv[1];
+  long volume_percent = atol(argv[2]);
+
+  set_volume(selem_name, volume_percent);
+
+  return 0;
+}
+} // namespace alsa

cpp-server/src/alsa.h

@@ -0,0 +1,4 @@
+namespace alsa {
+int get_volume(const char *selem_name);
+void set_volume(const char *selem_name, long volume_percent);
+} // namespace alsa

cpp-server/src/crypt.cpp

@@ -0,0 +1,38 @@
+#include <cryptopp/aes.h>
+#include <cryptopp/base64.h>
+#include <cryptopp/filters.h>
+#include <cryptopp/modes.h>
+#include <iomanip>
+#include <iostream>
+#include <string>
+
+int main() {
+  // Key and IV (Initialization Vector) for AES
+  CryptoPP::byte key[CryptoPP::AES::DEFAULT_KEYLENGTH] = {
+      'k', 'e', 'y', '1', '2', '3', '4', '5',
+      '6', '7', '8', '9', '1', '0', '1', '1'};
+  CryptoPP::byte iv[CryptoPP::AES::BLOCKSIZE] = {'i', 'v', '1', '2', '3', '4',
+                                                 '5', '6', '7', '8', '9', '1',
+                                                 '0', '1', '1', '1'};
+
+  // Message to be encrypted
+  std::string plainText = "Hello, AES!";
+  std::string cipherText; // Declare cipherText variable
+
+  // Encrypt using AES in CBC mode
+  CryptoPP::CBC_Mode<CryptoPP::AES>::Encryption encryptor(key, sizeof(key), iv);
+  CryptoPP::StringSource(plainText, true,
+                         new CryptoPP::StreamTransformationFilter(
+                             encryptor, new CryptoPP::StringSink(cipherText)));
+
+  // Encode the encrypted message in Base64 format
+  std::string base64Encoded;
+  CryptoPP::StringSource(
+      cipherText, true,
+      new CryptoPP::Base64Encoder(new CryptoPP::StringSink(base64Encoded)));
+
+  // Display the Base64 encoded encrypted message
+  std::cout << "Encrypted Text (Base64): " << base64Encoded << std::endl;
+
+  return 0;
+}

cpp-server/src/helper_funcs.cpp

@@ -0,0 +1,12 @@
+#include "main.h"
+#include <iostream>
+#include <unistd.h>
+void safe_exit(int code) {
+  try {
+    std::clog << "Exiting\n";
+
+    close(serverSocket);
+  } catch (...) {
+  }
+  exit(code);
+}

cpp-server/src/helper_funcs.h

@@ -0,0 +1 @@
+void safe_exit(int code);

cpp-server/src/main.cpp

@@ -0,0 +1,124 @@
+#include "alsa.h"
+#include "helper_funcs.h"
+#include "secret.h"
+#include <alsa/asoundlib.h>
+#include <arpa/inet.h>
+#include <cerrno>
+#include <csignal>
+#include <cstdint>
+#include <cstdio>
+#include <cstdlib>
+#include <fcntl.h>
+#include <iostream>
+#include <netdb.h>
+#include <netinet/in.h>
+#include <sched.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <string>
+#include <sys/socket.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <sys/uio.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#define PORT 54321
+
+int serverSocket;
+
+int main(int argc, char *argv[]) {
+
+  std::string SecretNumCode_s = "";
+  for (char ch : SECRET) {
+    uint num = ch - 'a' + 1; // Convert 'a' to 1, 'b' to 2, etc.
+    SecretNumCode_s.append(std::to_string(num));
+  }
+  const long SecretNumCode = std::stoi(SecretNumCode_s);
+
+  // signal handlers
+  signal(SIGTERM, safe_exit);
+  signal(SIGINT, safe_exit);
+  signal(SIGQUIT, safe_exit);
+  signal(SIGHUP, safe_exit);
+
+  // error signal handlers
+  signal(SIGSEGV, safe_exit);
+
+  // creating socket
+  serverSocket = socket(AF_INET, SOCK_STREAM, 0);
+
+  // specifying the address
+  sockaddr_in serverAddress;
+  serverAddress.sin_family = AF_INET;
+  serverAddress.sin_port = htons(PORT);
+  serverAddress.sin_addr.s_addr = INADDR_ANY;
+
+  // binding socket.
+  while (bind(serverSocket, (struct sockaddr *)&serverAddress,
+              sizeof(serverAddress)) != 0) {
+    std::cerr << "error binding socket retring\n";
+    sleep(2);
+  }
+
+  // listening to the assigned socket
+  listen(serverSocket, 5);
+
+accept_new_connection:
+  // accepting connection request
+  int clientSocket = accept(serverSocket, nullptr, nullptr);
+
+  pid_t pid;
+  pid = fork();
+
+  if (pid == -1) {
+    std::cerr << "Fork failed";
+    safe_exit(-1);
+
+  } else if (pid == 0) {
+    // child process
+    signal(SIGUSR1, exit);
+    char bufferSend[1024];
+    int volume_percent = INTMAX_MIN;
+    int volume_percent_old;
+    while (1) {
+      volume_percent_old = volume_percent;
+      volume_percent = alsa::get_volume("Master");
+      if (volume_percent != volume_percent_old) {
+      }
+      usleep(100000);
+      sprintf(bufferSend, "Volume: %d%%\n", alsa::get_volume("Master"));
+      if (send(clientSocket, bufferSend, strlen(bufferSend), 0) == -1) {
+        std::cerr << "send() returned an error code\n";
+        safe_exit(-1);
+      }
+      sleep(1);
+    }
+
+  } else {
+    // parent process
+    char bufferRecv[1024];
+    // recieving data
+    while (1) {
+      memset(&bufferRecv, 0, sizeof(bufferRecv));
+      int RecvRetVal = recv(clientSocket, bufferRecv, sizeof(bufferRecv), 0);
+      if (RecvRetVal > sizeof(bufferRecv) || RecvRetVal < 0) {
+        std::cerr << "recv() returned an error code\n";
+        safe_exit(RecvRetVal);
+      } else if (RecvRetVal == 0) {
+        // detect if client disconected
+        kill(pid, SIGUSR1);
+        close(clientSocket);
+        goto accept_new_connection;
+      }
+
+      std::cout << "Message from client: " << bufferRecv << std::endl;
+    }
+
+    // closing the socket.
+    close(serverSocket);
+  }
+
+  return 0;
+}

cpp-server/src/main.h

@@ -0,0 +1 @@
+extern int serverSocket;