Basic socket communication

sources/ui-socket.c

@@ -0,0 +1,104 @@
+#include "ui-socket.h"
+#include <errno.h>
+#include <pthread.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <unistd.h>
+
+static int socket_fd = -1;
+static pthread_mutex_t socket_mutex = PTHREAD_MUTEX_INITIALIZER;
+
+int init_ui_socket(const char *filename) {
+  struct sockaddr_un addr;
+  int fd;
+
+  if ((fd = socket(AF_UNIX, SOCK_STREAM, 0)) == -1) {
+    perror("socket");
+    return -1;
+  }
+
+  memset(&addr, 0, sizeof(addr));
+  addr.sun_family = AF_UNIX;
+  strncpy(addr.sun_path, filename, sizeof(addr.sun_path) - 1);
+
+  if (unlink(filename) == -1 && errno != ENOENT) {
+    perror("unlink");
+    close(fd);
+    return -1;
+  }
+
+  if (bind(fd, (struct sockaddr *)&addr, sizeof(addr)) == -1) {
+    perror("bind");
+    close(fd);
+    return -1;
+  }
+
+  if (listen(fd, 5) == -1) {
+    perror("listen");
+    close(fd);
+    return -1;
+  }
+
+  socket_fd = fd;
+  return 0;
+}
+
+int ask_access(const char *filename, struct process_info pi) {
+  int client_fd;
+  struct sockaddr_un client_addr;
+  socklen_t client_len = sizeof(client_addr);
+  char request[1024];
+  char response[4];
+  ssize_t bytes_sent, bytes_received;
+
+  // Accept a connection from the GUI
+  if ((client_fd = accept(socket_fd, (struct sockaddr *)&client_addr,
+                          &client_len)) == -1) {
+    perror("accept");
+    return -1;
+  }
+
+  // Construct the request message
+  snprintf(request, sizeof(request), "r%s;%d;%s;%d\0", filename, pi.PID,
+           pi.name, pi.UID);
+
+  // Lock the socket to ensure thread safety
+  pthread_mutex_lock(&socket_mutex);
+
+  // Send the request message to the GUI
+  bytes_sent = send(client_fd, request, strlen(request), 0);
+  if (bytes_sent == -1) {
+    perror("send");
+    pthread_mutex_unlock(&socket_mutex);
+    close(client_fd);
+    return -1;
+  }
+
+  // Receive the response from the GUI
+  bytes_received = recv(client_fd, response, sizeof(response) - 1, 0);
+  if (bytes_received == -1) {
+    perror("recv");
+    pthread_mutex_unlock(&socket_mutex);
+    close(client_fd);
+    return -1;
+  }
+  response[bytes_received] = '\0';
+
+  // Unlock the socket
+  pthread_mutex_unlock(&socket_mutex);
+
+  // Close the client socket
+  close(client_fd);
+
+  // Check the response
+  if (response[0] == 'a' && response[1] == 'y' && response[2] == '\0') {
+    return 0; // Access granted
+  } else if (response[0] == 'a' && response[1] == 'n' && response[2] == '\0') {
+    return 1; // Access denied
+  } else {
+    // fprintf(stderr, "Invalid response from GUI: %s\n", response);
+    return -1; // Invalid response
+  }
+}

sources/ui-socket.h

@@ -6,14 +6,19 @@
 #ifndef UI_SOCKET_H
 #define UI_SOCKET_H
 
+#include <sys/types.h>
+
 struct process_info {
-  // TODO: define some fields
+  pid_t PID;
+  const char *name;
+  uid_t UID;
 };
 
-int init_ui_socket();
+// For default socket location, set socket_path = NULL.
+int init_ui_socket(const char *socket_path);
 
 // TODO: design an interface for asking user for permission.
 
-int ask_access(const char *filename, process_info pi);
+int ask_access(const char *filename, struct process_info pi);
 
 #endif // !UI_SOCKET_H