134 lines
3.1 KiB
C
134 lines
3.1 KiB
C
#include "../../libs/communication/communication.h"
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#include "../../libs/protocol/protocol.h"
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#include <errno.h>
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#include <fcntl.h>
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#include <pwd.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <sys/stat.h>
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#include <sys/wait.h>
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#include <unistd.h>
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int main() {
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chdir("/djumbai/");
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if (chroot("/djumbai/") != 0) {
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perror("chroot /djumbai");
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return 1;
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}
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const char *send_fifo_path = "fifos/send_fifo";
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if (faccessat(AT_FDCWD,send_fifo_path, F_OK,AT_EACCESS) != -1) {
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// FIFO exists, delete it
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if (unlink(send_fifo_path) == -1) {
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perror("unlink");
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exit(EXIT_FAILURE);
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}
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printf("Existing FIFO deleted.\n");
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}
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// Open the FIFO for reading
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if (mkfifo(send_fifo_path, 0620) == -1) {
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perror("mkfifo");
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exit(EXIT_FAILURE);
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}
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int send_fifo_fd;
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send_fifo_fd = open(send_fifo_path, O_RDONLY);
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if (send_fifo_fd == -1) {
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if (errno == ENOENT) {
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// FIFO does not exist
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printf("FIFO '%s' does not exist. Exiting...\n", send_fifo_path);
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return 1;
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} else {
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perror("open");
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return 1;
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}
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}
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while (1) {
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// Read message from the send_fifo
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unsigned char buffer[MESSAGE_SIZE];
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read(send_fifo_fd, buffer, MESSAGE_SIZE);
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// Deserialize the message
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message msg;
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deserialize_message(buffer, MESSAGE_SIZE, &msg);
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int pipe_to_child[2];
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if (pipe(pipe_to_child) == -1) {
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perror("pipe");
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exit(EXIT_FAILURE);
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}
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pid_t pid = fork();
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if (pid == -1) {
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perror("fork");
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exit(EXIT_FAILURE);
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}
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if (pid == 0) { // Child process
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close(pipe_to_child[1]); // Close write end of pipe
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if (msg.header.isgroup) {
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// Message receiver is a group
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// Get the UID of the nobody user.
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const char *nobody_username = "nobody";
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struct passwd *pw = getpwnam(nobody_username);
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if (pw == NULL) {
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fprintf(stderr, "User %s not found\n", nobody_username);
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exit(EXIT_FAILURE);
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}
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// Set UID to nobody
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if (seteuid(pw->pw_uid) == -1) {
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perror("setuid");
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exit(EXIT_FAILURE);
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}
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// Set gid to receiver
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if (setegid(msg.header.receiver) == -1) {
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perror("setgid");
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exit(EXIT_FAILURE);
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}
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} else {
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// Message receiver is a user
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// Change UID receiver
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if (seteuid(msg.header.receiver) == -1) {
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perror("setuid");
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exit(EXIT_FAILURE);
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}
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struct passwd *pw = getpwuid(msg.header.receiver);
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if (pw == NULL) {
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fprintf(stderr, "User with uid %d not found\n", msg.header.receiver);
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exit(EXIT_FAILURE);
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}
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if (setegid(pw->pw_gid) == -1) {
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perror("setgid");
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exit(EXIT_FAILURE);
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}
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}
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// Redirect stdin to read from pipe_to_child
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dup2(pipe_to_child[0], STDIN_FILENO);
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execlp("./bin/djumbai_client_receive", "djumbai_client_receive", NULL);
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// If execlp fails
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perror("execlp");
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close(pipe_to_child[0]);
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exit(EXIT_FAILURE);
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} else { // Parent process
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close(pipe_to_child[0]); // Close read end of pipe
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write(pipe_to_child[1], buffer, sizeof(buffer));
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// Close the write end of the pipe
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close(pipe_to_child[1]);
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// Wait for the child process to finish
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wait(NULL);
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}
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}
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close(send_fifo_fd);
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unlink(send_fifo_path);
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}
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