#include <stdbool.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdnoreturn.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <arpa/inet.h>
#include <signal.h>

noreturn void err(const char *fn) {
  perror(fn);
  exit(1);
}

void sigchld_handler(int signal) {
  int old_err = errno;
  errno = 0;
  while (errno != ECHILD) {
    int status;
    waitpid(-1, &status, 0);
  }
  errno = old_err;
}

int main() {
  signal(SIGCHLD, sigchld_handler);

  int sock = socket(AF_INET, SOCK_STREAM, 0);
  if (sock < 0) err("socket");

  struct sockaddr_in addr = {
    .sin_family = AF_INET,
    .sin_addr = {0},
    .sin_port = htons(7777),
  };

  int e = bind(sock, (struct sockaddr *)&addr, sizeof(addr));
  if (e < 0) err("bind");

  e = listen(sock, 1);
  if (e < 0) err("listen");

  while (true) {
    struct sockaddr_in recv = {0};
    socklen_t recv_len = sizeof(recv);

    int conn = accept(sock, (struct sockaddr *)&recv, &recv_len);
    if (conn < 0) err("accept");
    if (recv_len != sizeof(recv)) err("accept len");

    if (fork()) {
      close(conn);
    } else {
      dup2(conn, 0);
      dup2(conn, 1);

      execl("/opt/veronica/bin/ver-server-0.6b.pl", "/opt/veronica/bin/ver-server-0.6b.pl", (char *)NULL);
    }
  }
}