doorgo/door32.c

#include <netdb.h>
#include <netinet/in.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <termios.h>
#include <unistd.h>

// auto zombie reaping
#include <errno.h>
#include <signal.h>
#include <sys/wait.h>

void doprocessing(int sock);
char *cmds[10];

void set_raw(int fd) {
  struct termios tio_raw;
  tcgetattr(fd, &tio_raw);
  cfmakeraw(&tio_raw);
  tcsetattr(fd, TCSANOW, &tio_raw);
}

int drain(int fd) {
  struct timeval tv;
  fd_set set;
  int ret;
  char buffer[21];
  int total = 0;

  printf("draining... \n");

  do {
    FD_ZERO(&set);
    FD_SET(fd, &set);
    tv.tv_sec = 0;
    // 50,000 works for syncterm
    tv.tv_usec = 50000;

    ret = select(fd + 1, &set, NULL, NULL, &tv);
    if (ret == 1) {
      total += read(fd, buffer, 20);
    }
  } while (ret != 0);
  printf(" [%d]\n", total);
  return total;
}

int main(int argc, char *argv[]) {
  int sockfd, newsockfd, portno, clilen;
  char buffer[256];
  struct sockaddr_in serv_addr, cli_addr;
  int n, pid;

  // Automatically reap zombies.
  if (signal(SIGCHLD, SIG_IGN) == SIG_ERR) {
    perror(0);
    exit(1);
  }

  /* First call to socket() function */
  sockfd = socket(AF_INET, SOCK_STREAM, 0);

  if (sockfd < 0) {
    perror("ERROR opening socket");
    exit(1);
  }

  if (argc != 3) {
    printf("I need a listening port number, and command/door to call.\n");
    exit(2);
  }

  int listen_port = atoi(argv[1]);
  char *command = strdup(argv[2]);
  printf("Port %d Cmd [%s]\n", listen_port, command);

  char *cp;
  int cmd_count = 0;
  cp = command;
  cmds[cmd_count] = cp;
  cmd_count++;
  while (*cp != 0) {
    if (*cp == ' ') {
      *cp = 0;
      cp++;
      cmds[cmd_count] = cp;
      cmd_count++;
      continue;
    }
    cp++;
  }
  cmds[cmd_count] = (char *)NULL;

  if (listen_port == 0) {
    printf("I need a listening port number as a parameter.\n");
    exit(2);
  }

  /* Initialize socket structure */
  bzero((char *)&serv_addr, sizeof(serv_addr));
  portno = listen_port;

  serv_addr.sin_family = AF_INET;
  serv_addr.sin_addr.s_addr = INADDR_ANY;
  serv_addr.sin_port = htons(portno);

  int flag = 1;
  if (-1 == setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &flag, sizeof(flag))) {
    perror("setsockopt fail");
  }

  /* Now bind the host address using bind() call.*/
  if (bind(sockfd, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0) {
    perror("ERROR on binding");
    exit(1);
  }

  /* Now start listening for the clients, here
   * process will go in sleep mode and will wait
   * for the incoming connection
   */
  printf("Listening for connections on %d\n", listen_port);

  listen(sockfd, 5);
  clilen = sizeof(cli_addr);

  while (1) {
    newsockfd = accept(sockfd, (struct sockaddr *)&cli_addr, &clilen);

    if (newsockfd < 0) {
      perror("ERROR on accept");
      exit(1);
    }

    set_raw(newsockfd);

    /* Create child process */
    pid = fork();

    if (pid < 0) {
      perror("ERROR on fork");
      exit(1);
    }

    if (pid == 0) {
      /* This is the client process */
      close(sockfd);
      doprocessing(newsockfd);
      exit(0);
    } else {
      close(newsockfd);
    }

  } /* end of while */
  free((void *)command);
}

#define CRNL "\r\n"

void doprocessing(int sock) {
  int n;
  char buffer[256];
  // raw mode
  // set_raw(sock);
  /*
      std::string ayt = std::string((const char *)"\x00\xff\xfd\xf6", 4);
      std::string ayt_resp = std::string((const char *)"\xff\xfb\x00", 3);
      std::string ayt2 = std::string((const char *)"\xff\xfb\x00", 3);
      std::string ayt2_resp = std::string((const char *)"\xff\xfd\x00", 3);

  */
  // write(sock, "\x00\xff\xfd\xf6", 4);
  // write(sock, "\xff\xfb\x00", 3);

  /*
  https://www.rfc-editor.org/rfc/rfc658.html
  https://www.rfc-editor.org/rfc/rfc652.html
  https://www.iana.org/assignments/telnet-options/telnet-options.xhtml
  https://stackoverflow.com/questions/273261/force-telnet-client-into-character-mode
  https://www.omnisecu.com/tcpip/telnet-modes-of-operation.php
  https://www.omnisecu.com/tcpip/iac-interpret-as-command-telnet.php
  https://www.omnisecu.com/tcpip/telnet-negotiation.php
  https://stackoverflow.com/questions/10413963/telnet-iac-command-answering
  http://ryobbs.com/doku.php/terminal_iac
  https://www.omnisecu.com/tcpip/telnet-commands-and-options.php

   */
  write(sock, "\xff\xfb\x01", 3);
  // drain(sock);
  write(sock, "\xff\xfb\x03", 3);
  // drain(sock);
  write(sock, "\xff\xfd\x10", 3);
  // write(sock, "\xff\xfc\x22", 3);

  // syncterm is slow.  It needs time to drain.  :()

  drain(sock);
  // drain(sock);
  /*
  struct termios tio_raw;
  tcgetattr(sock, &tio_raw);
  cfmakeraw(&tio_raw);
  tcsetattr(sock, TCSANOW, &tio_raw);
  */

  // telnet client into character mode
  // sprintf(buffer, "\377\375\042\377\373\001Welcome socket %d\n\r", sock);
  sprintf(buffer, "Welcome socket %d" CRNL, sock);
  write(sock, buffer, strlen(buffer));

  // can I read the buffer until empty, maybe?

  FILE *fp;

  fp = fopen("door32.sys", "w");
  if (fp == NULL) {
    return;
  }

  fprintf(fp, "%d\n", 2);
  fprintf(fp, "%d\n", sock);
  fprintf(fp, "38400\n");
  fprintf(fp, "Fake Door32 BBS\n");
  fprintf(fp, "1\n");
  fprintf(fp, "%s\n%s\n", "Bugz Laundry", "Bugz");
  fprintf(fp, "%d\n", 100);
  fprintf(fp, "%d\n", 120);
  fprintf(fp, "1\n1\n");
  fclose(fp);

  // This resets the termios ??
  // execl("./testdoor", "testdoor", "-d", "door32.sys", (const char *)NULL);
  execv(cmds[0], cmds);

  // step1:  write out door32.sys file
  // exec / replace this with our door

  /*
  bzero(buffer,256);

  n = read(sock,buffer,255);

  if (n < 0) {
     perror("ERROR reading from socket");
     exit(1);
  }

  printf("Here is the message: %s\n",buffer);
  n = write(sock,"I got your message",18);

  if (n < 0) {
     perror("ERROR writing to socket");
     exit(1);
  }
  */
}