rlogin.c

/*
 * Rlogin backend.
 */

#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
#include <ctype.h>

#include "putty.h"

#ifndef FALSE
#define FALSE 0
#endif
#ifndef TRUE
#define TRUE 1
#endif

#define RLOGIN_MAX_BACKLOG 4096

typedef struct rlogin_tag {
  const struct plug_function_table *fn;
  /* the above field _must_ be first in the structure */

  Socket s;
  int closed_on_socket_error;
  int bufsize;
  int firstbyte;
  int cansize;
  int term_width, term_height;
  void *frontend;

  Conf *conf;

  /* In case we need to read a username from the terminal before starting */
  prompts_t *prompt;
} * Rlogin;

static void rlogin_size(void *handle, int width, int height);

static void c_write(Rlogin rlogin, char *buf, int len)
{
  int backlog = from_backend(rlogin->frontend, 0, buf, len);
  sk_set_frozen(rlogin->s, backlog > RLOGIN_MAX_BACKLOG);
}

static void rlogin_log(Plug plug,
                       int type,
                       SockAddr addr,
                       int port,
                       const char *error_msg,
                       int error_code)
{
  Rlogin rlogin = (Rlogin)plug;
  backend_socket_log(rlogin->frontend,
                     type,
                     addr,
                     port,
                     error_msg,
                     error_code,
                     rlogin->conf,
                     !rlogin->firstbyte);
}

static void rlogin_closing(Plug plug,
                           const char *error_msg,
                           int error_code,
                           int calling_back)
{
  Rlogin rlogin = (Rlogin)plug;

  /*
   * We don't implement independent EOF in each direction for Telnet
   * connections; as soon as we get word that the remote side has
   * sent us EOF, we wind up the whole connection.
   */

  if (rlogin->s) {
    sk_close(rlogin->s);
    rlogin->s = NULL;
    if (error_msg)
      rlogin->closed_on_socket_error = TRUE;
    notify_remote_exit(rlogin->frontend);
  }
  if (error_msg) {
    /* A socket error has occurred. */
    logevent(rlogin->frontend, error_msg);
    connection_fatal(rlogin->frontend, "%s", error_msg);
  } /* Otherwise, the remote side closed the connection normally. */
}

static void rlogin_receive(Plug plug, int urgent, char *data, int len)
{
  Rlogin rlogin = (Rlogin)plug;
  if (urgent == 2) {
    char c;

    c = *data++;
    len--;
    if (c == '\x80') {
      rlogin->cansize = 1;
      rlogin_size(rlogin, rlogin->term_width, rlogin->term_height);
    }
    /*
     * We should flush everything (aka Telnet SYNCH) if we see
     * 0x02, and we should turn off and on _local_ flow control
     * on 0x10 and 0x20 respectively. I'm not convinced it's
     * worth it...
     */
  } else {
    /*
     * Main rlogin protocol. This is really simple: the first
     * byte is expected to be NULL and is ignored, and the rest
     * is printed.
     */
    if (rlogin->firstbyte) {
      if (data[0] == '\0') {
        data++;
        len--;
      }
      rlogin->firstbyte = 0;
    }
    if (len > 0)
      c_write(rlogin, data, len);
  }
}

static void rlogin_sent(Plug plug, int bufsize)
{
  Rlogin rlogin = (Rlogin)plug;
  rlogin->bufsize = bufsize;
}

static void rlogin_startup(Rlogin rlogin, const char *ruser)
{
  char z = 0;
  char *p;

  sk_write(rlogin->s, &z, 1);
  p = conf_get_str(rlogin->conf, CONF_localusername);
  sk_write(rlogin->s, p, strlen(p));
  sk_write(rlogin->s, &z, 1);
  sk_write(rlogin->s, ruser, strlen(ruser));
  sk_write(rlogin->s, &z, 1);
  p = conf_get_str(rlogin->conf, CONF_termtype);
  sk_write(rlogin->s, p, strlen(p));
  sk_write(rlogin->s, "/", 1);
  p = conf_get_str(rlogin->conf, CONF_termspeed);
  sk_write(rlogin->s, p, strspn(p, "0123456789"));
  rlogin->bufsize = sk_write(rlogin->s, &z, 1);

  rlogin->prompt = NULL;
}

/*
 * Called to set up the rlogin connection.
 *
 * Returns an error message, or NULL on success.
 *
 * Also places the canonical host name into `realhost'. It must be
 * freed by the caller.
 */
static const char *rlogin_init(void *frontend_handle,
                               void **backend_handle,
                               Conf *conf,
                               const char *host,
                               int port,
                               char **realhost,
                               int nodelay,
                               int keepalive)
{
  static const struct plug_function_table fn_table = {
      rlogin_log, rlogin_closing, rlogin_receive, rlogin_sent};
  SockAddr addr;
  const char *err;
  Rlogin rlogin;
  char *ruser;
  int addressfamily;
  char *loghost;

  rlogin = snew(struct rlogin_tag);
  rlogin->fn = &fn_table;
  rlogin->s = NULL;
  rlogin->closed_on_socket_error = FALSE;
  rlogin->frontend = frontend_handle;
  rlogin->term_width = conf_get_int(conf, CONF_width);
  rlogin->term_height = conf_get_int(conf, CONF_height);
  rlogin->firstbyte = 1;
  rlogin->cansize = 0;
  rlogin->prompt = NULL;
  rlogin->conf = conf_copy(conf);
  *backend_handle = rlogin;

  addressfamily = conf_get_int(conf, CONF_addressfamily);
  /*
   * Try to find host.
   */
  addr = name_lookup(host,
                     port,
                     realhost,
                     conf,
                     addressfamily,
                     rlogin->frontend,
                     "rlogin connection");
  if ((err = sk_addr_error(addr)) != NULL) {
    sk_addr_free(addr);
    return err;
  }

  if (port < 0)
    port = 513; /* default rlogin port */

  /*
   * Open socket.
   */
  rlogin->s = new_connection(
      addr, *realhost, port, 1, 0, nodelay, keepalive, (Plug)rlogin, conf);
  if ((err = sk_socket_error(rlogin->s)) != NULL)
    return err;

  loghost = conf_get_str(conf, CONF_loghost);
  if (*loghost) {
    char *colon;

    sfree(*realhost);
    *realhost = dupstr(loghost);

    colon = host_strrchr(*realhost, ':');
    if (colon)
      *colon++ = '\0';
  }

  /*
   * Send local username, remote username, terminal type and
   * terminal speed - unless we don't have the remote username yet,
   * in which case we prompt for it and may end up deferring doing
   * anything else until the local prompt mechanism returns.
   */
  if ((ruser = get_remote_username(conf)) != NULL) {
    rlogin_startup(rlogin, ruser);
    sfree(ruser);
  } else {
    int ret;

    rlogin->prompt = new_prompts(rlogin->frontend);
    rlogin->prompt->to_server = TRUE;
    rlogin->prompt->name = dupstr("Rlogin login name");
    add_prompt(rlogin->prompt, dupstr("rlogin username: "), TRUE);
    ret = get_userpass_input(rlogin->prompt, NULL, 0);
    if (ret >= 0) {
      rlogin_startup(rlogin, rlogin->prompt->prompts[0]->result);
    }
  }

  return NULL;
}

static void rlogin_free(void *handle)
{
  Rlogin rlogin = (Rlogin)handle;

  if (rlogin->prompt)
    free_prompts(rlogin->prompt);
  if (rlogin->s)
    sk_close(rlogin->s);
  conf_free(rlogin->conf);
  sfree(rlogin);
}

/*
 * Stub routine (we don't have any need to reconfigure this backend).
 */
static void rlogin_reconfig(void *handle, Conf *conf)
{
}

/*
 * Called to send data down the rlogin connection.
 */
static int rlogin_send(void *handle, const char *buf, int len)
{
  Rlogin rlogin = (Rlogin)handle;

  if (rlogin->s == NULL)
    return 0;

  if (rlogin->prompt) {
    /*
     * We're still prompting for a username, and aren't talking
     * directly to the network connection yet.
     */
    int ret = get_userpass_input(rlogin->prompt, (unsigned char *)buf, len);
    if (ret >= 0) {
      rlogin_startup(rlogin, rlogin->prompt->prompts[0]->result);
      /* that nulls out rlogin->prompt, so then we'll start sending
       * data down the wire in the obvious way */
    }
  } else {
    rlogin->bufsize = sk_write(rlogin->s, buf, len);
  }

  return rlogin->bufsize;
}

/*
 * Called to query the current socket sendability status.
 */
static int rlogin_sendbuffer(void *handle)
{
  Rlogin rlogin = (Rlogin)handle;
  return rlogin->bufsize;
}

/*
 * Called to set the size of the window
 */
static void rlogin_size(void *handle, int width, int height)
{
  Rlogin rlogin = (Rlogin)handle;
  char b[12] = {'\xFF', '\xFF', 0x73, 0x73, 0, 0, 0, 0, 0, 0, 0, 0};

  rlogin->term_width = width;
  rlogin->term_height = height;

  if (rlogin->s == NULL || !rlogin->cansize)
    return;

  b[6] = rlogin->term_width >> 8;
  b[7] = rlogin->term_width & 0xFF;
  b[4] = rlogin->term_height >> 8;
  b[5] = rlogin->term_height & 0xFF;
  rlogin->bufsize = sk_write(rlogin->s, b, 12);
  return;
}

/*
 * Send rlogin special codes.
 */
static void rlogin_special(void *handle, Telnet_Special code)
{
  /* Do nothing! */
  return;
}

/*
 * Return a list of the special codes that make sense in this
 * protocol.
 */
static const struct telnet_special *rlogin_get_specials(void *handle)
{
  return NULL;
}

static int rlogin_connected(void *handle)
{
  Rlogin rlogin = (Rlogin)handle;
  return rlogin->s != NULL;
}

static int rlogin_sendok(void *handle)
{
  /* Rlogin rlogin = (Rlogin) handle; */
  return 1;
}

static void rlogin_unthrottle(void *handle, int backlog)
{
  Rlogin rlogin = (Rlogin)handle;
  sk_set_frozen(rlogin->s, backlog > RLOGIN_MAX_BACKLOG);
}

static int rlogin_ldisc(void *handle, int option)
{
  /* Rlogin rlogin = (Rlogin) handle; */
  return 0;
}

static void rlogin_provide_ldisc(void *handle, void *ldisc)
{
  /* This is a stub. */
}

static void rlogin_provide_logctx(void *handle, void *logctx)
{
  /* This is a stub. */
}

static int rlogin_exitcode(void *handle)
{
  Rlogin rlogin = (Rlogin)handle;
  if (rlogin->s != NULL)
    return -1; /* still connected */
  else if (rlogin->closed_on_socket_error)
    return INT_MAX; /* a socket error counts as an unclean exit */
  else
    /* If we ever implement RSH, we'll probably need to do this properly */
    return 0;
}

/*
 * cfg_info for rlogin does nothing at all.
 */
static int rlogin_cfg_info(void *handle)
{
  return 0;
}

Backend rlogin_backend = {rlogin_init,
                          rlogin_free,
                          rlogin_reconfig,
                          rlogin_send,
                          rlogin_sendbuffer,
                          rlogin_size,
                          rlogin_special,
                          rlogin_get_specials,
                          rlogin_connected,
                          rlogin_exitcode,
                          rlogin_sendok,
                          rlogin_ldisc,
                          rlogin_provide_ldisc,
                          rlogin_provide_logctx,
                          rlogin_unthrottle,
                          rlogin_cfg_info,
                          NULL /* test_for_upstream */,
                          "rlogin",
                          PROT_RLOGIN,
                          513};