raw.c

/*
 * "Raw" backend.
 */

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

#include "putty.h"

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

#define RAW_MAX_BACKLOG 4096

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

  Socket s;
  int closed_on_socket_error;
  int bufsize;
  void *frontend;
  int sent_console_eof, sent_socket_eof, session_started;

  Conf *conf;
} * Raw;

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

static void c_write(Raw raw, char *buf, int len)
{
  int backlog = from_backend(raw->frontend, 0, buf, len);
  sk_set_frozen(raw->s, backlog > RAW_MAX_BACKLOG);
}

static void raw_log(Plug plug,
                    int type,
                    SockAddr addr,
                    int port,
                    const char *error_msg,
                    int error_code)
{
  Raw raw = (Raw)plug;
  backend_socket_log(raw->frontend,
                     type,
                     addr,
                     port,
                     error_msg,
                     error_code,
                     raw->conf,
                     raw->session_started);
}

static void raw_check_close(Raw raw)
{
  /*
   * Called after we send EOF on either the socket or the console.
   * Its job is to wind up the session once we have sent EOF on both.
   */
  if (raw->sent_console_eof && raw->sent_socket_eof) {
    if (raw->s) {
      sk_close(raw->s);
      raw->s = NULL;
      notify_remote_exit(raw->frontend);
    }
  }
}

static void raw_closing(Plug plug,
                        const char *error_msg,
                        int error_code,
                        int calling_back)
{
  Raw raw = (Raw)plug;

  if (error_msg) {
    /* A socket error has occurred. */
    if (raw->s) {
      sk_close(raw->s);
      raw->s = NULL;
      raw->closed_on_socket_error = TRUE;
      notify_remote_exit(raw->frontend);
    }
    logevent(raw->frontend, error_msg);
    connection_fatal(raw->frontend, "%s", error_msg);
  } else {
    /* Otherwise, the remote side closed the connection normally. */
    if (!raw->sent_console_eof && from_backend_eof(raw->frontend)) {
      /*
       * The front end wants us to close the outgoing side of the
       * connection as soon as we see EOF from the far end.
       */
      if (!raw->sent_socket_eof) {
        if (raw->s)
          sk_write_eof(raw->s);
        raw->sent_socket_eof = TRUE;
      }
    }
    raw->sent_console_eof = TRUE;
    raw_check_close(raw);
  }
}

static void raw_receive(Plug plug, int urgent, char *data, int len)
{
  Raw raw = (Raw)plug;
  c_write(raw, data, len);
  /* We count 'session start', for proxy logging purposes, as being
   * when data is received from the network and printed. */
  raw->session_started = TRUE;
}

static void raw_sent(Plug plug, int bufsize)
{
  Raw raw = (Raw)plug;
  raw->bufsize = bufsize;
}

/*
 * Called to set up the raw 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 *raw_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 = {
      raw_log, raw_closing, raw_receive, raw_sent};
  SockAddr addr;
  const char *err;
  Raw raw;
  int addressfamily;
  char *loghost;

  raw = snew(struct raw_backend_data);
  raw->fn = &fn_table;
  raw->s = NULL;
  raw->closed_on_socket_error = FALSE;
  *backend_handle = raw;
  raw->sent_console_eof = raw->sent_socket_eof = FALSE;
  raw->bufsize = 0;
  raw->session_started = FALSE;
  raw->conf = conf_copy(conf);

  raw->frontend = frontend_handle;

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

  if (port < 0)
    port = 23; /* default telnet port */

  /*
   * Open socket.
   */
  raw->s = new_connection(
      addr, *realhost, port, 0, 1, nodelay, keepalive, (Plug)raw, conf);
  if ((err = sk_socket_error(raw->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';
  }

  return NULL;
}

static void raw_free(void *handle)
{
  Raw raw = (Raw)handle;

  if (raw->s)
    sk_close(raw->s);
  conf_free(raw->conf);
  sfree(raw);
}

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

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

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

  raw->bufsize = sk_write(raw->s, buf, len);

  return raw->bufsize;
}

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

/*
 * Called to set the size of the window
 */
static void raw_size(void *handle, int width, int height)
{
  /* Do nothing! */
  return;
}

/*
 * Send raw special codes. We only handle outgoing EOF here.
 */
static void raw_special(void *handle, Telnet_Special code)
{
  Raw raw = (Raw)handle;
  if (code == TS_EOF && raw->s) {
    sk_write_eof(raw->s);
    raw->sent_socket_eof = TRUE;
    raw_check_close(raw);
  }

  return;
}

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

static int raw_connected(void *handle)
{
  Raw raw = (Raw)handle;
  return raw->s != NULL;
}

static int raw_sendok(void *handle)
{
  return 1;
}

static void raw_unthrottle(void *handle, int backlog)
{
  Raw raw = (Raw)handle;
  sk_set_frozen(raw->s, backlog > RAW_MAX_BACKLOG);
}

static int raw_ldisc(void *handle, int option)
{
  if (option == LD_EDIT || option == LD_ECHO)
    return 1;
  return 0;
}

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

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

static int raw_exitcode(void *handle)
{
  Raw raw = (Raw)handle;
  if (raw->s != NULL)
    return -1; /* still connected */
  else if (raw->closed_on_socket_error)
    return INT_MAX; /* a socket error counts as an unclean exit */
  else
    /* Exit codes are a meaningless concept in the Raw protocol */
    return 0;
}

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

Backend raw_backend = {raw_init,
                       raw_free,
                       raw_reconfig,
                       raw_send,
                       raw_sendbuffer,
                       raw_size,
                       raw_special,
                       raw_get_specials,
                       raw_connected,
                       raw_exitcode,
                       raw_sendok,
                       raw_ldisc,
                       raw_provide_ldisc,
                       raw_provide_logctx,
                       raw_unthrottle,
                       raw_cfg_info,
                       NULL /* test_for_upstream */,
                       "raw",
                       PROT_RAW,
                       0};