bird/nest/cli.c

/*
 *	BIRD Internet Routing Daemon -- Command-Line Interface
 *
 *	(c) 1999--2000 Martin Mares <mj@ucw.cz>
 *
 *	Can be freely distributed and used under the terms of the GNU GPL.
 */

/**
 * DOC: Command line interface
 *
 * This module takes care of the BIRD's command-line interface (CLI).
 * The CLI exists to provide a way to control BIRD remotely and to inspect
 * its status. It uses a very simple textual protocol over a stream
 * connection provided by the platform dependent code (on UNIX systems,
 * it's a UNIX domain socket).
 *
 * Each session of the CLI consists of a sequence of request and replies,
 * slightly resembling the FTP and SMTP protocols.
 * Requests are commands encoded as a single line of text, replies are
 * sequences of lines starting with a four-digit code followed by either
 * a space (if it's the last line of the reply) or a minus sign (when the
 * reply is going to continue with the next line), the rest of the line
 * contains a textual message semantics of which depends on the numeric
 * code. If a reply line has the same code as the previous one and it's
 * a continuation line, the whole prefix can be replaced by a single
 * white space character.
 *
 * Reply codes starting with 0 stand for `action successfully completed' messages,
 * 1 means `table entry', 8 `runtime error' and 9 `syntax error'.
 *
 * Each CLI session is internally represented by a &cli structure and a
 * resource pool containing all resources associated with the connection,
 * so that it can be easily freed whenever the connection gets closed, not depending
 * on the current state of command processing.
 *
 * The CLI commands are declared as a part of the configuration grammar
 * by using the |CF_CLI| macro. When a command is received, it is processed
 * by the same lexical analyzer and parser as used for the configuration, but
 * it's switched to a special mode by prepending a fake token to the text,
 * so that it uses only the CLI command rules. Then the parser invokes
 * an execution routine corresponding to the command, which either constructs
 * the whole reply and returns it back or (in case it expects the reply will be long)
 * it prints a partial reply and asks the CLI module (using the @cont hook)
 * to call it again when the output is transferred to the user.
 *
 * The @this_cli variable points to a &cli structure of the session being
 * currently parsed, but it's of course available only in command handlers
 * not entered using the @cont hook.
 *
 * TX buffer management works as follows: At cli.tx_buf there is a
 * list of TX buffers (struct cli_out), cli.tx_write is the buffer
 * currently used by the producer (cli_printf(), cli_alloc_out()) and
 * cli.tx_pos is the buffer currently used by the consumer
 * (cli_write(), in system dependent code). The producer uses
 * cli_out.wpos ptr as the current write position and the consumer
 * uses cli_out.outpos ptr as the current read position. When the
 * producer produces something, it calls cli_write_trigger(). If there
 * is not enough space in the current buffer, the producer allocates
 * the new one. When the consumer processes everything in the buffer
 * queue, it calls cli_written(), tha frees all buffers (except the
 * first one) and schedules cli.event .
 *
 */

#include "nest/bird.h"
#include "nest/cli.h"
#include "conf/conf.h"
#include "lib/string.h"

pool *cli_pool;

static byte *
cli_alloc_out(cli *c, int size)
{
  struct cli_out *o;

  if (!(o = c->tx_write) || o->wpos + size > o->end)
    {
      if (!o && c->tx_buf)
	o = c->tx_buf;
      else
	{
	  o = mb_alloc(c->pool, sizeof(struct cli_out) + CLI_TX_BUF_SIZE);
	  if (c->tx_write)
	    c->tx_write->next = o;
	  else
	    c->tx_buf = o;
	  o->wpos = o->outpos = o->buf;
	  o->end = o->buf + CLI_TX_BUF_SIZE;
	}
      c->tx_write = o;
      if (!c->tx_pos)
	c->tx_pos = o;
      o->next = NULL;
    }
  o->wpos += size;
  return o->wpos - size;
}

/**
 * cli_printf - send reply to a CLI connection
 * @c: CLI connection
 * @code: numeric code of the reply, negative for continuation lines
 * @msg: a printf()-like formatting string.
 *
 * This function send a single line of reply to a given CLI connection.
 * In works in all aspects like bsprintf() except that it automatically
 * prepends the reply line prefix.
 *
 * Please note that if the connection can be already busy sending some
 * data in which case cli_printf() stores the output to a temporary buffer,
 * so please avoid sending a large batch of replies without waiting
 * for the buffers to be flushed.
 *
 * If you want to write to the current CLI output, you can use the cli_msg()
 * macro instead.
 */
void
cli_printf(cli *c, int code, char *msg, ...)
{
  va_list args;
  byte buf[CLI_LINE_SIZE];
  int cd = code;
  int errcode;
  int size, cnt;

  if (cd < 0)
    {
      cd = -cd;
      if (cd == c->last_reply)
	size = bsprintf(buf, " ");
      else
	size = bsprintf(buf, "%04d-", cd);
      errcode = -8000;
    }
  else if (cd == CLI_ASYNC_CODE)
    {
      size = 1; buf[0] = '+';
      errcode = cd;
    }
  else
    {
      size = bsprintf(buf, "%04d ", cd);
      errcode = 8000;
      cd = 0;	/* Final message - no more continuation lines */
    }

  c->last_reply = cd;
  va_start(args, msg);
  cnt = bvsnprintf(buf+size, sizeof(buf)-size-1, msg, args);
  va_end(args);
  if (cnt < 0)
    {
      cli_printf(c, errcode, "<line overflow>");
      return;
    }
  size += cnt;
  buf[size++] = '\n';
  memcpy(cli_alloc_out(c, size), buf, size);
}

static void
cli_hello(cli *c)
{
  cli_printf(c, 1, "BIRD " BIRD_VERSION " ready.");
  c->cont = NULL;
}

static void
cli_free_out(cli *c)
{
  struct cli_out *o, *p;

  if (o = c->tx_buf)
    {
      o->wpos = o->outpos = o->buf;
      while (p = o->next)
	{
	  o->next = p->next;
	  mb_free(p);
	}
    }
  c->tx_write = c->tx_pos = NULL;
  c->async_msg_size = 0;
}

void
cli_written(cli *c)
{
  cli_free_out(c);
  ev_schedule(c->event);
}


static byte *cli_rh_pos;
static uint cli_rh_len;
static int cli_rh_trick_flag;
struct cli *this_cli;

static int
cli_cmd_read_hook(byte *buf, uint max, UNUSED int fd)
{
  if (!cli_rh_trick_flag)
    {
      cli_rh_trick_flag = 1;
      buf[0] = '!';
      return 1;
    }
  if (max > cli_rh_len)
    max = cli_rh_len;
  memcpy(buf, cli_rh_pos, max);
  cli_rh_pos += max;
  cli_rh_len -= max;
  return max;
}

static void
cli_command(struct cli *c)
{
  struct config f;
  int res;

  if (config->cli_debug > 1)
    log(L_TRACE "CLI: %s", c->rx_buf);
  bzero(&f, sizeof(f));
  f.mem = c->parser_pool;
  f.pool = rp_new(c->pool, the_bird_domain.the_bird, "Config");
  init_list(&f.symbols);
  cf_read_hook = cli_cmd_read_hook;
  cli_rh_pos = c->rx_buf;
  cli_rh_len = strlen(c->rx_buf);
  cli_rh_trick_flag = 0;
  this_cli = c;
  lp_flush(c->parser_pool);
  res = cli_parse(&f);
  if (!res)
    cli_printf(c, 9001, f.err_msg);

  config_free(&f);
}

static void
cli_event(void *data)
{
  cli *c = data;
  int err;

  if (c->tx_pos)
    ;
  else if (c->cont)
    c->cont(c);
  else
    {
      err = cli_get_command(c);
      if (!err)
	return;
      if (err < 0)
	cli_printf(c, 9000, "Command too long");
      else
	cli_command(c);
    }

  if (c->tx_pos)
    cli_write_trigger(c);
}

cli *
cli_new(struct birdsock *sock)
{
  pool *p = rp_new(cli_pool, the_bird_domain.the_bird, "CLI");
  cli *c = mb_alloc(p, sizeof(cli));

  bzero(c, sizeof(cli));
  c->pool = p;
  c->sock = sock;
  c->event = ev_new(p);
  c->event->hook = cli_event;
  c->event->data = c;
  c->cont = cli_hello;
  c->parser_pool = lp_new_default(c->pool);
  c->rx_buf = mb_alloc(c->pool, CLI_RX_BUF_SIZE);
  ev_schedule(c->event);
  return c;
}

void
cli_kick(cli *c)
{
  if (!c->cont && !c->tx_pos)
    ev_schedule(c->event);
}

static list cli_log_hooks;
static int cli_log_inited;

/* Hack for scheduled undo notification */
extern cli *cmd_reconfig_stored_cli;

void
cli_free(cli *c)
{
  int defer = 0;
  if (c->cleanup)
    defer = c->cleanup(c);
  if (c == cmd_reconfig_stored_cli)
    cmd_reconfig_stored_cli = NULL;

  if (defer)
  {
    sk_close(c->sock);
    c->sock = NULL;
  }
  else
    rp_free(c->pool);
}

/**
 * cli_init - initialize the CLI module
 *
 * This function is called during BIRD startup to initialize
 * the internal data structures of the CLI module.
 */
void
cli_init(void)
{
  cli_pool = rp_new(&root_pool, the_bird_domain.the_bird, "CLI");
  init_list(&cli_log_hooks);
  cli_log_inited = 1;
}