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/*
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 *        BIRD Internet Routing Daemon -- Command-Line Interface
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 *
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 *        (c) 1999--2000 Martin Mares <mj@ucw.cz>
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 *
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 *        Can be freely distributed and used under the terms of the GNU GPL.
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 */
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/**
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 * DOC: Command line interface
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 *
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 * This module takes care of the BIRD's command-line interface (CLI).
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 * The CLI exists to provide a way to control BIRD remotely and to inspect
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 * its status. It uses a very simple textual protocol over a stream
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 * connection provided by the platform dependent code (on UNIX systems,
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 * it's a UNIX domain socket).
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 *
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 * Each session of the CLI consists of a sequence of request and replies,
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 * slightly resembling the FTP and SMTP protocols.
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 * Requests are commands encoded as a single line of text, replies are
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 * sequences of lines starting with a four-digit code followed by either
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 * a space (if it's the last line of the reply) or a minus sign (when the
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 * reply is going to continue with the next line), the rest of the line
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 * contains a textual message semantics of which depends on the numeric
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 * code. If a reply line has the same code as the previous one and it's
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 * a continuation line, the whole prefix can be replaced by a single
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 * white space character.
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 *
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 * Reply codes starting with 0 stand for `action successfully completed' messages,
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 * 1 means `table entry', 8 `runtime error' and 9 `syntax error'.
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 *
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 * Each CLI session is internally represented by a &cli structure and a
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 * resource pool containing all resources associated with the connection,
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 * so that it can be easily freed whenever the connection gets closed, not depending
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 * on the current state of command processing.
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 *
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 * The CLI commands are declared as a part of the configuration grammar
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 * by using the |CF_CLI| macro. When a command is received, it is processed
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 * by the same lexical analyzer and parser as used for the configuration, but
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 * it's switched to a special mode by prepending a fake token to the text,
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 * so that it uses only the CLI command rules. Then the parser invokes
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 * an execution routine corresponding to the command, which either constructs
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 * the whole reply and returns it back or (in case it expects the reply will be long)
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 * it prints a partial reply and asks the CLI module (using the @cont hook)
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 * to call it again when the output is transferred to the user.
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 *
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 * The @this_cli variable points to a &cli structure of the session being
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 * currently parsed, but it's of course available only in command handlers
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 * not entered using the @cont hook.
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 *
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 * TX buffer management works as follows: At cli.tx_buf there is a
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 * list of TX buffers (struct cli_out), cli.tx_write is the buffer
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 * currently used by the producer (cli_printf(), cli_alloc_out()) and
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 * cli.tx_pos is the buffer currently used by the consumer
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 * (cli_write(), in system dependent code). The producer uses
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 * cli_out.wpos ptr as the current write position and the consumer
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 * uses cli_out.outpos ptr as the current read position. When the
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 * producer produces something, it calls cli_write_trigger(). If there
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 * is not enough space in the current buffer, the producer allocates
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 * the new one. When the consumer processes everything in the buffer
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 * queue, it calls cli_written(), tha frees all buffers (except the
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 * first one) and schedules cli.event .
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 * 
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 */
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#include "nest/bird.h"
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#include "nest/cli.h"
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#include "conf/conf.h"
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#include "lib/string.h"
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pool *cli_pool;
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static byte *
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cli_alloc_out(cli *c, int size)
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{
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  struct cli_out *o;
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  if (!(o = c->tx_write) || o->wpos + size > o->end)
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    {
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      if (!o && c->tx_buf)
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        o = c->tx_buf;
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      else
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        {
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          o = mb_alloc(c->pool, sizeof(struct cli_out) + CLI_TX_BUF_SIZE);
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          if (c->tx_write)
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            c->tx_write->next = o;
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          else
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            c->tx_buf = o;
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          o->wpos = o->outpos = o->buf;
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          o->end = o->buf + CLI_TX_BUF_SIZE;
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        }
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      c->tx_write = o;
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      if (!c->tx_pos)
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        c->tx_pos = o;
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      o->next = NULL;
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    }
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  o->wpos += size;
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  return o->wpos - size;
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}
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/**
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 * cli_printf - send reply to a CLI connection
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 * @c: CLI connection
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 * @code: numeric code of the reply, negative for continuation lines
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 * @msg: a printf()-like formatting string.
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 *
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 * This function send a single line of reply to a given CLI connection.
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 * In works in all aspects like bsprintf() except that it automatically
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 * prepends the reply line prefix.
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 *
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 * Please note that if the connection can be already busy sending some
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 * data in which case cli_printf() stores the output to a temporary buffer,
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 * so please avoid sending a large batch of replies without waiting
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 * for the buffers to be flushed.
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 *
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 * If you want to write to the current CLI output, you can use the cli_msg()
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 * macro instead.
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 */
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void
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cli_printf(cli *c, int code, char *msg, ...)
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{
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  va_list args;
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  byte buf[CLI_LINE_SIZE];
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  int cd = code;
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  int errcode;
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  int size, cnt;
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  if (cd < 0)
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    {
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      cd = -cd;
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      if (cd == c->last_reply)
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        size = bsprintf(buf, " ");
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      else
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        size = bsprintf(buf, "%04d-", cd);
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      errcode = -8000;
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    }
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  else if (cd == CLI_ASYNC_CODE)
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    {
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      size = 1; buf[0] = '+'; 
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      errcode = cd;
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    }
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  else
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    {
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      size = bsprintf(buf, "%04d ", cd);
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      errcode = 8000;
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    }
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  c->last_reply = cd;
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  va_start(args, msg);
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  cnt = bvsnprintf(buf+size, sizeof(buf)-size-1, msg, args);
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  va_end(args);
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  if (cnt < 0)
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    {
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      cli_printf(c, errcode, "<line overflow>");
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      return;
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    }
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  size += cnt;
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  buf[size++] = '\n';
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  memcpy(cli_alloc_out(c, size), buf, size);
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}
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static void
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cli_copy_message(cli *c)
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{
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  byte *p, *q;
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  uint cnt = 2;
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  if (c->ring_overflow)
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    {
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      byte buf[64];
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      int n = bsprintf(buf, "<%d messages lost>\n", c->ring_overflow);
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      c->ring_overflow = 0;
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      memcpy(cli_alloc_out(c, n), buf, n);
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    }
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  p = c->ring_read;
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  while (*p)
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    {
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      cnt++;
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      p++;
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      if (p == c->ring_end)
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        p = c->ring_buf;
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      ASSERT(p != c->ring_write);
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    }
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  c->async_msg_size += cnt;
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  q = cli_alloc_out(c, cnt);
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  *q++ = '+';
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  p = c->ring_read;
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  do
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    {
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      *q = *p++;
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      if (p == c->ring_end)
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        p = c->ring_buf;
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    }
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  while (*q++);
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  c->ring_read = p;
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  q[-1] = '\n';
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}
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static void
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cli_hello(cli *c)
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{
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  cli_printf(c, 1, "BIRD " BIRD_VERSION " ready.");
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  c->cont = NULL;
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}
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static void
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cli_free_out(cli *c)
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{
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  struct cli_out *o, *p;
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  if (o = c->tx_buf)
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    {
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      o->wpos = o->outpos = o->buf;
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      while (p = o->next)
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        {
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          o->next = p->next;
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          mb_free(p);
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        }
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    }
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  c->tx_write = c->tx_pos = NULL;
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  c->async_msg_size = 0;
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}
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void
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cli_written(cli *c)
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{
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  cli_free_out(c);
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  ev_schedule(c->event);
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}
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static byte *cli_rh_pos;
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static uint cli_rh_len;
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static int cli_rh_trick_flag;
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struct cli *this_cli;
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static int
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cli_cmd_read_hook(byte *buf, uint max, UNUSED int fd)
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{
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  if (!cli_rh_trick_flag)
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    {
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      cli_rh_trick_flag = 1;
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      buf[0] = '!';
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      return 1;
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    }
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  if (max > cli_rh_len)
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    max = cli_rh_len;
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  memcpy(buf, cli_rh_pos, max);
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  cli_rh_pos += max;
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  cli_rh_len -= max;
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  return max;
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}
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static void
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cli_command(struct cli *c)
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{
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  struct config f;
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  int res;
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  if (config->cli_debug > 1)
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    log(L_TRACE "CLI: %s", c->rx_buf);
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  bzero(&f, sizeof(f));
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  f.mem = c->parser_pool;
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  cf_read_hook = cli_cmd_read_hook;
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  cli_rh_pos = c->rx_buf;
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  cli_rh_len = strlen(c->rx_buf);
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  cli_rh_trick_flag = 0;
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  this_cli = c;
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  lp_flush(c->parser_pool);
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  res = cli_parse(&f);
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  if (!res)
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    cli_printf(c, 9001, f.err_msg);
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}
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static void
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cli_event(void *data)
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{
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  cli *c = data;
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  int err;
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  while (c->ring_read != c->ring_write &&
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      c->async_msg_size < CLI_MAX_ASYNC_QUEUE)
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    cli_copy_message(c);
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  if (c->tx_pos)
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    ;
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  else if (c->cont)
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    c->cont(c);
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  else
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    {
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      err = cli_get_command(c);
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      if (!err)
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        return;
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      if (err < 0)
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        cli_printf(c, 9000, "Command too long");
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      else
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        cli_command(c);
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    }
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  cli_write_trigger(c);
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}
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cli *
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cli_new(void *priv)
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{
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  pool *p = rp_new(cli_pool, "CLI");
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  cli *c = mb_alloc(p, sizeof(cli));
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  bzero(c, sizeof(cli));
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  c->pool = p;
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  c->priv = priv;
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  c->event = ev_new(p);
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  c->event->hook = cli_event;
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  c->event->data = c;
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  c->cont = cli_hello;
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  c->parser_pool = lp_new(c->pool, 4080);
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  c->show_pool = lp_new(c->pool, 4080);
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  c->rx_buf = mb_alloc(c->pool, CLI_RX_BUF_SIZE);
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  ev_schedule(c->event);
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  return c;
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}
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void
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cli_kick(cli *c)
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{
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  if (!c->cont && !c->tx_pos)
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    ev_schedule(c->event);
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}
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static list cli_log_hooks;
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static int cli_log_inited;
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void
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cli_set_log_echo(cli *c, uint mask, uint size)
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{
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  if (c->ring_buf)
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    {
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      mb_free(c->ring_buf);
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      c->ring_buf = c->ring_end = c->ring_read = c->ring_write = NULL;
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      rem_node(&c->n);
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    }
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  c->log_mask = mask;
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  if (mask && size)
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    {
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      c->ring_buf = mb_alloc(c->pool, size);
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      c->ring_end = c->ring_buf + size;
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      c->ring_read = c->ring_write = c->ring_buf;
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      add_tail(&cli_log_hooks, &c->n);
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      c->log_threshold = size / 8;
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    }
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  c->ring_overflow = 0;
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}
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void
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cli_echo(uint class, byte *msg)
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{
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  unsigned len, free, i, l;
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  cli *c;
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  byte *m;
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  if (!cli_log_inited || EMPTY_LIST(cli_log_hooks))
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    return;
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  len = strlen(msg) + 1;
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  WALK_LIST(c, cli_log_hooks)
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    {
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      if (!(c->log_mask & (1 << class)))
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        continue;
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      if (c->ring_read <= c->ring_write)
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        free = (c->ring_end - c->ring_buf) - (c->ring_write - c->ring_read + 1);
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      else
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        free = c->ring_read - c->ring_write - 1;
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      if ((len > free) ||
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          (free < c->log_threshold && class < (unsigned) L_INFO[0]))
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        {
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          c->ring_overflow++;
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          continue;
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        }
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      if (c->ring_read == c->ring_write)
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        ev_schedule(c->event);
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      m = msg;
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      l = len;
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      while (l)
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        {
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          if (c->ring_read <= c->ring_write)
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            i = c->ring_end - c->ring_write;
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          else
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            i = c->ring_read - c->ring_write;
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          if (i > l)
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            i = l;
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          memcpy(c->ring_write, m, i);
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          m += i;
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          l -= i;
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          c->ring_write += i;
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          if (c->ring_write == c->ring_end)
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            c->ring_write = c->ring_buf;
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        }
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    }
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}
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/* Hack for scheduled undo notification */
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extern cli *cmd_reconfig_stored_cli;
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void
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cli_free(cli *c)
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{
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  cli_set_log_echo(c, 0, 0);
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  if (c->cleanup)
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    c->cleanup(c);
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  if (c == cmd_reconfig_stored_cli)
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    cmd_reconfig_stored_cli = NULL;
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  rfree(c->pool);
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}
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/**
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 * cli_init - initialize the CLI module
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 *
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 * This function is called during BIRD startup to initialize
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 * the internal data structures of the CLI module.
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 */
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void
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cli_init(void)
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{
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  cli_pool = rp_new(&root_pool, "CLI");
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  init_list(&cli_log_hooks);
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  cli_log_inited = 1;
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}