tor/src/or/control.c

/* Copyright 2004-2005 Roger Dingledine, Nick Mathewson. */
/* See LICENSE for licensing information */
/* $Id$ */
const char control_c_id[] = "$Id$";

/**
 * \file control.c
 * \brief Implementation for Tor's control-socket interface.
 **/

#include "or.h"

#define STATE_IS_OPEN(s) ((s) == CONTROL_CONN_STATE_OPEN_V0 ||       \
                          (s) == CONTROL_CONN_STATE_OPEN_V1)
#define STATE_IS_V0(s) ((s) == CONTROL_CONN_STATE_NEEDAUTH_V0 || \
                        (s) == CONTROL_CONN_STATE_OPEN_V0)

/*
 * See control-spec.txt and control-spec-v0.txt for full details on protocol(s).
 */

/* Recognized message type codes. */
#define CONTROL0_CMD_ERROR        0x0000
#define CONTROL0_CMD_DONE         0x0001
#define CONTROL0_CMD_SETCONF      0x0002
#define CONTROL0_CMD_GETCONF      0x0003
#define CONTROL0_CMD_CONFVALUE    0x0004
#define CONTROL0_CMD_SETEVENTS    0x0005
#define CONTROL0_CMD_EVENT        0x0006
#define CONTROL0_CMD_AUTHENTICATE 0x0007
#define CONTROL0_CMD_SAVECONF     0x0008
#define CONTROL0_CMD_SIGNAL       0x0009
#define CONTROL0_CMD_MAPADDRESS   0x000A
#define CONTROL0_CMD_GETINFO      0x000B
#define CONTROL0_CMD_INFOVALUE    0x000C
#define CONTROL0_CMD_EXTENDCIRCUIT  0x000D
#define CONTROL0_CMD_ATTACHSTREAM   0x000E
#define CONTROL0_CMD_POSTDESCRIPTOR 0x000F
#define CONTROL0_CMD_FRAGMENTHEADER 0x0010
#define CONTROL0_CMD_FRAGMENT       0x0011
#define CONTROL0_CMD_REDIRECTSTREAM 0x0012
#define CONTROL0_CMD_CLOSESTREAM    0x0013
#define CONTROL0_CMD_CLOSECIRCUIT   0x0014
#define _CONTROL0_CMD_MAX_RECOGNIZED 0x0014

/* Recognized error codes. */
#define ERR_UNSPECIFIED             0x0000
#define ERR_INTERNAL                0x0001
#define ERR_UNRECOGNIZED_TYPE       0x0002
#define ERR_SYNTAX                  0x0003
#define ERR_UNRECOGNIZED_CONFIG_KEY 0x0004
#define ERR_INVALID_CONFIG_VALUE    0x0005
#define ERR_UNRECOGNIZED_EVENT_CODE 0x0006
#define ERR_UNAUTHORIZED            0x0007
#define ERR_REJECTED_AUTHENTICATION 0x0008
#define ERR_RESOURCE_EXHAUSETED     0x0009
#define ERR_NO_STREAM               0x000A
#define ERR_NO_CIRC                 0x000B
#define ERR_NO_ROUTER               0x000C

/* Recognized asynchronous event types. */
#define _EVENT_MIN            0x0001
#define EVENT_CIRCUIT_STATUS  0x0001
#define EVENT_STREAM_STATUS   0x0002
#define EVENT_OR_CONN_STATUS  0x0003
#define EVENT_BANDWIDTH_USED  0x0004
#define EVENT_LOG_OBSOLETE    0x0005
#define EVENT_NEW_DESC        0x0006
#define EVENT_DEBUG_MSG       0x0007
#define EVENT_INFO_MSG        0x0008
#define EVENT_NOTICE_MSG      0x0009
#define EVENT_WARN_MSG        0x000A
#define EVENT_ERR_MSG         0x000B
#define EVENT_ADDRMAP         0x000C
#define _EVENT_MAX            0x000C

/** Array mapping from message type codes to human-readable message
 * type names. Used for compatibility with version 0 of the control
 * protocol. */
static const char * CONTROL0_COMMANDS[_CONTROL0_CMD_MAX_RECOGNIZED+1] = {
  "error",
  "done",
  "setconf",
  "getconf",
  "confvalue",
  "setevents",
  "events",
  "authenticate",
  "saveconf",
  "signal",
  "mapaddress",
  "getinfo",
  "infovalue",
  "extendcircuit",
  "attachstream",
  "postdescriptor",
  "fragmentheader",
  "fragment",
};

/** Bitfield: The bit 1&lt;&lt;e is set if <b>any</b> open control
 * connection is interested in events of type <b>e</b>.  We use this
 * so that we can decide to skip generating event messages that nobody
 * has interest in without having to walk over the global connection
 * list to find out.
 **/
static uint32_t global_event_mask0 = 0;
static uint32_t global_event_mask1 = 0;

/** True iff we have disabled log messages from being sent to the controller */
static int disable_log_messages = 0;

/** Macro: true if any control connection is interested in events of type
 * <b>e</b>. */
#define EVENT_IS_INTERESTING0(e) (global_event_mask0 & (1<<(e)))
#define EVENT_IS_INTERESTING1(e) (global_event_mask1 & (1<<(e)))
#define EVENT_IS_INTERESTING(e) \
  ((global_event_mask0|global_event_mask1) & (1<<(e)))

/** If we're using cookie-type authentication, how long should our cookies be?
 */
#define AUTHENTICATION_COOKIE_LEN 32

/** If true, we've set authentication_cookie to a secret code and
 * stored it to disk. */
static int authentication_cookie_is_set = 0;
static char authentication_cookie[AUTHENTICATION_COOKIE_LEN];

static void connection_printf_to_buf(connection_t *conn, const char *format, ...)
  CHECK_PRINTF(2,3);
/*static*/ size_t write_escaped_data(const char *data, size_t len,
                                     int translate_newlines, char **out);
/*static*/ size_t read_escaped_data(const char *data, size_t len,
                                    int translate_newlines,  char **out);
static void send_control0_message(connection_t *conn, uint16_t type,
                                 uint32_t len, const char *body);
static void send_control_done(connection_t *conn);
static void send_control_done2(connection_t *conn, const char *msg, size_t len);
static void send_control0_error(connection_t *conn, uint16_t error,
                               const char *message);
static void send_control0_event(uint16_t event, uint32_t len, const char *body);
static void send_control1_event(uint16_t event, const char *format, ...)
  CHECK_PRINTF(2,3);
static int handle_control_setconf(connection_t *conn, uint32_t len,
                                  char *body);
static int handle_control_resetconf(connection_t *conn, uint32_t len,
                                    char *body);
static int handle_control_getconf(connection_t *conn, uint32_t len,
                                  const char *body);
static int handle_control_setevents(connection_t *conn, uint32_t len,
                                    const char *body);
static int handle_control_authenticate(connection_t *conn, uint32_t len,
                                       const char *body);
static int handle_control_saveconf(connection_t *conn, uint32_t len,
                                   const char *body);
static int handle_control_signal(connection_t *conn, uint32_t len,
                                 const char *body);
static int handle_control_mapaddress(connection_t *conn, uint32_t len,
                                     const char *body);
static int handle_control_getinfo(connection_t *conn, uint32_t len,
                                  const char *body);
static int handle_control_extendcircuit(connection_t *conn, uint32_t len,
                                        const char *body);
static int handle_control_attachstream(connection_t *conn, uint32_t len,
                                        const char *body);
static int handle_control_postdescriptor(connection_t *conn, uint32_t len,
                                         const char *body);
static int handle_control_redirectstream(connection_t *conn, uint32_t len,
                                         const char *body);
static int handle_control_closestream(connection_t *conn, uint32_t len,
                                      const char *body);
static int handle_control_closecircuit(connection_t *conn, uint32_t len,
                                       const char *body);
static int write_stream_target_to_buf(connection_t *conn, char *buf, size_t len);

/** Given a possibly invalid message type code <b>cmd</b>, return a
 * human-readable string equivalent. */
static INLINE const char *
control_cmd_to_string(uint16_t cmd)
{
  return (cmd<=_CONTROL0_CMD_MAX_RECOGNIZED) ? CONTROL0_COMMANDS[cmd] : "Unknown";
}

static INLINE int
event_to_log_severity(int event)
{
  switch (event) {
    case EVENT_DEBUG_MSG: return LOG_DEBUG;
    case EVENT_INFO_MSG: return LOG_INFO;
    case EVENT_NOTICE_MSG: return LOG_NOTICE;
    case EVENT_WARN_MSG: return LOG_WARN;
    case EVENT_ERR_MSG: return LOG_ERR;
    default: return -1;
  }
}

/** DOCDOC */
static INLINE int
log_severity_to_event(int severity)
{
  switch (severity) {
    case LOG_DEBUG: return EVENT_DEBUG_MSG;
    case LOG_INFO: return EVENT_INFO_MSG;
    case LOG_NOTICE: return EVENT_NOTICE_MSG;
    case LOG_WARN: return EVENT_WARN_MSG;
    case LOG_ERR: return EVENT_ERR_MSG;
    default: return -1;
  }
}

/** Set <b>global_event_maskX</b> (where X is 0 or 1) to the bitwise OR
 * of each live control connection's event_mask field. */
void
control_update_global_event_mask(void)
{
  connection_t **conns;
  int n_conns, i;
  global_event_mask0 = 0;
  global_event_mask1 = 0;
  get_connection_array(&conns, &n_conns);
  for (i = 0; i < n_conns; ++i) {
    if (conns[i]->type == CONN_TYPE_CONTROL &&
        STATE_IS_OPEN(conns[i]->state)) {
      if (STATE_IS_V0(conns[i]->state))
        global_event_mask0 |= conns[i]->event_mask;
      else
        global_event_mask1 |= conns[i]->event_mask;
    }
  }

  control_adjust_event_log_severity();
}

/** DOCDOC */
void
control_adjust_event_log_severity(void)
{
  int i;
  int min_log_event=EVENT_ERR_MSG, max_log_event=EVENT_DEBUG_MSG;

  for (i = EVENT_DEBUG_MSG; i <= EVENT_ERR_MSG; ++i) {
    if (EVENT_IS_INTERESTING(i)) {
      min_log_event = i;
      break;
    }
  }
  for (i = EVENT_ERR_MSG; i >= EVENT_DEBUG_MSG; --i) {
    if (EVENT_IS_INTERESTING(i)) {
      max_log_event = i;
      break;
    }
  }
  if (EVENT_IS_INTERESTING(EVENT_LOG_OBSOLETE)) {
    if (min_log_event > EVENT_NOTICE_MSG)
      min_log_event = EVENT_NOTICE_MSG;
    if (max_log_event < EVENT_ERR_MSG)
      max_log_event = EVENT_ERR_MSG;
  }
  change_callback_log_severity(event_to_log_severity(min_log_event),
                               event_to_log_severity(max_log_event),
                               control_event_logmsg);
}

/** Append a NUL-terminated string <b>s</b> to the end of
 * <b>conn</b>-\>outbuf
 */
static INLINE void
connection_write_str_to_buf(const char *s, connection_t *conn)
{
  size_t len = strlen(s);
  connection_write_to_buf(s, len, conn);
}

/** Given a <b>len</b>-character string in <b>data</b>, made of lines
 * terminated by CRLF, allocate a new string in *<b>out</b>, and copy
 * the contents of <b>data</b> into *<b>out</b>, adding a period
 * before any period that that appears at the start of a line, and
 * adding a period-CRLF line at the end. If <b>translate_newlines</b>
 * is true, replace all LF characters sequences with CRLF.  Return the
 * number of bytes in *<b>out</b>.
 */
/* static */ size_t
write_escaped_data(const char *data, size_t len, int translate_newlines,
                   char **out)
{
  size_t sz_out = len+8;
  char *outp;
  const char *end;
  int i;
  int start_of_line;
  for (i=0; i<(int)len; ++i) {
    if (data[i]== '\n')
      ++sz_out;
  }
  *out = outp = tor_malloc(sz_out+1);
  end = data+len;
  start_of_line = 1;
  while (data < end) {
    if (*data == '\n') {
      if (translate_newlines)
        *outp++ = '\r';
      start_of_line = 1;
    } else if (*data == '.') {
      if (start_of_line) {
        start_of_line = 0;
        *outp++ = '.';
      }
    } else {
      start_of_line = 0;
    }
    *outp++ = *data++;
  }
  if (outp < *out+2 || memcmp(outp-2, "\r\n", 2)) {
    *outp++ = '\r';
    *outp++ = '\n';
  }
  *outp++ = '.';
  *outp++ = '\r';
  *outp++ = '\n';
  return outp - *out;
}

/** Given a <b>len</b>-character string in <b>data</b>, made of lines
 * terminated by CRLF, allocate a new string in *<b>out</b>, and copy
 * the contents of <b>data</b> into *<b>out</b>, removing any period
 * that appears at the start of a line.  If <b>translate_newlines</b>
 * is true, replace all CRLF sequences with LF.  Return the number of
 * bytes in *<b>out</b>. */
/*static*/ size_t
read_escaped_data(const char *data, size_t len, int translate_newlines,
                  char **out)
{
  char *outp;
  const char *next;
  const char *end;

  *out = outp = tor_malloc(len+1);

  end = data+len;

  while (data < end) {
    if (*data == '.')
      ++data;
    if (translate_newlines)
      next = tor_memmem(data, end-data, "\r\n", 2);
    else
      next = tor_memmem(data, end-data, "\r\n.", 3);
    if (next) {
      memcpy(outp, data, next-data);
      outp += (next-data);
      data = next+2;
    } else {
      memcpy(outp, data, end-data);
      outp += (end-data);
      *outp = '\0';
      return outp - *out;
    }
    if (translate_newlines) {
      *outp++ = '\n';
    } else {
      *outp++ = '\r';
      *outp++ = '\n';
    }
  }

  *outp = '\0';
  return outp - *out;
}

/** DOCDOC; test **/
static const char *
get_escaped_string(const char *start, size_t in_len_max,
                   char **out, size_t *out_len)
{
  const char *cp, *end;
  char *outp;
  size_t len=0;

  if (*start != '\"')
    return NULL;

  cp = start+1;
  end = start+in_len_max;

  /* Calculate length. */
  while (1) {
    if (cp >= end)
      return NULL;
    else if (*cp == '\\') {
      if (++cp == end)
        return NULL; /* Can't escape EOS. */
      ++cp;
      ++len;
    } else if (*cp == '\"') {
      break;
    } else {
      ++cp;
      ++len;
    }
  }
  end = cp;
  outp = *out = tor_malloc(len+1);
  *out_len = len;

  cp = start+1;
  while (cp < end) {
    if (*cp == '\\')
      ++cp;
    *outp++ = *cp++;
  }
  *outp = '\0';
  tor_assert((outp - *out) == (int)*out_len);

  return end+1;
}

/** Acts like sprintf, but writes its formatted string to the end of
 * <b>conn</b>-\>outbuf.  The message may be truncated if it is too long,
 * but it will always end with a CRLF sequence.
 */
static void
connection_printf_to_buf(connection_t *conn, const char *format, ...)
{
  va_list ap;
  char buf[1024];
  int r;
  size_t len;
  va_start(ap,format);
  r = tor_vsnprintf(buf, sizeof(buf), format, ap);
  va_end(ap);
  len = strlen(buf);
  if (memcmp("\r\n\0", buf+len-2, 3)) {
    buf[1023] = '\0';
    buf[1022] = '\n';
    buf[1021] = '\r';
  }
  connection_write_to_buf(buf, len, conn);
}

/** Send a message of type <b>type</b> containing <b>len</b> bytes
 * from <b>body</b> along the control connection <b>conn</b> */
static void
send_control0_message(connection_t *conn, uint16_t type, uint32_t len,
                     const char *body)
{
  char buf[10];
  tor_assert(conn);
  tor_assert(STATE_IS_V0(conn->state));
  tor_assert(len || !body);
  tor_assert(type <= _CONTROL0_CMD_MAX_RECOGNIZED);
  if (len < 65536) {
    set_uint16(buf, htons(len));
    set_uint16(buf+2, htons(type));
    connection_write_to_buf(buf, 4, conn);
    if (len)
      connection_write_to_buf(body, len, conn);
  } else {
    set_uint16(buf, htons(65535));
    set_uint16(buf+2, htons(CONTROL0_CMD_FRAGMENTHEADER));
    set_uint16(buf+4, htons(type));
    set_uint32(buf+6, htonl(len));
    connection_write_to_buf(buf, 10, conn);
    connection_write_to_buf(body, 65535-6, conn);
    len -= (65535-6);
    body += (65535-6);
    while (len) {
      size_t chunklen = (len<65535)?len:65535;
      set_uint16(buf, htons((uint16_t)chunklen));
      set_uint16(buf+2, htons(CONTROL0_CMD_FRAGMENT));
      connection_write_to_buf(buf, 4, conn);
      connection_write_to_buf(body, chunklen, conn);
      len -= chunklen;
      body += chunklen;
    }
  }
}

/** Send a "DONE" message down the control connection <b>conn</b> */
static void
send_control_done(connection_t *conn)
{
  if (STATE_IS_V0(conn->state)) {
    send_control0_message(conn, CONTROL0_CMD_DONE, 0, NULL);
  } else {
    connection_write_str_to_buf("250 OK\r\n", conn);
  }
}

/** DOCDOC */
static void
send_control_done2(connection_t *conn, const char *msg, size_t len)
{
  if (len==0)
    len = strlen(msg);
  send_control0_message(conn, CONTROL0_CMD_DONE, len, msg);
}

/** Send an error message with error code <b>error</b> and body
 * <b>message</b> down the connection <b>conn</b> */
static void
send_control0_error(connection_t *conn, uint16_t error, const char *message)
{
  char buf[256];
  size_t len;
  set_uint16(buf, htons(error));
  len = strlen(message);
  tor_assert(len < (256-2));
  memcpy(buf+2, message, len);
  send_control0_message(conn, CONTROL0_CMD_ERROR, (uint16_t)(len+2), buf);
}

/** Send an 'event' message of event type <b>event</b>, containing
 * <b>len</b> bytes in <b>body</b> to every control connection that
 * is interested in it. */
static void
send_control0_event(uint16_t event, uint32_t len, const char *body)
{
  connection_t **conns;
  int n_conns, i;
  size_t buflen;
  char *buf;

  tor_assert(event >= _EVENT_MIN && event <= _EVENT_MAX);

  buflen = len + 2;
  buf = tor_malloc_zero(buflen);
  set_uint16(buf, htons(event));
  memcpy(buf+2, body, len);

  get_connection_array(&conns, &n_conns);
  for (i = 0; i < n_conns; ++i) {
    if (conns[i]->type == CONN_TYPE_CONTROL &&
        !conns[i]->marked_for_close &&
        conns[i]->state == CONTROL_CONN_STATE_OPEN_V0 &&
        conns[i]->event_mask & (1<<event)) {
      send_control0_message(conns[i], CONTROL0_CMD_EVENT, buflen, buf);
      if (event == EVENT_ERR_MSG)
        _connection_controller_force_write(conns[i]);
    }
  }

  tor_free(buf);
}

/* DOCDOC */
static void
send_control1_event(uint16_t event, const char *format, ...)
{
  connection_t **conns;
  int n_conns, i, r;
  char buf[1024]; /* XXXX Length */
  va_list ap;
  size_t len;

  va_start(ap, format);
  r = tor_vsnprintf(buf, sizeof(buf), format, ap);
  va_end(ap);

  len = strlen(buf);
  if (memcmp("\r\n\0", buf+len-2, 3)) {
    buf[1023] = '\0';
    buf[1022] = '\n';
    buf[1021] = '\r';
  }

  tor_assert(event >= _EVENT_MIN && event <= _EVENT_MAX);

  get_connection_array(&conns, &n_conns);
  for (i = 0; i < n_conns; ++i) {
    if (conns[i]->type == CONN_TYPE_CONTROL &&
        !conns[i]->marked_for_close &&
        conns[i]->state == CONTROL_CONN_STATE_OPEN_V1 &&
        conns[i]->event_mask & (1<<event)) {
      connection_write_to_buf(buf, len, conns[i]);
      if (event == EVENT_ERR_MSG)
        _connection_controller_force_write(conns[i]);
    }
  }
}

static circuit_t *
get_circ(const char *id)
{
  unsigned long n_id;
  int ok;
  n_id = tor_parse_ulong(id, 10, 0, ULONG_MAX, &ok, NULL);
  if (!ok)
    return NULL;
  return circuit_get_by_global_id(n_id);
}

static connection_t *
get_stream(const char *id)
{
  unsigned long n_id;
  int ok;
  connection_t *conn;
  n_id = tor_parse_ulong(id, 10, 0, ULONG_MAX, &ok, NULL);
  if (!ok)
    return NULL;
  conn = connection_get_by_global_id(n_id);
  if (!conn || conn->type != CONN_TYPE_AP)
    return NULL;
  return conn;
}

/** Helper for setconf and resetconf. Acts like setconf, except
 * it passes <b>use_defaults</b> on to options_trial_assign().
 */
static int
control_setconf_helper(connection_t *conn, uint32_t len, char *body,
                       int use_defaults, int clear_first)
{
  int r;
  config_line_t *lines=NULL;
  char *start = body;
  int v0 = STATE_IS_V0(conn->state);

  if (!v0) {
    char *config = tor_malloc(len+1);
    char *outp = config;
    while (*body) {
      char *eq = body;
      while (!TOR_ISSPACE(*eq) && *eq != '=')
        ++eq;
      memcpy(outp, body, eq-body);
      outp += (eq-body);
      *outp++ = ' ';
      body = eq+1;
      if (*eq == '=') {
        if (*body != '\"') {
          while (!TOR_ISSPACE(*body))
            *outp++ = *body++;
        } else {
          char *val;
          size_t val_len;
          body = (char*)get_escaped_string(body, (len - (body-start)),
                                           &val, &val_len);
          if (!body) {
            connection_write_str_to_buf("551 Couldn't parse string\r\n", conn);
            tor_free(config);
            return 0;
          }
          memcpy(outp, val, val_len);
          outp += val_len;
          tor_free(val);
        }
      }
      while (TOR_ISSPACE(*body))
        ++body;
      *outp++ = '\n';
    }
    *outp = '\0';

    if (config_get_lines(config, &lines) < 0) {
      log_fn(LOG_WARN,"Controller gave us config lines we can't parse.");
      connection_write_str_to_buf("551 Couldn't parse configuration\r\n", conn);
      tor_free(config);
      return 0;
    }
    tor_free(config);
  } else {
    if (config_get_lines(body, &lines) < 0) {
      log_fn(LOG_WARN,"Controller gave us config lines we can't parse.");
      send_control0_error(conn, ERR_SYNTAX, "Couldn't parse configuration");
      return 0;
    }
  }

  if ((r=options_trial_assign(lines, use_defaults, clear_first)) < 0) {
    int v0_err;
    const char *msg;
    log_fn(LOG_WARN,"Controller gave us config lines that didn't validate.");
    switch (r) {
      case -1:
        v0_err = ERR_UNRECOGNIZED_CONFIG_KEY;
        msg = "Unrecognized option";
        break;
      case -2:
        v0_err = ERR_INVALID_CONFIG_VALUE;
        msg = "Unrecognized option value";
        break;
      case -3:
        v0_err = ERR_INVALID_CONFIG_VALUE;
        msg = "Transition not allowed";
        break;
      case -4:
      default:
        v0_err = ERR_INVALID_CONFIG_VALUE;
        msg = "Unable to set option";
        break;
    }
    if (v0) {
      send_control0_error(conn, v0_err, msg);
    } else {
      connection_printf_to_buf(conn, "552 %s\r\n", msg);
    }
    config_free_lines(lines);
    return 0;
  }
  config_free_lines(lines);
  send_control_done(conn);
  return 0;
}

/** Called when we receive a SETCONF message: parse the body and try
 * to update our configuration.  Reply with a DONE or ERROR message. */
static int
handle_control_setconf(connection_t *conn, uint32_t len, char *body)
{
  return control_setconf_helper(conn, len, body, 0, 1);
}

/** Called when we receive a RESETCONF message: parse the body and try
 * to update our configuration.  Reply with a DONE or ERROR message. */
static int
handle_control_resetconf(connection_t *conn, uint32_t len, char *body)
{
  int v0 = STATE_IS_V0(conn->state);
  tor_assert(!v0);
  return control_setconf_helper(conn, len, body, 1, 1);
}

/** Called when we receive a GETCONF message.  Parse the request, and
 * reply with a CONFVALUE or an ERROR message */
static int
handle_control_getconf(connection_t *conn, uint32_t body_len, const char *body)
{
  smartlist_t *questions = NULL;
  smartlist_t *answers = NULL;
  smartlist_t *unrecognized = NULL;
  char *msg = NULL;
  size_t msg_len;
  or_options_t *options = get_options();
  int v0 = STATE_IS_V0(conn->state);

  questions = smartlist_create();
  if (v0) {
    smartlist_split_string(questions, body, "\n",
                           SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, 0);
  } else {
    smartlist_split_string(questions, body, " ",
                           SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, 0);
  }
  answers = smartlist_create();
  unrecognized = smartlist_create();
  SMARTLIST_FOREACH(questions, char *, q,
  {
    if (!option_is_recognized(q)) {
      if (v0) {
        send_control0_error(conn, ERR_UNRECOGNIZED_CONFIG_KEY, q);
        goto done;
      } else {
        smartlist_add(unrecognized, q);
      }
    } else {
      config_line_t *answer = option_get_assignment(options,q);
      if (!v0 && !answer) {
        const char *name = option_get_canonical_name(q);
        size_t alen = strlen(name)+8;
        char *astr = tor_malloc(alen);
        tor_snprintf(astr, alen, "250-%s\r\n", name);
        smartlist_add(answers, astr);
      }

      while (answer) {
        config_line_t *next;
        size_t alen = strlen(answer->key)+strlen(answer->value)+8;
        char *astr = tor_malloc(alen);
        if (v0)
          tor_snprintf(astr, alen, "%s %s\n", answer->key, answer->value);
        else
          tor_snprintf(astr, alen, "250-%s=%s\r\n", answer->key, answer->value);
        smartlist_add(answers, astr);

        next = answer->next;
        tor_free(answer->key);
        tor_free(answer->value);
        tor_free(answer);
        answer = next;
      }
    }
  });

  if (v0) {
    msg = smartlist_join_strings(answers, "", 0, &msg_len);
    send_control0_message(conn, CONTROL0_CMD_CONFVALUE,
                          (uint16_t)msg_len, msg_len?msg:NULL);
  } else {
    int i,len;
    if ((len = smartlist_len(unrecognized))) {
      for (i=0; i < len-1; ++i)
        connection_printf_to_buf(conn,
                                 "552-Unrecognized configuration key \"%s\"\r\n",
                                 (char*)smartlist_get(unrecognized, i));
      connection_printf_to_buf(conn,
                               "552 Unrecognized configuration key \"%s\"\r\n",
                               (char*)smartlist_get(unrecognized, len-1));
    } else if ((len = smartlist_len(answers))) {
      char *tmp = smartlist_get(answers, len-1);
      tor_assert(strlen(tmp)>4);
      tmp[3] = ' ';
      msg = smartlist_join_strings(answers, "", 0, &msg_len);
      connection_write_to_buf(msg, msg_len, conn);
    } else {
      connection_write_str_to_buf("250 OK\r\n", conn);
    }
  }

 done:
  if (answers) SMARTLIST_FOREACH(answers, char *, cp, tor_free(cp));
  if (questions) SMARTLIST_FOREACH(questions, char *, cp, tor_free(cp));
  smartlist_free(answers);
  smartlist_free(questions);
  smartlist_free(unrecognized);
  tor_free(msg);

  return 0;
}

/** Called when we get a SETEVENTS message: update conn->event_mask,
 * and reply with DONE or ERROR. */
static int
handle_control_setevents(connection_t *conn, uint32_t len, const char *body)
{
  uint16_t event_code;
  uint32_t event_mask = 0;

  if (STATE_IS_V0(conn->state)) {
    if (len % 2) {
      send_control0_error(conn, ERR_SYNTAX,
                          "Odd number of bytes in setevents message");
      return 0;
    }

    for (; len; len -= 2, body += 2) {
      event_code = ntohs(get_uint16(body));
      if (event_code < _EVENT_MIN || event_code > _EVENT_MAX) {
        send_control0_error(conn, ERR_UNRECOGNIZED_EVENT_CODE,
                            "Unrecognized event code");
        return 0;
      }
      event_mask |= (1 << event_code);
    }
  } else {
    smartlist_t *events = smartlist_create();
    smartlist_split_string(events, body, " ",
                           SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, 0);
    SMARTLIST_FOREACH(events, const char *, ev,
      {
        if (!strcasecmp(ev, "CIRC"))
          event_code = EVENT_CIRCUIT_STATUS;
        else if (!strcasecmp(ev, "STREAM"))
          event_code = EVENT_STREAM_STATUS;
        else if (!strcasecmp(ev, "ORCONN"))
          event_code = EVENT_OR_CONN_STATUS;
        else if (!strcasecmp(ev, "BW"))
          event_code = EVENT_BANDWIDTH_USED;
        else if (!strcasecmp(ev, "DEBUG"))
          event_code = EVENT_DEBUG_MSG;
        else if (!strcasecmp(ev, "INFO"))
          event_code = EVENT_INFO_MSG;
        else if (!strcasecmp(ev, "NOTICE"))
          event_code = EVENT_NOTICE_MSG;
        else if (!strcasecmp(ev, "WARN"))
          event_code = EVENT_WARN_MSG;
        else if (!strcasecmp(ev, "ERR"))
          event_code = EVENT_ERR_MSG;
        else if (!strcasecmp(ev, "NEWDESC"))
          event_code = EVENT_NEW_DESC;
        else if (!strcasecmp(ev, "ADDRMAP"))
          event_code = EVENT_ADDRMAP;
        else {
          connection_printf_to_buf(conn, "552 Unrecognized event \"%s\"\r\n",
                                   ev);
          SMARTLIST_FOREACH(events, char *, e, tor_free(e));
          smartlist_free(events);
          return 0;
        }
        event_mask |= (1 << event_code);
      });
    SMARTLIST_FOREACH(events, char *, e, tor_free(e));
    smartlist_free(events);
  }
  conn->event_mask = event_mask;

  control_update_global_event_mask();
  send_control_done(conn);
  return 0;
}

/** Decode the hashed, base64'd password stored in <b>hashed</b>.  If
 * <b>buf</b> is provided, store the hashed password in the first
 * S2K_SPECIFIER_LEN+DIGEST_LEN bytes of <b>buf</b>.  Return 0 on
 * success, -1 on failure.
 */
int
decode_hashed_password(char *buf, const char *hashed)
{
  char decoded[64];
  if (!strcmpstart(hashed, "16:")) {
    if (base16_decode(decoded, sizeof(decoded), hashed+3, strlen(hashed+3))<0
        || strlen(hashed+3) != (S2K_SPECIFIER_LEN+DIGEST_LEN)*2) {
      return -1;
    }
  } else {
      if (base64_decode(decoded, sizeof(decoded), hashed, strlen(hashed))
          != S2K_SPECIFIER_LEN+DIGEST_LEN) {
        return -1;
      }
  }
  if (buf)
    memcpy(buf, decoded, S2K_SPECIFIER_LEN+DIGEST_LEN);
  return 0;
}

/** Called when we get an AUTHENTICATE message.  Check whether the
 * authentication is valid, and if so, update the connection's state to
 * OPEN.  Reply with DONE or ERROR.
 */
static int
handle_control_authenticate(connection_t *conn, uint32_t len, const char *body)
{
  or_options_t *options = get_options();
  char *password;
  size_t password_len;
  if (STATE_IS_V0(conn->state)) {
    password = (char*)body;
    password_len = len;
  } else {
    if (TOR_ISXDIGIT(body[0])) {
      int i = 0;
      while (TOR_ISXDIGIT(body[i]))
        ++i;
      password = tor_malloc(i/2 + 1);
      if (base16_decode(password, i/2+1, body, i)<0) {
        connection_write_str_to_buf("551 Invalid hexadecimal encoding\r\n", conn);
        tor_free(password);
        return 0;
      }
      password_len = i/2;
    } else if (TOR_ISSPACE(body[0])) {
      password = tor_strdup("");
      password_len = 0;
    } else {
      if (!get_escaped_string(body, len, &password, &password_len)) {
        connection_write_str_to_buf("551 Invalid quoted string\r\n", conn);
        return 0;
      }
    }
  }
  if (options->CookieAuthentication) {
    if (len == AUTHENTICATION_COOKIE_LEN &&
        !memcmp(authentication_cookie, password, password_len)) {
      goto ok;
    }
  } else if (options->HashedControlPassword) {
    char expected[S2K_SPECIFIER_LEN+DIGEST_LEN];
    char received[DIGEST_LEN];
    if (decode_hashed_password(expected, options->HashedControlPassword)<0) {
      log_fn(LOG_WARN,"Couldn't decode HashedControlPassword: invalid base64");
      goto err;
    }
    secret_to_key(received,DIGEST_LEN,password,password_len,expected);
    if (!memcmp(expected+S2K_SPECIFIER_LEN, received, DIGEST_LEN))
      goto ok;
    goto err;
  } else {
    /* if Tor doesn't demand any stronger authentication, then
     * the controller can get in with anything. */
    goto ok;
  }

 err:
  if (STATE_IS_V0(conn->state))
    send_control0_error(conn,ERR_REJECTED_AUTHENTICATION,"Authentication failed");
  else {
    tor_free(password);
    connection_write_str_to_buf("515 Authentication failed\r\n", conn);
  }
  return 0;
 ok:
  log_fn(LOG_INFO, "Authenticated control connection (%d)", conn->s);
  send_control_done(conn);
  if (STATE_IS_V0(conn->state))
    conn->state = CONTROL_CONN_STATE_OPEN_V0;
  else {
    conn->state = CONTROL_CONN_STATE_OPEN_V1;
    tor_free(password);
  }
  return 0;
}

/** DOCDOC */
static int
handle_control_saveconf(connection_t *conn, uint32_t len,
                        const char *body)
{
  if (options_save_current()<0) {
    if (STATE_IS_V0(conn->state))
      send_control0_error(conn, ERR_INTERNAL,
                          "Unable to write configuration to disk.");
    else
      connection_write_str_to_buf("551 Unable to write configuration to disk.",
                                  conn);
  } else {
    send_control_done(conn);
  }
  return 0;
}

/** DOCDOC */
static int
handle_control_signal(connection_t *conn, uint32_t len,
                      const char *body)
{
  int sig;
  if (STATE_IS_V0(conn->state)) {
    if (len != 1) {
      send_control0_error(conn, ERR_SYNTAX,
                          "Body of SIGNAL command too long or too short.");
      return 0;
    } else {
      sig = (uint8_t)body[0];
    }
  } else {
    int n = 0;
    char *s;
    while (body[n] && ! TOR_ISSPACE(body[n]))
      ++n;
    s = tor_strndup(body, n);
    if (!strcasecmp(s, "RELOAD") || !strcasecmp(s, "HUP"))
      sig = SIGHUP;
    else if (!strcasecmp(s, "SHUTDOWN") || !strcasecmp(s, "INT"))
      sig = SIGINT;
    else if (!strcasecmp(s, "DUMP") || !strcasecmp(s, "USR1"))
      sig = SIGUSR1;
    else if (!strcasecmp(s, "DEBUG") || !strcasecmp(s, "USR2"))
      sig = SIGUSR2;
    else if (!strcasecmp(s, "HALT") || !strcasecmp(s, "TERM"))
      sig = SIGTERM;
    else {
      connection_printf_to_buf(conn, "552 Unrecognized signal code \"%s\"\r\n",
                               body);
      sig = -1;
    }
    tor_free(s);
    if (sig<0)
      return 0;
  }

  if (control_signal_act(sig) < 0) {
    if (STATE_IS_V0(conn->state))
      send_control0_error(conn, ERR_SYNTAX, "Unrecognized signal number.");
    else
      connection_write_str_to_buf("551 Internal error acting on signal\r\n",
                                  conn);
  } else {
    send_control_done(conn);
  }
  return 0;
}

/** DOCDOC */
static int
handle_control_mapaddress(connection_t *conn, uint32_t len, const char *body)
{
  smartlist_t *elts;
  smartlist_t *lines;
  smartlist_t *reply;
  char *r;
  size_t sz;
  int v0 = STATE_IS_V0(conn->state);
  lines = smartlist_create();
  elts = smartlist_create();
  reply = smartlist_create();
  if (v0)
    smartlist_split_string(lines, body, "\n",
                           SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, 0);
  else
    smartlist_split_string(lines, body, " ",
                           SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, 0);
  /* XXXX Make errors conformant. */
  SMARTLIST_FOREACH(lines, char *, line,
  {
    tor_strlower(line);
    if (v0)
      smartlist_split_string(elts, line, " ", 0, 2);
    else
      smartlist_split_string(elts, line, "=", 0, 2);
    if (smartlist_len(elts) == 2) {
      const char *from = smartlist_get(elts,0);
      const char *to = smartlist_get(elts,1);
      if (!is_plausible_address(from)) {
        log_fn(LOG_WARN,"Skipping invalid argument '%s' in MapAddress msg",from);
      } else if (!is_plausible_address(to)) {
        log_fn(LOG_WARN,"Skipping invalid argument '%s' in MapAddress msg",to);
      } else if (!strcmp(from, ".") || !strcmp(from, "0.0.0.0")) {
        const char *addr = addressmap_register_virtual_address(
              !strcmp(from,".") ? RESOLVED_TYPE_HOSTNAME : RESOLVED_TYPE_IPV4,
               tor_strdup(to));
        if (!addr) {
          log_fn(LOG_WARN,
                 "Unable to allocate address for '%s' in MapAddress msg",
                 safe_str(line));
        } else {
          size_t anslen = strlen(addr)+strlen(to)+8;
          char *ans = tor_malloc(anslen);
          if (v0)
            tor_snprintf(ans, anslen, "%s %s", addr, to);
          else
            tor_snprintf(ans, anslen, "250-%s=%s", addr, to);
          smartlist_add(reply, ans);
        }
      } else {
        addressmap_register(from, tor_strdup(to), 1);
        if (v0)
          smartlist_add(reply, tor_strdup(line));
        else {
          size_t anslen = strlen(line)+8;
          char *ans = tor_malloc(anslen);
          tor_snprintf(ans, anslen, "250-%s", line);
          smartlist_add(reply, ans);
        }
      }
    } else {
      log_fn(LOG_WARN, "Skipping MapAddress line with wrong number of items.");
    }
    SMARTLIST_FOREACH(elts, char *, cp, tor_free(cp));
    smartlist_clear(elts);
  });
  SMARTLIST_FOREACH(lines, char *, cp, tor_free(cp));
  smartlist_free(lines);
  smartlist_free(elts);

  if (v0) {
    r = smartlist_join_strings(reply, "\n", 1, &sz);
    send_control_done2(conn,r,sz);
  } else {
    if (smartlist_len(reply))
      ((char*)smartlist_get(reply,smartlist_len(reply)-1))[3] = ' ';
    r = smartlist_join_strings(reply, "\r\n", 1, &sz);
    connection_write_to_buf(r, sz, conn);
  }

  SMARTLIST_FOREACH(reply, char *, cp, tor_free(cp));
  smartlist_free(reply);
  tor_free(r);
  return 0;
}

/** DOCDOC */
static char *
list_getinfo_options(void)
{
  return tor_strdup(
    "accounting/bytes Number of bytes read/written so far in interval.\n"
    "accounting/bytes-left Number of bytes left to read/write in interval.\n"
    "accounting/enabled Is accounting currently enabled?\n"
    "accounting/hibernating Are we hibernating or awake?\n"
    "accounting/interval-end Time when interval ends.\n"
    "accounting/interval-start Time when interval starts.\n"
    "accounting/interval-wake Time to wake up in this interval.\n"
    "addr-mappings/all All current remapped addresses.\n"
    "addr-mappings/cache Addresses remapped by DNS cache.\n"
    "addr-mappings/configl Addresses remapped from configuration options.\n"
    "addr-mappings/control Addresses remapped by a controller.\n"
    "circuit-status Status of each current circuit.\n"
    "config/names List of configuration options, types, and documentation.\n"
    "desc/id/* Server descriptor by hex ID\n"
    "desc/name/* Server descriptor by nickname.\n"
    "helper-nodes Which nodes will we use as helpers?\n"
    "info/names List of GETINFO options, types, and documentation.\n"
    "network-status List of hex IDs, nicknames, server statuses.\n"
    "orconn-status Status of each current OR connection.\n"
    "stream-status Status of each current application stream.\n"
    "version The current version of Tor.\n");
}

/** Lookup the 'getinfo' entry <b>question</b>, and return
 * the answer in <b>*answer</b> (or NULL if key not recognized).
 * Return 0 if success, or -1 if internal error. */
static int
handle_getinfo_helper(const char *question, char **answer)
{
  *answer = NULL; /* unrecognized key by default */
  if (!strcmp(question, "version")) {
    *answer = tor_strdup(VERSION);
  } else if (!strcmp(question, "config-file")) {
    *answer = tor_strdup(get_torrc_fname());
  } else if (!strcmpstart(question, "accounting/")) {
    return accounting_getinfo_helper(question, answer);
  } else if (!strcmpstart(question, "helper-nodes")) {
    return helper_nodes_getinfo_helper(question, answer);
  } else if (!strcmpstart(question, "config/")) {
    return config_getinfo_helper(question, answer);
  } else if (!strcmp(question, "info/names")) {
    *answer = list_getinfo_options();
  } else if (!strcmpstart(question, "desc/id/")) {
    routerinfo_t *ri = router_get_by_hexdigest(question+strlen("desc/id/"));
    if (ri && ri->signed_descriptor)
      *answer = tor_strdup(ri->signed_descriptor);
  } else if (!strcmpstart(question, "desc/name/")) {
    routerinfo_t *ri = router_get_by_nickname(question+strlen("desc/name/"));
    if (ri && ri->signed_descriptor)
      *answer = tor_strdup(ri->signed_descriptor);
  } else if (!strcmpstart(question, "unregistered-servers-")) {
    *answer = dirserver_getinfo_unregistered(question +
                                             strlen("unregistered-servers-"));
  } else if (!strcmp(question, "network-status")) {
    routerlist_t *routerlist;
    router_get_routerlist(&routerlist);
    if (!routerlist || !routerlist->routers ||
        list_server_status(routerlist->routers, answer) < 0) {
      return -1;
    }
  } else if (!strcmp(question, "circuit-status")) {
    circuit_t *circ;
    smartlist_t *status = smartlist_create();
    for (circ = _circuit_get_global_list(); circ; circ = circ->next) {
      char *s, *path;
      size_t slen;
      const char *state;
      if (! CIRCUIT_IS_ORIGIN(circ) || circ->marked_for_close)
        continue;
      path = circuit_list_path(circ,0);
      if (circ->state == CIRCUIT_STATE_OPEN)
        state = "BUILT";
      else if (strlen(path))
        state = "EXTENDED";
      else
        state = "LAUNCHED";

      slen = strlen(path)+strlen(state)+20;
      s = tor_malloc(slen+1);
      tor_snprintf(s, slen, "%lu %s %s", (unsigned long)circ->global_identifier,
                   state, path);
      smartlist_add(status, s);
      tor_free(path);
    }
    *answer = smartlist_join_strings(status, "\r\n", 0, NULL);
    SMARTLIST_FOREACH(status, char *, cp, tor_free(cp));
    smartlist_free(status);
  } else if (!strcmp(question, "stream-status")) {
    connection_t **conns;
    int n_conns, i;
    char buf[256];
    smartlist_t *status = smartlist_create();
    get_connection_array(&conns, &n_conns);
    for (i=0; i < n_conns; ++i) {
      const char *state;
      char *s;
      size_t slen;
      circuit_t *circ;
      if (conns[i]->type != CONN_TYPE_AP ||
          conns[i]->marked_for_close ||
          conns[i]->state == AP_CONN_STATE_SOCKS_WAIT)
        continue;
      switch (conns[i]->state)
        {
        case AP_CONN_STATE_CONTROLLER_WAIT:
        case AP_CONN_STATE_CIRCUIT_WAIT:
          if (conns[i]->socks_request &&
              conns[i]->socks_request->command == SOCKS_COMMAND_RESOLVE)
            state = "NEWRESOLVE";
          else
            state = "NEW";
          break;
        case AP_CONN_STATE_RENDDESC_WAIT:
        case AP_CONN_STATE_CONNECT_WAIT:
          state = "SENTCONNECT"; break;
        case AP_CONN_STATE_RESOLVE_WAIT:
          state = "SENTRESOLVE"; break;
        case AP_CONN_STATE_OPEN:
          state = "SUCCEEDED"; break;
        default:
          log_fn(LOG_WARN, "Asked for stream in unknown state %d",
                 conns[i]->state);
          continue;
        }
      circ = circuit_get_by_edge_conn(conns[i]);
      write_stream_target_to_buf(conns[i], buf, sizeof(buf));
      slen = strlen(buf)+strlen(state)+32;
      s = tor_malloc(slen+1);
      tor_snprintf(s, slen, "%lu %s %lu %s",
                   (unsigned long) conns[i]->global_identifier,state,
                   circ?(unsigned long)circ->global_identifier : 0ul,
                   buf);
      smartlist_add(status, s);
    }
    *answer = smartlist_join_strings(status, "\r\n", 0, NULL);
    SMARTLIST_FOREACH(status, char *, cp, tor_free(cp));
    smartlist_free(status);
  } else if (!strcmp(question, "orconn-status")) {
    connection_t **conns;
    int n_conns, i;
    smartlist_t *status = smartlist_create();
    get_connection_array(&conns, &n_conns);
    for (i=0; i < n_conns; ++i) {
      const char *state;
      char *s;
      size_t slen;
      if (conns[i]->type != CONN_TYPE_OR || conns[i]->marked_for_close)
        continue;
      if (conns[i]->state == OR_CONN_STATE_OPEN)
        state = "CONNECTED";
      else
        state = "LAUNCHED";
      slen = strlen(conns[i]->nickname)+strlen(state)+2;
      s = tor_malloc(slen+1);
      tor_snprintf(s, slen, "%s %s",conns[i]->nickname,state);
      smartlist_add(status, s);
    }
    *answer = smartlist_join_strings(status, "\r\n", 0, NULL);
    SMARTLIST_FOREACH(status, char *, cp, tor_free(cp));
    smartlist_free(status);
  } else if (!strcmpstart(question, "addr-mappings/")) {
    time_t min_e, max_e;
    smartlist_t *mappings;
    if (!strcmp(question, "addr-mappings/all")) {
      min_e = 0; max_e = TIME_MAX;
    } else if (!strcmp(question, "addr-mappings/cache")) {
      min_e = 2; max_e = TIME_MAX;
    } else if (!strcmp(question, "addr-mappings/config")) {
      min_e = 0; max_e = 0;
    } else if (!strcmp(question, "addr-mappings/control")) {
      min_e = 1; max_e = 1;
    } else {
      return 0;
    }
    mappings = smartlist_create();
    addressmap_get_mappings(mappings, min_e, max_e);
    *answer = smartlist_join_strings(mappings, "\n", 0, NULL);
    SMARTLIST_FOREACH(mappings, char *, cp, tor_free(cp));
    smartlist_free(mappings);
  }
  return 0;
}

/** DOCDOC */
static int
handle_control_getinfo(connection_t *conn, uint32_t len, const char *body)
{
  smartlist_t *questions = NULL;
  smartlist_t *answers = NULL;
  smartlist_t *unrecognized = NULL;
  char *msg = NULL, *ans = NULL;
  size_t msg_len;
  int v0 = STATE_IS_V0(conn->state);

  questions = smartlist_create();
  if (v0)
    smartlist_split_string(questions, body, "\n",
                           SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, 0);
  else
    smartlist_split_string(questions, body, " ",
                           SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, 0);
  answers = smartlist_create();
  unrecognized = smartlist_create();
  SMARTLIST_FOREACH(questions, const char *, q,
  {
    if (handle_getinfo_helper(q, &ans) < 0) {
      if (v0)
        send_control0_error(conn, ERR_INTERNAL, body);
      else
        connection_write_str_to_buf("551 Internal error\r\n", conn);
      goto done;
    }
    if (!ans) {
      if (v0) {
        send_control0_error(conn, ERR_UNRECOGNIZED_CONFIG_KEY, body);
        goto done;
      } else
        smartlist_add(unrecognized, (char*)q);
    } else {
      smartlist_add(answers, tor_strdup(q));
      smartlist_add(answers, ans);
    }
  });
  if (smartlist_len(unrecognized)) {
    int i;
    tor_assert(!v0);
    for (i=0; i < smartlist_len(unrecognized)-1; ++i)
      connection_printf_to_buf(conn,
                               "552-Unrecognized key \"%s\"\r\n",
                               (char*)smartlist_get(unrecognized, i));
    connection_printf_to_buf(conn,
                             "552 Unrecognized key \"%s\"\r\n",
                             (char*)smartlist_get(unrecognized, i));
    goto done;
  }

  if (v0) {
    msg = smartlist_join_strings2(answers, "\0", 1, 1, &msg_len);
    tor_assert(msg_len > 0); /* it will at least be terminated */
    send_control0_message(conn, CONTROL0_CMD_INFOVALUE,
                          msg_len, msg);
  } else if (smartlist_len(answers)) {
    int i;
    for (i = 0; i < smartlist_len(answers); i += 2) {
      char *k = smartlist_get(answers, i);
      char *v = smartlist_get(answers, i+1);
      /*XXXX Not an adequate test! XXXX011 */
      if (!strchr(v, '\n') && !strchr(v, '\r')) {
        connection_printf_to_buf(conn, "250-%s=", k);
        connection_write_str_to_buf(v, conn);
        connection_write_str_to_buf("\r\n", conn);
      } else {
        char *esc = NULL;
        size_t len;
        len = write_escaped_data(v, strlen(v), 1, &esc);
        connection_printf_to_buf(conn, "250+%s=\r\n", k);
        connection_write_to_buf(esc, len, conn);
        tor_free(esc);
      }
    }
    connection_write_str_to_buf("250 OK\r\n", conn);
  }

 done:
  if (answers) SMARTLIST_FOREACH(answers, char *, cp, tor_free(cp));
  if (questions) SMARTLIST_FOREACH(questions, char *, cp, tor_free(cp));
  smartlist_free(answers);
  smartlist_free(questions);
  smartlist_free(unrecognized);
  tor_free(msg);

  return 0;
}

/** DOCDOC */
static int
handle_control_extendcircuit(connection_t *conn, uint32_t len,
                             const char *body)
{
  smartlist_t *router_nicknames=NULL, *routers=NULL;
  uint32_t circ_id;
  circuit_t *circ = NULL;
  int zero_circ, v0;
  char reply[4];

  v0 = STATE_IS_V0(conn->state);
  router_nicknames = smartlist_create();

  if (v0) {
    if (len<5) {
      send_control0_error(conn, ERR_SYNTAX, "extendcircuit message too short");
      goto done;
    }
    smartlist_split_string(router_nicknames, body+4, ",", 0, 0);
    circ_id = ntohl(get_uint32(body));
    if (!circ_id) {
      /* start a new circuit */
      zero_circ = 1;
    } else {
      circ = circuit_get_by_global_id(circ_id);
      zero_circ = 0;
      if (!circ) {
        send_control0_error(conn, ERR_NO_CIRC,
                            "No circuit found with given ID");
        goto done;
      }
    }
  } else { /* v1 */
    smartlist_t *args;
    args = smartlist_create();
    smartlist_split_string(args, body, " ",
                           SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, 0);
    if (smartlist_len(args)<2)
      connection_printf_to_buf(conn,"512 Missing argument to EXTENDCIRCUIT\r\n");

    zero_circ = !strcmp("0", (char*)smartlist_get(args,0));
    if (!zero_circ && !(circ = get_circ(smartlist_get(args,0)))) {
      connection_printf_to_buf(conn, "552 Unknown circuit \"%s\"\r\n",
                               (char*)smartlist_get(args, 0));
    }
    smartlist_split_string(router_nicknames, smartlist_get(args,1), ",", 0, 0);

    SMARTLIST_FOREACH(args, char *, cp, tor_free(cp));
    smartlist_free(args);
    if (!zero_circ && !circ) {
      goto done;
    }
  }

  routers = smartlist_create();
  SMARTLIST_FOREACH(router_nicknames, const char *, n,
  {
    routerinfo_t *r = router_get_by_nickname(n);
    if (!r) {
      if (v0)
        send_control0_error(conn, ERR_NO_ROUTER, n);
      else
        connection_printf_to_buf(conn, "552 No such router \"%s\"\r\n", n);
      goto done;
    }
    smartlist_add(routers, r);
  });
  if (!smartlist_len(routers)) {
    if (v0)
      send_control0_error(conn, ERR_SYNTAX, "No router names provided");
    else
      connection_write_str_to_buf("512 No router names provided\r\n", conn);
    goto done;
  }

  if (zero_circ) {
    /* start a new circuit */
    circ = circuit_init(CIRCUIT_PURPOSE_C_GENERAL, 0, 0, 0);
  }

  /* now circ refers to something that is ready to be extended */
  SMARTLIST_FOREACH(routers, routerinfo_t *, r,
  {
    extend_info_t *info = extend_info_from_router(r);
    circuit_append_new_exit(circ, info);
    extend_info_free(info);
  });

  /* now that we've populated the cpath, start extending */
  if (zero_circ) {
    if (circuit_handle_first_hop(circ) < 0) {
      circuit_mark_for_close(circ);
      if (v0)
        send_control0_error(conn, ERR_INTERNAL, "couldn't start circuit");
      else
        connection_write_str_to_buf("551 Couldn't start circuit\r\n", conn);
      goto done;
    }
  } else {
    if (circ->state == CIRCUIT_STATE_OPEN) {
      circ->state = CIRCUIT_STATE_BUILDING;
      if (circuit_send_next_onion_skin(circ) < 0) {
        log_fn(LOG_INFO,"send_next_onion_skin failed; circuit marked for closing.");
        circuit_mark_for_close(circ);
        if (v0)
          send_control0_error(conn, ERR_INTERNAL, "couldn't send onion skin");
        else
          connection_write_str_to_buf("551 Couldn't send onion skinr\n", conn);
        goto done;
      }
    }
  }

  if (v0) {
    set_uint32(reply, htonl(circ->global_identifier));
    send_control_done2(conn, reply, sizeof(reply));
  } else {
    connection_printf_to_buf(conn, "250 EXTENDED %lu\r\n",
                             (unsigned long)circ->global_identifier);
  }
 done:
  SMARTLIST_FOREACH(router_nicknames, char *, n, tor_free(n));
  smartlist_free(router_nicknames);
  if (routers)
    smartlist_free(routers);
  return 0;
}

/** DOCDOC */
static int
handle_control_attachstream(connection_t *conn, uint32_t len,
                            const char *body)
{
  connection_t *ap_conn = NULL;
  circuit_t *circ = NULL;
  int zero_circ;

  if (STATE_IS_V0(conn->state)) {
    uint32_t conn_id;
    uint32_t circ_id;
    if (len < 8) {
      send_control0_error(conn, ERR_SYNTAX, "attachstream message too short");
      return 0;
    }

    conn_id = ntohl(get_uint32(body));
    circ_id = ntohl(get_uint32(body+4));
    zero_circ = circ_id == 0;

    if (!(ap_conn = connection_get_by_global_id(conn_id))) {
      send_control0_error(conn, ERR_NO_STREAM,
                          "No connection found with given ID");
      return 0;
    }
    if (circ_id && !(circ = circuit_get_by_global_id(circ_id))) {
      send_control0_error(conn, ERR_NO_CIRC, "No circuit found with given ID");
      return 0;
    }
  } else {
    smartlist_t *args;
    args = smartlist_create();
    smartlist_split_string(args, body, " ",
                           SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, 0);
    if (smartlist_len(args)<2)
      connection_printf_to_buf(conn,"512 Missing argument to ATTACHSTREAM\r\n");

    zero_circ = !strcmp("0", (char*)smartlist_get(args,1));

    if (!(ap_conn = get_stream(smartlist_get(args, 0)))) {
      connection_printf_to_buf(conn, "552 Unknown stream \"%s\"\r\n",
                               (char*)smartlist_get(args, 0));
    } else if (!zero_circ && !(circ = get_circ(smartlist_get(args, 1)))) {
      connection_printf_to_buf(conn, "552 Unknown circuit \"%s\"\r\n",
                               (char*)smartlist_get(args, 1));
    }
    SMARTLIST_FOREACH(args, char *, cp, tor_free(cp));
    smartlist_free(args);
    if (!ap_conn || (!zero_circ && !circ))
      return 0;
  }

  if (ap_conn->state != AP_CONN_STATE_CONTROLLER_WAIT) {
    if (STATE_IS_V0(conn->state)) {
      send_control0_error(conn, ERR_NO_STREAM,
                          "Connection is not managed by controller.");
    } else {
      connection_write_str_to_buf(
                              "555 Connection is not managed by controller.\r\n",
                                  conn);
    }
    return 0;
  }

  if (zero_circ) {
    ap_conn->state = AP_CONN_STATE_CIRCUIT_WAIT;
    if (connection_ap_handshake_attach_circuit(ap_conn)<0)
      connection_mark_unattached_ap(ap_conn, END_STREAM_REASON_CANT_ATTACH);
    send_control_done(conn);
    return 0;
  }
  if (circ->state != CIRCUIT_STATE_OPEN) {
    if (STATE_IS_V0(conn->state))
      send_control0_error(conn, ERR_INTERNAL, "Refuse to attach stream to non-open circ.");
    else
      connection_write_str_to_buf(
                              "551 Can't attach stream to non-open circuit\r\n",
                              conn);
    return 0;
  }
  if (connection_ap_handshake_attach_chosen_circuit(ap_conn, circ) != 1) {
    if (STATE_IS_V0(conn->state))
      send_control0_error(conn, ERR_INTERNAL, "Unable to attach stream.");
    else
      connection_write_str_to_buf("551 Unable to attach stream\r\n", conn);
    return 0;
  }
  send_control_done(conn);
  return 0;
}

/** DOCDOC */
static int
handle_control_postdescriptor(connection_t *conn, uint32_t len,
                              const char *body)
{
  char *desc;
  int v0 = STATE_IS_V0(conn->state);
  const char *msg=NULL;

  if (v0)
    desc = (char*)body;
  else {
    const char *cp = memchr(body, '\n', len);
    tor_assert(cp);
    read_escaped_data(cp, len-(cp-body), 1, &desc);
  }

  switch (router_load_single_router(desc, &msg)) {
  case -1:
    if (!msg) msg = "Could not parse descriptor";
    if (v0)
      send_control0_error(conn,ERR_SYNTAX,msg);
    else
      connection_printf_to_buf(conn, "554 %s\r\n", msg);
    break;
  case 0:
    if (!msg) msg = "Descriptor not added";
    if (v0)
      send_control_done2(conn,msg,0);
    else
      connection_printf_to_buf(conn, "251 %s\r\n",msg);
    break;
  case 1:
    send_control_done(conn);
    break;
  }

  if (!v0)
    tor_free(desc);
  return 0;
}

/** DOCDOC */
static int
handle_control_redirectstream(connection_t *conn, uint32_t len,
                              const char *body)
{
  connection_t *ap_conn = NULL;
  uint32_t conn_id;
  char *new_addr = NULL;
  if (STATE_IS_V0(conn->state)) {
    if (len < 6) {
      send_control0_error(conn, ERR_SYNTAX, "redirectstream message too short");
      return 0;
    }
    conn_id = ntohl(get_uint32(body));

    if (!(ap_conn = connection_get_by_global_id(conn_id))
        || ap_conn->state != CONN_TYPE_AP
        || !ap_conn->socks_request) {
      send_control0_error(conn, ERR_NO_STREAM,
                          "No AP connection found with given ID");
      return 0;
    }
    new_addr = tor_strdup(body+4);
  } else {
    smartlist_t *args;
    args = smartlist_create();
    smartlist_split_string(args, body, " ",
                           SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, 0);
    if (smartlist_len(args)<2)
      connection_printf_to_buf(conn,"512 Missing argument to REDIRECTSTREAM\r\n");
    else if (!(ap_conn = get_stream(smartlist_get(args, 0)))
             || !ap_conn->socks_request) {
      connection_printf_to_buf(conn, "552 Unknown stream \"%s\"\r\n",
                               (char*)smartlist_get(args, 0));
    } else {
      new_addr = tor_strdup(smartlist_get(args, 1));
    }

    SMARTLIST_FOREACH(args, char *, cp, tor_free(cp));
    smartlist_free(args);
    if (!new_addr)
      return 0;
  }

  strlcpy(ap_conn->socks_request->address, new_addr,
          sizeof(ap_conn->socks_request->address));
  tor_free(new_addr);
  send_control_done(conn);
  return 0;
}

/** DOCDOC */
static int
handle_control_closestream(connection_t *conn, uint32_t len,
                           const char *body)
{
  connection_t *ap_conn=NULL;
  uint8_t reason=0;

  if (STATE_IS_V0(conn->state)) {
    uint32_t conn_id;
    if (len < 6) {
      send_control0_error(conn, ERR_SYNTAX, "closestream message too short");
      return 0;
    }

    conn_id = ntohl(get_uint32(body));
    reason = *(uint8_t*)(body+4);

    if (!(ap_conn = connection_get_by_global_id(conn_id))
        || ap_conn->state != CONN_TYPE_AP
        || !ap_conn->socks_request) {
      send_control0_error(conn, ERR_NO_STREAM,
                          "No AP connection found with given ID");
      return 0;
    }
  } else {
    smartlist_t *args;
    int ok;
    args = smartlist_create();
    smartlist_split_string(args, body, " ",
                           SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, 0);
    if (smartlist_len(args)<2)
      connection_printf_to_buf(conn, "512 Missing argument to CLOSESTREAM\r\n");
    else if (!(ap_conn = get_stream(smartlist_get(args, 0))))
      connection_printf_to_buf(conn, "552 Unknown stream \"%s\"\r\n",
                               (char*)smartlist_get(args, 0));
    else {
      reason = (uint8_t) tor_parse_ulong(smartlist_get(args,1), 10, 0, 255,
                                         &ok, NULL);
      if (!ok) {
        connection_printf_to_buf(conn, "552 Unrecognized reason \"%s\"\r\n",
                                 (char*)smartlist_get(args, 1));
        ap_conn = NULL;
      }
    }
    SMARTLIST_FOREACH(args, char *, cp, tor_free(cp));
    smartlist_free(args);
    if (!ap_conn)
      return 0;
  }

  connection_mark_unattached_ap(ap_conn, reason);
  send_control_done(conn);
  return 0;
}

/** DOCDOC */
static int
handle_control_closecircuit(connection_t *conn, uint32_t len,
                            const char *body)
{
  circuit_t *circ = NULL;
  int safe = 0;

  if (STATE_IS_V0(conn->state)) {
    uint32_t circ_id;
    if (len < 5) {
      send_control0_error(conn, ERR_SYNTAX, "closecircuit message too short");
      return 0;
    }
    circ_id = ntohl(get_uint32(body));
    safe = (*(uint8_t*)(body+4)) & 1;

    if (!(circ = circuit_get_by_global_id(circ_id))) {
      send_control0_error(conn, ERR_NO_CIRC,
                          "No circuit found with given ID");
      return 0;
    }
  } else {
    smartlist_t *args;
    args = smartlist_create();
    smartlist_split_string(args, body, " ",
                           SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, 0);
    if (smartlist_len(args)<1)
      connection_printf_to_buf(conn, "512 Missing argument to CLOSECIRCUIT\r\n");
    else if (!(circ=get_circ(smartlist_get(args, 0))))
      connection_printf_to_buf(conn, "552 Unknown circuit \"%s\"\r\n",
                               (char*)smartlist_get(args, 0));
    else {
      int i;
      for (i=1; i < smartlist_len(args); ++i) {
        if (!strcasecmp(smartlist_get(args, i), "IfUnused"))
          safe = 1;
        else
          log_fn(LOG_INFO, "Skipping unknown option %s",
                 (char*)smartlist_get(args,i));
      }
    }
    SMARTLIST_FOREACH(args, char *, cp, tor_free(cp));
    smartlist_free(args);
    if (!circ)
      return 0;
  }

  if (!safe || !circ->p_streams) {
    circuit_mark_for_close(circ);
  }

  send_control_done(conn);
  return 0;
}

/** DOCDOC */
static int
handle_control_fragments(connection_t *conn, uint16_t command_type,
                         uint32_t body_len, char *body)
{
  if (command_type == CONTROL0_CMD_FRAGMENTHEADER) {
    if (conn->incoming_cmd) {
      log_fn(LOG_WARN, "Dropping incomplete fragmented command");
      tor_free(conn->incoming_cmd);
    }
    if (body_len < 6) {
      send_control0_error(conn, ERR_SYNTAX, "FRAGMENTHEADER too short.");
      return 0;
    }
    conn->incoming_cmd_type = ntohs(get_uint16(body));
    conn->incoming_cmd_len = ntohl(get_uint32(body+2));
    conn->incoming_cmd_cur_len = 0;
    conn->incoming_cmd = tor_malloc(conn->incoming_cmd_len);
    body += 6;
    body_len -= 6;
  } else if (command_type == CONTROL0_CMD_FRAGMENT) {
    if (!conn->incoming_cmd) {
      send_control0_error(conn, ERR_SYNTAX, "Out-of-place FRAGMENT");
      return 0;
    }
  } else {
    tor_assert(0);
  }

  if (conn->incoming_cmd_cur_len + body_len > conn->incoming_cmd_len) {
    tor_free(conn->incoming_cmd);
    send_control0_error(conn, ERR_SYNTAX,
                       "Fragmented data exceeds declared length");
    return 0;
  }
  memcpy(conn->incoming_cmd + conn->incoming_cmd_cur_len,
         body, body_len);
  conn->incoming_cmd_cur_len += body_len;
  return 0;
}

/** Called when <b>conn</b> has no more bytes left on its outbuf. */
int
connection_control_finished_flushing(connection_t *conn)
{
  tor_assert(conn);
  tor_assert(conn->type == CONN_TYPE_CONTROL);

  connection_stop_writing(conn);
  return 0;
}

/** Called when <b>conn</b> has gotten its socket closed. */
int
connection_control_reached_eof(connection_t *conn)
{
  tor_assert(conn);
  tor_assert(conn->type == CONN_TYPE_CONTROL);

  log_fn(LOG_INFO,"Control connection reached EOF. Closing.");
  connection_mark_for_close(conn);
  return 0;
}

/* DOCDOC */
static int
connection_control_process_inbuf_v1(connection_t *conn)
{
  size_t data_len;
  int cmd_len;
  char *args;

  tor_assert(conn);
  tor_assert(conn->type == CONN_TYPE_CONTROL);
  tor_assert(conn->state == CONTROL_CONN_STATE_OPEN_V1 ||
             conn->state == CONTROL_CONN_STATE_NEEDAUTH_V1);

  if (!conn->incoming_cmd) {
    conn->incoming_cmd = tor_malloc(1024);
    conn->incoming_cmd_len = 1024;
    conn->incoming_cmd_cur_len = 0;
  }

 again:
  while (1) {
    size_t last_idx;
    int r;
    /* First, fetch a line. */
    do {
      data_len = conn->incoming_cmd_len - conn->incoming_cmd_cur_len;
      r = fetch_from_buf_line(conn->inbuf,
                              conn->incoming_cmd+conn->incoming_cmd_cur_len,
                              &data_len);
      if (r == 0)
        /* Line not all here yet. Wait. */
        return 0;
      else if (r == -1) {
          while (conn->incoming_cmd_len < data_len+conn->incoming_cmd_cur_len)
            conn->incoming_cmd_len *= 2;
          conn->incoming_cmd = tor_realloc(conn->incoming_cmd,
                                           conn->incoming_cmd_len);
      }
    } while (r != 1);

    tor_assert(data_len);

    last_idx = conn->incoming_cmd_cur_len;
    conn->incoming_cmd_cur_len += data_len;

    /* We have appended a line to incoming_cmd.  Is the command done? */
    if (last_idx == 0 && *conn->incoming_cmd != '+')
      /* One line command, didn't start with '+'. */
      break;
    if (last_idx+3 == conn->incoming_cmd_cur_len &&
        !memcmp(conn->incoming_cmd + last_idx, ".\r\n", 3)) {
      /* Just appended ".\r\n"; we're done. Remove it. */
      conn->incoming_cmd_cur_len -= 3;
      break;
    }
    /* Otherwise, read another line. */
  }
  data_len = conn->incoming_cmd_cur_len;
  /* Okay, we now have a command sitting on conn->incoming_cmd. See if we
   * recognize it.
   */
  cmd_len = 0;
  while ((size_t)cmd_len < data_len
         && !TOR_ISSPACE(conn->incoming_cmd[cmd_len]))
    ++cmd_len;

  /*
  log_fn(LOG_NOTICE, "READ A COMMAND FROM THE BUFFER: <%s> [%d]",
         conn->incoming_cmd, (int)cmd_len);
  */
  data_len -= cmd_len;
  conn->incoming_cmd[cmd_len]='\0';
  args = conn->incoming_cmd+cmd_len+1;
  while (*args == ' ' || *args == '\t') {
    ++args;
    --data_len;
  }
  /*
  log_fn(LOG_NOTICE, "COMMAND IS: <%s>", conn->incoming_cmd);
  log_fn(LOG_NOTICE, "ARGS ARE: <%s>", args);
  */

  if (!strcasecmp(conn->incoming_cmd, "QUIT")) {
    connection_write_str_to_buf("250 closing connection\r\n", conn);
    connection_mark_for_close(conn);
    return 0;
  }

  if (conn->state == CONTROL_CONN_STATE_NEEDAUTH_V1 &&
      strcasecmp(conn->incoming_cmd, "AUTHENTICATE")) {
    connection_write_str_to_buf("514 Authentication required.\r\n", conn);
    conn->incoming_cmd_cur_len = 0;
    goto again;
  }

  if (!strcasecmp(conn->incoming_cmd, "SETCONF")) {
    if (handle_control_setconf(conn, data_len, args))
      return -1;
  } else if (!strcasecmp(conn->incoming_cmd, "RESETCONF")) {
    if (handle_control_resetconf(conn, data_len, args))
      return -1;
  } else if (!strcasecmp(conn->incoming_cmd, "GETCONF")) {
    if (handle_control_getconf(conn, data_len, args))
      return -1;
  } else if (!strcasecmp(conn->incoming_cmd, "SETEVENTS")) {
    if (handle_control_setevents(conn, data_len, args))
      return -1;
  } else if (!strcasecmp(conn->incoming_cmd, "AUTHENTICATE")) {
    if (handle_control_authenticate(conn, data_len, args))
      return -1;
  } else if (!strcasecmp(conn->incoming_cmd, "SAVECONF")) {
    if (handle_control_saveconf(conn, data_len, args))
      return -1;
  } else if (!strcasecmp(conn->incoming_cmd, "SIGNAL")) {
    if (handle_control_signal(conn, data_len, args))
      return -1;
  } else if (!strcasecmp(conn->incoming_cmd, "MAPADDRESS")) {
    if (handle_control_mapaddress(conn, data_len, args))
      return -1;
  } else if (!strcasecmp(conn->incoming_cmd, "GETINFO")) {
    if (handle_control_getinfo(conn, data_len, args))
      return -1;
  } else if (!strcasecmp(conn->incoming_cmd, "EXTENDCIRCUIT")) {
    if (handle_control_extendcircuit(conn, data_len, args))
      return -1;
  } else if (!strcasecmp(conn->incoming_cmd, "ATTACHSTREAM")) {
    if (handle_control_attachstream(conn, data_len, args))
      return -1;
  } else if (!strcasecmp(conn->incoming_cmd, "+POSTDESCRIPTOR")) {
    if (handle_control_postdescriptor(conn, data_len, args))
      return -1;
  } else if (!strcasecmp(conn->incoming_cmd, "REDIRECTSTREAM")) {
    if (handle_control_redirectstream(conn, data_len, args))
      return -1;
  } else if (!strcasecmp(conn->incoming_cmd, "CLOSESTREAM")) {
    if (handle_control_closestream(conn, data_len, args))
      return -1;
  } else if (!strcasecmp(conn->incoming_cmd, "CLOSECIRCUIT")) {
    if (handle_control_closecircuit(conn, data_len, args))
      return -1;
  } else {
    connection_printf_to_buf(conn, "510 Unrecognized command \"%s\"\r\n",
                             conn->incoming_cmd);
  }

  conn->incoming_cmd_cur_len = 0;
  goto again;
}

/* DOCDOC */
static int
connection_control_process_inbuf_v0(connection_t *conn)
{
  uint32_t body_len;
  uint16_t command_type;
  char *body=NULL;

 again:
  /* Try to suck a control message from the buffer. */
  switch (fetch_from_buf_control0(conn->inbuf, &body_len, &command_type, &body,
                                  conn->state == CONTROL_CONN_STATE_NEEDAUTH_V0))
    {
    case -2:
      tor_free(body);
      log_fn(LOG_INFO, "Detected v1 control protocol on connection (fd %d)",
             conn->s);
      conn->state = CONTROL_CONN_STATE_NEEDAUTH_V1;
      return connection_control_process_inbuf_v1(conn);
    case -1:
      tor_free(body);
      log_fn(LOG_WARN, "Error in control command. Failing.");
      return -1;
    case 0:
      /* Control command not all here yet. Wait. */
      return 0;
    case 1:
      /* We got a command. Process it. */
      break;
    default:
      tor_assert(0);
    }

  /* We got a command.  If we need authentication, only authentication
   * commands will be considered. */
  if (conn->state == CONTROL_CONN_STATE_NEEDAUTH_V0 &&
      command_type != CONTROL0_CMD_AUTHENTICATE) {
    log_fn(LOG_WARN, "Rejecting '%s' command; authentication needed.",
           control_cmd_to_string(command_type));
    send_control0_error(conn, ERR_UNAUTHORIZED, "Authentication required");
    tor_free(body);
    goto again;
  }

  if (command_type == CONTROL0_CMD_FRAGMENTHEADER ||
      command_type == CONTROL0_CMD_FRAGMENT) {
    if (handle_control_fragments(conn, command_type, body_len, body))
      return -1;
    tor_free(body);
    if (conn->incoming_cmd_cur_len != conn->incoming_cmd_len)
      goto again;

    command_type = conn->incoming_cmd_type;
    body_len = conn->incoming_cmd_len;
    body = conn->incoming_cmd;
    conn->incoming_cmd = NULL;
  } else if (conn->incoming_cmd) {
    log_fn(LOG_WARN, "Dropping incomplete fragmented command");
    tor_free(conn->incoming_cmd);
  }

  /* Okay, we're willing to process the command. */
  switch (command_type)
    {
    case CONTROL0_CMD_SETCONF:
      if (handle_control_setconf(conn, body_len, body))
        return -1;
      break;
    case CONTROL0_CMD_GETCONF:
      if (handle_control_getconf(conn, body_len, body))
        return -1;
      break;
    case CONTROL0_CMD_SETEVENTS:
      if (handle_control_setevents(conn, body_len, body))
        return -1;
      break;
    case CONTROL0_CMD_AUTHENTICATE:
      if (handle_control_authenticate(conn, body_len, body))
        return -1;
      break;
    case CONTROL0_CMD_SAVECONF:
      if (handle_control_saveconf(conn, body_len, body))
        return -1;
      break;
    case CONTROL0_CMD_SIGNAL:
      if (handle_control_signal(conn, body_len, body))
        return -1;
      break;
    case CONTROL0_CMD_MAPADDRESS:
      if (handle_control_mapaddress(conn, body_len, body))
        return -1;
      break;
    case CONTROL0_CMD_GETINFO:
      if (handle_control_getinfo(conn, body_len, body))
        return -1;
      break;
    case CONTROL0_CMD_EXTENDCIRCUIT:
      if (handle_control_extendcircuit(conn, body_len, body))
        return -1;
      break;
    case CONTROL0_CMD_ATTACHSTREAM:
      if (handle_control_attachstream(conn, body_len, body))
        return -1;
      break;
    case CONTROL0_CMD_POSTDESCRIPTOR:
      if (handle_control_postdescriptor(conn, body_len, body))
        return -1;
      break;
    case CONTROL0_CMD_REDIRECTSTREAM:
      if (handle_control_redirectstream(conn, body_len, body))
        return -1;
      break;
    case CONTROL0_CMD_CLOSESTREAM:
      if (handle_control_closestream(conn, body_len, body))
        return -1;
      break;
    case CONTROL0_CMD_CLOSECIRCUIT:
      if (handle_control_closecircuit(conn, body_len, body))
        return -1;
      break;
    case CONTROL0_CMD_ERROR:
    case CONTROL0_CMD_DONE:
    case CONTROL0_CMD_CONFVALUE:
    case CONTROL0_CMD_EVENT:
    case CONTROL0_CMD_INFOVALUE:
      log_fn(LOG_WARN, "Received client-only '%s' command; ignoring.",
             control_cmd_to_string(command_type));
      send_control0_error(conn, ERR_UNRECOGNIZED_TYPE,
                         "Command type only valid from server to tor client");
      break;
    case CONTROL0_CMD_FRAGMENTHEADER:
    case CONTROL0_CMD_FRAGMENT:
      log_fn(LOG_WARN, "Recieved command fragment out of order; ignoring.");
      send_control0_error(conn, ERR_SYNTAX, "Bad fragmentation on command.");
    default:
      log_fn(LOG_WARN, "Received unrecognized command type %d; ignoring.",
             (int)command_type);
      send_control0_error(conn, ERR_UNRECOGNIZED_TYPE,
                         "Unrecognized command type");
      break;
  }
  tor_free(body);
  goto again; /* There might be more data. */
}

/** Called when <b>conn</b> has received more bytes on its inbuf.
 */
int
connection_control_process_inbuf(connection_t *conn)
{
  tor_assert(conn);
  tor_assert(conn->type == CONN_TYPE_CONTROL);

  if (STATE_IS_V0(conn->state))
    return connection_control_process_inbuf_v0(conn);
  else
    return connection_control_process_inbuf_v1(conn);
}

/** Something has happened to circuit <b>circ</b>: tell any interested
 * control connections. */
int
control_event_circuit_status(circuit_t *circ, circuit_status_event_t tp)
{
  char *path, *msg;
  if (!EVENT_IS_INTERESTING(EVENT_CIRCUIT_STATUS))
    return 0;
  tor_assert(circ);
  tor_assert(CIRCUIT_IS_ORIGIN(circ));

  path = circuit_list_path(circ,0);
  if (EVENT_IS_INTERESTING0(EVENT_CIRCUIT_STATUS)) {
    size_t path_len = strlen(path);
    msg = tor_malloc(1+4+path_len+1); /* event, circid, path, NUL. */
    msg[0] = (uint8_t) tp;
    set_uint32(msg+1, htonl(circ->global_identifier));
    strlcpy(msg+5,path,path_len+1);

    send_control0_event(EVENT_CIRCUIT_STATUS, (uint32_t)(path_len+6), msg);
    tor_free(msg);
  }
  if (EVENT_IS_INTERESTING1(EVENT_CIRCUIT_STATUS)) {
    const char *status;
    switch (tp)
      {
      case CIRC_EVENT_LAUNCHED: status = "LAUNCHED"; break;
      case CIRC_EVENT_BUILT: status = "BUILT"; break;
      case CIRC_EVENT_EXTENDED: status = "EXTENDED"; break;
      case CIRC_EVENT_FAILED: status = "FAILED"; break;
      case CIRC_EVENT_CLOSED: status = "CLOSED"; break;
      default:
        log_fn(LOG_WARN, "Unrecognized status code %d", (int)tp);
        return 0;
      }
    send_control1_event(EVENT_CIRCUIT_STATUS,
                        "650 CIRC %lu %s %s\r\n",
                        (unsigned long)circ->global_identifier,
                        status, path);
  }
  tor_free(path);

  return 0;
}

/** DOCDOC */
static int
write_stream_target_to_buf(connection_t *conn, char *buf, size_t len)
{
  char buf2[256];
  if (conn->chosen_exit_name)
    if (tor_snprintf(buf2, sizeof(buf2), ".%s.exit", conn->chosen_exit_name)<0)
      return -1;
  if (tor_snprintf(buf, len, "%s%s:%d",
                   conn->socks_request->address,
                   conn->chosen_exit_name ? buf2 : "",
                   conn->socks_request->port)<0)
    return -1;
  return 0;
}

/** Something has happened to the stream associated with AP connection
 * <b>conn</b>: tell any interested control connections. */
int
control_event_stream_status(connection_t *conn, stream_status_event_t tp)
{
  char *msg;
  size_t len;
  char buf[256];
  tor_assert(conn->type == CONN_TYPE_AP);
  tor_assert(conn->socks_request);

  if (!EVENT_IS_INTERESTING(EVENT_STREAM_STATUS))
    return 0;

  write_stream_target_to_buf(conn, buf, sizeof(buf));
  if (EVENT_IS_INTERESTING0(EVENT_STREAM_STATUS)) {
    len = strlen(buf);
    msg = tor_malloc(5+len+1);
    msg[0] = (uint8_t) tp;
    set_uint32(msg+1, htonl(conn->global_identifier));
    strlcpy(msg+5, buf, len+1);

    send_control0_event(EVENT_STREAM_STATUS, (uint32_t)(5+len+1), msg);
    tor_free(msg);
  }
  if (EVENT_IS_INTERESTING1(EVENT_STREAM_STATUS)) {
    const char *status;
    circuit_t *circ;
    switch (tp)
      {
      case STREAM_EVENT_SENT_CONNECT: status = "SENTCONNECT"; break;
      case STREAM_EVENT_SENT_RESOLVE: status = "SENTRESOLVE"; break;
      case STREAM_EVENT_SUCCEEDED: status = "SUCCEEDED"; break;
      case STREAM_EVENT_FAILED: status = "FAILED"; break;
      case STREAM_EVENT_CLOSED: status = "CLOSED"; break;
      case STREAM_EVENT_NEW: status = "NEW"; break;
      case STREAM_EVENT_NEW_RESOLVE: status = "NEWRESOLVE"; break;
      case STREAM_EVENT_FAILED_RETRIABLE: status = "DETACHED"; break;
      default:
        log_fn(LOG_WARN, "Unrecognized status code %d", (int)tp);
        return 0;
      }
    circ = circuit_get_by_edge_conn(conn);
    send_control1_event(EVENT_STREAM_STATUS,
                        "650 STREAM %lu %s %lu %s\r\n",
                        (unsigned long)conn->global_identifier, status,
                        circ?(unsigned long)circ->global_identifier : 0ul,
                        buf);
    /* XXX need to specify its intended exit, etc? */
  }
  return 0;
}

/** Something has happened to the OR connection <b>conn</b>: tell any
 * interested control connections. */
int
control_event_or_conn_status(connection_t *conn,or_conn_status_event_t tp)
{
  char buf[HEX_DIGEST_LEN+3]; /* status, dollar, identity, NUL */
  size_t len;

  tor_assert(conn->type == CONN_TYPE_OR);

  if (!EVENT_IS_INTERESTING(EVENT_OR_CONN_STATUS))
    return 0;

  if (EVENT_IS_INTERESTING0(EVENT_OR_CONN_STATUS)) {
    buf[0] = (uint8_t)tp;
    strlcpy(buf+1,conn->nickname,sizeof(buf)-1);
    len = strlen(buf+1);
    send_control0_event(EVENT_OR_CONN_STATUS, (uint32_t)(len+1), buf);
  }
  if (EVENT_IS_INTERESTING1(EVENT_OR_CONN_STATUS)) {
    const char *status;
    switch (tp)
      {
      case OR_CONN_EVENT_LAUNCHED: status = "LAUNCHED"; break;
      case OR_CONN_EVENT_CONNECTED: status = "CONNECTED"; break;
      case OR_CONN_EVENT_FAILED: status = "FAILED"; break;
      case OR_CONN_EVENT_CLOSED: status = "CLOSED"; break;
      default:
        log_fn(LOG_WARN, "Unrecognized status code %d", (int)tp);
        return 0;
      }
    send_control1_event(EVENT_OR_CONN_STATUS,
                        "650 ORCONN %s %s\r\n",
                        conn->nickname, status);
  }
  return 0;
}

/** A second or more has elapsed: tell any interested control
 * connections how much bandwidth we used. */
int
control_event_bandwidth_used(uint32_t n_read, uint32_t n_written)
{
  char buf[8];

  if (EVENT_IS_INTERESTING0(EVENT_BANDWIDTH_USED)) {
    set_uint32(buf, htonl(n_read));
    set_uint32(buf+4, htonl(n_written));
    send_control0_event(EVENT_BANDWIDTH_USED, 8, buf);
  }
  if (EVENT_IS_INTERESTING1(EVENT_BANDWIDTH_USED)) {
    send_control1_event(EVENT_BANDWIDTH_USED,
                        "650 BW %lu %lu\r\n",
                        (unsigned long)n_read,
                        (unsigned long)n_written);
  }

  return 0;
}

/** DOCDOC */
void
disable_control_logging(void)
{
  ++disable_log_messages;
}

/** DOCDOC */
void
enable_control_logging(void)
{
  if (--disable_log_messages < 0)
    tor_assert(0);
}

/** We got a log message: tell any interested control connections. */
void
control_event_logmsg(int severity, const char *msg)
{
  int oldlog, event;

  if (disable_log_messages)
    return;

  oldlog = EVENT_IS_INTERESTING0(EVENT_LOG_OBSOLETE) &&
    (severity == LOG_NOTICE || severity == LOG_WARN || severity == LOG_ERR);
  event = log_severity_to_event(severity);

  if (event<0 || !EVENT_IS_INTERESTING0(event))
    event = 0;

  if (oldlog || event) {
    size_t len = strlen(msg);
    disable_log_messages = 1;
    if (event)
      send_control0_event(event, (uint32_t)(len+1), msg);
    if (oldlog)
      send_control0_event(EVENT_LOG_OBSOLETE, (uint32_t)(len+1), msg);
    disable_log_messages = 0;
  }

  event = log_severity_to_event(severity);
  if (event >= 0 && EVENT_IS_INTERESTING1(event)) {
    char *b = NULL;
    const char *s;
    if (strchr(msg, '\n')) {
      char *cp;
      b = tor_strdup(msg);
      for (cp = b; *cp; ++cp)
        if (*cp == '\r' || *cp == '\n')
          *cp = ' ';
    }
    switch (severity) {
      case LOG_DEBUG: s = "DEBUG"; break;
      case LOG_INFO: s = "INFO"; break;
      case LOG_NOTICE: s = "NOTICE"; break;
      case LOG_WARN: s = "WARN"; break;
      case LOG_ERR: s = "ERR"; break;
      default: s = "UnknownLogSeverity"; break;
    }
    disable_log_messages = 1;
    send_control1_event(event, "650 %s %s\r\n", s, b?b:msg);
    disable_log_messages = 0;
    tor_free(b);
  }
}

/** Called whenever we receive new router descriptors: tell any
 * interested control connections.  <b>routers</b> is a list of
 * DIGEST_LEN-byte identity digests.
 */
int
control_event_descriptors_changed(smartlist_t *routers)
{
  size_t len;
  char *msg;
  smartlist_t *identities;
  char buf[HEX_DIGEST_LEN+1];

  if (!EVENT_IS_INTERESTING(EVENT_NEW_DESC))
    return 0;
  identities = smartlist_create();
  SMARTLIST_FOREACH(routers, routerinfo_t *, r,
  {
    base16_encode(buf,sizeof(buf),r->identity_digest,DIGEST_LEN);
    smartlist_add(identities, tor_strdup(buf));
  });
  if (EVENT_IS_INTERESTING0(EVENT_NEW_DESC)) {
    msg = smartlist_join_strings(identities, ",", 0, &len);
    send_control0_event(EVENT_NEW_DESC, len+1, msg);
    tor_free(msg);
  }
  if (EVENT_IS_INTERESTING1(EVENT_NEW_DESC)) {
    msg = smartlist_join_strings(identities, " ", 0, &len);
    send_control1_event(EVENT_NEW_DESC, "650 NEWDESC %s\r\n", msg);
    tor_free(msg);
  }
  SMARTLIST_FOREACH(identities, char *, cp, tor_free(cp));
  smartlist_free(identities);

  return 0;
}

/** DOCDOC */
int
control_event_address_mapped(const char *from, const char *to, time_t expires)
{
  if (!EVENT_IS_INTERESTING1(EVENT_ADDRMAP))
    return 0;

  if (expires < 3)
    send_control1_event(EVENT_ADDRMAP, "650 ADDRMAP %s %s NEVER\r\n", from, to);
  else {
    char buf[ISO_TIME_LEN+1];
    format_local_iso_time(buf,expires);
    send_control1_event(EVENT_ADDRMAP, "650 ADDRMAP %s %s \"%s\"\r\n",
                        from, to, buf);
  }

  return 0;
}

/** Choose a random authentication cookie and write it to disk.
 * Anybody who can read the cookie from disk will be considered
 * authorized to use the control connection. */
int
init_cookie_authentication(int enabled)
{
  char fname[512];

  if (!enabled) {
    authentication_cookie_is_set = 0;
    return 0;
  }

  tor_snprintf(fname, sizeof(fname), "%s/control_auth_cookie",
               get_options()->DataDirectory);
  crypto_rand(authentication_cookie, AUTHENTICATION_COOKIE_LEN);
  authentication_cookie_is_set = 1;
  if (write_bytes_to_file(fname, authentication_cookie,
                          AUTHENTICATION_COOKIE_LEN, 1)) {
    log_fn(LOG_WARN,"Error writing authentication cookie.");
    return -1;
  }

  return 0;
}