config.c

/* Copyright 2001 Matej Pfajfar.
 * Copyright 2001-2004 Roger Dingledine.
 * Copyright 2004 Roger Dingledine, Nick Mathewson. */
/* See LICENSE for licensing information */
/* $Id$ */
const char config_c_id[] = "$Id$";

/**
 * \file config.c
 *
 * \brief Code to parse and interpret configuration files.
 **/

#include "or.h"
#ifdef MS_WINDOWS
#include <shlobj.h>
#endif
#include "../common/aes.h"

/** Enumeration of types which option values can take */
typedef enum config_type_t {
  CONFIG_TYPE_STRING = 0,   /**< An arbitrary string. */
  CONFIG_TYPE_UINT,         /**< A non-negative integer less than MAX_INT */
  CONFIG_TYPE_INTERVAL,     /**< A number of seconds, with optional units*/
  CONFIG_TYPE_MEMUNIT,      /**< A number of bytes, with optional units*/
  CONFIG_TYPE_DOUBLE,       /**< A floating-point value */
  CONFIG_TYPE_BOOL,         /**< A boolean value, expressed as 0 or 1. */
  CONFIG_TYPE_CSV,          /**< A list of strings, separated by commas and optional
                              * whitespace. */
  CONFIG_TYPE_LINELIST,     /**< Uninterpreted config lines */
  CONFIG_TYPE_LINELIST_S,   /**< Uninterpreted, context-sensitive config lines,
                             * mixed with other keywords. */
  CONFIG_TYPE_LINELIST_V,   /**< Catch-all "virtual" option to summarize
                             * context-sensitive config lines when fetching.
                             */
  CONFIG_TYPE_OBSOLETE,     /**< Obsolete (ignored) option. */
} config_type_t;

/* An abbreviation for a configuration option allowed on the command line */
typedef struct config_abbrev_t {
  const char *abbreviated;
  const char *full;
  int commandline_only;
} config_abbrev_t;

/* Handy macro for declaring "In the config file or on the command line,
 * you can abbreviate <b>tok</b>s as <b>tok</b>". */
#define PLURAL(tok) { #tok, #tok "s", 0 }

/* A list of command-line abbreviations. */
static config_abbrev_t config_abbrevs[] = {
  PLURAL(ExitNode),
  PLURAL(EntryNode),
  PLURAL(ExcludeNode),
  PLURAL(FirewallPort),
  PLURAL(HiddenServiceNode),
  PLURAL(HiddenServiceExcludeNode),
  PLURAL(RendNode),
  PLURAL(RendExcludeNode),
  PLURAL(StrictEntryNode),
  PLURAL(StrictExitNode),
  { "l", "Log", 1},
  { "BandwidthRateBytes", "BandwidthRate", 0},
  { "BandwidthBurstBytes", "BandwidthBurst", 0},
  { "DirFetchPostPeriod", "StatusFetchPeriod", 0},
  { NULL, NULL , 0},
};
#undef PLURAL

/** A variable allowed in the configuration file or on the command line. */
typedef struct config_var_t {
  const char *name; /**< The full keyword (case insensitive). */
  config_type_t type; /**< How to interpret the type and turn it into a value. */
  off_t var_offset; /**< Offset of the corresponding member of or_options_t. */
  const char *initvalue; /**< String (or null) describing initial value. */
} config_var_t;

/** Return the offset of <b>member</b> within the type <b>tp</b>, in bytes */
#define STRUCT_OFFSET(tp, member) ((off_t) (((char*)&((tp*)0)->member)-(char*)0))
/** An entry for config_vars: "The option <b>name</b> has type
 * CONFIG_TYPE_<b>conftype</b>, and corresponds to
 * or_options_t.<b>member</b>"
 */
#define VAR(name,conftype,member,initvalue) \
  { name, CONFIG_TYPE_ ## conftype, STRUCT_OFFSET(or_options_t, member), initvalue }
/** An entry for config_vars: "The option <b>name</b> is obsolete." */
#define OBSOLETE(name) { name, CONFIG_TYPE_OBSOLETE, 0, NULL }

/** Array of configuration options.  Until we disallow nonstandard
 * abbreviations, order is significant, since the first matching option will
 * be chosen first.
 */
static config_var_t config_vars[] = {
  VAR("Address",             STRING,   Address,              NULL),
  VAR("AccountingStart",     STRING,   AccountingStart,      NULL),
  VAR("AllowUnverifiedNodes",CSV,      AllowUnverifiedNodes, "middle,rendezvous"),
  VAR("AuthoritativeDirectory",BOOL,   AuthoritativeDir,     "0"),
  VAR("BandwidthRate",       MEMUNIT,  BandwidthRate,        "780 KB"),
  VAR("BandwidthBurst",      MEMUNIT,  BandwidthBurst,       "48 MB"),
  VAR("ClientOnly",          BOOL,     ClientOnly,           "0"),
  VAR("ContactInfo",         STRING,   ContactInfo,          NULL),
  VAR("ControlPort",         UINT,     ControlPort,          "0"),
  VAR("CookieAuthentication",BOOL,     CookieAuthentication, "0"),
  VAR("DebugLogFile",        STRING,   DebugLogFile,         NULL),
  VAR("DataDirectory",       STRING,   DataDirectory,        NULL),
  VAR("DirAllowPrivateAddresses",BOOL, DirAllowPrivateAddresses, NULL),
  VAR("DirPort",             UINT,     DirPort,              "0"),
  VAR("DirBindAddress",      LINELIST, DirBindAddress,       NULL),
/* XXX we'd like dirfetchperiod to be higher for people with dirport not
 * set, but low for people with dirport set. how to have two defaults? */
  VAR("DirFetchPeriod",      INTERVAL, DirFetchPeriod,       "1 hour"),
  VAR("DirPostPeriod",       INTERVAL, DirPostPeriod,        "20 minutes"),
  VAR("RendPostPeriod",      INTERVAL, RendPostPeriod,       "20 minutes"),
  VAR("DirPolicy",           LINELIST, DirPolicy,            NULL),
  VAR("DirServer",           LINELIST, DirServers,           NULL),
  VAR("ExitNodes",           STRING,   ExitNodes,            NULL),
  VAR("EntryNodes",          STRING,   EntryNodes,           NULL),
  VAR("StrictExitNodes",     BOOL,     StrictExitNodes,      "0"),
  VAR("StrictEntryNodes",    BOOL,     StrictEntryNodes,     "0"),
  VAR("ExitPolicy",          LINELIST, ExitPolicy,           NULL),
  VAR("ExcludeNodes",        STRING,   ExcludeNodes,         NULL),
  VAR("FascistFirewall",     BOOL,     FascistFirewall,      "0"),
  VAR("FirewallPorts",       CSV,      FirewallPorts,        "80,443"),
  VAR("MyFamily",            STRING,   MyFamily,             NULL),
  VAR("NodeFamily",          LINELIST, NodeFamilies,         NULL),
  VAR("Group",               STRING,   Group,                NULL),
  VAR("HashedControlPassword",STRING,  HashedControlPassword, NULL),
  VAR("HttpProxy",           STRING,   HttpProxy,            NULL),
  VAR("HiddenServiceOptions",LINELIST_V, RendConfigLines,    NULL),
  VAR("HiddenServiceDir",    LINELIST_S, RendConfigLines,    NULL),
  VAR("HiddenServicePort",   LINELIST_S, RendConfigLines,    NULL),
  VAR("HiddenServiceNodes",  LINELIST_S, RendConfigLines,    NULL),
  VAR("HiddenServiceExcludeNodes", LINELIST_S, RendConfigLines, NULL),
  VAR("IgnoreVersion",       BOOL,     IgnoreVersion,        "0"),
  VAR("KeepalivePeriod",     INTERVAL, KeepalivePeriod,      "5 minutes"),
  VAR("Log",                 LINELIST, Logs,                 NULL),
  VAR("LogLevel",            LINELIST_S, OldLogOptions,      NULL),
  VAR("LogFile",             LINELIST_S, OldLogOptions,      NULL),
  OBSOLETE("LinkPadding"),
  VAR("MaxConn",             UINT,     MaxConn,              "1024"),
  VAR("MaxOnionsPending",    UINT,     MaxOnionsPending,     "100"),
  VAR("MonthlyAccountingStart",UINT,   _MonthlyAccountingStart,"0"),
  VAR("AccountingMaxKB",     UINT,     _AccountingMaxKB,     "0"),
  VAR("AccountingMax",       MEMUNIT,   AccountingMax,        "0 bytes"),
  VAR("Nickname",            STRING,   Nickname,             NULL),
  VAR("NewCircuitPeriod",    INTERVAL, NewCircuitPeriod,     "30 seconds"),
  VAR("NumCpus",             UINT,     NumCpus,              "1"),
  VAR("ORPort",              UINT,     ORPort,               "0"),
  VAR("ORBindAddress",       LINELIST, ORBindAddress,        NULL),
  VAR("OutboundBindAddress", STRING,   OutboundBindAddress,  NULL),
  VAR("PidFile",             STRING,   PidFile,              NULL),
  VAR("PathlenCoinWeight",   DOUBLE,   PathlenCoinWeight,    "0.3"),
  VAR("RedirectExit",        LINELIST, RedirectExit,         NULL),
  OBSOLETE("RouterFile"),
  VAR("RunAsDaemon",         BOOL,     RunAsDaemon,          "0"),
  VAR("RunTesting",          BOOL,     RunTesting,           "0"),
  VAR("RecommendedVersions", LINELIST, RecommendedVersions,  NULL),
  VAR("RendNodes",           STRING,   RendNodes,            NULL),
  VAR("RendExcludeNodes",    STRING,   RendExcludeNodes,     NULL),
  VAR("SocksPort",           UINT,     SocksPort,            "9050"),
  VAR("SocksBindAddress",    LINELIST, SocksBindAddress,     NULL),
  VAR("SocksPolicy",         LINELIST, SocksPolicy,          NULL),
/* XXX as with dirfetchperiod, we want this to be 15 minutes for people
 * with a dirport open, but higher for people without a dirport open. */
  VAR("StatusFetchPeriod",   INTERVAL, StatusFetchPeriod,    "15 minutes"),
  VAR("SysLog",              LINELIST_S, OldLogOptions,      NULL),
  OBSOLETE("TrafficShaping"),
  VAR("User",                STRING,   User,                 NULL),
  { NULL, CONFIG_TYPE_OBSOLETE, 0, NULL }
};
#undef VAR
#undef OBSOLETE

/** Largest allowed config line */
#define CONFIG_LINE_T_MAXLEN 4096

static void config_line_append(struct config_line_t **lst,
                               const char *key, const char *val);
static void option_reset(or_options_t *options, config_var_t *var);
static void options_free(or_options_t *options);
static int option_is_same(or_options_t *o1, or_options_t *o2,const char *name);
static or_options_t *options_dup(or_options_t *old);
static int options_validate(or_options_t *options);
static int options_transition_allowed(or_options_t *old, or_options_t *new);
static int check_nickname_list(const char *lst, const char *name);

static int parse_dir_server_line(const char *line, int validate_only);
static int parse_redirect_line(smartlist_t *result,
                               struct config_line_t *line);
static int parse_log_severity_range(const char *range, int *min_out,
                                    int *max_out);
static int convert_log_option(or_options_t *options,
                              struct config_line_t *level_opt,
                              struct config_line_t *file_opt, int isDaemon);
static int add_single_log_option(or_options_t *options, int minSeverity,
                                 int maxSeverity,
                                 const char *type, const char *fname);
static int normalize_log_options(or_options_t *options);
static int validate_data_directory(or_options_t *options);
static int write_configuration_file(const char *fname, or_options_t *options);

static uint64_t config_parse_memunit(const char *s, int *ok);
static int config_parse_interval(const char *s, int *ok);
static void print_cvs_version(void);

/*
 * Functions to read and write the global options pointer.
 */

/** Command-line and config-file options. */
static or_options_t *global_options=NULL;
/** Name of most recently read torrc file. */
static char *config_fname = NULL;

/** Return the currently configured options. */
or_options_t *
get_options(void) {
  tor_assert(global_options);
  return global_options;
}

/** Change the current global options to contain <b>new_val</b> instead
 * of their current value; free the old value as necessary.
 */
void
set_options(or_options_t *new_val) {
  if (global_options)
    options_free(global_options);
  global_options = new_val;
}

/** Fetch the active option list, and take actions based on it. All
 * of the things we do should survive being done repeatedly.
 * Return 0 if all goes well, return -1 if it's time to die.
 *
 * Note 1: <b>new_val</b> must have previously been validated with
 * options_validate(), or Tor may freak out and exit.
 *
 * Note 2: We haven't moved all the "act on new configuration" logic
 * here yet.  Some is still in do_hup() and other places.
 */
int
options_act(void) {
  struct config_line_t *cl;
  or_options_t *options = get_options();

  clear_trusted_dir_servers();
  for (cl = options->DirServers; cl; cl = cl->next) {
    if (parse_dir_server_line(cl->value, 0)<0) {
      log_fn(LOG_ERR,
             "Bug: Previously validated DirServer line could not be added!");
      return -1;
    }
  }

  if (rend_config_services(options, 0)<0) {
    log_fn(LOG_ERR,
           "Bug: Previously validated hidden services line could not be added!");
    return -1;
  }

  /* Setuid/setgid as appropriate */
  if (options->User || options->Group) {
    if (switch_id(options->User, options->Group) != 0) {
      return -1;
    }
  }

  /* Ensure data directory is private; create if possible. */
  if (check_private_dir(options->DataDirectory, CPD_CREATE) != 0) {
    log_fn(LOG_ERR, "Couldn't access/create private data directory %s",
           options->DataDirectory);
    return -1;
  }

  /* Bail out at this point if we're not going to be a server: we want
   * to not fork, and to log stuff to stderr. */
  if (options->command != CMD_RUN_TOR)
    return 0;

  mark_logs_temp(); /* Close current logs once new logs are open. */
  if (config_init_logs(options, 0)<0) /* Configure the log(s) */
    return -1;
  /* Close the temporary log we used while starting up, if it isn't already
   * gone. */
  close_temp_logs();
  add_callback_log(LOG_NOTICE, LOG_ERR, control_event_logmsg);

  if (set_max_file_descriptors(options->MaxConn) < 0)
    return -1;

  {
    smartlist_t *sl = smartlist_create();
    for (cl = options->RedirectExit; cl; cl = cl->next) {
      if (parse_redirect_line(sl, cl)<0)
        return -1;
    }
    set_exit_redirects(sl);
  }

  /* Start backgrounding the process, if requested. */

  /* XXXX009 We once had a reason to separate start_daemon and finish_daemon:
   *    It let us have the parent process stick around until we were sure Tor
   *    was started.  Should we make start_daemon get called earlier? -NM */
  if (options->RunAsDaemon) {
    start_daemon(options->DataDirectory);
  }

  /* Finish backgrounding the process */
  if (options->RunAsDaemon) {
    /* We may be calling this for the n'th time (on SIGHUP), but it's safe. */
    finish_daemon();
  }

  /* Write our pid to the pid file. If we do not have write permissions we
   * will log a warning */
  if (options->PidFile)
    write_pidfile(options->PidFile);

  /* Update address policies. */
  parse_socks_policy();
  parse_dir_policy();

  init_cookie_authentication(options->CookieAuthentication);

  /* reload keys as needed for rendezvous services. */
  if (rend_service_load_keys()<0) {
    log_fn(LOG_ERR,"Error loading rendezvous service keys");
    return -1;
  }

  /* Set up accounting */
  if (accounting_parse_options(options, 0)<0) {
    log_fn(LOG_ERR,"Error in accounting options");
    return -1;
  }
  if (accounting_is_enabled(options))
    configure_accounting(time(NULL));

  if (!we_are_hibernating() && retry_all_listeners(1) < 0) {
    log_fn(LOG_ERR,"Failed to bind one of the listener ports.");
    return -1;
  }

#if 0
  {
    char *smin, *smax;
    smin = config_dump_options(options, 1);
    smax = config_dump_options(options, 0);
    log_fn(LOG_DEBUG, "These are our options:\n%s",smax);
    log_fn(LOG_DEBUG, "We changed these options:\n%s",smin);
    tor_free(smin);
    tor_free(smax);
  }
#endif

  /* Since our options changed, we might need to regenerate and upload our
   * server descriptor.  (We could probably be more clever about only calling
   * this when something significant changed.)
   */
  mark_my_descriptor_dirty();

  return 0;
}

/*
 * Functions to parse config options
 */

/** If <b>option</b> is an official abbreviation for a longer option,
 * return the longer option.  Otherwise return <b>option</b>.
 * If <b>command_line</b> is set, apply all abbreviations.  Otherwise, only
 * apply abbreviations that work for the config file and the command line. */
static const char *
expand_abbrev(const char *option, int command_line)
{
  int i;
  for (i=0; config_abbrevs[i].abbreviated; ++i) {
    /* Abbreviations aren't casei. */
    if (!strcasecmp(option,config_abbrevs[i].abbreviated) &&
        (command_line || !config_abbrevs[i].commandline_only)) {
      return config_abbrevs[i].full;
    }
  }
  return option;
}

/** Helper: Read a list of configuration options from the command line. */
static struct config_line_t *
config_get_commandlines(int argc, char **argv)
{
  struct config_line_t *new;
  struct config_line_t *front = NULL;
  char *s;
  int i = 1;

  while (i < argc-1) {
    if (!strcmp(argv[i],"-f") ||
        !strcmp(argv[i],"--hash-password")) {
      i += 2; /* command-line option with argument. ignore them. */
      continue;
    } else if (!strcmp(argv[i],"--list-fingerprint")) {
      i += 1; /* command-line option. ignore it. */
      continue;
    }

    new = tor_malloc(sizeof(struct config_line_t));
    s = argv[i];

    while (*s == '-')
      s++;

    new->key = tor_strdup(expand_abbrev(s, 1));
    new->value = tor_strdup(argv[i+1]);

    log(LOG_DEBUG,"Commandline: parsed keyword '%s', value '%s'",
        new->key, new->value);
    new->next = front;
    front = new;
    i += 2;
  }
  return front;
}

/** Helper: allocate a new configuration option mapping 'key' to 'val',
 * append it to *<b>lst</b>. */
static void
config_line_append(struct config_line_t **lst,
                   const char *key,
                   const char *val)
{
  struct config_line_t *newline;

  newline = tor_malloc(sizeof(struct config_line_t));
  newline->key = tor_strdup(key);
  newline->value = tor_strdup(val);
  newline->next = NULL;
  while (*lst)
    lst = &((*lst)->next);

  (*lst) = newline;
}

/** Helper: parse the config string and strdup into key/value
 * strings. Set *result to the list, or NULL if parsing the string
 * failed.  Return 0 on success, -1 on failure. Warn and ignore any
 * misformatted lines. */
int
config_get_lines(char *string, struct config_line_t **result)
{
  struct config_line_t *list = NULL, **next;
  char *k, *v;

  next = &list;
  do {
    string = parse_line_from_str(string, &k, &v);
    if (!string) {
      config_free_lines(list);
      return -1;
    }
    if (k && v) {
      /* This list can get long, so we keep a pointer to the end of it
       * rather than using config_line_append over and over and getting n^2
       * performance.  This is the only really long list. */
      *next = tor_malloc(sizeof(struct config_line_t));
      (*next)->key = tor_strdup(k);
      (*next)->value = tor_strdup(v);
      (*next)->next = NULL;
      next = &((*next)->next);
    }
  } while (*string);

  *result = list;
  return 0;
}

/**
 * Free all the configuration lines on the linked list <b>front</b>.
 */
void
config_free_lines(struct config_line_t *front)
{
  struct config_line_t *tmp;

  while (front) {
    tmp = front;
    front = tmp->next;

    tor_free(tmp->key);
    tor_free(tmp->value);
    tor_free(tmp);
  }
}

/** If <b>key</b> is a configuration option, return the corresponding
 * config_var_t.  Otherwise, if <b>key</b> is a non-standard abbreviation,
 * warn, and return the corresponding config_var_t.  Otherwise return NULL.
 */
static config_var_t *config_find_option(const char *key)
{
  int i;
  /* First, check for an exact (case-insensitive) match */
  for (i=0; config_vars[i].name; ++i) {
    if (!strcasecmp(key, config_vars[i].name))
      return &config_vars[i];
  }
  /* If none, check for an abbreviated match */
  for (i=0; config_vars[i].name; ++i) {
    if (!strncasecmp(key, config_vars[i].name, strlen(key))) {
      log_fn(LOG_WARN, "The abbreviation '%s' is deprecated. "
          "Tell Nick and Roger to make it official, or just use '%s' instead",
             key, config_vars[i].name);
      return &config_vars[i];
    }
  }
  /* Okay, unrecognized options */
  return NULL;
}

/** If <b>c</b> is a syntactically valid configuration line, update
 * <b>options</b> with its value and return 0.  Otherwise return -1 for bad key,
 * -2 for bad value.
 *
 * If 'reset' is set, and we get a line containing no value, restore the
 * option to its default value.
 */
static int
config_assign_line(or_options_t *options, struct config_line_t *c, int reset)
{
  int i, ok;
  config_var_t *var;
  void *lvalue;

  var = config_find_option(c->key);
  if (!var) {
    log_fn(LOG_WARN, "Unknown option '%s'.  Failing.", c->key);
    return -1;
  }
  /* Put keyword into canonical case. */
  if (strcmp(var->name, c->key)) {
    tor_free(c->key);
    c->key = tor_strdup(var->name);
  }

  if (reset && !strlen(c->value)) {
    option_reset(options, var);
    return 0;
  }

  lvalue = ((char*)options) + var->var_offset;
  switch (var->type) {

  case CONFIG_TYPE_UINT:
    i = tor_parse_long(c->value, 10, 0, INT_MAX, &ok, NULL);
    if (!ok) {
      log(LOG_WARN, "Int keyword '%s %s' is malformed or out of bounds.",
          c->key,c->value);
      return -2;
    }
    *(int *)lvalue = i;
    break;

  case CONFIG_TYPE_INTERVAL: {
    i = config_parse_interval(c->value, &ok);
    if (!ok) {
      return -2;
    }
    *(int *)lvalue = i;
    break;
  }

  case CONFIG_TYPE_MEMUNIT: {
    uint64_t u64 = config_parse_memunit(c->value, &ok);
    if (!ok) {
      return -2;
    }
    *(uint64_t *)lvalue = u64;
    break;
  }

  case CONFIG_TYPE_BOOL:
    i = tor_parse_long(c->value, 10, 0, 1, &ok, NULL);
    if (!ok) {
      log(LOG_WARN, "Boolean keyword '%s' expects 0 or 1.", c->key);
      return -2;
    }
    *(int *)lvalue = i;
    break;

  case CONFIG_TYPE_STRING:
    tor_free(*(char **)lvalue);
    *(char **)lvalue = tor_strdup(c->value);
    break;

  case CONFIG_TYPE_DOUBLE:
    *(double *)lvalue = atof(c->value);
    break;

  case CONFIG_TYPE_CSV:
    if (*(smartlist_t**)lvalue) {
      SMARTLIST_FOREACH(*(smartlist_t**)lvalue, char *, cp, tor_free(cp));
      smartlist_clear(*(smartlist_t**)lvalue);
    } else {
      *(smartlist_t**)lvalue = smartlist_create();
    }

    smartlist_split_string(*(smartlist_t**)lvalue, c->value, ",",
                           SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, 0);
    break;

  case CONFIG_TYPE_LINELIST:
  case CONFIG_TYPE_LINELIST_S:
    config_line_append((struct config_line_t**)lvalue, c->key, c->value);
    break;

  case CONFIG_TYPE_OBSOLETE:
    log_fn(LOG_WARN, "Skipping obsolete configuration option '%s'", c->key);
    break;
  case CONFIG_TYPE_LINELIST_V:
    log_fn(LOG_WARN, "Can't provide value for virtual option '%s'", c->key);
    return -2;
  default:
    tor_assert(0);
    break;
  }
  return 0;
}

/** restore the option named <b>key</b> in options to its default value. */
static void
config_reset_line(or_options_t *options, const char *key)
{
  config_var_t *var;

  var = config_find_option(key);
  if (!var)
    return; /* give error on next pass. */

  option_reset(options, var);
}

/** Return true iff key is a valid configuration option. */
int
config_option_is_recognized(const char *key)
{
  config_var_t *var = config_find_option(key);
  return (var != NULL);
}

/** Return a canonicalized list of the options assigned for key.
 */
struct config_line_t *
config_get_assigned_option(or_options_t *options, const char *key)
{
  config_var_t *var;
  const void *value;
  char buf[32];
  struct config_line_t *result;
  tor_assert(options && key);

  var = config_find_option(key);
  if (!var) {
    log_fn(LOG_WARN, "Unknown option '%s'.  Failing.", key);
    return NULL;
  } else if (var->type == CONFIG_TYPE_LINELIST_S) {
    log_fn(LOG_WARN, "Can't return context-sensitive '%s' on its own", key);
    return NULL;
  }
  value = ((char*)options) + var->var_offset;

  if (var->type == CONFIG_TYPE_LINELIST ||
      var->type == CONFIG_TYPE_LINELIST_V) {
    /* Linelist requires special handling: we just copy and return it. */
    const struct config_line_t *next_in = *(const struct config_line_t**)value;
    struct config_line_t **next_out = &result;
    while (next_in) {
      *next_out = tor_malloc(sizeof(struct config_line_t));
      (*next_out)->key = tor_strdup(next_in->key);
      (*next_out)->value = tor_strdup(next_in->value);
      next_in = next_in->next;
      next_out = &((*next_out)->next);
    }
    (*next_out) = NULL;
    return result;
  }

  result = tor_malloc_zero(sizeof(struct config_line_t));
  result->key = tor_strdup(var->name);
  switch (var->type)
    {
    case CONFIG_TYPE_STRING:
      if (*(char**)value) {
        result->value = tor_strdup(*(char**)value);
      } else {
        tor_free(result->key);
        tor_free(result);
        return NULL;
      }
      break;
    case CONFIG_TYPE_INTERVAL:
    case CONFIG_TYPE_UINT:
      /* This means every or_options_t uint or bool element
       * needs to be an int. Not, say, a uint16_t or char. */
      tor_snprintf(buf, sizeof(buf), "%d", *(int*)value);
      result->value = tor_strdup(buf);
      break;
    case CONFIG_TYPE_MEMUNIT:
      tor_snprintf(buf, sizeof(buf), U64_FORMAT,
                   U64_PRINTF_ARG(*(uint64_t*)value));
      result->value = tor_strdup(buf);
      break;
    case CONFIG_TYPE_DOUBLE:
      tor_snprintf(buf, sizeof(buf), "%f", *(double*)value);
      result->value = tor_strdup(buf);
      break;
    case CONFIG_TYPE_BOOL:
      result->value = tor_strdup(*(int*)value ? "1" : "0");
      break;
    case CONFIG_TYPE_CSV:
      if (*(smartlist_t**)value)
        result->value = smartlist_join_strings(*(smartlist_t**)value,",",0,NULL);
      else
        result->value = tor_strdup("");
      break;
    case CONFIG_TYPE_OBSOLETE:
      log_fn(LOG_WARN,"You asked me for the value of an obsolete config option %s.", key);
      tor_free(result->key);
      tor_free(result);
      return NULL;
    default:
      tor_free(result->key);
      tor_free(result);
      log_fn(LOG_WARN,"Bug: unknown type %d for known key %s", var->type, key);
      return NULL;
    }

  return result;
}

/** Iterate through the linked list of requested options <b>list</b>.
 * For each item, convert as appropriate and assign to <b>options</b>.
 * If an item is unrecognized, return -1 immediately,
 * else return 0 for success.
 *
 * If <b>reset</b>, then interpret empty lines as meaning "restore to
 * default value", and interpret LINELIST* options as replacing (not
 * extending) their previous values.  Return 0 on success, -1 on bad key,
 * -2 on bad value.
 */
static int
config_assign(or_options_t *options, struct config_line_t *list, int reset)
{
  struct config_line_t *p;
  tor_assert(options);

  /* pass 1: normalize keys */
  for (p = list; p; p = p->next) {
    const char *full = expand_abbrev(p->key, 0);
    if (strcmp(full,p->key)) {
      tor_free(p->key);
      p->key = tor_strdup(full);
    }
  }

  /* pass 2: if we're reading from a resetting source, clear all mentioned
   * linelists. */
  if (reset) {
    for (p = list; p; p = p->next)
      config_reset_line(options, p->key);
  }

  /* pass 3: assign. */
  while (list) {
    int r;
    if ((r=config_assign_line(options, list, reset)))
      return r;
    list = list->next;
  }
  return 0;
}

/** Try assigning <b>list</b> to the global options. You do this by duping
 * options, assigning list to the new one, then validating it. If it's
 * ok, then throw out the old one and stick with the new one. Else,
 * revert to old and return failure.  Return 0 on success, -1 on bad
 * keys, -2 on bad values, -3 on bad transition.
 */
int
config_trial_assign(struct config_line_t *list, int reset)
{
  int r;
  or_options_t *trial_options = options_dup(get_options());

  if ((r=config_assign(trial_options, list, reset)) < 0) {
    options_free(trial_options);
    return r;
  }

  if (options_validate(trial_options) < 0) {
    options_free(trial_options);
    return -2;
  }

  if (options_transition_allowed(get_options(), trial_options) < 0) {
    options_free(trial_options);
    return -3;
  }

  set_options(trial_options); /* we liked it. put it in place. */
  return 0;
}

/** Replace the option indexed by <b>var</b> in <b>options</b> with its
 * default value. */
static void
option_reset(or_options_t *options, config_var_t *var)
{
  struct config_line_t *c;
  void *lvalue;

  lvalue = ((char*)options) + var->var_offset;
  switch (var->type) {
    case CONFIG_TYPE_STRING:
      tor_free(*(char**)lvalue);
      break;
    case CONFIG_TYPE_DOUBLE:
      *(double*)lvalue = 0.0;
      break;
    case CONFIG_TYPE_INTERVAL:
    case CONFIG_TYPE_UINT:
    case CONFIG_TYPE_BOOL:
      *(int*)lvalue = 0;
      break;
    case CONFIG_TYPE_MEMUNIT:
      *(uint64_t*)lvalue = 0;
      break;
    case CONFIG_TYPE_CSV:
      if (*(smartlist_t**)lvalue) {
        SMARTLIST_FOREACH(*(smartlist_t **)lvalue, char *, cp, tor_free(cp));
        smartlist_free(*(smartlist_t **)lvalue);
        *(smartlist_t **)lvalue = NULL;
      }
      break;
    case CONFIG_TYPE_LINELIST:
    case CONFIG_TYPE_LINELIST_S:
      config_free_lines(*(struct config_line_t **)lvalue);
      *(struct config_line_t **)lvalue = NULL;
      break;
    case CONFIG_TYPE_LINELIST_V:
      /* handled by linelist_s. */
      break;
    case CONFIG_TYPE_OBSOLETE:
      break;
  }
  if (var->initvalue) {
    c = tor_malloc_zero(sizeof(struct config_line_t));
    c->key = tor_strdup(var->name);
    c->value = tor_strdup(var->initvalue);
    config_assign_line(options,c,0);
    config_free_lines(c);
  }
}

/** Set <b>options</b>-&gt;DirServers to contain the default directory
 * servers. */
static void
add_default_trusted_dirservers(or_options_t *options)
{
  /* moria1 */
  config_line_append(&options->DirServers, "DirServer",
       "18.244.0.188:9031 FFCB 46DB 1339 DA84 674C 70D7 CB58 6434 C437 0441");
  /* moria2 */
  config_line_append(&options->DirServers, "DirServer",
         "18.244.0.114:80 719B E45D E224 B607 C537 07D0 E214 3E2D 423E 74CF");
  /* tor26 */
  config_line_append(&options->DirServers, "DirServer",
     "62.116.124.106:9030 847B 1F85 0344 D787 6491 A548 92F9 0493 4E4E B85D");
//  "tor.noreply.org:9030 847B 1F85 0344 D787 6491 A548 92F9 0493 4E4E B85D");
}

/** Print a usage message for tor. */
static void
print_usage(void)
{
  printf(
"Copyright 2001-2004 Roger Dingledine, Nick Mathewson, Matej Pfajfar.\n\n"
"tor -f <torrc> [args]\n"
"See man page for options, or http://tor.eff.org/ for documentation.\n");
}

/**
 * Based on <b>address</b>, guess our public IP address and put it
 * in <b>addr</b>.
 */
int
resolve_my_address(const char *address, uint32_t *addr)
{
  struct in_addr in;
  struct hostent *rent;
  char hostname[256];
  int explicit_ip=1;

  tor_assert(addr);

  if (address) {
    strlcpy(hostname, address, sizeof(hostname));
  } else { /* then we need to guess our address */
    explicit_ip = 0; /* it's implicit */

    if (gethostname(hostname, sizeof(hostname)) < 0) {
      log_fn(LOG_WARN,"Error obtaining local hostname");
      return -1;
    }
    log_fn(LOG_DEBUG,"Guessed local host name as '%s'",hostname);
  }

  /* now we know hostname. resolve it and keep only the IP */

  if (tor_inet_aton(hostname, &in) == 0) {
    /* then we have to resolve it */
    explicit_ip = 0;
    rent = (struct hostent *)gethostbyname(hostname);
    if (!rent) {
      log_fn(LOG_WARN,"Could not resolve local Address %s. Failing.", hostname);
      return -1;
    }
    tor_assert(rent->h_length == 4);
    memcpy(&in.s_addr, rent->h_addr, rent->h_length);
  }

  if (!explicit_ip && is_internal_IP(htonl(in.s_addr))) {
    log_fn(LOG_WARN,"Address '%s' resolves to private IP '%s'. "
           "Please set the Address config option to be the IP you want to use.",
           hostname, inet_ntoa(in));
    return -1;
  }

  log_fn(LOG_DEBUG, "Resolved Address to %s.", inet_ntoa(in));
  *addr = ntohl(in.s_addr);
  return 0;
}

/** Called when we don't have a nickname set.  Try to guess a good
 * nickname based on the hostname, and return it in a newly allocated string. */
static char *
get_default_nickname(void)