config.c

/* Copyright 2001 Matej Pfajfar.
 * Copyright 2001-2004 Roger Dingledine.
 * Copyright 2004 Roger Dingledine, Nick Mathewson. */
/* See LICENSE for licensing information */
/* $Id$ */

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

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

/** 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_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),
  { "l", "Log", 1},
  { "BandwidthRate", "BandwidthRateBytes", 0},
  { "BandwidthBurst", "BandwidthBurstBytes", 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("AllowUnverifiedNodes",CSV,      AllowUnverifiedNodes, "middle,rendezvous"),
  VAR("AuthoritativeDirectory",BOOL,   AuthoritativeDir,     "0"),
  VAR("BandwidthRateBytes",  UINT,     BandwidthRateBytes,   "800000"),
  VAR("BandwidthBurstBytes", UINT,     BandwidthBurstBytes,  "50000000"),
  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("DirPort",             UINT,     DirPort,              "0"),
  VAR("DirBindAddress",      LINELIST, DirBindAddress,       NULL),
  VAR("DirFetchPostPeriod",  UINT,     DirFetchPostPeriod,   "600"),
  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",     UINT,     KeepalivePeriod,      "300"),
  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,   AccountingStart,      "1"),
  VAR("AccountingMaxKB",     UINT,     AccountingMaxKB,      "0"),
  VAR("Nickname",            STRING,   Nickname,             NULL),
  VAR("NewCircuitPeriod",    UINT,     NewCircuitPeriod,     "30"),
  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),
  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 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);

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

/** Command-line and config-file options. */
static or_options_t *global_options=NULL;
/** Name of ost 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.  Where
 * <b>new_val</b> is different from the old value, update the process to
 * use the new value instead.
 *
 * 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.
 */
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.
 */
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,
             "Previously validated DirServer line could not be added!");
      return -1;
    }
  }

  if (rend_config_services(options, 0)<0) {
    log_fn(LOG_ERR,
           "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;

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

  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);

  {
    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 reloading rendezvous service keys");
    return -1;
  }

  /* Set up accounting */
  if (get_options()->AccountingMaxKB)
    configure_accounting(time(NULL));

  if(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_DEBUGS, "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',
 * prepend it to 'front', and return the newly allocated config_line_t */
struct config_line_t *
config_line_prepend(struct config_line_t *front,
                    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 = front;
  return 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;
  char *k, *v;

  do {
    string = parse_line_from_str(string, &k, &v);
    if (!string) {
      config_free_lines(list);
      return -1;
    }
    if (k && v)
      list = config_line_prepend(list, k, v);
  } 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, unrecogized 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_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 == NULL)
      *(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:
    /* Note: this reverses the order that the lines appear in.  That's
     * just fine, since we build up the list of lines reversed in the
     * first place. */
    *(struct config_line_t**)lvalue =
      config_line_prepend(*(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_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_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_UINT:
    case CONFIG_TYPE_BOOL:
      *(int*)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 */
  options->DirServers = config_line_prepend(options->DirServers, "DirServer",
       "18.244.0.188:9031 FFCB 46DB 1339 DA84 674C 70D7 CB58 6434 C437 0441");
  /* moria2 */
  options->DirServers = config_line_prepend(options->DirServers, "DirServer",
         "18.244.0.114:80 719B E45D E224 B607 C537 07D0 E214 3E2D 423E 74CF");
  /* tor26 */
  options->DirServers = config_line_prepend(options->DirServers, "DirServer",
     "62.116.124.106:9030 847B 1F85 0344 D787 6491 A548 92F9 0493 4E4E B85D");
}

/** Print a usage message for tor. */
static void
print_usage(void)
{
  printf("tor -f <torrc> [args]\n"
         "See man page for more options. This -h is obsolete.\n");
#if 0
         "-b <bandwidth>\t\tbytes/second rate limiting\n"
         "-d <file>\t\tDebug file\n"
         "-l <level>\t\tLog level\n"
         "-r <file>\t\tList of known routers\n");
  printf("\nClient options:\n"
         "-e \"nick1 nick2 ...\"\t\tExit nodes\n"
         "-s <IP>\t\t\tPort to bind to for Socks\n");
  printf("\nServer options:\n"
         "-n <nick>\t\tNickname of router\n"
         "-o <port>\t\tOR port to bind to\n"
         "-p <file>\t\tPID file\n");
#endif
}

/**
 * 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. */
static char *
get_default_nickname(void)
{
  char localhostname[256];
  char *cp, *out, *outp;

  if (gethostname(localhostname, sizeof(localhostname)) < 0) {
    log_fn(LOG_WARN,"Error obtaining local hostname");
    return NULL;
  }

  /* Put it in lowercase; stop at the first dot. */
  for (cp = localhostname; *cp; ++cp) {
    if (*cp == '.') {
      *cp = '\0';
      break;
    }
    *cp = tolower(*cp);
  }

  /* Strip invalid characters. */
  cp = localhostname;
  out = outp = tor_malloc(strlen(localhostname) + 1);
  while (*cp) {
    if (strchr(LEGAL_NICKNAME_CHARACTERS, *cp))
      *outp++ = *cp++;
    else
      cp++;
  }
  *outp = '\0';

  /* Enforce length. */
  if (strlen(out) > MAX_NICKNAME_LEN)
    out[MAX_NICKNAME_LEN]='\0';

  return out;
}

/** Release storage held by <b>options</b> */
static void
options_free(or_options_t *options)
{
  int i;
  void *lvalue;

  for (i=0; config_vars[i].name; ++i) {
    lvalue = ((char*)options) + config_vars[i].var_offset;
    switch(config_vars[i].type) {
      case CONFIG_TYPE_UINT:
      case CONFIG_TYPE_BOOL:
      case CONFIG_TYPE_DOUBLE:
      case CONFIG_TYPE_OBSOLETE:
        break; /* nothing to free for these config types */
      case CONFIG_TYPE_STRING:
        tor_free(*(char **)lvalue);
        break;
      case CONFIG_TYPE_LINELIST:
      case CONFIG_TYPE_LINELIST_V:
        config_free_lines(*(struct config_line_t**)lvalue);
        *(struct config_line_t**)lvalue = NULL;
        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_S:
        /* will be freed by corresponding LINELIST_V. */
        break;
    }
  }
}

/** Return true iff the option <b>var</b> has the same value in <b>o1</b>
 * and <b>o2</b>.  Must not be called for LINELIST_S or OBSOLETE options.
 */
static int
option_is_same(or_options_t *o1, or_options_t *o2, const char *name)
{
  struct config_line_t *c1, *c2;
  int r = 1;
  c1 = config_get_assigned_option(o1, name);
  c2 = config_get_assigned_option(o2, name);
  while (c1 && c2) {
    if (strcasecmp(c1->key, c2->key) ||
        strcmp(c1->value, c2->value)) {
      r = 0;
      break;
    }
    c1 = c1->next;
    c2 = c2->next;
  }
  if (r && (c1 || c2)) {
    r = 0;
  }
  config_free_lines(c1);
  config_free_lines(c2);
  return r;
}

/** Copy storage held by <b>old</b> into a new or_options_t and return it. */
static or_options_t *
options_dup(or_options_t *old)
{
  or_options_t *newopts;
  int i;
  struct config_line_t *line;