config.c

/* Copyright 2001 Matej Pfajfar.
 * Copyright 2001-2004 Roger Dingledine.
 * Copyright 2004-2005 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_ISOTIME,      /**< An ISO-formated time relative to GMT. */
  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 _option_abbrevs[] = {
  PLURAL(ExitNode),
  PLURAL(EntryNode),
  PLURAL(ExcludeNode),
  PLURAL(FirewallPort),
  PLURAL(LongLivedPort),
  PLURAL(HiddenServiceNode),
  PLURAL(HiddenServiceExcludeNode),
  PLURAL(NumCpu),
  PLURAL(RendNode),
  PLURAL(RendExcludeNode),
  PLURAL(StrictEntryNode),
  PLURAL(StrictExitNode),
  { "l", "Log", 1},
  { "BandwidthRateBytes", "BandwidthRate", 0},
  { "BandwidthBurstBytes", "BandwidthBurst", 0},
  { "DirFetchPostPeriod", "StatusFetchPeriod", 0},
  { "MaxConn", "ConnLimit", 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. */
  const char *description;
} 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 _option_vars[] = {
  VAR("AccountingMax",       MEMUNIT,   AccountingMax,        "0 bytes"),
  VAR("AccountingMaxKB",     UINT,     _AccountingMaxKB,     "0"),
  VAR("AccountingStart",     STRING,   AccountingStart,      NULL),
  VAR("Address",             STRING,   Address,              NULL),
  VAR("AllowUnverifiedNodes",CSV,      AllowUnverifiedNodes, "middle,rendezvous"),
  VAR("AuthoritativeDirectory",BOOL,   AuthoritativeDir,     "0"),
  VAR("BandwidthBurst",      MEMUNIT,  BandwidthBurst,       "5 MB"),
  VAR("BandwidthRate",       MEMUNIT,  BandwidthRate,        "2 MB"),
  VAR("ClientOnly",          BOOL,     ClientOnly,           "0"),
  VAR("ConnLimit",           UINT,     ConnLimit,            "1024"),
  VAR("ContactInfo",         STRING,   ContactInfo,          NULL),
  VAR("ControlPort",         UINT,     ControlPort,          "0"),
  VAR("CookieAuthentication",BOOL,     CookieAuthentication, "0"),
  VAR("DataDirectory",       STRING,   DataDirectory,        NULL),
  VAR("DebugLogFile",        STRING,   DebugLogFile,         NULL),
  VAR("DirAllowPrivateAddresses",BOOL, DirAllowPrivateAddresses, NULL),
  VAR("DirBindAddress",      LINELIST, DirBindAddress,       NULL),
  VAR("DirFetchPeriod",      INTERVAL, DirFetchPeriod,       "0 seconds"),  /** DOCDOC **/
  VAR("DirPolicy",           LINELIST, DirPolicy,            NULL),
  VAR("DirPort",             UINT,     DirPort,              "0"),
  VAR("DirPostPeriod",       INTERVAL, DirPostPeriod,        "20 minutes"),
  VAR("DirServer",           LINELIST, DirServers,           NULL),
  VAR("EntryNodes",          STRING,   EntryNodes,           NULL),
  VAR("ExcludeNodes",        STRING,   ExcludeNodes,         NULL),
  VAR("ExitNodes",           STRING,   ExitNodes,            NULL),
  VAR("ExitPolicy",          LINELIST, ExitPolicy,           NULL),
  VAR("FascistFirewall",     BOOL,     FascistFirewall,      "0"),
  VAR("FirewallPorts",       CSV,      FirewallPorts,        ""),
  VAR("FirewallIPs",         CSV,      FirewallIPs,          NULL),
  VAR("Group",               STRING,   Group,                NULL),
  VAR("HardwareAccel",       BOOL,     HardwareAccel,        "1"),
  VAR("HashedControlPassword",STRING,  HashedControlPassword, NULL),
  VAR("HiddenServiceDir",    LINELIST_S, RendConfigLines,    NULL),
  VAR("HiddenServiceExcludeNodes", LINELIST_S, RendConfigLines, NULL),
  VAR("HiddenServiceNodes",  LINELIST_S, RendConfigLines,    NULL),
  VAR("HiddenServiceOptions",LINELIST_V, RendConfigLines,    NULL),
  VAR("HiddenServicePort",   LINELIST_S, RendConfigLines,    NULL),
  VAR("HttpProxy",           STRING,   HttpProxy,            NULL),
  VAR("HttpProxyAuthenticator",STRING, HttpProxyAuthenticator,NULL),
  VAR("HttpsProxy",          STRING,   HttpsProxy,           NULL),
  VAR("HttpsProxyAuthenticator",STRING,HttpsProxyAuthenticator,NULL),
  VAR("IgnoreVersion",       BOOL,     IgnoreVersion,        "0"),
  VAR("KeepalivePeriod",     INTERVAL, KeepalivePeriod,      "5 minutes"),
  VAR("Log",                 LINELIST, Logs,                 NULL),
  OBSOLETE("LinkPadding"),
  VAR("LogFile",             LINELIST_S, OldLogOptions,      NULL),
  VAR("LogLevel",            LINELIST_S, OldLogOptions,      NULL),
  VAR("LongLivedPorts",      CSV,      LongLivedPorts,       "21,22,706,1863,5050,5190,5222,5223,6667,8300,8888"),
  VAR("MapAddress",          LINELIST, AddressMap,           NULL),
  VAR("MaxAdvertisedBandwidth",MEMUNIT,MaxAdvertisedBandwidth,"128 TB"),
  VAR("MaxCircuitDirtiness", INTERVAL, MaxCircuitDirtiness,  "10 minutes"),
  VAR("MaxOnionsPending",    UINT,     MaxOnionsPending,     "100"),
  VAR("MonthlyAccountingStart",UINT,   _MonthlyAccountingStart,"0"),
  VAR("MyFamily",            STRING,   MyFamily,             NULL),
  VAR("NewCircuitPeriod",    INTERVAL, NewCircuitPeriod,     "30 seconds"),
  VAR("Nickname",            STRING,   Nickname,             NULL),
  VAR("NoPublish",           BOOL,     NoPublish,            "0"),
  VAR("NodeFamily",          LINELIST, NodeFamilies,         NULL),
  VAR("NumCpus",             UINT,     NumCpus,              "1"),
  VAR("NumHelperNodes",      UINT,     NumHelperNodes,       "3"),
  VAR("ORBindAddress",       LINELIST, ORBindAddress,        NULL),
  VAR("ORPort",              UINT,     ORPort,               "0"),
  VAR("OutboundBindAddress", STRING,   OutboundBindAddress,  NULL),
  VAR("PathlenCoinWeight",   DOUBLE,   PathlenCoinWeight,    "0.3"),
  VAR("PidFile",             STRING,   PidFile,              NULL),
  VAR("RecommendedVersions", LINELIST, RecommendedVersions,  NULL),
  VAR("RedirectExit",        LINELIST, RedirectExit,         NULL),
  VAR("RendExcludeNodes",    STRING,   RendExcludeNodes,     NULL),
  VAR("RendNodes",           STRING,   RendNodes,            NULL),
  VAR("RendPostPeriod",      INTERVAL, RendPostPeriod,       "20 minutes"),
  VAR("RephistTrackTime",    INTERVAL, RephistTrackTime,     "24 hours"),
  OBSOLETE("RouterFile"),
  VAR("RunAsDaemon",         BOOL,     RunAsDaemon,          "0"),
  VAR("RunTesting",          BOOL,     RunTesting,           "0"),
  VAR("SafeLogging",         BOOL,     SafeLogging,          "1"),
  VAR("ShutdownWaitLength",  INTERVAL, ShutdownWaitLength,   "30 seconds"),
  VAR("SocksBindAddress",    LINELIST, SocksBindAddress,     NULL),
  VAR("SocksPolicy",         LINELIST, SocksPolicy,          NULL),
  VAR("SocksPort",           UINT,     SocksPort,            "9050"),
  VAR("StatusFetchPeriod",   INTERVAL, StatusFetchPeriod,    "0 seconds"),  /** DOCDOC */
  VAR("StrictEntryNodes",    BOOL,     StrictEntryNodes,     "0"),
  VAR("StrictExitNodes",     BOOL,     StrictExitNodes,      "0"),
  VAR("SysLog",              LINELIST_S, OldLogOptions,      NULL),
  VAR("TrackHostExits",      CSV,      TrackHostExits,       NULL),
  VAR("TrackHostExitsExpire",INTERVAL, TrackHostExitsExpire, "30 minutes"),
  OBSOLETE("TrafficShaping"),
  VAR("UseHelperNodes",      BOOL,     UseHelperNodes,       "0"),
  VAR("User",                STRING,   User,                 NULL),
  VAR("__LeaveStreamsUnattached", BOOL,LeaveStreamsUnattached, "0"),
  { NULL, CONFIG_TYPE_OBSOLETE, 0, NULL }
};
#undef VAR

#define VAR(name,conftype,member,initvalue) \
  { name, CONFIG_TYPE_ ## conftype, STRUCT_OFFSET(or_state_t, member), initvalue }
static config_var_t _state_vars[] = {
  VAR("AccountingBytesReadInterval", MEMUNIT, AccountingBytesReadInInterval,NULL),
  VAR("AccountingBytesWrittenInInterval", MEMUNIT,
      AccountingBytesWrittenInInterval, NULL),
  VAR("AccountingExpectedUsage", MEMUNIT,     AccountingExpectedUsage, NULL),
  VAR("AccountingIntervalStart", ISOTIME,  AccountingIntervalStart, NULL),
  VAR("AccountingSecondsActive", INTERVAL,    AccountingSecondsActive, NULL),
  VAR("HelperNode",              LINELIST_S,  HelperNodes,          NULL),
  VAR("HelperNodeDownSince",     LINELIST_S,  HelperNodes,          NULL),
  VAR("HelperNodeUnlistedSince", LINELIST_S,  HelperNodes,          NULL),
  VAR("HelperNodes",             LINELIST_V,  HelperNodes,          NULL),
  VAR("LastWritten",             ISOTIME,     LastWritten,          NULL),

  { NULL, CONFIG_TYPE_OBSOLETE, 0, NULL }
};

#undef VAR
#undef OBSOLETE

/** DOCDOC*/
typedef struct config_var_description_t {
  const char *name;
  const char *description;
} config_var_description_t;

static config_var_description_t options_description[] = {
  { "Address", "The advertised (external) address we should use." },
  // { "AccountingStart", ""},
  { NULL, NULL },
};

static config_var_description_t state_description[] = {
  { "HelperNode", "One of the nodes we have chosen as a fixed entry" },
  { "HelperNodeDownSince",
    "The last helper node has been down since this time." },
  { "HelperNodeUnlistedSince",
    "The last helper node has been unlisted since this time." },
  { NULL, NULL },
};

typedef int (*validate_fn_t)(void*);

typedef struct {
  size_t size;
  uint32_t magic;
  off_t magic_offset;
  config_abbrev_t *abbrevs;
  config_var_t *vars;
  validate_fn_t validate_fn;
  config_var_description_t *descriptions;
} config_format_t;

#define CHECK(fmt, cfg) do {                                            \
    tor_assert(fmt && cfg);                                             \
    tor_assert((fmt)->magic == *(uint32_t*)(((char*)(cfg))+fmt->magic_offset)); \
  } while (0)

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

static void config_line_append(config_line_t **lst,
                               const char *key, const char *val);
static void option_reset(config_format_t *fmt, or_options_t *options,
                         config_var_t *var);
static void config_free(config_format_t *fmt, void *options);
static int option_is_same(config_format_t *fmt,
                          or_options_t *o1, or_options_t *o2,const char *name);
static or_options_t *options_dup(config_format_t *fmt, 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 void config_register_addressmaps(or_options_t *options);

static int parse_dir_server_line(const char *line, int validate_only);
static int parse_redirect_line(smartlist_t *result,
                               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,
                              config_line_t *level_opt,
                              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 config_line_t *get_assigned_option(config_format_t *fmt,
                                     or_options_t *options, const char *key);
static void config_init(config_format_t *fmt, void *options);
static int or_state_validate(or_state_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);
static int init_libevent(void);
#if defined(HAVE_EVENT_GET_VERSION) && defined(HAVE_EVENT_GET_METHOD)
static void check_libevent_version(const char *m, const char *v, int server);
#endif

#define OR_OPTIONS_MAGIC 9090909

static config_format_t options_format = {
  sizeof(or_options_t),
  OR_OPTIONS_MAGIC,
  STRUCT_OFFSET(or_options_t, _magic),
  _option_abbrevs,
  _option_vars,
  (validate_fn_t)options_validate,
  options_description
};

#define OR_STATE_MAGIC 0x57A73f57

static config_format_t state_format = {
  sizeof(or_state_t),
  OR_STATE_MAGIC,
  STRUCT_OFFSET(or_state_t, _magic),
  NULL,
  _state_vars,
  (validate_fn_t)or_state_validate,
  state_description
};

/*
 * 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;
/** Persistant serialized state. */
static or_state_t *global_state = NULL;

static void *
config_alloc(config_format_t *fmt)
{
  void *opts = opts = tor_malloc_zero(fmt->size);
  *(uint32_t*)(((char*)opts)+fmt->magic_offset) = fmt->magic;
  CHECK(fmt, opts);
  return opts;
}

/** 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)
    config_free(&options_format, global_options);
  global_options = new_val;
}

void
config_free_all(void)
{
  config_free(&options_format, global_options);
  tor_free(config_fname);
}

/** If options->SafeLogging is on, return a not very useful string,
 * else return address.
 */
const char *
safe_str(const char *address)
{
  if (get_options()->SafeLogging)
    return "[scrubbed]";
  else
    return address;
}

/** 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)
{
  config_line_t *cl;
  or_options_t *options = get_options();
  static int libevent_initialized = 0;

  if (options->RunAsDaemon) {
    start_daemon();
  }

  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;
  }

  if (options->EntryNodes && strlen(options->EntryNodes))
    options->UseHelperNodes = 0;

  /* 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 (options_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_ERR, LOG_ERR, control_event_logmsg);
  control_adjust_event_log_severity();

  /* Set up libevent. */
  if (!libevent_initialized) {
    if (init_libevent())
      return -1;
    libevent_initialized = 1;
  }

  /* Load state */
  if (! global_state)
    if (or_state_load())
      return -1;

  options->_ConnLimit =
    set_max_file_descriptors((unsigned)options->ConnLimit, MAXCONNECTIONS);
  if (options->_ConnLimit < 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);
  }

  /* 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(options->DataDirectory);
  }

  /* 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);

  /* Register addressmap directives */
  config_register_addressmaps(options);

  /* 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(0) < 0) {
    log_fn(LOG_ERR,"Failed to bind one of the listener ports.");
    return -1;
  }

  /* 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(config_format_t *fmt, const char *option, int command_line)
{
  int i;
  if (! fmt->abbrevs)
    return option;
  for (i=0; fmt->abbrevs[i].abbreviated; ++i) {
    /* Abbreviations aren't casei. */
    if (!strcasecmp(option,fmt->abbrevs[i].abbreviated) &&
        (command_line || !fmt->abbrevs[i].commandline_only)) {
      return fmt->abbrevs[i].full;
    }
  }
  return option;
}

/** Helper: Read a list of configuration options from the command line. */
static config_line_t *
config_get_commandlines(int argc, char **argv)
{
  config_line_t *front = NULL;
  config_line_t **new = &front;
  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;
    } else if (!strcmp(argv[i],"--nt-service")) {
      i += 1;
      continue;
    }

    *new = tor_malloc_zero(sizeof(config_line_t));
    s = argv[i];

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

    (*new)->key = tor_strdup(expand_abbrev(&options_format, s, 1));
    (*new)->value = tor_strdup(argv[i+1]);
    (*new)->next = NULL;
    log(LOG_DEBUG,"Commandline: parsed keyword '%s', value '%s'",
        (*new)->key, (*new)->value);

    new = &((*new)->next);
    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(config_line_t **lst,
                   const char *key,
                   const char *val)
{
  config_line_t *newline;

  newline = tor_malloc(sizeof(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, config_line_t **result)
{
  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(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(config_line_t *front)
{
  config_line_t *tmp;

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

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

/** DOCDOC */
static const char *
config_find_description(config_format_t *fmt, const char *name)
{
  int i;
  for (i=0; fmt->descriptions[i].name; ++i) {
    if (!strcasecmp(name, fmt->descriptions[i].name))
      return fmt->descriptions[i].description;
  }
  return NULL;
}

/** 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(config_format_t *fmt, const char *key)
{
  int i;
  size_t keylen = strlen(key);
  if (!keylen)
    return NULL; /* if they say "--" on the commandline, it's not an option */
  /* First, check for an exact (case-insensitive) match */
  for (i=0; fmt->vars[i].name; ++i) {
    if (!strcasecmp(key, fmt->vars[i].name)) {
      return &fmt->vars[i];
    }
  }
  /* If none, check for an abbreviated match */
  for (i=0; fmt->vars[i].name; ++i) {
    if (!strncasecmp(key, fmt->vars[i].name, keylen)) {
      log_fn(LOG_WARN, "The abbreviation '%s' is deprecated. "
          "Please use '%s' instead",
             key, fmt->vars[i].name);
      return &fmt->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(config_format_t *fmt,
                   or_options_t *options, config_line_t *c, int reset)
{
  int i, ok;
  config_var_t *var;
  void *lvalue;

  CHECK(fmt, options);

  var = config_find_option(fmt, 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(fmt, 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_ISOTIME:
    if (parse_iso_time(c->value, (time_t *)lvalue)) {
      log(LOG_WARN, "Invalid time '%s' for keyword '%s'", c->value, c->key);
      return -2;
    }
    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((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(config_format_t *fmt, or_options_t *options, const char *key)
{
  config_var_t *var;

  CHECK(fmt, options);

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

  option_reset(fmt, options, var);
}

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

/** Return the canonical name of a configuration option. */
const char *
option_get_canonical_name(const char *key)
{
  config_var_t *var = config_find_option(&options_format, key);
  return var->name;
}

/** Return a canonicalized list of the options assigned for key.
 */
config_line_t *
option_get_assignment(or_options_t *options, const char *key)
{
  return get_assigned_option(&options_format, options, key);
}

static config_line_t *
get_assigned_option(config_format_t *fmt, or_options_t *options, const char *key)
{
  config_var_t *var;
  const void *value;
  char buf[32];
  config_line_t *result;
  tor_assert(options && key);

  CHECK(fmt, options);

  var = config_find_option(fmt, 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 config_line_t *next_in = *(const config_line_t**)value;
    config_line_t **next_out = &result;