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;
  int warn;
} 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, 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, 0},
  { "BandwidthRateBytes", "BandwidthRate", 0, 0},
  { "BandwidthBurstBytes", "BandwidthBurst", 0, 0},
  { "DirFetchPostPeriod", "StatusFetchPeriod", 0, 0},
  { "MaxConn", "ConnLimit", 0, 1},
  { "ORBindAddress", "ORListenAddress", 0, 0},
  { "DirBindAddress", "DirListenAddress", 0, 0},
  { "SocksBindAddress", "SocksListenAddress", 0, 0},
  { "UseHelperNodes", "UseEntryGuards", 0, 0},
  { "NumHelperNodes", "NumEntryGuards", 0, 0},
  { "UseEntryNodes", "UseEntryGuards", 0, 0},
  { "NumEntryNodes", "NumEntryGuards", 0, 0},
  { NULL, NULL, 0, 0},
};
/* A list of state-file abbreviations, for compatibility. */
static config_abbrev_t _state_abbrevs[] = {
  { "AccountingBytesReadInterval", "AccountingBytesReadInInterval", 0, 0 },
  { "HelperNode", "EntryGuard", 0, 0 },
  { "HelperNodeDownSince", "EntryGuardDownSince", 0, 0 },
  { "HelperNodeUnlistedSince", "EntryGuardUnlistedSince", 0, 0 },
  { "EntryNode", "EntryGuard", 0, 0 },
  { "EntryNodeDownSince", "EntryGuardDownSince", 0, 0 },
  { "EntryNodeUnlistedSince", "EntryGuardUnlistedSince", 0, 0 },
  { NULL, NULL, 0, 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 _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("AssumeReachable",     BOOL,     AssumeReachable,      "0"),
  VAR("AuthDirInvalid",      LINELIST, AuthDirInvalid,       NULL),
  VAR("AuthDirReject",       LINELIST, AuthDirReject,        NULL),
  VAR("AuthDirRejectUnlisted",BOOL,    AuthDirRejectUnlisted,"0"),
  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("DirListenAddress",    LINELIST, DirListenAddress,     NULL),
  /* if DirFetchPeriod is 0, see get_dir_fetch_period() in main.c */
  VAR("DirFetchPeriod",      INTERVAL, DirFetchPeriod,       "0 seconds"),
  VAR("DirPolicy",           LINELIST, DirPolicy,            NULL),
  VAR("DirPort",             UINT,     DirPort,              "0"),
  OBSOLETE("DirPostPeriod"),
  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("FastFirstHopPK",      BOOL,     FastFirstHopPK,       "1"),
  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),
  OBSOLETE("IgnoreVersion"),
  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"),
  OBSOLETE("MonthlyAccountingStart"),
  VAR("MyFamily",            STRING,   MyFamily,             NULL),
  VAR("NewCircuitPeriod",    INTERVAL, NewCircuitPeriod,     "30 seconds"),
  VAR("NamingAuthoritativeDirectory",BOOL, NamingAuthoritativeDir, "0"),
  VAR("Nickname",            STRING,   Nickname,             NULL),
  VAR("NoPublish",           BOOL,     NoPublish,            "0"),
  VAR("NodeFamily",          LINELIST, NodeFamilies,         NULL),
  VAR("NumCpus",             UINT,     NumCpus,              "1"),
  VAR("NumEntryGuards",      UINT,     NumEntryGuards,       "3"),
  VAR("ORListenAddress",     LINELIST, ORListenAddress,      NULL),
  VAR("ORPort",              UINT,     ORPort,               "0"),
  VAR("OutboundBindAddress", STRING,   OutboundBindAddress,  NULL),
  VAR("PathlenCoinWeight",   DOUBLE,   PathlenCoinWeight,    "0.3"),
  VAR("PidFile",             STRING,   PidFile,              NULL),
  VAR("ProtocolWarnings",    BOOL,     ProtocolWarnings,     "0"),
  VAR("ReachableAddresses",  LINELIST, ReachableAddresses,   NULL),
  VAR("RecommendedVersions", LINELIST, RecommendedVersions,  NULL),
  VAR("RecommendedClientVersions", LINELIST, RecommendedClientVersions,  NULL),
  VAR("RecommendedServerVersions", LINELIST, RecommendedServerVersions,  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("SocksListenAddress",  LINELIST, SocksListenAddress,   NULL),
  VAR("SocksPolicy",         LINELIST, SocksPolicy,          NULL),
  VAR("SocksPort",           UINT,     SocksPort,            "9050"),
  /* if StatusFetchPeriod is 0, see get_status_fetch_period() in main.c */
  VAR("StatusFetchPeriod",   INTERVAL, StatusFetchPeriod,    "0 seconds"),
  VAR("StrictEntryNodes",    BOOL,     StrictEntryNodes,     "0"),
  VAR("StrictExitNodes",     BOOL,     StrictExitNodes,      "0"),
  VAR("SysLog",              LINELIST_S, OldLogOptions,      NULL),
  VAR("TestSocks",           BOOL,     TestSocks,            "0"),
  VAR("TrackHostExits",      CSV,      TrackHostExits,       NULL),
  VAR("TrackHostExitsExpire",INTERVAL, TrackHostExitsExpire, "30 minutes"),
  OBSOLETE("TrafficShaping"),
  VAR("UseEntryGuards",      BOOL,     UseEntryGuards,       "1"),
  VAR("User",                STRING,   User,                 NULL),
  VAR("V1AuthoritativeDirectory",BOOL, V1AuthoritativeDir,   "0"),
  VAR("VersioningAuthoritativeDirectory",BOOL,VersioningAuthoritativeDir, "0"),
  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("AccountingBytesReadInInterval", MEMUNIT,
      AccountingBytesReadInInterval, NULL),
  VAR("AccountingBytesWrittenInInterval", MEMUNIT,
      AccountingBytesWrittenInInterval, NULL),
  VAR("AccountingExpectedUsage", MEMUNIT,     AccountingExpectedUsage, NULL),
  VAR("AccountingIntervalStart", ISOTIME,     AccountingIntervalStart, NULL),
  VAR("AccountingSecondsActive", INTERVAL,    AccountingSecondsActive, NULL),
  VAR("EntryGuard",              LINELIST_S,  EntryGuards,             NULL),
  VAR("EntryGuardDownSince",     LINELIST_S,  EntryGuards,             NULL),
  VAR("EntryGuardUnlistedSince", LINELIST_S,  EntryGuards,             NULL),
  VAR("EntryGuards",             LINELIST_V,  EntryGuards,             NULL),

  VAR("BWHistoryReadEnds",       ISOTIME,     BWHistoryReadEnds,      NULL),
  VAR("BWHistoryReadInterval",   UINT,        BWHistoryReadInterval,  NULL),
  VAR("BWHistoryReadValues",     CSV,         BWHistoryReadValues,    NULL),
  VAR("BWHistoryWriteEnds",      ISOTIME,     BWHistoryWriteEnds,     NULL),
  VAR("BWHistoryWriteInterval",  UINT,        BWHistoryWriteInterval, NULL),
  VAR("BWHistoryWriteValues",    CSV,         BWHistoryWriteValues,   NULL),

  VAR("TorVersion",              STRING,      TorVersion,             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[] = {
  { "AccountingBytesReadInterval",
    "How many bytes have we read in this accounting period?" },
  { "AccountingBytesWrittenInInterval",
    "How many bytes have we written in this accounting period?" },
  { "AccountingExpectedUsage",
    "How many bytes did we expect to use per minute? (0 for no estimate.)" },
  { "AccountingIntervalStart", "When did this accounting period begin?" },
  { "AccountingSecondsActive", "How long have we been awake in this period?" },

  { "BWHistoryReadEnds", "When does the last-recorded read-interval end?" },
  { "BWHistoryReadInterval", "How long is each read-interval (in seconds)?" },
  { "BWHistoryReadValues", "Number of bytes read in each interval." },
  { "BWHistoryWriteEnds", "When does the last-recorded write-interval end?" },
  { "BWHistoryWriteInterval", "How long is each write-interval (in seconds)?"},
  { "BWHistoryWriteValues", "Number of bytes written in each interval." },

  { "EntryGuard", "One of the nodes we have chosen as a fixed entry" },
  { "EntryGuardDownSince",
    "The last entry guard has been down since this time." },
  { "EntryGuardUnlistedSince",
    "The last entry guard has been unlisted since this time." },
  { "LastWritten", "When was this state file last regenerated?" },

  { "TorVersion", "Which version of Tor generated this state file?" },
  { NULL, NULL },
};

typedef int (*validate_fn_t)(void*,void*,int);

/** Information on the keys, value types, key-to-struct-member mappings,
 * variable descriptions, validation functions, and abbreviations for a
 * configuration or storage format. */
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_clear(config_format_t *fmt, or_options_t *options,
                         config_var_t *var);
static void option_reset(config_format_t *fmt, or_options_t *options,
                         config_var_t *var, int use_defaults);
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 *old_options,
                            or_options_t *options, int from_setconf);
static int options_act_reversible(or_options_t *old_options);
static int options_act(or_options_t *old_options);
static int options_transition_allowed(or_options_t *old, or_options_t *new);
static int options_transition_affects_workers(or_options_t *old_options,
                                              or_options_t *new_options);
static int options_transition_affects_descriptor(or_options_t *old_options,
                                                 or_options_t *new_options);
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 *old_options, or_state_t *options,
                             int from_setconf);

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 void parse_reachable_addresses(void);
static int init_libevent(void);
static int opt_streq(const char *s1, const char *s2);
#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

/*static*/ or_options_t *options_new(void);

#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),
  _state_abbrevs,
  _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 *torrc_fname = NULL;
/** Persistent serialized state. */
static or_state_t *global_state = NULL;
/** DOCDOC */
static addr_policy_t *reachable_addr_policy = 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; take action based on the new value; free the old value
 * as necessary.
 */
int
set_options(or_options_t *new_val)
{
  or_options_t *old_options = global_options;
  global_options = new_val;
  /* Note that we pass the *old* options below, for comparison. It
   * pulls the new options directly out of global_options. */
  if (options_act_reversible(old_options)<0) {
    global_options = old_options;
    return -1;
  }
  if (options_act(old_options) < 0) { /* acting on the options failed. die. */
    err(LD_CONFIG,
        "Acting on config options left us in a broken state. Dying.");
    exit(1);
  }
  if (old_options)
    config_free(&options_format, old_options);

  return 0;
}

void
config_free_all(void)
{
  if (global_options) {
    config_free(&options_format, global_options);
    global_options = NULL;
  }
  if (global_state) {
    config_free(&state_format, global_state);
    global_state = NULL;
  }
  tor_free(torrc_fname);
  if (reachable_addr_policy) {
    addr_policy_free(reachable_addr_policy);
    reachable_addr_policy = NULL;
  }
}

/** 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;
}

/** Add the default directory servers directly into the trusted dir list. */
static void
add_default_trusted_dirservers(void)
{
  const char *dirservers[] = {
"moria1 v1 18.244.0.188:9031 "
                           "FFCB 46DB 1339 DA84 674C 70D7 CB58 6434 C437 0441",
"moria2 v1 18.244.0.114:80  719B E45D E224 B607 C537 07D0 E214 3E2D 423E 74CF",
"tor26 v1 86.59.21.38:80    847B 1F85 0344 D787 6491 A548 92F9 0493 4E4E B85D"
  };
  parse_dir_server_line(dirservers[0], 0);
  parse_dir_server_line(dirservers[1], 0);
  parse_dir_server_line(dirservers[2], 0);
}

/** Fetch the active option list, and take actions based on it. All of the
 * things we do should survive being done repeatedly.  If present,
 * <b>old_options</b> contains the previous value of the options.
 *
 * Return 0 if all goes well, return -1 if things went badly.
 */
static int
options_act_reversible(or_options_t *old_options)
{
  smartlist_t *new_listeners = smartlist_create();
  smartlist_t *replaced_listeners = smartlist_create();
  static int libevent_initialized = 0;
  or_options_t *options = get_options();
  int running_tor = options->command == CMD_RUN_TOR;
  int set_conn_limit = 0;
  int r = -1;

  if (running_tor && options->RunAsDaemon) {
    /* No need to roll back, since you can't change the value. */
    start_daemon();
  }

  /* Setuid/setgid as appropriate */
  if (options->User || options->Group) {
    if (switch_id(options->User, options->Group) != 0) {
      /* No need to roll back, since you can't change the value. */
      goto done;
    }
  }

  /* Set up libevent. */
  if (running_tor && !libevent_initialized) {
    if (init_libevent())
      goto done;
    libevent_initialized = 1;
  }

  /* Ensure data directory is private; create if possible. */
  if (check_private_dir(options->DataDirectory, CPD_CREATE)<0) {
    err(LD_FS, "Couldn't access/create private data directory \"%s\"",
        options->DataDirectory);
    /* No need to roll back, since you can't change the value. */
    goto done;
  }

  /* Bail out at this point if we're not going to be a client or server:
   * we don't run  */
  if (options->command != CMD_RUN_TOR)
    goto commit;

  options->_ConnLimit =
    set_max_file_descriptors((unsigned)options->ConnLimit, MAXCONNECTIONS);
  if (options->_ConnLimit < 0)
    goto rollback;
  set_conn_limit = 1;

  if (retry_all_listeners(0, replaced_listeners, new_listeners) < 0) {
    err(LD_CONFIG, "Failed to bind one of the listener ports.");
    goto rollback;
  }

 commit:
  r = 0;
  SMARTLIST_FOREACH(replaced_listeners, connection_t *, conn,
  {
    notice(LD_NET, "Closing old %s on %s:%d",
           conn_type_to_string(conn->type), conn->address, conn->port);
    connection_close_immediate(conn);
    connection_mark_for_close(conn);
  });
  goto done;

 rollback:
  r = -1;

  if (set_conn_limit && old_options)
    set_max_file_descriptors((unsigned)old_options->ConnLimit,MAXCONNECTIONS);

  SMARTLIST_FOREACH(new_listeners, connection_t *, conn,
  {
    notice(LD_NET, "Closing %s on %s:%d",
           conn_type_to_string(conn->type), conn->address, conn->port);
    connection_close_immediate(conn);
    connection_mark_for_close(conn);
  });

 done:
  smartlist_free(new_listeners);
  smartlist_free(replaced_listeners);
  return r;
}

/** Fetch the active option list, and take actions based on it. All of the
 * things we do should survive being done repeatedly.  If present,
 * <b>old_options</b> contains the previous value of the options.
 *
 * Return 0 if all goes well, return -1 if it's time to die.
 *
 * Note 2: We haven't moved all the "act on new configuration" logic
 * here yet.  Some is still in do_hup() and other places.
 */
static int
options_act(or_options_t *old_options)
{
  config_line_t *cl;
  char *fn;
  size_t len;
  or_options_t *options = get_options();
  int running_tor = options->command == CMD_RUN_TOR;

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

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

  if (running_tor) {
    len = strlen(options->DataDirectory)+32;
    fn = tor_malloc(len);
    tor_snprintf(fn, len, "%s/cached-status", options->DataDirectory);
    if (check_private_dir(fn, CPD_CREATE) != 0) {
      err(LD_CONFIG,
          "Couldn't access/create private data directory \"%s\"", fn);
      tor_free(fn);
      return -1;
    }
    tor_free(fn);
  }

  /* Bail out at this point if we're not going to be a client or 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();

  /* Load state */
  if (! global_state)
    if (or_state_load())
      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 (running_tor && 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 (running_tor && options->PidFile)
    write_pidfile(options->PidFile);

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

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

  init_cookie_authentication(options->CookieAuthentication);

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

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

  if (!running_tor)
    return 0;

  /* Check for transitions that need action. */
  if (old_options) {
    if (options->UseEntryGuards && !old_options->UseEntryGuards) {
      info(LD_CIRC,"Switching to entry guards; abandoning previous circuits");
      circuit_mark_all_unused_circs();
      circuit_expire_all_dirty_circs();
    }

    if (options_transition_affects_workers(old_options, options)) {
      info(LD_GENERAL,"Worker-related options changed. Rotating workers.");
      cpuworkers_rotate();
      dnsworkers_rotate();
    }
  }

  /* Check if we need to parse and add the EntryNodes config option. */
  if (options->EntryNodes &&
      (!old_options ||
       !opt_streq(old_options->EntryNodes, options->EntryNodes)))
    entry_nodes_should_be_added();

  /* Since our options changed, we might need to regenerate and upload our
   * server descriptor.
   */
  if (!old_options ||
      options_transition_affects_descriptor(old_options, options))
    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.
 * If <b>warn_obsolete</b> is set, warn about deprecated names. */
static const char *
expand_abbrev(config_format_t *fmt, const char *option, int command_line,
              int warn_obsolete)
{
  int i;
  if (! fmt->abbrevs)
    return option;
  for (i=0; fmt->abbrevs[i].abbreviated; ++i) {
    /* Abbreviations are casei. */
    if (!strcasecmp(option,fmt->abbrevs[i].abbreviated) &&
        (command_line || !fmt->abbrevs[i].commandline_only)) {
      if (warn_obsolete && fmt->abbrevs[i].warn) {
        warn(LD_CONFIG,
             "The configuration option '%s' is deprecated; use '%s' instead.",
             fmt->abbrevs[i].abbreviated,
             fmt->abbrevs[i].full);
      }
      return fmt->abbrevs[i].full;
    }
  }
  return option;
}

/** Helper: Read a list of configuration options from the command line.
 * If successful, put them in *<b>result</b> and return 0, and return
 * -1 and leave *<b>result</b> alone. */
static int
config_get_commandlines(int argc, char **argv, config_line_t **result)
{
  config_line_t *front = NULL;
  config_line_t **new = &front;
  char *s;
  int i = 1;

  while (i < argc) {
    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;
    }
    if (i == argc-1) {
      warn(LD_CONFIG,"Command-line option '%s' with no value. Failing.",
           argv[i]);
      config_free_lines(front);
      return -1;
    }

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

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

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

    new = &((*new)->next);
    i += 2;
  }
  *result = front;
  return 0;
}

/** 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 (