/* Copyright (c) 2007-2008, The Tor Project, Inc. */
/* See LICENSE for licensing information */
/* $Id: /tor/trunk/src/or/networkstatus.c 15493 2007-12-16T18:33:25.055570Z nickm  $ */
const char geoip_c_id[] =
  "$Id: /tor/trunk/src/or/networkstatus.c 15493 2007-12-16T18:33:25.055570Z nickm  $";

/**
 * \file geoip.c
 * \brief Functions related to maintaining an IP-to-country database and to
 *    summarizing client connections by country.
 */

#define GEOIP_PRIVATE
#include "or.h"
#include "ht.h"

static void clear_geoip_db(void);

/** An entry from the GeoIP file: maps an IP range to a country. */
typedef struct geoip_entry_t {
  uint32_t ip_low; /**< The lowest IP in the range, in host order */
  uint32_t ip_high; /**< The highest IP in the range, in host order */
  int country; /**< An index into geoip_countries */
} geoip_entry_t;

/** A list of lowercased two-letter country codes. */
static smartlist_t *geoip_countries = NULL;
/** A map from lowercased country codes to their position in geoip_countries.
 * The index is encoded in the pointer, and 1 is added so that NULL can mean
 * not found. */
static strmap_t *country_idxplus1_by_lc_code = NULL;
/** A list of all known geoip_entry_t, sorted by ip_low. */
static smartlist_t *geoip_entries = NULL;

/** Add an entry to the GeoIP table, mapping all IPs between <b>low</b> and
 * <b>high</b>, inclusive, to the 2-letter country code <b>country</b>.
 */
static void
geoip_add_entry(uint32_t low, uint32_t high, const char *country)
{
  uintptr_t idx;
  geoip_entry_t *ent;
  void *_idxplus1;

  if (high < low)
    return;

  _idxplus1 = strmap_get_lc(country_idxplus1_by_lc_code, country);

  if (!_idxplus1) {
    char *c = tor_strdup(country);
    tor_strlower(c);
    smartlist_add(geoip_countries, c);
    idx = smartlist_len(geoip_countries) - 1;
    strmap_set_lc(country_idxplus1_by_lc_code, country, (void*)(idx+1));
  } else {
    idx = ((uintptr_t)_idxplus1)-1;
  }
  tor_assert(!strcasecmp(smartlist_get(geoip_countries, idx), country));
  ent = tor_malloc_zero(sizeof(geoip_entry_t));
  ent->ip_low = low;
  ent->ip_high = high;
  ent->country = idx;
  smartlist_add(geoip_entries, ent);
}

/** Add an entry to the GeoIP table, parsing it from <b>line</b>.  The
 * format is as for geoip_load_file. */
/*private*/ int
geoip_parse_entry(const char *line)
{
  unsigned int low, high;
  char b[3];
  if (!geoip_countries) {
    geoip_countries = smartlist_create();
    geoip_entries = smartlist_create();
    country_idxplus1_by_lc_code = strmap_new();
  }
  if (sscanf(line,"%u,%u,%2s", &low, &high, b) == 3) {
    geoip_add_entry(low, high, b);
    return 0;
  } else if (sscanf(line,"\"%u\",\"%u\",\"%2s\",", &low, &high, b) == 3) {
    geoip_add_entry(low, high, b);
    return 0;
  } else {
    log_warn(LD_GENERAL, "Unable to parse line from GEOIP file: %s",
             escaped(line));
    return -1;
  }
}

/** Sorting helper: return -1, 1, or 0 based on comparison of two
 * geoip_entry_t */
static int
_geoip_compare_entries(const void **_a, const void **_b)
{
  const geoip_entry_t *a = *_a, *b = *_b;
  if (a->ip_low < b->ip_low)
    return -1;
  else if (a->ip_low > b->ip_low)
    return 1;
  else
    return 0;
}

/** bsearch helper: return -1, 1, or 0 based on comparison of an IP (a pointer
 * to a uint32_t in host order) to a geoip_entry_t */
static int
_geoip_compare_key_to_entry(const void *_key, const void **_member)
{
  const uint32_t addr = *(uint32_t *)_key;
  const geoip_entry_t *entry = *_member;
  if (addr < entry->ip_low)
    return -1;
  else if (addr > entry->ip_high)
    return 1;
  else
    return 0;
}

/** Clear the GeoIP database and reload it from the file
 * <b>filename</b>. Return 0 on success, -1 on failure.
 *
 * Recognized line formats are:
 *   INTIPLOW,INTIPHIGH,CC
 * and
 *   "INTIPLOW","INTIPHIGH","CC","CC3","COUNTRY NAME"
 * where INTIPLOW and INTIPHIGH are IPv4 addresses encoded as 4-byte unsigned
 * integers, and CC is a country code.
 */
int
geoip_load_file(const char *filename)
{
  FILE *f;
  clear_geoip_db();
  if (!(f = fopen(filename, "r"))) {
    log_warn(LD_GENERAL, "Failed to open GEOIP file %s.", filename);
    return -1;
  }
  geoip_countries = smartlist_create();
  geoip_entries = smartlist_create();
  country_idxplus1_by_lc_code = strmap_new();
  log_info(LD_GENERAL, "Parsing GEOIP file.");
  while (!feof(f)) {
    char buf[512];
    if (fgets(buf, sizeof(buf), f) == NULL)
      break;
    /* FFFF track full country name. */
    geoip_parse_entry(buf);
  }
  /*XXXX020 abort and return -1 if no entries/illformed?*/
  fclose(f);

  smartlist_sort(geoip_entries, _geoip_compare_entries);
  return 0;
}

/** Given an IP address in host order, return a number representing the
 * country to which that address belongs, or -1 for unknown.  The return value
 * will always be less than geoip_get_n_countries().  To decode it,
 * call geoip_get_country_name().
 */
int
geoip_get_country_by_ip(uint32_t ipaddr)
{
  geoip_entry_t *ent;
  if (!geoip_entries)
    return -1;
  ent = smartlist_bsearch(geoip_entries, &ipaddr, _geoip_compare_key_to_entry);
  return ent ? ent->country : -1;
}

/** Return the number of countries recognized by the GeoIP database. */
int
geoip_get_n_countries(void)
{
  return smartlist_len(geoip_countries);
}

/** Return the two-letter country code associated with the number <b>num</b>,
 * or "??" for an unknown value. */
const char *
geoip_get_country_name(int num)
{
  if (geoip_countries && num >= 0 && num < smartlist_len(geoip_countries))
    return smartlist_get(geoip_countries, num);
  else
    return "??";
}

/** Return true iff we have loaded a GeoIP database.*/
int
geoip_is_loaded(void)
{
  return geoip_countries != NULL && geoip_entries != NULL;
}

/** Entry in a map from IP address to the last time we've seen an incoming
 * connection from that IP address. Used by bridges only, to track which
 * countries have them blocked. */
typedef struct clientmap_entry_t {
  HT_ENTRY(clientmap_entry_t) node;
  uint32_t ipaddr;
  time_t last_seen;
} clientmap_entry_t;

/** Map from client IP address to last time seen. */
static HT_HEAD(clientmap, clientmap_entry_t) client_history =
     HT_INITIALIZER();
/** Time at which we started tracking client history. */
static time_t client_history_starts = 0;

/** Hashtable helper: compute a hash of a clientmap_entry_t. */
static INLINE unsigned
clientmap_entry_hash(const clientmap_entry_t *a)
{
  return ht_improve_hash((unsigned) a->ipaddr);
}
/** Hashtable helper: compare two clientmap_entry_t values for equality. */
static INLINE int
clientmap_entries_eq(const clientmap_entry_t *a, const clientmap_entry_t *b)
{
  return a->ipaddr == b->ipaddr;
}

HT_PROTOTYPE(clientmap, clientmap_entry_t, node, clientmap_entry_hash,
             clientmap_entries_eq);
HT_GENERATE(clientmap, clientmap_entry_t, node, clientmap_entry_hash,
            clientmap_entries_eq, 0.6, malloc, realloc, free);

/** Note that we've seen a client connect from the IP <b>addr</b> (host order)
 * at time <b>now</b>. Ignored by all but bridges. */
void
geoip_note_client_seen(uint32_t addr, time_t now)
{
  or_options_t *options = get_options();
  clientmap_entry_t lookup, *ent;
  if (!(options->BridgeRelay && options->BridgeRecordUsageByCountry))
    return;
  lookup.ipaddr = addr;
  ent = HT_FIND(clientmap, &client_history, &lookup);
  if (ent) {
    ent->last_seen = now;
  } else {
    ent = tor_malloc_zero(sizeof(clientmap_entry_t));
    ent->ipaddr = addr;
    ent->last_seen = now;
    HT_INSERT(clientmap, &client_history, ent);
  }
  if (!client_history_starts)
    client_history_starts = now;
}

/** HT_FOREACH helper: remove a clientmap_entry_t from the hashtable if it's
 * older than a certain time. */
static int
_remove_old_client_helper(struct clientmap_entry_t *ent, void *_cutoff)
{
  time_t cutoff = *(time_t*)_cutoff;
  if (ent->last_seen < cutoff) {
    tor_free(ent);
    return 1;
  } else {
    return 0;
  }
}

/** Forget about all clients that haven't connected since <b>cutoff</b>. */
void
geoip_remove_old_clients(time_t cutoff)
{
  clientmap_HT_FOREACH_FN(&client_history,
                          _remove_old_client_helper,
                          &cutoff);
  if (client_history_starts < cutoff)
    client_history_starts = cutoff;
}

/** Do not mention any country from which fewer than this number of IPs have
 * connected.  This avoids reporting information that could deanonymize
 * users. */
#define MIN_IPS_TO_NOTE_COUNTRY 8
/** Do not report any geoip data at all if we have fewer than this number of
 * IPs to report about. */
#define MIN_IPS_TO_NOTE_ANYTHING 16
/** When reporting geoip data about countries, round down to the nearest
 * multiple of this value. */
#define IP_GRANULARITY 8

/** Return the time at which we started recording geoip data. */
time_t
geoip_get_history_start(void)
{
  return client_history_starts;
}

/* Helper type: used to sort results by value. */
typedef struct c_hist_t {
  char country[3];
  unsigned total;
} c_hist_t;

/** Sorting helper: return -1, 1, or 0 based on comparison of two
 * geoip_entry_t.  Sort in descending order of total, and then by country
 * code. */
static int
_c_hist_compare(const void **_a, const void **_b)
{
  const c_hist_t *a = *_a, *b = *_b;
  if (a->total > b->total)
    return -1;
  else if (a->total < b->total)
    return 1;
  else
    return strcmp(a->country, b->country);
}

/** Return a newly allocated comma-separated string containing entries for all
 * the countries from which we've seen enough clients connect. The entry
 * format is cc=num where num is the number of IPs we've seen connecting from
 * that country, and cc is a lowercased country code.  Returns NULL if we don't
 * want to export geoip data yet. */
char *
geoip_get_client_history(time_t now)
{
  char *result = NULL;
  if (!geoip_is_loaded())
    return NULL;
  if (client_history_starts < (now - 12*60*60)) {
    char buf[32];
    smartlist_t *chunks = NULL;
    smartlist_t *entries = NULL;
    int n_countries = geoip_get_n_countries();
    int i;
    clientmap_entry_t **ent;
    unsigned *counts = tor_malloc_zero(sizeof(unsigned)*n_countries);
    unsigned total = 0;
    HT_FOREACH(ent, clientmap, &client_history) {
      int country = geoip_get_country_by_ip((*ent)->ipaddr);
      if (country < 0)
        continue;
      tor_assert(0 <= country && country < n_countries);
      ++counts[country];
      ++total;
    }
    /* Don't record anything if we haven't seen enough IPs. */
    if (total < MIN_IPS_TO_NOTE_ANYTHING)
      goto done;
    /* Make a list of c_hist_t */
    entries = smartlist_create();
    for (i = 0; i < n_countries; ++i) {
      unsigned c = counts[i];
      const char *countrycode;
      c_hist_t *ent;
      /* Only report a country if it has a minimum number of IPs. */
      if (c >= MIN_IPS_TO_NOTE_COUNTRY) {
        /* Round up to the next multiple of IP_GRANULARITY */
        c += IP_GRANULARITY-1;
        c -= c % IP_GRANULARITY;
        countrycode = geoip_get_country_name(i);
        ent = tor_malloc(sizeof(c_hist_t));
        strlcpy(ent->country, countrycode, sizeof(ent->country));
        ent->total = c;
        smartlist_add(entries, ent);
      }
    }
    /* Sort entries. Note that we must do this _AFTER_ rounding, or else
     * the sort order could leak info. */
    smartlist_sort(entries, _c_hist_compare);

    /* Build the result. */
    chunks = smartlist_create();
    SMARTLIST_FOREACH(entries, c_hist_t *, ch, {
        tor_snprintf(buf, sizeof(buf), "%s=%u", ch->country, ch->total);
        smartlist_add(chunks, tor_strdup(buf));
      });
    result = smartlist_join_strings(chunks, ",", 0, NULL);
  done:
    tor_free(counts);
    if (chunks) {
      SMARTLIST_FOREACH(chunks, char *, c, tor_free(c));
      smartlist_free(chunks);
    }
    if (entries) {
      SMARTLIST_FOREACH(entries, c_hist_t *, c, tor_free(c));
      smartlist_free(entries);
    }
  }
  return result;
}

/** Helper used to implement GETINFO ip-to-country/... controller command. */
int
getinfo_helper_geoip(control_connection_t *control_conn,
                     const char *question, char **answer)
{
  (void)control_conn;
  if (geoip_is_loaded() && !strcmpstart(question, "ip-to-country/")) {
    int c;
    uint32_t ip;
    struct in_addr in;
    question += strlen("ip-to-country/");
    if (tor_inet_aton(question, &in) != 0) {
      ip = ntohl(in.s_addr);
      c = geoip_get_country_by_ip(ip);
      *answer = tor_strdup(geoip_get_country_name(c));
    }
  }
  return 0;
}

/** Release all storage held by the GeoIP database. */
static void
clear_geoip_db(void)
{
  if (geoip_countries) {
    SMARTLIST_FOREACH(geoip_countries, char *, cp, tor_free(cp));
    smartlist_free(geoip_countries);
  }
  if (country_idxplus1_by_lc_code)
    strmap_free(country_idxplus1_by_lc_code, NULL);
  if (geoip_entries) {
    SMARTLIST_FOREACH(geoip_entries, geoip_entry_t *, ent, tor_free(ent));
    smartlist_free(geoip_entries);
  }
  geoip_countries = NULL;
  country_idxplus1_by_lc_code = NULL;
  geoip_entries = NULL;
}

/** Release all storage held in this file. */
void
geoip_free_all(void)
{
  clientmap_entry_t **ent, **next, *this;
  for (ent = HT_START(clientmap, &client_history); ent != NULL; ent = next) {
    this = *ent;
    next = HT_NEXT_RMV(clientmap, &client_history, ent);
    tor_free(this);
  }
  HT_CLEAR(clientmap, &client_history);

  clear_geoip_db();
}