/*
 * This file Copyright (C) Mnemosyne LLC
 *
 * This file is licensed by the GPL version 2. Works owned by the
 * Transmission project are granted a special exemption to clause 2 (b)
 * so that the bulk of its code can remain under the MIT license.
 * This exemption does not extend to derived works not owned by
 * the Transmission project.
 *
 * $Id$
 */

#include <assert.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h> /* bsearch (), qsort () */
#include <string.h>

#include <unistd.h> /* close () */

#ifdef WIN32
 #include <w32api.h>
 #define WINVER  WindowsXP
 #include <windows.h>
 #define PROT_READ      PAGE_READONLY
 #define MAP_PRIVATE    FILE_MAP_COPY
#endif

#ifndef WIN32
 #include <sys/mman.h>
#endif
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

#include "transmission.h"
#include "blocklist.h"
#include "log.h"
#include "net.h"
#include "utils.h"

#ifndef O_BINARY
 #define O_BINARY 0
#endif


/***
****  PRIVATE
***/

struct tr_ipv4_range
{
  uint32_t begin;
  uint32_t end;
};

struct tr_blocklistFile
{
  bool                   isEnabled;
  int                    fd;
  size_t                 ruleCount;
  size_t                 byteCount;
  char *                 filename;
  struct tr_ipv4_range * rules;
};

static void
blocklistClose (tr_blocklistFile * b)
{
  if (b->rules != NULL)
    {
      munmap (b->rules, b->byteCount);
      close (b->fd);
      b->rules = NULL;
      b->ruleCount = 0;
      b->byteCount = 0;
      b->fd = -1;
    }
}

static void
blocklistLoad (tr_blocklistFile * b)
{
  int fd;
  size_t byteCount;
  struct stat st;
  char * base;
  const char * err_fmt = _("Couldn't read \"%1$s\": %2$s");

  blocklistClose (b);

  if (stat (b->filename, &st) == -1)
    return;

  fd = open (b->filename, O_RDONLY | O_BINARY);
  if (fd == -1)
    {
      tr_logAddError (err_fmt, b->filename, tr_strerror (errno));
      return;
    }

  byteCount = (size_t) st.st_size;
  b->rules = mmap (NULL, byteCount, PROT_READ, MAP_PRIVATE, fd, 0);
  if (!b->rules)
    {
      tr_logAddError (err_fmt, b->filename, tr_strerror (errno));
      close (fd);
      return;
    }

  b->fd = fd;
  b->byteCount = byteCount;
  b->ruleCount = byteCount / sizeof (struct tr_ipv4_range);

  base = tr_basename (b->filename);
  tr_logAddInfo (_("Blocklist \"%s\" contains %zu entries"), base, b->ruleCount);
  tr_free (base);
}

static void
blocklistEnsureLoaded (tr_blocklistFile * b)
{
  if (b->rules == NULL)
    blocklistLoad (b);
}

static int
compareAddressToRange (const void * va, const void * vb)
{
  const uint32_t * a = va;
  const struct tr_ipv4_range * b = vb;

  if (*a < b->begin) return -1;
  if (*a > b->end) return 1;
  return 0;
}

static void
blocklistDelete (tr_blocklistFile * b)
{
  blocklistClose (b);
  tr_remove (b->filename);
}

/***
****  PACKAGE-VISIBLE
***/

tr_blocklistFile *
tr_blocklistFileNew (const char * filename, bool isEnabled)
{
  tr_blocklistFile * b;

  b = tr_new0 (tr_blocklistFile, 1);
  b->fd = -1;
  b->filename = tr_strdup (filename);
  b->isEnabled = isEnabled;

  return b;
}

const char*
tr_blocklistFileGetFilename (const tr_blocklistFile * b)
{
  return b->filename;
}

void
tr_blocklistFileFree (tr_blocklistFile * b)
{
  blocklistClose (b);
  tr_free (b->filename);
  tr_free (b);
}

int
tr_blocklistFileExists (const tr_blocklistFile * b)
{
  struct stat st;

  return !stat (b->filename, &st);
}

int
tr_blocklistFileGetRuleCount (const tr_blocklistFile * b)
{
  blocklistEnsureLoaded ((tr_blocklistFile*)b);

  return b->ruleCount;
}

int
tr_blocklistFileIsEnabled (tr_blocklistFile * b)
{
  return b->isEnabled;
}

void
tr_blocklistFileSetEnabled (tr_blocklistFile * b, bool isEnabled)
{
  b->isEnabled = isEnabled ? 1 : 0;
}

int
tr_blocklistFileHasAddress (tr_blocklistFile * b, const tr_address * addr)
{
  uint32_t needle;
  const struct tr_ipv4_range * range;

  assert (tr_address_is_valid (addr));

  if (!b->isEnabled || addr->type == TR_AF_INET6)
    return 0;

  blocklistEnsureLoaded (b);

  if (!b->rules || !b->ruleCount)
    return 0;

  needle = ntohl (addr->addr.addr4.s_addr);

  range = bsearch (&needle,
                   b->rules,
                   b->ruleCount,
                   sizeof (struct tr_ipv4_range),
                   compareAddressToRange);

  return range != NULL;
}

/*
 * P2P plaintext format: "comment:x.x.x.x-y.y.y.y"
 * http://wiki.phoenixlabs.org/wiki/P2P_Format
 * http://en.wikipedia.org/wiki/PeerGuardian#P2P_plaintext_format
 */
static bool
parseLine1 (const char * line, struct tr_ipv4_range * range)
{
  char * walk;
  int b[4];
  int e[4];
  char str[64];
  tr_address addr;

  walk = strrchr (line, ':');
  if (!walk)
    return false;
  ++walk; /* walk past the colon */

  if (sscanf (walk, "%d.%d.%d.%d-%d.%d.%d.%d",
              &b[0], &b[1], &b[2], &b[3],
              &e[0], &e[1], &e[2], &e[3]) != 8)
    return false;

  tr_snprintf (str, sizeof (str), "%d.%d.%d.%d", b[0], b[1], b[2], b[3]);
  if (!tr_address_from_string (&addr, str))
    return false;
  range->begin = ntohl (addr.addr.addr4.s_addr);

  tr_snprintf (str, sizeof (str), "%d.%d.%d.%d", e[0], e[1], e[2], e[3]);
  if (!tr_address_from_string (&addr, str))
    return false;
  range->end = ntohl (addr.addr.addr4.s_addr);

  return true;
}

/*
 * DAT format: "000.000.000.000 - 000.255.255.255 , 000 , invalid ip"
 * http://wiki.phoenixlabs.org/wiki/DAT_Format
 */
static bool
parseLine2 (const char * line, struct tr_ipv4_range * range)
{
  int unk;
  int a[4];
  int b[4];
  char str[32];
  tr_address addr;

  if (sscanf (line, "%3d.%3d.%3d.%3d - %3d.%3d.%3d.%3d , %3d , ",
              &a[0], &a[1], &a[2], &a[3],
              &b[0], &b[1], &b[2], &b[3],
              &unk) != 9)
    return false;

  tr_snprintf (str, sizeof (str), "%d.%d.%d.%d", a[0], a[1], a[2], a[3]);
  if (!tr_address_from_string (&addr, str))
    return false;
  range->begin = ntohl (addr.addr.addr4.s_addr);

  tr_snprintf (str, sizeof (str), "%d.%d.%d.%d", b[0], b[1], b[2], b[3]);
  if (!tr_address_from_string (&addr, str))
    return false;
  range->end = ntohl (addr.addr.addr4.s_addr);

  return true;
}

static int
parseLine (const char * line, struct tr_ipv4_range * range)
{
  return parseLine1 (line, range)
      || parseLine2 (line, range);
}

static int
compareAddressRangesByFirstAddress (const void * va, const void * vb)
{
  const struct tr_ipv4_range * a = va;
  const struct tr_ipv4_range * b = vb;
  if (a->begin != b->begin)
    return a->begin < b->begin ? -1 : 1;
  return 0;
}

int
tr_blocklistFileSetContent (tr_blocklistFile * b, const char * filename)
{
  FILE * in;
  FILE * out;
  int inCount = 0;
  char line[2048];
  const char * err_fmt = _("Couldn't read \"%1$s\": %2$s");
  struct tr_ipv4_range * ranges = NULL;
  size_t ranges_alloc = 0;
  size_t ranges_count = 0;

  if (!filename)
    {
      blocklistDelete (b);
      return 0;
    }

  in = fopen (filename, "rb");
  if (in == NULL)
    {
      tr_logAddError (err_fmt, filename, tr_strerror (errno));
      return 0;
    }

  blocklistClose (b);

  out = fopen (b->filename, "wb+");
  if (out == NULL)
    {
      tr_logAddError (err_fmt, b->filename, tr_strerror (errno));
      fclose (in);
      return 0;
    }

  /* load the rules into memory */
  while (fgets (line, sizeof (line), in) != NULL)
    {
      char * walk;
      struct tr_ipv4_range range;

      ++inCount;

      /* zap the linefeed */
      if ((walk = strchr (line, '\r'))) *walk = '\0';
      if ((walk = strchr (line, '\n'))) *walk = '\0';

      if (!parseLine (line, &range))
        {
          /* don't try to display the actual lines - it causes issues */
          tr_logAddError (_("blocklist skipped invalid address at line %d"), inCount);
          continue;
        }

      if (ranges_alloc == ranges_count)
        {
          ranges_alloc += 4096; /* arbitrary */
          ranges = tr_renew (struct tr_ipv4_range, ranges, ranges_alloc);
        }

      ranges[ranges_count++] = range;
    }

  if (ranges_count > 0) /* sort and merge */
    {
      struct tr_ipv4_range * r;
      struct tr_ipv4_range * keep = ranges;
      const struct tr_ipv4_range * end;

      /* sort */
      qsort (ranges, ranges_count, sizeof (struct tr_ipv4_range),
             compareAddressRangesByFirstAddress);

      /* merge */
      for (r=ranges+1, end=ranges+ranges_count; r!=end; ++r) {
        if (keep->end < r->begin)
          *++keep = *r;
        else if (keep->end < r->end)
          keep->end = r->end;
      }

      ranges_count = keep + 1 - ranges;

#ifndef NDEBUG
      /* sanity checks: make sure the rules are sorted
       * in ascending order and don't overlap */
      {
        size_t i;

        for (i=0; i<ranges_count; ++i)
          assert (ranges[i].begin <= ranges[i].end);

        for (i=1; i<ranges_count; ++i)
          assert (ranges[i-1].end < ranges[i].begin);
      }
#endif
    }

  if (fwrite (ranges, sizeof (struct tr_ipv4_range), ranges_count, out) != ranges_count)
    {
      tr_logAddError (_("Couldn't save file \"%1$s\": %2$s"), b->filename, tr_strerror (errno));
    }
  else
    {
      char * base = tr_basename (b->filename);
      tr_logAddInfo (_("Blocklist \"%s\" updated with %zu entries"), base, ranges_count);
      tr_free (base);
    }

  tr_free (ranges);
  fclose (out);
  fclose (in);

  blocklistLoad (b);

  return ranges_count;
}