util.c

关于tor匿名通信的源代码

      case '\\':
        if ((cp[1] == 'x' || cp[1] == 'X')
            && TOR_ISXDIGIT(cp[2]) && TOR_ISXDIGIT(cp[3])) {
          cp += 4;
        } else if (TOR_ISODIGIT(cp[1])) {
          cp += 2;
          if (TOR_ISODIGIT(*cp)) ++cp;
          if (TOR_ISODIGIT(*cp)) ++cp;
        } else if (cp[1]) {
          cp += 2;
        } else {
          return NULL;
        }
        break;
      default:
        ++cp;
        break;
    }
  }
 end_of_loop:
  out = *result = tor_malloc(cp-s + 1);
  cp = s+1;
  while (1) {
    switch (*cp)
      {
      case '\"':
        *out = '\0';
        if (size_out) *size_out = out - *result;
        return cp+1;
      case '\0':
        tor_fragile_assert();
        tor_free(*result);
        return NULL;
      case '\\':
        switch (cp[1])
          {
          case 'n': *out++ = '\n'; cp += 2; break;
          case 'r': *out++ = '\r'; cp += 2; break;
          case 't': *out++ = '\t'; cp += 2; break;
          case 'x': case 'X':
            *out++ = ((hex_decode_digit(cp[2])<<4) +
                      hex_decode_digit(cp[3]));
            cp += 4;
            break;
          case '0': case '1': case '2': case '3': case '4': case '5':
          case '6': case '7':
            {
              int n = cp[1]-'0';
              cp += 2;
              if (TOR_ISODIGIT(*cp)) { n = n*8 + *cp-'0'; cp++; }
              if (TOR_ISODIGIT(*cp)) { n = n*8 + *cp-'0'; cp++; }
              if (n > 255) { tor_free(*result); return NULL; }
              *out++ = (char)n;
            }
            break;
          case '\'':
          case '\"':
          case '\\':
          case '\?':
            *out++ = cp[1];
            cp += 2;
            break;
          default:
            tor_free(*result); return NULL;
          }
        break;
      default:
        *out++ = *cp++;
      }
  }
}

/** Given a string containing part of a configuration file or similar format,
 * advance past comments and whitespace and try to parse a single line.  If we
 * parse a line successfully, set *<b>key_out</b> to a new string holding the
 * key portion and *<b>value_out</b> to a new string holding the value portion
 * of the line, and return a pointer to the start of the next line.  If we run
 * out of data, return a pointer to the end of the string.  If we encounter an
 * error, return NULL.
 */
const char *
parse_config_line_from_str(const char *line, char **key_out, char **value_out)
{
  const char *key, *val, *cp;

  tor_assert(key_out);
  tor_assert(value_out);

  *key_out = *value_out = NULL;
  key = val = NULL;
  /* Skip until the first keyword. */
  while (1) {
    while (TOR_ISSPACE(*line))
      ++line;
    if (*line == '#') {
      while (*line && *line != '\n')
        ++line;
    } else {
      break;
    }
  }

  if (!*line) { /* End of string? */
    *key_out = *value_out = NULL;
    return line;
  }

  /* Skip until the next space. */
  key = line;
  while (*line && !TOR_ISSPACE(*line) && *line != '#')
    ++line;
  *key_out = tor_strndup(key, line-key);

  /* Skip until the value. */
  while (*line == ' ' || *line == '\t')
    ++line;

  val = line;

  /* Find the end of the line. */
  if (*line == '\"') {
    if (!(line = unescape_string(line, value_out, NULL)))
       return NULL;
    while (*line == ' ' || *line == '\t')
      ++line;
    if (*line && *line != '#' && *line != '\n')
      return NULL;
  } else {
    while (*line && *line != '\n' && *line != '#')
      ++line;
    if (*line == '\n') {
      cp = line++;
    } else {
      cp = line;
    }
    while (cp>val && TOR_ISSPACE(*(cp-1)))
      --cp;

    tor_assert(cp >= val);
    *value_out = tor_strndup(val, cp-val);
  }

  if (*line == '#') {
    do {
      ++line;
    } while (*line && *line != '\n');
  }
  while (TOR_ISSPACE(*line)) ++line;

  return line;
}

/** Expand any homedir prefix on <b>filename</b>; return a newly allocated
 * string. */
char *
expand_filename(const char *filename)
{
  tor_assert(filename);
  if (*filename == '~') {
    size_t len;
    char *home, *result;
    const char *rest;

    if (filename[1] == '/' || filename[1] == '\0') {
      home = getenv("HOME");
      if (!home) {
        log_warn(LD_CONFIG, "Couldn't find $HOME environment variable while "
                 "expanding \"%s\"", filename);
        return NULL;
      }
      home = tor_strdup(home);
      rest = strlen(filename)>=2?(filename+2):"";
    } else {
#ifdef HAVE_PWD_H
      char *username, *slash;
      slash = strchr(filename, '/');
      if (slash)
        username = tor_strndup(filename+1,slash-filename-1);
      else
        username = tor_strdup(filename+1);
      if (!(home = get_user_homedir(username))) {
        log_warn(LD_CONFIG,"Couldn't get homedir for \"%s\"",username);
        tor_free(username);
        return NULL;
      }
      tor_free(username);
      rest = slash ? (slash+1) : "";
#else
      log_warn(LD_CONFIG, "Couldn't expend homedir on system without pwd.h");
      return tor_strdup(filename);
#endif
    }
    tor_assert(home);
    /* Remove trailing slash. */
    if (strlen(home)>1 && !strcmpend(home,PATH_SEPARATOR)) {
      home[strlen(home)-1] = '\0';
    }
    /* Plus one for /, plus one for NUL.
     * Round up to 16 in case we can't do math. */
    len = strlen(home)+strlen(rest)+16;
    result = tor_malloc(len);
    tor_snprintf(result,len,"%s"PATH_SEPARATOR"%s",home,rest);
    tor_free(home);
    return result;
  } else {
    return tor_strdup(filename);
  }
}

/** Return a new list containing the filenames in the directory <b>dirname</b>.
 * Return NULL on error or if <b>dirname</b> is not a directory.
 */
smartlist_t *
tor_listdir(const char *dirname)
{
  smartlist_t *result;
#ifdef MS_WINDOWS
  char *pattern;
  HANDLE handle;
  WIN32_FIND_DATA findData;
  size_t pattern_len = strlen(dirname)+16;
  pattern = tor_malloc(pattern_len);
  tor_snprintf(pattern, pattern_len, "%s\\*", dirname);
  if (INVALID_HANDLE_VALUE == (handle = FindFirstFile(pattern, &findData))) {
    tor_free(pattern);
    return NULL;
  }
  result = smartlist_create();
  while (1) {
    if (strcmp(findData.cFileName, ".") &&
        strcmp(findData.cFileName, "..")) {
      smartlist_add(result, tor_strdup(findData.cFileName));
    }
    if (!FindNextFile(handle, &findData)) {
      if (GetLastError() != ERROR_NO_MORE_FILES) {
        /* XXX021 can we say what the error is? */
        log_warn(LD_FS, "Error reading directory '%s'.", dirname);
      }
      break;
    }
  }
  FindClose(handle);
  tor_free(pattern);
#else
  DIR *d;
  struct dirent *de;
  if (!(d = opendir(dirname)))
    return NULL;

  result = smartlist_create();
  while ((de = readdir(d))) {
    if (!strcmp(de->d_name, ".") ||
        !strcmp(de->d_name, ".."))
      continue;
    smartlist_add(result, tor_strdup(de->d_name));
  }
  closedir(d);
#endif
  return result;
}

/** Return true iff <b>filename</b> is a relative path. */
int
path_is_relative(const char *filename)
{
  if (filename && filename[0] == '/')
    return 0;
#ifdef MS_WINDOWS
  else if (filename && filename[0] == '\\')
    return 0;
  else if (filename && strlen(filename)>3 && TOR_ISALPHA(filename[0]) &&
           filename[1] == ':' && filename[2] == '\\')
    return 0;
#endif
  else
    return 1;
}

/* =====
 * Net helpers
 * ===== */

/** Return true iff <b>ip</b> (in host order) is an IP reserved to localhost,
 * or reserved for local networks by RFC 1918.
 */
int
is_internal_IP(uint32_t ip, int for_listening)
{
  tor_addr_t myaddr;
  myaddr.family = AF_INET;
  myaddr.addr.in_addr.s_addr = htonl(ip);

  return tor_addr_is_internal(&myaddr, for_listening);
}

/** Return true iff <b>ip</b> is an IP reserved to localhost or local networks
 * in RFC1918 or RFC4193 or RFC4291. (fec0::/10, deprecated by RFC3879, is
 * also treated as internal for now.)
 */
int
tor_addr_is_internal(const tor_addr_t *addr, int for_listening)
{
  uint32_t iph4 = 0;
  uint32_t iph6[4];
  sa_family_t v_family;
  v_family = IN_FAMILY(addr);

  if (v_family == AF_INET) {
    iph4 = IPV4IPh(addr);
  } else if (v_family == AF_INET6) {
    if (tor_addr_is_v4(addr)) { /* v4-mapped */
      v_family = AF_INET;
      iph4 = ntohl(IN6_ADDRESS32(addr)[3]);
    }
  }

  if (v_family == AF_INET6) {
    iph6[0] = ntohl(IN6_ADDRESS32(addr)[0]);
    iph6[1] = ntohl(IN6_ADDRESS32(addr)[1]);
    iph6[2] = ntohl(IN6_ADDRESS32(addr)[2]);
    iph6[3] = ntohl(IN6_ADDRESS32(addr)[3]);
    if (for_listening && !iph6[0] && !iph6[1] && !iph6[2] && !iph6[3]) /* :: */
      return 0;

    if (((iph6[0] & 0xfe000000) == 0xfc000000) || /* fc00/7  - RFC4193 */
        ((iph6[0] & 0xffc00000) == 0xfe800000) || /* fe80/10 - RFC4291 */
        ((iph6[0] & 0xffc00000) == 0xfec00000))   /* fec0/10 D- RFC3879 */
      return 1;

    if (!iph6[0] && !iph6[1] && !iph6[2] &&
        ((iph6[3] & 0xfffffffe) == 0x00000000))  /* ::/127 */
      return 1;

    return 0;
  } else if (v_family == AF_INET) {
    if (for_listening && !iph4) /* special case for binding to 0.0.0.0 */
      return 0;
    if (((iph4 & 0xff000000) == 0x0a000000) || /*       10/8 */
        ((iph4 & 0xff000000) == 0x00000000) || /*        0/8 */
        ((iph4 & 0xff000000) == 0x7f000000) || /*      127/8 */
        ((iph4 & 0xffff0000) == 0xa9fe0000) || /* 169.254/16 */
        ((iph4 & 0xfff00000) == 0xac100000) || /*  172.16/12 */
        ((iph4 & 0xffff0000) == 0xc0a80000))   /* 192.168/16 */
      return 1;
    return 0;
  }

  /* unknown address family... assume it's not safe for external use */
  /* rather than tor_assert(0) */
  log_warn(LD_BUG, "tor_addr_is_internal() called with a non-IP address.");
  return 1;
}

#if 0
/** Convert a tor_addr_t <b>addr</b> into a string, and store it in
 *  <b>dest</b> of size <b>len</b>.  Returns a pointer to dest on success,
 *  or NULL on failure.
 */
void
tor_addr_to_str(char *dest, const tor_addr_t *addr, int len)
{
  const char *ptr;
  tor_assert(addr && dest);

  switch (IN_FAMILY(addr)) {
    case AF_INET:
      ptr = tor_inet_ntop(AF_INET, &addr->sa.sin_addr, dest, len);
      break;
    case AF_INET6:
      ptr = tor_inet_ntop(AF_INET6, &addr->sa6.sin6_addr, dest, len);
      break;
    default:
      return NULL;
  }
  return ptr;
}
#endif

/** Parse a string of the form "host[:port]" from <b>addrport</b>.  If
 * <b>address</b> is provided, set *<b>address</b> to a copy of the
 * host portion of the string.  If <b>addr</b> is provided, try to
 * resolve the host portion of the string and store it into
 * *<b>addr</b> (in host byte order).  If <b>port_out</b> is provided,
 * store the port number into *<b>port_out</b>, or 0 if no port is given.
 * If <b>port_out</b> is NULL, then there must be no port number in
 * <b>addrport</b>.
 * Return 0 on success, -1 on failure.
 */
int
parse_addr_port(int severity, const char *addrport, char **address,
                uint32_t *addr, uint16_t *port_out)
{
  const char *colon;
  char *_address = NULL;
  int _port;
  int ok = 1;

  tor_assert(addrport);

  colon = strchr(addrport, ':');
  if (colon) {
    _address = tor_strndup(addrport, colon-addrport);
    _port = (int) tor_parse_long(colon+1,10,1,65535,NULL,NULL);
    if (!_port) {
      log_fn(severity, LD_GENERAL, "Port %s out of range", escaped(colon+1));
      ok = 0;
    }
    if (!port_out) {
      char *esc_addrport = esc_for_log(addrport);
      log_fn(severity, LD_GENERAL,
             "Port %s given on %s when not required",
             escaped(colon+1), esc_addrport);
      tor_free(esc_addrport);
      ok = 0;
    }
  } else {
    _address = tor_strdup(addrport);
    _port = 0;
  }

  if (addr) {
    /* There's an addr pointer, so we need to resolve the hostname. */
    if (tor_lookup_hostname(_address,addr)) {
      log_fn(severity, LD_NET, "Couldn't look up %s", escaped(_address));
      ok = 0;
      *addr = 0;
    }
  }

  if (address && ok) {
    *address = _address;
  } else {
    if (address)
      *address = NULL;
    tor_free(_address);
  }
  if (port_out)
    *port_out = ok ? ((uint16_t) _port) : 0;

  return ok ? 0 : -1;
}

/** If <b>mask</b> is an address mask for a bit-prefix, return the number of
 * bits.  Otherwise, return -1. */
int
addr_mask_get_bits(uint32_t mask)
{
  int i;
  if (mask == 0)
    return 0;
  if (mask == 0xFFFFFFFFu)
    return 32;
  for (i=0; i<=32; ++i) {
    if (mask == (uint32_t) ~((1u<<(32-i))-1)) {
      return i;
    }
  }
  return -1;
}

/** Compare two addresses <b>a1</b> and <b>a2</b> for equality under a
 *  etmask of <b>mbits</b> bits.  Return -1, 0, or 1.
 *
 * XXXX_IP6 Temporary function to allow masks as bitcounts everywhere.  This
 * will be replaced with an IPv6-aware version as soon as 32-bit addresses are
 * no lo