buffers.c

关于tor匿名通信的源代码

                   "Rejecting.");
          req->replylen = 2; /* 2 bytes of response */
          req->reply[0] = 5;
          req->reply[1] = '\xFF'; /* reject all methods */
          return -1;
        }
        /* remove packet from buf. also remove any other extraneous
         * bytes, to support broken socks clients. */
        buf_clear(buf);

        req->replylen = 2; /* 2 bytes of response */
        req->reply[0] = 5; /* socks5 reply */
        req->reply[1] = 0; /* tell client to use "none" auth method */
        req->socks_version = 5; /* remember we've already negotiated auth */
        log_debug(LD_APP,"socks5: accepted method 0");
        return 0;
      }
      /* we know the method; read in the request */
      log_debug(LD_APP,"socks5: checking request");
      if (buf->datalen < 8) /* basic info plus >=2 for addr plus 2 for port */
        return 0; /* not yet */
      tor_assert(buf->head->datalen >= 8);
      req->command = (unsigned char) *(buf->head->data+1);
      if (req->command != SOCKS_COMMAND_CONNECT &&
          req->command != SOCKS_COMMAND_RESOLVE &&
          req->command != SOCKS_COMMAND_RESOLVE_PTR) {
        /* not a connect or resolve or a resolve_ptr? we don't support it. */
        log_warn(LD_APP,"socks5: command %d not recognized. Rejecting.",
                 req->command);
        return -1;
      }
      switch (*(buf->head->data+3)) { /* address type */
        case 1: /* IPv4 address */
          log_debug(LD_APP,"socks5: ipv4 address type");
          if (buf->datalen < 10) /* ip/port there? */
            return 0; /* not yet */

          destip = ntohl(*(uint32_t*)(buf->head->data+4));
          in.s_addr = htonl(destip);
          tor_inet_ntoa(&in,tmpbuf,sizeof(tmpbuf));
          if (strlen(tmpbuf)+1 > MAX_SOCKS_ADDR_LEN) {
            log_warn(LD_APP,
                     "socks5 IP takes %d bytes, which doesn't fit in %d. "
                     "Rejecting.",
                     (int)strlen(tmpbuf)+1,(int)MAX_SOCKS_ADDR_LEN);
            return -1;
          }
          strlcpy(req->address,tmpbuf,sizeof(req->address));
          req->port = ntohs(*(uint16_t*)(buf->head->data+8));
          buf_remove_from_front(buf, 10);
          if (req->command != SOCKS_COMMAND_RESOLVE_PTR &&
              !addressmap_have_mapping(req->address) &&
              !have_warned_about_unsafe_socks) {
            log_warn(LD_APP,
                "Your application (using socks5 to port %d) is giving "
                "Tor only an IP address. Applications that do DNS resolves "
                "themselves may leak information. Consider using Socks4A "
                "(e.g. via privoxy or socat) instead. For more information, "
                "please see http://wiki.noreply.org/noreply/TheOnionRouter/"
                "TorFAQ#SOCKSAndDNS.%s", req->port,
                safe_socks ? " Rejecting." : "");
//            have_warned_about_unsafe_socks = 1; // (for now, warn every time)
            control_event_client_status(LOG_WARN,
                          "DANGEROUS_SOCKS PROTOCOL=SOCKS5 ADDRESS=%s:%d",
                          req->address, req->port);
            if (safe_socks)
              return -1;
          }
          return 1;
        case 3: /* fqdn */
          log_debug(LD_APP,"socks5: fqdn address type");
          if (req->command == SOCKS_COMMAND_RESOLVE_PTR) {
            log_warn(LD_APP, "socks5 received RESOLVE_PTR command with "
                     "hostname type. Rejecting.");
            return -1;
          }
          len = (unsigned char)*(buf->head->data+4);
          if (buf->datalen < 7+len) /* addr/port there? */
            return 0; /* not yet */
          buf_pullup(buf, 7+len, 0);
          tor_assert(buf->head->datalen >= 7+len);
          if (len+1 > MAX_SOCKS_ADDR_LEN) {
            log_warn(LD_APP,
                     "socks5 hostname is %d bytes, which doesn't fit in "
                     "%d. Rejecting.", len+1,MAX_SOCKS_ADDR_LEN);
            return -1;
          }
          memcpy(req->address,buf->head->data+5,len);
          req->address[len] = 0;
          req->port = ntohs(get_uint16(buf->head->data+5+len));
          buf_remove_from_front(buf, 5+len+2);
          if (!tor_strisprint(req->address) || strchr(req->address,'\"')) {
            log_warn(LD_PROTOCOL,
                     "Your application (using socks5 to port %d) gave Tor "
                     "a malformed hostname: %s. Rejecting the connection.",
                     req->port, escaped(req->address));
            return -1;
          }
          if (log_sockstype)
            log_notice(LD_APP,
                  "Your application (using socks5 to port %d) gave "
                  "Tor a hostname, which means Tor will do the DNS resolve "
                  "for you. This is good.", req->port);
          return 1;
        default: /* unsupported */
          log_warn(LD_APP,"socks5: unsupported address type %d. Rejecting.",
                   (int) *(buf->head->data+3));
          return -1;
      }
      tor_assert(0);
    case 4: /* socks4 */
      /* http://archive.socks.permeo.com/protocol/socks4.protocol */
      /* http://archive.socks.permeo.com/protocol/socks4a.protocol */

      req->socks_version = 4;
      if (buf->datalen < SOCKS4_NETWORK_LEN) /* basic info available? */
        return 0; /* not yet */
      buf_pullup(buf, 1280, 0);
      req->command = (unsigned char) *(buf->head->data+1);
      if (req->command != SOCKS_COMMAND_CONNECT &&
          req->command != SOCKS_COMMAND_RESOLVE) {
        /* not a connect or resolve? we don't support it. (No resolve_ptr with
         * socks4.) */
        log_warn(LD_APP,"socks4: command %d not recognized. Rejecting.",
                 req->command);
        return -1;
      }

      req->port = ntohs(*(uint16_t*)(buf->head->data+2));
      destip = ntohl(*(uint32_t*)(buf->head->data+4));
      if ((!req->port && req->command!=SOCKS_COMMAND_RESOLVE) || !destip) {
        log_warn(LD_APP,"socks4: Port or DestIP is zero. Rejecting.");
        return -1;
      }
      if (destip >> 8) {
        log_debug(LD_APP,"socks4: destip not in form 0.0.0.x.");
        in.s_addr = htonl(destip);
        tor_inet_ntoa(&in,tmpbuf,sizeof(tmpbuf));
        if (strlen(tmpbuf)+1 > MAX_SOCKS_ADDR_LEN) {
          log_debug(LD_APP,"socks4 addr (%d bytes) too long. Rejecting.",
                    (int)strlen(tmpbuf));
          return -1;
        }
        log_debug(LD_APP,
                  "socks4: successfully read destip (%s)", safe_str(tmpbuf));
        socks4_prot = socks4;
      }

      next = memchr(buf->head->data+SOCKS4_NETWORK_LEN, 0,
                    buf->head->datalen-SOCKS4_NETWORK_LEN);
      if (!next) {
        if (buf->head->datalen >= 1024) {
          log_debug(LD_APP, "Socks4 user name too long; rejecting.");
          return -1;
        }
        log_debug(LD_APP,"socks4: Username not here yet.");
        return 0;
      }
      tor_assert(next < CHUNK_WRITE_PTR(buf->head));

      startaddr = NULL;
      if (socks4_prot != socks4a &&
          !addressmap_have_mapping(tmpbuf) &&
          !have_warned_about_unsafe_socks) {
        log_warn(LD_APP,
                 "Your application (using socks4 to port %d) is giving Tor "
                 "only an IP address. Applications that do DNS resolves "
                 "themselves may leak information. Consider using Socks4A "
                 "(e.g. via privoxy or socat) instead. For more information, "
                 "please see http://wiki.noreply.org/noreply/TheOnionRouter/"
                 "TorFAQ#SOCKSAndDNS.%s", req->port,
                 safe_socks ? " Rejecting." : "");
//      have_warned_about_unsafe_socks = 1; // (for now, warn every time)
        control_event_client_status(LOG_WARN,
                        "DANGEROUS_SOCKS PROTOCOL=SOCKS4 ADDRESS=%s:%d",
                        tmpbuf, req->port);
        if (safe_socks)
          return -1;
      }
      if (socks4_prot == socks4a) {
        if (next+1 == CHUNK_WRITE_PTR(buf->head)) {
          log_debug(LD_APP,"socks4: No part of destaddr here yet.");
          return 0;
        }
        startaddr = next+1;
        next = memchr(startaddr, 0, CHUNK_WRITE_PTR(buf->head)-startaddr);
        if (!next) {
          if (buf->head->datalen >= 1024) {
            log_debug(LD_APP,"socks4: Destaddr too long.");
            return -1;
          }
          log_debug(LD_APP,"socks4: Destaddr not all here yet.");
          return 0;
        }
        if (MAX_SOCKS_ADDR_LEN <= next-startaddr) {
          log_warn(LD_APP,"socks4: Destaddr too long. Rejecting.");
          return -1;
        }
        // tor_assert(next < buf->cur+buf->datalen);

        if (log_sockstype)
          log_notice(LD_APP,
                     "Your application (using socks4a to port %d) gave "
                     "Tor a hostname, which means Tor will do the DNS resolve "
                     "for you. This is good.", req->port);
      }
      log_debug(LD_APP,"socks4: Everything is here. Success.");
      strlcpy(req->address, startaddr ? startaddr : tmpbuf,
              sizeof(req->address));
      if (!tor_strisprint(req->address) || strchr(req->address,'\"')) {
        log_warn(LD_PROTOCOL,
                 "Your application (using socks4 to port %d) gave Tor "
                 "a malformed hostname: %s. Rejecting the connection.",
                 req->port, escaped(req->address));
        return -1;
      }
      /* next points to the final \0 on inbuf */
      buf_remove_from_front(buf, next - buf->head->data + 1);
      return 1;

    case 'G': /* get */
    case 'H': /* head */
    case 'P': /* put/post */
    case 'C': /* connect */
      strlcpy(req->reply,
"HTTP/1.0 501 Tor is not an HTTP Proxy\r\n"
"Content-Type: text/html; charset=iso-8859-1\r\n\r\n"
"<html>\n"
"<head>\n"
"<title>Tor is not an HTTP Proxy</title>\n"
"</head>\n"
"<body>\n"
"<h1>Tor is not an HTTP Proxy</h1>\n"
"<p>\n"
"It appears you have configured your web browser to use Tor as an HTTP proxy."
"\n"
"This is not correct: Tor is a SOCKS proxy, not an HTTP proxy.\n"
"Please configure your client accordingly.\n"
"</p>\n"
"<p>\n"
"See <a href=\"https://www.torproject.org/documentation.html\">"
           "https://www.torproject.org/documentation.html</a> for more "
           "information.\n"
"<!-- Plus this comment, to make the body response more than 512 bytes, so "
"     IE will be willing to display it. Comment comment comment comment "
"     comment comment comment comment comment comment comment comment.-->\n"
"</p>\n"
"</body>\n"
"</html>\n"
             , MAX_SOCKS_REPLY_LEN);
      req->replylen = strlen(req->reply)+1;
      /* fall through */
    default: /* version is not socks4 or socks5 */
      log_warn(LD_APP,
               "Socks version %d not recognized. (Tor is not an http proxy.)",
               *(buf->head->data));
      {
        char *tmp = tor_strndup(buf->head->data, 8); /*XXXX what if longer?*/
        control_event_client_status(LOG_WARN,
                                    "SOCKS_UNKNOWN_PROTOCOL DATA=\"%s\"",
                                    escaped(tmp));
        tor_free(tmp);
      }
      return -1;
  }
}

/** Return 1 iff buf looks more like it has an (obsolete) v0 controller
 * command on it than any valid v1 controller command. */
int
peek_buf_has_control0_command(buf_t *buf)
{
  if (buf->datalen >= 4) {
    char header[4];
    uint16_t cmd;
    peek_from_buf(header, sizeof(header), buf);
    cmd = ntohs(get_uint16(header+2));
    if (cmd <= 0x14)
      return 1; /* This is definitely not a v1 control command. */
  }
  return 0;
}

/** Return the index within <b>buf</b> at which <b>ch</b> first appears,
 * or -1 if <b>ch</b> does not appear on buf. */
static off_t
buf_find_offset_of_char(buf_t *buf, char ch)
{
  chunk_t *chunk;
  off_t offset = 0;
  for (chunk = buf->head; chunk; chunk = chunk->next) {
    char *cp = memchr(chunk->data, ch, chunk->datalen);
    if (cp)
      return offset + (cp - chunk->data);
    else
      offset += chunk->datalen;
  }
  return -1;
}

/** Try to read a single LF-terminated line from <b>buf</b>, and write it,
 * NUL-terminated, into the *<b>data_len</b> byte buffer at <b>data_out</b>.
 * Set *<b>data_len</b> to the number of bytes in the line, not counting the
 * terminating NUL.  Return 1 if we read a whole line, return 0 if we don't
 * have a whole line yet, and return -1 if the line length exceeds
 * *<b>data_len</b>.
 */
int
fetch_from_buf_line(buf_t *buf, char *data_out, size_t *data_len)
{
  size_t sz;
  off_t offset;

  if (!buf->head)
    return 0;

  offset = buf_find_offset_of_char(buf, '\n');
  if (offset < 0)
    return 0;
  sz = (size_t) offset;
  if (sz+2 > *data_len) {
    *data_len = sz + 2;
    return -1;
  }
  fetch_from_buf(data_out, sz+1, buf);
  data_out[sz+1] = '\0';
  *data_len = sz+1;
  return 1;
}

/** Compress on uncompress the <b>data_len</b> bytes in <b>data</b> using the
 * zlib state <b>state</b>, appending the result to <b>buf</b>.  If
 * <b>done</b> is true, flush the data in the state and finish the
 * compression/uncompression.  Return -1 on failure, 0 on success. */
int
write_to_buf_zlib(buf_t *buf, tor_zlib_state_t *state,
                  const char *data, size_t data_len,
                  int done)
{
  char *next;
  size_t old_avail, avail;
  int over = 0;
  do {
    int need_new_chunk = 0;
    if (!buf->tail || ! CHUNK_REMAINING_CAPACITY(buf->tail)) {
      size_t cap = data_len / 4;
      buf_add_chunk_with_capacity(buf, cap, 1);
    }
    next = CHUNK_WRITE_PTR(buf->tail);
    avail = old_avail = CHUNK_REMAINING_CAPACITY(buf->tail);
    switch (tor_zlib_process(state, &next, &avail, &data, &data_len, done)) {
      case TOR_ZLIB_DONE:
        over = 1;
        break;
      case TOR_ZLIB_ERR:
        return -1;
      case TOR_ZLIB_OK:
        if (data_len == 0)
          over = 1;
        break;
      case TOR_ZLIB_BUF_FULL:
        if (avail) {
          /* Zlib says we need more room (ZLIB_BUF_FULL).  Start a new chunk
           * automatically, whether were going to or not. */
          need_new_chunk = 1;
        }
        break;
    }
    buf->datalen += old_avail - avail;
    buf->tail->datalen += old_avail - avail;
    if (need_new_chunk) {
      buf_add_chunk_with_capacity(buf, data_len/4, 1);
    }

  } while (!over);
  check();
  return 0;
}

/** Log an error and exit if <b>buf</b> is corrupted.
 */
void
assert_buf_ok(buf_t *buf)
{
  tor_assert(buf);
  tor_assert(buf->magic == BUFFER_MAGIC);

  if (! buf->head) {
    tor_assert(!buf->tail);
    tor_assert(buf->datalen == 0);
  } else {
    chunk_t *ch;
    size_t total = 0;
    tor_assert(buf->tail);
    for (ch = buf->head; ch; ch = ch->next) {
      total += ch->datalen;
      tor_assert(ch->datalen <= ch->memlen);
      tor_assert(ch->data >= &ch->mem[0]);
      tor_assert(ch->data < &ch->mem[0]+ch->memlen);
      tor_assert(ch->data+ch->datalen <= &ch->mem[0] + ch->memlen);
      if (!ch->next)
        tor_assert(ch == buf->tail);
    }
    tor_assert(buf->datalen == total);
  }
}

#ifdef ENABLE_BUF_FREELISTS
/** Log an error and exit if <b>fl</b> is corrupted.
 */
static void
assert_freelist_ok(chunk_freelist_t *fl)
{
  chunk_t *ch;
  int n;
  tor_assert(fl->alloc_size > 0);
  n = 0;
  for (ch = fl->head; ch; ch = ch->next) {
    tor_assert(CHUNK_ALLOC_SIZE(ch->memlen) == fl->alloc_size);
    ++n;
  }
  tor_assert(n == fl->cur_length);
  tor_assert(n >= fl->lowest_length);
  tor_assert(n <= fl->max_length);
}
#endif