src/core/proto/proto_control0.c

   1 /* Copyright (c) 2001 Matej Pfajfar.
   2  * Copyright (c) 2001-2004, Roger Dingledine.
   3  * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
   4  * Copyright (c) 2007-2021, The Tor Project, Inc. */
   5 /* See LICENSE for licensing information */
   6
   7 /**
   8  * @file proto_control0.c
   9  * @brief Code to detect the obsolete v0 control protocol.
  10  **/
  11
  12 #include "core/or/or.h"
  13 #include "lib/buf/buffers.h"
  14 #include "core/proto/proto_control0.h"
  15
  16 /** Return 1 iff buf looks more like it has an (obsolete) v0 controller
  17  * command on it than any valid v1 controller command. */
  18 int
  19 peek_buf_has_control0_command(buf_t *buf)
  20 {
  21   if (buf_datalen(buf) >= 4) {
  22     char header[4];
  23     uint16_t cmd;
  24     buf_peek(buf, header, sizeof(header));
  25     cmd = ntohs(get_uint16(header+2));
  26     if (cmd <= 0x14)
  27       return 1; /* This is definitely not a v1 control command. */
  28   }
  29   return 0;
  30 }