src/or/proto_ext_or.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) 2007-2017, The Tor Project, Inc. */
   5 /* See LICENSE for licensing information */
   6
   7 #include "or.h"
   8 #include "buffers.h"
   9 #include "ext_orport.h"
  10 #include "proto_ext_or.h"
  11
  12 /** The size of the header of an Extended ORPort message: 2 bytes for
  13  *  COMMAND, 2 bytes for BODYLEN */
  14 #define EXT_OR_CMD_HEADER_SIZE 4
  15
  16 /** Read <b>buf</b>, which should contain an Extended ORPort message
  17  *  from a transport proxy. If well-formed, create and populate
  18  *  <b>out</b> with the Extended ORport message. Return 0 if the
  19  *  buffer was incomplete, 1 if it was well-formed and -1 if we
  20  *  encountered an error while parsing it.  */
  21 int
  22 fetch_ext_or_command_from_buf(buf_t *buf, ext_or_cmd_t **out)
  23 {
  24   char hdr[EXT_OR_CMD_HEADER_SIZE];
  25   uint16_t len;
  26
  27   if (buf_datalen(buf) < EXT_OR_CMD_HEADER_SIZE)
  28     return 0;
  29   buf_peek(buf, hdr, sizeof(hdr));
  30   len = ntohs(get_uint16(hdr+2));
  31   if (buf_datalen(buf) < (unsigned)len + EXT_OR_CMD_HEADER_SIZE)
  32     return 0;
  33   *out = ext_or_cmd_new(len);
  34   (*out)->cmd = ntohs(get_uint16(hdr));
  35   (*out)->len = len;
  36   buf_drain(buf, EXT_OR_CMD_HEADER_SIZE);
  37   buf_get_bytes(buf, (*out)->body, len);
  38   return 1;
  39 }
  40