Source Code for Module backend.common.byterange

  1  # 
  2  # Copyright (c) 2008--2017 Red Hat, Inc. 
  3  # 
  4  # This software is licensed to you under the GNU General Public License, 
  5  # version 2 (GPLv2). There is NO WARRANTY for this software, express or 
  6  # implied, including the implied warranties of MERCHANTABILITY or FITNESS 
  7  # FOR A PARTICULAR PURPOSE. You should have received a copy of GPLv2 
  8  # along with this software; if not, see 
  9  # http://www.gnu.org/licenses/old-licenses/gpl-2.0.txt. 
 10  # 
 11  # Red Hat trademarks are not licensed under GPLv2. No permission is 
 12  # granted to use or replicate Red Hat trademarks that are incorporated 
 13  # in this software or its documentation. 
 14  # 
 15  # 
 16   
 17  import re 
 18  import sys 
 19   
 20  # common module 
 21  from spacewalk.common.usix import raise_with_tb 
 22  from spacewalk.common.rhnLog import log_debug 
 23  from spacewalk.common.rhnException import rhnException 
 24   
 25  # pylint: disable=W0710 
 26   
 27  # Parses the HTTP header value and stores in the flags  a list of (start, end) 
 28  # tuples that are more pythonic than the RFC semantics 
 29   
 30   
 31 -def parse_byteranges(byterange_header, file_size=None): 
 32      log_debug(4, "Parsing byte range", byterange_header) 
 33      regexp = re.compile(r"^bytes\s*=\s*(.*)$") 
 34      mo = regexp.match(byterange_header) 
 35      if not mo: 
 36          raise InvalidByteRangeException 
 37   
 38      arr = mo.groups()[0].split(",") 
 39      regexp = re.compile(r"^([^-]*)-([^-]*)$") 
 40   
 41      if len(arr) > 1: 
 42          # We don't support very fancy byte ranges yet 
 43          raise UnsatisfyableByteRangeException 
 44   
 45      mo = regexp.match(arr[0]) 
 46      if not mo: 
 47          # Invalid byterange 
 48          raise InvalidByteRangeException 
 49      try: 
 50          start, end = list(map(_str2int, mo.groups())) 
 51      except ValueError: 
 52          # Invalid 
 53          raise_with_tb(InvalidByteRangeException, sys.exc_info()[2]) 
 54      if start is not None: 
 55          if start < 0: 
 56              # Invalid 
 57              raise InvalidByteRangeException 
 58          if file_size is not None: 
 59              if start >= file_size: 
 60                  raise UnsatisfyableByteRangeException 
 61          if end is not None: 
 62              if start > end: 
 63                  # Invalid 
 64                  raise InvalidByteRangeException 
 65              end = end + 1 
 66          else: 
 67              if file_size: 
 68                  end = file_size 
 69      else: 
 70          # No start specified 
 71          if end is None: 
 72              # Invalid 
 73              raise InvalidByteRangeException 
 74          if end <= 0: 
 75              # Invalid 
 76              raise InvalidByteRangeException 
 77          if file_size: 
 78              if end > file_size: 
 79                  raise UnsatisfyableByteRangeException 
 80              start = file_size - end 
 81              end = file_size 
 82          else: 
 83              start = -end 
 84              end = None 
 85   
 86      byteranges = (start, end) 
 87   
 88      log_debug(4, "Request byterange", byteranges) 
 89      return byteranges 
 90   
 91   
 92 -def _str2int(val): 
 93      val = val.strip() 
 94      if val == "": 
 95          return None 
 96   
 97      return int(val) 
 98   
 99   
100 -def get_content_range(start, end, total_length=None): 
101      if total_length is None: 
102          total_length = "*" 
103      end = end - 1 
104      content_range = "bytes %d-%d/%s" % (start, end, total_length) 
105      return content_range 
106   
107   
108 -class InvalidByteRangeException(rhnException): 
109      pass 
110   
111   
112 -class UnsatisfyableByteRangeException(rhnException): 
113      pass 
114