EyeFiServer TCPCheckSum speedup patch

gistfile1.diff

*** tachang-EyeFiServer-4c473e7/Release 2.0/EyeFiCrypto.py	Sun Feb 28 12:47:58 2010
--- ../EyeFiServer/Release 2.0/EyeFiCrypto.py	Mon Jan  9 18:27:25 2012
***************
*** 2,7 ****
--- 2,8 ----
  import struct
  import array
  import hashlib
+ import sys
  
  class EyeFiCrypto():
      
***************
*** 15,76 ****
      if(len(bytes) % 2 != 0 ):
        bytes = bytes + "\x00"
          
!     counter = 0
!     sumOfTwoByteWords = 0
!         
!     # Loop over all the bytes, two at a time
!     while(counter < len(bytes) ):
!     
!       # For each pair of bytes, cast them into a 2 byte integer (unsigned short)
!       # Compute using little-endian (which is what the '<' sign if for)
!       unsignedShort = struct.unpack("<H",bytes[counter:counter+2])
!       
!       # Add them all up
!       sumOfTwoByteWords = sumOfTwoByteWords + int(unsignedShort[0])
!       counter = counter + 2
  
-     
      # The sum at this point is probably a 32 bit integer. Take the left 16 bits
      # and the right 16 bites, interpret both as an integer of max value 2^16 and
      # add them together. If the resulting value is still bigger than 2^16 then do it
      # again until we get a value less than 16 bits.
!     while (sumOfTwoByteWords >> 16):
!       sumOfTwoByteWords = (sumOfTwoByteWords >> 16) + (sumOfTwoByteWords & 0xFFFF) 
      
      # Take the one's complement of the result through the use of an xor
!     checksum = sumOfTwoByteWords ^ 0xFFFFFFFF
! 
!     # Compute the final checksum by taking only the last 16 bits
!     checksum = (checksum & 0xFFFF)
!     
      return checksum
- 
    
    def calculateIntegrityDigest(self, bytes, uploadkey):
  
-     # If the number of bytes I was given is not a multiple of 512
-     # pad the input with a null characters to get the proper alignment
-     while(len(bytes) % 512 != 0 ):
-       bytes = bytes + "\x00"
-       
      counter = 0
      
      # Create an array of 2 byte integers
      concatenatedTCPChecksums = array.array('H')
      
      # Loop over all the bytes, using 512 byte blocks
!     while(counter < len(bytes) ): 
!       
        tcpChecksum = self.calculateTCPChecksum(bytes[counter:counter+512])
        concatenatedTCPChecksums.append(tcpChecksum)
        counter = counter + 512
! 
!     # Append the upload key
!     concatenatedTCPChecksums.fromstring(binascii.unhexlify(uploadkey))
  
      # Get the concatenatedTCPChecksums array as a binary string
      integrityDigest = concatenatedTCPChecksums.tostring()
!     
      # MD5 hash the binary string    
      m = hashlib.md5()
      m.update(integrityDigest)
--- 16,61 ----
      if(len(bytes) % 2 != 0 ):
        bytes = bytes + "\x00"
          
!     ushorts = array.array('H', bytes)
!     if sys.byteorder == "big":
!       ushorts.byteswap()
!     sumOfTwoByteWords = sum(ushorts)
  
      # The sum at this point is probably a 32 bit integer. Take the left 16 bits
      # and the right 16 bites, interpret both as an integer of max value 2^16 and
      # add them together. If the resulting value is still bigger than 2^16 then do it
      # again until we get a value less than 16 bits.
!     sumOfTwoByteWords = (sumOfTwoByteWords >> 16) + (sumOfTwoByteWords & 0xFFFF)
!     sumOfTwoByteWords = (sumOfTwoByteWords >> 16) + (sumOfTwoByteWords & 0xFFFF)
      
      # Take the one's complement of the result through the use of an xor
!     checksum = sumOfTwoByteWords ^ 0xFFFF
      return checksum
    
    def calculateIntegrityDigest(self, bytes, uploadkey):
  
      counter = 0
      
      # Create an array of 2 byte integers
      concatenatedTCPChecksums = array.array('H')
      
      # Loop over all the bytes, using 512 byte blocks
!     while counter <= len(bytes) - 512:
        tcpChecksum = self.calculateTCPChecksum(bytes[counter:counter+512])
        concatenatedTCPChecksums.append(tcpChecksum)
        counter = counter + 512
!     if counter < len(bytes):
!       tcpChecksum = self.calculateTCPChecksum(bytes[counter:])
!       concatenatedTCPChecksums.append(tcpChecksum)
  
      # Get the concatenatedTCPChecksums array as a binary string
+     if sys.byteorder == "big":
+       concatenatedTCPChecksums.byteswap()
      integrityDigest = concatenatedTCPChecksums.tostring()
! 
!     # Append the upload key
!     integrityDigest += binascii.unhexlify(uploadkey)
! 
      # MD5 hash the binary string    
      m = hashlib.md5()
      m.update(integrityDigest)