6.3.7 Name Compression and Decompression

msdn link

The server can choose any compression algorithm, as long as the compressed stream can be decompressed using the following name decompression algorithm. When the server compresses the names for the LDAP ping response, if compression fails, the response of the server is documented in "Response to Invalid filter" (section 6.3.3.3). When the server compresses the names for the mailslot ping response, if compression fails, the server does not send any response back to the client.

Name Decompression Algorithm

 --
 --  On Entry: InputBuffer - a buffer of compressed data, treated as 
 --                bytes
 --            InputBufferSize - The number of bytes in the InputBuffer
 --            StringCount - number of strings needed to be 
 --                decompressed from InputBuffer
 --            Current – Index into the buffer that contains the first 
 --                byte of the compressed strings
 --
 --  On Exit:  OutputBuffers - an array of decompressed strings
 --            Success -  Set to TRUE if decompression succeeds, set to
 --                FALSE if decompression fails.
 --            Current – Index of the byte in the message succeeding the last
 --                byte of the compressed string block
  
  
  
  
  
 SET deCompressedCount = 0
 SET localCurrent = 0
 FOR i = 1 to StringCount
     SET dnsNameLen = 0
     SET firstLabel = 0
     allocate a buffer s[InputBufferSize]
     WHILE Current < InputBufferSize
         SET labelSize = InputBuffer[Current]
         IF labelSize == '\0' THEN                           
             s[dnsNameLen] = '\0'
             OutputBuffers[deCompressedCount] = s
             deCompressedCount++
             Current++
             BREAK
         ELSE IF (labelSize & 0xC0) != 0 THEN
             Current++
             localCurrent = Current + 1
             labelSize = InputBuffer[Current]
             IF labelSize > InputBufferSize THEN
                 Success = FALSE  
                 RETURN        
             END IF
             Current = labelSize
             CONTINUE
         ELSE
             IF (labelSize + Current) >= InputBufferSize THEN
                 Success = FALSE  
                 RETURN
             END IF
             IF firstLabel == 0 THEN
                 firstLabel = 1
             ELSE
                 s[dnsNameLen] = '.'
                 dnsNameLen++
             ENDIF
  
  
             Append
               substring InputBuffer[Current + 1, Current + labelSize]
                 to s
             dnsNameLen += labelSize       
             IF localCurrent != 0 THEN
                 Current = localCurrent
                 localCurrent = 0       
             ELSE
                 Current = Current + 1 + labelSize     
             END IF
         END IF                                    
     END WHILE
     If i <> deCompressedCount THEN
         Success = FALSE
         RETURN
     ENDIF
 END FOR
 Success = TRUE
 RETURN