github.com/psiphon-labs/psiphon-tunnel-core@v2.0.28+incompatible/psiphon/upstreamproxy/go-ntlm/ntlm/helpers.go (about)

     1  //Copyright 2013 Thomson Reuters Global Resources. BSD License please see License file for more information
     2  
     3  package ntlm
     4  
     5  import (
     6  	"bytes"
     7  	"crypto/rand"
     8  	"unicode/utf16"
     9  	"encoding/binary"
    10  )
    11  
    12  // Concatenate two byte slices into a new slice
    13  func concat(ar ...[]byte) []byte {
    14  	return bytes.Join(ar, nil)
    15  }
    16  
    17  // Create a 0 initialized slice of bytes
    18  func zeroBytes(length int) []byte {
    19  	return make([]byte, length, length)
    20  }
    21  
    22  func randomBytes(length int) []byte {
    23  	randombytes := make([]byte, length)
    24  	_, err := rand.Read(randombytes)
    25  	if err != nil {
    26  	} // TODO: What to do with err here
    27  	return randombytes
    28  }
    29  
    30  // Zero pad the input byte slice to the given size
    31  // bytes - input byte slice
    32  // offset - where to start taking the bytes from the input slice
    33  // size - size of the output byte slize
    34  func zeroPaddedBytes(bytes []byte, offset int, size int) []byte {
    35  	newSlice := zeroBytes(size)
    36  	for i := 0; i < size && i+offset < len(bytes); i++ {
    37  		newSlice[i] = bytes[i+offset]
    38  	}
    39  	return newSlice
    40  }
    41  
    42  func MacsEqual(slice1, slice2 []byte) bool {
    43  	if len(slice1) != len(slice2) {
    44  		return false
    45  	}
    46  	for i := 0; i < len(slice1); i++ {
    47  		// bytes between 4 and 7 (inclusive) contains random
    48  		// data that should be ignored while comparing the
    49  		// macs
    50  		if (i < 4 || i > 7) && slice1[i] != slice2[i] {
    51  			return false
    52  		}
    53  	}
    54  	return true
    55  }
    56  
    57  func utf16FromString(s string) []byte {
    58  	encoded := utf16.Encode([]rune(s))
    59  	// TODO: I'm sure there is an easier way to do the conversion from utf16 to bytes
    60  	result := zeroBytes(len(encoded) * 2)
    61  	for i := 0; i < len(encoded); i++ {
    62  		result[i*2] = byte(encoded[i])
    63  		result[i*2+1] = byte(encoded[i] << 8)
    64  	}
    65  	return result
    66  }
    67  
    68  // Convert a UTF16 string to UTF8 string for Go usage
    69  func utf16ToString(bytes []byte) string {
    70         var data []uint16
    71  
    72         // NOTE: This is definitely not the best way to do this, but when I tried using a buffer.Read I could not get it to work
    73         for offset := 0; offset < len(bytes); offset = offset + 2 {
    74                 i := binary.LittleEndian.Uint16(bytes[offset : offset+2])
    75                 data = append(data, i)
    76         }
    77  
    78         return string(utf16.Decode(data))
    79  }
    80  
    81  func uint32ToBytes(v uint32) []byte {
    82         bytes := make([]byte, 4)
    83         bytes[0] = byte(v & 0xff)
    84         bytes[1] = byte((v >> 8) & 0xff)
    85         bytes[2] = byte((v >> 16) & 0xff)
    86         bytes[3] = byte((v >> 24) & 0xff)
    87         return bytes
    88  }
    89