We Keep Coding

C# How do I set specific binary bit to 0 or 1?

I've got four checkboxes linked to a hex value between 0x00 and 0x0F, so if you type in 0x0B which would be 1011 the check boxes would be checked, not checked, checked, checked. For this I used:
if ((controlByte.Item2 & 0x01) == 0x01)
{
control1 = true;
}
if ((controlByte.Item2 & 0x02) == 0x02)
{
control2 = true;
}
if ((controlByte.Item2 & 0x04) == 0x04)
{
control3 = true;
}
if ((controlByte.Item2 & 0x08) == 0x08)
{
control4 = true;
}
Next I want it to go the other direction, so as you click checkboxes the hex value will change.
If I have the current value 0x0B (1011) And click the first box I want it to return 0x0A (1010). My function will go over each checkbox and update the hex value as it goes. My current attempt looks like this:
if (checkbox1)
{
controlbyte = (byte)(controlbyte | 0x01);
}
else
{
controlbyte = (byte)(controlbyte ^ 0x01);
}
It looks like this toggles it, but when I run through all checkboxes it toggles ones I didn't click. Is there a better way to take 0x0B (1011) and just set one of the bits to 0 or 1?

( 1 << flag ) <--- change like this;
if ((controlByte.Item2 & (1 << flag)) == (1 << flag))
{
control[flag] = true;
}
//0x01 == 1 << 1;
//0x02 == 1 << 2;
//0x04 == 1 << 3;
//0x08 == 1 << 4;
//because it same like this:
if ((controlByte.Item2 & (1 << 1)) == (1 << 1))
{
control1 = true;
}
if ((controlByte.Item2 & (1 << 2)) == (1 << 2))
{
control2 = true;
}
if ((controlByte.Item2 & (1 << 3)) == (1 << 3))
{
control3 = true;
}
...
controlbyte = (byte)(controlbyte | (1 << 1));
controlbyte = (byte)(controlbyte ^ (1 << 1));

Decode cyrillic quoted-printable content

I'm using this sample for getting mail from server. Problem is that response contains cyrillic symbols I cannot decode.
Here is a header:
Content-type: text/html; charset="koi8-r"
Content-Transfer-Encoding: quoted-printable
And receive response function:
static void receiveResponse(string command)
{
try
{
if (command != "")
{
if (tcpc.Connected)
{
dummy = Encoding.ASCII.GetBytes(command);
ssl.Write(dummy, 0, dummy.Length);
}
else
{
throw new ApplicationException("TCP CONNECTION DISCONNECTED");
}
}
ssl.Flush();
byte[] bigBuffer = new byte[1024*16];
int bites = ssl.Read(bigBuffer, 0, bigBuffer.Length);
byte[] buffer = new byte[bites];
Array.Copy(bigBuffer, 0, buffer, 0, bites);
sb.Append(Encoding.ASCII.GetString(buffer));
string result = sb.ToString();
// here is an unsuccessful attempt at decoding
result = Regex.Replace(result, #"=([0-9a-fA-F]{2})",
m => m.Groups[1].Success
? Convert.ToChar(Convert.ToInt32(m.Groups[1].Value, 16)).ToString()
: "");
byte[] bytes = Encoding.Default.GetBytes(result);
result = Encoding.GetEncoding("koi8r").GetString(bytes);
}
catch (Exception ex)
{
throw new ApplicationException(ex.ToString());
}
}
How to decode stream correctly? In result string I got <p>=F0=D2=C9=D7=C5=D4 =D1 =F7=C1=CE=D1</p> instead of <p>Привет я Ваня</p>.

As #Max pointed out, you will need to decode the content using the encoding algorithm declared in the Content-Transfer-Encoding header.
In your case, it is the quoted-printable encoding.
You will need to decode the text of the message into an array of bytes and then you’ll need to convert that array of bytes into a string using the appropriate System.Text.Encoding. The name of the encoding to use will typically be specified in the Content-Type header as the charset parameter (in your case, koi8-r).
Since you already have the text as bytes in the buffer variable, simply perform the deciding on that:
byte[] buffer = new byte[bites];
int decodedLength = 0;
for (int i = 0; i < bites; i++) {
if (bigBuffer[i] == (byte) '=') {
if (bites > i + 1) {
// possible hex sequence
byte b1 = bigBuffer[i + 1];
byte b2 = bigBuffer[i + 2];
if (IsXDigit (b1) && IsXDigit (b2)) {
// decode
buffer[decodedLength++] = (ToXDigit (b1) << 4) | ToXDigit (b2);
i += 2;
} else if (b1 == (byte) '\r' && b2 == (byte) '\n') {
// folded line, drop the '=\r\n' sequence
i += 2;
} else {
// error condition, just pass it through
buffer[decodedLength++] = bigBuffer[i];
}
} else {
// truncated? just pass it through
buffer[decodedLength++] = bigBuffer[i];
}
} else {
buffer[decodedLength++] = bigBuffer[i];
}
}
string result = Encoding.GetEncoding ("koi8-r").GetString (buffer, 0, decodedLength);
Custom functions:
static byte ToXDigit (byte c)
{
if (c >= 0x41) {
if (c >= 0x61)
return (byte) (c - (0x61 - 0x0a));
return (byte) (c - (0x41 - 0x0A));
}
return (byte) (c - 0x30);
}
static bool IsXDigit (byte c)
{
return (c >= (byte) 'A' && c <= (byte) 'F') || (c >= (byte) 'a' && c <= (byte) 'f') || (c >= (byte) '0' && c <= (byte) '9');
}
Of course, instead of writing your own hodge podge IMAP library, you could just use MimeKit and MailKit ;-)

Encoding errors in embedded Json file

I have run into an issue and can't quite get my head around it.
I have this code:
public List<NavigationModul> LoadNavigation()
{
byte[] navBytes = NavigationResources.Navigation;
var encoding = GetEncoding(navBytes);
string json = encoding.GetString(navBytes);
List<NavigationModul> navigation = JsonConvert.DeserializeObject<List<NavigationModul>>(json);
return navigation;
}
public static Encoding GetEncoding(byte [] textBytes)
{
if (textBytes[0] == 0x2b && textBytes[1] == 0x2f && textBytes[2] == 0x76) return Encoding.UTF7;
if (textBytes[0] == 0xef && textBytes[1] == 0xbb && textBytes[2] == 0xbf) return Encoding.UTF8;
if (textBytes[0] == 0xff && textBytes[1] == 0xfe) return Encoding.Unicode; //UTF-16LE
if (textBytes[0] == 0xfe && textBytes[1] == 0xff) return Encoding.BigEndianUnicode; //UTF-16BE
if (textBytes[0] == 0 && textBytes[1] == 0 && textBytes[2] == 0xfe && textBytes[3] == 0xff) return Encoding.UTF32;
return Encoding.ASCII;
}
The Goal is to load an embedded Json File (NavigationResources.Navigation) from a ResourceFile. The Navigation File is an embedded file. We are just jusing the ResourceManager to avoid Magic strings.
After loading the bytes of the embedded file and checking for its encoding, I now read the String from the file and pass it to the JsonConverter.DeserializeObject function.
But unfortunaly this fails due to invalid Json. Long story short: The loaded json string still contains encoding identification bytes. And I can't figure out how to get rid of it.
I also tryed to convert the utf8 bytearray to default encoding before loading the string but this only makes the encoding bytes become a visible charecter.
I talked to my peers and they told me that they have run into the same problem reading embedded batchfiles, leading to broken batchfiles. They didn't know how to fix the problem either, but came up with a workaround for the batchfiles itself (add a blank line into the batchfile to make it work)
Any suggestions on how to fix this?

Thanks to Alex K. I have a solution:
Cuting of the Identification Bytes before calling Encoding.GetString did the trick.
Here is my function I now use to do the Task:
public static string GetStringFromEncodedBytes(byte[] bytes) {
Encoding encoding = Encoding.Default;
int skipBytes = 0;
if (bytes[0] == 0x2b && bytes[1] == 0x2f && bytes[2] == 0x76) {
encoding = Encoding.UTF7;
skipBytes = 3;
}
if (bytes[0] == 0xef && bytes[1] == 0xbb && bytes[2] == 0xbf)
{
encoding = Encoding.UTF8;
skipBytes = 3;
}
if (bytes[0] == 0xff && bytes[1] == 0xfe)
{
encoding = Encoding.Unicode;
skipBytes = 2;
}
if (bytes[0] == 0xfe && bytes[1] == 0xff)
{
encoding = Encoding.BigEndianUnicode;
skipBytes = 2;
}
if (bytes[0] == 0 && bytes[1] == 0 && bytes[2] == 0xfe && bytes[3] == 0xff)
{
encoding = Encoding.UTF32;
skipBytes = 4;
}
return encoding.GetString(bytes.Skip(skipBytes).ToArray());
}

Here's a simpler approach, removing the BOM after decoding:
// Your data is always in UTF-8 apparently, so just rely on that.
string text = Encoding.UTF8.GetString(data);
if (text.StartsWith("\ufeff"))
{
text = text.Substring(1);
}
This has the downside of copying the string, of course.
Or if you do want to skip the bytes:
// Again, we're assuming UTF-8
int start = data.Length >= 3 && data[0] == 0xef &&
data[1] == 0xbb && data[2] == 0xbf)
? 3 : 0;
string text = Encoding.UTF8.GetString(data, start, data.Length - start);
That way you don't need to use Skip and ToArray, and it avoids doing any extraneous copying.

Checking if Bytes are 0x00

What is the most readable (and idiomatic) to write this method?
private bool BytesAreValid(byte[] bytes) {
var t = (bytes[0] | bytes[1] | bytes[2]);
return t != 0;
}
I need a function which tests the first three bytes of a file that it's not begin with 00 00 00.
Haven't done much byte manipulation. The code above doesn't seem correct to me, since t is inferred of type Int32.

t is type-inferred to be an Int32
Yup, because the | operator (like most operators) isn't defined for byte - the bytes are promoted to int values. (See section 7.11.1 of the C# 4 spec for details.)
But given that you only want to compare it with 0, that's fine anyway.
Personally I'd just write it as:
return bytes[0] != 0 && bytes[1] != 0 && bytes[2] != 0;
Or even:
return (bytes[0] != 0) && (bytes[1] != 0) && (bytes[2] != 0);
Both of these seem clearer to me.

private bool BytesAreValid(byte[] bytes) {
return !bytes.Take(3).SequenceEqual(new byte[] { 0, 0, 0 });
}

To anticipate variable array lengths and avoid null reference exceptions:
private bool BytesAreValid(byte[] bytes)
{
if (bytes == null) return false;
return !Array.Exists(bytes, x => x == 0);
}
Non-Linq version:
private bool BytesAreValid(byte[] bytes)
{
if (bytes == null) return false;
for (int i = 0; i < bytes.Length; i++)
{
if (bytes[i] == 0) return false;
}
return true;
}

Given an IP address and subnetmask, how do I calculate the CIDR?

Ok I can't seem to figure this out: given the following:
IP address = 192.168.1.0
Subnetmask = 255.255.255.240
Using c#, how do I calculate the CIDR notation 192.168.1.0/28 ? Is there an easy way to achieve this? Am I missing something?
Thanks!

256 - 240 = 16 = 2**4, 32 - 4 = 28
It is not really a C# question.
To get a net address from an IP and mask you can apply bytewise and to the IP and mask. You can get bytes from a string using IPAddress.Parse() and IPAddress.GetAddressBytes().

I had to do the same thing, no new info but this snippet may come in handy for the next person looking for a way to do this in C#.
note that this method only counts the number of consecutive 1s, and leaves you the work of appending it to the IP.
public class IPAddressHelper
{
public static UInt32 SubnetToCIDR(string subnetStr)
{
IPAddress subnetAddress = IPAddress.Parse(subnetStr);
byte[] ipParts = subnetAddress.GetAddressBytes();
UInt32 subnet = 16777216 * Convert.ToUInt32(ipParts[0]) + 65536 * Convert.ToUInt32(ipParts[1]) + 256 * Convert.ToUInt32(ipParts[2]) + Convert.ToUInt32(ipParts[3]);
UInt32 mask = 0x80000000;
UInt32 subnetConsecutiveOnes = 0;
for (int i = 0; i < 32; i++)
{
if (!(mask & subnet).Equals(mask)) break;
subnetConsecutiveOnes++;
mask = mask >> 1;
}
return subnetConsecutiveOnes;
}
}

Keep it simple!
This works for IPv4 only, but since IPv6 does only support CIDR like /64 in fe80::1ff:fe23:4567:890a/64 calculations like that are unnecessary there.
All you need for an IPv4 network mask:
int cidr = Convert.ToString(mask.Address, 2).Count( o => o == '1');
Explanation based on the given example:
IPAddress mask = new IPAddress(new byte[] { 255, 255, 255, 240 });
// maskBinAsString = 11110000111101001111111111111111
string maskBinAsString = Convert.ToString(mask.Address, 2);
// cidr = 28
int cidr = Convert.ToString(mask.Address, 2).Count( o=> o == '1');

I don't have it as C# code but here is the answer in VB. Should not be to hard to convert.
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim someIP As Net.IPAddress = Net.IPAddress.Parse("192.168.1.10")
Dim someMASK As Net.IPAddress = Net.IPAddress.Parse("255.255.255.240")
Dim ipL As Long = IPtoLong(someIP)
Dim maskL As Long = IPtoLong(someMASK)
'Convert Mask to CIDR(1-30)
Dim oneBit As Long = &H80000000L
Dim CIDR As Integer = 0
For x As Integer = 31 To 0 Step -1
If (maskL And oneBit) = oneBit Then CIDR += 1 Else Exit For
oneBit = oneBit >> 1
Next
Dim answer As String = LongToIp(ipL And maskL) & " /" & CIDR.ToString
End Sub
Public Function IPtoLong(ByVal theIP As Net.IPAddress) As Long 'convert IP to number
Dim IPb() As Byte = theIP.GetAddressBytes 'get the octets
Dim addr As Long 'accumulator for address
For x As Integer = 0 To 3
addr = addr Or (CLng(IPb(x)) << (3 - x) * 8)
Next
Return addr
End Function
Public Function LongToIp(ByVal theIP As Long) As String 'convert number back to IP
Dim IPb(3) As Byte '4 octets
Dim addr As String = "" 'accumulator for address
Dim mask8 As Long = MaskFromCidr(8) 'create eight bit mask
For x = 0 To 3 'get the octets
IPb(x) = CByte((theIP And mask8) >> ((3 - x) * 8))
mask8 = mask8 >> 8
addr &= IPb(x).ToString & "." 'add current octet to string
Next
Return addr.TrimEnd("."c)
End Function
Private Function MaskFromCidr(ByVal CIDR As Integer) As Long
MaskFromCidr = CLng(2 ^ ((32 - CIDR)) - 1) Xor 4294967295L
End Function

my solution, first parse to IPAddress:
var Subnetmask = "255.255.255.240";
IPAddress ip = IPAddress.Parse(Subnetmask);
then, check count of set bits in the mask ip:
var intAddress = (int)IPAddress.Address;
Console.WriteLine(NumberOfSetBits(intAddress)); //28
the function (from https://stackoverflow.com/a/12175897/1271037):
int NumberOfSetBits(int i)
{
i = i - ((i >> 1) & 0x55555555);
i = (i & 0x33333333) + ((i >> 2) & 0x33333333);
return (((i + (i >> 4)) & 0x0F0F0F0F) * 0x01010101) >> 24;
}

I know it's a little late, but I took a swing converting dbasnett's answer VB.NET code above to C# (thanks to Telerik Code Converter) and put it up in a .NET Fiddle here and included my conversion below:
public static void Main()
{
System.Net.IPAddress someIP = System.Net.IPAddress.Parse("192.168.1.23");
System.Net.IPAddress someMASK = System.Net.IPAddress.Parse("255.255.255.128");
long ipL = IPtoLong(someIP);
long maskL = IPtoLong(someMASK);
// Convert Mask to CIDR(1-30)
long oneBit = 0x80000000L;
int CIDR = 0;
for (int x = 31; x >= 0; x += -1)
{
if ((maskL & oneBit) == oneBit)
CIDR += 1;
else
break;
oneBit = oneBit >> 1;
}
string answer = LongToIp(ipL & maskL) + "/" + CIDR.ToString();
Console.Out.WriteLine("woah woah we woah " + answer);
}
public static long IPtoLong(System.Net.IPAddress theIP) // convert IP to number
{
byte[] IPb = theIP.GetAddressBytes(); // get the octets
long addr = 0; // accumulator for address
for (int x = 0; x <= 3; x++) {
addr |= (System.Convert.ToInt64(IPb[x]) << (3 - x) * 8);
}
return addr;
}
public static string LongToIp(long theIP) // convert number back to IP
{
byte[] IPb = new byte[4]; // 4 octets
string addr = ""; // accumulator for address
long mask8 = MaskFromCidr(8); // create eight bit mask
for (var x = 0; x <= 3; x++) // get the octets
{
IPb[x] = System.Convert.ToByte((theIP & mask8) >> ((3 - x) * 8));
mask8 = mask8 >> 8;
addr += IPb[x].ToString() + "."; // add current octet to string
}
return addr.TrimEnd('.');
}
private static long MaskFromCidr(int CIDR)
{
return System.Convert.ToInt64(Math.Pow(2, ((32 - CIDR))) - 1) ^ 4294967295L;
}

See Get CIDR from netmask
Usage:
var cidrnetmask = MaskToCIDR(IPAddress.Parse("255.0.0.0").GetAddressBytes());
This works for IPv4. To support IPv6, one could expand the number of bytes but hopefully nobody will try and use old-style netmasks for IPv6 :o)
Method:
static int MaskToCIDR(byte[] bytes)
{
var b0 = bytes[0];
var b1 = bytes[1];
var b2 = bytes[2];
var b3 = bytes[3];
return
b3 != 0 ? (
(b3 & 0x01) != 0 ? 32 :
(b3 & 0x02) != 0 ? 31 :
(b3 & 0x04) != 0 ? 30 :
(b3 & 0x08) != 0 ? 29 :
(b3 & 0x10) != 0 ? 28 :
(b3 & 0x20) != 0 ? 27 :
(b3 & 0x40) != 0 ? 26 :
25 ) :
b2 != 0 ? (
(b2 & 0x01) != 0 ? 24 :
(b2 & 0x02) != 0 ? 23 :
(b2 & 0x04) != 0 ? 22 :
(b2 & 0x08) != 0 ? 21 :
(b2 & 0x10) != 0 ? 20 :
(b2 & 0x20) != 0 ? 19 :
(b2 & 0x40) != 0 ? 18 :
17 ) :
b1 != 0 ? (
(b1 & 0x01) != 0 ? 16 :
(b1 & 0x02) != 0 ? 15 :
(b1 & 0x04) != 0 ? 14 :
(b1 & 0x08) != 0 ? 13 :
(b1 & 0x10) != 0 ? 12 :
(b1 & 0x20) != 0 ? 11 :
(b1 & 0x40) != 0 ? 10 :
9 ) :
b0 != 0 ? (
(b0 & 0x01) != 0 ? 8 :
(b0 & 0x02) != 0 ? 7 :
(b0 & 0x04) != 0 ? 6 :
(b0 & 0x08) != 0 ? 5 :
(b0 & 0x10) != 0 ? 4 :
(b0 & 0x20) != 0 ? 3 :
(b0 & 0x40) != 0 ? 2 :
1 ) :
0;
}