I keep getting an Overflow on the bitwise and in this first function. I fixed the other overflows by converting from Long to Currency (still seems weird), but I can't get this And to work.
Any ideas? I'm just trying to convert some IP addresses to CIDRs and calculate some host numbers.
Option Explicit
Public Function ConvertMaskToCIDR(someIP As String, someMask As String)
Dim ipL As Variant
ipL = iPToNum(someIP)
Dim maskL As Variant
maskL = iPToNum(someMask)
maskL = CDec(maskL)
'Convert Mask to CIDR(1-30)
Dim oneBit As Variant
oneBit = 2147483648#
oneBit = CDec(oneBit)
Dim CIDR As Integer
CIDR = 0
Dim x As Integer
For x = 31 To 0 Step -1
If (maskL And oneBit) = oneBit Then
CIDR = CIDR + 1
Else
Exit For
End If
oneBit = oneBit / 2# 'Shift one bit to the right (>> 1)
Next
Dim answer As String
answer = numToIp(ipL And maskL) & " /" & CStr(CIDR)
End Function
Public Function NumHostsInCidr(CIDR As Integer) As Currency
Dim mask As Currency
mask = maskFromCidr(CIDR)
NumHostsInCidr = iPnumOfHosts(mask)
End Function
Private Function maskFromCidr(ByVal CIDR As Integer) As Currency
'x = 32 - CIDR
'z = (2^x)-1
'return z xor 255.255.255.255
maskFromCidr = CLng(2 ^ ((32 - CIDR)) - 1) Xor 4294967295# '255.255.255.255
End Function
Private Function iPnumOfHosts(ByVal IPmsk As Currency) As Currency 'a mask for the host portion
'255.255.255.0 XOR 255.255.255.255 = 255 so 0 to 255 is 256 hosts
iPnumOfHosts = IPmsk Xor 4294967295# '255.255.255.255 , calculate the number of hosts
End Function
Private Function numToIp(ByVal theIP As Currency) As String 'convert number back to IP
Dim IPb(3) As Byte '4 octets
Dim theBit As Integer
theBit = 31 'work MSb to LSb
Dim addr As String 'accumulator for address
Dim x As Integer
For x = 0 To 3 'four octets
Dim y As Integer
For y = 7 To 0 Step -1 '8 bits
If (theIP And CLng(2 ^ theBit)) = CLng(2 ^ theBit) Then 'if the bit is on
IPb(x) = IPb(x) + CByte(2 ^ y) 'accumulate
End If
theBit = theBit - 1
Next
addr = addr & CStr(IPb(x)) & "." 'add current octet to string
Next
numToIp = trimLast(addr, ".")
End Function
Private Function iPToNum(ByVal ip As String) As Currency
Dim IPpart As Variant
Dim IPbyte(3) As Byte
IPpart = Split(ip, ".")
Dim x As Integer
For x = 0 To 3
IPbyte(x) = CByte(IPpart(x))
Next x
iPToNum = (IPbyte(0) * (256 ^ 3)) + (IPbyte(1) * (256 ^ 2)) + (IPbyte(2) * 256#) + IPbyte(3)
End Function
Private Function trimLast(str As String, chr As String)
'****
'* Remove "chr" (if it exists) from end of "str".
'****
trimLast = str
If Right(str, 1) = chr Then trimLast = Left(str, Len(str) - 1)
End Function