Initial commit

subcalc.py

@@ -0,0 +1,57 @@
+#!/usr/bin/env python
+# -*- coding:utf-8 -*-
+import sys
+
+def subcalc(slash):
+    """    Subcalc is a simple function to convert a slash-notation netmask 
+        into a dotted decimal notation netmask.
+
+        Usage: subcalc(netmask)
+        Example: subcalc (24)
+                 will return 255.255.255.0
+
+        Note: As input to subcalc, enter only the number, not the leading slash.
+              If an invalid slash-notation netmask is sent to subcalc.
+              it will return -1
+    """
+    # Check if the value is an int, if it's not then quit and return -1
+    if isinstance(slash, int) == False:
+        return -1
+        sys.exit()
+    # Check the size of the netmask, if bogus, then quit end return -1
+    if slash < 0 or slash > 32:
+        return -1
+        sys.exit()
+
+    zeroes = "0" * (32-slash) # Fill up "the rest" with zeroes
+    binNum = "1" * slash # Fill up the binary string with ones
+    binNum = binNum + zeroes # Put together the ones and the zeroes (tot = 32)
+    sub = "" # Initalize sub-variable
+
+    # Divide the binary string into four groups
+    group = []
+    group.append(binNum[0:8])
+    group.append(binNum[8:16])
+    group.append(binNum[16:24])
+    group.append(binNum[24:])
+
+    # For each group, convert to decimal type and end with a dot and append
+    # the result to the sub-variable
+    for i in group:
+        sub += (str(int(i, 2))+".")
+    return sub.rstrip(".") # Strip of the last dot
+
+def main():
+    # A simple implementation of the subcalc-function above
+    # Takes one command-line argument (the netmask)
+    if len(sys.argv) < 2: 
+        print "Usage: subcalc.py <netmask in slash-notation>"
+        print "Example: subcalc.py 24"
+        sys.exit()
+    arg = int(sys.argv[1]) # Have to typecast here since arguments are strings
+    print subcalc(arg)
+    
+    #help(subcalc)
+
+if __name__=='__main__':
+    main()