add sn domains conversion tool

conv.py

@@ -0,0 +1,68 @@
+#!/usr/bin/env python
+
+# Read the wiki for more infomation
+# https://github.com/lennylxx/ipv6-hosts/wiki/sn-domains
+
+import sys
+table = '1023456789abcdefghijklmnopqrstuvwxyz'
+
+def iata2sn(iata):
+    global table
+    sn = ''
+    for v in iata[0:3]:
+        i = ((ord(v) - ord('a')) * 7 + 5) % 36
+        sn += table[i]
+    return sn
+
+def sn2iata(sn):
+    global table
+    iata = ''
+    for v in sn:
+        i = table.index(v)
+        i = (5 - i % 7) * 5 + i / 7 + 10
+        iata += table[i]
+    return iata
+
+def num2code(num):
+    global table
+    code = ''
+    for v in num:
+        i = ((ord(v) - ord('0') + 1) * 7) % 36
+        code += table[i]
+    return code
+    
+def code2num(code):
+    global table
+    num = ''
+    for v in code:
+        i = table.index(v)
+        i = i / 7 + i % 7 - 1
+        num += str(i)
+    return num
+
+def main():
+    if len(sys.argv) != 3:
+        print 'usage:\n\t./%s -i iata\n\t./%s -s sn'\
+            % (sys.argv[0], sys.argv[0])
+        sys.exit(1)
+
+    input = sys.argv[2]
+    ret = ''
+    if sys.argv[1] == '-i':
+        ret += iata2sn(input[0:3])
+        ret += num2code(input[3:5])
+        ret += 'n'
+        ret += num2code(input[6:8])
+        print ret
+    elif sys.argv[1] == '-s':
+        ret += sn2iata(input[0:3])
+        ret += code2num(input[3:5])
+        ret += 's'
+        ret += code2num(input[6:8])
+        print ret
+    else:
+        print 'Unknown option.'
+        sys.exit(1)
+
+if __name__ == '__main__':
+    main()