added is_mac_adddress() function to check if a string is a valid ethernet

mac address

Author: NetworkJack2

README.md

@@ -19,6 +19,9 @@ Random device bytes will be generated.
 
 **list_vendors(_file_)** - return a python list [] with valid vendors
 
+**is_mac_address(_mac_)** - Takes a string, and checks if it is a valid Ethernet
+MAC address. returns True or False(bool type)
+
 Usage
 -----
 
@@ -61,3 +64,9 @@ List valid vendor options as a list.
 g.list_vendors('/usr/share/wireshark/manuf')
 ['Vendor1','Vendor2','etc']
 ```
+
+Check if a MAC address is valid
+```
+if g.is_mac_address('94:0C:98:BC:74:1C') == True:
+    print('Valid Ethernet AAddress')
+```

generate_mac/__init__.py

@@ -190,3 +190,20 @@ def list_vendors(vid_file):
         '''Returns a list[] of valid ETH Vendors that can be used with vid_file_vendor()'''
         file_lines = generate_mac._read_vid_file(vid_file)
         return list(generate_mac._valid_vendors)
+
+    def is_mac_address(mac_address):
+        '''Test if a given string is a valid Ethernet MAC address. return True or False'''
+        try:
+            mac_bytes=mac_address.split(":")
+        except:
+            return False
+        if len(mac_bytes) != 6:
+            return False
+
+        # First Octet needs to be odd.       
+        mac_byte_bcast = mac_bytes[0][1]
+        mac_byte_bcast = mac_byte_bcast.upper()
+        if mac_byte_bcast in generate_mac._valid_bcast_char:
+            return True
+        else:
+            return False