Update regex to disallow leading zeros

Also updated a comment to point to a non-experimental RFC.

Signed-off-by: jbzdarkid <jbzdarkid@gmail.com>

automated install/basic-install.sh

@@ -1018,9 +1018,11 @@ valid_ip() {
     local stat=1
 
     # Regex matching one IPv4 component, i.e. an integer from 0 to 255.
-    local ipv4elem="(25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[0-9]{1,2})";
-    # Regex matching an optional port beginning with # matching optional port number starting '#' with range of 1 to 65536
-    local portelem="(:(6553[0-5]|655[0-2][0-9]|65[0-4][0-9]{2}|6[0-4][0-9]{3}|[1-5][0-9]{4}|[0-9]{1,4}))?";
+    # See https://tools.ietf.org/html/rfc1340
+    local ipv4elem="(25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9][0-9]?|0)";
+    # Regex matching an optional port beginning with : from 0 to 65535
+    # See https://tools.ietf.org/html/rfc1340#page-33
+    local portelem="(:(6553[0-5]|655[0-2][0-9]|65[0-4][0-9]{2}|6[0-4][0-9]{3}|[1-5][0-9]{4}|[1-9][0-9]{0,3}|0))?";
     # Build a full IPv4 regex from the above subexpressions
     local regex="^${ipv4elem}\.${ipv4elem}\.${ipv4elem}\.${ipv4elem}${portelem}$"
 

test/test_automated_install.py

@@ -555,6 +555,14 @@ def test_validate_ip(Pihole):
     test_address('8.8.8.8:65535')
     test_address('8.8.8.8:65536', False)
     test_address('8.8.8.8:-1', False)
+    test_address('00.0.0.0', False)
+    test_address('010.0.0.0', False)
+    test_address('001.0.0.0', False)
+    test_address('0.0.0.0:00', False)
+    test_address('0.0.0.0:01', False)
+    test_address('0.0.0.0:001', False)
+    test_address('0.0.0.0:0001', False)
+    test_address('0.0.0.0:00001', False)
 
 
 def test_os_check_fails(Pihole):