Add a plguin for public ip passing the tests

Author: perryzjc

Diff for: detect_secrets/plugins/ip_public.py

@@ -0,0 +1,39 @@
+import re
+from .base import RegexBasedDetector
+
+class IPPublicDetector(RegexBasedDetector):
+    """Scans for public ip address (ipv4)
+
+    Some non-public ipv4 addresses are ignored, such as:
+        - 127.
+        - 10.
+        - 172.(16-31)
+        - 192.168.
+
+    Reference: 
+    https://www.iana.org/assignments/ipv4-address-space/ipv4-address-space.xhtml
+    https://en.wikipedia.org/wiki/Private_network
+    """
+    secret_type = 'Public IP (ipv4)'
+
+    denylist_ipv4_address = r"""
+        (?<![0-9])                    # Negative lookbehind: Asserts that what immediately precedes the current position in the string is not a digit
+        (?!                            # Negative lookahead: Asserts that what immediately follows the current position in the string does not match the enclosed pattern
+            192\.168\.|                # Match "192.168."
+            127\.|                     # Match "127."
+            10\.|                      # Match "10."
+            172\.(?:1[6-9]|2[0-9]|3[01])  # Match "172." followed by a number between 16 and 31
+        )
+        (?:                            # Non-capturing group: Groups the enclosed pattern but does not create a backreference
+            (?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.   # Match a number between 0 and 255 followed by a dot
+        ){3}                           # Repeat the preceding non-capturing group three times
+        (?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)         # Match a number between 0 and 255
+        (?::\d{1,5})?                   # Optional non-capturing group: Match a colon followed by a number between 0 and 99999 (a port number)
+        (?!                            # Negative lookahead: Asserts that what immediately follows the current position in the string does not match the enclosed pattern
+            [0-9]                       # Match a digit
+        )
+    """
+
+    denylist = [
+        re.compile(denylist_ipv4_address, flags=re.IGNORECASE | re.VERBOSE)
+    ]