IPField: Add concat method for IP handling.

Author: mzen17

scapy/fields.py

@@ -848,8 +848,25 @@ class IPField(Field[Union[str, Net], bytes]):
     def __init__(self, name, default):
         # type: (str, Optional[str]) -> None
         Field.__init__(self, name, default, "4s")
-
-    def h2i(self, pkt, x):
+    
+    def _concat_ip(self, ip_string):
+        """Concat a IP str of form IP,IP,IP and returns it as bytes
+        Backcompatible if IP is a single IP.
+        :param ip_string: String of the IP to be packed"""
+        ip_string = ip_string.replace(" ", "")
+        
+        # Split IPs by commas and filter out empty strings
+        ip_list = [ip.strip() for ip in ip_string.split(',') if ip.strip()]
+        
+        # Convert each IP to packed format
+        packed_ips = []
+        for ip in ip_list:
+            packed_ips.append(socket.inet_aton(ip))
+        
+        # Concatenate packed IPs into a single byte string
+        return b''.join(packed_ips)
+        
+    def h2i(self, pkt, x, multiple=False):
         # type: (Optional[Packet], Union[AnyStr, List[AnyStr]]) -> Any
         if isinstance(x, bytes):
             x = plain_str(x)  # type: ignore
@@ -858,7 +875,7 @@ def h2i(self, pkt, x):
         elif isinstance(x, str):
             x = ScopedIP(x)
             try:
-                inet_aton(x)
+                self._concat_ip(x)
             except socket.error:
                 return Net(x)
         elif isinstance(x, tuple):
@@ -889,7 +906,7 @@ def i2m(self, pkt, x):
         # type: (Optional[Packet], Optional[Union[str, Net]]) -> bytes
         if x is None:
             return b'\x00\x00\x00\x00'
-        return inet_aton(plain_str(x))
+        return self._concat_ip(plain_str(x))
 
     def m2i(self, pkt, x):
         # type: (Optional[Packet], bytes) -> str