get-dns-namespaces.py

import ctypes  
import ctypes.wintypes  
import socket  
  
# Load necessary libraries  
iphlpapi = ctypes.WinDLL('Iphlpapi.dll')  
  
# Define necessary constants and flags  
AF_UNSPEC = 0  
GAA_FLAG_INCLUDE_PREFIX = 0x0010  
ERROR_BUFFER_OVERFLOW = 111  
ERROR_SUCCESS = 0  
  
MAX_DNS_SUFFIX_STRING_LENGTH = 256  
MAX_ADAPTER_DESCRIPTION_LENGTH = 128  
MAX_ADAPTER_NAME_LENGTH = 256  
  
# Define ctypes structures  
class SOCKADDR(ctypes.Structure):  
    _fields_ = [  
        ("sa_family", ctypes.wintypes.USHORT),  
        ("sa_data", ctypes.wintypes.BYTE * 14),  
    ]  
  
class SOCKET_ADDRESS(ctypes.Structure):  
    _fields_ = [  
        ("lpSockaddr", ctypes.POINTER(SOCKADDR)),  
        ("iSockaddrLength", ctypes.wintypes.INT),  
    ]  
  
class IP_ADAPTER_DNS_SERVER_ADDRESS(ctypes.Structure):  
    pass  
  
LP_IP_ADAPTER_DNS_SERVER_ADDRESS = ctypes.POINTER(IP_ADAPTER_DNS_SERVER_ADDRESS)  
  
IP_ADAPTER_DNS_SERVER_ADDRESS._fields_ = [  
    ("Length", ctypes.wintypes.ULONG),  
    ("Reserved", ctypes.wintypes.DWORD),  
    ("Next", LP_IP_ADAPTER_DNS_SERVER_ADDRESS),  
    ("Address", SOCKET_ADDRESS),  
]  
  
class IP_ADAPTER_ADDRESSES(ctypes.Structure):  
    pass  
  
LP_IP_ADAPTER_ADDRESSES = ctypes.POINTER(IP_ADAPTER_ADDRESSES)  
  
IP_ADAPTER_ADDRESSES._fields_ = [  
    ("Length", ctypes.wintypes.ULONG),  
    ("IfIndex", ctypes.wintypes.DWORD),  
    ("Next", LP_IP_ADAPTER_ADDRESSES),  
    ("AdapterName", ctypes.c_char_p),  
    ("FirstUnicastAddress", ctypes.POINTER(SOCKET_ADDRESS)),  
    ("FirstAnycastAddress", ctypes.POINTER(SOCKET_ADDRESS)),  
    ("FirstMulticastAddress", ctypes.POINTER(SOCKET_ADDRESS)),  
    ("FirstDnsServerAddress", LP_IP_ADAPTER_DNS_SERVER_ADDRESS),  
    ("DnsSuffix", ctypes.c_wchar * MAX_DNS_SUFFIX_STRING_LENGTH),  
    ("Description", ctypes.c_wchar * MAX_ADAPTER_DESCRIPTION_LENGTH),  
    ("FriendlyName", ctypes.c_wchar * MAX_ADAPTER_NAME_LENGTH),  
    # Additional fields are omitted for brevity  
]  
  
def print_dns_servers():  
    buffer_size = ctypes.wintypes.ULONG(15000)  # Initial buffer size for the adapter addresses  
    buffer = ctypes.create_string_buffer(buffer_size.value)  
  
    # Call GetAdaptersAddresses to fill the buffer  
    ret = iphlpapi.GetAdaptersAddresses(  
        AF_UNSPEC, GAA_FLAG_INCLUDE_PREFIX, None, buffer, ctypes.byref(buffer_size)  
    )  
  
    if ret == ERROR_BUFFER_OVERFLOW:  
        buffer = ctypes.create_string_buffer(buffer_size.value)  
        ret = iphlpapi.GetAdaptersAddresses(  
            AF_UNSPEC, GAA_FLAG_INCLUDE_PREFIX, None, buffer, ctypes.byref(buffer_size)  
        )  
  
    if ret != ERROR_SUCCESS:  
        print("Failed to retrieve adapter addresses")  
        return  
  
    # Cast buffer to IP_ADAPTER_ADDRESSES structure  
    current_address = ctypes.cast(buffer, LP_IP_ADAPTER_ADDRESSES)  
  
    # Iterate through the linked list of IP_ADAPTER_ADDRESSES  
    while current_address:  
        adapter = current_address.contents  
        dns_server_address = adapter.FirstDnsServerAddress  
  
        while dns_server_address:  
            sockaddr = dns_server_address.contents.Address.lpSockaddr.contents  
            if sockaddr.sa_family == socket.AF_INET:  
                # Extract IPv4 address, which is in sa_data[2:6]  
                ip_address_bytes = sockaddr.sa_data[2:6]  
                ip_address = ".".join(map(str, ip_address_bytes))  
                print(f"Adapter: {adapter.FriendlyName}")  
                print(f"DNS Server: {ip_address}")  
  
            dns_server_address = dns_server_address.contents.Next  
  
        current_address = adapter.Next  
  
if __name__ == '__main__':  
    print_dns_servers()