MVNO BSS/OSS Platform Architecture

# DIAMETER Cx User-Data-Request (UDR) to HSS
# Simulates S-CSCF querying HSS for subscriber profile

import socket
import struct

class DIAMETERCxInterface:
    def __init__(self, hss_host, hss_port=3868):
        self.hss_host = hss_host
        self.hss_port = hss_port
        self.socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

    def encode_avp(self, code, flags, vendor_id, data):
        """Encode DIAMETER AVP (Attribute-Value Pair)"""
        length = 8 + len(data)
        if length % 4:
            length += 4 - (length % 4)

        header = struct.pack('>I', code)
        header += struct.pack('B', flags)
        header += struct.pack('>I', length)[1:]

        if vendor_id:
            header += struct.pack('>I', vendor_id)

        return header + data + b'\x00' * (length - 8 - len(data))

    def fetch_subscriber(self, impu):
        """
        Send User-Data-Request (UDR) to HSS
        IMPU: IMS Public User Identity (e.g., sip:user@domain)
        """
        # Connect to HSS
        self.socket.connect((self.hss_host, self.hss_port))

        # Build DIAMETER message header
        # Cmd-Code: 300 (UDR)
        # Flags: 11000000 (Request, PXY)

        avps = []

        # Session-Id
        session_id = b"mvno.example.com;12345"
        avps.append(self.encode_avp(263, 0x40, 0, session_id))

        # Origin-Host (FQDN of S-CSCF)
        origin_host = b"scscf.mvno.example.com"
        avps.append(self.encode_avp(264, 0x40, 0, origin_host))

        # Origin-Realm
        origin_realm = b"mvno.example.com"
        avps.append(self.encode_avp(296, 0x40, 0, origin_realm))

        # Destination-Host (HSS)
        dest_host = b"hss.mvno.example.com"
        avps.append(self.encode_avp(293, 0x40, 0, dest_host))

        # Destination-Realm
        dest_realm = b"mvno.example.com"
        avps.append(self.encode_avp(283, 0x40, 0, dest_realm))

        # Public-Identity (IMPU) - 3GPP specific
        # AVP Code: 1657 (Public-Identity)
        avps.append(self.encode_avp(1657, 0xc0, 10415, impu.encode()))

        # Auth-Session-State: NO_STATE_MAINTAINED
        avps.append(self.encode_avp(277, 0x40, 0, struct.pack('>I', 1)))

        # Combine AVPs
        message_body = b"".join(avps)

        # DIAMETER Header: Version (1 byte) + Length (3 bytes) + Flags + Cmd-Code
        version = 0x01
        length = 20 + len(message_body)
        header = struct.pack('B', version)
        header += struct.pack('>I', length)[1:]  # 3-byte length
        header += struct.pack('B', 0xc0)  # Flags: Request, Proxiable
        header += struct.pack('>I', 300)[1:]  # Cmd-Code: 300 (UDR)
        header += struct.pack('>I', 0)  # App-Id: 16777216 (3GPP IMS)
        header += struct.pack('>I', 12345)  # Hop-by-Hop ID
        header += struct.pack('>I', 67890)  # End-to-End ID

        # Send message
        self.socket.send(header + message_body)

        # Receive UDR from HSS
        response = self.socket.recv(4096)
        return self.parse_response(response)

    def parse_response(self, data):
        """Parse User-Data-Answer (UDA) from HSS"""
        # Simplified parsing
        result = {
            'result_code': None,
            'subscriber_profile': None,
            'subscription_status': None,
        }

        # Extract Result-Code AVP (268)
        if b'\x01\x0c' in data:  # Simplified check
            result['result_code'] = 'DIAMETER_SUCCESS'
            result['subscriber_profile'] = {
                'impu': 'sip:[email protected]',
                'impi': '[email protected]',
                'subscription_state': 'ACTIVE',
                'service_profile': {
                    'initial_filter_criteria': [
                        'Allow voice calls',
                        'Allow SMS',
                        'Allow data (LTE)',
                    ]
                }
            }

        return result


# Usage example
if __name__ == '__main__':
    hss_client = DIAMETERCxInterface('hss.mvno.example.com', 3868)

    result = hss_client.fetch_subscriber('sip:[email protected]')

    print("HSS Query Result:", result)
    print("Subscriber Active:", result['subscriber_profile']['subscription_state'])