#!/usr/bin/env python3
"""Verify Classic SRP login and realm listing without entering the game world."""
import argparse,hashlib,json,pathlib,secrets,socket,struct

def verify(host,port,credentials):
    username=credentials['username'].upper().encode();password=credentials['password'].upper().encode()
    def h(data):return hashlib.sha1(data).digest()
    with socket.create_connection((host,port),timeout=8) as sock:
        def read(n):
            data=b''
            while len(data)<n:
                block=sock.recv(n-len(data))
                if not block:raise RuntimeError('Authentication connection closed')
                data+=block
            return data
        payload=b'WoW\0'+bytes([1,12,1])+struct.pack('<H',5875)+b'68x\0'+b'niW\0'+b'SUne'+struct.pack('<I',0)+socket.inet_aton('127.0.0.1')+bytes([len(username)])+username
        sock.sendall(bytes([0,0])+struct.pack('<H',len(payload))+payload)
        header=read(3)
        if header!=b'\0\0\0':raise RuntimeError('Classic challenge rejected: '+header.hex())
        Braw=read(32);graw=read(read(1)[0]);Nraw=read(read(1)[0]);salt=read(32);read(16)
        flags=read(1)[0]
        if flags:raise RuntimeError('Unexpected extra authentication factor')
        N=int.from_bytes(Nraw,'little');g=int.from_bytes(graw,'little');B=int.from_bytes(Braw,'little')
        a=secrets.randbits(256);A=pow(g,a,N).to_bytes(32,'little')
        x=int.from_bytes(h(salt+h(username+b':'+password)),'little')
        u=int.from_bytes(h(A+Braw),'little')
        secret=pow((B-3*pow(g,x,N))%N,a+u*x,N).to_bytes(32,'little')
        even=h(secret[::2]);odd=h(secret[1::2]);key=bytes(v for pair in zip(even,odd) for v in pair)
        proof=h(bytes(x^y for x,y in zip(h(Nraw),h(graw)))+h(username)+salt+A+Braw+key)
        sock.sendall(b'\x01'+A+proof+bytes(20)+b'\0\0')
        result=read(2)
        if result!=b'\x01\0':raise RuntimeError('Classic password proof rejected: '+result.hex())
        if read(20)!=h(A+proof+key):raise RuntimeError('Server password proof did not match')
        read(4)
        sock.sendall(b'\x10'+bytes(4))
        if read(1)!=b'\x10':raise RuntimeError('Unexpected realm-list response')
        realms=read(struct.unpack('<H',read(2))[0])
        if b'AzerothAI Classic\0' not in realms:raise RuntimeError('Expected Classic realm missing')
        print('Classic password proof, server proof and AzerothAI Classic realm listing verified.')

if __name__=='__main__':
    p=argparse.ArgumentParser();p.add_argument('--root',type=pathlib.Path,required=True);p.add_argument('--host',default='127.0.0.1');p.add_argument('--port',type=int,default=3725);a=p.parse_args()
    verify(a.host,a.port,json.loads((a.root/'classic-gm-credentials.json').read_text()))