logon_packets

authenticate(Opcode, Data, State) ->
    case logon_patterns:auth_request(Data) of
    {ok, Build, Account} ->
        case account_helper:find_by_name(Account) of
        [AccountRecord] -> 
            H = srp6:challenge(AccountRecord),
            NewState = State#logon_state{authenticated=no, account=AccountRecord, hash=H},
            {send, logon_patterns:auth_reply(H), NewState};
        _ ->
            {send, logon_patterns:error(Opcode, account_missing), State}
        end;
    _ ->
        wrong_packet(authenticate, Data),
        {send, logon_patterns:error(Opcode, account_missing), State}
    end.

logon_patterns

auth_request(<<_Err?B, _Size?W?IN, _Game:4?b, _Major?B, 
               _Middle?B, _Minor?B, Build?W?IN, _Platform:4?b, 
               _Os:4?b, _Country:4?b, _TimeZone?L?IN, _IP:4?b, 
               _Length?B, Account:_Length?b>>) ->
    {ok, Build, binary_to_list(Account)};