From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id CC6F172A for ; Mon, 13 Feb 2017 08:47:40 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-wm0-f68.google.com (mail-wm0-f68.google.com [74.125.82.68]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 3431488 for ; Mon, 13 Feb 2017 08:47:40 +0000 (UTC) Received: by mail-wm0-f68.google.com with SMTP id r18so18086819wmd.3 for ; Mon, 13 Feb 2017 00:47:40 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=nIQIguwARaPwMj/oezltyRypJTKAhsAyUsN7hpsiY74=; b=dusZ+SSLdqTJdTy9j1rXxCQVHqniW5wKbVf9NyzXQRqf3WgtbtGkLe/OY04G5Vx/Oz EJb/fJSr2tudDGRlpKRUk81CerRaJX9zmTJ7dRT8sC2m5Pl6njEoD812gkKpDkQuGTP4 CkSntCDlIt5rWRdfBKCblvymnjnwC+TlU+8S88Uqd90zKc+eDnpDSkVi4uZo3erMf/JG 6TNz8e+v+eN/w1r4KdOIYTOynSGr53tQAOhFF2WiSZh74pxLUxeHQtgmynMChmknP7JO VU6j0/z/0FbbMIjaDRrp4im4X9+6mZRpic5zqYuVfrcdt/zaXaLQKRdv3jr9IKaIuI8D wxGw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=nIQIguwARaPwMj/oezltyRypJTKAhsAyUsN7hpsiY74=; b=Y4WLGQnTF1rGEJvSoPnuPz8ZB3M7/iveSTfqVGto1yv1yI047gNUHM0X4Poc4sr56S zmnXE78ki5Gs8a++6rURh67EuvORV6D2i/kZbUYVSS71lo9O0QMgMcdjo8GOYhuHt3vN BV9O7R4Y0rVSKgMSC5RgzdK48oMUwIXhKyN2UyVrHJI9tradyViiuWxNgLSwA/LpiY9n aqFEBeTv6ZZSOwQZ+lsvAbjsXOY0/r5qNa/tlrf+Grp+PZqmUrAuxDVu8nSWBBx9ab23 Ru3ht6BWTwFWhJYppRYnAadwuzD6VEsHt2XVm0tUdZwyCI+ZlXxYMUFxAA3gxR1VbmyT Iraw== X-Gm-Message-State: AMke39kRn/lUVqwX+wQfsxk1clUxhY9LrgFG13fQbXUfWg7AIZ8EmBFkbdVzXPaL4RIwh6opfED3bkKjMGnKoQ== X-Received: by 10.28.180.132 with SMTP id d126mr37928800wmf.123.1486975658693; Mon, 13 Feb 2017 00:47:38 -0800 (PST) MIME-Version: 1.0 Received: by 10.80.142.68 with HTTP; Mon, 13 Feb 2017 00:47:38 -0800 (PST) Received: by 10.80.142.68 with HTTP; Mon, 13 Feb 2017 00:47:38 -0800 (PST) In-Reply-To: References: From: Pieter Wuille Date: Mon, 13 Feb 2017 00:47:38 -0800 Message-ID: To: Bitcoin Dev , Eric Voskuil Content-Type: multipart/alternative; boundary=001a114b2e44ed1f950548657f1f X-Spam-Status: No, score=-2.0 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, FREEMAIL_FROM, HTML_MESSAGE, RCVD_IN_DNSWL_NONE autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org Cc: libbitcoin@lists.dyne.org Subject: Re: [bitcoin-dev] BIP151 protocol incompatibility X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Bitcoin Protocol Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 13 Feb 2017 08:47:40 -0000 --001a114b2e44ed1f950548657f1f Content-Type: text/plain; charset=UTF-8 On Feb 12, 2017 23:58, "Eric Voskuil via bitcoin-dev" < bitcoin-dev@lists.linuxfoundation.org> wrote: The BIP151 proposal states: > This proposal is backward compatible. Non-supporting peers will ignore the encinit messages. This statement is incorrect. Sending content that existing nodes do not expect is clearly an incompatibility. An implementation that ignores invalid content leaves itself wide open to DOS attacks. The version handshake must be complete before the protocol level can be determined. While it may be desirable for this change to precede the version handshake it cannot be described as backward compatible. The worst possible effect of ignoring unknown messages is a waste of downstream bandwidth. The same is already possible by being sent addr messages. Using the protocol level requires a strict linear progression of (allowed) network protocol features, which I expect to become harder and harder to maintain. Using otherwise ignored messages for determining optional features is elegant, simple and opens no new attack vectors. I think it's very much preferable over continued increments of the protocol version. -- Pieter --001a114b2e44ed1f950548657f1f Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable


On Feb 12, 2017 23:58, "Eric Voskuil via bitcoin-dev" &= lt;bitcoin-dev@lis= ts.linuxfoundation.org> wrote:
The BIP151 proposal states:

> This proposal is backward compatible. Non-supporting peers will ignore=
the encinit messages.

This statement is incorrect. Sending content that existing nodes do not
expect is clearly an incompatibility. An implementation that ignores
invalid content leaves itself wide open to DOS attacks. The version
handshake must be complete before the protocol level can be determined.
While it may be desirable for this change to precede the version
handshake it cannot be described as backward compatible.
=

The worst possibl= e effect of ignoring unknown messages is a waste of downstream bandwidth. T= he same is already possible by being sent addr messages.

Using the protocol level requires a strict= linear progression of (allowed) network protocol features, which I expect = to become harder and harder to maintain.

<= div dir=3D"auto">Using otherwise ignored messages for determining optional = features is elegant, simple and opens no new attack vectors. I think it'= ;s very much preferable over continued increments of the protocol version.<= /div>

--=C2=A0
Pieter

<= div dir=3D"auto">

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