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 3CBFCCC67 for ; Fri, 8 Mar 2019 00:53:10 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-ed1-f42.google.com (mail-ed1-f42.google.com [209.85.208.42]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id A051B180 for ; Fri, 8 Mar 2019 00:53:09 +0000 (UTC) Received: by mail-ed1-f42.google.com with SMTP id p27so15053046edc.6 for ; Thu, 07 Mar 2019 16:53:09 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to; bh=fF5hTtggFSGvak4hGzUJJBwsAjgLNjMjMTS6kMYoOx4=; b=ILagmj4aJRrAT4wuPck+otpNIfKYm/9o5C5zixSmWVq2EuSnxZn6f2baEYN1AdD5H7 qbApz1pyS+n687PYoKnHzOaIAMt0t+qo3mEMcFsuibVkc4UBSO66tX1RSjHwKckyvnuG NUKDwnzaH+U7G5vuQbHFVs4dPixDCoMlChFIjPlV2pwapVf8NHyLn+vM86hyIEscp9Zt 1/oEMpq5VZi69mElrVz9F4pjmKYvqLCMKKRN7XWcGsUWu+2akAE8NPS1+eVMfoAt16P3 JeTznx1Y5jl13/qX2Ul9ngRhiMOcf8kKbXEixZDFiiBd+tUNEAhshOSlAua29PdeoyQn 0PVQ== X-Gm-Message-State: APjAAAUCnJWP2zLcdfoX8GjHnb9JvTwXF7ST/FA/OAeirWPG0SWQO0uW WJF4hqAkrx/Iab8z59SMA2tLd35XwJDsRuYamau9mg== X-Google-Smtp-Source: APXvYqwkXfRi9nhDnqPLs6isWICdW3g0dfPm9UAMs6IEsiQh+jeZaukob4UYB16nHaKjNaR+evb1ny32Y1c3TUlrryw= X-Received: by 2002:a17:906:81d0:: with SMTP id e16mr9766458ejx.243.1552006388277; Thu, 07 Mar 2019 16:53:08 -0800 (PST) MIME-Version: 1.0 References: <78CAF294-56E2-477C-B46F-C65A56357820@sprovoost.nl> In-Reply-To: From: Gregory Maxwell Date: Fri, 8 Mar 2019 00:52:56 +0000 Message-ID: To: Andreas Schildbach , Bitcoin Protocol Discussion Content-Type: text/plain; charset="UTF-8" X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,FREEMAIL_FROM, 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 X-Mailman-Approved-At: Fri, 08 Mar 2019 18:57:26 +0000 Subject: Re: [bitcoin-dev] Removal of reject network messages from Bitcoin Core (BIP61) 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: Fri, 08 Mar 2019 00:53:10 -0000 On Thu, Mar 7, 2019 at 11:46 PM Andreas Schildbach via bitcoin-dev wrote: > First and foremost, reject messages are an indication that the > transaction isn't going to confirm. Without these messages, we'd need to > revert to pre-BIP61 behaviour of using a timeout for reception of > network confirmations. That is already required because even in the presence of perfectly honest and cooperative hosts reject messages at most can only tell you about first-hop behaviour. It won't even tell you if the transaction was ever even attempted to be sent to a next hop. So alternative handling must be provided and must be reliable for the software to work at all regardless of reject messages. > - Not enough fee Rejection on low fee (over the static minimum feerate) only happens at the point where the nodes mempool is full, which is already at a point where you might be waiting weeks for confirmation. Rejection causes were also not stable or reliable because the validity criteria cannot generally be tested independently. For example, if a transaction is queued due to missing a parent it isn't rejected because missing the parent is often a temporary issue, but its feerate cannot be measured without the parent. Later, when the parent is obtained, the transaction can then be rejected due to feerate-- but no reject is sent then. Output already spend is often completely indistinguishable from a missing parent and can't get rejects generated for it generally. Similarly, the error state detected for things like invalid signatures are often not very useful. The software knows that script execution returned false, but in the general case _why_ it returned false is not clear, and a straightforward high performance validation implementation doesn't necessarily yield a good way of figuring out and propagating up that information. (I think invalid signatures end up returning a stack-nonempty state from validation currently, as an example of that).