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From: Eric Voskuil <eric@voskuil.org>
To: Matt Corallo <lf-lists@mattcorallo.com>,
	Bitcoin Protocol Discussion
	<bitcoin-dev@lists.linuxfoundation.org>,
	Pieter Wuille <pieter.wuille@gmail.com>
Cc: libbitcoin@lists.dyne.org
Subject: Re: [bitcoin-dev] BIP151 protocol incompatibility
Date: Mon, 13 Feb 2017 03:17:11 -0800	[thread overview]
Message-ID: <0983c823-e517-2821-1398-24bc7467b364@voskuil.org> (raw)
In-Reply-To: <9ECDD902-1D2C-4500-8FC2-4DADF46E4318@mattcorallo.com>

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On 02/13/2017 03:11 AM, Matt Corallo wrote:
> I believe many, if not all, of those messages are sent irrespective of version number.

In the interest of perfect clarity, see your code:

https://github.com/bitcoin/bitcoin/blob/master/src/net_processing.cpp#L1372-L1403

Inside of the VERACK handler (i.e. after the handshake) there is a peer
version test before sending SENDCMPCT (and SENDHEADERS).

I have no idea where the fee filter message is sent, if it is sent at
all. But I have *never* seen any control messages arrive before the
handshake is complete.

> In any case, I fail to see how adding any additional messages which
are ignored by old peers amounts to a lack of backward compatibility.

See preceding messages in this thread, I think it's pretty clearly
spelled out.

e

> On February 13, 2017 11:54:23 AM GMT+01:00, Eric Voskuil <eric@voskuil.org> wrote:
>> On 02/13/2017 02:16 AM, Matt Corallo wrote:
>>> For the reasons Pieter listed, an explicit part of our version
>> handshake and protocol negotiation is the exchange of otherwise-ignored
>> messages to set up optional features.
>>
>> Only if the peer is at the protocol level that allows the message:
>>
>> compact blocks:
>>
>> https://github.com/bitcoin/bitcoin/blob/master/src/protocol.h#L217-L242
>>
>> fee filter:
>>
>> https://github.com/bitcoin/bitcoin/blob/master/src/protocol.h#L211-L216
>>
>> send headers:
>>
>> https://github.com/bitcoin/bitcoin/blob/master/src/protocol.h#L204-L210
>>
>> filters:
>>
>> https://github.com/bitcoin/bitcoin/blob/master/src/protocol.h#L170-L196
>>
>>> Peers that do not support this ignore such messages, just as if they
>> had indicated they wouldn't support it, see, eg BIP 152's handshake.
>> Not
>> sure why you consider this backwards incompatible, as I would say it's
>> pretty clearly allowing old nodes to communicate just fine.
>>
>> No, it is not the same as BIP152. Control messages apart from BIP151
>> are
>> not sent until *after* the version is negotiated.
>>
>> I assume that BIP151 is different in this manner because it has a
>> desire
>> to negotiate encryption before any other communications, including
>> version.
>>
>> e


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  reply	other threads:[~2017-02-13 11:17 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-02-13  5:18 [bitcoin-dev] BIP151 protocol incompatibility Eric Voskuil
2017-02-13  8:47 ` Pieter Wuille
2017-02-13  9:36   ` Eric Voskuil
2017-02-13 10:07     ` Jonas Schnelli
2017-02-13 10:30       ` Eric Voskuil
2017-02-13 11:14         ` Jonas Schnelli
2017-02-14 19:54           ` Eric Voskuil
2017-02-14 20:58             ` Jonas Schnelli
2017-02-13 10:16     ` Matt Corallo
2017-02-13 10:54       ` Eric Voskuil
2017-02-13 11:11         ` Matt Corallo
2017-02-13 11:17           ` Eric Voskuil [this message]
2017-02-13 13:04             ` Matt Corallo

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