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Date: Wed, 30 Oct 2013 12:01:16 +1000
Message-ID: <CABsx9T25sqq5ps+ePgc+tH+ns8ygahpYztgga0DuqgoQj9tpzQ@mail.gmail.com>
From: Gavin Andresen <gavinandresen@gmail.com>
To: Mike Hearn <mike@plan99.net>
Content-Type: multipart/alternative; boundary=001a11c25c9e609aee04e9ebb507
Cc: Bitcoin Development <bitcoin-development@lists.sourceforge.net>,
	Andreas Schildbach <andreas@schildbach.de>
Subject: Re: [Bitcoin-development] Feedback requested: "reject" p2p message
Precedence: list

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On Tue, Oct 29, 2013 at 10:32 PM, Mike Hearn <mike@plan99.net> wrote:

> Yes, exactly. That's the point. As you well know I think the whole
> soft-fork mechanism is wrong and should not be used. If the rules change,
> your node is *supposed* to end up on a chain fork and trigger an alert to
> you, that's pretty much the whole purpose of Bitcoin's design. Undermining
> that security model is problematic.
>

But if you are getting soft-forked recent versions of the reference
implementation WILL alert you; see this code in main.cpp:

        if (nUpgraded > 100/2)
            strMiscWarning = _("Warning: This version is obsolete, upgrade
required!");

That is, if more than half of the last 100 blocks are up-version, warn.
 block.version is part of the block header, so SPV clients can (and
probably should) do the same.

There are also warnings if you are forked, and, most recently, warnings if
there is a high-work alternative fork.

-- 
--
Gavin Andresen

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<div dir=3D"ltr">On Tue, Oct 29, 2013 at 10:32 PM, Mike Hearn <span dir=3D"=
ltr">&lt;<a href=3D"mailto:mike@plan99.net" target=3D"_blank">mike@plan99.n=
et</a>&gt;</span> wrote:<br><div class=3D"gmail_extra"><div class=3D"gmail_=
quote"><blockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;=
border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:=
solid;padding-left:1ex">
<div dir=3D"ltr">Yes, exactly. That&#39;s the point. As you well know I thi=
nk the whole soft-fork mechanism is wrong and should not be used. If the ru=
les change, your node is *supposed* to end up on a chain fork and trigger a=
n alert to you, that&#39;s pretty much the whole purpose of Bitcoin&#39;s d=
esign. Undermining that security model is problematic.</div>
</blockquote><div><br></div><div>But if you are getting soft-forked recent =
versions of the reference implementation WILL alert you; see this code in m=
ain.cpp:</div><div><br></div><div><div>=A0 =A0 =A0 =A0 if (nUpgraded &gt; 1=
00/2)</div>
<div>=A0 =A0 =A0 =A0 =A0 =A0 strMiscWarning =3D _(&quot;Warning: This versi=
on is obsolete, upgrade required!&quot;);</div></div><div><br></div><div>Th=
at is, if more than half of the last 100 blocks are up-version, warn. =A0bl=
ock.version is part of the block header, so SPV clients can (and probably s=
hould) do the same.</div>
<div><br></div><div>There are also warnings if you are forked, and, most re=
cently, warnings if there is a high-work alternative fork.</div><div><br></=
div></div>-- <br>--<br>Gavin Andresen<br>
</div></div>

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