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Date: Fri, 8 Aug 2014 14:11:25 +0200
Message-ID: <CANEZrP2UFMDJ+88MU=RTyU4FV_HCHwuHLmd5S9aK2AZ7DJ+j7g@mail.gmail.com>
From: Mike Hearn <mike@plan99.net>
To: Wladimir <laanwj@gmail.com>
Content-Type: multipart/alternative; boundary=047d7bd6c4e4b9930f05001d1a96
Cc: Bitcoin Dev <bitcoin-development@lists.sourceforge.net>
Subject: Re: [Bitcoin-development] NODE_EXT_SERVICES and advertising related
	services
Precedence: list

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>
> Something like `getutxos` or this proposal could be implemented as an
> external application or script, instead of having to integrate
> everything into bitcoind.
>

Right, although getutxos needs access to the UTXO set which bitcoind
already has. An external plugin would have to recalculate it from scratch
which seems redundant.

However there are many other useful services that could be added in such a
way, like -txindex or the nLockTime storage facility we talked about the
other day.


> Bitcoind would need a local interprocess message bus for that


Maybe, that feels like it could be overkill though. Probably just something
like

./bitcoind -servicecookie=<long random string> -allowextservices=127.0.0.1/8

and then any program can connect to bitcoind as normal, send "registersrv"
with the cookie and a list of command ids it's interested in, maybe a
service bit to set, and start receiving those messages wrapped in a new
structure that gives some kind of client ID (like IP address). So any
library that can do the basic P2P protocol could then be extended with not
much code to get a multiplexed stream of messages from different clients.

An additional standalone program can then bridge this mechanism to running
a shell command for particular messages, though given the history of shell
based exploits I'd feel safer with something that doesn't do that ....

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<div dir=3D"ltr"><div class=3D"gmail_extra"><div class=3D"gmail_quote"><blo=
ckquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #c=
cc solid;padding-left:1ex">Something like `getutxos` or this proposal could=
 be implemented as an<br>

external application or script, instead of having to integrate<br>
everything into bitcoind.<br></blockquote><div><br></div><div>Right, althou=
gh getutxos needs access to the UTXO set which bitcoind already has. An ext=
ernal plugin would have to recalculate it from scratch which seems redundan=
t.</div>
<div><br></div><div>However there are many other useful services that could=
 be added in such a way, like -txindex or the nLockTime storage facility we=
 talked about the other day.</div><div>=C2=A0</div><blockquote class=3D"gma=
il_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-lef=
t:1ex">
Bitcoind would need a local interprocess message bus for that</blockquote><=
div><br></div><div>Maybe, that feels like it could be overkill though. Prob=
ably just something like</div><div><br></div><div>./bitcoind -servicecookie=
=3D&lt;long random string&gt; -allowextservices=3D<a href=3D"http://127.0.0=
.1/8">127.0.0.1/8</a></div>
<div><br></div><div>and then any program can connect to bitcoind as normal,=
 send &quot;registersrv&quot; with the cookie and a list of command ids it&=
#39;s interested in, maybe a service bit to set, and start receiving those =
messages wrapped in a new structure that gives some kind of client ID (like=
 IP address). So any library that can do the basic P2P protocol could then =
be extended with not much code to get a multiplexed stream of messages from=
 different clients.</div>
<div><br></div><div>An additional standalone program can then bridge this m=
echanism to running a shell command for particular messages, though given t=
he history of shell based exploits I&#39;d feel safer with something that d=
oesn&#39;t do that ....</div>
</div></div></div>

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