From: Andreas Schildbach <andreas@schildbach•de>
To: bitcoin-development@lists•sourceforge.net
Subject: Re: [Bitcoin-development] BIP70/71 issue, RFD
Date: Sun, 26 Jan 2014 22:32:52 +0100 [thread overview]
Message-ID: <lc3utn$m8u$1@ger.gmane.org> (raw)
In-Reply-To: <CANEZrP2F-1aqzBfUB82riWOwTABf1arbx70FdQ-XndQ91m_QqA@mail.gmail.com>
Bluetooth, Wifi Direct, HTTP request/responses via broken proxies, smoke
signals... basically anything that is a stream rather than a file.
Right, NFC NDEF and QR codes are not affected, so we can skip the
delimiter for these mediums.
On 01/26/2014 10:24 PM, Mike Hearn wrote:
> Which medium is this an issue for? As you note, for files and HTTP
> responses it's not a problem in practice. i'd guess nor for NFC tags nor
> QR codes.
>
>
> On Sun, Jan 26, 2014 at 10:11 PM, Andreas Schildbach
> <andreas@schildbach•de <mailto:andreas@schildbach•de>> wrote:
>
> I'm experimenting with BIP70/71 (payment protocol) usage in face to face
> payments (more on that soon).
>
> I've excountered an issue with the protobuf format. Protobufs are not
> self-delimiting. That means if you're reading from an undelimited
> stream, you will read endlessly because you don't know how much to read.
>
> The current BIP70 implementations probably work because they're reading
> either from a file or from an HTTP resource which sets the
> Content-Length header. Trouble is the Content-Length header is optional,
> and also there are many kinds of streams that don't have this built-in
> delimiting mechanism.
>
> The Java protobuf API solves this by offering delimited I/O, like
>
> payment.writeDelimitedTo(os);
>
> This writes the size of the message as a varint before writing the data.
> I don't know about protobuf implementations for other languages but I'd
> expect them to offer something compatible.
>
> However, this leading varint is an incompatible change and would need to
> be added to the spec.
>
> I specifically encountered this with PaymentMessage and PaymentACK, but
> it might be a good idea to apply this to all messages if any. Open for
> discussion.
>
>
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next prev parent reply other threads:[~2014-01-26 21:33 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-26 21:11 Andreas Schildbach
2014-01-26 21:24 ` Mike Hearn
2014-01-26 21:32 ` Andreas Schildbach [this message]
2014-01-26 22:00 ` Mike Hearn
2014-01-26 22:14 ` Andreas Schildbach
2014-01-26 23:01 ` Mike Hearn
2014-01-27 2:05 ` Gavin
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