BIP70/71 issue, RFD
7 messages, 26 to 27 Jan 2014. Started by Andreas Schildbach.
Andreas Schildbach (3), Mike Hearn (3), Gavin Andresen
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.
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>wrote:
Quoted text (42 lines)
> 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. > > > > ------------------------------------------------------------------------------ > CenturyLink Cloud: The Leader in Enterprise Cloud Services. > Learn Why More Businesses Are Choosing CenturyLink Cloud For > Critical Workloads, Development Environments & Everything In Between. > Get a Quote or Start a Free Trial Today. > > http://pubads.g.doubleclick.net/gampad/clk?id=119420431&iu=/4140/ostg.clktrk > _______________________________________________ > Bitcoin-development mailing list > Bitcoin-development@lists•sourceforge•net > https://lists.sourceforge.net/lists/listinfo/bitcoin-development >
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:
Quoted text (66 lines)
> 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. > > > ------------------------------------------------------------------------------ > CenturyLink Cloud: The Leader in Enterprise Cloud Services. > Learn Why More Businesses Are Choosing CenturyLink Cloud For > Critical Workloads, Development Environments & Everything In Between. > Get a Quote or Start a Free Trial Today. > http://pubads.g.doubleclick.net/gampad/clk?id=119420431&iu=/4140/ostg.clktrk > _______________________________________________ > Bitcoin-development mailing list > Bitcoin-development@lists•sourceforge•net > <mailto:Bitcoin-development@lists.sourceforge.net> > https://lists.sourceforge.net/lists/listinfo/bitcoin-development > > > > > ------------------------------------------------------------------------------ > CenturyLink Cloud: The Leader in Enterprise Cloud Services. > Learn Why More Businesses Are Choosing CenturyLink Cloud For > Critical Workloads, Development Environments & Everything In Between. > Get a Quote or Start a Free Trial Today. > http://pubads.g.doubleclick.net/gampad/clk?id=119420431&iu=/4140/ostg.clktrk > > > > _______________________________________________ > Bitcoin-development mailing list > Bitcoin-development@lists•sourceforge•net > https://lists.sourceforge.net/lists/listinfo/bitcoin-development >
I think for "binding" the payment protocol to those transports we should indeed use protobuf varint length prefixes. But it's unnecessary for all cases. Unless Gavin feels it'd be better to be consistent everywhere and is willing to change the spec and code - as far as I know though we're trying to ship 0.9rc1 soonish .....
On Sun, Jan 26, 2014 at 10:32 PM, Andreas Schildbach <andreas@schildbach•de>wrote:
Quoted text (104 lines)
> 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. > > > > > > > ------------------------------------------------------------------------------ > > CenturyLink Cloud: The Leader in Enterprise Cloud Services. > > Learn Why More Businesses Are Choosing CenturyLink Cloud For > > Critical Workloads, Development Environments & Everything In Between. > > Get a Quote or Start a Free Trial Today. > > > http://pubads.g.doubleclick.net/gampad/clk?id=119420431&iu=/4140/ostg.clktrk > > _______________________________________________ > > Bitcoin-development mailing list > > Bitcoin-development@lists•sourceforge•net > > <mailto:Bitcoin-development@lists.sourceforge.net> > > https://lists.sourceforge.net/lists/listinfo/bitcoin-development > > > > > > > > > > > ------------------------------------------------------------------------------ > > CenturyLink Cloud: The Leader in Enterprise Cloud Services. > > Learn Why More Businesses Are Choosing CenturyLink Cloud For > > Critical Workloads, Development Environments & Everything In Between. > > Get a Quote or Start a Free Trial Today. > > > http://pubads.g.doubleclick.net/gampad/clk?id=119420431&iu=/4140/ostg.clktrk > > > > > > > > _______________________________________________ > > Bitcoin-development mailing list > > Bitcoin-development@lists•sourceforge•net > > https://lists.sourceforge.net/lists/listinfo/bitcoin-development > > > > > > > ------------------------------------------------------------------------------ > CenturyLink Cloud: The Leader in Enterprise Cloud Services. > Learn Why More Businesses Are Choosing CenturyLink Cloud For > Critical Workloads, Development Environments & Everything In Between. > Get a Quote or Start a Free Trial Today. > > http://pubads.g.doubleclick.net/gampad/clk?id=119420431&iu=/4140/ostg.clktrk > _______________________________________________ > Bitcoin-development mailing list > Bitcoin-development@lists•sourceforge•net > https://lists.sourceforge.net/lists/listinfo/bitcoin-development >
Just keep in mind that if it turns out we need to retrofit messages with length prefixes I fear we will have to restart with new mime-types. The nature of prefixes being always at the start means this rules out simply incrementing a protocol version number.
Correcting myself:
Quoted text (1 line)
> it might be a good idea to apply this to all messages if any.
Of course I only mean the "root" messages, namely PaymentRequest, Payment, and PaymentACK. The embedded messages don't need length prefixes.
On 01/26/2014 11:00 PM, Mike Hearn wrote:
Quoted text (137 lines)
> I think for "binding" the payment protocol to those transports we should > indeed use protobuf varint length prefixes. But it's unnecessary for all > cases. Unless Gavin feels it'd be better to be consistent everywhere and > is willing to change the spec and code - as far as I know though we're > trying to ship 0.9rc1 soonish ..... > > > On Sun, Jan 26, 2014 at 10:32 PM, Andreas Schildbach > <andreas@schildbach•de <mailto:andreas@schildbach.de>> wrote: > > 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> > <mailto: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. > > > > > > > ------------------------------------------------------------------------------ > > CenturyLink Cloud: The Leader in Enterprise Cloud Services. > > Learn Why More Businesses Are Choosing CenturyLink Cloud For > > Critical Workloads, Development Environments & Everything In > Between. > > Get a Quote or Start a Free Trial Today. > > > http://pubads.g.doubleclick.net/gampad/clk?id=119420431&iu=/4140/ostg.clktrk > > _______________________________________________ > > Bitcoin-development mailing list > > Bitcoin-development@lists•sourceforge•net > <mailto:Bitcoin-development@lists.sourceforge.net> > > <mailto:Bitcoin-development@lists.sourceforge.net > <mailto:Bitcoin-development@lists.sourceforge.net>> > > https://lists.sourceforge.net/lists/listinfo/bitcoin-development > > > > > > > > > > > ------------------------------------------------------------------------------ > > CenturyLink Cloud: The Leader in Enterprise Cloud Services. > > Learn Why More Businesses Are Choosing CenturyLink Cloud For > > Critical Workloads, Development Environments & Everything In Between. > > Get a Quote or Start a Free Trial Today. > > > http://pubads.g.doubleclick.net/gampad/clk?id=119420431&iu=/4140/ostg.clktrk > > > > > > > > _______________________________________________ > > Bitcoin-development mailing list > > Bitcoin-development@lists•sourceforge•net > <mailto:Bitcoin-development@lists.sourceforge.net> > > https://lists.sourceforge.net/lists/listinfo/bitcoin-development > > > > > > ------------------------------------------------------------------------------ > CenturyLink Cloud: The Leader in Enterprise Cloud Services. > Learn Why More Businesses Are Choosing CenturyLink Cloud For > Critical Workloads, Development Environments & Everything In Between. > Get a Quote or Start a Free Trial Today. > http://pubads.g.doubleclick.net/gampad/clk?id=119420431&iu=/4140/ostg.clktrk > _______________________________________________ > Bitcoin-development mailing list > Bitcoin-development@lists•sourceforge•net > <mailto:Bitcoin-development@lists.sourceforge.net> > https://lists.sourceforge.net/lists/listinfo/bitcoin-development > > > > > ------------------------------------------------------------------------------ > CenturyLink Cloud: The Leader in Enterprise Cloud Services. > Learn Why More Businesses Are Choosing CenturyLink Cloud For > Critical Workloads, Development Environments & Everything In Between. > Get a Quote or Start a Free Trial Today. > http://pubads.g.doubleclick.net/gampad/clk?id=119420431&iu=/4140/ostg.clktrk > > > > _______________________________________________ > Bitcoin-development mailing list > Bitcoin-development@lists•sourceforge•net > https://lists.sourceforge.net/lists/listinfo/bitcoin-development >
To be more accurate, the embedded messages already have length prefixes :-)
On Sun, Jan 26, 2014 at 11:14 PM, Andreas Schildbach <andreas@schildbach•de>wrote:
Quoted text (181 lines)
> Just keep in mind that if it turns out we need to retrofit messages with > length prefixes I fear we will have to restart with new mime-types. The > nature of prefixes being always at the start means this rules out simply > incrementing a protocol version number. > > Correcting myself: > > > it might be a good idea to apply this to all messages if any. > > Of course I only mean the "root" messages, namely PaymentRequest, > Payment, and PaymentACK. The embedded messages don't need length prefixes. > > > On 01/26/2014 11:00 PM, Mike Hearn wrote: > > I think for "binding" the payment protocol to those transports we should > > indeed use protobuf varint length prefixes. But it's unnecessary for all > > cases. Unless Gavin feels it'd be better to be consistent everywhere and > > is willing to change the spec and code - as far as I know though we're > > trying to ship 0.9rc1 soonish ..... > > > > > > On Sun, Jan 26, 2014 at 10:32 PM, Andreas Schildbach > > <andreas@schildbach•de <mailto:andreas@schildbach.de>> wrote: > > > > 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> > > <mailto: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. > > > > > > > > > > > > ------------------------------------------------------------------------------ > > > CenturyLink Cloud: The Leader in Enterprise Cloud Services. > > > Learn Why More Businesses Are Choosing CenturyLink Cloud For > > > Critical Workloads, Development Environments & Everything In > > Between. > > > Get a Quote or Start a Free Trial Today. > > > > > > http://pubads.g.doubleclick.net/gampad/clk?id=119420431&iu=/4140/ostg.clktrk > > > _______________________________________________ > > > Bitcoin-development mailing list > > > Bitcoin-development@lists•sourceforge•net > > <mailto:Bitcoin-development@lists.sourceforge.net> > > > <mailto:Bitcoin-development@lists.sourceforge.net > > <mailto:Bitcoin-development@lists.sourceforge.net>> > > > > https://lists.sourceforge.net/lists/listinfo/bitcoin-development > > > > > > > > > > > > > > > > > > ------------------------------------------------------------------------------ > > > CenturyLink Cloud: The Leader in Enterprise Cloud Services. > > > Learn Why More Businesses Are Choosing CenturyLink Cloud For > > > Critical Workloads, Development Environments & Everything In > Between. > > > Get a Quote or Start a Free Trial Today. > > > > > > http://pubads.g.doubleclick.net/gampad/clk?id=119420431&iu=/4140/ostg.clktrk > > > > > > > > > > > > _______________________________________________ > > > Bitcoin-development mailing list > > > Bitcoin-development@lists•sourceforge•net > > <mailto:Bitcoin-development@lists.sourceforge.net> > > > https://lists.sourceforge.net/lists/listinfo/bitcoin-development > > > > > > > > > > > > ------------------------------------------------------------------------------ > > CenturyLink Cloud: The Leader in Enterprise Cloud Services. > > Learn Why More Businesses Are Choosing CenturyLink Cloud For > > Critical Workloads, Development Environments & Everything In Between. > > Get a Quote or Start a Free Trial Today. > > > http://pubads.g.doubleclick.net/gampad/clk?id=119420431&iu=/4140/ostg.clktrk > > _______________________________________________ > > Bitcoin-development mailing list > > Bitcoin-development@lists•sourceforge•net > > <mailto:Bitcoin-development@lists.sourceforge.net> > > https://lists.sourceforge.net/lists/listinfo/bitcoin-development > > > > > > > > > > > ------------------------------------------------------------------------------ > > CenturyLink Cloud: The Leader in Enterprise Cloud Services. > > Learn Why More Businesses Are Choosing CenturyLink Cloud For > > Critical Workloads, Development Environments & Everything In Between. > > Get a Quote or Start a Free Trial Today. > > > http://pubads.g.doubleclick.net/gampad/clk?id=119420431&iu=/4140/ostg.clktrk > > > > > > > > _______________________________________________ > > Bitcoin-development mailing list > > Bitcoin-development@lists•sourceforge•net > > https://lists.sourceforge.net/lists/listinfo/bitcoin-development > > > > > > > ------------------------------------------------------------------------------ > CenturyLink Cloud: The Leader in Enterprise Cloud Services. > Learn Why More Businesses Are Choosing CenturyLink Cloud For > Critical Workloads, Development Environments & Everything In Between. > Get a Quote or Start a Free Trial Today. > > http://pubads.g.doubleclick.net/gampad/clk?id=119420431&iu=/4140/ostg.clktrk > _______________________________________________ > Bitcoin-development mailing list > Bitcoin-development@lists•sourceforge•net > https://lists.sourceforge.net/lists/listinfo/bitcoin-development >
Message encoding and length (or terminator or checksum or error correction or...) should be part of the transport protocol, in my humble opinion.