From: Mark Nottingham <mnot@mnot.net>

Date: Thu, 30 Jan 2020 09:21:56 +1100

Cc: HTTP Working Group <ietf-http-wg@w3.org>, Poul-Henning Kamp <phk@varnish-cache.org>

Message-Id: <9E4F45C3-1B74-458D-AE93-E6EA6BE58A9C@mnot.net>

To: Kari Hurtta <hurtta-ietf@elmme-mailer.org>

Date: Thu, 30 Jan 2020 09:21:56 +1100

Cc: HTTP Working Group <ietf-http-wg@w3.org>, Poul-Henning Kamp <phk@varnish-cache.org>

Message-Id: <9E4F45C3-1B74-458D-AE93-E6EA6BE58A9C@mnot.net>

To: Kari Hurtta <hurtta-ietf@elmme-mailer.org>

Hi Kari, Very good catch; I noticed this a while back but forgot to file an issue. Now: https://github.com/httpwg/http-extensions/issues/1043 Cheers, > On 30 Jan 2020, at 5:17 am, Kari Hurtta <hurtta-ietf@elmme-mailer.org> wrote: > > 4.1.5. Serializing a Decimal > https://tools.ietf.org/html/draft-ietf-httpbis-header-structure-15#section-4.1.5 > > > | Given a decimal_number as input_decimal, return an ASCII string > | suitable for use in a HTTP header value. > | > | 1. Let output be an empty string. > | > | 2. If input_decimal is less than (but not equal to) 0, append "-" to > | output. > | > | 3. Append input_decimal's integer component represented in base 10 > | (using only decimal digits) to output; if it is zero, append "0". > | > | 4. If the number of characters appended in the previous step is > | greater than 12, fail serialisation. > | > | 5. Append "." to output. > | > | 6. If input_decimal's fractional component is zero, append "0" to > | output. > | > | 7. Else if input_decimal's fractional component has up to three > | digits, append them represented in base 10 (using only decimal > | digits) to output. > | > | 8. Otherwise, append the first three digits of input_decimal's > | fractional component (represented in base 10, using only decimal > | digits) to output, rounding the final digit to the nearest value, > | or to the even value if it is equidistant. > | > | 9. Return output. > > I'm not sure how this works. > > > Let's input_decimal to be 123.9998 > > After step 3 output is "123" > > After step 5 output is "123." > > On step 8 the first three digits of input_decimal's fractional component > are "999". > > The final digit is "9". There is no possiblity to round up that digit. > > So final output is "123.999". > > Is that orrect ? That is effectively truncation. > > If 123.9998 is rounded to 3 fractional decimals, value is 124.000, > but that serialization can not produce it. > > / Kari Hurtta > > -- Mark Nottingham https://www.mnot.net/Received on Wednesday, 29 January 2020 22:22:06 UTC

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