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Use the Date header field value first. #44

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merged 1 commit into from
Jan 4, 2024
Merged

Use the Date header field value first. #44

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70 changes: 32 additions & 38 deletions rfc9111/shared.go
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Original file line number Diff line number Diff line change
Expand Up @@ -323,71 +323,65 @@
ok, age := rule.Cacheable(req, res)
if ok {
// Add Expires header field
var expires time.Time
if res.Header.Get("Date") != "" {
date, err := http.ParseTime(res.Header.Get("Date"))
if err == nil {
expires = date.Add(age)
} else {
expires = now.Add(age)
}
} else {
expires = now.Add(age)
}
od := originDate(res.Header, now)
expires := od.Add(age)

Check failure on line 327 in rfc9111/shared.go

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[gostyle.varnames] "expires" is small scope. Variable name length of small scope should be less than or equal to 4. (THIS IS NOT IN Go Style)
res.Header.Set("Expires", expires.UTC().Format(http.TimeFormat))
return true, expires
}
}
return false, time.Time{}
}

func CalclateExpires(d *ResponseDirectives, header http.Header, heuristicExpirationRatio float64, now time.Time) time.Time {
func CalclateExpires(d *ResponseDirectives, resHeader http.Header, heuristicExpirationRatio float64, now time.Time) time.Time {
// 4.2.1. Calculating Freshness Lifetime
// A cache can calculate the freshness lifetime (denoted as freshness_lifetime) of a response by evaluating the following rules and using the first match:

// - If the cache is shared and the s-maxage response directive (https://httpwg.org/specs/rfc9111.html#rfc.section.5.2.2.10) is present, use its value, or
// - If the cache is shared and the s-maxage response directive (https://httpwg.org/specs/rfc9111.html#rfc.section.5.2.2.10) is present, use its value
if d.SMaxAge != nil {
return now.Add(time.Duration(*d.SMaxAge) * time.Second)
od := originDate(resHeader, now)
return od.Add(time.Duration(*d.SMaxAge) * time.Second)
}
// - If the max-age response directive (https://httpwg.org/specs/rfc9111.html#rfc.section.5.2.2.1) is present, use its value, or
// - If the max-age response directive (https://httpwg.org/specs/rfc9111.html#rfc.section.5.2.2.1) is present, use its value
if d.MaxAge != nil {
return now.Add(time.Duration(*d.MaxAge) * time.Second)
od := originDate(resHeader, now)
return od.Add(time.Duration(*d.MaxAge) * time.Second)
}
if header.Get("Expires") != "" {
// - If the Expires response header field (https://httpwg.org/specs/rfc9111.html#rfc.section.5.3) is present, use its value minus the value of the Date response header field
et, err := http.ParseTime(header.Get("Expires"))
if resHeader.Get("Expires") != "" {
// - If the Expires response header field (https://httpwg.org/specs/rfc9111.html#rfc.section.5.3) is present, use its value minus the value of the Date response header field (using the time the message was received if it is not present, as per Section 6.6.1 of [HTTP])
et, err := http.ParseTime(resHeader.Get("Expires"))
if err == nil {
if header.Get("Date") != "" {
dt, err := http.ParseTime(header.Get("Date"))
if err == nil {
return now.Add(et.Sub(dt))
}
} else {
// (using the time the message was received if it is not present, as per https://httpwg.org/specs/rfc9110.html#rfc.section.6.6.1 of [HTTP])
return et // == return now.Add(et.Sub(now))
}
od := originDate(resHeader, now)
return now.Add(et.Sub(od))
}
}
// Otherwise, no explicit expiration time is present in the response. A heuristic freshness lifetime might be applicable; see https://httpwg.org/specs/rfc9111.html#rfc.section.4.2.2.
if header.Get("Last-Modified") != "" {
lt, err := http.ParseTime(header.Get("Last-Modified"))
if resHeader.Get("Last-Modified") != "" {
lt, err := http.ParseTime(resHeader.Get("Last-Modified"))
if err == nil {
// If the response has a Last-Modified header field (https://httpwg.org/specs/rfc9110.html#rfc.section.8.8.2 of [HTTP]), caches are encouraged to use a heuristic expiration value that is no more than some fraction of the interval since that time. A typical setting of this fraction might be 10%.
if header.Get("Date") != "" {
dt, err := http.ParseTime(header.Get("Date"))
if err == nil {
return dt.Add(time.Duration(float64(dt.Sub(lt)) * heuristicExpirationRatio))
}
} else {
return now.Add(time.Duration(float64(now.Sub(lt)) * heuristicExpirationRatio))
}
od := originDate(resHeader, now)
return od.Add(time.Duration(float64(od.Sub(lt)) * heuristicExpirationRatio))
}
}

// Can't calculate expires
return time.Time{}
}

func originDate(resHeader http.Header, now time.Time) time.Time {
if resHeader.Get("Date") != "" {
t, err := http.ParseTime(resHeader.Get("Date"))
if err == nil {
return t
}
}
// A recipient with a clock that receives a response with an invalid Date header field value MAY replace that value with the time that response was received. (https://httpwg.org/specs/rfc9110.html#rfc.section.6.6.1 of [HTTP])
//
// ...using the time the message was received if it is not present, as per https://httpwg.org/specs/rfc9110.html#rfc.section.6.6.1 of [HTTP]
// (https://httpwg.org/specs/rfc9111.html#rfc.section.4.2.1)
return now
}

func contains[T comparable](v T, vv []T) bool {
for _, vvv := range vv {
if vvv == v {
Expand Down
2 changes: 1 addition & 1 deletion testdata/go_test.mod
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Original file line number Diff line number Diff line change
Expand Up @@ -4,7 +4,7 @@ go 1.21.5

require (
github.com/google/go-cmp v0.6.0
github.com/k1LoW/httpstub v0.11.1
github.com/k1LoW/httpstub v0.12.0
)

require (
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4 changes: 2 additions & 2 deletions testdata/go_test.sum
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Original file line number Diff line number Diff line change
Expand Up @@ -19,8 +19,8 @@ github.com/invopop/yaml v0.1.0 h1:YW3WGUoJEXYfzWBjn00zIlrw7brGVD0fUKRYDPAPhrc=
github.com/invopop/yaml v0.1.0/go.mod h1:2XuRLgs/ouIrW3XNzuNj7J3Nvu/Dig5MXvbCEdiBN3Q=
github.com/josharian/intern v1.0.0 h1:vlS4z54oSdjm0bgjRigI+G1HpF+tI+9rE5LLzOg8HmY=
github.com/josharian/intern v1.0.0/go.mod h1:5DoeVV0s6jJacbCEi61lwdGj/aVlrQvzHFFd8Hwg//Y=
github.com/k1LoW/httpstub v0.11.1 h1:amfxTttNX82F12kmUr9vrptpLl+nCUzHrEpvUqoCWQ0=
github.com/k1LoW/httpstub v0.11.1/go.mod h1:PYUmCF/2A7+TPhRPVJ4xSynM0O1x2mIjh+Tzd/DmiG8=
github.com/k1LoW/httpstub v0.12.0 h1:BDiTmO8G8FIdvDavHaYgl7+kVlQQACLESpC+02/DzQ0=
github.com/k1LoW/httpstub v0.12.0/go.mod h1:PYUmCF/2A7+TPhRPVJ4xSynM0O1x2mIjh+Tzd/DmiG8=
github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
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