/
header.go
115 lines (102 loc) · 3.73 KB
/
header.go
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package httd
import (
"errors"
"net/http"
"strconv"
"time"
"github.com/andersfylling/disgord/json"
)
// http rate limit identifiers
const (
XAuditLogReason = "X-Audit-Log-Reason"
XRateLimitPrecision = "X-RateLimit-Precision"
XRateLimitBucket = "X-RateLimit-Bucket"
XRateLimitLimit = "X-RateLimit-Limit"
XRateLimitRemaining = "X-RateLimit-Remaining"
XRateLimitReset = "X-RateLimit-Reset"
XRateLimitResetAfter = "X-RateLimit-Reset-After"
XRateLimitGlobal = "X-RateLimit-Global"
RateLimitRetryAfter = "Retry-After"
DisgordNormalizedHeader = "X-Disgord-Normalized-Kufdsfksduhf-S47yf"
XDisgordNow = "X-Disgord-Now-fsagkhf"
)
// HeaderToTime takes the response header from Discord and extracts the
// timestamp. Useful for detecting time desync between discord and client
func HeaderToTime(header http.Header) (t time.Time, err error) {
// date: Fri, 14 Sep 2018 19:04:24 GMT
dateStr := header.Get("date")
if dateStr == "" {
err = errors.New("missing header field 'date'")
return
}
t, err = time.Parse(time.RFC1123, dateStr)
return
}
type RateLimitResponseStructure struct {
Message string `json:"message"` // A message saying you are being rate limited.
RetryAfter float64 `json:"retry_after"` // The number of seconds to wait before submitting another request.
Global bool `json:"global"` // A value indicating if you are being globally rate limited or not
}
// NormalizeDiscordHeader overrides header fields with body content and make sure every header field
// uses milliseconds and not seconds. Regards rate limits only.
func NormalizeDiscordHeader(statusCode int, header http.Header, body []byte) (h http.Header, err error) {
secondsToMilli := func(s float64) int64 {
s *= 1000
return int64(s)
}
var now time.Time
if field := header.Get(XDisgordNow); field != "" {
n, err := strconv.ParseUint(field, 10, 64)
if err != nil {
now = time.Now()
} else {
now = time.Unix(0, int64(time.Duration(n)*time.Millisecond))
}
} else {
now = time.Now()
}
// don't care about 2 different time delay estimates for the ltBucket reset.
// So lets take Retry-After and X-RateLimit-Reset-After to set the reset
var delay int64
if retry := header.Get(XRateLimitResetAfter); delay == 0 && retry != "" {
delayF, _ := strconv.ParseFloat(retry, 64)
delay = secondsToMilli(delayF)
}
// sometimes the body might be populated too
if delay == 0 && statusCode == http.StatusTooManyRequests && body != nil {
var rateLimitBodyInfo *RateLimitResponseStructure
if err = json.Unmarshal(body, &rateLimitBodyInfo); err != nil {
return nil, err
}
if rateLimitBodyInfo.Global {
header.Set(XRateLimitGlobal, "true")
}
if delay == 0 && rateLimitBodyInfo.RetryAfter > 0 {
delay = secondsToMilli(rateLimitBodyInfo.RetryAfter)
}
}
// convert reset to store milliseconds and not seconds
// if there is no content, we create a reset unix using the delay
if reset := header.Get(XRateLimitReset); reset != "" {
if delay == 0 {
epoch, _ := strconv.ParseFloat(reset, 64)
epochMilli := secondsToMilli(epoch)
header.Set(XRateLimitReset, strconv.FormatInt(epochMilli, 10))
} else {
epochNow := now.UnixNano() / int64(time.Millisecond)
header.Set(XRateLimitReset, strconv.FormatInt(epochNow+delay, 10))
}
} else if delay > 0 {
timestamp, err := HeaderToTime(header)
if err != nil {
// does add an delay, but there is no reason
// to go insane if timestamp could not be handled
timestamp = now
}
resetTime := timestamp.Add(time.Duration(delay) * time.Millisecond)
ms := resetTime.UnixNano() / int64(time.Millisecond)
header.Set(XRateLimitReset, strconv.FormatInt(ms, 10))
}
header.Set(DisgordNormalizedHeader, "true")
return header, nil
}