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package ratelimit
import (
"errors"
"math"
"strconv"
"strings"
"time"
)
var errInvalidXSRLRetryAfter = errors.New("invalid retry-after value")
// parseXSentryRateLimits returns a RateLimits map by parsing an input string in
// the format of the X-Sentry-Rate-Limits header.
//
// Example
//
// X-Sentry-Rate-Limits: 60:transaction, 2700:default;error;security
//
// This will rate limit transactions for the next 60 seconds and errors for the
// next 2700 seconds.
//
// Limits for unknown categories are ignored.
func parseXSentryRateLimits(s string, now time.Time) Map {
// https://github.com/getsentry/relay/blob/0424a2e017d193a93918053c90cdae9472d164bf/relay-server/src/utils/rate_limits.rs#L44-L82
m := make(Map, len(knownCategories))
for _, limit := range strings.Split(s, ",") {
limit = strings.TrimSpace(limit)
if limit == "" {
continue
}
components := strings.Split(limit, ":")
if len(components) == 0 {
continue
}
retryAfter, err := parseXSRLRetryAfter(strings.TrimSpace(components[0]), now)
if err != nil {
continue
}
categories := ""
if len(components) > 1 {
categories = components[1]
}
for _, category := range strings.Split(categories, ";") {
c := Category(strings.ToLower(strings.TrimSpace(category)))
if _, ok := knownCategories[c]; !ok {
// skip unknown categories, keep m small
continue
}
// always keep the deadline furthest into the future
if retryAfter.After(m[c]) {
m[c] = retryAfter
}
}
}
return m
}
// parseXSRLRetryAfter parses a string into a retry-after rate limit deadline.
//
// Valid input is a number, possibly signed and possibly floating-point,
// indicating the number of seconds to wait before sending another request.
// Negative values are treated as zero. Fractional values are rounded to the
// next integer.
func parseXSRLRetryAfter(s string, now time.Time) (Deadline, error) {
// https://github.com/getsentry/relay/blob/0424a2e017d193a93918053c90cdae9472d164bf/relay-quotas/src/rate_limit.rs#L88-L96
f, err := strconv.ParseFloat(s, 64)
if err != nil {
return Deadline{}, errInvalidXSRLRetryAfter
}
d := time.Duration(math.Ceil(math.Max(f, 0.0))) * time.Second
if d < 0 {
d = 0
}
return Deadline(now.Add(d)), nil
}
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