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https://github.com/Control-D-Inc/ctrld.git
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b4faf82f76
For cached or singleflight messages, the edns0 cookie is currently shared among all of them, causing mismatch cookie warning from clients. The ctrld proxy should re-set client cookies for each request separately, even though they use the same shared answer.
31 lines
831 B
Go
31 lines
831 B
Go
package ctrld
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import (
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"github.com/miekg/dns"
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)
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// SetCacheReply extracts and stores the necessary data from the message for a cached answer.
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func SetCacheReply(answer, msg *dns.Msg, code int) {
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answer.SetRcode(msg, code)
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cCookie := getEdns0Cookie(msg.IsEdns0())
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sCookie := getEdns0Cookie(answer.IsEdns0())
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if cCookie != nil && sCookie != nil {
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// Client cookie is fixed size 8 bytes, Server cookie is variable size 8 -> 32 bytes.
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// See https://datatracker.ietf.org/doc/html/rfc7873#section-4
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sCookie.Cookie = cCookie.Cookie[:16] + sCookie.Cookie[16:]
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}
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}
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// getEdns0Cookie returns Edns0 cookie from *dns.OPT if present.
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func getEdns0Cookie(opt *dns.OPT) *dns.EDNS0_COOKIE {
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if opt == nil {
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return nil
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}
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for _, o := range opt.Option {
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if e, ok := o.(*dns.EDNS0_COOKIE); ok {
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return e
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}
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}
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return nil
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}
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