9b94696b11
* plugin/edns: remove truncating of question section on bad EDNS version EDNS requests of "Unknown Version" removed the query section altogether. Not sure why since this is not require (see [link](https://kb.isc.org/docs/edns-compatibility-dig-queries) This cause issues with DNS solutions that uses this information (initial queried name, type and class) in order to route the response to the right client (e.g. PDNS). The change here is to keep the inital query section as is. Signed-off-by: Ben Kaplan <ben.kaplan@redis.com> * adding tests for edns0 version check Signed-off-by: Ben Kaplan <ben.kaplan@redis.com> * adding tests for non-edns0 version check Signed-off-by: Ben Kaplan <ben.kaplan@redis.com> Signed-off-by: Ben Kaplan <ben.kaplan@redis.com>
71 lines
1.7 KiB
Go
71 lines
1.7 KiB
Go
// Package edns provides function useful for adding/inspecting OPT records to/in messages.
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package edns
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import (
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"errors"
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"sync"
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"github.com/miekg/dns"
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)
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var sup = &supported{m: make(map[uint16]struct{})}
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type supported struct {
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m map[uint16]struct{}
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sync.RWMutex
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}
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// SetSupportedOption adds a new supported option the set of EDNS0 options that we support. Plugins typically call
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// this in their setup code to signal support for a new option.
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// By default we support:
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// dns.EDNS0NSID, dns.EDNS0EXPIRE, dns.EDNS0COOKIE, dns.EDNS0TCPKEEPALIVE, dns.EDNS0PADDING. These
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// values are not in this map and checked directly in the server.
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func SetSupportedOption(option uint16) {
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sup.Lock()
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sup.m[option] = struct{}{}
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sup.Unlock()
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}
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// SupportedOption returns true if the option code is supported as an extra EDNS0 option.
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func SupportedOption(option uint16) bool {
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sup.RLock()
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_, ok := sup.m[option]
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sup.RUnlock()
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return ok
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}
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// Version checks the EDNS version in the request. If error
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// is nil everything is OK and we can invoke the plugin. If non-nil, the
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// returned Msg is valid to be returned to the client (and should).
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func Version(req *dns.Msg) (*dns.Msg, error) {
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opt := req.IsEdns0()
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if opt == nil {
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return nil, nil
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}
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if opt.Version() == 0 {
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return nil, nil
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}
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m := new(dns.Msg)
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m.SetReply(req)
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o := new(dns.OPT)
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o.Hdr.Name = "."
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o.Hdr.Rrtype = dns.TypeOPT
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o.SetVersion(0)
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m.Rcode = dns.RcodeBadVers
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o.SetExtendedRcode(dns.RcodeBadVers)
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m.Extra = []dns.RR{o}
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return m, errors.New("EDNS0 BADVERS")
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}
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// Size returns a normalized size based on proto.
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func Size(proto string, size uint16) uint16 {
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if proto == "tcp" {
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return dns.MaxMsgSize
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}
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if size < dns.MinMsgSize {
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return dns.MinMsgSize
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}
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return size
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}
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