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Handle packing of empty RDATA correctly for EDNS0_EXPIRE (Resolves #1292) #1293

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merged 5 commits into from
Mar 12, 2022
Merged

Handle packing of empty RDATA correctly for EDNS0_EXPIRE (Resolves #1292) #1293

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8161c7d
Change EDNS_EXPIRE field to support zero length option data (Resolves…
dmavrommatis Sep 4, 2021
6f14f3c
addressed comments
dmavrommatis Sep 14, 2021
ba45878
addressed comments
dmavrommatis Oct 28, 2021
dc39a2c
make change backwards compatible
dmavrommatis Nov 4, 2021
37bd514
add comment for Empty field
dmavrommatis Mar 7, 2022
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16 changes: 14 additions & 2 deletions edns.go
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Original file line number Diff line number Diff line change
Expand Up @@ -577,14 +577,17 @@ func (e *EDNS0_N3U) copy() EDNS0 { return &EDNS0_N3U{e.Code, e.AlgCode} }
type EDNS0_EXPIRE struct {
Code uint16 // Always EDNS0EXPIRE
Expire uint32
Empty bool // Empty is used to signal an empty Expire option in a backwards compatible way, it's not used on the wire.
}

// Option implements the EDNS0 interface.
func (e *EDNS0_EXPIRE) Option() uint16 { return EDNS0EXPIRE }
func (e *EDNS0_EXPIRE) String() string { return strconv.FormatUint(uint64(e.Expire), 10) }
func (e *EDNS0_EXPIRE) copy() EDNS0 { return &EDNS0_EXPIRE{e.Code, e.Expire} }
func (e *EDNS0_EXPIRE) copy() EDNS0 { return &EDNS0_EXPIRE{e.Code, e.Expire, e.Empty} }

func (e *EDNS0_EXPIRE) pack() ([]byte, error) {
if e.Empty {
return []byte{}, nil
}
b := make([]byte, 4)
binary.BigEndian.PutUint32(b, e.Expire)
return b, nil
Expand All @@ -593,15 +596,24 @@ func (e *EDNS0_EXPIRE) pack() ([]byte, error) {
func (e *EDNS0_EXPIRE) unpack(b []byte) error {
if len(b) == 0 {
// zero-length EXPIRE query, see RFC 7314 Section 2
e.Empty = true
return nil
}
if len(b) < 4 {
return ErrBuf
}
e.Expire = binary.BigEndian.Uint32(b)
e.Empty = false
return nil
}

func (e *EDNS0_EXPIRE) String() (s string) {
if e.Empty {
return ""
}
return strconv.FormatUint(uint64(e.Expire), 10)
}

// The EDNS0_LOCAL option is used for local/experimental purposes. The option
// code is recommended to be within the range [EDNS0LOCALSTART, EDNS0LOCALEND]
// (RFC6891), although any unassigned code can actually be used. The content of
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