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tsdns: initial implementation of a Tailscale DNS resolver (#396)

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Signed-off-by: Dmytro Shynkevych <dmytro@tailscale.com>
This commit is contained in:
Dmytro Shynkevych
2020-06-08 18:19:26 -04:00
committed by GitHub
parent 5e1ee4be53
commit 511840b1f6
12 changed files with 583 additions and 109 deletions
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10
wgengine/packet/packet.go
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@ -102,7 +102,7 @@ func ipChecksum(b []byte) uint16 {
// It extracts only the subprotocol id, IP addresses, and (if any) ports,
// and shouldn't need any memory allocation.
func (q *ParsedPacket) Decode(b []byte) {
q.b = nil
q.b = b
if len(b) < ipHeaderLength {
q.IPProto = Unknown
@ -170,7 +170,6 @@ func (q *ParsedPacket) Decode(b []byte) {
}
q.SrcPort = 0
q.DstPort = 0
q.b = b
q.dataofs = q.subofs + icmpHeaderLength
return
case TCP:
@ -181,7 +180,6 @@ func (q *ParsedPacket) Decode(b []byte) {
q.SrcPort = get16(sub[0:2])
q.DstPort = get16(sub[2:4])
q.TCPFlags = sub[13] & 0x3F
q.b = b
headerLength := (sub[12] & 0xF0) >> 2
q.dataofs = q.subofs + int(headerLength)
return
@ -192,7 +190,6 @@ func (q *ParsedPacket) Decode(b []byte) {
}
q.SrcPort = get16(sub[0:2])
q.DstPort = get16(sub[2:4])
q.b = b
q.dataofs = q.subofs + udpHeaderLength
return
default:
@ -244,6 +241,11 @@ func (q *ParsedPacket) UDPHeader() UDPHeader {
}
}
// Buffer returns the entire packet buffer.
func (q *ParsedPacket) Buffer() []byte {
return q.b
}
// Sub returns the IP subprotocol section.
func (q *ParsedPacket) Sub(begin, n int) []byte {
return q.b[q.subofs+begin : q.subofs+begin+n]