Matthias Radestock
5b6dc2d762
Issues with the previous scheme... When we have just encountered an EMSGSIZE, the odds of encountering another one straight away, when attemtping to send a verification packet with the lower mtu, are slim, since for a new, lower mtu to be set some packet must have made it further then the one that triggered the icmp3.4 that gave rise to the EMSGSIZE, and we must have received the resulting icmp3.4. All of which takes time. Also, sending a bunch of udp packets in rapid succession is not a great way to improve their chances of making it through to the other peer, since they could easily all get dropped by a single congestion event or other network glitch. Now we send a single verification packet, wait for a short while, and if we don't get a response then we send another one, wait for longer period (2x), etc, until some upper bound is reached, at which point we lower the pmtu and start the verification process again (same as currently happens). We are now also calling flush() to send the verification packet, just as we do for ordinary packets. This makes for shorter code, consistent error handling, and introduces a nice little recursion :)
48 lines
1.5 KiB
Go
48 lines
1.5 KiB
Go
package weave
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import (
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"time"
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)
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const (
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Protocol = "weave"
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ProtocolVersion = 8
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EthernetOverhead = 14
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UDPOverhead = 28 // 20 bytes for IPv4, 8 bytes for UDP
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Port = 6783
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DefaultPMTU = 65535
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MaxUDPPacketSize = 65536
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ChannelSize = 16
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UDPNonceSendAt = 8192
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FragTestSize = 60001
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PMTUDiscoverySize = 60000
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FastHeartbeat = 500 * time.Millisecond
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SlowHeartbeat = 10 * time.Second
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FetchAllInterval = 30 * time.Second
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FragTestInterval = 5 * time.Minute
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PMTUVerifyAttempts = 8
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PMTUVerifyTimeout = 10 * time.Millisecond // gets doubled with every attempt
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)
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const (
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ProtocolConnectionEstablished = iota
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ProtocolFragmentationReceived = iota
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ProtocolStartFragmentationTest = iota
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ProtocolNonce = iota
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ProtocolFetchAll = iota
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ProtocolUpdate = iota
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ProtocolPMTUVerified = iota
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)
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var (
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FragTest = make([]byte, FragTestSize)
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PMTUDiscovery = make([]byte, PMTUDiscoverySize)
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ProtocolConnectionEstablishedByte = []byte{ProtocolConnectionEstablished}
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ProtocolFragmentationReceivedByte = []byte{ProtocolFragmentationReceived}
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ProtocolStartFragmentationTestByte = []byte{ProtocolStartFragmentationTest}
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ProtocolNonceByte = []byte{ProtocolNonce}
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ProtocolFetchAllByte = []byte{ProtocolFetchAll}
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ProtocolUpdateByte = []byte{ProtocolUpdate}
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ProtocolPMTUVerifiedByte = []byte{ProtocolPMTUVerified}
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)
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