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htlcswitch: randomize non-strict forwarding

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This commit is contained in:
Joost Jager 2020-09-29 11:05:49 +02:00
parent fd962d322a
commit 2236813c95
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GPG Key ID: A61B9D4C393C59C7
1 changed files with 14 additions and 6 deletions
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20
htlcswitch/switch.go
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@ -4,6 +4,7 @@ import (
"bytes"
"errors"
"fmt"
"math/rand"
"sync"
"sync/atomic"
"time"
@ -1010,9 +1011,9 @@ func (s *Switch) handlePacketForward(packet *htlcPacket) error {
// trying all links to utilize our available bandwidth.
linkErrs := make(map[lnwire.ShortChannelID]*LinkError)
// Try to find destination channel link with appropriate
// Find all destination channel links with appropriate
// bandwidth.
var destination ChannelLink
var destinations []ChannelLink
for _, link := range interfaceLinks {
var failure *LinkError
@ -1035,10 +1036,11 @@ func (s *Switch) handlePacketForward(packet *htlcPacket) error {
)
}
// Stop searching if this link can forward the htlc.
// If this link can forward the htlc, add it to the set
// of destinations.
if failure == nil {
destination = link
break
destinations = append(destinations, link)
continue
}
linkErrs[link.ShortChanID()] = failure
@ -1048,7 +1050,7 @@ func (s *Switch) handlePacketForward(packet *htlcPacket) error {
// satisfying the current policy, then we'll send back an
// error, but ensure we send back the error sourced at the
// *target* link.
if destination == nil {
if len(destinations) == 0 {
// At this point, some or all of the links rejected the
// HTLC so we couldn't forward it. So we'll try to look
// up the error that came from the source.
@ -1075,6 +1077,12 @@ func (s *Switch) handlePacketForward(packet *htlcPacket) error {
return s.failAddPacket(packet, linkErr)
}
// Choose a random link out of the set of links that can forward
// this htlc. The reason for randomization is to evenly
// distribute the htlc load without making assumptions about
// what the best channel is.
destination := destinations[rand.Intn(len(destinations))]
// Send the packet to the destination channel link which
// manages the channel.
packet.outgoingChanID = destination.ShortChanID()