cloudflared-mirror/packet/flow.go

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package packet
import (
"errors"
"fmt"
"net/netip"
"sync"
)
var (
ErrFlowNotFound = errors.New("flow not found")
)
// FlowID represents a key type that can be used by FlowTracker
type FlowID interface {
// Type returns the name of the type that implements the FlowID
Type() string
fmt.Stringer
}
type Flow struct {
Src netip.Addr
Dst netip.Addr
Responder FlowResponder
}
func isSameFlow(f1, f2 *Flow) bool {
if f1 == nil || f2 == nil {
return false
}
return *f1 == *f2
}
// FlowResponder sends response packets to the flow
type FlowResponder interface {
// SendPacket returns a packet to the flow. It must not modify the packet,
// and after return it must not read the packet
SendPacket(pk RawPacket) error
}
// FlowTracker tracks flow from the perspective of eyeball to origin
type FlowTracker struct {
lock sync.RWMutex
flows map[FlowID]*Flow
}
func NewFlowTracker() *FlowTracker {
return &FlowTracker{
flows: make(map[FlowID]*Flow),
}
}
func (sft *FlowTracker) Get(id FlowID) (*Flow, bool) {
sft.lock.RLock()
defer sft.lock.RUnlock()
flow, ok := sft.flows[id]
return flow, ok
}
// Registers a flow. If shouldReplace = true, replace the current flow
func (sft *FlowTracker) Register(id FlowID, flow *Flow, shouldReplace bool) (replaced bool) {
sft.lock.Lock()
defer sft.lock.Unlock()
currentFlow, ok := sft.flows[id]
if !ok {
sft.flows[id] = flow
return false
}
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if shouldReplace && !isSameFlow(currentFlow, flow) {
sft.flows[id] = flow
return true
}
return false
}
// Unregisters a flow. If force = true, delete it even if it maps to a different flow
func (sft *FlowTracker) Unregister(id FlowID, flow *Flow, force bool) (forceDeleted bool) {
sft.lock.Lock()
defer sft.lock.Unlock()
currentFlow, ok := sft.flows[id]
if !ok {
return false
}
if isSameFlow(currentFlow, flow) {
delete(sft.flows, id)
return false
}
if force {
delete(sft.flows, id)
return true
}
return false
}