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Localhost working - is this the best way to do it?

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This commit is contained in:
Owen
2025-12-05 16:33:43 -05:00
parent 02949be245
commit 72a9e111dc
2 changed files with 86 additions and 18 deletions
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68
netstack2/proxy.go
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@@ -145,6 +145,14 @@ type connKey struct {
proto uint8
}
// destKey identifies a destination for handler lookups (without source port since it may change)
type destKey struct {
srcIP string
dstIP string
dstPort uint16
proto uint8
}
// natState tracks NAT translation state for reverse translation
type natState struct {
originalDst netip.Addr // Original destination before DNAT
@@ -160,6 +168,7 @@ type ProxyHandler struct {
udpHandler *UDPHandler
subnetLookup *SubnetLookup
natTable map[connKey]*natState
destRewriteTable map[destKey]netip.Addr // Maps original dest to rewritten dest for handler lookups
natMu sync.RWMutex
enabled bool
}
@@ -178,10 +187,11 @@ func NewProxyHandler(options ProxyHandlerOptions) (*ProxyHandler, error) {
}
handler := &ProxyHandler{
enabled: true,
subnetLookup: NewSubnetLookup(),
natTable: make(map[connKey]*natState),
proxyEp: channel.New(1024, uint32(options.MTU), ""),
enabled: true,
subnetLookup: NewSubnetLookup(),
natTable: make(map[connKey]*natState),
destRewriteTable: make(map[destKey]netip.Addr),
proxyEp: channel.New(1024, uint32(options.MTU), ""),
proxyStack: stack.New(stack.Options{
NetworkProtocols: []stack.NetworkProtocolFactory{
ipv4.NewProtocol,
@@ -198,7 +208,7 @@ func NewProxyHandler(options ProxyHandlerOptions) (*ProxyHandler, error) {
// Initialize TCP handler if enabled
if options.EnableTCP {
handler.tcpHandler = NewTCPHandler(handler.proxyStack)
handler.tcpHandler = NewTCPHandler(handler.proxyStack, handler)
if err := handler.tcpHandler.InstallTCPHandler(); err != nil {
return nil, fmt.Errorf("failed to install TCP handler: %v", err)
}
@@ -206,7 +216,7 @@ func NewProxyHandler(options ProxyHandlerOptions) (*ProxyHandler, error) {
// Initialize UDP handler if enabled
if options.EnableUDP {
handler.udpHandler = NewUDPHandler(handler.proxyStack)
handler.udpHandler = NewUDPHandler(handler.proxyStack, handler)
if err := handler.udpHandler.InstallUDPHandler(); err != nil {
return nil, fmt.Errorf("failed to install UDP handler: %v", err)
}
@@ -251,6 +261,27 @@ func (p *ProxyHandler) RemoveSubnetRule(sourcePrefix, destPrefix netip.Prefix) {
p.subnetLookup.RemoveSubnet(sourcePrefix, destPrefix)
}
// LookupDestinationRewrite looks up the rewritten destination for a connection
// This is used by TCP/UDP handlers to find the actual target address
func (p *ProxyHandler) LookupDestinationRewrite(srcIP, dstIP string, dstPort uint16, proto uint8) (netip.Addr, bool) {
if p == nil || !p.enabled {
return netip.Addr{}, false
}
key := destKey{
srcIP: srcIP,
dstIP: dstIP,
dstPort: dstPort,
proto: proto,
}
p.natMu.RLock()
defer p.natMu.RUnlock()
addr, ok := p.destRewriteTable[key]
return addr, ok
}
// resolveRewriteAddress resolves a rewrite address which can be either:
// - An IP address with CIDR notation (e.g., "192.168.1.1/32") - returns the IP directly
// - A plain IP address (e.g., "192.168.1.1") - returns the IP directly
@@ -407,6 +438,14 @@ func (p *ProxyHandler) HandleIncomingPacket(packet []byte) bool {
proto: uint8(protocol),
}
// Key for handler lookups (doesn't include srcPort for flexibility)
dKey := destKey{
srcIP: srcAddr.String(),
dstIP: dstAddr.String(),
dstPort: dstPort,
proto: uint8(protocol),
}
// Check if we already have a NAT entry for this connection
p.natMu.RLock()
existingEntry, exists := p.natTable[key]
@@ -437,14 +476,23 @@ func (p *ProxyHandler) HandleIncomingPacket(packet []byte) bool {
originalDst: dstAddr,
rewrittenTo: newDst,
}
// Store destination rewrite for handler lookups
p.destRewriteTable[dKey] = newDst
p.natMu.Unlock()
logger.Debug("New NAT entry for connection: %s -> %s", dstAddr, newDst)
}
// Rewrite the packet
packet = p.rewritePacketDestination(packet, newDst)
if packet == nil {
return false
// Check if target is loopback - if so, don't rewrite packet destination
// as gVisor will drop martian packets. Instead, the handlers will use
// destRewriteTable to find the actual target address.
if !newDst.IsLoopback() {
// Rewrite the packet only for non-loopback destinations
packet = p.rewritePacketDestination(packet, newDst)
if packet == nil {
return false
}
} else {
logger.Debug("Target is loopback, not rewriting packet - handlers will use rewrite table")
}
}