101 lines
1.8 KiB
Go
101 lines
1.8 KiB
Go
package peer
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import (
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"io"
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"log"
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"sync/atomic"
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)
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type ifReader struct {
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iface io.Reader
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routes [256]*atomic.Pointer[peerRoute]
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relay *atomic.Pointer[peerRoute]
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sender dataPacketSender
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}
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func newIFReader(
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iface io.Reader,
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routes [256]*atomic.Pointer[peerRoute],
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relay *atomic.Pointer[peerRoute],
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sender dataPacketSender,
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) *ifReader {
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return &ifReader{
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iface: iface,
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routes: routes,
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relay: relay,
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sender: sender,
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}
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}
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func (r *ifReader) Run() {
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var (
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packet = make([]byte, bufferSize)
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remoteIP byte
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ok bool
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)
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for {
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packet = r.readNextPacket(packet)
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if remoteIP, ok = r.parsePacket(packet); ok {
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r.sendPacket(packet, remoteIP)
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}
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}
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}
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func (r *ifReader) sendPacket(pkt []byte, remoteIP byte) {
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route := r.routes[remoteIP].Load()
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if !route.Up {
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log.Printf("Route not connected: %d", remoteIP)
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return
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}
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// Direct path => early return.
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if route.Direct {
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r.sender.SendDataPacket(pkt, route)
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return
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}
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if relay := r.relay.Load(); relay != nil && relay.Up {
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r.sender.RelayDataPacket(pkt, route, relay)
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}
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}
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// Get next packet, returning packet, and destination ip.
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func (r *ifReader) readNextPacket(buf []byte) []byte {
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n, err := r.iface.Read(buf[:cap(buf)])
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if err != nil {
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log.Fatalf("Failed to read from interface: %v", err)
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}
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return buf[:n]
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}
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func (r *ifReader) parsePacket(buf []byte) (byte, bool) {
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n := len(buf)
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if n == 0 {
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return 0, false
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}
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version := buf[0] >> 4
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switch version {
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case 4:
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if n < 20 {
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log.Printf("Short IPv4 packet: %d", len(buf))
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return 0, false
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}
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return buf[19], true
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case 6:
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if len(buf) < 40 {
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log.Printf("Short IPv6 packet: %d", len(buf))
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return 0, false
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}
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return buf[39], true
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default:
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log.Printf("Invalid IP packet version: %v", version)
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return 0, false
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}
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}
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