79 lines
1.3 KiB
Go
79 lines
1.3 KiB
Go
package peer
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import (
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"io"
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"log"
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)
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type IFReader struct {
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iface io.Reader
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connWriter interface {
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WriteData(ip byte, pkt []byte)
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}
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}
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func NewIFReader(
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iface io.Reader,
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connWriter interface {
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WriteData(ip byte, pkt []byte)
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},
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) *IFReader {
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return &IFReader{iface, connWriter}
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}
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func (r *IFReader) Run() {
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packet := newBuf()
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for {
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r.handleNextPacket(packet)
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}
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}
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func (r *IFReader) handleNextPacket(packet []byte) {
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packet = r.readNextPacket(packet)
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if remoteIP, ok := r.parsePacket(packet); ok {
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r.connWriter.WriteData(remoteIP, packet)
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}
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}
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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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r.logf("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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r.logf("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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r.logf("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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func (*IFReader) logf(s string, args ...any) {
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log.Printf("[IFReader] "+s, args...)
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}
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