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prototype scion-socket
this is required by bindings to languages whose networking libraries main abstraction are berkley sockets, not connections as in Go
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8 files changed

+590
-46
lines changed

8 files changed

+590
-46
lines changed

‎.vscode/launch.json

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{
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// Use IntelliSense to learn about possible attributes.
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// Hover to view descriptions of existing attributes.
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// For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
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"version": "0.2.0",
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"configurations": [
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{
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"name": "Launch Package",
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"type": "go",
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"request": "launch",
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"mode": "auto",
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"program": "${workspaceFolder}/_examples/helloworld_socket/helloworld_socket.go",
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"args": ["-remote" ,"19-ffaa:1:1067,127.0.0.1:2222"]
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}
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]
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}

‎_examples/helloworld_socket/helloworld_socket

22.1 MB
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‎_examples/helloworld_socket/helloworld_socket.go

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// Copyright 2018 ETH Zurich
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package main
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import (
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"context"
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"errors"
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"flag"
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"fmt"
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"net/netip"
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"os"
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"time"
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"github.com/netsec-ethz/scion-apps/pkg/pan"
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)
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func main() {
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var err error
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// get local and remote addresses from program arguments:
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var listen pan.IPPortValue
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flag.Var(&listen, "listen", "[Server] local IP:port to listen on")
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remoteAddr := flag.String("remote", "", "[Client] Remote (i.e. the server's) SCION Address (e.g. 17-ffaa:1:1,[127.0.0.1]:12345)")
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count := flag.Uint("count", 1, "[Client] Number of messages to send")
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flag.Parse()
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if (listen.Get().Port() > 0) == (len(*remoteAddr) > 0) {
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check(fmt.Errorf("either specify -listen for server or -remote for client"))
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}
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if listen.Get().Port() > 0 {
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err = runServer(listen.Get())
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check(err)
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} else {
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err = runClient(*remoteAddr, int(*count))
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check(err)
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}
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}
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func runServer(listen netip.AddrPort) error {
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sock, err := pan.NewScionSocket(context.Background(), listen)
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if err != nil {
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return err
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}
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defer sock.Close()
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fmt.Println(sock.LocalAddr())
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buffer := make([]byte, 16*1024)
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for {
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n, from, err := sock.ReadFrom(buffer)
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if err != nil {
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return err
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}
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data := buffer[:n]
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fmt.Printf("Received %s: %s\n", from, data)
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msg := fmt.Sprintf("take it back! %s", time.Now().Format("15:04:05.0"))
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n, err = sock.WriteTo([]byte(msg), from)
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if err != nil {
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return err
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}
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fmt.Printf("Wrote %d bytes.\n", n)
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}
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}
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func runClient(address string, count int) error {
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addr, err := pan.ResolveUDPAddr(context.TODO(), address)
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if err != nil {
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return err
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}
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sock, err := pan.NewScionSocket(context.Background(), netip.AddrPort{})
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if err != nil {
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return err
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}
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defer sock.Close()
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for i := 0; i < count; i++ {
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nBytes, err := sock.WriteTo([]byte(fmt.Sprintf("hello world %s", time.Now().Format("15:04:05.0"))), addr)
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if err != nil {
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return err
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}
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fmt.Printf("Wrote %d bytes.\n", nBytes)
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buffer := make([]byte, 16*1024)
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/* if err = conn.SetReadDeadline(time.Now().Add(1 * time.Second)); err != nil {
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return err
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} */
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n, _, err := sock.ReadFrom(buffer)
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if errors.Is(err, os.ErrDeadlineExceeded) {
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continue
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} else if err != nil {
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return err
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}
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data := buffer[:n]
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fmt.Printf("Received reply: %s\n", data)
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}
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return nil
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}
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// Check just ensures the error is nil, or complains and quits
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func check(e error) {
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if e != nil {
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fmt.Fprintln(os.Stderr, "Fatal error:", e)
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os.Exit(1)
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}
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}

‎pkg/pan/combi_selector.go

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package pan
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import (
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"context"
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"errors"
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)
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// socket roles (selector internals)
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const dialer = 0
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const listener = 1
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/*
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!
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\brief this class provides the service of path selection for a remote address to scion-sockets
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Every scion-socket has one.
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It should not be cluttered with Refresh()/Update()/PathDown or any other technical
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methods that are required by the pathStatedDB or pathPool to update the selectors state.
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*/
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type CombiSelector interface {
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Close() error
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// PathDown(PathFingerprint, PathInterface) // pathDownNotifyee
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// called when the scion-socket is bound to an address
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LocalAddrChanged(newlocal UDPAddr)
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Path(remote UDPAddr) (*Path, error)
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//Refresh([]*Path) Selector
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// Refresh(paths []*Path, remote UDPAddr)
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Record(remote UDPAddr, path *Path)
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//Update( )#
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// setter the respective defaults
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SetReplySelector(ReplySelector)
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SetSelector(sel func() Selector)
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SetPolicy(pol func() Policy)
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// setter for AS specific path policies
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// SetSelectorFor(remote IA, sel Selector)
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// SetPolicyFor(remote IA, pol Policy)
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// SetPolicedSelectorFor(remote IA, sel Selector, pol Policy)
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// initialize(local UDPAddr, remote UDPAddr, paths []*Path)
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// maybe make this pubilc and let the ScionCocketCall it,
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// in its ctor (or once the local addr is known i.e after Bind() was called )
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}
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type DefaultCombiSelector struct {
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local UDPAddr
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roles map[UDPAddr]int // is this host the dialer or listener for the connection to this remote host
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// decided from which method is called first for a remote address X
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// Record(X)->listener or Path(X)->dialer
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// maybe make map of pair (, ,) ?!
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// policies map[UDPAddr]Policy
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policy_factory func() Policy
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selector_factory func() Selector
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// TODO: this state should be confined in size somehow
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// i.e. drop selectors with LRU scheme
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// Note that this is not an attack vector, as this state can only be increased
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// by deliberate decisions of this host to dial a remote for which it does not yet has a selector
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selectors map[IA]Selector
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subscribers map[IA]*pathRefreshSubscriber
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replyselector ReplySelector
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}
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func (s *DefaultCombiSelector) needPathTo(remote UDPAddr) bool {
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return s.local.IA != remote.IA
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}
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func (s *DefaultCombiSelector) Close() error {
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for _, v := range s.subscribers {
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if e := v.Close(); e != nil {
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return e
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}
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}
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for _, v := range s.selectors {
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if e := v.Close(); e != nil {
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return e
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}
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}
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if e := s.replyselector.Close(); e != nil {
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return e
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}
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return nil
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}
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func NewDefaultCombiSelector(local UDPAddr) (CombiSelector, error) {
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selector := &DefaultCombiSelector{
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local: local,
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roles: make(map[UDPAddr]int),
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// policies: make(map[UDPAddr]Policy),
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policy_factory: func() Policy {
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var s Policy = nil
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return s
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},
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selector_factory: func() Selector { return NewDefaultSelector() },
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selectors: make(map[IA]Selector),
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subscribers: make(map[IA]*pathRefreshSubscriber),
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replyselector: NewDefaultReplySelector(),
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}
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selector.replyselector.Initialize(local)
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return selector, nil
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}
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func (s *DefaultCombiSelector) SetReplySelector(rep ReplySelector) {
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s.replyselector = rep
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}
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func (s *DefaultCombiSelector) LocalAddrChanged(newlocal UDPAddr) {
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s.local = newlocal
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}
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func (s *DefaultCombiSelector) Path(remote UDPAddr) (*Path, error) {
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if r, ok := s.roles[remote]; ok {
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// the role is already decided
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if r == dialer {
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if s.needPathTo(remote) {
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sel := s.selectors[remote.IA]
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sel.NewRemote(remote)
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return sel.Path(remote)
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} else {
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return nil, errors.New("if src and dst are in same AS and no scion path is required, the connection shouldnt request one")
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}
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} else {
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return s.replyselector.Path(remote)
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}
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} else {
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// no role yet -> no path to remote has been requested yet Path()
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// so we are acting as a server
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s.roles[remote] = dialer
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// set up a refresherSubscriber etc ..
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if s.needPathTo(remote) {
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var selector Selector
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var policy Policy
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if s.policy_factory != nil {
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policy = s.policy_factory()
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}
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if s.selector_factory != nil {
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selector = s.selector_factory()
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} else {
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selector = NewDefaultSelector()
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}
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var ctx context.Context = context.Background()
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// Todo: set timeout for path request
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subscriber, err := openPathRefreshSubscriber(ctx, s.local, remote, policy, selector)
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if err != nil {
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return nil, err
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}
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s.selectors[remote.IA] = selector
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s.subscribers[remote.IA] = subscriber
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return selector.Path(remote)
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} else {
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return nil, errors.New("if src and dst are in same AS and no scion path is required, the connection shouldnt request one")
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}
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}
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}
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func (s *DefaultCombiSelector) SetPolicy(pol func() Policy) {
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s.policy_factory = pol
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}
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func (s *DefaultCombiSelector) SetSelector(sel func() Selector) {
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s.selector_factory = sel
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}
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func (s *DefaultCombiSelector) Record(remote UDPAddr, path *Path) {
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if r, ok := s.roles[remote]; ok {
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// the role is already decided
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if r == listener {
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s.replyselector.Record(remote, path)
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}
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} else {
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// no role yet -> no path to remote has been requested yet Path()
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// so we are acting as a server
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s.roles[remote] = listener
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}
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}

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