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tstest/natlab: print trace data when NATLAB_TRACE is set.

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Signed-off-by: David Anderson <danderson@tailscale.com>
This commit is contained in:
David Anderson 2020-07-03 02:09:54 +00:00
parent 1d4f9852a7
commit 622c0d0cb3
1 changed files with 39 additions and 6 deletions
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45
tstest/natlab/natlab.go
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@ -13,8 +13,11 @@
import (
"context"
"crypto/sha256"
"encoding/base64"
"fmt"
"net"
"os"
"sort"
"strconv"
"sync"
@ -23,6 +26,25 @@
"inet.af/netaddr"
)
var traceOn = os.Getenv("NATLAB_TRACE")
func trace(p []byte, msg string, args ...interface{}) {
if traceOn == "" {
return
}
id := packetShort(p)
as := []interface{}{id}
as = append(as, args...)
fmt.Fprintf(os.Stderr, "[%s] "+msg+"\n", as...)
}
// packetShort returns a short identifier for a packet payload,
// suitable for pritning trace information.
func packetShort(p []byte) string {
s := sha256.Sum256(p)
return base64.RawStdEncoding.EncodeToString(s[:])[:4]
}
func mustPrefix(s string) netaddr.IPPrefix {
ipp, err := netaddr.ParseIPPrefix(s)
if err != nil {
@ -113,12 +135,13 @@ func (n *Network) write(p []byte, dst, src netaddr.IPPort) (num int, err error)
defer n.mu.Unlock()
m, ok := n.machine[dst.IP]
if !ok {
// TODO: queue? hang forever? return success? don't fail fast probably.
return 0, fmt.Errorf("unknown dest IP %v", dst.IP)
trace(p, "net=%s dropped, no route to %v", n.Name, dst.IP)
return len(p), nil
}
// Pretend it went across the network. Make a copy so nobody
// can later mess with caller's memory.
trace(p, "net=%s src=%v dst=%v -> mach=%s", n.Name, src, dst, m.name)
pcopy := append([]byte(nil), p...)
go m.deliverIncomingPacket(pcopy, dst, src)
return len(p), nil
@ -201,17 +224,21 @@ func (m *Machine) deliverIncomingPacket(p []byte, dst, src netaddr.IPPort) {
netaddr.IPPort{IP: v6unspec, Port: dst.Port},
netaddr.IPPort{IP: v4unspec, Port: dst.Port},
}
for _, dst := range possibleDsts {
c, ok := conns[dst]
for _, dest := range possibleDsts {
c, ok := conns[dest]
if !ok {
continue
}
select {
case c.in <- incomingPacket{src: src, p: p}:
trace(p, "mach=%s src=%v dst=%v queued to conn", m.name, src, dst)
default:
trace(p, "mach=%s src=%v dst=%v dropped, queue overflow", m.name, src, dst)
// Queue overflow. Just drop it.
}
return
}
trace(p, "mach=%s src=%v dst=%v dropped, no listening conn", m.name, src, dst)
}
func unspecOf(ip netaddr.IP) netaddr.IP {
@ -283,6 +310,7 @@ func (m *Machine) Attach(interfaceName string, n *Network) *Interface {
func (m *Machine) writePacket(p []byte, dst, src netaddr.IPPort) (n int, err error) {
iface, err := m.interfaceForIP(dst.IP)
if err != nil {
trace(p, "%v", err)
return 0, err
}
origSrcIP := src.IP
@ -298,13 +326,18 @@ func (m *Machine) writePacket(p []byte, dst, src netaddr.IPPort) (n int, err err
}
default:
if !iface.Contains(src.IP) {
return 0, fmt.Errorf("can't send to %v with src %v on interface %v", dst.IP, src.IP, iface)
err := fmt.Errorf("can't send to %v with src %v on interface %v", dst.IP, src.IP, iface)
trace(p, "%v", err)
return 0, err
}
}
if src.IP.IsZero() {
return 0, fmt.Errorf("no matching address for address family for %v", origSrcIP)
err := fmt.Errorf("no matching address for address family for %v", origSrcIP)
trace(p, "%v", err)
return 0, err
}
trace(p, "mach=%s src=%s dst=%s -> net=%s", m.name, src, dst, iface.net.Name)
return iface.net.write(p, dst, src)
}