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Add per-sniffer instance log prefix

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A prefix associated with a sniffer instance can help debug situations where
more than one NIC (i.e. more than one sniffer) exists.

PiperOrigin-RevId: 342950027
This commit is contained in:
Bruno Dal Bo
2020-11-17 14:46:00 -08:00
committed by gVisor bot
parent 2d89f23402
commit 7492ed6bd6
1 changed files with 44 additions and 14 deletions
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pkg/tcpip/link/sniffer/sniffer.go
+44 -14
View File
@@ -53,16 +53,35 @@ type endpoint struct {
nested.Endpoint
writer io.Writer
maxPCAPLen uint32
logPrefix string
}
var _ stack.GSOEndpoint = (*endpoint)(nil)
var _ stack.LinkEndpoint = (*endpoint)(nil)
var _ stack.NetworkDispatcher = (*endpoint)(nil)
type direction int
const (
directionSend = iota
directionRecv
)
// New creates a new sniffer link-layer endpoint. It wraps around another
// endpoint and logs packets and they traverse the endpoint.
func New(lower stack.LinkEndpoint) stack.LinkEndpoint {
sniffer := &endpoint{}
return NewWithPrefix(lower, "")
}
// NewWithPrefix creates a new sniffer link-layer endpoint. It wraps around
// another endpoint and logs packets prefixed with logPrefix as they traverse
// the endpoint.
//
// logPrefix is prepended to the log line without any separators.
// E.g. logPrefix = "NIC:en0/" will produce log lines like
// "NIC:en0/send udp [...]".
func NewWithPrefix(lower stack.LinkEndpoint, logPrefix string) stack.LinkEndpoint {
sniffer := &endpoint{logPrefix: logPrefix}
sniffer.Endpoint.Init(lower, sniffer)
return sniffer
}
@@ -120,7 +139,7 @@ func NewWithWriter(lower stack.LinkEndpoint, writer io.Writer, snapLen uint32) (
// called by the link-layer endpoint being wrapped when a packet arrives, and
// logs the packet before forwarding to the actual dispatcher.
func (e *endpoint) DeliverNetworkPacket(remote, local tcpip.LinkAddress, protocol tcpip.NetworkProtocolNumber, pkt *stack.PacketBuffer) {
e.dumpPacket("recv", nil, protocol, pkt)
e.dumpPacket(directionRecv, nil, protocol, pkt)
e.Endpoint.DeliverNetworkPacket(remote, local, protocol, pkt)
}
@@ -129,10 +148,10 @@ func (e *endpoint) DeliverOutboundPacket(remote, local tcpip.LinkAddress, protoc
e.Endpoint.DeliverOutboundPacket(remote, local, protocol, pkt)
}
func (e *endpoint) dumpPacket(prefix string, gso *stack.GSO, protocol tcpip.NetworkProtocolNumber, pkt *stack.PacketBuffer) {
func (e *endpoint) dumpPacket(dir direction, gso *stack.GSO, protocol tcpip.NetworkProtocolNumber, pkt *stack.PacketBuffer) {
writer := e.writer
if writer == nil && atomic.LoadUint32(&LogPackets) == 1 {
logPacket(prefix, protocol, pkt, gso)
logPacket(e.logPrefix, dir, protocol, pkt, gso)
}
if writer != nil && atomic.LoadUint32(&LogPacketsToPCAP) == 1 {
totalLength := pkt.Size()
@@ -169,7 +188,7 @@ func (e *endpoint) dumpPacket(prefix string, gso *stack.GSO, protocol tcpip.Netw
// higher-level protocols to write packets; it just logs the packet and
// forwards the request to the lower endpoint.
func (e *endpoint) WritePacket(r *stack.Route, gso *stack.GSO, protocol tcpip.NetworkProtocolNumber, pkt *stack.PacketBuffer) *tcpip.Error {
e.dumpPacket("send", gso, protocol, pkt)
e.dumpPacket(directionSend, gso, protocol, pkt)
return e.Endpoint.WritePacket(r, gso, protocol, pkt)
}
@@ -178,20 +197,20 @@ func (e *endpoint) WritePacket(r *stack.Route, gso *stack.GSO, protocol tcpip.Ne
// forwards the request to the lower endpoint.
func (e *endpoint) WritePackets(r *stack.Route, gso *stack.GSO, pkts stack.PacketBufferList, protocol tcpip.NetworkProtocolNumber) (int, *tcpip.Error) {
for pkt := pkts.Front(); pkt != nil; pkt = pkt.Next() {
e.dumpPacket("send", gso, protocol, pkt)
e.dumpPacket(directionSend, gso, protocol, pkt)
}
return e.Endpoint.WritePackets(r, gso, pkts, protocol)
}
// WriteRawPacket implements stack.LinkEndpoint.WriteRawPacket.
func (e *endpoint) WriteRawPacket(vv buffer.VectorisedView) *tcpip.Error {
e.dumpPacket("send", nil, 0, stack.NewPacketBuffer(stack.PacketBufferOptions{
e.dumpPacket(directionSend, nil, 0, stack.NewPacketBuffer(stack.PacketBufferOptions{
Data: vv,
}))
return e.Endpoint.WriteRawPacket(vv)
}
func logPacket(prefix string, protocol tcpip.NetworkProtocolNumber, pkt *stack.PacketBuffer, gso *stack.GSO) {
func logPacket(prefix string, dir direction, protocol tcpip.NetworkProtocolNumber, pkt *stack.PacketBuffer, gso *stack.GSO) {
// Figure out the network layer info.
var transProto uint8
src := tcpip.Address("unknown")
@@ -201,6 +220,16 @@ func logPacket(prefix string, protocol tcpip.NetworkProtocolNumber, pkt *stack.P
var fragmentOffset uint16
var moreFragments bool
var directionPrefix string
switch dir {
case directionSend:
directionPrefix = "send"
case directionRecv:
directionPrefix = "recv"
default:
panic(fmt.Sprintf("unrecognized direction: %d", dir))
}
// Clone the packet buffer to not modify the original.
//
// We don't clone the original packet buffer so that the new packet buffer
@@ -248,15 +277,16 @@ func logPacket(prefix string, protocol tcpip.NetworkProtocolNumber, pkt *stack.P
arp := header.ARP(pkt.NetworkHeader().View())
log.Infof(
"%s arp %s (%s) -> %s (%s) valid:%t",
"%s%s arp %s (%s) -> %s (%s) valid:%t",
prefix,
directionPrefix,
tcpip.Address(arp.ProtocolAddressSender()), tcpip.LinkAddress(arp.HardwareAddressSender()),
tcpip.Address(arp.ProtocolAddressTarget()), tcpip.LinkAddress(arp.HardwareAddressTarget()),
arp.IsValid(),
)
return
default:
log.Infof("%s unknown network protocol", prefix)
log.Infof("%s%s unknown network protocol", prefix, directionPrefix)
return
}
@@ -300,7 +330,7 @@ func logPacket(prefix string, protocol tcpip.NetworkProtocolNumber, pkt *stack.P
icmpType = "info reply"
}
}
log.Infof("%s %s %s -> %s %s len:%d id:%04x code:%d", prefix, transName, src, dst, icmpType, size, id, icmp.Code())
log.Infof("%s%s %s %s -> %s %s len:%d id:%04x code:%d", prefix, directionPrefix, transName, src, dst, icmpType, size, id, icmp.Code())
return
case header.ICMPv6ProtocolNumber:
@@ -335,7 +365,7 @@ func logPacket(prefix string, protocol tcpip.NetworkProtocolNumber, pkt *stack.P
case header.ICMPv6RedirectMsg:
icmpType = "redirect message"
}
log.Infof("%s %s %s -> %s %s len:%d id:%04x code:%d", prefix, transName, src, dst, icmpType, size, id, icmp.Code())
log.Infof("%s%s %s %s -> %s %s len:%d id:%04x code:%d", prefix, directionPrefix, transName, src, dst, icmpType, size, id, icmp.Code())
return
case header.UDPProtocolNumber:
@@ -391,7 +421,7 @@ func logPacket(prefix string, protocol tcpip.NetworkProtocolNumber, pkt *stack.P
}
default:
log.Infof("%s %s -> %s unknown transport protocol: %d", prefix, src, dst, transProto)
log.Infof("%s%s %s -> %s unknown transport protocol: %d", prefix, directionPrefix, src, dst, transProto)
return
}
@@ -399,5 +429,5 @@ func logPacket(prefix string, protocol tcpip.NetworkProtocolNumber, pkt *stack.P
details += fmt.Sprintf(" gso: %+v", gso)
}
log.Infof("%s %s %s:%d -> %s:%d len:%d id:%04x %s", prefix, transName, src, srcPort, dst, dstPort, size, id, details)
log.Infof("%s%s %s %s:%d -> %s:%d len:%d id:%04x %s", prefix, directionPrefix, transName, src, srcPort, dst, dstPort, size, id, details)
}