From 7492ed6bd63cd4f3b7c81a45b13b053b840f6d50 Mon Sep 17 00:00:00 2001 From: Bruno Dal Bo Date: Tue, 17 Nov 2020 14:43:45 -0800 Subject: Add per-sniffer instance log prefix 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 --- pkg/tcpip/link/sniffer/sniffer.go | 58 +++++++++++++++++++++++++++++---------- 1 file changed, 44 insertions(+), 14 deletions(-) (limited to 'pkg/tcpip/link/sniffer') diff --git a/pkg/tcpip/link/sniffer/sniffer.go b/pkg/tcpip/link/sniffer/sniffer.go index b3e8c4b92..178e658df 100644 --- a/pkg/tcpip/link/sniffer/sniffer.go +++ b/pkg/tcpip/link/sniffer/sniffer.go @@ -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) } -- cgit v1.2.3