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// Copyright 2012 Google, Inc. All rights reserved.
// Copyright 2009-2011 Andreas Krennmair. All rights reserved.
//
// Use of this source code is governed by a BSD-style license
// that can be found in the LICENSE file in the root of the source
// tree.
// +build pfring
package pfring
/*
// lpcap is needed for bpf
#cgo LDFLAGS: -lpfring -lpcap
#include <stdlib.h>
#include <pfring.h>
#include <stdint.h>
#include <linux/pf_ring.h>
struct metadata {
u_int64_t timestamp_ns;
u_int32_t caplen;
u_int32_t len;
int32_t if_index;
};
// In pfring 7.2 pfring_pkthdr struct was changed to packed
// Since this is incompatible with go, copy the values we need to a custom
// struct (struct metadata above).
// Another way to do this, would be to store the struct offsets in defines
// and use encoding/binary in go-land. But this has the downside, that there is
// no native endianess in encoding/binary and storing ByteOrder in a variable
// leads to an expensive itab lookup + call (instead of very fast inlined and
// optimized movs). Using unsafe magic could lead to problems with unaligned
// access.
// Additionally, this does the same uintptr-dance as pcap.
int pfring_readpacketdatato_wrapper(
pfring* ring,
uintptr_t buffer,
uintptr_t meta) {
struct metadata* ci = (struct metadata* )meta;
struct pfring_pkthdr hdr;
int ret = pfring_recv(ring, (u_char**)buffer, 0, &hdr, 1);
ci->timestamp_ns = hdr.extended_hdr.timestamp_ns;
ci->caplen = hdr.caplen;
ci->len = hdr.len;
ci->if_index = hdr.extended_hdr.if_index;
return ret;
}
*/
import "C"
// NOTE: If you install PF_RING with non-standard options, you may also need
// to use LDFLAGS -lnuma and/or -lrt. Both have been reported necessary if
// PF_RING is configured with --disable-bpf.
import (
"fmt"
"net"
"os"
"reflect"
"strconv"
"sync"
"time"
"unsafe"
"github.com/google/gopacket"
)
const errorBufferSize = 256
// Ring provides a handle to a pf_ring.
type Ring struct {
cptr *C.pfring
useExtendedPacketHeader bool
interfaceIndex int
mu sync.Mutex
meta C.struct_metadata
bufPtr *C.u_char
}
// Flag provides a set of boolean flags to use when creating a new ring.
type Flag uint32
// Set of flags that can be passed (OR'd together) to NewRing.
const (
FlagReentrant Flag = C.PF_RING_REENTRANT
FlagLongHeader Flag = C.PF_RING_LONG_HEADER
FlagPromisc Flag = C.PF_RING_PROMISC
FlagDNASymmetricRSS Flag = C.PF_RING_DNA_SYMMETRIC_RSS
FlagTimestamp Flag = C.PF_RING_TIMESTAMP
FlagHWTimestamp Flag = C.PF_RING_HW_TIMESTAMP
)
// NewRing creates a new PFRing. Note that when the ring is initially created,
// it is disabled. The caller must call Enable to start receiving packets.
// The caller should call Close on the given ring when finished with it.
func NewRing(device string, snaplen uint32, flags Flag) (ring *Ring, _ error) {
dev := C.CString(device)
defer C.free(unsafe.Pointer(dev))
cptr, err := C.pfring_open(dev, C.u_int32_t(snaplen), C.u_int32_t(flags))
if cptr == nil || err != nil {
return nil, fmt.Errorf("pfring NewRing error: %v", err)
}
ring = &Ring{cptr: cptr}
if flags&FlagLongHeader == FlagLongHeader {
ring.useExtendedPacketHeader = true
} else {
ifc, err := net.InterfaceByName(device)
if err == nil {
ring.interfaceIndex = ifc.Index
}
}
ring.SetApplicationName(os.Args[0])
return
}
// Close closes the given Ring. After this call, the Ring should no longer be
// used.
func (r *Ring) Close() {
C.pfring_close(r.cptr)
}
// NextResult is the return code from a call to Next.
type NextResult int32
// Set of results that could be returned from a call to get another packet.
const (
NextNoPacketNonblocking NextResult = 0
NextError NextResult = -1
NextOk NextResult = 1
NextNotEnabled NextResult = -7
)
// NextResult implements the error interface.
func (n NextResult) Error() string {
switch n {
case NextNoPacketNonblocking:
return "No packet available, nonblocking socket"
case NextError:
return "Generic error"
case NextOk:
return "Success (not an error)"
case NextNotEnabled:
return "Ring not enabled"
}
return strconv.Itoa(int(n))
}
// shared code (Read-functions), that fetches a packet + metadata from pf_ring
func (r *Ring) getNextBufPtrLocked(ci *gopacket.CaptureInfo) error {
result := NextResult(C.pfring_readpacketdatato_wrapper(r.cptr, C.uintptr_t(uintptr(unsafe.Pointer(&r.bufPtr))), C.uintptr_t(uintptr(unsafe.Pointer(&r.meta)))))
if result != NextOk {
return result
}
ci.Timestamp = time.Unix(0, int64(r.meta.timestamp_ns))
ci.CaptureLength = int(r.meta.caplen)
ci.Length = int(r.meta.len)
if r.useExtendedPacketHeader {
ci.InterfaceIndex = int(r.meta.if_index)
} else {
ci.InterfaceIndex = r.interfaceIndex
}
return nil
}
// ReadPacketDataTo reads packet data into a user-supplied buffer.
//
// Deprecated: This function is provided for legacy code only. Use ReadPacketData or ZeroCopyReadPacketData
// This function does an additional copy, and is therefore slower than ZeroCopyReadPacketData.
// The old implementation did the same inside the pf_ring library.
func (r *Ring) ReadPacketDataTo(data []byte) (ci gopacket.CaptureInfo, err error) {
r.mu.Lock()
err = r.getNextBufPtrLocked(&ci)
if err == nil {
var buf []byte
slice := (*reflect.SliceHeader)(unsafe.Pointer(&buf))
slice.Data = uintptr(unsafe.Pointer(r.bufPtr))
slice.Len = ci.CaptureLength
slice.Cap = ci.CaptureLength
copy(data, buf)
}
r.mu.Unlock()
return
}
// ReadPacketData returns the next packet read from pf_ring, along with an error
// code associated with that packet. If the packet is read successfully, the
// returned error is nil.
func (r *Ring) ReadPacketData() (data []byte, ci gopacket.CaptureInfo, err error) {
r.mu.Lock()
err = r.getNextBufPtrLocked(&ci)
if err == nil {
data = C.GoBytes(unsafe.Pointer(r.bufPtr), C.int(ci.CaptureLength))
}
r.mu.Unlock()
return
}
// ZeroCopyReadPacketData returns the next packet read from pf_ring, along with an error
// code associated with that packet.
// The slice returned by ZeroCopyReadPacketData points to bytes inside a pf_ring
// ring. Each call to ZeroCopyReadPacketData might invalidate any data previously
// returned by ZeroCopyReadPacketData. Care must be taken not to keep pointers
// to old bytes when using ZeroCopyReadPacketData... if you need to keep data past
// the next time you call ZeroCopyReadPacketData, use ReadPacketData, which copies
// the bytes into a new buffer for you.
// data1, _, _ := handle.ZeroCopyReadPacketData()
// // do everything you want with data1 here, copying bytes out of it if you'd like to keep them around.
// data2, _, _ := handle.ZeroCopyReadPacketData() // invalidates bytes in data1
func (r *Ring) ZeroCopyReadPacketData() (data []byte, ci gopacket.CaptureInfo, err error) {
r.mu.Lock()
err = r.getNextBufPtrLocked(&ci)
if err == nil {
slice := (*reflect.SliceHeader)(unsafe.Pointer(&data))
slice.Data = uintptr(unsafe.Pointer(r.bufPtr))
slice.Len = ci.CaptureLength
slice.Cap = ci.CaptureLength
}
r.mu.Unlock()
return
}
// ClusterType is a type of clustering used when balancing across multiple
// rings.
type ClusterType C.cluster_type
const (
// ClusterPerFlow clusters by <src ip, src port, dst ip, dst port, proto,
// vlan>
ClusterPerFlow ClusterType = C.cluster_per_flow
// ClusterRoundRobin round-robins packets between applications, ignoring
// packet information.
ClusterRoundRobin ClusterType = C.cluster_round_robin
// ClusterPerFlow2Tuple clusters by <src ip, dst ip>
ClusterPerFlow2Tuple ClusterType = C.cluster_per_flow_2_tuple
// ClusterPerFlow4Tuple clusters by <src ip, src port, dst ip, dst port>
ClusterPerFlow4Tuple ClusterType = C.cluster_per_flow_4_tuple
// ClusterPerFlow5Tuple clusters by <src ip, src port, dst ip, dst port,
// proto>
ClusterPerFlow5Tuple ClusterType = C.cluster_per_flow_5_tuple
// ClusterPerFlowTCP5Tuple acts like ClusterPerFlow5Tuple for TCP packets and
// like ClusterPerFlow2Tuple for all other packets.
ClusterPerFlowTCP5Tuple ClusterType = C.cluster_per_flow_tcp_5_tuple
)
// SetCluster sets which cluster the ring should be part of, and the cluster
// type to use.
func (r *Ring) SetCluster(cluster int, typ ClusterType) error {
if rv := C.pfring_set_cluster(r.cptr, C.u_int(cluster), C.cluster_type(typ)); rv != 0 {
return fmt.Errorf("Unable to set cluster, got error code %d", rv)
}
return nil
}
// RemoveFromCluster removes the ring from the cluster it was put in with
// SetCluster.
func (r *Ring) RemoveFromCluster() error {
if rv := C.pfring_remove_from_cluster(r.cptr); rv != 0 {
return fmt.Errorf("Unable to remove from cluster, got error code %d", rv)
}
return nil
}
// SetSamplingRate sets the sampling rate to 1/<rate>.
func (r *Ring) SetSamplingRate(rate int) error {
if rv := C.pfring_set_sampling_rate(r.cptr, C.u_int32_t(rate)); rv != 0 {
return fmt.Errorf("Unable to set sampling rate, got error code %d", rv)
}
return nil
}
// SetPollWatermark sets the pfring's poll watermark packet count
func (r *Ring) SetPollWatermark(count uint16) error {
if rv := C.pfring_set_poll_watermark(r.cptr, C.u_int16_t(count)); rv != 0 {
return fmt.Errorf("Unable to set poll watermark, got error code %d", rv)
}
return nil
}
// SetPriority sets the pfring poll threads CPU usage limit
func (r *Ring) SetPriority(cpu uint16) {
C.pfring_config(C.u_short(cpu))
}
// SetPollDuration sets the pfring's poll duration before it yields/returns
func (r *Ring) SetPollDuration(durationMillis uint) error {
if rv := C.pfring_set_poll_duration(r.cptr, C.u_int(durationMillis)); rv != 0 {
return fmt.Errorf("Unable to set poll duration, got error code %d", rv)
}
return nil
}
// SetBPFFilter sets the BPF filter for the ring.
func (r *Ring) SetBPFFilter(bpfFilter string) error {
filter := C.CString(bpfFilter)
defer C.free(unsafe.Pointer(filter))
if rv := C.pfring_set_bpf_filter(r.cptr, filter); rv != 0 {
return fmt.Errorf("Unable to set BPF filter, got error code %d", rv)
}
return nil
}
// RemoveBPFFilter removes the BPF filter from the ring.
func (r *Ring) RemoveBPFFilter() error {
if rv := C.pfring_remove_bpf_filter(r.cptr); rv != 0 {
return fmt.Errorf("Unable to remove BPF filter, got error code %d", rv)
}
return nil
}
// WritePacketData uses the ring to send raw packet data to the interface.
func (r *Ring) WritePacketData(data []byte) error {
buf := (*C.char)(unsafe.Pointer(&data[0]))
if rv := C.pfring_send(r.cptr, buf, C.u_int(len(data)), 1); rv < 0 {
return fmt.Errorf("Unable to send packet data, got error code %d", rv)
}
return nil
}
// Enable enables the given ring. This function MUST be called on each new
// ring after it has been set up, or that ring will NOT receive packets.
func (r *Ring) Enable() error {
if rv := C.pfring_enable_ring(r.cptr); rv != 0 {
return fmt.Errorf("Unable to enable ring, got error code %d", rv)
}
return nil
}
// Disable disables the given ring. After this call, it will no longer receive
// packets.
func (r *Ring) Disable() error {
if rv := C.pfring_disable_ring(r.cptr); rv != 0 {
return fmt.Errorf("Unable to disable ring, got error code %d", rv)
}
return nil
}
// Stats provides simple statistics on a ring.
type Stats struct {
Received, Dropped uint64
}
// Stats returns statistsics for the ring.
func (r *Ring) Stats() (s Stats, err error) {
var stats C.pfring_stat
if rv := C.pfring_stats(r.cptr, &stats); rv != 0 {
err = fmt.Errorf("Unable to get ring stats, got error code %d", rv)
return
}
s.Received = uint64(stats.recv)
s.Dropped = uint64(stats.drop)
return
}
// Direction is a simple enum to set which packets (TX, RX, or both) a ring
// captures.
type Direction C.packet_direction
const (
// TransmitOnly will only capture packets transmitted by the ring's
// interface(s).
TransmitOnly Direction = C.tx_only_direction
// ReceiveOnly will only capture packets received by the ring's
// interface(s).
ReceiveOnly Direction = C.rx_only_direction
// ReceiveAndTransmit will capture both received and transmitted packets on
// the ring's interface(s).
ReceiveAndTransmit Direction = C.rx_and_tx_direction
)
// SetDirection sets which packets should be captured by the ring.
func (r *Ring) SetDirection(d Direction) error {
if rv := C.pfring_set_direction(r.cptr, C.packet_direction(d)); rv != 0 {
return fmt.Errorf("Unable to set ring direction, got error code %d", rv)
}
return nil
}
// SocketMode is an enum for setting whether a ring should read, write, or both.
type SocketMode C.socket_mode
const (
// WriteOnly sets up the ring to only send packets (Inject), not read them.
WriteOnly SocketMode = C.send_only_mode
// ReadOnly sets up the ring to only receive packets (ReadPacketData), not
// send them.
ReadOnly SocketMode = C.recv_only_mode
// WriteAndRead sets up the ring to both send and receive packets.
WriteAndRead SocketMode = C.send_and_recv_mode
)
// SetSocketMode sets the mode of the ring socket to send, receive, or both.
func (r *Ring) SetSocketMode(s SocketMode) error {
if rv := C.pfring_set_socket_mode(r.cptr, C.socket_mode(s)); rv != 0 {
return fmt.Errorf("Unable to set socket mode, got error code %d", rv)
}
return nil
}
// SetApplicationName sets a string name to the ring. This name is available in
// /proc stats for pf_ring. By default, NewRing automatically calls this with
// argv[0].
func (r *Ring) SetApplicationName(name string) error {
buf := C.CString(name)
defer C.free(unsafe.Pointer(buf))
if rv := C.pfring_set_application_name(r.cptr, buf); rv != 0 {
return fmt.Errorf("Unable to set ring application name, got error code %d", rv)
}
return nil
}
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