--- /dev/null
+// Copyright 2012 Google, Inc. 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 linux
+
+package afpacket
+
+import (
+ "reflect"
+ "time"
+ "unsafe"
+)
+
+// #include <linux/if_packet.h>
+import "C"
+
+// Our model of handling all TPacket versions is a little hacky, to say the
+// least. We use the header interface to handle interactions with the
+// tpacket1/tpacket2 packet header AND the tpacket3 block header. The big
+// difference is that tpacket3's block header implements the next() call to get
+// the next packet within the block, while v1/v2 just always return false.
+
+type header interface {
+ // getStatus returns the TPacket status of the current header.
+ getStatus() int
+ // clearStatus clears the status of the current header, releasing its
+ // underlying data back to the kernel for future use with new packets.
+ // Using the header after calling clearStatus is an error. clearStatus
+ // should only be called after next() returns false.
+ clearStatus()
+ // getTime returns the timestamp for the current packet pointed to by
+ // the header.
+ getTime() time.Time
+ // getData returns the packet data pointed to by the current header.
+ getData() []byte
+ // getLength returns the total length of the packet.
+ getLength() int
+ // getIfaceIndex returns the index of the network interface
+ // where the packet was seen. The index can later be translated to a name.
+ getIfaceIndex() int
+ // next moves this header to point to the next packet it contains,
+ // returning true on success (in which case getTime and getData will
+ // return values for the new packet) or false if there are no more
+ // packets (in which case clearStatus should be called).
+ next() bool
+}
+
+func tpAlign(x int) int {
+ return int((uint(x) + tpacketAlignment - 1) &^ (tpacketAlignment - 1))
+}
+
+type v1header C.struct_tpacket_hdr
+type v2header C.struct_tpacket2_hdr
+
+func makeSlice(start uintptr, length int) (data []byte) {
+ slice := (*reflect.SliceHeader)(unsafe.Pointer(&data))
+ slice.Data = start
+ slice.Len = length
+ slice.Cap = length
+ return
+}
+
+func (h *v1header) getStatus() int {
+ return int(h.tp_status)
+}
+func (h *v1header) clearStatus() {
+ h.tp_status = 0
+}
+func (h *v1header) getTime() time.Time {
+ return time.Unix(int64(h.tp_sec), int64(h.tp_usec)*1000)
+}
+func (h *v1header) getData() []byte {
+ return makeSlice(uintptr(unsafe.Pointer(h))+uintptr(h.tp_mac), int(h.tp_snaplen))
+}
+func (h *v1header) getLength() int {
+ return int(h.tp_len)
+}
+func (h *v1header) getIfaceIndex() int {
+ ll := (*C.struct_sockaddr_ll)(unsafe.Pointer(uintptr(unsafe.Pointer(h)) + uintptr(tpAlign(int(C.sizeof_struct_tpacket_hdr)))))
+ return int(ll.sll_ifindex)
+}
+func (h *v1header) next() bool {
+ return false
+}
+
+func (h *v2header) getStatus() int {
+ return int(h.tp_status)
+}
+func (h *v2header) clearStatus() {
+ h.tp_status = 0
+}
+func (h *v2header) getTime() time.Time {
+ return time.Unix(int64(h.tp_sec), int64(h.tp_nsec))
+}
+func (h *v2header) getData() []byte {
+ return makeSlice(uintptr(unsafe.Pointer(h))+uintptr(h.tp_mac), int(h.tp_snaplen))
+}
+func (h *v2header) getLength() int {
+ return int(h.tp_len)
+}
+func (h *v2header) getIfaceIndex() int {
+ ll := (*C.struct_sockaddr_ll)(unsafe.Pointer(uintptr(unsafe.Pointer(h)) + uintptr(tpAlign(int(C.sizeof_struct_tpacket2_hdr)))))
+ return int(ll.sll_ifindex)
+}
+func (h *v2header) next() bool {
+ return false
+}
+
+type v3wrapper struct {
+ block *C.struct_tpacket_block_desc
+ blockhdr *C.struct_tpacket_hdr_v1
+ packet *C.struct_tpacket3_hdr
+ used C.__u32
+}
+
+func initV3Wrapper(block unsafe.Pointer) (w v3wrapper) {
+ w.block = (*C.struct_tpacket_block_desc)(block)
+ w.blockhdr = (*C.struct_tpacket_hdr_v1)(unsafe.Pointer(&w.block.hdr[0]))
+ w.packet = (*C.struct_tpacket3_hdr)(unsafe.Pointer(uintptr(block) + uintptr(w.blockhdr.offset_to_first_pkt)))
+ return
+}
+func (w *v3wrapper) getStatus() int {
+ return int(w.blockhdr.block_status)
+}
+func (w *v3wrapper) clearStatus() {
+ w.blockhdr.block_status = 0
+}
+func (w *v3wrapper) getTime() time.Time {
+ return time.Unix(int64(w.packet.tp_sec), int64(w.packet.tp_nsec))
+}
+func (w *v3wrapper) getData() []byte {
+ return makeSlice(uintptr(unsafe.Pointer(w.packet))+uintptr(w.packet.tp_mac), int(w.packet.tp_snaplen))
+}
+func (w *v3wrapper) getLength() int {
+ return int(w.packet.tp_len)
+}
+func (w *v3wrapper) getIfaceIndex() int {
+ ll := (*C.struct_sockaddr_ll)(unsafe.Pointer(uintptr(unsafe.Pointer(w.packet)) + uintptr(tpAlign(int(C.sizeof_struct_tpacket3_hdr)))))
+ return int(ll.sll_ifindex)
+}
+func (w *v3wrapper) next() bool {
+ w.used++
+ if w.used >= w.blockhdr.num_pkts {
+ return false
+ }
+
+ next := uintptr(unsafe.Pointer(w.packet))
+ if w.packet.tp_next_offset != 0 {
+ next += uintptr(w.packet.tp_next_offset)
+ } else {
+ next += uintptr(tpacketAlign(int(w.packet.tp_snaplen) + int(w.packet.tp_mac)))
+ }
+ w.packet = (*C.struct_tpacket3_hdr)(unsafe.Pointer(next))
+ return true
+}
Code Review / govpp.git / blobdiff