From 3f1edad4e6ba0a7876750aea55507fae14d8badf Mon Sep 17 00:00:00 2001 From: Milan Lenco Date: Wed, 11 Oct 2017 16:40:58 +0200 Subject: ODPM 266: Go-libmemif + 2 examples. Change-Id: Icdb9b9eb2314eff6c96afe7996fcf2728291de4a Signed-off-by: Milan Lenco --- vendor/github.com/google/gopacket/pcap/doc.go | 106 ++++++++++++++++++++++++++ 1 file changed, 106 insertions(+) create mode 100644 vendor/github.com/google/gopacket/pcap/doc.go (limited to 'vendor/github.com/google/gopacket/pcap/doc.go') diff --git a/vendor/github.com/google/gopacket/pcap/doc.go b/vendor/github.com/google/gopacket/pcap/doc.go new file mode 100644 index 0000000..5bf8d86 --- /dev/null +++ b/vendor/github.com/google/gopacket/pcap/doc.go @@ -0,0 +1,106 @@ +// 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. + +/* +Package pcap allows users of gopacket to read packets off the wire or from +pcap files. + +This package is meant to be used with its parent, +http://github.com/google/gopacket, although it can also be used independently +if you just want to get packet data from the wire. + +Reading PCAP Files + +The following code can be used to read in data from a pcap file. + + if handle, err := pcap.OpenOffline("/path/to/my/file"); err != nil { + panic(err) + } else { + packetSource := gopacket.NewPacketSource(handle, handle.LinkType()) + for packet := range packetSource.Packets() { + handlePacket(packet) // Do something with a packet here. + } + } + +Reading Live Packets + +The following code can be used to read in data from a live device, in this case +"eth0". + + if handle, err := pcap.OpenLive("eth0", 1600, true, pcap.BlockForever); err != nil { + panic(err) + } else if err := handle.SetBPFFilter("tcp and port 80"); err != nil { // optional + panic(err) + } else { + packetSource := gopacket.NewPacketSource(handle, handle.LinkType()) + for packet := range packetSource.Packets() { + handlePacket(packet) // Do something with a packet here. + } + } + +Inactive Handles + +Newer PCAP functionality requires the concept of an 'inactive' PCAP handle. +Instead of constantly adding new arguments to pcap_open_live, users now call +pcap_create to create a handle, set it up with a bunch of optional function +calls, then call pcap_activate to activate it. This library mirrors that +mechanism, for those that want to expose/use these new features: + + inactive, err := pcap.NewInactiveHandle(deviceName) + if err != nil { + log.Fatal(err) + } + defer inactive.CleanUp() + + // Call various functions on inactive to set it up the way you'd like: + if err = inactive.SetTimeout(time.Minute); err != nil { + log.Fatal(err) + } else if err = inactive.SetTimestampSource("foo"); err != nil { + log.Fatal(err) + } + + // Finally, create the actual handle by calling Activate: + handle, err := inactive.Activate() // after this, inactive is no longer valid + if err != nil { + log.Fatal(err) + } + defer handle.Close() + + // Now use your handle as you see fit. + +PCAP Timeouts + +pcap.OpenLive and pcap.SetTimeout both take timeouts. +If you don't care about timeouts, just pass in BlockForever, +which should do what you expect with minimal fuss. + +A timeout of 0 is not recommended. Some platforms, like Macs +(http://www.manpages.info/macosx/pcap.3.html) say: + The read timeout is used to arrange that the read not necessarily return + immediately when a packet is seen, but that it wait for some amount of time + to allow more packets to arrive and to read multiple packets from the OS + kernel in one operation. +This means that if you only capture one packet, the kernel might decide to wait +'timeout' for more packets to batch with it before returning. A timeout of +0, then, means 'wait forever for more packets', which is... not good. + +To get around this, we've introduced the following behavior: if a negative +timeout is passed in, we set the positive timeout in the handle, then loop +internally in ReadPacketData/ZeroCopyReadPacketData when we see timeout +errors. + +PCAP File Writing + +This package does not implement PCAP file writing. However, gopacket/pcapgo +does! Look there if you'd like to write PCAP files. + +Note For Windows 10 Users + +If you're trying to use 64-bit winpcap on Windows 10, you might have to do +the crazy hijinks detailed at +http://stackoverflow.com/questions/38047858/compile-gopacket-on-windows-64bit +*/ +package pcap -- cgit 1.2.3-korg