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Diffstat (limited to 'vendor/github.com/google/gopacket/layers/doc.go')
-rw-r--r-- | vendor/github.com/google/gopacket/layers/doc.go | 61 |
1 files changed, 61 insertions, 0 deletions
diff --git a/vendor/github.com/google/gopacket/layers/doc.go b/vendor/github.com/google/gopacket/layers/doc.go new file mode 100644 index 0000000..3c882c3 --- /dev/null +++ b/vendor/github.com/google/gopacket/layers/doc.go @@ -0,0 +1,61 @@ +// 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 layers provides decoding layers for many common protocols. + +The layers package contains decode implementations for a number of different +types of packet layers. Users of gopacket will almost always want to also use +layers to actually decode packet data into useful pieces. To see the set of +protocols that gopacket/layers is currently able to decode, +look at the set of LayerTypes defined in the Variables sections. The +layers package also defines endpoints for many of the common packet layers +that have source/destination addresses associated with them, for example IPv4/6 +(IPs) and TCP/UDP (ports). +Finally, layers contains a number of useful enumerations (IPProtocol, +EthernetType, LinkType, PPPType, etc...). Many of these implement the +gopacket.Decoder interface, so they can be passed into gopacket as decoders. + +Most common protocol layers are named using acronyms or other industry-common +names (IPv4, TCP, PPP). Some of the less common ones have their names expanded +(CiscoDiscoveryProtocol). +For certain protocols, sub-parts of the protocol are split out into their own +layers (SCTP, for example). This is done mostly in cases where portions of the +protocol may fulfill the capabilities of interesting layers (SCTPData implements +ApplicationLayer, while base SCTP implements TransportLayer), or possibly +because splitting a protocol into a few layers makes decoding easier. + +This package is meant to be used with its parent, +http://github.com/google/gopacket. + +Port Types + +Instead of using raw uint16 or uint8 values for ports, we use a different port +type for every protocol, for example TCPPort and UDPPort. This allows us to +override string behavior for each port, which we do by setting up port name +maps (TCPPortNames, UDPPortNames, etc...). Well-known ports are annotated with +their protocol names, and their String function displays these names: + + p := TCPPort(80) + fmt.Printf("Number: %d String: %v", p, p) + // Prints: "Number: 80 String: 80(http)" + +Modifying Decode Behavior + +layers links together decoding through its enumerations. For example, after +decoding layer type Ethernet, it uses Ethernet.EthernetType as its next decoder. +All enumerations that act as decoders, like EthernetType, can be modified by +users depending on their preferences. For example, if you have a spiffy new +IPv4 decoder that works way better than the one built into layers, you can do +this: + + var mySpiffyIPv4Decoder gopacket.Decoder = ... + layers.EthernetTypeMetadata[EthernetTypeIPv4].DecodeWith = mySpiffyIPv4Decoder + +This will make all future ethernet packets use your new decoder to decode IPv4 +packets, instead of the built-in decoder used by gopacket. +*/ +package layers |