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Diffstat (limited to 'vendor/github.com/google/gopacket/layers/ntp.go')
| -rw-r--r-- | vendor/github.com/google/gopacket/layers/ntp.go | 416 |
1 files changed, 0 insertions, 416 deletions
diff --git a/vendor/github.com/google/gopacket/layers/ntp.go b/vendor/github.com/google/gopacket/layers/ntp.go deleted file mode 100644 index 33c15b3..0000000 --- a/vendor/github.com/google/gopacket/layers/ntp.go +++ /dev/null @@ -1,416 +0,0 @@ -// Copyright 2016 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 - -import ( - "encoding/binary" - "errors" - - "github.com/google/gopacket" -) - -//****************************************************************************** -// -// Network Time Protocol (NTP) Decoding Layer -// ------------------------------------------ -// This file provides a GoPacket decoding layer for NTP. -// -//****************************************************************************** -// -// About The Network Time Protocol (NTP) -// ------------------------------------- -// NTP is a protocol that enables computers on the internet to set their -// clocks to the correct time (or to a time that is acceptably close to the -// correct time). NTP runs on top of UDP. -// -// There have been a series of versions of the NTP protocol. The latest -// version is V4 and is specified in RFC 5905: -// http://www.ietf.org/rfc/rfc5905.txt -// -//****************************************************************************** -// -// References -// ---------- -// -// Wikipedia's NTP entry: -// https://en.wikipedia.org/wiki/Network_Time_Protocol -// This is the best place to get an overview of NTP. -// -// Network Time Protocol Home Website: -// http://www.ntp.org/ -// This appears to be the official website of NTP. -// -// List of current NTP Protocol RFCs: -// http://www.ntp.org/rfc.html -// -// RFC 958: "Network Time Protocol (NTP)" (1985) -// https://tools.ietf.org/html/rfc958 -// This is the original NTP specification. -// -// RFC 1305: "Network Time Protocol (Version 3) Specification, Implementation and Analysis" (1992) -// https://tools.ietf.org/html/rfc1305 -// The protocol was updated in 1992 yielding NTP V3. -// -// RFC 5905: "Network Time Protocol Version 4: Protocol and Algorithms Specification" (2010) -// https://www.ietf.org/rfc/rfc5905.txt -// The protocol was updated in 2010 yielding NTP V4. -// V4 is backwards compatible with all previous versions of NTP. -// -// RFC 5906: "Network Time Protocol Version 4: Autokey Specification" -// https://tools.ietf.org/html/rfc5906 -// This document addresses the security of the NTP protocol -// and is probably not relevant to this package. -// -// RFC 5907: "Definitions of Managed Objects for Network Time Protocol Version 4 (NTPv4)" -// https://tools.ietf.org/html/rfc5907 -// This document addresses the management of NTP servers and -// is probably not relevant to this package. -// -// RFC 5908: "Network Time Protocol (NTP) Server Option for DHCPv6" -// https://tools.ietf.org/html/rfc5908 -// This document addresses the use of NTP in DHCPv6 and is -// probably not relevant to this package. -// -// "Let's make a NTP Client in C" -// https://lettier.github.io/posts/2016-04-26-lets-make-a-ntp-client-in-c.html -// This web page contains useful information about the details of NTP, -// including an NTP record struture in C, and C code. -// -// "NTP Packet Header (NTP Reference Implementation) (Computer Network Time Synchronization)" -// http://what-when-how.com/computer-network-time-synchronization/ -// ntp-packet-header-ntp-reference-implementation-computer-network-time-synchronization/ -// This web page contains useful information on the details of NTP. -// -// "Technical information - NTP Data Packet" -// https://www.meinbergglobal.com/english/info/ntp-packet.htm -// This page has a helpful diagram of an NTP V4 packet. -// -//****************************************************************************** -// -// Obsolete References -// ------------------- -// -// RFC 1119: "RFC-1119 "Network Time Protocol (Version 2) Specification and Implementation" (1989) -// https://tools.ietf.org/html/rfc1119 -// Version 2 was drafted in 1989. -// It is unclear whether V2 was ever implememented or whether the -// ideas ended up in V3 (which was implemented in 1992). -// -// RFC 1361: "Simple Network Time Protocol (SNTP)" -// https://tools.ietf.org/html/rfc1361 -// This document is obsoleted by RFC 1769 and is included only for completeness. -// -// RFC 1769: "Simple Network Time Protocol (SNTP)" -// https://tools.ietf.org/html/rfc1769 -// This document is obsoleted by RFC 2030 and RFC 4330 and is included only for completeness. -// -// RFC 2030: "Simple Network Time Protocol (SNTP) Version 4 for IPv4, IPv6 and OSI" -// https://tools.ietf.org/html/rfc2030 -// This document is obsoleted by RFC 4330 and is included only for completeness. -// -// RFC 4330: "Simple Network Time Protocol (SNTP) Version 4 for IPv4, IPv6 and OSI" -// https://tools.ietf.org/html/rfc4330 -// This document is obsoleted by RFC 5905 and is included only for completeness. -// -//****************************************************************************** -// -// Endian And Bit Numbering Issues -// ------------------------------- -// -// Endian and bit numbering issues can be confusing. Here is some -// clarification: -// -// ENDIAN: Values are sent big endian. -// https://en.wikipedia.org/wiki/Endianness -// -// BIT NUMBERING: Bits are numbered 0 upwards from the most significant -// bit to the least significant bit. This means that if there is a 32-bit -// value, the most significant bit is called bit 0 and the least -// significant bit is called bit 31. -// -// See RFC 791 Appendix B for more discussion. -// -//****************************************************************************** -// -// NTP V3 and V4 Packet Format -// --------------------------- -// NTP packets are UDP packets whose payload contains an NTP record. -// -// The NTP RFC defines the format of the NTP record. -// -// There have been four versions of the protocol: -// -// V1 in 1985 -// V2 in 1989 -// V3 in 1992 -// V4 in 2010 -// -// It is clear that V1 and V2 are obsolete, and there is no need to -// cater for these formats. -// -// V3 and V4 essentially use the same format, with V4 adding some optional -// fields on the end. So this package supports the V3 and V4 formats. -// -// The current version of NTP (NTP V4)'s RFC (V4 - RFC 5905) contains -// the following diagram for the NTP record format: - -// 0 1 2 3 -// 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 -// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ -// |LI | VN |Mode | Stratum | Poll | Precision | -// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ -// | Root Delay | -// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ -// | Root Dispersion | -// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ -// | Reference ID | -// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ -// | | -// + Reference Timestamp (64) + -// | | -// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ -// | | -// + Origin Timestamp (64) + -// | | -// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ -// | | -// + Receive Timestamp (64) + -// | | -// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ -// | | -// + Transmit Timestamp (64) + -// | | -// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ -// | | -// . . -// . Extension Field 1 (variable) . -// . . -// | | -// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ -// | | -// . . -// . Extension Field 2 (variable) . -// . . -// | | -// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ -// | Key Identifier | -// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ -// | | -// | dgst (128) | -// | | -// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ -// From http://www.ietf.org/rfc/rfc5905.txt -// -// The fields "Extension Field 1 (variable)" and later are optional fields, -// and so we can set a minimum NTP record size of 48 bytes. -// -const ntpMinimumRecordSizeInBytes int = 48 - -//****************************************************************************** - -// NTP Type -// -------- -// Type NTP implements the DecodingLayer interface. Each NTP object -// represents in a structured form the NTP record present as the UDP -// payload in an NTP UDP packet. -// - -type NTPLeapIndicator uint8 -type NTPVersion uint8 -type NTPMode uint8 -type NTPStratum uint8 -type NTPLog2Seconds int8 -type NTPFixed16Seconds uint32 -type NTPReferenceID uint32 -type NTPTimestamp uint64 - -type NTP struct { - BaseLayer // Stores the packet bytes and payload bytes. - - LeapIndicator NTPLeapIndicator // [0,3]. Indicates whether leap second(s) is to be added. - Version NTPVersion // [0,7]. Version of the NTP protocol. - Mode NTPMode // [0,7]. Mode. - Stratum NTPStratum // [0,255]. Stratum of time server in the server tree. - Poll NTPLog2Seconds // [-128,127]. The maximum interval between successive messages, in log2 seconds. - Precision NTPLog2Seconds // [-128,127]. The precision of the system clock, in log2 seconds. - RootDelay NTPFixed16Seconds // [0,2^32-1]. Total round trip delay to the reference clock in seconds times 2^16. - RootDispersion NTPFixed16Seconds // [0,2^32-1]. Total dispersion to the reference clock, in seconds times 2^16. - ReferenceID NTPReferenceID // ID code of reference clock [0,2^32-1]. - ReferenceTimestamp NTPTimestamp // Most recent timestamp from the reference clock. - OriginTimestamp NTPTimestamp // Local time when request was sent from local host. - ReceiveTimestamp NTPTimestamp // Local time (on server) that request arrived at server host. - TransmitTimestamp NTPTimestamp // Local time (on server) that request departed server host. - - // FIX: This package should analyse the extension fields and represent the extension fields too. - ExtensionBytes []byte // Just put extensions in a byte slice. -} - -//****************************************************************************** - -// LayerType returns the layer type of the NTP object, which is LayerTypeNTP. -func (d *NTP) LayerType() gopacket.LayerType { - return LayerTypeNTP -} - -//****************************************************************************** - -// decodeNTP analyses a byte slice and attempts to decode it as an NTP -// record of a UDP packet. -// -// If it succeeds, it loads p with information about the packet and returns nil. -// If it fails, it returns an error (non nil). -// -// This function is employed in layertypes.go to register the NTP layer. -func decodeNTP(data []byte, p gopacket.PacketBuilder) error { - - // Attempt to decode the byte slice. - d := &NTP{} - err := d.DecodeFromBytes(data, p) - if err != nil { - return err - } - - // If the decoding worked, add the layer to the packet and set it - // as the application layer too, if there isn't already one. - p.AddLayer(d) - p.SetApplicationLayer(d) - - return nil -} - -//****************************************************************************** - -// DecodeFromBytes analyses a byte slice and attempts to decode it as an NTP -// record of a UDP packet. -// -// Upon succeeds, it loads the NTP object with information about the packet -// and returns nil. -// Upon failure, it returns an error (non nil). -func (d *NTP) DecodeFromBytes(data []byte, df gopacket.DecodeFeedback) error { - - // If the data block is too short to be a NTP record, then return an error. - if len(data) < ntpMinimumRecordSizeInBytes { - df.SetTruncated() - return errors.New("NTP packet too short") - } - - // RFC 5905 does not appear to define a maximum NTP record length. - // The protocol allows "extension fields" to be included in the record, - // and states about these fields:" - // - // "While the minimum field length containing required fields is - // four words (16 octets), a maximum field length remains to be - // established." - // - // For this reason, the packet length is not checked here for being too long. - - // NTP type embeds type BaseLayer which contains two fields: - // Contents is supposed to contain the bytes of the data at this level. - // Payload is supposed to contain the payload of this level. - // Here we set the baselayer to be the bytes of the NTP record. - d.BaseLayer = BaseLayer{Contents: data[:len(data)]} - - // Extract the fields from the block of bytes. - // To make sense of this, refer to the packet diagram - // above and the section on endian conventions. - - // The first few fields are all packed into the first 32 bits. Unpack them. - f := data[0] - d.LeapIndicator = NTPLeapIndicator((f & 0xC0) >> 6) - d.Version = NTPVersion((f & 0x38) >> 3) - d.Mode = NTPMode(f & 0x07) - d.Stratum = NTPStratum(data[1]) - d.Poll = NTPLog2Seconds(data[2]) - d.Precision = NTPLog2Seconds(data[3]) - - // The remaining fields can just be copied in big endian order. - d.RootDelay = NTPFixed16Seconds(binary.BigEndian.Uint32(data[4:8])) - d.RootDispersion = NTPFixed16Seconds(binary.BigEndian.Uint32(data[8:12])) - d.ReferenceID = NTPReferenceID(binary.BigEndian.Uint32(data[12:16])) - d.ReferenceTimestamp = NTPTimestamp(binary.BigEndian.Uint64(data[16:24])) - d.OriginTimestamp = NTPTimestamp(binary.BigEndian.Uint64(data[24:32])) - d.ReceiveTimestamp = NTPTimestamp(binary.BigEndian.Uint64(data[32:40])) - d.TransmitTimestamp = NTPTimestamp(binary.BigEndian.Uint64(data[40:48])) - - // This layer does not attempt to analyse the extension bytes. - // But if there are any, we'd like the user to know. So we just - // place them all in an ExtensionBytes field. - d.ExtensionBytes = data[48:] - - // Return no error. - return nil -} - -// SerializeTo writes the serialized form of this layer into the -// SerializationBuffer, implementing gopacket.SerializableLayer. -// See the docs for gopacket.SerializableLayer for more info. -func (d *NTP) SerializeTo(b gopacket.SerializeBuffer, opts gopacket.SerializeOptions) error { - data, err := b.PrependBytes(ntpMinimumRecordSizeInBytes) - if err != nil { - return err - } - - // Pack the first few fields into the first 32 bits. - h := uint8(0) - h |= (uint8(d.LeapIndicator) << 6) & 0xC0 - h |= (uint8(d.Version) << 3) & 0x38 - h |= (uint8(d.Mode)) & 0x07 - data[0] = byte(h) - data[1] = byte(d.Stratum) - data[2] = byte(d.Poll) - data[3] = byte(d.Precision) - - // The remaining fields can just be copied in big endian order. - binary.BigEndian.PutUint32(data[4:8], uint32(d.RootDelay)) - binary.BigEndian.PutUint32(data[8:12], uint32(d.RootDispersion)) - binary.BigEndian.PutUint32(data[12:16], uint32(d.ReferenceID)) - binary.BigEndian.PutUint64(data[16:24], uint64(d.ReferenceTimestamp)) - binary.BigEndian.PutUint64(data[24:32], uint64(d.OriginTimestamp)) - binary.BigEndian.PutUint64(data[32:40], uint64(d.ReceiveTimestamp)) - binary.BigEndian.PutUint64(data[40:48], uint64(d.TransmitTimestamp)) - - ex, err := b.AppendBytes(len(d.ExtensionBytes)) - if err != nil { - return err - } - copy(ex, d.ExtensionBytes) - - return nil -} - -//****************************************************************************** - -// CanDecode returns a set of layers that NTP objects can decode. -// As NTP objects can only decide the NTP layer, we can return just that layer. -// Apparently a single layer type implements LayerClass. -func (d *NTP) CanDecode() gopacket.LayerClass { - return LayerTypeNTP -} - -//****************************************************************************** - -// NextLayerType specifies the next layer that GoPacket should attempt to -// analyse after this (NTP) layer. As NTP packets do not contain any payload -// bytes, there are no further layers to analyse. -func (d *NTP) NextLayerType() gopacket.LayerType { - return gopacket.LayerTypeZero -} - -//****************************************************************************** - -// NTP packets do not carry any data payload, so the empty byte slice is retured. -// In Go, a nil slice is functionally identical to an empty slice, so we -// return nil to avoid a heap allocation. -func (d *NTP) Payload() []byte { - return nil -} - -//****************************************************************************** -//* End Of NTP File * -//****************************************************************************** |