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ZeroTierOne/node/Packet.hpp

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/*
* ZeroTier One - Global Peer to Peer Ethernet
* Copyright (C) 2012-2013 ZeroTier Networks LLC
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* --
*
* ZeroTier may be used and distributed under the terms of the GPLv3, which
* are available at: http://www.gnu.org/licenses/gpl-3.0.html
*
* If you would like to embed ZeroTier into a commercial application or
* redistribute it in a modified binary form, please contact ZeroTier Networks
* LLC. Start here: http://www.zerotier.com/
*/
#ifndef _ZT_N_PACKET_HPP
#define _ZT_N_PACKET_HPP
#include <stdint.h>
#include <string.h>
#include <stdio.h>
#include <string>
#include <iostream>
#include "Address.hpp"
#include "Poly1305.hpp"
#include "Salsa20.hpp"
#include "Utils.hpp"
#include "Constants.hpp"
#include "Buffer.hpp"
#include "../ext/lz4/lz4.h"
/**
* Protocol version -- incremented only for MAJOR changes
*
* 1 - 0.2.0 ... 0.2.5
* 2 - 0.3.0 ... 0.4.5
* * Added signature and originating peer to multicast frame
* * Double size of multicast frame bloom filter
* 3 - 0.5.0 ...
* * Yet another multicast redesign
* * New crypto completely changes key agreement cipher
*/
#define ZT_PROTO_VERSION 3
/**
* Maximum hop count allowed by packet structure (3 bits, 0-7)
*
* This is not necessarily the maximum hop counter after which
* relaying is no longer performed.
*/
#define ZT_PROTO_MAX_HOPS 7
/**
* Header flag indicating that a packet is encrypted with Salsa20
*
* If this is not set, then the packet's payload is in the clear and the
* MAC is over this (since there is no ciphertext). Otherwise the MAC is
* of the ciphertext after encryption.
*/
#define ZT_PROTO_FLAG_ENCRYPTED 0x80
/**
* Header flag indicating that a packet is fragmented
*
* If this flag is set, the receiver knows to expect more than one fragment.
* See Packet::Fragment for details.
*/
#define ZT_PROTO_FLAG_FRAGMENTED 0x40
/**
* Verb flag indicating payload is compressed with LZ4
*/
#define ZT_PROTO_VERB_FLAG_COMPRESSED 0x80
// Indices of fields in normal packet header -- do not change as this
// might require both code rework and will break compatibility.
#define ZT_PACKET_IDX_IV 0
#define ZT_PACKET_IDX_DEST 8
#define ZT_PACKET_IDX_SOURCE 13
#define ZT_PACKET_IDX_FLAGS 18
#define ZT_PACKET_IDX_MAC 19
#define ZT_PACKET_IDX_VERB 27
#define ZT_PACKET_IDX_PAYLOAD 28
/**
* ZeroTier packet buffer size
*
* This can be changed. This provides enough room for MTU-size packet
* payloads plus some overhead. The subtraction of sizeof(unsigned int)
* makes it an even multiple of 1024 (see Buffer), which might reduce
* memory use a little.
*/
#define ZT_PROTO_MAX_PACKET_LENGTH (3072 - sizeof(unsigned int))
/**
* Minimum viable packet length (also length of header)
*/
#define ZT_PROTO_MIN_PACKET_LENGTH ZT_PACKET_IDX_PAYLOAD
// Indexes of fields in fragment header -- also can't be changed without
// breaking compatibility.
#define ZT_PACKET_FRAGMENT_IDX_PACKET_ID 0
#define ZT_PACKET_FRAGMENT_IDX_DEST 8
#define ZT_PACKET_FRAGMENT_IDX_FRAGMENT_INDICATOR 13
#define ZT_PACKET_FRAGMENT_IDX_FRAGMENT_NO 14
#define ZT_PACKET_FRAGMENT_IDX_HOPS 15
#define ZT_PACKET_FRAGMENT_IDX_PAYLOAD 16
/**
* Value found at ZT_PACKET_FRAGMENT_IDX_FRAGMENT_INDICATOR in fragments
*/
#define ZT_PACKET_FRAGMENT_INDICATOR ZT_ADDRESS_RESERVED_PREFIX
/**
* Minimum viable fragment length
*/
#define ZT_PROTO_MIN_FRAGMENT_LENGTH ZT_PACKET_FRAGMENT_IDX_PAYLOAD
// Size of bloom filter used in multicast propagation graph exploration
#define ZT_PROTO_VERB_MULTICAST_FRAME_BLOOM_FILTER_SIZE_BITS 512
#define ZT_PROTO_VERB_MULTICAST_FRAME_BLOOM_FILTER_SIZE_BYTES 64
// Field incides for parsing verbs -------------------------------------------
#define ZT_PROTO_VERB_HELLO_IDX_PROTOCOL_VERSION (ZT_PACKET_IDX_PAYLOAD)
#define ZT_PROTO_VERB_HELLO_IDX_MAJOR_VERSION (ZT_PROTO_VERB_HELLO_IDX_PROTOCOL_VERSION + 1)
#define ZT_PROTO_VERB_HELLO_IDX_MINOR_VERSION (ZT_PROTO_VERB_HELLO_IDX_MAJOR_VERSION + 1)
#define ZT_PROTO_VERB_HELLO_IDX_REVISION (ZT_PROTO_VERB_HELLO_IDX_MINOR_VERSION + 1)
#define ZT_PROTO_VERB_HELLO_IDX_TIMESTAMP (ZT_PROTO_VERB_HELLO_IDX_REVISION + 2)
#define ZT_PROTO_VERB_HELLO_IDX_IDENTITY (ZT_PROTO_VERB_HELLO_IDX_TIMESTAMP + 8)
#define ZT_PROTO_VERB_ERROR_IDX_IN_RE_VERB (ZT_PACKET_IDX_PAYLOAD)
#define ZT_PROTO_VERB_ERROR_IDX_IN_RE_PACKET_ID (ZT_PROTO_VERB_ERROR_IDX_IN_RE_VERB + 1)
#define ZT_PROTO_VERB_ERROR_IDX_ERROR_CODE (ZT_PROTO_VERB_ERROR_IDX_IN_RE_PACKET_ID + 8)
#define ZT_PROTO_VERB_ERROR_IDX_PAYLOAD (ZT_PROTO_VERB_ERROR_IDX_ERROR_CODE + 1)
#define ZT_PROTO_VERB_OK_IDX_IN_RE_VERB (ZT_PACKET_IDX_PAYLOAD)
#define ZT_PROTO_VERB_OK_IDX_IN_RE_PACKET_ID (ZT_PROTO_VERB_OK_IDX_IN_RE_VERB + 1)
#define ZT_PROTO_VERB_OK_IDX_PAYLOAD (ZT_PROTO_VERB_OK_IDX_IN_RE_PACKET_ID + 8)
#define ZT_PROTO_VERB_WHOIS_IDX_ZTADDRESS (ZT_PACKET_IDX_PAYLOAD)
#define ZT_PROTO_VERB_RENDEZVOUS_IDX_ZTADDRESS (ZT_PACKET_IDX_PAYLOAD)
#define ZT_PROTO_VERB_RENDEZVOUS_IDX_PORT (ZT_PROTO_VERB_RENDEZVOUS_IDX_ZTADDRESS + 5)
#define ZT_PROTO_VERB_RENDEZVOUS_IDX_ADDRLEN (ZT_PROTO_VERB_RENDEZVOUS_IDX_PORT + 2)
#define ZT_PROTO_VERB_RENDEZVOUS_IDX_ADDRESS (ZT_PROTO_VERB_RENDEZVOUS_IDX_ADDRLEN + 1)
#define ZT_PROTO_VERB_FRAME_IDX_NETWORK_ID (ZT_PACKET_IDX_PAYLOAD)
#define ZT_PROTO_VERB_FRAME_IDX_ETHERTYPE (ZT_PROTO_VERB_FRAME_IDX_NETWORK_ID + 8)
#define ZT_PROTO_VERB_FRAME_IDX_PAYLOAD (ZT_PROTO_VERB_FRAME_IDX_ETHERTYPE + 2)
#define ZT_PROTO_VERB_MULTICAST_GOT_IDX_NETWORK_ID (ZT_PACKET_IDX_PAYLOAD)
#define ZT_PROTO_VERB_MULTICAST_GOT_IDX_MULTICAST_GUID (ZT_PROTO_VERB_MULTICAST_GOT_IDX_NETWORK_ID + 8)
#define ZT_PROTO_VERB_MULTICAST_FRAME_IDX_FORWARD_COUNT (ZT_PACKET_IDX_PAYLOAD)
#define ZT_PROTO_VERB_MULTICAST_FRAME_IDX_QUEUE (ZT_PROTO_VERB_MULTICAST_FRAME_IDX_FORWARD_COUNT + 4)
#define ZT_PROTO_VERB_MULTICAST_FRAME_LEN_QUEUE 320
#define ZT_PROTO_VERB_MULTICAST_FRAME_IDX_MAGNET (ZT_PROTO_VERB_MULTICAST_FRAME_IDX_QUEUE + ZT_PROTO_VERB_MULTICAST_FRAME_LEN_QUEUE)
#define ZT_PROTO_VERB_MULTICAST_FRAME_IDX_SUBMITTER (ZT_PROTO_VERB_MULTICAST_FRAME_IDX_MAGNET + 5)
#define ZT_PROTO_VERB_MULTICAST_FRAME_IDX_SUBMITTER_UNIQUE_ID (ZT_PROTO_VERB_MULTICAST_FRAME_IDX_SUBMITTER + 5)
#define ZT_PROTO_VERB_MULTICAST_FRAME_IDX_NETWORK_ID (ZT_PROTO_VERB_MULTICAST_FRAME_IDX_SUBMITTER_UNIQUE_ID + 3)
#define ZT_PROTO_VERB_MULTICAST_FRAME_IDX_SOURCE_MAC (ZT_PROTO_VERB_MULTICAST_FRAME_IDX_NETWORK_ID + 8)
#define ZT_PROTO_VERB_MULTICAST_FRAME_IDX_DESTINATION_MAC (ZT_PROTO_VERB_MULTICAST_FRAME_IDX_SOURCE_MAC + 6)
#define ZT_PROTO_VERB_MULTICAST_FRAME_IDX_DESTINATION_ADI (ZT_PROTO_VERB_MULTICAST_FRAME_IDX_DESTINATION_MAC + 6)
#define ZT_PROTO_VERB_MULTICAST_FRAME_IDX_ETHERTYPE (ZT_PROTO_VERB_MULTICAST_FRAME_IDX_DESTINATION_ADI + 4)
#define ZT_PROTO_VERB_MULTICAST_FRAME_IDX_PAYLOAD_LENGTH (ZT_PROTO_VERB_MULTICAST_FRAME_IDX_ETHERTYPE + 2)
#define ZT_PROTO_VERB_MULTICAST_FRAME_IDX_PAYLOAD (ZT_PROTO_VERB_MULTICAST_FRAME_IDX_PAYLOAD_LENGTH + 2)
#define ZT_PROTO_VERB_NETWORK_CONFIG_REQUEST_IDX_NETWORK_ID (ZT_PACKET_IDX_PAYLOAD)
#define ZT_PROTO_VERB_NETWORK_CONFIG_REQUEST_IDX_DICT_LEN (ZT_PROTO_VERB_NETWORK_CONFIG_REQUEST_IDX_NETWORK_ID + 8)
#define ZT_PROTO_VERB_NETWORK_CONFIG_REQUEST_IDX_DICT (ZT_PROTO_VERB_NETWORK_CONFIG_REQUEST_IDX_DICT_LEN + 2)
#define ZT_PROTO_VERB_NETWORK_CONFIG_REFRESH_IDX_NETWORK_ID (ZT_PACKET_IDX_PAYLOAD)
#define ZT_PROTO_VERB_HELLO__OK__IDX_TIMESTAMP (ZT_PROTO_VERB_OK_IDX_PAYLOAD)
#define ZT_PROTO_VERB_HELLO__OK__IDX_PROTOCOL_VERSION (ZT_PROTO_VERB_HELLO__OK__IDX_TIMESTAMP + 8)
#define ZT_PROTO_VERB_HELLO__OK__IDX_MAJOR_VERSION (ZT_PROTO_VERB_HELLO__OK__IDX_PROTOCOL_VERSION + 1)
#define ZT_PROTO_VERB_HELLO__OK__IDX_MINOR_VERSION (ZT_PROTO_VERB_HELLO__OK__IDX_MAJOR_VERSION + 1)
#define ZT_PROTO_VERB_HELLO__OK__IDX_REVISION (ZT_PROTO_VERB_HELLO__OK__IDX_MINOR_VERSION + 1)
#define ZT_PROTO_VERB_WHOIS__OK__IDX_IDENTITY (ZT_PROTO_VERB_OK_IDX_PAYLOAD)
#define ZT_PROTO_VERB_WHOIS__ERROR__IDX_ZTADDRESS (ZT_PROTO_VERB_ERROR_IDX_PAYLOAD)
#define ZT_PROTO_VERB_NETWORK_CONFIG_REQUEST__OK__IDX_NETWORK_ID (ZT_PROTO_VERB_OK_IDX_PAYLOAD)
#define ZT_PROTO_VERB_NETWORK_CONFIG_REQUEST__OK__IDX_DICT_LEN (ZT_PROTO_VERB_NETWORK_CONFIG_REQUEST__OK__IDX_NETWORK_ID + 8)
#define ZT_PROTO_VERB_NETWORK_CONFIG_REQUEST__OK__IDX_DICT (ZT_PROTO_VERB_NETWORK_CONFIG_REQUEST__OK__IDX_DICT_LEN + 2)
// ---------------------------------------------------------------------------
namespace ZeroTier {
/**
* ZeroTier packet
*
* Packet format:
* <[8] random initialization vector (doubles as 64-bit packet ID)>
* <[5] destination ZT address>
* <[5] source ZT address>
* <[1] flags (LS 5 bits) and ZT hop count (MS 3 bits)>
* <[8] 8-bit MAC (currently first 8 bytes of poly1305 tag)>
* [... -- begin encryption envelope -- ...]
* <[1] encrypted flags (MS 3 bits) and verb (LS 5 bits)>
* [... verb-specific payload ...]
*
* Packets smaller than 28 bytes are invalid and silently discarded.
*
* MAC is computed on ciphertext *after* encryption. See also:
*
* http://tonyarcieri.com/all-the-crypto-code-youve-ever-written-is-probably-broken
*
* For unencrypted packets, MAC is computed on plaintext. Only HELLO is ever
* sent in the clear, as it's the "here is my public key" message.
*/
class Packet : public Buffer<ZT_PROTO_MAX_PACKET_LENGTH>
{
public:
/**
* A packet fragment
*
* Fragments are sent if a packet is larger than UDP MTU. The first fragment
* is sent with its normal header with the fragmented flag set. Remaining
* fragments are sent this way.
*
* The fragmented bit indicates that there is at least one fragment. Fragments
* themselves contain the total, so the receiver must "learn" this from the
* first fragment it receives.
*
* Fragments are sent with the following format:
* <[8] packet ID of packet whose fragment this belongs to>
* <[5] destination ZT address>
* <[1] 0xff, a reserved address, signals that this isn't a normal packet>
* <[1] total fragments (most significant 4 bits), fragment no (LS 4 bits)>
* <[1] ZT hop count>
* <[...] fragment data>
*
* The protocol supports a maximum of 16 fragments. If a fragment is received
* before its main packet header, it should be cached for a brief period of
* time to see if its parent arrives. Loss of any fragment constitutes packet
* loss; there is no retransmission mechanism. The receiver must wait for full
* receipt to authenticate and decrypt; there is no per-fragment MAC. (But if
* fragments are corrupt, the MAC will fail for the whole assembled packet.)
*/
class Fragment : public Buffer<ZT_PROTO_MAX_PACKET_LENGTH>
{
public:
Fragment() :
Buffer<ZT_PROTO_MAX_PACKET_LENGTH>()
{
}
template<unsigned int C2>
Fragment(const Buffer<C2> &b)
throw(std::out_of_range) :
Buffer<ZT_PROTO_MAX_PACKET_LENGTH>(b)
{
}
/**
* Initialize from a packet
*
* @param p Original assembled packet
* @param fragStart Start of fragment (raw index in packet data)
* @param fragLen Length of fragment in bytes
* @param fragNo Which fragment (>= 1, since 0 is Packet with end chopped off)
* @param fragTotal Total number of fragments (including 0)
* @throws std::out_of_range Packet size would exceed buffer
*/
Fragment(const Packet &p,unsigned int fragStart,unsigned int fragLen,unsigned int fragNo,unsigned int fragTotal)
throw(std::out_of_range)
{
init(p,fragStart,fragLen,fragNo,fragTotal);
}
/**
* Initialize from a packet
*
* @param p Original assembled packet
* @param fragStart Start of fragment (raw index in packet data)
* @param fragLen Length of fragment in bytes
* @param fragNo Which fragment (>= 1, since 0 is Packet with end chopped off)
* @param fragTotal Total number of fragments (including 0)
* @throws std::out_of_range Packet size would exceed buffer
*/
inline void init(const Packet &p,unsigned int fragStart,unsigned int fragLen,unsigned int fragNo,unsigned int fragTotal)
throw(std::out_of_range)
{
if ((fragStart + fragLen) > p.size())
throw std::out_of_range("Packet::Fragment: tried to construct fragment of packet past its length");
setSize(fragLen + ZT_PROTO_MIN_FRAGMENT_LENGTH);
// NOTE: this copies both the IV/packet ID and the destination address.
memcpy(field(ZT_PACKET_FRAGMENT_IDX_PACKET_ID,13),p.data() + ZT_PACKET_IDX_IV,13);
(*this)[ZT_PACKET_FRAGMENT_IDX_FRAGMENT_INDICATOR] = ZT_PACKET_FRAGMENT_INDICATOR;
(*this)[ZT_PACKET_FRAGMENT_IDX_FRAGMENT_NO] = (char)(((fragTotal & 0xf) << 4) | (fragNo & 0xf));
(*this)[ZT_PACKET_FRAGMENT_IDX_HOPS] = 0;
memcpy(field(ZT_PACKET_FRAGMENT_IDX_PAYLOAD,fragLen),p.data() + fragStart,fragLen);
}
/**
* Get this fragment's destination
*
* @return Destination ZT address
*/
inline Address destination() const { return Address(field(ZT_PACKET_FRAGMENT_IDX_DEST,ZT_ADDRESS_LENGTH),ZT_ADDRESS_LENGTH); }
/**
* @return True if fragment is of a valid length
*/
inline bool lengthValid() const { return (size() >= ZT_PACKET_FRAGMENT_IDX_PAYLOAD); }
/**
* @return ID of packet this is a fragment of
*/
inline uint64_t packetId() const { return at<uint64_t>(ZT_PACKET_FRAGMENT_IDX_PACKET_ID); }
/**
* @return Total number of fragments in packet
*/
inline unsigned int totalFragments() const { return (((unsigned int)((*this)[ZT_PACKET_FRAGMENT_IDX_FRAGMENT_NO]) >> 4) & 0xf); }
/**
* @return Fragment number of this fragment
*/
inline unsigned int fragmentNumber() const { return ((unsigned int)((*this)[ZT_PACKET_FRAGMENT_IDX_FRAGMENT_NO]) & 0xf); }
/**
* @return Fragment ZT hop count
*/
inline unsigned int hops() const { return (unsigned int)((*this)[ZT_PACKET_FRAGMENT_IDX_HOPS]); }
/**
* Increment this packet's hop count
*/
inline void incrementHops()
{
(*this)[ZT_PACKET_FRAGMENT_IDX_HOPS] = (((*this)[ZT_PACKET_FRAGMENT_IDX_HOPS]) + 1) & ZT_PROTO_MAX_HOPS;
}
/**
* @return Length of payload in bytes
*/
inline unsigned int payloadLength() const { return ((size() > ZT_PACKET_FRAGMENT_IDX_PAYLOAD) ? (size() - ZT_PACKET_FRAGMENT_IDX_PAYLOAD) : 0); }
/**
* @return Raw packet payload
*/
inline const unsigned char *payload() const
{
return field(ZT_PACKET_FRAGMENT_IDX_PAYLOAD,size() - ZT_PACKET_FRAGMENT_IDX_PAYLOAD);
}
};
/**
* ZeroTier protocol verbs
*/
enum Verb /* Max value: 32 (5 bits) */
{
/* No operation, payload ignored, no reply */
VERB_NOP = 0,
/* Announcement of a node's existence:
* <[1] protocol version>
* <[1] software major version>
* <[1] software minor version>
* <[2] software revision>
* <[8] timestamp (ms since epoch)>
* <[...] binary serialized identity (see Identity)>
*
* OK payload:
* <[8] timestamp (echoed from original HELLO)>
* <[1] protocol version (of responder)>
* <[1] software major version (of responder)>
* <[1] software minor version (of responder)>
* <[2] software revision (of responder)>
*
* ERROR has no payload.
*/
VERB_HELLO = 1,
/* Error response:
* <[1] in-re verb>
* <[8] in-re packet ID>
* <[1] error code>
* <[...] error-dependent payload>
*/
VERB_ERROR = 2,
/* Success response:
* <[1] in-re verb>
* <[8] in-re packet ID>
* <[...] request-specific payload>
*/
VERB_OK = 3,
/* Query an identity by address:
* <[5] address to look up>
*
* OK response payload:
* <[...] binary serialized identity>
*
* Error payload will be address queried.
*/
VERB_WHOIS = 4,
/* Meet another node at a given protocol address:
* <[5] ZeroTier address of peer that might be found at this address>
* <[2] 16-bit protocol address port>
* <[1] protocol address length (4 for IPv4, 16 for IPv6)>
* <[...] protocol address (network byte order)>
*
* This is sent by a relaying node to initiate NAT traversal between two
* peers that are communicating by way of indirect relay. The relay will
* send this to both peers at the same time on a periodic basis, telling
* each where it might find the other on the network.
*
* Upon receipt, a peer sends a message such as NOP or HELLO to the other
* peer. Peers only "learn" one anothers' direct addresses when they
* successfully *receive* a message and authenticate it. Optionally, peers
* will usually preface these messages with one or more firewall openers
* to clear the path.
*
* Nodes should implement rate control, limiting the rate at which they
* respond to these packets to prevent their use in DDOS attacks. Nodes
* may also ignore these messages if a peer is not known or is not being
* actively communicated with.
*
* No OK or ERROR is generated.
*/
VERB_RENDEZVOUS = 5,
/* A ZT-to-ZT unicast ethernet frame:
* <[8] 64-bit network ID>
* <[2] 16-bit ethertype>
* <[...] ethernet payload>
*
* MAC addresses are derived from the packet's source and destination
* ZeroTier addresses. ZeroTier does not support VLANs or other extensions
* beyond core Ethernet.
*
* No OK or ERROR is generated.
*/
VERB_FRAME = 6,
/* Announce interest in multicast group(s):
* <[8] 64-bit network ID>
* <[6] multicast Ethernet address>
* <[4] multicast additional distinguishing information (ADI)>
* [... additional tuples of network/address/adi ...]
*
* OK/ERROR are not generated.
*/
VERB_MULTICAST_LIKE = 7,
/* Announce receipt of a multicast to propagation magnet node:
* <[8] 64-bit network ID>
* <[8] 64-bit multicast GUID>
*
* OK/ERROR are not generated.
*/
VERB_MULTICAST_GOT = 8,
/* A multicast frame:
* <[4] 32-bit forwarding counter>
* <[320] FIFO queue of up to 64 ZT addresses, zero address terminated>
* [... start of signed portion, signed by original submitter below ...]
* <[5] ZeroTier address of propagation magnet node>
* <[5] ZeroTier address of original submitter/signer>
* <[3] 24-bit multicast ID, combined with signer address to form GUID>
* <[8] 64-bit network ID>
* <[6] source MAC address>
* <[6] destination multicast group MAC address>
* <[4] destination multicast group 32-bit ADI field>
* <[2] 16-bit frame ethertype>
* <[2] 16-bit length of payload>
* <[...] ethernet frame payload>
* [... end of signed portion ...]
* <[2] 16-bit length of signature>
* <[...] signature (currently Ed25519/SHA-512, 96 bytes in length)>
*
* Multicast frames are propagated using a graph exploration algorithm in
* which the FIFO queue is embedded in the multicast packet.
*
* Upon receipt:
* (1) packet is possibly injected into the local TAP
* (2) send a MULTICAST_GOT message to magnet node with 64-bit
* multicast GUID
* (3) forwarding counter is incremented, STOP of max exceeded
* (4) topmost value is removed from FIFO and saved (next hop)
* (5) deduplicate FIFO (helps prevent floods)
* (6) FIFO is filled with as many known peers that have LIKED this
* multicast group as possible, excluding peers to whom this
* multicast has already been sent or (if magnet node) have GOT
* this multicast
* (7) packet is sent to next hop (if possible)
*
* If there was no next hop -- empty FIFO -- and no new hops are known,
* the packet is sent to the magnet node. The magnet node must be aware
* of all members of a given multicast group. It is the node responsible
* for bridging sparse multicast groups. When other nodes receive the
* multicast, they send GOT to the magnet node so that it will not
* send it back to them.
*
* Right now the magnet is a supernode. In the future there may be
* dedicated magnets and/or magnets elected via some kind of DHT or
* something to act as such for given multicast groups. This latter
* might happen if we evolve more toward a totally decentralized model
* instead of today's partially decentralized model.
*
* The multicast GUID is formed by packing the original sender / signer
* address into the most significant 5 bytes of a 64-bit big-endian
* number, and then packing the 24-bit sender unique ID into the least
* significant 3 bytes. This can be used to locally deduplicate, and
* to identify the multicast in a GOT sent to the magnet. The 24-bit
* ID must be unique for a given sender over recent (say, 10min) time
* spans and across networks. Random or sequential values are fine.
*
* OK/ERROR are not generated, but GOT is sent to magnet.
*/
VERB_MULTICAST_FRAME = 9,
/* Network member certificate for sending peer:
* <[8] 64-bit network ID>
* <[2] 16-bit length of certificate>
* <[2] 16-bit length of signature>
* <[...] string-serialized certificate dictionary>
* <[...] ECDSA signature of certificate>
*
* OK is generated on acceptance. ERROR is returned on failure. In both
* cases the payload is the network ID.
*/
VERB_NETWORK_MEMBERSHIP_CERTIFICATE = 10,
/* Network configuration request:
* <[8] 64-bit network ID>
* <[2] 16-bit length of request meta-data dictionary>
* <[...] string-serialized request meta-data>
*
* This message requests network configuration from a node capable of
* providing it. Such nodes run the netconf service, which must be
* installed into the ZeroTier home directory.
*
* OK response payload:
* <[8] 64-bit network ID>
* <[2] 16-bit length of network configuration dictionary>
* <[...] network configuration dictionary>
*
* OK returns a Dictionary (string serialized) containing the network's
* configuration and IP address assignment information for the querying
* node. It also contains a membership certificate that the querying
* node can push to other peers to demonstrate its right to speak on
* a given network.
*
* ERROR may be NOT_FOUND if no such network is known, or
* UNSUPPORTED_OPERATION if the netconf service isn't available. The
* payload will be the network ID.
*/
VERB_NETWORK_CONFIG_REQUEST = 11,
/* Network configuration refresh request:
* <[8] 64-bit network ID>
*
* This message can be sent by the network configuration master node
* to request that nodes refresh their network configuration. It can
* thus be used to "push" updates.
*
* It does not generate an OK or ERROR message, and is treated only as
* a hint to refresh now.
*/
VERB_NETWORK_CONFIG_REFRESH = 12
};
/**
* Error codes for VERB_ERROR
*/
enum ErrorCode
{
/* No error, not actually used in transit */
ERROR_NONE = 0,
/* Invalid request */
ERROR_INVALID_REQUEST = 1,
/* Bad/unsupported protocol version */
ERROR_BAD_PROTOCOL_VERSION = 2,
/* Unknown object queried (e.g. with WHOIS) */
ERROR_OBJ_NOT_FOUND = 3,
/* HELLO pushed an identity whose address is already claimed */
ERROR_IDENTITY_COLLISION = 4,
/* Identity was not valid */
ERROR_IDENTITY_INVALID = 5,
/* Verb or use case not supported/enabled by this node */
ERROR_UNSUPPORTED_OPERATION = 6,
/* Message to private network rejected -- no unexpired certificate on file */
ERROR_NO_MEMBER_CERTIFICATE = 7
};
/**
* @param v Verb
* @return String representation (e.g. HELLO, OK)
*/
static const char *verbString(Verb v)
throw();
/**
* @param e Error code
* @return String error name
*/
static const char *errorString(ErrorCode e)
throw();
template<unsigned int C2>
Packet(const Buffer<C2> &b)
throw(std::out_of_range) :
Buffer<ZT_PROTO_MAX_PACKET_LENGTH>(b)
{
}
/**
* Construct a new empty packet with a unique random packet ID
*
* Flags and hops will be zero. Other fields and data region are undefined.
* Use the header access methods (setDestination() and friends) to fill out
* the header. Payload should be appended; initial size is header size.
*/
Packet() :
Buffer<ZT_PROTO_MAX_PACKET_LENGTH>(ZT_PROTO_MIN_PACKET_LENGTH)
{
Utils::getSecureRandom(field(ZT_PACKET_IDX_IV,8),8);
(*this)[ZT_PACKET_IDX_FLAGS] = 0; // zero flags and hops
}
/**
* Construct a new empty packet with a unique random packet ID
*
* @param dest Destination ZT address
* @param source Source ZT address
* @param v Verb
*/
Packet(const Address &dest,const Address &source,const Verb v) :
Buffer<ZT_PROTO_MAX_PACKET_LENGTH>(ZT_PROTO_MIN_PACKET_LENGTH)
{
Utils::getSecureRandom(field(ZT_PACKET_IDX_IV,8),8);
setDestination(dest);
setSource(source);
(*this)[ZT_PACKET_IDX_FLAGS] = 0; // zero flags and hops
setVerb(v);
}
/**
* Reset this packet structure for reuse in place
*
* @param dest Destination ZT address
* @param source Source ZT address
* @param v Verb
*/
inline void reset(const Address &dest,const Address &source,const Verb v)
{
setSize(ZT_PROTO_MIN_PACKET_LENGTH);
Utils::getSecureRandom(field(ZT_PACKET_IDX_IV,8),8);
setDestination(dest);
setSource(source);
(*this)[ZT_PACKET_IDX_FLAGS] = 0; // zero flags and hops
setVerb(v);
}
/**
* Generate a new IV / packet ID in place
*
* This can be used to re-use a packet buffer multiple times to send
* technically different but otherwise identical copies of the same
* packet.
*/
inline void newInitializationVector()
{
Utils::getSecureRandom(field(ZT_PACKET_IDX_IV,8),8);
}
/**
* Set this packet's destination
*
* @param dest ZeroTier address of destination
*/
inline void setDestination(const Address &dest)
{
unsigned char *d = field(ZT_PACKET_IDX_DEST,ZT_ADDRESS_LENGTH);
for(unsigned int i=0;i<ZT_ADDRESS_LENGTH;++i)
d[i] = dest[i];
}
/**
* Set this packet's source
*
* @param source ZeroTier address of source
*/
inline void setSource(const Address &source)
{
unsigned char *s = field(ZT_PACKET_IDX_SOURCE,ZT_ADDRESS_LENGTH);
for(unsigned int i=0;i<ZT_ADDRESS_LENGTH;++i)
s[i] = source[i];
}
/**
* Get this packet's destination
*
* @return Destination ZT address
*/
inline Address destination() const { return Address(field(ZT_PACKET_IDX_DEST,ZT_ADDRESS_LENGTH),ZT_ADDRESS_LENGTH); }
/**
* Get this packet's source
*
* @return Source ZT address
*/
inline Address source() const { return Address(field(ZT_PACKET_IDX_SOURCE,ZT_ADDRESS_LENGTH),ZT_ADDRESS_LENGTH); }
/**
* @return True if packet is of valid length
*/
inline bool lengthValid() const { return (size() >= ZT_PROTO_MIN_PACKET_LENGTH); }
/**
* @return True if packet is encrypted
*/
inline bool encrypted() const { return (((unsigned char)(*this)[ZT_PACKET_IDX_FLAGS] & ZT_PROTO_FLAG_ENCRYPTED) != 0); }
/**
* @return True if packet is fragmented (expect fragments)
*/
inline bool fragmented() const { return (((unsigned char)(*this)[ZT_PACKET_IDX_FLAGS] & ZT_PROTO_FLAG_FRAGMENTED) != 0); }
/**
* Set this packet's fragmented flag
*
* @param f Fragmented flag value
*/
inline void setFragmented(bool f)
{
if (f)
(*this)[ZT_PACKET_IDX_FLAGS] |= (char)ZT_PROTO_FLAG_FRAGMENTED;
else (*this)[ZT_PACKET_IDX_FLAGS] &= (char)(~ZT_PROTO_FLAG_FRAGMENTED);
}
/**
* @return True if compressed (result only valid if unencrypted)
*/
inline bool compressed() const { return (((unsigned char)(*this)[ZT_PACKET_IDX_VERB] & ZT_PROTO_VERB_FLAG_COMPRESSED) != 0); }
/**
* @return ZeroTier forwarding hops (0 to 7)
*/
inline unsigned int hops() const { return ((unsigned int)(*this)[ZT_PACKET_IDX_FLAGS] & 0x07); }
/**
* Increment this packet's hop count
*/
inline void incrementHops()
{
(*this)[ZT_PACKET_IDX_FLAGS] = (char)((unsigned char)(*this)[ZT_PACKET_IDX_FLAGS] & 0xf8) | (((unsigned char)(*this)[ZT_PACKET_IDX_FLAGS] + 1) & 0x07);
}
/**
* Get this packet's unique ID (the IV field interpreted as uint64_t)
*
* @return Packet ID
*/
inline uint64_t packetId() const { return at<uint64_t>(ZT_PACKET_IDX_IV); }
/**
* Set packet verb
*
* This also has the side-effect of clearing any verb flags, such as
* compressed, and so must only be done during packet composition.
*
* @param v New packet verb
*/
inline void setVerb(Verb v) { (*this)[ZT_PACKET_IDX_VERB] = (char)v; }
/**
* @return Packet verb (not including flag bits)
*/
inline Verb verb() const { return (Verb)((*this)[ZT_PACKET_IDX_VERB] & 0x1f); }
/**
* @return Length of packet payload
*/
inline unsigned int payloadLength() const { return ((size() < ZT_PROTO_MIN_PACKET_LENGTH) ? 0 : (size() - ZT_PROTO_MIN_PACKET_LENGTH)); }
/**
* @return Raw packet payload
*/
inline const unsigned char *payload() const
{
return field(ZT_PACKET_IDX_PAYLOAD,size() - ZT_PACKET_IDX_PAYLOAD);
}
/**
* Armor packet for transport
*
* @param key 32-byte key
* @param encryptPayload If true, encrypt packet payload, else just MAC
*/
inline void armor(const void *key,bool encryptPayload)
{
unsigned char mangledKey[32];
unsigned char macKey[32];
unsigned char mac[16];
const unsigned int payloadLen = size() - ZT_PACKET_IDX_VERB;
unsigned char *const payload = field(ZT_PACKET_IDX_VERB,payloadLen);
// Set flag now, since it affects key mangle function
if (encryptPayload)
(*this)[ZT_PACKET_IDX_FLAGS] |= (char)ZT_PROTO_FLAG_ENCRYPTED;
else (*this)[ZT_PACKET_IDX_FLAGS] &= (char)(~ZT_PROTO_FLAG_ENCRYPTED);
_mangleKey((const unsigned char *)key,mangledKey);
Salsa20 s20(mangledKey,256,field(ZT_PACKET_IDX_IV,8));
// MAC key is always the first 32 bytes of the Salsa20 key stream
// This is the same construction DJB's NaCl library uses
s20.encrypt(ZERO_KEY,macKey,sizeof(macKey));
if (encryptPayload)
s20.encrypt(payload,payload,payloadLen);
Poly1305::compute(mac,payload,payloadLen,macKey);
memcpy(field(ZT_PACKET_IDX_MAC,8),mac,8);
}
/**
* Verify and (if encrypted) decrypt packet
*
* @param key 32-byte key
* @return False if packet is invalid or failed MAC authenticity check
*/
inline bool dearmor(const void *key)
{
unsigned char mangledKey[32];
unsigned char macKey[32];
unsigned char mac[16];
const unsigned int payloadLen = size() - ZT_PACKET_IDX_VERB;
unsigned char *const payload = field(ZT_PACKET_IDX_VERB,payloadLen);
_mangleKey((const unsigned char *)key,mangledKey);
Salsa20 s20(mangledKey,256,field(ZT_PACKET_IDX_IV,8));
s20.encrypt(ZERO_KEY,macKey,sizeof(macKey));
Poly1305::compute(mac,payload,payloadLen,macKey);
if (!Utils::secureEq(mac,field(ZT_PACKET_IDX_MAC,8),8))
return false;
if (((*this)[ZT_PACKET_IDX_FLAGS] & (char)ZT_PROTO_FLAG_ENCRYPTED)) {
s20.decrypt(payload,payload,payloadLen);
(*this)[ZT_PACKET_IDX_FLAGS] &= (char)(~ZT_PROTO_FLAG_ENCRYPTED);
}
return true;
}
/**
* Attempt to compress payload if not already (must be unencrypted)
*
* This requires that the payload at least contain the verb byte already
* set. The compressed flag in the verb is set if compression successfully
* results in a size reduction. If no size reduction occurs, compression
* is not done and the flag is left cleared.
*
* @return True if compression occurred
*/
inline bool compress()
{
unsigned char buf[ZT_PROTO_MAX_PACKET_LENGTH * 2];
if ((!compressed())&&(size() > (ZT_PACKET_IDX_PAYLOAD + 32))) {
int pl = (int)(size() - ZT_PACKET_IDX_PAYLOAD);
int cl = LZ4_compress((const char *)field(ZT_PACKET_IDX_PAYLOAD,(unsigned int)pl),(char *)buf,pl);
if ((cl > 0)&&(cl < pl)) {
(*this)[ZT_PACKET_IDX_VERB] |= (char)ZT_PROTO_VERB_FLAG_COMPRESSED;
setSize((unsigned int)cl + ZT_PACKET_IDX_PAYLOAD);
memcpy(field(ZT_PACKET_IDX_PAYLOAD,(unsigned int)cl),buf,cl);
return true;
}
}
(*this)[ZT_PACKET_IDX_VERB] &= (char)(~ZT_PROTO_VERB_FLAG_COMPRESSED);
return false;
}
/**
* Attempt to decompress payload if it is compressed (must be unencrypted)
*
* If payload is compressed, it is decompressed and the compressed verb
* flag is cleared. Otherwise nothing is done and true is returned.
*
* @return True if data is now decompressed and valid, false on error
*/
inline bool uncompress()
{
unsigned char buf[ZT_PROTO_MAX_PACKET_LENGTH];
if ((compressed())&&(size() >= ZT_PROTO_MIN_PACKET_LENGTH)) {
if (size() > ZT_PACKET_IDX_PAYLOAD) {
unsigned int compLen = size() - ZT_PACKET_IDX_PAYLOAD;
int ucl = LZ4_uncompress_unknownOutputSize((const char *)field(ZT_PACKET_IDX_PAYLOAD,compLen),(char *)buf,compLen,sizeof(buf));
if ((ucl > 0)&&(ucl <= (int)(capacity() - ZT_PACKET_IDX_PAYLOAD))) {
setSize((unsigned int)ucl + ZT_PACKET_IDX_PAYLOAD);
memcpy(field(ZT_PACKET_IDX_PAYLOAD,(unsigned int)ucl),buf,ucl);
} else return false;
}
(*this)[ZT_PACKET_IDX_VERB] &= (char)(~ZT_PROTO_VERB_FLAG_COMPRESSED);
}
return true;
}
private:
static const unsigned char ZERO_KEY[32];
/**
* Deterministically mangle a 256-bit crypto key based on packet
*
* @param in Input key (32 bytes)
* @param out Output buffer (32 bytes)
*/
inline void _mangleKey(const unsigned char *in,unsigned char *out) const
{
// IV and source/destination addresses. Using the addresses divides the
// key space into two halves-- A->B and B->A (since order will change).
for(unsigned int i=0;i<18;++i) // 8 + (ZT_ADDRESS_LENGTH * 2) == 18
out[i] = in[i] ^ (unsigned char)(*this)[i];
// Flags, but with hop count masked off. Hop count is altered by forwarding
// nodes. It's one of the only parts of a packet modifiable by people
// without the key.
out[18] = in[18] ^ ((unsigned char)(*this)[ZT_PACKET_IDX_FLAGS] & 0xf8);
// Raw packet size in bytes -- thus each packet size defines a new
// key space.
out[19] = in[19] ^ (unsigned char)(size() & 0xff);
out[20] = in[20] ^ (unsigned char)((size() >> 8) & 0xff); // little endian
// Rest of raw key is used unchanged
for(unsigned int i=21;i<32;++i)
out[i] = in[i];
}
};
} // namespace ZeroTier
#endif
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