diff options
Diffstat (limited to 'bip-0155.mediawiki')
| -rw-r--r-- | bip-0155.mediawiki | 189 |
1 files changed, 189 insertions, 0 deletions
diff --git a/bip-0155.mediawiki b/bip-0155.mediawiki new file mode 100644 index 0000000..3e7b0d8 --- /dev/null +++ b/bip-0155.mediawiki @@ -0,0 +1,189 @@ +<pre> + BIP: 155 + Layer: Peer Services + Title: addrv2 message + Author: Wladimir J. van der Laan <laanwj@gmail.com> + Comments-Summary: No comments yet. + Comments-URI: https://github.com/bitcoin/bips/wiki/Comments:BIP-0155 + Status: Draft + Type: Standards Track + Created: 2019-02-27 + License: BSD-2-Clause +</pre> + +==Introduction== + +===Abstract=== + +This document proposes a new P2P message to gossip longer node addresses over the P2P network. +This is required to support new-generation Onion addresses, I2P, and potentially other networks +that have longer endpoint addresses than fit in the 128 bits of the current <code>addr</code> message. + +===Copyright=== + +This BIP is licensed under the 2-clause BSD license. + +===Motivation=== + +Tor v3 hidden services are part of the stable release of Tor since version 0.3.2.9. They have +various advantages compared to the old hidden services, among which better encryption and privacy +<ref>[https://gitweb.torproject.org/torspec.git/tree/rend-spec-v3.txt Tor Rendezvous Specification - Version 3]</ref>. +These services have 256 bit addresses and thus do not fit in the existing <code>addr</code> message, which encapsulates onion addresses in OnionCat IPv6 addresses. + +Other transport-layer protocols such as I2P have always used longer +addresses. This change would make it possible to gossip such addresses over the +P2P network, so that other peers can connect to them. + +==Specification== + +<blockquote> +The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", +"SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be +interpreted as described in RFC 2119<ref>[https://tools.ietf.org/html/rfc2119 RFC 2119]</ref>. +</blockquote> + +The <code>addrv2</code> message is defined as a message where <code>pchCommand == "addrv2"</code>. +It is serialized in the standard encoding for P2P messages. +Its format is similar to the current <code>addr</code> message format, with the difference that the +fixed 16-byte IP address is replaced by a network ID and a variable-length address, and the services format has been changed to [https://en.bitcoin.it/wiki/Protocol_documentation#Variable_length_integer CompactSize]. + +This means that the message contains a serialized <code>std::vector</code> of the following structure: + +{| class="wikitable" style="width: auto; text-align: center; font-size: smaller; table-layout: fixed;" +!Type +!Name +!Description +|- +| <code>uint32_t</code> +| <code>time</code> +| Time that this node was last seen as connected to the network. A time in Unix epoch time format. +|- +| <code>CompactSize</code> +| <code>services</code> +| Service bits. A bit field that is 64 bits wide, encoded in [https://en.bitcoin.it/wiki/Protocol_documentation#Variable_length_integer CompactSize]. +|- +| <code>uint8_t</code> +| <code>networkID</code> +| Network identifier. An 8-bit value that specifies which network is addressed. +|- +| <code>std::vector<uint8_t></code> +| <code>addr</code> +| Network address. The interpretation depends on networkID. +|- +| <code>uint16_t</code> +| <code>port</code> +| Network port. If not relevant for the network this MUST be 0. +|} + +One message can contain up to 1,000 addresses. Clients SHOULD reject messages with more addresses. + +Field <code>addr</code> has a variable length, with a maximum of 512 bytes (4096 bits). +Clients SHOULD reject messages with longer addresses, irrespective of the network ID. + +The list of reserved network IDs is as follows: + +{| class="wikitable" style="width: auto; text-align: center; font-size: smaller; table-layout: fixed;" +!Network ID +!Enumeration +!Address length (bytes) +!Description +|- +| <code>0x01</code> +| <code>IPV4</code> +| 4 +| IPv4 address (globally routed internet) +|- +| <code>0x02</code> +| <code>IPV6</code> +| 16 +| IPv6 address (globally routed internet) +|- +| <code>0x03</code> +| <code>TORV2</code> +| 10 +| Tor v2 hidden service address +|- +| <code>0x04</code> +| <code>TORV3</code> +| 32 +| Tor v3 hidden service address +|- +| <code>0x05</code> +| <code>I2P</code> +| 32 +| I2P overlay network address +|- +| <code>0x06</code> +| <code>CJDNS</code> +| 16 +| Cjdns overlay network address +|} + +Clients are RECOMMENDED to gossip addresses from all known networks even if they are currently not connected to some of them. That could help multi-homed nodes and make it more difficult for an observer to tell which networks a node is connected to. + +Clients SHOULD NOT gossip addresses from unknown networks because they have no means to validate those addresses and so can be tricked to gossip invalid addresses. + +Further network ID numbers MUST be reserved in a new BIP document. + +Clients SHOULD reject messages that contain addresses that have a different length than specified in this table for a specific network ID, as these are meaningless. + +See the appendices for the address encodings to be used for the various networks. + +==Signaling support and compatibility== + +Introduce a new message type <code>sendaddrv2</code>. Sending such a message indicates that a node can understand and prefers to receive <code>addrv2</code> messages instead of <code>addr</code> messages. I.e. "Send me addrv2". Sending or not sending this message does not imply any preference with respect to receiving unrequested address messages. + +The <code>sendaddrv2</code> message MUST only be sent in response to the <code>version</code> message from a peer and prior to sending the <code>verack</code> message. + +For older peers, that did not emit <code>sendaddrv2</code>, keep sending the legacy <code>addr</code> message, ignoring addresses with the newly introduced address types. + +==Reference implementation== + +The reference implementation is available at (to be done) + +==Acknowledgements== + +- Jonas Schnelli: change <code>services</code> field to [https://en.bitcoin.it/wiki/Protocol_documentation#Variable_length_integer CompactSize], to make the message more compact in the likely case instead of always using 8 bytes. + +- Gregory Maxwell: various suggestions regarding extensibility + +==Appendix A: Tor v2 address encoding== + +The new message introduces a separate network ID for <code>TORV2</code>. + +Clients MUST send Tor hidden service addresses with this network ID, with the 80-bit hidden service ID in the address field. This is the same as the representation in the legacy <code>addr</code> message, minus the 6 byte prefix of the OnionCat wrapping. + +Clients SHOULD ignore OnionCat (<code>fd87:d87e:eb43::/48</code>) addresses on receive if they come with the <code>IPV6</code> network ID. + +==Appendix B: Tor v3 address encoding== + +According to the spec <ref>[https://gitweb.torproject.org/torspec.git/tree/rend-spec-v3.txt Tor Rendezvous Specification - Version 3: Encoding onion addresses]</ref>, next-gen <code>.onion</code> addresses are encoded as follows: +<pre> +onion_address = base32(PUBKEY | CHECKSUM | VERSION) + ".onion" + CHECKSUM = H(".onion checksum" | PUBKEY | VERSION)[:2] + + where: + - PUBKEY is the 32 bytes ed25519 master pubkey of the hidden service + - VERSION is a one byte version field (default value '\x03') + - ".onion checksum" is a constant string + - CHECKSUM is truncated to two bytes before inserting it in onion_address + - H() is the SHA3-256 cryptographic hash function +</pre> + +Tor v3 addresses MUST be sent with the <code>TORV3</code> network ID, with the 32-byte PUBKEY part in the address field. As VERSION will always be '\x03' in the case of v3 addresses, this is enough to reconstruct the onion address. + +==Appendix C: I2P address encoding== + +Like Tor, I2P naming uses a base32-encoded address format<ref>[https://geti2p.net/en/docs/naming#base32 I2P: Naming and address book]</ref>. + +I2P uses 52 characters (256 bits) to represent the full SHA-256 hash, followed by <code>.b32.i2p</code>. + +I2P addresses MUST be sent with the <code>I2P</code> network ID, with the decoded SHA-256 hash as address field. + +==Appendix D: Cjdns address encoding== + +Cjdns addresses are simply IPv6 addresses in the <code>fc00::/8</code> range<ref>[https://github.com/cjdelisle/cjdns/blob/6e46fa41f5647d6b414612d9d63626b0b952746b/doc/Whitepaper.md#pulling-it-all-together Cjdns whitepaper: Pulling It All Together]</ref>. They MUST be sent with the <code>CJDNS</code> network ID. + +==References== + +<references/> |