diff options
Diffstat (limited to 'bip-0155.mediawiki')
-rw-r--r-- | bip-0155.mediawiki | 50 |
1 files changed, 25 insertions, 25 deletions
diff --git a/bip-0155.mediawiki b/bip-0155.mediawiki index 5914241..3e7b0d8 100644 --- a/bip-0155.mediawiki +++ b/bip-0155.mediawiki @@ -44,9 +44,8 @@ interpreted as described in RFC 2119<ref>[https://tools.ietf.org/html/rfc2119 RF 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 -<ref>[https://bitcoin.org/en/developer-reference#addr Bitcoin Developer Reference: addr message]</ref>, with the difference that the -fixed 16-byte IP address is replaced by a network ID and a variable-length address, and the time and services format has been changed to VARINT. +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: @@ -55,13 +54,13 @@ This means that the message contains a serialized <code>std::vector</code> of th !Name !Description |- -| <code>VARINT</code> (unsigned) +| <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, up to 64 bits wide. +| Time that this node was last seen as connected to the network. A time in Unix epoch time format. |- -| <code>VARINT</code> (unsigned) +| <code>CompactSize</code> | <code>services</code> -| Service bits. A 64-wide bit field. +| 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> @@ -78,8 +77,8 @@ This means that the message contains a serialized <code>std::vector</code> of th 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 32 bytes (256 bits). Clients SHOULD reject -longer 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: @@ -120,21 +119,23 @@ The list of reserved network IDs is as follows: | Cjdns overlay network address |} -To allow for future extensibility, clients MUST ignore address types that they do not know about. -Client MAY store and gossip address formats that they do not know about. Further network ID numbers MUST be reserved in a new BIP document. +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 reject addresses that have a different length than specified in this table for a specific address ID, as these are meaningless. +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. -==Compatibility== +==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. -Send <code>addrv2</code> messages only, and exclusively, when the peer has a certain protocol version (or higher): -<source lang="c++"> -//! gossiping using `addrv2` messages starts with this version -static const int GOSSIP_ADDRV2_VERSION = 70016; -</source> -For older peers keep sending the legacy <code>addr</code> message, ignoring addresses with the newly introduced address types. +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== @@ -142,15 +143,13 @@ The reference implementation is available at (to be done) ==Acknowledgements== -- Jonas Schnelli: change <code>services</code> field to VARINT, to make the message more compact in the likely case instead of always using 8 bytes. - -- Luke-Jr: change <code>time</code> field to VARINT, for post-2038 compatibility. +- 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>. +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. @@ -164,10 +163,11 @@ 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 an one byte version field (default value '\x03') + - 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. |