diff options
Diffstat (limited to 'bip-0155.mediawiki')
| -rw-r--r-- | bip-0155.mediawiki | 40 |
1 files changed, 20 insertions, 20 deletions
diff --git a/bip-0155.mediawiki b/bip-0155.mediawiki index 5914241..f437043 100644 --- a/bip-0155.mediawiki +++ b/bip-0155.mediawiki @@ -46,7 +46,7 @@ The <code>addrv2</code> message is defined as a message where <code>pchCommand = 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. +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 +55,13 @@ 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 +78,8 @@ 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 +120,23 @@ 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". -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. +<code>sendaddrv2</code> SHOULD be sent after receiving the <code>verack</code> message from the peer. + +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== @@ -142,9 +144,7 @@ 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 |