DEP 0001: Version Message Info

status: accepted


Currently version messages are empty, but before releasing in order to anticipate protocol upgrades, we should include the protocol version. This is for the moment inside verack, but should be moved to version since it allows immediately dropping the connection if the protocol version is incorrect (and indeed is the main purpose of the version message).

Additionally it should include further info which makes debugging connections and negotiation easier.


u32versionIdentifies protocol version being used by the node
u64timestampUNIX timestamp
u16nonceRandom nonce, randomly generated everytime a version packet is sent. This nonce is used to detect connections to self.
Urlconnect_recv_addrNetwork address of the node receiving this message (before resolving)
Option<Url>resolv_recv_addrNetwork address of the node receiving this message (after resolving)
Vec<String>ext_send_addr(Optional) External address of the node sending this message
Vec<(String, u32)>(services, version)List of features to be enabled for this connection

resolv_recv_addr is optional as inbound connections do not have such an address.

ext_send_addr is empty when no external address is set.

The (services, version) field can be used to enable certain features in protocols, or even to upgrade protocols to new versions. When protocols are first attached, they can add their own data to this field which will be communicated in the subsequent version exchange. Any further negotiation needed can be done using protocol specific messages afterwards.