Move p2p::constants::PROTOCOL_VERSION to p2p module

The `PROTOCOL_VERSION` const is a p2p layer constant. It can live in the
`mod.rs` file of the `p2p` module.

This is a straight code move, the `PROTOCOL_VERSION` replaces the
current re-export.

bitcoin/src/p2p/constants.rs

@@ -42,23 +42,6 @@ use crate::error::impl_std_error;
 use crate::io;
 use crate::prelude::{String, ToOwned};
 
-/// Version of the protocol as appearing in network message headers
-/// This constant is used to signal to other peers which features you support.
-/// Increasing it implies that your software also supports every feature prior to this version.
-/// Doing so without support may lead to you incorrectly banning other peers or other peers banning you.
-/// These are the features required for each version:
-/// 70016 - Support receiving `wtxidrelay` message between `version` and `verack` message
-/// 70015 - Support receiving invalid compact blocks from a peer without banning them
-/// 70014 - Support compact block messages `sendcmpct`, `cmpctblock`, `getblocktxn` and `blocktxn`
-/// 70013 - Support `feefilter` message
-/// 70012 - Support `sendheaders` message and announce new blocks via headers rather than inv
-/// 70011 - Support NODE_BLOOM service flag and don't support bloom filter messages if it is not set
-/// 70002 - Support `reject` message
-/// 70001 - Support bloom filter messages `filterload`, `filterclear` `filteradd`, `merkleblock` and FILTERED_BLOCK inventory type
-/// 60002 - Support `mempool` message
-/// 60001 - Support `pong` message and nonce in `ping` message
-pub const PROTOCOL_VERSION: u32 = 70001;
-
 /// The cryptocurrency network to act on.
 #[derive(Copy, PartialEq, Eq, PartialOrd, Ord, Clone, Hash, Debug)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]

bitcoin/src/p2p/message_blockdata.rs

@@ -11,9 +11,8 @@ use hashes::{sha256d, Hash as _};
 use crate::consensus::encode::{self, Decodable, Encodable};
 use crate::hash_types::{BlockHash, Txid, Wtxid};
 use crate::internal_macros::impl_consensus_encoding;
-use crate::io;
-use crate::p2p::constants;
 use crate::prelude::*;
+use crate::{io, p2p};
 
 /// An inventory item.
 #[derive(PartialEq, Eq, Clone, Debug, Copy, Hash, PartialOrd, Ord)]
@@ -128,7 +127,7 @@ pub struct GetHeadersMessage {
 impl GetBlocksMessage {
     /// Construct a new `getblocks` message
     pub fn new(locator_hashes: Vec<BlockHash>, stop_hash: BlockHash) -> GetBlocksMessage {
-        GetBlocksMessage { version: constants::PROTOCOL_VERSION, locator_hashes, stop_hash }
+        GetBlocksMessage { version: p2p::PROTOCOL_VERSION, locator_hashes, stop_hash }
     }
 }
 
@@ -137,7 +136,7 @@ impl_consensus_encoding!(GetBlocksMessage, version, locator_hashes, stop_hash);
 impl GetHeadersMessage {
     /// Construct a new `getheaders` message
     pub fn new(locator_hashes: Vec<BlockHash>, stop_hash: BlockHash) -> GetHeadersMessage {
-        GetHeadersMessage { version: constants::PROTOCOL_VERSION, locator_hashes, stop_hash }
+        GetHeadersMessage { version: p2p::PROTOCOL_VERSION, locator_hashes, stop_hash }
     }
 }
 

bitcoin/src/p2p/message_network.rs

@@ -10,10 +10,10 @@ use hashes::sha256d;
 
 use crate::consensus::{encode, Decodable, Encodable, ReadExt};
 use crate::internal_macros::impl_consensus_encoding;
-use crate::io;
 use crate::p2p::address::Address;
-use crate::p2p::constants::{self, ServiceFlags};
+use crate::p2p::constants::ServiceFlags;
 use crate::prelude::*;
+use crate::{io, p2p};
 
 /// Some simple messages
 
@@ -54,7 +54,7 @@ impl VersionMessage {
         start_height: i32,
     ) -> VersionMessage {
         VersionMessage {
-            version: constants::PROTOCOL_VERSION,
+            version: p2p::PROTOCOL_VERSION,
             services,
             timestamp,
             receiver,

bitcoin/src/p2p/mod.rs

@@ -25,3 +25,20 @@ pub mod message_filter;
 pub mod message_network;
 
 pub use self::constants::Magic;
+
+/// Version of the protocol as appearing in network message headers
+/// This constant is used to signal to other peers which features you support.
+/// Increasing it implies that your software also supports every feature prior to this version.
+/// Doing so without support may lead to you incorrectly banning other peers or other peers banning you.
+/// These are the features required for each version:
+/// 70016 - Support receiving `wtxidrelay` message between `version` and `verack` message
+/// 70015 - Support receiving invalid compact blocks from a peer without banning them
+/// 70014 - Support compact block messages `sendcmpct`, `cmpctblock`, `getblocktxn` and `blocktxn`
+/// 70013 - Support `feefilter` message
+/// 70012 - Support `sendheaders` message and announce new blocks via headers rather than inv
+/// 70011 - Support NODE_BLOOM service flag and don't support bloom filter messages if it is not set
+/// 70002 - Support `reject` message
+/// 70001 - Support bloom filter messages `filterload`, `filterclear` `filteradd`, `merkleblock` and FILTERED_BLOCK inventory type
+/// 60002 - Support `mempool` message
+/// 60001 - Support `pong` message and nonce in `ping` message
+pub const PROTOCOL_VERSION: u32 = 70001;