p2p: Add "feeler" connection

p2p/examples/feeler.rs

@@ -22,9 +22,15 @@ fn main() {
         .set_user_agent("/bitcoin-feeler:0.1.0".to_string())
         .connection_timeout(Duration::from_millis(3500))
         .change_network(NETWORK)
-        .open_connection(socket_addr);
+        .open_feeler(socket_addr);
     match connection {
-        Ok(_) => tracing::info!("Connection successful!"),
+        Ok(f) => {
+            tracing::info!(
+                "Connection successful: Advertised protocol version {}, Adveristed services {}",
+                f.protocol_version.0,
+                f.services
+            );
+        }
         Err(e) => tracing::warn!("Connection failed {e:?}"),
     }
 }

p2p/src/lib.rs

@@ -70,6 +70,7 @@ impl ConnectionContext {
         read_half: ReadHalf,
         negotiation: Negotiation,
         their_services: ServiceFlags,
+        their_version: ProtocolVerison,
     ) -> Self {
         let read_ctx = ReadContext {
             read_half,
@@ -83,6 +84,7 @@ impl ConnectionContext {
             write_half,
             negotiation,
             their_services,
+            their_protocol_verison: their_version,
         };
         Self {
             read_ctx,
@@ -210,6 +212,7 @@ pub struct WriteContext {
     write_half: WriteHalf,
     negotiation: Negotiation,
     their_services: ServiceFlags,
+    their_protocol_verison: ProtocolVerison,
 }
 
 impl WriteContext {
@@ -432,6 +435,12 @@ impl Default for Offered {
     }
 }
 
+#[derive(Debug, Clone, Copy)]
+pub struct Feeler {
+    pub services: ServiceFlags,
+    pub protocol_version: ProtocolVerison,
+}
+
 pub(crate) struct MessageHeader {
     magic: Magic,
     _command: CommandString,
@@ -490,7 +499,7 @@ fn interpret_first_message(
     nonce: u64,
     their_expected_version: ProtocolVerison,
     their_expected_services: ServiceFlags,
-) -> Result<(), HandshakeError> {
+) -> Result<(ProtocolVerison, ServiceFlags), HandshakeError> {
     if let NetworkMessage::Version(version) = message {
         if version.nonce.eq(&nonce) {
             return Err(HandshakeError::ConnectedToSelf);
@@ -503,10 +512,10 @@ fn interpret_first_message(
         if !version.services.has(their_expected_services) {
             return Err(HandshakeError::UnsupportedFeature);
         }
+        Ok((ProtocolVerison(version.version), version.services))
     } else {
-        return Err(HandshakeError::IrrelevantMessage(message));
+        Err(HandshakeError::IrrelevantMessage(message))
     }
-    Ok(())
 }
 
 /// Errors when parsing a peer-to-peer message.
@@ -656,8 +665,15 @@ macro_rules! define_version_message_logic {
         let version = $awaiter!(read_half.read_message(&mut $reader))?;
         match version {
             Some(version) => {
-                interpret_first_message(version, nonce, $conn.their_version, $conn.their_services)
-                    .map_err(ConnectionError::Protocol)?;
+                let (protocol, services) = interpret_first_message(
+                    version,
+                    nonce,
+                    $conn.their_version,
+                    $conn.their_services,
+                )
+                .map_err(ConnectionError::Protocol)?;
+                $conn.their_services = services;
+                $conn.their_version = protocol;
             }
             None => {
                 return Err(ConnectionError::Protocol(HandshakeError::BadDecoy));
@@ -717,8 +733,13 @@ macro_rules! define_version_message_logic {
                 &mut write_half,
             ))?;
         }
-        let context =
-            ConnectionContext::new(write_half, read_half, negotiation, $conn.their_services);
+        let context = ConnectionContext::new(
+            write_half,
+            read_half,
+            negotiation,
+            $conn.their_services,
+            $conn.their_version,
+        );
         Ok(($reader, context))
     }};
 }

p2p/src/net.rs

@@ -11,7 +11,7 @@ use bitcoin::{consensus, p2p::message_compact_blocks::SendCmpct};
 
 use crate::{
     blocking_awaiter, interpret_first_message, make_version, version_handshake_blocking,
-    ConnectionBuilder, ConnectionContext, HandshakeError, Negotiation, ParseMessageError,
+    ConnectionBuilder, ConnectionContext, Feeler, HandshakeError, Negotiation, ParseMessageError,
     ReadContext, ReadHalf, WriteContext, WriteHalf,
 };
 
@@ -30,11 +30,15 @@ pub trait ConnectionExt {
         self,
         tcp_stream: TcpStream,
     ) -> Result<(TcpStream, ConnectionContext), ConnectionError>;
+
+    /// Open a "feeler" connection to test if the peer is online and update their services and
+    /// protocol version.
+    fn open_feeler(self, to: impl Into<SocketAddr>) -> Result<Feeler, ConnectionError>;
 }
 
 impl ConnectionExt for ConnectionBuilder {
     fn open_connection(
-        self,
+        mut self,
         to: impl Into<SocketAddr>,
     ) -> Result<(TcpStream, ConnectionContext), ConnectionError> {
         let socket_addr = to.into();
@@ -44,11 +48,26 @@ impl ConnectionExt for ConnectionBuilder {
     }
 
     fn start_handshake(
-        self,
+        mut self,
         mut tcp_stream: TcpStream,
     ) -> Result<(TcpStream, ConnectionContext), ConnectionError> {
         version_handshake_blocking!(tcp_stream, self)
     }
+
+    fn open_feeler(mut self, to: impl Into<SocketAddr>) -> Result<Feeler, ConnectionError> {
+        let socket_addr = to.into();
+        let mut tcp_stream = TcpStream::connect_timeout(&socket_addr, self.tcp_timeout)?;
+        let res: Result<(TcpStream, ConnectionContext), ConnectionError> =
+            version_handshake_blocking!(tcp_stream, self);
+        let (_, ctx) = res?;
+        let (_, wtx) = ctx.into_split();
+        let services = wtx.their_services;
+        let protocol_version = wtx.their_protocol_verison;
+        Ok(Feeler {
+            services,
+            protocol_version,
+        })
+    }
 }
 
 #[allow(clippy::result_large_err)]

p2p/src/tokio_ext.rs

@@ -14,7 +14,7 @@ use tokio::{
 
 use crate::{
     async_awaiter, interpret_first_message, make_version, version_handshake_async,
-    ConnectionBuilder, ConnectionContext, HandshakeError, Negotiation, ParseMessageError,
+    ConnectionBuilder, ConnectionContext, Feeler, HandshakeError, Negotiation, ParseMessageError,
     ReadContext, ReadHalf, WriteContext, WriteHalf,
 };
 
@@ -36,13 +36,17 @@ pub trait TokioConnectionExt {
         self,
         tcp_stream: TcpStream,
     ) -> Result<(TcpStream, ConnectionContext), Self::Error>;
+
+    ///
+    #[allow(async_fn_in_trait)]
+    async fn open_feeler(self, to: impl Into<SocketAddr>) -> Result<Feeler, Self::Error>;
 }
 
 impl TokioConnectionExt for ConnectionBuilder {
     type Error = ConnectionError;
 
     async fn open_connection(
-        self,
+        mut self,
         to: impl Into<SocketAddr>,
     ) -> Result<(TcpStream, ConnectionContext), Self::Error> {
         let socket_addr = to.into();
@@ -53,11 +57,27 @@ impl TokioConnectionExt for ConnectionBuilder {
     }
 
     async fn start_handshake(
-        self,
+        mut self,
         mut tcp_stream: TcpStream,
     ) -> Result<(TcpStream, ConnectionContext), Self::Error> {
         version_handshake_async!(tcp_stream, self)
     }
+
+    async fn open_feeler(mut self, to: impl Into<SocketAddr>) -> Result<Feeler, Self::Error> {
+        let socket_addr = to.into();
+        let timeout = tokio::time::timeout(self.tcp_timeout, TcpStream::connect(socket_addr)).await;
+        let mut tcp_stream =
+            timeout.map_err(|_| ConnectionError::Protocol(HandshakeError::Timeout))??;
+        let res: Result<(TcpStream, ConnectionContext), Self::Error> =
+            version_handshake_async!(tcp_stream, self);
+        let (_, ctx) = res?;
+        let services = ctx.write_ctx.their_services;
+        let protocol_version = ctx.write_ctx.their_protocol_verison;
+        Ok(Feeler {
+            services,
+            protocol_version,
+        })
+    }
 }
 
 async fn write_message<W: AsyncWriteExt + Send + Sync + Unpin>(