feat: implement --recv-only

This option causes the sending side to not send any data and instead
immeditally send an EOF.  This can be useful when you are only
interested in sending data in one direction.

Closes #10

Author: eminence

src/main.rs

@@ -150,6 +150,10 @@ fn parse_alpn(alpn: &str) -> Result<Vec<u8>> {
 
 #[derive(Parser, Debug)]
 pub struct ListenArgs {
+    /// Immediately close our sending side, indicating that we will not transmit any data
+    #[clap(long)]
+    pub recv_only: bool,
+
     #[clap(flatten)]
     pub common: CommonArgs,
 }
@@ -183,6 +187,10 @@ pub struct ConnectArgs {
     /// The node to connect to
     pub ticket: NodeTicket,
 
+    /// Immediately close our sending side, indicating that we will not transmit any data
+    #[clap(long)]
+    pub recv_only: bool,
+
     #[clap(flatten)]
     pub common: CommonArgs,
 }
@@ -381,8 +389,13 @@ async fn listen_stdio(args: ListenArgs) -> Result<()> {
             r.read_exact(&mut buf).await.e()?;
             snafu::ensure_whatever!(buf == dumbpipe::HANDSHAKE, "invalid handshake");
         }
-        tracing::info!("forwarding stdin/stdout to {}", remote_node_id);
-        forward_bidi(tokio::io::stdin(), tokio::io::stdout(), r, s).await?;
+        if args.recv_only {
+            tracing::info!("forwarding stdout to {} (ignoring stdin)", remote_node_id);
+            forward_bidi(tokio::io::empty(), tokio::io::stdout(), r, s).await?;
+        } else {
+            tracing::info!("forwarding stdin/stdout to {}", remote_node_id);
+            forward_bidi(tokio::io::stdin(), tokio::io::stdout(), r, s).await?;
+        }
         // stop accepting connections after the first successful one
         break;
     }
@@ -407,8 +420,13 @@ async fn connect_stdio(args: ConnectArgs) -> Result<()> {
         // on stdin, so just write a handshake.
         s.write_all(&dumbpipe::HANDSHAKE).await.e()?;
     }
-    tracing::info!("forwarding stdin/stdout to {}", remote_node_id);
-    forward_bidi(tokio::io::stdin(), tokio::io::stdout(), r, s).await?;
+    if args.recv_only {
+        tracing::info!("forwarding stdout to {} (ignoring stdin)", remote_node_id);
+        forward_bidi(tokio::io::empty(), tokio::io::stdout(), r, s).await?;
+    } else {
+        tracing::info!("forwarding stdin/stdout to {}", remote_node_id);
+        forward_bidi(tokio::io::stdin(), tokio::io::stdout(), r, s).await?;
+    }
     tokio::io::stdout().flush().await.e()?;
     Ok(())
 }