IRC: split on word if possible, + flush

channels/irc/src/main.rs

@@ -139,7 +139,12 @@ impl AsyncWriter for TlsWriter {
         line: &str,
     ) -> std::pin::Pin<Box<dyn std::future::Future<Output = io::Result<()>> + '_>> {
         let data = format!("{line}\r\n");
-        Box::pin(async move { self.inner.write_all(data.as_bytes()).await })
+        Box::pin(async move {
+            self.inner.write_all(data.as_bytes()).await?;
+            // Unconfirmed reports that some servers require
+            // multiple lines to be in separate packets
+            self.inner.flush().await
+        })
     }
 }
 
@@ -153,7 +158,12 @@ impl AsyncWriter for PlainWriter {
         line: &str,
     ) -> std::pin::Pin<Box<dyn std::future::Future<Output = io::Result<()>> + '_>> {
         let data = format!("{line}\r\n");
-        Box::pin(async move { self.inner.write_all(data.as_bytes()).await })
+        Box::pin(async move {
+            self.inner.write_all(data.as_bytes()).await?;
+            // Unconfirmed reports that some servers require
+            // multiple lines to be in separate packets
+            self.inner.flush().await
+        })
     }
 }
 
@@ -225,6 +235,8 @@ impl State {
     }
 
     async fn send_privmsg(&mut self, target: &str, msg: &str) -> io::Result<()> {
+        // Send PRIVMSG, which is used for both private and channel messages.
+        // Splits into multiple fragments if necessary.
         // IRC max line = 512 bytes including CRLF. The server prepends
         // our prefix when relaying: ":nick!~user@host PRIVMSG target :msg\r\n"
         // User is often ~nick (nick_len + 1). Host is up to 63 bytes.
@@ -246,7 +258,11 @@ impl State {
                 // Find last char boundary at or before max_msg
                 let mut i = max_msg;
                 while i > 0 && !remaining.is_char_boundary(i) { i -= 1; }
-                if i == 0 { max_msg } else { i }
+                // To avoid splitting mid-word, see if there was a space recently
+                let mut j = i;
+                while j > 0 && j > i-10 && remaining.as_bytes()[j] != b' ' { j -= 1; }
+                if remaining.as_bytes()[j] == b' ' { j }
+                else if i == 0 { max_msg } else { i }
             };
             let (chunk, rest) = remaining.split_at(split_at);
             self.send_raw(&format!("PRIVMSG {target} :{chunk}")).await?;