Implement sending splits

[mt_rudp.git] / src / send.rs

diff --git a/src/send.rs b/src/send.rs
index 90bbe2d83e0b56dd0ef1b58e41297a27a4d0600a..3681eb9837292e8ba50316b327498d5584a7eb33 100644 (file)
--- a/src/send.rs
+++ b/src/send.rs
@@ -1,6 +1,7 @@
 use super::*;
 use byteorder::{BigEndian, WriteBytesExt};
 use std::{
+    borrow::Cow,
     collections::HashMap,
     io::{self, Write},
     sync::Arc,
@@ -20,6 +21,7 @@ pub(crate) struct AckWait {
 pub(crate) struct Chan {
     pub(crate) acks: HashMap<u16, AckWait>,
     pub(crate) seqnum: u16,
+    pub(crate) splits_seqnum: u16,
 }
 
 #[derive(Debug)]
@@ -42,17 +44,58 @@ impl<S: UdpSender> Sender<S> {
                 Mutex::new(Chan {
                     acks: HashMap::new(),
                     seqnum: INIT_SEQNUM,
+                    splits_seqnum: INIT_SEQNUM,
                 })
             }),
         })
     }
 
     pub async fn send_rudp(&self, pkt: Pkt<'_>) -> io::Result<Ack> {
-        self.send_rudp_type(PktType::Orig, pkt).await // TODO: splits
+        if pkt.size() > UDP_PKT_SIZE {
+            let chunks = pkt
+                .data
+                .chunks(UDP_PKT_SIZE - (pkt.header_size() + 1 + 2 + 2 + 2));
+            let num_chunks: u16 = chunks
+                .len()
+                .try_into()
+                .map_err(|_| io::Error::new(io::ErrorKind::Other, "too many chunks"))?;
+
+            let seqnum = {
+                let mut chan = self.chans[pkt.chan as usize].lock().await;
+                let sn = chan.splits_seqnum;
+                chan.splits_seqnum = chan.splits_seqnum.overflowing_add(1).0;
+
+                sn
+            };
+
+            for (i, ch) in chunks.enumerate() {
+                self.send_rudp_type(
+                    PktType::Orig,
+                    Some((seqnum, num_chunks, i as u16)),
+                    Pkt {
+                        unrel: pkt.unrel,
+                        chan: pkt.chan,
+                        data: Cow::Borrowed(ch),
+                    },
+                )
+                .await?;
+            }
+
+            Ok(None) // TODO: ack
+        } else {
+            self.send_rudp_type(PktType::Orig, None, pkt).await
+        }
     }
 
-    pub async fn send_rudp_type(&self, tp: PktType, pkt: Pkt<'_>) -> io::Result<Ack> {
-        let mut buf = Vec::with_capacity(4 + 2 + 1 + 1 + 2 + 1 + pkt.data.len());
+    pub async fn send_rudp_type(
+        &self,
+        tp: PktType,
+        chunk: Option<(u16, u16, u16)>,
+        pkt: Pkt<'_>,
+    ) -> io::Result<Ack> {
+        let mut buf =
+            Vec::with_capacity(pkt.size() + if chunk.is_some() { 1 + 2 + 2 + 2 } else { 0 });
+
         buf.write_u32::<BigEndian>(PROTO_ID)?;
         buf.write_u16::<BigEndian>(*self.remote_id.read().await)?;
         buf.write_u8(pkt.chan)?;
@@ -65,7 +108,15 @@ impl<S: UdpSender> Sender<S> {
             buf.write_u16::<BigEndian>(seqnum)?;
         }
 
-        buf.write_u8(tp as u8)?;
+        if let Some((seqnum, count, index)) = chunk {
+            buf.write_u8(PktType::Split as u8)?;
+            buf.write_u16::<BigEndian>(seqnum)?;
+            buf.write_u16::<BigEndian>(count)?;
+            buf.write_u16::<BigEndian>(index)?;
+        } else {
+            buf.write_u8(tp as u8)?;
+        }
+
         buf.write_all(pkt.data.as_ref())?;
 
         self.send_udp(&buf).await?;
@@ -91,7 +142,10 @@ impl<S: UdpSender> Sender<S> {
 
     pub async fn send_udp(&self, data: &[u8]) -> io::Result<()> {
         if data.len() > UDP_PKT_SIZE {
-            panic!("splitting packets is not implemented yet");
+            panic!(
+                "attempted to send a packet with len {} > {UDP_PKT_SIZE}",
+                data.len()
+            );
         }
 
         self.udp.send(data).await