From c0ec9b4bcd6f4218a6285762e387b2e86be157da Mon Sep 17 00:00:00 2001
From: Lorenzo Rizzotti <Lore.rizzotti@gmail.com>
Date: Thu, 27 Nov 2025 10:06:08 -0800
Subject: [PATCH] Add vectored IO to avoid userspace vec copy (#38)

---
 idevice/src/lib.rs                        | 69 +++++++++++++++++++++++
 idevice/src/services/core_device_proxy.rs | 16 +++++-
 2 files changed, 84 insertions(+), 1 deletion(-)

diff --git a/idevice/src/lib.rs b/idevice/src/lib.rs
index 2fab32e..cacd0de 100644
--- a/idevice/src/lib.rs
+++ b/idevice/src/lib.rs
@@ -304,6 +304,75 @@ impl Idevice {
         self.send_raw_with_progress(message, |_| async {}, ()).await
     }
 
+    /// Sends raw binary data via vectored I/O
+    ///
+    /// # Arguments
+    /// * `bufs` - The buffers to send
+    ///
+    /// # Errors
+    /// Returns `IdeviceError` if transmission fails
+    pub async fn send_raw_vectored(
+        &mut self,
+        bufs: &[std::io::IoSlice<'_>],
+    ) -> Result<(), IdeviceError> {
+        if let Some(socket) = &mut self.socket {
+            let mut curr_idx = 0;
+            let mut curr_offset = 0;
+
+            while curr_idx < bufs.len() {
+                let mut iovec = Vec::new();
+                let mut accumulated_len = 0;
+                let max_chunk = 1024 * 64;
+
+                // Add partial first slice
+                let first_avail = bufs[curr_idx].len() - curr_offset;
+                let to_take_first = std::cmp::min(first_avail, max_chunk);
+                iovec.push(std::io::IoSlice::new(
+                    &bufs[curr_idx][curr_offset..curr_offset + to_take_first],
+                ));
+                accumulated_len += to_take_first;
+
+                // Add others up to max_chunk
+                let mut temp_idx = curr_idx + 1;
+                while temp_idx < bufs.len() && accumulated_len < max_chunk {
+                    let needed = max_chunk - accumulated_len;
+                    let avail = bufs[temp_idx].len();
+                    let take = std::cmp::min(avail, needed);
+                    iovec.push(std::io::IoSlice::new(&bufs[temp_idx][..take]));
+                    accumulated_len += take;
+                    temp_idx += 1;
+                }
+
+                let n = socket.write_vectored(&iovec).await?;
+                if n == 0 {
+                    return Err(io::Error::new(
+                        io::ErrorKind::WriteZero,
+                        "failed to write whole buffer",
+                    )
+                    .into());
+                }
+
+                // Advance cursor by n
+                let mut advanced = n;
+                while advanced > 0 && curr_idx < bufs.len() {
+                    let available = bufs[curr_idx].len() - curr_offset;
+                    if advanced < available {
+                        curr_offset += advanced;
+                        advanced = 0;
+                    } else {
+                        advanced -= available;
+                        curr_idx += 1;
+                        curr_offset = 0;
+                    }
+                }
+            }
+            socket.flush().await?;
+            Ok(())
+        } else {
+            Err(IdeviceError::NoEstablishedConnection)
+        }
+    }
+
     /// Sends raw binary data with progress callbacks
     ///
     /// # Arguments
diff --git a/idevice/src/services/core_device_proxy.rs b/idevice/src/services/core_device_proxy.rs
index a08b0ff..6783d50 100644
--- a/idevice/src/services/core_device_proxy.rs
+++ b/idevice/src/services/core_device_proxy.rs
@@ -17,7 +17,7 @@ use crate::{Idevice, IdeviceError, IdeviceService, obf};
 
 use byteorder::{BigEndian, WriteBytesExt};
 use serde::{Deserialize, Serialize};
-use std::io::{self, Write};
+use std::io::{self, IoSlice, Write};
 
 /// A representation of a CDTunnel packet used in the CoreDeviceProxy protocol.
 #[derive(Debug, PartialEq)]
@@ -195,6 +195,20 @@ impl CoreDeviceProxy {
         Ok(())
     }
 
+    /// Sends a raw data packet through the tunnel using vectored I/O.
+    ///
+    /// # Arguments
+    ///
+    /// * `bufs` - The buffers to send.
+    ///
+    /// # Returns
+    ///
+    /// * `Ok(())` if the data is successfully sent.
+    /// * `Err(IdeviceError)` if sending fails.
+    pub async fn send_vectored(&mut self, bufs: &[IoSlice<'_>]) -> Result<(), IdeviceError> {
+        self.idevice.send_raw_vectored(bufs).await
+    }
+
     /// Receives up to `mtu` bytes from the tunnel.
     ///
     /// # Returns