fix(mssql): handle multi-chunk packets

fixes #523

sqlx-core/src/io/buf_stream.rs

@@ -69,28 +69,18 @@ where
     where
         T: Decode<'de, C>,
     {
-        // zero-fills the space in the read buffer
-        self.rbuf.resize(cnt, 0);
+        T::decode_with(self.read_raw(cnt).await?.freeze(), context)
+    }
 
-        let mut read = 0;
-        while cnt > read {
-            // read in bytes from the stream into the read buffer starting
-            // from the offset we last read from
-            let n = self.stream.read(&mut self.rbuf[read..]).await?;
+    pub async fn read_raw(&mut self, cnt: usize) -> Result<BytesMut, Error> {
+        read_raw_into(&mut self.stream, &mut self.rbuf, cnt).await?;
+        let buf = self.rbuf.split_to(cnt);
 
-            if n == 0 {
-                // a zero read when we had space in the read buffer
-                // should be treated as an EOF
+        Ok(buf)
+    }
 
-                // and an unexpected EOF means the server told us to go away
-
-                return Err(io::Error::from(io::ErrorKind::ConnectionAborted).into());
-            }
-
-            read += n;
-        }
-
-        T::decode_with(self.rbuf.split_to(cnt).freeze(), context)
+    pub async fn read_raw_into(&mut self, buf: &mut BytesMut, cnt: usize) -> Result<(), Error> {
+        read_raw_into(&mut self.stream, buf, cnt).await
     }
 }
 
@@ -113,3 +103,34 @@ where
         &mut self.stream
     }
 }
+
+async fn read_raw_into<S: AsyncRead + Unpin>(
+    stream: &mut S,
+    buf: &mut BytesMut,
+    cnt: usize,
+) -> Result<(), Error> {
+    let offset = buf.len();
+
+    // zero-fills the space in the read buffer
+    buf.resize(offset + cnt, 0);
+
+    let mut read = offset;
+    while (offset + cnt) > read {
+        // read in bytes from the stream into the read buffer starting
+        // from the offset we last read from
+        let n = stream.read(&mut buf[read..]).await?;
+
+        if n == 0 {
+            // a zero read when we had space in the read buffer
+            // should be treated as an EOF
+
+            // and an unexpected EOF means the server told us to go away
+
+            return Err(io::Error::from(io::ErrorKind::ConnectionAborted).into());
+        }
+
+        read += n;
+    }
+
+    Ok(())
+}

sqlx-core/src/mssql/connection/stream.rs

@@ -1,6 +1,6 @@
 use std::ops::{Deref, DerefMut};
 
-use bytes::Bytes;
+use bytes::{Bytes, BytesMut};
 use sqlx_rt::TcpStream;
 
 use crate::error::Error;
@@ -92,9 +92,7 @@ impl MssqlStream {
     // receive the next packet from the database
     // blocks until a packet is available
     pub(super) async fn recv_packet(&mut self) -> Result<(PacketHeader, Bytes), Error> {
-        // TODO: Support packet chunking for large packet sizes
-
-        let header: PacketHeader = self.inner.read(8).await?;
+        let mut header: PacketHeader = self.inner.read(8).await?;
 
         // NOTE: From what I can tell, the response type from the server should ~always~
         //       be TabularResult. Here we expect that and die otherwise.
@@ -105,10 +103,21 @@ impl MssqlStream {
             ));
         }
 
-        let payload_len = (header.length - 8) as usize;
-        let payload: Bytes = self.inner.read(payload_len).await?;
+        let mut payload = BytesMut::new();
 
-        Ok((header, payload))
+        loop {
+            self.inner
+                .read_raw_into(&mut payload, (header.length - 8) as usize)
+                .await?;
+
+            if header.status.contains(Status::END_OF_MESSAGE) {
+                break;
+            }
+
+            header = self.inner.read(8).await?;
+        }
+
+        Ok((header, payload.freeze()))
     }
 
     // receive the next ~message~

tests/mssql/mssql.rs

@@ -112,6 +112,38 @@ CREATE TABLE #users (id INTEGER PRIMARY KEY);
     Ok(())
 }
 
+#[sqlx_macros::test]
+async fn it_can_return_1000_rows() -> anyhow::Result<()> {
+    let mut conn = new::<Mssql>().await?;
+
+    let _ = conn
+        .execute(
+            r#"
+CREATE TABLE #users (id INTEGER PRIMARY KEY);
+            "#,
+        )
+        .await?;
+
+    for index in 1..=1000_i32 {
+        let done = sqlx::query("INSERT INTO #users (id) VALUES (@p1)")
+            .bind(index * 2)
+            .execute(&mut conn)
+            .await?;
+
+        assert_eq!(done.rows_affected(), 1);
+    }
+
+    let sum: i32 = sqlx::query("SELECT id FROM #users")
+        .try_map(|row: MssqlRow| row.try_get::<i32, _>(0))
+        .fetch(&mut conn)
+        .try_fold(0_i32, |acc, x| async move { Ok(acc + x) })
+        .await?;
+
+    assert_eq!(sum, 1001000);
+
+    Ok(())
+}
+
 #[sqlx_macros::test]
 async fn it_selects_null() -> anyhow::Result<()> {
     let mut conn = new::<Mssql>().await?;