From a77301b5b013087e56506dcfdb48796275aaf3cc Mon Sep 17 00:00:00 2001
From: sundy-li <543950155@qq.com>
Date: Sat, 16 Oct 2021 12:08:59 +0800
Subject: [PATCH] Refuse connection when client did not use CLIENT_PROTOCOL_41

---
 src/lib.rs     | 14 ++++++++++++--
 src/writers.rs | 18 ++++++------------
 2 files changed, 18 insertions(+), 14 deletions(-)

diff --git a/src/lib.rs b/src/lib.rs
index c0e4323..6e3f265 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -400,6 +400,17 @@ impl<B: MysqlShim<W>, R: Read, W: Write> MysqlIntermediary<B, R, W> {
                 })?
                 .1;
 
+            if !handshake
+                .capabilities
+                .contains(CapabilityFlags::CLIENT_PROTOCOL_41)
+            {
+                let err = io::Error::new(
+                    io::ErrorKind::ConnectionAborted,
+                    "Required capability: CLIENT_PROTOCOL_41, please upgrade your MySQL client version",
+                );
+                return Err(err.into());
+            }
+
             self.client_capabilities = handshake.capabilities;
             let mut auth_response = handshake.auth_response.clone();
             let auth_plugin_expect = self.shim.auth_plugin_for_username(&handshake.username);
@@ -579,10 +590,9 @@ impl<B: MysqlShim<W>, R: Read, W: Write> MysqlIntermediary<B, R, W> {
                         coltype: myc::constants::ColumnType::MYSQL_TYPE_SHORT,
                         colflags: myc::constants::ColumnFlags::UNSIGNED_FLAG,
                     }];
-                    writers::write_column_definitions(
+                    writers::write_column_definitions_41(
                         cols,
                         &mut self.writer,
-                        true,
                         self.client_capabilities,
                     )?;
                 }
diff --git a/src/writers.rs b/src/writers.rs
index 5605398..d61c236 100644
--- a/src/writers.rs
+++ b/src/writers.rs
@@ -80,14 +80,15 @@ where
     w.write_u16::<LittleEndian>(0)?; // number of warnings
     w.end_packet()?;
 
-    write_column_definitions(pi, w, false, client_capabilities)?;
-    write_column_definitions(ci, w, false, client_capabilities)
+    write_column_definitions_41(pi, w, client_capabilities)?;
+    write_column_definitions_41(ci, w, client_capabilities)
 }
 
-pub(crate) fn write_column_definitions<'a, I, W>(
+/// works for Protocol::ColumnDefinition41 is set
+/// see: https://dev.mysql.com/doc/dev/mysql-server/latest/page_protocol_com_query_response_text_resultset_column_definition.html
+pub(crate) fn write_column_definitions_41<'a, I, W>(
     i: I,
     w: &mut PacketWriter<W>,
-    is_comm_field_list_response: bool,
     client_capabilities: CapabilityFlags,
 ) -> io::Result<()>
 where
@@ -112,13 +113,6 @@ where
         w.write_all(&[0x00])?; // decimals
         w.write_all(&[0x00, 0x00])?; // unused
 
-        if is_comm_field_list_response {
-            // We should write length encoded int with string size
-            // followed by string with some "default values" (possibly it's column defaults).
-            // But we just send NULL for simplicity
-            w.write_u8(0xfb)?;
-        }
-
         w.end_packet()?;
         empty = false;
     }
@@ -143,5 +137,5 @@ where
     let i = i.into_iter();
     w.write_lenenc_int(i.len() as u64)?;
     w.end_packet()?;
-    write_column_definitions(i, w, false, client_capabilities)
+    write_column_definitions_41(i, w, client_capabilities)
 }