Output diagnostic for SSL_CTX_set_msg_callback use

This changes the behaviour from adding an error to the error stack,
to quietly logging.

Author: ctz

MATRIX.md

@@ -161,7 +161,7 @@
 | `SSL_CTX_set_info_callback`  |  | :white_check_mark: | :white_check_mark: | :white_check_mark: |
 | `SSL_CTX_set_keylog_callback`  | :white_check_mark: | :white_check_mark: | :white_check_mark: | :exclamation: [^stub] |
 | `SSL_CTX_set_max_early_data`  |  | :white_check_mark: |  | :white_check_mark: |
-| `SSL_CTX_set_msg_callback`  | :white_check_mark: |  | :white_check_mark: | :exclamation: [^stub] |
+| `SSL_CTX_set_msg_callback`  | :white_check_mark: |  | :white_check_mark: | :white_check_mark: |
 | `SSL_CTX_set_next_proto_select_cb` [^nextprotoneg] | :white_check_mark: |  | :white_check_mark: | :exclamation: [^stub] |
 | `SSL_CTX_set_next_protos_advertised_cb` [^nextprotoneg] |  | :white_check_mark: | :white_check_mark: | :exclamation: [^stub] |
 | `SSL_CTX_set_not_resumable_session_callback`  |  |  |  |  |
@@ -442,7 +442,7 @@
 | `SSL_set_hostflags`  |  |  |  |  |
 | `SSL_set_info_callback`  |  |  |  | :white_check_mark: |
 | `SSL_set_max_early_data`  |  | :white_check_mark: | :white_check_mark: | :white_check_mark: |
-| `SSL_set_msg_callback`  |  | :white_check_mark: | :white_check_mark: | :exclamation: [^stub] |
+| `SSL_set_msg_callback`  |  | :white_check_mark: | :white_check_mark: | :white_check_mark: |
 | `SSL_set_not_resumable_session_callback`  |  |  |  |  |
 | `SSL_set_num_tickets`  |  |  |  | :white_check_mark: |
 | `SSL_set_options`  |  | :white_check_mark: |  | :white_check_mark: |

src/entry.rs

@@ -712,6 +712,30 @@ entry! {
 pub type SSL_CTX_info_callback_func =
     Option<unsafe extern "C" fn(ssl: *mut SSL, type_: c_int, val: c_int)>;
 
+entry! {
+    pub fn _SSL_CTX_set_msg_callback(_ctx: *mut SSL_CTX, _cb: SSL_CTX_msg_cb_func) {
+        log::warn!("SSL_CTX_set_msg_callback not implemented; callback will not be called");
+    }
+}
+
+entry! {
+    pub fn _SSL_set_msg_callback(_ssl: *mut SSL, _cb: SSL_CTX_msg_cb_func) {
+        log::warn!("SSL_set_msg_callback not implemented; callback will not be called");
+    }
+}
+
+pub type SSL_CTX_msg_cb_func = Option<
+    unsafe extern "C" fn(
+        write_p: c_int,
+        version: c_int,
+        content_type: c_int,
+        buf: *const c_void,
+        len: usize,
+        ssl: *mut SSL,
+        arg: *mut c_void,
+    ),
+>;
+
 entry! {
     pub fn _SSL_CTX_get_max_early_data(ctx: *const SSL_CTX) -> u32 {
         try_clone_arc!(ctx).get().get_max_early_data()
@@ -2320,28 +2344,6 @@ entry_stub! {
     ) -> c_int;
 }
 
-// no individual message logging
-
-entry_stub! {
-    pub fn _SSL_CTX_set_msg_callback(_ctx: *mut SSL_CTX, _cb: SSL_CTX_msg_cb_func);
-}
-
-entry_stub! {
-    pub fn _SSL_set_msg_callback(_ssl: *mut SSL, _cb: SSL_CTX_msg_cb_func);
-}
-
-pub type SSL_CTX_msg_cb_func = Option<
-    unsafe extern "C" fn(
-        write_p: c_int,
-        version: c_int,
-        content_type: c_int,
-        buf: *const c_void,
-        len: usize,
-        ssl: *mut SSL,
-        arg: *mut c_void,
-    ),
->;
-
 // no NPN (obsolete precursor to ALPN)
 
 entry_stub! {