Add nghttp2_error_callback2

nghttp2_error_callback2 is an extended version of the existing
nghttp2_error_callback by adding error code parameter.  This
deprecates nghttp2_error_callback.

doc/Makefile.am

@@ -81,6 +81,7 @@ APIDOCS= \
 	nghttp2_session_callbacks_set_before_frame_send_callback.rst \
 	nghttp2_session_callbacks_set_data_source_read_length_callback.rst \
 	nghttp2_session_callbacks_set_error_callback.rst \
+	nghttp2_session_callbacks_set_error_callback2.rst \
 	nghttp2_session_callbacks_set_on_begin_frame_callback.rst \
 	nghttp2_session_callbacks_set_on_begin_headers_callback.rst \
 	nghttp2_session_callbacks_set_on_data_chunk_recv_callback.rst \

lib/includes/nghttp2/nghttp2.h

@@ -387,6 +387,11 @@ typedef enum {
    * Indicates that a processing was canceled.
    */
   NGHTTP2_ERR_CANCEL = -535,
+  /**
+   * When a local endpoint expects to receive SETTINGS frame, it
+   * receives an other type of frame.
+   */
+  NGHTTP2_ERR_SETTINGS_EXPECTED = -536,
   /**
    * The errors < :enum:`NGHTTP2_ERR_FATAL` mean that the library is
    * under unexpected condition and processing was terminated (e.g.,
@@ -1987,6 +1992,9 @@ typedef ssize_t (*nghttp2_pack_extension_callback)(nghttp2_session *session,
  * of length |len|.  |len| does not include the sentinel NULL
  * character.
  *
+ * This function is deprecated.  The new application should use
+ * :type:`nghttp2_error_callback2`.
+ *
  * The format of error message may change between nghttp2 library
  * versions.  The application should not depend on the particular
  * format.
@@ -2003,6 +2011,33 @@ typedef ssize_t (*nghttp2_pack_extension_callback)(nghttp2_session *session,
 typedef int (*nghttp2_error_callback)(nghttp2_session *session, const char *msg,
                                       size_t len, void *user_data);
 
+/**
+ * @functypedef
+ *
+ * Callback function invoked when library provides the error code, and
+ * message.  This callback is solely for debugging purpose.
+ * |lib_error_code| is one of error code defined in
+ * :enum:`nghttp2_error`.  The |msg| is typically NULL-terminated
+ * string of length |len|, and intended for human consumption.  |len|
+ * does not include the sentinel NULL character.
+ *
+ * The format of error message may change between nghttp2 library
+ * versions.  The application should not depend on the particular
+ * format.
+ *
+ * Normally, application should return 0 from this callback.  If fatal
+ * error occurred while doing something in this callback, application
+ * should return :enum:`NGHTTP2_ERR_CALLBACK_FAILURE`.  In this case,
+ * library will return immediately with return value
+ * :enum:`NGHTTP2_ERR_CALLBACK_FAILURE`.  Currently, if nonzero value
+ * is returned from this callback, they are treated as
+ * :enum:`NGHTTP2_ERR_CALLBACK_FAILURE`, but application should not
+ * rely on this details.
+ */
+typedef int (*nghttp2_error_callback2)(nghttp2_session *session,
+                                       int lib_error_code, const char *msg,
+                                       size_t len, void *user_data);
+
 struct nghttp2_session_callbacks;
 
 /**
@@ -2267,10 +2302,30 @@ nghttp2_session_callbacks_set_on_extension_chunk_recv_callback(
  *
  * Sets callback function invoked when library tells error message to
  * the application.
+ *
+ * This function is deprecated.  The new application should use
+ * `nghttp2_session_callbacks_set_error_callback2()`.
+ *
+ * If both :type:`nghttp2_error_callback` and
+ * :type:`nghttp2_error_callback2` are set, the latter takes
+ * precedence.
  */
 NGHTTP2_EXTERN void nghttp2_session_callbacks_set_error_callback(
     nghttp2_session_callbacks *cbs, nghttp2_error_callback error_callback);
 
+/**
+ * @function
+ *
+ * Sets callback function invoked when library tells error code, and
+ * message to the application.
+ *
+ * If both :type:`nghttp2_error_callback` and
+ * :type:`nghttp2_error_callback2` are set, the latter takes
+ * precedence.
+ */
+NGHTTP2_EXTERN void nghttp2_session_callbacks_set_error_callback2(
+    nghttp2_session_callbacks *cbs, nghttp2_error_callback2 error_callback2);
+
 /**
  * @functypedef
  *

lib/nghttp2_callbacks.c

@@ -168,3 +168,8 @@ void nghttp2_session_callbacks_set_error_callback(
     nghttp2_session_callbacks *cbs, nghttp2_error_callback error_callback) {
   cbs->error_callback = error_callback;
 }
+
+void nghttp2_session_callbacks_set_error_callback2(
+    nghttp2_session_callbacks *cbs, nghttp2_error_callback2 error_callback2) {
+  cbs->error_callback2 = error_callback2;
+}

lib/nghttp2_callbacks.h

@@ -119,6 +119,7 @@ struct nghttp2_session_callbacks {
   nghttp2_unpack_extension_callback unpack_extension_callback;
   nghttp2_on_extension_chunk_recv_callback on_extension_chunk_recv_callback;
   nghttp2_error_callback error_callback;
+  nghttp2_error_callback2 error_callback2;
 };
 
 #endif /* NGHTTP2_CALLBACKS_H */

lib/nghttp2_helper.c

@@ -322,6 +322,9 @@ const char *nghttp2_strerror(int error_code) {
     return "Internal error";
   case NGHTTP2_ERR_CANCEL:
     return "Cancel";
+  case NGHTTP2_ERR_SETTINGS_EXPECTED:
+    return "When a local endpoint expects to receive SETTINGS frame, it "
+           "receives an other type of frame";
   case NGHTTP2_ERR_NOMEM:
     return "Out of memory";
   case NGHTTP2_ERR_CALLBACK_FAILURE:

lib/nghttp2_session.c

@@ -148,14 +148,16 @@ static int check_ext_type_set(const uint8_t *ext_types, uint8_t type) {
 }
 
 static int session_call_error_callback(nghttp2_session *session,
-                                       const char *fmt, ...) {
+                                       int lib_error_code, const char *fmt,
+                                       ...) {
   size_t bufsize;
   va_list ap;
   char *buf;
   int rv;
   nghttp2_mem *mem;
 
-  if (!session->callbacks.error_callback) {
+  if (!session->callbacks.error_callback &&
+      !session->callbacks.error_callback2) {
     return 0;
   }
 
@@ -189,8 +191,13 @@ static int session_call_error_callback(nghttp2_session *session,
     return 0;
   }
 
-  rv = session->callbacks.error_callback(session, buf, (size_t)rv,
-                                         session->user_data);
+  if (session->callbacks.error_callback2) {
+    rv = session->callbacks.error_callback2(session, lib_error_code, buf,
+                                            (size_t)rv, session->user_data);
+  } else {
+    rv = session->callbacks.error_callback(session, buf, (size_t)rv,
+                                           session->user_data);
+  }
 
   nghttp2_mem_free(mem, buf);
 
@@ -3608,7 +3615,7 @@ static int inflate_header_block(nghttp2_session *session, nghttp2_frame *frame,
                    nv.name->base, (int)nv.value->len, nv.value->base);
 
             rv2 = session_call_error_callback(
-                session,
+                session, NGHTTP2_ERR_HTTP_HEADER,
                 "Ignoring received invalid HTTP header field: frame type: "
                 "%u, stream: %d, name: [%.*s], value: [%.*s]",
                 frame->hd.type, frame->hd.stream_id, (int)nv.name->len,
@@ -3626,8 +3633,9 @@ static int inflate_header_block(nghttp2_session *session, nghttp2_frame *frame,
                  nv.name->base, (int)nv.value->len, nv.value->base);
 
           rv = session_call_error_callback(
-              session, "Invalid HTTP header field was received: frame type: "
-                       "%u, stream: %d, name: [%.*s], value: [%.*s]",
+              session, NGHTTP2_ERR_HTTP_HEADER,
+              "Invalid HTTP header field was received: frame type: "
+              "%u, stream: %d, name: [%.*s], value: [%.*s]",
               frame->hd.type, frame->hd.stream_id, (int)nv.name->len,
               nv.name->base, (int)nv.value->len, nv.value->base);
 
@@ -5345,9 +5353,10 @@ ssize_t nghttp2_session_mem_recv(nghttp2_session *session, const uint8_t *in,
         iframe->state = NGHTTP2_IB_IGN_ALL;
 
         rv = session_call_error_callback(
-            session, "Remote peer returned unexpected data while we expected "
-                     "SETTINGS frame.  Perhaps, peer does not support HTTP/2 "
-                     "properly.");
+            session, NGHTTP2_ERR_SETTINGS_EXPECTED,
+            "Remote peer returned unexpected data while we expected "
+            "SETTINGS frame.  Perhaps, peer does not support HTTP/2 "
+            "properly.");
 
         if (nghttp2_is_fatal(rv)) {
           return rv;