Apply initiated SETTINGS changes on reception of ACK

lib/includes/nghttp2/nghttp2.h

@@ -127,6 +127,13 @@ typedef struct {
  */
 #define NGHTTP2_INITIAL_CONNECTION_WINDOW_SIZE ((1 << 16) - 1)
 
+/**
+ * @macro
+ *
+ * The maximum header table size.
+ */
+#define NGHTTP2_MAX_HEADER_TABLE_SIZE (1 << 16)
+
 /**
  * @macro
  *
@@ -262,6 +269,11 @@ typedef enum {
    * Callback was paused by the application
    */
   NGHTTP2_ERR_PAUSE = -526,
+  /**
+   * There are too many in-flight SETTING frame and no more
+   * transmission of SETTINGS is allowed.
+   */
+  NGHTTP2_ERR_TOO_MANY_INFLIGHT_SETTINGS = -527,
   /**
    * The errors < :enum:`NGHTTP2_ERR_FATAL` mean that the library is
    * under unexpected condition and cannot process any further data
@@ -379,9 +391,9 @@ typedef enum {
    */
   NGHTTP2_FLAG_END_PUSH_PROMISE = 0x4,
   /**
-   * The PONG flag.
+   * The ACK flag.
    */
-  NGHTTP2_FLAG_PONG = 0x1
+  NGHTTP2_FLAG_ACK = 0x1
 } nghttp2_flag;
 
 /**

lib/nghttp2_frame.c

@@ -106,12 +106,11 @@ void nghttp2_frame_rst_stream_free(nghttp2_rst_stream *frame)
 {}
 
 
-void nghttp2_frame_settings_init(nghttp2_settings *frame,
+void nghttp2_frame_settings_init(nghttp2_settings *frame, uint8_t flags,
                                  nghttp2_settings_entry *iv, size_t niv)
 {
   memset(frame, 0, sizeof(nghttp2_settings));
-  nghttp2_frame_set_hd(&frame->hd, niv*8, NGHTTP2_SETTINGS, NGHTTP2_FLAG_NONE,
+  nghttp2_frame_set_hd(&frame->hd, niv*8, NGHTTP2_SETTINGS, flags, 0);
-                       0);
   frame->niv = niv;
   frame->iv = iv;
 }

lib/nghttp2_frame.h

@@ -470,7 +470,7 @@ void nghttp2_frame_push_promise_free(nghttp2_push_promise *frame);
  * ownership of |iv|, so caller must not free it. The |flags| are
  * bitwise-OR of one or more of nghttp2_settings_flag.
  */
-void nghttp2_frame_settings_init(nghttp2_settings *frame,
+void nghttp2_frame_settings_init(nghttp2_settings *frame, uint8_t flags,
                                  nghttp2_settings_entry *iv, size_t niv);
 
 void nghttp2_frame_settings_free(nghttp2_settings *frame);

lib/nghttp2_session.c

@@ -191,6 +191,8 @@ static int nghttp2_session_new(nghttp2_session **session_ptr,
   (*session_ptr)->goaway_flags = NGHTTP2_GOAWAY_NONE;
   (*session_ptr)->last_stream_id = 0;
 
+  (*session_ptr)->inflight_niv = -1;
+
   if(server) {
     (*session_ptr)->server = 1;
     side_deflate = NGHTTP2_HD_SIDE_RESPONSE;
@@ -341,6 +343,7 @@ void nghttp2_session_del(nghttp2_session *session)
   if(session == NULL) {
     return;
   }
+  free(session->inflight_iv);
   nghttp2_inbound_frame_reset(session);
   nghttp2_map_each_free(&session->streams, nghttp2_free_streams, NULL);
   nghttp2_session_ob_pq_free(&session->ob_pq);
@@ -923,6 +926,27 @@ static int nghttp2_session_predicate_window_update_send
   return 0;
 }
 
+/*
+ * This function checks SETTINGS can be sent at this time.
+ *
+ * This function returns 0 if it succeeds, or one of the following
+ * negative error codes:
+ *
+ * NGHTTP2_ERR_TOO_MANY_INFLIGHT_SETTINGS
+ *     There is already another in-flight SETTINGS.  Note that the
+ *     current implementation only allows 1 in-flight SETTINGS frame
+ *     without ACK flag set.
+ */
+static int nghttp2_session_predicate_settings_send(nghttp2_session *session,
+                                                   nghttp2_frame *frame)
+{
+  if((frame->hd.flags & NGHTTP2_FLAG_ACK) == 0 &&
+     session->inflight_niv != -1) {
+    return NGHTTP2_ERR_TOO_MANY_INFLIGHT_SETTINGS;
+  }
+  return 0;
+}
+
 /*
  * Returns the maximum length of next data read. If the
  * connection-level and/or stream-wise flow control are enabled, the
@@ -1102,7 +1126,12 @@ static ssize_t nghttp2_session_prep_frame(nghttp2_session *session,
         return framebuflen;
       }
       break;
-    case NGHTTP2_SETTINGS:
+    case NGHTTP2_SETTINGS: {
+      int r;
+      r = nghttp2_session_predicate_settings_send(session, frame);
+      if(r != 0) {
+        return r;
+      }
       framebuflen = nghttp2_frame_pack_settings(&session->aob.framebuf,
                                                 &session->aob.framebufmax,
                                                 &frame->settings);
@@ -1110,6 +1139,7 @@ static ssize_t nghttp2_session_prep_frame(nghttp2_session *session,
         return framebuflen;
       }
       break;
+    }
     case NGHTTP2_PUSH_PROMISE: {
       int r;
       nghttp2_stream *stream;
@@ -1412,9 +1442,29 @@ static int nghttp2_session_after_frame_sent(nghttp2_session *session)
       }
       r = 0;
       break;
-    case NGHTTP2_SETTINGS:
+    case NGHTTP2_SETTINGS: {
-      /* nothing to do */
+      size_t i;
+      if(frame->hd.flags & NGHTTP2_FLAG_ACK) {
+        break;
+      }
+      /* Only update max concurrent stream here. Applying it without
+         ACK is safe because we can respond to the exceeding streams
+         with REFUSED_STREAM and client will retry later. */
+      for(i = frame->settings.niv; i > 0; --i) {
+        if(frame->settings.iv[i - 1].settings_id ==
+           NGHTTP2_SETTINGS_MAX_CONCURRENT_STREAMS) {
+          session->local_settings[NGHTTP2_SETTINGS_MAX_CONCURRENT_STREAMS] =
+            frame->settings.iv[i - 1].value;
+          break;
+        }
+      }
+      assert(session->inflight_niv == -1);
+      session->inflight_iv = frame->settings.iv;
+      session->inflight_niv = frame->settings.niv;
+      frame->settings.iv = NULL;
+      frame->settings.niv = 0;
       break;
+    }
     case NGHTTP2_PUSH_PROMISE:
       /* nothing to do */
       break;
@@ -2187,6 +2237,10 @@ static int nghttp2_disable_remote_flow_control_func(nghttp2_map_entry *entry,
 /*
  * Disable remote side connection-level flow control and stream-level
  * flow control of existing streams.
+ *
+ * This function returns 0 if it succeeds, or one of negative error codes.
+ *
+ * The error code is always FATAL.
  */
 static int nghttp2_session_disable_remote_flow_control
 (nghttp2_session *session)
@@ -2219,6 +2273,20 @@ static void nghttp2_session_disable_local_flow_control
   assert(rv == 0);
 }
 
+/*
+ * Apply SETTINGS values |iv| having |niv| elements to the local
+ * settings. SETTINGS_MAX_CONCURRENT_STREAMS is not applied here
+ * because it has been already applied on transmission of SETTINGS
+ * frame.
+ *
+ * This function returns 0 if it succeeds, or one of the following
+ * negative error codes:
+ *
+ * NGHTTP2_ERR_HEADER_COMP
+ *     The header table size is out of range
+ * NGHTTP2_ERR_NOMEM
+ *     Out of memory
+ */
 int nghttp2_session_update_local_settings(nghttp2_session *session,
                                           nghttp2_settings_entry *iv,
                                           size_t niv)
@@ -2229,12 +2297,32 @@ int nghttp2_session_update_local_settings(nghttp2_session *session,
     session->local_settings[NGHTTP2_SETTINGS_FLOW_CONTROL_OPTIONS];
   uint8_t new_flow_control = old_flow_control;
   int32_t new_initial_window_size = -1;
+  int32_t header_table_size = -1;
+  uint8_t header_table_size_seen = 0;
   /* Use the value last seen. */
   for(i = 0; i < niv; ++i) {
-    if(iv[i].settings_id == NGHTTP2_SETTINGS_INITIAL_WINDOW_SIZE) {
+    switch(iv[i].settings_id) {
+    case NGHTTP2_SETTINGS_HEADER_TABLE_SIZE:
+      header_table_size_seen = 1;
+      header_table_size = iv[i].value;
+      break;
+    case NGHTTP2_SETTINGS_INITIAL_WINDOW_SIZE:
       new_initial_window_size = iv[i].value;
-    } else if(iv[i].settings_id == NGHTTP2_SETTINGS_FLOW_CONTROL_OPTIONS) {
+      break;
+    case  NGHTTP2_SETTINGS_FLOW_CONTROL_OPTIONS:
       new_flow_control = iv[i].value;
+      break;
+    }
+  }
+  if(header_table_size_seen) {
+    if(header_table_size < 0 ||
+       header_table_size > NGHTTP2_MAX_HEADER_TABLE_SIZE) {
+      return NGHTTP2_ERR_HEADER_COMP;
+    }
+    rv = nghttp2_hd_change_table_size(&session->hd_inflater,
+                                      header_table_size);
+    if(rv != 0) {
+      return rv;
     }
   }
   if(!old_flow_control && !new_flow_control && new_initial_window_size != -1) {
@@ -2247,7 +2335,10 @@ int nghttp2_session_update_local_settings(nghttp2_session *session,
     }
   }
   for(i = 0; i < niv; ++i) {
-    if(iv[i].settings_id > 0 && iv[i].settings_id <= NGHTTP2_SETTINGS_MAX) {
+    /* SETTINGS_MAX_CONCURRENT_STREAMS has already been applied on
+       transmission of the SETTINGS frame. */
+    if(iv[i].settings_id > 0 && iv[i].settings_id <= NGHTTP2_SETTINGS_MAX &&
+       iv[i].settings_id != NGHTTP2_SETTINGS_MAX_CONCURRENT_STREAMS) {
       session->local_settings[iv[i].settings_id] = iv[i].value;
     }
   }
@@ -2259,7 +2350,8 @@ int nghttp2_session_update_local_settings(nghttp2_session *session,
 }
 
 int nghttp2_session_on_settings_received(nghttp2_session *session,
-                                         nghttp2_frame *frame)
+                                         nghttp2_frame *frame,
+                                         int noack)
 {
   int rv;
   int i;
@@ -2268,6 +2360,33 @@ int nghttp2_session_on_settings_received(nghttp2_session *session,
     return nghttp2_session_handle_invalid_connection(session, frame,
                                                      NGHTTP2_PROTOCOL_ERROR);
   }
+  if(frame->hd.flags & NGHTTP2_FLAG_ACK) {
+    if(frame->settings.niv != 0) {
+      return nghttp2_session_handle_invalid_connection
+        (session, frame, NGHTTP2_FRAME_TOO_LARGE);
+    }
+    if(session->inflight_niv == -1) {
+      return nghttp2_session_handle_invalid_connection(session, frame,
+                                                       NGHTTP2_PROTOCOL_ERROR);
+    }
+    rv = nghttp2_session_update_local_settings(session, session->inflight_iv,
+                                               session->inflight_niv);
+    free(session->inflight_iv);
+    session->inflight_iv = NULL;
+    session->inflight_niv = -1;
+    if(rv != 0) {
+      nghttp2_error_code error_code = NGHTTP2_INTERNAL_ERROR;
+      if(nghttp2_is_fatal(rv)) {
+        return rv;
+      }
+      if(rv == NGHTTP2_ERR_HEADER_COMP) {
+        error_code = NGHTTP2_COMPRESSION_ERROR;
+      }
+      return nghttp2_session_handle_invalid_connection(session, frame,
+                                                       error_code);
+    }
+    return nghttp2_session_call_on_frame_received(session, frame);
+  }
   /* Check ID/value pairs and persist them if necessary. */
   memset(check, 0, sizeof(check));
   for(i = (int)frame->settings.niv - 1; i >= 0; --i) {
@@ -2282,6 +2401,21 @@ int nghttp2_session_on_settings_received(nghttp2_session *session,
     }
     check[entry->settings_id] = 1;
     switch(entry->settings_id) {
+    case NGHTTP2_SETTINGS_HEADER_TABLE_SIZE:
+      if(entry->value > NGHTTP2_MAX_HEADER_TABLE_SIZE) {
+        return nghttp2_session_handle_invalid_connection
+          (session, frame, NGHTTP2_COMPRESSION_ERROR);
+      }
+      rv = nghttp2_hd_change_table_size(&session->hd_deflater, entry->value);
+      if(rv != 0) {
+        if(nghttp2_is_fatal(rv)) {
+          return rv;
+        } else {
+          return nghttp2_session_handle_invalid_connection
+            (session, frame, NGHTTP2_COMPRESSION_ERROR);
+        }
+      }
+      break;
     case NGHTTP2_SETTINGS_INITIAL_WINDOW_SIZE:
       /* Update the initial window size of the all active streams */
       /* Check that initial_window_size < (1u << 31) */
@@ -2306,6 +2440,8 @@ int nghttp2_session_on_settings_received(nghttp2_session *session,
         if(session->remote_settings[entry->settings_id] == 0) {
           rv = nghttp2_session_disable_remote_flow_control(session);
           if(rv != 0) {
+            /* FATAL */
+            assert(rv < NGHTTP2_ERR_FATAL);
             return rv;
           }
         }
@@ -2319,6 +2455,16 @@ int nghttp2_session_on_settings_received(nghttp2_session *session,
     }
     session->remote_settings[entry->settings_id] = entry->value;
   }
+  if(!noack) {
+    rv = nghttp2_session_add_settings(session, NGHTTP2_FLAG_ACK, NULL, 0);
+    if(rv != 0) {
+      if(nghttp2_is_fatal(rv)) {
+        return rv;
+      }
+      return nghttp2_session_handle_invalid_connection
+        (session, frame, NGHTTP2_INTERNAL_ERROR);
+    }
+  }
   return nghttp2_session_call_on_frame_received(session, frame);
 }
 
@@ -2401,9 +2547,9 @@ int nghttp2_session_on_ping_received(nghttp2_session *session,
     return nghttp2_session_handle_invalid_connection(session, frame,
                                                      NGHTTP2_PROTOCOL_ERROR);
   }
-  if((frame->hd.flags & NGHTTP2_FLAG_PONG) == 0) {
+  if((frame->hd.flags & NGHTTP2_FLAG_ACK) == 0) {
     /* Peer sent ping, so ping it back */
-    r = nghttp2_session_add_ping(session, NGHTTP2_FLAG_PONG,
+    r = nghttp2_session_add_ping(session, NGHTTP2_FLAG_ACK,
                                  frame->ping.opaque_data);
     if(r != 0) {
       return r;
@@ -2645,7 +2791,7 @@ static int nghttp2_session_process_ctrl_frame(nghttp2_session *session)
                                       session->iframe.buf,
                                       session->iframe.buflen);
     if(r == 0) {
-      r = nghttp2_session_on_settings_received(session, frame);
+      r = nghttp2_session_on_settings_received(session, frame, 0 /* ACK */);
       if(r != NGHTTP2_ERR_PAUSE) {
         nghttp2_frame_settings_free(&frame->settings);
       }
@@ -3328,6 +3474,37 @@ int nghttp2_session_add_window_update(nghttp2_session *session, uint8_t flags,
   return r;
 }
 
+int nghttp2_session_add_settings(nghttp2_session *session, uint8_t flags,
+                                 const nghttp2_settings_entry *iv, size_t niv)
+{
+  nghttp2_frame *frame;
+  nghttp2_settings_entry *iv_copy;
+  int r;
+  if(!nghttp2_iv_check(iv, niv,
+                       session->local_settings
+                       [NGHTTP2_SETTINGS_FLOW_CONTROL_OPTIONS])) {
+    return NGHTTP2_ERR_INVALID_ARGUMENT;
+  }
+  frame = malloc(sizeof(nghttp2_frame));
+  if(frame == NULL) {
+    return NGHTTP2_ERR_NOMEM;
+  }
+  iv_copy = nghttp2_frame_iv_copy(iv, niv);
+  if(iv_copy == NULL) {
+    free(frame);
+    return NGHTTP2_ERR_NOMEM;
+  }
+  nghttp2_frame_settings_init(&frame->settings, flags, iv_copy, niv);
+  r = nghttp2_session_add_frame(session, NGHTTP2_CAT_CTRL, frame, NULL);
+  if(r != 0) {
+    /* The only expected error is fatal one */
+    assert(r < NGHTTP2_ERR_FATAL);
+    nghttp2_frame_settings_free(&frame->settings);
+    free(frame);
+  }
+  return r;
+}
+
 ssize_t nghttp2_session_pack_data(nghttp2_session *session,
                                   uint8_t **buf_ptr, size_t *buflen_ptr,
                                   size_t datamax,
@@ -3481,7 +3658,7 @@ int nghttp2_session_upgrade(nghttp2_session *session,
     memset(&frame.hd, 0, sizeof(frame.hd));
     frame.settings.iv = iv;
     frame.settings.niv = niv;
-    rv = nghttp2_session_on_settings_received(session, &frame);
+    rv = nghttp2_session_on_settings_received(session, &frame, 1 /* No ACK */);
   } else {
     rv = nghttp2_submit_settings(session, NGHTTP2_FLAG_NONE, iv, niv);
   }

lib/nghttp2_session.h

@@ -188,6 +188,13 @@ struct nghttp2_session {
   /* Settings value of the local endpoint. */
   uint32_t local_settings[NGHTTP2_SETTINGS_MAX+1];
 
+  /* In-flight SETTINGS values. NULL does not necessarily mean there
+     is no in-flight SETTINGS. */
+  nghttp2_settings_entry *inflight_iv;
+  /* The number of entries in |inflight_iv|. -1 if there is no
+     in-flight SETTINGS. */
+  ssize_t inflight_niv;
+
   /* Option flags. This is bitwise-OR of 0 or more of nghttp2_optmask. */
   uint32_t opt_flags;
 
@@ -295,6 +302,18 @@ int nghttp2_session_add_window_update(nghttp2_session *session, uint8_t flags,
                                       int32_t stream_id,
                                       int32_t window_size_increment);
 
+/*
+ * Adds SETTINGS frame.
+ *
+ * This function returns 0 if it succeeds, or one of the following
+ * negative error codes:
+ *
+ * NGHTTP2_ERR_NOMEM
+ *     Out of memory.
+ */
+int nghttp2_session_add_settings(nghttp2_session *session, uint8_t flags,
+                                 const nghttp2_settings_entry *iv, size_t niv);
+
 /*
  * Creates new stream in |session| with stream ID |stream_id|,
  * priority |pri| and flags |flags|. NGHTTP2_FLAG_END_STREAM flag is
@@ -386,19 +405,33 @@ int nghttp2_session_on_priority_received(nghttp2_session *session,
  * Called when RST_STREAM is received, assuming |frame| is properly
  * initialized.
  *
- * This function returns 0 and never fail.
+ * This function returns 0 if it succeeds, or one the following
+ * negative error codes:
+ *
+ * TBD
  */
 int nghttp2_session_on_rst_stream_received(nghttp2_session *session,
                                            nghttp2_frame *frame);
 
 /*
  * Called when SETTINGS is received, assuming |frame| is properly
- * initialized.
+ * initialized. If |noack| is non-zero, SETTINGS with ACK will not be
+ * submitted. If |frame| has NGHTTP2_FLAG_ACK flag set, no SETTINGS
+ * with ACK will not be submitted regardless of |noack|.
  *
- * This function returns 0 and never fail.
+ * This function returns 0 if it succeeds, or one the following
+ * negative error codes:
+ *
+ * NGHTTP2_ERR_NOMEM
+ *     Out of memory
+ * NGHTTP2_ERR_PAUSE
+ *     Callback function returns NGHTTP2_ERR_PAUSE
+ * NGHTTP2_ERR_CALLBACK_FAILURE
+ *     The read_callback failed
  */
 int nghttp2_session_on_settings_received(nghttp2_session *session,
-                                         nghttp2_frame *frame);
+                                         nghttp2_frame *frame,
+                                         int noack);
 
 /*
  * Called when PUSH_PROMISE is received, assuming |frame| is properly

lib/nghttp2_submit.c

@@ -209,39 +209,7 @@ int nghttp2_submit_goaway(nghttp2_session *session, uint8_t flags,
 int nghttp2_submit_settings(nghttp2_session *session, uint8_t flags,
                             const nghttp2_settings_entry *iv, size_t niv)
 {
-  nghttp2_frame *frame;
+  return nghttp2_session_add_settings(session, NGHTTP2_FLAG_NONE, iv, niv);
-  nghttp2_settings_entry *iv_copy;
-  int r;
-  if(!nghttp2_iv_check(iv, niv,
-                       session->local_settings
-                       [NGHTTP2_SETTINGS_FLOW_CONTROL_OPTIONS])) {
-    return NGHTTP2_ERR_INVALID_ARGUMENT;
-  }
-  frame = malloc(sizeof(nghttp2_frame));
-  if(frame == NULL) {
-    return NGHTTP2_ERR_NOMEM;
-  }
-  iv_copy = nghttp2_frame_iv_copy(iv, niv);
-  if(iv_copy == NULL) {
-    free(frame);
-    return NGHTTP2_ERR_NOMEM;
-  }
-  nghttp2_frame_settings_init(&frame->settings, iv_copy, niv);
-
-  r = nghttp2_session_update_local_settings(session, iv_copy, niv);
-  if(r != 0) {
-    nghttp2_frame_settings_free(&frame->settings);
-    free(frame);
-    return r;
-  }
-  r = nghttp2_session_add_frame(session, NGHTTP2_CAT_CTRL, frame, NULL);
-  if(r != 0) {
-    /* The only expected error is fatal one */
-    assert(r < NGHTTP2_ERR_FATAL);
-    nghttp2_frame_settings_free(&frame->settings);
-    free(frame);
-  }
-  return r;
 }
 
 int nghttp2_submit_push_promise(nghttp2_session *session, uint8_t flags,

src/app_helper.cc

@@ -80,12 +80,16 @@ namespace {
 const char* strsettingsid(int32_t id)
 {
   switch(id) {
+  case NGHTTP2_SETTINGS_HEADER_TABLE_SIZE:
+    return "SETTINGS_HEADER_TABLE_SIZE";
+  case NGHTTP2_SETTINGS_ENABLE_PUSH:
+    return "SETTINGS_ENABLE_PUSH";
   case NGHTTP2_SETTINGS_MAX_CONCURRENT_STREAMS:
-    return "MAX_CONCURRENT_STREAMS";
+    return "SETTINGS_MAX_CONCURRENT_STREAMS";
   case NGHTTP2_SETTINGS_INITIAL_WINDOW_SIZE:
-    return "INITIAL_WINDOW_SIZE";
+    return "SETTINGS_INITIAL_WINDOW_SIZE";
   case NGHTTP2_SETTINGS_FLOW_CONTROL_OPTIONS:
-    return "FLOW_CONTROL_OPTIONS";
+    return "SETTINGS_FLOW_CONTROL_OPTIONS";
   default:
     return "UNKNOWN";
   }
@@ -208,14 +212,19 @@ void print_flags(const nghttp2_frame_hd& hd)
       s += "PRIORITY";
     }
     break;
+  case NGHTTP2_SETTINGS:
+    if(hd.flags & NGHTTP2_FLAG_ACK) {
+      s += "ACK";
+    }
+    break;
   case NGHTTP2_PUSH_PROMISE:
     if(hd.flags & NGHTTP2_FLAG_END_PUSH_PROMISE) {
       s += "END_PUSH_PROMISE";
     }
     break;
   case NGHTTP2_PING:
-    if(hd.flags & NGHTTP2_FLAG_PONG) {
+    if(hd.flags & NGHTTP2_FLAG_ACK) {
-      s += "PONG";
+      s += "ACK";
     }
     break;
   }

tests/nghttp2_frame_test.c

@@ -223,7 +223,8 @@ void test_nghttp2_frame_pack_settings()
   iv[2].settings_id = NGHTTP2_SETTINGS_FLOW_CONTROL_OPTIONS;
   iv[2].value = 1;
 
-  nghttp2_frame_settings_init(&frame, nghttp2_frame_iv_copy(iv, 3), 3);
+  nghttp2_frame_settings_init(&frame, NGHTTP2_FLAG_NONE,
+                              nghttp2_frame_iv_copy(iv, 3), 3);
   framelen = nghttp2_frame_pack_settings(&buf, &buflen, &frame);
   CU_ASSERT(NGHTTP2_FRAME_HEAD_LENGTH+3*8 == framelen);
 
@@ -290,14 +291,14 @@ void test_nghttp2_frame_pack_ping(void)
   size_t buflen = 0;
   ssize_t framelen;
   const uint8_t opaque_data[] = "01234567";
-  nghttp2_frame_ping_init(&frame, NGHTTP2_FLAG_PONG, opaque_data);
+  nghttp2_frame_ping_init(&frame, NGHTTP2_FLAG_ACK, opaque_data);
   framelen = nghttp2_frame_pack_ping(&buf, &buflen, &frame);
   CU_ASSERT(0 == nghttp2_frame_unpack_ping
             (&oframe,
              &buf[0], NGHTTP2_FRAME_HEAD_LENGTH,
              &buf[NGHTTP2_FRAME_HEAD_LENGTH],
              framelen - NGHTTP2_FRAME_HEAD_LENGTH));
-  check_frame_header(8, NGHTTP2_PING, NGHTTP2_FLAG_PONG, 0, &oframe.hd);
+  check_frame_header(8, NGHTTP2_PING, NGHTTP2_FLAG_ACK, 0, &oframe.hd);
   CU_ASSERT(memcmp(opaque_data, oframe.opaque_data, sizeof(opaque_data) - 1)
             == 0);
   free(buf);

tests/nghttp2_session_test.c

@@ -1134,6 +1134,7 @@ void test_nghttp2_session_on_settings_received(void)
   nghttp2_frame frame;
   const size_t niv = 5;
   nghttp2_settings_entry iv[255];
+  nghttp2_outbound_item *item;
 
   iv[0].settings_id = NGHTTP2_SETTINGS_MAX_CONCURRENT_STREAMS;
   iv[0].value = 50;
@@ -1166,9 +1167,10 @@ void test_nghttp2_session_on_settings_received(void)
   stream1->remote_window_size = 16*1024;
   stream2->remote_window_size = -48*1024;
 
-  nghttp2_frame_settings_init(&frame.settings, dup_iv(iv, niv), niv);
+  nghttp2_frame_settings_init(&frame.settings, NGHTTP2_FLAG_NONE,
+                              dup_iv(iv, niv), niv);
 
-  CU_ASSERT(0 == nghttp2_session_on_settings_received(session, &frame));
+  CU_ASSERT(0 == nghttp2_session_on_settings_received(session, &frame, 0));
   CU_ASSERT(1000000009 ==
             session->remote_settings[NGHTTP2_SETTINGS_MAX_CONCURRENT_STREAMS]);
   CU_ASSERT(64*1024 ==
@@ -1181,7 +1183,7 @@ void test_nghttp2_session_on_settings_received(void)
 
   frame.settings.iv[2].value = 16*1024;
 
-  CU_ASSERT(0 == nghttp2_session_on_settings_received(session, &frame));
+  CU_ASSERT(0 == nghttp2_session_on_settings_received(session, &frame, 0));
 
   CU_ASSERT(16*1024 == stream1->remote_window_size);
   CU_ASSERT(-48*1024 == stream2->remote_window_size);
@@ -1193,6 +1195,37 @@ void test_nghttp2_session_on_settings_received(void)
   nghttp2_frame_settings_free(&frame.settings);
 
   nghttp2_session_del(session);
+
+  /* Check ACK with niv > 0 */
+  nghttp2_session_server_new(&session, &callbacks, NULL);
+  nghttp2_frame_settings_init(&frame.settings, NGHTTP2_FLAG_ACK,
+                              dup_iv(iv, 1), 1);
+  /* Specify inflight_iv deliberately */
+  session->inflight_iv = frame.settings.iv;
+  session->inflight_niv = frame.settings.niv;
+
+  CU_ASSERT(0 == nghttp2_session_on_settings_received(session, &frame, 0));
+  item = nghttp2_session_get_next_ob_item(session);
+  CU_ASSERT(item != NULL);
+  CU_ASSERT(NGHTTP2_GOAWAY == OB_CTRL_TYPE(item));
+
+  session->inflight_iv = NULL;
+  session->inflight_niv = -1;
+
+  nghttp2_frame_settings_free(&frame.settings);
+  nghttp2_session_del(session);
+
+  /* Check ACK against no inflight SETTINGS */
+  nghttp2_session_server_new(&session, &callbacks, NULL);
+  nghttp2_frame_settings_init(&frame.settings, NGHTTP2_FLAG_ACK, NULL, 0);
+
+  CU_ASSERT(0 == nghttp2_session_on_settings_received(session, &frame, 0));
+  item = nghttp2_session_get_next_ob_item(session);
+  CU_ASSERT(item != NULL);
+  CU_ASSERT(NGHTTP2_GOAWAY == OB_CTRL_TYPE(item));
+
+  nghttp2_frame_settings_free(&frame.settings);
+  nghttp2_session_del(session);
 }
 
 void test_nghttp2_session_on_push_promise_received(void)
@@ -1346,7 +1379,7 @@ void test_nghttp2_session_on_ping_received(void)
   callbacks.on_invalid_frame_recv_callback = on_invalid_frame_recv_callback;
 
   nghttp2_session_client_new(&session, &callbacks, &user_data);
-  nghttp2_frame_ping_init(&frame.ping, NGHTTP2_FLAG_PONG, opaque_data);
+  nghttp2_frame_ping_init(&frame.ping, NGHTTP2_FLAG_ACK, opaque_data);
 
   CU_ASSERT(0 == nghttp2_session_on_ping_received(session, &frame));
   CU_ASSERT(1 == user_data.frame_recv_cb_called);
@@ -1362,7 +1395,7 @@ void test_nghttp2_session_on_ping_received(void)
   CU_ASSERT(2 == user_data.frame_recv_cb_called);
   top = nghttp2_session_get_ob_pq_top(session);
   CU_ASSERT(NGHTTP2_PING == OB_CTRL_TYPE(top));
-  CU_ASSERT(NGHTTP2_FLAG_PONG == OB_CTRL(top)->hd.flags);
+  CU_ASSERT(NGHTTP2_FLAG_ACK == OB_CTRL(top)->hd.flags);
   CU_ASSERT(memcmp(opaque_data, OB_CTRL(top)->ping.opaque_data, 8) == 0);
 
   nghttp2_frame_ping_free(&frame.ping);
@@ -2260,6 +2293,7 @@ void test_nghttp2_submit_settings(void)
   nghttp2_outbound_item *item;
   nghttp2_frame *frame;
   nghttp2_settings_entry iv[5];
+  nghttp2_frame ack_frame;
 
   iv[0].settings_id = NGHTTP2_SETTINGS_MAX_CONCURRENT_STREAMS;
   iv[0].value = 5;
@@ -2296,15 +2330,6 @@ void test_nghttp2_submit_settings(void)
   /* Now sends without 5th one */
   CU_ASSERT(0 == nghttp2_submit_settings(session, NGHTTP2_FLAG_NONE, iv, 4));
 
-  /* Make sure that local settings are changed */
-  CU_ASSERT(50 ==
-            session->local_settings[NGHTTP2_SETTINGS_MAX_CONCURRENT_STREAMS]);
-  CU_ASSERT(16*1024 ==
-            session->local_settings[NGHTTP2_SETTINGS_INITIAL_WINDOW_SIZE]);
-  CU_ASSERT(1 ==
-            session->local_settings[NGHTTP2_SETTINGS_FLOW_CONTROL_OPTIONS]);
-  CU_ASSERT(0 == session->local_flow_control);
-
   item = nghttp2_session_get_next_ob_item(session);
 
   CU_ASSERT(NGHTTP2_SETTINGS == OB_CTRL_TYPE(item));
@@ -2323,6 +2348,20 @@ void test_nghttp2_submit_settings(void)
   CU_ASSERT(0 == nghttp2_session_send(session));
   CU_ASSERT(1 == ud.frame_send_cb_called);
 
+  /* Only SETTINGS_MAX_CONCURRENT_STREAMS is applied on transmission */
+  CU_ASSERT(50 ==
+            session->local_settings[NGHTTP2_SETTINGS_MAX_CONCURRENT_STREAMS]);
+
+  nghttp2_frame_settings_init(&ack_frame.settings, NGHTTP2_FLAG_ACK, NULL, 0);
+  CU_ASSERT(0 == nghttp2_session_on_settings_received(session, &ack_frame, 0));
+  nghttp2_frame_settings_free(&ack_frame.settings);
+
+  CU_ASSERT(16*1024 ==
+            session->local_settings[NGHTTP2_SETTINGS_INITIAL_WINDOW_SIZE]);
+  CU_ASSERT(1 ==
+            session->local_settings[NGHTTP2_SETTINGS_FLOW_CONTROL_OPTIONS]);
+  CU_ASSERT(0 == session->local_flow_control);
+
   nghttp2_session_del(session);
 }
 
@@ -2333,7 +2372,9 @@ void test_nghttp2_submit_settings_update_local_window_size(void)
   nghttp2_outbound_item *item;
   nghttp2_settings_entry iv[4];
   nghttp2_stream *stream;
-  my_user_data ud;
+  nghttp2_frame ack_frame;
+
+  nghttp2_frame_settings_init(&ack_frame.settings, NGHTTP2_FLAG_ACK, NULL, 0);
 
   iv[0].settings_id = NGHTTP2_SETTINGS_INITIAL_WINDOW_SIZE;
   iv[0].value = 16*1024;
@@ -2342,9 +2383,9 @@ void test_nghttp2_submit_settings_update_local_window_size(void)
   iv[1].value = 1;
 
   memset(&callbacks, 0, sizeof(nghttp2_session_callbacks));
-  callbacks.send_callback = block_count_send_callback;
+  callbacks.send_callback = null_send_callback;
 
-  nghttp2_session_server_new(&session, &callbacks, &ud);
+  nghttp2_session_server_new(&session, &callbacks, NULL);
 
   stream = nghttp2_session_open_stream(session, 1, NGHTTP2_FLAG_NONE,
                                        NGHTTP2_PRI_DEFAULT,
@@ -2358,6 +2399,8 @@ void test_nghttp2_submit_settings_update_local_window_size(void)
   stream->local_flow_control = 0;
 
   CU_ASSERT(0 == nghttp2_submit_settings(session, NGHTTP2_FLAG_NONE, iv, 1));
+  CU_ASSERT(0 == nghttp2_session_send(session));
+  CU_ASSERT(0 == nghttp2_session_on_settings_received(session, &ack_frame, 0));
 
   stream = nghttp2_session_get_stream(session, 1);
   CU_ASSERT(0 == stream->recv_window_size);
@@ -2366,9 +2409,6 @@ void test_nghttp2_submit_settings_update_local_window_size(void)
   stream = nghttp2_session_get_stream(session, 3);
   CU_ASSERT(NGHTTP2_INITIAL_WINDOW_SIZE == stream->local_window_size);
 
-  /* Setting block_count = 0 will pop first entry SETTINGS */
-  ud.block_count = 0;
-  CU_ASSERT(0 == nghttp2_session_send(session));
   item = nghttp2_session_get_next_ob_item(session);
   CU_ASSERT(NGHTTP2_WINDOW_UPDATE == OB_CTRL_TYPE(item));
   CU_ASSERT(32768 == OB_CTRL(item)->window_update.window_size_increment);
@@ -2376,28 +2416,35 @@ void test_nghttp2_submit_settings_update_local_window_size(void)
   nghttp2_session_del(session);
 
   /* Check flow control disabled case */
-  nghttp2_session_server_new(&session, &callbacks, &ud);
+  nghttp2_session_server_new(&session, &callbacks, NULL);
   stream = nghttp2_session_open_stream(session, 1, NGHTTP2_FLAG_NONE,
                                        NGHTTP2_PRI_DEFAULT,
                                        NGHTTP2_STREAM_OPENED, NULL);
 
   CU_ASSERT(0 == nghttp2_submit_settings(session, NGHTTP2_FLAG_NONE, iv, 2));
+  CU_ASSERT(0 == nghttp2_session_send(session));
+  CU_ASSERT(0 == nghttp2_session_on_settings_received(session, &ack_frame, 0));
+
   CU_ASSERT(NGHTTP2_INITIAL_WINDOW_SIZE == stream->local_window_size);
 
   nghttp2_session_del(session);
 
   /* Check overflow case */
   iv[0].value = 128*1024;
-  nghttp2_session_server_new(&session, &callbacks, &ud);
+  nghttp2_session_server_new(&session, &callbacks, NULL);
   stream = nghttp2_session_open_stream(session, 1, NGHTTP2_FLAG_NONE,
                                        NGHTTP2_PRI_DEFAULT,
                                        NGHTTP2_STREAM_OPENED, NULL);
   stream->local_window_size = NGHTTP2_MAX_WINDOW_SIZE;
 
   CU_ASSERT(0 == nghttp2_submit_settings(session, NGHTTP2_FLAG_NONE, iv, 1));
+  CU_ASSERT(0 == nghttp2_session_send(session));
+  CU_ASSERT(0 == nghttp2_session_on_settings_received(session, &ack_frame, 0));
+
   CU_ASSERT(NGHTTP2_STREAM_CLOSING == stream->state);
 
   nghttp2_session_del(session);
+  nghttp2_frame_settings_free(&ack_frame.settings);
 }
 
 void test_nghttp2_submit_push_promise(void)
@@ -3068,8 +3115,9 @@ void test_nghttp2_session_flow_control(void)
   iv[0].settings_id = NGHTTP2_SETTINGS_INITIAL_WINDOW_SIZE;
   iv[0].value = 32*1024;
 
-  nghttp2_frame_settings_init(&settings_frame.settings, dup_iv(iv, 1), 1);
+  nghttp2_frame_settings_init(&settings_frame.settings, NGHTTP2_FLAG_NONE,
-  nghttp2_session_on_settings_received(session, &settings_frame);
+                              dup_iv(iv, 1), 1);
+  nghttp2_session_on_settings_received(session, &settings_frame, 1);
   nghttp2_frame_settings_free(&settings_frame.settings);
 
   /* Sends another 8KiB data */
@@ -3119,8 +3167,9 @@ void test_nghttp2_session_flow_control_disable_remote(void)
   CU_ASSERT(data_size - NGHTTP2_INITIAL_WINDOW_SIZE == ud.data_source_length);
 
   /* Disable flow control entirely */
-  nghttp2_frame_settings_init(&frame.settings, dup_iv(&iv, 1), 1);
+  nghttp2_frame_settings_init(&frame.settings, NGHTTP2_FLAG_NONE,
-  nghttp2_session_on_settings_received(session, &frame);
+                              dup_iv(&iv, 1), 1);
+  nghttp2_session_on_settings_received(session, &frame, 1);
 
   /* Check both connection and stream-level remote_flow_control is
      disabled */
@@ -3141,7 +3190,9 @@ void test_nghttp2_session_flow_control_disable_local(void)
   nghttp2_session_callbacks callbacks;
   nghttp2_stream *stream;
   nghttp2_settings_entry iv[1];
+  nghttp2_frame ack_frame;
 
+  nghttp2_frame_settings_init(&ack_frame.settings, NGHTTP2_FLAG_ACK, NULL, 0);
   memset(&callbacks, 0, sizeof(nghttp2_session_callbacks));
   callbacks.send_callback = null_send_callback;
 
@@ -3155,11 +3206,15 @@ void test_nghttp2_session_flow_control_disable_local(void)
   iv[0].value = 1;
 
   CU_ASSERT(0 == nghttp2_submit_settings(session, NGHTTP2_FLAG_NONE, iv,
-                                         sizeof(iv)/sizeof(iv[0])));
+                                         ARRLEN(iv)));
+  CU_ASSERT(0 == nghttp2_session_send(session));
+  CU_ASSERT(0 == nghttp2_session_on_settings_received(session, &ack_frame, 0));
+
   CU_ASSERT(0 == stream->local_flow_control);
   CU_ASSERT(0 == session->local_flow_control);
 
   nghttp2_session_del(session);
+  nghttp2_frame_settings_free(&ack_frame.settings);
 }
 
 void test_nghttp2_session_flow_control_data_recv(void)