http2: addtl http/2 settings

Currently, node.js http/2 is limited in sending SETTINGs, that are currently implemented by nghttp2. However, nghttp2 has the ability to send arbitary SETTINGs, that are not known beforehand. This patch adds this feature including a fall back mechanism, if a SETTING is implemented in a later nghttp2 or node version. Fixes: #1337 PR-URL: #49025 Reviewed-By: Matteo Collina <matteo.collina@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Marco Ippolito <marcoippolito54@gmail.com>
RafaelGSS · Jan 15, 2024 · Oct 28, 2023 · Nov 16, 2023 · Dec 16, 2023 · Dec 16, 2023
commit 89eee7763fece62952d28eefcbddde7f0d3a6369
diff --git a/doc/api/errors.md b/doc/api/errors.md
@@ -1710,6 +1710,12 @@ When setting the priority for an HTTP/2 stream, the stream may be marked as
 a dependency for a parent stream. This error code is used when an attempt is
 made to mark a stream and dependent of itself.
 
+<a id="ERR_HTTP2_TOO_MANY_CUSTOM_SETTINGS"></a>
+
+### `ERR_HTTP2_TOO_MANY_CUSTOM_SETTINGS`
+
+The number of supported custom settings (10) has been exceeded.
+
 <a id="ERR_HTTP2_TOO_MANY_INVALID_FRAMES"></a>
 
 ### `ERR_HTTP2_TOO_MANY_INVALID_FRAMES`

diff --git a/doc/api/http2.md b/doc/api/http2.md
@@ -3010,6 +3010,19 @@ properties.
   meaningful if sent by the server. Once the `enableConnectProtocol` setting
   has been enabled for a given `Http2Session`, it cannot be disabled.
   **Default:** `false`.
+* `customSettings` {Object} Specifies additional settings, yet not implemented
+  in node and the underlying libraries. The key of the object defines the
+  numeric value of the settings type (as defined in the "HTTP/2 SETTINGS"
+  registry established by \[RFC 7540]) and the values the actual numeric value
+  of the settings.
+  The settings type has to be an integer in the range from 1 to 2^16-1.
+  It should not be a settings type already handled by node, i.e. currently
+  it should be greater than 6, although it is not an error.
+  The values need to be unsigned integers in the range from 0 to 2^32-1.
+  Currently, a maximum of up 10 custom settings is supported.
+  It is only supported for sending SETTINGS.
+  Custom settings are not supported for the functions retrieving remote and
+  local settings as nghttp2 does not pass unknown HTTP/2 settings to Node.js.
 
 All additional properties on the settings object are ignored.
 

diff --git a/lib/internal/errors.js b/lib/internal/errors.js
@@ -1279,6 +1279,8 @@ E('ERR_HTTP2_STREAM_CANCEL', function(error) {
 E('ERR_HTTP2_STREAM_ERROR', 'Stream closed with error code %s', Error);
 E('ERR_HTTP2_STREAM_SELF_DEPENDENCY',
   'A stream cannot depend on itself', Error);
+E('ERR_HTTP2_TOO_MANY_CUSTOM_SETTINGS',
+  'Number of custom settings exceeds MAX_ADDITIONAL_SETTINGS', Error);
 E('ERR_HTTP2_TOO_MANY_INVALID_FRAMES', 'Too many invalid HTTP/2 frames', Error);
 E('ERR_HTTP2_TRAILERS_ALREADY_SENT',
   'Trailing headers have already been sent', Error);

diff --git a/lib/internal/http2/core.js b/lib/internal/http2/core.js
@@ -946,6 +946,8 @@ function pingCallback(cb) {
 // All settings are optional and may be left undefined
 const validateSettings = hideStackFrames((settings) => {
   if (settings === undefined) return;
+  assertIsObject.withoutStackTrace(settings.customSettings, 'customSettings', 'Number');
+
   assertWithinRange.withoutStackTrace('headerTableSize',
                                       settings.headerTableSize,
                                       0, kMaxInt);
@@ -3387,6 +3389,10 @@ function getUnpackedSettings(buf, options = kEmptyObject) {
         break;
       case NGHTTP2_SETTINGS_ENABLE_CONNECT_PROTOCOL:
         settings.enableConnectProtocol = value !== 0;
+        break;
+      default:
+        if (!settings.customSettings) settings.customSettings = {};
+        settings.customSettings[id] = value;
     }
     offset += 4;
   }

diff --git a/lib/internal/http2/util.js b/lib/internal/http2/util.js
@@ -8,6 +8,7 @@ const {
   Error,
   MathMax,
   Number,
+  NumberIsNaN,
   ObjectKeys,
   SafeSet,
   String,
@@ -24,6 +25,7 @@ const {
     ERR_HTTP2_INVALID_CONNECTION_HEADERS,
     ERR_HTTP2_INVALID_PSEUDOHEADER: { HideStackFramesError: ERR_HTTP2_INVALID_PSEUDOHEADER },
     ERR_HTTP2_INVALID_SETTING_VALUE,
+    ERR_HTTP2_TOO_MANY_CUSTOM_SETTINGS,
     ERR_INVALID_ARG_TYPE,
     ERR_INVALID_HTTP_TOKEN,
   },
@@ -190,6 +192,9 @@ const IDX_SETTINGS_MAX_HEADER_LIST_SIZE = 5;
 const IDX_SETTINGS_ENABLE_CONNECT_PROTOCOL = 6;
 const IDX_SETTINGS_FLAGS = 7;
 
+// Maximum number of allowed additional settings
+const MAX_ADDITIONAL_SETTINGS = 10;
+
 const IDX_SESSION_STATE_EFFECTIVE_LOCAL_WINDOW_SIZE = 0;
 const IDX_SESSION_STATE_EFFECTIVE_RECV_DATA_LENGTH = 1;
 const IDX_SESSION_STATE_NEXT_STREAM_ID = 2;
@@ -348,6 +353,80 @@ function getSettings(session, remote) {
 
 function updateSettingsBuffer(settings) {
   let flags = 0;
+  let numCustomSettings = 0;
+
+  if (typeof settings.customSettings === 'object') {
+    const customSettings = settings.customSettings;
+    for (const setting in customSettings) {
+      const val = customSettings[setting];
+      if (typeof val === 'number') {
+        let set = false;
+        const nsetting = Number(setting);
+        if (NumberIsNaN(nsetting) ||
+          typeof nsetting !== 'number' ||
+          0 >= nsetting ||
+          nsetting > 0xffff)
+          throw new ERR_HTTP2_INVALID_SETTING_VALUE.RangeError(
+            'Range Error', nsetting, 0, 0xffff);
+        if (NumberIsNaN(val) ||
+            typeof val !== 'number' ||
+            0 >= val ||
+            val > 0xffffffff)
+          throw new ERR_HTTP2_INVALID_SETTING_VALUE.RangeError(
+            'Range Error', val, 0, 0xffffffff);
+        if (nsetting < IDX_SETTINGS_FLAGS) {
+          set = true;
+          switch (nsetting) {
+            case IDX_SETTINGS_HEADER_TABLE_SIZE:
+              flags |= (1 << IDX_SETTINGS_HEADER_TABLE_SIZE);
+              settingsBuffer[IDX_SETTINGS_HEADER_TABLE_SIZE] =
+                val;
+              break;
+            case IDX_SETTINGS_ENABLE_PUSH:
+              flags |= (1 << IDX_SETTINGS_ENABLE_PUSH);
+              settingsBuffer[IDX_SETTINGS_ENABLE_PUSH] = val;
+              break;
+            case IDX_SETTINGS_INITIAL_WINDOW_SIZE:
+              flags |= (1 << IDX_SETTINGS_INITIAL_WINDOW_SIZE);
+              settingsBuffer[IDX_SETTINGS_INITIAL_WINDOW_SIZE] =
+                val;
+              break;
+            case IDX_SETTINGS_MAX_FRAME_SIZE:
+              flags |= (1 << IDX_SETTINGS_MAX_FRAME_SIZE);
+              settingsBuffer[IDX_SETTINGS_MAX_FRAME_SIZE] =
+                val;
+              break;
+            case IDX_SETTINGS_MAX_CONCURRENT_STREAMS:
+              flags |= (1 << IDX_SETTINGS_MAX_CONCURRENT_STREAMS);
+              settingsBuffer[IDX_SETTINGS_MAX_CONCURRENT_STREAMS] = val;
+              break;
+            case IDX_SETTINGS_MAX_HEADER_LIST_SIZE:
+              flags |= (1 << IDX_SETTINGS_MAX_HEADER_LIST_SIZE);
+              settingsBuffer[IDX_SETTINGS_MAX_HEADER_LIST_SIZE] =
+                val;
+              break;
+            case IDX_SETTINGS_ENABLE_CONNECT_PROTOCOL:
+              flags |= (1 << IDX_SETTINGS_ENABLE_CONNECT_PROTOCOL);
+              settingsBuffer[IDX_SETTINGS_ENABLE_CONNECT_PROTOCOL] = val;
+              break;
+            default:
+              set = false;
+              break;
+          }
+        }
+        if (!set) { // not supported
+          if (numCustomSettings === MAX_ADDITIONAL_SETTINGS)
+            throw new ERR_HTTP2_TOO_MANY_CUSTOM_SETTINGS();
+
+          settingsBuffer[IDX_SETTINGS_FLAGS + 1 + 2 * numCustomSettings + 1] = nsetting;
+          settingsBuffer[IDX_SETTINGS_FLAGS + 1 + 2 * numCustomSettings + 2] = val;
+          numCustomSettings++;
+        }
+      }
+    }
+  }
+  settingsBuffer[IDX_SETTINGS_FLAGS + 1] = numCustomSettings;
+
   if (typeof settings.headerTableSize === 'number') {
     flags |= (1 << IDX_SETTINGS_HEADER_TABLE_SIZE);
     settingsBuffer[IDX_SETTINGS_HEADER_TABLE_SIZE] =

diff --git a/src/node_http2.cc b/src/node_http2.cc
@@ -228,6 +228,16 @@ size_t Http2Settings::Init(
   HTTP2_SETTINGS(V)
 #undef V
 
+  uint32_t numAddSettings = buffer[IDX_SETTINGS_COUNT + 1];
+  if (numAddSettings > 0) {
+    uint32_t offset = IDX_SETTINGS_COUNT + 1 + 1;
+    for (uint32_t i = 0; i < numAddSettings; i++) {
+      uint32_t key = buffer[offset + i * 2 + 0];
+      uint32_t val = buffer[offset + i * 2 + 1];
+      entries[count++] = nghttp2_settings_entry{(int32_t)key, val};
+    }
+  }
+
   return count;
 }
 #undef GRABSETTING
@@ -262,7 +272,7 @@ Local<Value> Http2Settings::Pack() {
 }
 
 Local<Value> Http2Settings::Pack(Http2State* state) {
-  nghttp2_settings_entry entries[IDX_SETTINGS_COUNT];
+  nghttp2_settings_entry entries[IDX_SETTINGS_COUNT + MAX_ADDITIONAL_SETTINGS];
   size_t count = Init(state, entries);
   return Pack(state->env(), count, entries);
 }
@@ -298,6 +308,8 @@ void Http2Settings::Update(Http2Session* session, get_setting fn) {
       fn(session->session(), NGHTTP2_SETTINGS_ ## name);
   HTTP2_SETTINGS(V)
 #undef V
+  buffer[IDX_SETTINGS_COUNT + 1] =
+      0;  // no additional settings are coming, clear them
 }
 
 // Initializes the shared TypedArray with the default settings values.
@@ -314,6 +326,7 @@ void Http2Settings::RefreshDefaults(Http2State* http2_state) {
 #undef V
 
   buffer[IDX_SETTINGS_COUNT] = flags;
+  buffer[IDX_SETTINGS_COUNT + 1] = 0;  // no additional settings
 }
 
 

diff --git a/src/node_http2.h b/src/node_http2.h
@@ -1035,7 +1035,7 @@ class Http2Settings : public AsyncWrap {
   v8::Global<v8::Function> callback_;
   uint64_t startTime_;
   size_t count_ = 0;
-  nghttp2_settings_entry entries_[IDX_SETTINGS_COUNT];
+  nghttp2_settings_entry entries_[IDX_SETTINGS_COUNT + MAX_ADDITIONAL_SETTINGS];
 };
 
 class Origins {

diff --git a/src/node_http2_state.h b/src/node_http2_state.h
@@ -21,6 +21,9 @@ namespace http2 {
     IDX_SETTINGS_COUNT
   };
 
+  // number of max additional settings, thus settings not implemented by nghttp2
+  const size_t MAX_ADDITIONAL_SETTINGS = 10;
+
   enum Http2SessionStateIndex {
     IDX_SESSION_STATE_EFFECTIVE_LOCAL_WINDOW_SIZE,
     IDX_SESSION_STATE_EFFECTIVE_RECV_DATA_LENGTH,
@@ -108,10 +111,11 @@ class Http2State : public BaseObject {
                        offsetof(http2_state_internal, options_buffer),
                        IDX_OPTIONS_FLAGS + 1,
                        root_buffer),
-        settings_buffer(realm->isolate(),
-                        offsetof(http2_state_internal, settings_buffer),
-                        IDX_SETTINGS_COUNT + 1,
-                        root_buffer) {}
+        settings_buffer(
+            realm->isolate(),
+            offsetof(http2_state_internal, settings_buffer),
+            IDX_SETTINGS_COUNT + 1 + 1 + 2 * MAX_ADDITIONAL_SETTINGS,
+            root_buffer) {}
 
   AliasedUint8Array root_buffer;
   AliasedFloat64Array session_state_buffer;
@@ -135,7 +139,12 @@ class Http2State : public BaseObject {
     double stream_stats_buffer[IDX_STREAM_STATS_COUNT];
     double session_stats_buffer[IDX_SESSION_STATS_COUNT];
     uint32_t options_buffer[IDX_OPTIONS_FLAGS + 1];
-    uint32_t settings_buffer[IDX_SETTINGS_COUNT + 1];
+    // first + 1: number of actual nghttp2 supported settings
+    // second + 1: number of additional settings not suppoted by nghttp2
+    // 2 * MAX_ADDITIONAL_SETTINGS: settings id and value for each
+    // additional setting
+    uint32_t settings_buffer[IDX_SETTINGS_COUNT + 1 + 1 +
+                             2 * MAX_ADDITIONAL_SETTINGS];
   };
 };
 

diff --git a/test/parallel/test-http2-getpackedsettings.js b/test/parallel/test-http2-getpackedsettings.js
@@ -29,6 +29,7 @@ assert.deepStrictEqual(val, check);
   ['maxHeaderListSize', 2 ** 32 - 1],
   ['maxHeaderSize', 0],
   ['maxHeaderSize', 2 ** 32 - 1],
+  ['customSettings', { '9999': 301 }],
 ].forEach((i) => {
   // Valid options should not throw.
   http2.getPackedSettings({ [i[0]]: i[1] });
@@ -93,6 +94,7 @@ http2.getPackedSettings({ enablePush: false });
     0x00, 0x05, 0x00, 0x00, 0x4e, 0x20,
     0x00, 0x06, 0x00, 0x00, 0x00, 0x64,
     0x00, 0x08, 0x00, 0x00, 0x00, 0x00,
+    0x27, 0x0F, 0x00, 0x00, 0x01, 0x2d,
   ]);
 
   const packed = http2.getPackedSettings({
@@ -104,12 +106,90 @@ http2.getPackedSettings({ enablePush: false });
     maxHeaderSize: 100,
     enablePush: true,
     enableConnectProtocol: false,
-    foo: 'ignored'
+    foo: 'ignored',
+    customSettings: { '9999': 301 }
   });
-  assert.strictEqual(packed.length, 42);
+  assert.strictEqual(packed.length, 48);
   assert.deepStrictEqual(packed, check);
 }
 
+// Check if multiple custom settings can be set
+{
+  const check = Buffer.from([
+    0x00, 0x01, 0x00, 0x00, 0x00, 0x64,
+    0x00, 0x02, 0x00, 0x00, 0x00, 0x01,
+    0x00, 0x03, 0x00, 0x00, 0x00, 0xc8,
+    0x00, 0x04, 0x00, 0x00, 0x00, 0x64,
+    0x00, 0x05, 0x00, 0x00, 0x4e, 0x20,
+    0x00, 0x06, 0x00, 0x00, 0x00, 0x64,
+    0x00, 0x08, 0x00, 0x00, 0x00, 0x00,
+    0x03, 0xf3, 0x00, 0x00, 0x07, 0x9F,
+    0x0a, 0x2e, 0x00, 0x00, 0x00, 0x58,
+  ]);
+
+  const packed = http2.getPackedSettings({
+    headerTableSize: 100,
+    initialWindowSize: 100,
+    maxFrameSize: 20000,
+    maxConcurrentStreams: 200,
+    maxHeaderListSize: 100,
+    maxHeaderSize: 100,
+    enablePush: true,
+    enableConnectProtocol: false,
+    customSettings: { '2606': 88, '1011': 1951 }
+  });
+  assert.strictEqual(packed.length, 54);
+  assert.deepStrictEqual(packed, check);
+}
+
+{
+  // Check if wrong custom settings cause an error
+
+  assert.throws(() => {
+    http2.getPackedSettings({
+      customSettings: { '-1': 659685 }
+    });
+  }, {
+    code: 'ERR_HTTP2_INVALID_SETTING_VALUE',
+    name: 'RangeError'
+  });
+
+  assert.throws(() => {
+    http2.getPackedSettings({
+      customSettings: { '10': 34577577777 }
+    });
+  }, {
+    code: 'ERR_HTTP2_INVALID_SETTING_VALUE',
+    name: 'RangeError'
+  });
+
+  assert.throws(() => {
+    http2.getPackedSettings({
+      customSettings: { 'notvalid': -777 }
+    });
+  }, {
+    code: 'ERR_HTTP2_INVALID_SETTING_VALUE',
+    name: 'RangeError'
+  });
+
+  assert.throws(() => {
+    http2.getPackedSettings({
+      customSettings: { '11': 11, '12': 12, '13': 13, '14': 14, '15': 15, '16': 16,
+                        '17': 17, '18': 18, '19': 19, '20': 20, '21': 21 }
+    });
+  }, {
+    code: 'ERR_HTTP2_TOO_MANY_CUSTOM_SETTINGS'
+  });
+  assert.throws(() => {
+    http2.getPackedSettings({
+      customSettings: { '11': 11, '12': 12, '13': 13, '14': 14, '15': 15, '16': 16,
+                        '17': 17, '18': 18, '19': 19, '20': 20, '21': 21, '22': 22 }
+    });
+  }, {
+    code: 'ERR_HTTP2_TOO_MANY_CUSTOM_SETTINGS'
+  });
+}
+
 // Check for not passing settings.
 {
   const packed = http2.getPackedSettings();
@@ -124,7 +204,8 @@ http2.getPackedSettings({ enablePush: false });
     0x00, 0x04, 0x00, 0x00, 0x00, 0x64,
     0x00, 0x06, 0x00, 0x00, 0x00, 0x64,
     0x00, 0x02, 0x00, 0x00, 0x00, 0x01,
-    0x00, 0x08, 0x00, 0x00, 0x00, 0x00]);
+    0x00, 0x08, 0x00, 0x00, 0x00, 0x00,
+    0x27, 0x0F, 0x00, 0x00, 0x01, 0x2d]);
 
   [1, true, '', [], {}, NaN].forEach((input) => {
     assert.throws(() => {
@@ -157,6 +238,7 @@ http2.getPackedSettings({ enablePush: false });
   assert.strictEqual(settings.maxHeaderSize, 100);
   assert.strictEqual(settings.enablePush, true);
   assert.strictEqual(settings.enableConnectProtocol, false);
+  assert.deepStrictEqual(settings.customSettings, { '9999': 301 });
 }
 
 {

diff --git a/test/parallel/test-http2-update-settings.js b/test/parallel/test-http2-update-settings.js
@@ -19,7 +19,8 @@ testUpdateSettingsWith({
     'maxHeaderListSize': 1,
     'maxFrameSize': 16385,
     'enablePush': false,
-    'enableConnectProtocol': true
+    'enableConnectProtocol': true,
+    'customSettings': { '9999': 301 }
   }
 });
 testUpdateSettingsWith({