Release 4.8.2 (#663)

- [FIX] Reject HTTP messages with multiple conflicting content-length
  fields.
- [FIX] Use ls-qpack v2.6.5 to pick up a fix for a latent use-after-free.
- [IMPROVEMENT] Handle unexpected stream readv/writev args correctly.
- [DOCS] Update docs about the now-defunct push promises.

Author: dtikhonov

CHANGELOG

@@ -1,3 +1,11 @@
+2026-06-28
+    - 4.8.2
+    - [FIX] Reject HTTP messages with multiple conflicting content-length
+      fields.
+    - [FIX] Use ls-qpack v2.6.5 to pick up a fix for a latent use-after-free.
+    - [IMPROVEMENT] Handle unexpected stream readv/writev args correctly.
+    - [DOCS] Update docs about the now-defunct push promises.
+
 2026-06-20
     - 4.8.1
     - [FIX] Send controller: bytes-scheduled underflow (issue #652).

docs/apiref.rst

@@ -420,19 +420,9 @@ settings structure:
 
     .. member:: int             es_support_push
 
-       Setting this value to 0 means that
-
-       For client:
-
-       1. we send a SETTINGS frame to indicate that we do not support server
-          push; and
-       2. all incoming pushed streams get reset immediately.
-
-       (For maximum effect, set es_max_streams_in to 0.)
-
-       For server:
-
-       1. :func:`lsquic_conn_push_stream()` will return -1.
+       Server push is not supported.  This setting is retained for API
+       compatibility.  :func:`lsquic_conn_is_push_enabled()` returns false and
+       :func:`lsquic_conn_push_stream()` returns 1.
 
     .. member:: int             es_support_tcid0
 
@@ -1009,7 +999,7 @@ out of date.  Please check your :file:`lsquic.h` for actual values.*
 
 .. macro:: LSQUIC_DF_SUPPORT_PUSH
 
-    Push promises are supported by default.
+    Server push is not supported.
 
 .. macro:: LSQUIC_DF_SUPPORT_TCID0
 
@@ -1868,7 +1858,8 @@ fields yourself.  In that case, the header set must be "read" from the stream vi
         :param stream: Stream with which the header set is associated.  May be set
                        to NULL in server mode.
         :param is_push_promise: Boolean value indicating whether this header set is
-                                for a push promise.
+                                for a push promise.  Server push is not supported;
+                                this parameter is retained for API compatibility.
         :return: Pointer to user-defined header set object.
 
         Create a new header set.  This object is (and must be) fetched from a
@@ -1946,46 +1937,52 @@ fields yourself.  In that case, the header set must be "read" from the stream vi
 Push Promises
 -------------
 
+Server push is not supported.  The following functions remain in the API for
+compatibility.
+
 .. function:: int lsquic_conn_push_stream (lsquic_conn_t *conn, void *hdr_set, lsquic_stream_t *stream, const lsquic_http_headers_t *headers)
 
     :return:
 
-        - 0: Stream pushed successfully.
-        - 1: Stream push failed because it is disabled or because we hit
-             stream limit or connection is going away.
-        - -1: Stream push failed because of an internal error.
-
-    A server may push a stream.  This call creates a new stream in reference
-    to stream ``stream``.  It will behave as if the client made a request: it will
-    trigger ``on_new_stream()`` event and it can be used as a regular client-initiated stream.
+        - 1: Stream push failed because server push is not supported.
 
-    ``hdr_set`` must be set.  It is passed as-is to :func:`lsquic_stream_get_hset()`.
+    This function is retained for API compatibility.
 
 .. function:: int lsquic_conn_is_push_enabled (lsquic_conn_t *conn)
 
-    :return: Boolean value indicating whether push promises are enabled.
+    :return: 0.
 
-    Only makes sense in server mode: the client cannot push a stream and this
-    function always returns false in client mode.
+    This function is retained for API compatibility.
 
 .. function:: int lsquic_stream_is_pushed (const lsquic_stream_t *stream)
 
-    :return: Boolean value indicating whether this is a pushed stream.
+    :return: Boolean value indicating whether this is a legacy pushed stream.
+
+    This function is retained for API compatibility.  Current LSQUIC versions
+    do not create pushed streams.
 
 .. function:: int lsquic_stream_refuse_push (lsquic_stream_t *stream)
 
-    Refuse pushed stream.  Call it from ``on_new_stream()``.  No need to
-    call :func:`lsquic_stream_close()` after this.  ``on_close()`` will be called.
+    Refuse a legacy pushed stream.
+
+    This function is retained for API compatibility.  Current LSQUIC versions
+    do not create pushed streams.
 
 .. function:: int lsquic_stream_push_info (const lsquic_stream_t *stream, lsquic_stream_id_t *ref_stream_id, void **hdr_set)
 
-    Get information associated with pushed stream
+    Get information associated with a legacy pushed stream.
 
-    :param ref_stream_id: Stream ID in response to which push promise was sent.
-    :param hdr_set: Header set. This object was passed to or generated by :func:`lsquic_conn_push_stream()`.
+    :param ref_stream_id: Stream ID in response to which a push promise would
+                          have been sent.
+    :param hdr_set: Header set.  In legacy push-enabled versions, this object
+                    was passed to or generated by
+                    :func:`lsquic_conn_push_stream()`.
 
     :return: 0 on success and -1 if this is not a pushed stream.
 
+    This function is retained for API compatibility.  Current LSQUIC versions
+    do not create pushed streams.
+
 Stream Priorities
 -----------------
 

docs/conf.py

@@ -26,7 +26,7 @@
 # The short X.Y version
 version = u'4.8'
 # The full version, including alpha/beta/rc tags
-release = u'4.8.1'
+release = u'4.8.2'
 
 
 # -- General configuration ---------------------------------------------------

docs/index.rst

@@ -33,7 +33,6 @@ LSQUIC supports nearly all QUIC and HTTP/3 features, including
 - Spin bits (allowing network observer to calculate a connection's RTT)
 - Path migration
 - NAT rebinding
-- Push promises
 - TLS Key updates
 - Extensions:
 

docs/internals.rst

@@ -720,10 +720,6 @@ internally:
 
    -  QPACK decoder stream
 
-In addition, HTTP/3 push promises use unidirectional streams. In the
-code, we make a unidirectional stream simply by closing one end in the
-constructor.
-
 All of the use cases above are handled by the single module,
 lsquic_stream. The differences in behavior -- gQUIC vs IETF QUIC, HTTP
 vs non-HTTP -- are handled either by explicit conditionals or via
@@ -752,7 +748,7 @@ size of 2\ :sup:`14` - 1 bytes. You will find literal ``2`` or ``3`` values
 in code that deals with writing HQ frames.
 
 If the HQ frame's size is known in advance (SHF_FIXED_SIZE) -- which is
-the case for HEADERS and PUSH_PROMISE frames -- then the HQ header
+the case for HEADERS frames -- then the HQ header
 contents are written immediately. Otherwise, ``shf_frame_ptr`` points to
 the bytes in the packet where the HQ header was written, to be filled in
 later.
@@ -1054,24 +1050,17 @@ This is done to minimize the goodput overhead incurred by the DATA frame header.
 
 .. image:: stream-http3-framing.png
 
-There are a couple of things that do not fit into this model:
-
-1. The HEADERS frame is fixed size [1]_. It is generated separately
-   (written by QPACK encoder into a buffer on the stack) and later
-   copied into the stream. (See the ``send_headers_ietf`` function.) It
-   can happen that the whole buffer cannot be written. In that case,
-   a rather complicated dance of buffering the unwritten HEADERS
-   frame bytes is performed. Here, the "on stream write" callback is
-   replaced with an internal callback (see the ``select_on_write``
-   function) and user interaction is prohibited until the whole of
-   the HEADERS frame is written to the stream.
-
-2. Push promise streams are even weirder. In addition to the HEADERS
-   handling above, the push promise stream must begin with a
-   variable-integer Push ID. To make this fit into the framed stream
-   model, the code makes up the concept of a "phantom" HTTP/3 frame.
-   This type of frame's header is not written. This allows us to
-   treat the Push ID as the payload of a regular HTTP/3 frame.
+There is one thing that does not fit into this model:
+
+The HEADERS frame is fixed size [1]_. It is generated separately
+(written by QPACK encoder into a buffer on the stack) and later
+copied into the stream. (See the ``send_headers_ietf`` function.) It
+can happen that the whole buffer cannot be written. In that case,
+a rather complicated dance of buffering the unwritten HEADERS
+frame bytes is performed. Here, the "on stream write" callback is
+replaced with an internal callback (see the ``select_on_write``
+function) and user interaction is prohibited until the whole of
+the HEADERS frame is written to the stream.
 
 The framing code has had its share of bugs. Because of that, there is a
 dedicated unit test program just for the framing code,
@@ -1675,8 +1664,8 @@ fc_last_stream_id
 ID of the last created stream.
 
 Used to assign ID to streams created by this side of the connection.
-Clients create odd-numbered streams, while servers initiate
-even-numbered streams (push promises).
+Clients create odd-numbered streams.  The server-created, even-numbered
+stream path was used by the now-removed push-promise support.
 
 fc_max_peer_stream_id
 ---------------------
@@ -2408,7 +2397,8 @@ stored; they are not in the ``ifc_pub.all_streams`` hash.
 ifc_u.ser
 ---------
 
-The server-specific state is only about push promises.
+The server-specific state tracks MAX_PUSH_ID for push-related HTTP/3
+error handling.  LSQUIC does not implement server push.
 
 ifc_idle_to
 -----------

include/lsquic.h

@@ -27,7 +27,7 @@ extern "C" {
 
 #define LSQUIC_MAJOR_VERSION 4
 #define LSQUIC_MINOR_VERSION 8
-#define LSQUIC_PATCH_VERSION 1
+#define LSQUIC_PATCH_VERSION 2
 
 #define LSQUIC_QUOTE(x)     #x
 #define LSQUIC_SVAL(v)      LSQUIC_QUOTE(v)
@@ -1771,25 +1771,18 @@ void *
 lsquic_stream_get_hset (lsquic_stream_t *);
 
 /**
- * A server may push a stream.  This call creates a new stream in reference
- * to stream `s'.  It will behave as if the client made a request: it will
- * trigger on_new_stream() event and it can be used as a regular client-
- * initiated stream.
+ * Server push is not supported.  This function is retained for API
+ * compatibility.
  *
- * `hdr_set' must be set.  It is passed as-is to @lsquic_stream_get_hset.
- *
- * @retval  0   Stream pushed successfully.
- * @retval  1   Stream push failed because it is disabled or because we hit
- *                stream limit or connection is going away.
- * @retval -1   Stream push failed because of an internal error.
+ * @retval  1   Stream push failed because server push is not supported.
  */
 int
 lsquic_conn_push_stream (lsquic_conn_t *c, void *hdr_set, lsquic_stream_t *s,
     const lsquic_http_headers_t *headers);
 
 /**
- * Only makes sense in server mode: the client cannot push a stream and this
- * function always returns false in client mode.
+ * Server push is not supported.  This function is retained for API
+ * compatibility and always returns false.
  */
 int
 lsquic_conn_is_push_enabled (lsquic_conn_t *);
@@ -1832,7 +1825,10 @@ lsquic_stream_get_ctx (const lsquic_stream_t *s);
 void
 lsquic_stream_set_ctx (lsquic_stream_t *stream, lsquic_stream_ctx_t *ctx);
 
-/** Returns true if this is a pushed stream */
+/**
+ * Retained for API compatibility with removed server push support.  Current
+ * LSQUIC versions do not create pushed streams.
+ */
 int
 lsquic_stream_is_pushed (const lsquic_stream_t *s);
 
@@ -1844,22 +1840,21 @@ int
 lsquic_stream_is_rejected (const lsquic_stream_t *s);
 
 /**
- * Refuse pushed stream.  Call it from @ref on_new_stream.
- *
- * No need to call lsquic_stream_close() after this.  on_close will be called.
+ * Retained for API compatibility with removed server push support.  Current
+ * LSQUIC versions do not create pushed streams.
  *
- * @see lsquic_stream_is_pushed
+ * @see lsquic_stream_is_pushed.
  */
 int
 lsquic_stream_refuse_push (lsquic_stream_t *s);
 
 /**
- * Get information associated with pushed stream:
+ * Retained for API compatibility with removed server push support.  Current
+ * LSQUIC versions do not create pushed streams.
  *
- * @param ref_stream_id   Stream ID in response to which push promise was
- *                            sent.
- * @param hdr_set         Header set.  This object was passed to or generated
- *                            by @ref lsquic_conn_push_stream().
+ * @param ref_stream_id   Legacy output parameter for stream ID in response
+ *                            to which a push promise would have been sent.
+ * @param hdr_set         Legacy output parameter for the push header set.
  *
  * @retval   0  Success.
  * @retval  -1  This is not a pushed stream.