new file mode 100644
--- /dev/null
+++ b/src/event/quic/ngx_event_quic_frames.c
@@ -0,0 +1,912 @@
+
+/*
+ * Copyright (C) Nginx, Inc.
+ */
+
+
+#include <ngx_config.h>
+#include <ngx_core.h>
+#include <ngx_event.h>
+#include <ngx_event_quic_connection.h>
+
+
+#define NGX_QUIC_BUFFER_SIZE  4096
+
+
+static void ngx_quic_free_bufs(ngx_connection_t *c, ngx_chain_t *in);
+static ngx_chain_t *ngx_quic_split_bufs(ngx_connection_t *c, ngx_chain_t *in,
+    size_t len);
+
+static ngx_int_t ngx_quic_buffer_frame(ngx_connection_t *c,
+    ngx_quic_frames_stream_t *stream, ngx_quic_frame_t *f);
+static ngx_int_t ngx_quic_adjust_frame_offset(ngx_connection_t *c,
+    ngx_quic_frame_t *f, uint64_t offset_in);
+
+
+ngx_quic_frame_t *
+ngx_quic_alloc_frame(ngx_connection_t *c)
+{
+    ngx_queue_t            *q;
+    ngx_quic_frame_t       *frame;
+    ngx_quic_connection_t  *qc;
+
+    qc = ngx_quic_get_connection(c);
+
+    if (!ngx_queue_empty(&qc->free_frames)) {
+
+        q = ngx_queue_head(&qc->free_frames);
+        frame = ngx_queue_data(q, ngx_quic_frame_t, queue);
+
+        ngx_queue_remove(&frame->queue);
+
+#ifdef NGX_QUIC_DEBUG_ALLOC
+        ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0,
+                       "quic reuse frame n:%ui", qc->nframes);
+#endif
+
+    } else {
+        frame = ngx_pcalloc(c->pool, sizeof(ngx_quic_frame_t));
+        if (frame == NULL) {
+            return NULL;
+        }
+
+#ifdef NGX_QUIC_DEBUG_ALLOC
+        ++qc->nframes;
+
+        ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0,
+                       "quic alloc frame n:%ui", qc->nframes);
+#endif
+    }
+
+    ngx_memzero(frame, sizeof(ngx_quic_frame_t));
+
+    return frame;
+}
+
+
+void
+ngx_quic_free_frame(ngx_connection_t *c, ngx_quic_frame_t *frame)
+{
+    ngx_quic_connection_t  *qc;
+
+    qc = ngx_quic_get_connection(c);
+
+    if (frame->data) {
+        ngx_quic_free_bufs(c, frame->data);
+    }
+
+    ngx_queue_insert_head(&qc->free_frames, &frame->queue);
+
+#ifdef NGX_QUIC_DEBUG_ALLOC
+    ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0,
+                   "quic free frame n:%ui", qc->nframes);
+#endif
+}
+
+
+static void
+ngx_quic_free_bufs(ngx_connection_t *c, ngx_chain_t *in)
+{
+    ngx_buf_t              *b, *shadow;
+    ngx_chain_t            *cl;
+    ngx_quic_connection_t  *qc;
+
+    qc = ngx_quic_get_connection(c);
+
+    while (in) {
+#ifdef NGX_QUIC_DEBUG_ALLOC
+        ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0,
+                       "quic free buffer n:%ui", qc->nbufs);
+#endif
+
+        cl = in;
+        in = in->next;
+        b = cl->buf;
+
+        if (b->shadow) {
+            if (!b->last_shadow) {
+                b->recycled = 1;
+                ngx_free_chain(c->pool, cl);
+                continue;
+            }
+
+            do {
+                shadow = b->shadow;
+                b->shadow = qc->free_shadow_bufs;
+                qc->free_shadow_bufs = b;
+                b = shadow;
+            } while (b->recycled);
+
+            if (b->shadow) {
+                b->last_shadow = 1;
+                ngx_free_chain(c->pool, cl);
+                continue;
+            }
+
+            cl->buf = b;
+        }
+
+        cl->next = qc->free_bufs;
+        qc->free_bufs = cl;
+    }
+}
+
+
+void
+ngx_quic_free_frames(ngx_connection_t *c, ngx_queue_t *frames)
+{
+    ngx_queue_t       *q;
+    ngx_quic_frame_t  *f;
+
+    do {
+        q = ngx_queue_head(frames);
+
+        if (q == ngx_queue_sentinel(frames)) {
+            break;
+        }
+
+        ngx_queue_remove(q);
+
+        f = ngx_queue_data(q, ngx_quic_frame_t, queue);
+
+        ngx_quic_free_frame(c, f);
+    } while (1);
+}
+
+
+void
+ngx_quic_queue_frame(ngx_quic_connection_t *qc, ngx_quic_frame_t *frame)
+{
+    ngx_quic_send_ctx_t  *ctx;
+
+    ctx = ngx_quic_get_send_ctx(qc, frame->level);
+
+    ngx_queue_insert_tail(&ctx->frames, &frame->queue);
+
+    frame->len = ngx_quic_create_frame(NULL, frame);
+    /* always succeeds */
+
+    if (qc->closing) {
+        return;
+    }
+
+    ngx_post_event(&qc->push, &ngx_posted_events);
+}
+
+
+ngx_int_t
+ngx_quic_split_frame(ngx_connection_t *c, ngx_quic_frame_t *f, size_t len)
+{
+    size_t                     shrink;
+    ngx_quic_frame_t          *nf;
+    ngx_quic_ordered_frame_t  *of, *onf;
+
+    switch (f->type) {
+    case NGX_QUIC_FT_CRYPTO:
+    case NGX_QUIC_FT_STREAM0:
+    case NGX_QUIC_FT_STREAM1:
+    case NGX_QUIC_FT_STREAM2:
+    case NGX_QUIC_FT_STREAM3:
+    case NGX_QUIC_FT_STREAM4:
+    case NGX_QUIC_FT_STREAM5:
+    case NGX_QUIC_FT_STREAM6:
+    case NGX_QUIC_FT_STREAM7:
+        break;
+
+    default:
+        return NGX_DECLINED;
+    }
+
+    if ((size_t) f->len <= len) {
+        return NGX_OK;
+    }
+
+    shrink = f->len - len;
+
+    ngx_log_debug3(NGX_LOG_DEBUG_EVENT, c->log, 0,
+                   "quic split frame now:%uz need:%uz shrink:%uz",
+                   f->len, len, shrink);
+
+    of = &f->u.ord;
+
+    if (of->length <= shrink) {
+        return NGX_DECLINED;
+    }
+
+    of->length -= shrink;
+    f->len = ngx_quic_create_frame(NULL, f);
+
+    if ((size_t) f->len > len) {
+        ngx_log_error(NGX_LOG_ERR, c->log, 0, "could not split QUIC frame");
+        return NGX_ERROR;
+    }
+
+    nf = ngx_quic_alloc_frame(c);
+    if (nf == NULL) {
+        return NGX_ERROR;
+    }
+
+    *nf = *f;
+    onf = &nf->u.ord;
+    onf->offset += of->length;
+    onf->length = shrink;
+    nf->len = ngx_quic_create_frame(NULL, nf);
+
+    nf->data = ngx_quic_split_bufs(c, f->data, of->length);
+    if (nf->data == NGX_CHAIN_ERROR) {
+        return NGX_ERROR;
+    }
+
+    ngx_queue_insert_after(&f->queue, &nf->queue);
+
+    return NGX_OK;
+}
+
+
+static ngx_chain_t *
+ngx_quic_split_bufs(ngx_connection_t *c, ngx_chain_t *in, size_t len)
+{
+    size_t                  n;
+    ngx_buf_t              *b;
+    ngx_chain_t            *out;
+    ngx_quic_connection_t  *qc;
+
+    qc = ngx_quic_get_connection(c);
+
+    while (in) {
+        n = ngx_buf_size(in->buf);
+
+        if (n == len) {
+            out = in->next;
+            in->next = NULL;
+            return out;
+        }
+
+        if (n > len) {
+            break;
+        }
+
+        len -= n;
+        in = in->next;
+    }
+
+    if (in == NULL) {
+        return NULL;
+    }
+
+    /* split in->buf by creating shadow bufs which reference it */
+
+    if (in->buf->shadow == NULL) {
+        if (qc->free_shadow_bufs) {
+            b = qc->free_shadow_bufs;
+            qc->free_shadow_bufs = b->shadow;
+
+        } else {
+            b = ngx_alloc_buf(c->pool);
+            if (b == NULL) {
+                return NGX_CHAIN_ERROR;
+            }
+        }
+
+        *b = *in->buf;
+        b->shadow = in->buf;
+        b->last_shadow = 1;
+        in->buf = b;
+    }
+
+    out = ngx_alloc_chain_link(c->pool);
+    if (out == NULL) {
+        return NGX_CHAIN_ERROR;
+    }
+
+    if (qc->free_shadow_bufs) {
+        b = qc->free_shadow_bufs;
+        qc->free_shadow_bufs = b->shadow;
+
+    } else {
+        b = ngx_alloc_buf(c->pool);
+        if (b == NULL) {
+            ngx_free_chain(c->pool, out);
+            return NGX_CHAIN_ERROR;
+        }
+    }
+
+    out->buf = b;
+    out->next = in->next;
+    in->next = NULL;
+
+    *b = *in->buf;
+    b->last_shadow = 0;
+    b->pos = b->pos + len;
+
+    in->buf->shadow = b;
+    in->buf->last = in->buf->pos + len;
+
+    return out;
+}
+
+
+ngx_chain_t *
+ngx_quic_alloc_buf(ngx_connection_t *c)
+{
+    ngx_buf_t              *b;
+    ngx_chain_t            *cl;
+    ngx_quic_connection_t  *qc;
+
+    qc = ngx_quic_get_connection(c);
+
+    if (qc->free_bufs) {
+        cl = qc->free_bufs;
+        qc->free_bufs = cl->next;
+
+        b = cl->buf;
+        b->pos = b->start;
+        b->last = b->start;
+
+#ifdef NGX_QUIC_DEBUG_ALLOC
+        ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0,
+                       "quic reuse buffer n:%ui", qc->nbufs);
+#endif
+
+        return cl;
+    }
+
+    cl = ngx_alloc_chain_link(c->pool);
+    if (cl == NULL) {
+        return NULL;
+    }
+
+    b = ngx_create_temp_buf(c->pool, NGX_QUIC_BUFFER_SIZE);
+    if (b == NULL) {
+        return NULL;
+    }
+
+    b->tag = (ngx_buf_tag_t) &ngx_quic_alloc_buf;
+
+    cl->buf = b;
+
+#ifdef NGX_QUIC_DEBUG_ALLOC
+    ++qc->nbufs;
+
+    ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0,
+                   "quic alloc buffer n:%ui", qc->nbufs);
+#endif
+
+    return cl;
+}
+
+
+ngx_chain_t *
+ngx_quic_copy_buf(ngx_connection_t *c, u_char *data, size_t len)
+{
+    size_t        n;
+    ngx_buf_t    *b;
+    ngx_chain_t  *cl, *out, **ll;
+
+    out = NULL;
+    ll = &out;
+
+    while (len) {
+        cl = ngx_quic_alloc_buf(c);
+        if (cl == NULL) {
+            return NGX_CHAIN_ERROR;
+        }
+
+        b = cl->buf;
+        n = ngx_min((size_t) (b->end - b->last), len);
+
+        b->last = ngx_cpymem(b->last, data, n);
+
+        data += n;
+        len -= n;
+
+        *ll = cl;
+        ll = &cl->next;
+    }
+
+    *ll = NULL;
+
+    return out;
+}
+
+
+ngx_chain_t *
+ngx_quic_copy_chain(ngx_connection_t *c, ngx_chain_t *in, size_t limit)
+{
+    size_t        n;
+    ngx_buf_t    *b;
+    ngx_chain_t  *cl, *out, **ll;
+
+    out = NULL;
+    ll = &out;
+
+    while (in) {
+        if (!ngx_buf_in_memory(in->buf) || ngx_buf_size(in->buf) == 0) {
+            in = in->next;
+            continue;
+        }
+
+        cl = ngx_quic_alloc_buf(c);
+        if (cl == NULL) {
+            return NGX_CHAIN_ERROR;
+        }
+
+        *ll = cl;
+        ll = &cl->next;
+
+        b = cl->buf;
+
+        while (in && b->last != b->end) {
+
+            n = ngx_min(in->buf->last - in->buf->pos, b->end - b->last);
+
+            if (limit > 0 && n > limit) {
+                n = limit;
+            }
+
+            b->last = ngx_cpymem(b->last, in->buf->pos, n);
+
+            in->buf->pos += n;
+            if (in->buf->pos == in->buf->last) {
+                in = in->next;
+            }
+
+            if (limit > 0) {
+                if (limit == n) {
+                    goto done;
+                }
+
+                limit -= n;
+            }
+        }
+    }
+
+done:
+
+    *ll = NULL;
+
+    return out;
+}
+
+
+ngx_int_t ngx_quic_crypto_input(ngx_connection_t *c,
+    ngx_quic_frame_t *frame, void *data);
+
+
+ngx_int_t
+ngx_quic_handle_ordered_frame(ngx_connection_t *c, ngx_quic_frames_stream_t *fs,
+    ngx_quic_frame_t *frame, ngx_quic_frame_handler_pt handler, void *data)
+{
+    size_t                     full_len;
+    ngx_int_t                  rc;
+    ngx_queue_t               *q;
+    ngx_quic_ordered_frame_t  *f;
+
+    f = &frame->u.ord;
+
+    if (f->offset > fs->received) {
+        ngx_log_debug2(NGX_LOG_DEBUG_EVENT, c->log, 0,
+                       "quic out-of-order frame: expecting:%uL got:%uL",
+                       fs->received, f->offset);
+
+        return ngx_quic_buffer_frame(c, fs, frame);
+    }
+
+    if (f->offset < fs->received) {
+
+        if (ngx_quic_adjust_frame_offset(c, frame, fs->received)
+            == NGX_DONE)
+        {
+            /* old/duplicate data range */
+            return handler == ngx_quic_crypto_input ? NGX_DECLINED : NGX_OK;
+        }
+
+        /* intersecting data range, frame modified */
+    }
+
+    /* f->offset == fs->received */
+
+    rc = handler(c, frame, data);
+    if (rc == NGX_ERROR) {
+        return NGX_ERROR;
+
+    } else if (rc == NGX_DONE) {
+        /* handler destroyed stream, queue no longer exists */
+        return NGX_OK;
+    }
+
+    /* rc == NGX_OK */
+
+    fs->received += f->length;
+
+    /* now check the queue if we can continue with buffered frames */
+
+    do {
+        q = ngx_queue_head(&fs->frames);
+        if (q == ngx_queue_sentinel(&fs->frames)) {
+            break;
+        }
+
+        frame = ngx_queue_data(q, ngx_quic_frame_t, queue);
+        f = &frame->u.ord;
+
+        if (f->offset > fs->received) {
+            /* gap found, nothing more to do */
+            break;
+        }
+
+        full_len = f->length;
+
+        if (f->offset < fs->received) {
+
+            if (ngx_quic_adjust_frame_offset(c, frame, fs->received)
+                == NGX_DONE)
+            {
+                /* old/duplicate data range */
+                ngx_queue_remove(q);
+                fs->total -= f->length;
+
+                ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0,
+                               "quic skipped buffered frame, total:%ui",
+                               fs->total);
+                ngx_quic_free_frame(c, frame);
+                continue;
+            }
+
+            /* frame was adjusted, proceed to input */
+        }
+
+        /* f->offset == fs->received */
+
+        rc = handler(c, frame, data);
+
+        if (rc == NGX_ERROR) {
+            return NGX_ERROR;
+
+        } else if (rc == NGX_DONE) {
+            /* handler destroyed stream, queue no longer exists */
+            return NGX_OK;
+        }
+
+        fs->received += f->length;
+        fs->total -= full_len;
+
+        ngx_queue_remove(q);
+
+        ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0,
+                       "quic consumed buffered frame, total:%ui", fs->total);
+
+        ngx_quic_free_frame(c, frame);
+
+    } while (1);
+
+    return NGX_OK;
+}
+
+
+static ngx_int_t
+ngx_quic_adjust_frame_offset(ngx_connection_t *c, ngx_quic_frame_t *frame,
+    uint64_t offset_in)
+{
+    size_t                     tail, n;
+    ngx_buf_t                 *b;
+    ngx_chain_t               *cl;
+    ngx_quic_ordered_frame_t  *f;
+
+    f = &frame->u.ord;
+
+    tail = offset_in - f->offset;
+
+    if (tail >= f->length) {
+        /* range preceeding already received data or duplicate, ignore */
+
+        ngx_log_debug0(NGX_LOG_DEBUG_EVENT, c->log, 0,
+                       "quic old or duplicate data in ordered frame, ignored");
+        return NGX_DONE;
+    }
+
+    ngx_log_debug0(NGX_LOG_DEBUG_EVENT, c->log, 0,
+                   "quic adjusted ordered frame data start to expected offset");
+
+    /* intersecting range: adjust data size */
+
+    f->offset += tail;
+    f->length -= tail;
+
+    for (cl = frame->data; cl; cl = cl->next) {
+        b = cl->buf;
+        n = ngx_buf_size(b);
+
+        if (n >= tail) {
+            b->pos += tail;
+            break;
+        }
+
+        cl->buf->pos = cl->buf->last;
+        tail -= n;
+    }
+
+    return NGX_OK;
+}
+
+
+static ngx_int_t
+ngx_quic_buffer_frame(ngx_connection_t *c, ngx_quic_frames_stream_t *fs,
+    ngx_quic_frame_t *frame)
+{
+    ngx_queue_t               *q;
+    ngx_quic_frame_t          *dst, *item;
+    ngx_quic_ordered_frame_t  *f, *df;
+
+    ngx_log_debug0(NGX_LOG_DEBUG_EVENT, c->log, 0,
+                   "quic ngx_quic_buffer_frame");
+
+    f = &frame->u.ord;
+
+    /* frame start offset is in the future, buffer it */
+
+    dst = ngx_quic_alloc_frame(c);
+    if (dst == NULL) {
+        return NGX_ERROR;
+    }
+
+    ngx_memcpy(dst, frame, sizeof(ngx_quic_frame_t));
+
+    dst->data = ngx_quic_copy_chain(c, frame->data, 0);
+    if (dst->data == NGX_CHAIN_ERROR) {
+        return NGX_ERROR;
+    }
+
+    df = &dst->u.ord;
+
+    fs->total += f->length;
+
+    ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0,
+                   "quic ordered frame with unexpected offset:"
+                   " buffered total:%ui", fs->total);
+
+    if (ngx_queue_empty(&fs->frames)) {
+        ngx_queue_insert_after(&fs->frames, &dst->queue);
+        return NGX_OK;
+    }
+
+    for (q = ngx_queue_last(&fs->frames);
+         q != ngx_queue_sentinel(&fs->frames);
+         q = ngx_queue_prev(q))
+    {
+        item = ngx_queue_data(q, ngx_quic_frame_t, queue);
+        f = &item->u.ord;
+
+        if (f->offset < df->offset) {
+            ngx_queue_insert_after(q, &dst->queue);
+            return NGX_OK;
+        }
+    }
+
+    ngx_queue_insert_after(&fs->frames, &dst->queue);
+
+    return NGX_OK;
+}
+
+
+#if (NGX_DEBUG)
+
+void
+ngx_quic_log_frame(ngx_log_t *log, ngx_quic_frame_t *f, ngx_uint_t tx)
+{
+    u_char      *p, *last, *pos, *end;
+    ssize_t      n;
+    uint64_t     gap, range, largest, smallest;
+    ngx_uint_t   i;
+    u_char       buf[NGX_MAX_ERROR_STR];
+
+    p = buf;
+    last = buf + sizeof(buf);
+
+    switch (f->type) {
+
+    case NGX_QUIC_FT_CRYPTO:
+        p = ngx_slprintf(p, last, "CRYPTO len:%uL off:%uL",
+                         f->u.crypto.length, f->u.crypto.offset);
+        break;
+
+    case NGX_QUIC_FT_PADDING:
+        p = ngx_slprintf(p, last, "PADDING");
+        break;
+
+    case NGX_QUIC_FT_ACK:
+    case NGX_QUIC_FT_ACK_ECN:
+
+        p = ngx_slprintf(p, last, "ACK n:%ui delay:%uL ",
+                         f->u.ack.range_count, f->u.ack.delay);
+
+        if (f->data) {
+            pos = f->data->buf->pos;
+            end = f->data->buf->last;
+
+        } else {
+            pos = NULL;
+            end = NULL;
+        }
+
+        largest = f->u.ack.largest;
+        smallest = f->u.ack.largest - f->u.ack.first_range;
+
+        if (largest == smallest) {
+            p = ngx_slprintf(p, last, "%uL", largest);
+
+        } else {
+            p = ngx_slprintf(p, last, "%uL-%uL", largest, smallest);
+        }
+
+        for (i = 0; i < f->u.ack.range_count; i++) {
+            n = ngx_quic_parse_ack_range(log, pos, end, &gap, &range);
+            if (n == NGX_ERROR) {
+                break;
+            }
+
+            pos += n;
+
+            largest = smallest - gap - 2;
+            smallest = largest - range;
+
+            if (largest == smallest) {
+                p = ngx_slprintf(p, last, " %uL", largest);
+
+            } else {
+                p = ngx_slprintf(p, last, " %uL-%uL", largest, smallest);
+            }
+        }
+
+        if (f->type == NGX_QUIC_FT_ACK_ECN) {
+            p = ngx_slprintf(p, last, " ECN counters ect0:%uL ect1:%uL ce:%uL",
+                             f->u.ack.ect0, f->u.ack.ect1, f->u.ack.ce);
+        }
+        break;
+
+    case NGX_QUIC_FT_PING:
+        p = ngx_slprintf(p, last, "PING");
+        break;
+
+    case NGX_QUIC_FT_NEW_CONNECTION_ID:
+        p = ngx_slprintf(p, last,
+                         "NEW_CONNECTION_ID seq:%uL retire:%uL len:%ud",
+                         f->u.ncid.seqnum, f->u.ncid.retire, f->u.ncid.len);
+        break;
+
+    case NGX_QUIC_FT_RETIRE_CONNECTION_ID:
+        p = ngx_slprintf(p, last, "RETIRE_CONNECTION_ID seqnum:%uL",
+                         f->u.retire_cid.sequence_number);
+        break;
+
+    case NGX_QUIC_FT_CONNECTION_CLOSE:
+    case NGX_QUIC_FT_CONNECTION_CLOSE_APP:
+        p = ngx_slprintf(p, last, "CONNECTION_CLOSE%s err:%ui",
+                         f->type == NGX_QUIC_FT_CONNECTION_CLOSE ? "" : "_APP",
+                         f->u.close.error_code);
+
+        if (f->u.close.reason.len) {
+            p = ngx_slprintf(p, last, " %V", &f->u.close.reason);
+        }
+
+        if (f->type == NGX_QUIC_FT_CONNECTION_CLOSE) {
+            p = ngx_slprintf(p, last, " ft:%ui", f->u.close.frame_type);
+        }
+
+        break;
+
+    case NGX_QUIC_FT_STREAM0:
+    case NGX_QUIC_FT_STREAM1:
+    case NGX_QUIC_FT_STREAM2:
+    case NGX_QUIC_FT_STREAM3:
+    case NGX_QUIC_FT_STREAM4:
+    case NGX_QUIC_FT_STREAM5:
+    case NGX_QUIC_FT_STREAM6:
+    case NGX_QUIC_FT_STREAM7:
+
+        p = ngx_slprintf(p, last, "STREAM id:0x%xL", f->u.stream.stream_id);
+
+        if (f->u.stream.off) {
+            p = ngx_slprintf(p, last, " off:%uL", f->u.stream.offset);
+        }
+
+        if (f->u.stream.len) {
+            p = ngx_slprintf(p, last, " len:%uL", f->u.stream.length);
+        }
+
+        if (f->u.stream.fin) {
+            p = ngx_slprintf(p, last, " fin:1");
+        }
+
+#ifdef NGX_QUIC_DEBUG_FRAMES
+        {
+            ngx_chain_t  *cl;
+
+            p = ngx_slprintf(p, last, " data:");
+
+            for (cl = f->data; cl; cl = cl->next) {
+                p = ngx_slprintf(p, last, "%*xs",
+                                 cl->buf->last - cl->buf->pos, cl->buf->pos);
+            }
+        }
+#endif
+
+        break;
+
+    case NGX_QUIC_FT_MAX_DATA:
+        p = ngx_slprintf(p, last, "MAX_DATA max_data:%uL on recv",
+                         f->u.max_data.max_data);
+        break;
+
+    case NGX_QUIC_FT_RESET_STREAM:
+        p = ngx_slprintf(p, last, "RESET_STREAM"
+                        " id:0x%xL error_code:0x%xL final_size:0x%xL",
+                        f->u.reset_stream.id, f->u.reset_stream.error_code,
+                        f->u.reset_stream.final_size);
+        break;
+
+    case NGX_QUIC_FT_STOP_SENDING:
+        p = ngx_slprintf(p, last, "STOP_SENDING id:0x%xL err:0x%xL",
+                         f->u.stop_sending.id, f->u.stop_sending.error_code);
+        break;
+
+    case NGX_QUIC_FT_STREAMS_BLOCKED:
+    case NGX_QUIC_FT_STREAMS_BLOCKED2:
+        p = ngx_slprintf(p, last, "STREAMS_BLOCKED limit:%uL bidi:%ui",
+                         f->u.streams_blocked.limit, f->u.streams_blocked.bidi);
+        break;
+
+    case NGX_QUIC_FT_MAX_STREAMS:
+    case NGX_QUIC_FT_MAX_STREAMS2:
+        p = ngx_slprintf(p, last, "MAX_STREAMS limit:%uL bidi:%ui",
+                         f->u.max_streams.limit, f->u.max_streams.bidi);
+        break;
+
+    case NGX_QUIC_FT_MAX_STREAM_DATA:
+        p = ngx_slprintf(p, last, "MAX_STREAM_DATA id:0x%xL limit:%uL",
+                         f->u.max_stream_data.id, f->u.max_stream_data.limit);
+        break;
+
+
+    case NGX_QUIC_FT_DATA_BLOCKED:
+        p = ngx_slprintf(p, last, "DATA_BLOCKED limit:%uL",
+                         f->u.data_blocked.limit);
+        break;
+
+    case NGX_QUIC_FT_STREAM_DATA_BLOCKED:
+        p = ngx_slprintf(p, last, "STREAM_DATA_BLOCKED id:0x%xL limit:%uL",
+                         f->u.stream_data_blocked.id,
+                         f->u.stream_data_blocked.limit);
+        break;
+
+    case NGX_QUIC_FT_PATH_CHALLENGE:
+        p = ngx_slprintf(p, last, "PATH_CHALLENGE data:0x%*xs",
+                         sizeof(f->u.path_challenge.data),
+                         f->u.path_challenge.data);
+        break;
+
+    case NGX_QUIC_FT_PATH_RESPONSE:
+        p = ngx_slprintf(p, last, "PATH_RESPONSE data:0x%*xs",
+                         sizeof(f->u.path_challenge.data),
+                         f->u.path_challenge.data);
+        break;
+
+    case NGX_QUIC_FT_NEW_TOKEN:
+        p = ngx_slprintf(p, last, "NEW_TOKEN");
+        break;
+
+    case NGX_QUIC_FT_HANDSHAKE_DONE:
+        p = ngx_slprintf(p, last, "HANDSHAKE DONE");
+        break;
+
+    default:
+        p = ngx_slprintf(p, last, "unknown type 0x%xi", f->type);
+        break;
+    }
+
+    ngx_log_debug4(NGX_LOG_DEBUG_EVENT, log, 0, "quic frame %s %s %*s",
+                   tx ? "tx" : "rx", ngx_quic_level_name(f->level),
+                   p - buf, buf);
+}
+
+#endif