Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

18 files changed, 6444 insertions, 0 deletions

diff --git a/third_party/rust/neqo-qpack/.cargo-checksum.json b/third_party/rust/neqo-qpack/.cargo-checksum.json
new file mode 100644
index 0000000000..2bbec5df43
--- /dev/null
+++ b/third_party/rust/neqo-qpack/.cargo-checksum.json
@@ -0,0 +1 @@
+{"files":{"Cargo.toml":"2eabb2ad2846a08b51b306634ed75dc14ab3a43738b1190e3b4c4f2beb00b8e2","src/decoder.rs":"7e468d59adff1fa9373cbb703d13a7503f721a89bebafd049feaf0308a39b606","src/decoder_instructions.rs":"d991d70e51f079bc5b30d3982fd0176edfa9bb7ba14c17a20ec3eea878c56206","src/encoder.rs":"e026da38c2c3410a4e9aa330cda09ac411008772dd66d262d6c375601cebf481","src/encoder_instructions.rs":"86e3abbd9cf94332041326ac6cf806ed64623e3fd38dbc0385b1f63c37e73fd9","src/header_block.rs":"3925476df69b90d950594faadc5cb24c374d46de8c75a374a235f0d27323a7d8","src/huffman.rs":"8b0b2ea069c2a6eb6677b076b99b08ac0d29eabe1f2bbbab37f18f49187ef276","src/huffman_decode_helper.rs":"81309e27ff8f120a10c0b1598888ded21b76e297dc02cea8c7378d6a6627d62a","src/huffman_table.rs":"06fea766a6276ac56c7ee0326faed800a742c15fda1f33bf2513e6cc6a5e6d27","src/lib.rs":"196114397c2b1bf6ef154206018f519b012789cf712e89b069a7616d7278ef3a","src/prefix.rs":"fb4a9acbcf6fd3178f4474404cd3d3b131abca934f69fe14a9d744bc7e636dc5","src/qlog.rs":"e320007ea8309546b26f9c0019ab8722da80dbd38fa976233fd8ae19a0af637c","src/qpack_send_buf.rs":"14d71310c260ee15ea40a783998b507c968eef12db2892b47c689e872b5242a5","src/reader.rs":"b9a7dccd726f471fc24f1d3304f03ac0a039c0828aac7b33c927be07d395c655","src/static_table.rs":"fda9d5c6f38f94b0bf92d3afdf8432dce6e27e189736596e16727090c77b78ec","src/stats.rs":"624dfa3b40858c304097bb0ce5b1be1bb4d7916b1abfc222f1aa705907009730","src/table.rs":"05dbec6483bb24c9fc8d721b70fdfefc2df53b458488b55104147f13c386a47d"},"package":null}
\ No newline at end of file
diff --git a/third_party/rust/neqo-qpack/Cargo.toml b/third_party/rust/neqo-qpack/Cargo.toml
new file mode 100644
index 0000000000..7df63b7bf6
--- /dev/null
+++ b/third_party/rust/neqo-qpack/Cargo.toml
@@ -0,0 +1,45 @@
+# THIS FILE IS AUTOMATICALLY GENERATED BY CARGO
+#
+# When uploading crates to the registry Cargo will automatically
+# "normalize" Cargo.toml files for maximal compatibility
+# with all versions of Cargo and also rewrite `path` dependencies
+# to registry (e.g., crates.io) dependencies.
+#
+# If you are reading this file be aware that the original Cargo.toml
+# will likely look very different (and much more reasonable).
+# See Cargo.toml.orig for the original contents.
+
+[package]
+edition = "2018"
+rust-version = "1.70.0"
+name = "neqo-qpack"
+version = "0.7.0"
+authors = ["Dragana Damjanovic <dragana.damjano@gmail.com>"]
+license = "MIT OR Apache-2.0"
+
+[dependencies]
+lazy_static = "~1.4.0"
+static_assertions = "~1.1.0"
+
+[dependencies.log]
+version = "~0.4.17"
+default-features = false
+
+[dependencies.neqo-common]
+path = "./../neqo-common"
+
+[dependencies.neqo-crypto]
+path = "./../neqo-crypto"
+
+[dependencies.neqo-transport]
+path = "./../neqo-transport"
+
+[dependencies.qlog]
+git = "https://github.com/cloudflare/quiche"
+rev = "09ea4b244096a013071cfe2175bbf2945fb7f8d1"
+
+[dev-dependencies.test-fixture]
+path = "../test-fixture"
+
+[features]
+deny-warnings = []
diff --git a/third_party/rust/neqo-qpack/src/decoder.rs b/third_party/rust/neqo-qpack/src/decoder.rs
new file mode 100644
index 0000000000..2119db0256
--- /dev/null
+++ b/third_party/rust/neqo-qpack/src/decoder.rs
@@ -0,0 +1,825 @@
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use std::convert::TryFrom;
+
+use neqo_common::{qdebug, Header};
+use neqo_transport::{Connection, StreamId};
+
+use crate::{
+    decoder_instructions::DecoderInstruction,
+    encoder_instructions::{DecodedEncoderInstruction, EncoderInstructionReader},
+    header_block::{HeaderDecoder, HeaderDecoderResult},
+    qpack_send_buf::QpackData,
+    reader::ReceiverConnWrapper,
+    stats::Stats,
+    table::HeaderTable,
+    Error, QpackSettings, Res,
+};
+
+pub const QPACK_UNI_STREAM_TYPE_DECODER: u64 = 0x3;
+
+#[derive(Debug)]
+pub struct QPackDecoder {
+    instruction_reader: EncoderInstructionReader,
+    table: HeaderTable,
+    acked_inserts: u64,
+    max_entries: u64,
+    send_buf: QpackData,
+    local_stream_id: Option<StreamId>,
+    max_table_size: u64,
+    max_blocked_streams: usize,
+    blocked_streams: Vec<(StreamId, u64)>, // stream_id and requested inserts count.
+    stats: Stats,
+}
+
+impl QPackDecoder {
+    /// # Panics
+    ///
+    /// If settings include invalid values.
+    #[must_use]
+    pub fn new(qpack_settings: &QpackSettings) -> Self {
+        qdebug!("Decoder: creating a new qpack decoder.");
+        let mut send_buf = QpackData::default();
+        send_buf.encode_varint(QPACK_UNI_STREAM_TYPE_DECODER);
+        Self {
+            instruction_reader: EncoderInstructionReader::new(),
+            table: HeaderTable::new(false),
+            acked_inserts: 0,
+            max_entries: qpack_settings.max_table_size_decoder >> 5,
+            send_buf,
+            local_stream_id: None,
+            max_table_size: qpack_settings.max_table_size_decoder,
+            max_blocked_streams: usize::from(qpack_settings.max_blocked_streams),
+            blocked_streams: Vec::new(),
+            stats: Stats::default(),
+        }
+    }
+
+    #[must_use]
+    fn capacity(&self) -> u64 {
+        self.table.capacity()
+    }
+
+    #[must_use]
+    pub fn get_max_table_size(&self) -> u64 {
+        self.max_table_size
+    }
+
+    /// # Panics
+    ///
+    /// If the number of blocked streams is too large.
+    #[must_use]
+    pub fn get_blocked_streams(&self) -> u16 {
+        u16::try_from(self.max_blocked_streams).unwrap()
+    }
+
+    /// returns a list of unblocked streams
+    ///
+    /// # Errors
+    ///
+    /// May return: `ClosedCriticalStream` if stream has been closed or `EncoderStream`
+    /// in case of any other transport error.
+    pub fn receive(&mut self, conn: &mut Connection, stream_id: StreamId) -> Res<Vec<StreamId>> {
+        let base_old = self.table.base();
+        self.read_instructions(conn, stream_id)
+            .map_err(|e| map_error(&e))?;
+        let base_new = self.table.base();
+        if base_old == base_new {
+            return Ok(Vec::new());
+        }
+
+        let r = self
+            .blocked_streams
+            .iter()
+            .filter_map(|(id, req)| if *req <= base_new { Some(*id) } else { None })
+            .collect::<Vec<_>>();
+        self.blocked_streams.retain(|(_, req)| *req > base_new);
+        Ok(r)
+    }
+
+    fn read_instructions(&mut self, conn: &mut Connection, stream_id: StreamId) -> Res<()> {
+        let mut recv = ReceiverConnWrapper::new(conn, stream_id);
+        loop {
+            match self.instruction_reader.read_instructions(&mut recv) {
+                Ok(instruction) => self.execute_instruction(instruction)?,
+                Err(Error::NeedMoreData) => break Ok(()),
+                Err(e) => break Err(e),
+            }
+        }
+    }
+
+    fn execute_instruction(&mut self, instruction: DecodedEncoderInstruction) -> Res<()> {
+        match instruction {
+            DecodedEncoderInstruction::Capacity { value } => self.set_capacity(value)?,
+            DecodedEncoderInstruction::InsertWithNameRefStatic { index, value } => {
+                Error::map_error(
+                    self.table.insert_with_name_ref(true, index, &value),
+                    Error::EncoderStream,
+                )?;
+                self.stats.dynamic_table_inserts += 1;
+            }
+            DecodedEncoderInstruction::InsertWithNameRefDynamic { index, value } => {
+                Error::map_error(
+                    self.table.insert_with_name_ref(false, index, &value),
+                    Error::EncoderStream,
+                )?;
+                self.stats.dynamic_table_inserts += 1;
+            }
+            DecodedEncoderInstruction::InsertWithNameLiteral { name, value } => {
+                Error::map_error(
+                    self.table.insert(&name, &value).map(|_| ()),
+                    Error::EncoderStream,
+                )?;
+                self.stats.dynamic_table_inserts += 1;
+            }
+            DecodedEncoderInstruction::Duplicate { index } => {
+                Error::map_error(self.table.duplicate(index), Error::EncoderStream)?;
+                self.stats.dynamic_table_inserts += 1;
+            }
+            DecodedEncoderInstruction::NoInstruction => {
+                unreachable!("This can be call only with an instruction.");
+            }
+        }
+        Ok(())
+    }
+
+    fn set_capacity(&mut self, cap: u64) -> Res<()> {
+        qdebug!([self], "received instruction capacity cap={}", cap);
+        if cap > self.max_table_size {
+            return Err(Error::EncoderStream);
+        }
+        self.table.set_capacity(cap)
+    }
+
+    fn header_ack(&mut self, stream_id: StreamId, required_inserts: u64) {
+        DecoderInstruction::HeaderAck { stream_id }.marshal(&mut self.send_buf);
+        if required_inserts > self.acked_inserts {
+            self.acked_inserts = required_inserts;
+        }
+    }
+
+    pub fn cancel_stream(&mut self, stream_id: StreamId) {
+        if self.table.capacity() > 0 {
+            self.blocked_streams.retain(|(id, _)| *id != stream_id);
+            DecoderInstruction::StreamCancellation { stream_id }.marshal(&mut self.send_buf);
+        }
+    }
+
+    /// # Errors
+    ///
+    /// May return an error in case of any transport error. TODO: define transport errors.
+    ///
+    /// # Panics
+    ///
+    /// Never, but rust doesn't know that.
+    #[allow(clippy::map_err_ignore)]
+    pub fn send(&mut self, conn: &mut Connection) -> Res<()> {
+        // Encode increment instruction if needed.
+        let increment = self.table.base() - self.acked_inserts;
+        if increment > 0 {
+            DecoderInstruction::InsertCountIncrement { increment }.marshal(&mut self.send_buf);
+            self.acked_inserts = self.table.base();
+        }
+        if self.send_buf.len() != 0 && self.local_stream_id.is_some() {
+            let r = conn
+                .stream_send(self.local_stream_id.unwrap(), &self.send_buf[..])
+                .map_err(|_| Error::DecoderStream)?;
+            qdebug!([self], "{} bytes sent.", r);
+            self.send_buf.read(r);
+        }
+        Ok(())
+    }
+
+    /// # Errors
+    ///
+    /// May return `DecompressionFailed` if header block is incorrect or incomplete.
+    pub fn refers_dynamic_table(&self, buf: &[u8]) -> Res<bool> {
+        HeaderDecoder::new(buf).refers_dynamic_table(self.max_entries, self.table.base())
+    }
+
+    /// This function returns None if the stream is blocked waiting for table insertions.
+    /// 'buf' must contain the complete header block.
+    ///
+    /// # Errors
+    ///
+    /// May return `DecompressionFailed` if header block is incorrect or incomplete.
+    ///
+    /// # Panics
+    ///
+    /// When there is a programming error.
+    pub fn decode_header_block(
+        &mut self,
+        buf: &[u8],
+        stream_id: StreamId,
+    ) -> Res<Option<Vec<Header>>> {
+        qdebug!([self], "decode header block.");
+        let mut decoder = HeaderDecoder::new(buf);
+
+        match decoder.decode_header_block(&self.table, self.max_entries, self.table.base()) {
+            Ok(HeaderDecoderResult::Blocked(req_insert_cnt)) => {
+                if self.blocked_streams.len() > self.max_blocked_streams {
+                    Err(Error::DecompressionFailed)
+                } else {
+                    let r = self
+                        .blocked_streams
+                        .iter()
+                        .filter_map(|(id, req)| if *id == stream_id { Some(*req) } else { None })
+                        .collect::<Vec<_>>();
+                    if !r.is_empty() {
+                        debug_assert!(r.len() == 1);
+                        debug_assert!(r[0] == req_insert_cnt);
+                        return Ok(None);
+                    }
+                    self.blocked_streams.push((stream_id, req_insert_cnt));
+                    Ok(None)
+                }
+            }
+            Ok(HeaderDecoderResult::Headers(h)) => {
+                if decoder.get_req_insert_cnt() != 0 {
+                    self.header_ack(stream_id, decoder.get_req_insert_cnt());
+                    self.stats.dynamic_table_references += 1;
+                }
+                Ok(Some(h))
+            }
+            Err(_) => Err(Error::DecompressionFailed),
+        }
+    }
+
+    /// # Panics
+    ///
+    /// When a stream has already been added.
+    pub fn add_send_stream(&mut self, stream_id: StreamId) {
+        assert!(
+            self.local_stream_id.is_none(),
+            "Adding multiple local streams"
+        );
+        self.local_stream_id = Some(stream_id);
+    }
+
+    #[must_use]
+    pub fn local_stream_id(&self) -> Option<StreamId> {
+        self.local_stream_id
+    }
+
+    #[must_use]
+    pub fn stats(&self) -> Stats {
+        self.stats.clone()
+    }
+}
+
+impl ::std::fmt::Display for QPackDecoder {
+    fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
+        write!(f, "QPackDecoder {}", self.capacity())
+    }
+}
+
+fn map_error(err: &Error) -> Error {
+    if *err == Error::ClosedCriticalStream {
+        Error::ClosedCriticalStream
+    } else {
+        Error::EncoderStream
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::{convert::TryFrom, mem};
+
+    use neqo_common::Header;
+    use neqo_transport::{StreamId, StreamType};
+    use test_fixture::now;
+
+    use super::{Connection, Error, QPackDecoder, Res};
+    use crate::QpackSettings;
+
+    const STREAM_0: StreamId = StreamId::new(0);
+
+    struct TestDecoder {
+        decoder: QPackDecoder,
+        send_stream_id: StreamId,
+        recv_stream_id: StreamId,
+        conn: Connection,
+        peer_conn: Connection,
+    }
+
+    fn connect() -> TestDecoder {
+        let (mut conn, mut peer_conn) = test_fixture::connect();
+
+        // create a stream
+        let recv_stream_id = peer_conn.stream_create(StreamType::UniDi).unwrap();
+        let send_stream_id = conn.stream_create(StreamType::UniDi).unwrap();
+
+        // create a decoder
+        let mut decoder = QPackDecoder::new(&QpackSettings {
+            max_table_size_encoder: 0,
+            max_table_size_decoder: 300,
+            max_blocked_streams: 100,
+        });
+        decoder.add_send_stream(send_stream_id);
+
+        TestDecoder {
+            decoder,
+            send_stream_id,
+            recv_stream_id,
+            conn,
+            peer_conn,
+        }
+    }
+
+    fn recv_instruction(decoder: &mut TestDecoder, encoder_instruction: &[u8], res: &Res<()>) {
+        _ = decoder
+            .peer_conn
+            .stream_send(decoder.recv_stream_id, encoder_instruction)
+            .unwrap();
+        let out = decoder.peer_conn.process(None, now());
+        mem::drop(decoder.conn.process(out.as_dgram_ref(), now()));
+        assert_eq!(
+            decoder
+                .decoder
+                .read_instructions(&mut decoder.conn, decoder.recv_stream_id),
+            *res
+        );
+    }
+
+    fn send_instructions_and_check(decoder: &mut TestDecoder, decoder_instruction: &[u8]) {
+        decoder.decoder.send(&mut decoder.conn).unwrap();
+        let out = decoder.conn.process(None, now());
+        mem::drop(decoder.peer_conn.process(out.as_dgram_ref(), now()));
+        let mut buf = [0_u8; 100];
+        let (amount, fin) = decoder
+            .peer_conn
+            .stream_recv(decoder.send_stream_id, &mut buf)
+            .unwrap();
+        assert!(!fin);
+        assert_eq!(&buf[..amount], decoder_instruction);
+    }
+
+    fn decode_headers(
+        decoder: &mut TestDecoder,
+        header_block: &[u8],
+        headers: &[Header],
+        stream_id: StreamId,
+    ) {
+        let decoded_headers = decoder
+            .decoder
+            .decode_header_block(header_block, stream_id)
+            .unwrap();
+        let h = decoded_headers.unwrap();
+        assert_eq!(h, headers);
+    }
+
+    fn test_instruction(
+        capacity: u64,
+        instruction: &[u8],
+        res: &Res<()>,
+        decoder_instruction: &[u8],
+        check_capacity: u64,
+    ) {
+        let mut decoder = connect();
+
+        if capacity > 0 {
+            assert!(decoder.decoder.set_capacity(capacity).is_ok());
+        }
+
+        // recv an instruction
+        recv_instruction(&mut decoder, instruction, res);
+
+        // send decoder instruction and check that is what we expect.
+        send_instructions_and_check(&mut decoder, decoder_instruction);
+
+        if check_capacity > 0 {
+            assert_eq!(decoder.decoder.capacity(), check_capacity);
+        }
+    }
+
+    // test insert_with_name_ref which fails because there is not enough space in the table
+    #[test]
+    fn test_recv_insert_with_name_ref_1() {
+        test_instruction(
+            0,
+            &[0xc4, 0x04, 0x31, 0x32, 0x33, 0x34],
+            &Err(Error::EncoderStream),
+            &[0x03],
+            0,
+        );
+    }
+
+    // test insert_name_ref that succeeds
+    #[test]
+    fn test_recv_insert_with_name_ref_2() {
+        test_instruction(
+            100,
+            &[0xc4, 0x04, 0x31, 0x32, 0x33, 0x34],
+            &Ok(()),
+            &[0x03, 0x01],
+            0,
+        );
+    }
+
+    // test insert with name literal - succeeds
+    #[test]
+    fn test_recv_insert_with_name_litarel_2() {
+        test_instruction(
+            200,
+            &[
+                0x4e, 0x63, 0x6f, 0x6e, 0x74, 0x65, 0x6e, 0x74, 0x2d, 0x6c, 0x65, 0x6e, 0x67, 0x74,
+                0x68, 0x04, 0x31, 0x32, 0x33, 0x34,
+            ],
+            &Ok(()),
+            &[0x03, 0x01],
+            0,
+        );
+    }
+
+    #[test]
+    fn test_recv_change_capacity() {
+        test_instruction(0, &[0x3f, 0xa9, 0x01], &Ok(()), &[0x03], 200);
+    }
+
+    #[test]
+    fn test_recv_change_capacity_too_big() {
+        test_instruction(
+            0,
+            &[0x3f, 0xf1, 0x02],
+            &Err(Error::EncoderStream),
+            &[0x03],
+            0,
+        );
+    }
+
+    // this test tests header decoding, the header acks command and the insert count increment
+    // command.
+    #[test]
+    fn test_duplicate() {
+        let mut decoder = connect();
+
+        assert!(decoder.decoder.set_capacity(100).is_ok());
+
+        // receive an instruction
+        recv_instruction(
+            &mut decoder,
+            &[
+                0x4e, 0x63, 0x6f, 0x6e, 0x74, 0x65, 0x6e, 0x74, 0x2d, 0x6c, 0x65, 0x6e, 0x67, 0x74,
+                0x68, 0x04, 0x31, 0x32, 0x33, 0x34,
+            ],
+            &Ok(()),
+        );
+
+        // receive the second instruction, a duplicate instruction.
+        recv_instruction(&mut decoder, &[0x00], &Ok(()));
+
+        send_instructions_and_check(&mut decoder, &[0x03, 0x02]);
+    }
+
+    struct TestElement {
+        pub headers: Vec<Header>,
+        pub header_block: &'static [u8],
+        pub encoder_inst: &'static [u8],
+    }
+
+    #[test]
+    fn test_encode_incr_encode_header_ack_some() {
+        // 1. Decoder receives an instruction (header and value both as literal)
+        // 2. Decoder process the instruction and sends an increment instruction.
+        // 3. Decoder receives another two instruction (header and value both as literal) and a
+        //    header block.
+        // 4. Now it sends only a header ack and an increment instruction with increment==1.
+        let headers = vec![
+            Header::new("my-headera", "my-valuea"),
+            Header::new("my-headerb", "my-valueb"),
+        ];
+        let header_block = &[0x03, 0x81, 0x10, 0x11];
+        let first_encoder_inst = &[
+            0x4a, 0x6d, 0x79, 0x2d, 0x68, 0x65, 0x61, 0x64, 0x65, 0x72, 0x61, 0x09, 0x6d, 0x79,
+            0x2d, 0x76, 0x61, 0x6c, 0x75, 0x65, 0x61,
+        ];
+        let second_encoder_inst = &[
+            0x4a, 0x6d, 0x79, 0x2d, 0x68, 0x65, 0x61, 0x64, 0x65, 0x72, 0x62, 0x09, 0x6d, 0x79,
+            0x2d, 0x76, 0x61, 0x6c, 0x75, 0x65, 0x62, 0x4a, 0x6d, 0x79, 0x2d, 0x68, 0x65, 0x61,
+            0x64, 0x65, 0x72, 0x63, 0x09, 0x6d, 0x79, 0x2d, 0x76, 0x61, 0x6c, 0x75, 0x65, 0x63,
+        ];
+
+        let mut decoder = connect();
+
+        assert!(decoder.decoder.set_capacity(200).is_ok());
+
+        recv_instruction(&mut decoder, first_encoder_inst, &Ok(()));
+
+        send_instructions_and_check(&mut decoder, &[0x03, 0x1]);
+
+        recv_instruction(&mut decoder, second_encoder_inst, &Ok(()));
+
+        decode_headers(&mut decoder, header_block, &headers, STREAM_0);
+
+        send_instructions_and_check(&mut decoder, &[0x80, 0x1]);
+    }
+
+    #[test]
+    fn test_encode_incr_encode_header_ack_all() {
+        // 1. Decoder receives an instruction (header and value both as literal)
+        // 2. Decoder process the instruction and sends an increment instruction.
+        // 3. Decoder receives another instruction (header and value both as literal) and a header
+        //    block.
+        // 4. Now it sends only a header ack.
+        let headers = vec![
+            Header::new("my-headera", "my-valuea"),
+            Header::new("my-headerb", "my-valueb"),
+        ];
+        let header_block = &[0x03, 0x81, 0x10, 0x11];
+        let first_encoder_inst = &[
+            0x4a, 0x6d, 0x79, 0x2d, 0x68, 0x65, 0x61, 0x64, 0x65, 0x72, 0x61, 0x09, 0x6d, 0x79,
+            0x2d, 0x76, 0x61, 0x6c, 0x75, 0x65, 0x61,
+        ];
+        let second_encoder_inst = &[
+            0x4a, 0x6d, 0x79, 0x2d, 0x68, 0x65, 0x61, 0x64, 0x65, 0x72, 0x62, 0x09, 0x6d, 0x79,
+            0x2d, 0x76, 0x61, 0x6c, 0x75, 0x65, 0x62,
+        ];
+
+        let mut decoder = connect();
+
+        assert!(decoder.decoder.set_capacity(200).is_ok());
+
+        recv_instruction(&mut decoder, first_encoder_inst, &Ok(()));
+
+        send_instructions_and_check(&mut decoder, &[0x03, 0x1]);
+
+        recv_instruction(&mut decoder, second_encoder_inst, &Ok(()));
+
+        decode_headers(&mut decoder, header_block, &headers, STREAM_0);
+
+        send_instructions_and_check(&mut decoder, &[0x80]);
+    }
+
+    #[test]
+    fn test_header_ack_all() {
+        // Send two instructions to insert values into the dynamic table and then send a header
+        // that references them both. The result should be only a header acknowledgement.
+        let headers = vec![
+            Header::new("my-headera", "my-valuea"),
+            Header::new("my-headerb", "my-valueb"),
+        ];
+        let header_block = &[0x03, 0x81, 0x10, 0x11];
+        let encoder_inst = &[
+            0x4a, 0x6d, 0x79, 0x2d, 0x68, 0x65, 0x61, 0x64, 0x65, 0x72, 0x61, 0x09, 0x6d, 0x79,
+            0x2d, 0x76, 0x61, 0x6c, 0x75, 0x65, 0x61, 0x4a, 0x6d, 0x79, 0x2d, 0x68, 0x65, 0x61,
+            0x64, 0x65, 0x72, 0x62, 0x09, 0x6d, 0x79, 0x2d, 0x76, 0x61, 0x6c, 0x75, 0x65, 0x62,
+        ];
+
+        let mut decoder = connect();
+
+        assert!(decoder.decoder.set_capacity(200).is_ok());
+
+        recv_instruction(&mut decoder, encoder_inst, &Ok(()));
+
+        decode_headers(&mut decoder, header_block, &headers, STREAM_0);
+
+        send_instructions_and_check(&mut decoder, &[0x03, 0x80]);
+    }
+
+    #[test]
+    fn test_header_ack_and_incr_instruction() {
+        // Send two instructions to insert values into the dynamic table and then send a header
+        // that references only the first. The result should be a header acknowledgement and a
+        // increment instruction.
+        let headers = vec![Header::new("my-headera", "my-valuea")];
+        let header_block = &[0x02, 0x80, 0x10];
+        let encoder_inst = &[
+            0x4a, 0x6d, 0x79, 0x2d, 0x68, 0x65, 0x61, 0x64, 0x65, 0x72, 0x61, 0x09, 0x6d, 0x79,
+            0x2d, 0x76, 0x61, 0x6c, 0x75, 0x65, 0x61, 0x4a, 0x6d, 0x79, 0x2d, 0x68, 0x65, 0x61,
+            0x64, 0x65, 0x72, 0x62, 0x09, 0x6d, 0x79, 0x2d, 0x76, 0x61, 0x6c, 0x75, 0x65, 0x62,
+        ];
+
+        let mut decoder = connect();
+
+        assert!(decoder.decoder.set_capacity(200).is_ok());
+
+        recv_instruction(&mut decoder, encoder_inst, &Ok(()));
+
+        decode_headers(&mut decoder, header_block, &headers, STREAM_0);
+
+        send_instructions_and_check(&mut decoder, &[0x03, 0x80, 0x01]);
+    }
+
+    #[test]
+    fn test_header_block_decoder() {
+        let test_cases: [TestElement; 6] = [
+            // test a header with ref to static - encode_indexed
+            TestElement {
+                headers: vec![Header::new(":method", "GET")],
+                header_block: &[0x00, 0x00, 0xd1],
+                encoder_inst: &[],
+            },
+            // test encode_literal_with_name_ref
+            TestElement {
+                headers: vec![Header::new(":path", "/somewhere")],
+                header_block: &[
+                    0x00, 0x00, 0x51, 0x0a, 0x2f, 0x73, 0x6f, 0x6d, 0x65, 0x77, 0x68, 0x65, 0x72,
+                    0x65,
+                ],
+                encoder_inst: &[],
+            },
+            // test adding a new header and encode_post_base_index, also test
+            // fix_header_block_prefix
+            TestElement {
+                headers: vec![Header::new("my-header", "my-value")],
+                header_block: &[0x02, 0x80, 0x10],
+                encoder_inst: &[
+                    0x49, 0x6d, 0x79, 0x2d, 0x68, 0x65, 0x61, 0x64, 0x65, 0x72, 0x08, 0x6d, 0x79,
+                    0x2d, 0x76, 0x61, 0x6c, 0x75, 0x65,
+                ],
+            },
+            // test encode_indexed with a ref to dynamic table.
+            TestElement {
+                headers: vec![Header::new("my-header", "my-value")],
+                header_block: &[0x02, 0x00, 0x80],
+                encoder_inst: &[],
+            },
+            // test encode_literal_with_name_ref.
+            TestElement {
+                headers: vec![Header::new("my-header", "my-value2")],
+                header_block: &[
+                    0x02, 0x00, 0x40, 0x09, 0x6d, 0x79, 0x2d, 0x76, 0x61, 0x6c, 0x75, 0x65, 0x32,
+                ],
+                encoder_inst: &[],
+            },
+            // test multiple headers
+            TestElement {
+                headers: vec![
+                    Header::new(":method", "GET"),
+                    Header::new(":path", "/somewhere"),
+                    Header::new(":authority", "example.com"),
+                    Header::new(":scheme", "https"),
+                ],
+                header_block: &[
+                    0x00, 0x01, 0xd1, 0x51, 0x0a, 0x2f, 0x73, 0x6f, 0x6d, 0x65, 0x77, 0x68, 0x65,
+                    0x72, 0x65, 0x50, 0x0b, 0x65, 0x78, 0x61, 0x6d, 0x70, 0x6c, 0x65, 0x2e, 0x63,
+                    0x6f, 0x6d, 0xd7,
+                ],
+                encoder_inst: &[],
+            },
+        ];
+
+        let mut decoder = connect();
+
+        assert!(decoder.decoder.set_capacity(200).is_ok());
+
+        for (i, t) in test_cases.iter().enumerate() {
+            // receive an instruction
+            if !t.encoder_inst.is_empty() {
+                recv_instruction(&mut decoder, t.encoder_inst, &Ok(()));
+            }
+
+            decode_headers(
+                &mut decoder,
+                t.header_block,
+                &t.headers,
+                StreamId::from(u64::try_from(i).unwrap()),
+            );
+        }
+
+        // test header acks and the insert count increment command
+        send_instructions_and_check(&mut decoder, &[0x03, 0x82, 0x83, 0x84]);
+    }
+
+    #[test]
+    fn test_header_block_decoder_huffman() {
+        let test_cases: [TestElement; 6] = [
+            // test a header with ref to static - encode_indexed
+            TestElement {
+                headers: vec![Header::new(":method", "GET")],
+                header_block: &[0x00, 0x00, 0xd1],
+                encoder_inst: &[],
+            },
+            // test encode_literal_with_name_ref
+            TestElement {
+                headers: vec![Header::new(":path", "/somewhere")],
+                header_block: &[
+                    0x00, 0x00, 0x51, 0x87, 0x61, 0x07, 0xa4, 0xbe, 0x27, 0x2d, 0x85,
+                ],
+                encoder_inst: &[],
+            },
+            // test adding a new header and encode_post_base_index, also test
+            // fix_header_block_prefix
+            TestElement {
+                headers: vec![Header::new("my-header", "my-value")],
+                header_block: &[0x02, 0x80, 0x10],
+                encoder_inst: &[
+                    0x67, 0xa7, 0xd2, 0xd3, 0x94, 0x72, 0x16, 0xcf, 0x86, 0xa7, 0xd2, 0xdd, 0xc7,
+                    0x45, 0xa5,
+                ],
+            },
+            // test encode_indexed with a ref to dynamic table.
+            TestElement {
+                headers: vec![Header::new("my-header", "my-value")],
+                header_block: &[0x02, 0x00, 0x80],
+                encoder_inst: &[],
+            },
+            // test encode_literal_with_name_ref.
+            TestElement {
+                headers: vec![Header::new("my-header", "my-value2")],
+                header_block: &[
+                    0x02, 0x00, 0x40, 0x87, 0xa7, 0xd2, 0xdd, 0xc7, 0x45, 0xa5, 0x17,
+                ],
+                encoder_inst: &[],
+            },
+            // test multiple headers
+            TestElement {
+                headers: vec![
+                    Header::new(":method", "GET"),
+                    Header::new(":path", "/somewhere"),
+                    Header::new(":authority", "example.com"),
+                    Header::new(":scheme", "https"),
+                ],
+                header_block: &[
+                    0x00, 0x01, 0xd1, 0x51, 0x87, 0x61, 0x07, 0xa4, 0xbe, 0x27, 0x2d, 0x85, 0x50,
+                    0x88, 0x2f, 0x91, 0xd3, 0x5d, 0x05, 0x5c, 0x87, 0xa7, 0xd7,
+                ],
+                encoder_inst: &[],
+            },
+        ];
+
+        let mut decoder = connect();
+
+        assert!(decoder.decoder.set_capacity(200).is_ok());
+
+        for (i, t) in test_cases.iter().enumerate() {
+            // receive an instruction.
+            if !t.encoder_inst.is_empty() {
+                recv_instruction(&mut decoder, t.encoder_inst, &Ok(()));
+            }
+
+            decode_headers(
+                &mut decoder,
+                t.header_block,
+                &t.headers,
+                StreamId::from(u64::try_from(i).unwrap()),
+            );
+        }
+
+        // test header acks and the insert count increment command
+        send_instructions_and_check(&mut decoder, &[0x03, 0x82, 0x83, 0x84]);
+    }
+
+    #[test]
+    fn test_subtract_overflow_in_header_ack() {
+        const HEADER_BLOCK_1: &[u8] = &[0x03, 0x81, 0x10, 0x11];
+        const ENCODER_INST: &[u8] = &[
+            0x4a, 0x6d, 0x79, 0x2d, 0x68, 0x65, 0x61, 0x64, 0x65, 0x72, 0x61, 0x09, 0x6d, 0x79,
+            0x2d, 0x76, 0x61, 0x6c, 0x75, 0x65, 0x61, 0x4a, 0x6d, 0x79, 0x2d, 0x68, 0x65, 0x61,
+            0x64, 0x65, 0x72, 0x62, 0x09, 0x6d, 0x79, 0x2d, 0x76, 0x61, 0x6c, 0x75, 0x65, 0x62,
+        ];
+        const HEADER_BLOCK_2: &[u8] = &[0x02, 0x80, 0x10];
+        // Test for issue https://github.com/mozilla/neqo/issues/475
+        // Send two instructions to insert values into the dynamic table and send a header
+        // that references them both. This will increase number of acked inserts in the table
+        // to 2. Then send a header that references only one of them which shouldn't increase
+        // number of acked inserts.
+        let headers = vec![
+            Header::new("my-headera", "my-valuea"),
+            Header::new("my-headerb", "my-valueb"),
+        ];
+
+        let mut decoder = connect();
+
+        assert!(decoder.decoder.set_capacity(200).is_ok());
+
+        recv_instruction(&mut decoder, ENCODER_INST, &Ok(()));
+
+        decode_headers(&mut decoder, HEADER_BLOCK_1, &headers, STREAM_0);
+
+        let headers = vec![Header::new("my-headera", "my-valuea")];
+
+        decode_headers(&mut decoder, HEADER_BLOCK_2, &headers, STREAM_0);
+    }
+
+    #[test]
+    fn test_base_larger_than_entry_count() {
+        // Test for issue https://github.com/mozilla/neqo/issues/533
+        // Send instruction that inserts 2 fields into the dynamic table and send a header that
+        // uses base larger than 2.
+        const ENCODER_INST: &[u8] = &[
+            0x4a, 0x6d, 0x79, 0x2d, 0x68, 0x65, 0x61, 0x64, 0x65, 0x72, 0x61, 0x09, 0x6d, 0x79,
+            0x2d, 0x76, 0x61, 0x6c, 0x75, 0x65, 0x61, 0x4a, 0x6d, 0x79, 0x2d, 0x68, 0x65, 0x61,
+            0x64, 0x65, 0x72, 0x62, 0x09, 0x6d, 0x79, 0x2d, 0x76, 0x61, 0x6c, 0x75, 0x65, 0x62,
+        ];
+
+        const HEADER_BLOCK: &[u8] = &[0x03, 0x03, 0x83, 0x84];
+
+        let headers = vec![
+            Header::new("my-headerb", "my-valueb"),
+            Header::new("my-headera", "my-valuea"),
+        ];
+
+        let mut decoder = connect();
+
+        assert!(decoder.decoder.set_capacity(200).is_ok());
+
+        recv_instruction(&mut decoder, ENCODER_INST, &Ok(()));
+
+        decode_headers(&mut decoder, HEADER_BLOCK, &headers, STREAM_0);
+    }
+}
diff --git a/third_party/rust/neqo-qpack/src/decoder_instructions.rs b/third_party/rust/neqo-qpack/src/decoder_instructions.rs
new file mode 100644
index 0000000000..029cd61db6
--- /dev/null
+++ b/third_party/rust/neqo-qpack/src/decoder_instructions.rs
@@ -0,0 +1,247 @@
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use std::mem;
+
+use neqo_common::{qdebug, qtrace};
+use neqo_transport::StreamId;
+
+use crate::{
+    prefix::{DECODER_HEADER_ACK, DECODER_INSERT_COUNT_INCREMENT, DECODER_STREAM_CANCELLATION},
+    qpack_send_buf::QpackData,
+    reader::{IntReader, ReadByte},
+    Res,
+};
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+pub enum DecoderInstruction {
+    InsertCountIncrement { increment: u64 },
+    HeaderAck { stream_id: StreamId },
+    StreamCancellation { stream_id: StreamId },
+    NoInstruction,
+}
+
+impl DecoderInstruction {
+    fn get_instruction(b: u8) -> Self {
+        if DECODER_HEADER_ACK.cmp_prefix(b) {
+            Self::HeaderAck {
+                stream_id: StreamId::from(0),
+            }
+        } else if DECODER_STREAM_CANCELLATION.cmp_prefix(b) {
+            Self::StreamCancellation {
+                stream_id: StreamId::from(0),
+            }
+        } else if DECODER_INSERT_COUNT_INCREMENT.cmp_prefix(b) {
+            Self::InsertCountIncrement { increment: 0 }
+        } else {
+            unreachable!();
+        }
+    }
+
+    pub(crate) fn marshal(&self, enc: &mut QpackData) {
+        match self {
+            Self::InsertCountIncrement { increment } => {
+                enc.encode_prefixed_encoded_int(DECODER_INSERT_COUNT_INCREMENT, *increment);
+            }
+            Self::HeaderAck { stream_id } => {
+                enc.encode_prefixed_encoded_int(DECODER_HEADER_ACK, stream_id.as_u64());
+            }
+            Self::StreamCancellation { stream_id } => {
+                enc.encode_prefixed_encoded_int(DECODER_STREAM_CANCELLATION, stream_id.as_u64());
+            }
+            Self::NoInstruction => {}
+        }
+    }
+}
+
+#[derive(Debug)]
+enum DecoderInstructionReaderState {
+    ReadInstruction,
+    ReadInt { reader: IntReader },
+}
+
+#[derive(Debug)]
+pub struct DecoderInstructionReader {
+    state: DecoderInstructionReaderState,
+    instruction: DecoderInstruction,
+}
+
+impl ::std::fmt::Display for DecoderInstructionReader {
+    fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
+        write!(f, "InstructionReader")
+    }
+}
+
+impl DecoderInstructionReader {
+    pub fn new() -> Self {
+        Self {
+            state: DecoderInstructionReaderState::ReadInstruction,
+            instruction: DecoderInstruction::NoInstruction,
+        }
+    }
+
+    /// # Errors
+    ///
+    /// 1) `NeedMoreData` if the reader needs more data
+    /// 2) `ClosedCriticalStream`
+    /// 3) other errors will be translated to `DecoderStream` by the caller of this function.
+    pub fn read_instructions<R: ReadByte>(&mut self, recv: &mut R) -> Res<DecoderInstruction> {
+        qdebug!([self], "read a new instraction");
+        loop {
+            match &mut self.state {
+                DecoderInstructionReaderState::ReadInstruction => {
+                    let b = recv.read_byte()?;
+                    self.instruction = DecoderInstruction::get_instruction(b);
+                    self.state = DecoderInstructionReaderState::ReadInt {
+                        reader: IntReader::make(
+                            b,
+                            &[
+                                DECODER_HEADER_ACK,
+                                DECODER_STREAM_CANCELLATION,
+                                DECODER_INSERT_COUNT_INCREMENT,
+                            ],
+                        ),
+                    };
+                }
+                DecoderInstructionReaderState::ReadInt { reader } => {
+                    let val = reader.read(recv)?;
+                    qtrace!([self], "varint read {}", val);
+                    match &mut self.instruction {
+                        DecoderInstruction::InsertCountIncrement { increment: v } => {
+                            *v = val;
+                            self.state = DecoderInstructionReaderState::ReadInstruction;
+                            break Ok(mem::replace(
+                                &mut self.instruction,
+                                DecoderInstruction::NoInstruction,
+                            ));
+                        }
+                        DecoderInstruction::HeaderAck { stream_id: v }
+                        | DecoderInstruction::StreamCancellation { stream_id: v } => {
+                            *v = StreamId::from(val);
+                            self.state = DecoderInstructionReaderState::ReadInstruction;
+                            break Ok(mem::replace(
+                                &mut self.instruction,
+                                DecoderInstruction::NoInstruction,
+                            ));
+                        }
+                        DecoderInstruction::NoInstruction => {
+                            unreachable!("This instruction cannot be in this state.");
+                        }
+                    }
+                }
+            }
+        }
+    }
+}
+
+#[cfg(test)]
+mod test {
+
+    use neqo_transport::StreamId;
+
+    use super::{DecoderInstruction, DecoderInstructionReader, QpackData};
+    use crate::{reader::test_receiver::TestReceiver, Error};
+
+    fn test_encoding_decoding(instruction: DecoderInstruction) {
+        let mut buf = QpackData::default();
+        instruction.marshal(&mut buf);
+        let mut test_receiver: TestReceiver = TestReceiver::default();
+        test_receiver.write(&buf);
+        let mut decoder = DecoderInstructionReader::new();
+        assert_eq!(
+            decoder.read_instructions(&mut test_receiver).unwrap(),
+            instruction
+        );
+    }
+
+    #[test]
+    fn test_encoding_decoding_instructions() {
+        test_encoding_decoding(DecoderInstruction::InsertCountIncrement { increment: 1 });
+        test_encoding_decoding(DecoderInstruction::InsertCountIncrement { increment: 10_000 });
+
+        test_encoding_decoding(DecoderInstruction::HeaderAck {
+            stream_id: StreamId::new(1),
+        });
+        test_encoding_decoding(DecoderInstruction::HeaderAck {
+            stream_id: StreamId::new(10_000),
+        });
+
+        test_encoding_decoding(DecoderInstruction::StreamCancellation {
+            stream_id: StreamId::new(1),
+        });
+        test_encoding_decoding(DecoderInstruction::StreamCancellation {
+            stream_id: StreamId::new(10_000),
+        });
+    }
+
+    fn test_encoding_decoding_slow_reader(instruction: DecoderInstruction) {
+        let mut buf = QpackData::default();
+        instruction.marshal(&mut buf);
+        let mut test_receiver: TestReceiver = TestReceiver::default();
+        let mut decoder = DecoderInstructionReader::new();
+        for i in 0..buf.len() - 1 {
+            test_receiver.write(&buf[i..=i]);
+            assert_eq!(
+                decoder.read_instructions(&mut test_receiver),
+                Err(Error::NeedMoreData)
+            );
+        }
+        test_receiver.write(&buf[buf.len() - 1..buf.len()]);
+        assert_eq!(
+            decoder.read_instructions(&mut test_receiver).unwrap(),
+            instruction
+        );
+    }
+
+    #[test]
+    fn test_encoding_decoding_instructions_slow_reader() {
+        test_encoding_decoding_slow_reader(DecoderInstruction::InsertCountIncrement {
+            increment: 10_000,
+        });
+        test_encoding_decoding_slow_reader(DecoderInstruction::HeaderAck {
+            stream_id: StreamId::new(10_000),
+        });
+        test_encoding_decoding_slow_reader(DecoderInstruction::StreamCancellation {
+            stream_id: StreamId::new(10_000),
+        });
+    }
+
+    #[test]
+    fn test_decoding_error() {
+        let mut test_receiver: TestReceiver = TestReceiver::default();
+        // InsertCountIncrement with overflow
+        test_receiver.write(&[
+            0x3f, 0xc1, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xff, 0x02,
+        ]);
+        let mut decoder = DecoderInstructionReader::new();
+        assert_eq!(
+            decoder.read_instructions(&mut test_receiver),
+            Err(Error::IntegerOverflow)
+        );
+
+        let mut test_receiver: TestReceiver = TestReceiver::default();
+        // StreamCancellation with overflow
+        test_receiver.write(&[
+            0x7f, 0xc1, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xff, 0x02,
+        ]);
+        let mut decoder = DecoderInstructionReader::new();
+        assert_eq!(
+            decoder.read_instructions(&mut test_receiver),
+            Err(Error::IntegerOverflow)
+        );
+
+        let mut test_receiver: TestReceiver = TestReceiver::default();
+        // HeaderAck with overflow
+        test_receiver.write(&[
+            0x7f, 0xc1, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xff, 0x02,
+        ]);
+        let mut decoder = DecoderInstructionReader::new();
+        assert_eq!(
+            decoder.read_instructions(&mut test_receiver),
+            Err(Error::IntegerOverflow)
+        );
+    }
+}
diff --git a/third_party/rust/neqo-qpack/src/encoder.rs b/third_party/rust/neqo-qpack/src/encoder.rs
new file mode 100644
index 0000000000..c7921ee2c0
--- /dev/null
+++ b/third_party/rust/neqo-qpack/src/encoder.rs
@@ -0,0 +1,1680 @@
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use std::{
+    collections::{HashMap, HashSet, VecDeque},
+    convert::TryFrom,
+};
+
+use neqo_common::{qdebug, qerror, qlog::NeqoQlog, qtrace, Header};
+use neqo_transport::{Connection, Error as TransportError, StreamId};
+
+use crate::{
+    decoder_instructions::{DecoderInstruction, DecoderInstructionReader},
+    encoder_instructions::EncoderInstruction,
+    header_block::HeaderEncoder,
+    qlog,
+    qpack_send_buf::QpackData,
+    reader::ReceiverConnWrapper,
+    stats::Stats,
+    table::{HeaderTable, LookupResult, ADDITIONAL_TABLE_ENTRY_SIZE},
+    Error, QpackSettings, Res,
+};
+
+pub const QPACK_UNI_STREAM_TYPE_ENCODER: u64 = 0x2;
+
+#[derive(Debug, PartialEq)]
+enum LocalStreamState {
+    NoStream,
+    Uninitialized(StreamId),
+    Initialized(StreamId),
+}
+
+impl LocalStreamState {
+    pub fn stream_id(&self) -> Option<StreamId> {
+        match self {
+            Self::NoStream => None,
+            Self::Uninitialized(stream_id) | Self::Initialized(stream_id) => Some(*stream_id),
+        }
+    }
+}
+
+#[derive(Debug)]
+pub struct QPackEncoder {
+    table: HeaderTable,
+    max_table_size: u64,
+    max_entries: u64,
+    instruction_reader: DecoderInstructionReader,
+    local_stream: LocalStreamState,
+    max_blocked_streams: u16,
+    // Remember header blocks that are referring to dynamic table.
+    // There can be multiple header blocks in one stream, headers, trailer, push stream request,
+    // etc. This HashMap maps a stream ID to a list of header blocks. Each header block is a
+    // list of referenced dynamic table entries.
+    unacked_header_blocks: HashMap<StreamId, VecDeque<HashSet<u64>>>,
+    blocked_stream_cnt: u16,
+    use_huffman: bool,
+    next_capacity: Option<u64>,
+    stats: Stats,
+}
+
+impl QPackEncoder {
+    #[must_use]
+    pub fn new(qpack_settings: &QpackSettings, use_huffman: bool) -> Self {
+        Self {
+            table: HeaderTable::new(true),
+            max_table_size: qpack_settings.max_table_size_encoder,
+            max_entries: 0,
+            instruction_reader: DecoderInstructionReader::new(),
+            local_stream: LocalStreamState::NoStream,
+            max_blocked_streams: 0,
+            unacked_header_blocks: HashMap::new(),
+            blocked_stream_cnt: 0,
+            use_huffman,
+            next_capacity: None,
+            stats: Stats::default(),
+        }
+    }
+
+    /// This function is use for setting encoders table max capacity. The value is received as
+    /// a `SETTINGS_QPACK_MAX_TABLE_CAPACITY` setting parameter.
+    ///
+    /// # Errors
+    ///
+    /// `EncoderStream` if value is too big.
+    /// `ChangeCapacity` if table capacity cannot be reduced.
+    pub fn set_max_capacity(&mut self, cap: u64) -> Res<()> {
+        if cap > (1 << 30) - 1 {
+            return Err(Error::EncoderStream);
+        }
+
+        if cap == self.table.capacity() {
+            return Ok(());
+        }
+
+        qdebug!(
+            [self],
+            "Set max capacity to new capacity:{} old:{} max_table_size={}.",
+            cap,
+            self.table.capacity(),
+            self.max_table_size,
+        );
+
+        let new_cap = std::cmp::min(self.max_table_size, cap);
+        // we also set our table to the max allowed.
+        self.change_capacity(new_cap);
+        Ok(())
+    }
+
+    /// This function is use for setting encoders max blocked streams. The value is received as
+    /// a `SETTINGS_QPACK_BLOCKED_STREAMS` setting parameter.
+    ///
+    /// # Errors
+    ///
+    /// `EncoderStream` if value is too big.
+    pub fn set_max_blocked_streams(&mut self, blocked_streams: u64) -> Res<()> {
+        self.max_blocked_streams = u16::try_from(blocked_streams).or(Err(Error::EncoderStream))?;
+        Ok(())
+    }
+
+    /// Reads decoder instructions.
+    ///
+    /// # Errors
+    ///
+    /// May return: `ClosedCriticalStream` if stream has been closed or `DecoderStream`
+    /// in case of any other transport error.
+    pub fn receive(&mut self, conn: &mut Connection, stream_id: StreamId) -> Res<()> {
+        self.read_instructions(conn, stream_id)
+            .map_err(|e| map_error(&e))
+    }
+
+    fn read_instructions(&mut self, conn: &mut Connection, stream_id: StreamId) -> Res<()> {
+        qdebug!([self], "read a new instraction");
+        loop {
+            let mut recv = ReceiverConnWrapper::new(conn, stream_id);
+            match self.instruction_reader.read_instructions(&mut recv) {
+                Ok(instruction) => self.call_instruction(instruction, conn.qlog_mut())?,
+                Err(Error::NeedMoreData) => break Ok(()),
+                Err(e) => break Err(e),
+            }
+        }
+    }
+
+    fn recalculate_blocked_streams(&mut self) {
+        let acked_inserts_cnt = self.table.get_acked_inserts_cnt();
+        self.blocked_stream_cnt = 0;
+        for hb_list in self.unacked_header_blocks.values_mut() {
+            debug_assert!(!hb_list.is_empty());
+            if hb_list.iter().flatten().any(|e| *e >= acked_inserts_cnt) {
+                self.blocked_stream_cnt += 1;
+            }
+        }
+    }
+
+    #[allow(clippy::map_err_ignore)]
+    fn insert_count_instruction(&mut self, increment: u64) -> Res<()> {
+        self.table
+            .increment_acked(increment)
+            .map_err(|_| Error::DecoderStream)?;
+        self.recalculate_blocked_streams();
+        Ok(())
+    }
+
+    fn header_ack(&mut self, stream_id: StreamId) {
+        self.stats.header_acks_recv += 1;
+        let mut new_acked = self.table.get_acked_inserts_cnt();
+        if let Some(hb_list) = self.unacked_header_blocks.get_mut(&stream_id) {
+            if let Some(ref_list) = hb_list.pop_back() {
+                for iter in ref_list {
+                    self.table.remove_ref(iter);
+                    if iter >= new_acked {
+                        new_acked = iter + 1;
+                    }
+                }
+            } else {
+                debug_assert!(false, "We should have at least one header block.");
+            }
+            if hb_list.is_empty() {
+                self.unacked_header_blocks.remove(&stream_id);
+            }
+        }
+        if new_acked > self.table.get_acked_inserts_cnt() {
+            self.insert_count_instruction(new_acked - self.table.get_acked_inserts_cnt())
+                .expect("This should neve happen");
+        }
+    }
+
+    fn stream_cancellation(&mut self, stream_id: StreamId) {
+        self.stats.stream_cancelled_recv += 1;
+        let mut was_blocker = false;
+        if let Some(mut hb_list) = self.unacked_header_blocks.remove(&stream_id) {
+            debug_assert!(!hb_list.is_empty());
+            while let Some(ref_list) = hb_list.pop_front() {
+                for iter in ref_list {
+                    self.table.remove_ref(iter);
+                    was_blocker = was_blocker || (iter >= self.table.get_acked_inserts_cnt());
+                }
+            }
+        }
+        if was_blocker {
+            debug_assert!(self.blocked_stream_cnt > 0);
+            self.blocked_stream_cnt -= 1;
+        }
+    }
+
+    fn call_instruction(
+        &mut self,
+        instruction: DecoderInstruction,
+        qlog: &mut NeqoQlog,
+    ) -> Res<()> {
+        qdebug!([self], "call intruction {:?}", instruction);
+        match instruction {
+            DecoderInstruction::InsertCountIncrement { increment } => {
+                qlog::qpack_read_insert_count_increment_instruction(
+                    qlog,
+                    increment,
+                    &increment.to_be_bytes(),
+                );
+
+                self.insert_count_instruction(increment)
+            }
+            DecoderInstruction::HeaderAck { stream_id } => {
+                self.header_ack(stream_id);
+                Ok(())
+            }
+            DecoderInstruction::StreamCancellation { stream_id } => {
+                self.stream_cancellation(stream_id);
+                Ok(())
+            }
+            DecoderInstruction::NoInstruction => Ok(()),
+        }
+    }
+
+    /// Inserts a new entry into a table and sends the corresponding instruction to a peer. An entry
+    /// is added only if it is possible to send the corresponding instruction immediately, i.e.
+    /// the encoder stream is not blocked by the flow control (or stream internal buffer(this is
+    /// very unlikely)).
+    ///
+    /// # Errors
+    ///
+    /// `EncoderStreamBlocked` if the encoder stream is blocked by the flow control.
+    /// `DynamicTableFull` if the dynamic table does not have enough space for the entry.
+    /// The function can return transport errors: `InvalidStreamId`, `InvalidInput` and
+    /// `FinalSizeError`.
+    ///
+    /// # Panics
+    ///
+    /// When the insertion fails (it should not).
+    pub fn send_and_insert(
+        &mut self,
+        conn: &mut Connection,
+        name: &[u8],
+        value: &[u8],
+    ) -> Res<u64> {
+        qdebug!([self], "insert {:?} {:?}.", name, value);
+
+        let entry_size = name.len() + value.len() + ADDITIONAL_TABLE_ENTRY_SIZE;
+
+        if !self.table.insert_possible(entry_size) {
+            return Err(Error::DynamicTableFull);
+        }
+
+        let mut buf = QpackData::default();
+        EncoderInstruction::InsertWithNameLiteral { name, value }
+            .marshal(&mut buf, self.use_huffman);
+
+        let stream_id = self.local_stream.stream_id().ok_or(Error::Internal)?;
+
+        let sent = conn
+            .stream_send_atomic(stream_id, &buf)
+            .map_err(|e| map_stream_send_atomic_error(&e))?;
+        if !sent {
+            return Err(Error::EncoderStreamBlocked);
+        }
+
+        self.stats.dynamic_table_inserts += 1;
+
+        match self.table.insert(name, value) {
+            Ok(inx) => Ok(inx),
+            Err(e) => {
+                debug_assert!(false);
+                Err(e)
+            }
+        }
+    }
+
+    fn change_capacity(&mut self, value: u64) {
+        qdebug!([self], "change capacity: {}", value);
+        self.next_capacity = Some(value);
+    }
+
+    fn maybe_send_change_capacity(
+        &mut self,
+        conn: &mut Connection,
+        stream_id: StreamId,
+    ) -> Res<()> {
+        if let Some(cap) = self.next_capacity {
+            // Check if it is possible to reduce the capacity, e.g. if enough space can be make free
+            // for the reduction.
+            if cap < self.table.capacity() && !self.table.can_evict_to(cap) {
+                return Err(Error::DynamicTableFull);
+            }
+            let mut buf = QpackData::default();
+            EncoderInstruction::Capacity { value: cap }.marshal(&mut buf, self.use_huffman);
+            if !conn.stream_send_atomic(stream_id, &buf)? {
+                return Err(Error::EncoderStreamBlocked);
+            }
+            if self.table.set_capacity(cap).is_err() {
+                debug_assert!(
+                    false,
+                    "can_evict_to should have checked and make sure this operation is possible"
+                );
+                return Err(Error::InternalError);
+            }
+            self.max_entries = cap / 32;
+            self.next_capacity = None;
+        }
+        Ok(())
+    }
+
+    /// Sends any qpack encoder instructions.
+    ///
+    /// # Errors
+    ///
+    ///   returns `EncoderStream` in case of an error.
+    pub fn send_encoder_updates(&mut self, conn: &mut Connection) -> Res<()> {
+        match self.local_stream {
+            LocalStreamState::NoStream => {
+                qerror!("Send call but there is no stream yet.");
+                Ok(())
+            }
+            LocalStreamState::Uninitialized(stream_id) => {
+                let mut buf = QpackData::default();
+                buf.encode_varint(QPACK_UNI_STREAM_TYPE_ENCODER);
+                if !conn.stream_send_atomic(stream_id, &buf[..])? {
+                    return Err(Error::EncoderStreamBlocked);
+                }
+                self.local_stream = LocalStreamState::Initialized(stream_id);
+                self.maybe_send_change_capacity(conn, stream_id)
+            }
+            LocalStreamState::Initialized(stream_id) => {
+                self.maybe_send_change_capacity(conn, stream_id)
+            }
+        }
+    }
+
+    fn is_stream_blocker(&self, stream_id: StreamId) -> bool {
+        if let Some(hb_list) = self.unacked_header_blocks.get(&stream_id) {
+            debug_assert!(!hb_list.is_empty());
+            match hb_list.iter().flatten().max() {
+                Some(max_ref) => *max_ref >= self.table.get_acked_inserts_cnt(),
+                None => false,
+            }
+        } else {
+            false
+        }
+    }
+
+    /// Encodes headers
+    ///
+    /// # Errors
+    ///
+    /// `ClosedCriticalStream` if the encoder stream is closed.
+    /// `InternalError` if an unexpected error occurred.
+    ///
+    /// # Panics
+    ///
+    /// If there is a programming error.
+    pub fn encode_header_block(
+        &mut self,
+        conn: &mut Connection,
+        h: &[Header],
+        stream_id: StreamId,
+    ) -> HeaderEncoder {
+        qdebug!([self], "encoding headers.");
+
+        let mut encoder_blocked = false;
+        // Try to send capacity instructions if present.
+        if self.send_encoder_updates(conn).is_err() {
+            // This code doesn't try to deal with errors, it just tries
+            // to write to the encoder stream AND if it can't uses
+            // literal instructions.
+            // The errors can be:
+            //   1) `EncoderStreamBlocked` - this is an error that can occur.
+            //   2) `InternalError` - this is unexpected error.
+            //   3) `ClosedCriticalStream` - this is error that should close the HTTP/3 session.
+            // The last 2 errors are ignored here and will be picked up
+            // by the main loop.
+            encoder_blocked = true;
+        }
+
+        let mut encoded_h =
+            HeaderEncoder::new(self.table.base(), self.use_huffman, self.max_entries);
+
+        let stream_is_blocker = self.is_stream_blocker(stream_id);
+        let can_block = self.blocked_stream_cnt < self.max_blocked_streams || stream_is_blocker;
+
+        let mut ref_entries = HashSet::new();
+
+        for iter in h {
+            let name = iter.name().as_bytes().to_vec();
+            let value = iter.value().as_bytes().to_vec();
+            qtrace!("encoding {:x?} {:x?}.", name, value);
+
+            if let Some(LookupResult {
+                index,
+                static_table,
+                value_matches,
+            }) = self.table.lookup(&name, &value, can_block)
+            {
+                qtrace!(
+                    [self],
+                    "found a {} entry, value-match={}",
+                    if static_table { "static" } else { "dynamic" },
+                    value_matches
+                );
+                if value_matches {
+                    if static_table {
+                        encoded_h.encode_indexed_static(index);
+                    } else {
+                        encoded_h.encode_indexed_dynamic(index);
+                    }
+                } else {
+                    encoded_h.encode_literal_with_name_ref(static_table, index, &value);
+                }
+                if !static_table && ref_entries.insert(index) {
+                    self.table.add_ref(index);
+                }
+            } else if can_block && !encoder_blocked {
+                // Insert using an InsertWithNameLiteral instruction. This entry name does not match
+                // any name in the tables therefore we cannot use any other
+                // instruction.
+                if let Ok(index) = self.send_and_insert(conn, &name, &value) {
+                    encoded_h.encode_indexed_dynamic(index);
+                    ref_entries.insert(index);
+                    self.table.add_ref(index);
+                } else {
+                    // This code doesn't try to deal with errors, it just tries
+                    // to write to the encoder stream AND if it can't uses
+                    // literal instructions.
+                    // The errors can be:
+                    //   1) `EncoderStreamBlocked` - this is an error that can occur.
+                    //   2) `DynamicTableFull` - this is an error that can occur.
+                    //   3) `InternalError` - this is unexpected error.
+                    //   4) `ClosedCriticalStream` - this is error that should close the HTTP/3
+                    //      session.
+                    // The last 2 errors are ignored here and will be picked up
+                    // by the main loop.
+                    // As soon as one of the instructions cannot be written or the table is full, do
+                    // not try again.
+                    encoder_blocked = true;
+                    encoded_h.encode_literal_with_name_literal(&name, &value);
+                }
+            } else {
+                encoded_h.encode_literal_with_name_literal(&name, &value);
+            }
+        }
+
+        encoded_h.encode_header_block_prefix();
+
+        if !stream_is_blocker {
+            // The streams was not a blocker, check if the stream is a blocker now.
+            if let Some(max_ref) = ref_entries.iter().max() {
+                if *max_ref >= self.table.get_acked_inserts_cnt() {
+                    debug_assert!(self.blocked_stream_cnt <= self.max_blocked_streams);
+                    self.blocked_stream_cnt += 1;
+                }
+            }
+        }
+
+        if !ref_entries.is_empty() {
+            self.unacked_header_blocks
+                .entry(stream_id)
+                .or_default()
+                .push_front(ref_entries);
+            self.stats.dynamic_table_references += 1;
+        }
+        encoded_h
+    }
+
+    /// Encoder stream has been created. Add the stream id.
+    ///
+    /// # Panics
+    ///
+    /// If a stream has already been added.
+    pub fn add_send_stream(&mut self, stream_id: StreamId) {
+        if self.local_stream == LocalStreamState::NoStream {
+            self.local_stream = LocalStreamState::Uninitialized(stream_id);
+        } else {
+            panic!("Adding multiple local streams");
+        }
+    }
+
+    #[must_use]
+    pub fn stats(&self) -> Stats {
+        self.stats.clone()
+    }
+
+    #[must_use]
+    pub fn local_stream_id(&self) -> Option<StreamId> {
+        self.local_stream.stream_id()
+    }
+
+    #[cfg(test)]
+    fn blocked_stream_cnt(&self) -> u16 {
+        self.blocked_stream_cnt
+    }
+}
+
+impl ::std::fmt::Display for QPackEncoder {
+    fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
+        write!(f, "QPackEncoder")
+    }
+}
+
+fn map_error(err: &Error) -> Error {
+    if *err == Error::ClosedCriticalStream {
+        Error::ClosedCriticalStream
+    } else {
+        Error::DecoderStream
+    }
+}
+
+fn map_stream_send_atomic_error(err: &TransportError) -> Error {
+    match err {
+        TransportError::InvalidStreamId | TransportError::FinalSizeError => {
+            Error::ClosedCriticalStream
+        }
+        _ => {
+            debug_assert!(false, "Unexpected error");
+            Error::InternalError
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::mem;
+
+    use neqo_transport::{ConnectionParameters, StreamId, StreamType};
+    use test_fixture::{default_client, default_server, handshake, new_server, now, DEFAULT_ALPN};
+
+    use super::{Connection, Error, Header, QPackEncoder, Res};
+    use crate::QpackSettings;
+
+    struct TestEncoder {
+        encoder: QPackEncoder,
+        send_stream_id: StreamId,
+        recv_stream_id: StreamId,
+        conn: Connection,
+        peer_conn: Connection,
+    }
+
+    impl TestEncoder {
+        pub fn change_capacity(&mut self, capacity: u64) -> Res<()> {
+            self.encoder.set_max_capacity(capacity).unwrap();
+            // We will try to really change the table only when we send the change capacity
+            // instruction.
+            self.encoder.send_encoder_updates(&mut self.conn)
+        }
+
+        pub fn insert(&mut self, header: &[u8], value: &[u8], inst: &[u8]) {
+            let res = self.encoder.send_and_insert(&mut self.conn, header, value);
+            assert!(res.is_ok());
+            self.send_instructions(inst);
+        }
+
+        pub fn encode_header_block(
+            &mut self,
+            stream_id: StreamId,
+            headers: &[Header],
+            expected_encoding: &[u8],
+            inst: &[u8],
+        ) {
+            let buf = self
+                .encoder
+                .encode_header_block(&mut self.conn, headers, stream_id);
+            assert_eq!(&buf[..], expected_encoding);
+            self.send_instructions(inst);
+        }
+
+        pub fn send_instructions(&mut self, encoder_instruction: &[u8]) {
+            self.encoder.send_encoder_updates(&mut self.conn).unwrap();
+            let out = self.conn.process(None, now());
+            let out2 = self.peer_conn.process(out.as_dgram_ref(), now());
+            mem::drop(self.conn.process(out2.as_dgram_ref(), now()));
+            let mut buf = [0_u8; 100];
+            let (amount, fin) = self
+                .peer_conn
+                .stream_recv(self.send_stream_id, &mut buf)
+                .unwrap();
+            assert!(!fin);
+            assert_eq!(buf[..amount], encoder_instruction[..]);
+        }
+    }
+
+    fn connect_generic(huffman: bool, max_data: Option<u64>) -> TestEncoder {
+        let mut conn = default_client();
+        let mut peer_conn = max_data.map_or_else(default_server, |max| {
+            new_server(
+                DEFAULT_ALPN,
+                ConnectionParameters::default()
+                    .max_stream_data(StreamType::UniDi, true, max)
+                    .max_stream_data(StreamType::BiDi, true, max)
+                    .max_stream_data(StreamType::BiDi, false, max),
+            )
+        });
+        handshake(&mut conn, &mut peer_conn);
+
+        // create a stream
+        let recv_stream_id = peer_conn.stream_create(StreamType::UniDi).unwrap();
+        let send_stream_id = conn.stream_create(StreamType::UniDi).unwrap();
+
+        // create an encoder
+        let mut encoder = QPackEncoder::new(
+            &QpackSettings {
+                max_table_size_encoder: 1500,
+                max_table_size_decoder: 0,
+                max_blocked_streams: 0,
+            },
+            huffman,
+        );
+        encoder.add_send_stream(send_stream_id);
+
+        TestEncoder {
+            encoder,
+            send_stream_id,
+            recv_stream_id,
+            conn,
+            peer_conn,
+        }
+    }
+
+    fn connect(huffman: bool) -> TestEncoder {
+        connect_generic(huffman, None)
+    }
+
+    fn connect_flow_control(max_data: u64) -> TestEncoder {
+        connect_generic(true, Some(max_data))
+    }
+
+    fn recv_instruction(encoder: &mut TestEncoder, decoder_instruction: &[u8]) {
+        encoder
+            .peer_conn
+            .stream_send(encoder.recv_stream_id, decoder_instruction)
+            .unwrap();
+        let out = encoder.peer_conn.process(None, now());
+        mem::drop(encoder.conn.process(out.as_dgram_ref(), now()));
+        assert!(encoder
+            .encoder
+            .read_instructions(&mut encoder.conn, encoder.recv_stream_id)
+            .is_ok());
+    }
+
+    const CAP_INSTRUCTION_200: &[u8] = &[0x02, 0x3f, 0xa9, 0x01];
+    const CAP_INSTRUCTION_60: &[u8] = &[0x02, 0x3f, 0x1d];
+    const CAP_INSTRUCTION_1000: &[u8] = &[0x02, 0x3f, 0xc9, 0x07];
+    const CAP_INSTRUCTION_1500: &[u8] = &[0x02, 0x3f, 0xbd, 0x0b];
+
+    const HEADER_CONTENT_LENGTH: &[u8] = &[
+        0x63, 0x6f, 0x6e, 0x74, 0x65, 0x6e, 0x74, 0x2d, 0x6c, 0x65, 0x6e, 0x67, 0x74, 0x68,
+    ];
+    const VALUE_1: &[u8] = &[0x31, 0x32, 0x33, 0x34];
+    const VALUE_2: &[u8] = &[0x31, 0x32, 0x33, 0x34, 0x35];
+
+    // HEADER_CONTENT_LENGTH and VALUE_1 encoded by instruction insert_with_name_literal.
+    const HEADER_CONTENT_LENGTH_VALUE_1_NAME_LITERAL: &[u8] = &[
+        0x4e, 0x63, 0x6f, 0x6e, 0x74, 0x65, 0x6e, 0x74, 0x2d, 0x6c, 0x65, 0x6e, 0x67, 0x74, 0x68,
+        0x04, 0x31, 0x32, 0x33, 0x34,
+    ];
+
+    // HEADER_CONTENT_LENGTH and VALUE_2 encoded by instruction insert_with_name_literal.
+    const HEADER_CONTENT_LENGTH_VALUE_2_NAME_LITERAL: &[u8] = &[
+        0x4e, 0x63, 0x6f, 0x6e, 0x74, 0x65, 0x6e, 0x74, 0x2d, 0x6c, 0x65, 0x6e, 0x67, 0x74, 0x68,
+        0x05, 0x31, 0x32, 0x33, 0x34, 0x35,
+    ];
+
+    // Indexed Header Field that refers to the first entry in the dynamic table.
+    const ENCODE_INDEXED_REF_DYNAMIC: &[u8] = &[0x02, 0x00, 0x80];
+
+    const STREAM_1: StreamId = StreamId::new(1);
+    const STREAM_2: StreamId = StreamId::new(2);
+    const HEADER_ACK_STREAM_ID_1: &[u8] = &[0x81];
+    const HEADER_ACK_STREAM_ID_2: &[u8] = &[0x82];
+    const STREAM_CANCELED_ID_1: &[u8] = &[0x41];
+
+    // test insert_with_name_literal which fails because there is not enough space in the table
+    #[test]
+    fn test_insert_with_name_literal_1() {
+        let mut encoder = connect(false);
+
+        // insert "content-length: 1234
+        let res =
+            encoder
+                .encoder
+                .send_and_insert(&mut encoder.conn, HEADER_CONTENT_LENGTH, VALUE_1);
+        assert_eq!(Error::DynamicTableFull, res.unwrap_err());
+        encoder.send_instructions(&[0x02]);
+    }
+
+    // test insert_with_name_literal - succeeds
+    #[test]
+    fn test_insert_with_name_literal_2() {
+        let mut encoder = connect(false);
+
+        assert!(encoder.encoder.set_max_capacity(200).is_ok());
+        // test the change capacity instruction.
+        encoder.send_instructions(CAP_INSTRUCTION_200);
+
+        // insert "content-length: 1234
+        let res =
+            encoder
+                .encoder
+                .send_and_insert(&mut encoder.conn, HEADER_CONTENT_LENGTH, VALUE_1);
+        assert!(res.is_ok());
+        encoder.send_instructions(HEADER_CONTENT_LENGTH_VALUE_1_NAME_LITERAL);
+    }
+
+    #[test]
+    fn test_change_capacity() {
+        let mut encoder = connect(false);
+
+        assert!(encoder.encoder.set_max_capacity(200).is_ok());
+        encoder.send_instructions(CAP_INSTRUCTION_200);
+    }
+
+    struct TestElement {
+        pub headers: Vec<Header>,
+        pub header_block: &'static [u8],
+        pub encoder_inst: &'static [u8],
+    }
+
+    #[test]
+    fn test_header_block_encoder_non() {
+        let test_cases: [TestElement; 6] = [
+            // test a header with ref to static - encode_indexed
+            TestElement {
+                headers: vec![Header::new(":method", "GET")],
+                header_block: &[0x00, 0x00, 0xd1],
+                encoder_inst: &[],
+            },
+            // test encode_literal_with_name_ref
+            TestElement {
+                headers: vec![Header::new(":path", "/somewhere")],
+                header_block: &[
+                    0x00, 0x00, 0x51, 0x0a, 0x2f, 0x73, 0x6f, 0x6d, 0x65, 0x77, 0x68, 0x65, 0x72,
+                    0x65,
+                ],
+                encoder_inst: &[],
+            },
+            // test adding a new header and encode_post_base_index, also test
+            // fix_header_block_prefix
+            TestElement {
+                headers: vec![Header::new("my-header", "my-value")],
+                header_block: &[0x02, 0x80, 0x10],
+                encoder_inst: &[
+                    0x49, 0x6d, 0x79, 0x2d, 0x68, 0x65, 0x61, 0x64, 0x65, 0x72, 0x08, 0x6d, 0x79,
+                    0x2d, 0x76, 0x61, 0x6c, 0x75, 0x65,
+                ],
+            },
+            // test encode_indexed with a ref to dynamic table.
+            TestElement {
+                headers: vec![Header::new("my-header", "my-value")],
+                header_block: ENCODE_INDEXED_REF_DYNAMIC,
+                encoder_inst: &[],
+            },
+            // test encode_literal_with_name_ref.
+            TestElement {
+                headers: vec![Header::new("my-header", "my-value2")],
+                header_block: &[
+                    0x02, 0x00, 0x40, 0x09, 0x6d, 0x79, 0x2d, 0x76, 0x61, 0x6c, 0x75, 0x65, 0x32,
+                ],
+                encoder_inst: &[],
+            },
+            // test multiple headers
+            TestElement {
+                headers: vec![
+                    Header::new(":method", "GET"),
+                    Header::new(":path", "/somewhere"),
+                    Header::new(":authority", "example.com"),
+                    Header::new(":scheme", "https"),
+                ],
+                header_block: &[
+                    0x00, 0x01, 0xd1, 0x51, 0x0a, 0x2f, 0x73, 0x6f, 0x6d, 0x65, 0x77, 0x68, 0x65,
+                    0x72, 0x65, 0x50, 0x0b, 0x65, 0x78, 0x61, 0x6d, 0x70, 0x6c, 0x65, 0x2e, 0x63,
+                    0x6f, 0x6d, 0xd7,
+                ],
+                encoder_inst: &[],
+            },
+        ];
+
+        let mut encoder = connect(false);
+
+        encoder.encoder.set_max_blocked_streams(100).unwrap();
+        encoder.encoder.set_max_capacity(200).unwrap();
+
+        // test the change capacity instruction.
+        encoder.send_instructions(CAP_INSTRUCTION_200);
+
+        for t in &test_cases {
+            let buf = encoder
+                .encoder
+                .encode_header_block(&mut encoder.conn, &t.headers, STREAM_1);
+            assert_eq!(&buf[..], t.header_block);
+            encoder.send_instructions(t.encoder_inst);
+        }
+    }
+
+    #[test]
+    fn test_header_block_encoder_huffman() {
+        let test_cases: [TestElement; 6] = [
+            // test a header with ref to static - encode_indexed
+            TestElement {
+                headers: vec![Header::new(":method", "GET")],
+                header_block: &[0x00, 0x00, 0xd1],
+                encoder_inst: &[],
+            },
+            // test encode_literal_with_name_ref
+            TestElement {
+                headers: vec![Header::new(":path", "/somewhere")],
+                header_block: &[
+                    0x00, 0x00, 0x51, 0x87, 0x61, 0x07, 0xa4, 0xbe, 0x27, 0x2d, 0x85,
+                ],
+                encoder_inst: &[],
+            },
+            // test adding a new header and encode_post_base_index, also test
+            // fix_header_block_prefix
+            TestElement {
+                headers: vec![Header::new("my-header", "my-value")],
+                header_block: &[0x02, 0x80, 0x10],
+                encoder_inst: &[
+                    0x67, 0xa7, 0xd2, 0xd3, 0x94, 0x72, 0x16, 0xcf, 0x86, 0xa7, 0xd2, 0xdd, 0xc7,
+                    0x45, 0xa5,
+                ],
+            },
+            // test encode_indexed with a ref to dynamic table.
+            TestElement {
+                headers: vec![Header::new("my-header", "my-value")],
+                header_block: ENCODE_INDEXED_REF_DYNAMIC,
+                encoder_inst: &[],
+            },
+            // test encode_literal_with_name_ref.
+            TestElement {
+                headers: vec![Header::new("my-header", "my-value2")],
+                header_block: &[
+                    0x02, 0x00, 0x40, 0x87, 0xa7, 0xd2, 0xdd, 0xc7, 0x45, 0xa5, 0x17,
+                ],
+                encoder_inst: &[],
+            },
+            // test multiple headers
+            TestElement {
+                headers: vec![
+                    Header::new(":method", "GET"),
+                    Header::new(":path", "/somewhere"),
+                    Header::new(":authority", "example.com"),
+                    Header::new(":scheme", "https"),
+                ],
+                header_block: &[
+                    0x00, 0x01, 0xd1, 0x51, 0x87, 0x61, 0x07, 0xa4, 0xbe, 0x27, 0x2d, 0x85, 0x50,
+                    0x88, 0x2f, 0x91, 0xd3, 0x5d, 0x05, 0x5c, 0x87, 0xa7, 0xd7,
+                ],
+                encoder_inst: &[],
+            },
+        ];
+
+        let mut encoder = connect(true);
+
+        encoder.encoder.set_max_blocked_streams(100).unwrap();
+        encoder.encoder.set_max_capacity(200).unwrap();
+
+        // test the change capacity instruction.
+        encoder.send_instructions(CAP_INSTRUCTION_200);
+
+        for t in &test_cases {
+            let buf = encoder
+                .encoder
+                .encode_header_block(&mut encoder.conn, &t.headers, STREAM_1);
+            assert_eq!(&buf[..], t.header_block);
+            encoder.send_instructions(t.encoder_inst);
+        }
+    }
+
+    // Test inserts block on waiting for an insert count increment.
+    #[test]
+    fn test_insertion_blocked_on_insert_count_feedback() {
+        let mut encoder = connect(false);
+
+        encoder.encoder.set_max_capacity(60).unwrap();
+
+        // test the change capacity instruction.
+        encoder.send_instructions(CAP_INSTRUCTION_60);
+
+        // insert "content-length: 1234
+        let res =
+            encoder
+                .encoder
+                .send_and_insert(&mut encoder.conn, HEADER_CONTENT_LENGTH, VALUE_1);
+        assert!(res.is_ok());
+        encoder.send_instructions(HEADER_CONTENT_LENGTH_VALUE_1_NAME_LITERAL);
+
+        // insert "content-length: 12345 which will fail because the ntry in the table cannot be
+        // evicted.
+        let res =
+            encoder
+                .encoder
+                .send_and_insert(&mut encoder.conn, HEADER_CONTENT_LENGTH, VALUE_2);
+        assert!(res.is_err());
+        encoder.send_instructions(&[]);
+
+        // receive an insert count increment.
+        recv_instruction(&mut encoder, &[0x01]);
+
+        // insert "content-length: 12345 again it will succeed.
+        let res =
+            encoder
+                .encoder
+                .send_and_insert(&mut encoder.conn, HEADER_CONTENT_LENGTH, VALUE_2);
+        assert!(res.is_ok());
+        encoder.send_instructions(HEADER_CONTENT_LENGTH_VALUE_2_NAME_LITERAL);
+    }
+
+    // Test inserts block on waiting for acks
+    // test the table insertion is blocked:
+    // 0 - waiting for a header ack
+    // 2 - waiting for a stream cancel.
+    fn test_insertion_blocked_on_waiting_for_header_ack_or_stream_cancel(wait: u8) {
+        let mut encoder = connect(false);
+
+        assert!(encoder.encoder.set_max_capacity(60).is_ok());
+        // test the change capacity instruction.
+        encoder.send_instructions(CAP_INSTRUCTION_60);
+
+        // insert "content-length: 1234
+        let res =
+            encoder
+                .encoder
+                .send_and_insert(&mut encoder.conn, HEADER_CONTENT_LENGTH, VALUE_1);
+        assert!(res.is_ok());
+        encoder.send_instructions(HEADER_CONTENT_LENGTH_VALUE_1_NAME_LITERAL);
+
+        // receive an insert count increment.
+        recv_instruction(&mut encoder, &[0x01]);
+
+        // send a header block
+        let buf = encoder.encoder.encode_header_block(
+            &mut encoder.conn,
+            &[Header::new("content-length", "1234")],
+            STREAM_1,
+        );
+        assert_eq!(&buf[..], ENCODE_INDEXED_REF_DYNAMIC);
+        encoder.send_instructions(&[]);
+
+        // insert "content-length: 12345 which will fail because the entry in the table cannot be
+        // evicted
+        let res =
+            encoder
+                .encoder
+                .send_and_insert(&mut encoder.conn, HEADER_CONTENT_LENGTH, VALUE_2);
+        assert!(res.is_err());
+        encoder.send_instructions(&[]);
+
+        if wait == 0 {
+            // receive a header_ack.
+            recv_instruction(&mut encoder, HEADER_ACK_STREAM_ID_1);
+        } else {
+            // receive a stream canceled
+            recv_instruction(&mut encoder, STREAM_CANCELED_ID_1);
+        }
+
+        // insert "content-length: 12345 again it will succeed.
+        let res =
+            encoder
+                .encoder
+                .send_and_insert(&mut encoder.conn, HEADER_CONTENT_LENGTH, VALUE_2);
+        assert!(res.is_ok());
+        encoder.send_instructions(HEADER_CONTENT_LENGTH_VALUE_2_NAME_LITERAL);
+    }
+
+    #[test]
+    fn test_header_ack() {
+        test_insertion_blocked_on_waiting_for_header_ack_or_stream_cancel(0);
+    }
+
+    #[test]
+    fn test_stream_canceled() {
+        test_insertion_blocked_on_waiting_for_header_ack_or_stream_cancel(1);
+    }
+
+    fn assert_is_index_to_dynamic(buf: &[u8]) {
+        assert_eq!(buf[2] & 0xc0, 0x80);
+    }
+
+    fn assert_is_index_to_dynamic_post(buf: &[u8]) {
+        assert_eq!(buf[2] & 0xf0, 0x10);
+    }
+
+    fn assert_is_index_to_static_name_only(buf: &[u8]) {
+        assert_eq!(buf[2] & 0xf0, 0x50);
+    }
+
+    fn assert_is_literal_value_literal_name(buf: &[u8]) {
+        assert_eq!(buf[2] & 0xf0, 0x20);
+    }
+
+    #[test]
+    fn max_block_streams1() {
+        let mut encoder = connect(false);
+
+        assert!(encoder.encoder.set_max_capacity(60).is_ok());
+
+        // change capacity to 60.
+        encoder.send_instructions(CAP_INSTRUCTION_60);
+
+        // insert "content-length: 1234
+        let res =
+            encoder
+                .encoder
+                .send_and_insert(&mut encoder.conn, HEADER_CONTENT_LENGTH, VALUE_1);
+
+        assert!(res.is_ok());
+        encoder.send_instructions(HEADER_CONTENT_LENGTH_VALUE_1_NAME_LITERAL);
+
+        encoder.encoder.set_max_blocked_streams(1).unwrap();
+
+        // send a header block, it refers to unacked entry.
+        let buf = encoder.encoder.encode_header_block(
+            &mut encoder.conn,
+            &[Header::new("content-length", "1234")],
+            STREAM_1,
+        );
+        assert_is_index_to_dynamic(&buf);
+
+        assert_eq!(encoder.encoder.blocked_stream_cnt(), 1);
+
+        encoder.send_instructions(&[]);
+
+        // The next one will not use the dynamic entry because it is exceeding the
+        // max_blocked_streams limit.
+        let buf = encoder.encoder.encode_header_block(
+            &mut encoder.conn,
+            &[Header::new("content-length", "1234")],
+            StreamId::new(2),
+        );
+        assert_is_index_to_static_name_only(&buf);
+
+        encoder.send_instructions(&[]);
+        assert_eq!(encoder.encoder.blocked_stream_cnt(), 1);
+
+        // another header block to already blocked stream can still use the entry.
+        let buf = encoder.encoder.encode_header_block(
+            &mut encoder.conn,
+            &[Header::new("content-length", "1234")],
+            STREAM_1,
+        );
+        assert_is_index_to_dynamic(&buf);
+
+        assert_eq!(encoder.encoder.blocked_stream_cnt(), 1);
+    }
+
+    #[test]
+    fn max_block_streams2() {
+        let mut encoder = connect(false);
+
+        assert!(encoder.encoder.set_max_capacity(200).is_ok());
+
+        // change capacity to 200.
+        encoder.send_instructions(CAP_INSTRUCTION_200);
+
+        // insert "content-length: 1234
+        let res =
+            encoder
+                .encoder
+                .send_and_insert(&mut encoder.conn, HEADER_CONTENT_LENGTH, VALUE_1);
+
+        assert!(res.is_ok());
+        encoder.send_instructions(HEADER_CONTENT_LENGTH_VALUE_1_NAME_LITERAL);
+
+        // insert "content-length: 12345
+        let res =
+            encoder
+                .encoder
+                .send_and_insert(&mut encoder.conn, HEADER_CONTENT_LENGTH, VALUE_2);
+
+        assert!(res.is_ok());
+        encoder.send_instructions(HEADER_CONTENT_LENGTH_VALUE_2_NAME_LITERAL);
+
+        encoder.encoder.set_max_blocked_streams(1).unwrap();
+
+        // send a header block, it refers to unacked entry.
+        let buf = encoder.encoder.encode_header_block(
+            &mut encoder.conn,
+            &[Header::new("content-length", "1234")],
+            STREAM_1,
+        );
+        assert_is_index_to_dynamic(&buf);
+
+        // encode another header block for the same stream that will refer to the second entry
+        // in the dynamic table.
+        // This should work because the stream is already a blocked stream
+        // send a header block, it refers to unacked entry.
+        let buf = encoder.encoder.encode_header_block(
+            &mut encoder.conn,
+            &[Header::new("content-length", "12345")],
+            STREAM_1,
+        );
+        assert_is_index_to_dynamic(&buf);
+    }
+
+    #[test]
+    fn max_block_streams3() {
+        let mut encoder = connect(false);
+
+        assert!(encoder.encoder.set_max_capacity(200).is_ok());
+
+        // change capacity to 200.
+        encoder.send_instructions(CAP_INSTRUCTION_200);
+
+        encoder.encoder.set_max_blocked_streams(1).unwrap();
+
+        assert_eq!(encoder.encoder.blocked_stream_cnt(), 0);
+
+        // send a header block, that creates an new entry and refers to it.
+        let buf = encoder.encoder.encode_header_block(
+            &mut encoder.conn,
+            &[Header::new("name1", "value1")],
+            STREAM_1,
+        );
+        assert_is_index_to_dynamic_post(&buf);
+
+        assert_eq!(encoder.encoder.blocked_stream_cnt(), 1);
+
+        // The next one will not create a new entry because the encoder is on max_blocked_streams
+        // limit.
+        let buf = encoder.encoder.encode_header_block(
+            &mut encoder.conn,
+            &[Header::new("name2", "value2")],
+            STREAM_2,
+        );
+        assert_is_literal_value_literal_name(&buf);
+
+        assert_eq!(encoder.encoder.blocked_stream_cnt(), 1);
+
+        // another header block to already blocked stream can still create a new entry.
+        let buf = encoder.encoder.encode_header_block(
+            &mut encoder.conn,
+            &[Header::new("name2", "value2")],
+            STREAM_1,
+        );
+        assert_is_index_to_dynamic_post(&buf);
+
+        assert_eq!(encoder.encoder.blocked_stream_cnt(), 1);
+    }
+
+    #[test]
+    fn max_block_streams4() {
+        let mut encoder = connect(false);
+
+        assert!(encoder.encoder.set_max_capacity(200).is_ok());
+
+        // change capacity to 200.
+        encoder.send_instructions(CAP_INSTRUCTION_200);
+
+        encoder.encoder.set_max_blocked_streams(1).unwrap();
+
+        assert_eq!(encoder.encoder.blocked_stream_cnt(), 0);
+
+        // send a header block, that creates an new entry and refers to it.
+        let buf = encoder.encoder.encode_header_block(
+            &mut encoder.conn,
+            &[Header::new("name1", "value1")],
+            STREAM_1,
+        );
+        assert_is_index_to_dynamic_post(&buf);
+
+        assert_eq!(encoder.encoder.blocked_stream_cnt(), 1);
+
+        // another header block to already blocked stream can still create a new entry.
+        let buf = encoder.encoder.encode_header_block(
+            &mut encoder.conn,
+            &[Header::new("name2", "value2")],
+            STREAM_1,
+        );
+        assert_is_index_to_dynamic_post(&buf);
+
+        assert_eq!(encoder.encoder.blocked_stream_cnt(), 1);
+
+        // receive a header_ack for the first header block.
+        recv_instruction(&mut encoder, HEADER_ACK_STREAM_ID_1);
+
+        // The stream is still blocking because the second header block is not acked.
+        assert_eq!(encoder.encoder.blocked_stream_cnt(), 1);
+    }
+
+    #[test]
+    fn max_block_streams5() {
+        let mut encoder = connect(false);
+
+        assert!(encoder.encoder.set_max_capacity(200).is_ok());
+
+        // change capacity to 200.
+        encoder.send_instructions(CAP_INSTRUCTION_200);
+
+        encoder.encoder.set_max_blocked_streams(1).unwrap();
+
+        assert_eq!(encoder.encoder.blocked_stream_cnt(), 0);
+
+        // send a header block, that creates an new entry and refers to it.
+        let buf = encoder.encoder.encode_header_block(
+            &mut encoder.conn,
+            &[Header::new("name1", "value1")],
+            STREAM_1,
+        );
+        assert_is_index_to_dynamic_post(&buf);
+
+        assert_eq!(encoder.encoder.blocked_stream_cnt(), 1);
+
+        // another header block to already blocked stream can still create a new entry.
+        let buf = encoder.encoder.encode_header_block(
+            &mut encoder.conn,
+            &[Header::new("name1", "value1")],
+            STREAM_1,
+        );
+        assert_is_index_to_dynamic(&buf);
+
+        assert_eq!(encoder.encoder.blocked_stream_cnt(), 1);
+
+        // receive a header_ack for the first header block.
+        recv_instruction(&mut encoder, HEADER_ACK_STREAM_ID_1);
+
+        // The stream is not blocking anymore because header ack also acks the instruction.
+        assert_eq!(encoder.encoder.blocked_stream_cnt(), 0);
+    }
+
+    #[test]
+    fn max_block_streams6() {
+        let mut encoder = connect(false);
+
+        assert!(encoder.encoder.set_max_capacity(200).is_ok());
+
+        // change capacity to 200.
+        encoder.send_instructions(CAP_INSTRUCTION_200);
+
+        encoder.encoder.set_max_blocked_streams(2).unwrap();
+
+        assert_eq!(encoder.encoder.blocked_stream_cnt(), 0);
+
+        // send a header block, that creates an new entry and refers to it.
+        let buf = encoder.encoder.encode_header_block(
+            &mut encoder.conn,
+            &[Header::new("name1", "value1")],
+            STREAM_1,
+        );
+        assert_is_index_to_dynamic_post(&buf);
+
+        assert_eq!(encoder.encoder.blocked_stream_cnt(), 1);
+
+        // header block for the next stream will create an new entry as well.
+        let buf = encoder.encoder.encode_header_block(
+            &mut encoder.conn,
+            &[Header::new("name2", "value2")],
+            STREAM_2,
+        );
+        assert_is_index_to_dynamic_post(&buf);
+
+        assert_eq!(encoder.encoder.blocked_stream_cnt(), 2);
+
+        // receive a header_ack for the second header block. This will ack the first as well
+        recv_instruction(&mut encoder, HEADER_ACK_STREAM_ID_2);
+
+        // The stream is not blocking anymore because header ack also acks the instruction.
+        assert_eq!(encoder.encoder.blocked_stream_cnt(), 0);
+    }
+
+    #[test]
+    fn max_block_streams7() {
+        let mut encoder = connect(false);
+
+        assert!(encoder.encoder.set_max_capacity(200).is_ok());
+
+        // change capacity to 200.
+        encoder.send_instructions(CAP_INSTRUCTION_200);
+
+        encoder.encoder.set_max_blocked_streams(2).unwrap();
+
+        assert_eq!(encoder.encoder.blocked_stream_cnt(), 0);
+
+        // send a header block, that creates an new entry and refers to it.
+        let buf = encoder.encoder.encode_header_block(
+            &mut encoder.conn,
+            &[Header::new("name1", "value1")],
+            STREAM_1,
+        );
+        assert_is_index_to_dynamic_post(&buf);
+
+        assert_eq!(encoder.encoder.blocked_stream_cnt(), 1);
+
+        // header block for the next stream will create an new entry as well.
+        let buf = encoder.encoder.encode_header_block(
+            &mut encoder.conn,
+            &[Header::new("name1", "value1")],
+            STREAM_2,
+        );
+        assert_is_index_to_dynamic(&buf);
+
+        assert_eq!(encoder.encoder.blocked_stream_cnt(), 2);
+
+        // receive a stream cancel for the first stream.
+        // This will remove the first stream as blocking but it will not mark the instruction as
+        // acked. and the second steam will still be blocking.
+        recv_instruction(&mut encoder, STREAM_CANCELED_ID_1);
+
+        // The stream is not blocking anymore because header ack also acks the instruction.
+        assert_eq!(encoder.encoder.blocked_stream_cnt(), 1);
+    }
+
+    #[test]
+    fn max_block_stream8() {
+        let mut encoder = connect(false);
+
+        assert!(encoder.encoder.set_max_capacity(200).is_ok());
+
+        // change capacity to 200.
+        encoder.send_instructions(CAP_INSTRUCTION_200);
+
+        encoder.encoder.set_max_blocked_streams(2).unwrap();
+
+        assert_eq!(encoder.encoder.blocked_stream_cnt(), 0);
+
+        // send a header block, that creates an new entry and refers to it.
+        let buf = encoder.encoder.encode_header_block(
+            &mut encoder.conn,
+            &[Header::new("name1", "value1")],
+            STREAM_1,
+        );
+        assert_is_index_to_dynamic_post(&buf);
+
+        assert_eq!(encoder.encoder.blocked_stream_cnt(), 1);
+
+        // header block for the next stream will refer to the same entry.
+        let buf = encoder.encoder.encode_header_block(
+            &mut encoder.conn,
+            &[Header::new("name1", "value1")],
+            STREAM_2,
+        );
+        assert_is_index_to_dynamic(&buf);
+
+        assert_eq!(encoder.encoder.blocked_stream_cnt(), 2);
+
+        // send another header block on stream 1.
+        let buf = encoder.encoder.encode_header_block(
+            &mut encoder.conn,
+            &[Header::new("name2", "value2")],
+            STREAM_1,
+        );
+        assert_is_index_to_dynamic_post(&buf);
+
+        assert_eq!(encoder.encoder.blocked_stream_cnt(), 2);
+
+        // stream 1 is block on entries 1 and 2; stream 2 is block only on 1.
+        // receive an Insert Count Increment for the first entry.
+        // After that only stream 1 will be blocking.
+        recv_instruction(&mut encoder, &[0x01]);
+
+        assert_eq!(encoder.encoder.blocked_stream_cnt(), 1);
+    }
+
+    #[test]
+    fn dynamic_table_can_evict1() {
+        let mut encoder = connect(false);
+
+        assert!(encoder.encoder.set_max_capacity(60).is_ok());
+
+        // change capacity to 60.
+        encoder.send_instructions(CAP_INSTRUCTION_60);
+
+        encoder.encoder.set_max_blocked_streams(2).unwrap();
+
+        // insert "content-length: 1234
+        let res =
+            encoder
+                .encoder
+                .send_and_insert(&mut encoder.conn, HEADER_CONTENT_LENGTH, VALUE_1);
+
+        assert!(res.is_ok());
+        encoder.send_instructions(HEADER_CONTENT_LENGTH_VALUE_1_NAME_LITERAL);
+
+        // send a header block, it refers to unacked entry.
+        let buf = encoder.encoder.encode_header_block(
+            &mut encoder.conn,
+            &[Header::new("content-length", "1234")],
+            STREAM_1,
+        );
+        assert_is_index_to_dynamic(&buf);
+
+        // trying to evict the entry will failed.
+        assert!(encoder.change_capacity(10).is_err());
+
+        // receive an Insert Count Increment for the entry.
+        recv_instruction(&mut encoder, &[0x01]);
+
+        // trying to evict the entry will failed. The stream is still referring to it.
+        assert!(encoder.change_capacity(10).is_err());
+
+        // receive a header_ack for the header block.
+        recv_instruction(&mut encoder, HEADER_ACK_STREAM_ID_1);
+
+        // now entry can be evicted.
+        assert!(encoder.change_capacity(10).is_ok());
+    }
+
+    #[test]
+    fn dynamic_table_can_evict2() {
+        let mut encoder = connect(false);
+
+        assert!(encoder.encoder.set_max_capacity(60).is_ok());
+
+        // change capacity to 60.
+        encoder.send_instructions(CAP_INSTRUCTION_60);
+
+        encoder.encoder.set_max_blocked_streams(2).unwrap();
+
+        // insert "content-length: 1234
+        let res =
+            encoder
+                .encoder
+                .send_and_insert(&mut encoder.conn, HEADER_CONTENT_LENGTH, VALUE_1);
+
+        assert!(res.is_ok());
+        encoder.send_instructions(HEADER_CONTENT_LENGTH_VALUE_1_NAME_LITERAL);
+
+        // send a header block, it refers to unacked entry.
+        let buf = encoder.encoder.encode_header_block(
+            &mut encoder.conn,
+            &[Header::new("content-length", "1234")],
+            STREAM_1,
+        );
+        assert_is_index_to_dynamic(&buf);
+
+        // trying to evict the entry will failed.
+        assert!(encoder.change_capacity(10).is_err());
+
+        // receive an Insert Count Increment for the entry.
+        recv_instruction(&mut encoder, &[0x01]);
+
+        // trying to evict the entry will failed. The stream is still referring to it.
+        assert!(encoder.change_capacity(10).is_err());
+
+        // receive a stream cancelled.
+        recv_instruction(&mut encoder, STREAM_CANCELED_ID_1);
+
+        // now entry can be evicted.
+        assert!(encoder.change_capacity(10).is_ok());
+    }
+
+    #[test]
+    fn dynamic_table_can_evict3() {
+        let mut encoder = connect(false);
+
+        assert!(encoder.encoder.set_max_capacity(60).is_ok());
+
+        // change capacity to 60.
+        encoder.send_instructions(CAP_INSTRUCTION_60);
+
+        encoder.encoder.set_max_blocked_streams(2).unwrap();
+
+        // insert "content-length: 1234
+        let res =
+            encoder
+                .encoder
+                .send_and_insert(&mut encoder.conn, HEADER_CONTENT_LENGTH, VALUE_1);
+
+        assert!(res.is_ok());
+        encoder.send_instructions(HEADER_CONTENT_LENGTH_VALUE_1_NAME_LITERAL);
+
+        // trying to evict the entry will failed, because the entry is not acked.
+        assert!(encoder.change_capacity(10).is_err());
+
+        // receive an Insert Count Increment for the entry.
+        recv_instruction(&mut encoder, &[0x01]);
+
+        // now entry can be evicted.
+        assert!(encoder.change_capacity(10).is_ok());
+    }
+
+    #[test]
+    fn dynamic_table_can_evict4() {
+        let mut encoder = connect(false);
+
+        assert!(encoder.encoder.set_max_capacity(60).is_ok());
+
+        // change capacity to 60.
+        encoder.send_instructions(CAP_INSTRUCTION_60);
+
+        encoder.encoder.set_max_blocked_streams(2).unwrap();
+
+        // insert "content-length: 1234
+        let res =
+            encoder
+                .encoder
+                .send_and_insert(&mut encoder.conn, HEADER_CONTENT_LENGTH, VALUE_1);
+
+        assert!(res.is_ok());
+        encoder.send_instructions(HEADER_CONTENT_LENGTH_VALUE_1_NAME_LITERAL);
+
+        // send a header block, it refers to unacked entry.
+        let buf = encoder.encoder.encode_header_block(
+            &mut encoder.conn,
+            &[Header::new("content-length", "1234")],
+            STREAM_1,
+        );
+        assert_is_index_to_dynamic(&buf);
+
+        // trying to evict the entry will failed. The stream is still referring to it and
+        // entry is not acked.
+        assert!(encoder.change_capacity(10).is_err());
+
+        // receive a header_ack for the header block. This will also ack the instruction.
+        recv_instruction(&mut encoder, HEADER_ACK_STREAM_ID_1);
+
+        // now entry can be evicted.
+        assert!(encoder.change_capacity(10).is_ok());
+    }
+
+    #[test]
+    fn encoder_flow_controlled_blocked() {
+        const SMALL_MAX_DATA: u64 = 20;
+        const ONE_INSTRUCTION_1: &[u8] = &[
+            0x67, 0x41, 0xe9, 0x2a, 0x67, 0x35, 0x53, 0x7f, 0x83, 0x8, 0x99, 0x6b,
+        ];
+        const ONE_INSTRUCTION_2: &[u8] = &[
+            0x67, 0x41, 0xe9, 0x2a, 0x67, 0x35, 0x53, 0x37, 0x83, 0x8, 0x99, 0x6b,
+        ];
+
+        let mut encoder = connect_flow_control(SMALL_MAX_DATA);
+
+        // change capacity to 1000 and max_block streams to 20.
+        encoder.encoder.set_max_blocked_streams(20).unwrap();
+        assert!(encoder.encoder.set_max_capacity(1000).is_ok());
+        encoder.send_instructions(CAP_INSTRUCTION_1000);
+
+        // Encode a header block with 2 headers. The first header will be added to the dynamic
+        // table. The second will not be added to the dynamic table, because the
+        // corresponding instruction cannot be written immediately due to the flow control
+        // limit.
+        let buf1 = encoder.encoder.encode_header_block(
+            &mut encoder.conn,
+            &[
+                Header::new("something", "1234"),
+                Header::new("something2", "12345678910"),
+            ],
+            STREAM_1,
+        );
+
+        // Assert that the first header is encoded as an index to the dynamic table (a post form).
+        assert_eq!(buf1[2], 0x10);
+        // Assert that the second header is encoded as a literal with a name literal
+        assert_eq!(buf1[3] & 0xf0, 0x20);
+
+        // Try to encode another header block. Here both headers will be encoded as a literal with a
+        // name literal
+        let buf2 = encoder.encoder.encode_header_block(
+            &mut encoder.conn,
+            &[
+                Header::new("something3", "1234"),
+                Header::new("something4", "12345678910"),
+            ],
+            STREAM_2,
+        );
+        assert_eq!(buf2[2] & 0xf0, 0x20);
+
+        // Ensure that we have sent only one instruction for (String::from("something", "1234"))
+        encoder.send_instructions(ONE_INSTRUCTION_1);
+
+        // exchange a flow control update.
+        let out = encoder.peer_conn.process(None, now());
+        mem::drop(encoder.conn.process(out.as_dgram_ref(), now()));
+
+        // Try writing a new header block. Now, headers will be added to the dynamic table again,
+        // because instructions can be sent.
+        let buf3 = encoder.encoder.encode_header_block(
+            &mut encoder.conn,
+            &[
+                Header::new("something5", "1234"),
+                Header::new("something6", "12345678910"),
+            ],
+            StreamId::new(3),
+        );
+        // Assert that the first header is encoded as an index to the dynamic table (a post form).
+        assert_eq!(buf3[2], 0x10);
+        // Assert that the second header is encoded as a literal with a name literal
+        assert_eq!(buf3[3] & 0xf0, 0x20);
+
+        // Asset that one instruction has been sent
+        encoder.send_instructions(ONE_INSTRUCTION_2);
+    }
+
+    #[test]
+    fn encoder_max_capacity_limit() {
+        let mut encoder = connect(false);
+
+        // change capacity to 2000.
+        assert!(encoder.encoder.set_max_capacity(2000).is_ok());
+        encoder.send_instructions(CAP_INSTRUCTION_1500);
+    }
+
+    #[test]
+    fn test_do_not_evict_entry_that_are_referred_only_by_the_same_header_blocked_encoding() {
+        let mut encoder = connect(false);
+
+        encoder.encoder.set_max_blocked_streams(20).unwrap();
+        assert!(encoder.change_capacity(50).is_ok());
+
+        encoder
+            .encoder
+            .send_and_insert(&mut encoder.conn, b"something5", b"1234")
+            .unwrap();
+
+        encoder
+            .encoder
+            .send_encoder_updates(&mut encoder.conn)
+            .unwrap();
+        let out = encoder.conn.process(None, now());
+        mem::drop(encoder.peer_conn.process(out.as_dgram_ref(), now()));
+        // receive an insert count increment.
+        recv_instruction(&mut encoder, &[0x01]);
+
+        // The first header will use the table entry and the second will use the literal
+        // encoding because the first entry is referred to and cannot be evicted.
+        assert_eq!(
+            encoder
+                .encoder
+                .encode_header_block(
+                    &mut encoder.conn,
+                    &[
+                        Header::new("something5", "1234"),
+                        Header::new("something6", "1234"),
+                    ],
+                    StreamId::new(3),
+                )
+                .to_vec(),
+            &[
+                0x02, 0x00, 0x80, 0x27, 0x03, 0x73, 0x6f, 0x6d, 0x65, 0x74, 0x68, 0x69, 0x6e, 0x67,
+                0x36, 0x04, 0x31, 0x32, 0x33, 0x34
+            ]
+        );
+        // Also check that ther is no new instruction send by the encoder.
+        assert!(encoder.conn.process_output(now()).dgram().is_none());
+    }
+
+    #[test]
+    fn test_streams_cancel_cleans_up_unacked_header_blocks() {
+        let mut encoder = connect(false);
+
+        encoder.encoder.set_max_blocked_streams(10).unwrap();
+        assert!(encoder.change_capacity(60).is_ok());
+        encoder.send_instructions(CAP_INSTRUCTION_60);
+
+        // insert "content-length: 1234
+        encoder.insert(
+            HEADER_CONTENT_LENGTH,
+            VALUE_1,
+            HEADER_CONTENT_LENGTH_VALUE_1_NAME_LITERAL,
+        );
+
+        // send a header block
+        encoder.encode_header_block(
+            StreamId::new(1),
+            &[Header::new("content-length", "1234")],
+            ENCODE_INDEXED_REF_DYNAMIC,
+            &[],
+        );
+
+        // receive a stream canceled instruction.
+        recv_instruction(&mut encoder, STREAM_CANCELED_ID_1);
+
+        recv_instruction(&mut encoder, &[0x01]);
+    }
+}
diff --git a/third_party/rust/neqo-qpack/src/encoder_instructions.rs b/third_party/rust/neqo-qpack/src/encoder_instructions.rs
new file mode 100644
index 0000000000..5564af969e
--- /dev/null
+++ b/third_party/rust/neqo-qpack/src/encoder_instructions.rs
@@ -0,0 +1,503 @@
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use std::mem;
+
+use neqo_common::{qdebug, qtrace};
+
+use crate::{
+    prefix::{
+        ENCODER_CAPACITY, ENCODER_DUPLICATE, ENCODER_INSERT_WITH_NAME_LITERAL,
+        ENCODER_INSERT_WITH_NAME_REF_DYNAMIC, ENCODER_INSERT_WITH_NAME_REF_STATIC, NO_PREFIX,
+    },
+    qpack_send_buf::QpackData,
+    reader::{IntReader, LiteralReader, ReadByte, Reader},
+    Res,
+};
+
+// The encoder only uses InsertWithNameLiteral, therefore clippy is complaining about dead_code.
+// We may decide to use othe instruction in the future.
+// All instructions are used for testing, therefore they are defined.
+#[allow(dead_code)]
+#[derive(Debug, PartialEq, Eq)]
+pub enum EncoderInstruction<'a> {
+    Capacity { value: u64 },
+    InsertWithNameRefStatic { index: u64, value: &'a [u8] },
+    InsertWithNameRefDynamic { index: u64, value: &'a [u8] },
+    InsertWithNameLiteral { name: &'a [u8], value: &'a [u8] },
+    Duplicate { index: u64 },
+    NoInstruction,
+}
+
+impl<'a> EncoderInstruction<'a> {
+    pub(crate) fn marshal(&self, enc: &mut QpackData, use_huffman: bool) {
+        match self {
+            Self::Capacity { value } => {
+                enc.encode_prefixed_encoded_int(ENCODER_CAPACITY, *value);
+            }
+            Self::InsertWithNameRefStatic { index, value } => {
+                enc.encode_prefixed_encoded_int(ENCODER_INSERT_WITH_NAME_REF_STATIC, *index);
+                enc.encode_literal(use_huffman, NO_PREFIX, value);
+            }
+            Self::InsertWithNameRefDynamic { index, value } => {
+                enc.encode_prefixed_encoded_int(ENCODER_INSERT_WITH_NAME_REF_DYNAMIC, *index);
+                enc.encode_literal(use_huffman, NO_PREFIX, value);
+            }
+            Self::InsertWithNameLiteral { name, value } => {
+                enc.encode_literal(use_huffman, ENCODER_INSERT_WITH_NAME_LITERAL, name);
+                enc.encode_literal(use_huffman, NO_PREFIX, value);
+            }
+            Self::Duplicate { index } => {
+                enc.encode_prefixed_encoded_int(ENCODER_DUPLICATE, *index);
+            }
+            Self::NoInstruction => {}
+        }
+    }
+}
+
+#[derive(Debug)]
+enum EncoderInstructionReaderState {
+    ReadInstruction,
+    ReadFirstInt { reader: IntReader },
+    ReadFirstLiteral { reader: LiteralReader },
+    ReadSecondLiteral { reader: LiteralReader },
+    Done,
+}
+
+#[derive(Debug, PartialEq, Eq)]
+pub enum DecodedEncoderInstruction {
+    Capacity { value: u64 },
+    InsertWithNameRefStatic { index: u64, value: Vec<u8> },
+    InsertWithNameRefDynamic { index: u64, value: Vec<u8> },
+    InsertWithNameLiteral { name: Vec<u8>, value: Vec<u8> },
+    Duplicate { index: u64 },
+    NoInstruction,
+}
+
+impl<'a> From<&'a EncoderInstruction<'a>> for DecodedEncoderInstruction {
+    fn from(inst: &'a EncoderInstruction) -> Self {
+        match inst {
+            EncoderInstruction::Capacity { value } => Self::Capacity { value: *value },
+            EncoderInstruction::InsertWithNameRefStatic { index, value } => {
+                Self::InsertWithNameRefStatic {
+                    index: *index,
+                    value: value.to_vec(),
+                }
+            }
+            EncoderInstruction::InsertWithNameRefDynamic { index, value } => {
+                Self::InsertWithNameRefDynamic {
+                    index: *index,
+                    value: value.to_vec(),
+                }
+            }
+            EncoderInstruction::InsertWithNameLiteral { name, value } => {
+                Self::InsertWithNameLiteral {
+                    name: name.to_vec(),
+                    value: value.to_vec(),
+                }
+            }
+            EncoderInstruction::Duplicate { index } => Self::Duplicate { index: *index },
+            EncoderInstruction::NoInstruction => Self::NoInstruction,
+        }
+    }
+}
+
+#[derive(Debug)]
+pub struct EncoderInstructionReader {
+    state: EncoderInstructionReaderState,
+    instruction: DecodedEncoderInstruction,
+}
+
+impl ::std::fmt::Display for EncoderInstructionReader {
+    fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
+        write!(
+            f,
+            "EncoderInstructionReader state={:?} instruction:{:?}",
+            self.state, self.instruction
+        )
+    }
+}
+
+impl EncoderInstructionReader {
+    pub fn new() -> Self {
+        Self {
+            state: EncoderInstructionReaderState::ReadInstruction,
+            instruction: DecodedEncoderInstruction::NoInstruction,
+        }
+    }
+
+    fn decode_instruction_from_byte(&mut self, b: u8) {
+        self.instruction = if ENCODER_INSERT_WITH_NAME_REF_STATIC.cmp_prefix(b) {
+            DecodedEncoderInstruction::InsertWithNameRefStatic {
+                index: 0,
+                value: Vec::new(),
+            }
+        } else if ENCODER_INSERT_WITH_NAME_REF_DYNAMIC.cmp_prefix(b) {
+            DecodedEncoderInstruction::InsertWithNameRefDynamic {
+                index: 0,
+                value: Vec::new(),
+            }
+        } else if ENCODER_INSERT_WITH_NAME_LITERAL.cmp_prefix(b) {
+            DecodedEncoderInstruction::InsertWithNameLiteral {
+                name: Vec::new(),
+                value: Vec::new(),
+            }
+        } else if ENCODER_CAPACITY.cmp_prefix(b) {
+            DecodedEncoderInstruction::Capacity { value: 0 }
+        } else if ENCODER_DUPLICATE.cmp_prefix(b) {
+            DecodedEncoderInstruction::Duplicate { index: 0 }
+        } else {
+            unreachable!("The above patterns match everything.");
+        };
+        qdebug!([self], "instruction decoded");
+    }
+
+    fn decode_instruction_type<T: ReadByte + Reader>(&mut self, recv: &mut T) -> Res<()> {
+        let b = recv.read_byte()?;
+
+        self.decode_instruction_from_byte(b);
+        match self.instruction {
+            DecodedEncoderInstruction::Capacity { .. }
+            | DecodedEncoderInstruction::Duplicate { .. } => {
+                self.state = EncoderInstructionReaderState::ReadFirstInt {
+                    reader: IntReader::new(b, ENCODER_CAPACITY.len()),
+                }
+            }
+            DecodedEncoderInstruction::InsertWithNameRefStatic { .. }
+            | DecodedEncoderInstruction::InsertWithNameRefDynamic { .. } => {
+                self.state = EncoderInstructionReaderState::ReadFirstInt {
+                    reader: IntReader::new(b, ENCODER_INSERT_WITH_NAME_REF_STATIC.len()),
+                }
+            }
+            DecodedEncoderInstruction::InsertWithNameLiteral { .. } => {
+                self.state = EncoderInstructionReaderState::ReadFirstLiteral {
+                    reader: LiteralReader::new_with_first_byte(
+                        b,
+                        ENCODER_INSERT_WITH_NAME_LITERAL.len(),
+                    ),
+                }
+            }
+            DecodedEncoderInstruction::NoInstruction => {
+                unreachable!("We must have instruction at this point.");
+            }
+        }
+        Ok(())
+    }
+
+    /// # Errors
+    ///
+    /// 1) `NeedMoreData` if the reader needs more data
+    /// 2) `ClosedCriticalStream`
+    /// 3) other errors will be translated to `EncoderStream` by the caller of this function.
+    pub fn read_instructions<T: ReadByte + Reader>(
+        &mut self,
+        recv: &mut T,
+    ) -> Res<DecodedEncoderInstruction> {
+        qdebug!([self], "reading instructions");
+        loop {
+            match &mut self.state {
+                EncoderInstructionReaderState::ReadInstruction => {
+                    self.decode_instruction_type(recv)?;
+                }
+                EncoderInstructionReaderState::ReadFirstInt { reader } => {
+                    let val = reader.read(recv)?;
+
+                    qtrace!([self], "First varint read {}", val);
+                    match &mut self.instruction {
+                        DecodedEncoderInstruction::Capacity { value: v, .. }
+                        | DecodedEncoderInstruction::Duplicate { index: v } => {
+                            *v = val;
+                            self.state = EncoderInstructionReaderState::Done;
+                        }
+                        DecodedEncoderInstruction::InsertWithNameRefStatic { index, .. }
+                        | DecodedEncoderInstruction::InsertWithNameRefDynamic { index, .. } => {
+                            *index = val;
+                            self.state = EncoderInstructionReaderState::ReadFirstLiteral {
+                                reader: LiteralReader::default(),
+                            };
+                        }
+                        _ => unreachable!("This instruction cannot be in this state."),
+                    }
+                }
+                EncoderInstructionReaderState::ReadFirstLiteral { reader } => {
+                    let val = reader.read(recv)?;
+
+                    qtrace!([self], "first literal read {:?}", val);
+                    match &mut self.instruction {
+                        DecodedEncoderInstruction::InsertWithNameRefStatic { value, .. }
+                        | DecodedEncoderInstruction::InsertWithNameRefDynamic { value, .. } => {
+                            *value = val;
+                            self.state = EncoderInstructionReaderState::Done;
+                        }
+                        DecodedEncoderInstruction::InsertWithNameLiteral { name, .. } => {
+                            *name = val;
+                            self.state = EncoderInstructionReaderState::ReadSecondLiteral {
+                                reader: LiteralReader::default(),
+                            };
+                        }
+                        _ => unreachable!("This instruction cannot be in this state."),
+                    }
+                }
+                EncoderInstructionReaderState::ReadSecondLiteral { reader } => {
+                    let val = reader.read(recv)?;
+
+                    qtrace!([self], "second literal read {:?}", val);
+                    match &mut self.instruction {
+                        DecodedEncoderInstruction::InsertWithNameLiteral { value, .. } => {
+                            *value = val;
+                            self.state = EncoderInstructionReaderState::Done;
+                        }
+                        _ => unreachable!("This instruction cannot be in this state."),
+                    }
+                }
+                EncoderInstructionReaderState::Done => {}
+            }
+            if matches!(self.state, EncoderInstructionReaderState::Done) {
+                self.state = EncoderInstructionReaderState::ReadInstruction;
+                break Ok(mem::replace(
+                    &mut self.instruction,
+                    DecodedEncoderInstruction::NoInstruction,
+                ));
+            }
+        }
+    }
+}
+
+#[cfg(test)]
+mod test {
+
+    use super::{EncoderInstruction, EncoderInstructionReader, QpackData};
+    use crate::{reader::test_receiver::TestReceiver, Error};
+
+    fn test_encoding_decoding(instruction: &EncoderInstruction, use_huffman: bool) {
+        let mut buf = QpackData::default();
+        instruction.marshal(&mut buf, use_huffman);
+        let mut test_receiver: TestReceiver = TestReceiver::default();
+        test_receiver.write(&buf);
+        let mut reader = EncoderInstructionReader::new();
+        assert_eq!(
+            reader.read_instructions(&mut test_receiver).unwrap(),
+            instruction.into()
+        );
+    }
+
+    #[test]
+    fn test_encoding_decoding_instructions() {
+        test_encoding_decoding(&EncoderInstruction::Capacity { value: 1 }, false);
+        test_encoding_decoding(&EncoderInstruction::Capacity { value: 10_000 }, false);
+
+        test_encoding_decoding(
+            &EncoderInstruction::InsertWithNameRefStatic {
+                index: 1,
+                value: &[0x62, 0x64, 0x65],
+            },
+            false,
+        );
+        test_encoding_decoding(
+            &EncoderInstruction::InsertWithNameRefStatic {
+                index: 1,
+                value: &[0x62, 0x64, 0x65],
+            },
+            true,
+        );
+        test_encoding_decoding(
+            &EncoderInstruction::InsertWithNameRefStatic {
+                index: 10_000,
+                value: &[0x62, 0x64, 0x65],
+            },
+            false,
+        );
+        test_encoding_decoding(
+            &EncoderInstruction::InsertWithNameRefStatic {
+                index: 10_000,
+                value: &[0x62, 0x64, 0x65],
+            },
+            true,
+        );
+
+        test_encoding_decoding(
+            &EncoderInstruction::InsertWithNameRefDynamic {
+                index: 1,
+                value: &[0x62, 0x64, 0x65],
+            },
+            false,
+        );
+        test_encoding_decoding(
+            &EncoderInstruction::InsertWithNameRefDynamic {
+                index: 1,
+                value: &[0x62, 0x64, 0x65],
+            },
+            true,
+        );
+        test_encoding_decoding(
+            &EncoderInstruction::InsertWithNameRefDynamic {
+                index: 10_000,
+                value: &[0x62, 0x64, 0x65],
+            },
+            false,
+        );
+        test_encoding_decoding(
+            &EncoderInstruction::InsertWithNameRefDynamic {
+                index: 10_000,
+                value: &[0x62, 0x64, 0x65],
+            },
+            true,
+        );
+
+        test_encoding_decoding(
+            &EncoderInstruction::InsertWithNameLiteral {
+                name: &[0x62, 0x64, 0x65],
+                value: &[0x62, 0x64, 0x65],
+            },
+            false,
+        );
+        test_encoding_decoding(
+            &EncoderInstruction::InsertWithNameLiteral {
+                name: &[0x62, 0x64, 0x65],
+                value: &[0x62, 0x64, 0x65],
+            },
+            true,
+        );
+
+        test_encoding_decoding(&EncoderInstruction::Duplicate { index: 1 }, false);
+        test_encoding_decoding(&EncoderInstruction::Duplicate { index: 10_000 }, false);
+    }
+
+    fn test_encoding_decoding_slow_reader(instruction: &EncoderInstruction, use_huffman: bool) {
+        let mut buf = QpackData::default();
+        instruction.marshal(&mut buf, use_huffman);
+        let mut test_receiver: TestReceiver = TestReceiver::default();
+        let mut decoder = EncoderInstructionReader::new();
+        for i in 0..buf.len() - 1 {
+            test_receiver.write(&buf[i..=i]);
+            assert_eq!(
+                decoder.read_instructions(&mut test_receiver),
+                Err(Error::NeedMoreData)
+            );
+        }
+        test_receiver.write(&buf[buf.len() - 1..buf.len()]);
+        assert_eq!(
+            decoder.read_instructions(&mut test_receiver).unwrap(),
+            instruction.into()
+        );
+    }
+
+    #[test]
+    fn test_encoding_decoding_instructions_slow_reader() {
+        test_encoding_decoding_slow_reader(&EncoderInstruction::Capacity { value: 1 }, false);
+        test_encoding_decoding_slow_reader(&EncoderInstruction::Capacity { value: 10_000 }, false);
+
+        test_encoding_decoding_slow_reader(
+            &EncoderInstruction::InsertWithNameRefStatic {
+                index: 1,
+                value: &[0x62, 0x64, 0x65],
+            },
+            false,
+        );
+        test_encoding_decoding_slow_reader(
+            &EncoderInstruction::InsertWithNameRefStatic {
+                index: 1,
+                value: &[0x62, 0x64, 0x65],
+            },
+            true,
+        );
+        test_encoding_decoding_slow_reader(
+            &EncoderInstruction::InsertWithNameRefStatic {
+                index: 10_000,
+                value: &[0x62, 0x64, 0x65],
+            },
+            false,
+        );
+        test_encoding_decoding_slow_reader(
+            &EncoderInstruction::InsertWithNameRefStatic {
+                index: 10_000,
+                value: &[0x62, 0x64, 0x65],
+            },
+            true,
+        );
+
+        test_encoding_decoding_slow_reader(
+            &EncoderInstruction::InsertWithNameRefDynamic {
+                index: 1,
+                value: &[0x62, 0x64, 0x65],
+            },
+            false,
+        );
+        test_encoding_decoding_slow_reader(
+            &EncoderInstruction::InsertWithNameRefDynamic {
+                index: 1,
+                value: &[0x62, 0x64, 0x65],
+            },
+            true,
+        );
+        test_encoding_decoding_slow_reader(
+            &EncoderInstruction::InsertWithNameRefDynamic {
+                index: 10_000,
+                value: &[0x62, 0x64, 0x65],
+            },
+            false,
+        );
+        test_encoding_decoding_slow_reader(
+            &EncoderInstruction::InsertWithNameRefDynamic {
+                index: 10_000,
+                value: &[0x62, 0x64, 0x65],
+            },
+            true,
+        );
+
+        test_encoding_decoding_slow_reader(
+            &EncoderInstruction::InsertWithNameLiteral {
+                name: &[0x62, 0x64, 0x65],
+                value: &[0x62, 0x64, 0x65],
+            },
+            false,
+        );
+        test_encoding_decoding_slow_reader(
+            &EncoderInstruction::InsertWithNameLiteral {
+                name: &[0x62, 0x64, 0x65],
+                value: &[0x62, 0x64, 0x65],
+            },
+            true,
+        );
+
+        test_encoding_decoding_slow_reader(&EncoderInstruction::Duplicate { index: 1 }, false);
+        test_encoding_decoding_slow_reader(&EncoderInstruction::Duplicate { index: 10_000 }, false);
+    }
+
+    #[test]
+    fn test_decoding_error() {
+        let mut test_receiver: TestReceiver = TestReceiver::default();
+        // EncoderInstruction::Capacity with overflow
+        test_receiver.write(&[
+            0x3f, 0xc1, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xff, 0x02,
+        ]);
+        let mut decoder = EncoderInstructionReader::new();
+        assert_eq!(
+            decoder.read_instructions(&mut test_receiver),
+            Err(Error::IntegerOverflow)
+        );
+
+        let mut test_receiver: TestReceiver = TestReceiver::default();
+        // EncoderInstruction::InsertWithNameRefStatic with overflow of index value.
+        test_receiver.write(&[
+            0xff, 0xc1, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xff, 0x02, 0x00, 0x00,
+        ]);
+        let mut decoder = EncoderInstructionReader::new();
+        assert_eq!(
+            decoder.read_instructions(&mut test_receiver),
+            Err(Error::IntegerOverflow)
+        );
+
+        let mut test_receiver: TestReceiver = TestReceiver::default();
+        // EncoderInstruction::InsertWithNameRefStatic with a garbage value.
+        test_receiver.write(&[0xc1, 0x81, 0x00]);
+        let mut decoder = EncoderInstructionReader::new();
+        assert_eq!(
+            decoder.read_instructions(&mut test_receiver),
+            Err(Error::HuffmanDecompressionFailed)
+        );
+    }
+}
diff --git a/third_party/rust/neqo-qpack/src/header_block.rs b/third_party/rust/neqo-qpack/src/header_block.rs
new file mode 100644
index 0000000000..2e15bdf1fe
--- /dev/null
+++ b/third_party/rust/neqo-qpack/src/header_block.rs
@@ -0,0 +1,940 @@
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use std::{
+    mem,
+    ops::{Deref, Div},
+};
+
+use neqo_common::{qtrace, Header};
+
+use crate::{
+    prefix::{
+        BASE_PREFIX_NEGATIVE, BASE_PREFIX_POSITIVE, HEADER_FIELD_INDEX_DYNAMIC,
+        HEADER_FIELD_INDEX_DYNAMIC_POST, HEADER_FIELD_INDEX_STATIC,
+        HEADER_FIELD_LITERAL_NAME_LITERAL, HEADER_FIELD_LITERAL_NAME_REF_DYNAMIC,
+        HEADER_FIELD_LITERAL_NAME_REF_DYNAMIC_POST, HEADER_FIELD_LITERAL_NAME_REF_STATIC,
+        NO_PREFIX,
+    },
+    qpack_send_buf::QpackData,
+    reader::{parse_utf8, ReceiverBufferWrapper},
+    table::HeaderTable,
+    Error, Res,
+};
+
+#[derive(Default, Debug, PartialEq)]
+pub struct HeaderEncoder {
+    buf: QpackData,
+    base: u64,
+    use_huffman: bool,
+    max_entries: u64,
+    max_dynamic_index_ref: Option<u64>,
+}
+
+impl ::std::fmt::Display for HeaderEncoder {
+    fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
+        write!(f, "HeaderEncoder")
+    }
+}
+
+impl HeaderEncoder {
+    pub fn new(base: u64, use_huffman: bool, max_entries: u64) -> Self {
+        Self {
+            buf: QpackData::default(),
+            base,
+            use_huffman,
+            max_entries,
+            max_dynamic_index_ref: None,
+        }
+    }
+
+    pub fn len(&self) -> usize {
+        self.buf.len()
+    }
+
+    pub fn read(&mut self, r: usize) {
+        self.buf.read(r);
+    }
+
+    pub fn encode_indexed_static(&mut self, index: u64) {
+        qtrace!([self], "encode static index {}.", index);
+        self.buf
+            .encode_prefixed_encoded_int(HEADER_FIELD_INDEX_STATIC, index);
+    }
+
+    fn new_ref(&mut self, index: u64) {
+        if let Some(r) = self.max_dynamic_index_ref {
+            if r < index {
+                self.max_dynamic_index_ref = Some(index);
+            }
+        } else {
+            self.max_dynamic_index_ref = Some(index);
+        }
+    }
+
+    pub fn encode_indexed_dynamic(&mut self, index: u64) {
+        qtrace!([self], "encode dynamic index {}.", index);
+        if index < self.base {
+            self.buf
+                .encode_prefixed_encoded_int(HEADER_FIELD_INDEX_DYNAMIC, self.base - index - 1);
+        } else {
+            self.buf
+                .encode_prefixed_encoded_int(HEADER_FIELD_INDEX_DYNAMIC_POST, index - self.base);
+        }
+        self.new_ref(index);
+    }
+
+    pub fn encode_literal_with_name_ref(&mut self, is_static: bool, index: u64, value: &[u8]) {
+        qtrace!(
+            [self],
+            "encode literal with name ref - index={}, static={}, value={:x?}",
+            index,
+            is_static,
+            value
+        );
+        if is_static {
+            self.buf
+                .encode_prefixed_encoded_int(HEADER_FIELD_LITERAL_NAME_REF_STATIC, index);
+        } else if index < self.base {
+            self.buf.encode_prefixed_encoded_int(
+                HEADER_FIELD_LITERAL_NAME_REF_DYNAMIC,
+                self.base - index - 1,
+            );
+            self.new_ref(index);
+        } else {
+            self.buf.encode_prefixed_encoded_int(
+                HEADER_FIELD_LITERAL_NAME_REF_DYNAMIC_POST,
+                index - self.base,
+            );
+            self.new_ref(index);
+        }
+
+        self.buf.encode_literal(self.use_huffman, NO_PREFIX, value);
+    }
+
+    pub fn encode_literal_with_name_literal(&mut self, name: &[u8], value: &[u8]) {
+        qtrace!(
+            [self],
+            "encode literal with name literal - name={:x?}, value={:x?}.",
+            name,
+            value
+        );
+        self.buf
+            .encode_literal(self.use_huffman, HEADER_FIELD_LITERAL_NAME_LITERAL, name);
+        self.buf.encode_literal(self.use_huffman, NO_PREFIX, value);
+    }
+
+    pub fn encode_header_block_prefix(&mut self) {
+        let tmp = mem::take(&mut self.buf);
+        let (enc_insert_cnt, delta, prefix) =
+            self.max_dynamic_index_ref
+                .map_or((0, self.base, BASE_PREFIX_POSITIVE), |r| {
+                    let req_insert_cnt = r + 1;
+                    if req_insert_cnt <= self.base {
+                        (
+                            req_insert_cnt % (2 * self.max_entries) + 1,
+                            self.base - req_insert_cnt,
+                            BASE_PREFIX_POSITIVE,
+                        )
+                    } else {
+                        (
+                            req_insert_cnt % (2 * self.max_entries) + 1,
+                            req_insert_cnt - self.base - 1,
+                            BASE_PREFIX_NEGATIVE,
+                        )
+                    }
+                });
+        qtrace!(
+            [self],
+            "encode header block prefix max_dynamic_index_ref={:?}, base={}, enc_insert_cnt={}, delta={}, prefix={:?}.",
+            self.max_dynamic_index_ref,
+            self.base,
+            enc_insert_cnt,
+            delta,
+            prefix
+        );
+
+        self.buf
+            .encode_prefixed_encoded_int(NO_PREFIX, enc_insert_cnt);
+        self.buf.encode_prefixed_encoded_int(prefix, delta);
+
+        self.buf.write_bytes(&tmp);
+    }
+}
+
+impl Deref for HeaderEncoder {
+    type Target = [u8];
+    fn deref(&self) -> &Self::Target {
+        &self.buf
+    }
+}
+
+pub(crate) struct HeaderDecoder<'a> {
+    buf: ReceiverBufferWrapper<'a>,
+    base: u64,
+    req_insert_cnt: u64,
+}
+
+impl<'a> ::std::fmt::Display for HeaderDecoder<'a> {
+    fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
+        write!(f, "HeaderDecoder")
+    }
+}
+
+#[derive(Debug, PartialEq, Eq)]
+pub enum HeaderDecoderResult {
+    Blocked(u64),
+    Headers(Vec<Header>),
+}
+
+impl<'a> HeaderDecoder<'a> {
+    pub fn new(buf: &'a [u8]) -> Self {
+        Self {
+            buf: ReceiverBufferWrapper::new(buf),
+            base: 0,
+            req_insert_cnt: 0,
+        }
+    }
+
+    pub fn refers_dynamic_table(
+        &mut self,
+        max_entries: u64,
+        total_num_of_inserts: u64,
+    ) -> Res<bool> {
+        Error::map_error(
+            self.read_base(max_entries, total_num_of_inserts),
+            Error::DecompressionFailed,
+        )?;
+        Ok(self.req_insert_cnt != 0)
+    }
+
+    pub fn decode_header_block(
+        &mut self,
+        table: &HeaderTable,
+        max_entries: u64,
+        total_num_of_inserts: u64,
+    ) -> Res<HeaderDecoderResult> {
+        Error::map_error(
+            self.read_base(max_entries, total_num_of_inserts),
+            Error::DecompressionFailed,
+        )?;
+
+        if table.base() < self.req_insert_cnt {
+            qtrace!(
+                [self],
+                "decoding is blocked, requested inserts count={}",
+                self.req_insert_cnt
+            );
+            return Ok(HeaderDecoderResult::Blocked(self.req_insert_cnt));
+        }
+        let mut h: Vec<Header> = Vec::new();
+
+        while !self.buf.done() {
+            let b = Error::map_error(self.buf.peek(), Error::DecompressionFailed)?;
+            if HEADER_FIELD_INDEX_STATIC.cmp_prefix(b) {
+                h.push(Error::map_error(
+                    self.read_indexed_static(),
+                    Error::DecompressionFailed,
+                )?);
+            } else if HEADER_FIELD_INDEX_DYNAMIC.cmp_prefix(b) {
+                h.push(Error::map_error(
+                    self.read_indexed_dynamic(table),
+                    Error::DecompressionFailed,
+                )?);
+            } else if HEADER_FIELD_INDEX_DYNAMIC_POST.cmp_prefix(b) {
+                h.push(Error::map_error(
+                    self.read_indexed_dynamic_post(table),
+                    Error::DecompressionFailed,
+                )?);
+            } else if HEADER_FIELD_LITERAL_NAME_REF_STATIC.cmp_prefix(b) {
+                h.push(Error::map_error(
+                    self.read_literal_with_name_ref_static(),
+                    Error::DecompressionFailed,
+                )?);
+            } else if HEADER_FIELD_LITERAL_NAME_REF_DYNAMIC.cmp_prefix(b) {
+                h.push(Error::map_error(
+                    self.read_literal_with_name_ref_dynamic(table),
+                    Error::DecompressionFailed,
+                )?);
+            } else if HEADER_FIELD_LITERAL_NAME_LITERAL.cmp_prefix(b) {
+                h.push(Error::map_error(
+                    self.read_literal_with_name_literal(),
+                    Error::DecompressionFailed,
+                )?);
+            } else if HEADER_FIELD_LITERAL_NAME_REF_DYNAMIC_POST.cmp_prefix(b) {
+                h.push(Error::map_error(
+                    self.read_literal_with_name_ref_dynamic_post(table),
+                    Error::DecompressionFailed,
+                )?);
+            } else {
+                unreachable!("All prefixes are covered");
+            }
+        }
+
+        qtrace!([self], "done decoding header block.");
+        Ok(HeaderDecoderResult::Headers(h))
+    }
+
+    pub fn get_req_insert_cnt(&self) -> u64 {
+        self.req_insert_cnt
+    }
+
+    fn read_base(&mut self, max_entries: u64, total_num_of_inserts: u64) -> Res<()> {
+        let insert_cnt = self.buf.read_prefixed_int(0)?;
+        self.req_insert_cnt =
+            HeaderDecoder::calc_req_insert_cnt(insert_cnt, max_entries, total_num_of_inserts)?;
+
+        let s = self.buf.peek()? & 0x80 != 0;
+        let base_delta = self.buf.read_prefixed_int(1)?;
+        self.base = if s {
+            if self.req_insert_cnt <= base_delta {
+                return Err(Error::DecompressionFailed);
+            }
+            self.req_insert_cnt - base_delta - 1
+        } else {
+            self.req_insert_cnt
+                .checked_add(base_delta)
+                .ok_or(Error::DecompressionFailed)?
+        };
+        qtrace!(
+            [self],
+            "requested inserts count is {} and base is {}",
+            self.req_insert_cnt,
+            self.base
+        );
+        Ok(())
+    }
+
+    fn calc_req_insert_cnt(encoded: u64, max_entries: u64, total_num_of_inserts: u64) -> Res<u64> {
+        if encoded == 0 {
+            Ok(0)
+        } else if max_entries == 0 {
+            Err(Error::DecompressionFailed)
+        } else {
+            let full_range = 2 * max_entries;
+            if encoded > full_range {
+                return Err(Error::DecompressionFailed);
+            }
+            let max_value = total_num_of_inserts + max_entries;
+            let max_wrapped = max_value.div(full_range) * full_range;
+            let mut req_insert_cnt = max_wrapped + encoded - 1;
+            if req_insert_cnt > max_value {
+                if req_insert_cnt < full_range {
+                    return Err(Error::DecompressionFailed);
+                }
+                req_insert_cnt -= full_range;
+            }
+            Ok(req_insert_cnt)
+        }
+    }
+
+    fn read_indexed_static(&mut self) -> Res<Header> {
+        let index = self
+            .buf
+            .read_prefixed_int(HEADER_FIELD_INDEX_STATIC.len())?;
+        qtrace!([self], "decoder static indexed {}.", index);
+        let entry = HeaderTable::get_static(index)?;
+        Ok(Header::new(
+            parse_utf8(entry.name())?,
+            parse_utf8(entry.value())?,
+        ))
+    }
+
+    fn read_indexed_dynamic(&mut self, table: &HeaderTable) -> Res<Header> {
+        let index = self
+            .buf
+            .read_prefixed_int(HEADER_FIELD_INDEX_DYNAMIC.len())?;
+        qtrace!([self], "decoder dynamic indexed {}.", index);
+        let entry = table.get_dynamic(index, self.base, false)?;
+        Ok(Header::new(
+            parse_utf8(entry.name())?,
+            parse_utf8(entry.value())?,
+        ))
+    }
+
+    fn read_indexed_dynamic_post(&mut self, table: &HeaderTable) -> Res<Header> {
+        let index = self
+            .buf
+            .read_prefixed_int(HEADER_FIELD_INDEX_DYNAMIC_POST.len())?;
+        qtrace!([self], "decode post-based {}.", index);
+        let entry = table.get_dynamic(index, self.base, true)?;
+        Ok(Header::new(
+            parse_utf8(entry.name())?,
+            parse_utf8(entry.value())?,
+        ))
+    }
+
+    fn read_literal_with_name_ref_static(&mut self) -> Res<Header> {
+        qtrace!(
+            [self],
+            "read literal with name reference to the static table."
+        );
+
+        let index = self
+            .buf
+            .read_prefixed_int(HEADER_FIELD_LITERAL_NAME_REF_STATIC.len())?;
+
+        Ok(Header::new(
+            parse_utf8(HeaderTable::get_static(index)?.name())?,
+            self.buf.read_literal_from_buffer(0)?,
+        ))
+    }
+
+    fn read_literal_with_name_ref_dynamic(&mut self, table: &HeaderTable) -> Res<Header> {
+        qtrace!(
+            [self],
+            "read literal with name reference ot the dynamic table."
+        );
+
+        let index = self
+            .buf
+            .read_prefixed_int(HEADER_FIELD_LITERAL_NAME_REF_DYNAMIC.len())?;
+
+        Ok(Header::new(
+            parse_utf8(table.get_dynamic(index, self.base, false)?.name())?,
+            self.buf.read_literal_from_buffer(0)?,
+        ))
+    }
+
+    fn read_literal_with_name_ref_dynamic_post(&mut self, table: &HeaderTable) -> Res<Header> {
+        qtrace!([self], "decoder literal with post-based index.");
+
+        let index = self
+            .buf
+            .read_prefixed_int(HEADER_FIELD_LITERAL_NAME_REF_DYNAMIC_POST.len())?;
+
+        Ok(Header::new(
+            parse_utf8(table.get_dynamic(index, self.base, true)?.name())?,
+            self.buf.read_literal_from_buffer(0)?,
+        ))
+    }
+
+    fn read_literal_with_name_literal(&mut self) -> Res<Header> {
+        qtrace!([self], "decode literal with name literal.");
+
+        let name = self
+            .buf
+            .read_literal_from_buffer(HEADER_FIELD_LITERAL_NAME_LITERAL.len())?;
+
+        Ok(Header::new(name, self.buf.read_literal_from_buffer(0)?))
+    }
+}
+
+#[cfg(test)]
+mod tests {
+
+    use super::{HeaderDecoder, HeaderDecoderResult, HeaderEncoder, HeaderTable};
+    use crate::Error;
+
+    const INDEX_STATIC_TEST: &[(u64, &[u8], &str, &str)] = &[
+        (0, &[0x0, 0x0, 0xc0], ":authority", ""),
+        (10, &[0x0, 0x0, 0xca], "last-modified", ""),
+        (15, &[0x0, 0x0, 0xcf], ":method", "CONNECT"),
+        (65, &[0x0, 0x0, 0xff, 0x02], ":status", "206"),
+    ];
+
+    const INDEX_DYNAMIC_TEST: &[(u64, &[u8], &str, &str)] = &[
+        (0, &[0x02, 0x41, 0xbf, 0x2], "header0", "0"),
+        (10, &[0x0c, 0x37, 0xb7], "header10", "10"),
+        (15, &[0x11, 0x32, 0xb2], "header15", "15"),
+        (65, &[0x43, 0x0, 0x80], "header65", "65"),
+    ];
+
+    const INDEX_DYNAMIC_POST_TEST: &[(u64, &[u8], &str, &str)] = &[
+        (0, &[0x02, 0x80, 0x10], "header0", "0"),
+        (10, &[0x0c, 0x8a, 0x1a], "header10", "10"),
+        (15, &[0x11, 0x8f, 0x1f, 0x00], "header15", "15"),
+        (65, &[0x43, 0xc1, 0x1f, 0x32], "header65", "65"),
+    ];
+
+    const NAME_REF_STATIC: &[(u64, &[u8], &str, &str)] = &[
+        (
+            0,
+            &[
+                0x00, 0x00, 0x50, 0x0a, 0x63, 0x75, 0x73, 0x74, 0x6f, 0x6d, 0x2d, 0x6b, 0x65, 0x79,
+            ],
+            ":authority",
+            "custom-key",
+        ),
+        (
+            10,
+            &[
+                0x00, 0x00, 0x5a, 0x0a, 0x63, 0x75, 0x73, 0x74, 0x6f, 0x6d, 0x2d, 0x6b, 0x65, 0x79,
+            ],
+            "last-modified",
+            "custom-key",
+        ),
+        (
+            15,
+            &[
+                0x00, 0x00, 0x5f, 0x00, 0x0a, 0x63, 0x75, 0x73, 0x74, 0x6f, 0x6d, 0x2d, 0x6b, 0x65,
+                0x79,
+            ],
+            ":method",
+            "custom-key",
+        ),
+        (
+            65,
+            &[
+                0x00, 0x00, 0x5f, 0x32, 0x0a, 0x63, 0x75, 0x73, 0x74, 0x6f, 0x6d, 0x2d, 0x6b, 0x65,
+                0x79,
+            ],
+            ":status",
+            "custom-key",
+        ),
+    ];
+
+    const NAME_REF_DYNAMIC: &[(u64, &[u8], &str, &str)] = &[
+        (
+            0,
+            &[
+                0x02, 0x41, 0x4f, 0x32, 0x0a, 0x63, 0x75, 0x73, 0x74, 0x6f, 0x6d, 0x2d, 0x6b, 0x65,
+                0x79,
+            ],
+            "header0",
+            "custom-key",
+        ),
+        (
+            10,
+            &[
+                0x0c, 0x37, 0x4f, 0x28, 0x0a, 0x63, 0x75, 0x73, 0x74, 0x6f, 0x6d, 0x2d, 0x6b, 0x65,
+                0x79,
+            ],
+            "header10",
+            "custom-key",
+        ),
+        (
+            15,
+            &[
+                0x11, 0x32, 0x4f, 0x23, 0x0a, 0x63, 0x75, 0x73, 0x74, 0x6f, 0x6d, 0x2d, 0x6b, 0x65,
+                0x79,
+            ],
+            "header15",
+            "custom-key",
+        ),
+        (
+            65,
+            &[
+                0x43, 0x00, 0x40, 0x0a, 0x63, 0x75, 0x73, 0x74, 0x6f, 0x6d, 0x2d, 0x6b, 0x65, 0x79,
+            ],
+            "header65",
+            "custom-key",
+        ),
+    ];
+
+    const NAME_REF_DYNAMIC_POST: &[(u64, &[u8], &str, &str)] = &[
+        (
+            0,
+            &[
+                0x02, 0x80, 0x00, 0x0a, 0x63, 0x75, 0x73, 0x74, 0x6f, 0x6d, 0x2d, 0x6b, 0x65, 0x79,
+            ],
+            "header0",
+            "custom-key",
+        ),
+        (
+            10,
+            &[
+                0x0c, 0x8a, 0x07, 0x03, 0x0a, 0x63, 0x75, 0x73, 0x74, 0x6f, 0x6d, 0x2d, 0x6b, 0x65,
+                0x79,
+            ],
+            "header10",
+            "custom-key",
+        ),
+        (
+            15,
+            &[
+                0x11, 0x8f, 0x07, 0x08, 0x0a, 0x63, 0x75, 0x73, 0x74, 0x6f, 0x6d, 0x2d, 0x6b, 0x65,
+                0x79,
+            ],
+            "header15",
+            "custom-key",
+        ),
+        (
+            65,
+            &[
+                0x43, 0xc1, 0x07, 0x3a, 0x0a, 0x63, 0x75, 0x73, 0x74, 0x6f, 0x6d, 0x2d, 0x6b, 0x65,
+                0x79,
+            ],
+            "header65",
+            "custom-key",
+        ),
+    ];
+
+    const NAME_REF_DYNAMIC_HUFFMAN: &[(u64, &[u8], &str, &str)] = &[
+        (
+            0,
+            &[
+                0x02, 0x41, 0x4f, 0x32, 0x88, 0x25, 0xa8, 0x49, 0xe9, 0x5b, 0xa9, 0x7d, 0x7f,
+            ],
+            "header0",
+            "custom-key",
+        ),
+        (
+            10,
+            &[
+                0x0c, 0x37, 0x4f, 0x28, 0x88, 0x25, 0xa8, 0x49, 0xe9, 0x5b, 0xa9, 0x7d, 0x7f,
+            ],
+            "header10",
+            "custom-key",
+        ),
+        (
+            15,
+            &[
+                0x11, 0x32, 0x4f, 0x23, 0x88, 0x25, 0xa8, 0x49, 0xe9, 0x5b, 0xa9, 0x7d, 0x7f,
+            ],
+            "header15",
+            "custom-key",
+        ),
+        (
+            65,
+            &[
+                0x43, 0x00, 0x40, 0x88, 0x25, 0xa8, 0x49, 0xe9, 0x5b, 0xa9, 0x7d, 0x7f,
+            ],
+            "header65",
+            "custom-key",
+        ),
+    ];
+
+    const VALUE: &[u8] = &[0x63, 0x75, 0x73, 0x74, 0x6f, 0x6d, 0x2d, 0x6b, 0x65, 0x79];
+
+    const LITERAL_LITERAL: &[u8] = &[
+        0x0, 0x42, 0x27, 0x03, 0x63, 0x75, 0x73, 0x74, 0x6f, 0x6d, 0x2d, 0x6b, 0x65, 0x79, 0x0a,
+        0x63, 0x75, 0x73, 0x74, 0x6f, 0x6d, 0x2d, 0x6b, 0x65, 0x79,
+    ];
+    const LITERAL_LITERAL_HUFFMAN: &[u8] = &[
+        0x0, 0x42, 0x2f, 0x01, 0x25, 0xa8, 0x49, 0xe9, 0x5b, 0xa9, 0x7d, 0x7f, 0x88, 0x25, 0xa8,
+        0x49, 0xe9, 0x5b, 0xa9, 0x7d, 0x7f,
+    ];
+
+    const LITERAL_VALUE: &str = "custom-key";
+
+    #[test]
+    fn test_encode_indexed_static() {
+        for (index, result, _, _) in INDEX_STATIC_TEST {
+            let mut encoded_h = HeaderEncoder::new(0, true, 1000);
+            encoded_h.encode_indexed_static(*index);
+            encoded_h.encode_header_block_prefix();
+            assert_eq!(&&*encoded_h, result);
+        }
+    }
+
+    #[test]
+    fn test_encode_indexed_dynamic() {
+        for (index, result, _, _) in INDEX_DYNAMIC_TEST {
+            let mut encoded_h = HeaderEncoder::new(66, true, 1000);
+            encoded_h.encode_indexed_dynamic(*index);
+            encoded_h.encode_header_block_prefix();
+            assert_eq!(&&*encoded_h, result);
+        }
+    }
+
+    #[test]
+    fn test_encode_indexed_dynamic_post() {
+        for (index, result, _, _) in INDEX_DYNAMIC_POST_TEST {
+            let mut encoded_h = HeaderEncoder::new(0, true, 1000);
+            encoded_h.encode_indexed_dynamic(*index);
+            encoded_h.encode_header_block_prefix();
+            assert_eq!(&&*encoded_h, result);
+        }
+    }
+
+    #[test]
+    fn test_encode_literal_with_name_ref_static() {
+        for (index, result, _, _) in NAME_REF_STATIC {
+            let mut encoded_h = HeaderEncoder::new(0, false, 1000);
+            encoded_h.encode_literal_with_name_ref(true, *index, VALUE);
+            encoded_h.encode_header_block_prefix();
+            assert_eq!(&&*encoded_h, result);
+        }
+    }
+
+    #[test]
+    fn test_encode_literal_with_name_ref_dynamic() {
+        for (index, result, _, _) in NAME_REF_DYNAMIC {
+            let mut encoded_h = HeaderEncoder::new(66, false, 1000);
+            encoded_h.encode_literal_with_name_ref(false, *index, VALUE);
+            encoded_h.encode_header_block_prefix();
+            assert_eq!(&&*encoded_h, result);
+        }
+    }
+
+    #[test]
+    fn test_encode_literal_with_name_ref_dynamic_post() {
+        for (index, result, _, _) in NAME_REF_DYNAMIC_POST {
+            let mut encoded_h = HeaderEncoder::new(0, false, 1000);
+            encoded_h.encode_literal_with_name_ref(false, *index, VALUE);
+            encoded_h.encode_header_block_prefix();
+            assert_eq!(&&*encoded_h, result);
+        }
+    }
+
+    #[test]
+    fn test_encode_literal_with_name_ref_dynamic_huffman() {
+        for (index, result, _, _) in NAME_REF_DYNAMIC_HUFFMAN {
+            let mut encoded_h = HeaderEncoder::new(66, true, 1000);
+            encoded_h.encode_literal_with_name_ref(false, *index, VALUE);
+            encoded_h.encode_header_block_prefix();
+            assert_eq!(&&*encoded_h, result);
+        }
+    }
+    #[test]
+    fn test_encode_literal_with_literal() {
+        let mut encoded_h = HeaderEncoder::new(66, false, 1000);
+        encoded_h.encode_literal_with_name_literal(VALUE, VALUE);
+        encoded_h.encode_header_block_prefix();
+        assert_eq!(&*encoded_h, LITERAL_LITERAL);
+
+        let mut encoded_h = HeaderEncoder::new(66, true, 1000);
+        encoded_h.encode_literal_with_name_literal(VALUE, VALUE);
+        encoded_h.encode_header_block_prefix();
+        assert_eq!(&*encoded_h, LITERAL_LITERAL_HUFFMAN);
+    }
+
+    #[test]
+    fn decode_indexed_static() {
+        for (_, encoded, decoded1, decoded2) in INDEX_STATIC_TEST {
+            let table = HeaderTable::new(false);
+            let mut decoder_h = HeaderDecoder::new(encoded);
+            if let HeaderDecoderResult::Headers(result) =
+                decoder_h.decode_header_block(&table, 1000, 0).unwrap()
+            {
+                assert_eq!(result.len(), 1);
+                assert_eq!(result[0].name(), *decoded1);
+                assert_eq!(result[0].value(), *decoded2);
+            } else {
+                panic!("No headers");
+            }
+        }
+    }
+
+    fn fill_table(table: &mut HeaderTable) {
+        table.set_capacity(10000).unwrap();
+        for i in 0..66 {
+            let mut v = b"header".to_vec();
+            let mut num = i.to_string().as_bytes().to_vec();
+            v.append(&mut num);
+            table.insert(&v[..], i.to_string().as_bytes()).unwrap();
+        }
+    }
+
+    #[test]
+    fn decode_indexed_dynamic() {
+        for (_, encoded, decoded1, decoded2) in INDEX_DYNAMIC_TEST {
+            let mut table = HeaderTable::new(false);
+            fill_table(&mut table);
+            let mut decoder_h = HeaderDecoder::new(encoded);
+            if let HeaderDecoderResult::Headers(result) =
+                decoder_h.decode_header_block(&table, 1000, 0).unwrap()
+            {
+                assert_eq!(result.len(), 1);
+                assert_eq!(result[0].name(), *decoded1);
+                assert_eq!(result[0].value(), *decoded2);
+            } else {
+                panic!("No headers");
+            }
+        }
+    }
+
+    #[test]
+    fn decode_indexed_dynamic_post() {
+        for (_, encoded, decoded1, decoded2) in INDEX_DYNAMIC_POST_TEST {
+            let mut table = HeaderTable::new(false);
+            fill_table(&mut table);
+            let mut decoder_h = HeaderDecoder::new(encoded);
+            if let HeaderDecoderResult::Headers(result) =
+                decoder_h.decode_header_block(&table, 1000, 0).unwrap()
+            {
+                assert_eq!(result.len(), 1);
+                assert_eq!(result[0].name(), *decoded1);
+                assert_eq!(result[0].value(), *decoded2);
+            } else {
+                panic!("No headers");
+            }
+        }
+    }
+
+    #[test]
+    fn decode_literal_with_name_ref_static() {
+        for (_, encoded, decoded1, decoded2) in NAME_REF_STATIC {
+            let table = HeaderTable::new(false);
+            let mut decoder_h = HeaderDecoder::new(encoded);
+            if let HeaderDecoderResult::Headers(result) =
+                decoder_h.decode_header_block(&table, 1000, 0).unwrap()
+            {
+                assert_eq!(result.len(), 1);
+                assert_eq!(result[0].name(), *decoded1);
+                assert_eq!(result[0].value(), *decoded2);
+            } else {
+                panic!("No headers");
+            }
+        }
+    }
+
+    #[test]
+    fn decode_literal_with_name_ref_dynamic() {
+        for (_, encoded, decoded1, decoded2) in NAME_REF_DYNAMIC {
+            let mut table = HeaderTable::new(false);
+            fill_table(&mut table);
+            let mut decoder_h = HeaderDecoder::new(encoded);
+            if let HeaderDecoderResult::Headers(result) =
+                decoder_h.decode_header_block(&table, 1000, 0).unwrap()
+            {
+                assert_eq!(result.len(), 1);
+                assert_eq!(result[0].name(), *decoded1);
+                assert_eq!(result[0].value(), *decoded2);
+            } else {
+                panic!("No headers");
+            }
+        }
+    }
+
+    #[test]
+    fn decode_literal_with_name_ref_dynamic_post() {
+        for (_, encoded, decoded1, decoded2) in NAME_REF_DYNAMIC_POST {
+            let mut table = HeaderTable::new(false);
+            fill_table(&mut table);
+            let mut decoder_h = HeaderDecoder::new(encoded);
+            if let HeaderDecoderResult::Headers(result) =
+                decoder_h.decode_header_block(&table, 1000, 0).unwrap()
+            {
+                assert_eq!(result.len(), 1);
+                assert_eq!(result[0].name(), *decoded1);
+                assert_eq!(result[0].value(), *decoded2);
+            } else {
+                panic!("No headers");
+            }
+        }
+    }
+
+    #[test]
+    fn decode_literal_with_name_ref_dynamic_huffman() {
+        for (_, encoded, decoded1, decoded2) in NAME_REF_DYNAMIC_HUFFMAN {
+            let mut table = HeaderTable::new(false);
+            fill_table(&mut table);
+            let mut decoder_h = HeaderDecoder::new(encoded);
+            if let HeaderDecoderResult::Headers(result) =
+                decoder_h.decode_header_block(&table, 1000, 0).unwrap()
+            {
+                assert_eq!(result.len(), 1);
+                assert_eq!(result[0].name(), *decoded1);
+                assert_eq!(result[0].value(), *decoded2);
+            } else {
+                panic!("No headers");
+            }
+        }
+    }
+
+    #[test]
+    fn decode_literal_literal() {
+        let mut table = HeaderTable::new(false);
+        fill_table(&mut table);
+        let mut decoder_h = HeaderDecoder::new(LITERAL_LITERAL);
+        if let HeaderDecoderResult::Headers(result) =
+            decoder_h.decode_header_block(&table, 1000, 0).unwrap()
+        {
+            assert_eq!(result.len(), 1);
+            assert_eq!(result[0].name(), LITERAL_VALUE);
+            assert_eq!(result[0].value(), LITERAL_VALUE);
+        } else {
+            panic!("No headers");
+        }
+
+        let mut decoder_h = HeaderDecoder::new(LITERAL_LITERAL_HUFFMAN);
+        if let HeaderDecoderResult::Headers(result) =
+            decoder_h.decode_header_block(&table, 1000, 0).unwrap()
+        {
+            assert_eq!(result.len(), 1);
+            assert_eq!(result[0].name(), LITERAL_VALUE);
+            assert_eq!(result[0].value(), LITERAL_VALUE);
+        } else {
+            panic!("No headers");
+        }
+    }
+
+    // Test that we are ignoring N-bit.
+    #[test]
+    fn decode_ignore_n_bit() {
+        const TEST_N_BIT: &[(&[u8], &str, &str)] = &[
+            (
+                &[
+                    0x02, 0x41, 0x6f, 0x32, 0x0a, 0x63, 0x75, 0x73, 0x74, 0x6f, 0x6d, 0x2d, 0x6b,
+                    0x65, 0x79,
+                ],
+                "header0",
+                "custom-key",
+            ),
+            (
+                &[
+                    0x02, 0x80, 0x08, 0x0a, 0x63, 0x75, 0x73, 0x74, 0x6f, 0x6d, 0x2d, 0x6b, 0x65,
+                    0x79,
+                ],
+                "header0",
+                "custom-key",
+            ),
+            (
+                &[
+                    0x0, 0x42, 0x37, 0x03, 0x63, 0x75, 0x73, 0x74, 0x6f, 0x6d, 0x2d, 0x6b, 0x65,
+                    0x79, 0x0a, 0x63, 0x75, 0x73, 0x74, 0x6f, 0x6d, 0x2d, 0x6b, 0x65, 0x79,
+                ],
+                "custom-key",
+                "custom-key",
+            ),
+            (
+                &[
+                    0x0, 0x42, 0x3f, 0x01, 0x25, 0xa8, 0x49, 0xe9, 0x5b, 0xa9, 0x7d, 0x7f, 0x88,
+                    0x25, 0xa8, 0x49, 0xe9, 0x5b, 0xa9, 0x7d, 0x7f,
+                ],
+                "custom-key",
+                "custom-key",
+            ),
+        ];
+
+        for (encoded, decoded1, decoded2) in TEST_N_BIT {
+            let mut table = HeaderTable::new(false);
+            fill_table(&mut table);
+            let mut decoder_h = HeaderDecoder::new(encoded);
+            if let HeaderDecoderResult::Headers(result) =
+                decoder_h.decode_header_block(&table, 1000, 0).unwrap()
+            {
+                assert_eq!(result.len(), 1);
+                assert_eq!(result[0].name(), *decoded1);
+                assert_eq!(result[0].value(), *decoded2);
+            } else {
+                panic!("No headers");
+            }
+        }
+    }
+
+    /// If the base calculation goes negative, that is an error.
+    #[test]
+    fn negative_base() {
+        let mut table = HeaderTable::new(false);
+        fill_table(&mut table);
+        let mut decoder_h = HeaderDecoder::new(&[0x0, 0x87, 0x01, 0x02, 0x03]);
+        assert_eq!(
+            Error::DecompressionFailed,
+            decoder_h.decode_header_block(&table, 1000, 0).unwrap_err()
+        );
+    }
+
+    /// If the base calculation overflows the largest value we support (`u64::MAX`),
+    /// then that is an error.
+    #[test]
+    fn overflow_base() {
+        let mut table = HeaderTable::new(false);
+        fill_table(&mut table);
+        // A small required insert count is necessary, but we can set the
+        // base delta to u64::MAX.
+        let mut decoder_h = HeaderDecoder::new(&[
+            0xff, 0x01, 0x7f, 0x80, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x01, 0x02,
+            0x03,
+        ]);
+        assert_eq!(
+            Error::DecompressionFailed,
+            decoder_h.decode_header_block(&table, 1000, 0).unwrap_err()
+        );
+    }
+}
diff --git a/third_party/rust/neqo-qpack/src/huffman.rs b/third_party/rust/neqo-qpack/src/huffman.rs
new file mode 100644
index 0000000000..283a501b32
--- /dev/null
+++ b/third_party/rust/neqo-qpack/src/huffman.rs
@@ -0,0 +1,265 @@
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use std::convert::TryFrom;
+
+use crate::{
+    huffman_decode_helper::{HuffmanDecoderNode, HUFFMAN_DECODE_ROOT},
+    huffman_table::HUFFMAN_TABLE,
+    Error, Res,
+};
+
+struct BitReader<'a> {
+    input: &'a [u8],
+    offset: usize,
+    current_bit: u8,
+}
+
+impl<'a> BitReader<'a> {
+    pub fn new(input: &'a [u8]) -> Self {
+        BitReader {
+            input,
+            offset: 0,
+            current_bit: 8,
+        }
+    }
+
+    pub fn read_bit(&mut self) -> Res<u8> {
+        if self.input.len() == self.offset {
+            return Err(Error::NeedMoreData);
+        }
+
+        if self.current_bit == 0 {
+            self.offset += 1;
+            if self.offset == self.input.len() {
+                return Err(Error::NeedMoreData);
+            }
+            self.current_bit = 8;
+        }
+        self.current_bit -= 1;
+        Ok((self.input[self.offset] >> self.current_bit) & 0x01)
+    }
+
+    pub fn verify_ending(&mut self, i: u8) -> Res<()> {
+        if (i + self.current_bit) > 7 {
+            return Err(Error::HuffmanDecompressionFailed);
+        }
+
+        if self.input.is_empty() {
+            Ok(())
+        } else if self.offset != self.input.len() {
+            Err(Error::HuffmanDecompressionFailed)
+        } else if self.input[self.input.len() - 1] & ((0x1 << (i + self.current_bit)) - 1)
+            == ((0x1 << (i + self.current_bit)) - 1)
+        {
+            self.current_bit = 0;
+            Ok(())
+        } else {
+            Err(Error::HuffmanDecompressionFailed)
+        }
+    }
+
+    pub fn has_more_data(&self) -> bool {
+        !self.input.is_empty() && (self.offset != self.input.len() || (self.current_bit != 0))
+    }
+}
+
+/// Decodes huffman encoded input.
+///
+/// # Errors
+///
+/// This function may return `HuffmanDecompressionFailed` if `input` is not a correct
+/// huffman-encoded array of bits.
+///
+/// # Panics
+///
+/// Never, but rust can't know that.
+pub fn decode_huffman(input: &[u8]) -> Res<Vec<u8>> {
+    let mut reader = BitReader::new(input);
+    let mut output = Vec::new();
+    while reader.has_more_data() {
+        if let Some(c) = decode_character(&mut reader)? {
+            if c == 256 {
+                return Err(Error::HuffmanDecompressionFailed);
+            }
+            output.push(u8::try_from(c).unwrap());
+        }
+    }
+
+    Ok(output)
+}
+
+fn decode_character(reader: &mut BitReader) -> Res<Option<u16>> {
+    let mut node: &HuffmanDecoderNode = &HUFFMAN_DECODE_ROOT;
+    let mut i = 0;
+    while node.value.is_none() {
+        match reader.read_bit() {
+            Err(_) => {
+                reader.verify_ending(i)?;
+                return Ok(None);
+            }
+            Ok(b) => {
+                i += 1;
+                if let Some(next) = &node.next[usize::from(b)] {
+                    node = next;
+                } else {
+                    reader.verify_ending(i)?;
+                    return Ok(None);
+                }
+            }
+        }
+    }
+    debug_assert!(node.value.is_some());
+    Ok(node.value)
+}
+
+/// # Panics
+///
+/// Never, but rust doesn't know that.
+#[must_use]
+pub fn encode_huffman(input: &[u8]) -> Vec<u8> {
+    let mut output: Vec<u8> = Vec::new();
+    let mut left: u8 = 8;
+    let mut saved: u8 = 0;
+    for c in input {
+        let mut e = HUFFMAN_TABLE[*c as usize];
+
+        // Fill the previous byte
+        if e.len < left {
+            let b = u8::try_from(e.val & 0xFF).unwrap();
+            saved |= b << (left - e.len);
+            left -= e.len;
+            e.len = 0;
+        } else {
+            let v: u8 = u8::try_from(e.val >> (e.len - left)).unwrap();
+            saved |= v;
+            output.push(saved);
+            e.len -= left;
+            left = 8;
+            saved = 0;
+        }
+
+        // Write full bytes
+        while e.len >= 8 {
+            let v: u8 = u8::try_from((e.val >> (e.len - 8)) & 0xFF).unwrap();
+            output.push(v);
+            e.len -= 8;
+        }
+
+        // Write the rest into saved.
+        if e.len > 0 {
+            saved = u8::try_from(e.val & ((1 << e.len) - 1)).unwrap() << (8 - e.len);
+            left = 8 - e.len;
+        }
+    }
+
+    if left < 8 {
+        let v: u8 = (1 << left) - 1;
+        saved |= v;
+        output.push(saved);
+    }
+
+    output
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{decode_huffman, encode_huffman, Error};
+
+    struct TestElement {
+        pub val: &'static [u8],
+        pub res: &'static [u8],
+    }
+    const TEST_CASES: &[TestElement] = &[
+        TestElement {
+            val: b"www.example.com",
+            res: &[
+                0xf1, 0xe3, 0xc2, 0xe5, 0xf2, 0x3a, 0x6b, 0xa0, 0xab, 0x90, 0xf4, 0xff,
+            ],
+        },
+        TestElement {
+            val: b"no-cache",
+            res: &[0xa8, 0xeb, 0x10, 0x64, 0x9c, 0xbf],
+        },
+        TestElement {
+            val: b"custom-key",
+            res: &[0x25, 0xa8, 0x49, 0xe9, 0x5b, 0xa9, 0x7d, 0x7f],
+        },
+        TestElement {
+            val: b"custom-value",
+            res: &[0x25, 0xa8, 0x49, 0xe9, 0x5b, 0xb8, 0xe8, 0xb4, 0xbf],
+        },
+        TestElement {
+            val: b"private",
+            res: &[0xae, 0xc3, 0x77, 0x1a, 0x4b],
+        },
+        TestElement {
+            val: b"Mon, 21 Oct 2013 20:13:21 GMT",
+            res: &[
+                0xd0, 0x7a, 0xbe, 0x94, 0x10, 0x54, 0xd4, 0x44, 0xa8, 0x20, 0x05, 0x95, 0x04, 0x0b,
+                0x81, 0x66, 0xe0, 0x82, 0xa6, 0x2d, 0x1b, 0xff,
+            ],
+        },
+        TestElement {
+            val: b"https://www.example.com",
+            res: &[
+                0x9d, 0x29, 0xad, 0x17, 0x18, 0x63, 0xc7, 0x8f, 0x0b, 0x97, 0xc8, 0xe9, 0xae, 0x82,
+                0xae, 0x43, 0xd3,
+            ],
+        },
+        TestElement {
+            val: b"Mon, 21 Oct 2013 20:13:22 GMT",
+            res: &[
+                0xd0, 0x7a, 0xbe, 0x94, 0x10, 0x54, 0xd4, 0x44, 0xa8, 0x20, 0x05, 0x95, 0x04, 0x0b,
+                0x81, 0x66, 0xe0, 0x84, 0xa6, 0x2d, 0x1b, 0xff,
+            ],
+        },
+        TestElement {
+            val: b"gzip",
+            res: &[0x9b, 0xd9, 0xab],
+        },
+        TestElement {
+            val: b"foo=ASDJKHQKBZXOQWEOPIUAXQWEOIU; max-age=3600; version=1",
+            res: &[
+                0x94, 0xe7, 0x82, 0x1d, 0xd7, 0xf2, 0xe6, 0xc7, 0xb3, 0x35, 0xdf, 0xdf, 0xcd, 0x5b,
+                0x39, 0x60, 0xd5, 0xaf, 0x27, 0x08, 0x7f, 0x36, 0x72, 0xc1, 0xab, 0x27, 0x0f, 0xb5,
+                0x29, 0x1f, 0x95, 0x87, 0x31, 0x60, 0x65, 0xc0, 0x03, 0xed, 0x4e, 0xe5, 0xb1, 0x06,
+                0x3d, 0x50, 0x07,
+            ],
+        },
+        TestElement {
+            val: b"<?\\ >",
+            res: &[0xff, 0xf9, 0xfe, 0x7f, 0xff, 0x05, 0x3f, 0xef],
+        },
+    ];
+
+    const WRONG_END: &[u8] = &[0xa8, 0xeb, 0x10, 0x64, 0x9c, 0xaf];
+
+    #[test]
+    fn test_encoder() {
+        for e in TEST_CASES {
+            let out = encode_huffman(e.val);
+            assert_eq!(out[..], *e.res);
+        }
+    }
+
+    #[test]
+    fn test_decoder() {
+        for e in TEST_CASES {
+            let res = decode_huffman(e.res);
+            assert!(res.is_ok());
+            assert_eq!(res.unwrap()[..], *e.val);
+        }
+    }
+
+    #[test]
+    fn decoder_error_wrong_ending() {
+        assert_eq!(
+            decode_huffman(WRONG_END),
+            Err(Error::HuffmanDecompressionFailed)
+        );
+    }
+}
diff --git a/third_party/rust/neqo-qpack/src/huffman_decode_helper.rs b/third_party/rust/neqo-qpack/src/huffman_decode_helper.rs
new file mode 100644
index 0000000000..122226dd1f
--- /dev/null
+++ b/third_party/rust/neqo-qpack/src/huffman_decode_helper.rs
@@ -0,0 +1,57 @@
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use std::convert::TryFrom;
+
+use lazy_static::lazy_static;
+
+use crate::huffman_table::HUFFMAN_TABLE;
+
+pub struct HuffmanDecoderNode {
+    pub next: [Option<Box<HuffmanDecoderNode>>; 2],
+    pub value: Option<u16>,
+}
+
+lazy_static! {
+    pub static ref HUFFMAN_DECODE_ROOT: HuffmanDecoderNode = make_huffman_tree(0, 0);
+}
+
+fn make_huffman_tree(prefix: u32, len: u8) -> HuffmanDecoderNode {
+    let mut found = false;
+    let mut next = [None, None];
+    for (i, iter) in HUFFMAN_TABLE.iter().enumerate() {
+        if iter.len <= len {
+            continue;
+        }
+        if (iter.val >> (iter.len - len)) != prefix {
+            continue;
+        }
+
+        found = true;
+        if iter.len == len + 1 {
+            // This is a leaf
+            let bit = usize::try_from(iter.val & 1).unwrap();
+            next[bit] = Some(Box::new(HuffmanDecoderNode {
+                next: [None, None],
+                value: Some(u16::try_from(i).unwrap()),
+            }));
+            if next[bit ^ 1].is_some() {
+                return HuffmanDecoderNode { next, value: None };
+            }
+        }
+    }
+
+    if found {
+        if next[0].is_none() {
+            next[0] = Some(Box::new(make_huffman_tree(prefix << 1, len + 1)));
+        }
+        if next[1].is_none() {
+            next[1] = Some(Box::new(make_huffman_tree((prefix << 1) + 1, len + 1)));
+        }
+    }
+
+    HuffmanDecoderNode { next, value: None }
+}
diff --git a/third_party/rust/neqo-qpack/src/huffman_table.rs b/third_party/rust/neqo-qpack/src/huffman_table.rs
new file mode 100644
index 0000000000..928f6860a5
--- /dev/null
+++ b/third_party/rust/neqo-qpack/src/huffman_table.rs
@@ -0,0 +1,280 @@
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#[derive(Debug, Copy, Clone)]
+pub struct HuffmanTableEntry {
+    pub len: u8,
+    pub val: u32,
+}
+
+macro_rules! huffman_table {
+    [$($v:expr => $l:expr),+ $(,)?] => {
+        &[
+            $(HuffmanTableEntry { len: $l, val: $v }),+
+        ]
+    };
+}
+
+// Table contains the raw HPACK Huffman table
+pub const HUFFMAN_TABLE: &[HuffmanTableEntry] = huffman_table![
+    0x1ff8 => 13,
+    0x007f_ffd8 => 23,
+    0x0fff_ffe2 => 28,
+    0x0fff_ffe3 => 28,
+    0x0fff_ffe4 => 28,
+    0x0fff_ffe5 => 28,
+    0x0fff_ffe6 => 28,
+    0x0fff_ffe7 => 28,
+    0x0fff_ffe8 => 28,
+    0x00ff_ffea => 24,
+    0x3fff_fffc => 30,
+    0x0fff_ffe9 => 28,
+    0x0fff_ffea => 28,
+    0x3fff_fffd => 30,
+    0x0fff_ffeb => 28,
+    0x0fff_ffec => 28,
+    0x0fff_ffed => 28,
+    0x0fff_ffee => 28,
+    0x0fff_ffef => 28,
+    0x0fff_fff0 => 28,
+    0x0fff_fff1 => 28,
+    0x0fff_fff2 => 28,
+    0x3fff_fffe => 30,
+    0x0fff_fff3 => 28,
+    0x0fff_fff4 => 28,
+    0x0fff_fff5 => 28,
+    0x0fff_fff6 => 28,
+    0x0fff_fff7 => 28,
+    0x0fff_fff8 => 28,
+    0x0fff_fff9 => 28,
+    0x0fff_fffa => 28,
+    0x0fff_fffb => 28,
+    0x14 => 6, // ' '
+    0x3f8 => 10, // '!'
+    0x3f9 => 10, // '"'
+    0xffa => 12, // '#'
+    0x1ff9 => 13, // '$'
+    0x15 => 6, // '%'
+    0xf8 => 8, // '&'
+    0x7fa => 11, // '''
+    0x3fa => 10, // '('
+    0x3fb => 10, // ')'
+    0xf9 => 8, // '*'
+    0x7fb => 11, // '+'
+    0xfa => 8, // ','
+    0x16 => 6, // '-'
+    0x17 => 6, // '.'
+    0x18 => 6, // '/'
+    0x0 => 5, // '0'
+    0x1 => 5, // '1'
+    0x2 => 5, // '2'
+    0x19 => 6, // '3'
+    0x1a => 6, // '4'
+    0x1b => 6, // '5'
+    0x1c => 6, // '6'
+    0x1d => 6, // '7'
+    0x1e => 6, // '8'
+    0x1f => 6, // '9'
+    0x5c => 7, // ':'
+    0xfb => 8, // ';'
+    0x7ffc => 15, // '<'
+    0x20 => 6, // '='
+    0xffb => 12, // '>'
+    0x3fc => 10, // '?'
+    0x1ffa => 13, // '@'
+    0x21 => 6, // 'A'
+    0x5d => 7, // 'B'
+    0x5e => 7, // 'C'
+    0x5f => 7, // 'D'
+    0x60 => 7, // 'E'
+    0x61 => 7, // 'F'
+    0x62 => 7, // 'G'
+    0x63 => 7, // 'H'
+    0x64 => 7, // 'I'
+    0x65 => 7, // 'J'
+    0x66 => 7, // 'K'
+    0x67 => 7, // 'L'
+    0x68 => 7, // 'M'
+    0x69 => 7, // 'N'
+    0x6a => 7, // 'O'
+    0x6b => 7, // 'P'
+    0x6c => 7, // 'Q'
+    0x6d => 7, // 'R'
+    0x6e => 7, // 'S'
+    0x6f => 7, // 'T'
+    0x70 => 7, // 'U'
+    0x71 => 7, // 'V'
+    0x72 => 7, // 'W'
+    0xfc => 8, // 'X'
+    0x73 => 7, // 'Y'
+    0xfd => 8, // 'Z'
+    0x1ffb => 13, // '['
+    0x0007_fff0 => 19, // '\'
+    0x1ffc => 13, // ']'
+    0x3ffc => 14, // '^'
+    0x22 => 6, // '_'
+    0x7ffd => 15, // '`'
+    0x3 => 5, // 'a'
+    0x23 => 6, // 'b'
+    0x4 => 5, // 'c'
+    0x24 => 6, // 'd'
+    0x5 => 5, // 'e'
+    0x25 => 6, // 'f'
+    0x26 => 6, // 'g'
+    0x27 => 6, // 'h'
+    0x6 => 5, // 'i'
+    0x74 => 7, // 'j'
+    0x75 => 7, // 'k'
+    0x28 => 6, // 'l'
+    0x29 => 6, // 'm'
+    0x2a => 6, // 'n'
+    0x7 => 5, // 'o'
+    0x2b => 6, // 'p'
+    0x76 => 7, // 'q'
+    0x2c => 6, // 'r'
+    0x8 => 5, // 's'
+    0x9 => 5, // 't'
+    0x2d => 6, // 'u'
+    0x77 => 7, // 'v'
+    0x78 => 7, // 'w'
+    0x79 => 7, // 'x'
+    0x7a => 7, // 'y'
+    0x7b => 7, // 'z'
+    0x7ffe => 15, // '{'
+    0x7fc => 11, // '|'
+    0x3ffd => 14, // '}'
+    0x1ffd => 13, // '~'
+    0x0fff_fffc => 28,
+    0x000f_ffe6 => 20,
+    0x003f_ffd2 => 22,
+    0x000f_ffe7 => 20,
+    0x000f_ffe8 => 20,
+    0x003f_ffd3 => 22,
+    0x003f_ffd4 => 22,
+    0x003f_ffd5 => 22,
+    0x007f_ffd9 => 23,
+    0x003f_ffd6 => 22,
+    0x007f_ffda => 23,
+    0x007f_ffdb => 23,
+    0x007f_ffdc => 23,
+    0x007f_ffdd => 23,
+    0x007f_ffde => 23,
+    0x00ff_ffeb => 24,
+    0x007f_ffdf => 23,
+    0x00ff_ffec => 24,
+    0x00ff_ffed => 24,
+    0x003f_ffd7 => 22,
+    0x007f_ffe0 => 23,
+    0x00ff_ffee => 24,
+    0x007f_ffe1 => 23,
+    0x007f_ffe2 => 23,
+    0x007f_ffe3 => 23,
+    0x007f_ffe4 => 23,
+    0x001f_ffdc => 21,
+    0x003f_ffd8 => 22,
+    0x007f_ffe5 => 23,
+    0x003f_ffd9 => 22,
+    0x007f_ffe6 => 23,
+    0x007f_ffe7 => 23,
+    0x00ff_ffef => 24,
+    0x003f_ffda => 22,
+    0x001f_ffdd => 21,
+    0x000f_ffe9 => 20,
+    0x003f_ffdb => 22,
+    0x003f_ffdc => 22,
+    0x007f_ffe8 => 23,
+    0x007f_ffe9 => 23,
+    0x001f_ffde => 21,
+    0x007f_ffea => 23,
+    0x003f_ffdd => 22,
+    0x003f_ffde => 22,
+    0x00ff_fff0 => 24,
+    0x001f_ffdf => 21,
+    0x003f_ffdf => 22,
+    0x007f_ffeb => 23,
+    0x007f_ffec => 23,
+    0x001f_ffe0 => 21,
+    0x001f_ffe1 => 21,
+    0x003f_ffe0 => 22,
+    0x001f_ffe2 => 21,
+    0x007f_ffed => 23,
+    0x003f_ffe1 => 22,
+    0x007f_ffee => 23,
+    0x007f_ffef => 23,
+    0x000f_ffea => 20,
+    0x003f_ffe2 => 22,
+    0x003f_ffe3 => 22,
+    0x003f_ffe4 => 22,
+    0x007f_fff0 => 23,
+    0x003f_ffe5 => 22,
+    0x003f_ffe6 => 22,
+    0x007f_fff1 => 23,
+    0x03ff_ffe0 => 26,
+    0x03ff_ffe1 => 26,
+    0x000f_ffeb => 20,
+    0x0007_fff1 => 19,
+    0x003f_ffe7 => 22,
+    0x007f_fff2 => 23,
+    0x003f_ffe8 => 22,
+    0x01ff_ffec => 25,
+    0x03ff_ffe2 => 26,
+    0x03ff_ffe3 => 26,
+    0x03ff_ffe4 => 26,
+    0x07ff_ffde => 27,
+    0x07ff_ffdf => 27,
+    0x03ff_ffe5 => 26,
+    0x00ff_fff1 => 24,
+    0x01ff_ffed => 25,
+    0x0007_fff2 => 19,
+    0x001f_ffe3 => 21,
+    0x03ff_ffe6 => 26,
+    0x07ff_ffe0 => 27,
+    0x07ff_ffe1 => 27,
+    0x03ff_ffe7 => 26,
+    0x07ff_ffe2 => 27,
+    0x00ff_fff2 => 24,
+    0x001f_ffe4 => 21,
+    0x001f_ffe5 => 21,
+    0x03ff_ffe8 => 26,
+    0x03ff_ffe9 => 26,
+    0x0fff_fffd => 28,
+    0x07ff_ffe3 => 27,
+    0x07ff_ffe4 => 27,
+    0x07ff_ffe5 => 27,
+    0x000f_ffec => 20,
+    0x00ff_fff3 => 24,
+    0x000f_ffed => 20,
+    0x001f_ffe6 => 21,
+    0x003f_ffe9 => 22,
+    0x001f_ffe7 => 21,
+    0x001f_ffe8 => 21,
+    0x007f_fff3 => 23,
+    0x003f_ffea => 22,
+    0x003f_ffeb => 22,
+    0x01ff_ffee => 25,
+    0x01ff_ffef => 25,
+    0x00ff_fff4 => 24,
+    0x00ff_fff5 => 24,
+    0x03ff_ffea => 26,
+    0x007f_fff4 => 23,
+    0x03ff_ffeb => 26,
+    0x07ff_ffe6 => 27,
+    0x03ff_ffec => 26,
+    0x03ff_ffed => 26,
+    0x07ff_ffe7 => 27,
+    0x07ff_ffe8 => 27,
+    0x07ff_ffe9 => 27,
+    0x07ff_ffea => 27,
+    0x07ff_ffeb => 27,
+    0x0fff_fffe => 28,
+    0x07ff_ffec => 27,
+    0x07ff_ffed => 27,
+    0x07ff_ffee => 27,
+    0x07ff_ffef => 27,
+    0x07ff_fff0 => 27,
+    0x03ff_ffee => 26,
+    0x3fff_ffff => 30,
+];
diff --git a/third_party/rust/neqo-qpack/src/lib.rs b/third_party/rust/neqo-qpack/src/lib.rs
new file mode 100644
index 0000000000..1581712017
--- /dev/null
+++ b/third_party/rust/neqo-qpack/src/lib.rs
@@ -0,0 +1,121 @@
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![cfg_attr(feature = "deny-warnings", deny(warnings))]
+#![warn(clippy::pedantic)]
+// This is because of Encoder and Decoder structs. TODO: think about a better namings for crate and
+// structs.
+#![allow(clippy::module_name_repetitions)]
+
+pub mod decoder;
+mod decoder_instructions;
+pub mod encoder;
+mod encoder_instructions;
+mod header_block;
+pub mod huffman;
+mod huffman_decode_helper;
+pub mod huffman_table;
+mod prefix;
+mod qlog;
+mod qpack_send_buf;
+pub mod reader;
+mod static_table;
+mod stats;
+mod table;
+
+pub use decoder::QPackDecoder;
+pub use encoder::QPackEncoder;
+pub use stats::Stats;
+
+type Res<T> = Result<T, Error>;
+
+#[derive(Debug, PartialEq, PartialOrd, Ord, Eq, Clone, Copy)]
+pub struct QpackSettings {
+    pub max_table_size_decoder: u64,
+    pub max_table_size_encoder: u64,
+    pub max_blocked_streams: u16,
+}
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub enum Error {
+    DecompressionFailed,
+    EncoderStream,
+    DecoderStream,
+    ClosedCriticalStream,
+    InternalError,
+
+    // These are internal errors, they will be transformed into one of the above.
+    NeedMoreData, /* Return when an input stream does not have more data that a decoder
+                   * needs.(It does not mean that a stream is closed.) */
+    HeaderLookup,
+    HuffmanDecompressionFailed,
+    BadUtf8,
+    ChangeCapacity,
+    DynamicTableFull,
+    IncrementAck,
+    IntegerOverflow,
+    WrongStreamCount,
+    Decoding, // Decoding internal error that is not one of the above.
+    EncoderStreamBlocked,
+    Internal,
+
+    TransportError(neqo_transport::Error),
+    QlogError,
+}
+
+impl Error {
+    #[must_use]
+    pub fn code(&self) -> neqo_transport::AppError {
+        match self {
+            Self::DecompressionFailed => 0x200,
+            Self::EncoderStream => 0x201,
+            Self::DecoderStream => 0x202,
+            Self::ClosedCriticalStream => 0x104,
+            // These are all internal errors.
+            _ => 3,
+        }
+    }
+
+    /// # Errors
+    ///
+    /// Any error is mapped to the indicated type.
+    fn map_error<R>(r: Result<R, Self>, err: Self) -> Result<R, Self> {
+        r.map_err(|e| {
+            if matches!(e, Self::ClosedCriticalStream) {
+                e
+            } else {
+                err
+            }
+        })
+    }
+}
+
+impl ::std::error::Error for Error {
+    fn source(&self) -> Option<&(dyn ::std::error::Error + 'static)> {
+        match self {
+            Self::TransportError(e) => Some(e),
+            _ => None,
+        }
+    }
+}
+
+impl ::std::fmt::Display for Error {
+    fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
+        write!(f, "QPACK error: {self:?}")
+    }
+}
+
+impl From<neqo_transport::Error> for Error {
+    fn from(err: neqo_transport::Error) -> Self {
+        Self::TransportError(err)
+    }
+}
+
+impl From<::qlog::Error> for Error {
+    fn from(_err: ::qlog::Error) -> Self {
+        Self::QlogError
+    }
+}
diff --git a/third_party/rust/neqo-qpack/src/prefix.rs b/third_party/rust/neqo-qpack/src/prefix.rs
new file mode 100644
index 0000000000..0085de0df9
--- /dev/null
+++ b/third_party/rust/neqo-qpack/src/prefix.rs
@@ -0,0 +1,143 @@
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#[derive(Copy, Clone, Debug)]
+pub struct Prefix {
+    #[allow(unknown_lints)] // available with Rust v1.75
+    #[allow(clippy::struct_field_names)]
+    prefix: u8,
+    len: u8,
+    mask: u8,
+}
+
+impl Prefix {
+    pub fn new(prefix: u8, len: u8) -> Self {
+        // len should never be larger than 7.
+        // Most of Prefixes are instantiated as consts bellow. The only place where this
+        // construcrtor is used is in tests and when literals are encoded and the Huffman
+        // bit is added to one of the consts bellow. create_prefix guaranty that all const
+        // have len < 7 so we can safely assert that len is <=7.
+        assert!(len <= 7);
+        assert!((len == 0) || (prefix & ((1 << (8 - len)) - 1) == 0));
+        Self {
+            prefix,
+            len,
+            mask: if len == 0 {
+                0xFF
+            } else {
+                ((1 << len) - 1) << (8 - len)
+            },
+        }
+    }
+
+    pub fn len(self) -> u8 {
+        self.len
+    }
+
+    pub fn prefix(self) -> u8 {
+        self.prefix
+    }
+
+    pub fn cmp_prefix(self, b: u8) -> bool {
+        (b & self.mask) == self.prefix
+    }
+}
+
+#[macro_export]
+macro_rules! create_prefix {
+    ($n:ident) => {
+        pub const $n: Prefix = Prefix {
+            prefix: 0x0,
+            len: 0,
+            mask: 0xFF,
+        };
+    };
+    ($n:ident, $v:expr, $l:expr) => {
+        static_assertions::const_assert!($l < 7);
+        static_assertions::const_assert!($v & ((1 << (8 - $l)) - 1) == 0);
+        pub const $n: Prefix = Prefix {
+            prefix: $v,
+            len: $l,
+            mask: ((1 << $l) - 1) << (8 - $l),
+        };
+    };
+    ($n:ident, $v:expr, $l:expr, $m:expr) => {
+        static_assertions::const_assert!($l < 7);
+        static_assertions::const_assert!($v & ((1 << (8 - $l)) - 1) == 0);
+        static_assertions::const_assert!((((1 << $l) - 1) << (8 - $l)) >= $m);
+        pub const $n: Prefix = Prefix {
+            prefix: $v,
+            len: $l,
+            mask: $m,
+        };
+    };
+}
+
+create_prefix!(NO_PREFIX);
+//=====================================================================
+// Decoder instructions prefix
+//=====================================================================
+
+// | 1 |      Stream ID (7+)       |
+create_prefix!(DECODER_HEADER_ACK, 0x80, 1);
+
+// | 0 | 1 |     Stream ID (6+)    |
+create_prefix!(DECODER_STREAM_CANCELLATION, 0x40, 2);
+
+// | 0 | 0 |     Increment (6+)    |
+create_prefix!(DECODER_INSERT_COUNT_INCREMENT, 0x00, 2);
+
+//=====================================================================
+// Encoder instructions prefix
+//=====================================================================
+
+// | 0 | 0 | 1 |   Capacity (5+)   |
+create_prefix!(ENCODER_CAPACITY, 0x20, 3);
+
+// | 1 | T |    Name Index (6+)    |
+// T == 1 static
+// T == 0 dynamic
+create_prefix!(ENCODER_INSERT_WITH_NAME_REF_STATIC, 0xC0, 2);
+create_prefix!(ENCODER_INSERT_WITH_NAME_REF_DYNAMIC, 0x80, 2);
+
+// | 0 | 1 | H | Name Length (5+)  |
+// H is not relevant for decoding this prefix, therefore the mask is 1100 0000 = 0xC0
+create_prefix!(ENCODER_INSERT_WITH_NAME_LITERAL, 0x40, 2);
+
+// | 0 | 0 | 0 |    Index (5+)     |
+create_prefix!(ENCODER_DUPLICATE, 0x00, 3);
+
+//=====================================================================
+// Header block encoding prefixes
+//=====================================================================
+
+create_prefix!(BASE_PREFIX_POSITIVE, 0x00, 1);
+create_prefix!(BASE_PREFIX_NEGATIVE, 0x80, 1);
+
+// | 1 | T |  index(6+) |
+// T == 1 static
+// T == 0 dynamic
+create_prefix!(HEADER_FIELD_INDEX_STATIC, 0xC0, 2);
+create_prefix!(HEADER_FIELD_INDEX_DYNAMIC, 0x80, 2);
+
+// | 0 | 0 | 0 | 1 |  Index(4+) |
+create_prefix!(HEADER_FIELD_INDEX_DYNAMIC_POST, 0x10, 4);
+
+// | 0 | 1 | N | T |  Index(4+) |
+// T == 1 static
+// T == 0 dynamic
+// N is ignored, therefore the mask is 1101 0000 = 0xD0
+create_prefix!(HEADER_FIELD_LITERAL_NAME_REF_STATIC, 0x50, 4, 0xD0);
+create_prefix!(HEADER_FIELD_LITERAL_NAME_REF_DYNAMIC, 0x40, 4, 0xD0);
+
+// | 0 | 0 | 0 | 0 | N |  Index(3+) |
+// N is ignored, therefore the mask is 1111 0000 = 0xF0
+create_prefix!(HEADER_FIELD_LITERAL_NAME_REF_DYNAMIC_POST, 0x00, 5, 0xF0);
+
+// | 0 | 0 | 1 | N | H |  Index(3+) |
+// N is ignored and H is not relevant for decoding this prefix, therefore the mask is 1110 0000 =
+// 0xE0
+create_prefix!(HEADER_FIELD_LITERAL_NAME_LITERAL, 0x20, 4, 0xE0);
diff --git a/third_party/rust/neqo-qpack/src/qlog.rs b/third_party/rust/neqo-qpack/src/qlog.rs
new file mode 100644
index 0000000000..8d48efb0aa
--- /dev/null
+++ b/third_party/rust/neqo-qpack/src/qlog.rs
@@ -0,0 +1,36 @@
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// Functions that handle capturing QLOG traces.
+
+use neqo_common::{hex, qlog::NeqoQlog};
+use qlog::events::{
+    qpack::{QPackInstruction, QpackInstructionParsed, QpackInstructionTypeName},
+    EventData, RawInfo,
+};
+
+pub fn qpack_read_insert_count_increment_instruction(
+    qlog: &mut NeqoQlog,
+    increment: u64,
+    data: &[u8],
+) {
+    qlog.add_event_data(|| {
+        let raw = RawInfo {
+            length: Some(8),
+            payload_length: None,
+            data: Some(hex(data)),
+        };
+        let ev_data = EventData::QpackInstructionParsed(QpackInstructionParsed {
+            instruction: QPackInstruction::InsertCountIncrementInstruction {
+                instruction_type: QpackInstructionTypeName::InsertCountIncrementInstruction,
+                increment,
+            },
+            raw: Some(raw),
+        });
+
+        Some(ev_data)
+    });
+}
diff --git a/third_party/rust/neqo-qpack/src/qpack_send_buf.rs b/third_party/rust/neqo-qpack/src/qpack_send_buf.rs
new file mode 100644
index 0000000000..a443859081
--- /dev/null
+++ b/third_party/rust/neqo-qpack/src/qpack_send_buf.rs
@@ -0,0 +1,161 @@
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use std::{convert::TryFrom, ops::Deref};
+
+use neqo_common::Encoder;
+
+use crate::{huffman::encode_huffman, prefix::Prefix};
+
+#[derive(Default, Debug, PartialEq)]
+pub(crate) struct QpackData {
+    buf: Vec<u8>,
+}
+
+impl QpackData {
+    pub fn len(&self) -> usize {
+        self.buf.len()
+    }
+
+    fn write_byte(&mut self, b: u8) {
+        self.buf.push(b);
+    }
+
+    pub fn encode_varint(&mut self, i: u64) {
+        let mut enc = Encoder::default();
+        enc.encode_varint(i);
+        self.buf.append(&mut enc.into());
+    }
+
+    pub(crate) fn encode_prefixed_encoded_int(&mut self, prefix: Prefix, mut val: u64) -> usize {
+        let first_byte_max: u8 = if prefix.len() == 0 {
+            0xff
+        } else {
+            (1 << (8 - prefix.len())) - 1
+        };
+
+        if val < u64::from(first_byte_max) {
+            let v = u8::try_from(val).unwrap();
+            self.write_byte((prefix.prefix() & !first_byte_max) | v);
+            return 1;
+        }
+
+        self.write_byte(prefix.prefix() | first_byte_max);
+        val -= u64::from(first_byte_max);
+
+        let mut written = 1;
+        let mut done = false;
+        while !done {
+            let mut b = u8::try_from(val & 0x7f).unwrap();
+            val >>= 7;
+            if val > 0 {
+                b |= 0x80;
+            } else {
+                done = true;
+            }
+
+            self.write_byte(b);
+            written += 1;
+        }
+        written
+    }
+
+    pub fn encode_literal(&mut self, use_huffman: bool, prefix: Prefix, value: &[u8]) {
+        let real_prefix = Prefix::new(
+            if use_huffman {
+                prefix.prefix() | (0x80 >> prefix.len())
+            } else {
+                prefix.prefix()
+            },
+            prefix.len() + 1,
+        );
+
+        if use_huffman {
+            let encoded = encode_huffman(value);
+            self.encode_prefixed_encoded_int(real_prefix, u64::try_from(encoded.len()).unwrap());
+            self.write_bytes(&encoded);
+        } else {
+            self.encode_prefixed_encoded_int(real_prefix, u64::try_from(value.len()).unwrap());
+            self.write_bytes(value);
+        }
+    }
+
+    pub fn write_bytes(&mut self, buf: &[u8]) {
+        self.buf.extend_from_slice(buf);
+    }
+
+    pub fn read(&mut self, r: usize) {
+        assert!(
+            r <= self.buf.len(),
+            "want to set more bytes read than remain in the buffer."
+        );
+        self.buf = self.buf.split_off(r);
+    }
+}
+
+impl Deref for QpackData {
+    type Target = [u8];
+    fn deref(&self) -> &Self::Target {
+        &self.buf
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{Prefix, QpackData};
+
+    #[test]
+    fn test_encode_prefixed_encoded_int_1() {
+        let mut d = QpackData::default();
+        d.encode_prefixed_encoded_int(Prefix::new(0xC0, 2), 5);
+        assert_eq!(d[..], [0xc5]);
+    }
+
+    #[test]
+    fn test_encode_prefixed_encoded_int_2() {
+        let mut d = QpackData::default();
+        d.encode_prefixed_encoded_int(Prefix::new(0xC0, 2), 65);
+        assert_eq!(d[..], [0xff, 0x02]);
+    }
+
+    #[test]
+    fn test_encode_prefixed_encoded_int_3() {
+        let mut d = QpackData::default();
+        d.encode_prefixed_encoded_int(Prefix::new(0xC0, 2), 100_000);
+        assert_eq!(d[..], [0xff, 0xe1, 0x8c, 0x06]);
+    }
+
+    #[test]
+    fn max_int() {
+        let mut d = QpackData::default();
+        d.encode_prefixed_encoded_int(Prefix::new(0x80, 1), u64::MAX);
+        assert_eq!(
+            d[..],
+            [0xff, 0x80, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x01]
+        );
+    }
+
+    const VALUE: &[u8] = b"custom-key";
+
+    const LITERAL: &[u8] = &[
+        0xca, 0x63, 0x75, 0x73, 0x74, 0x6f, 0x6d, 0x2d, 0x6b, 0x65, 0x79,
+    ];
+    const LITERAL_HUFFMAN: &[u8] = &[0xe8, 0x25, 0xa8, 0x49, 0xe9, 0x5b, 0xa9, 0x7d, 0x7f];
+
+    #[test]
+    fn test_encode_literal() {
+        let mut d = QpackData::default();
+        d.encode_literal(false, Prefix::new(0xC0, 2), VALUE);
+        assert_eq!(&&d[..], &LITERAL);
+    }
+
+    #[test]
+    fn test_encode_literal_huffman() {
+        let mut d = QpackData::default();
+        d.encode_literal(true, Prefix::new(0xC0, 2), VALUE);
+        assert_eq!(&&d[..], &LITERAL_HUFFMAN);
+    }
+}
diff --git a/third_party/rust/neqo-qpack/src/reader.rs b/third_party/rust/neqo-qpack/src/reader.rs
new file mode 100644
index 0000000000..ff9c42b246
--- /dev/null
+++ b/third_party/rust/neqo-qpack/src/reader.rs
@@ -0,0 +1,598 @@
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use std::{convert::TryInto, mem, str};
+
+use neqo_common::{qdebug, qerror};
+use neqo_transport::{Connection, StreamId};
+
+use crate::{huffman::decode_huffman, prefix::Prefix, Error, Res};
+
+pub trait ReadByte {
+    /// # Errors
+    ///
+    /// Return error occurred while reading a byte.
+    /// The exact error depends on trait implementation.
+    fn read_byte(&mut self) -> Res<u8>;
+}
+
+pub trait Reader {
+    /// # Errors
+    ///
+    /// Return error occurred while reading date into a buffer.
+    /// The exact error depends on trait implementation.
+    fn read(&mut self, buf: &mut [u8]) -> Res<usize>;
+}
+
+pub(crate) struct ReceiverConnWrapper<'a> {
+    conn: &'a mut Connection,
+    stream_id: StreamId,
+}
+
+impl<'a> ReadByte for ReceiverConnWrapper<'a> {
+    fn read_byte(&mut self) -> Res<u8> {
+        let mut b = [0];
+        match self.conn.stream_recv(self.stream_id, &mut b)? {
+            (_, true) => Err(Error::ClosedCriticalStream),
+            (0, false) => Err(Error::NeedMoreData),
+            _ => Ok(b[0]),
+        }
+    }
+}
+
+impl<'a> Reader for ReceiverConnWrapper<'a> {
+    fn read(&mut self, buf: &mut [u8]) -> Res<usize> {
+        match self.conn.stream_recv(self.stream_id, buf)? {
+            (_, true) => Err(Error::ClosedCriticalStream),
+            (amount, false) => Ok(amount),
+        }
+    }
+}
+
+impl<'a> ReceiverConnWrapper<'a> {
+    pub fn new(conn: &'a mut Connection, stream_id: StreamId) -> Self {
+        Self { conn, stream_id }
+    }
+}
+
+/// This is only used by header decoder therefore all errors are `DecompressionFailed`.
+/// A header block is read entirely before decoding it, therefore if there is not enough
+/// data in the buffer an error `DecompressionFailed` will be return.
+pub(crate) struct ReceiverBufferWrapper<'a> {
+    buf: &'a [u8],
+    offset: usize,
+}
+
+impl<'a> ReadByte for ReceiverBufferWrapper<'a> {
+    fn read_byte(&mut self) -> Res<u8> {
+        if self.offset == self.buf.len() {
+            Err(Error::DecompressionFailed)
+        } else {
+            let b = self.buf[self.offset];
+            self.offset += 1;
+            Ok(b)
+        }
+    }
+}
+
+impl<'a> ReceiverBufferWrapper<'a> {
+    pub fn new(buf: &'a [u8]) -> Self {
+        Self { buf, offset: 0 }
+    }
+
+    pub fn peek(&self) -> Res<u8> {
+        if self.offset == self.buf.len() {
+            Err(Error::DecompressionFailed)
+        } else {
+            Ok(self.buf[self.offset])
+        }
+    }
+
+    pub fn done(&self) -> bool {
+        self.offset == self.buf.len()
+    }
+
+    /// The function decodes varint with a prefixed, i.e. ignores `prefix_len` bits of the first
+    /// byte.
+    /// `ReceiverBufferWrapper` is only used for decoding header blocks. The header blocks are read
+    /// entirely before a decoding starts, therefore any incomplete varint because of reaching the
+    /// end of a buffer will be treated as the `DecompressionFailed` error.
+    pub fn read_prefixed_int(&mut self, prefix_len: u8) -> Res<u64> {
+        debug_assert!(prefix_len < 8);
+
+        let first_byte = self.read_byte()?;
+        let mut reader = IntReader::new(first_byte, prefix_len);
+        reader.read(self)
+    }
+
+    /// Do not use `LiteralReader` here to avoid copying data.
+    /// The function decoded a literal with a prefix:
+    ///   1) ignores `prefix_len` bits of the first byte,
+    ///   2) reads "huffman bit"
+    ///   3) decode varint that is the length of a literal
+    ///   4) reads the literal
+    ///   5) performs huffman decoding if needed.
+    ///
+    /// `ReceiverBufferWrapper` is only used for decoding header blocks. The header blocks are read
+    /// entirely before a decoding starts, therefore any incomplete varint or literal because of
+    /// reaching the end of a buffer will be treated as the `DecompressionFailed` error.
+    pub fn read_literal_from_buffer(&mut self, prefix_len: u8) -> Res<String> {
+        debug_assert!(prefix_len < 7);
+
+        let first_byte = self.read_byte()?;
+        let use_huffman = (first_byte & (0x80 >> prefix_len)) != 0;
+        let mut int_reader = IntReader::new(first_byte, prefix_len + 1);
+        let length: usize = int_reader
+            .read(self)?
+            .try_into()
+            .or(Err(Error::DecompressionFailed))?;
+        if use_huffman {
+            Ok(parse_utf8(&decode_huffman(self.slice(length)?)?)?.to_string())
+        } else {
+            Ok(parse_utf8(self.slice(length)?)?.to_string())
+        }
+    }
+
+    fn slice(&mut self, len: usize) -> Res<&[u8]> {
+        if self.offset + len > self.buf.len() {
+            Err(Error::DecompressionFailed)
+        } else {
+            let start = self.offset;
+            self.offset += len;
+            Ok(&self.buf[start..self.offset])
+        }
+    }
+}
+
+/// This is varint reader that can take into account a prefix.
+#[derive(Debug)]
+pub struct IntReader {
+    value: u64,
+    cnt: u8,
+    done: bool,
+}
+
+impl IntReader {
+    /// `IntReader` is created by suppling the first byte anf prefix length.
+    /// A varint may take only one byte, In that case already the first by has set state to done.
+    ///
+    /// # Panics
+    ///
+    /// When `prefix_len` is 8 or larger.
+    #[must_use]
+    pub fn new(first_byte: u8, prefix_len: u8) -> Self {
+        debug_assert!(prefix_len < 8, "prefix cannot larger than 7.");
+        let mask = if prefix_len == 0 {
+            0xff
+        } else {
+            (1 << (8 - prefix_len)) - 1
+        };
+        let value = u64::from(first_byte & mask);
+
+        Self {
+            value,
+            cnt: 0,
+            done: value < u64::from(mask),
+        }
+    }
+
+    /// # Panics
+    ///
+    /// Never, but rust doesn't know that.
+    #[must_use]
+    pub fn make(first_byte: u8, prefixes: &[Prefix]) -> Self {
+        for prefix in prefixes {
+            if prefix.cmp_prefix(first_byte) {
+                return Self::new(first_byte, prefix.len());
+            }
+        }
+        unreachable!();
+    }
+
+    /// This function reads bytes until the varint is decoded or until stream/buffer does not
+    /// have any more date.
+    ///
+    /// # Errors
+    ///
+    /// Possible errors are:
+    ///  1) `NeedMoreData` if the reader needs more data,
+    ///  2) `IntegerOverflow`,
+    ///  3) Any `ReadByte`'s error
+    pub fn read<R: ReadByte>(&mut self, s: &mut R) -> Res<u64> {
+        let mut b: u8;
+        while !self.done {
+            b = s.read_byte()?;
+
+            if (self.cnt == 63) && (b > 1 || (b == 1 && ((self.value >> 63) == 1))) {
+                qerror!("Error decoding prefixed encoded int - IntegerOverflow");
+                return Err(Error::IntegerOverflow);
+            }
+            self.value += u64::from(b & 0x7f) << self.cnt;
+            if (b & 0x80) == 0 {
+                self.done = true;
+            }
+            self.cnt += 7;
+            if self.cnt >= 64 {
+                self.done = true;
+            }
+        }
+        Ok(self.value)
+    }
+}
+
+#[derive(Debug)]
+enum LiteralReaderState {
+    ReadHuffman,
+    ReadLength { reader: IntReader },
+    ReadLiteral { offset: usize },
+    Done,
+}
+
+impl Default for LiteralReaderState {
+    fn default() -> Self {
+        Self::ReadHuffman
+    }
+}
+
+/// This is decoder of a literal with a prefix:
+///   1) ignores `prefix_len` bits of the first byte,
+///   2) reads "huffman bit"
+///   3) decode varint that is the length of a literal
+///   4) reads the literal
+///   5) performs huffman decoding if needed.
+#[derive(Debug, Default)]
+pub struct LiteralReader {
+    state: LiteralReaderState,
+    literal: Vec<u8>,
+    use_huffman: bool,
+}
+
+impl LiteralReader {
+    /// Creates `LiteralReader` with the first byte. This constructor is always used
+    /// when a litreral has a prefix.
+    /// For literals without a prefix please use the default constructor.
+    ///
+    /// # Panics
+    ///
+    /// If `prefix_len` is 8 or more.
+    #[must_use]
+    pub fn new_with_first_byte(first_byte: u8, prefix_len: u8) -> Self {
+        assert!(prefix_len < 8);
+        Self {
+            state: LiteralReaderState::ReadLength {
+                reader: IntReader::new(first_byte, prefix_len + 1),
+            },
+            literal: Vec::new(),
+            use_huffman: (first_byte & (0x80 >> prefix_len)) != 0,
+        }
+    }
+
+    /// This function reads bytes until the literal is decoded or until stream/buffer does not
+    /// have any more date ready.
+    ///
+    /// # Errors
+    ///
+    /// Possible errors are:
+    ///  1) `NeedMoreData` if the reader needs more data,
+    ///  2) `IntegerOverflow`
+    ///  3) Any `ReadByte`'s error
+    /// It returns value if reading the literal is done or None if it needs more data.
+    ///
+    /// # Panics
+    ///
+    /// When this object is complete.
+    pub fn read<T: ReadByte + Reader>(&mut self, s: &mut T) -> Res<Vec<u8>> {
+        loop {
+            qdebug!("state = {:?}", self.state);
+            match &mut self.state {
+                LiteralReaderState::ReadHuffman => {
+                    let b = s.read_byte()?;
+
+                    self.use_huffman = (b & 0x80) != 0;
+                    self.state = LiteralReaderState::ReadLength {
+                        reader: IntReader::new(b, 1),
+                    };
+                }
+                LiteralReaderState::ReadLength { reader } => {
+                    let v = reader.read(s)?;
+                    self.literal
+                        .resize(v.try_into().or(Err(Error::Decoding))?, 0x0);
+                    self.state = LiteralReaderState::ReadLiteral { offset: 0 };
+                }
+                LiteralReaderState::ReadLiteral { offset } => {
+                    let amount = s.read(&mut self.literal[*offset..])?;
+                    *offset += amount;
+                    if *offset == self.literal.len() {
+                        self.state = LiteralReaderState::Done;
+                        if self.use_huffman {
+                            break Ok(decode_huffman(&self.literal)?);
+                        }
+                        break Ok(mem::take(&mut self.literal));
+                    }
+                    break Err(Error::NeedMoreData);
+                }
+                LiteralReaderState::Done => {
+                    panic!("Should not call read() in this state.");
+                }
+            }
+        }
+    }
+}
+
+/// This is a helper function used only by `ReceiverBufferWrapper`, therefore it returns
+/// `DecompressionFailed` if any error happens.
+///
+/// # Errors
+///
+/// If an parsing error occurred, the function returns `BadUtf8`.
+pub fn parse_utf8(v: &[u8]) -> Res<&str> {
+    str::from_utf8(v).map_err(|_| Error::BadUtf8)
+}
+
+#[cfg(test)]
+pub(crate) mod test_receiver {
+
+    use std::collections::VecDeque;
+
+    use super::{Error, ReadByte, Reader, Res};
+
+    #[derive(Default)]
+    pub struct TestReceiver {
+        buf: VecDeque<u8>,
+    }
+
+    impl ReadByte for TestReceiver {
+        fn read_byte(&mut self) -> Res<u8> {
+            self.buf.pop_back().ok_or(Error::NeedMoreData)
+        }
+    }
+
+    impl Reader for TestReceiver {
+        fn read(&mut self, buf: &mut [u8]) -> Res<usize> {
+            let len = if buf.len() > self.buf.len() {
+                self.buf.len()
+            } else {
+                buf.len()
+            };
+            for item in buf.iter_mut().take(len) {
+                *item = self.buf.pop_back().ok_or(Error::NeedMoreData)?;
+            }
+            Ok(len)
+        }
+    }
+
+    impl TestReceiver {
+        pub fn write(&mut self, buf: &[u8]) {
+            for b in buf {
+                self.buf.push_front(*b);
+            }
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+
+    use test_receiver::TestReceiver;
+
+    use super::{
+        parse_utf8, str, test_receiver, Error, IntReader, LiteralReader, ReadByte,
+        ReceiverBufferWrapper, Res,
+    };
+
+    const TEST_CASES_NUMBERS: [(&[u8], u8, u64); 7] = [
+        (&[0xEA], 3, 10),
+        (&[0x0A], 3, 10),
+        (&[0x8A], 3, 10),
+        (&[0xFF, 0x9A, 0x0A], 3, 1337),
+        (&[0x1F, 0x9A, 0x0A], 3, 1337),
+        (&[0x9F, 0x9A, 0x0A], 3, 1337),
+        (&[0x2A], 0, 42),
+    ];
+
+    #[test]
+    fn read_prefixed_int() {
+        for (buf, prefix_len, value) in &TEST_CASES_NUMBERS {
+            let mut reader = IntReader::new(buf[0], *prefix_len);
+            let mut test_receiver: TestReceiver = TestReceiver::default();
+            test_receiver.write(&buf[1..]);
+            assert_eq!(reader.read(&mut test_receiver), Ok(*value));
+        }
+    }
+
+    #[test]
+    fn read_prefixed_int_with_more_data_in_buffer() {
+        for (buf, prefix_len, value) in &TEST_CASES_NUMBERS {
+            let mut reader = IntReader::new(buf[0], *prefix_len);
+            let mut test_receiver: TestReceiver = TestReceiver::default();
+            test_receiver.write(&buf[1..]);
+            // add some more data
+            test_receiver.write(&[0x0, 0x0, 0x0]);
+            assert_eq!(reader.read(&mut test_receiver), Ok(*value));
+        }
+    }
+
+    #[test]
+    fn read_prefixed_int_slow_writer() {
+        let (buf, prefix_len, value) = &TEST_CASES_NUMBERS[4];
+        let mut reader = IntReader::new(buf[0], *prefix_len);
+        let mut test_receiver: TestReceiver = TestReceiver::default();
+
+        // data has not been received yet, reading IntReader will return Err(Error::NeedMoreData).
+        assert_eq!(reader.read(&mut test_receiver), Err(Error::NeedMoreData));
+
+        // Write one byte.
+        test_receiver.write(&buf[1..2]);
+        // data has not been received yet, reading IntReader will return Err(Error::NeedMoreData).
+        assert_eq!(reader.read(&mut test_receiver), Err(Error::NeedMoreData));
+
+        // Write one byte.
+        test_receiver.write(&buf[2..]);
+        // Now prefixed int is complete.
+        assert_eq!(reader.read(&mut test_receiver), Ok(*value));
+    }
+
+    type TestSetup = (&'static [u8], u8, Res<u64>);
+    const TEST_CASES_BIG_NUMBERS: [TestSetup; 3] = [
+        (
+            &[
+                0xFF, 0x80, 0xFE, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0x01,
+            ],
+            0,
+            Ok(0xFFFF_FFFF_FFFF_FFFF),
+        ),
+        (
+            &[
+                0xFF, 0x81, 0xFE, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0x01,
+            ],
+            0,
+            Err(Error::IntegerOverflow),
+        ),
+        (
+            &[
+                0xFF, 0x80, 0xFE, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0x02,
+            ],
+            0,
+            Err(Error::IntegerOverflow),
+        ),
+    ];
+
+    #[test]
+    fn read_prefixed_int_big_number() {
+        for (buf, prefix_len, value) in &TEST_CASES_BIG_NUMBERS {
+            let mut reader = IntReader::new(buf[0], *prefix_len);
+            let mut test_receiver: TestReceiver = TestReceiver::default();
+            test_receiver.write(&buf[1..]);
+            assert_eq!(reader.read(&mut test_receiver), *value);
+        }
+    }
+
+    const TEST_CASES_LITERAL: [(&[u8], u8, &str); 9] = [
+        // No Huffman
+        (
+            &[
+                0x0a, 0x63, 0x75, 0x73, 0x74, 0x6f, 0x6d, 0x2d, 0x6b, 0x65, 0x79,
+            ],
+            1,
+            "custom-key",
+        ),
+        (
+            &[
+                0x0a, 0x63, 0x75, 0x73, 0x74, 0x6f, 0x6d, 0x2d, 0x6b, 0x65, 0x79,
+            ],
+            3,
+            "custom-key",
+        ),
+        (
+            &[
+                0xea, 0x63, 0x75, 0x73, 0x74, 0x6f, 0x6d, 0x2d, 0x6b, 0x65, 0x79,
+            ],
+            3,
+            "custom-key",
+        ),
+        (
+            &[
+                0x0d, 0x63, 0x75, 0x73, 0x74, 0x6f, 0x6d, 0x2d, 0x68, 0x65, 0x61, 0x64, 0x65, 0x72,
+            ],
+            1,
+            "custom-header",
+        ),
+        // With Huffman
+        (&[0x15, 0xae, 0xc3, 0x77, 0x1a, 0x4b], 3, "private"),
+        (
+            &[
+                0x56, 0xd0, 0x7a, 0xbe, 0x94, 0x10, 0x54, 0xd4, 0x44, 0xa8, 0x20, 0x05, 0x95, 0x04,
+                0x0b, 0x81, 0x66, 0xe0, 0x82, 0xa6, 0x2d, 0x1b, 0xff,
+            ],
+            1,
+            "Mon, 21 Oct 2013 20:13:21 GMT",
+        ),
+        (
+            &[
+                0xff, 0x0f, 0xd0, 0x7a, 0xbe, 0x94, 0x10, 0x54, 0xd4, 0x44, 0xa8, 0x20, 0x05, 0x95,
+                0x04, 0x0b, 0x81, 0x66, 0xe0, 0x82, 0xa6, 0x2d, 0x1b, 0xff,
+            ],
+            4,
+            "Mon, 21 Oct 2013 20:13:21 GMT",
+        ),
+        (
+            &[
+                0x51, 0x9d, 0x29, 0xad, 0x17, 0x18, 0x63, 0xc7, 0x8f, 0x0b, 0x97, 0xc8, 0xe9, 0xae,
+                0x82, 0xae, 0x43, 0xd3,
+            ],
+            1,
+            "https://www.example.com",
+        ),
+        (
+            &[
+                0x91, 0x9d, 0x29, 0xad, 0x17, 0x18, 0x63, 0xc7, 0x8f, 0x0b, 0x97, 0xc8, 0xe9, 0xae,
+                0x82, 0xae, 0x43, 0xd3,
+            ],
+            0,
+            "https://www.example.com",
+        ),
+    ];
+
+    #[test]
+    fn read_literal() {
+        for (buf, prefix_len, value) in &TEST_CASES_LITERAL {
+            let mut reader = LiteralReader::new_with_first_byte(buf[0], *prefix_len);
+            let mut test_receiver: TestReceiver = TestReceiver::default();
+            test_receiver.write(&buf[1..]);
+            assert_eq!(
+                parse_utf8(&reader.read(&mut test_receiver).unwrap()).unwrap(),
+                *value
+            );
+        }
+    }
+
+    #[test]
+    fn read_prefixed_int_receiver_buffer_wrapper() {
+        for (buf, prefix_len, value) in &TEST_CASES_NUMBERS {
+            let mut buffer = ReceiverBufferWrapper::new(buf);
+            let mut reader = IntReader::new(buffer.read_byte().unwrap(), *prefix_len);
+            assert_eq!(reader.read(&mut buffer), Ok(*value));
+        }
+    }
+
+    #[test]
+    fn read_prefixed_int_big_receiver_buffer_wrapper() {
+        for (buf, prefix_len, value) in &TEST_CASES_BIG_NUMBERS {
+            let mut buffer = ReceiverBufferWrapper::new(buf);
+            let mut reader = IntReader::new(buffer.read_byte().unwrap(), *prefix_len);
+            assert_eq!(reader.read(&mut buffer), *value);
+        }
+    }
+
+    #[test]
+    fn read_literal_receiver_buffer_wrapper() {
+        for (buf, prefix_len, value) in &TEST_CASES_LITERAL {
+            let mut buffer = ReceiverBufferWrapper::new(buf);
+            assert_eq!(
+                buffer.read_literal_from_buffer(*prefix_len).unwrap(),
+                *value
+            );
+        }
+    }
+
+    #[test]
+    fn read_failure_receiver_buffer_wrapper_number() {
+        let (buf, prefix_len, _) = &TEST_CASES_NUMBERS[4];
+        let mut buffer = ReceiverBufferWrapper::new(&buf[..1]);
+        let mut reader = IntReader::new(buffer.read_byte().unwrap(), *prefix_len);
+        assert_eq!(reader.read(&mut buffer), Err(Error::DecompressionFailed));
+    }
+
+    #[test]
+    fn read_failure_receiver_buffer_wrapper_literal() {
+        let (buf, prefix_len, _) = &TEST_CASES_LITERAL[0];
+        let mut buffer = ReceiverBufferWrapper::new(&buf[..6]);
+        assert_eq!(
+            buffer.read_literal_from_buffer(*prefix_len),
+            Err(Error::DecompressionFailed)
+        );
+    }
+}
diff --git a/third_party/rust/neqo-qpack/src/static_table.rs b/third_party/rust/neqo-qpack/src/static_table.rs
new file mode 100644
index 0000000000..4407fbce59
--- /dev/null
+++ b/third_party/rust/neqo-qpack/src/static_table.rs
@@ -0,0 +1,134 @@
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#[derive(Debug)]
+pub struct StaticTableEntry {
+    index: u64,
+    name: &'static [u8],
+    value: &'static [u8],
+}
+
+impl StaticTableEntry {
+    pub fn name(&self) -> &[u8] {
+        self.name
+    }
+
+    pub fn value(&self) -> &[u8] {
+        self.value
+    }
+
+    pub fn index(&self) -> u64 {
+        self.index
+    }
+}
+
+macro_rules! static_table_entries {
+    [$($i:expr, $n:expr, $v:expr);+ $(;)?] => {
+        &[ $(StaticTableEntry { index: $i, name: $n, value: $v }),+ ]
+    };
+}
+
+pub const HEADER_STATIC_TABLE: &[StaticTableEntry] = static_table_entries![
+    0, b":authority", b"";
+    1, b":path", b"/";
+    2, b"age", b"0";
+    3, b"content-disposition", b"";
+    4, b"content-length", b"0";
+    5, b"cookie", b"";
+    6, b"date", b"";
+    7, b"etag", b"";
+    8, b"if-modified-since", b"";
+    9, b"if-none-match", b"";
+    10, b"last-modified", b"";
+    11, b"link", b"";
+    12, b"location", b"";
+    13, b"referer", b"";
+    14, b"set-cookie", b"";
+    15, b":method", b"CONNECT";
+    16, b":method", b"DELETE";
+    17, b":method", b"GET";
+    18, b":method", b"HEAD";
+    19, b":method", b"OPTIONS";
+    20, b":method", b"POST";
+    21, b":method", b"PUT";
+    22, b":scheme", b"http";
+    23, b":scheme", b"https";
+    24, b":status", b"103";
+    25, b":status", b"200";
+    26, b":status", b"304";
+    27, b":status", b"404";
+    28, b":status", b"503";
+    29, b"accept", b"*/*";
+    30, b"accept", b"application/dns-message";
+    31, b"accept-encoding", b"gzip, deflate, br";
+    32, b"accept-ranges", b"bytes";
+    33, b"access-control-allow-headers", b"cache-control";
+    34, b"access-control-allow-headers", b"content-type";
+    35, b"access-control-allow-origin", b"*";
+    36, b"cache-control", b"max-age=0";
+    37, b"cache-control", b"max-age=2592000";
+    38, b"cache-control", b"max-age=604800";
+    39, b"cache-control", b"no-cache";
+    40, b"cache-control", b"no-store";
+    41, b"cache-control", b"public, max-age=31536000";
+    42, b"content-encoding", b"br";
+    43, b"content-encoding", b"gzip";
+    44, b"content-type", b"application/dns-message";
+    45, b"content-type", b"application/javascript";
+    46, b"content-type", b"application/json";
+    47, b"content-type", b"application/x-www-form-urlencoded";
+    48, b"content-type", b"image/gif";
+    49, b"content-type", b"image/jpeg";
+    50, b"content-type", b"image/png";
+    51, b"content-type", b"text/css";
+    52, b"content-type", b"text/html; charset=utf-8";
+    53, b"content-type", b"text/plain";
+    54, b"content-type", b"text/plain;charset=utf-8";
+    55, b"range", b"bytes=0-";
+    56, b"strict-transport-security", b"max-age=31536000";
+    57, b"strict-transport-security", b"max-age=31536000; includesubdomains";
+    58, b"strict-transport-security", b"max-age=31536000; includesubdomains; preload";
+    59, b"vary", b"accept-encoding";
+    60, b"vary", b"origin";
+    61, b"x-content-type-options", b"nosniff";
+    62, b"x-xss-protection", b"1; mode=block";
+    63, b":status", b"100";
+    64, b":status", b"204";
+    65, b":status", b"206";
+    66, b":status", b"302";
+    67, b":status", b"400";
+    68, b":status", b"403";
+    69, b":status", b"421";
+    70, b":status", b"425";
+    71, b":status", b"500";
+    72, b"accept-language", b"";
+    73, b"access-control-allow-credentials", b"FALSE";
+    74, b"access-control-allow-credentials", b"TRUE";
+    75, b"access-control-allow-headers", b"*";
+    76, b"access-control-allow-methods", b"get";
+    77, b"access-control-allow-methods", b"get, post, options";
+    78, b"access-control-allow-methods", b"options";
+    79, b"access-control-expose-headers", b"content-length";
+    80, b"access-control-request-headers", b"content-type";
+    81, b"access-control-request-method", b"get";
+    82, b"access-control-request-method", b"post";
+    83, b"alt-svc", b"clear";
+    84, b"authorization", b"";
+    85, b"content-security-policy", b"script-src 'none'; object-src 'none'; base-uri 'none'";
+    86, b"early-data", b"1";
+    87, b"expect-ct", b"";
+    88, b"forwarded", b"";
+    89, b"if-range", b"";
+    90, b"origin", b"";
+    91, b"purpose", b"prefetch";
+    92, b"server", b"";
+    93, b"timing-allow-origin", b"*";
+    94, b"upgrade-insecure-requests", b"1";
+    95, b"user-agent", b"";
+    96, b"x-forwarded-for", b"";
+    97, b"x-frame-options", b"deny";
+    98, b"x-frame-options", b"sameorigin";
+];
diff --git a/third_party/rust/neqo-qpack/src/stats.rs b/third_party/rust/neqo-qpack/src/stats.rs
new file mode 100644
index 0000000000..7cb334b0c7
--- /dev/null
+++ b/third_party/rust/neqo-qpack/src/stats.rs
@@ -0,0 +1,17 @@
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// Tracking of some useful statistics.
+
+#[derive(Default, Debug, Clone)]
+/// `QPack` statistics
+pub struct Stats {
+    pub dynamic_table_inserts: usize,
+    // This is the munber of header blockes that reference the dynamic table.
+    pub dynamic_table_references: usize,
+    pub stream_cancelled_recv: usize,
+    pub header_acks_recv: usize,
+}
diff --git a/third_party/rust/neqo-qpack/src/table.rs b/third_party/rust/neqo-qpack/src/table.rs
new file mode 100644
index 0000000000..7ce8572542
--- /dev/null
+++ b/third_party/rust/neqo-qpack/src/table.rs
@@ -0,0 +1,391 @@
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use std::{collections::VecDeque, convert::TryFrom};
+
+use neqo_common::qtrace;
+
+use crate::{
+    static_table::{StaticTableEntry, HEADER_STATIC_TABLE},
+    Error, Res,
+};
+
+pub const ADDITIONAL_TABLE_ENTRY_SIZE: usize = 32;
+
+pub struct LookupResult {
+    pub index: u64,
+    pub static_table: bool,
+    pub value_matches: bool,
+}
+
+#[derive(Debug)]
+pub(crate) struct DynamicTableEntry {
+    base: u64,
+    name: Vec<u8>,
+    value: Vec<u8>,
+    /// Number of header blocks that refer this entry.
+    /// This is only used by the encoder.
+    refs: u64,
+}
+
+impl DynamicTableEntry {
+    pub fn can_reduce(&self, first_not_acked: u64) -> bool {
+        self.refs == 0 && self.base < first_not_acked
+    }
+
+    pub fn size(&self) -> usize {
+        self.name.len() + self.value.len() + ADDITIONAL_TABLE_ENTRY_SIZE
+    }
+
+    pub fn add_ref(&mut self) {
+        self.refs += 1;
+    }
+
+    pub fn remove_ref(&mut self) {
+        assert!(self.refs > 0);
+        self.refs -= 1;
+    }
+
+    pub fn name(&self) -> &[u8] {
+        &self.name
+    }
+
+    pub fn value(&self) -> &[u8] {
+        &self.value
+    }
+
+    pub fn index(&self) -> u64 {
+        self.base
+    }
+}
+
+#[derive(Debug)]
+pub(crate) struct HeaderTable {
+    dynamic: VecDeque<DynamicTableEntry>,
+    /// The total capacity (in QPACK bytes) of the table. This is set by
+    /// configuration.
+    capacity: u64,
+    /// The amount of used capacity.
+    used: u64,
+    /// The total number of inserts thus far.
+    base: u64,
+    /// This is number of inserts that are acked. this correspond to index of the first not acked.
+    /// This is only used by thee encoder.
+    acked_inserts_cnt: u64,
+}
+
+impl ::std::fmt::Display for HeaderTable {
+    fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
+        write!(
+            f,
+            "HeaderTable for (base={} acked_inserts_cnt={} capacity={})",
+            self.base, self.acked_inserts_cnt, self.capacity
+        )
+    }
+}
+
+impl HeaderTable {
+    pub fn new(encoder: bool) -> Self {
+        Self {
+            dynamic: VecDeque::new(),
+            capacity: 0,
+            used: 0,
+            base: 0,
+            acked_inserts_cnt: if encoder { 0 } else { u64::max_value() },
+        }
+    }
+
+    /// Returns number of inserts.
+    pub fn base(&self) -> u64 {
+        self.base
+    }
+
+    /// Returns capacity of the dynamic table
+    pub fn capacity(&self) -> u64 {
+        self.capacity
+    }
+
+    /// Change the dynamic table capacity.
+    ///
+    /// # Errors
+    ///
+    /// `ChangeCapacity` if table capacity cannot be reduced.
+    /// The table cannot be reduce if there are entries that are referred at the moment or their
+    /// inserts are unacked.
+    pub fn set_capacity(&mut self, cap: u64) -> Res<()> {
+        qtrace!([self], "set capacity to {}", cap);
+        if !self.evict_to(cap) {
+            return Err(Error::ChangeCapacity);
+        }
+        self.capacity = cap;
+        Ok(())
+    }
+
+    /// Get a static entry with `index`.
+    ///
+    /// # Errors
+    ///
+    /// `HeaderLookup` if the index does not exist in the static table.
+    pub fn get_static(index: u64) -> Res<&'static StaticTableEntry> {
+        let inx = usize::try_from(index).or(Err(Error::HeaderLookup))?;
+        if inx > HEADER_STATIC_TABLE.len() {
+            return Err(Error::HeaderLookup);
+        }
+        Ok(&HEADER_STATIC_TABLE[inx])
+    }
+
+    fn get_dynamic_with_abs_index(&mut self, index: u64) -> Res<&mut DynamicTableEntry> {
+        if self.base <= index {
+            debug_assert!(false, "This is an internal error");
+            return Err(Error::HeaderLookup);
+        }
+        let inx = self.base - index - 1;
+        let inx = usize::try_from(inx).or(Err(Error::HeaderLookup))?;
+        if inx >= self.dynamic.len() {
+            return Err(Error::HeaderLookup);
+        }
+        Ok(&mut self.dynamic[inx])
+    }
+
+    fn get_dynamic_with_relative_index(&self, index: u64) -> Res<&DynamicTableEntry> {
+        let inx = usize::try_from(index).or(Err(Error::HeaderLookup))?;
+        if inx >= self.dynamic.len() {
+            return Err(Error::HeaderLookup);
+        }
+        Ok(&self.dynamic[inx])
+    }
+
+    /// Get a entry in the  dynamic table.
+    ///
+    /// # Errors
+    ///
+    /// `HeaderLookup` if entry does not exist.
+    pub fn get_dynamic(&self, index: u64, base: u64, post: bool) -> Res<&DynamicTableEntry> {
+        let inx = if post {
+            if self.base < (base + index + 1) {
+                return Err(Error::HeaderLookup);
+            }
+            self.base - (base + index + 1)
+        } else {
+            if (self.base + index) < base {
+                return Err(Error::HeaderLookup);
+            }
+            (self.base + index) - base
+        };
+
+        self.get_dynamic_with_relative_index(inx)
+    }
+
+    /// Remove a reference to a dynamic table entry.
+    pub fn remove_ref(&mut self, index: u64) {
+        qtrace!([self], "remove reference to entry {}", index);
+        self.get_dynamic_with_abs_index(index)
+            .expect("we should have the entry")
+            .remove_ref();
+    }
+
+    /// Add a reference to a dynamic table entry.
+    pub fn add_ref(&mut self, index: u64) {
+        qtrace!([self], "add reference to entry {}", index);
+        self.get_dynamic_with_abs_index(index)
+            .expect("we should have the entry")
+            .add_ref();
+    }
+
+    /// Look for a header pair.
+    /// The function returns `LookupResult`: `index`, `static_table` (if it is a static table entry)
+    /// and `value_matches` (if the header value matches as well not only header name)
+    pub fn lookup(&mut self, name: &[u8], value: &[u8], can_block: bool) -> Option<LookupResult> {
+        qtrace!(
+            [self],
+            "lookup name:{:?} value {:?} can_block={}",
+            name,
+            value,
+            can_block
+        );
+        let mut name_match = None;
+        for iter in HEADER_STATIC_TABLE {
+            if iter.name() == name {
+                if iter.value() == value {
+                    return Some(LookupResult {
+                        index: iter.index(),
+                        static_table: true,
+                        value_matches: true,
+                    });
+                }
+
+                if name_match.is_none() {
+                    name_match = Some(LookupResult {
+                        index: iter.index(),
+                        static_table: true,
+                        value_matches: false,
+                    });
+                }
+            }
+        }
+
+        for iter in &mut self.dynamic {
+            if !can_block && iter.index() >= self.acked_inserts_cnt {
+                continue;
+            }
+            if iter.name == name {
+                if iter.value == value {
+                    return Some(LookupResult {
+                        index: iter.index(),
+                        static_table: false,
+                        value_matches: true,
+                    });
+                }
+
+                if name_match.is_none() {
+                    name_match = Some(LookupResult {
+                        index: iter.index(),
+                        static_table: false,
+                        value_matches: false,
+                    });
+                }
+            }
+        }
+        name_match
+    }
+
+    fn evict_to(&mut self, reduce: u64) -> bool {
+        self.evict_to_internal(reduce, false)
+    }
+
+    pub fn can_evict_to(&mut self, reduce: u64) -> bool {
+        self.evict_to_internal(reduce, true)
+    }
+
+    pub fn evict_to_internal(&mut self, reduce: u64, only_check: bool) -> bool {
+        qtrace!(
+            [self],
+            "reduce table to {}, currently used:{} only_check:{}",
+            reduce,
+            self.used,
+            only_check
+        );
+        let mut used = self.used;
+        while (!self.dynamic.is_empty()) && used > reduce {
+            if let Some(e) = self.dynamic.back() {
+                if !e.can_reduce(self.acked_inserts_cnt) {
+                    return false;
+                }
+                used -= u64::try_from(e.size()).unwrap();
+                if !only_check {
+                    self.used -= u64::try_from(e.size()).unwrap();
+                    self.dynamic.pop_back();
+                }
+            }
+        }
+        true
+    }
+
+    pub fn insert_possible(&mut self, size: usize) -> bool {
+        u64::try_from(size).unwrap() <= self.capacity
+            && self.can_evict_to(self.capacity - u64::try_from(size).unwrap())
+    }
+
+    /// Insert a new entry.
+    ///
+    /// # Errors
+    ///
+    /// `DynamicTableFull` if an entry cannot be added to the table because there is not enough
+    /// space and/or other entry cannot be evicted.
+    pub fn insert(&mut self, name: &[u8], value: &[u8]) -> Res<u64> {
+        qtrace!([self], "insert name={:?} value={:?}", name, value);
+        let entry = DynamicTableEntry {
+            name: name.to_vec(),
+            value: value.to_vec(),
+            base: self.base,
+            refs: 0,
+        };
+        if u64::try_from(entry.size()).unwrap() > self.capacity
+            || !self.evict_to(self.capacity - u64::try_from(entry.size()).unwrap())
+        {
+            return Err(Error::DynamicTableFull);
+        }
+        self.base += 1;
+        self.used += u64::try_from(entry.size()).unwrap();
+        let index = entry.index();
+        self.dynamic.push_front(entry);
+        Ok(index)
+    }
+
+    /// Insert a new entry with the name refer to by a index to static or dynamic table.
+    ///
+    /// # Errors
+    ///
+    /// `DynamicTableFull` if an entry cannot be added to the table because there is not enough
+    /// space and/or other entry cannot be evicted.
+    /// `HeaderLookup` if the index dos not exits in the static/dynamic table.
+    pub fn insert_with_name_ref(
+        &mut self,
+        name_static_table: bool,
+        name_index: u64,
+        value: &[u8],
+    ) -> Res<u64> {
+        qtrace!(
+            [self],
+            "insert with ref to index={} in {} value={:?}",
+            name_index,
+            if name_static_table {
+                "static"
+            } else {
+                "dynamic"
+            },
+            value
+        );
+        let name = if name_static_table {
+            HeaderTable::get_static(name_index)?.name().to_vec()
+        } else {
+            self.get_dynamic(name_index, self.base, false)?
+                .name()
+                .to_vec()
+        };
+        self.insert(&name, value)
+    }
+
+    /// Duplicate an entry.
+    ///
+    /// # Errors
+    ///
+    /// `DynamicTableFull` if an entry cannot be added to the table because there is not enough
+    /// space and/or other entry cannot be evicted.
+    /// `HeaderLookup` if the index dos not exits in the static/dynamic table.
+    pub fn duplicate(&mut self, index: u64) -> Res<u64> {
+        qtrace!([self], "duplicate entry={}", index);
+        // need to remember name and value because insert may delete the entry.
+        let name: Vec<u8>;
+        let value: Vec<u8>;
+        {
+            let entry = self.get_dynamic(index, self.base, false)?;
+            name = entry.name().to_vec();
+            value = entry.value().to_vec();
+            qtrace!([self], "dumplicate name={:?} value={:?}", name, value);
+        }
+        self.insert(&name, &value)
+    }
+
+    /// Increment number of acknowledge entries.
+    ///
+    /// # Errors
+    ///
+    /// `IncrementAck` if ack is greater than actual number of inserts.
+    pub fn increment_acked(&mut self, increment: u64) -> Res<()> {
+        qtrace!([self], "increment acked by {}", increment);
+        self.acked_inserts_cnt += increment;
+        if self.base < self.acked_inserts_cnt {
+            return Err(Error::IncrementAck);
+        }
+        Ok(())
+    }
+
+    /// Return number of acknowledge inserts.
+    pub fn get_acked_inserts_cnt(&self) -> u64 {
+        self.acked_inserts_cnt
+    }
+}