Adding upstream version 110.0.1.upstream/110.0.1upstream

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

22 files changed, 4900 insertions, 0 deletions

diff --git a/netwerk/socket/moz.build b/netwerk/socket/moz.build
new file mode 100644
index 0000000000..d8ce8d0b2b
--- /dev/null
+++ b/netwerk/socket/moz.build
@@ -0,0 +1,46 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+DIRS += [
+    "neqo_glue",
+]
+
+XPIDL_SOURCES += [
+    "nsISocketProvider.idl",
+    "nsISocketProviderService.idl",
+]
+
+XPIDL_MODULE = "necko_socket"
+
+LOCAL_INCLUDES += [
+    "/netwerk/base",
+]
+
+include("/ipc/chromium/chromium-config.mozbuild")
+
+EXPORTS += [
+    "nsSocketProviderService.h",
+]
+
+UNIFIED_SOURCES += [
+    "nsSocketProviderService.cpp",
+    "nsSOCKSIOLayer.cpp",
+    "nsSOCKSSocketProvider.cpp",
+    "nsUDPSocketProvider.cpp",
+]
+
+if CONFIG["MOZ_WIDGET_TOOLKIT"] == "windows":
+    XPIDL_SOURCES += [
+        "nsINamedPipeService.idl",
+    ]
+    EXPORTS += [
+        "nsNamedPipeService.h",
+    ]
+    UNIFIED_SOURCES += ["nsNamedPipeIOLayer.cpp", "nsNamedPipeService.cpp"]
+
+FINAL_LIBRARY = "xul"
+
+CONFIGURE_SUBST_FILES += ["neqo/extra-bindgen-flags"]
diff --git a/netwerk/socket/neqo/extra-bindgen-flags.in b/netwerk/socket/neqo/extra-bindgen-flags.in
new file mode 100644
index 0000000000..69f7dabf26
--- /dev/null
+++ b/netwerk/socket/neqo/extra-bindgen-flags.in
@@ -0,0 +1 @@
+@BINDGEN_SYSTEM_FLAGS@ @NSPR_CFLAGS@ @NSS_CFLAGS@
diff --git a/netwerk/socket/neqo_glue/Cargo.toml b/netwerk/socket/neqo_glue/Cargo.toml
new file mode 100644
index 0000000000..ed4cce53fb
--- /dev/null
+++ b/netwerk/socket/neqo_glue/Cargo.toml
@@ -0,0 +1,35 @@
+[package]
+name = "neqo_glue"
+version = "0.1.0"
+authors = ["Dragana Damjanovic <dd.mozilla@gmail.com>"]
+edition = "2018"
+license = "MPL-2.0"
+
+[lib]
+name = "neqo_glue"
+
+[dependencies]
+neqo-http3 = { tag = "v0.6.3", git = "https://github.com/mozilla/neqo" }
+neqo-transport = { tag = "v0.6.3", git = "https://github.com/mozilla/neqo" }
+neqo-common = { tag = "v0.6.3", git = "https://github.com/mozilla/neqo" }
+neqo-qpack = { tag = "v0.6.3", git = "https://github.com/mozilla/neqo" }
+nserror = { path = "../../../xpcom/rust/nserror" }
+nsstring = { path = "../../../xpcom/rust/nsstring" }
+xpcom = { path = "../../../xpcom/rust/xpcom" }
+thin-vec = { version = "0.2.1", features = ["gecko-ffi"] }
+log = "0.4.0"
+qlog = "0.4.0"
+libc = "0.2.0"
+static_prefs = { path = "../../../modules/libpref/init/static_prefs", optional = true }
+
+[target.'cfg(target_os = "windows")'.dependencies]
+winapi = {version = "0.3", features = ["ws2def"] }
+
+[dependencies.neqo-crypto]
+tag = "v0.6.3"
+git = "https://github.com/mozilla/neqo"
+default-features = false
+features = ["gecko"]
+
+[features]
+fuzzing = ["neqo-http3/fuzzing", "static_prefs"]
diff --git a/netwerk/socket/neqo_glue/NeqoHttp3Conn.h b/netwerk/socket/neqo_glue/NeqoHttp3Conn.h
new file mode 100644
index 0000000000..6ea47e7830
--- /dev/null
+++ b/netwerk/socket/neqo_glue/NeqoHttp3Conn.h
@@ -0,0 +1,162 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef NeqoHttp3Conn_h__
+#define NeqoHttp3Conn_h__
+
+#include <cstdint>
+#include "mozilla/net/neqo_glue_ffi_generated.h"
+
+namespace mozilla {
+namespace net {
+
+class NeqoHttp3Conn final {
+ public:
+  static nsresult Init(const nsACString& aOrigin, const nsACString& aAlpn,
+                       const NetAddr& aLocalAddr, const NetAddr& aRemoteAddr,
+                       uint32_t aMaxTableSize, uint16_t aMaxBlockedStreams,
+                       uint64_t aMaxData, uint64_t aMaxStreamData,
+                       bool aVersionNegotiation, bool aWebTransport,
+                       const nsACString& aQlogDir, uint32_t aDatagramSize,
+                       NeqoHttp3Conn** aConn) {
+    return neqo_http3conn_new(&aOrigin, &aAlpn, &aLocalAddr, &aRemoteAddr,
+                              aMaxTableSize, aMaxBlockedStreams, aMaxData,
+                              aMaxStreamData, aVersionNegotiation,
+                              aWebTransport, &aQlogDir, aDatagramSize,
+                              (const mozilla::net::NeqoHttp3Conn**)aConn);
+  }
+
+  void Close(uint64_t aError) { neqo_http3conn_close(this, aError); }
+
+  nsresult GetSecInfo(NeqoSecretInfo* aSecInfo) {
+    return neqo_http3conn_tls_info(this, aSecInfo);
+  }
+
+  nsresult PeerCertificateInfo(NeqoCertificateInfo* aCertInfo) {
+    return neqo_http3conn_peer_certificate_info(this, aCertInfo);
+  }
+
+  void PeerAuthenticated(PRErrorCode aError) {
+    neqo_http3conn_authenticated(this, aError);
+  }
+
+  nsresult ProcessInput(const NetAddr& aRemoteAddr,
+                        const nsTArray<uint8_t>& aPacket) {
+    return neqo_http3conn_process_input(this, &aRemoteAddr, &aPacket);
+  }
+
+  bool ProcessOutput(nsACString* aRemoteAddr, uint16_t* aPort,
+                     nsTArray<uint8_t>& aData, uint64_t* aTimeout) {
+    aData.TruncateLength(0);
+    return neqo_http3conn_process_output(this, aRemoteAddr, aPort, &aData,
+                                         aTimeout);
+  }
+
+  nsresult GetEvent(Http3Event* aEvent, nsTArray<uint8_t>& aData) {
+    return neqo_http3conn_event(this, aEvent, &aData);
+  }
+
+  nsresult Fetch(const nsACString& aMethod, const nsACString& aScheme,
+                 const nsACString& aHost, const nsACString& aPath,
+                 const nsACString& aHeaders, uint64_t* aStreamId,
+                 uint8_t aUrgency, bool aIncremental) {
+    return neqo_http3conn_fetch(this, &aMethod, &aScheme, &aHost, &aPath,
+                                &aHeaders, aStreamId, aUrgency, aIncremental);
+  }
+
+  nsresult PriorityUpdate(uint64_t aStreamId, uint8_t aUrgency,
+                          bool aIncremental) {
+    return neqo_http3conn_priority_update(this, aStreamId, aUrgency,
+                                          aIncremental);
+  }
+
+  nsresult SendRequestBody(uint64_t aStreamId, const uint8_t* aBuf,
+                           uint32_t aCount, uint32_t* aCountRead) {
+    return neqo_htttp3conn_send_request_body(this, aStreamId, aBuf, aCount,
+                                             aCountRead);
+  }
+
+  // This closes only the sending side of a stream.
+  nsresult CloseStream(uint64_t aStreamId) {
+    return neqo_http3conn_close_stream(this, aStreamId);
+  }
+
+  nsresult ReadResponseData(uint64_t aStreamId, uint8_t* aBuf, uint32_t aLen,
+                            uint32_t* aRead, bool* aFin) {
+    return neqo_http3conn_read_response_data(this, aStreamId, aBuf, aLen, aRead,
+                                             aFin);
+  }
+
+  void CancelFetch(uint64_t aStreamId, uint64_t aError) {
+    neqo_http3conn_cancel_fetch(this, aStreamId, aError);
+  }
+
+  void ResetStream(uint64_t aStreamId, uint64_t aError) {
+    neqo_http3conn_reset_stream(this, aStreamId, aError);
+  }
+
+  void StreamStopSending(uint64_t aStreamId, uint64_t aError) {
+    neqo_http3conn_stream_stop_sending(this, aStreamId, aError);
+  }
+
+  void SetResumptionToken(nsTArray<uint8_t>& aToken) {
+    neqo_http3conn_set_resumption_token(this, &aToken);
+  }
+
+  void SetEchConfig(nsTArray<uint8_t>& aEchConfig) {
+    neqo_http3conn_set_ech_config(this, &aEchConfig);
+  }
+
+  bool IsZeroRtt() { return neqo_http3conn_is_zero_rtt(this); }
+
+  void AddRef() { neqo_http3conn_addref(this); }
+  void Release() { neqo_http3conn_release(this); }
+
+  void GetStats(Http3Stats* aStats) {
+    return neqo_http3conn_get_stats(this, aStats);
+  }
+
+  nsresult CreateWebTransport(const nsACString& aHost, const nsACString& aPath,
+                              const nsACString& aHeaders,
+                              uint64_t* aSessionId) {
+    return neqo_http3conn_webtransport_create_session(this, &aHost, &aPath,
+                                                      &aHeaders, aSessionId);
+  }
+
+  nsresult CloseWebTransport(uint64_t aSessionId, uint32_t aError,
+                             const nsACString& aMessage) {
+    return neqo_http3conn_webtransport_close_session(this, aSessionId, aError,
+                                                     &aMessage);
+  }
+
+  nsresult CreateWebTransportStream(uint64_t aSessionId,
+                                    WebTransportStreamType aStreamType,
+                                    uint64_t* aStreamId) {
+    return neqo_http3conn_webtransport_create_stream(this, aSessionId,
+                                                     aStreamType, aStreamId);
+  }
+
+  nsresult WebTransportSendDatagram(uint64_t aSessionId,
+                                    nsTArray<uint8_t>& aData,
+                                    uint64_t aTrackingId) {
+    return neqo_http3conn_webtransport_send_datagram(this, aSessionId, &aData,
+                                                     aTrackingId);
+  }
+
+  nsresult WebTransportMaxDatagramSize(uint64_t aSessionId, uint64_t* aResult) {
+    return neqo_http3conn_webtransport_max_datagram_size(this, aSessionId,
+                                                         aResult);
+  }
+
+ private:
+  NeqoHttp3Conn() = delete;
+  ~NeqoHttp3Conn() = delete;
+  NeqoHttp3Conn(const NeqoHttp3Conn&) = delete;
+  NeqoHttp3Conn& operator=(const NeqoHttp3Conn&) = delete;
+};
+
+}  // namespace net
+}  // namespace mozilla
+
+#endif
diff --git a/netwerk/socket/neqo_glue/cbindgen.toml b/netwerk/socket/neqo_glue/cbindgen.toml
new file mode 100644
index 0000000000..312e1731e5
--- /dev/null
+++ b/netwerk/socket/neqo_glue/cbindgen.toml
@@ -0,0 +1,27 @@
+header = """/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */"""
+autogen_warning = """/* DO NOT MODIFY THIS MANUALLY! This file was generated using cbindgen.
+ */
+
+namespace mozilla {
+namespace net {
+class NeqoHttp3Conn;
+union NetAddr;
+}  // namespace net
+}  // namespace mozilla
+ """
+include_version = true
+braces = "SameLine"
+line_length = 100
+tab_width = 2
+language = "C++"
+namespaces = ["mozilla", "net"]
+includes = ["certt.h", "prerror.h"]
+
+[export]
+exclude = ["NeqoHttp3Conn", "NetAddr"]
+item_types = ["globals", "enums", "structs", "unions", "typedefs", "opaque", "functions", "constants"]
+
+[export.rename]
+"ThinVec" = "nsTArray"
diff --git a/netwerk/socket/neqo_glue/moz.build b/netwerk/socket/neqo_glue/moz.build
new file mode 100644
index 0000000000..b3123dde4f
--- /dev/null
+++ b/netwerk/socket/neqo_glue/moz.build
@@ -0,0 +1,21 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+EXPORTS.mozilla.net += [
+    "NeqoHttp3Conn.h",
+]
+
+LOCAL_INCLUDES += [
+    "/security/manager/ssl",
+    "/security/nss/lib/ssl",
+]
+
+if CONFIG["COMPILE_ENVIRONMENT"]:
+    CbindgenHeader("neqo_glue_ffi_generated.h", inputs=["/netwerk/socket/neqo_glue"])
+
+    EXPORTS.mozilla.net += [
+        "!neqo_glue_ffi_generated.h",
+    ]
diff --git a/netwerk/socket/neqo_glue/src/lib.rs b/netwerk/socket/neqo_glue/src/lib.rs
new file mode 100644
index 0000000000..b509f015e9
--- /dev/null
+++ b/netwerk/socket/neqo_glue/src/lib.rs
@@ -0,0 +1,1321 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+#[cfg(not(windows))]
+use libc::{AF_INET, AF_INET6};
+use neqo_common::event::Provider;
+use neqo_common::{self as common, qlog::NeqoQlog, qwarn, Datagram, Header, Role};
+use neqo_crypto::{init, PRErrorCode};
+use neqo_http3::{
+    features::extended_connect::SessionCloseReason, Error as Http3Error, Http3Client,
+    Http3ClientEvent, Http3Parameters, Http3State, Priority, WebTransportEvent,
+};
+use neqo_transport::{
+    stream_id::StreamType, CongestionControlAlgorithm, ConnectionParameters,
+    Error as TransportError, Output, RandomConnectionIdGenerator, StreamId, Version,
+};
+use nserror::*;
+use nsstring::*;
+use qlog::QlogStreamer;
+use std::borrow::Cow;
+use std::cell::RefCell;
+use std::convert::TryFrom;
+use std::convert::TryInto;
+use std::fs::OpenOptions;
+use std::net::SocketAddr;
+use std::net::{IpAddr, Ipv4Addr, Ipv6Addr};
+use std::path::PathBuf;
+use std::ptr;
+use std::rc::Rc;
+use std::slice;
+use std::str;
+#[cfg(feature = "fuzzing")]
+use std::time::Duration;
+use std::time::Instant;
+use thin_vec::ThinVec;
+#[cfg(windows)]
+use winapi::shared::ws2def::{AF_INET, AF_INET6};
+use xpcom::{AtomicRefcnt, RefCounted, RefPtr};
+
+#[repr(C)]
+pub struct NeqoHttp3Conn {
+    conn: Http3Client,
+    local_addr: SocketAddr,
+    refcnt: AtomicRefcnt,
+}
+
+// Opaque interface to mozilla::net::NetAddr defined in DNS.h
+#[repr(C)]
+pub union NetAddr {
+    private: [u8; 0],
+}
+
+extern "C" {
+    pub fn moz_netaddr_get_family(arg: *const NetAddr) -> u16;
+    pub fn moz_netaddr_get_network_order_ip(arg: *const NetAddr) -> u32;
+    pub fn moz_netaddr_get_ipv6(arg: *const NetAddr) -> *const u8;
+    pub fn moz_netaddr_get_network_order_port(arg: *const NetAddr) -> u16;
+}
+
+fn netaddr_to_socket_addr(arg: *const NetAddr) -> Result<SocketAddr, nsresult> {
+    if arg == ptr::null() {
+        return Err(NS_ERROR_INVALID_ARG);
+    }
+
+    unsafe {
+        let family = moz_netaddr_get_family(arg) as i32;
+        if family == AF_INET {
+            let port = u16::from_be(moz_netaddr_get_network_order_port(arg));
+            let ipv4 = Ipv4Addr::from(u32::from_be(moz_netaddr_get_network_order_ip(arg)));
+            return Ok(SocketAddr::new(IpAddr::V4(ipv4), port));
+        }
+
+        if family == AF_INET6 {
+            let port = u16::from_be(moz_netaddr_get_network_order_port(arg));
+            let ipv6_slice: [u8; 16] = slice::from_raw_parts(moz_netaddr_get_ipv6(arg), 16)
+                .try_into()
+                .expect("slice with incorrect length");
+            let ipv6 = Ipv6Addr::from(ipv6_slice);
+            return Ok(SocketAddr::new(IpAddr::V6(ipv6), port));
+        }
+    }
+
+    Err(NS_ERROR_UNEXPECTED)
+}
+
+impl NeqoHttp3Conn {
+    fn new(
+        origin: &nsACString,
+        alpn: &nsACString,
+        local_addr: *const NetAddr,
+        remote_addr: *const NetAddr,
+        max_table_size: u64,
+        max_blocked_streams: u16,
+        max_data: u64,
+        max_stream_data: u64,
+        version_negotiation: bool,
+        webtransport: bool,
+        qlog_dir: &nsACString,
+        webtransport_datagram_size: u32,
+    ) -> Result<RefPtr<NeqoHttp3Conn>, nsresult> {
+        // Nss init.
+        init();
+
+        let origin_conv = str::from_utf8(origin).map_err(|_| NS_ERROR_INVALID_ARG)?;
+
+        let alpn_conv = str::from_utf8(alpn).map_err(|_| NS_ERROR_INVALID_ARG)?;
+
+        let local: SocketAddr = netaddr_to_socket_addr(local_addr)?;
+
+        let remote: SocketAddr = netaddr_to_socket_addr(remote_addr)?;
+
+        let quic_version = match alpn_conv {
+            "h3-32" => Version::Draft32,
+            "h3-31" => Version::Draft31,
+            "h3-30" => Version::Draft30,
+            "h3-29" => Version::Draft29,
+            "h3" => Version::Version1,
+            _ => return Err(NS_ERROR_INVALID_ARG),
+        };
+
+        let version_list = if version_negotiation {
+            Version::all()
+        } else {
+            vec![quic_version]
+        };
+        #[allow(unused_mut)]
+        let mut params = ConnectionParameters::default()
+            .versions(quic_version, version_list)
+            .cc_algorithm(CongestionControlAlgorithm::Cubic)
+            .max_data(max_data)
+            .max_stream_data(StreamType::BiDi, false, max_stream_data);
+
+        // Set a short timeout when fuzzing.
+        #[cfg(feature = "fuzzing")]
+        if static_prefs::pref!("fuzzing.necko.http3") {
+            params = params.idle_timeout(Duration::from_millis(10));
+        }
+
+        if webtransport_datagram_size > 0 {
+            params = params.datagram_size(webtransport_datagram_size.into());
+        }
+
+        let http3_settings = Http3Parameters::default()
+            .max_table_size_encoder(max_table_size)
+            .max_table_size_decoder(max_table_size)
+            .max_blocked_streams(max_blocked_streams)
+            .max_concurrent_push_streams(0)
+            .connection_parameters(params)
+            .webtransport(webtransport);
+
+        let mut conn = match Http3Client::new(
+            origin_conv,
+            Rc::new(RefCell::new(RandomConnectionIdGenerator::new(3))),
+            local,
+            remote,
+            http3_settings,
+            Instant::now(),
+        ) {
+            Ok(c) => c,
+            Err(_) => return Err(NS_ERROR_INVALID_ARG),
+        };
+
+        if !qlog_dir.is_empty() {
+            let qlog_dir_conv = str::from_utf8(qlog_dir).map_err(|_| NS_ERROR_INVALID_ARG)?;
+            let mut qlog_path = PathBuf::from(qlog_dir_conv);
+            qlog_path.push(format!("{}.qlog", origin));
+
+            // Emit warnings but to not return an error if qlog initialization
+            // fails.
+            match OpenOptions::new()
+                .write(true)
+                .create(true)
+                .truncate(true)
+                .open(&qlog_path)
+            {
+                Err(_) => qwarn!("Could not open qlog path: {}", qlog_path.display()),
+                Ok(f) => {
+                    let streamer = QlogStreamer::new(
+                        qlog::QLOG_VERSION.to_string(),
+                        Some("Firefox Client qlog".to_string()),
+                        Some("Firefox Client qlog".to_string()),
+                        None,
+                        std::time::Instant::now(),
+                        common::qlog::new_trace(Role::Client),
+                        Box::new(f),
+                    );
+
+                    match NeqoQlog::enabled(streamer, &qlog_path) {
+                        Err(_) => qwarn!("Could not write to qlog path: {}", qlog_path.display()),
+                        Ok(nq) => conn.set_qlog(nq),
+                    }
+                }
+            }
+        }
+
+        let conn = Box::into_raw(Box::new(NeqoHttp3Conn {
+            conn,
+            local_addr: local,
+            refcnt: unsafe { AtomicRefcnt::new() },
+        }));
+        unsafe { Ok(RefPtr::from_raw(conn).unwrap()) }
+    }
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn neqo_http3conn_addref(conn: &NeqoHttp3Conn) {
+    conn.refcnt.inc();
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn neqo_http3conn_release(conn: &NeqoHttp3Conn) {
+    let rc = conn.refcnt.dec();
+    if rc == 0 {
+        std::mem::drop(Box::from_raw(conn as *const _ as *mut NeqoHttp3Conn));
+    }
+}
+
+// xpcom::RefPtr support
+unsafe impl RefCounted for NeqoHttp3Conn {
+    unsafe fn addref(&self) {
+        neqo_http3conn_addref(self);
+    }
+    unsafe fn release(&self) {
+        neqo_http3conn_release(self);
+    }
+}
+
+// Allocate a new NeqoHttp3Conn object.
+#[no_mangle]
+pub extern "C" fn neqo_http3conn_new(
+    origin: &nsACString,
+    alpn: &nsACString,
+    local_addr: *const NetAddr,
+    remote_addr: *const NetAddr,
+    max_table_size: u64,
+    max_blocked_streams: u16,
+    max_data: u64,
+    max_stream_data: u64,
+    version_negotiation: bool,
+    webtransport: bool,
+    qlog_dir: &nsACString,
+    webtransport_datagram_size: u32,
+    result: &mut *const NeqoHttp3Conn,
+) -> nsresult {
+    *result = ptr::null_mut();
+
+    match NeqoHttp3Conn::new(
+        origin,
+        alpn,
+        local_addr,
+        remote_addr,
+        max_table_size,
+        max_blocked_streams,
+        max_data,
+        max_stream_data,
+        version_negotiation,
+        webtransport,
+        qlog_dir,
+        webtransport_datagram_size,
+    ) {
+        Ok(http3_conn) => {
+            http3_conn.forget(result);
+            NS_OK
+        }
+        Err(e) => e,
+    }
+}
+
+/* Process a packet.
+ * packet holds packet data.
+ */
+#[no_mangle]
+pub unsafe extern "C" fn neqo_http3conn_process_input(
+    conn: &mut NeqoHttp3Conn,
+    remote_addr: *const NetAddr,
+    packet: *const ThinVec<u8>,
+) -> nsresult {
+    let remote = match netaddr_to_socket_addr(remote_addr) {
+        Ok(addr) => addr,
+        Err(result) => return result,
+    };
+    conn.conn.process_input(
+        Datagram::new(remote, conn.local_addr, (*packet).to_vec()),
+        Instant::now(),
+    );
+    return NS_OK;
+}
+
+/* Process output:
+ * this may return a packet that needs to be sent or a timeout.
+ * if it returns a packet the function returns true, otherwise it returns false.
+ */
+#[no_mangle]
+pub extern "C" fn neqo_http3conn_process_output(
+    conn: &mut NeqoHttp3Conn,
+    remote_addr: &mut nsACString,
+    remote_port: &mut u16,
+    packet: &mut ThinVec<u8>,
+    timeout: &mut u64,
+) -> bool {
+    match conn.conn.process_output(Instant::now()) {
+        Output::Datagram(dg) => {
+            packet.extend_from_slice(&dg);
+            remote_addr.append(&dg.destination().ip().to_string());
+            *remote_port = dg.destination().port();
+            true
+        }
+        Output::Callback(to) => {
+            *timeout = to.as_millis() as u64;
+            // Necko resolution is in milliseconds whereas neqo resolution
+            // is in nanoseconds. If we called process_output too soon due
+            // to this difference, we might do few unnecessary loops until
+            // we waste the remaining time. To avoid it, we return 1ms when
+            // the timeout is less than 1ms.
+            if *timeout == 0 {
+                *timeout = 1;
+            }
+            false
+        }
+        Output::None => {
+            *timeout = std::u64::MAX;
+            false
+        }
+    }
+}
+
+#[no_mangle]
+pub extern "C" fn neqo_http3conn_close(conn: &mut NeqoHttp3Conn, error: u64) {
+    conn.conn.close(Instant::now(), error, "");
+}
+
+fn is_excluded_header(name: &str) -> bool {
+    if (name == "connection")
+        || (name == "host")
+        || (name == "keep-alive")
+        || (name == "proxy-connection")
+        || (name == "te")
+        || (name == "transfer-encoding")
+        || (name == "upgrade")
+        || (name == "sec-websocket-key")
+    {
+        true
+    } else {
+        false
+    }
+}
+
+fn parse_headers(headers: &nsACString) -> Result<Vec<Header>, nsresult> {
+    let mut hdrs = Vec::new();
+    // this is only used for headers built by Firefox.
+    // Firefox supplies all headers already prepared for sending over http1.
+    // They need to be split into (String, String) pairs.
+    match str::from_utf8(headers) {
+        Err(_) => {
+            return Err(NS_ERROR_INVALID_ARG);
+        }
+        Ok(h) => {
+            for elem in h.split("\r\n").skip(1) {
+                if elem.starts_with(':') {
+                    // colon headers are for http/2 and 3 and this is http/1
+                    // input, so that is probably a smuggling attack of some
+                    // kind.
+                    continue;
+                }
+                if elem.len() == 0 {
+                    continue;
+                }
+                let hdr_str: Vec<_> = elem.splitn(2, ":").collect();
+                let name = hdr_str[0].trim().to_lowercase();
+                if is_excluded_header(&name) {
+                    continue;
+                }
+                let value = if hdr_str.len() > 1 {
+                    String::from(hdr_str[1].trim())
+                } else {
+                    String::new()
+                };
+
+                hdrs.push(Header::new(name, value));
+            }
+        }
+    }
+    Ok(hdrs)
+}
+
+#[no_mangle]
+pub extern "C" fn neqo_http3conn_fetch(
+    conn: &mut NeqoHttp3Conn,
+    method: &nsACString,
+    scheme: &nsACString,
+    host: &nsACString,
+    path: &nsACString,
+    headers: &nsACString,
+    stream_id: &mut u64,
+    urgency: u8,
+    incremental: bool,
+) -> nsresult {
+    let hdrs = match parse_headers(headers) {
+        Err(e) => {
+            return e;
+        }
+        Ok(h) => h,
+    };
+    let method_tmp = match str::from_utf8(method) {
+        Ok(m) => m,
+        Err(_) => {
+            return NS_ERROR_INVALID_ARG;
+        }
+    };
+    let scheme_tmp = match str::from_utf8(scheme) {
+        Ok(s) => s,
+        Err(_) => {
+            return NS_ERROR_INVALID_ARG;
+        }
+    };
+    let host_tmp = match str::from_utf8(host) {
+        Ok(h) => h,
+        Err(_) => {
+            return NS_ERROR_INVALID_ARG;
+        }
+    };
+    let path_tmp = match str::from_utf8(path) {
+        Ok(p) => p,
+        Err(_) => {
+            return NS_ERROR_INVALID_ARG;
+        }
+    };
+    if urgency >= 8 {
+        return NS_ERROR_INVALID_ARG;
+    }
+    let priority = Priority::new(urgency, incremental);
+    match conn.conn.fetch(
+        Instant::now(),
+        method_tmp,
+        &(scheme_tmp, host_tmp, path_tmp),
+        &hdrs,
+        priority,
+    ) {
+        Ok(id) => {
+            *stream_id = id.as_u64();
+            NS_OK
+        }
+        Err(Http3Error::StreamLimitError) => NS_BASE_STREAM_WOULD_BLOCK,
+        Err(_) => NS_ERROR_UNEXPECTED,
+    }
+}
+
+#[no_mangle]
+pub extern "C" fn neqo_http3conn_priority_update(
+    conn: &mut NeqoHttp3Conn,
+    stream_id: u64,
+    urgency: u8,
+    incremental: bool,
+) -> nsresult {
+    if urgency >= 8 {
+        return NS_ERROR_INVALID_ARG;
+    }
+    let priority = Priority::new(urgency, incremental);
+    match conn
+        .conn
+        .priority_update(StreamId::from(stream_id), priority)
+    {
+        Ok(_) => NS_OK,
+        Err(_) => NS_ERROR_UNEXPECTED,
+    }
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn neqo_htttp3conn_send_request_body(
+    conn: &mut NeqoHttp3Conn,
+    stream_id: u64,
+    buf: *const u8,
+    len: u32,
+    read: &mut u32,
+) -> nsresult {
+    let array = slice::from_raw_parts(buf, len as usize);
+    match conn.conn.send_data(StreamId::from(stream_id), array) {
+        Ok(amount) => {
+            *read = u32::try_from(amount).unwrap();
+            if amount == 0 {
+                NS_BASE_STREAM_WOULD_BLOCK
+            } else {
+                NS_OK
+            }
+        }
+        Err(_) => NS_ERROR_UNEXPECTED,
+    }
+}
+
+fn crypto_error_code(err: neqo_crypto::Error) -> u64 {
+    match err {
+        neqo_crypto::Error::AeadError => 1,
+        neqo_crypto::Error::CertificateLoading => 2,
+        neqo_crypto::Error::CreateSslSocket => 3,
+        neqo_crypto::Error::HkdfError => 4,
+        neqo_crypto::Error::InternalError => 5,
+        neqo_crypto::Error::IntegerOverflow => 6,
+        neqo_crypto::Error::InvalidEpoch => 7,
+        neqo_crypto::Error::MixedHandshakeMethod => 8,
+        neqo_crypto::Error::NoDataAvailable => 9,
+        neqo_crypto::Error::NssError { .. } => 10,
+        neqo_crypto::Error::OverrunError => 11,
+        neqo_crypto::Error::SelfEncryptFailure => 12,
+        neqo_crypto::Error::TimeTravelError => 13,
+        neqo_crypto::Error::UnsupportedCipher => 14,
+        neqo_crypto::Error::UnsupportedVersion => 15,
+        neqo_crypto::Error::StringError => 16,
+        neqo_crypto::Error::EchRetry(_) => 17,
+        neqo_crypto::Error::CipherInitFailure => 18,
+    }
+}
+
+// This is only used for telemetry. Therefore we only return error code
+// numbers and do not label them. Recording telemetry is easier with a
+// number.
+#[repr(C)]
+pub enum CloseError {
+    TransportInternalError(u16),
+    TransportInternalErrorOther(u16),
+    TransportError(u64),
+    CryptoError(u64),
+    CryptoAlert(u8),
+    PeerAppError(u64),
+    PeerError(u64),
+    AppError(u64),
+    EchRetry,
+}
+
+impl From<TransportError> for CloseError {
+    fn from(error: TransportError) -> CloseError {
+        match error {
+            TransportError::InternalError(c) => CloseError::TransportInternalError(c),
+            TransportError::CryptoError(neqo_crypto::Error::EchRetry(_)) => CloseError::EchRetry,
+            TransportError::CryptoError(c) => CloseError::CryptoError(crypto_error_code(c)),
+            TransportError::CryptoAlert(c) => CloseError::CryptoAlert(c),
+            TransportError::PeerApplicationError(c) => CloseError::PeerAppError(c),
+            TransportError::PeerError(c) => CloseError::PeerError(c),
+            TransportError::NoError
+            | TransportError::IdleTimeout
+            | TransportError::ConnectionRefused
+            | TransportError::FlowControlError
+            | TransportError::StreamLimitError
+            | TransportError::StreamStateError
+            | TransportError::FinalSizeError
+            | TransportError::FrameEncodingError
+            | TransportError::TransportParameterError
+            | TransportError::ProtocolViolation
+            | TransportError::InvalidToken
+            | TransportError::KeysExhausted
+            | TransportError::ApplicationError
+            | TransportError::NoAvailablePath => CloseError::TransportError(error.code()),
+            TransportError::EchRetry(_) => CloseError::EchRetry,
+            TransportError::AckedUnsentPacket => CloseError::TransportInternalErrorOther(0),
+            TransportError::ConnectionIdLimitExceeded => CloseError::TransportInternalErrorOther(1),
+            TransportError::ConnectionIdsExhausted => CloseError::TransportInternalErrorOther(2),
+            TransportError::ConnectionState => CloseError::TransportInternalErrorOther(3),
+            TransportError::DecodingFrame => CloseError::TransportInternalErrorOther(4),
+            TransportError::DecryptError => CloseError::TransportInternalErrorOther(5),
+            TransportError::HandshakeFailed => CloseError::TransportInternalErrorOther(6),
+            TransportError::IntegerOverflow => CloseError::TransportInternalErrorOther(7),
+            TransportError::InvalidInput => CloseError::TransportInternalErrorOther(8),
+            TransportError::InvalidMigration => CloseError::TransportInternalErrorOther(9),
+            TransportError::InvalidPacket => CloseError::TransportInternalErrorOther(10),
+            TransportError::InvalidResumptionToken => CloseError::TransportInternalErrorOther(11),
+            TransportError::InvalidRetry => CloseError::TransportInternalErrorOther(12),
+            TransportError::InvalidStreamId => CloseError::TransportInternalErrorOther(13),
+            TransportError::KeysDiscarded(_) => CloseError::TransportInternalErrorOther(14),
+            TransportError::KeysPending(_) => CloseError::TransportInternalErrorOther(15),
+            TransportError::KeyUpdateBlocked => CloseError::TransportInternalErrorOther(16),
+            TransportError::NoMoreData => CloseError::TransportInternalErrorOther(17),
+            TransportError::NotConnected => CloseError::TransportInternalErrorOther(18),
+            TransportError::PacketNumberOverlap => CloseError::TransportInternalErrorOther(19),
+            TransportError::StatelessReset => CloseError::TransportInternalErrorOther(20),
+            TransportError::TooMuchData => CloseError::TransportInternalErrorOther(21),
+            TransportError::UnexpectedMessage => CloseError::TransportInternalErrorOther(22),
+            TransportError::UnknownConnectionId => CloseError::TransportInternalErrorOther(23),
+            TransportError::UnknownFrameType => CloseError::TransportInternalErrorOther(24),
+            TransportError::VersionNegotiation => CloseError::TransportInternalErrorOther(25),
+            TransportError::WrongRole => CloseError::TransportInternalErrorOther(26),
+            TransportError::QlogError => CloseError::TransportInternalErrorOther(27),
+            TransportError::NotAvailable => CloseError::TransportInternalErrorOther(28),
+            TransportError::DisabledVersion => CloseError::TransportInternalErrorOther(29),
+        }
+    }
+}
+
+impl From<neqo_transport::ConnectionError> for CloseError {
+    fn from(error: neqo_transport::ConnectionError) -> CloseError {
+        match error {
+            neqo_transport::ConnectionError::Transport(c) => c.into(),
+            neqo_transport::ConnectionError::Application(c) => CloseError::AppError(c),
+        }
+    }
+}
+
+// Reset a stream with streamId.
+#[no_mangle]
+pub extern "C" fn neqo_http3conn_cancel_fetch(
+    conn: &mut NeqoHttp3Conn,
+    stream_id: u64,
+    error: u64,
+) -> nsresult {
+    match conn.conn.cancel_fetch(StreamId::from(stream_id), error) {
+        Ok(()) => NS_OK,
+        Err(_) => NS_ERROR_INVALID_ARG,
+    }
+}
+
+// Reset a stream with streamId.
+#[no_mangle]
+pub extern "C" fn neqo_http3conn_reset_stream(
+    conn: &mut NeqoHttp3Conn,
+    stream_id: u64,
+    error: u64,
+) -> nsresult {
+    match conn
+        .conn
+        .stream_reset_send(StreamId::from(stream_id), error)
+    {
+        Ok(()) => NS_OK,
+        Err(_) => NS_ERROR_INVALID_ARG,
+    }
+}
+
+#[no_mangle]
+pub extern "C" fn neqo_http3conn_stream_stop_sending(
+    conn: &mut NeqoHttp3Conn,
+    stream_id: u64,
+    error: u64,
+) -> nsresult {
+    match conn
+        .conn
+        .stream_stop_sending(StreamId::from(stream_id), error)
+    {
+        Ok(()) => NS_OK,
+        Err(_) => NS_ERROR_INVALID_ARG,
+    }
+}
+
+// Close sending side of a stream with stream_id
+#[no_mangle]
+pub extern "C" fn neqo_http3conn_close_stream(
+    conn: &mut NeqoHttp3Conn,
+    stream_id: u64,
+) -> nsresult {
+    match conn.conn.stream_close_send(StreamId::from(stream_id)) {
+        Ok(()) => NS_OK,
+        Err(_) => NS_ERROR_INVALID_ARG,
+    }
+}
+
+// WebTransport streams can be unidirectional and bidirectional.
+// It is mapped to and from neqo's StreamType enum.
+#[repr(C)]
+pub enum WebTransportStreamType {
+    BiDi,
+    UniDi,
+}
+
+impl From<StreamType> for WebTransportStreamType {
+    fn from(t: StreamType) -> WebTransportStreamType {
+        match t {
+            StreamType::BiDi => WebTransportStreamType::BiDi,
+            StreamType::UniDi => WebTransportStreamType::UniDi,
+        }
+    }
+}
+
+impl From<WebTransportStreamType> for StreamType {
+    fn from(t: WebTransportStreamType) -> StreamType {
+        match t {
+            WebTransportStreamType::BiDi => StreamType::BiDi,
+            WebTransportStreamType::UniDi => StreamType::UniDi,
+        }
+    }
+}
+
+#[repr(C)]
+pub enum SessionCloseReasonExternal {
+    Error(u64),
+    Status(u16),
+    Clean(u32),
+}
+
+impl SessionCloseReasonExternal {
+    fn new(reason: SessionCloseReason, data: &mut ThinVec<u8>) -> SessionCloseReasonExternal {
+        match reason {
+            SessionCloseReason::Error(e) => SessionCloseReasonExternal::Error(e),
+            SessionCloseReason::Status(s) => SessionCloseReasonExternal::Status(s),
+            SessionCloseReason::Clean { error, message } => {
+                data.extend_from_slice(message.as_ref());
+                SessionCloseReasonExternal::Clean(error)
+            }
+        }
+    }
+}
+
+#[repr(C)]
+pub enum WebTransportEventExternal {
+    Negotiated(bool),
+    Session(u64),
+    SessionClosed {
+        stream_id: u64,
+        reason: SessionCloseReasonExternal,
+    },
+    NewStream {
+        stream_id: u64,
+        stream_type: WebTransportStreamType,
+        session_id: u64,
+    },
+    Datagram {
+        session_id: u64,
+    },
+}
+
+impl WebTransportEventExternal {
+    fn new(event: WebTransportEvent, data: &mut ThinVec<u8>) -> WebTransportEventExternal {
+        match event {
+            WebTransportEvent::Negotiated(n) => WebTransportEventExternal::Negotiated(n),
+            WebTransportEvent::Session { stream_id, status } => {
+                data.extend_from_slice(b"HTTP/3 ");
+                data.extend_from_slice(&status.to_string().as_bytes());
+                data.extend_from_slice(b"\r\n\r\n");
+                WebTransportEventExternal::Session(stream_id.as_u64())
+            }
+            WebTransportEvent::SessionClosed { stream_id, reason } => match reason {
+                SessionCloseReason::Status(status) => {
+                    data.extend_from_slice(b"HTTP/3 ");
+                    data.extend_from_slice(&status.to_string().as_bytes());
+                    data.extend_from_slice(b"\r\n\r\n");
+                    WebTransportEventExternal::Session(stream_id.as_u64())
+                }
+                _ => WebTransportEventExternal::SessionClosed {
+                    stream_id: stream_id.as_u64(),
+                    reason: SessionCloseReasonExternal::new(reason, data),
+                },
+            },
+            WebTransportEvent::NewStream {
+                stream_id,
+                session_id,
+            } => WebTransportEventExternal::NewStream {
+                stream_id: stream_id.as_u64(),
+                stream_type: stream_id.stream_type().into(),
+                session_id: session_id.as_u64(),
+            },
+            WebTransportEvent::Datagram {
+                session_id,
+                datagram,
+            } => {
+                data.extend_from_slice(datagram.as_ref());
+                WebTransportEventExternal::Datagram {
+                    session_id: session_id.as_u64(),
+                }
+            }
+        }
+    }
+}
+
+#[repr(C)]
+pub enum Http3Event {
+    /// A request stream has space for more data to be sent.
+    DataWritable {
+        stream_id: u64,
+    },
+    /// A server has send STOP_SENDING frame.
+    StopSending {
+        stream_id: u64,
+        error: u64,
+    },
+    HeaderReady {
+        stream_id: u64,
+        fin: bool,
+        interim: bool,
+    },
+    /// New bytes available for reading.
+    DataReadable {
+        stream_id: u64,
+    },
+    /// Peer reset the stream.
+    Reset {
+        stream_id: u64,
+        error: u64,
+        local: bool,
+    },
+    /// A PushPromise
+    PushPromise {
+        push_id: u64,
+        request_stream_id: u64,
+    },
+    /// A push response headers are ready.
+    PushHeaderReady {
+        push_id: u64,
+        fin: bool,
+    },
+    /// New bytes are available on a push stream for reading.
+    PushDataReadable {
+        push_id: u64,
+    },
+    /// A push has been canceled.
+    PushCanceled {
+        push_id: u64,
+    },
+    PushReset {
+        push_id: u64,
+        error: u64,
+    },
+    RequestsCreatable,
+    AuthenticationNeeded,
+    ZeroRttRejected,
+    ConnectionConnected,
+    GoawayReceived,
+    ConnectionClosing {
+        error: CloseError,
+    },
+    ConnectionClosed {
+        error: CloseError,
+    },
+    ResumptionToken {
+        expire_in: u64, // microseconds
+    },
+    EchFallbackAuthenticationNeeded,
+    WebTransport(WebTransportEventExternal),
+    NoEvent,
+}
+
+fn sanitize_header(mut y: Cow<[u8]>) -> Cow<[u8]> {
+    for i in 0..y.len() {
+        if matches!(y[i], b'\n' | b'\r' | b'\0') {
+            y.to_mut()[i] = b' ';
+        }
+    }
+    y
+}
+
+fn convert_h3_to_h1_headers(headers: Vec<Header>, ret_headers: &mut ThinVec<u8>) -> nsresult {
+    if headers.iter().filter(|&h| h.name() == ":status").count() != 1 {
+        return NS_ERROR_ILLEGAL_VALUE;
+    }
+
+    let status_val = headers
+        .iter()
+        .find(|&h| h.name() == ":status")
+        .expect("must be one")
+        .value();
+
+    ret_headers.extend_from_slice(b"HTTP/3 ");
+    ret_headers.extend_from_slice(status_val.as_bytes());
+    ret_headers.extend_from_slice(b"\r\n");
+
+    for hdr in headers.iter().filter(|&h| h.name() != ":status") {
+        ret_headers.extend_from_slice(&sanitize_header(Cow::from(hdr.name().as_bytes())));
+        ret_headers.extend_from_slice(b": ");
+        ret_headers.extend_from_slice(&sanitize_header(Cow::from(hdr.value().as_bytes())));
+        ret_headers.extend_from_slice(b"\r\n");
+    }
+    ret_headers.extend_from_slice(b"\r\n");
+    return NS_OK;
+}
+
+#[no_mangle]
+pub extern "C" fn neqo_http3conn_event(
+    conn: &mut NeqoHttp3Conn,
+    ret_event: &mut Http3Event,
+    data: &mut ThinVec<u8>,
+) -> nsresult {
+    while let Some(evt) = conn.conn.next_event() {
+        let fe = match evt {
+            Http3ClientEvent::DataWritable { stream_id } => Http3Event::DataWritable {
+                stream_id: stream_id.as_u64(),
+            },
+            Http3ClientEvent::StopSending { stream_id, error } => Http3Event::StopSending {
+                stream_id: stream_id.as_u64(),
+                error,
+            },
+            Http3ClientEvent::HeaderReady {
+                stream_id,
+                headers,
+                fin,
+                interim,
+            } => {
+                let res = convert_h3_to_h1_headers(headers, data);
+                if res != NS_OK {
+                    return res;
+                }
+                Http3Event::HeaderReady {
+                    stream_id: stream_id.as_u64(),
+                    fin,
+                    interim,
+                }
+            }
+            Http3ClientEvent::DataReadable { stream_id } => Http3Event::DataReadable {
+                stream_id: stream_id.as_u64(),
+            },
+            Http3ClientEvent::Reset {
+                stream_id,
+                error,
+                local,
+            } => Http3Event::Reset {
+                stream_id: stream_id.as_u64(),
+                error,
+                local,
+            },
+            Http3ClientEvent::PushPromise {
+                push_id,
+                request_stream_id,
+                headers,
+            } => {
+                let res = convert_h3_to_h1_headers(headers, data);
+                if res != NS_OK {
+                    return res;
+                }
+                Http3Event::PushPromise {
+                    push_id,
+                    request_stream_id: request_stream_id.as_u64(),
+                }
+            }
+            Http3ClientEvent::PushHeaderReady {
+                push_id,
+                headers,
+                fin,
+                interim,
+            } => {
+                if interim {
+                    Http3Event::NoEvent
+                } else {
+                    let res = convert_h3_to_h1_headers(headers, data);
+                    if res != NS_OK {
+                        return res;
+                    }
+                    Http3Event::PushHeaderReady { push_id, fin }
+                }
+            }
+            Http3ClientEvent::PushDataReadable { push_id } => {
+                Http3Event::PushDataReadable { push_id }
+            }
+            Http3ClientEvent::PushCanceled { push_id } => Http3Event::PushCanceled { push_id },
+            Http3ClientEvent::PushReset { push_id, error } => {
+                Http3Event::PushReset { push_id, error }
+            }
+            Http3ClientEvent::RequestsCreatable => Http3Event::RequestsCreatable,
+            Http3ClientEvent::AuthenticationNeeded => Http3Event::AuthenticationNeeded,
+            Http3ClientEvent::ZeroRttRejected => Http3Event::ZeroRttRejected,
+            Http3ClientEvent::ResumptionToken(token) => {
+                // expiration_time time is Instant, transform it into microseconds it will
+                // be valid for. Necko code will add the value to PR_Now() to get the expiration
+                // time in PRTime.
+                if token.expiration_time() > Instant::now() {
+                    let e = (token.expiration_time() - Instant::now()).as_micros();
+                    if let Ok(expire_in) = u64::try_from(e) {
+                        data.extend_from_slice(token.as_ref());
+                        Http3Event::ResumptionToken { expire_in }
+                    } else {
+                        Http3Event::NoEvent
+                    }
+                } else {
+                    Http3Event::NoEvent
+                }
+            }
+            Http3ClientEvent::GoawayReceived => Http3Event::GoawayReceived,
+            Http3ClientEvent::StateChange(state) => match state {
+                Http3State::Connected => Http3Event::ConnectionConnected,
+                Http3State::Closing(error_code) => {
+                    match error_code {
+                        neqo_transport::ConnectionError::Transport(
+                            TransportError::CryptoError(neqo_crypto::Error::EchRetry(ref c)),
+                        )
+                        | neqo_transport::ConnectionError::Transport(TransportError::EchRetry(
+                            ref c,
+                        )) => {
+                            data.extend_from_slice(c.as_ref());
+                        }
+                        _ => {}
+                    }
+                    Http3Event::ConnectionClosing {
+                        error: error_code.into(),
+                    }
+                }
+                Http3State::Closed(error_code) => {
+                    match error_code {
+                        neqo_transport::ConnectionError::Transport(
+                            TransportError::CryptoError(neqo_crypto::Error::EchRetry(ref c)),
+                        )
+                        | neqo_transport::ConnectionError::Transport(TransportError::EchRetry(
+                            ref c,
+                        )) => {
+                            data.extend_from_slice(c.as_ref());
+                        }
+                        _ => {}
+                    }
+                    Http3Event::ConnectionClosed {
+                        error: error_code.into(),
+                    }
+                }
+                _ => Http3Event::NoEvent,
+            },
+            Http3ClientEvent::EchFallbackAuthenticationNeeded { public_name } => {
+                data.extend_from_slice(public_name.as_ref());
+                Http3Event::EchFallbackAuthenticationNeeded
+            }
+            Http3ClientEvent::WebTransport(e) => {
+                Http3Event::WebTransport(WebTransportEventExternal::new(e, data))
+            }
+        };
+
+        if !matches!(fe, Http3Event::NoEvent) {
+            *ret_event = fe;
+            return NS_OK;
+        }
+    }
+
+    *ret_event = Http3Event::NoEvent;
+    NS_OK
+}
+
+// Read response data into buf.
+#[no_mangle]
+pub unsafe extern "C" fn neqo_http3conn_read_response_data(
+    conn: &mut NeqoHttp3Conn,
+    stream_id: u64,
+    buf: *mut u8,
+    len: u32,
+    read: &mut u32,
+    fin: &mut bool,
+) -> nsresult {
+    let array = slice::from_raw_parts_mut(buf, len as usize);
+    match conn
+        .conn
+        .read_data(Instant::now(), StreamId::from(stream_id), &mut array[..])
+    {
+        Ok((amount, fin_recvd)) => {
+            *read = u32::try_from(amount).unwrap();
+            *fin = fin_recvd;
+            if (amount == 0) && !fin_recvd {
+                NS_BASE_STREAM_WOULD_BLOCK
+            } else {
+                NS_OK
+            }
+        }
+        Err(Http3Error::InvalidStreamId)
+        | Err(Http3Error::TransportError(TransportError::NoMoreData)) => NS_ERROR_INVALID_ARG,
+        Err(_) => NS_ERROR_NET_HTTP3_PROTOCOL_ERROR,
+    }
+}
+
+#[repr(C)]
+pub struct NeqoSecretInfo {
+    set: bool,
+    version: u16,
+    cipher: u16,
+    group: u16,
+    resumed: bool,
+    early_data: bool,
+    alpn: nsCString,
+    signature_scheme: u16,
+    ech_accepted: bool,
+}
+
+#[no_mangle]
+pub extern "C" fn neqo_http3conn_tls_info(
+    conn: &mut NeqoHttp3Conn,
+    sec_info: &mut NeqoSecretInfo,
+) -> nsresult {
+    match conn.conn.tls_info() {
+        Some(info) => {
+            sec_info.set = true;
+            sec_info.version = info.version();
+            sec_info.cipher = info.cipher_suite();
+            sec_info.group = info.key_exchange();
+            sec_info.resumed = info.resumed();
+            sec_info.early_data = info.early_data_accepted();
+            sec_info.alpn = match info.alpn() {
+                Some(a) => nsCString::from(a),
+                None => nsCString::new(),
+            };
+            sec_info.signature_scheme = info.signature_scheme();
+            sec_info.ech_accepted = info.ech_accepted();
+            NS_OK
+        }
+        None => NS_ERROR_NOT_AVAILABLE,
+    }
+}
+
+#[repr(C)]
+pub struct NeqoCertificateInfo {
+    certs: ThinVec<ThinVec<u8>>,
+    stapled_ocsp_responses_present: bool,
+    stapled_ocsp_responses: ThinVec<ThinVec<u8>>,
+    signed_cert_timestamp_present: bool,
+    signed_cert_timestamp: ThinVec<u8>,
+}
+
+#[no_mangle]
+pub extern "C" fn neqo_http3conn_peer_certificate_info(
+    conn: &mut NeqoHttp3Conn,
+    neqo_certs_info: &mut NeqoCertificateInfo,
+) -> nsresult {
+    let mut certs_info = match conn.conn.peer_certificate() {
+        Some(certs) => certs,
+        None => return NS_ERROR_NOT_AVAILABLE,
+    };
+
+    neqo_certs_info.certs = certs_info
+        .map(|cert| cert.iter().cloned().collect())
+        .collect();
+
+    match &mut certs_info.stapled_ocsp_responses() {
+        Some(ocsp_val) => {
+            neqo_certs_info.stapled_ocsp_responses_present = true;
+            neqo_certs_info.stapled_ocsp_responses = ocsp_val
+                .iter()
+                .map(|ocsp| ocsp.iter().cloned().collect())
+                .collect();
+        }
+        None => {
+            neqo_certs_info.stapled_ocsp_responses_present = false;
+        }
+    };
+
+    match certs_info.signed_cert_timestamp() {
+        Some(sct_val) => {
+            neqo_certs_info.signed_cert_timestamp_present = true;
+            neqo_certs_info
+                .signed_cert_timestamp
+                .extend_from_slice(sct_val);
+        }
+        None => {
+            neqo_certs_info.signed_cert_timestamp_present = false;
+        }
+    };
+
+    NS_OK
+}
+
+#[no_mangle]
+pub extern "C" fn neqo_http3conn_authenticated(conn: &mut NeqoHttp3Conn, error: PRErrorCode) {
+    conn.conn.authenticated(error.into(), Instant::now());
+}
+
+#[no_mangle]
+pub extern "C" fn neqo_http3conn_set_resumption_token(
+    conn: &mut NeqoHttp3Conn,
+    token: &mut ThinVec<u8>,
+) {
+    let _ = conn.conn.enable_resumption(Instant::now(), token);
+}
+
+#[no_mangle]
+pub extern "C" fn neqo_http3conn_set_ech_config(
+    conn: &mut NeqoHttp3Conn,
+    ech_config: &mut ThinVec<u8>,
+) {
+    let _ = conn.conn.enable_ech(ech_config);
+}
+
+#[no_mangle]
+pub extern "C" fn neqo_http3conn_is_zero_rtt(conn: &mut NeqoHttp3Conn) -> bool {
+    conn.conn.state() == Http3State::ZeroRtt
+}
+
+#[repr(C)]
+#[derive(Default)]
+pub struct Http3Stats {
+    /// Total packets received, including all the bad ones.
+    pub packets_rx: usize,
+    /// Duplicate packets received.
+    pub dups_rx: usize,
+    /// Dropped packets or dropped garbage.
+    pub dropped_rx: usize,
+    /// The number of packet that were saved for later processing.
+    pub saved_datagrams: usize,
+    /// Total packets sent.
+    pub packets_tx: usize,
+    /// Total number of packets that are declared lost.
+    pub lost: usize,
+    /// Late acknowledgments, for packets that were declared lost already.
+    pub late_ack: usize,
+    /// Acknowledgments for packets that contained data that was marked
+    /// for retransmission when the PTO timer popped.
+    pub pto_ack: usize,
+    /// Count PTOs. Single PTOs, 2 PTOs in a row, 3 PTOs in row, etc. are counted
+    /// separately.
+    pub pto_counts: [usize; 16],
+}
+
+#[no_mangle]
+pub extern "C" fn neqo_http3conn_get_stats(conn: &mut NeqoHttp3Conn, stats: &mut Http3Stats) {
+    let t_stats = conn.conn.transport_stats();
+    stats.packets_rx = t_stats.packets_rx;
+    stats.dups_rx = t_stats.dups_rx;
+    stats.dropped_rx = t_stats.dropped_rx;
+    stats.saved_datagrams = t_stats.saved_datagrams;
+    stats.packets_tx = t_stats.packets_tx;
+    stats.lost = t_stats.lost;
+    stats.late_ack = t_stats.late_ack;
+    stats.pto_ack = t_stats.pto_ack;
+    stats.pto_counts = t_stats.pto_counts;
+}
+
+#[no_mangle]
+pub extern "C" fn neqo_http3conn_webtransport_create_session(
+    conn: &mut NeqoHttp3Conn,
+    host: &nsACString,
+    path: &nsACString,
+    headers: &nsACString,
+    stream_id: &mut u64,
+) -> nsresult {
+    let hdrs = match parse_headers(headers) {
+        Err(e) => {
+            return e;
+        }
+        Ok(h) => h,
+    };
+    let host_tmp = match str::from_utf8(host) {
+        Ok(h) => h,
+        Err(_) => {
+            return NS_ERROR_INVALID_ARG;
+        }
+    };
+    let path_tmp = match str::from_utf8(path) {
+        Ok(p) => p,
+        Err(_) => {
+            return NS_ERROR_INVALID_ARG;
+        }
+    };
+
+    match conn.conn.webtransport_create_session(
+        Instant::now(),
+        &("https", host_tmp, path_tmp),
+        &hdrs,
+    ) {
+        Ok(id) => {
+            *stream_id = id.as_u64();
+            NS_OK
+        }
+        Err(Http3Error::StreamLimitError) => NS_BASE_STREAM_WOULD_BLOCK,
+        Err(_) => NS_ERROR_UNEXPECTED,
+    }
+}
+
+#[no_mangle]
+pub extern "C" fn neqo_http3conn_webtransport_close_session(
+    conn: &mut NeqoHttp3Conn,
+    session_id: u64,
+    error: u32,
+    message: &nsACString,
+) -> nsresult {
+    let message_tmp = match str::from_utf8(message) {
+        Ok(p) => p,
+        Err(_) => {
+            return NS_ERROR_INVALID_ARG;
+        }
+    };
+    match conn
+        .conn
+        .webtransport_close_session(StreamId::from(session_id), error, message_tmp)
+    {
+        Ok(()) => NS_OK,
+        Err(_) => NS_ERROR_INVALID_ARG,
+    }
+}
+
+#[no_mangle]
+pub extern "C" fn neqo_http3conn_webtransport_create_stream(
+    conn: &mut NeqoHttp3Conn,
+    session_id: u64,
+    stream_type: WebTransportStreamType,
+    stream_id: &mut u64,
+) -> nsresult {
+    match conn
+        .conn
+        .webtransport_create_stream(StreamId::from(session_id), stream_type.into())
+    {
+        Ok(id) => {
+            *stream_id = id.as_u64();
+            NS_OK
+        }
+        Err(Http3Error::StreamLimitError) => NS_BASE_STREAM_WOULD_BLOCK,
+        Err(_) => NS_ERROR_UNEXPECTED,
+    }
+}
+
+#[no_mangle]
+pub extern "C" fn neqo_http3conn_webtransport_send_datagram(
+    conn: &mut NeqoHttp3Conn,
+    session_id: u64,
+    data: &mut ThinVec<u8>,
+    tracking_id: u64,
+) -> nsresult {
+    let id = if tracking_id == 0 {
+        None
+    } else {
+        Some(tracking_id)
+    };
+    match conn
+        .conn
+        .webtransport_send_datagram(StreamId::from(session_id), data, id)
+    {
+        Ok(()) => NS_OK,
+        Err(Http3Error::TransportError(TransportError::TooMuchData)) => NS_ERROR_NOT_AVAILABLE,
+        Err(_) => NS_ERROR_UNEXPECTED,
+    }
+}
+
+#[no_mangle]
+pub extern "C" fn neqo_http3conn_webtransport_max_datagram_size(
+    conn: &mut NeqoHttp3Conn,
+    session_id: u64,
+    result: &mut u64,
+) -> nsresult {
+    match conn
+        .conn
+        .webtransport_max_datagram_size(StreamId::from(session_id))
+    {
+        Ok(size) => {
+            *result = size;
+            NS_OK
+        }
+        Err(_) => NS_ERROR_UNEXPECTED,
+    }
+}
diff --git a/netwerk/socket/nsINamedPipeService.idl b/netwerk/socket/nsINamedPipeService.idl
new file mode 100644
index 0000000000..9db557577d
--- /dev/null
+++ b/netwerk/socket/nsINamedPipeService.idl
@@ -0,0 +1,77 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+#include "nsrootidl.idl"
+
+/**
+ * nsINamedPipeDataObserver
+ *
+ * This is the callback interface for nsINamedPipeService.
+ * The functions are called by the internal thread in the nsINamedPipeService.
+ */
+[scriptable, uuid(de4f460b-94fd-442c-9002-1637beb2185a)]
+interface nsINamedPipeDataObserver : nsISupports
+{
+    /**
+     * onDataAvailable
+     *
+     * @param aBytesTransferred
+     *        Transfered bytes during last transmission.
+     * @param aOverlapped
+     *        Corresponding overlapped structure used by the async I/O
+     */
+    void onDataAvailable(in unsigned long aBytesTransferred,
+                         in voidPtr aOverlapped);
+
+    /**
+     * onError
+     *
+     * @param aError
+     *        Error code of the error.
+     * @param aOverlapped
+     *        Corresponding overlapped structure used by the async I/O
+     */
+    void onError(in unsigned long aError,
+                 in voidPtr aOverlapped);
+};
+
+/**
+ * nsINamedPipeService
+ */
+[scriptable, uuid(1bf19133-5625-4ac8-836a-80b1c215f72b)]
+interface nsINamedPipeService : nsISupports
+{
+    /**
+     * addDataObserver
+     *
+     * @param aHandle
+     *        The handle that is going to be monitored for read/write operations.
+     *        Only handles that are opened with overlapped IO are supported.
+     * @param aObserver
+     *        The observer of the handle, the service strong-refs of the observer.
+     */
+    void addDataObserver(in voidPtr aHandle,
+                         in nsINamedPipeDataObserver aObserver);
+
+    /**
+     * removeDataObserver
+     *
+     * @param aHandle
+              The handle associated to the observer, and will be closed by the
+              service.
+     * @param aObserver
+     *        The observer to be removed.
+     */
+    void removeDataObserver(in voidPtr aHandle,
+                            in nsINamedPipeDataObserver aObserver);
+
+    /**
+     * isOnCurrentThread
+     *
+     * @return the caller runs within the internal thread.
+     */
+    boolean isOnCurrentThread();
+};
diff --git a/netwerk/socket/nsISocketProvider.idl b/netwerk/socket/nsISocketProvider.idl
new file mode 100644
index 0000000000..ed4947ccb5
--- /dev/null
+++ b/netwerk/socket/nsISocketProvider.idl
@@ -0,0 +1,141 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+interface nsIProxyInfo;
+interface nsITLSSocketControl;
+[ptr] native PRFileDescStar(struct PRFileDesc);
+native OriginAttributes(mozilla::OriginAttributes);
+[ref] native const_OriginAttributesRef(const mozilla::OriginAttributes);
+
+%{ C++
+#include "mozilla/BasePrincipal.h"
+%}
+
+/**
+ * nsISocketProvider
+ */
+[scriptable, uuid(508d5469-9e1e-4a08-b5b0-7cfebba1e51a)]
+interface nsISocketProvider : nsISupports
+{
+    /**
+     * newSocket
+     *
+     * @param aFamily
+     *        The address family for this socket (PR_AF_INET or PR_AF_INET6).
+     * @param aHost
+     *        The origin hostname for this connection.
+     * @param aPort
+     *        The origin port for this connection.
+     * @param aProxyHost
+     *        If non-null, the proxy hostname for this connection.
+     * @param aProxyPort
+     *        The proxy port for this connection.
+     * @param aFlags
+     *        Control flags that govern this connection (see below.)
+     * @param aTlsFlags
+     *        An opaque flags for non-standard behavior of the TLS system.
+     *        It is unlikely this will need to be set outside of telemetry
+     *        studies relating to the TLS implementation.
+     * @param aFileDesc
+     *        The resulting PRFileDesc.
+     * @param aTLSSocketControl
+     *        TLS socket control object that should be associated with
+     *        aFileDesc, if applicable.
+     */
+    [noscript]
+    void newSocket(in long                      aFamily,
+                   in string                    aHost,
+                   in long                      aPort,
+                   in nsIProxyInfo              aProxy,
+                   in const_OriginAttributesRef aOriginAttributes,
+                   in unsigned long             aFlags,
+                   in unsigned long             aTlsFlags,
+                   out PRFileDescStar           aFileDesc,
+                   out nsITLSSocketControl      aTLSSocketControl);
+
+    /**
+     * addToSocket
+     *
+     * This function is called to allow the socket provider to layer a
+     * PRFileDesc on top of another PRFileDesc.  For example, SSL via a SOCKS
+     * proxy.
+     *
+     * Parameters are the same as newSocket with the exception of aFileDesc,
+     * which is an in-param instead.
+     */
+    [noscript]
+    void addToSocket(in long                      aFamily,
+                     in string                    aHost,
+                     in long                      aPort,
+                     in nsIProxyInfo              aProxy,
+                     in const_OriginAttributesRef aOriginAttributes,
+                     in unsigned long             aFlags,
+                     in unsigned long             aTlsFlags,
+                     in PRFileDescStar            aFileDesc,
+                     out nsITLSSocketControl      aTLSSocketControl);
+
+    /**
+     * PROXY_RESOLVES_HOST
+     *
+     * This flag is set if the proxy is to perform hostname resolution instead
+     * of the client.  When set, the hostname parameter passed when in this
+     * interface will be used instead of the address structure passed for a
+     * later connect et al. request.
+     */
+    const long PROXY_RESOLVES_HOST = 1 << 0;
+
+    /**
+     * When setting this flag, the socket will not apply any
+     * credentials when establishing a connection. For example,
+     * an SSL connection would not send any client-certificates
+     * if this flag is set.
+     */
+    const long ANONYMOUS_CONNECT = 1 << 1;
+
+    /**
+     * If set, indicates that the connection was initiated from a source
+     * defined as being private in the sense of Private Browsing. Generally,
+     * there should be no state shared between connections that are private
+     * and those that are not; it is OK for multiple private connections
+     * to share state with each other, and it is OK for multiple non-private
+     * connections to share state with each other.
+     */
+    const unsigned long NO_PERMANENT_STORAGE = 1 << 2;
+
+    /**
+     * If set, do not use newer protocol features that might have interop problems
+     * on the Internet. Intended only for use with critical infra like the updater.
+     * default is false.
+     */
+    const unsigned long BE_CONSERVATIVE = 1 << 3;
+
+    /**
+     * This is used for a temporary workaround for a web-compat issue. The flag is
+     * only set on CORS preflight request to allowed sending client certificates
+     * on a connection for an anonymous request.
+     */
+    const long ANONYMOUS_CONNECT_ALLOW_CLIENT_CERT = 1 << 4;
+
+    /**
+     * If set, do not send an ECH extension (whether GREASE or 'real').
+     * Currently false by default and is set when retrying failed connections.
+     */
+    const unsigned long DONT_TRY_ECH = (1 << 10);
+
+    /**
+     *  If set, indicates that the connection is a retry.
+     */
+    const unsigned long IS_RETRY = (1 << 11);
+
+    /**
+     * If set, indicates that the connection used a privacy-preserving DNS
+     * transport such as DoH, DoQ, ODOH or similar. Currently this field is
+     * set only when DoH is used via the TRR.
+     */
+    const unsigned long USED_PRIVATE_DNS = (1 << 12);
+
+};
diff --git a/netwerk/socket/nsISocketProviderService.idl b/netwerk/socket/nsISocketProviderService.idl
new file mode 100644
index 0000000000..db38d299a5
--- /dev/null
+++ b/netwerk/socket/nsISocketProviderService.idl
@@ -0,0 +1,20 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+interface nsISocketProvider;
+
+/**
+ * nsISocketProviderService
+ *
+ * Provides a mapping between a socket type and its associated socket provider
+ * instance.  One could also use the service manager directly.
+ */
+[scriptable, uuid(8f8a23d0-5472-11d3-bbc8-0000861d1237)]
+interface nsISocketProviderService : nsISupports
+{
+    nsISocketProvider getSocketProvider(in string socketType);
+};
diff --git a/netwerk/socket/nsNamedPipeIOLayer.cpp b/netwerk/socket/nsNamedPipeIOLayer.cpp
new file mode 100644
index 0000000000..d229f0e23e
--- /dev/null
+++ b/netwerk/socket/nsNamedPipeIOLayer.cpp
@@ -0,0 +1,864 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsNamedPipeIOLayer.h"
+
+#include <algorithm>
+#include <utility>
+
+#include "mozilla/Atomics.h"
+#include "mozilla/DebugOnly.h"
+#include "mozilla/Logging.h"
+#include "mozilla/RefPtr.h"
+#include "mozilla/Unused.h"
+#include "mozilla/net/DNS.h"
+#include "nsISupportsImpl.h"
+#include "nsNamedPipeService.h"
+#include "nsNativeCharsetUtils.h"
+#include "nsNetCID.h"
+#include "nsServiceManagerUtils.h"
+#include "nsSocketTransportService2.h"
+#include "nsString.h"
+#include "nsThreadUtils.h"
+#include "nspr.h"
+#include "private/pprio.h"
+
+namespace mozilla {
+namespace net {
+
+static mozilla::LazyLogModule gNamedPipeLog("NamedPipeWin");
+#define LOG_NPIO_DEBUG(...) \
+  MOZ_LOG(gNamedPipeLog, mozilla::LogLevel::Debug, (__VA_ARGS__))
+#define LOG_NPIO_ERROR(...) \
+  MOZ_LOG(gNamedPipeLog, mozilla::LogLevel::Error, (__VA_ARGS__))
+
+PRDescIdentity nsNamedPipeLayerIdentity;
+static PRIOMethods nsNamedPipeLayerMethods;
+
+class NamedPipeInfo final : public nsINamedPipeDataObserver {
+ public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSINAMEDPIPEDATAOBSERVER
+
+  explicit NamedPipeInfo();
+
+  nsresult Connect(const nsAString& aPath);
+  nsresult Disconnect();
+
+  /**
+   * Both blocking/non-blocking mode are supported in this class.
+   * The default mode is non-blocking mode, however, the client may change its
+   * mode to blocking mode during hand-shaking (e.g. nsSOCKSSocketInfo).
+   *
+   * In non-blocking mode, |Read| and |Write| should be called by clients only
+   * when |GetPollFlags| reports data availability. That is, the client calls
+   * |GetPollFlags| with |PR_POLL_READ| and/or |PR_POLL_WRITE| set, and
+   * according to the flags that set, |GetPollFlags| will check buffers status
+   * and decide corresponding actions:
+   *
+   * -------------------------------------------------------------------
+   * |               | data in buffer          | empty buffer          |
+   * |---------------+-------------------------+-----------------------|
+   * | PR_POLL_READ  | out: PR_POLL_READ       | DoRead/DoReadContinue |
+   * |---------------+-------------------------+-----------------------|
+   * | PR_POLL_WRITE | DoWrite/DoWriteContinue | out: PR_POLL_WRITE    |
+   * ------------------------------------------+------------------------
+   *
+   * |DoRead| and |DoWrite| initiate read/write operations asynchronously, and
+   * the |DoReadContinue| and |DoWriteContinue| are used to check the amount
+   * of the data are read/written to/from buffers.
+   *
+   * The output parameter and the return value of |GetPollFlags| are identical
+   * because we don't rely on the low-level select function to wait for data
+   * availability, we instead use nsNamedPipeService to poll I/O completeness.
+   *
+   * When client get |PR_POLL_READ| or |PR_POLL_WRITE| from |GetPollFlags|,
+   * they are able to use |Read| or |Write| to access the data in the buffer,
+   * and this is supposed to be very fast because no network traffic is
+   * involved.
+   *
+   * In blocking mode, the flow is quite similar to non-blocking mode, but
+   * |DoReadContinue| and |DoWriteContinue| are never been used since the
+   * operations are done synchronously, which could lead to slow responses.
+   */
+  int32_t Read(void* aBuffer, int32_t aSize);
+  int32_t Write(const void* aBuffer, int32_t aSize);
+
+  // Like Read, but doesn't remove data in internal buffer.
+  uint32_t Peek(void* aBuffer, int32_t aSize);
+
+  // Number of bytes available to read in internal buffer.
+  int32_t Available() const;
+
+  // Flush write buffer
+  //
+  // @return whether the buffer has been flushed
+  bool Sync(uint32_t aTimeout);
+  void SetNonblocking(bool nonblocking);
+
+  bool IsConnected() const;
+  bool IsNonblocking() const;
+  HANDLE GetHandle() const;
+
+  // Initiate and check current status for read/write operations.
+  int16_t GetPollFlags(int16_t aInFlags, int16_t* aOutFlags);
+
+ private:
+  virtual ~NamedPipeInfo();
+
+  /**
+   * DoRead/DoWrite starts a read/write call synchronously or asynchronously
+   * depending on |mNonblocking|. In blocking mode, they return when the action
+   * has been done and in non-blocking mode it returns the number of bytes that
+   * were read/written if the operation is done immediately. If it takes some
+   * time to finish the operation, zero is returned and
+   * DoReadContinue/DoWriteContinue must be called to get async I/O result.
+   */
+  int32_t DoRead();
+  int32_t DoReadContinue();
+  int32_t DoWrite();
+  int32_t DoWriteContinue();
+
+  /**
+   * There was a write size limitation of named pipe,
+   * see https://support.microsoft.com/en-us/kb/119218 for more information.
+   * The limitation no longer exists, so feel free to change the value.
+   */
+  static const uint32_t kBufferSize = 65536;
+
+  nsCOMPtr<nsINamedPipeService> mNamedPipeService;
+
+  HANDLE mPipe;                 // the handle to the named pipe.
+  OVERLAPPED mReadOverlapped;   // used for asynchronous read operations.
+  OVERLAPPED mWriteOverlapped;  // used for asynchronous write operations.
+
+  uint8_t mReadBuffer[kBufferSize];  // octets read from pipe.
+
+  /**
+   * These indicates the [begin, end) position of the data in the buffer.
+   */
+  DWORD mReadBegin;
+  DWORD mReadEnd;
+
+  bool mHasPendingRead;  // previous asynchronous read is not finished yet.
+
+  uint8_t mWriteBuffer[kBufferSize];  // octets to be written to pipe.
+
+  /**
+   * These indicates the [begin, end) position of the data in the buffer.
+   */
+  DWORD mWriteBegin;  // how many bytes are already written.
+  DWORD mWriteEnd;    // valid amount of data in the buffer.
+
+  bool mHasPendingWrite;  // previous asynchronous write is not finished yet.
+
+  /**
+   * current blocking mode is non-blocking or not, accessed only in socket
+   * thread.
+   */
+  bool mNonblocking;
+
+  Atomic<DWORD> mErrorCode;  // error code from Named Pipe Service.
+};
+
+NS_IMPL_ISUPPORTS(NamedPipeInfo, nsINamedPipeDataObserver)
+
+NamedPipeInfo::NamedPipeInfo()
+    : mNamedPipeService(NamedPipeService::GetOrCreate()),
+      mPipe(INVALID_HANDLE_VALUE),
+      mReadBegin(0),
+      mReadEnd(0),
+      mHasPendingRead(false),
+      mWriteBegin(0),
+      mWriteEnd(0),
+      mHasPendingWrite(false),
+      mNonblocking(true),
+      mErrorCode(0) {
+  MOZ_ASSERT(mNamedPipeService);
+
+  ZeroMemory(&mReadOverlapped, sizeof(OVERLAPPED));
+  ZeroMemory(&mWriteOverlapped, sizeof(OVERLAPPED));
+}
+
+NamedPipeInfo::~NamedPipeInfo() { MOZ_ASSERT(!mPipe); }
+
+// nsINamedPipeDataObserver
+
+NS_IMETHODIMP
+NamedPipeInfo::OnDataAvailable(uint32_t aBytesTransferred, void* aOverlapped) {
+  DebugOnly<bool> isOnPipeServiceThread;
+  MOZ_ASSERT(NS_SUCCEEDED(mNamedPipeService->IsOnCurrentThread(
+                 &isOnPipeServiceThread)) &&
+             isOnPipeServiceThread);
+
+  if (aOverlapped == &mReadOverlapped) {
+    LOG_NPIO_DEBUG("[%s] %p read %d bytes", __func__, this, aBytesTransferred);
+  } else if (aOverlapped == &mWriteOverlapped) {
+    LOG_NPIO_DEBUG("[%s] %p write %d bytes", __func__, this, aBytesTransferred);
+  } else {
+    MOZ_ASSERT(false, "invalid callback");
+    mErrorCode = ERROR_INVALID_DATA;
+    return NS_ERROR_FAILURE;
+  }
+
+  mErrorCode = ERROR_SUCCESS;
+
+  // dispatch an empty event to trigger STS thread
+  gSocketTransportService->Dispatch(
+      NS_NewRunnableFunction("NamedPipeInfo::OnDataAvailable", [] {}),
+      NS_DISPATCH_NORMAL);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+NamedPipeInfo::OnError(uint32_t aError, void* aOverlapped) {
+  DebugOnly<bool> isOnPipeServiceThread;
+  MOZ_ASSERT(NS_SUCCEEDED(mNamedPipeService->IsOnCurrentThread(
+                 &isOnPipeServiceThread)) &&
+             isOnPipeServiceThread);
+
+  LOG_NPIO_ERROR("[%s] error code=%d", __func__, aError);
+  mErrorCode = aError;
+
+  // dispatch an empty event to trigger STS thread
+  gSocketTransportService->Dispatch(
+      NS_NewRunnableFunction("NamedPipeInfo::OnError", [] {}),
+      NS_DISPATCH_NORMAL);
+
+  return NS_OK;
+}
+
+// Named pipe operations
+
+nsresult NamedPipeInfo::Connect(const nsAString& aPath) {
+  MOZ_ASSERT(OnSocketThread(), "not on socket thread");
+
+  HANDLE pipe =
+      CreateFileW(PromiseFlatString(aPath).get(), GENERIC_READ | GENERIC_WRITE,
+                  FILE_SHARE_READ | FILE_SHARE_WRITE, nullptr, OPEN_EXISTING,
+                  FILE_FLAG_OVERLAPPED, nullptr);
+
+  if (pipe == INVALID_HANDLE_VALUE) {
+    LOG_NPIO_ERROR("[%p] CreateFile error (%lu)", this, GetLastError());
+    return NS_ERROR_FAILURE;
+  }
+
+  DWORD pipeMode = PIPE_READMODE_MESSAGE;
+  if (!SetNamedPipeHandleState(pipe, &pipeMode, nullptr, nullptr)) {
+    LOG_NPIO_ERROR("[%p] SetNamedPipeHandleState error (%lu)", this,
+                   GetLastError());
+    CloseHandle(pipe);
+    return NS_ERROR_FAILURE;
+  }
+
+  nsresult rv = mNamedPipeService->AddDataObserver(pipe, this);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    CloseHandle(pipe);
+    return rv;
+  }
+
+  HANDLE readEvent = CreateEventA(nullptr, TRUE, TRUE, "NamedPipeRead");
+  if (NS_WARN_IF(!readEvent || readEvent == INVALID_HANDLE_VALUE)) {
+    CloseHandle(pipe);
+    return NS_ERROR_FAILURE;
+  }
+
+  HANDLE writeEvent = CreateEventA(nullptr, TRUE, TRUE, "NamedPipeWrite");
+  if (NS_WARN_IF(!writeEvent || writeEvent == INVALID_HANDLE_VALUE)) {
+    CloseHandle(pipe);
+    CloseHandle(readEvent);
+    return NS_ERROR_FAILURE;
+  }
+
+  mPipe = pipe;
+  mReadOverlapped.hEvent = readEvent;
+  mWriteOverlapped.hEvent = writeEvent;
+  return NS_OK;
+}
+
+nsresult NamedPipeInfo::Disconnect() {
+  MOZ_ASSERT(OnSocketThread(), "not on socket thread");
+
+  nsresult rv = mNamedPipeService->RemoveDataObserver(mPipe, this);
+  Unused << NS_WARN_IF(NS_FAILED(rv));
+
+  mPipe = nullptr;
+
+  if (mReadOverlapped.hEvent &&
+      mReadOverlapped.hEvent != INVALID_HANDLE_VALUE) {
+    CloseHandle(mReadOverlapped.hEvent);
+    mReadOverlapped.hEvent = nullptr;
+  }
+
+  if (mWriteOverlapped.hEvent &&
+      mWriteOverlapped.hEvent != INVALID_HANDLE_VALUE) {
+    CloseHandle(mWriteOverlapped.hEvent);
+    mWriteOverlapped.hEvent = nullptr;
+  }
+
+  return rv;
+}
+
+int32_t NamedPipeInfo::Read(void* aBuffer, int32_t aSize) {
+  MOZ_ASSERT(OnSocketThread(), "not on socket thread");
+
+  int32_t bytesRead = Peek(aBuffer, aSize);
+
+  if (bytesRead > 0) {
+    mReadBegin += bytesRead;
+  }
+
+  return bytesRead;
+}
+
+int32_t NamedPipeInfo::Write(const void* aBuffer, int32_t aSize) {
+  MOZ_ASSERT(OnSocketThread(), "not on socket thread");
+  MOZ_ASSERT(mWriteBegin <= mWriteEnd);
+
+  if (!IsConnected()) {
+    // pipe unconnected
+    PR_SetError(PR_NOT_CONNECTED_ERROR, 0);
+    return -1;
+  }
+
+  if (mWriteBegin == mWriteEnd) {
+    mWriteBegin = mWriteEnd = 0;
+  }
+
+  int32_t bytesToWrite =
+      std::min<int32_t>(aSize, sizeof(mWriteBuffer) - mWriteEnd);
+  MOZ_ASSERT(bytesToWrite >= 0);
+
+  if (bytesToWrite == 0) {
+    PR_SetError(IsNonblocking() ? PR_WOULD_BLOCK_ERROR : PR_IO_PENDING_ERROR,
+                0);
+    return -1;
+  }
+
+  memcpy(&mWriteBuffer[mWriteEnd], aBuffer, bytesToWrite);
+  mWriteEnd += bytesToWrite;
+
+  /**
+   * Triggers internal write operation by calling |GetPollFlags|.
+   * This is required for callers that use blocking I/O because they don't call
+   * |GetPollFlags| to write data, but this also works for non-blocking I/O.
+   */
+  int16_t outFlag;
+  GetPollFlags(PR_POLL_WRITE, &outFlag);
+
+  return bytesToWrite;
+}
+
+uint32_t NamedPipeInfo::Peek(void* aBuffer, int32_t aSize) {
+  MOZ_ASSERT(OnSocketThread(), "not on socket thread");
+  MOZ_ASSERT(mReadBegin <= mReadEnd);
+
+  if (!IsConnected()) {
+    // pipe unconnected
+    PR_SetError(PR_NOT_CONNECTED_ERROR, 0);
+    return -1;
+  }
+
+  /**
+   * If there's nothing in the read buffer, try to trigger internal read
+   * operation by calling |GetPollFlags|. This is required for callers that
+   * use blocking I/O because they don't call |GetPollFlags| to read data,
+   * but this also works for non-blocking I/O.
+   */
+  if (!Available()) {
+    int16_t outFlag;
+    GetPollFlags(PR_POLL_READ, &outFlag);
+
+    if (!(outFlag & PR_POLL_READ)) {
+      PR_SetError(IsNonblocking() ? PR_WOULD_BLOCK_ERROR : PR_IO_PENDING_ERROR,
+                  0);
+      return -1;
+    }
+  }
+
+  // Available() can't return more than what fits to the buffer at the read
+  // offset.
+  int32_t bytesRead = std::min<int32_t>(aSize, Available());
+  MOZ_ASSERT(bytesRead >= 0);
+  MOZ_ASSERT(mReadBegin + bytesRead <= mReadEnd);
+  memcpy(aBuffer, &mReadBuffer[mReadBegin], bytesRead);
+  return bytesRead;
+}
+
+int32_t NamedPipeInfo::Available() const {
+  MOZ_ASSERT(OnSocketThread(), "not on socket thread");
+  MOZ_ASSERT(mReadBegin <= mReadEnd);
+  MOZ_ASSERT(mReadEnd - mReadBegin <= 0x7FFFFFFF);  // no more than int32_max
+  return mReadEnd - mReadBegin;
+}
+
+bool NamedPipeInfo::Sync(uint32_t aTimeout) {
+  MOZ_ASSERT(OnSocketThread(), "not on socket thread");
+  if (!mHasPendingWrite) {
+    return true;
+  }
+  return WaitForSingleObject(mWriteOverlapped.hEvent, aTimeout) ==
+         WAIT_OBJECT_0;
+}
+
+void NamedPipeInfo::SetNonblocking(bool nonblocking) {
+  MOZ_ASSERT(OnSocketThread(), "not on socket thread");
+  mNonblocking = nonblocking;
+}
+
+bool NamedPipeInfo::IsConnected() const {
+  MOZ_ASSERT(OnSocketThread(), "not on socket thread");
+  return mPipe && mPipe != INVALID_HANDLE_VALUE;
+}
+
+bool NamedPipeInfo::IsNonblocking() const {
+  MOZ_ASSERT(OnSocketThread(), "not on socket thread");
+  return mNonblocking;
+}
+
+HANDLE
+NamedPipeInfo::GetHandle() const {
+  MOZ_ASSERT(OnSocketThread(), "not on socket thread");
+  return mPipe;
+}
+
+int16_t NamedPipeInfo::GetPollFlags(int16_t aInFlags, int16_t* aOutFlags) {
+  MOZ_ASSERT(OnSocketThread(), "not on socket thread");
+
+  *aOutFlags = 0;
+
+  if (aInFlags & PR_POLL_READ) {
+    int32_t bytesToRead = 0;
+    if (mReadBegin < mReadEnd) {  // data in buffer and is ready to be read
+      bytesToRead = Available();
+    } else if (mHasPendingRead) {  // nonblocking I/O and has pending task
+      bytesToRead = DoReadContinue();
+    } else {  // read bufer is empty.
+      bytesToRead = DoRead();
+    }
+
+    if (bytesToRead > 0) {
+      *aOutFlags |= PR_POLL_READ;
+    } else if (bytesToRead < 0) {
+      *aOutFlags |= PR_POLL_ERR;
+    }
+  }
+
+  if (aInFlags & PR_POLL_WRITE) {
+    int32_t bytesWritten = 0;
+    if (mHasPendingWrite) {  // nonblocking I/O and has pending task.
+      bytesWritten = DoWriteContinue();
+    } else if (mWriteBegin < mWriteEnd) {  // data in buffer, ready to write
+      bytesWritten = DoWrite();
+    } else {  // write buffer is empty.
+      *aOutFlags |= PR_POLL_WRITE;
+    }
+
+    if (bytesWritten < 0) {
+      *aOutFlags |= PR_POLL_ERR;
+    } else if (bytesWritten && !mHasPendingWrite && mWriteBegin == mWriteEnd) {
+      *aOutFlags |= PR_POLL_WRITE;
+    }
+  }
+
+  return *aOutFlags;
+}
+
+// @return: data has been read and is available
+int32_t NamedPipeInfo::DoRead() {
+  MOZ_ASSERT(OnSocketThread(), "not on socket thread");
+  MOZ_ASSERT(!mHasPendingRead);
+  MOZ_ASSERT(mReadBegin == mReadEnd);  // the buffer should be empty
+
+  mReadBegin = 0;
+  mReadEnd = 0;
+
+  BOOL success = ReadFile(mPipe, mReadBuffer, sizeof(mReadBuffer), &mReadEnd,
+                          IsNonblocking() ? &mReadOverlapped : nullptr);
+
+  if (success) {
+    LOG_NPIO_DEBUG("[%s][%p] %lu bytes read", __func__, this, mReadEnd);
+    return mReadEnd;
+  }
+
+  switch (GetLastError()) {
+    case ERROR_MORE_DATA:  // has more data to read
+      mHasPendingRead = true;
+      return DoReadContinue();
+
+    case ERROR_IO_PENDING:  // read is pending
+      mHasPendingRead = true;
+      break;
+
+    default:
+      LOG_NPIO_ERROR("[%s] ReadFile failed (%lu)", __func__, GetLastError());
+      Disconnect();
+      PR_SetError(PR_IO_ERROR, 0);
+      return -1;
+  }
+
+  return 0;
+}
+
+int32_t NamedPipeInfo::DoReadContinue() {
+  MOZ_ASSERT(OnSocketThread(), "not on socket thread");
+  MOZ_ASSERT(mHasPendingRead);
+  MOZ_ASSERT(mReadBegin == 0 && mReadEnd == 0);
+
+  BOOL success;
+  success = GetOverlappedResult(mPipe, &mReadOverlapped, &mReadEnd, FALSE);
+  if (success) {
+    mHasPendingRead = false;
+    if (mReadEnd == 0) {
+      Disconnect();
+      PR_SetError(PR_NOT_CONNECTED_ERROR, 0);
+      return -1;
+    }
+
+    LOG_NPIO_DEBUG("[%s][%p] %lu bytes read", __func__, this, mReadEnd);
+    return mReadEnd;
+  }
+
+  switch (GetLastError()) {
+    case ERROR_MORE_DATA:
+      mHasPendingRead = false;
+      LOG_NPIO_DEBUG("[%s][%p] %lu bytes read", __func__, this, mReadEnd);
+      return mReadEnd;
+    case ERROR_IO_INCOMPLETE:  // still in progress
+      break;
+    default:
+      LOG_NPIO_ERROR("[%s]: GetOverlappedResult failed (%lu)", __func__,
+                     GetLastError());
+      Disconnect();
+      PR_SetError(PR_IO_ERROR, 0);
+      return -1;
+  }
+
+  return 0;
+}
+
+int32_t NamedPipeInfo::DoWrite() {
+  MOZ_ASSERT(OnSocketThread(), "not on socket thread");
+  MOZ_ASSERT(!mHasPendingWrite);
+  MOZ_ASSERT(mWriteBegin < mWriteEnd);
+
+  DWORD bytesWritten = 0;
+  BOOL success =
+      WriteFile(mPipe, &mWriteBuffer[mWriteBegin], mWriteEnd - mWriteBegin,
+                &bytesWritten, IsNonblocking() ? &mWriteOverlapped : nullptr);
+
+  if (success) {
+    mWriteBegin += bytesWritten;
+    LOG_NPIO_DEBUG("[%s][%p] %lu bytes written", __func__, this, bytesWritten);
+    return bytesWritten;
+  }
+
+  if (GetLastError() != ERROR_IO_PENDING) {
+    LOG_NPIO_ERROR("[%s] WriteFile failed (%lu)", __func__, GetLastError());
+    Disconnect();
+    PR_SetError(PR_IO_ERROR, 0);
+    return -1;
+  }
+
+  mHasPendingWrite = true;
+
+  return 0;
+}
+
+int32_t NamedPipeInfo::DoWriteContinue() {
+  MOZ_ASSERT(OnSocketThread(), "not on socket thread");
+  MOZ_ASSERT(mHasPendingWrite);
+
+  DWORD bytesWritten = 0;
+  BOOL success =
+      GetOverlappedResult(mPipe, &mWriteOverlapped, &bytesWritten, FALSE);
+
+  if (!success) {
+    if (GetLastError() == ERROR_IO_INCOMPLETE) {
+      // still in progress
+      return 0;
+    }
+
+    LOG_NPIO_ERROR("[%s] GetOverlappedResult failed (%lu)", __func__,
+                   GetLastError());
+    Disconnect();
+    PR_SetError(PR_IO_ERROR, 0);
+    return -1;
+  }
+
+  mHasPendingWrite = false;
+  mWriteBegin += bytesWritten;
+  LOG_NPIO_DEBUG("[%s][%p] %lu bytes written", __func__, this, bytesWritten);
+  return bytesWritten;
+}
+
+static inline NamedPipeInfo* GetNamedPipeInfo(PRFileDesc* aFd) {
+  MOZ_ASSERT(OnSocketThread(), "not on socket thread");
+  MOZ_DIAGNOSTIC_ASSERT(aFd);
+  MOZ_DIAGNOSTIC_ASSERT(aFd->secret);
+  MOZ_DIAGNOSTIC_ASSERT(PR_GetLayersIdentity(aFd) == nsNamedPipeLayerIdentity);
+
+  if (!aFd || !aFd->secret ||
+      PR_GetLayersIdentity(aFd) != nsNamedPipeLayerIdentity) {
+    LOG_NPIO_ERROR("cannot get named pipe info");
+    return nullptr;
+  }
+
+  return reinterpret_cast<NamedPipeInfo*>(aFd->secret);
+}
+
+static PRStatus nsNamedPipeConnect(PRFileDesc* aFd, const PRNetAddr* aAddr,
+                                   PRIntervalTime aTimeout) {
+  MOZ_ASSERT(OnSocketThread(), "not on socket thread");
+
+  NamedPipeInfo* info = GetNamedPipeInfo(aFd);
+  if (!info) {
+    PR_SetError(PR_BAD_DESCRIPTOR_ERROR, 0);
+    return PR_FAILURE;
+  }
+
+  nsAutoString path;
+  if (NS_FAILED(NS_CopyNativeToUnicode(nsDependentCString(aAddr->local.path),
+                                       path))) {
+    PR_SetError(PR_OUT_OF_MEMORY_ERROR, 0);
+    return PR_FAILURE;
+  }
+  if (NS_WARN_IF(NS_FAILED(info->Connect(path)))) {
+    return PR_FAILURE;
+  }
+
+  return PR_SUCCESS;
+}
+
+static PRStatus nsNamedPipeConnectContinue(PRFileDesc* aFd, PRInt16 aOutFlags) {
+  MOZ_ASSERT(OnSocketThread(), "not on socket thread");
+
+  return PR_SUCCESS;
+}
+
+static PRStatus nsNamedPipeClose(PRFileDesc* aFd) {
+  MOZ_ASSERT(OnSocketThread(), "not on socket thread");
+
+  if (aFd->secret && PR_GetLayersIdentity(aFd) == nsNamedPipeLayerIdentity) {
+    RefPtr<NamedPipeInfo> info = dont_AddRef(GetNamedPipeInfo(aFd));
+    info->Disconnect();
+    aFd->secret = nullptr;
+    aFd->identity = PR_INVALID_IO_LAYER;
+  }
+
+  MOZ_ASSERT(!aFd->lower);
+  PR_Free(aFd);  // PRFileDescs are allocated with PR_Malloc().
+
+  return PR_SUCCESS;
+}
+
+static PRInt32 nsNamedPipeSend(PRFileDesc* aFd, const void* aBuffer,
+                               PRInt32 aAmount, PRIntn aFlags,
+                               PRIntervalTime aTimeout) {
+  MOZ_ASSERT(OnSocketThread(), "not on socket thread");
+
+  Unused << aFlags;
+  Unused << aTimeout;
+
+  NamedPipeInfo* info = GetNamedPipeInfo(aFd);
+  if (!info) {
+    PR_SetError(PR_BAD_DESCRIPTOR_ERROR, 0);
+    return -1;
+  }
+  return info->Write(aBuffer, aAmount);
+}
+
+static PRInt32 nsNamedPipeRecv(PRFileDesc* aFd, void* aBuffer, PRInt32 aAmount,
+                               PRIntn aFlags, PRIntervalTime aTimeout) {
+  MOZ_ASSERT(OnSocketThread(), "not on socket thread");
+
+  Unused << aTimeout;
+
+  NamedPipeInfo* info = GetNamedPipeInfo(aFd);
+  if (!info) {
+    PR_SetError(PR_BAD_DESCRIPTOR_ERROR, 0);
+    return -1;
+  }
+
+  if (aFlags) {
+    if (aFlags != PR_MSG_PEEK) {
+      PR_SetError(PR_UNKNOWN_ERROR, 0);
+      return -1;
+    }
+    return info->Peek(aBuffer, aAmount);
+  }
+
+  return info->Read(aBuffer, aAmount);
+}
+
+static inline PRInt32 nsNamedPipeRead(PRFileDesc* aFd, void* aBuffer,
+                                      PRInt32 aAmount) {
+  MOZ_ASSERT(OnSocketThread(), "not on socket thread");
+
+  NamedPipeInfo* info = GetNamedPipeInfo(aFd);
+  if (!info) {
+    PR_SetError(PR_BAD_DESCRIPTOR_ERROR, 0);
+    return -1;
+  }
+  return info->Read(aBuffer, aAmount);
+}
+
+static inline PRInt32 nsNamedPipeWrite(PRFileDesc* aFd, const void* aBuffer,
+                                       PRInt32 aAmount) {
+  MOZ_ASSERT(OnSocketThread(), "not on socket thread");
+
+  NamedPipeInfo* info = GetNamedPipeInfo(aFd);
+  if (!info) {
+    PR_SetError(PR_BAD_DESCRIPTOR_ERROR, 0);
+    return -1;
+  }
+  return info->Write(aBuffer, aAmount);
+}
+
+static PRInt32 nsNamedPipeAvailable(PRFileDesc* aFd) {
+  MOZ_ASSERT(OnSocketThread(), "not on socket thread");
+
+  NamedPipeInfo* info = GetNamedPipeInfo(aFd);
+  if (!info) {
+    PR_SetError(PR_BAD_DESCRIPTOR_ERROR, 0);
+    return -1;
+  }
+  return static_cast<PRInt32>(info->Available());
+}
+
+static PRInt64 nsNamedPipeAvailable64(PRFileDesc* aFd) {
+  MOZ_ASSERT(OnSocketThread(), "not on socket thread");
+
+  NamedPipeInfo* info = GetNamedPipeInfo(aFd);
+  if (!info) {
+    PR_SetError(PR_BAD_DESCRIPTOR_ERROR, 0);
+    return -1;
+  }
+  return static_cast<PRInt64>(info->Available());
+}
+
+static PRStatus nsNamedPipeSync(PRFileDesc* aFd) {
+  MOZ_ASSERT(OnSocketThread(), "not on socket thread");
+
+  NamedPipeInfo* info = GetNamedPipeInfo(aFd);
+  if (!info) {
+    PR_SetError(PR_BAD_DESCRIPTOR_ERROR, 0);
+    return PR_FAILURE;
+  }
+  return info->Sync(0) ? PR_SUCCESS : PR_FAILURE;
+}
+
+static PRInt16 nsNamedPipePoll(PRFileDesc* aFd, PRInt16 aInFlags,
+                               PRInt16* aOutFlags) {
+  MOZ_ASSERT(OnSocketThread(), "not on socket thread");
+
+  NamedPipeInfo* info = GetNamedPipeInfo(aFd);
+  if (!info) {
+    PR_SetError(PR_BAD_DESCRIPTOR_ERROR, 0);
+    return 0;
+  }
+  return info->GetPollFlags(aInFlags, aOutFlags);
+}
+
+// FIXME: remove socket option functions?
+static PRStatus nsNamedPipeGetSocketOption(PRFileDesc* aFd,
+                                           PRSocketOptionData* aData) {
+  MOZ_ASSERT(OnSocketThread(), "not on socket thread");
+
+  MOZ_ASSERT(aFd);
+  MOZ_ASSERT(aData);
+
+  switch (aData->option) {
+    case PR_SockOpt_Nonblocking:
+      aData->value.non_blocking =
+          GetNamedPipeInfo(aFd)->IsNonblocking() ? PR_TRUE : PR_FALSE;
+      break;
+    case PR_SockOpt_Keepalive:
+      aData->value.keep_alive = PR_TRUE;
+      break;
+    case PR_SockOpt_NoDelay:
+      aData->value.no_delay = PR_TRUE;
+      break;
+    default:
+      PR_SetError(PR_INVALID_METHOD_ERROR, 0);
+      return PR_FAILURE;
+  }
+
+  return PR_SUCCESS;
+}
+
+static PRStatus nsNamedPipeSetSocketOption(PRFileDesc* aFd,
+                                           const PRSocketOptionData* aData) {
+  MOZ_ASSERT(OnSocketThread(), "not on socket thread");
+
+  MOZ_ASSERT(aFd);
+  MOZ_ASSERT(aData);
+
+  switch (aData->option) {
+    case PR_SockOpt_Nonblocking:
+      GetNamedPipeInfo(aFd)->SetNonblocking(aData->value.non_blocking);
+      break;
+    case PR_SockOpt_Keepalive:
+    case PR_SockOpt_NoDelay:
+      break;
+    default:
+      PR_SetError(PR_INVALID_METHOD_ERROR, 0);
+      return PR_FAILURE;
+  }
+
+  return PR_SUCCESS;
+}
+
+static void Initialize() {
+  MOZ_ASSERT(OnSocketThread(), "not on socket thread");
+
+  static bool initialized = false;
+  if (initialized) {
+    return;
+  }
+
+  nsNamedPipeLayerIdentity = PR_GetUniqueIdentity("Named Pipe layer");
+  nsNamedPipeLayerMethods = *PR_GetDefaultIOMethods();
+  nsNamedPipeLayerMethods.close = nsNamedPipeClose;
+  nsNamedPipeLayerMethods.read = nsNamedPipeRead;
+  nsNamedPipeLayerMethods.write = nsNamedPipeWrite;
+  nsNamedPipeLayerMethods.available = nsNamedPipeAvailable;
+  nsNamedPipeLayerMethods.available64 = nsNamedPipeAvailable64;
+  nsNamedPipeLayerMethods.fsync = nsNamedPipeSync;
+  nsNamedPipeLayerMethods.connect = nsNamedPipeConnect;
+  nsNamedPipeLayerMethods.recv = nsNamedPipeRecv;
+  nsNamedPipeLayerMethods.send = nsNamedPipeSend;
+  nsNamedPipeLayerMethods.poll = nsNamedPipePoll;
+  nsNamedPipeLayerMethods.getsocketoption = nsNamedPipeGetSocketOption;
+  nsNamedPipeLayerMethods.setsocketoption = nsNamedPipeSetSocketOption;
+  nsNamedPipeLayerMethods.connectcontinue = nsNamedPipeConnectContinue;
+
+  initialized = true;
+}
+
+bool IsNamedPipePath(const nsACString& aPath) {
+  return StringBeginsWith(aPath, "\\\\.\\pipe\\"_ns);
+}
+
+PRFileDesc* CreateNamedPipeLayer() {
+  MOZ_ASSERT(OnSocketThread(), "not on socket thread");
+  Initialize();
+
+  PRFileDesc* layer =
+      PR_CreateIOLayerStub(nsNamedPipeLayerIdentity, &nsNamedPipeLayerMethods);
+  if (NS_WARN_IF(!layer)) {
+    LOG_NPIO_ERROR("CreateNamedPipeLayer() failed.");
+    return nullptr;
+  }
+
+  RefPtr<NamedPipeInfo> info = new NamedPipeInfo();
+  layer->secret = reinterpret_cast<PRFilePrivate*>(info.forget().take());
+
+  return layer;
+}
+
+}  // namespace net
+}  // namespace mozilla
diff --git a/netwerk/socket/nsNamedPipeIOLayer.h b/netwerk/socket/nsNamedPipeIOLayer.h
new file mode 100644
index 0000000000..87598324b6
--- /dev/null
+++ b/netwerk/socket/nsNamedPipeIOLayer.h
@@ -0,0 +1,24 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_netwerk_socket_nsNamedPipeIOLayer_h
+#define mozilla_netwerk_socket_nsNamedPipeIOLayer_h
+
+#include "nscore.h"
+#include "nsStringFwd.h"
+#include "prio.h"
+
+namespace mozilla {
+namespace net {
+
+bool IsNamedPipePath(const nsACString& aPath);
+PRFileDesc* CreateNamedPipeLayer();
+
+extern PRDescIdentity nsNamedPipeLayerIdentity;
+
+}  // namespace net
+}  // namespace mozilla
+
+#endif  // mozilla_netwerk_socket_nsNamedPipeIOLayer_h
diff --git a/netwerk/socket/nsNamedPipeService.cpp b/netwerk/socket/nsNamedPipeService.cpp
new file mode 100644
index 0000000000..4cf41680d5
--- /dev/null
+++ b/netwerk/socket/nsNamedPipeService.cpp
@@ -0,0 +1,319 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/Services.h"
+#include "nsCOMPtr.h"
+#include "nsIObserverService.h"
+#include "nsNamedPipeService.h"
+#include "nsNetCID.h"
+#include "nsThreadUtils.h"
+#include "mozilla/ClearOnShutdown.h"
+#include "mozilla/Logging.h"
+
+namespace mozilla {
+namespace net {
+
+static mozilla::LazyLogModule gNamedPipeServiceLog("NamedPipeWin");
+#define LOG_NPS_DEBUG(...) \
+  MOZ_LOG(gNamedPipeServiceLog, mozilla::LogLevel::Debug, (__VA_ARGS__))
+#define LOG_NPS_ERROR(...) \
+  MOZ_LOG(gNamedPipeServiceLog, mozilla::LogLevel::Error, (__VA_ARGS__))
+
+StaticRefPtr<NamedPipeService> NamedPipeService::gSingleton;
+
+NS_IMPL_ISUPPORTS(NamedPipeService, nsINamedPipeService, nsIObserver,
+                  nsIRunnable)
+
+NamedPipeService::NamedPipeService()
+    : mIocp(nullptr), mIsShutdown(false), mLock("NamedPipeServiceLock") {}
+
+nsresult NamedPipeService::Init() {
+  MOZ_ASSERT(!mIsShutdown);
+
+  nsresult rv;
+
+  // nsIObserverService must be accessed in main thread.
+  // register shutdown event to stop NamedPipeSrv thread.
+  nsCOMPtr<nsIObserver> self(this);
+  nsCOMPtr<nsIRunnable> r = NS_NewRunnableFunction(
+      "NamedPipeService::Init", [self = std::move(self)]() -> void {
+        MOZ_ASSERT(NS_IsMainThread());
+
+        nsCOMPtr<nsIObserverService> svc =
+            mozilla::services::GetObserverService();
+
+        if (NS_WARN_IF(!svc)) {
+          return;
+        }
+
+        if (NS_WARN_IF(NS_FAILED(svc->AddObserver(
+                self, NS_XPCOM_SHUTDOWN_OBSERVER_ID, false)))) {
+          return;
+        }
+      });
+
+  if (NS_IsMainThread()) {
+    rv = r->Run();
+  } else {
+    rv = NS_DispatchToMainThread(r);
+  }
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  mIocp = CreateIoCompletionPort(INVALID_HANDLE_VALUE, nullptr, 0, 1);
+  if (NS_WARN_IF(!mIocp || mIocp == INVALID_HANDLE_VALUE)) {
+    Shutdown();
+    return NS_ERROR_FAILURE;
+  }
+
+  rv = NS_NewNamedThread("NamedPipeSrv", getter_AddRefs(mThread));
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    Shutdown();
+    return rv;
+  }
+
+  return NS_OK;
+}
+
+// static
+already_AddRefed<nsINamedPipeService> NamedPipeService::GetOrCreate() {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  RefPtr<NamedPipeService> inst;
+  if (gSingleton) {
+    inst = gSingleton;
+  } else {
+    inst = new NamedPipeService();
+    nsresult rv = inst->Init();
+    NS_ENSURE_SUCCESS(rv, nullptr);
+    gSingleton = inst;
+    ClearOnShutdown(&gSingleton);
+  }
+
+  return inst.forget();
+}
+
+void NamedPipeService::Shutdown() {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  // remove observer
+  nsCOMPtr<nsIObserverService> obs = mozilla::services::GetObserverService();
+  if (obs) {
+    obs->RemoveObserver(this, NS_XPCOM_SHUTDOWN_OBSERVER_ID);
+  }
+
+  // stop thread
+  if (mThread && !mIsShutdown) {
+    mIsShutdown = true;
+
+    // invoke ERROR_ABANDONED_WAIT_0 to |GetQueuedCompletionStatus|
+    CloseHandle(mIocp);
+    mIocp = nullptr;
+
+    mThread->Shutdown();
+  }
+
+  // close I/O Completion Port
+  if (mIocp && mIocp != INVALID_HANDLE_VALUE) {
+    CloseHandle(mIocp);
+    mIocp = nullptr;
+  }
+}
+
+void NamedPipeService::RemoveRetiredObjects() {
+  MOZ_ASSERT(NS_GetCurrentThread() == mThread);
+  mLock.AssertCurrentThreadOwns();
+
+  if (!mRetiredHandles.IsEmpty()) {
+    for (auto& handle : mRetiredHandles) {
+      CloseHandle(handle);
+    }
+    mRetiredHandles.Clear();
+  }
+
+  mRetiredObservers.Clear();
+}
+
+/**
+ * Implement nsINamedPipeService
+ */
+
+NS_IMETHODIMP
+NamedPipeService::AddDataObserver(void* aHandle,
+                                  nsINamedPipeDataObserver* aObserver) {
+  if (!aHandle || aHandle == INVALID_HANDLE_VALUE || !aObserver) {
+    return NS_ERROR_ILLEGAL_VALUE;
+  }
+
+  nsresult rv;
+
+  HANDLE h = CreateIoCompletionPort(aHandle, mIocp,
+                                    reinterpret_cast<ULONG_PTR>(aObserver), 1);
+  if (NS_WARN_IF(!h)) {
+    LOG_NPS_ERROR("CreateIoCompletionPort error (%lu)", GetLastError());
+    return NS_ERROR_FAILURE;
+  }
+  if (NS_WARN_IF(h != mIocp)) {
+    LOG_NPS_ERROR(
+        "CreateIoCompletionPort got unexpected value %p (should be %p)", h,
+        mIocp);
+    CloseHandle(h);
+    return NS_ERROR_FAILURE;
+  }
+
+  {
+    MutexAutoLock lock(mLock);
+    MOZ_ASSERT(!mObservers.Contains(aObserver));
+
+    mObservers.AppendElement(aObserver);
+
+    // start event loop
+    if (mObservers.Length() == 1) {
+      rv = mThread->Dispatch(this, NS_DISPATCH_NORMAL);
+      if (NS_WARN_IF(NS_FAILED(rv))) {
+        LOG_NPS_ERROR("Dispatch to thread failed (%08x)", rv);
+        mObservers.Clear();
+        return rv;
+      }
+    }
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+NamedPipeService::RemoveDataObserver(void* aHandle,
+                                     nsINamedPipeDataObserver* aObserver) {
+  MutexAutoLock lock(mLock);
+  mObservers.RemoveElement(aObserver);
+
+  mRetiredHandles.AppendElement(aHandle);
+  mRetiredObservers.AppendElement(aObserver);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+NamedPipeService::IsOnCurrentThread(bool* aRetVal) {
+  MOZ_ASSERT(mThread);
+  MOZ_ASSERT(aRetVal);
+
+  if (!mThread) {
+    *aRetVal = false;
+    return NS_OK;
+  }
+
+  return mThread->IsOnCurrentThread(aRetVal);
+}
+
+/**
+ * Implement nsIObserver
+ */
+
+NS_IMETHODIMP
+NamedPipeService::Observe(nsISupports* aSubject, const char* aTopic,
+                          const char16_t* aData) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (!strcmp(NS_XPCOM_SHUTDOWN_OBSERVER_ID, aTopic)) {
+    Shutdown();
+  }
+
+  return NS_OK;
+}
+
+/**
+ * Implement nsIRunnable
+ */
+
+NS_IMETHODIMP
+NamedPipeService::Run() {
+  MOZ_ASSERT(NS_GetCurrentThread() == mThread);
+  MOZ_ASSERT(mIocp && mIocp != INVALID_HANDLE_VALUE);
+
+  while (!mIsShutdown) {
+    {
+      MutexAutoLock lock(mLock);
+      if (mObservers.IsEmpty()) {
+        LOG_NPS_DEBUG("no observer, stop loop");
+        break;
+      }
+
+      RemoveRetiredObjects();
+    }
+
+    DWORD bytesTransferred = 0;
+    ULONG_PTR key = 0;
+    LPOVERLAPPED overlapped = nullptr;
+    BOOL success =
+        GetQueuedCompletionStatus(mIocp, &bytesTransferred, &key, &overlapped,
+                                  1000);  // timeout, 1s
+    auto err = GetLastError();
+    if (!success) {
+      if (err == WAIT_TIMEOUT) {
+        continue;
+      } else if (err == ERROR_ABANDONED_WAIT_0) {  // mIocp was closed
+        break;
+      } else if (!overlapped) {
+        /**
+         * Did not dequeue a completion packet from the completion port, and
+         * bytesTransferred/key are meaningless.
+         * See remarks of |GetQueuedCompletionStatus| API.
+         */
+
+        LOG_NPS_ERROR("invalid overlapped (%lu)", err);
+        continue;
+      }
+
+      MOZ_ASSERT(key);
+    }
+
+    /**
+     * Windows doesn't provide a method to remove created I/O Completion Port,
+     * all we can do is just close the handle we monitored before.
+     * In some cases, there's race condition that the monitored handle has an
+     * I/O status after the observer is being removed and destroyed.
+     * To avoid changing the ref-count of a dangling pointer, don't use nsCOMPtr
+     * here.
+     */
+    nsINamedPipeDataObserver* target =
+        reinterpret_cast<nsINamedPipeDataObserver*>(key);
+
+    nsCOMPtr<nsINamedPipeDataObserver> obs;
+    {
+      MutexAutoLock lock(mLock);
+
+      auto idx = mObservers.IndexOf(target);
+      if (idx == decltype(mObservers)::NoIndex) {
+        LOG_NPS_ERROR("observer %p not found", target);
+        continue;
+      }
+      obs = target;
+    }
+
+    MOZ_ASSERT(obs.get());
+
+    if (success) {
+      LOG_NPS_DEBUG("OnDataAvailable: obs=%p, bytes=%lu", obs.get(),
+                    bytesTransferred);
+      obs->OnDataAvailable(bytesTransferred, overlapped);
+    } else {
+      LOG_NPS_ERROR("GetQueuedCompletionStatus %p failed, error=%lu", obs.get(),
+                    err);
+      obs->OnError(err, overlapped);
+    }
+  }
+
+  {
+    MutexAutoLock lock(mLock);
+    RemoveRetiredObjects();
+  }
+
+  return NS_OK;
+}
+
+}  // namespace net
+}  // namespace mozilla
diff --git a/netwerk/socket/nsNamedPipeService.h b/netwerk/socket/nsNamedPipeService.h
new file mode 100644
index 0000000000..cbe6ff9631
--- /dev/null
+++ b/netwerk/socket/nsNamedPipeService.h
@@ -0,0 +1,67 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_netwerk_socket_nsNamedPipeService_h
+#define mozilla_netwerk_socket_nsNamedPipeService_h
+
+#include <windows.h>
+#include "mozilla/Atomics.h"
+#include "mozilla/Mutex.h"
+#include "nsINamedPipeService.h"
+#include "nsIObserver.h"
+#include "nsIRunnable.h"
+#include "nsIThread.h"
+#include "nsTArray.h"
+#include "mozilla/StaticPtr.h"
+
+namespace mozilla {
+namespace net {
+
+class NamedPipeService final : public nsINamedPipeService,
+                               public nsIObserver,
+                               public nsIRunnable {
+ public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSINAMEDPIPESERVICE
+  NS_DECL_NSIOBSERVER
+  NS_DECL_NSIRUNNABLE
+
+  static already_AddRefed<nsINamedPipeService> GetOrCreate();
+
+ private:
+  explicit NamedPipeService();
+  virtual ~NamedPipeService() = default;
+
+  nsresult Init();
+
+  void Shutdown();
+  void RemoveRetiredObjects();
+
+  HANDLE mIocp;  // native handle to the I/O completion port.
+  Atomic<bool>
+      mIsShutdown;  // set to true to stop the event loop running by mThread.
+  nsCOMPtr<nsIThread> mThread;  // worker thread to get I/O events.
+
+  /**
+   * The observers is maintained in |mObservers| to ensure valid life-cycle.
+   * We don't remove the handle and corresponding observer directly, instead
+   * the handle and observer into a "retired" list and close/remove them in
+   * the worker thread to avoid a race condition that might happen between
+   * |CloseHandle()| and |GetQueuedCompletionStatus()|.
+   */
+  Mutex mLock MOZ_UNANNOTATED;
+  nsTArray<nsCOMPtr<nsINamedPipeDataObserver>>
+      mObservers;  // protected by mLock
+  nsTArray<nsCOMPtr<nsINamedPipeDataObserver>>
+      mRetiredObservers;             // protected by mLock
+  nsTArray<HANDLE> mRetiredHandles;  // protected by mLock
+
+  static StaticRefPtr<NamedPipeService> gSingleton;
+};
+
+}  // namespace net
+}  // namespace mozilla
+
+#endif  // mozilla_netwerk_socket_nsNamedPipeService_h
diff --git a/netwerk/socket/nsSOCKSIOLayer.cpp b/netwerk/socket/nsSOCKSIOLayer.cpp
new file mode 100644
index 0000000000..e47bc628bd
--- /dev/null
+++ b/netwerk/socket/nsSOCKSIOLayer.cpp
@@ -0,0 +1,1471 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set expandtab ts=4 sw=2 sts=2 cin: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nspr.h"
+#include "private/pprio.h"
+#include "nsString.h"
+#include "nsCRT.h"
+
+#include "nsIDNSService.h"
+#include "nsIDNSRecord.h"
+#include "nsISocketProvider.h"
+#include "nsNamedPipeIOLayer.h"
+#include "nsSOCKSIOLayer.h"
+#include "nsNetCID.h"
+#include "nsIDNSListener.h"
+#include "nsICancelable.h"
+#include "nsThreadUtils.h"
+#include "nsIFile.h"
+#include "nsIFileProtocolHandler.h"
+#include "mozilla/Logging.h"
+#include "mozilla/net/DNS.h"
+#include "mozilla/Unused.h"
+
+using mozilla::LogLevel;
+using namespace mozilla::net;
+
+static PRDescIdentity nsSOCKSIOLayerIdentity;
+static PRIOMethods nsSOCKSIOLayerMethods;
+static bool firstTime = true;
+static bool ipv6Supported = true;
+
+static mozilla::LazyLogModule gSOCKSLog("SOCKS");
+#define LOGDEBUG(args) MOZ_LOG(gSOCKSLog, mozilla::LogLevel::Debug, args)
+#define LOGERROR(args) MOZ_LOG(gSOCKSLog, mozilla::LogLevel::Error, args)
+
+class nsSOCKSSocketInfo : public nsIDNSListener {
+  enum State {
+    SOCKS_INITIAL,
+    SOCKS_DNS_IN_PROGRESS,
+    SOCKS_DNS_COMPLETE,
+    SOCKS_CONNECTING_TO_PROXY,
+    SOCKS4_WRITE_CONNECT_REQUEST,
+    SOCKS4_READ_CONNECT_RESPONSE,
+    SOCKS5_WRITE_AUTH_REQUEST,
+    SOCKS5_READ_AUTH_RESPONSE,
+    SOCKS5_WRITE_USERNAME_REQUEST,
+    SOCKS5_READ_USERNAME_RESPONSE,
+    SOCKS5_WRITE_CONNECT_REQUEST,
+    SOCKS5_READ_CONNECT_RESPONSE_TOP,
+    SOCKS5_READ_CONNECT_RESPONSE_BOTTOM,
+    SOCKS_CONNECTED,
+    SOCKS_FAILED
+  };
+
+  // A buffer of 520 bytes should be enough for any request and response
+  // in case of SOCKS4 as well as SOCKS5
+  static const uint32_t BUFFER_SIZE = 520;
+  static const uint32_t MAX_HOSTNAME_LEN = 255;
+  static const uint32_t MAX_USERNAME_LEN = 255;
+  static const uint32_t MAX_PASSWORD_LEN = 255;
+
+ public:
+  nsSOCKSSocketInfo();
+
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIDNSLISTENER
+
+  void Init(int32_t version, int32_t family, nsIProxyInfo* proxy,
+            const char* destinationHost, uint32_t flags, uint32_t tlsFlags);
+
+  void SetConnectTimeout(PRIntervalTime to);
+  PRStatus DoHandshake(PRFileDesc* fd, int16_t oflags = -1);
+  int16_t GetPollFlags() const;
+  bool IsConnected() const { return mState == SOCKS_CONNECTED; }
+  void ForgetFD() { mFD = nullptr; }
+  void SetNamedPipeFD(PRFileDesc* fd) { mFD = fd; }
+
+  void GetExternalProxyAddr(NetAddr& aExternalProxyAddr);
+  void GetDestinationAddr(NetAddr& aDestinationAddr);
+  void SetDestinationAddr(const NetAddr& aDestinationAddr);
+
+ private:
+  virtual ~nsSOCKSSocketInfo() {
+    ForgetFD();
+    HandshakeFinished();
+  }
+
+  void HandshakeFinished(PRErrorCode err = 0);
+  PRStatus StartDNS(PRFileDesc* fd);
+  PRStatus ConnectToProxy(PRFileDesc* fd);
+  void FixupAddressFamily(PRFileDesc* fd, NetAddr* proxy);
+  PRStatus ContinueConnectingToProxy(PRFileDesc* fd, int16_t oflags);
+  PRStatus WriteV4ConnectRequest();
+  PRStatus ReadV4ConnectResponse();
+  PRStatus WriteV5AuthRequest();
+  PRStatus ReadV5AuthResponse();
+  PRStatus WriteV5UsernameRequest();
+  PRStatus ReadV5UsernameResponse();
+  PRStatus WriteV5ConnectRequest();
+  PRStatus ReadV5AddrTypeAndLength(uint8_t* type, uint32_t* len);
+  PRStatus ReadV5ConnectResponseTop();
+  PRStatus ReadV5ConnectResponseBottom();
+
+  uint8_t ReadUint8();
+  uint16_t ReadUint16();
+  uint32_t ReadUint32();
+  void ReadNetAddr(NetAddr* addr, uint16_t fam);
+  void ReadNetPort(NetAddr* addr);
+
+  void WantRead(uint32_t sz);
+  PRStatus ReadFromSocket(PRFileDesc* fd);
+  PRStatus WriteToSocket(PRFileDesc* fd);
+
+  bool IsLocalProxy() {
+    nsAutoCString proxyHost;
+    mProxy->GetHost(proxyHost);
+    return IsHostLocalTarget(proxyHost);
+  }
+
+  nsresult SetLocalProxyPath(const nsACString& aLocalProxyPath,
+                             NetAddr* aProxyAddr) {
+#ifdef XP_UNIX
+    nsresult rv;
+    MOZ_ASSERT(aProxyAddr);
+
+    nsCOMPtr<nsIProtocolHandler> protocolHandler(
+        do_GetService(NS_NETWORK_PROTOCOL_CONTRACTID_PREFIX "file", &rv));
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+
+    nsCOMPtr<nsIFileProtocolHandler> fileHandler(
+        do_QueryInterface(protocolHandler, &rv));
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+
+    nsCOMPtr<nsIFile> socketFile;
+    rv = fileHandler->GetFileFromURLSpec(aLocalProxyPath,
+                                         getter_AddRefs(socketFile));
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+
+    nsAutoCString path;
+    if (NS_WARN_IF(NS_FAILED(rv = socketFile->GetNativePath(path)))) {
+      return rv;
+    }
+
+    if (sizeof(aProxyAddr->local.path) <= path.Length()) {
+      NS_WARNING("domain socket path too long.");
+      return NS_ERROR_FAILURE;
+    }
+
+    aProxyAddr->raw.family = AF_UNIX;
+    strcpy(aProxyAddr->local.path, path.get());
+
+    return NS_OK;
+#elif defined(XP_WIN)
+    MOZ_ASSERT(aProxyAddr);
+
+    if (sizeof(aProxyAddr->local.path) <= aLocalProxyPath.Length()) {
+      NS_WARNING("pipe path too long.");
+      return NS_ERROR_FAILURE;
+    }
+
+    aProxyAddr->raw.family = AF_LOCAL;
+    strcpy(aProxyAddr->local.path, PromiseFlatCString(aLocalProxyPath).get());
+    return NS_OK;
+#else
+    mozilla::Unused << aLocalProxyPath;
+    mozilla::Unused << aProxyAddr;
+    return NS_ERROR_NOT_IMPLEMENTED;
+#endif
+  }
+
+  bool SetupNamedPipeLayer(PRFileDesc* fd) {
+#if defined(XP_WIN)
+    if (IsLocalProxy()) {
+      // nsSOCKSIOLayer handshaking only works under blocking mode
+      // unfortunately. Remember named pipe's FD to switch between modes.
+      SetNamedPipeFD(fd->lower);
+      return true;
+    }
+#endif
+    return false;
+  }
+
+ private:
+  State mState{SOCKS_INITIAL};
+  uint8_t* mData{nullptr};
+  uint8_t* mDataIoPtr{nullptr};
+  uint32_t mDataLength{0};
+  uint32_t mReadOffset{0};
+  uint32_t mAmountToRead{0};
+  nsCOMPtr<nsIDNSRecord> mDnsRec;
+  nsCOMPtr<nsICancelable> mLookup;
+  nsresult mLookupStatus{NS_ERROR_NOT_INITIALIZED};
+  PRFileDesc* mFD{nullptr};
+
+  nsCString mDestinationHost;
+  nsCOMPtr<nsIProxyInfo> mProxy;
+  int32_t mVersion{-1};  // SOCKS version 4 or 5
+  int32_t mDestinationFamily{AF_INET};
+  uint32_t mFlags{0};
+  uint32_t mTlsFlags{0};
+  NetAddr mInternalProxyAddr;
+  NetAddr mExternalProxyAddr;
+  NetAddr mDestinationAddr;
+  PRIntervalTime mTimeout{PR_INTERVAL_NO_TIMEOUT};
+  nsCString mProxyUsername;  // Cache, from mProxy
+};
+
+nsSOCKSSocketInfo::nsSOCKSSocketInfo() {
+  mData = new uint8_t[BUFFER_SIZE];
+
+  mInternalProxyAddr.raw.family = AF_INET;
+  mInternalProxyAddr.inet.ip = htonl(INADDR_ANY);
+  mInternalProxyAddr.inet.port = htons(0);
+
+  mExternalProxyAddr.raw.family = AF_INET;
+  mExternalProxyAddr.inet.ip = htonl(INADDR_ANY);
+  mExternalProxyAddr.inet.port = htons(0);
+
+  mDestinationAddr.raw.family = AF_INET;
+  mDestinationAddr.inet.ip = htonl(INADDR_ANY);
+  mDestinationAddr.inet.port = htons(0);
+}
+
+/* Helper template class to statically check that writes to a fixed-size
+ * buffer are not going to overflow.
+ *
+ * Example usage:
+ *   uint8_t real_buf[TOTAL_SIZE];
+ *   Buffer<TOTAL_SIZE> buf(&real_buf);
+ *   auto buf2 = buf.WriteUint16(1);
+ *   auto buf3 = buf2.WriteUint8(2);
+ *
+ * It is possible to chain them, to limit the number of (error-prone)
+ * intermediate variables:
+ *   auto buf = Buffer<TOTAL_SIZE>(&real_buf)
+ *              .WriteUint16(1)
+ *              .WriteUint8(2);
+ *
+ * Debug builds assert when intermediate variables are reused:
+ *   Buffer<TOTAL_SIZE> buf(&real_buf);
+ *   auto buf2 = buf.WriteUint16(1);
+ *   auto buf3 = buf.WriteUint8(2); // Asserts
+ *
+ * Strings can be written, given an explicit maximum length.
+ *   buf.WriteString<MAX_STRING_LENGTH>(str);
+ *
+ * The Written() method returns how many bytes have been written so far:
+ *   Buffer<TOTAL_SIZE> buf(&real_buf);
+ *   auto buf2 = buf.WriteUint16(1);
+ *   auto buf3 = buf2.WriteUint8(2);
+ *   buf3.Written(); // returns 3.
+ */
+template <size_t Size>
+class Buffer {
+ public:
+  Buffer() = default;
+
+  explicit Buffer(uint8_t* aBuf, size_t aLength = 0)
+      : mBuf(aBuf), mLength(aLength) {}
+
+  template <size_t Size2>
+  MOZ_IMPLICIT Buffer(const Buffer<Size2>& aBuf)
+      : mBuf(aBuf.mBuf), mLength(aBuf.mLength) {
+    static_assert(Size2 > Size, "Cannot cast buffer");
+  }
+
+  Buffer<Size - sizeof(uint8_t)> WriteUint8(uint8_t aValue) {
+    return Write(aValue);
+  }
+
+  Buffer<Size - sizeof(uint16_t)> WriteUint16(uint16_t aValue) {
+    return Write(aValue);
+  }
+
+  Buffer<Size - sizeof(uint32_t)> WriteUint32(uint32_t aValue) {
+    return Write(aValue);
+  }
+
+  Buffer<Size - sizeof(uint16_t)> WriteNetPort(const NetAddr* aAddr) {
+    return WriteUint16(aAddr->inet.port);
+  }
+
+  Buffer<Size - sizeof(IPv6Addr)> WriteNetAddr(const NetAddr* aAddr) {
+    if (aAddr->raw.family == AF_INET) {
+      return Write(aAddr->inet.ip);
+    }
+    if (aAddr->raw.family == AF_INET6) {
+      return Write(aAddr->inet6.ip.u8);
+    }
+    MOZ_ASSERT_UNREACHABLE("Unknown address family");
+    return *this;
+  }
+
+  template <size_t MaxLength>
+  Buffer<Size - MaxLength> WriteString(const nsACString& aStr) {
+    if (aStr.Length() > MaxLength) {
+      return Buffer<Size - MaxLength>(nullptr);
+    }
+    return WritePtr<char, MaxLength>(aStr.Data(), aStr.Length());
+  }
+
+  size_t Written() {
+    MOZ_ASSERT(mBuf);
+    return mLength;
+  }
+
+  explicit operator bool() { return !!mBuf; }
+
+ private:
+  template <size_t Size2>
+  friend class Buffer;
+
+  template <typename T>
+  Buffer<Size - sizeof(T)> Write(T& aValue) {
+    return WritePtr<T, sizeof(T)>(&aValue, sizeof(T));
+  }
+
+  template <typename T, size_t Length>
+  Buffer<Size - Length> WritePtr(const T* aValue, size_t aCopyLength) {
+    static_assert(Size >= Length, "Cannot write that much");
+    MOZ_ASSERT(aCopyLength <= Length);
+    MOZ_ASSERT(mBuf);
+    memcpy(mBuf, aValue, aCopyLength);
+    Buffer<Size - Length> result(mBuf + aCopyLength, mLength + aCopyLength);
+    mBuf = nullptr;
+    mLength = 0;
+    return result;
+  }
+
+  uint8_t* mBuf{nullptr};
+  size_t mLength{0};
+};
+
+void nsSOCKSSocketInfo::Init(int32_t version, int32_t family,
+                             nsIProxyInfo* proxy, const char* host,
+                             uint32_t flags, uint32_t tlsFlags) {
+  mVersion = version;
+  mDestinationFamily = family;
+  mProxy = proxy;
+  mDestinationHost = host;
+  mFlags = flags;
+  mTlsFlags = tlsFlags;
+  mProxy->GetUsername(mProxyUsername);  // cache
+}
+
+NS_IMPL_ISUPPORTS(nsSOCKSSocketInfo, nsIDNSListener)
+
+void nsSOCKSSocketInfo::GetExternalProxyAddr(NetAddr& aExternalProxyAddr) {
+  aExternalProxyAddr = mExternalProxyAddr;
+}
+
+void nsSOCKSSocketInfo::GetDestinationAddr(NetAddr& aDestinationAddr) {
+  aDestinationAddr = mDestinationAddr;
+}
+
+void nsSOCKSSocketInfo::SetDestinationAddr(const NetAddr& aDestinationAddr) {
+  mDestinationAddr = aDestinationAddr;
+}
+
+// There needs to be a means of distinguishing between connection errors
+// that the SOCKS server reports when it rejects a connection request, and
+// connection errors that happen while attempting to connect to the SOCKS
+// server. Otherwise, Firefox will report incorrectly that the proxy server
+// is refusing connections when a SOCKS request is rejected by the proxy.
+// When a SOCKS handshake failure occurs, the PR error is set to
+// PR_UNKNOWN_ERROR, and the real error code is returned via the OS error.
+void nsSOCKSSocketInfo::HandshakeFinished(PRErrorCode err) {
+  if (err == 0) {
+    mState = SOCKS_CONNECTED;
+#if defined(XP_WIN)
+    // Switch back to nonblocking mode after finishing handshaking.
+    if (IsLocalProxy() && mFD) {
+      PRSocketOptionData opt_nonblock;
+      opt_nonblock.option = PR_SockOpt_Nonblocking;
+      opt_nonblock.value.non_blocking = PR_TRUE;
+      PR_SetSocketOption(mFD, &opt_nonblock);
+      mFD = nullptr;
+    }
+#endif
+  } else {
+    mState = SOCKS_FAILED;
+    PR_SetError(PR_UNKNOWN_ERROR, err);
+  }
+
+  // We don't need the buffer any longer, so free it.
+  delete[] mData;
+  mData = nullptr;
+  mDataIoPtr = nullptr;
+  mDataLength = 0;
+  mReadOffset = 0;
+  mAmountToRead = 0;
+  if (mLookup) {
+    mLookup->Cancel(NS_ERROR_FAILURE);
+    mLookup = nullptr;
+  }
+}
+
+PRStatus nsSOCKSSocketInfo::StartDNS(PRFileDesc* fd) {
+  MOZ_ASSERT(!mDnsRec && mState == SOCKS_INITIAL,
+             "Must be in initial state to make DNS Lookup");
+
+  nsCOMPtr<nsIDNSService> dns = do_GetService(NS_DNSSERVICE_CONTRACTID);
+  if (!dns) return PR_FAILURE;
+
+  nsCString proxyHost;
+  mProxy->GetHost(proxyHost);
+
+  mozilla::OriginAttributes attrs;
+
+  mFD = fd;
+  nsresult rv = dns->AsyncResolveNative(
+      proxyHost, nsIDNSService::RESOLVE_TYPE_DEFAULT,
+      nsIDNSService::RESOLVE_IGNORE_SOCKS_DNS, nullptr, this,
+      mozilla::GetCurrentEventTarget(), attrs, getter_AddRefs(mLookup));
+
+  if (NS_FAILED(rv)) {
+    LOGERROR(("socks: DNS lookup for SOCKS proxy %s failed", proxyHost.get()));
+    return PR_FAILURE;
+  }
+  mState = SOCKS_DNS_IN_PROGRESS;
+  PR_SetError(PR_IN_PROGRESS_ERROR, 0);
+  return PR_FAILURE;
+}
+
+NS_IMETHODIMP
+nsSOCKSSocketInfo::OnLookupComplete(nsICancelable* aRequest,
+                                    nsIDNSRecord* aRecord, nsresult aStatus) {
+  MOZ_ASSERT(aRequest == mLookup, "wrong DNS query");
+  mLookup = nullptr;
+  mLookupStatus = aStatus;
+  mDnsRec = aRecord;
+  mState = SOCKS_DNS_COMPLETE;
+  if (mFD) {
+    ConnectToProxy(mFD);
+    ForgetFD();
+  }
+  return NS_OK;
+}
+
+PRStatus nsSOCKSSocketInfo::ConnectToProxy(PRFileDesc* fd) {
+  PRStatus status;
+  nsresult rv;
+
+  MOZ_ASSERT(mState == SOCKS_DNS_COMPLETE, "Must have DNS to make connection!");
+
+  if (NS_FAILED(mLookupStatus)) {
+    PR_SetError(PR_BAD_ADDRESS_ERROR, 0);
+    return PR_FAILURE;
+  }
+
+  // Try socks5 if the destination addrress is IPv6
+  if (mVersion == 4 && mDestinationAddr.raw.family == AF_INET6) {
+    mVersion = 5;
+  }
+
+  nsAutoCString proxyHost;
+  mProxy->GetHost(proxyHost);
+
+  int32_t proxyPort;
+  mProxy->GetPort(&proxyPort);
+
+  int32_t addresses = 0;
+  do {
+    if (IsLocalProxy()) {
+      rv = SetLocalProxyPath(proxyHost, &mInternalProxyAddr);
+      if (NS_FAILED(rv)) {
+        LOGERROR(
+            ("socks: unable to connect to SOCKS proxy, %s", proxyHost.get()));
+        return PR_FAILURE;
+      }
+    } else {
+      nsCOMPtr<nsIDNSAddrRecord> record = do_QueryInterface(mDnsRec);
+      MOZ_ASSERT(record);
+      if (addresses++) {
+        record->ReportUnusable(proxyPort);
+      }
+
+      rv = record->GetNextAddr(proxyPort, &mInternalProxyAddr);
+      // No more addresses to try? If so, we'll need to bail
+      if (NS_FAILED(rv)) {
+        LOGERROR(
+            ("socks: unable to connect to SOCKS proxy, %s", proxyHost.get()));
+        return PR_FAILURE;
+      }
+
+      if (MOZ_LOG_TEST(gSOCKSLog, LogLevel::Debug)) {
+        char buf[kIPv6CStrBufSize];
+        mInternalProxyAddr.ToStringBuffer(buf, sizeof(buf));
+        LOGDEBUG(("socks: trying proxy server, %s:%hu", buf,
+                  ntohs(mInternalProxyAddr.inet.port)));
+      }
+    }
+
+    NetAddr proxy = mInternalProxyAddr;
+    FixupAddressFamily(fd, &proxy);
+    PRNetAddr prProxy;
+    NetAddrToPRNetAddr(&proxy, &prProxy);
+    status = fd->lower->methods->connect(fd->lower, &prProxy, mTimeout);
+    if (status != PR_SUCCESS) {
+      PRErrorCode c = PR_GetError();
+
+      // If EINPROGRESS, return now and check back later after polling
+      if (c == PR_WOULD_BLOCK_ERROR || c == PR_IN_PROGRESS_ERROR) {
+        mState = SOCKS_CONNECTING_TO_PROXY;
+        return status;
+      }
+      if (IsLocalProxy()) {
+        LOGERROR(("socks: connect to domain socket failed (%d)", c));
+        PR_SetError(PR_CONNECT_REFUSED_ERROR, 0);
+        mState = SOCKS_FAILED;
+        return status;
+      }
+    }
+  } while (status != PR_SUCCESS);
+
+#if defined(XP_WIN)
+  // Switch to blocking mode during handshaking
+  if (IsLocalProxy() && mFD) {
+    PRSocketOptionData opt_nonblock;
+    opt_nonblock.option = PR_SockOpt_Nonblocking;
+    opt_nonblock.value.non_blocking = PR_FALSE;
+    PR_SetSocketOption(mFD, &opt_nonblock);
+  }
+#endif
+
+  // Connected now, start SOCKS
+  if (mVersion == 4) return WriteV4ConnectRequest();
+  return WriteV5AuthRequest();
+}
+
+void nsSOCKSSocketInfo::FixupAddressFamily(PRFileDesc* fd, NetAddr* proxy) {
+  int32_t proxyFamily = mInternalProxyAddr.raw.family;
+  // Do nothing if the address family is already matched
+  if (proxyFamily == mDestinationFamily) {
+    return;
+  }
+  // If the system does not support IPv6 and the proxy address is IPv6,
+  // We can do nothing here.
+  if (proxyFamily == AF_INET6 && !ipv6Supported) {
+    return;
+  }
+  // If the system does not support IPv6 and the destination address is
+  // IPv6, convert IPv4 address to IPv4-mapped IPv6 address to satisfy
+  // the emulation layer
+  if (mDestinationFamily == AF_INET6 && !ipv6Supported) {
+    proxy->inet6.family = AF_INET6;
+    proxy->inet6.port = mInternalProxyAddr.inet.port;
+    uint8_t* proxyp = proxy->inet6.ip.u8;
+    memset(proxyp, 0, 10);
+    memset(proxyp + 10, 0xff, 2);
+    memcpy(proxyp + 12, (char*)&mInternalProxyAddr.inet.ip, 4);
+    // mDestinationFamily should not be updated
+    return;
+  }
+  // There's no PR_NSPR_IO_LAYER required when using named pipe,
+  // we simply ignore the TCP family here.
+  if (SetupNamedPipeLayer(fd)) {
+    return;
+  }
+
+  // Get an OS native handle from a specified FileDesc
+  PROsfd osfd = PR_FileDesc2NativeHandle(fd);
+  if (osfd == -1) {
+    return;
+  }
+
+  // Create a new FileDesc with a specified family
+  PRFileDesc* tmpfd = PR_OpenTCPSocket(proxyFamily);
+  if (!tmpfd) {
+    return;
+  }
+  PROsfd newsd = PR_FileDesc2NativeHandle(tmpfd);
+  if (newsd == -1) {
+    PR_Close(tmpfd);
+    return;
+  }
+  // Must succeed because PR_FileDesc2NativeHandle succeeded
+  fd = PR_GetIdentitiesLayer(fd, PR_NSPR_IO_LAYER);
+  MOZ_ASSERT(fd);
+  // Swap OS native handles
+  PR_ChangeFileDescNativeHandle(fd, newsd);
+  PR_ChangeFileDescNativeHandle(tmpfd, osfd);
+  // Close temporary FileDesc which is now associated with
+  // old OS native handle
+  PR_Close(tmpfd);
+  mDestinationFamily = proxyFamily;
+}
+
+PRStatus nsSOCKSSocketInfo::ContinueConnectingToProxy(PRFileDesc* fd,
+                                                      int16_t oflags) {
+  PRStatus status;
+
+  MOZ_ASSERT(mState == SOCKS_CONNECTING_TO_PROXY,
+             "Continuing connection in wrong state!");
+
+  LOGDEBUG(("socks: continuing connection to proxy"));
+
+  status = fd->lower->methods->connectcontinue(fd->lower, oflags);
+  if (status != PR_SUCCESS) {
+    PRErrorCode c = PR_GetError();
+    if (c != PR_WOULD_BLOCK_ERROR && c != PR_IN_PROGRESS_ERROR) {
+      // A connection failure occured, try another address
+      mState = SOCKS_DNS_COMPLETE;
+      return ConnectToProxy(fd);
+    }
+
+    // We're still connecting
+    return PR_FAILURE;
+  }
+
+  // Connected now, start SOCKS
+  if (mVersion == 4) return WriteV4ConnectRequest();
+  return WriteV5AuthRequest();
+}
+
+PRStatus nsSOCKSSocketInfo::WriteV4ConnectRequest() {
+  if (mProxyUsername.Length() > MAX_USERNAME_LEN) {
+    LOGERROR(("socks username is too long"));
+    HandshakeFinished(PR_UNKNOWN_ERROR);
+    return PR_FAILURE;
+  }
+
+  NetAddr* addr = &mDestinationAddr;
+  int32_t proxy_resolve;
+
+  MOZ_ASSERT(mState == SOCKS_CONNECTING_TO_PROXY, "Invalid state!");
+
+  proxy_resolve = mFlags & nsISocketProvider::PROXY_RESOLVES_HOST;
+
+  mDataLength = 0;
+  mState = SOCKS4_WRITE_CONNECT_REQUEST;
+
+  LOGDEBUG(("socks4: sending connection request (socks4a resolve? %s)",
+            proxy_resolve ? "yes" : "no"));
+
+  // Send a SOCKS 4 connect request.
+  auto buf = Buffer<BUFFER_SIZE>(mData)
+                 .WriteUint8(0x04)  // version -- 4
+                 .WriteUint8(0x01)  // command -- connect
+                 .WriteNetPort(addr);
+
+  // We don't have anything more to write after the if, so we can
+  // use a buffer with no further writes allowed.
+  Buffer<0> buf3;
+  if (proxy_resolve) {
+    // Add the full name, null-terminated, to the request
+    // according to SOCKS 4a. A fake IP address, with the first
+    // four bytes set to 0 and the last byte set to something other
+    // than 0, is used to notify the proxy that this is a SOCKS 4a
+    // request. This request type works for Tor and perhaps others.
+    // Passwords not supported by V4.
+    auto buf2 =
+        buf.WriteUint32(htonl(0x00000001))  // Fake IP
+            .WriteString<MAX_USERNAME_LEN>(mProxyUsername)
+            .WriteUint8(0x00)  // Null-terminate username
+            .WriteString<MAX_HOSTNAME_LEN>(mDestinationHost);  // Hostname
+    if (!buf2) {
+      LOGERROR(("socks4: destination host name is too long!"));
+      HandshakeFinished(PR_BAD_ADDRESS_ERROR);
+      return PR_FAILURE;
+    }
+    buf3 = buf2.WriteUint8(0x00);
+  } else if (addr->raw.family == AF_INET) {
+    // Passwords not supported by V4.
+    buf3 = buf.WriteNetAddr(addr)  // Add the IPv4 address
+               .WriteString<MAX_USERNAME_LEN>(mProxyUsername)
+               .WriteUint8(0x00);  // Null-terminate username
+  } else {
+    LOGERROR(("socks: SOCKS 4 can only handle IPv4 addresses!"));
+    HandshakeFinished(PR_BAD_ADDRESS_ERROR);
+    return PR_FAILURE;
+  }
+
+  mDataLength = buf3.Written();
+  return PR_SUCCESS;
+}
+
+PRStatus nsSOCKSSocketInfo::ReadV4ConnectResponse() {
+  MOZ_ASSERT(mState == SOCKS4_READ_CONNECT_RESPONSE,
+             "Handling SOCKS 4 connection reply in wrong state!");
+  MOZ_ASSERT(mDataLength == 8, "SOCKS 4 connection reply must be 8 bytes!");
+
+  LOGDEBUG(("socks4: checking connection reply"));
+
+  if (ReadUint8() != 0x00) {
+    LOGERROR(("socks4: wrong connection reply"));
+    HandshakeFinished(PR_CONNECT_REFUSED_ERROR);
+    return PR_FAILURE;
+  }
+
+  // See if our connection request was granted
+  if (ReadUint8() == 90) {
+    LOGDEBUG(("socks4: connection successful!"));
+    HandshakeFinished();
+    return PR_SUCCESS;
+  }
+
+  LOGERROR(("socks4: unable to connect"));
+  HandshakeFinished(PR_CONNECT_REFUSED_ERROR);
+  return PR_FAILURE;
+}
+
+PRStatus nsSOCKSSocketInfo::WriteV5AuthRequest() {
+  MOZ_ASSERT(mVersion == 5, "SOCKS version must be 5!");
+
+  mDataLength = 0;
+  mState = SOCKS5_WRITE_AUTH_REQUEST;
+
+  // Send an initial SOCKS 5 greeting
+  LOGDEBUG(("socks5: sending auth methods"));
+  mDataLength = Buffer<BUFFER_SIZE>(mData)
+                    .WriteUint8(0x05)  // version -- 5
+                    .WriteUint8(0x01)  // # of auth methods -- 1
+                    // Use authenticate iff we have a proxy username.
+                    .WriteUint8(mProxyUsername.IsEmpty() ? 0x00 : 0x02)
+                    .Written();
+
+  return PR_SUCCESS;
+}
+
+PRStatus nsSOCKSSocketInfo::ReadV5AuthResponse() {
+  MOZ_ASSERT(mState == SOCKS5_READ_AUTH_RESPONSE,
+             "Handling SOCKS 5 auth method reply in wrong state!");
+  MOZ_ASSERT(mDataLength == 2, "SOCKS 5 auth method reply must be 2 bytes!");
+
+  LOGDEBUG(("socks5: checking auth method reply"));
+
+  // Check version number
+  if (ReadUint8() != 0x05) {
+    LOGERROR(("socks5: unexpected version in the reply"));
+    HandshakeFinished(PR_CONNECT_REFUSED_ERROR);
+    return PR_FAILURE;
+  }
+
+  // Make sure our authentication choice was accepted,
+  // and continue accordingly
+  uint8_t authMethod = ReadUint8();
+  if (mProxyUsername.IsEmpty() && authMethod == 0x00) {  // no auth
+    LOGDEBUG(("socks5: server allows connection without authentication"));
+    return WriteV5ConnectRequest();
+  }
+  if (!mProxyUsername.IsEmpty() && authMethod == 0x02) {  // username/pw
+    LOGDEBUG(("socks5: auth method accepted by server"));
+    return WriteV5UsernameRequest();
+  }  // 0xFF signals error
+  LOGERROR(("socks5: server did not accept our authentication method"));
+  HandshakeFinished(PR_CONNECT_REFUSED_ERROR);
+  return PR_FAILURE;
+}
+
+PRStatus nsSOCKSSocketInfo::WriteV5UsernameRequest() {
+  MOZ_ASSERT(mVersion == 5, "SOCKS version must be 5!");
+
+  if (mProxyUsername.Length() > MAX_USERNAME_LEN) {
+    LOGERROR(("socks username is too long"));
+    HandshakeFinished(PR_UNKNOWN_ERROR);
+    return PR_FAILURE;
+  }
+
+  nsCString password;
+  mProxy->GetPassword(password);
+  if (password.Length() > MAX_PASSWORD_LEN) {
+    LOGERROR(("socks password is too long"));
+    HandshakeFinished(PR_UNKNOWN_ERROR);
+    return PR_FAILURE;
+  }
+
+  mDataLength = 0;
+  mState = SOCKS5_WRITE_USERNAME_REQUEST;
+
+  // RFC 1929 Username/password auth for SOCKS 5
+  LOGDEBUG(("socks5: sending username and password"));
+  mDataLength = Buffer<BUFFER_SIZE>(mData)
+                    .WriteUint8(0x01)                     // version 1 (not 5)
+                    .WriteUint8(mProxyUsername.Length())  // username length
+                    .WriteString<MAX_USERNAME_LEN>(mProxyUsername)  // username
+                    .WriteUint8(password.Length())  // password length
+                    .WriteString<MAX_PASSWORD_LEN>(
+                        password)  // password. WARNING: Sent unencrypted!
+                    .Written();
+
+  return PR_SUCCESS;
+}
+
+PRStatus nsSOCKSSocketInfo::ReadV5UsernameResponse() {
+  MOZ_ASSERT(mState == SOCKS5_READ_USERNAME_RESPONSE,
+             "Handling SOCKS 5 username/password reply in wrong state!");
+
+  MOZ_ASSERT(mDataLength == 2, "SOCKS 5 username reply must be 2 bytes");
+
+  // Check version number, must be 1 (not 5)
+  if (ReadUint8() != 0x01) {
+    LOGERROR(("socks5: unexpected version in the reply"));
+    HandshakeFinished(PR_CONNECT_REFUSED_ERROR);
+    return PR_FAILURE;
+  }
+
+  // Check whether username/password were accepted
+  if (ReadUint8() != 0x00) {  // 0 = success
+    LOGERROR(("socks5: username/password not accepted"));
+    HandshakeFinished(PR_CONNECT_REFUSED_ERROR);
+    return PR_FAILURE;
+  }
+
+  LOGDEBUG(("socks5: username/password accepted by server"));
+
+  return WriteV5ConnectRequest();
+}
+
+PRStatus nsSOCKSSocketInfo::WriteV5ConnectRequest() {
+  // Send SOCKS 5 connect request
+  NetAddr* addr = &mDestinationAddr;
+  int32_t proxy_resolve;
+  proxy_resolve = mFlags & nsISocketProvider::PROXY_RESOLVES_HOST;
+
+  LOGDEBUG(("socks5: sending connection request (socks5 resolve? %s)",
+            proxy_resolve ? "yes" : "no"));
+
+  mDataLength = 0;
+  mState = SOCKS5_WRITE_CONNECT_REQUEST;
+
+  auto buf = Buffer<BUFFER_SIZE>(mData)
+                 .WriteUint8(0x05)   // version -- 5
+                 .WriteUint8(0x01)   // command -- connect
+                 .WriteUint8(0x00);  // reserved
+
+  // We're writing a net port after the if, so we need a buffer allowing
+  // to write that much.
+  Buffer<sizeof(uint16_t)> buf2;
+  // Add the address to the SOCKS 5 request. SOCKS 5 supports several
+  // address types, so we pick the one that works best for us.
+  if (proxy_resolve) {
+    // Add the host name. Only a single byte is used to store the length,
+    // so we must prevent long names from being used.
+    buf2 = buf.WriteUint8(0x03)  // addr type -- domainname
+               .WriteUint8(mDestinationHost.Length())             // name length
+               .WriteString<MAX_HOSTNAME_LEN>(mDestinationHost);  // Hostname
+    if (!buf2) {
+      LOGERROR(("socks5: destination host name is too long!"));
+      HandshakeFinished(PR_BAD_ADDRESS_ERROR);
+      return PR_FAILURE;
+    }
+  } else if (addr->raw.family == AF_INET) {
+    buf2 = buf.WriteUint8(0x01)  // addr type -- IPv4
+               .WriteNetAddr(addr);
+  } else if (addr->raw.family == AF_INET6) {
+    buf2 = buf.WriteUint8(0x04)  // addr type -- IPv6
+               .WriteNetAddr(addr);
+  } else {
+    LOGERROR(("socks5: destination address of unknown type!"));
+    HandshakeFinished(PR_BAD_ADDRESS_ERROR);
+    return PR_FAILURE;
+  }
+
+  auto buf3 = buf2.WriteNetPort(addr);  // port
+  mDataLength = buf3.Written();
+
+  return PR_SUCCESS;
+}
+
+PRStatus nsSOCKSSocketInfo::ReadV5AddrTypeAndLength(uint8_t* type,
+                                                    uint32_t* len) {
+  MOZ_ASSERT(mState == SOCKS5_READ_CONNECT_RESPONSE_TOP ||
+                 mState == SOCKS5_READ_CONNECT_RESPONSE_BOTTOM,
+             "Invalid state!");
+  MOZ_ASSERT(mDataLength >= 5,
+             "SOCKS 5 connection reply must be at least 5 bytes!");
+
+  // Seek to the address location
+  mReadOffset = 3;
+
+  *type = ReadUint8();
+
+  switch (*type) {
+    case 0x01:  // ipv4
+      *len = 4 - 1;
+      break;
+    case 0x04:  // ipv6
+      *len = 16 - 1;
+      break;
+    case 0x03:  // fqdn
+      *len = ReadUint8();
+      break;
+    default:  // wrong address type
+      LOGERROR(("socks5: wrong address type in connection reply!"));
+      return PR_FAILURE;
+  }
+
+  return PR_SUCCESS;
+}
+
+PRStatus nsSOCKSSocketInfo::ReadV5ConnectResponseTop() {
+  uint8_t res;
+  uint32_t len;
+
+  MOZ_ASSERT(mState == SOCKS5_READ_CONNECT_RESPONSE_TOP, "Invalid state!");
+  MOZ_ASSERT(mDataLength == 5,
+             "SOCKS 5 connection reply must be exactly 5 bytes!");
+
+  LOGDEBUG(("socks5: checking connection reply"));
+
+  // Check version number
+  if (ReadUint8() != 0x05) {
+    LOGERROR(("socks5: unexpected version in the reply"));
+    HandshakeFinished(PR_CONNECT_REFUSED_ERROR);
+    return PR_FAILURE;
+  }
+
+  // Check response
+  res = ReadUint8();
+  if (res != 0x00) {
+    PRErrorCode c = PR_CONNECT_REFUSED_ERROR;
+
+    switch (res) {
+      case 0x01:
+        LOGERROR(
+            ("socks5: connect failed: "
+             "01, General SOCKS server failure."));
+        break;
+      case 0x02:
+        LOGERROR(
+            ("socks5: connect failed: "
+             "02, Connection not allowed by ruleset."));
+        break;
+      case 0x03:
+        LOGERROR(("socks5: connect failed: 03, Network unreachable."));
+        c = PR_NETWORK_UNREACHABLE_ERROR;
+        break;
+      case 0x04:
+        LOGERROR(("socks5: connect failed: 04, Host unreachable."));
+        c = PR_BAD_ADDRESS_ERROR;
+        break;
+      case 0x05:
+        LOGERROR(("socks5: connect failed: 05, Connection refused."));
+        break;
+      case 0x06:
+        LOGERROR(("socks5: connect failed: 06, TTL expired."));
+        c = PR_CONNECT_TIMEOUT_ERROR;
+        break;
+      case 0x07:
+        LOGERROR(
+            ("socks5: connect failed: "
+             "07, Command not supported."));
+        break;
+      case 0x08:
+        LOGERROR(
+            ("socks5: connect failed: "
+             "08, Address type not supported."));
+        c = PR_BAD_ADDRESS_ERROR;
+        break;
+      default:
+        LOGERROR(("socks5: connect failed."));
+        break;
+    }
+
+    HandshakeFinished(c);
+    return PR_FAILURE;
+  }
+
+  if (ReadV5AddrTypeAndLength(&res, &len) != PR_SUCCESS) {
+    HandshakeFinished(PR_BAD_ADDRESS_ERROR);
+    return PR_FAILURE;
+  }
+
+  mState = SOCKS5_READ_CONNECT_RESPONSE_BOTTOM;
+  WantRead(len + 2);
+
+  return PR_SUCCESS;
+}
+
+PRStatus nsSOCKSSocketInfo::ReadV5ConnectResponseBottom() {
+  uint8_t type;
+  uint32_t len;
+
+  MOZ_ASSERT(mState == SOCKS5_READ_CONNECT_RESPONSE_BOTTOM, "Invalid state!");
+
+  if (ReadV5AddrTypeAndLength(&type, &len) != PR_SUCCESS) {
+    HandshakeFinished(PR_BAD_ADDRESS_ERROR);
+    return PR_FAILURE;
+  }
+
+  MOZ_ASSERT(mDataLength == 7 + len,
+             "SOCKS 5 unexpected length of connection reply!");
+
+  LOGDEBUG(("socks5: loading source addr and port"));
+  // Read what the proxy says is our source address
+  switch (type) {
+    case 0x01:  // ipv4
+      ReadNetAddr(&mExternalProxyAddr, AF_INET);
+      break;
+    case 0x04:  // ipv6
+      ReadNetAddr(&mExternalProxyAddr, AF_INET6);
+      break;
+    case 0x03:  // fqdn (skip)
+      mReadOffset += len;
+      mExternalProxyAddr.raw.family = AF_INET;
+      break;
+  }
+
+  ReadNetPort(&mExternalProxyAddr);
+
+  LOGDEBUG(("socks5: connected!"));
+  HandshakeFinished();
+
+  return PR_SUCCESS;
+}
+
+void nsSOCKSSocketInfo::SetConnectTimeout(PRIntervalTime to) { mTimeout = to; }
+
+PRStatus nsSOCKSSocketInfo::DoHandshake(PRFileDesc* fd, int16_t oflags) {
+  LOGDEBUG(("socks: DoHandshake(), state = %d", mState));
+
+  switch (mState) {
+    case SOCKS_INITIAL:
+      if (IsLocalProxy()) {
+        mState = SOCKS_DNS_COMPLETE;
+        mLookupStatus = NS_OK;
+        return ConnectToProxy(fd);
+      }
+
+      return StartDNS(fd);
+    case SOCKS_DNS_IN_PROGRESS:
+      PR_SetError(PR_IN_PROGRESS_ERROR, 0);
+      return PR_FAILURE;
+    case SOCKS_DNS_COMPLETE:
+      return ConnectToProxy(fd);
+    case SOCKS_CONNECTING_TO_PROXY:
+      return ContinueConnectingToProxy(fd, oflags);
+    case SOCKS4_WRITE_CONNECT_REQUEST:
+      if (WriteToSocket(fd) != PR_SUCCESS) return PR_FAILURE;
+      WantRead(8);
+      mState = SOCKS4_READ_CONNECT_RESPONSE;
+      return PR_SUCCESS;
+    case SOCKS4_READ_CONNECT_RESPONSE:
+      if (ReadFromSocket(fd) != PR_SUCCESS) return PR_FAILURE;
+      return ReadV4ConnectResponse();
+
+    case SOCKS5_WRITE_AUTH_REQUEST:
+      if (WriteToSocket(fd) != PR_SUCCESS) return PR_FAILURE;
+      WantRead(2);
+      mState = SOCKS5_READ_AUTH_RESPONSE;
+      return PR_SUCCESS;
+    case SOCKS5_READ_AUTH_RESPONSE:
+      if (ReadFromSocket(fd) != PR_SUCCESS) return PR_FAILURE;
+      return ReadV5AuthResponse();
+    case SOCKS5_WRITE_USERNAME_REQUEST:
+      if (WriteToSocket(fd) != PR_SUCCESS) return PR_FAILURE;
+      WantRead(2);
+      mState = SOCKS5_READ_USERNAME_RESPONSE;
+      return PR_SUCCESS;
+    case SOCKS5_READ_USERNAME_RESPONSE:
+      if (ReadFromSocket(fd) != PR_SUCCESS) return PR_FAILURE;
+      return ReadV5UsernameResponse();
+    case SOCKS5_WRITE_CONNECT_REQUEST:
+      if (WriteToSocket(fd) != PR_SUCCESS) return PR_FAILURE;
+
+      // The SOCKS 5 response to the connection request is variable
+      // length. First, we'll read enough to tell how long the response
+      // is, and will read the rest later.
+      WantRead(5);
+      mState = SOCKS5_READ_CONNECT_RESPONSE_TOP;
+      return PR_SUCCESS;
+    case SOCKS5_READ_CONNECT_RESPONSE_TOP:
+      if (ReadFromSocket(fd) != PR_SUCCESS) return PR_FAILURE;
+      return ReadV5ConnectResponseTop();
+    case SOCKS5_READ_CONNECT_RESPONSE_BOTTOM:
+      if (ReadFromSocket(fd) != PR_SUCCESS) return PR_FAILURE;
+      return ReadV5ConnectResponseBottom();
+
+    case SOCKS_CONNECTED:
+      LOGERROR(("socks: already connected"));
+      HandshakeFinished(PR_IS_CONNECTED_ERROR);
+      return PR_FAILURE;
+    case SOCKS_FAILED:
+      LOGERROR(("socks: already failed"));
+      return PR_FAILURE;
+  }
+
+  LOGERROR(("socks: executing handshake in invalid state, %d", mState));
+  HandshakeFinished(PR_INVALID_STATE_ERROR);
+
+  return PR_FAILURE;
+}
+
+int16_t nsSOCKSSocketInfo::GetPollFlags() const {
+  switch (mState) {
+    case SOCKS_DNS_IN_PROGRESS:
+    case SOCKS_DNS_COMPLETE:
+    case SOCKS_CONNECTING_TO_PROXY:
+      return PR_POLL_EXCEPT | PR_POLL_WRITE;
+    case SOCKS4_WRITE_CONNECT_REQUEST:
+    case SOCKS5_WRITE_AUTH_REQUEST:
+    case SOCKS5_WRITE_USERNAME_REQUEST:
+    case SOCKS5_WRITE_CONNECT_REQUEST:
+      return PR_POLL_WRITE;
+    case SOCKS4_READ_CONNECT_RESPONSE:
+    case SOCKS5_READ_AUTH_RESPONSE:
+    case SOCKS5_READ_USERNAME_RESPONSE:
+    case SOCKS5_READ_CONNECT_RESPONSE_TOP:
+    case SOCKS5_READ_CONNECT_RESPONSE_BOTTOM:
+      return PR_POLL_READ;
+    default:
+      break;
+  }
+
+  return 0;
+}
+
+inline uint8_t nsSOCKSSocketInfo::ReadUint8() {
+  uint8_t rv;
+  MOZ_ASSERT(mReadOffset + sizeof(rv) <= mDataLength,
+             "Not enough space to pop a uint8_t!");
+  rv = mData[mReadOffset];
+  mReadOffset += sizeof(rv);
+  return rv;
+}
+
+inline uint16_t nsSOCKSSocketInfo::ReadUint16() {
+  uint16_t rv;
+  MOZ_ASSERT(mReadOffset + sizeof(rv) <= mDataLength,
+             "Not enough space to pop a uint16_t!");
+  memcpy(&rv, mData + mReadOffset, sizeof(rv));
+  mReadOffset += sizeof(rv);
+  return rv;
+}
+
+inline uint32_t nsSOCKSSocketInfo::ReadUint32() {
+  uint32_t rv;
+  MOZ_ASSERT(mReadOffset + sizeof(rv) <= mDataLength,
+             "Not enough space to pop a uint32_t!");
+  memcpy(&rv, mData + mReadOffset, sizeof(rv));
+  mReadOffset += sizeof(rv);
+  return rv;
+}
+
+void nsSOCKSSocketInfo::ReadNetAddr(NetAddr* addr, uint16_t fam) {
+  uint32_t amt = 0;
+  const uint8_t* ip = mData + mReadOffset;
+
+  addr->raw.family = fam;
+  if (fam == AF_INET) {
+    amt = sizeof(addr->inet.ip);
+    MOZ_ASSERT(mReadOffset + amt <= mDataLength,
+               "Not enough space to pop an ipv4 addr!");
+    memcpy(&addr->inet.ip, ip, amt);
+  } else if (fam == AF_INET6) {
+    amt = sizeof(addr->inet6.ip.u8);
+    MOZ_ASSERT(mReadOffset + amt <= mDataLength,
+               "Not enough space to pop an ipv6 addr!");
+    memcpy(addr->inet6.ip.u8, ip, amt);
+  }
+
+  mReadOffset += amt;
+}
+
+void nsSOCKSSocketInfo::ReadNetPort(NetAddr* addr) {
+  addr->inet.port = ReadUint16();
+}
+
+void nsSOCKSSocketInfo::WantRead(uint32_t sz) {
+  MOZ_ASSERT(mDataIoPtr == nullptr,
+             "WantRead() called while I/O already in progress!");
+  MOZ_ASSERT(mDataLength + sz <= BUFFER_SIZE, "Can't read that much data!");
+  mAmountToRead = sz;
+}
+
+PRStatus nsSOCKSSocketInfo::ReadFromSocket(PRFileDesc* fd) {
+  int32_t rc;
+  const uint8_t* end;
+
+  if (!mAmountToRead) {
+    LOGDEBUG(("socks: ReadFromSocket(), nothing to do"));
+    return PR_SUCCESS;
+  }
+
+  if (!mDataIoPtr) {
+    mDataIoPtr = mData + mDataLength;
+    mDataLength += mAmountToRead;
+  }
+
+  end = mData + mDataLength;
+
+  while (mDataIoPtr < end) {
+    rc = PR_Read(fd, mDataIoPtr, end - mDataIoPtr);
+    if (rc <= 0) {
+      if (rc == 0) {
+        LOGERROR(("socks: proxy server closed connection"));
+        HandshakeFinished(PR_CONNECT_REFUSED_ERROR);
+        return PR_FAILURE;
+      }
+      if (PR_GetError() == PR_WOULD_BLOCK_ERROR) {
+        LOGDEBUG(("socks: ReadFromSocket(), want read"));
+      }
+      break;
+    }
+
+    mDataIoPtr += rc;
+  }
+
+  LOGDEBUG(("socks: ReadFromSocket(), have %u bytes total",
+            unsigned(mDataIoPtr - mData)));
+  if (mDataIoPtr == end) {
+    mDataIoPtr = nullptr;
+    mAmountToRead = 0;
+    mReadOffset = 0;
+    return PR_SUCCESS;
+  }
+
+  return PR_FAILURE;
+}
+
+PRStatus nsSOCKSSocketInfo::WriteToSocket(PRFileDesc* fd) {
+  int32_t rc;
+  const uint8_t* end;
+
+  if (!mDataLength) {
+    LOGDEBUG(("socks: WriteToSocket(), nothing to do"));
+    return PR_SUCCESS;
+  }
+
+  if (!mDataIoPtr) mDataIoPtr = mData;
+
+  end = mData + mDataLength;
+
+  while (mDataIoPtr < end) {
+    rc = PR_Write(fd, mDataIoPtr, end - mDataIoPtr);
+    if (rc < 0) {
+      if (PR_GetError() == PR_WOULD_BLOCK_ERROR) {
+        LOGDEBUG(("socks: WriteToSocket(), want write"));
+      }
+      break;
+    }
+
+    mDataIoPtr += rc;
+  }
+
+  if (mDataIoPtr == end) {
+    mDataIoPtr = nullptr;
+    mDataLength = 0;
+    mReadOffset = 0;
+    return PR_SUCCESS;
+  }
+
+  return PR_FAILURE;
+}
+
+static PRStatus nsSOCKSIOLayerConnect(PRFileDesc* fd, const PRNetAddr* addr,
+                                      PRIntervalTime to) {
+  PRStatus status;
+  NetAddr dst;
+
+  nsSOCKSSocketInfo* info = (nsSOCKSSocketInfo*)fd->secret;
+  if (info == nullptr) return PR_FAILURE;
+
+  if (addr->raw.family == PR_AF_INET6 &&
+      PR_IsNetAddrType(addr, PR_IpAddrV4Mapped)) {
+    const uint8_t* srcp;
+
+    LOGDEBUG(("socks: converting ipv4-mapped ipv6 address to ipv4"));
+
+    // copied from _PR_ConvertToIpv4NetAddr()
+    dst.raw.family = AF_INET;
+    dst.inet.ip = htonl(INADDR_ANY);
+    dst.inet.port = htons(0);
+    srcp = addr->ipv6.ip.pr_s6_addr;
+    memcpy(&dst.inet.ip, srcp + 12, 4);
+    dst.inet.family = AF_INET;
+    dst.inet.port = addr->ipv6.port;
+  } else {
+    memcpy(&dst, addr, sizeof(dst));
+  }
+
+  info->SetDestinationAddr(dst);
+  info->SetConnectTimeout(to);
+
+  do {
+    status = info->DoHandshake(fd, -1);
+  } while (status == PR_SUCCESS && !info->IsConnected());
+
+  return status;
+}
+
+static PRStatus nsSOCKSIOLayerConnectContinue(PRFileDesc* fd, int16_t oflags) {
+  PRStatus status;
+
+  nsSOCKSSocketInfo* info = (nsSOCKSSocketInfo*)fd->secret;
+  if (info == nullptr) return PR_FAILURE;
+
+  do {
+    status = info->DoHandshake(fd, oflags);
+  } while (status == PR_SUCCESS && !info->IsConnected());
+
+  return status;
+}
+
+static int16_t nsSOCKSIOLayerPoll(PRFileDesc* fd, int16_t in_flags,
+                                  int16_t* out_flags) {
+  nsSOCKSSocketInfo* info = (nsSOCKSSocketInfo*)fd->secret;
+  if (info == nullptr) return PR_FAILURE;
+
+  if (!info->IsConnected()) {
+    *out_flags = 0;
+    return info->GetPollFlags();
+  }
+
+  return fd->lower->methods->poll(fd->lower, in_flags, out_flags);
+}
+
+static PRStatus nsSOCKSIOLayerClose(PRFileDesc* fd) {
+  nsSOCKSSocketInfo* info = (nsSOCKSSocketInfo*)fd->secret;
+  PRDescIdentity id = PR_GetLayersIdentity(fd);
+
+  if (info && id == nsSOCKSIOLayerIdentity) {
+    info->ForgetFD();
+    NS_RELEASE(info);
+    fd->identity = PR_INVALID_IO_LAYER;
+  }
+
+  return fd->lower->methods->close(fd->lower);
+}
+
+static PRFileDesc* nsSOCKSIOLayerAccept(PRFileDesc* fd, PRNetAddr* addr,
+                                        PRIntervalTime timeout) {
+  // TODO: implement SOCKS support for accept
+  return fd->lower->methods->accept(fd->lower, addr, timeout);
+}
+
+static int32_t nsSOCKSIOLayerAcceptRead(PRFileDesc* sd, PRFileDesc** nd,
+                                        PRNetAddr** raddr, void* buf,
+                                        int32_t amount,
+                                        PRIntervalTime timeout) {
+  // TODO: implement SOCKS support for accept, then read from it
+  return sd->lower->methods->acceptread(sd->lower, nd, raddr, buf, amount,
+                                        timeout);
+}
+
+static PRStatus nsSOCKSIOLayerBind(PRFileDesc* fd, const PRNetAddr* addr) {
+  // TODO: implement SOCKS support for bind (very similar to connect)
+  return fd->lower->methods->bind(fd->lower, addr);
+}
+
+static PRStatus nsSOCKSIOLayerGetName(PRFileDesc* fd, PRNetAddr* addr) {
+  nsSOCKSSocketInfo* info = (nsSOCKSSocketInfo*)fd->secret;
+
+  if (info != nullptr && addr != nullptr) {
+    NetAddr temp;
+    info->GetExternalProxyAddr(temp);
+    NetAddrToPRNetAddr(&temp, addr);
+    return PR_SUCCESS;
+  }
+
+  return PR_FAILURE;
+}
+
+static PRStatus nsSOCKSIOLayerGetPeerName(PRFileDesc* fd, PRNetAddr* addr) {
+  nsSOCKSSocketInfo* info = (nsSOCKSSocketInfo*)fd->secret;
+
+  if (info != nullptr && addr != nullptr) {
+    NetAddr temp;
+    info->GetDestinationAddr(temp);
+    NetAddrToPRNetAddr(&temp, addr);
+    return PR_SUCCESS;
+  }
+
+  return PR_FAILURE;
+}
+
+static PRStatus nsSOCKSIOLayerListen(PRFileDesc* fd, int backlog) {
+  // TODO: implement SOCKS support for listen
+  return fd->lower->methods->listen(fd->lower, backlog);
+}
+
+// add SOCKS IO layer to an existing socket
+nsresult nsSOCKSIOLayerAddToSocket(int32_t family, const char* host,
+                                   int32_t port, nsIProxyInfo* proxy,
+                                   int32_t socksVersion, uint32_t flags,
+                                   uint32_t tlsFlags, PRFileDesc* fd) {
+  NS_ENSURE_TRUE((socksVersion == 4) || (socksVersion == 5),
+                 NS_ERROR_NOT_INITIALIZED);
+
+  if (firstTime) {
+    // XXX hack until NSPR provides an official way to detect system IPv6
+    // support (bug 388519)
+    PRFileDesc* tmpfd = PR_OpenTCPSocket(PR_AF_INET6);
+    if (!tmpfd) {
+      ipv6Supported = false;
+    } else {
+      // If the system does not support IPv6, NSPR will push
+      // IPv6-to-IPv4 emulation layer onto the native layer
+      ipv6Supported = PR_GetIdentitiesLayer(tmpfd, PR_NSPR_IO_LAYER) == tmpfd;
+      PR_Close(tmpfd);
+    }
+
+    nsSOCKSIOLayerIdentity = PR_GetUniqueIdentity("SOCKS layer");
+    nsSOCKSIOLayerMethods = *PR_GetDefaultIOMethods();
+
+    nsSOCKSIOLayerMethods.connect = nsSOCKSIOLayerConnect;
+    nsSOCKSIOLayerMethods.connectcontinue = nsSOCKSIOLayerConnectContinue;
+    nsSOCKSIOLayerMethods.poll = nsSOCKSIOLayerPoll;
+    nsSOCKSIOLayerMethods.bind = nsSOCKSIOLayerBind;
+    nsSOCKSIOLayerMethods.acceptread = nsSOCKSIOLayerAcceptRead;
+    nsSOCKSIOLayerMethods.getsockname = nsSOCKSIOLayerGetName;
+    nsSOCKSIOLayerMethods.getpeername = nsSOCKSIOLayerGetPeerName;
+    nsSOCKSIOLayerMethods.accept = nsSOCKSIOLayerAccept;
+    nsSOCKSIOLayerMethods.listen = nsSOCKSIOLayerListen;
+    nsSOCKSIOLayerMethods.close = nsSOCKSIOLayerClose;
+
+    firstTime = false;
+  }
+
+  LOGDEBUG(("Entering nsSOCKSIOLayerAddToSocket()."));
+
+  PRFileDesc* layer;
+  PRStatus rv;
+
+  layer = PR_CreateIOLayerStub(nsSOCKSIOLayerIdentity, &nsSOCKSIOLayerMethods);
+  if (!layer) {
+    LOGERROR(("PR_CreateIOLayerStub() failed."));
+    return NS_ERROR_FAILURE;
+  }
+
+  nsSOCKSSocketInfo* infoObject = new nsSOCKSSocketInfo();
+  if (!infoObject) {
+    // clean up IOLayerStub
+    LOGERROR(("Failed to create nsSOCKSSocketInfo()."));
+    PR_Free(layer);  // PR_CreateIOLayerStub() uses PR_Malloc().
+    return NS_ERROR_FAILURE;
+  }
+
+  NS_ADDREF(infoObject);
+  infoObject->Init(socksVersion, family, proxy, host, flags, tlsFlags);
+  layer->secret = (PRFilePrivate*)infoObject;
+
+  PRDescIdentity fdIdentity = PR_GetLayersIdentity(fd);
+#if defined(XP_WIN)
+  if (fdIdentity == mozilla::net::nsNamedPipeLayerIdentity) {
+    // remember named pipe fd on the info object so that we can switch
+    // blocking and non-blocking mode on the pipe later.
+    infoObject->SetNamedPipeFD(fd);
+  }
+#endif
+  rv = PR_PushIOLayer(fd, fdIdentity, layer);
+
+  if (rv == PR_FAILURE) {
+    LOGERROR(("PR_PushIOLayer() failed. rv = %x.", rv));
+    NS_RELEASE(infoObject);
+    PR_Free(layer);  // PR_CreateIOLayerStub() uses PR_Malloc().
+    return NS_ERROR_FAILURE;
+  }
+
+  return NS_OK;
+}
+
+bool IsHostLocalTarget(const nsACString& aHost) {
+#if defined(XP_UNIX)
+  return StringBeginsWith(aHost, "file:"_ns);
+#elif defined(XP_WIN)
+  return IsNamedPipePath(aHost);
+#else
+  return false;
+#endif  // XP_UNIX
+}
diff --git a/netwerk/socket/nsSOCKSIOLayer.h b/netwerk/socket/nsSOCKSIOLayer.h
new file mode 100644
index 0000000000..576c96ea7f
--- /dev/null
+++ b/netwerk/socket/nsSOCKSIOLayer.h
@@ -0,0 +1,21 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsSOCKSIOLayer_h__
+#define nsSOCKSIOLayer_h__
+
+#include "prio.h"
+#include "nscore.h"
+#include "nsIProxyInfo.h"
+
+nsresult nsSOCKSIOLayerAddToSocket(int32_t family, const char* host,
+                                   int32_t port, nsIProxyInfo* proxyInfo,
+                                   int32_t socksVersion, uint32_t flags,
+                                   uint32_t tlsFlags, PRFileDesc* fd);
+
+bool IsHostLocalTarget(const nsACString& aHost);
+
+#endif /* nsSOCKSIOLayer_h__ */
diff --git a/netwerk/socket/nsSOCKSSocketProvider.cpp b/netwerk/socket/nsSOCKSSocketProvider.cpp
new file mode 100644
index 0000000000..fc18e8e788
--- /dev/null
+++ b/netwerk/socket/nsSOCKSSocketProvider.cpp
@@ -0,0 +1,98 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsNamedPipeIOLayer.h"
+#include "nsSOCKSSocketProvider.h"
+#include "nsSOCKSIOLayer.h"
+#include "nsCOMPtr.h"
+#include "nsError.h"
+
+using mozilla::OriginAttributes;
+using namespace mozilla::net;
+
+//////////////////////////////////////////////////////////////////////////
+
+NS_IMPL_ISUPPORTS(nsSOCKSSocketProvider, nsISocketProvider)
+
+// Per-platform implemenation of OpenTCPSocket helper function
+// Different platforms have special cases to handle
+
+#if defined(XP_WIN)
+// The proxy host on Windows may be a named pipe uri, in which
+// case a named-pipe (rather than a socket) should be returned
+static PRFileDesc* OpenTCPSocket(int32_t family, nsIProxyInfo* proxy) {
+  PRFileDesc* sock = nullptr;
+
+  nsAutoCString proxyHost;
+  proxy->GetHost(proxyHost);
+  if (IsNamedPipePath(proxyHost)) {
+    sock = CreateNamedPipeLayer();
+  } else {
+    sock = PR_OpenTCPSocket(family);
+  }
+
+  return sock;
+}
+#elif defined(XP_UNIX)
+// The proxy host on UNIX systems may point to a local file uri
+// in which case we should create an AF_LOCAL (UNIX Domain) socket
+// instead of the requested AF_INET or AF_INET6 socket.
+
+// Normally,this socket would get thrown out and recreated later on
+// with the proper family, but we want to do it early here so that
+// we can enforce seccomp policy to blacklist socket(AF_INET) calls
+// to prevent the content sandbox from creating network requests
+static PRFileDesc* OpenTCPSocket(int32_t family, nsIProxyInfo* proxy) {
+  nsAutoCString proxyHost;
+  proxy->GetHost(proxyHost);
+  if (StringBeginsWith(proxyHost, "file://"_ns)) {
+    family = AF_LOCAL;
+  }
+
+  return PR_OpenTCPSocket(family);
+}
+#else
+// Default, pass-through to PR_OpenTCPSocket
+static PRFileDesc* OpenTCPSocket(int32_t family, nsIProxyInfo*) {
+  return PR_OpenTCPSocket(family);
+}
+#endif
+
+NS_IMETHODIMP
+nsSOCKSSocketProvider::NewSocket(int32_t family, const char* host, int32_t port,
+                                 nsIProxyInfo* proxy,
+                                 const OriginAttributes& originAttributes,
+                                 uint32_t flags, uint32_t tlsFlags,
+                                 PRFileDesc** result,
+                                 nsITLSSocketControl** tlsSocketControl) {
+  PRFileDesc* sock = OpenTCPSocket(family, proxy);
+  if (!sock) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  nsresult rv = nsSOCKSIOLayerAddToSocket(family, host, port, proxy, mVersion,
+                                          flags, tlsFlags, sock);
+  if (NS_SUCCEEDED(rv)) {
+    *result = sock;
+    return NS_OK;
+  }
+
+  return NS_ERROR_SOCKET_CREATE_FAILED;
+}
+
+NS_IMETHODIMP
+nsSOCKSSocketProvider::AddToSocket(int32_t family, const char* host,
+                                   int32_t port, nsIProxyInfo* proxy,
+                                   const OriginAttributes& originAttributes,
+                                   uint32_t flags, uint32_t tlsFlags,
+                                   PRFileDesc* sock,
+                                   nsITLSSocketControl** tlsSocketControl) {
+  nsresult rv = nsSOCKSIOLayerAddToSocket(family, host, port, proxy, mVersion,
+                                          flags, tlsFlags, sock);
+
+  if (NS_FAILED(rv)) rv = NS_ERROR_SOCKET_CREATE_FAILED;
+  return rv;
+}
diff --git a/netwerk/socket/nsSOCKSSocketProvider.h b/netwerk/socket/nsSOCKSSocketProvider.h
new file mode 100644
index 0000000000..2733856733
--- /dev/null
+++ b/netwerk/socket/nsSOCKSSocketProvider.h
@@ -0,0 +1,28 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsSOCKSSocketProvider_h__
+#define nsSOCKSSocketProvider_h__
+
+#include "nsISocketProvider.h"
+
+// values for ctor's |version| argument
+enum { NS_SOCKS_VERSION_4 = 4, NS_SOCKS_VERSION_5 = 5 };
+
+class nsSOCKSSocketProvider : public nsISocketProvider {
+ public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSISOCKETPROVIDER
+
+  explicit nsSOCKSSocketProvider(uint32_t version) : mVersion(version) {}
+
+ private:
+  virtual ~nsSOCKSSocketProvider() = default;
+
+  uint32_t mVersion;  // NS_SOCKS_VERSION_4 or 5
+};
+
+#endif /* nsSOCKSSocketProvider_h__ */
diff --git a/netwerk/socket/nsSocketProviderService.cpp b/netwerk/socket/nsSocketProviderService.cpp
new file mode 100644
index 0000000000..737820890e
--- /dev/null
+++ b/netwerk/socket/nsSocketProviderService.cpp
@@ -0,0 +1,72 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsString.h"
+#include "nsISocketProvider.h"
+#include "nsError.h"
+#include "nsNSSComponent.h"
+#include "nsSOCKSSocketProvider.h"
+#include "nsSocketProviderService.h"
+#include "nsSSLSocketProvider.h"
+#include "nsTLSSocketProvider.h"
+#include "nsUDPSocketProvider.h"
+#include "mozilla/ClearOnShutdown.h"
+#include "nsThreadUtils.h"
+#include "nsCRT.h"
+
+mozilla::StaticRefPtr<nsSocketProviderService>
+    nsSocketProviderService::gSingleton;
+
+////////////////////////////////////////////////////////////////////////////////
+
+already_AddRefed<nsISocketProviderService>
+nsSocketProviderService::GetOrCreate() {
+  RefPtr<nsSocketProviderService> inst;
+  if (gSingleton) {
+    inst = gSingleton;
+  } else {
+    inst = new nsSocketProviderService();
+    gSingleton = inst;
+    if (NS_IsMainThread()) {
+      mozilla::ClearOnShutdown(&gSingleton);
+    } else {
+      NS_DispatchToMainThread(NS_NewRunnableFunction(
+          "net::nsSocketProviderService::GetOrCreate",
+          []() -> void { mozilla::ClearOnShutdown(&gSingleton); }));
+    }
+  }
+  return inst.forget();
+}
+
+NS_IMPL_ISUPPORTS(nsSocketProviderService, nsISocketProviderService)
+
+////////////////////////////////////////////////////////////////////////////////
+
+NS_IMETHODIMP
+nsSocketProviderService::GetSocketProvider(const char* type,
+                                           nsISocketProvider** result) {
+  nsCOMPtr<nsISocketProvider> inst;
+  if (!nsCRT::strcmp(type, "ssl") &&
+      (XRE_IsParentProcess() || XRE_IsSocketProcess()) &&
+      EnsureNSSInitializedChromeOrContent()) {
+    inst = new nsSSLSocketProvider();
+  } else if (!nsCRT::strcmp(type, "starttls") &&
+             (XRE_IsParentProcess() || XRE_IsSocketProcess()) &&
+             EnsureNSSInitializedChromeOrContent()) {
+    inst = new nsTLSSocketProvider();
+  } else if (!nsCRT::strcmp(type, "socks")) {
+    inst = new nsSOCKSSocketProvider(NS_SOCKS_VERSION_5);
+  } else if (!nsCRT::strcmp(type, "socks4")) {
+    inst = new nsSOCKSSocketProvider(NS_SOCKS_VERSION_4);
+  } else if (!nsCRT::strcmp(type, "udp")) {
+    inst = new nsUDPSocketProvider();
+  } else {
+    return NS_ERROR_UNKNOWN_SOCKET_TYPE;
+  }
+  inst.forget(result);
+  return NS_OK;
+}
+
+////////////////////////////////////////////////////////////////////////////////
diff --git a/netwerk/socket/nsSocketProviderService.h b/netwerk/socket/nsSocketProviderService.h
new file mode 100644
index 0000000000..85b2ba04a4
--- /dev/null
+++ b/netwerk/socket/nsSocketProviderService.h
@@ -0,0 +1,26 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsSocketProviderService_h__
+#define nsSocketProviderService_h__
+
+#include "nsISocketProviderService.h"
+#include "mozilla/StaticPtr.h"
+
+class nsSocketProviderService : public nsISocketProviderService {
+  nsSocketProviderService() = default;
+  virtual ~nsSocketProviderService() = default;
+
+ public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSISOCKETPROVIDERSERVICE
+
+  static already_AddRefed<nsISocketProviderService> GetOrCreate();
+
+ private:
+  static mozilla::StaticRefPtr<nsSocketProviderService> gSingleton;
+};
+
+#endif /* nsSocketProviderService_h__ */
diff --git a/netwerk/socket/nsUDPSocketProvider.cpp b/netwerk/socket/nsUDPSocketProvider.cpp
new file mode 100644
index 0000000000..e99ef36a6d
--- /dev/null
+++ b/netwerk/socket/nsUDPSocketProvider.cpp
@@ -0,0 +1,39 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsUDPSocketProvider.h"
+
+#include "nspr.h"
+
+using mozilla::OriginAttributes;
+
+NS_IMPL_ISUPPORTS(nsUDPSocketProvider, nsISocketProvider)
+
+NS_IMETHODIMP
+nsUDPSocketProvider::NewSocket(int32_t aFamily, const char* aHost,
+                               int32_t aPort, nsIProxyInfo* aProxy,
+                               const OriginAttributes& originAttributes,
+                               uint32_t aFlags, uint32_t aTlsFlags,
+                               PRFileDesc** aFileDesc,
+                               nsITLSSocketControl** aTLSSocketControl) {
+  NS_ENSURE_ARG_POINTER(aFileDesc);
+
+  PRFileDesc* udpFD = PR_OpenUDPSocket(aFamily);
+  if (!udpFD) return NS_ERROR_FAILURE;
+
+  *aFileDesc = udpFD;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsUDPSocketProvider::AddToSocket(int32_t aFamily, const char* aHost,
+                                 int32_t aPort, nsIProxyInfo* aProxy,
+                                 const OriginAttributes& originAttributes,
+                                 uint32_t aFlags, uint32_t aTlsFlags,
+                                 struct PRFileDesc* aFileDesc,
+                                 nsITLSSocketControl** aTLSSocketControl) {
+  // does not make sense to strap a UDP socket onto an existing socket
+  MOZ_ASSERT_UNREACHABLE("Cannot layer UDP socket on an existing socket");
+  return NS_ERROR_UNEXPECTED;
+}
diff --git a/netwerk/socket/nsUDPSocketProvider.h b/netwerk/socket/nsUDPSocketProvider.h
new file mode 100644
index 0000000000..fb1fe749d9
--- /dev/null
+++ b/netwerk/socket/nsUDPSocketProvider.h
@@ -0,0 +1,20 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsUDPSocketProvider_h__
+#define nsUDPSocketProvider_h__
+
+#include "nsISocketProvider.h"
+#include "mozilla/Attributes.h"
+
+class nsUDPSocketProvider final : public nsISocketProvider {
+ public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSISOCKETPROVIDER
+
+ private:
+  ~nsUDPSocketProvider() = default;
+};
+
+#endif /* nsUDPSocketProvider_h__ */