Adding upstream version 110.0.1.upstream/110.0.1upstream

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

13 files changed, 3084 insertions, 0 deletions

diff --git a/toolkit/components/bitsdownload/bits_client/.gitignore b/toolkit/components/bitsdownload/bits_client/.gitignore
new file mode 100644
index 0000000000..d78faf4575
--- /dev/null
+++ b/toolkit/components/bitsdownload/bits_client/.gitignore
@@ -0,0 +1,3 @@
+/target
+**/*.rs.bk
+**/.*.swp
diff --git a/toolkit/components/bitsdownload/bits_client/Cargo.toml b/toolkit/components/bitsdownload/bits_client/Cargo.toml
new file mode 100644
index 0000000000..eb0083d8e2
--- /dev/null
+++ b/toolkit/components/bitsdownload/bits_client/Cargo.toml
@@ -0,0 +1,19 @@
+[package]
+name = "bits_client"
+version = "0.2.0"
+authors = ["Adam Gashlin <agashlin@mozilla.com>"]
+license = "MPL-2.0"
+publish = false
+
+[dependencies]
+bits = { path = "./bits" }
+comedy = "0.2.0"
+guid_win = "0.2.0"
+thiserror = "1"
+
+[dev-dependencies]
+#ctrlc = "3.1.1"
+lazy_static = "1.0.1"
+rand = "0.8"
+regex = { version = "1", default_features = false, features = ["perf", "std"] }
+tempfile = "3"
diff --git a/toolkit/components/bitsdownload/bits_client/README.md b/toolkit/components/bitsdownload/bits_client/README.md
new file mode 100644
index 0000000000..0c21a5b68c
--- /dev/null
+++ b/toolkit/components/bitsdownload/bits_client/README.md
@@ -0,0 +1,23 @@
+bits\_client
+============
+
+Interfaces for BITS.
+
+bits\_client lib
+---------------
+
+`bits_client` is the primary target and provides `BitsClient`, an API for creating and monitoring BITS jobs.
+
+`bits_client::new()` creates a `BitsClient` that does all operations within the current process, as the current user.
+
+bits crate
+----------
+
+`bits` is a safe interface to BITS, providing connections to the
+Background Copy Manager, some basic operations on Background Copy Jobs, and
+methods for implementing `IBackgroundCopyCallback`s in Rust.
+
+test\_client example
+-------------------
+
+`examples/test_client.rs` shows how to use the API.
diff --git a/toolkit/components/bitsdownload/bits_client/bits/Cargo.toml b/toolkit/components/bitsdownload/bits_client/bits/Cargo.toml
new file mode 100644
index 0000000000..36b7b5ff89
--- /dev/null
+++ b/toolkit/components/bitsdownload/bits_client/bits/Cargo.toml
@@ -0,0 +1,31 @@
+[package]
+name = "bits"
+version = "0.2.0"
+authors = ["Adam Gashlin <agashlin@mozilla.com>"]
+license = "MIT/Apache-2.0"
+publish = false
+
+[features]
+status_serde = ["serde", "serde_derive"]
+
+[dependencies]
+comedy = "0.2.0"
+filetime_win = "0.2.0"
+guid_win = "0.2.0"
+serde = { version = "1.0.80", optional = true }
+serde_derive = { version = "1.0.80", optional = true }
+
+[dependencies.winapi]
+version = "0.3.7"
+features = ["basetsd",
+            "bits",
+            "bits2_5",
+            "bitsmsg",
+            "guiddef",
+            "minwindef",
+            "ntdef",
+            "rpcndr",
+            "unknwnbase",
+            "winerror",
+            "winnls",
+            ]
diff --git a/toolkit/components/bitsdownload/bits_client/bits/src/callback.rs b/toolkit/components/bitsdownload/bits_client/bits/src/callback.rs
new file mode 100644
index 0000000000..6dace83be8
--- /dev/null
+++ b/toolkit/components/bitsdownload/bits_client/bits/src/callback.rs
@@ -0,0 +1,205 @@
+// Licensed under the Apache License, Version 2.0
+// <LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
+// All files in the project carrying such notice may not be copied, modified, or distributed
+// except according to those terms.
+
+use std::panic::{catch_unwind, RefUnwindSafe};
+use std::ptr::NonNull;
+use std::sync::atomic::{AtomicUsize, Ordering};
+
+use comedy::{com::ComRef, HResult};
+use guid_win::Guid;
+use winapi::ctypes::c_void;
+use winapi::shared::guiddef::REFIID;
+use winapi::shared::minwindef::DWORD;
+use winapi::shared::ntdef::ULONG;
+use winapi::shared::winerror::{E_FAIL, E_NOINTERFACE, HRESULT, NOERROR, S_OK};
+use winapi::um::bits::{
+    IBackgroundCopyCallback, IBackgroundCopyCallbackVtbl, IBackgroundCopyError, IBackgroundCopyJob,
+};
+use winapi::um::unknwnbase::{IUnknown, IUnknownVtbl};
+use winapi::Interface;
+
+use BitsJob;
+
+/// The type of a notification callback.
+///
+/// The callbacks must be `Fn()` to be called arbitrarily many times, `RefUnwindSafe` to have a
+/// panic unwind safely caught, `Send`, `Sync` and `'static` to run on any thread COM invokes us on
+/// any time.
+///
+/// If the callback returns a non-success `HRESULT`, the notification may pass to other BITS
+/// mechanisms such as `IBackgroundCopyJob2::SetNotifyCmdLine`.
+pub type TransferredCallback =
+    dyn (Fn() -> Result<(), HRESULT>) + RefUnwindSafe + Send + Sync + 'static;
+pub type ErrorCallback = dyn (Fn() -> Result<(), HRESULT>) + RefUnwindSafe + Send + Sync + 'static;
+pub type ModificationCallback =
+    dyn (Fn() -> Result<(), HRESULT>) + RefUnwindSafe + Send + Sync + 'static;
+
+#[repr(C)]
+pub struct BackgroundCopyCallback {
+    // Everything assumes that the interface vtable is the first member of this struct.
+    interface: IBackgroundCopyCallback,
+    rc: AtomicUsize,
+    transferred_cb: Option<Box<TransferredCallback>>,
+    error_cb: Option<Box<ErrorCallback>>,
+    modification_cb: Option<Box<ModificationCallback>>,
+}
+
+impl BackgroundCopyCallback {
+    /// Construct the callback object and register it with a job.
+    ///
+    /// Only one notify interface can be present on a job at once, so this will release BITS'
+    /// ref to any previously registered interface.
+    pub fn register(
+        job: &mut BitsJob,
+        transferred_cb: Option<Box<TransferredCallback>>,
+        error_cb: Option<Box<ErrorCallback>>,
+        modification_cb: Option<Box<ModificationCallback>>,
+    ) -> Result<(), HResult> {
+        let cb = Box::new(BackgroundCopyCallback {
+            interface: IBackgroundCopyCallback { lpVtbl: &VTBL },
+            rc: AtomicUsize::new(1),
+            transferred_cb,
+            error_cb,
+            modification_cb,
+        });
+
+        // Leak the callback, it has no Rust owner until we need to drop it later.
+        // The ComRef will Release when it goes out of scope.
+        unsafe {
+            let cb = ComRef::from_raw(NonNull::new_unchecked(Box::into_raw(cb) as *mut IUnknown));
+
+            job.set_notify_interface(cb.as_raw_ptr())?;
+        }
+
+        Ok(())
+    }
+}
+
+extern "system" fn query_interface(
+    this: *mut IUnknown,
+    riid: REFIID,
+    obj: *mut *mut c_void,
+) -> HRESULT {
+    unsafe {
+        // `IBackgroundCopyCallback` is the first (currently only) interface on the
+        // `BackgroundCopyCallback` object, so we can return `this` either as
+        // `IUnknown` or `IBackgroundCopyCallback`.
+        if Guid(*riid) == Guid(IUnknown::uuidof())
+            || Guid(*riid) == Guid(IBackgroundCopyCallback::uuidof())
+        {
+            addref(this);
+            // Cast first to `IBackgroundCopyCallback` to be clear which `IUnknown`
+            // we are pointing at.
+            *obj = this as *mut IBackgroundCopyCallback as *mut c_void;
+            NOERROR
+        } else {
+            E_NOINTERFACE
+        }
+    }
+}
+
+extern "system" fn addref(raw_this: *mut IUnknown) -> ULONG {
+    unsafe {
+        let this = raw_this as *const BackgroundCopyCallback;
+
+        // Forge a reference for just this statement.
+        let old_rc = (*this).rc.fetch_add(1, Ordering::SeqCst);
+        (old_rc + 1) as ULONG
+    }
+}
+
+extern "system" fn release(raw_this: *mut IUnknown) -> ULONG {
+    unsafe {
+        {
+            let this = raw_this as *const BackgroundCopyCallback;
+
+            // Forge a reference for just this statement.
+            let old_rc = (*this).rc.fetch_sub(1, Ordering::SeqCst);
+
+            let rc = old_rc - 1;
+            if rc > 0 {
+                return rc as ULONG;
+            }
+        }
+
+        // rc will have been 0 for us to get here, and we're out of scope of the reference above,
+        // so there should be no references or pointers left (besides `this`).
+        // Re-Box and to drop immediately.
+        let _ = Box::from_raw(raw_this as *mut BackgroundCopyCallback);
+
+        0
+    }
+}
+
+extern "system" fn transferred_stub(
+    raw_this: *mut IBackgroundCopyCallback,
+    _job: *mut IBackgroundCopyJob,
+) -> HRESULT {
+    unsafe {
+        let this = raw_this as *const BackgroundCopyCallback;
+        // Forge a reference just for this statement.
+        if let Some(ref cb) = (*this).transferred_cb {
+            match catch_unwind(|| cb()) {
+                Ok(Ok(())) => S_OK,
+                Ok(Err(hr)) => hr,
+                Err(_) => E_FAIL,
+            }
+        } else {
+            S_OK
+        }
+    }
+}
+
+extern "system" fn error_stub(
+    raw_this: *mut IBackgroundCopyCallback,
+    _job: *mut IBackgroundCopyJob,
+    _error: *mut IBackgroundCopyError,
+) -> HRESULT {
+    unsafe {
+        let this = raw_this as *const BackgroundCopyCallback;
+        // Forge a reference just for this statement.
+        if let Some(ref cb) = (*this).error_cb {
+            match catch_unwind(|| cb()) {
+                Ok(Ok(())) => S_OK,
+                Ok(Err(hr)) => hr,
+                Err(_) => E_FAIL,
+            }
+        } else {
+            S_OK
+        }
+    }
+}
+
+extern "system" fn modification_stub(
+    raw_this: *mut IBackgroundCopyCallback,
+    _job: *mut IBackgroundCopyJob,
+    _reserved: DWORD,
+) -> HRESULT {
+    unsafe {
+        let this = raw_this as *const BackgroundCopyCallback;
+        // Forge a reference just for this statement.
+        if let Some(ref cb) = (*this).modification_cb {
+            match catch_unwind(|| cb()) {
+                Ok(Ok(())) => S_OK,
+                Ok(Err(hr)) => hr,
+                Err(_) => E_FAIL,
+            }
+        } else {
+            S_OK
+        }
+    }
+}
+
+pub static VTBL: IBackgroundCopyCallbackVtbl = IBackgroundCopyCallbackVtbl {
+    parent: IUnknownVtbl {
+        QueryInterface: query_interface,
+        AddRef: addref,
+        Release: release,
+    },
+    JobTransferred: transferred_stub,
+    JobError: error_stub,
+    JobModification: modification_stub,
+};
diff --git a/toolkit/components/bitsdownload/bits_client/bits/src/lib.rs b/toolkit/components/bitsdownload/bits_client/bits/src/lib.rs
new file mode 100644
index 0000000000..09da2b0349
--- /dev/null
+++ b/toolkit/components/bitsdownload/bits_client/bits/src/lib.rs
@@ -0,0 +1,592 @@
+// Licensed under the Apache License, Version 2.0
+// <LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
+// All files in the project carrying such notice may not be copied, modified, or distributed
+// except according to those terms.
+
+//! A safe interface for BITS
+//!
+//! The primary entry point into BITS is the
+//! [`BackgroundCopyManager`](struct.BackgroundCopyManager.html) struct.
+//!
+//! Functionality is only provided by this crate on an as-needed basis for
+//! [bits_client](../bits_client/index.html), so there are vast swathes of the BITS API
+//! unsupported.
+
+extern crate comedy;
+extern crate filetime_win;
+extern crate guid_win;
+extern crate winapi;
+
+#[cfg(feature = "status_serde")]
+extern crate serde;
+#[cfg(feature = "status_serde")]
+extern crate serde_derive;
+
+mod callback;
+pub mod status;
+mod wide;
+
+use std::ffi::{OsStr, OsString};
+use std::mem;
+use std::os::windows::ffi::OsStringExt;
+use std::ptr;
+use std::result;
+
+use comedy::com::{create_instance_local_server, CoTaskMem, ComRef, INIT_MTA};
+use comedy::error::{HResult, ResultExt};
+use comedy::{com_call, com_call_getter, com_call_taskmem_getter};
+use filetime_win::FileTime;
+use guid_win::Guid;
+use winapi::shared::minwindef::DWORD;
+use winapi::shared::ntdef::{HRESULT, LANGIDFROMLCID, ULONG};
+use winapi::shared::winerror::S_FALSE;
+use winapi::um::bits::{
+    IBackgroundCopyError, IBackgroundCopyFile, IBackgroundCopyJob, IBackgroundCopyManager,
+    IEnumBackgroundCopyFiles, IEnumBackgroundCopyJobs, BG_JOB_PRIORITY, BG_JOB_PRIORITY_FOREGROUND,
+    BG_JOB_PRIORITY_HIGH, BG_JOB_PRIORITY_LOW, BG_JOB_PRIORITY_NORMAL, BG_JOB_PROXY_USAGE,
+    BG_JOB_PROXY_USAGE_AUTODETECT, BG_JOB_PROXY_USAGE_NO_PROXY, BG_JOB_PROXY_USAGE_PRECONFIG,
+    BG_JOB_STATE_ERROR, BG_JOB_STATE_TRANSIENT_ERROR, BG_JOB_TYPE_DOWNLOAD, BG_NOTIFY_DISABLE,
+    BG_NOTIFY_JOB_ERROR, BG_NOTIFY_JOB_MODIFICATION, BG_NOTIFY_JOB_TRANSFERRED, BG_SIZE_UNKNOWN,
+};
+use winapi::um::bits2_5::{IBackgroundCopyJobHttpOptions, BG_HTTP_REDIRECT_POLICY_ALLOW_REPORT};
+use winapi::um::bitsmsg::BG_E_NOT_FOUND;
+use winapi::um::unknwnbase::IUnknown;
+use winapi::um::winnls::GetThreadLocale;
+
+pub use winapi::um::bits::{BG_ERROR_CONTEXT, BG_JOB_STATE};
+pub use winapi::um::bitsmsg::{BG_S_PARTIAL_COMPLETE, BG_S_UNABLE_TO_DELETE_FILES};
+
+pub use status::{
+    BitsErrorContext, BitsJobError, BitsJobProgress, BitsJobState, BitsJobStatus, BitsJobTimes,
+};
+use wide::ToWideNull;
+
+pub use winapi::shared::winerror::E_FAIL;
+
+#[repr(u32)]
+#[derive(Copy, Clone, Debug)]
+pub enum BitsJobPriority {
+    Foreground = BG_JOB_PRIORITY_FOREGROUND,
+    High = BG_JOB_PRIORITY_HIGH,
+    /// Default
+    Normal = BG_JOB_PRIORITY_NORMAL,
+    Low = BG_JOB_PRIORITY_LOW,
+}
+
+#[repr(u32)]
+#[derive(Copy, Clone, Debug)]
+pub enum BitsProxyUsage {
+    /// Directly access the network.
+    NoProxy = BG_JOB_PROXY_USAGE_NO_PROXY,
+    /// Use Internet Explorer proxy settings. This is the default.
+    Preconfig = BG_JOB_PROXY_USAGE_PRECONFIG,
+    /// Attempt to auto-detect the connection's proxy settings.
+    AutoDetect = BG_JOB_PROXY_USAGE_AUTODETECT,
+}
+
+type Result<T> = result::Result<T, HResult>;
+
+pub struct BackgroundCopyManager(ComRef<IBackgroundCopyManager>);
+
+impl BackgroundCopyManager {
+    /// Get access to the local BITS service.
+    ///
+    /// # COM Initialization and Threading Model #
+    ///
+    /// This method uses a thread local variable to initialize COM with a multithreaded apartment
+    /// model for this thread, and leaves it this way until the thread local is dropped.
+    /// If the thread was in a single-threaded apartment, `connect()` will fail gracefully.
+    ///
+    /// # Safety #
+    ///
+    /// If there are mismatched `CoUninitialize` calls on this thread which lead to COM shutting
+    /// down before this thread ends, unsafe behavior may result.
+    pub fn connect() -> Result<BackgroundCopyManager> {
+        INIT_MTA.with(|com| {
+            if let Err(e) = com {
+                return Err(e.clone());
+            }
+            Ok(())
+        })?;
+
+        // Assuming no mismatched CoUninitialize calls, methods do not have to check for
+        // successfully initialized COM once the object is constructed: `BackgroundCopyManager`
+        // is not `Send` or `Sync` so it must be used on the thread it was constructed on,
+        // which has now successfully inited MTA for the lifetime of thread local `INIT_MTA`.
+        // This also holds for any functions using pointers only derived from these methods, like
+        // the `BitsJob` methods.
+
+        Ok(BackgroundCopyManager(create_instance_local_server::<
+            winapi::um::bits::BackgroundCopyManager,
+            IBackgroundCopyManager,
+        >()?))
+    }
+
+    /// Create a new download job with the given name.
+    pub fn create_job(&self, display_name: &OsStr) -> Result<BitsJob> {
+        unsafe {
+            let mut guid = mem::zeroed();
+            Ok(BitsJob(com_call_getter!(
+                |job| self.0,
+                IBackgroundCopyManager::CreateJob(
+                    display_name.to_wide_null().as_ptr(),
+                    BG_JOB_TYPE_DOWNLOAD,
+                    &mut guid,
+                    job,
+                )
+            )?))
+        }
+    }
+
+    /// Cancel all jobs with the given name.
+    ///
+    /// This only attempts to cancel jobs owned by the current user.
+    /// No errors are returned for jobs that failed to cancel.
+    pub fn cancel_jobs_by_name(&self, match_name: &OsStr) -> Result<()> {
+        let jobs =
+            unsafe { com_call_getter!(|jobs| self.0, IBackgroundCopyManager::EnumJobs(0, jobs))? };
+
+        loop {
+            let result = unsafe {
+                com_call_getter!(
+                    |job| jobs,
+                    IEnumBackgroundCopyJobs::Next(1, job, ptr::null_mut())
+                )
+            };
+            match result {
+                Ok(job) => {
+                    if job_name_eq(&job, match_name)? {
+                        unsafe {
+                            let _ = com_call!(job, IBackgroundCopyJob::Cancel());
+                        }
+                    }
+                }
+                Err(e) => {
+                    if e.code() == S_FALSE {
+                        // Ran out of jobs to enumerate
+                        return Ok(());
+                    } else {
+                        return Err(e);
+                    }
+                }
+            }
+        }
+    }
+
+    /// Get the job with the given GUID.
+    ///
+    /// Returns Err if the job was not found.
+    pub fn get_job_by_guid(&self, guid: &Guid) -> Result<BitsJob> {
+        unsafe { com_call_getter!(|job| self.0, IBackgroundCopyManager::GetJob(&guid.0, job)) }
+            .map(BitsJob)
+    }
+
+    /// Try to find a job with a given GUID.
+    ///
+    /// Returns Ok(None) if the job was not found but there was no other error.
+    pub fn find_job_by_guid(&self, guid: &Guid) -> Result<Option<BitsJob>> {
+        Ok(self
+            .get_job_by_guid(guid)
+            .map(Some)
+            .allow_err(BG_E_NOT_FOUND as i32, None)?)
+    }
+
+    /// Try to find a job with a given GUID and name.
+    ///
+    /// Returns Ok(None) if the job was not found, or if it had the wrong name, as long as there
+    /// was no other error.
+    pub fn find_job_by_guid_and_name(
+        &self,
+        guid: &Guid,
+        match_name: &OsStr,
+    ) -> Result<Option<BitsJob>> {
+        Ok(match self.find_job_by_guid(guid)? {
+            None => None,
+            Some(BitsJob(ref job)) if !job_name_eq(job, match_name)? => None,
+            result => result,
+        })
+    }
+
+    /// Translate a BITS `HRESULT` to a textual description.
+    ///
+    /// This uses the current thread's locale to look up the message associated with a BITS
+    /// error. It should only be used for `HRESULT`s returned from BITS COM interfaces.
+    pub fn get_error_description(&self, hr: HRESULT) -> Result<String> {
+        unsafe {
+            let language_id = DWORD::from(LANGIDFROMLCID(GetThreadLocale()));
+
+            Ok(taskmem_into_lossy_string(com_call_taskmem_getter!(
+                |desc| self.0,
+                IBackgroundCopyManager::GetErrorDescription(hr, language_id, desc)
+            )?))
+        }
+    }
+}
+
+unsafe fn taskmem_into_lossy_string(taskmem: CoTaskMem<u16>) -> String {
+    OsString::from_wide(taskmem.as_slice_until_null())
+        .to_string_lossy()
+        .into_owned()
+}
+
+fn job_name_eq(job: &ComRef<IBackgroundCopyJob>, match_name: &OsStr) -> Result<bool> {
+    let job_name = unsafe {
+        OsString::from_wide(
+            com_call_taskmem_getter!(|name| job, IBackgroundCopyJob::GetDisplayName(name))?
+                .as_slice_until_null(),
+        )
+    };
+
+    Ok(job_name == match_name)
+}
+
+pub struct BitsJob(ComRef<IBackgroundCopyJob>);
+
+impl BitsJob {
+    /// Get the job's GUID.
+    pub fn guid(&self) -> Result<Guid> {
+        // TODO: cache on create or retrieved by GUID?
+        unsafe {
+            let mut guid = mem::zeroed();
+            com_call!(self.0, IBackgroundCopyJob::GetId(&mut guid))?;
+            Ok(Guid(guid))
+        }
+    }
+
+    /// Add a file to the job.
+    pub fn add_file(&mut self, remote_url: &OsStr, local_file: &OsStr) -> Result<()> {
+        unsafe {
+            com_call!(
+                self.0,
+                IBackgroundCopyJob::AddFile(
+                    remote_url.to_wide_null().as_ptr(),
+                    local_file.to_wide_null().as_ptr(),
+                )
+            )
+        }?;
+        Ok(())
+    }
+
+    /// Get the first file in the job.
+    ///
+    /// This is provided for collecting the redirected remote name of single file jobs.
+    pub fn get_first_file(&mut self) -> Result<BitsFile> {
+        let files = unsafe { com_call_getter!(|e| self.0, IBackgroundCopyJob::EnumFiles(e))? };
+
+        let file = unsafe {
+            com_call_getter!(
+                |file| files,
+                IEnumBackgroundCopyFiles::Next(1, file, ptr::null_mut())
+            )?
+        };
+
+        Ok(BitsFile(file))
+    }
+
+    /// Set the job's description string.
+    ///
+    /// This is different from the display name set when creating the job.
+    pub fn set_description(&mut self, description: &OsStr) -> Result<()> {
+        unsafe {
+            com_call!(
+                self.0,
+                IBackgroundCopyJob::SetDescription(description.to_wide_null().as_ptr())
+            )
+        }?;
+        Ok(())
+    }
+
+    /// Change the job's proxy usage setting.
+    ///
+    /// The default is `BitsProxyUsage::Preconfig`.
+    pub fn set_proxy_usage(&mut self, usage: BitsProxyUsage) -> Result<()> {
+        use BitsProxyUsage::*;
+
+        match usage {
+            Preconfig | NoProxy | AutoDetect => {
+                unsafe {
+                    com_call!(
+                        self.0,
+                        IBackgroundCopyJob::SetProxySettings(
+                            usage as BG_JOB_PROXY_USAGE,
+                            ptr::null_mut(),
+                            ptr::null_mut(),
+                        )
+                    )
+                }?;
+                Ok(())
+            }
+        }
+    }
+
+    /// Change the job's priority.
+    ///
+    /// The default is `BitsJobPriority::Normal`.
+    pub fn set_priority(&mut self, priority: BitsJobPriority) -> Result<()> {
+        unsafe {
+            com_call!(
+                self.0,
+                IBackgroundCopyJob::SetPriority(priority as BG_JOB_PRIORITY)
+            )
+        }?;
+        Ok(())
+    }
+
+    pub fn set_minimum_retry_delay(&mut self, seconds: ULONG) -> Result<()> {
+        unsafe { com_call!(self.0, IBackgroundCopyJob::SetMinimumRetryDelay(seconds)) }?;
+        Ok(())
+    }
+
+    pub fn set_no_progress_timeout(&mut self, seconds: ULONG) -> Result<()> {
+        unsafe { com_call!(self.0, IBackgroundCopyJob::SetNoProgressTimeout(seconds)) }?;
+        Ok(())
+    }
+
+    /// Enable HTTP redirect reporting.
+    ///
+    /// The default setting is to allow HTTP redirects, but to not report them in any way. With
+    /// this setting enabled, the remote name of a file will be updated to reflect the redirect.
+    ///
+    /// # Compatibility #
+    ///
+    /// First available in Windows Vista.
+    pub fn set_redirect_report(&mut self) -> Result<()> {
+        unsafe {
+            com_call!(
+                self.0.cast()?,
+                IBackgroundCopyJobHttpOptions::SetSecurityFlags(
+                    BG_HTTP_REDIRECT_POLICY_ALLOW_REPORT
+                )
+            )
+        }?;
+
+        Ok(())
+    }
+
+    /// Resume the job. This must be done at least once to initially enqueue the job.
+    pub fn resume(&mut self) -> Result<()> {
+        unsafe { com_call!(self.0, IBackgroundCopyJob::Resume()) }?;
+        Ok(())
+    }
+
+    pub fn suspend(&mut self) -> Result<()> {
+        unsafe { com_call!(self.0, IBackgroundCopyJob::Suspend()) }?;
+        Ok(())
+    }
+
+    /// Complete the job, moving the local files to their final names.
+    ///
+    /// Has two interesting success `HRESULT`s: `BG_S_PARTIAL_COMPLETE` and
+    /// `BG_S_UNABLE_TO_DELETE_FILES`.
+    pub fn complete(&mut self) -> Result<HRESULT> {
+        unsafe { com_call!(self.0, IBackgroundCopyJob::Complete()) }
+    }
+
+    /// Cancel the job, deleting any temporary files.
+    ///
+    /// Has an interesting success `HRESULT`: `BG_S_UNABLE_TO_DELETE_FILES`.
+    pub fn cancel(&mut self) -> Result<HRESULT> {
+        unsafe { com_call!(self.0, IBackgroundCopyJob::Cancel()) }
+    }
+
+    /// Set the notification callbacks to use with this job.
+    ///
+    /// This will replace any previously set callbacks.
+    pub fn register_callbacks(
+        &mut self,
+        transferred_cb: Option<Box<callback::TransferredCallback>>,
+        error_cb: Option<Box<callback::ErrorCallback>>,
+        modification_cb: Option<Box<callback::ModificationCallback>>,
+    ) -> Result<()> {
+        let mut flags = 0;
+        if transferred_cb.is_some() {
+            flags |= BG_NOTIFY_JOB_TRANSFERRED;
+        }
+        if error_cb.is_some() {
+            flags |= BG_NOTIFY_JOB_ERROR;
+        }
+        if modification_cb.is_some() {
+            flags |= BG_NOTIFY_JOB_MODIFICATION;
+        }
+
+        callback::BackgroundCopyCallback::register(
+            self,
+            transferred_cb,
+            error_cb,
+            modification_cb,
+        )?;
+
+        unsafe { com_call!(self.0, IBackgroundCopyJob::SetNotifyFlags(flags)) }?;
+
+        Ok(())
+    }
+
+    fn _clear_callbacks(&mut self) -> Result<()> {
+        unsafe {
+            com_call!(
+                self.0,
+                IBackgroundCopyJob::SetNotifyFlags(BG_NOTIFY_DISABLE)
+            )?;
+
+            self.set_notify_interface(ptr::null_mut() as *mut IUnknown)
+        }
+    }
+
+    /// Collect the current status of the job, including errors.
+    pub fn get_status(&self) -> Result<BitsJobStatus> {
+        let mut state = 0;
+        let mut progress = unsafe { mem::zeroed() };
+        let mut error_count = 0;
+        let mut times = unsafe { mem::zeroed() };
+
+        unsafe {
+            com_call!(self.0, IBackgroundCopyJob::GetState(&mut state))?;
+            com_call!(self.0, IBackgroundCopyJob::GetProgress(&mut progress))?;
+            com_call!(self.0, IBackgroundCopyJob::GetErrorCount(&mut error_count))?;
+            com_call!(self.0, IBackgroundCopyJob::GetTimes(&mut times))?;
+        }
+
+        Ok(BitsJobStatus {
+            state: BitsJobState::from(state),
+            progress: BitsJobProgress {
+                total_bytes: if progress.BytesTotal == BG_SIZE_UNKNOWN {
+                    None
+                } else {
+                    Some(progress.BytesTotal)
+                },
+                transferred_bytes: progress.BytesTransferred,
+                total_files: progress.FilesTotal,
+                transferred_files: progress.FilesTransferred,
+            },
+            error_count,
+            error: if state == BG_JOB_STATE_ERROR || state == BG_JOB_STATE_TRANSIENT_ERROR {
+                let error_obj =
+                    unsafe { com_call_getter!(|e| self.0, IBackgroundCopyJob::GetError(e)) }?;
+
+                Some(BitsJob::get_error(error_obj)?)
+            } else {
+                None
+            },
+            times: BitsJobTimes {
+                creation: FileTime(times.CreationTime),
+                modification: FileTime(times.ModificationTime),
+                transfer_completion: if times.TransferCompletionTime.dwLowDateTime == 0
+                    && times.TransferCompletionTime.dwHighDateTime == 0
+                {
+                    None
+                } else {
+                    Some(FileTime(times.TransferCompletionTime))
+                },
+            },
+        })
+    }
+
+    fn get_error(error_obj: ComRef<IBackgroundCopyError>) -> Result<BitsJobError> {
+        let mut context = 0;
+        let mut hresult = 0;
+        unsafe {
+            com_call!(
+                error_obj,
+                IBackgroundCopyError::GetError(&mut context, &mut hresult)
+            )?;
+
+            let language_id = DWORD::from(LANGIDFROMLCID(GetThreadLocale()));
+
+            let context = BitsErrorContext::from(context);
+            let context_str = com_call_taskmem_getter!(
+                |desc| error_obj,
+                IBackgroundCopyError::GetErrorContextDescription(language_id, desc)
+            )
+            .map(|s| taskmem_into_lossy_string(s))
+            .unwrap_or_else(|_| format!("{:?}", context));
+            let error_str = com_call_taskmem_getter!(
+                |desc| error_obj,
+                IBackgroundCopyError::GetErrorDescription(language_id, desc)
+            )
+            .map(|s| taskmem_into_lossy_string(s))
+            .unwrap_or_else(|_| format!("{:#08x}", hresult));
+
+            Ok(BitsJobError {
+                context,
+                context_str,
+                error: hresult,
+                error_str,
+            })
+        }
+    }
+
+    unsafe fn set_notify_interface(&self, interface: *mut IUnknown) -> Result<()> {
+        com_call!(self.0, IBackgroundCopyJob::SetNotifyInterface(interface))?;
+        Ok(())
+    }
+}
+
+pub struct BitsFile(ComRef<IBackgroundCopyFile>);
+
+/// A single file in a BITS job.
+///
+/// This is provided for collecting the redirected remote name.
+impl BitsFile {
+    /// Get the remote name from which the file is being downloaded.
+    ///
+    /// If [`BitsJob::set_redirect_report()`](struct.BitsJob.html#method.set_redirect_report)
+    /// hasn't been called on the job, this won't be
+    /// updated as HTTP redirects are processed.
+    pub fn get_remote_name(&self) -> Result<OsString> {
+        unsafe {
+            Ok(OsString::from_wide(
+                com_call_taskmem_getter!(|name| self.0, IBackgroundCopyFile::GetRemoteName(name))?
+                    .as_slice_until_null(),
+            ))
+        }
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::BackgroundCopyManager;
+    use std::ffi::OsString;
+    use std::mem;
+
+    #[test]
+    #[ignore]
+    fn test_find_job() {
+        let bcm = BackgroundCopyManager::connect().unwrap();
+        let name = OsString::from("bits test job");
+        let wrong_name = OsString::from("bits test jobbo");
+
+        let mut job = bcm.create_job(&name).unwrap();
+        let guid = job.guid().unwrap();
+
+        assert_eq!(
+            bcm.find_job_by_guid(&guid)
+                .unwrap()
+                .unwrap()
+                .guid()
+                .unwrap(),
+            guid
+        );
+        assert_eq!(
+            bcm.find_job_by_guid_and_name(&guid, &name)
+                .unwrap()
+                .unwrap()
+                .guid()
+                .unwrap(),
+            guid
+        );
+        assert!(bcm
+            .find_job_by_guid_and_name(&guid, &wrong_name)
+            .unwrap()
+            .is_none());
+
+        job.cancel().unwrap();
+        mem::drop(job);
+
+        assert!(bcm.find_job_by_guid(&guid).unwrap().is_none());
+        assert!(bcm
+            .find_job_by_guid_and_name(&guid, &name)
+            .unwrap()
+            .is_none());
+    }
+}
diff --git a/toolkit/components/bitsdownload/bits_client/bits/src/status.rs b/toolkit/components/bitsdownload/bits_client/bits/src/status.rs
new file mode 100644
index 0000000000..648a26866e
--- /dev/null
+++ b/toolkit/components/bitsdownload/bits_client/bits/src/status.rs
@@ -0,0 +1,118 @@
+// Licensed under the Apache License, Version 2.0
+// <LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
+// All files in the project carrying such notice may not be copied, modified, or distributed
+// except according to those terms.
+
+//! Data types for reporting a job's status
+
+use filetime_win::FileTime;
+use winapi::shared::winerror::HRESULT;
+use winapi::um::bits::{BG_ERROR_CONTEXT, BG_JOB_STATE};
+
+#[cfg(feature = "status_serde")]
+use serde_derive::{Deserialize, Serialize};
+
+#[derive(Clone, Debug)]
+#[cfg_attr(feature = "status_serde", derive(Serialize, Deserialize))]
+pub struct BitsJobStatus {
+    pub state: BitsJobState,
+    pub progress: BitsJobProgress,
+    pub error_count: u32,
+    pub error: Option<BitsJobError>,
+    pub times: BitsJobTimes,
+}
+
+#[derive(Clone, Debug)]
+#[cfg_attr(feature = "status_serde", derive(Serialize, Deserialize))]
+pub struct BitsJobError {
+    pub context: BitsErrorContext,
+    pub context_str: String,
+    pub error: HRESULT,
+    pub error_str: String,
+}
+
+#[derive(Copy, Clone, Debug, Eq, PartialEq)]
+#[cfg_attr(feature = "status_serde", derive(Serialize, Deserialize))]
+pub enum BitsErrorContext {
+    None,
+    Unknown,
+    GeneralQueueManager,
+    QueueManagerNotification,
+    LocalFile,
+    RemoteFile,
+    GeneralTransport,
+    RemoteApplication,
+    /// No other values are documented
+    Other(BG_ERROR_CONTEXT),
+}
+
+impl From<BG_ERROR_CONTEXT> for BitsErrorContext {
+    fn from(ec: BG_ERROR_CONTEXT) -> BitsErrorContext {
+        use self::BitsErrorContext::*;
+        use winapi::um::bits;
+        match ec {
+            bits::BG_ERROR_CONTEXT_NONE => None,
+            bits::BG_ERROR_CONTEXT_UNKNOWN => Unknown,
+            bits::BG_ERROR_CONTEXT_GENERAL_QUEUE_MANAGER => GeneralQueueManager,
+            bits::BG_ERROR_CONTEXT_QUEUE_MANAGER_NOTIFICATION => QueueManagerNotification,
+            bits::BG_ERROR_CONTEXT_LOCAL_FILE => LocalFile,
+            bits::BG_ERROR_CONTEXT_REMOTE_FILE => RemoteFile,
+            bits::BG_ERROR_CONTEXT_GENERAL_TRANSPORT => GeneralTransport,
+            bits::BG_ERROR_CONTEXT_REMOTE_APPLICATION => RemoteApplication,
+            ec => Other(ec),
+        }
+    }
+}
+
+#[derive(Copy, Clone, Debug, Eq, PartialEq)]
+#[cfg_attr(feature = "status_serde", derive(Serialize, Deserialize))]
+pub enum BitsJobState {
+    Queued,
+    Connecting,
+    Transferring,
+    Suspended,
+    Error,
+    TransientError,
+    Transferred,
+    Acknowledged,
+    Cancelled,
+    /// No other values are documented
+    Other(BG_JOB_STATE),
+}
+
+impl From<BG_JOB_STATE> for BitsJobState {
+    fn from(s: BG_JOB_STATE) -> BitsJobState {
+        use self::BitsJobState::*;
+        use winapi::um::bits;
+        match s {
+            bits::BG_JOB_STATE_QUEUED => Queued,
+            bits::BG_JOB_STATE_CONNECTING => Connecting,
+            bits::BG_JOB_STATE_TRANSFERRING => Transferring,
+            bits::BG_JOB_STATE_SUSPENDED => Suspended,
+            bits::BG_JOB_STATE_ERROR => Error,
+            bits::BG_JOB_STATE_TRANSIENT_ERROR => TransientError,
+            bits::BG_JOB_STATE_TRANSFERRED => Transferred,
+            bits::BG_JOB_STATE_ACKNOWLEDGED => Acknowledged,
+            bits::BG_JOB_STATE_CANCELLED => Cancelled,
+            s => Other(s),
+        }
+    }
+}
+
+#[derive(Copy, Clone, Debug)]
+#[cfg_attr(feature = "status_serde", derive(Serialize, Deserialize))]
+pub struct BitsJobProgress {
+    pub total_bytes: Option<u64>,
+    pub transferred_bytes: u64,
+    pub total_files: u32,
+    pub transferred_files: u32,
+}
+
+#[derive(Copy, Clone, Debug)]
+#[cfg_attr(feature = "status_serde", derive(Serialize, Deserialize))]
+pub struct BitsJobTimes {
+    pub creation: FileTime,
+    pub modification: FileTime,
+    pub transfer_completion: Option<FileTime>,
+}
diff --git a/toolkit/components/bitsdownload/bits_client/bits/src/wide.rs b/toolkit/components/bitsdownload/bits_client/bits/src/wide.rs
new file mode 100644
index 0000000000..c108f8d629
--- /dev/null
+++ b/toolkit/components/bitsdownload/bits_client/bits/src/wide.rs
@@ -0,0 +1,38 @@
+// Licensed under the Apache License, Version 2.0
+// <LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
+// All files in the project carrying such notice may not be copied, modified, or distributed
+// except according to those terms.
+
+// Minimal null-terminated wide string support from wio.
+
+use std::ffi::{OsStr, OsString};
+use std::os::windows::ffi::{OsStrExt, OsStringExt};
+use std::slice;
+
+pub trait ToWideNull {
+    fn to_wide_null(&self) -> Vec<u16>;
+}
+
+impl<T: AsRef<OsStr>> ToWideNull for T {
+    fn to_wide_null(&self) -> Vec<u16> {
+        self.as_ref().encode_wide().chain(Some(0)).collect()
+    }
+}
+
+pub trait FromWidePtrNull {
+    unsafe fn from_wide_ptr_null(wide: *const u16) -> Self;
+}
+
+impl FromWidePtrNull for OsString {
+    unsafe fn from_wide_ptr_null(wide: *const u16) -> Self {
+        assert!(!wide.is_null());
+
+        for i in 0.. {
+            if *wide.offset(i) == 0 {
+                return Self::from_wide(&slice::from_raw_parts(wide, i as usize));
+            }
+        }
+        unreachable!()
+    }
+}
diff --git a/toolkit/components/bitsdownload/bits_client/examples/test_client.rs b/toolkit/components/bitsdownload/bits_client/examples/test_client.rs
new file mode 100644
index 0000000000..25d7a0d82e
--- /dev/null
+++ b/toolkit/components/bitsdownload/bits_client/examples/test_client.rs
@@ -0,0 +1,285 @@
+/* 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/. */
+
+extern crate bits_client;
+extern crate comedy;
+//extern crate ctrlc;
+extern crate guid_win;
+extern crate thiserror;
+
+use std::env;
+use std::ffi::{OsStr, OsString};
+use std::process;
+use std::str::FromStr;
+use std::sync::{Arc, Mutex};
+
+use thiserror::Error;
+
+use bits_client::bits_protocol::HResultMessage;
+use bits_client::{BitsClient, BitsJobState, BitsMonitorClient, BitsProxyUsage, Guid, PipeError};
+
+#[derive(Debug, Error)]
+enum MyError {
+    #[error("{0}")]
+    Msg(String),
+    #[error("HResult")]
+    HResult(#[from] comedy::HResult),
+    #[error("Win32Error")]
+    Win32Error(#[from] comedy::Win32Error),
+    #[error("PipeError")]
+    PipeError(#[from] PipeError),
+    #[error("HResultMessage")]
+    HResultMessage(#[from] HResultMessage),
+}
+
+macro_rules! bail {
+    ($e:expr) => {
+        return Err($crate::MyError::Msg($e.to_string()))
+    };
+    ($fmt:expr, $($arg:tt)*) => {
+        return Err($crate::MyError::Msg(format!($fmt, $($arg)*)))
+    };
+}
+
+type Result = std::result::Result<(), MyError>;
+
+pub fn main() {
+    if let Err(err) = entry() {
+        eprintln!("{}", err);
+        let mut err: &dyn std::error::Error = &err;
+        while let Some(source) = err.source() {
+            eprintln!("caused by {}", source);
+            err = source;
+        }
+
+        process::exit(1);
+    } else {
+        println!("OK");
+    }
+}
+
+const EXE_NAME: &'static str = "test_client";
+
+fn usage() -> String {
+    format!(
+        concat!(
+            "Usage {0} <command> ",
+            "[local-service] ",
+            "[args...]\n",
+            "Commands:\n",
+            "  bits-start <URL> <local file>\n",
+            "  bits-monitor <GUID>\n",
+            "  bits-bg <GUID>\n",
+            "  bits-fg <GUID>\n",
+            "  bits-suspend <GUID>\n",
+            "  bits-resume <GUID>\n",
+            "  bits-complete <GUID>\n",
+            "  bits-cancel <GUID> ...\n"
+        ),
+        EXE_NAME
+    )
+}
+
+fn entry() -> Result {
+    let args: Vec<_> = env::args_os().collect();
+
+    let mut client = BitsClient::new(
+        OsString::from("bits_client test"),
+        OsString::from("C:\\ProgramData"),
+    )?;
+
+    if args.len() < 2 {
+        eprintln!("{}", usage());
+        bail!("not enough arguments");
+    }
+
+    let cmd = &*args[1].to_string_lossy();
+    let cmd_args = &args[2..];
+
+    match cmd {
+        // command line client for testing
+        "bits-start" if cmd_args.len() == 2 => bits_start(
+            Arc::new(Mutex::new(client)),
+            cmd_args[0].clone(),
+            cmd_args[1].clone(),
+            BitsProxyUsage::Preconfig,
+        ),
+        "bits-monitor" if cmd_args.len() == 1 => {
+            bits_monitor(Arc::new(Mutex::new(client)), &cmd_args[0])
+        }
+        // TODO: some way of testing set update interval
+        "bits-bg" if cmd_args.len() == 1 => bits_bg(&mut client, &cmd_args[0]),
+        "bits-fg" if cmd_args.len() == 1 => bits_fg(&mut client, &cmd_args[0]),
+        "bits-suspend" if cmd_args.len() == 1 => bits_suspend(&mut client, &cmd_args[0]),
+        "bits-resume" if cmd_args.len() == 1 => bits_resume(&mut client, &cmd_args[0]),
+        "bits-complete" if cmd_args.len() == 1 => bits_complete(&mut client, &cmd_args[0]),
+        "bits-cancel" if cmd_args.len() >= 1 => {
+            for guid in cmd_args {
+                bits_cancel(&mut client, guid)?;
+            }
+            Ok(())
+        }
+        _ => {
+            eprintln!("{}", usage());
+            bail!("usage error");
+        }
+    }
+}
+
+fn bits_start(
+    client: Arc<Mutex<BitsClient>>,
+    url: OsString,
+    save_path: OsString,
+    proxy_usage: BitsProxyUsage,
+) -> Result {
+    //let interval = 10 * 60 * 1000;
+    let no_progress_timeout_secs = 60;
+    let interval = 1000;
+
+    let result = client.lock().unwrap().start_job(
+        url,
+        save_path,
+        proxy_usage,
+        no_progress_timeout_secs,
+        interval,
+    )?;
+
+    match result {
+        Ok((r, monitor_client)) => {
+            println!("start success, guid = {}", r.guid);
+            client
+                .lock()
+                .unwrap()
+                .set_update_interval(r.guid.clone(), interval)?
+                .unwrap();
+            monitor_loop(client, monitor_client, r.guid.clone(), interval)?;
+            Ok(())
+        }
+        Err(e) => {
+            let _ = e.clone();
+            bail!("error from server {}", e)
+        }
+    }
+}
+
+fn bits_monitor(client: Arc<Mutex<BitsClient>>, guid: &OsStr) -> Result {
+    let guid = Guid::from_str(&guid.to_string_lossy())?;
+    let result = client.lock().unwrap().monitor_job(guid.clone(), 1000)?;
+    match result {
+        Ok(monitor_client) => {
+            println!("monitor success");
+            monitor_loop(client, monitor_client, guid, 1000)?;
+            Ok(())
+        }
+        Err(e) => bail!("error from server {}", e),
+    }
+}
+
+fn _check_client_send()
+where
+    BitsClient: Send,
+{
+}
+fn _check_monitor_send()
+where
+    BitsMonitorClient: Send,
+{
+}
+
+fn monitor_loop(
+    _client: Arc<Mutex<BitsClient>>,
+    mut monitor_client: BitsMonitorClient,
+    _guid: Guid,
+    wait_millis: u32,
+) -> Result {
+    /*
+    // Commented out to avoid vendoring ctrlc.
+    // This could also possibly be done with `exclude` in the mozilla-central `Cargo.toml`.
+    let client_for_handler = _client.clone();
+    ctrlc::set_handler(move || {
+        eprintln!("Ctrl-C!");
+        let _ = client_for_handler.lock().unwrap().stop_update(_guid.clone());
+    })
+    .expect("Error setting Ctrl-C handler");
+    */
+
+    loop {
+        let status = monitor_client.get_status(wait_millis * 10)??;
+
+        println!("{:?} {:?}", BitsJobState::from(status.state), status);
+
+        //println!("{}", job.get_first_file()?.get_remote_name()?.into_string().unwrap());
+        let transfer_completion_time = if let Some(ft) = status.times.transfer_completion {
+            format!("Some({})", ft.to_system_time_utc()?)
+        } else {
+            String::from("None")
+        };
+        println!(
+            "creation: {}, modification: {}, transfer completion: {}",
+            status.times.creation.to_system_time_utc()?,
+            status.times.modification.to_system_time_utc()?,
+            transfer_completion_time
+        );
+
+        match BitsJobState::from(status.state) {
+            BitsJobState::Connecting
+            | BitsJobState::Transferring
+            | BitsJobState::TransientError => {}
+            _ => break,
+        }
+    }
+    println!("monitor loop ending");
+    println!("sleeping...");
+    std::thread::sleep(std::time::Duration::from_secs(1));
+
+    Ok(())
+}
+
+fn bits_bg(client: &mut BitsClient, guid: &OsStr) -> Result {
+    bits_set_priority(client, guid, false)
+}
+
+fn bits_fg(client: &mut BitsClient, guid: &OsStr) -> Result {
+    bits_set_priority(client, guid, true)
+}
+
+fn bits_set_priority(client: &mut BitsClient, guid: &OsStr, foreground: bool) -> Result {
+    let guid = Guid::from_str(&guid.to_string_lossy())?;
+    match client.set_job_priority(guid, foreground)? {
+        Ok(()) => Ok(()),
+        Err(e) => bail!("error from server {}", e),
+    }
+}
+
+fn bits_suspend(client: &mut BitsClient, guid: &OsStr) -> Result {
+    let guid = Guid::from_str(&guid.to_string_lossy())?;
+    match client.suspend_job(guid)? {
+        Ok(()) => Ok(()),
+        Err(e) => bail!("error from server {}", e),
+    }
+}
+
+fn bits_resume(client: &mut BitsClient, guid: &OsStr) -> Result {
+    let guid = Guid::from_str(&guid.to_string_lossy())?;
+    match client.resume_job(guid)? {
+        Ok(()) => Ok(()),
+        Err(e) => bail!("error from server {}", e),
+    }
+}
+
+fn bits_complete(client: &mut BitsClient, guid: &OsStr) -> Result {
+    let guid = Guid::from_str(&guid.to_string_lossy())?;
+    match client.complete_job(guid)? {
+        Ok(()) => Ok(()),
+        Err(e) => bail!("error from server {}", e),
+    }
+}
+
+fn bits_cancel(client: &mut BitsClient, guid: &OsStr) -> Result {
+    let guid = Guid::from_str(&guid.to_string_lossy())?;
+    match client.cancel_job(guid)? {
+        Ok(()) => Ok(()),
+        Err(e) => bail!("error from server {}", e),
+    }
+}
diff --git a/toolkit/components/bitsdownload/bits_client/src/bits_protocol.rs b/toolkit/components/bitsdownload/bits_client/src/bits_protocol.rs
new file mode 100644
index 0000000000..6f19f5ef23
--- /dev/null
+++ b/toolkit/components/bitsdownload/bits_client/src/bits_protocol.rs
@@ -0,0 +1,380 @@
+/* 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/. */
+
+//! Command, response, and status types.
+
+use std::error::Error as StdError;
+use std::ffi::OsString;
+use std::fmt;
+use std::result;
+
+use guid_win::Guid;
+use thiserror::Error;
+
+use super::{BitsErrorContext, BitsJobProgress, BitsJobState, BitsJobTimes, BitsProxyUsage};
+
+type HRESULT = i32;
+
+/// An HRESULT with a descriptive message
+#[derive(Clone, Debug)]
+pub struct HResultMessage {
+    pub hr: HRESULT,
+    pub message: String,
+}
+
+impl fmt::Display for HResultMessage {
+    fn fmt(&self, f: &mut fmt::Formatter) -> result::Result<(), fmt::Error> {
+        self.message.fmt(f)
+    }
+}
+
+impl StdError for HResultMessage {}
+
+/// Commands which can be sent to the server.
+///
+/// This is currently unused as the out-of-process Local Service server is not finished.
+#[doc(hidden)]
+#[derive(Clone, Debug)]
+pub enum Command {
+    StartJob(StartJobCommand),
+    MonitorJob(MonitorJobCommand),
+    SuspendJob(SuspendJobCommand),
+    ResumeJob(ResumeJobCommand),
+    SetJobPriority(SetJobPriorityCommand),
+    SetNoProgressTimeout(SetNoProgressTimeoutCommand),
+    SetUpdateInterval(SetUpdateIntervalCommand),
+    CompleteJob(CompleteJobCommand),
+    CancelJob(CancelJobCommand),
+}
+
+/// Combine a [`Command`](enum.Command.html) with its success and failure result types.
+#[doc(hidden)]
+pub trait CommandType {
+    type Success;
+    type Failure: StdError;
+    fn wrap(command: Self) -> Command;
+}
+
+// Start Job
+#[doc(hidden)]
+#[derive(Clone, Debug)]
+pub struct StartJobCommand {
+    pub url: OsString,
+    pub save_path: OsString,
+    pub proxy_usage: BitsProxyUsage,
+    pub no_progress_timeout_secs: u32,
+    pub monitor: Option<MonitorConfig>,
+}
+
+impl CommandType for StartJobCommand {
+    type Success = StartJobSuccess;
+    type Failure = StartJobFailure;
+    fn wrap(cmd: Self) -> Command {
+        Command::StartJob(cmd)
+    }
+}
+
+#[doc(hidden)]
+#[derive(Clone, Debug)]
+pub struct MonitorConfig {
+    pub pipe_name: OsString,
+    pub interval_millis: u32,
+}
+
+#[derive(Clone, Debug)]
+pub struct StartJobSuccess {
+    pub guid: Guid,
+}
+
+#[derive(Clone, Debug, Error)]
+pub enum StartJobFailure {
+    #[error("Argument validation failed: {0}")]
+    ArgumentValidation(String),
+    #[error("Create job: {0}")]
+    Create(HResultMessage),
+    #[error("Add file to job: {0}")]
+    AddFile(HResultMessage),
+    #[error("Apply settings to job: {0}")]
+    ApplySettings(HResultMessage),
+    #[error("Resume job: {0}")]
+    Resume(HResultMessage),
+    #[error("Connect to BackgroundCopyManager: {0}")]
+    ConnectBcm(HResultMessage),
+    #[error("BITS error: {0}")]
+    OtherBITS(HResultMessage),
+    #[error("Other failure: {0}")]
+    Other(String),
+}
+
+// Monitor Job
+#[doc(hidden)]
+#[derive(Clone, Debug)]
+pub struct MonitorJobCommand {
+    pub guid: Guid,
+    pub monitor: MonitorConfig,
+}
+
+impl CommandType for MonitorJobCommand {
+    type Success = ();
+    type Failure = MonitorJobFailure;
+    fn wrap(cmd: Self) -> Command {
+        Command::MonitorJob(cmd)
+    }
+}
+
+#[derive(Clone, Debug, Error)]
+pub enum MonitorJobFailure {
+    #[error("Argument validation failed: {0}")]
+    ArgumentValidation(String),
+    #[error("Job not found")]
+    NotFound,
+    #[error("Get job: {0}")]
+    GetJob(HResultMessage),
+    #[error("Connect to BackgroundCopyManager: {0}")]
+    ConnectBcm(HResultMessage),
+    #[error("BITS error: {0}")]
+    OtherBITS(HResultMessage),
+    #[error("Other failure: {0}")]
+    Other(String),
+}
+
+// Suspend Job
+#[doc(hidden)]
+#[derive(Clone, Debug)]
+pub struct SuspendJobCommand {
+    pub guid: Guid,
+}
+
+impl CommandType for SuspendJobCommand {
+    type Success = ();
+    type Failure = SuspendJobFailure;
+    fn wrap(cmd: Self) -> Command {
+        Command::SuspendJob(cmd)
+    }
+}
+
+#[derive(Clone, Debug, Error)]
+pub enum SuspendJobFailure {
+    #[error("Job not found")]
+    NotFound,
+    #[error("Get job: {0}")]
+    GetJob(HResultMessage),
+    #[error("Suspend job: {0}")]
+    SuspendJob(HResultMessage),
+    #[error("Connect to BackgroundCopyManager: {0}")]
+    ConnectBcm(HResultMessage),
+    #[error("BITS error: {0}")]
+    OtherBITS(HResultMessage),
+    #[error("Other failure: {0}")]
+    Other(String),
+}
+
+// Resume Job
+#[doc(hidden)]
+#[derive(Clone, Debug)]
+pub struct ResumeJobCommand {
+    pub guid: Guid,
+}
+
+impl CommandType for ResumeJobCommand {
+    type Success = ();
+    type Failure = ResumeJobFailure;
+    fn wrap(cmd: Self) -> Command {
+        Command::ResumeJob(cmd)
+    }
+}
+
+#[derive(Clone, Debug, Error)]
+pub enum ResumeJobFailure {
+    #[error("Job not found")]
+    NotFound,
+    #[error("Get job: {0}")]
+    GetJob(HResultMessage),
+    #[error("Resume job: {0}")]
+    ResumeJob(HResultMessage),
+    #[error("Connect to BackgroundCopyManager: {0}")]
+    ConnectBcm(HResultMessage),
+    #[error("BITS error: {0}")]
+    OtherBITS(HResultMessage),
+    #[error("Other failure: {0}")]
+    Other(String),
+}
+
+// Set Job Priority
+#[doc(hidden)]
+#[derive(Clone, Debug)]
+pub struct SetJobPriorityCommand {
+    pub guid: Guid,
+    pub foreground: bool,
+}
+
+impl CommandType for SetJobPriorityCommand {
+    type Success = ();
+    type Failure = SetJobPriorityFailure;
+    fn wrap(cmd: Self) -> Command {
+        Command::SetJobPriority(cmd)
+    }
+}
+
+#[derive(Clone, Debug, Error)]
+pub enum SetJobPriorityFailure {
+    #[error("Job not found")]
+    NotFound,
+    #[error("Get job: {0}")]
+    GetJob(HResultMessage),
+    #[error("Apply settings to job: {0}")]
+    ApplySettings(HResultMessage),
+    #[error("Connect to BackgroundCopyManager: {0}")]
+    ConnectBcm(HResultMessage),
+    #[error("BITS error: {0}")]
+    OtherBITS(HResultMessage),
+    #[error("Other failure: {0}")]
+    Other(String),
+}
+
+// Set No Progress Timeout
+#[doc(hidden)]
+#[derive(Clone, Debug)]
+pub struct SetNoProgressTimeoutCommand {
+    pub guid: Guid,
+    pub timeout_secs: u32,
+}
+
+impl CommandType for SetNoProgressTimeoutCommand {
+    type Success = ();
+    type Failure = SetNoProgressTimeoutFailure;
+    fn wrap(cmd: Self) -> Command {
+        Command::SetNoProgressTimeout(cmd)
+    }
+}
+
+#[derive(Clone, Debug, Error)]
+pub enum SetNoProgressTimeoutFailure {
+    #[error("Job not found")]
+    NotFound,
+    #[error("Get job: {0}")]
+    GetJob(HResultMessage),
+    #[error("Apply settings to job: {0}")]
+    ApplySettings(HResultMessage),
+    #[error("Connect to BackgroundCopyManager: {0}")]
+    ConnectBcm(HResultMessage),
+    #[error("BITS error: {0}")]
+    OtherBITS(HResultMessage),
+    #[error("Other failure: {0}")]
+    Other(String),
+}
+
+// Set Update Interval
+#[doc(hidden)]
+#[derive(Clone, Debug)]
+pub struct SetUpdateIntervalCommand {
+    pub guid: Guid,
+    pub interval_millis: u32,
+}
+
+impl CommandType for SetUpdateIntervalCommand {
+    type Success = ();
+    type Failure = SetUpdateIntervalFailure;
+    fn wrap(cmd: Self) -> Command {
+        Command::SetUpdateInterval(cmd)
+    }
+}
+
+#[derive(Clone, Debug, Error)]
+pub enum SetUpdateIntervalFailure {
+    #[error("Argument validation: {0}")]
+    ArgumentValidation(String),
+    #[error("Monitor not found")]
+    NotFound,
+    #[error("Other failure: {0}")]
+    Other(String),
+}
+
+// Complete Job
+#[doc(hidden)]
+#[derive(Clone, Debug)]
+pub struct CompleteJobCommand {
+    pub guid: Guid,
+}
+
+impl CommandType for CompleteJobCommand {
+    type Success = ();
+    type Failure = CompleteJobFailure;
+    fn wrap(cmd: Self) -> Command {
+        Command::CompleteJob(cmd)
+    }
+}
+
+#[derive(Clone, Debug, Error)]
+pub enum CompleteJobFailure {
+    #[error("Job not found")]
+    NotFound,
+    #[error("Get job: {0}")]
+    GetJob(HResultMessage),
+    #[error("Complete job: {0}")]
+    CompleteJob(HResultMessage),
+    #[error("Job only partially completed")]
+    PartialComplete,
+    #[error("Connect to BackgroundCopyManager: {0}")]
+    ConnectBcm(HResultMessage),
+    #[error("BITS error: {0}")]
+    OtherBITS(HResultMessage),
+    #[error("Other failure: {0}")]
+    Other(String),
+}
+
+// Cancel Job
+#[doc(hidden)]
+#[derive(Clone, Debug)]
+pub struct CancelJobCommand {
+    pub guid: Guid,
+}
+
+impl CommandType for CancelJobCommand {
+    type Success = ();
+    type Failure = CancelJobFailure;
+    fn wrap(cmd: Self) -> Command {
+        Command::CancelJob(cmd)
+    }
+}
+
+#[derive(Clone, Debug, Error)]
+pub enum CancelJobFailure {
+    #[error("Job not found")]
+    NotFound,
+    #[error("Get job: {0}")]
+    GetJob(HResultMessage),
+    #[error("Cancel job: {0}")]
+    CancelJob(HResultMessage),
+    #[error("Connect to BackgroundCopyManager: {0}")]
+    ConnectBcm(HResultMessage),
+    #[error("BITS error: {0}")]
+    OtherBITS(HResultMessage),
+    #[error("Other failure: {0}")]
+    Other(String),
+}
+
+/// Job status report
+///
+/// This includes a URL which updates with redirect but is otherwise the same as
+/// `bits::status::BitsJobStatus`.
+#[derive(Clone, Debug)]
+pub struct JobStatus {
+    pub state: BitsJobState,
+    pub progress: BitsJobProgress,
+    pub error_count: u32,
+    pub error: Option<JobError>,
+    pub times: BitsJobTimes,
+    /// None means same as last time
+    pub url: Option<OsString>,
+}
+
+/// Job error report
+#[derive(Clone, Debug, Error)]
+#[error("Job error in context {context_str}: {error}")]
+pub struct JobError {
+    pub context: BitsErrorContext,
+    pub context_str: String,
+    pub error: HResultMessage,
+}
diff --git a/toolkit/components/bitsdownload/bits_client/src/in_process/mod.rs b/toolkit/components/bitsdownload/bits_client/src/in_process/mod.rs
new file mode 100644
index 0000000000..c7f6869167
--- /dev/null
+++ b/toolkit/components/bitsdownload/bits_client/src/in_process/mod.rs
@@ -0,0 +1,504 @@
+/* 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/. */
+
+use std::cmp;
+use std::collections::{hash_map, HashMap};
+use std::ffi;
+use std::path;
+use std::sync::{Arc, Condvar, Mutex, Weak};
+use std::time::{Duration, Instant};
+
+use bits::{
+    BackgroundCopyManager, BitsJob, BitsJobPriority, BitsProxyUsage, BG_S_PARTIAL_COMPLETE, E_FAIL,
+};
+use guid_win::Guid;
+
+use bits_protocol::*;
+
+use super::Error;
+
+// This is a macro in order to use the NotFound and GetJob variants from whatever enum is in scope.
+macro_rules! get_job {
+    ($bcm:ident, $guid:expr, $name:expr) => {{
+        $bcm = BackgroundCopyManager::connect().map_err(|e| {
+            ConnectBcm(HResultMessage {
+                hr: e.code(),
+                message: e.to_string(),
+            })
+        })?;
+        $bcm.find_job_by_guid_and_name($guid, $name)
+            .map_err(|e| GetJob($crate::in_process::format_error(&$bcm, e)))?
+            .ok_or(NotFound)?
+    }};
+}
+
+fn format_error(bcm: &BackgroundCopyManager, error: comedy::HResult) -> HResultMessage {
+    let bits_description = bcm.get_error_description(error.code()).ok();
+
+    HResultMessage {
+        hr: error.code(),
+        message: if let Some(desc) = bits_description {
+            format!("{}: {}", error, desc)
+        } else {
+            format!("{}", error)
+        },
+    }
+}
+
+// The in-process client uses direct BITS calls via the `bits` crate.
+// See the corresponding functions in BitsClient.
+pub struct InProcessClient {
+    job_name: ffi::OsString,
+    save_path_prefix: path::PathBuf,
+    monitors: HashMap<Guid, InProcessMonitorControl>,
+}
+
+impl InProcessClient {
+    pub fn new(
+        job_name: ffi::OsString,
+        save_path_prefix: ffi::OsString,
+    ) -> Result<InProcessClient, Error> {
+        Ok(InProcessClient {
+            job_name,
+            save_path_prefix: path::PathBuf::from(save_path_prefix),
+            monitors: HashMap::new(),
+        })
+    }
+
+    pub fn start_job(
+        &mut self,
+        url: ffi::OsString,
+        save_path: ffi::OsString,
+        proxy_usage: BitsProxyUsage,
+        no_progress_timeout_secs: u32,
+        monitor_interval_millis: u32,
+    ) -> Result<(StartJobSuccess, InProcessMonitor), StartJobFailure> {
+        use StartJobFailure::*;
+
+        let full_path = self.save_path_prefix.join(save_path);
+
+        // Verify that `full_path` is under the directory called `save_path_prefix`.
+        {
+            let canonical_prefix = self.save_path_prefix.canonicalize().map_err(|e| {
+                ArgumentValidation(format!("save_path_prefix.canonicalize(): {}", e))
+            })?;
+            // Full path minus file name, canonicalize() fails with nonexistent files, but the
+            // parent directory ought to exist.
+            let canonical_full_path = full_path
+                .parent()
+                .ok_or_else(|| ArgumentValidation("full_path.parent(): None".into()))?
+                .canonicalize()
+                .map_err(|e| {
+                    ArgumentValidation(format!("full_path.parent().canonicalize(): {}", e))
+                })?;
+
+            if !canonical_full_path.starts_with(&canonical_prefix) {
+                return Err(ArgumentValidation(format!(
+                    "{:?} is not within {:?}",
+                    canonical_full_path, canonical_prefix
+                )));
+            }
+        }
+
+        // TODO: Should the job be explicitly cleaned up if this fn can't return success?
+        // If the job is dropped before `AddFile` succeeds, I think it automatically gets
+        // deleted from the queue. There is only one fallible call after that (`Resume`).
+
+        let bcm = BackgroundCopyManager::connect().map_err(|e| {
+            ConnectBcm(HResultMessage {
+                hr: e.code(),
+                message: e.to_string(),
+            })
+        })?;
+        let mut job = bcm
+            .create_job(&self.job_name)
+            .map_err(|e| Create(format_error(&bcm, e)))?;
+
+        let guid = job.guid().map_err(|e| OtherBITS(format_error(&bcm, e)))?;
+
+        (|| {
+            job.set_proxy_usage(proxy_usage)?;
+            job.set_minimum_retry_delay(60)?;
+            job.set_no_progress_timeout(no_progress_timeout_secs)?;
+            job.set_redirect_report()?;
+
+            job.set_priority(BitsJobPriority::Foreground)?;
+
+            Ok(())
+        })()
+        .map_err(|e| ApplySettings(format_error(&bcm, e)))?;
+
+        let (client, control) = InProcessMonitor::new(&mut job, monitor_interval_millis)
+            .map_err(|e| OtherBITS(format_error(&bcm, e)))?;
+
+        job.add_file(&url, &full_path.into_os_string())
+            .map_err(|e| AddFile(format_error(&bcm, e)))?;
+
+        job.resume().map_err(|e| Resume(format_error(&bcm, e)))?;
+
+        self.monitors.insert(guid.clone(), control);
+
+        Ok((StartJobSuccess { guid }, client))
+    }
+
+    pub fn monitor_job(
+        &mut self,
+        guid: Guid,
+        interval_millis: u32,
+    ) -> Result<InProcessMonitor, MonitorJobFailure> {
+        use MonitorJobFailure::*;
+
+        // Stop any preexisting monitor for the same guid.
+        let _ = self.stop_update(guid.clone());
+
+        let bcm;
+        let (client, control) =
+            InProcessMonitor::new(&mut get_job!(bcm, &guid, &self.job_name), interval_millis)
+                .map_err(|e| OtherBITS(format_error(&bcm, e)))?;
+
+        self.monitors.insert(guid, control);
+
+        Ok(client)
+    }
+
+    pub fn suspend_job(&mut self, guid: Guid) -> Result<(), SuspendJobFailure> {
+        use SuspendJobFailure::*;
+
+        let bcm;
+        get_job!(bcm, &guid, &self.job_name)
+            .suspend()
+            .map_err(|e| SuspendJob(format_error(&bcm, e)))?;
+
+        Ok(())
+    }
+
+    pub fn resume_job(&mut self, guid: Guid) -> Result<(), ResumeJobFailure> {
+        use ResumeJobFailure::*;
+
+        let bcm;
+        get_job!(bcm, &guid, &self.job_name)
+            .resume()
+            .map_err(|e| ResumeJob(format_error(&bcm, e)))?;
+
+        Ok(())
+    }
+
+    pub fn set_job_priority(
+        &mut self,
+        guid: Guid,
+        foreground: bool,
+    ) -> Result<(), SetJobPriorityFailure> {
+        use SetJobPriorityFailure::*;
+
+        let priority = if foreground {
+            BitsJobPriority::Foreground
+        } else {
+            BitsJobPriority::Normal
+        };
+
+        let bcm;
+        get_job!(bcm, &guid, &self.job_name)
+            .set_priority(priority)
+            .map_err(|e| ApplySettings(format_error(&bcm, e)))?;
+
+        Ok(())
+    }
+
+    pub fn set_no_progress_timeout(
+        &mut self,
+        guid: Guid,
+        timeout_secs: u32,
+    ) -> Result<(), SetNoProgressTimeoutFailure> {
+        use SetNoProgressTimeoutFailure::*;
+
+        let bcm;
+        get_job!(bcm, &guid, &self.job_name)
+            .set_no_progress_timeout(timeout_secs)
+            .map_err(|e| ApplySettings(format_error(&bcm, e)))?;
+
+        Ok(())
+    }
+
+    fn get_monitor_control_sender(&mut self, guid: Guid) -> Option<Arc<ControlPair>> {
+        if let hash_map::Entry::Occupied(occ) = self.monitors.entry(guid) {
+            if let Some(sender) = occ.get().0.upgrade() {
+                Some(sender)
+            } else {
+                // Remove dangling Weak
+                occ.remove_entry();
+                None
+            }
+        } else {
+            None
+        }
+    }
+
+    pub fn set_update_interval(
+        &mut self,
+        guid: Guid,
+        interval_millis: u32,
+    ) -> Result<(), SetUpdateIntervalFailure> {
+        use SetUpdateIntervalFailure::*;
+
+        if let Some(sender) = self.get_monitor_control_sender(guid) {
+            let mut s = sender.1.lock().unwrap();
+            s.interval_millis = interval_millis;
+            sender.0.notify_all();
+            Ok(())
+        } else {
+            Err(NotFound)
+        }
+    }
+
+    pub fn stop_update(&mut self, guid: Guid) -> Result<(), SetUpdateIntervalFailure> {
+        use SetUpdateIntervalFailure::*;
+
+        if let Some(sender) = self.get_monitor_control_sender(guid) {
+            sender.1.lock().unwrap().shutdown = true;
+            sender.0.notify_all();
+            Ok(())
+        } else {
+            Err(NotFound)
+        }
+    }
+
+    pub fn complete_job(&mut self, guid: Guid) -> Result<(), CompleteJobFailure> {
+        use CompleteJobFailure::*;
+
+        let bcm;
+        get_job!(bcm, &guid, &self.job_name)
+            .complete()
+            .map_err(|e| CompleteJob(format_error(&bcm, e)))
+            .and_then(|hr| {
+                if hr == BG_S_PARTIAL_COMPLETE as i32 {
+                    Err(PartialComplete)
+                } else {
+                    Ok(())
+                }
+            })?;
+
+        let _ = self.stop_update(guid);
+
+        Ok(())
+    }
+
+    pub fn cancel_job(&mut self, guid: Guid) -> Result<(), CancelJobFailure> {
+        use CancelJobFailure::*;
+
+        let bcm;
+        get_job!(bcm, &guid, &self.job_name)
+            .cancel()
+            .map_err(|e| CancelJob(format_error(&bcm, e)))?;
+
+        let _ = self.stop_update(guid);
+
+        Ok(())
+    }
+}
+
+// InProcessMonitor can be used on any thread, and `ControlPair` can be synchronously modified to
+// control a blocked `get_status` call from another thread.
+pub struct InProcessMonitor {
+    vars: Arc<ControlPair>,
+    guid: Guid,
+    last_status_time: Option<Instant>,
+    last_url: Option<ffi::OsString>,
+}
+
+// The `Condvar` is notified when `InProcessMonitorVars` changes.
+type ControlPair = (Condvar, Mutex<InProcessMonitorVars>);
+struct InProcessMonitorControl(Weak<ControlPair>);
+
+// RefUnwindSafe is not impl'd for Condvar but likely should be,
+// see https://github.com/rust-lang/rust/issues/54768
+impl std::panic::RefUnwindSafe for InProcessMonitorControl {}
+
+struct InProcessMonitorVars {
+    interval_millis: u32,
+    notified: bool,
+    shutdown: bool,
+}
+
+impl InProcessMonitor {
+    fn new(
+        job: &mut BitsJob,
+        interval_millis: u32,
+    ) -> Result<(InProcessMonitor, InProcessMonitorControl), comedy::HResult> {
+        let guid = job.guid()?;
+
+        let vars = Arc::new((
+            Condvar::new(),
+            Mutex::new(InProcessMonitorVars {
+                interval_millis,
+                notified: false,
+                shutdown: false,
+            }),
+        ));
+
+        let transferred_control = InProcessMonitorControl(Arc::downgrade(&vars));
+        let transferred_cb = Box::new(move || {
+            if let Some(control) = transferred_control.0.upgrade() {
+                if let Ok(mut vars) = control.1.lock() {
+                    vars.notified = true;
+                    control.0.notify_all();
+                    return Ok(());
+                }
+            }
+            Err(E_FAIL)
+        });
+
+        let error_control = InProcessMonitorControl(Arc::downgrade(&vars));
+        let error_cb = Box::new(move || {
+            if let Some(control) = error_control.0.upgrade() {
+                if let Ok(mut vars) = control.1.lock() {
+                    vars.notified = true;
+                    control.0.notify_all();
+                    return Ok(());
+                }
+            }
+            Err(E_FAIL)
+        });
+
+        // Note: These callbacks are never explicitly cleared. They will be freed when the
+        // job is deleted from BITS, and they will be cleared if an attempt is made to call them
+        // when they are no longer valid (e.g. after the process exits). This is done mostly for
+        // simplicity and should be safe.
+
+        job.register_callbacks(Some(transferred_cb), Some(error_cb), None)?;
+
+        let control = InProcessMonitorControl(Arc::downgrade(&vars));
+
+        let monitor = InProcessMonitor {
+            guid,
+            vars,
+            last_status_time: None,
+            last_url: None,
+        };
+
+        Ok((monitor, control))
+    }
+
+    pub fn get_status(
+        &mut self,
+        timeout_millis: u32,
+    ) -> Result<Result<JobStatus, HResultMessage>, Error> {
+        let timeout = Duration::from_millis(u64::from(timeout_millis));
+
+        let started = Instant::now();
+        let timeout_end = started + timeout;
+
+        {
+            let mut s = self.vars.1.lock().unwrap();
+            loop {
+                let wait_start = Instant::now();
+
+                if s.shutdown {
+                    // Disconnected, immediately return error.
+                    // Note: Shutdown takes priority over simultaneous notification.
+                    return Err(Error::NotConnected);
+                }
+
+                if wait_start >= timeout_end {
+                    // Timed out, immediately return timeout error.
+                    // This should not normally happen with the in-process monitor, but the
+                    // monitor interval could be longer than the timeout.
+                    s.shutdown = true;
+                    return Err(Error::Timeout);
+                }
+
+                // Get the interval every pass through the loop, in case it has changed.
+                let interval = Duration::from_millis(u64::from(s.interval_millis));
+
+                let wait_until = self
+                    .last_status_time
+                    .map(|last_status_time| cmp::min(last_status_time + interval, timeout_end));
+
+                if s.notified {
+                    // Notified, exit loop to get status.
+                    s.notified = false;
+                    break;
+                }
+
+                if wait_until.is_none() {
+                    // First status report, no waiting, exit loop to get status.
+                    break;
+                }
+
+                let wait_until = wait_until.unwrap();
+
+                if wait_until <= wait_start {
+                    // No time left to wait. This can't be due to timeout because
+                    // `wait_until <= wait_start < timeout_end`.
+                    // Status report due, exit loop to get status.
+                    break;
+                }
+
+                // Wait.
+                // Do not attempt to recover from poisoned Mutex.
+                s = self
+                    .vars
+                    .0
+                    .wait_timeout(s, wait_until - wait_start)
+                    .unwrap()
+                    .0;
+
+                // Mutex re-acquired, loop.
+            }
+        }
+
+        // No error yet, start getting status now.
+        self.last_status_time = Some(Instant::now());
+
+        let bcm = match BackgroundCopyManager::connect() {
+            Ok(bcm) => bcm,
+            Err(e) => {
+                // On any error, disconnect.
+                self.vars.1.lock().unwrap().shutdown = true;
+
+                // Errors below can use the BCM to do `format_error()`, but this one just gets the
+                // basic `comedy::HResult` treatment.
+                return Ok(Err(HResultMessage {
+                    hr: e.code(),
+                    message: format!("{}", e),
+                }));
+            }
+        };
+
+        Ok((|| {
+            let mut job = bcm.get_job_by_guid(&self.guid)?;
+
+            let status = job.get_status()?;
+            let url = job.get_first_file()?.get_remote_name()?;
+
+            Ok(JobStatus {
+                state: status.state,
+                progress: status.progress,
+                error_count: status.error_count,
+                error: status.error.map(|e| JobError {
+                    context: e.context,
+                    context_str: e.context_str,
+                    error: HResultMessage {
+                        hr: e.error,
+                        message: e.error_str,
+                    },
+                }),
+                times: status.times,
+                url: if self.last_url.is_some() && *self.last_url.as_ref().unwrap() == url {
+                    None
+                } else {
+                    self.last_url = Some(url);
+                    self.last_url.clone()
+                },
+            })
+        })()
+        .map_err(|e| {
+            // On any error, disconnect.
+            self.vars.1.lock().unwrap().shutdown = true;
+            format_error(&bcm, e)
+        }))
+    }
+}
+
+#[cfg(test)]
+mod tests;
diff --git a/toolkit/components/bitsdownload/bits_client/src/in_process/tests.rs b/toolkit/components/bitsdownload/bits_client/src/in_process/tests.rs
new file mode 100644
index 0000000000..5545f6bd74
--- /dev/null
+++ b/toolkit/components/bitsdownload/bits_client/src/in_process/tests.rs
@@ -0,0 +1,628 @@
+/* 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/. */
+
+// These are full integration tests that use the BITS service.
+
+// TODO
+// It may make sense to restrict how many tests can run at once. BITS is only supposed to support
+// four simultaneous notifications per user, it is not impossible that this test suite could
+// exceed that.
+
+#![cfg(test)]
+extern crate bits;
+extern crate lazy_static;
+extern crate rand;
+extern crate regex;
+extern crate tempfile;
+
+use std::ffi::{OsStr, OsString};
+use std::fs::{self, File};
+use std::io::{Read, Write};
+use std::net::{SocketAddr, TcpListener, TcpStream};
+use std::panic;
+use std::sync::{Arc, Condvar, Mutex};
+use std::thread::{self, JoinHandle};
+use std::time::{Duration, Instant};
+
+use self::{
+    bits::BackgroundCopyManager,
+    lazy_static::lazy_static,
+    rand::{thread_rng, Rng},
+    regex::bytes::Regex,
+    tempfile::{Builder, TempDir},
+};
+use super::{
+    super::{BitsJobState, Error},
+    BitsProxyUsage, InProcessClient, StartJobSuccess,
+};
+
+static SERVER_ADDRESS: [u8; 4] = [127, 0, 0, 1];
+
+lazy_static! {
+    static ref TEST_MUTEX: Mutex<()> = Mutex::new(());
+}
+
+fn format_job_name(name: &str) -> OsString {
+    format!("InProcessClient Test {}", name).into()
+}
+
+fn format_dir_prefix(tmp_dir: &TempDir) -> OsString {
+    let mut dir = tmp_dir.path().to_path_buf().into_os_string();
+    dir.push("\\");
+    dir
+}
+
+fn cancel_jobs(name: &OsStr) {
+    BackgroundCopyManager::connect()
+        .unwrap()
+        .cancel_jobs_by_name(name)
+        .unwrap();
+}
+
+struct HttpServerResponses {
+    body: Box<[u8]>,
+    delay: u64,
+    //error: Box<[u8]>,
+}
+
+struct MockHttpServerHandle {
+    port: u16,
+    join: Option<JoinHandle<Result<(), ()>>>,
+    shutdown: Arc<(Mutex<bool>, Condvar)>,
+}
+
+impl MockHttpServerHandle {
+    fn shutdown(&mut self) {
+        if self.join.is_none() {
+            return;
+        }
+
+        {
+            let &(ref lock, ref cvar) = &*self.shutdown;
+            let mut shutdown = lock.lock().unwrap();
+
+            if !*shutdown {
+                *shutdown = true;
+                cvar.notify_all();
+            }
+        }
+        // Wake up the server from `accept()`. Will fail if the server wasn't listening.
+        let _ = TcpStream::connect_timeout(
+            &(SERVER_ADDRESS, self.port).into(),
+            Duration::from_millis(10_000),
+        );
+
+        match self.join.take().unwrap().join() {
+            Ok(_) => {}
+            Err(p) => panic::resume_unwind(p),
+        }
+    }
+
+    fn format_url(&self, name: &str) -> OsString {
+        format!(
+            "http://{}/{}",
+            SocketAddr::from((SERVER_ADDRESS, self.port)),
+            name
+        )
+        .into()
+    }
+}
+
+fn mock_http_server(name: &'static str, responses: HttpServerResponses) -> MockHttpServerHandle {
+    let mut bind_retries = 10;
+    let shutdown = Arc::new((Mutex::new(false), Condvar::new()));
+    let caller_shutdown = shutdown.clone();
+
+    let (listener, port) = loop {
+        let port = thread_rng().gen_range(1024..0x1_0000u32) as u16;
+        match TcpListener::bind(SocketAddr::from((SERVER_ADDRESS, port))) {
+            Ok(listener) => {
+                break (listener, port);
+            }
+            r @ Err(_) => {
+                if bind_retries == 0 {
+                    r.unwrap();
+                }
+                bind_retries -= 1;
+                continue;
+            }
+        }
+    };
+
+    let join = thread::Builder::new()
+        .name(format!("mock_http_server {}", name))
+        .spawn(move || {
+            // returns Err(()) if server should shut down immediately
+            fn check_shutdown(shutdown: &Arc<(Mutex<bool>, Condvar)>) -> Result<(), ()> {
+                if *shutdown.0.lock().unwrap() {
+                    Err(())
+                } else {
+                    Ok(())
+                }
+            }
+            fn sleep(shutdown: &Arc<(Mutex<bool>, Condvar)>, delay_millis: u64) -> Result<(), ()> {
+                let sleep_start = Instant::now();
+                let sleep_end = sleep_start + Duration::from_millis(delay_millis);
+
+                let (ref lock, ref cvar) = **shutdown;
+                let mut shutdown_requested = lock.lock().unwrap();
+                loop {
+                    if *shutdown_requested {
+                        return Err(());
+                    }
+
+                    let before_wait = Instant::now();
+                    if before_wait >= sleep_end {
+                        return Ok(());
+                    }
+                    let wait_dur = sleep_end - before_wait;
+                    shutdown_requested = cvar.wait_timeout(shutdown_requested, wait_dur).unwrap().0;
+                }
+            }
+
+            let error_404 = Regex::new(r"^((GET)|(HEAD)) [[:print:]]*/error_404 ").unwrap();
+            let error_500 = Regex::new(r"^((GET)|(HEAD)) [[:print:]]*/error_500 ").unwrap();
+
+            loop {
+                let (mut socket, _addr) = listener.accept().expect("accept should succeed");
+
+                socket
+                    .set_read_timeout(Some(Duration::from_millis(10_000)))
+                    .unwrap();
+                let mut s = Vec::new();
+                for b in Read::by_ref(&mut socket).bytes() {
+                    if b.is_err() {
+                        eprintln!("read error {:?}", b);
+                        break;
+                    }
+                    let b = b.unwrap();
+                    s.push(b);
+                    if s.ends_with(b"\r\n\r\n") {
+                        break;
+                    }
+                    check_shutdown(&shutdown)?;
+                }
+
+                // request received
+
+                check_shutdown(&shutdown)?;
+
+                // Special error URIs
+                if error_404.is_match(&s) {
+                    sleep(&shutdown, responses.delay)?;
+                    let result = socket
+                        .write(b"HTTP/1.1 404 Not Found\r\n\r\n")
+                        .and_then(|_| socket.flush());
+                    if let Err(e) = result {
+                        eprintln!("error writing 404 header {:?}", e);
+                    }
+                    continue;
+                }
+
+                if error_500.is_match(&s) {
+                    sleep(&shutdown, responses.delay)?;
+                    let result = socket
+                        .write(b"HTTP/1.1 500 Internal Server Error\r\n\r\n")
+                        .and_then(|_| socket.flush());
+                    if let Err(e) = result {
+                        eprintln!("error writing 500 header {:?}", e);
+                    }
+                    continue;
+                }
+
+                // Response with a body.
+                if s.starts_with(b"HEAD") || s.starts_with(b"GET") {
+                    let result = socket
+                        .write(
+                            format!(
+                                "HTTP/1.1 200 OK\r\nContent-Length: {}\r\n\r\n",
+                                responses.body.len()
+                            )
+                            .as_bytes(),
+                        )
+                        .and_then(|_| socket.flush());
+                    if let Err(e) = result {
+                        eprintln!("error writing header {:?}", e);
+                        continue;
+                    }
+                }
+
+                if s.starts_with(b"GET") {
+                    sleep(&shutdown, responses.delay)?;
+                    let result = socket.write(&responses.body).and_then(|_| socket.flush());
+                    if let Err(e) = result {
+                        eprintln!("error writing content {:?}", e);
+                        continue;
+                    }
+                }
+            }
+        });
+
+    MockHttpServerHandle {
+        port,
+        join: Some(join.unwrap()),
+        shutdown: caller_shutdown,
+    }
+}
+
+// Test wrapper to ensure jobs are canceled, set up name strings
+macro_rules! test {
+    (fn $name:ident($param:ident : &str, $tmpdir:ident : &TempDir) $body:block) => {
+        #[test]
+        fn $name() {
+            let $param = stringify!($name);
+            let $tmpdir = &Builder::new().prefix($param).tempdir().unwrap();
+
+            let result = panic::catch_unwind(|| $body);
+
+            cancel_jobs(&format_job_name($param));
+
+            if let Err(e) = result {
+                panic::resume_unwind(e);
+            }
+        }
+    };
+}
+
+test! {
+    fn start_monitor_and_cancel(name: &str, tmp_dir: &TempDir) {
+        let mut server = mock_http_server(name, HttpServerResponses {
+            body: name.to_owned().into_boxed_str().into_boxed_bytes(),
+            delay: 10_000,
+        });
+
+        let mut client = InProcessClient::new(format_job_name(name), tmp_dir.path().into()).unwrap();
+
+        let no_progress_timeout_secs = 60;
+        let interval = 10_000;
+        let timeout = 10_000;
+
+        let (StartJobSuccess {guid}, mut monitor) =
+            client.start_job(
+                server.format_url(name),
+                name.into(),
+                BitsProxyUsage::Preconfig,
+                no_progress_timeout_secs,
+                interval,
+                ).unwrap();
+
+        // cancel in ~250ms
+        let _join = thread::Builder::new()
+            .spawn(move || {
+                thread::sleep(Duration::from_millis(250));
+                client.cancel_job(guid).unwrap();
+            });
+
+        let start = Instant::now();
+
+        // First immediate report
+        monitor.get_status(timeout).expect("should initially be ok").unwrap();
+
+        // ~250ms the cancel should cause an immediate disconnect (otherwise we wouldn't get
+        // an update until 10s when the transfer completes or the interval expires)
+        match monitor.get_status(timeout) {
+            Err(Error::NotConnected) => {},
+            Ok(r) => panic!("unexpected success from get_status() {:?}", r),
+            Err(e) => panic!("unexpected failure from get_status() {:?}", e),
+        }
+        assert!(start.elapsed() < Duration::from_millis(9_000));
+
+        server.shutdown();
+    }
+}
+
+test! {
+    fn start_monitor_and_complete(name: &str, tmp_dir: &TempDir) {
+        let file_path = tmp_dir.path().join(name);
+
+        let mut server = mock_http_server(name, HttpServerResponses {
+            body: name.to_owned().into_boxed_str().into_boxed_bytes(),
+            delay: 500,
+        });
+
+        let mut client = InProcessClient::new(format_job_name(name), format_dir_prefix(tmp_dir)).unwrap();
+
+        let no_progress_timeout_secs = 60;
+        let interval = 100;
+        let timeout = 10_000;
+
+        let (StartJobSuccess {guid}, mut monitor) =
+            client.start_job(
+                server.format_url(name),
+                name.into(),
+                BitsProxyUsage::Preconfig,
+                no_progress_timeout_secs,
+                interval,
+                ).unwrap();
+
+        let start = Instant::now();
+
+        // Get status reports until transfer finishes (~500ms)
+        let mut completed = false;
+        loop {
+            match monitor.get_status(timeout) {
+                Err(e) => {
+                    if completed {
+                        break;
+                    } else {
+                        panic!("monitor failed before completion {:?}", e);
+                    }
+                }
+                Ok(Ok(status)) => match BitsJobState::from(status.state) {
+                    BitsJobState::Queued | BitsJobState::Connecting
+                        | BitsJobState::Transferring => {
+                            //eprintln!("{:?}", BitsJobState::from(status.state));
+                            //eprintln!("{:?}", status);
+
+                            // As long as there is no error, setting the timeout to 0 will not
+                            // fail an active transfer.
+                            client.set_no_progress_timeout(guid.clone(), 0).unwrap();
+                        }
+                    BitsJobState::Transferred => {
+                        client.complete_job(guid.clone()).unwrap();
+                        completed = true;
+                    }
+                    _ => {
+                        panic!("{:?}", status);
+                    }
+                }
+                Ok(Err(e)) => panic!("{:?}", e),
+            }
+
+            // Timeout to prevent waiting forever
+            assert!(start.elapsed() < Duration::from_millis(60_000));
+        }
+
+
+        // Verify file contents
+        let result = panic::catch_unwind(|| {
+            let mut file = File::open(file_path.clone()).unwrap();
+            let mut v = Vec::new();
+            file.read_to_end(&mut v).unwrap();
+            assert_eq!(v, name.as_bytes());
+        });
+
+        let _ = fs::remove_file(file_path);
+
+        if let Err(e) = result {
+            panic::resume_unwind(e);
+        }
+
+        // Save this for last to ensure the file is removed.
+        server.shutdown();
+    }
+}
+
+test! {
+    fn async_transferred_notification(name: &str, tmp_dir: &TempDir) {
+        let mut server = mock_http_server(name, HttpServerResponses {
+            body: name.to_owned().into_boxed_str().into_boxed_bytes(),
+            delay: 250,
+        });
+
+        let mut client = InProcessClient::new(format_job_name(name), format_dir_prefix(tmp_dir)).unwrap();
+
+        let no_progress_timeout_secs = 60;
+        let interval = 60_000;
+        let timeout = 10_000;
+
+        let (_, mut monitor) =
+            client.start_job(
+                server.format_url(name),
+                name.into(),
+                BitsProxyUsage::Preconfig,
+                no_progress_timeout_secs,
+                interval,
+                ).unwrap();
+
+        // Start the timer now, the initial job creation may be delayed by BITS service startup.
+        let start = Instant::now();
+
+        // First report, immediate
+        let report_1 = monitor.get_status(timeout).expect("should initially be ok").unwrap();
+        let elapsed_to_report_1 = start.elapsed();
+
+        // Transferred notification should come when the job completes in ~250 ms, otherwise we
+        // will be stuck until timeout.
+        let report_2 = monitor.get_status(timeout).expect("should get status update").unwrap();
+        let elapsed_to_report_2 = start.elapsed();
+        assert!(elapsed_to_report_2 < Duration::from_millis(9_000));
+        assert_eq!(report_2.state, BitsJobState::Transferred);
+
+        let short_timeout = 500;
+        let report_3 = monitor.get_status(short_timeout);
+        let elapsed_to_report_3 = start.elapsed();
+
+        if let Ok(report_3) = report_3 {
+          panic!("should be disconnected\n\
+                  report_1 ({}.{:03}): {:?}\n\
+                  report_2 ({}.{:03}): {:?}\n\
+                  report_3 ({}.{:03}): {:?}",
+                  elapsed_to_report_1.as_secs(), elapsed_to_report_1.subsec_millis(), report_1,
+                  elapsed_to_report_2.as_secs(), elapsed_to_report_2.subsec_millis(), report_2,
+                  elapsed_to_report_3.as_secs(), elapsed_to_report_3.subsec_millis(), report_3,
+                  );
+        }
+
+        server.shutdown();
+
+        // job will be cancelled by macro
+    }
+}
+
+test! {
+    fn change_interval(name: &str, tmp_dir: &TempDir) {
+        let mut server = mock_http_server(name, HttpServerResponses {
+            body: name.to_owned().into_boxed_str().into_boxed_bytes(),
+            delay: 1000,
+        });
+
+        let mut client = InProcessClient::new(format_job_name(name), format_dir_prefix(tmp_dir)).unwrap();
+
+        let no_progress_timeout_secs = 0;
+        let interval = 60_000;
+        let timeout = 10_000;
+
+        let (StartJobSuccess { guid }, mut monitor) =
+            client.start_job(
+                server.format_url(name),
+                name.into(),
+                BitsProxyUsage::Preconfig,
+                no_progress_timeout_secs,
+                interval,
+                ).unwrap();
+
+        let start = Instant::now();
+
+        // reduce monitor interval in ~250ms to 500ms
+        let _join = thread::Builder::new()
+            .spawn(move || {
+                thread::sleep(Duration::from_millis(250));
+                client.set_update_interval(guid, 500).unwrap();
+            });
+
+        // First immediate report
+        monitor.get_status(timeout).expect("should initially be ok").unwrap();
+
+        // Next report should be rescheduled to 500ms by the spawned thread, otherwise no status
+        // until the original 10s interval.
+        monitor.get_status(timeout).expect("expected second status").unwrap();
+        assert!(start.elapsed() < Duration::from_millis(9_000));
+        assert!(start.elapsed() > Duration::from_millis(400));
+
+        server.shutdown();
+
+        // job will be cancelled by macro
+    }
+}
+
+test! {
+    fn async_error_notification(name: &str, tmp_dir: &TempDir) {
+        let mut server = mock_http_server(name, HttpServerResponses {
+            body: name.to_owned().into_boxed_str().into_boxed_bytes(),
+            delay: 100,
+        });
+
+        let mut client = InProcessClient::new(format_job_name(name), format_dir_prefix(tmp_dir)).unwrap();
+
+        let no_progress_timeout_secs = 60;
+        let interval = 60_000;
+        let timeout = 10_000;
+
+        let (_, mut monitor) =
+            client.start_job(
+                server.format_url("error_404"),
+                name.into(),
+                BitsProxyUsage::Preconfig,
+                no_progress_timeout_secs,
+                interval,
+                ).unwrap();
+
+        // Start the timer now, the initial job creation may be delayed by BITS service startup.
+        let start = Instant::now();
+
+        // First immediate report
+        monitor.get_status(timeout).expect("should initially be ok").unwrap();
+
+        // Error notification should come with HEAD response in 100ms, otherwise no status until
+        // 10s interval or timeout.
+        let status = monitor.get_status(timeout).expect("should get status update").unwrap();
+        assert!(start.elapsed() < Duration::from_millis(9_000));
+        assert_eq!(status.state, BitsJobState::Error);
+
+        server.shutdown();
+
+        // job will be cancelled by macro
+    }
+}
+
+test! {
+    fn transient_error(name: &str, tmp_dir: &TempDir) {
+        let mut server = mock_http_server(name, HttpServerResponses {
+            body: name.to_owned().into_boxed_str().into_boxed_bytes(),
+            delay: 100,
+        });
+
+        let mut client = InProcessClient::new(format_job_name(name), format_dir_prefix(tmp_dir)).unwrap();
+
+        let no_progress_timeout_secs = 60;
+        let interval = 1_000;
+        let timeout = 10_000;
+
+        let (StartJobSuccess { guid }, mut monitor) =
+            client.start_job(
+                server.format_url("error_500"),
+                name.into(),
+                BitsProxyUsage::Preconfig,
+                no_progress_timeout_secs,
+                interval,
+                ).unwrap();
+
+        // Start the timer now, the initial job creation may be delayed by BITS service startup.
+        let start = Instant::now();
+
+        // First immediate report
+        monitor.get_status(timeout).expect("should initially be ok").unwrap();
+
+        // Transient error notification should come when the interval expires in ~1s.
+        let status = monitor.get_status(timeout).expect("should get status update").unwrap();
+        assert!(start.elapsed() > Duration::from_millis(900));
+        assert!(start.elapsed() < Duration::from_millis(9_000));
+        assert_eq!(status.state, BitsJobState::TransientError);
+
+        // Lower no progress timeout to 0
+        let set_timeout_at = Instant::now();
+        client.set_no_progress_timeout(guid, 0).unwrap();
+
+        // Should convert the transient error to a permanent error immediately.
+        let status = monitor.get_status(timeout).expect("should get status update").unwrap();
+        assert!(set_timeout_at.elapsed() < Duration::from_millis(500));
+        assert_eq!(status.state, BitsJobState::Error);
+
+        server.shutdown();
+
+        // job will be cancelled by macro
+    }
+}
+
+test! {
+    fn transient_to_permanent_error(name: &str, tmp_dir: &TempDir) {
+        let mut server = mock_http_server(name, HttpServerResponses {
+            body: name.to_owned().into_boxed_str().into_boxed_bytes(),
+            delay: 100,
+        });
+
+        let mut client = InProcessClient::new(format_job_name(name), format_dir_prefix(tmp_dir)).unwrap();
+
+        let no_progress_timeout_secs = 0;
+        let interval = 1_000;
+        let timeout = 10_000;
+
+        let (_, mut monitor) =
+            client.start_job(
+                server.format_url("error_500"),
+                name.into(),
+                BitsProxyUsage::Preconfig,
+                no_progress_timeout_secs,
+                interval,
+                ).unwrap();
+
+        // Start the timer now, the initial job creation may be delayed by BITS service startup.
+        let start = Instant::now();
+
+        // First immediate report
+        monitor.get_status(timeout).expect("should initially be ok").unwrap();
+
+        // 500 is a transient error, but with no_progress_timeout_secs = 0 it should immediately
+        // produce an error notification with the HEAD response in 100ms. Otherwise no status
+        // until 10s interval or timeout.
+        let status = monitor.get_status(timeout).expect("should get status update").unwrap();
+        assert!(start.elapsed() < Duration::from_millis(500));
+        assert_eq!(status.state, BitsJobState::Error);
+
+        server.shutdown();
+
+        // job will be cancelled by macro
+    }
+}
diff --git a/toolkit/components/bitsdownload/bits_client/src/lib.rs b/toolkit/components/bitsdownload/bits_client/src/lib.rs
new file mode 100644
index 0000000000..7db887bbc5
--- /dev/null
+++ b/toolkit/components/bitsdownload/bits_client/src/lib.rs
@@ -0,0 +1,258 @@
+/* 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/. */
+
+//! An interface for managing and monitoring BITS jobs.
+//!
+//! BITS is a Windows service for performing downloads in the background, independent from an
+//! application, usually via HTTP/HTTPS.
+//!
+//! [`BitsClient`](enum.BitsClient.html) is the main interface, used to issue commands.
+//!
+//! [`BitsMonitorClient`](enum.BitsMonitorClient.html) delivers periodic status reports about a
+//! job.
+//!
+//! Microsoft's documentation for BITS can be found at
+//! <https://docs.microsoft.com/en-us/windows/desktop/Bits/background-intelligent-transfer-service-portal>
+
+extern crate bits;
+extern crate comedy;
+extern crate guid_win;
+extern crate thiserror;
+
+pub mod bits_protocol;
+
+mod in_process;
+
+use std::ffi;
+
+use bits_protocol::*;
+use thiserror::Error;
+
+pub use bits::status::{BitsErrorContext, BitsJobState, BitsJobTimes};
+pub use bits::{BitsJobProgress, BitsJobStatus, BitsProxyUsage};
+pub use bits_protocol::{JobError, JobStatus};
+pub use comedy::HResult;
+pub use guid_win::Guid;
+
+// These errors would come from a Local Service client but are mostly unused currently.
+// PipeError properly lives in the crate that deals with named pipes, but it isn't in use now.
+#[derive(Clone, Debug, Eq, Error, PartialEq)]
+pub enum PipeError {
+    #[error("Pipe is not connected")]
+    NotConnected,
+    #[error("Operation timed out")]
+    Timeout,
+    #[error("Should have written {0} bytes, wrote {1}")]
+    WriteCount(usize, u32),
+    #[error("Windows API error")]
+    Api(#[from] HResult),
+}
+
+pub use PipeError as Error;
+
+/// A client for interacting with BITS.
+///
+/// Methods on `BitsClient` return a `Result<Result<_, XyzFailure>, Error>`. The outer `Result`
+/// is `Err` if there was a communication error in sending the associated command or receiving
+/// its response. Currently this is always `Ok` as all clients are in-process. The inner
+/// `Result` is `Err` if there was an error executing the command.
+///
+/// A single `BitsClient` can be used with multiple BITS jobs simultaneously; generally a job
+/// is not bound tightly to a client.
+///
+/// A `BitsClient` tracks all [`BitsMonitorClient`s](enum.BitsMonitorClient.html) that it started
+/// with `start_job()` or `monitor_job()`, so that the monitor can be stopped or modified.
+pub enum BitsClient {
+    // The `InProcess` variant does all BITS calls directly.
+    #[doc(hidden)]
+    InProcess(in_process::InProcessClient),
+    // Space is reserved here for the LocalService variant, which will work through an external
+    // process running as Local Service.
+}
+
+use BitsClient::InProcess;
+
+impl BitsClient {
+    /// Create an in-process `BitsClient`.
+    ///
+    /// `job_name` will be used when creating jobs, and this `BitsClient` can only be used to
+    /// manipulate jobs with that name.
+    ///
+    /// `save_path_prefix` will be prepended to the local `save_path` given to `start_job()`, it
+    /// must name an existing directory.
+    pub fn new(
+        job_name: ffi::OsString,
+        save_path_prefix: ffi::OsString,
+    ) -> Result<BitsClient, Error> {
+        Ok(InProcess(in_process::InProcessClient::new(
+            job_name,
+            save_path_prefix,
+        )?))
+    }
+
+    /// Start a job to download a single file at `url` to local path `save_path` (relative to the
+    /// `save_path_prefix` given when constructing the `BitsClient`).
+    ///
+    /// `save_path_prefix` combined with `save_path` must name a file (existing or not) in an
+    /// existing directory, which must be under the directory named by `save_path_prefix`.
+    ///
+    /// `proxy_usage` determines what proxy will be used.
+    ///
+    /// When a successful result `Ok(result)` is returned, `result.0.guid` is the id for the
+    /// new job, and `result.1` is a monitor client that can be polled for periodic updates,
+    /// returning a result approximately once per `monitor_interval_millis` milliseconds.
+    pub fn start_job(
+        &mut self,
+        url: ffi::OsString,
+        save_path: ffi::OsString,
+        proxy_usage: BitsProxyUsage,
+        no_progress_timeout_secs: u32,
+        monitor_interval_millis: u32,
+    ) -> Result<Result<(StartJobSuccess, BitsMonitorClient), StartJobFailure>, Error> {
+        match self {
+            InProcess(client) => Ok(client
+                .start_job(
+                    url,
+                    save_path,
+                    proxy_usage,
+                    no_progress_timeout_secs,
+                    monitor_interval_millis,
+                )
+                .map(|(success, monitor)| (success, BitsMonitorClient::InProcess(monitor)))),
+        }
+    }
+
+    /// Start monitoring the job with id `guid` approximately once per `monitor_interval_millis`
+    /// milliseconds.
+    ///
+    /// The returned `Ok(monitor)` is a monitor client to be polled for periodic updates.
+    ///
+    /// There can only be one ongoing `BitsMonitorClient` for each job associated with a given
+    /// `BitsClient`. If a monitor client already exists for the specified job, it will be stopped.
+    pub fn monitor_job(
+        &mut self,
+        guid: Guid,
+        interval_millis: u32,
+    ) -> Result<Result<BitsMonitorClient, MonitorJobFailure>, Error> {
+        match self {
+            InProcess(client) => Ok(client
+                .monitor_job(guid, interval_millis)
+                .map(BitsMonitorClient::InProcess)),
+        }
+    }
+
+    /// Suspend job `guid`.
+    pub fn suspend_job(&mut self, guid: Guid) -> Result<Result<(), SuspendJobFailure>, Error> {
+        match self {
+            InProcess(client) => Ok(client.suspend_job(guid)),
+        }
+    }
+
+    /// Resume job `guid`.
+    pub fn resume_job(&mut self, guid: Guid) -> Result<Result<(), ResumeJobFailure>, Error> {
+        match self {
+            InProcess(client) => Ok(client.resume_job(guid)),
+        }
+    }
+
+    /// Set the priority of job `guid`.
+    ///
+    /// `foreground == true` will set the priority to `BG_JOB_PRIORITY_FOREGROUND`,
+    /// `false` will use the default `BG_JOB_PRIORITY_NORMAL`.
+    /// See the Microsoft documentation for `BG_JOB_PRIORITY` for details.
+    ///
+    /// A job created by `start_job()` will be foreground priority, by default.
+    pub fn set_job_priority(
+        &mut self,
+        guid: Guid,
+        foreground: bool,
+    ) -> Result<Result<(), SetJobPriorityFailure>, Error> {
+        match self {
+            InProcess(client) => Ok(client.set_job_priority(guid, foreground)),
+        }
+    }
+
+    /// Set the "no progress timeout" of job `guid`.
+    pub fn set_no_progress_timeout(
+        &mut self,
+        guid: Guid,
+        timeout_secs: u32,
+    ) -> Result<Result<(), SetNoProgressTimeoutFailure>, Error> {
+        match self {
+            InProcess(client) => Ok(client.set_no_progress_timeout(guid, timeout_secs)),
+        }
+    }
+
+    /// Change the update interval for an ongoing monitor of job `guid`.
+    pub fn set_update_interval(
+        &mut self,
+        guid: Guid,
+        interval_millis: u32,
+    ) -> Result<Result<(), SetUpdateIntervalFailure>, Error> {
+        match self {
+            InProcess(client) => Ok(client.set_update_interval(guid, interval_millis)),
+        }
+    }
+
+    /// Stop any ongoing monitor for job `guid`.
+    pub fn stop_update(
+        &mut self,
+        guid: Guid,
+    ) -> Result<Result<(), SetUpdateIntervalFailure>, Error> {
+        match self {
+            InProcess(client) => Ok(client.stop_update(guid)),
+        }
+    }
+
+    /// Complete the job `guid`.
+    ///
+    /// This also stops any ongoing monitor for the job.
+    pub fn complete_job(&mut self, guid: Guid) -> Result<Result<(), CompleteJobFailure>, Error> {
+        match self {
+            InProcess(client) => Ok(client.complete_job(guid)),
+        }
+    }
+
+    /// Cancel the job `guid`.
+    ///
+    /// This also stops any ongoing monitor for the job.
+    pub fn cancel_job(&mut self, guid: Guid) -> Result<Result<(), CancelJobFailure>, Error> {
+        match self {
+            InProcess(client) => Ok(client.cancel_job(guid)),
+        }
+    }
+}
+
+/// The client side of a monitor for a BITS job.
+///
+/// It is intended to be used by calling `get_status` in a loop to receive notifications about
+/// the status of a job. Because `get_status` blocks, it is recommended to run this loop on its
+/// own thread.
+pub enum BitsMonitorClient {
+    InProcess(in_process::InProcessMonitor),
+}
+
+impl BitsMonitorClient {
+    /// `get_status` will return a result approximately every `monitor_interval_millis`
+    /// milliseconds, but in case a result isn't available within `timeout_millis` milliseconds
+    /// this will return `Err(Error::Timeout)`. Any `Err` returned, including timeout, indicates
+    /// that the monitor has been stopped; the `BitsMonitorClient` should then be discarded.
+    ///
+    /// As with methods on `BitsClient`, `BitsMonitorClient::get_status()` has an inner `Result`
+    /// type which indicates an error returned from the server. Any `Err` here also indicates that
+    /// the monitor has stopped after yielding the result.
+    ///
+    /// The first time `get_status` is called it will return a status without any delay.
+    ///
+    /// If there is an error or the transfer completes, a result may be available sooner than
+    /// the monitor interval.
+    pub fn get_status(
+        &mut self,
+        timeout_millis: u32,
+    ) -> Result<Result<JobStatus, HResultMessage>, Error> {
+        match self {
+            BitsMonitorClient::InProcess(client) => client.get_status(timeout_millis),
+        }
+    }
+}