#![cfg_attr(docsrs, feature(doc_cfg))]

#![doc = include_str!("../README.md")]

// @@ begin lint list maintained by maint/add_warning @@

#![allow(renamed_and_removed_lints)] // @@REMOVE_WHEN(ci_arti_stable)

#![allow(unknown_lints)] // @@REMOVE_WHEN(ci_arti_nightly)

#![warn(missing_docs)]

#![warn(noop_method_call)]

#![warn(unreachable_pub)]

#![warn(clippy::all)]

#![deny(clippy::await_holding_lock)]

#![deny(clippy::cargo_common_metadata)]

#![deny(clippy::cast_lossless)]

#![deny(clippy::checked_conversions)]

#![allow(clippy::cognitive_complexity)] // See arti#2556

#![deny(clippy::debug_assert_with_mut_call)]

#![deny(clippy::exhaustive_enums)]

#![deny(clippy::exhaustive_structs)]

#![deny(clippy::expl_impl_clone_on_copy)]

#![deny(clippy::fallible_impl_from)]

#![deny(clippy::implicit_clone)]

#![deny(clippy::large_stack_arrays)]

#![warn(clippy::manual_ok_or)]

#![deny(clippy::missing_docs_in_private_items)]

#![warn(clippy::needless_borrow)]

#![warn(clippy::needless_pass_by_value)]

#![warn(clippy::option_option)]

#![warn(clippy::or_fun_call)]

#![deny(clippy::print_stderr)]

#![deny(clippy::print_stdout)]

#![warn(clippy::rc_buffer)]

#![deny(clippy::ref_option_ref)]

#![warn(clippy::semicolon_if_nothing_returned)]

#![warn(clippy::trait_duplication_in_bounds)]

#![deny(clippy::unchecked_time_subtraction)]

#![deny(clippy::unnecessary_wraps)]

#![warn(clippy::unseparated_literal_suffix)]

#![deny(clippy::unwrap_used)]

#![deny(clippy::mod_module_files)]

#![allow(clippy::let_unit_value)] // This can reasonably be done for explicitness

#![allow(clippy::uninlined_format_args)]

#![allow(clippy::significant_drop_in_scrutinee)] // arti/-/merge_requests/588/#note_2812945

#![allow(clippy::result_large_err)] // temporary workaround for arti#587

#![allow(clippy::needless_raw_string_hashes)] // complained-about code is fine, often best

#![allow(clippy::needless_lifetimes)] // See arti#1765

#![allow(mismatched_lifetime_syntaxes)] // temporary workaround for arti#2060

#![allow(clippy::collapsible_if)] // See arti#2342

#![deny(clippy::unused_async)]

#![deny(clippy::string_slice)] // See arti#2571

#![allow(recursion_depth_exceeding_limit)] // arti#2715, rust/issues/159228

//! <!-- @@ end lint list maintained by maint/add_warning @@ -->

// TODO probably remove this at some point - see tpo/core/arti#1060

#![cfg_attr(

    not(all(feature = "full", feature = "experimental")),

    allow(unused_imports)

)]

mod body;

mod err;

pub mod request;

mod response;

mod util;

use tor_circmgr::{CircMgr, DirInfo};

use tor_error::bad_api_usage;

use tor_rtcompat::{Runtime, SleepProvider, SleepProviderExt};

// Zlib is required; the others are optional.

#[cfg(feature = "xz")]

use async_compression::futures::bufread::XzDecoder;

use async_compression::futures::bufread::ZlibDecoder;

#[cfg(feature = "zstd")]

use async_compression::futures::bufread::ZstdDecoder;

use futures::FutureExt;

use futures::io::{

    AsyncBufRead, AsyncBufReadExt, AsyncRead, AsyncReadExt, AsyncWrite, AsyncWriteExt, BufReader,

};

use std::sync::Arc;

use std::time::Duration;

use tracing::{info, instrument};

pub use err::{Error, RequestError, RequestFailedError};

pub use response::{DirResponse, SourceInfo};

/// Type for results returned in this crate.

pub type Result<T> = std::result::Result<T, Error>;

/// Type for internal results  containing a RequestError.

pub type RequestResult<T> = std::result::Result<T, RequestError>;

/// Flag to declare whether a request is always anonymized or not.

///

/// This is used by tor-dirclient to control whether *other* deanonymizing metadata

/// might be added to the request (eg in request headers):

/// Some requests (like those to download onion service descriptors) are always

/// anonymized, and should never be sent in a way that leaks information about

/// our settings or configuration.

///

/// It is up to the *caller* of `tor-dirclient` to ensure that

///

///   - every request whose anonymization status is `AnonymizedRequest::Direct`

///     is sent only over non-anonymous connections.

///

///     (Sending an `AnonymizedRequest::Direct` request over an anonymized connection

///     would weaken the connection's anonymity, and can therefore weaken the anonymity

///     of user traffic sharing the same circuit.)

///

///   - every request whose anonymization status is `AnonymizedRequest::Anonymized`

///     is sent over only anonymous connections (ie, multi-hop circuits).

///

///     (Sending an `AnonymizedRequest::Anonymized` request over a direct connection

///     would directly reveal user behaviour data to the directory server.)

///

/// TODO the calling code cannot easily be sure to get this right this because

/// the anonymization status is a run-time property and the choice of connection kind

/// is statically defined in the calling code.  (Perhaps this could be checked in tests?)

#[derive(Copy, Clone, Debug, Eq, PartialEq)]

#[non_exhaustive]

pub enum AnonymizedRequest {

    /// This request's content or semantics reveals or is correlated with sensitive information.

    ///

    /// For example, requests for hidden service descriptors reveal which hidden services

    /// the client is connecting to.

    ///

    /// The request must be sent over an anonymous circuit by the caller

    /// and no additional deanonymizing information should be added to it by `tor-dirclient`.

    /// (For example, no client-version-specific information should be

    /// sent in HTTP headers when the request is made.)

    Anonymized,

    /// Making this request does not reveal anything sensitive, nor any user behaviour.

    ///

    /// The request body is uncorrelated with such things as the websites the user might visit,

    /// the onion services the user is visiting or running, etc.

    ///

    /// For example, requests for all router microdescriptors are made by all clients,

    /// so which microdescriptor(s) are requested reveals nothing to any attacker.

    ///

    /// tor-dirclient is allowed to add include information about our capabilities

    /// when sending this request.

    /// The request must *not* be sent over an anonymous circuit by the caller

    /// (at least, not one used for anything else).

    Direct,

}

/// Fetch the resource described by `req` over the Tor network.

///

/// Circuits are built or found using `circ_mgr`, using paths

/// constructed using `dirinfo`.

///

/// For more fine-grained control over the circuit and stream used,

/// construct them yourself, and then call [`send_request`] instead.

///

/// # TODO

///

/// This is the only function in this crate that knows about CircMgr and

/// DirInfo.  Perhaps this function should move up a level into DirMgr?

#[instrument(level = "trace", skip_all)]

    let tunnel = circ_mgr.get_or_launch_dir(dirinfo).await?;

    if req.anonymized() == AnonymizedRequest::Anonymized {

        return Err(bad_api_usage!("Tried to use get_resource for an anonymized request").into());

    }

    // TODO(nickm) This should be an option, and is too long.

    let begin_timeout = Duration::from_secs(5);

    let source = match SourceInfo::from_tunnel(&tunnel) {

        Ok(source) => source,

        Err(e) => {

            return Err(Error::RequestFailed(RequestFailedError {

                source: None,

                error: e.into(),

            }));

        }

    };

    req.check_circuit_skip_optimization(&tunnel)

        .await

        .map_err(wrap_err)?;

    // Launch the stream.

    let mut stream = runtime

        .timeout(begin_timeout, tunnel.begin_dir_stream())

        .await

        .map_err(RequestError::from)

        .map_err(wrap_err)?

        .map_err(RequestError::from)

        .map_err(wrap_err)?; // TODO(nickm) handle fatalities here too

    // TODO: Perhaps we want separate timeouts for each phase of this.

    // For now, we just use higher-level timeouts in `dirmgr`.

    let r = send_request(runtime, req, &mut stream, source.clone()).await;

    if should_retire_circ(&r) {

        retire_circ(&circ_mgr, &tunnel.unique_id(), "Partial response");

    }

    r

/// Return true if `result` holds an error indicating that we should retire the

/// circuit used for the corresponding request.

    }

/// Fetch a Tor directory object from a provided stream.

#[deprecated(since = "0.8.1", note = "Use send_request instead.")]

/// Fetch or upload a Tor directory object using the provided stream.

///

/// To do this, we send a simple HTTP/1.0 request for the described

/// object in `req` over `stream`, and then wait for a response.  In

/// log messages, we describe the origin of the data as coming from

/// `source`.

///

/// # Notes

///

/// It's kind of bogus to have a 'source' field here at all; we may

/// eventually want to remove it.

///

/// This function doesn't close the stream; you may want to do that

/// yourself.

///

/// The only error variant returned is [`Error::RequestFailed`].

// TODO: should the error return type change to `RequestFailedError`?

// If so, that would simplify some code in_dirmgr::bridgedesc.

    // Write the request.

    }

    // Handle the response

            // Note that we _don't_ return here: we want the partial response.

        }

        }

    };

/// Maximum length for the HTTP headers in a single request or response.

///

/// Chosen more or less arbitrarily.

const MAX_HEADERS_LEN: usize = 16384;

/// Read and parse HTTP/1 headers from `stream`.

///

/// Wraps around [`read_headers_internal()`] with a timeout.

    // Just like with the other timeouts in this code, this should probably be

    // configurable and may even be too much.

/// Internal version of [`read_headers()`] without a timeout.

    // Note: Using `take` here will ensure that we will get an EOF if the header length

    // would exceed the maximum.  No extra bytes will actually be extracted.

    loop {

        // TODO: it's inefficient to do this a line at a time; it would

        // probably be better to read until the CRLF CRLF ending of the

        // response.  But this should be fast enough.

        // TODO(nickm): Better maximum and/or let this expand.

            httparse::Status::Partial => {

                // We didn't get a whole response; we may need to try again.

                    // We hit an EOF; no more progress can be made.

            }

                {

                } else {

                };

                /*

                if let Some(clen) = response.headers.iter().find(|h| h.name == "Content-Length") {

                    let clen = std::str::from_utf8(clen.value)?;

                    length = Some(clen.parse()?);

                }

                 */

            }

        }

    }

/// Return value from read_headers

#[derive(Debug, Clone)]

struct HeaderStatus {

    /// HTTP status code.

    status: Option<u16>,

    /// HTTP status message associated with the status code.

    status_message: Option<String>,

    /// The Content-Encoding header, if any.

    encoding: Option<String>,

}

/// Helper: download directory information from `stream` and

/// decompress it into a result buffer.  Assumes that `buf` is empty.

///

/// If we get more than maxlen bytes after decompression, give an error.

///

/// Returns the status of our download attempt, stores any data that

/// we were able to download into `result`.  Existing contents of

/// `result` are overwritten.

    // TODO(nickm): This should be an option, and is maybe too long.

    // Though for some users it may be too short?

    loop {

        // allocate buffer for next read

            _ = timer => {

            }

        };

            }

        };

        // exit conditions below

            /*

            in case we read less than `buffer_window_size` in last `read`

            we need to shrink result because otherwise we'll return those

            un-read 0s

            */

        // TODO: It would be good to detect compression bombs, but

        // that would require access to the internal stream, which

        // would in turn require some tricky programming.  For now, we

        // use the maximum length here to prevent an attacker from

        // filling our RAM.

    }

/// Retire a directory circuit because of an error we've encountered on it.

{

        "{}: Retiring circuit because of directory failure: {}",

    );

/// Memory limit of the LZMA dictionary we are willing to allocate.

///

/// Without it, it may lead to an allocation of 4GiB, which is a bit overkill.

///

/// Right now, we use 16 MiB, as the spec limits the compression quality to

/// "6", meaning 9 MiB of decompression memory, which rounds up to 16 MiB in

/// terms of base 2.

///

/// From the xz(1) manual page:

/// ```text

/// Preset   DictSize   CompCPU   CompMem   DecMem

///  -0e     256 KiB       8        4 MiB    1 MiB

///  -1e       1 MiB       8       13 MiB    2 MiB

///  -2e       2 MiB       8       25 MiB    3 MiB

///  -3e       4 MiB       7       48 MiB    5 MiB

///  -4e       4 MiB       8       48 MiB    5 MiB

///  -5e       8 MiB       7       94 MiB    9 MiB

///  -6e       8 MiB       8       94 MiB    9 MiB

///  -7e      16 MiB       8      186 MiB   17 MiB

///  -8e      32 MiB       8      370 MiB   33 MiB

///  -9e      64 MiB       8      674 MiB   65 MiB

/// ```

const LZMA_DICT_MEM_LIMIT: u64 = 1 << 24; // 16 MiB

/// Helper: Return a boxed decoder object that wraps the stream  $s.

macro_rules! decoder {

    (XzDecoder, $s:expr) => {{

        let mut decoder = XzDecoder::with_mem_limit($s, LZMA_DICT_MEM_LIMIT);

        decoder.multiple_members(true);

        Ok(Box::new(decoder))

    }};

    ($dec:ident, $s:expr) => {{

        let mut decoder = $dec::new($s);

        decoder.multiple_members(true);

        Ok(Box::new(decoder))

    }};

}

/// Wrap `stream` in an appropriate type to undo the content encoding

/// as described in `encoding`.

    use AnonymizedRequest::Direct;

        // We only admit to supporting these on a direct connection; otherwise,

        // a hostile directory could send them back even though we hadn't

        // requested them.

        #[cfg(feature = "xz")]

        #[cfg(feature = "zstd")]

    }

#[cfg(test)]

mod test {

    // @@ begin test lint list maintained by maint/add_warning @@

    #![allow(clippy::bool_assert_comparison)]

    #![allow(clippy::clone_on_copy)]

    #![allow(clippy::dbg_macro)]

    #![allow(clippy::mixed_attributes_style)]

    #![allow(clippy::print_stderr)]

    #![allow(clippy::print_stdout)]

    #![allow(clippy::single_char_pattern)]

    #![allow(clippy::unwrap_used)]

    #![allow(clippy::unchecked_time_subtraction)]

    #![allow(clippy::useless_vec)]

    #![allow(clippy::needless_pass_by_value)]

    #![allow(clippy::string_slice)] // See arti#2571

    //! <!-- @@ end test lint list maintained by maint/add_warning @@ -->

    use super::*;

    use tor_rtmock::io::stream_pair;

    use tor_rtmock::simple_time::SimpleMockTimeProvider;

    use web_time_compat::{SystemTime, SystemTimeExt};

    use futures_await_test::async_test;

    // Basic decompression wrapper.

    async fn decomp_basic(

        encoding: Option<&str>,

        data: &[u8],

        maxlen: usize,

    ) -> (RequestResult<()>, Vec<u8>) {

        // We don't need to do anything fancy here, since we aren't simulating

        // a timeout.

        #[allow(deprecated)] // TODO #1885

        let mock_time = SimpleMockTimeProvider::from_wallclock(SystemTime::get());

        let mut output = Vec::new();

        let mut stream = match get_decoder(data, encoding, AnonymizedRequest::Direct) {

            Ok(s) => s,

            Err(e) => return (Err(e), output),

        };

        let r = read_and_decompress(&mock_time, &mut stream, maxlen, &mut output).await;

        (r, output)

    }

    #[async_test]

    async fn decompress_identity() -> RequestResult<()> {

        let mut text = Vec::new();

        for _ in 0..1000 {

            text.extend(b"This is a string with a nontrivial length that we'll use to make sure that the loop is executed more than once.");

        }

        let limit = 10 << 20;

        let (s, r) = decomp_basic(None, &text[..], limit).await;

        s?;

        assert_eq!(r, text);

        let (s, r) = decomp_basic(Some("identity"), &text[..], limit).await;

        s?;

        assert_eq!(r, text);

        // Try truncated result

        let limit = 100;

        let (s, r) = decomp_basic(Some("identity"), &text[..], limit).await;

        assert!(s.is_err());

        assert_eq!(r, &text[..100]);

        Ok(())

    }

    #[async_test]

    async fn decomp_zlib() -> RequestResult<()> {

        let compressed =

            hex::decode("789cf3cf4b5548cb2cce500829cf8730825253200ca79c52881c00e5970c88").unwrap();

        let limit = 10 << 20;

        let (s, r) = decomp_basic(Some("deflate"), &compressed, limit).await;

        s?;

        assert_eq!(r, b"One fish Two fish Red fish Blue fish");

        Ok(())

    }

    #[cfg(feature = "zstd")]

    #[async_test]

    async fn decomp_zstd() -> RequestResult<()> {

        let compressed = hex::decode("28b52ffd24250d0100c84f6e6520666973682054776f526564426c756520666973680a0200600c0e2509478352cb").unwrap();

        let limit = 10 << 20;

        let (s, r) = decomp_basic(Some("x-zstd"), &compressed, limit).await;

        s?;

        assert_eq!(r, b"One fish Two fish Red fish Blue fish\n");

        Ok(())

    }

    #[cfg(feature = "xz")]

    #[async_test]

    async fn decomp_xz() -> RequestResult<()> {

        // echo "One fish Two fish Red fish Blue fish" | xz -6 | xxd -p

        let compressed = hex::decode("fd377a585a000004e6d6b44604c02525210116000000000000000000bfdbca33e00024001d5d00279b88a202ca8612cfb3c19c87c34248a570451e4851d3323d34ab8000000000000901af64854c91f600014125281fe0821fb6f37d010000000004595a").unwrap();

        let limit = LZMA_DICT_MEM_LIMIT as usize;

        let (s, r) = decomp_basic(Some("x-tor-lzma"), &compressed, limit).await;

        s?;

        assert_eq!(r, b"One fish Two fish Red fish Blue fish\n");

        Ok(())

    }

    #[cfg(feature = "xz")]

    #[async_test]

    async fn decomp_xz_bad() -> RequestResult<()> {

        // Not so good at tiny files...

        let compressed = hex::decode("fd377a585a000004e6d6b446020021011c00000010cf58cce00024001d5d00279b88a202ca8612cfb3c19c87c34248a570451e4851d3323d34ab8000000000000901af64854c91f600013925d6ec06651fb6f37d010000000004595a").unwrap();

        let limit = 10 << 20;

        let (s, _) = decomp_basic(Some("x-tor-lzma"), &compressed, limit).await;

        assert!(matches!(s, Err(RequestError::IoError(_))));

        Ok(())

    }

    #[async_test]

    async fn decomp_unknown() {

        let compressed = hex::decode("28b52ffd24250d0100c84f6e6520666973682054776f526564426c756520666973680a0200600c0e2509478352cb").unwrap();

        let limit = 10 << 20;

        let (s, _r) = decomp_basic(Some("x-proprietary-rle"), &compressed, limit).await;

        assert!(matches!(s, Err(RequestError::ContentEncoding(_))));

    }

    #[async_test]

    async fn decomp_bad_data() {

        let compressed = b"This is not good zlib data";

        let limit = 10 << 20;

        let (s, _r) = decomp_basic(Some("deflate"), compressed, limit).await;

        // This should possibly be a different type in the future.

        assert!(matches!(s, Err(RequestError::IoError(_))));

    }

    #[test]

    fn headers_ok() -> RequestResult<()> {

        let text = b"HTTP/1.0 200 OK\r\nDate: ignored\r\nContent-Encoding: Waffles\r\n\r\n";

        let mut s = &text[..];

        let h = tor_rtcompat::test_with_one_runtime!(async |rt| read_headers(&rt, &mut s).await)?;

        assert_eq!(h.status, Some(200));

        assert_eq!(h.encoding.as_deref(), Some("Waffles"));

        // now try truncated

        let mut s = &text[..15];

        let h = tor_rtcompat::test_with_one_runtime!(async |rt| read_headers(&rt, &mut s).await);

        assert!(matches!(h, Err(RequestError::TruncatedHeaders)));

        // now try with no encoding.

        let text = b"HTTP/1.0 404 Not found\r\n\r\n";

        let mut s = &text[..];

        let h = tor_rtcompat::test_with_one_runtime!(async |rt| read_headers(&rt, &mut s).await)?;

        assert_eq!(h.status, Some(404));

        assert!(h.encoding.is_none());

        Ok(())

    }

    #[test]

    fn headers_bogus() {

        let text = b"HTTP/999.0 WHAT EVEN\r\n\r\n";

        let mut s = &text[..];

        let h = tor_rtcompat::test_with_one_runtime!(async |rt| read_headers(&rt, &mut s).await);

        assert!(h.is_err());

        assert!(matches!(h, Err(RequestError::HttparseError(_))));

    }

    /// Run a trivial download example with a response provided as a binary

    /// string.

    ///

    /// Return the directory response (if any) and the request as encoded (if

    /// any.)

    fn run_download_test<Req: request::Requestable>(

        req: Req,

        response: &[u8],

    ) -> (Result<DirResponse>, RequestResult<Vec<u8>>) {

        let (mut s1, s2) = stream_pair();

        let (mut s2_r, mut s2_w) = s2.split();

        tor_rtcompat::test_with_one_runtime!(|rt| async move {

            let rt2 = rt.clone();

            let (v1, v2, v3): (

                Result<DirResponse>,

                RequestResult<Vec<u8>>,

                RequestResult<()>,

            ) = futures::join!(

                async {

                    // Run the download function.

                    let r = send_request(&rt, &req, &mut s1, None).await;

                    s1.close().await.map_err(|error| {

                        Error::RequestFailed(RequestFailedError {

                            source: None,

                            error: error.into(),

                        })

                    })?;

                    r

                },

                async {

                    // Take the request from the client, and return it in "v2"

                    let mut v = Vec::new();

                    s2_r.read_to_end(&mut v).await?;

                    Ok(v)

                },

                async {

                    // Send back a response.

                    s2_w.write_all(response).await?;

                    // We wait a moment to give the other side time to notice it

                    // has data.

                    //

                    // (Tentative diagnosis: The `async-compress` crate seems to

                    // be behave differently depending on whether the "close"

                    // comes right after the incomplete data or whether it comes

                    // after a delay.  If there's a delay, it notices the

                    // truncated data and tells us about it. But when there's

                    // _no_delay, it treats the data as an error and doesn't

                    // tell our code.)

                    // TODO: sleeping in tests is not great.

                    rt2.sleep(Duration::from_millis(50)).await;

                    s2_w.close().await?;

                    Ok(())

                }

            );

            assert!(v3.is_ok());

            (v1, v2)

        })

    }

    #[test]

    fn test_send_request() -> RequestResult<()> {

        let req: request::MicrodescRequest = vec![[9; 32]].into_iter().collect();

        let (response, request) = run_download_test(

            req,

            b"HTTP/1.0 200 OK\r\n\r\nThis is where the descs would go.",

        );

        let request = request?;

        assert!(request[..].starts_with(

            b"GET /tor/micro/d/CQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQk HTTP/1.0\r\n"

        ));

        let response = response.unwrap();

        assert_eq!(response.status_code(), 200);

        assert!(!response.is_partial());

        assert!(response.error().is_none());

        assert!(response.source().is_none());

        let out_ref = response.output_unchecked();

        assert_eq!(out_ref, b"This is where the descs would go.");

        let out = response.into_output_unchecked();

        assert_eq!(&out, b"This is where the descs would go.");

        Ok(())

    }

    #[test]

    fn test_download_truncated() {

        // Request only one md, so "partial ok" will not be set.

        let req: request::MicrodescRequest = vec![[9; 32]].into_iter().collect();

        let mut response_text: Vec<u8> =

            (*b"HTTP/1.0 200 OK\r\nContent-Encoding: deflate\r\n\r\n").into();

        // "One fish two fish" as above twice, but truncated the second time

        response_text.extend(

            hex::decode("789cf3cf4b5548cb2cce500829cf8730825253200ca79c52881c00e5970c88").unwrap(),

        );

        response_text.extend(

            hex::decode("789cf3cf4b5548cb2cce500829cf8730825253200ca79c52881c00e5").unwrap(),

        );

        let (response, request) = run_download_test(req, &response_text);

        assert!(request.is_ok());

        assert!(response.is_err()); // The whole download should fail, since partial_ok wasn't set.

        // request two microdescs, so "partial_ok" will be set.

        let req: request::MicrodescRequest = vec![[9; 32]; 2].into_iter().collect();

        let (response, request) = run_download_test(req, &response_text);

        assert!(request.is_ok());

        let response = response.unwrap();

        assert_eq!(response.status_code(), 200);

        assert!(response.error().is_some());

        assert!(response.is_partial());

        assert!(response.output_unchecked().len() < 37 * 2);

        assert!(response.output_unchecked().starts_with(b"One fish"));

    }

    #[test]

    fn test_404() {

        let req: request::MicrodescRequest = vec![[9; 32]].into_iter().collect();

        let response_text = b"HTTP/1.0 418 I'm a teapot\r\n\r\n";

        let (response, _request) = run_download_test(req, response_text);

        assert_eq!(response.unwrap().status_code(), 418);

    }

    #[test]

    fn test_headers_truncated() {

        let req: request::MicrodescRequest = vec![[9; 32]].into_iter().collect();

        let response_text = b"HTTP/1.0 404 truncation happens here\r\n";

        let (response, _request) = run_download_test(req, response_text);

        assert!(matches!(

            response,

            Err(Error::RequestFailed(RequestFailedError {

                error: RequestError::TruncatedHeaders,

                ..

            }))

        ));

        // Try a completely empty response.

        let req: request::MicrodescRequest = vec![[9; 32]].into_iter().collect();

        let response_text = b"";

        let (response, _request) = run_download_test(req, response_text);

        assert!(matches!(

            response,

            Err(Error::RequestFailed(RequestFailedError {

                error: RequestError::TruncatedHeaders,

                ..

            }))

        ));

    }

    #[test]

    fn test_headers_too_long() {

        let req: request::MicrodescRequest = vec![[9; 32]].into_iter().collect();

        let mut response_text: Vec<u8> = (*b"HTTP/1.0 418 I'm a teapot\r\nX-Too-Many-As: ").into();

        response_text.resize(16384, b'A');

        let (response, _request) = run_download_test(req, &response_text);

        assert!(response.as_ref().unwrap_err().should_retire_circ());

        assert!(matches!(

            response,

            Err(Error::RequestFailed(RequestFailedError {

                error: RequestError::HeadersTooLong(_),

                ..

            }))

        ));

    }

    #[test]

    fn test_bad_utf8() {

        let req: request::MicrodescRequest = vec![[9; 32]].into_iter().collect();

        let faulty_utf8 = vec![0, 159, 146, 150];

        let mut response_text: Vec<u8> = b"HTTP/1.0 200 OK\r\n\r\n".into();

        response_text.extend(faulty_utf8);

        let (response, _request) = run_download_test(req, &response_text);

        assert!(matches!(

            response.unwrap().into_output_string().unwrap_err(),

            RequestFailedError {

                error: RequestError::Utf8Encoding(_),

                ..

            }

        ));

    }

}