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libreddit/src/server.rs

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use brotli::enc::{BrotliCompress, BrotliEncoderParams};
use cached::proc_macro::cached;
use cookie::Cookie;
use core::f64;
use futures_lite::{future::Boxed, Future, FutureExt};
use hyper::{
body,
body::HttpBody,
header,
service::{make_service_fn, service_fn},
HeaderMap,
};
use hyper::{Body, Method, Request, Response, Server as HyperServer};
use libflate::gzip;
use route_recognizer::{Params, Router};
use std::{
cmp::Ordering,
io,
pin::Pin,
result::Result,
str::{from_utf8, Split},
string::ToString,
};
use time::Duration;
use crate::dbg_msg;
type BoxResponse = Pin<Box<dyn Future<Output = Result<Response<Body>, String>> + Send>>;
/// Compressors for the response Body, in ascending order of preference.
#[derive(Copy, Clone, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
enum CompressionType {
Passthrough,
Gzip,
Brotli,
}
/// All browsers support gzip, so if we are given `Accept-Encoding: *`, deliver
/// gzipped-content.
///
/// Brotli would be nice universally, but Safari (iOS, iPhone, macOS) reportedly
/// doesn't support it yet.
const DEFAULT_COMPRESSOR: CompressionType = CompressionType::Gzip;
impl CompressionType {
/// Returns a `CompressionType` given a content coding
/// in [RFC 7231](https://datatracker.ietf.org/doc/html/rfc7231#section-5.3.4)
/// format.
fn parse(s: &str) -> Option<CompressionType> {
let c = match s {
// Compressors we support.
"gzip" => CompressionType::Gzip,
"br" => CompressionType::Brotli,
// The wildcard means that we can choose whatever
// compression we prefer. In this case, use the
// default.
"*" => DEFAULT_COMPRESSOR,
// Compressor not supported.
_ => return None,
};
Some(c)
}
}
impl ToString for CompressionType {
fn to_string(&self) -> String {
match self {
CompressionType::Gzip => "gzip".to_string(),
CompressionType::Brotli => "br".to_string(),
_ => String::new(),
}
}
}
pub struct Route<'a> {
router: &'a mut Router<fn(Request<Body>) -> BoxResponse>,
path: String,
}
pub struct Server {
pub default_headers: HeaderMap,
router: Router<fn(Request<Body>) -> BoxResponse>,
}
#[macro_export]
macro_rules! headers(
{ $($key:expr => $value:expr),+ } => {
{
let mut m = hyper::HeaderMap::new();
$(
if let Ok(val) = hyper::header::HeaderValue::from_str($value) {
m.insert($key, val);
}
)+
m
}
};
);
pub trait RequestExt {
fn params(&self) -> Params;
fn param(&self, name: &str) -> Option<String>;
fn set_params(&mut self, params: Params) -> Option<Params>;
fn cookies(&self) -> Vec<Cookie>;
fn cookie(&self, name: &str) -> Option<Cookie>;
}
pub trait ResponseExt {
fn cookies(&self) -> Vec<Cookie>;
fn insert_cookie(&mut self, cookie: Cookie);
fn remove_cookie(&mut self, name: String);
}
impl RequestExt for Request<Body> {
fn params(&self) -> Params {
self.extensions().get::<Params>().unwrap_or(&Params::new()).clone()
// self.extensions()
// .get::<RequestMeta>()
// .and_then(|meta| meta.route_params())
// .expect("Routerify: No RouteParams added while processing request")
}
fn param(&self, name: &str) -> Option<String> {
self.params().find(name).map(std::borrow::ToOwned::to_owned)
}
fn set_params(&mut self, params: Params) -> Option<Params> {
self.extensions_mut().insert(params)
}
fn cookies(&self) -> Vec<Cookie> {
self.headers().get("Cookie").map_or(Vec::new(), |header| {
header
.to_str()
.unwrap_or_default()
.split("; ")
.map(|cookie| Cookie::parse(cookie).unwrap_or_else(|_| Cookie::named("")))
.collect()
})
}
fn cookie(&self, name: &str) -> Option<Cookie> {
self.cookies().into_iter().find(|c| c.name() == name)
}
}
impl ResponseExt for Response<Body> {
fn cookies(&self) -> Vec<Cookie> {
self.headers().get("Cookie").map_or(Vec::new(), |header| {
header
.to_str()
.unwrap_or_default()
.split("; ")
.map(|cookie| Cookie::parse(cookie).unwrap_or_else(|_| Cookie::named("")))
.collect()
})
}
fn insert_cookie(&mut self, cookie: Cookie) {
if let Ok(val) = header::HeaderValue::from_str(&cookie.to_string()) {
self.headers_mut().append("Set-Cookie", val);
}
}
fn remove_cookie(&mut self, name: String) {
let mut cookie = Cookie::named(name);
cookie.set_path("/");
cookie.set_max_age(Duration::seconds(1));
if let Ok(val) = header::HeaderValue::from_str(&cookie.to_string()) {
self.headers_mut().append("Set-Cookie", val);
}
}
}
impl Route<'_> {
fn method(&mut self, method: Method, dest: fn(Request<Body>) -> BoxResponse) -> &mut Self {
self.router.add(&format!("/{}{}", method.as_str(), self.path), dest);
self
}
/// Add an endpoint for `GET` requests
pub fn get(&mut self, dest: fn(Request<Body>) -> BoxResponse) -> &mut Self {
self.method(Method::GET, dest)
}
/// Add an endpoint for `POST` requests
pub fn post(&mut self, dest: fn(Request<Body>) -> BoxResponse) -> &mut Self {
self.method(Method::POST, dest)
}
}
impl Server {
pub fn new() -> Self {
Server {
default_headers: HeaderMap::new(),
router: Router::new(),
}
}
pub fn at(&mut self, path: &str) -> Route {
Route {
path: path.to_owned(),
router: &mut self.router,
}
}
pub fn listen(self, addr: String) -> Boxed<Result<(), hyper::Error>> {
let make_svc = make_service_fn(move |_conn| {
// For correct borrowing, these values need to be borrowed
let router = self.router.clone();
let default_headers = self.default_headers.clone();
// This is the `Service` that will handle the connection.
// `service_fn` is a helper to convert a function that
// returns a Response into a `Service`.
// let shared_router = router.clone();
async move {
Ok::<_, String>(service_fn(move |req: Request<Body>| {
let req_headers = req.headers().clone();
let def_headers = default_headers.clone();
// Remove double slashes and decode encoded slashes
let mut path = req.uri().path().replace("//", "/").replace("%2F", "/");
// Remove trailing slashes
if path != "/" && path.ends_with('/') {
path.pop();
}
// Match the visited path with an added route
match router.recognize(&format!("/{}{}", req.method().as_str(), path)) {
// If a route was configured for this path
Ok(found) => {
let mut parammed = req;
parammed.set_params(found.params().clone());
// Run the route's function
let func = (found.handler().to_owned().to_owned())(parammed);
async move {
match func.await {
Ok(mut res) => {
res.headers_mut().extend(def_headers);
let _ = compress_response(&req_headers, &mut res).await;
Ok(res)
}
Err(msg) => new_boilerplate(def_headers, req_headers, 500, Body::from(msg)).await,
}
}
.boxed()
}
// If there was a routing error
Err(e) => new_boilerplate(def_headers, req_headers, 404, e.into()).boxed(),
}
}))
}
});
// Build SocketAddr from provided address
let address = &addr.parse().unwrap_or_else(|_| panic!("Cannot parse {} as address (example format: 0.0.0.0:8080)", addr));
// Bind server to address specified above. Gracefully shut down if CTRL+C is pressed
let server = HyperServer::bind(address).serve(make_svc).with_graceful_shutdown(async {
// Wait for the CTRL+C signal
tokio::signal::ctrl_c().await.expect("Failed to install CTRL+C signal handler");
});
server.boxed()
}
}
/// Create a boilerplate Response for error conditions. This response will be
/// compressed if requested by client.
async fn new_boilerplate(
default_headers: HeaderMap<header::HeaderValue>,
req_headers: HeaderMap<header::HeaderValue>,
status: u16,
body: Body,
) -> Result<Response<Body>, String> {
match Response::builder().status(status).body(body) {
Ok(mut res) => {
let _ = compress_response(&req_headers, &mut res).await;
res.headers_mut().extend(default_headers.clone());
Ok(res)
}
Err(msg) => Err(msg.to_string()),
}
}
/// Determines the desired compressor based on the Accept-Encoding header.
///
/// This function will honor the [q-value](https://developer.mozilla.org/en-US/docs/Glossary/Quality_values)
/// for each compressor. The q-value is an optional parameter, a decimal value
/// on \[0..1\], to order the compressors by preference. An Accept-Encoding value
/// with no q-values is also accepted.
///
/// Here are [examples](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Accept-Encoding#examples)
/// of valid Accept-Encoding headers.
///
/// ```http
/// Accept-Encoding: gzip
/// Accept-Encoding: gzip, compress, br
/// Accept-Encoding: br;q=1.0, gzip;q=0.8, *;q=0.1
/// ```
#[cached]
fn determine_compressor(accept_encoding: String) -> Option<CompressionType> {
if accept_encoding.is_empty() {
return None;
};
// Keep track of the compressor candidate based on both the client's
// preference and our own. Concrete examples:
//
// 1. "Accept-Encoding: gzip, br" => assuming we like brotli more than
// gzip, and the browser supports brotli, we choose brotli
//
// 2. "Accept-Encoding: gzip;q=0.8, br;q=0.3" => the client has stated a
// preference for gzip over brotli, so we choose gzip
//
// To do this, we need to define a struct which contains the requested
// requested compressor (abstracted as a CompressionType enum) and the
// q-value. If no q-value is defined for the compressor, we assume one of
// 1.0. We first compare compressor candidates by comparing q-values, and
// then CompressionTypes. We keep track of whatever is the greatest per our
// ordering.
struct CompressorCandidate {
alg: CompressionType,
q: f64,
}
impl Ord for CompressorCandidate {
fn cmp(&self, other: &Self) -> Ordering {
// Compare q-values. Break ties with the
// CompressionType values.
match self.q.total_cmp(&other.q) {
Ordering::Equal => self.alg.cmp(&other.alg),
ord => ord,
}
}
}
impl PartialOrd for CompressorCandidate {
fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
// Guard against NAN, both on our end and on the other.
if self.q.is_nan() || other.q.is_nan() {
return None;
};
// f64 and CompressionType are ordered, except in the case
// where the f64 is NAN (which we checked against), so we
// can safely return a Some here.
Some(self.cmp(other))
}
}
impl PartialEq for CompressorCandidate {
fn eq(&self, other: &Self) -> bool {
(self.q == other.q) && (self.alg == other.alg)
}
}
impl Eq for CompressorCandidate {}
// This is the current candidate.
//
// Assmume no candidate so far. We do this by assigning the sentinel value
// of negative infinity to the q-value. If this value is negative infinity,
// that means there was no viable compressor candidate.
let mut cur_candidate = CompressorCandidate {
alg: CompressionType::Passthrough,
q: f64::NEG_INFINITY,
};
// This loop reads the requested compressors and keeps track of whichever
// one has the highest priority per our heuristic.
for val in accept_encoding.split(',') {
let mut q: f64 = 1.0;
// The compressor and q-value (if the latter is defined)
// will be delimited by semicolons.
let mut spl: Split<char> = val.split(';');
// Get the compressor. For example, in
// gzip;q=0.8
// this grabs "gzip" in the string. It
// will further validate the compressor against the
// list of those we support. If it is not supported,
// we move onto the next one.
let compressor: CompressionType = match spl.next() {
// CompressionType::parse will return the appropriate enum given
// a string. For example, it will return CompressionType::Gzip
// when given "gzip".
Some(s) => match CompressionType::parse(s.trim()) {
Some(candidate) => candidate,
// We don't support the requested compression algorithm.
None => continue,
},
// We should never get here, but I'm paranoid.
None => continue,
};
// Get the q-value. This might not be defined, in which case assume
// 1.0.
if let Some(s) = spl.next() {
if !(s.len() > 2 && s.starts_with("q=")) {
// If the q-value is malformed, the header is malformed, so
// abort.
return None;
}
match s[2..].parse::<f64>() {
Ok(val) => {
if (0.0..=1.0).contains(&val) {
q = val;
} else {
// If the value is outside [0..1], header is malformed.
// Abort.
return None;
};
}
Err(_) => {
// If this isn't a f64, then assume a malformed header
// value and abort.
return None;
}
}
};
// If new_candidate > cur_candidate, make new_candidate the new
// cur_candidate. But do this safely! It is very possible that
// someone gave us the string "NAN", which (&str).parse::<f64>
// will happily translate to f64::NAN.
let new_candidate = CompressorCandidate { alg: compressor, q };
if let Some(ord) = new_candidate.partial_cmp(&cur_candidate) {
if ord == Ordering::Greater {
cur_candidate = new_candidate;
}
};
}
if cur_candidate.q != f64::NEG_INFINITY {
Some(cur_candidate.alg)
} else {
None
}
}
/// Compress the response body, if possible or desirable. The Body will be
/// compressed in place, and a new header Content-Encoding will be set
/// indicating the compression algorithm.
///
/// This function deems Body eligible compression if and only if the following
/// conditions are met:
///
/// 1. the HTTP client requests a compression encoding in the Content-Encoding
/// header (hence the need for the req_headers);
///
/// 2. the content encoding corresponds to a compression algorithm we support;
///
/// 3. the Media type in the Content-Type response header is text with any
/// subtype (e.g. text/plain) or application/json.
///
/// compress_response returns Ok on successful compression, or if not all three
/// conditions above are met. It returns Err if there was a problem decoding
/// any header in either req_headers or res, but res will remain intact.
///
/// This function logs errors to stderr, but only in debug mode. No information
/// is logged in release builds.
async fn compress_response(req_headers: &HeaderMap<header::HeaderValue>, res: &mut Response<Body>) -> Result<(), String> {
// Check if the data is eligible for compression.
if let Some(hdr) = res.headers().get(header::CONTENT_TYPE) {
match from_utf8(hdr.as_bytes()) {
Ok(val) => {
let s = val.to_string();
// TODO: better determination of what is eligible for compression
if !(s.starts_with("text/") || s.starts_with("application/json")) {
return Ok(());
};
}
Err(e) => {
dbg_msg!(e);
return Err(e.to_string());
}
};
} else {
// Response declares no Content-Type. Assume for simplicity that it
// cannot be compressed.
return Ok(());
};
// Don't bother if the size of the size of the response body will fit
// within an IP frame (less the bytes that make up the TCP/IP and HTTP
// headers).
if res.body().size_hint().lower() < 1452 {
return Ok(());
};
// Check to see which compressor is requested, and if we can use it.
let accept_encoding: String = match req_headers.get(header::ACCEPT_ENCODING) {
None => return Ok(()), // Client requested no compression.
Some(hdr) => match String::from_utf8(hdr.as_bytes().into()) {
Ok(val) => val,
#[cfg(debug_assertions)]
Err(e) => {
dbg_msg!(e);
return Ok(());
}
#[cfg(not(debug_assertions))]
Err(_) => return Ok(()),
},
};
let compressor: CompressionType = match determine_compressor(accept_encoding) {
Some(c) => c,
None => return Ok(()),
};
// Get the body from the response.
let body_bytes: Vec<u8> = match body::to_bytes(res.body_mut()).await {
Ok(b) => b.to_vec(),
Err(e) => {
dbg_msg!(e);
return Err(e.to_string());
}
};
// Compress!
match compress_body(compressor, body_bytes) {
Ok(compressed) => {
// We get here iff the compression was successful. Replace the body
// with the compressed payload, and add the appropriate
// Content-Encoding header in the response.
res.headers_mut().insert(header::CONTENT_ENCODING, compressor.to_string().parse().unwrap());
*(res.body_mut()) = Body::from(compressed);
}
Err(e) => return Err(e),
}
Ok(())
}
/// Compresses a `Vec<u8>` given a [`CompressionType`].
///
/// This is a helper function for [`compress_response`] and should not be
/// called directly.
// I've chosen a TTL of 600 (== 10 minutes) since compression is
// computationally expensive and we don't want to be doing it often. This is
// larger than client::json's TTL, but that's okay, because if client::json
// returns a new serde_json::Value, body_bytes changes, so this function will
// execute again.
#[cached(size = 100, time = 600, result = true)]
fn compress_body(compressor: CompressionType, body_bytes: Vec<u8>) -> Result<Vec<u8>, String> {
// io::Cursor implements io::Read, required for our encoders.
let mut reader = io::Cursor::new(body_bytes);
let compressed: Vec<u8> = match compressor {
CompressionType::Gzip => {
let mut gz: gzip::Encoder<Vec<u8>> = match gzip::Encoder::new(Vec::new()) {
Ok(gz) => gz,
Err(e) => {
dbg_msg!(e);
return Err(e.to_string());
}
};
match io::copy(&mut reader, &mut gz) {
Ok(_) => match gz.finish().into_result() {
Ok(compressed) => compressed,
Err(e) => {
dbg_msg!(e);
return Err(e.to_string());
}
},
Err(e) => {
dbg_msg!(e);
return Err(e.to_string());
}
}
}
CompressionType::Brotli => {
// We may want to make the compression parameters configurable
// in the future. For now, the defaults are sufficient.
let brotli_params = BrotliEncoderParams::default();
let mut compressed = Vec::<u8>::new();
match BrotliCompress(&mut reader, &mut compressed, &brotli_params) {
Ok(_) => compressed,
Err(e) => {
dbg_msg!(e);
return Err(e.to_string());
}
}
}
// This arm is for any requested compressor for which we don't yet
// have an implementation.
_ => {
let msg = "unsupported compressor".to_string();
return Err(msg);
}
};
Ok(compressed)
}
#[cfg(test)]
mod tests {
use super::*;
use brotli::Decompressor as BrotliDecompressor;
use futures_lite::future::block_on;
use lipsum::lipsum;
use std::{boxed::Box, io};
#[test]
fn test_determine_compressor() {
// Single compressor given.
assert_eq!(determine_compressor("unsupported".to_string()), None);
assert_eq!(determine_compressor("gzip".to_string()), Some(CompressionType::Gzip));
assert_eq!(determine_compressor("*".to_string()), Some(DEFAULT_COMPRESSOR));
// Multiple compressors.
assert_eq!(determine_compressor("gzip, br".to_string()), Some(CompressionType::Brotli));
assert_eq!(determine_compressor("gzip;q=0.8, br;q=0.3".to_string()), Some(CompressionType::Gzip));
assert_eq!(determine_compressor("br, gzip".to_string()), Some(CompressionType::Brotli));
assert_eq!(determine_compressor("br;q=0.3, gzip;q=0.4".to_string()), Some(CompressionType::Gzip));
// Invalid q-values.
assert_eq!(determine_compressor("gzip;q=NAN".to_string()), None);
}
#[test]
fn test_compress_response() {
// This macro generates an Accept-Encoding header value given any number of
// compressors.
macro_rules! ae_gen {
($x:expr) => {
$x.to_string().as_str()
};
($x:expr, $($y:expr),+) => {
format!("{}, {}", $x.to_string(), ae_gen!($($y),+)).as_str()
};
}
for accept_encoding in [
"*",
ae_gen!(CompressionType::Gzip),
ae_gen!(CompressionType::Brotli, CompressionType::Gzip),
ae_gen!(CompressionType::Brotli),
] {
// Determine what the expected encoding should be based on both the
// specific encodings we accept.
let expected_encoding: CompressionType = match determine_compressor(accept_encoding.to_string()) {
Some(s) => s,
None => panic!("determine_compressor(accept_encoding.to_string()) => None"),
};
// Build headers with our Accept-Encoding.
let mut req_headers = HeaderMap::new();
req_headers.insert(header::ACCEPT_ENCODING, header::HeaderValue::from_str(accept_encoding).unwrap());
// Build test response.
let lorem_ipsum: String = lipsum(10000);
let expected_lorem_ipsum = Vec::<u8>::from(lorem_ipsum.as_str());
let mut res = Response::builder()
.status(200)
.header(header::CONTENT_TYPE, "text/plain")
.body(Body::from(lorem_ipsum))
.unwrap();
// Perform the compression.
if let Err(e) = block_on(compress_response(&req_headers, &mut res)) {
panic!("compress_response(&req_headers, &mut res) => Err(\"{}\")", e);
};
// If the content was compressed, we expect the Content-Encoding
// header to be modified.
assert_eq!(
res
.headers()
.get(header::CONTENT_ENCODING)
.unwrap_or_else(|| panic!("missing content-encoding header"))
.to_str()
.unwrap_or_else(|_| panic!("failed to convert Content-Encoding header::HeaderValue to String")),
expected_encoding.to_string()
);
// Decompress body and make sure it's equal to what we started
// with.
//
// In the case of no compression, just make sure the "new" body in
// the Response is the same as what with which we start.
let body_vec = match block_on(body::to_bytes(res.body_mut())) {
Ok(b) => b.to_vec(),
Err(e) => panic!("{}", e),
};
if expected_encoding == CompressionType::Passthrough {
assert!(body_vec.eq(&expected_lorem_ipsum));
continue;
}
// This provides an io::Read for the underlying body.
let mut body_cursor: io::Cursor<Vec<u8>> = io::Cursor::new(body_vec);
// Match the appropriate decompresor for the given
// expected_encoding.
let mut decoder: Box<dyn io::Read> = match expected_encoding {
CompressionType::Gzip => match gzip::Decoder::new(&mut body_cursor) {
Ok(dgz) => Box::new(dgz),
Err(e) => panic!("{}", e),
},
CompressionType::Brotli => Box::new(BrotliDecompressor::new(body_cursor, expected_lorem_ipsum.len())),
_ => panic!("no decompressor for {}", expected_encoding.to_string()),
};
let mut decompressed = Vec::<u8>::new();
if let Err(e) = io::copy(&mut decoder, &mut decompressed) {
panic!("{}", e);
};
assert!(decompressed.eq(&expected_lorem_ipsum));
}
}
}
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