From a2cbe9dc54690df833894eda498124865604b5f4 Mon Sep 17 00:00:00 2001
From: Jake Hillion <jake@hillion.co.uk>
Date: Mon, 23 May 2022 07:07:18 +0100
Subject: [PATCH 1/3] no-op tls handler

---
 README.md              | 10 ++++++
 examples/tls/main.rs   | 82 +++++++++++++++++++++++++++++++++++++-----
 examples/tls/spec.json | 48 ++++++++++++++++++++++---
 examples/tls/tls.rs    | 12 +++++++
 4 files changed, 140 insertions(+), 12 deletions(-)
 create mode 100644 examples/tls/tls.rs

diff --git a/README.md b/README.md
index c29320e..4ba51d8 100644
--- a/README.md
+++ b/README.md
@@ -32,6 +32,16 @@ To run this example:
     cargo build --example pipes
     target/debug/clone-shim -s examples/pipes/spec.json target/debug/examples/pipes
 
+### examples/pipes
+
+The pipes example shows some of the power of the shim by using pipes. The process "pipe_sender" sends two messages down a pipe that it's given by the shim. These two messages each spawn a completely isolated process, "pipe_receiver", that receives that message.
+
+To run this example:
+
+    cargo build
+    cargo build --example tls
+    target/debug/clone-shim -s examples/tls/spec.json target/debug/examples/tls
+
 ## Debugging the shim
 
 The shim can be debugged as with most processes, but it is exceptionally forky. Breaking before a clone in `rust-gdb` then running `set follow-fork-mode child` is often necessary. The best approach is to go in with a plan of attack.
diff --git a/examples/tls/main.rs b/examples/tls/main.rs
index 0087586..dda71b4 100644
--- a/examples/tls/main.rs
+++ b/examples/tls/main.rs
@@ -1,4 +1,5 @@
 mod http;
+mod tls;
 
 use std::fs::File;
 use std::net::{TcpListener, TcpStream};
@@ -7,6 +8,7 @@ fn main() {
     match std::env::args().next() {
         Some(s) => match s.as_str() {
             "connection_listener" => connection_listener_entrypoint(),
+            "tls_handler" => tls_handler_entrypoint(),
             "http_handler" => http_handler_entrypoint(),
 
             _ => unimplemented!(),
@@ -24,12 +26,12 @@ fn connection_listener_entrypoint() {
 
     let _entrypoint = args.next();
 
-    let http_handler_trigger = args.next();
-    let http_handler_trigger: RawFd = http_handler_trigger
-        .expect("request handler required")
+    let tls_handler_trigger = args.next();
+    let tls_handler_trigger: RawFd = tls_handler_trigger
+        .expect("tls handler trigger required")
         .parse()
-        .expect("tcp listener should be a file descriptor");
-    let http_handler_trigger = unsafe { File::from_raw_fd(http_handler_trigger) };
+        .expect("tls handler trigger should be a file descriptor");
+    let tls_handler_trigger = unsafe { File::from_raw_fd(tls_handler_trigger) };
 
     let tcp_listener = args.next();
     let tcp_listener: RawFd = tcp_listener
@@ -39,7 +41,7 @@ fn connection_listener_entrypoint() {
     let tcp_listener = unsafe { TcpListener::from_raw_fd(tcp_listener) };
 
     // actual function body
-    fn connection_listener(http_handler_trigger: File, tcp_listener: TcpListener) -> i32 {
+    fn connection_listener(tls_handler_trigger: File, tcp_listener: TcpListener) -> i32 {
         println!("connection_listener entered");
 
         // handle incoming connections
@@ -53,14 +55,78 @@ fn connection_listener_entrypoint() {
             };
 
             println!("received a new connection");
-            http_handler(&http_handler_trigger, stream);
+            tls_handler(&tls_handler_trigger, stream);
         }
 
         exitcode::OK
     }
 
     // run function
-    std::process::exit(connection_listener(http_handler_trigger, tcp_listener));
+    std::process::exit(connection_listener(tls_handler_trigger, tcp_listener));
+}
+
+fn tls_handler(trigger_socket: &File, stream: TcpStream) {
+    // imports
+    use nix::sys::socket::{sendmsg, ControlMessage, MsgFlags};
+    use std::os::unix::io::AsRawFd;
+
+    // send file descriptor(s)
+    let sockfd = trigger_socket.as_raw_fd();
+    let fds = [stream.as_raw_fd()];
+
+    sendmsg::<()>(
+        sockfd,
+        &[],
+        &[ControlMessage::ScmRights(&fds)],
+        MsgFlags::empty(),
+        None,
+    )
+    .unwrap();
+}
+
+fn tls_handler_entrypoint() {
+    // imports
+    use std::os::unix::io::{FromRawFd, RawFd};
+
+    // argument parsing
+    let mut args = std::env::args();
+
+    let _entrypoint = args.next();
+
+    let http_handler_trigger = args.next();
+    let http_handler_trigger: RawFd = http_handler_trigger
+        .expect("http handler trigger required")
+        .parse()
+        .expect("http handler trigger should be a file descriptor");
+    let http_handler_trigger = unsafe { File::from_raw_fd(http_handler_trigger) };
+
+    let tls_cert_file = args.next();
+    let tls_cert_file: RawFd = tls_cert_file
+        .expect("tls cert file required")
+        .parse()
+        .expect("tls cert file should be a file descriptor");
+    let tls_cert_file = unsafe { File::from_raw_fd(tls_cert_file) };
+
+    let tls_key_file = args.next();
+    let tls_key_file: RawFd = tls_key_file
+        .expect("tls key file required")
+        .parse()
+        .expect("tls key file should be a file descriptor");
+    let tls_key_file = unsafe { File::from_raw_fd(tls_key_file) };
+
+    let stream = args.next();
+    let stream: RawFd = stream
+        .expect("request stream required")
+        .parse()
+        .expect("request stream should be a file descriptor");
+    let stream = unsafe { TcpStream::from_raw_fd(stream) };
+
+    std::process::exit(tls::handler(
+        http_handler_trigger,
+        tls_cert_file,
+        tls_key_file,
+        stream,
+    ));
 }
 
 fn http_handler(trigger_socket: &File, stream: TcpStream) {
diff --git a/examples/tls/spec.json b/examples/tls/spec.json
index 6a4817f..72bd86d 100644
--- a/examples/tls/spec.json
+++ b/examples/tls/spec.json
@@ -1,6 +1,44 @@
 {
     "entrypoints": {
         "connection_listener": {
+            "args": [
+                "Entrypoint",
+                {
+                    "FileSocket": {
+                        "Tx": "tls"
+                    }
+                },
+                {
+                    "TcpListener": {
+                        "addr": "0.0.0.0:8443"
+                    }
+                }
+            ],
+            "environment": [
+                {
+                    "Filesystem": {
+                        "host_path": "/lib/x86_64-linux-gnu/libgcc_s.so.1",
+                        "environment_path": "/lib/libgcc_s.so.1"
+                    }
+                },
+                {
+                    "Filesystem": {
+                        "host_path": "/lib/x86_64-linux-gnu/libc.so.6",
+                        "environment_path": "/lib/libc.so.6"
+                    }
+                },
+                {
+                    "Filesystem": {
+                        "host_path": "/lib64/ld-linux-x86-64.so.2",
+                        "environment_path": "/lib64/ld-linux-x86-64.so.2"
+                    }
+                }
+            ]
+        },
+        "tls_handler": {
+            "trigger": {
+                "FileSocket": "tls"
+            },
             "args": [
                 "Entrypoint",
                 {
@@ -9,10 +47,12 @@
                     }
                 },
                 {
-                    "TcpListener": {
-                        "addr": "0.0.0.0:8443"
-                    }
-                }
+                    "File": "/etc/ssl/certs/example.com.pem"
+                },
+                {
+                    "File": "/etc/ssl/private/example.com.key"
+                },
+                "Trigger"
             ],
             "environment": [
                 {
diff --git a/examples/tls/tls.rs b/examples/tls/tls.rs
new file mode 100644
index 0000000..74bf5aa
--- /dev/null
+++ b/examples/tls/tls.rs
@@ -0,0 +1,12 @@
+use std::fs::File;
+use std::net::TcpStream;
+
+pub(crate) fn handler(
+    http_trigger_socket: File,
+    _cert: File,
+    _key: File,
+    stream: TcpStream,
+) -> i32 {
+    super::http_handler(&http_trigger_socket, stream);
+    exitcode::OK
+}
-- 
2.46.0


From 20c2f8d5f73d003e3038aa2515c8c8758c6bfe5b Mon Sep 17 00:00:00 2001
From: Jake Hillion <jake@hillion.co.uk>
Date: Mon, 23 May 2022 18:26:55 +0100
Subject: [PATCH 2/3] forward tls handler

---
 examples/tls/http.rs |  4 +--
 examples/tls/main.rs |  5 +--
 examples/tls/tls.rs  | 83 ++++++++++++++++++++++++++++++++++++++++++--
 3 files changed, 86 insertions(+), 6 deletions(-)

diff --git a/examples/tls/http.rs b/examples/tls/http.rs
index 0688f37..82c6e52 100644
--- a/examples/tls/http.rs
+++ b/examples/tls/http.rs
@@ -1,9 +1,9 @@
 use std::fs;
 use std::io::{Read, Write};
-use std::net::TcpStream;
+use std::os::unix::net::UnixStream;
 use std::path::PathBuf;
 
-pub(super) fn handler(mut stream: TcpStream) -> i32 {
+pub(super) fn handler(mut stream: UnixStream) -> i32 {
     println!("entered http handler");
 
     let mut buf = Vec::new();
diff --git a/examples/tls/main.rs b/examples/tls/main.rs
index dda71b4..94b75f0 100644
--- a/examples/tls/main.rs
+++ b/examples/tls/main.rs
@@ -3,6 +3,7 @@ mod tls;
 
 use std::fs::File;
 use std::net::{TcpListener, TcpStream};
+use std::os::unix::net::UnixStream;
 
 fn main() {
     match std::env::args().next() {
@@ -129,7 +130,7 @@ fn tls_handler_entrypoint() {
     ));
 }
 
-fn http_handler(trigger_socket: &File, stream: TcpStream) {
+fn http_handler(trigger_socket: &File, stream: UnixStream) {
     // imports
     use nix::sys::socket::{sendmsg, ControlMessage, MsgFlags};
     use std::os::unix::io::AsRawFd;
@@ -162,7 +163,7 @@ fn http_handler_entrypoint() {
         .expect("request stream required")
         .parse()
         .expect("request stream should be a file descriptor");
-    let stream = unsafe { TcpStream::from_raw_fd(stream) };
+    let stream = unsafe { UnixStream::from_raw_fd(stream) };
 
     std::process::exit(http::handler(stream));
 }
diff --git a/examples/tls/tls.rs b/examples/tls/tls.rs
index 74bf5aa..62dfd2c 100644
--- a/examples/tls/tls.rs
+++ b/examples/tls/tls.rs
@@ -1,12 +1,91 @@
 use std::fs::File;
+use std::io::{self, ErrorKind, Read, Write};
 use std::net::TcpStream;
+use std::os::unix::io::AsRawFd;
+use std::os::unix::net::UnixStream;
+
+use nix::poll::{poll, PollFd, PollFlags};
+
+const BUFFER_SIZE: usize = 4096;
 
 pub(crate) fn handler(
     http_trigger_socket: File,
     _cert: File,
     _key: File,
-    stream: TcpStream,
+    mut stream: TcpStream,
 ) -> i32 {
-    super::http_handler(&http_trigger_socket, stream);
+    let (mut socket, far_socket) = UnixStream::pair().unwrap();
+
+    super::http_handler(&http_trigger_socket, far_socket);
+
+    stream.set_nonblocking(true).unwrap();
+    socket.set_nonblocking(true).unwrap();
+
+    let mut to_poll = [
+        PollFd::new(stream.as_raw_fd(), PollFlags::POLLIN),
+        PollFd::new(socket.as_raw_fd(), PollFlags::POLLIN),
+    ];
+
+    loop {
+        println!("starting polling");
+        poll(&mut to_poll, -1).unwrap();
+
+        if let Some(events) = to_poll[0].revents() {
+            if events.contains(PollFlags::POLLIN) {
+                handle_encrypted_data(&mut stream, &mut socket).unwrap();
+            }
+        }
+
+        if let Some(events) = to_poll[1].revents() {
+            if events.contains(PollFlags::POLLIN) {
+                handle_new_data(&mut socket, &mut stream).unwrap();
+            }
+
+            if events.contains(PollFlags::POLLHUP) {
+                println!("response writer hung up, exiting");
+                break;
+            }
+        }
+    }
+
     exitcode::OK
 }
+
+fn handle_encrypted_data(stream: &mut impl Read, socket: &mut impl Write) -> io::Result<()> {
+    let mut buf = [0_u8; BUFFER_SIZE];
+
+    loop {
+        let read = non_blocking_read(stream, &mut buf)?;
+        if read == 0 {
+            return Ok(());
+        }
+
+        socket.write_all(&buf[0..read]).unwrap();
+    }
+}
+
+fn handle_new_data(socket: &mut impl Read, stream: &mut impl Write) -> io::Result<()> {
+    let mut buf = [0_u8; BUFFER_SIZE];
+
+    loop {
+        let read = non_blocking_read(socket, &mut buf)?;
+        if read == 0 {
+            return Ok(());
+        }
+
+        stream.write_all(&buf[0..read]).unwrap();
+    }
+}
+
+fn non_blocking_read(reader: &mut impl io::Read, buf: &mut [u8]) -> io::Result<usize> {
+    match reader.read(buf) {
+        Err(e) => {
+            if e.kind() == ErrorKind::WouldBlock {
+                Ok(0)
+            } else {
+                Err(e)
+            }
+        }
+        Ok(n) => Ok(n),
+    }
+}
-- 
2.46.0


From 71888d40e71be0c217612319181a6a8ccd9dc35f Mon Sep 17 00:00:00 2001
From: Jake Hillion <jake@hillion.co.uk>
Date: Mon, 23 May 2022 19:42:07 +0100
Subject: [PATCH 3/3] added tls processing

---
 Cargo.lock          |  95 +++++++++++++++++++++++++++++++++++++++
 Cargo.toml          |   3 ++
 examples/tls/tls.rs | 106 +++++++++++++++++++++++++++++++++++++++-----
 3 files changed, 192 insertions(+), 12 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 091c3f0..86a3f61 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -11,6 +11,12 @@ dependencies = [
  "memchr",
 ]
 
+[[package]]
+name = "anyhow"
+version = "1.0.57"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "08f9b8508dccb7687a1d6c4ce66b2b0ecef467c94667de27d8d7fe1f8d2a9cdc"
+
 [[package]]
 name = "atty"
 version = "0.2.14"
@@ -28,6 +34,12 @@ version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d468802bab17cbc0cc575e9b053f41e72aa36bfa6b7f55e3529ffa43161b97fa"
 
+[[package]]
+name = "base64"
+version = "0.13.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "904dfeac50f3cdaba28fc6f57fdcddb75f49ed61346676a78c4ffe55877802fd"
+
 [[package]]
 name = "bitflags"
 version = "1.3.2"
@@ -61,6 +73,12 @@ dependencies = [
  "rustc_version",
 ]
 
+[[package]]
+name = "cc"
+version = "1.0.73"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2fff2a6927b3bb87f9595d67196a70493f627687a71d87a0d692242c33f58c11"
+
 [[package]]
 name = "cfg-if"
 version = "1.0.0"
@@ -106,6 +124,7 @@ dependencies = [
 name = "clone-shim"
 version = "0.1.0"
 dependencies = [
+ "anyhow",
  "clap 3.1.15",
  "close_fds",
  "criterion",
@@ -116,6 +135,8 @@ dependencies = [
  "libc",
  "log",
  "nix",
+ "rustls",
+ "rustls-pemfile",
  "serde",
  "serde_json",
  "tempfile",
@@ -427,6 +448,12 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "once_cell"
+version = "1.12.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7709cef83f0c1f58f666e746a08b21e0085f7440fa6a29cc194d68aac97a4225"
+
 [[package]]
 name = "oorandom"
 version = "11.1.3"
@@ -551,6 +578,21 @@ dependencies = [
  "winapi",
 ]
 
+[[package]]
+name = "ring"
+version = "0.16.20"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3053cf52e236a3ed746dfc745aa9cacf1b791d846bdaf412f60a8d7d6e17c8fc"
+dependencies = [
+ "cc",
+ "libc",
+ "once_cell",
+ "spin",
+ "untrusted",
+ "web-sys",
+ "winapi",
+]
+
 [[package]]
 name = "rustc_version"
 version = "0.4.0"
@@ -560,6 +602,27 @@ dependencies = [
  "semver",
 ]
 
+[[package]]
+name = "rustls"
+version = "0.20.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5aab8ee6c7097ed6057f43c187a62418d0c05a4bd5f18b3571db50ee0f9ce033"
+dependencies = [
+ "log",
+ "ring",
+ "sct",
+ "webpki",
+]
+
+[[package]]
+name = "rustls-pemfile"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e7522c9de787ff061458fe9a829dc790a3f5b22dc571694fc5883f448b94d9a9"
+dependencies = [
+ "base64",
+]
+
 [[package]]
 name = "ryu"
 version = "1.0.9"
@@ -581,6 +644,16 @@ version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d29ab0c6d3fc0ee92fe66e2d99f700eab17a8d57d1c1d3b748380fb20baa78cd"
 
+[[package]]
+name = "sct"
+version = "0.7.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d53dcdb7c9f8158937a7981b48accfd39a43af418591a5d008c7b22b5e1b7ca4"
+dependencies = [
+ "ring",
+ "untrusted",
+]
+
 [[package]]
 name = "semver"
 version = "1.0.6"
@@ -628,6 +701,12 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "spin"
+version = "0.5.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6e63cff320ae2c57904679ba7cb63280a3dc4613885beafb148ee7bf9aa9042d"
+
 [[package]]
 name = "strsim"
 version = "0.10.0"
@@ -725,6 +804,12 @@ version = "0.2.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8ccb82d61f80a663efe1f787a51b16b5a51e3314d6ac365b08639f52387b33f3"
 
+[[package]]
+name = "untrusted"
+version = "0.7.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a156c684c91ea7d62626509bce3cb4e1d9ed5c4d978f7b4352658f96a4c26b4a"
+
 [[package]]
 name = "walkdir"
 version = "2.3.2"
@@ -800,6 +885,16 @@ dependencies = [
  "wasm-bindgen",
 ]
 
+[[package]]
+name = "webpki"
+version = "0.22.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f095d78192e208183081cc07bc5515ef55216397af48b873e5edcd72637fa1bd"
+dependencies = [
+ "ring",
+ "untrusted",
+]
+
 [[package]]
 name = "winapi"
 version = "0.3.9"
diff --git a/Cargo.toml b/Cargo.toml
index 97634c3..7d53d83 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -24,9 +24,12 @@ tempfile = "3.3"
 
 [dev-dependencies]
 criterion = "0.3"
+anyhow = "1"
 
 # examples/tls
 httparse = "1"
+rustls = "0.20"
+rustls-pemfile = "1"
 
 [[bench]]
 name = "clone3"
diff --git a/examples/tls/tls.rs b/examples/tls/tls.rs
index 62dfd2c..39cae5c 100644
--- a/examples/tls/tls.rs
+++ b/examples/tls/tls.rs
@@ -1,21 +1,29 @@
 use std::fs::File;
-use std::io::{self, ErrorKind, Read, Write};
+use std::io::{self, BufReader, ErrorKind, Read, Write};
 use std::net::TcpStream;
 use std::os::unix::io::AsRawFd;
 use std::os::unix::net::UnixStream;
+use std::sync::Arc;
 
 use nix::poll::{poll, PollFd, PollFlags};
 
+use rustls::ServerConnection;
+
+use anyhow::Context;
+
 const BUFFER_SIZE: usize = 4096;
 
 pub(crate) fn handler(
     http_trigger_socket: File,
-    _cert: File,
-    _key: File,
+    cert: File,
+    key: File,
     mut stream: TcpStream,
 ) -> i32 {
     let (mut socket, far_socket) = UnixStream::pair().unwrap();
 
+    let config = make_config(cert, key);
+    let mut tls_conn = rustls::ServerConnection::new(config).unwrap();
+
     super::http_handler(&http_trigger_socket, far_socket);
 
     stream.set_nonblocking(true).unwrap();
@@ -32,13 +40,13 @@ pub(crate) fn handler(
 
         if let Some(events) = to_poll[0].revents() {
             if events.contains(PollFlags::POLLIN) {
-                handle_encrypted_data(&mut stream, &mut socket).unwrap();
+                handle_encrypted_data(&mut tls_conn, &mut stream, &mut socket).unwrap();
             }
         }
 
         if let Some(events) = to_poll[1].revents() {
             if events.contains(PollFlags::POLLIN) {
-                handle_new_data(&mut socket, &mut stream).unwrap();
+                handle_new_data(&mut tls_conn, &mut socket, &mut stream).unwrap();
             }
 
             if events.contains(PollFlags::POLLHUP) {
@@ -51,29 +59,61 @@ pub(crate) fn handler(
     exitcode::OK
 }
 
-fn handle_encrypted_data(stream: &mut impl Read, socket: &mut impl Write) -> io::Result<()> {
-    let mut buf = [0_u8; BUFFER_SIZE];
+fn handle_encrypted_data(
+    tls_conn: &mut ServerConnection,
+    stream: &mut (impl Read + Write),
+    socket: &mut impl Write,
+) -> anyhow::Result<()> {
+    println!("handling newly received encrypted data");
 
     loop {
-        let read = non_blocking_read(stream, &mut buf)?;
+        let read = match tls_conn.read_tls(stream) {
+            Err(e) => {
+                if e.kind() == ErrorKind::WouldBlock {
+                    0
+                } else {
+                    return Err(e).context("io error reading from stream");
+                }
+            }
+            Ok(n) => n,
+        };
+
         if read == 0 {
             return Ok(());
         }
 
-        socket.write_all(&buf[0..read]).unwrap();
+        let process_result = tls_conn.process_new_packets();
+        let write_tls_result = tls_conn.write_tls(stream);
+
+        let io_state = process_result.context("tls processing failure")?;
+        write_tls_result.context("tls write failure")?;
+
+        if io_state.plaintext_bytes_to_read() > 0 {
+            let mut reader = tls_conn
+                .reader()
+                .take(io_state.plaintext_bytes_to_read() as u64);
+
+            std::io::copy(&mut reader, socket)?;
+        }
     }
 }
 
-fn handle_new_data(socket: &mut impl Read, stream: &mut impl Write) -> io::Result<()> {
-    let mut buf = [0_u8; BUFFER_SIZE];
+fn handle_new_data(
+    tls_conn: &mut ServerConnection,
+    socket: &mut impl Read,
+    stream: &mut impl Write,
+) -> anyhow::Result<()> {
+    println!("handling new data to encrypt");
 
+    let mut buf = [0_u8; BUFFER_SIZE];
     loop {
         let read = non_blocking_read(socket, &mut buf)?;
         if read == 0 {
             return Ok(());
         }
 
-        stream.write_all(&buf[0..read]).unwrap();
+        tls_conn.writer().write_all(&buf[0..read])?;
+        tls_conn.write_tls(stream)?;
     }
 }
 
@@ -89,3 +129,45 @@ fn non_blocking_read(reader: &mut impl io::Read, buf: &mut [u8]) -> io::Result<u
         Ok(n) => Ok(n),
     }
 }
+
+fn make_config(cert: File, key: File) -> Arc<rustls::ServerConfig> {
+    let certs = load_certs(cert);
+    let privkey = load_private_key(key);
+
+    let config = rustls::ServerConfig::builder()
+        .with_safe_default_cipher_suites()
+        .with_safe_default_kx_groups()
+        .with_safe_default_protocol_versions()
+        .expect("inconsistent cipher-suites/versions specified")
+        .with_no_client_auth()
+        .with_single_cert(certs, privkey)
+        .expect("bad certificates/private key");
+
+    Arc::new(config)
+}
+
+fn load_certs(certfile: File) -> Vec<rustls::Certificate> {
+    let mut reader = BufReader::new(certfile);
+
+    rustls_pemfile::certs(&mut reader)
+        .unwrap()
+        .iter()
+        .map(|v| rustls::Certificate(v.clone()))
+        .collect()
+}
+
+fn load_private_key(keyfile: File) -> rustls::PrivateKey {
+    let mut reader = BufReader::new(keyfile);
+
+    loop {
+        match rustls_pemfile::read_one(&mut reader).expect("cannot parse private key .pem file") {
+            Some(rustls_pemfile::Item::RSAKey(key)) => return rustls::PrivateKey(key),
+            Some(rustls_pemfile::Item::PKCS8Key(key)) => return rustls::PrivateKey(key),
+            Some(rustls_pemfile::Item::ECKey(key)) => return rustls::PrivateKey(key),
+            None => break,
+            _ => {}
+        }
+    }
+
+    panic!("no keys found (encrypted keys not supported)");
+}
-- 
2.46.0