server: get token, wip hmac work

[hippotat.git] / src / bin / server.rs

diff --git a/src/bin/server.rs b/src/bin/server.rs
index d0d7c840ef3d411a284ccd45152f61d59eae3139..3e71b4134776e76778cb4373c1712fd2c3e3e50e 100644 (file)
--- a/src/bin/server.rs
+++ b/src/bin/server.rs
@@ -27,9 +27,9 @@ struct WebRequest {
 }
 
 async fn handle(
-  _all_clients: Arc<AllClients>,
+  all_clients: Arc<AllClients>,
   req: hyper::Request<hyper::Body>
-) -> Result<hyper::Response<hyper::Body>, Infallible> {
+) -> Result<hyper::Response<hyper::Body>, Void> {
   if req.method() == Method::GET {
     let mut resp = hyper::Response::new(hyper::Body::from("hippotat\r\n"));
     resp.headers_mut().insert(
@@ -88,17 +88,60 @@ async fn handle(
       r#"first multipart component must be name="m""#
     )) }
 
-    let nl = memchr::memchr2(b'\r', b'\n', comp.payload_start)
-      .ok_or_else(|| anyhow!("no newline in first metadata line?"))?;
-
-    let client = &comp.payload_start[0..nl];
-    let client = str::from_utf8(client).context("client addr utf-8")?;
-    let client: IpAddr = client.parse().context("client address")?;
+    let mut meta = MetadataFieldIterator::new(comp.payload_start);
+
+    let client: ClientName = meta.need_parse().context("client addr")?;
+
+    let mut hmac_got = [0; HMAC_L];
+    let (client_time, hmac_got_l) = (||{
+      let token: &str = meta.need_next().context(r#"find in "m""#)?;
+      let (time_t, hmac_b64) = token.split_once(' ')
+        .ok_or_else(|| anyhow!("split"))?;
+      let time_t = u64::from_str_radix(time_t, 16).context("parse time_t")?;
+      let l = io::copy(
+        &mut base64::read::DecoderReader::new(&mut hmac_b64.as_bytes(),
+                                              BASE64_CONFIG),
+        &mut &mut hmac_got[..]
+      ).context("parse b64 token")?;
+      let l = l.try_into()?;
+      Ok::<_,AE>((time_t, l))
+    })().context("token")?;
+    let hmac_got = &hmac_got[0..hmac_got_l];
+
+    let client = all_clients.get(&client);
+
+    // We attempt to hide whether the client exists we don't try to
+    // hide the hash lookup computationgs, but we do try to hide the
+    // HMAC computation by always doing it.  We hope that the compiler
+    // doesn't produce a specialised implementation for the dummy
+    // secret value.
+    let client_exists = subtle::Choice::from(client.is_some() as u8);
+    let secret = client.map(|c| c.ic.secret.0.as_bytes());
+    let secret = secret.unwrap_or(&[0x55; HMAC_B][..]);
+    let client_time_s = format!("{:x}", client_time);
+    let hmac_exp = token_hmac(secret, client_time_s.as_bytes());
+    // We also definitely want a consttime memeq for the hmac value
+    let hmac_ok = hmac_got.ct_eq(&hmac_exp);
+    if ! bool::from(hmac_ok & client_exists) {
+      throw!(anyhow!("xxx should be a 403 error"));
+    }
 
+    let client = client.unwrap();
+    let now = time_t_now();
+    let chk_skew = |a: u64, b: u64, c_ahead_behind| {
+      if let Some(a_ahead) = a.checked_sub(b) {
+        if a_ahead > client.ic.max_clock_skew.as_secs() {
+          throw!(anyhow!("too much clock skew (client {} by {})",
+                         c_ahead_behind, a_ahead));
+        }
+      }
+      Ok::<_,AE>(())
+    };
+    chk_skew(client_time, now, "ahead")?;
+    chk_skew(now, client_time, "behind")?;
     
-
     eprintln!("boundary={:?} start={} name={:?} client={}",
-              boundary, start, &comp.name, client);
+              boundary, start, &comp.name, &client.ic);
 
     Ok::<_,AE>(())
   }.await {
@@ -117,6 +160,7 @@ async fn handle(
 async fn run_client(_ic: Arc<InstanceConfig>, _web: mpsc::Receiver<WebRequest>)
                     -> Result<Void, AE>
 {
+  tokio::time::sleep(Duration::from_secs(1_000_000_000)).await;
   Err(anyhow!("xxx"))
 }
 
@@ -158,16 +202,11 @@ async fn main() {
 
     for addr in &global.addrs {
       let all_clients_ = all_clients.clone();
-      let make_service = hyper::service::make_service_fn(
-        move |_conn| {
-          let all_clients_ = all_clients_.clone();
-          async {
-            Ok::<_, Void>(hyper::service::service_fn(move |req| {
-              let all_clients_ = all_clients_.clone();
-              handle(all_clients_, req)
-            }))
-          }
-        }
+      let make_service = hyper::service::make_service_fn(move |_conn| {
+        let all_clients_ = all_clients_.clone();
+        async { Ok::<_, Void>( hyper::service::service_fn(move |req| {
+          handle(all_clients_.clone(), req)
+        }) ) } }
       );
 
       let addr = SocketAddr::new(*addr, global.port);