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 92eabbdddf8170b7664679357085144cb1c49ec8..bc56fe7fd5af97090b438de873cc1501930832d9 100644 (file)
--- a/src/bin/server.rs
+++ b/src/bin/server.rs
@@ -27,7 +27,7 @@ struct WebRequest {
 }
 
 async fn handle(
-  _all_clients: Arc<AllClients>,
+  all_clients: Arc<AllClients>,
   req: hyper::Request<hyper::Body>
 ) -> Result<hyper::Response<hyper::Body>, Void> {
   if req.method() == Method::GET {
@@ -88,17 +88,52 @@ 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 (client_time, hmac_got) = (||{
+      let token: &str = meta.need_next().context(r#"find in "m""#)?;
+      let (time_t, hmac_got) = token.split_once(' ')
+        .ok_or_else(|| anyhow!("split"))?;
+      let time_t: u64 = time_t.parse().context("parse time_t")?;
+      Ok::<_,AE>((time_t, hmac_got))
+    })().context("token")?;
+
+    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.as_bytes().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 +152,7 @@ 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"))
 }