fix: http1.0 behavior

src/Std/Internal/Http/Protocol/H1.lean

@@ -309,9 +309,13 @@ private def checkReceivingMessageHead (message : Message.Head .receiving) : Exce
   if !isValidRequestTargetForMethod message then
     throw .badMessage
 
-  -- Host validation
-  if !hasSingleAcceptedHostHeader message then
-    throw .badMessage
+  -- Host validation:
+  -- • HTTP/1.1: a Host header is REQUIRED (RFC 9112 §3.2).
+  -- • HTTP/1.0: Host is optional (RFC 2616 §14.23), but if present it must
+  --   be a single, well-formed value (no duplicates, correct authority form).
+  if message.version == .v11 || message.headers.contains .host then
+    if !hasSingleAcceptedHostHeader message then
+      throw .badMessage
 
   -- Gets the size of the message.
   match message.getSize (allowEOFBody := true) with

src/Std/Internal/Http/Protocol/H1/Message.lean

@@ -91,7 +91,11 @@ def Message.Head.getSize (message : Message.Head dir) (allowEOFBody : Bool) : Op
     let te := Header.TransferEncoding.parse header
 
     match Header.TransferEncoding.isChunked <$> te, contentLength with
-    | some true, none => some .chunked
+    | some true, none =>
+        -- HTTP/1.0 does not define chunked transfer encoding (RFC 2068 §19.4.6).
+        -- A server MUST NOT use chunked with an HTTP/1.0 peer; likewise, an
+        -- HTTP/1.0 request carrying Transfer-Encoding: chunked is malformed.
+        if message.version == .v10 then none else some .chunked
     | _, _ => none -- To avoid request smuggling when TE and CL are mixed.
 
   -- We disallow multiple transfer-encoding headers.
@@ -99,23 +103,24 @@ def Message.Head.getSize (message : Message.Head dir) (allowEOFBody : Bool) : Op
 /--
 Checks whether the message indicates that the connection should be kept alive.
 -/
-@[inline]
 def Message.Head.shouldKeepAlive (message : Message.Head dir) : Bool :=
-  if message.version ≠ .v11 then
-    false
-  else
+  let tokens? : Option (Array String) :=
     match message.headers.getAll? .connection with
-    | none => true
+    | none => some #[]
     | some values =>
-        let tokens? : Option (Array String) :=
-          values.foldl (fun acc raw => do
-            let acc ← acc
-            let parsed ← Header.Connection.parse raw
-            pure (acc ++ parsed.tokens)
-          ) (some #[])
-        match tokens? with
-        | none => false
-        | some tokens => !tokens.any (· == "close")
+        values.foldl (fun acc raw => do
+          let acc ← acc
+          let parsed ← Header.Connection.parse raw
+          pure (acc ++ parsed.tokens)
+        ) (some #[])
+
+  match tokens? with
+  | none =>false
+  | some tokens =>
+      if message.version == .v11 then
+        !tokens.any (· == "close")
+      else
+        tokens.any (· == "keep-alive")
 
 instance : Repr (Message.Head dir) :=
   match dir with