Relax MessageBody limit to 2048kb (#2110)

* relax MessageBody limit to 2048kb

* fix clippy

* Update awc/src/response.rs

Co-authored-by: Rob Ede <robjtede@icloud.com>

* fix default body limit

Co-authored-by: Rob Ede <robjtede@icloud.com>

awc/src/response.rs

@@ -228,12 +228,13 @@ impl<S> fmt::Debug for ClientResponse<S> {
     }
 }
 
+const DEFAULT_BODY_LIMIT: usize = 2 * 1024 * 1024;
+
 /// Future that resolves to a complete HTTP message body.
 pub struct MessageBody<S> {
     length: Option<usize>,
-    err: Option<PayloadError>,
     timeout: ResponseTimeout,
-    fut: Option<ReadBody<S>>,
+    body: Result<ReadBody<S>, Option<PayloadError>>,
 }
 
 impl<S> MessageBody<S>
@@ -242,41 +243,38 @@ where
 {
     /// Create `MessageBody` for request.
     pub fn new(res: &mut ClientResponse<S>) -> MessageBody<S> {
-        let mut len = None;
-        if let Some(l) = res.headers().get(&header::CONTENT_LENGTH) {
-            if let Ok(s) = l.to_str() {
-                if let Ok(l) = s.parse::<usize>() {
-                    len = Some(l)
-                } else {
-                    return Self::err(PayloadError::UnknownLength);
+        let length = match res.headers().get(&header::CONTENT_LENGTH) {
+            Some(value) => {
+                let len = value.to_str().ok().and_then(|s| s.parse::<usize>().ok());
+
+                match len {
+                    None => return Self::err(PayloadError::UnknownLength),
+                    len => len,
                 }
-            } else {
-                return Self::err(PayloadError::UnknownLength);
             }
-        }
+            None => None,
+        };
 
         MessageBody {
-            length: len,
-            err: None,
+            length,
             timeout: std::mem::take(&mut res.timeout),
-            fut: Some(ReadBody::new(res.take_payload(), 262_144)),
+            body: Ok(ReadBody::new(res.take_payload(), DEFAULT_BODY_LIMIT)),
         }
     }
 
-    /// Change max size of payload. By default max size is 256kB
+    /// Change max size of payload. By default max size is 2048kB
     pub fn limit(mut self, limit: usize) -> Self {
-        if let Some(ref mut fut) = self.fut {
-            fut.limit = limit;
+        if let Ok(ref mut body) = self.body {
+            body.limit = limit;
         }
         self
     }
 
     fn err(e: PayloadError) -> Self {
         MessageBody {
-            fut: None,
-            err: Some(e),
             length: None,
             timeout: ResponseTimeout::default(),
+            body: Err(Some(e)),
         }
     }
 }
@@ -290,19 +288,20 @@ where
     fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
         let this = self.get_mut();
 
-        if let Some(err) = this.err.take() {
-            return Poll::Ready(Err(err));
-        }
+        match this.body {
+            Err(ref mut err) => Poll::Ready(Err(err.take().unwrap())),
+            Ok(ref mut body) => {
+                if let Some(len) = this.length.take() {
+                    if len > body.limit {
+                        return Poll::Ready(Err(PayloadError::Overflow));
+                    }
+                }
 
-        if let Some(len) = this.length.take() {
-            if len > this.fut.as_ref().unwrap().limit {
-                return Poll::Ready(Err(PayloadError::Overflow));
+                this.timeout.poll_timeout(cx)?;
+
+                Pin::new(body).poll(cx)
             }
         }
-
-        this.timeout.poll_timeout(cx)?;
-
-        Pin::new(&mut this.fut.as_mut().unwrap()).poll(cx)
     }
 }
 
@@ -415,7 +414,7 @@ impl<S> ReadBody<S> {
     fn new(stream: Payload<S>, limit: usize) -> Self {
         Self {
             stream,
-            buf: BytesMut::with_capacity(std::cmp::min(limit, 32768)),
+            buf: BytesMut::new(),
             limit,
         }
     }
@@ -430,20 +429,14 @@ where
     fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
         let this = self.get_mut();
 
-        loop {
-            return match Pin::new(&mut this.stream).poll_next(cx)? {
-                Poll::Ready(Some(chunk)) => {
-                    if (this.buf.len() + chunk.len()) > this.limit {
-                        Poll::Ready(Err(PayloadError::Overflow))
-                    } else {
-                        this.buf.extend_from_slice(&chunk);
-                        continue;
-                    }
-                }
-                Poll::Ready(None) => Poll::Ready(Ok(this.buf.split().freeze())),
-                Poll::Pending => Poll::Pending,
-            };
+        while let Some(chunk) = ready!(Pin::new(&mut this.stream).poll_next(cx)?) {
+            if (this.buf.len() + chunk.len()) > this.limit {
+                return Poll::Ready(Err(PayloadError::Overflow));
+            }
+            this.buf.extend_from_slice(&chunk);
         }
+
+        Poll::Ready(Ok(this.buf.split().freeze()))
     }
 }
 
@@ -462,7 +455,7 @@ mod tests {
             _ => unreachable!("error"),
         }
 
-        let mut req = TestResponse::with_header(header::CONTENT_LENGTH, "1000000").finish();
+        let mut req = TestResponse::with_header(header::CONTENT_LENGTH, "10000000").finish();
         match req.body().await.err().unwrap() {
             PayloadError::Overflow => {}
             _ => unreachable!("error"),