fix(http): read more before triggering TooLargeError

This includes a custom BufReader, since the one in libstd doesn't allow
reading additional data into the buffer without consuming it. This is
required because some connections may send shorter packets, and so we
need to perform multiple reads. After each read, the contents of the
buffer are passed to httparse to see if have a valid message. If so, the
proper amount of bytes are consumed. The additional bytes are left in
the buffer since they are the beginning of the body.

The buffer in this BufReader also grows in size, compared to the libstd
which is sized once. This is because we start with a smaller buffer,
since the majority of messages will be able to include their head in a
packet or 2. Therefore, it's a wasteful performance hit to allocate the
maximum size for every message. However, some headers can be quite big,
and to allow for many of them to be set, we include a maximum size. Once
we've hit the maximum buffer size, and still haven't determined the end
of the headers, a HttpTooLargeError will be returned.

Closes #389

src/buffer.rs

@@ -0,0 +1,95 @@
+use std::cmp;
+use std::iter;
+use std::io::{self, Read, BufRead, Cursor};
+
+pub struct BufReader<R> {
+    buf: Cursor<Vec<u8>>,
+    inner: R
+}
+
+const INIT_BUFFER_SIZE: usize = 4096;
+const MAX_BUFFER_SIZE: usize = 8192 + 4096 * 100;
+
+impl<R: Read> BufReader<R> {
+    pub fn new(rdr: R) -> BufReader<R> {
+        BufReader::with_capacity(rdr, INIT_BUFFER_SIZE)
+    }
+
+    pub fn with_capacity(rdr: R, cap: usize) -> BufReader<R> {
+        BufReader {
+            buf: Cursor::new(Vec::with_capacity(cap)),
+            inner: rdr
+        }
+    }
+
+    pub fn get_ref(&self) -> &R { &self.inner }
+
+    pub fn get_mut(&mut self) -> &mut R { &mut self.inner }
+
+    pub fn get_buf(&self) -> &[u8] {
+        self.buf.get_ref()
+    }
+
+    pub fn into_inner(self) -> R { self.inner }
+
+    pub fn read_into_buf(&mut self) -> io::Result<usize> {
+        let v = self.buf.get_mut();
+        reserve(v);
+        let inner = &mut self.inner;
+        with_end_to_cap(v, |b| inner.read(b))
+    }
+}
+
+impl<R: Read> Read for BufReader<R> {
+    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+        if self.buf.get_ref().len() == self.buf.position() as usize &&
+            buf.len() >= self.buf.get_ref().capacity() {
+            return self.inner.read(buf);
+        }
+        try!(self.fill_buf());
+        self.buf.read(buf)
+    }
+}
+
+impl<R: Read> BufRead for BufReader<R> {
+    fn fill_buf(&mut self) -> io::Result<&[u8]> {
+         if self.buf.position() as usize == self.buf.get_ref().len() {
+            self.buf.set_position(0);
+            let v = self.buf.get_mut();
+            v.truncate(0);
+            let inner = &mut self.inner;
+            try!(with_end_to_cap(v, |b| inner.read(b)));
+         }
+         self.buf.fill_buf()
+    }
+
+    fn consume(&mut self, amt: usize) {
+        self.buf.consume(amt)
+    }
+}
+
+fn with_end_to_cap<F>(v: &mut Vec<u8>, f: F) -> io::Result<usize>
+    where F: FnOnce(&mut [u8]) -> io::Result<usize>
+{
+    let len = v.len();
+    let new_area = v.capacity() - len;
+    v.extend(iter::repeat(0).take(new_area));
+    match f(&mut v[len..]) {
+        Ok(n) => {
+            v.truncate(len + n);
+            Ok(n)
+        }
+        Err(e) => {
+            v.truncate(len);
+            Err(e)
+        }
+    }
+}
+
+#[inline]
+fn reserve(v: &mut Vec<u8>) {
+    let cap = v.capacity();
+    if v.len() == cap {
+        v.reserve(cmp::min(cap * 4, MAX_BUFFER_SIZE) - cap);
+    }
+}

src/client/response.rs

@@ -1,8 +1,9 @@
 //! Client Responses
-use std::io::{self, Read, BufReader};
+use std::io::{self, Read};
 use std::num::FromPrimitive;
 use std::marker::PhantomData;
 
+use buffer::BufReader;
 use header;
 use header::{ContentLength, TransferEncoding};
 use header::Encoding::Chunked;
@@ -103,9 +104,10 @@ impl Read for Response {
 mod tests {
     use std::borrow::Cow::Borrowed;
     use std::boxed::BoxAny;
-    use std::io::{self, Read, BufReader};
+    use std::io::{self, Read};
     use std::marker::PhantomData;
 
+    use buffer::BufReader;
     use header::Headers;
     use header::TransferEncoding;
     use header::Encoding;

src/http.rs

@@ -5,12 +5,13 @@ use std::io::{self, Read, Write, BufRead};
 
 use httparse;
 
+use buffer::BufReader;
 use header::Headers;
 use method::Method;
 use uri::RequestUri;
 use version::HttpVersion::{self, Http10, Http11};
 use HttpError:: HttpTooLargeError;
-use HttpResult;
+use {HttpError, HttpResult};
 
 use self::HttpReader::{SizedReader, ChunkedReader, EofReader, EmptyReader};
 use self::HttpWriter::{ThroughWriter, ChunkedWriter, SizedWriter, EmptyWriter};
@@ -307,56 +308,88 @@ impl<W: Write> Write for HttpWriter<W> {
     }
 }
 
+const MAX_HEADERS: usize = 100;
+
 /// Parses a request into an Incoming message head.
-pub fn parse_request<T: BufRead>(buf: &mut T) -> HttpResult<Incoming<(Method, RequestUri)>> {
-    let (inc, len) = {
-        let slice = try!(buf.fill_buf());
-        let mut headers = [httparse::Header { name: "", value: b"" }; 64];
-        let mut req = httparse::Request::new(&mut headers);
-        match try!(req.parse(slice)) {
+#[inline]
+pub fn parse_request<R: Read>(buf: &mut BufReader<R>) -> HttpResult<Incoming<(Method, RequestUri)>> {
+    parse::<R, httparse::Request, (Method, RequestUri)>(buf)
+}
+
+/// Parses a response into an Incoming message head.
+#[inline]
+pub fn parse_response<R: Read>(buf: &mut BufReader<R>) -> HttpResult<Incoming<RawStatus>> {
+    parse::<R, httparse::Response, RawStatus>(buf)
+}
+
+fn parse<R: Read, T: TryParse<Subject=I>, I>(rdr: &mut BufReader<R>) -> HttpResult<Incoming<I>> {
+    loop {
+        match try!(try_parse::<R, T, I>(rdr)) {
+            httparse::Status::Complete((inc, len)) => {
+                rdr.consume(len);
+                return Ok(inc);
+            },
+            _partial => ()
+        }
+        match try!(rdr.read_into_buf()) {
+            0 => return Err(HttpTooLargeError),
+            _ => ()
+        }
+    }
+}
+
+fn try_parse<R: Read, T: TryParse<Subject=I>, I>(rdr: &mut BufReader<R>) -> TryParseResult<I> {
+    let mut headers = [httparse::EMPTY_HEADER; MAX_HEADERS];
+    <T as TryParse>::try_parse(&mut headers, rdr.get_buf())
+}
+
+#[doc(hidden)]
+trait TryParse {
+    type Subject;
+    fn try_parse<'a>(headers: &'a mut [httparse::Header<'a>], buf: &'a [u8]) -> TryParseResult<Self::Subject>;
+}
+
+type TryParseResult<T> = Result<httparse::Status<(Incoming<T>, usize)>, HttpError>;
+
+impl<'a> TryParse for httparse::Request<'a> {
+    type Subject = (Method, RequestUri);
+
+    fn try_parse<'b>(headers: &'b mut [httparse::Header<'b>], buf: &'b [u8]) -> TryParseResult<(Method, RequestUri)> {
+        let mut req = httparse::Request::new(headers);
+        Ok(match try!(req.parse(buf)) {
             httparse::Status::Complete(len) => {
-                (Incoming {
+                httparse::Status::Complete((Incoming {
                     version: if req.version.unwrap() == 1 { Http11 } else { Http10 },
                     subject: (
                         try!(req.method.unwrap().parse()),
                         try!(req.path.unwrap().parse())
                     ),
                     headers: try!(Headers::from_raw(req.headers))
-                }, len)
+                }, len))
             },
-            _ => {
-                // request head is bigger than a BufRead's buffer? 400 that!
-                return Err(HttpTooLargeError)
-            }
-        }
-    };
-    buf.consume(len);
-    Ok(inc)
+            httparse::Status::Partial => httparse::Status::Partial
+        })
+    }
 }
 
-/// Parses a response into an Incoming message head.
-pub fn parse_response<T: BufRead>(buf: &mut T) -> HttpResult<Incoming<RawStatus>> {
-    let (inc, len) = {
-        let mut headers = [httparse::Header { name: "", value: b"" }; 64];
-        let mut res = httparse::Response::new(&mut headers);
-        match try!(res.parse(try!(buf.fill_buf()))) {
+impl<'a> TryParse for httparse::Response<'a> {
+    type Subject = RawStatus;
+
+    fn try_parse<'b>(headers: &'b mut [httparse::Header<'b>], buf: &'b [u8]) -> TryParseResult<RawStatus> {
+        let mut res = httparse::Response::new(headers);
+        Ok(match try!(res.parse(buf)) {
             httparse::Status::Complete(len) => {
-                (Incoming {
+                httparse::Status::Complete((Incoming {
                     version: if res.version.unwrap() == 1 { Http11 } else { Http10 },
                     subject: RawStatus(
                         res.code.unwrap(), res.reason.unwrap().to_owned().into_cow()
                     ),
                     headers: try!(Headers::from_raw(res.headers))
-                }, len)
+                }, len))
             },
-            _ => {
-                // response head is bigger than a BufRead's buffer?
-                return Err(HttpTooLargeError)
-            }
-        }
-    };
-    buf.consume(len);
-    Ok(inc)
+            httparse::Status::Partial => httparse::Status::Partial
+        })
+    }
 }
 
 /// An Incoming Message head. Includes request/status line, and headers.
@@ -456,19 +489,30 @@ mod tests {
         read_err("1;no CRLF");
     }
 
+    #[test]
+    fn test_parse_incoming() {
+        use buffer::BufReader;
+        use mock::MockStream;
+
+        use super::parse_request;
+        let mut raw = MockStream::with_input(b"GET /echo HTTP/1.1\r\nHost: hyper.rs\r\n\r\n");
+        let mut buf = BufReader::new(&mut raw);
+        parse_request(&mut buf).unwrap();
+    }
+
     use test::Bencher;
 
     #[bench]
     fn bench_parse_incoming(b: &mut Bencher) {
-        use std::io::BufReader;
+        use buffer::BufReader;
         use mock::MockStream;
 
         use super::parse_request;
+        let mut raw = MockStream::with_input(b"GET /echo HTTP/1.1\r\nHost: hyper.rs\r\n\r\n");
+        let mut buf = BufReader::new(&mut raw);
         b.iter(|| {
-            let mut raw = MockStream::with_input(b"GET /echo HTTP/1.1\r\nHost: hyper.rs\r\n\r\n");
-            let mut buf = BufReader::new(&mut raw);
-
             parse_request(&mut buf).unwrap();
+            buf.get_mut().read.set_position(0);
         });
     }
 }

src/lib.rs

@@ -168,7 +168,8 @@ macro_rules! inspect(
 #[cfg(test)]
 #[macro_use]
 mod mock;
-
+#[doc(hidden)]
+pub mod buffer;
 pub mod client;
 pub mod error;
 pub mod method;

src/server/mod.rs

@@ -1,5 +1,5 @@
 //! HTTP Server
-use std::io::{BufReader, BufWriter, Write};
+use std::io::{BufWriter, Write};
 use std::marker::PhantomData;
 use std::net::{SocketAddr, ToSocketAddrs};
 use std::path::Path;
@@ -14,6 +14,7 @@ pub use net::{Fresh, Streaming};
 
 use HttpError::HttpIoError;
 use {HttpResult};
+use buffer::BufReader;
 use header::{Headers, Connection, Expect};
 use header::ConnectionOption::{Close, KeepAlive};
 use method::Method;
@@ -227,6 +228,7 @@ mod tests {
             Host: example.domain\r\n\
             Expect: 100-continue\r\n\
             Content-Length: 10\r\n\
+            Connection: close\r\n\
             \r\n\
             1234567890\
         ");

src/server/request.rs

@@ -2,10 +2,11 @@
 //!
 //! These are requests that a `hyper::Server` receives, and include its method,
 //! target URI, headers, and message body.
-use std::io::{self, Read, BufReader};
+use std::io::{self, Read};
 use std::net::SocketAddr;
 
 use {HttpResult};
+use buffer::BufReader;
 use net::NetworkStream;
 use version::{HttpVersion};
 use method::Method::{self, Get, Head};
@@ -81,12 +82,13 @@ impl<'a, 'b> Read for Request<'a, 'b> {
 
 #[cfg(test)]
 mod tests {
+    use buffer::BufReader;
     use header::{Host, TransferEncoding, Encoding};
     use net::NetworkStream;
     use mock::MockStream;
     use super::Request;
 
-    use std::io::{self, Read, BufReader};
+    use std::io::{self, Read};
     use std::net::SocketAddr;
 
     fn sock(s: &str) -> SocketAddr {