Motivation:
A degradation in performance has been observed from the 4.0 branch as documented in https://github.com/netty/netty/issues/3962.
Modifications:
- Simplify Headers class hierarchy.
- Restore the DefaultHeaders to be based upon DefaultHttpHeaders from 4.0.
- Make various other modifications that are causing hot spots.
Result:
Performance is now on par with 4.0.
Motivation:
Due not using a cast we insert 32 and not a whitespace into the String.
Modifications:
Correclty cast to char.
Result:
Correct handling of whitespaces.
Motivation:
In the event an HTTP message does not include either a content-length or a transfer-encoding header [RFC 7230](https://tools.ietf.org/html/rfc7230#section-3.3.3) states the behavior must be treated differently for requests and responses. If the channel is half closed then the HttpObjectDecoder is not invoking decodeLast and thus not checking if messages should be sent up the pipeline.
Modifications:
- Add comments to clarify regular decode default case.
- Handle the ChannelInputShutdownEvent in the HttpObjectDecoder and evaluate if messages need to be generated.
Result:
Messages are generated on half closed, and comments clarify existing logic.
Motivation:
We noticed that the headers implementation in Netty for HTTP/2 uses quite a lot of memory
and that also at least the performance of randomly accessing a header is quite poor. The main
concern however was memory usage, as profiling has shown that a DefaultHttp2Headers
not only use a lot of memory it also wastes a lot due to the underlying hashmaps having
to be resized potentially several times as new headers are being inserted.
This is tracked as issue #3600.
Modifications:
We redesigned the DefaultHeaders to simply take a Map object in its constructor and
reimplemented the class using only the Map primitives. That way the implementation
is very concise and hopefully easy to understand and it allows each concrete headers
implementation to provide its own map or to even use a different headers implementation
for processing requests and writing responses i.e. incoming headers need to provide
fast random access while outgoing headers need fast insertion and fast iteration. The
new implementation can support this with hardly any code changes. It also comes
with the advantage that if the Netty project decides to add a third party collections library
as a dependency, one can simply plug in one of those very fast and memory efficient map
implementations and get faster and smaller headers for free.
For now, we are using the JDK's TreeMap for HTTP and HTTP/2 default headers.
Result:
- Significantly fewer lines of code in the implementation. While the total commit is still
roughly 400 lines less, the actual implementation is a lot less. I just added some more
tests and microbenchmarks.
- Overall performance is up. The current implementation should be significantly faster
for insertion and retrieval. However, it is slower when it comes to iteration. There is simply
no way a TreeMap can have the same iteration performance as a linked list (as used in the
current headers implementation). That's totally fine though, because when looking at the
benchmark results @ejona86 pointed out that the performance of the headers is completely
dominated by insertion, that is insertion is so significantly faster in the new implementation
that it does make up for several times the iteration speed. You can't iterate what you haven't
inserted. I am demonstrating that in this spreadsheet [1]. (Actually, iteration performance is
only down for HTTP, it's significantly improved for HTTP/2).
- Memory is down. The implementation with TreeMap uses on avg ~30% less memory. It also does not
produce any garbage while being resized. In load tests for GRPC we have seen a memory reduction
of up to 1.2KB per RPC. I summarized the memory improvements in this spreadsheet [1]. The data
was generated by [2] using JOL.
- While it was my original intend to only improve the memory usage for HTTP/2, it should be similarly
improved for HTTP, SPDY and STOMP as they all share a common implementation.
[1] https://docs.google.com/spreadsheets/d/1ck3RQklyzEcCLlyJoqDXPCWRGVUuS-ArZf0etSXLVDQ/edit#gid=0
[2] https://gist.github.com/buchgr/4458a8bdb51dd58c82b4
Motivation:
The SPDY spec requires that all header names be lowercase (see https://www.chromium.org/spdy/spdy-protocol/spdy-protocol-draft3-1#TOC-3.2-HTTP-Request-Response). The SPDY codec header name validator does not enforce this requirement.
Modifications:
- SpdyCodecUtil.validateHeaderName should check for upper case characters and throw an error if any are found.
Result:
SPDY codec header validation enforces specification requirement.
Motivation:
The HttpObjectDecoder is on the hot code path for the http codec. There are a few hot methods which can be modified to improve performance.
Modifications:
- Modify AppendableCharSequence to provide unsafe methods which don't need to re-check bounds for every call.
- Update HttpObjectDecoder methods to take advantage of new AppendableCharSequence methods.
Result:
Peformance boost for decoding http objects.
Motivation:
WebSocketServerHandshakerFactory.sendUnsupportedVersionResponse does not
send a LastHttpContent, nor does it flush, and it doesn't send a content
length.
Modifications:
Changed sendUnsupportedVersionResponse to send FullHttpResponse, to
writeAndFlush, and to set a content length of 0. Also added a test for
this method.
Result:
Upstream handlers will be able to determine the end of the response, the
response will actually get written to the client, and the client will be
able to determine the end of the response.
Proposal to fix issue #3636
Motivations:
Currently, while adding the next buffers to the decoder
(`decoder.offer()`), there is no way to access to the current HTTP
object being decoded since it can only be available currently once fully
decoded by `decoder.hasNext()`.
Some could want to know the progression on the overall transfer but also
per HTTP object.
While overall progression could be done using (if available) the global
Content-Length of the request and taking into account each HttpContent
size, the per HttpData object progression is unknown.
Modifications:
1) For HTTP object, `AbstractHttpData` has 2 protected properties named
`definedSize` and `size`, respectively the supposely final size and the
current (decoded until now) size.
This provides a new method `definedSize()` to get the current value for
`definedSize`. The `size` attribute is reachable by the `length()`
method.
Note however there are 2 different ways that currently managed the
`definedSize`:
a) `Attribute`: it is reset each time the value is less than actual
(when a buffer is added, the value is increased) since the final length
is not known (no Content-Length)
b) `FileUpload`: it is set at startup from the lengh provided
So these differences could lead in wrong perception;
a) `Attribute`: definedSize = size always
b) `FileUpload`: definedSize >= size always
Therefore the comment tries to explain clearly the different behaviors.
2) In the InterfaceHttpPostRequestDecoder (and the derived classes), I
add a new method: `decoder.currentPartialHttpData()` which will return a
`InterfaceHttpData` (if any) as the current `Attribute` or `FileUpload`
(the 2 generic types), which will allow then the programmer to check
according to the real type (instance of) the 2 methods `definedSize()`
and `length()`.
This method check if currentFileUpload or currentAttribute are null and
returns the one (only one could be not null) that is not null.
Note that if this method returns null, it might mean 2 situations:
a) the last `HttpData` (whatever attribute or file upload) is already
finished and therefore accessible through `next()`
b) there is not yet any `HttpData` in decoding (body not yet parsed for
instance)
Result:
The developper has more access and therefore control on the current
upload.
The coding from developper side could looks like in the example in
HttpUloadServerHandler.
Related: #3814
Motivation:
To implement the support for an upgrade from cleartext HTTP/1.1
connection to cleartext HTTP/2 (h2c) connection, a user usually uses
HttpServerUpgradeHandler.
It does its job, but it requires a user to instantiate the UpgradeCodecs
for all supported protocols upfront. It means redundancy for the
connections that are not upgraded.
Modifications:
- Change the constructor of HttpServerUpgradeHandler
- Accept UpgraceCodecFactory instead of UpgradeCodecs
- The default constructor of HttpServerUpgradeHandler sets the
maxContentLength to 0 now, which shouldn't be a problem because a
usual upgrade request is a GET.
- Update the examples accordingly
Result:
A user can instantiate Http2ServerUpgradeCodec and its related objects
(Http2Connection, Http2FrameReader/Writer, Http2FrameListener, etc) only
when necessary.
Motivation:
We need to ensure we never allow to have null values set on headers, otherwise we will see a NPE during encoding them.
Modifications:
Add unit test that shows we correctly handle null values.
Result:
Verify correct implementation.
Motivation:
SpdyOrHttpChooser and Http2OrHttpChooser duplicate fair amount code with each other.
Modification:
- Replace SpdyOrHttpChooser and Http2OrHttpChooser with ApplicationProtocolNegotiationHandler
- Add ApplicationProtocolNames to define the known application-level protocol names
Result:
- Less code duplication
- A user can perform dynamic pipeline configuration that follows ALPN/NPN for any protocols.
Related: #3641 and #3813
Motivation:
When setting up an HTTP/1 or HTTP/2 (or SPDY) pipeline, a user usually
ends up with adding arbitrary set of handlers.
Http2OrHttpChooser and SpdyOrHttpChooser have two abstract methods
(create*Handler()) that expect a user to return a single handler, and
also have add*Handlers() methods that add the handler returned by
create*Handler() to the pipeline as well as the pre-defined set of
handlers.
The problem is, some users (read: I) don't need all of them or the
user wants to add more than one handler. For example, take a look at
io.netty.example.http2.tiles.Http2OrHttpHandler, which works around
this issue by overriding addHttp2Handlers() and making
createHttp2RequestHandler() a no-op.
Modifications:
- Replace add*Handlers() and create*Handler() with configure*()
- Rename getProtocol() to selectProtocol() to make what it does clear
- Provide the default implementation of selectProtocol()
- Remove SelectedProtocol.UNKNOWN and use null instead, because
'UNKNOWN' is not a protocol
- Proper exception handling in the *OrHttpChooser so that the
exception is logged and the connection is closed when failed to
select a protocol
- Make SpdyClient example always use SSL. It was always using SSL
anyway.
- Implement SslHandshakeCompletionEvent.toString() for debuggability
- Remove an orphaned class: JettyNpnSslSession
- Add SslHandler.applicationProtocol() to get the name of the
application protocol
- SSLSession.getProtocol() now returns transport-layer protocol name
only, so that it conforms to its contract.
Result:
- *OrHttpChooser have better API.
- *OrHttpChooser handle protocol selection failure properly.
- SSLSession.getProtocol() now conforms to its contract.
- SpdyClient example works with SpdyServer example out of the box
Motivation:
Found a bug in that netty would generate a 20 byte body when returing a response
to an HTTP HEAD. the 20 bytes seems to be related to the compression footer.
RFC2616, section 9.4 states that responses to an HTTP HEAD MUST not return a message
body in the response.
Netty's own client implementation expected an empty response. The extra bytes lead to a
2nd response with an error decoder result:
java.lang.IllegalArgumentException: invalid version format: 14
Modifications:
Track the HTTP request method. When processing the response we determine if the response
is passthru unnchanged. This decision now takes into account the request method and passthru
responses related to HTTP HEAD requests.
Result:
Netty's http client works and better RFC conformance.
Motivation:
* Path attribute should be null, not empty String, if it's passed as "Path=".
* Only extract attribute value when the name is recognized.
* Only extract Expires attribute value String if MaxAge is undefined as it has precedence.
Modification:
Modify ClientCookieDecoder.
Add "testIgnoreEmptyPath" test in ClientCookieDecoderTest.
Result:
More idyomatic Path behavior (like Domain).
Minor performance improvement in some corner cases.
Motivations:
When using HttpPostRequestEncoder and trying to set an attribute if a
charset is defined, currenlty implicit Charset.toStrng() is used, given
wrong format.
As in Android for UTF-16 = "com.ibm.icu4jni.charset.CharsetICU[UTF-16]".
Modifications:
Each time charset is used to be printed as its name, charset.name() is
used to get the canonical name.
Result:
Now get "UTF-16" instead.
(3.10 version)
RFC6265 specifies which characters are allowed in a cookie name and value.
Netty is currently too lax, which can used for HttpOnly escaping.
Modification:
In ServerCookieDecoder: discard cookie key-value pairs that contain invalid characters.
In ClientCookieEncoder: throw an exception when trying to encode cookies with invalid characters.
Result:
The problem described in the motivation section is fixed.
Motivation:
Our automatically handling of non-auto-read failed because it not detected the need of calling read again by itself if nothing was decoded. Beside this handling of non-auto-read never worked for SslHandler as it always triggered a read even if it decoded a message and auto-read was false.
This fixes [#3529] and [#3587].
Modifications:
- Implement handling of calling read when nothing was decoded (with non-auto-read) to ByteToMessageDecoder again
- Correctly respect non-auto-read by SslHandler
Result:
No more stales and correctly respecting of non-auto-read by SslHandler.
Motivation:
Other implementations of FullHttpMessage allow .toString to be called after the Message has been released
This brings AggregatedFullHttpMessage into line with those impls.
Modifications:
- Changed AggregatedFullHttpMessage to no longer be a sub-class of DefaultByteBufHolder
- Changes AggregatedFullHttpMessage to implement ByteBufHolder
- Hold the content buffer internally to AggregatedFullHttpMessage
- Implement the required content() and release() methods that were missing
- Do not check refcnt when accessing content() (similar to DefaultFullHttpMessage)
Result:
A released AggregatedFullHttpMessage can have .toString called without throwing an exception
Motivation:
While forward porting https://github.com/netty/netty/pull/3579 there were a few areas that had not been previously back ported.
Modifications:
Backport the missed areas to ensure consistency.
Result:
More consistent 4.1 and master branches.
Motivation:
The usage and code within AsciiString has exceeded the original design scope for this class. Its usage as a binary string is confusing and on the verge of violating interface assumptions in some spots.
Modifications:
- ByteString will be created as a base class to AsciiString. All of the generic byte handling processing will live in ByteString and all the special character encoding will live in AsciiString.
Results:
The AsciiString interface will be clarified. Users of AsciiString can now be clear of the limitations the class imposes while users of the ByteString class don't have to live with those limitations.
(Ported @luciferous's changes against 3.10)
Motivation:
The current implementation of the encoder writes each character of the
String as a single byte to the buffer, however not all characters are
mappable to a single byte.
Modifications:
If a character is outside the ASCII range, it's converted to '?'.
Result:
A safer encoder for String to ASCII, which substitutes unmappable
characters with'?'.
Motivation:
Not knowing which unit is used for the maxContentLength of the HttpObjectAggregator when reading the Javadoc is annoying and can be a source of bugs.
Modifications:
Added the mention "in bytes"
Result:
Javadoc is clear.
Related: #3445
Motivation:
HttpObjectDecoder.HeaderParser does not reset its counter (the size
field) when it failed to find the end of line. If a header is split
into multiple fragments, the counter is increased as many times as the
number of fragments, resulting an unexpected TooLongFrameException.
Modifications:
- Add test cases that reproduces the problem
- Reset the HeaderParser.size field when no EOL is found.
Result:
One less bug
Motivation:
Currently CORS can be configured to support a 'null' origin, which can
be set by a browser if a resources is loaded from the local file system.
When this is done 'Access-Control-Allow-Origin' will be set to "*" (any
origin). There is also a configuration option to allow credentials being
sent from the client (cookies, basic HTTP Authentication, client side
SSL). This is indicated by the response header
'Access-Control-Allow-Credentials' being set to true. When this is set
to true, the "*" origin is not valid as the value of
'Access-Control-Allow-Origin' and a browser will reject the request:
http://www.w3.org/TR/cors/#resource-requests
Modifications:
Updated CorsHandler's setAllowCredentials to check the origin and if it
is "*" then it will not add the 'Access-Control-Allow-Credentials'
header.
Result:
Is is possible to have a client send a 'null' origin, and at the same
time have configured the CORS to support that and to allow credentials
in that combination.
Motivation:
At the moment if you want to return a HTTP header containing multiple
values you have to set/add that header once with the values wanted. If
you used set/add with an array/iterable multiple HTTP header fields will
be returned in the response.
Note, that this is indeed a suggestion and additional work and tests
should be added. This is mainly to bring up a discussion.
Modifications:
Added a flag to specify that when multiple values exist for a single
HTTP header then add them as a comma separated string.
In addition added a method to StringUtil to help escape comma separated
value charsequences.
Result:
Allows for responses to be smaller.
Motivation:
To use WebSocketClientHandshaker / WebSocketServerHandshaker it's currently a requirement of having a HttpObjectAggregator in the ChannelPipeline. This is not a big deal when a user only wants to server WebSockets but is a limitation if the server serves WebSockets and normal HTTP traffic.
Modifications:
Allow to use WebSocketClientHandshaker and WebSocketServerHandshaker without HttpObjectAggregator in the ChannelPipeline.
Result:
More flexibility
Motivation:
SonarQube (clinker.netty.io/sonar) reported a resource which may not have been properly closed in all situations in AbstractDiskHttpData.
Modifications:
- Ensure file channels are closed in the presence of exceptions.
- Correct instances where local channels were created but potentially not closed.
Result:
Less leaks. Less SonarQube vulnerabilities.
Motivation:
`HttpResponseDecoder` and `HttpRequestDecoder` in the event when the max configured sizes for HTTP initial line, headers or content is breached, sends a `DefaultHttpResponse` and `DefaultHttpRequest` respectively. After this `HttpObjectDecoder` gets into `BAD_MESSAGE` state and ignores any other data received on this connection.
The combination of the above two behaviors, means that the decoded response/request are not complete (absence of sending `LastHTTPContent`). So, any code, waiting for a complete message will have to additionally check for decoder result to follow the correct semantics of HTTP.
If `HttpResponseDecoder` and `HttpRequestDecoder` creates a Full* invalid message then the request/response is a complete HTTP message and hence obeys the HTTP contract.
Modification:
Modified `HttpRequestDecoder`, `HttpResponseDecoder`, `RtspRequestDecoder` and `RtspResponseDecoder` to return Full* messages from `createInvalidMessage()`
Result:
Fixes the wrong behavior of sending incomplete messages from these codecs
In testEncodingSingleCookieV0():
Let's assume we encoded a cookie with MaxAge=50 when currentTimeMillis
is 10999.
Because the encoder will not encode the millisecond part for Expires,
the timeMillis value of the encoded Expires field will be 60000. (If we
did not dropped the millisecond part, it would be 60999.)
Encoding a cookie will take some time, so currentTimeMillis will
increase slightly, such as to 11001.
diff = (60000 - 11001) / 1000 = 48999 / 1000 = 48
maxAge - diff = 50 - 48 = 2
Due to losing millisecond part twice, we end up with the precision
problem illustrated above, and thus we should increase the tolerance
from 1 second to 2 seconds.
/cc @slandelle
Motivation:
Internet Explorer doesn't honor Set-Cookie header Max-Age attribute. It only honors the Expires one.
Modification:
Always generate an Expires attribute along the Max-Age one.
Result:
Internet Explorer compatible expiring cookies. Close#1466.
Motivation:
HTTP/2 codec was implemented in master branch.
Since, master is not yet stable and will be some time before it gets released, backporting it to 4.1, enables people to use the codec with a stable netty version.
Modification:
The code has been copied from master branch as is, with minor modifications to suit the `ChannelHandler` API in 4.x.
Apart from that change, there are two backward incompatible API changes included, namely,
- Added an abstract method:
`public abstract Map.Entry<CharSequence, CharSequence> forEachEntry(EntryVisitor<CharSequence> visitor)
throws Exception;`
to `HttpHeaders` and implemented the same in `DefaultHttpHeaders` as a delegate to the internal `TextHeader` instance.
- Added a method:
`FullHttpMessage copy(ByteBuf newContent);`
in `FullHttpMessage` with the implementations copied from relevant places in the master branch.
- Added missing abstract method related to setting/adding short values to `HttpHeaders`
Result:
HTTP/2 codec can be used with netty 4.1
Motivation:
HttpContentDecoder had the following issues:
- For chunked content, the decoder set invalid "Content-Length" header
with length of the first decoded chunk.
- Decoding of FullHttpRequests put both the original conent and decoded
content into output. As result, using HttpObjectAggregator before the
decoder lead to errors.
- Requests with "Expect: 100-continue" header were not acknowleged:
the decoder didn't pass the header message down the handler's chain
until content is received. If client expected "100 Continue" response,
deadlock happened.
Modification:
- Invalid "Content-Length" header is removed; handlers down the chain can either
rely on LastHttpContent message or ask HttpObjectAggregator to add the header.
- FullHttpRequest is split into HttpRequest and HttpContent (decoded) parts.
- Header (HttpRequest) part of request is sent down the chain as soon as it's received.
Result:
The issues are fixed, unittest is added.
Motivation:
Pull request for RFC6265 support had some unused flag first in ClientCookieDecoder.
Modification:
Remove unused flag first.
Result:
Cleaner code.
Motivation:
Rfc6265Client/ServerCookieEncoder is a better replacement of the old
Client/ServerCookieEncoder, and thus there's no point of keeping both.
Modifications:
- Remove the old Client/ServerCookieEncoder
- Remove the 'Rfc6265' prefix from the new cookie encoder/decoder
classes
- Deprecate CookieDecoder
Result:
We have much better cookie encoder/decoder implementation now.
Motivation:
Currently Netty supports a weird implementation of RFC 2965.
First, this RFC has been deprecated by RFC 6265 and nobody on the
internet use this format.
Then, there's a confusion between client side and server side encoding
and decoding.
Typically, clients should only send name=value pairs.
This PR introduces RFC 6265 support, but keeps on supporting RFC 2965 in
the sense that old unused fields are simply ignored, and Cookie fields
won't be populated. Deprecated fields are comment, commentUrl, version,
discard and ports.
It also provides a mechanism for safe server-client-server roundtrip, as
User-Agents are not supposed to interpret cookie values but return them
as-is (e.g. if Set-Cookie contained a quoted value, it should be sent
back in the Cookie header in quoted form too).
Also, there are performance gains to be obtained by not allocating the
attribute name Strings, as we only want to match them to find which POJO
field to populate.
Modifications:
- New RFC6265ClientCookieEncoder/Decoder and
RFC6265ServerCookieEncoder/Decoder pairs that live alongside old
CookieEncoder/Decoder pair to not break backward compatibility.
- New Cookie.rawValue field, used for lossless server-client-server
roundtrip.
Result:
RFC 6265 support.
Clean separation of client and server side.
Decoder performance gain:
Benchmark Mode Samples Score Error
Units
parseOldClientDecoder thrpt 20 2070169,228 ± 105044,970
ops/s
parseRFC6265ClientDecoder thrpt 20 2954015,476 ± 126670,633
ops/s
This commit closes#3221 and #1406.
Motivation:
HttpPostMultipartRequestDecoder threw an ArrayIndexOutOfBoundsException
when trying to decode Content-Disposition header with filename
containing ';' or protected \\".
See issue #3326 and #3327.
Modifications:
Added splitMultipartHeaderValues method which cares about quotes, and
use it in splitMultipartHeader method, instead of StringUtils.split.
Result:
Filenames can contain semicolons and protected \\".
Motivation:
HttpResponseStaus, HttpMethod and HttpVersion have methods that return
AsciiString. There's no need for object-to-string conversion.
Modifications:
Use codeAsText(), name(), text() instead of setInt() and setObject()
Result:
Efficiency
Motivation:
The SpdyHttpDecoder was modified to support pushed resources that are
divided into multiple frames. The decoder accepts a pushed
SpdySynStreamFrame containing the request headers, followed by a
SpdyHeadersFrame containing the response headers.
Modifications:
This commit modifies the SpdyHttpEncoder so that it encodes pushed
resources in a format that the SpdyHttpDecoder can decode. The encoder
will accept an HttpRequest object containing the request headers,
followed by an HttpResponse object containing the response headers.
Result:
The SpdyHttpEncoder will create a SpdySynStreamFrame followed by a
SpdyHeadersFrame when sending pushed resources.
Motivations:
It seems that slicing a buffer and using this slice to write to CTX will
decrease the initial refCnt to 0, while the original buffer is not yet
fully used (not empty).
Modifications:
As suggested in the ticket and tested, when the currentBuffer is sliced
since it will still be used later on, the currentBuffer is retained.
Add a test case for this issue.
Result:
The currentBuffer still has its correct refCnt when reaching the last
write (not sliced) of 1 and therefore will be released correctly.
The exception does no more occur.
This fix should be applied to all branches >= 4.0.
When handling an oversized message, HttpObjectAggregator does not wait
until the last chunk is received to produce the failed message, making
AggregatedFullHttpMessage.trailingHeaders() return null.
Related: #3019
Motivation:
We have multiple (Full)HttpRequest/Response implementations and only
some of them implements toString() properly.
Modifications:
- Add the reusable string converter for HttpMessages to HttpMessageUtil
- Implement toString() of (Full)HttpRequest/Response implementations
properly using HttpMessageUtil
Result:
Prettier string representation is returned by HttpMessage
implementations.
Motivation:
Even if its against the HTTP RFC there are situations where it may be useful to use other chars then US_ASCII in the headers. We should allow to make it possible by allow the user to override the how headers are encoded.
Modifications:
- Add encodeHeaders(...) method and so allow to override it.
Result:
It's now possible to encode headers with other charset then US_ASCII by just extend the encoder and override the encodeHeaders(...) method.
Motivation:
HEAD requests will have a Content-Length set that doesn't match the
actual length. So we only want to set Content-Length header if it isn't
already set.
Modifications:
If check around setting the Content-Length.
Result:
A HEAD request will no correctly return the specified Content-Length
instead of the body length.
