This is an experimental implementation of Google's SPDY protocol in C.
This library provides SPDY version 2 and 3 framing layer implementation. It does not perform any I/O operations. When the library needs them, it calls the callback functions provided by the application. It also does not include any event polling mechanism, so the application can freely choose the way of handling events. This library code does not depend on any particular SSL library (except for example programs which depend on OpenSSL 1.0.1 or later).
This project also develops SPDY client, server and proxy on top of Spdylay library. See SPDY Client and Server Programs section.
Most of the SPDY/2 and SPDY/3 functionality has been implemented. In both versions, the direct support of server-push has not been available yet. The application can achieve server-push using primitive APIs though.
As described below, we can create SPDY client and server with the current Spdylay API.
The following packages are needed to build the library:
- pkg-config >= 0.20
- zlib >= 1.2.3
To build and run the unit test programs, the following packages are needed:
- cunit >= 2.1
To build and run the example programs, the following packages are needed:
- OpenSSL >= 1.0.1
To enable -a option (getting linked assets from the downloaded
resouce) in spdycat (one of the example program), the following
packages are needed:
- libxml2 >= 2.7.7
To build SPDY/HTTPS to HTTP reverse proxy shrpx (one of the
example program), the following packages are needed:
- libevent-openssl >= 2.0.8
If you are using Ubuntu 12.04, you need the following packages installed:
- autoconf
- automake
- autotools-dev
- libtool
- pkg-config
- zlib1g-dev
- libcunit1-dev
- libssl-dev
- libxml2-dev
- libevent-dev
Building from git is easy, but please be sure that at least autoconf 2.68 is used:
$ autoreconf -i $ automake $ autoconf $ ./configure $ make
To build documentation, run:
$ make html
The documents will be generated under doc/manual/html/.
The generated documents will not be installed with make install.
The public API reference is available on online. Visit http://spdylay.sourceforge.net/. All public APIs are in spdylay/spdylay.h. All public API functions as well as the callback function typedefs are documented.
The src directory contains SPDY client and server implementations using Spdylay library. These programs are intended to make sure that Spdylay API is acutally usable for real implementation and also for debugging purposes. Please note that OpenSSL with NPN support is required in order to build and run these programs. At the time of this writing, the OpenSSL 1.0.1 supports NPN.
The SPDY client is called spdycat. It is a dead simple downloader
like wget/curl. It connects to SPDY server and gets resources given in
the command-line:
$ src/spdycat -h
Usage: spdycat [-Oansv23] [-t <SECONDS>] [-w <WINDOW_BITS>] [--cert=<CERT>]
[--key=<KEY>] <URI>...
OPTIONS:
-v, --verbose Print debug information such as reception/
transmission of frames and name/value pairs.
-n, --null-out Discard downloaded data.
-O, --remote-name Save download data in the current directory.
The filename is dereived from URI. If URI
ends with '/', 'index.html' is used as a
filename. Not implemented yet.
-2, --spdy2 Only use SPDY/2.
-3, --spdy3 Only use SPDY/3.
-t, --timeout=<N> Timeout each request after <N> seconds.
-w, --window-bits=<N>
Sets the initial window size to 2**<N>.
-a, --get-assets Download assets such as stylesheets, images
and script files linked from the downloaded
resource. Only links whose origins are the
same with the linking resource will be
downloaded.
-s, --stat Print statistics.
--cert=<CERT> Use the specified client certificate file.
The file must be in PEM format.
--key=<KEY> Use the client private key file. The file
must be in PEM format.
$ src/spdycat -nv https://www.google.com/
[ 0.025] NPN select next protocol: the remote server offers:
* spdy/3
* spdy/2
* http/1.1
NPN selected the protocol: spdy/3
[ 0.035] recv SETTINGS frame <version=3, flags=0, length=20>
(niv=2)
[4(1):100]
[7(0):12288]
[ 0.035] send SYN_STREAM frame <version=3, flags=1, length=106>
(stream_id=1, assoc_stream_id=0, pri=3)
:host: www.google.com
:method: GET
:path: /
:scheme: https
:version: HTTP/1.1
accept: */*
user-agent: spdylay/0.2.0
[ 0.077] recv SYN_REPLY frame <version=3, flags=0, length=558>
(stream_id=1)
:status: 302 Found
:version: HTTP/1.1
cache-control: private
content-length: 222
content-type: text/html; charset=UTF-8
date: Sun, 13 May 2012 08:02:54 GMT
location: https://www.google.co.jp/
server: gws
x-frame-options: SAMEORIGIN
x-xss-protection: 1; mode=block
[ 0.077] recv DATA frame (stream_id=1, flags=1, length=222)
[ 0.077] send GOAWAY frame <version=3, flags=0, length=8>
(last_good_stream_id=0)
SPDY server is called spdyd and serves static files. It is single
threaded and multiplexes connections using non-blocking socket. The
static files are read using blocking I/O system call, read(2). It
speaks SPDY/2 and SPDY/3:
$ src/spdyd --htdocs=/your/htdocs/ -v 3000 server.key server.crt
IPv4: listen on port 3000
IPv6: listen on port 3000
The negotiated next protocol: spdy/3
[id=1] [ 17.456] send SETTINGS frame <version=3, flags=0, length=12>
(niv=1)
[4(0):100]
[id=1] [ 17.457] recv SYN_STREAM frame <version=3, flags=1, length=108>
(stream_id=1, assoc_stream_id=0, pri=3)
:host: localhost:3000
:method: GET
:path: /README
:scheme: https
:version: HTTP/1.1
accept: */*
user-agent: spdylay/0.2.0
[id=1] [ 17.457] send SYN_REPLY frame <version=3, flags=0, length=113>
(stream_id=1)
:status: 200 OK
:version: HTTP/1.1
cache-control: max-age=3600
content-length: 15
date: Sun, 13 May 2012 08:06:12 GMT
last-modified: Tue, 17 Jan 2012 15:39:01 GMT
server: spdyd spdylay/0.2.0
[id=1] [ 17.467] send DATA frame (stream_id=1, flags=0, length=15)
[id=1] [ 17.467] send DATA frame (stream_id=1, flags=1, length=0)
[id=1] [ 17.468] stream_id=1 closed
[id=1] [ 17.468] recv GOAWAY frame <version=3, flags=0, length=8>
(last_good_stream_id=0)
[id=1] [ 17.468] closed
Currently, spdyd needs epoll or kqueue.
The shrpx is a multi-threaded reverse proxy for SPDY/HTTPS. It
converts SPDY/HTTPS traffic to plain HTTP. It can be used as SSL/SPDY
proxy with the http proxy (e.g., Squid) in the backend. To enable
SSL/SPDY proxy mode, use --spdy-proxy option. It also supports
configuration file. See --conf option and sample configuration
file shrpx.conf.sample.
We briefly describe the architecture of shrpx here. It has a
dedicated thread which listens on server sockets. When it accepted
the incoming connection, it passes the file descriptor of the incoming
connection to one of the worker thread. Each worker thread has its
own event loop and can handle many connections using non-blocking I/O.
The number of worker thread can be specified using the command-line
option. The libevent is used to handle
low-level network I/O.
Here is the command-line options:
$ src/shrpx -h
Usage: shrpx [-Dhs] [-b <HOST,PORT>] [-f <HOST,PORT>] [-n <CORES>]
[-c <NUM>] [-L <LEVEL>] [OPTIONS...]
<PRIVATE_KEY> <CERT>
shrpx --client-mode [-Dh] [-b <HOST,PORT>] [-f <HOST,PORT>]
[-n <CORES>] [-c <NUM>] [-L <LEVEL>] [OPTIONS...]
A reverse proxy for SPDY/HTTPS.
OPTIONS:
-b, --backend=<HOST,PORT>
Set backend host and port.
Default: '127.0.0.1,80'
-f, --frontend=<HOST,PORT>
Set frontend host and port.
Default: '0.0.0.0,3000'
-n, --workers=<CORES>
Set the number of worker threads.
Default: 1
-c, --spdy-max-concurrent-streams=<NUM>
Set the maximum number of the concurrent
streams in one SPDY session.
Default: 100
-L, --log-level=<LEVEL>
Set the severity level of log output.
INFO, WARNING, ERROR and FATAL.
Default: WARNING
-D, --daemon Run in a background. If -D is used, the
current working directory is changed to '/'.
-s, --spdy-proxy SSL/SPDY proxy mode.
--add-x-forwarded-for
Append X-Forwarded-For header field to the
downstream request.
--frontend-spdy-read-timeout=<SEC>
Specify read timeout for SPDY frontend
connection. Default: 180
--frontend-read-timeout=<SEC>
Specify read timeout for non-SPDY frontend
connection. Default: 180
--frontend-write-timeout=<SEC>
Specify write timeout for both SPDY and
non-SPDY frontends.
connection. Default: 60
--backend-read-timeout=<SEC>
Specify read timeout for backend connection.
Default: 900
--backend-write-timeout=<SEC>
Specify write timeout for backend
connection. Default: 60
--backend-keep-alive-timeout=<SEC>
Specify keep-alive timeout for backend
connection. Default: 60
--accesslog Print simple accesslog to stderr.
--frontend-spdy-window-bits=<N>
Sets the initial window size of SPDY
frontend connection to 2**<N>.
Default: 16
--pid-file=<PATH> Set path to save PID of this program.
--user=<USER> Run this program as USER. This option is
intended to be used to drop root privileges.
--conf=<PATH> Load configuration from PATH.
Default: /etc/shrpx/shrpx.conf
--syslog Send log messages to syslog.
--syslog-facility=<FACILITY>
Set syslog facility.
Default: daemon
--backlog=<NUM> Set listen backlog size.
Default: 256
--ciphers=<SUITE> Set allowed cipher list. The format of the
string is described in OpenSSL ciphers(1).
--client-mode Instead of accepting SPDY/HTTPS connection,
accept HTTP connection and communicate with
backend server in SPDY. This is for testing
purpose.
-h, --help Print this help.
For those of you who are curious, shrpx is an abbreviation of
"Spdy/https to Http Reverse ProXy".
Without -s option, it works in the following configuration:
Client <-- (SPDY, HTTPS) --> Shrpx <-- (HTTP) --> Web Server
With -s option, it works in the following configuration:
Client <-- (SPDY, HTTPS) --> Shrpx <-- (HTTP) --> Proxy (e.g., Squid) * Client is configured to use Shrpx as SSL/SPDY proxy.
At the time of this writing, Chrome is the only browser which supports SSL/SPDY proxy. The one way to configure Chrome to use SSL/SPDY proxy is create proxy.pac script like this:
function FindProxyForURL(url, host) {
return "HTTPS SERVERADDR:PORT";
}
SERVERADDR and PORT is the hostname/address and port of the
machine shrpx is running. Please note that Chrome requires valid
certificate for SSL/PROXY.
Then run chrome with the following arguments:
$ google-chrome --proxy-pac-url=file:///path/to/proxy.pac --use-npn
There is an interesting option --client-mode. If it is given,
shrpx accepts HTTP connections and communicates with the backend
in SPDY:
Client <-- (HTTP) --> Shrpx <-- (SPDY) --> Web Server or another Shrpx
--client-mode option is for testing purpose only.
The examples directory contains a simple SPDY client implementation in C.
The library comes with Python wrapper python-spdylay. See
python directory.