Apache Traffic Server SPDY Protocol Plugin

A SPDY protocol plugin for Apache Traffic Server. This plugin implements the SPDY/2 protocol and transforms incoming SPDY client requests to HTTP/1.1 origin server requests.

Installation and Configuration

To install, copy spdy.so into the TrafficServer plugins directory and add the following to plugin.config:

spdy.so [OPTIONS]

The SPDY plugin will automatically listen on the SPDY/2 NPN endpoint for all configure SSL ports. I used to have an option in there to listen on an arbitrary non-SSL port, which is useful for debugging. It's pretty easy to add that back in and I'll probably do that.

Options:

• --system-resolver: Use the system's DNS resolver instead of the Traffic Server DNS resolver. This has the advantage of being able to resolve Bonjour names and /etc/hosts entries and the disadvantage of being a blocking API that will hold down a Traffic Server thread.

To enable debug, configure the spdy diagnostic tags by adding the following to recods.config:

CONFIG proxy.config.diags.debug.tags STRING spdy.*

Valid SPDY debugging tags are:

• spdy.protocol: SPDY protocol logging
• spdy.plugin: SPDY plugin lifecycle
• spdy.http: HTTP client request processing

Plugin Status

The plugin implements SPDY/2. It's unlikely to ever support SPDY/3, but probably I'll get around to SPDY/4 at some point.

This has only every been built and tested on Mac OS X. It compiles and basically works for me, but there's a lot of rough edges and it needs a good kicking before going into production. That said, patches are gleefully accepted.

HTTP Semantics

301 Moved Permanently

Currently, we just return whatever response the server sends us. This seems like the right thing to do and none of the SPDY specifications suggest doing otherwise. However, Chrome does not actually follow redirections that come via the SPDY channel. It's a pretty atrocious user experience to have to manually deal with redirections.

Testing with Google Chrome

Use the following command-line to have Chrome proxy all requests through the SPDY proxy at localhost:9999:

chrome --use-spdy=no-ssl --host-resolver-rules="MAP * localhost:9999"

Resources

• http://mbelshe.github.com/SPDY-Specification/draft-mbelshe-spdy-00.xml
• http://www.chromium.org/spdy/spdy-protocol/spdy-protocol-draft2
• http://www.chromium.org/spdy/spdy-tools-and-debugging
• http://technotes.googlecode.com/git/nextprotoneg.html

To Do

• A raw memory container that we can decompress bytes straight into. TSIOBuffer() is too coupled to the ATS IO implementation to be nice and generic, and std::vector zeros when you resize so you can't combine capacity() and size() nicely.

• SPDY protocol versioning. SPDY/2 and SPDY/3 are incompatible in a number of ways (eg. SPDY/3 widens some fields to 32bits).

• Err, protocol error handling. That would help.

• Implement request caching using TSCacheRead() and TSCacheWrite().

• Support host:port specification by parsing the port from the SPDY host header.