From: Christoph Paasch <cpaa...@apple.com> Date: Fri, 14 Dec 2018 14:40:02 -0800
> Currently, TFO only allows a single TFO-secret. This means that whenever > the secret gets changed for key-rotation purposes, all the previously > issued TFO-cookies become invalid. This means that clients will fallback > to "regular" TCP, incurring a cost of one additional round-trip. > > This patchset introduces a TFO key-pool that allows to more gracefully > change the key. The size of the pool is 2 (this could be changed in the > future through a sysctl if needed). When a client connects with an "old" > TFO cookie, the server will now accept the data in the SYN and at the > same time announce a new TFO-cookie to the client. > > We have seen a significant reduction of LINUX_MIB_TCPFASTOPENPASSIVEFAIL > thanks to these patches. Invalid cookies are now solely observed when > clients behind a NAT are getting a new public IP. Yuchung and Eric, please review.
