go /
crypto /
2e74c773682f59dc50a56475f7918dd8fa6dcaf8 ssh: rewrite (re)keying logic.
Use channels and a dedicated write loop for managing the rekeying
process. This lets us collect packets to be written while a key
exchange is in progress.
Previously, the read loop ran the key exchange, and writers would
block if a key exchange was going on. If a reader wrote back a packet
while processing a read packet, it could block, stopping the read
loop, thus causing a deadlock. Such coupled read/writes are inherent
with handling requests that want a response (eg. keepalive,
opening/closing channels etc.). The buffered channels (most channels
have capacity 16) papered over these problems, but under load SSH
connections would occasionally deadlock.
Fixes #18439.
Change-Id: I7c14ff4991fa3100a5d36025125d0cf1119c471d
Reviewed-on: https://go-review.googlesource.com/35012
Run-TryBot: Han-Wen Nienhuys <hanwen@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Han-Wen Nienhuys <hanwen@google.com>
6 files changed
