Netstack always picks a random start point everytime PickEphemeralPort
is called. While this is required for UDP so that DNS requests go
out through a randomized set of ports it is not required for TCP. Infact
Linux explicitly hashes the (srcip, dstip, dstport) and a one time secret
initialized at start of the application to get a random offset. But to
ensure it doesn't start from the same point on every scan it uses a static
hint that is incremented by 2 in every call to pick ephemeral ports.
The reason for 2 is Linux seems to split the port ranges where active connects
seem to use even ones while odd ones are used by listening sockets.
This CL implements a similar strategy where we use a hash + hint to generate
the offset to start the search for a free Ephemeral port.
This ensures that we cycle through the available port space in order for
repeated connects to the same destination and significantly reduces the
chance of picking a recently released port.
PiperOrigin-RevId: 272058370
Based on the guidelines at
https://opensource.google.com/docs/releasing/authors/.
1. $ rg -l "Google LLC" | xargs sed -i 's/Google LLC.*/The gVisor Authors./'
2. Manual fixup of "Google Inc" references.
3. Add AUTHORS file. Authors may request to be added to this file.
4. Point netstack AUTHORS to gVisor AUTHORS. Drop CONTRIBUTORS.
Fixes#209
PiperOrigin-RevId: 245823212
Change-Id: I64530b24ad021a7d683137459cafc510f5ee1de9
This option allows multiple sockets to be bound to the same port.
Incoming packets are distributed to sockets using a hash based on source and
destination addresses. This means that all packets from one sender will be
received by the same server socket.
PiperOrigin-RevId: 227153413
Change-Id: I59b6edda9c2209d5b8968671e9129adb675920cf
Bhasker Hariharan
gVisor bot
Adin Scannell
Michael Pratt
Andrei Vagin
Ian Gudger
Tamir Duberstein
Nicolas Lacasse
Googler