Since commit b3fabedec, the bridge driver maps ports following a 3-step
process: 1. create a socket, and bind it to the host port; 2. create
iptables rules; 3. start the userland proxy (if it's enabled). This
ensures that the port is really free before inserting iptables rules
that could otherwise disrupt host services.
However, this 3-step process wasn't implemented for SCTP, because we had
no way to instiantiate an SCTP listener from an fd. Since
github.com/ishidawataru/sctp@4719921f9, we can.
Signed-off-by: Albin Kerouanton <albinker@gmail.com>
In preparation for the daemon passing a listen fd, add command line
option -use-listen-fd to indicate that the fd is present (as fd 4).
If the new flag isn't given, open the listener as normal.
Refactor the TCP and UDP proxies to be constructed with an existing
TCPListener or UDPConn, respectively. Lift the responsibilty of opening
the listener to the entrypoint. Per the Single Responsibility Principle,
this structure affords changing how the listener is created without
having to touch the proxy implementations.
Co-authored-by: Cory Snider <csnider@mirantis.com>
Signed-off-by: Rob Murray <rob.murray@docker.com>
