Begin forwarded message: Date: Wed, 18 Nov 2020 15:06:51 +0000 From: bugzilla-dae...@bugzilla.kernel.org To: step...@networkplumber.org Subject: [Bug 210255] New: IP_UNICAST_IF has no effect on connect()ed UDP sockets https://bugzilla.kernel.org/show_bug.cgi?id=210255 Bug ID: 210255 Summary: IP_UNICAST_IF has no effect on connect()ed UDP sockets Product: Networking Version: 2.5 Kernel Version: 5.9.0-36.fc34.x86_64 Hardware: All OS: Linux Tree: Mainline Status: NEW Severity: normal Priority: P1 Component: IPV4 Assignee: step...@networkplumber.org Reporter: mzxre...@0pointer.de Regression: No The IP_UNICAST_IF sockopt has an effect for unconnected UDP sockets, and is used as key for the route lookup. However, when using connect() on an UDP socket, then the routing decision is already done at connect() time, and unlike the routing decision for unconnected sockets the IP_UNICAST_IF sockopt is not taken into consideration then. I figure this was simply forgotten when IP_UNICAST_IF was added, but I am pretty sure this should be corrected so that connected and unconnected UDP sockets behave more alike. (SO_BINDTODEVICE/SO_BINDTOINDEX actually works on both equally, but given they do a lot more than IP_UNICAST_IF they are no replacement) (This was noticed in context of the UDP/DNS code in systemd-resolved, see this for further discussion: https://github.com/systemd/systemd/issues/11935#issuecomment-618691018) (The research on this was done by hvenev, not me, I am just propagating his findings here.) -- You are receiving this mail because: You are the assignee for the bug.
