python on Ikoma's Bloghttps://blog.yusukeikoma.com/tags/python/Recent content in python on Ikoma's BlogHugoen-usMon, 05 Oct 2026 13:20:23 +0900UDP connect() Sends Nothing, and getsockname() Gives You Your Local IPhttps://blog.yusukeikoma.com/posts/udp-connect-local-ip/Mon, 05 Oct 2026 13:20:23 +0900https://blog.yusukeikoma.com/posts/udp-connect-local-ip/A machine with Wi-Fi, a VPN and a container bridge has several addresses, and a hostname lookup can return the wrong one. Connecting a UDP socket to a destination makes the kernel pick the source address it would use, and getsockname() reads it back without a single packet being sent. Checked on Linux with three interfaces: five destinations, five answers, no IPv4 or ARP frames on the wire.Hardening a Go Daemon and a Python APIhttps://blog.yusukeikoma.com/posts/go-daemon-and-python-api-hardening/Sat, 01 Aug 2026 14:11:31 +0900https://blog.yusukeikoma.com/posts/go-daemon-and-python-api-hardening/Five techniques from a polyglot codebase: rolling out golangci-lint on existing Go code, running the race detector in CI, bounding subprocess lifetimes, re-registering launchd services without the bootout race, and choosing PostgreSQL row-lock strength around foreign keys.