getaddrinfo() blocks indefinitely when DNS query times out

Goal: Apply a per‑call timeout to the getaddrinfo() function in a portable C program while correctly interpreting EAI_AGAIN (transient) and EAI_NONAME (permanent) results.

Constraints: The standard getaddrinfo() API lacks a timeout argument; blocking time is dictated by system resolver configuration (/etc/resolv.conf options on Linux, hard‑coded defaults in musl, or registry settings on Windows). Implementing a timeout therefore requires external mechanisms such as running the call in a worker thread with cancellation, using non‑blocking socket tricks, or delegating to an asynchronous DNS library. Variations in AI_ADDRCONFIG handling and thread‑cancellation safety across glibc, musl, and Windows add uncertainty.

Questions:

• What is the safest way to bound the blocking time of getaddrinfo() across glibc, musl, and Windows implementations?
• How should an application distinguish between transient (EAI_AGAIN) and permanent (EAI_NONAME) failures when a timeout wrapper is in place?
• Are there portability‑safe patterns for cancelling a thread blocked in getaddrinfo() that avoid leaking resolver‑internal locks or file descriptors?