Fix interfaces() on Windows when ipconfig is missing#1
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Some Windows systems don't have ipconfig.exe on PATH, which
caused System.cmd("ipconfig", []) to crash and made
interfaces() return an empty MapSet. As a result, NetworkMonitor
saw all interfaces as down and downstream code (like direct P2P
connections) couldn't get a usable local address.
- Try the cross-platform :inet.getifaddrs/0 first on Windows
(no subprocess required).
- Only fall back to parsing 'ipconfig' output if that returns
nothing usable, and resolve the binary via System32 absolute
paths (using %SystemRoot% / %WINDIR% and the canonical
C:\Windows path) before trying the bare "ipconfig" lookup.
- Use System.find_executable/1 so a missing binary returns nil
instead of raising.
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Code Review
This pull request improves network interface detection on Windows by prioritizing the cross-platform :inet.getifaddrs/0 function, which avoids spawning a subprocess. It also enhances the fallback mechanism by searching for the ipconfig.exe binary in common system directories (e.g., System32) if it is not available in the system PATH. I have no feedback to provide.
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Problem
Some Windows systems don't have
ipconfig.exeonPATH. When that happens,NetworkMonitor.interfaces/0calls:…which raises
ErlangError, the GenServer crashes duringstart/2→interfaces/0, and downstream code (e.g. NIC change detection, direct P2P connections in DiodeClient) can't see any interfaces.Tracked alongside diodechain/ddrive#930.
Fix
:inet.getifaddrs/0first (no subprocess required, supported on Windows).ipconfigoutput if:inet.getifaddrs/0returns nothing usable.%SystemRoot%\System32\ipconfig.exe(and the canonicalC:\Windows\System32\ipconfig.exepath) before trying the bare"ipconfig"lookup, usingSystem.find_executable/1so a missing binary returnsnilinstead of raising.Behavior on Linux/macOS is unchanged.