wmantly
b2ad8f4844
Completes the mDNS local-discovery feature on Windows (was Linux-only since v2.1.2). Three parts: 1. Windows hosts override (hosts_override_windows.go): %SystemRoot%...\\hosts, CRLF-aware read/write, ipconfig /flushdns after each change. The agent runs as a SYSTEM service so elevation is a non-issue. hosts_override.go split into shared rewrite logic + platform files; the hosts tests now run the real Windows write path on CI instead of skipping. 2. Local route pinning (local_route*.go): the hosts override only fixes name resolution -- the packet path is the routing table's job. If the WG mesh tunnel is up with AllowedIPs covering the LAN (or full-tunnel 0.0.0.0/0) it swallows the direct connection. Discovery now pins a /32 host route via the owning local interface (route.exe metric 1 on Windows, ip route replace on Linux) and drops it on revert. Closes a gap in the shipped Linux path too. 3. Prompt reconnect: apply/revert signals the WS loop so it reconnects immediately instead of waiting out the 5s backoff. Route/hosts code is injectable + unit tested; go test passes natively on Windows (this machine), and linux/amd64 + windows/arm64 cross-builds are clean.
64 lines
2.1 KiB
Go
64 lines
2.1 KiB
Go
//go:build windows
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package main
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import (
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"log"
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"os"
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"strings"
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)
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// Windows hosts override (AGENT_LOCAL_DISCOVERY_SPEC.md):
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// - The hosts file lives at %SystemRoot%\System32\drivers\etc\hosts. The
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// theta-agent runs as a SYSTEM service (DESIGN-WINDOWS.md), so elevation
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// is not a blocker here -- SYSTEM can write it directly.
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// - Windows caches DNS in the DNS Client service. An edit to the hosts file
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// does not immediately change resolution until the cache is flushed, so
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// every successful change runs `ipconfig /flushdns`.
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// - Windows hosts files conventionally use CRLF line endings; the shared
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// rewrite normalizes on read and writes back with hostsEOL().
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// hostsFilePathWindows, when set (tests only), redirects hostsFilePath() at a
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// temp file so unit tests never touch the real system hosts file.
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var hostsFilePathWindows string
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// systemHostsPath resolves the real system hosts file.
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func systemHostsPath() string {
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root := os.Getenv("SystemRoot")
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if root == "" {
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root = `C:\Windows`
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}
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return root + `\System32\drivers\etc\hosts`
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}
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func hostsFilePath() string {
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if hostsFilePathWindows != "" {
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return hostsFilePathWindows
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}
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return systemHostsPath()
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}
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func hostsEOL() string { return "\r\n" }
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// flushDNSOnHostsChange invalidates the Windows DNS cache after a hosts edit.
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// No-op when a test redirected the path to a temp file -- a temp file has no
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// cached entries and running ipconfig here would just slow the tests down.
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func flushDNSOnHostsChange() {
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if hostsFilePathWindows != "" {
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return
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}
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out, err := (&SystemExecutor{}).Execute("ipconfig", "/flushdns")
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if err != nil {
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log.Printf("[local-discovery] ipconfig /flushdns failed (hosts override may not take effect immediately): %v: %s", err, strings.TrimSpace(string(out)))
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}
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}
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// setTestHostsPath points hostsFilePath() at a temp file for tests and
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// returns a restore func. Exists in both platform files so the shared test
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// code can compile everywhere.
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func setTestHostsPath(path string) (restore func()) {
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prev := hostsFilePathWindows
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hostsFilePathWindows = path
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return func() { hostsFilePathWindows = prev }
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}
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