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feat: Windows DNS configuration via netsh (#28)

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* feat: Windows DNS configuration via netsh

numa install/uninstall now set/restore system DNS on Windows via
netsh. Parses ipconfig /all per-interface (adapter name, DHCP status,
DNS servers), saves backup to %APPDATA%\numa\original-dns.json, and
restores on uninstall (DHCP or static with secondary servers).

Handles localization (German adapter/DHCP/DNS labels), disconnected
adapters, multiple interfaces, and missing admin privileges. Adds IP
validation to discover_windows() for consistency.

No Windows Service or CA trust yet — user runs numa in a terminal.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* ci: add cargo test to Windows CI job

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* ci: upload Windows binary as artifact for testing

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: SRTT decay tests panic on Windows due to Instant underflow

On Windows, Instant starts near boot time — subtracting large
durations panics. Use checked_sub with a process-start fallback.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: SRTT decay tests use binary search for max Instant age

Replace age() helper with set_age_secs() on SrttCache that
binary-searches for the maximum subtractable duration. Prevents
panic on Windows (Instant starts at boot) while still producing
the oldest representable instant for correct decay calculations.

Also removes ephemeral test-ubuntu.sh from git.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: use ProgramData for Windows DNS backup path

APPDATA differs between user and admin contexts — install runs as
admin but uninstall might resolve a different APPDATA. Use
ProgramData which is consistent across elevation contexts.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* feat: disable Dnscache on Windows install, re-enable on uninstall

Windows DNS Client (Dnscache) holds port 53 at kernel level and
can't be stopped via sc/net stop. Disable via registry during
install (requires reboot), re-enable on uninstall.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: rewrite SRTT decay tests as pure functions

Decay tests manipulated Instant timestamps which panics on Windows
(Instant can't go before boot time). Rewrite to test decay_for_age()
directly — a pure function taking srtt_ms and age_secs, no platform
dependency.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: use Quad9 IP (9.9.9.9) for DoH fallback, not hostname

DoH to dns.quad9.net requires DNS to resolve the hostname, which
creates a chicken-and-egg loop when numa IS the system resolver
(e.g. after numa install on Windows). Using the IP directly avoids
the bootstrap dependency.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* refactor: extract DOH_FALLBACK constant

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* refactor: extract QUAD9_IP constant

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* refactor: remove dead test helpers, fix constant placement

Remove unused get_srtt_ms() and saturated_penalty_cache() left over
from SRTT test rewrite. Move QUAD9_IP/DOH_FALLBACK after use block.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: ignore ConnectionReset on UDP socket (Windows ICMP error)

Windows delivers ICMP port-unreachable as ConnectionReset on the
next UDP recv_from, crashing numa. Linux/macOS silently ignore these.
Catch and continue the recv loop.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* feat: auto-start numa on Windows boot via registry Run key

Without a Windows Service, rebooting after numa install leaves DNS
broken (pointing at 127.0.0.1 with nothing listening). Register
numa in HKLM\...\Run so it starts automatically. Removed on
uninstall.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* docs: update README, Windows plan, and launch drafts for Windows support

- README: platform-specific Quick Start, install/uninstall table
- Windows plan: Phase 2 complete, Phase 3 scoped
- Launch drafts: updated "Does it support Windows?" response

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* chore: remove docs from git tracking (already gitignored)

docs/ is in .gitignore but files were force-added. Remove from
tracking — files remain on disk.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
This commit is contained in:
Razvan Dimescu
2026-04-01 18:17:52 +03:00
committed by GitHub
parent 7f46f6271e
commit 0b883d1c0d
5 changed files with 475 additions and 76 deletions
Download Patch File Download Diff File Expand all files Collapse all files

399
src/system_dns.rs
View File

@@ -334,7 +334,7 @@ fn discover_windows() -> SystemDnsInfo {
if trimmed.contains("DNS Servers") || trimmed.contains("DNS-Server") {
if let Some(ip) = trimmed.split(':').next_back() {
let ip = ip.trim();
if !is_loopback_or_stub(ip) {
if ip.parse::<std::net::IpAddr>().is_ok() && !is_loopback_or_stub(ip) {
upstream = Some(ip.to_string());
break;
}
@@ -358,6 +358,339 @@ fn discover_windows() -> SystemDnsInfo {
}
}
#[cfg(any(windows, test))]
#[derive(serde::Serialize, serde::Deserialize, Debug, PartialEq)]
struct WindowsInterfaceDns {
dhcp: bool,
servers: Vec<String>,
}
#[cfg(any(windows, test))]
fn parse_ipconfig_interfaces(text: &str) -> std::collections::HashMap<String, WindowsInterfaceDns> {
let mut interfaces = std::collections::HashMap::new();
let mut current_adapter: Option<String> = None;
let mut current_dhcp = false;
let mut current_dns: Vec<String> = Vec::new();
let mut in_dns_block = false;
let mut disconnected = false;
for line in text.lines() {
let trimmed = line.trim();
// Adapter section headers start at column 0
if !trimmed.is_empty() && !line.starts_with(' ') && !line.starts_with('\t') {
if let Some(name) = current_adapter.take() {
if !disconnected {
interfaces.insert(
name,
WindowsInterfaceDns {
dhcp: current_dhcp,
servers: std::mem::take(&mut current_dns),
},
);
}
current_dns.clear();
}
in_dns_block = false;
current_dhcp = false;
disconnected = false;
// "XXX adapter YYY:" (English) / "XXX Adapter YYY:" (German)
let lower = trimmed.to_lowercase();
if let Some(pos) = lower.find(" adapter ") {
let after = &trimmed[pos + " adapter ".len()..];
let name = after.trim_end_matches(':').trim();
if !name.is_empty() {
current_adapter = Some(name.to_string());
}
}
} else if current_adapter.is_some() {
if trimmed.contains("Media disconnected") || trimmed.contains("Medienstatus") {
disconnected = true;
} else if trimmed.contains("DHCP") && trimmed.contains(". .") {
current_dhcp = trimmed
.split(':')
.next_back()
.map(|v| {
let v = v.trim().to_lowercase();
v == "yes" || v == "ja"
})
.unwrap_or(false);
in_dns_block = false;
} else if trimmed.contains("DNS Servers") || trimmed.contains("DNS-Server") {
in_dns_block = true;
if let Some(ip) = trimmed.split(':').next_back() {
let ip = ip.trim();
if ip.parse::<std::net::IpAddr>().is_ok() {
current_dns.push(ip.to_string());
}
}
} else if in_dns_block {
if trimmed.parse::<std::net::IpAddr>().is_ok() {
current_dns.push(trimmed.to_string());
} else {
in_dns_block = false;
}
}
}
}
if let Some(name) = current_adapter {
if !disconnected {
interfaces.insert(
name,
WindowsInterfaceDns {
dhcp: current_dhcp,
servers: current_dns,
},
);
}
}
interfaces
}
#[cfg(windows)]
fn get_windows_interfaces() -> Result<std::collections::HashMap<String, WindowsInterfaceDns>, String>
{
let output = std::process::Command::new("ipconfig")
.arg("/all")
.output()
.map_err(|e| format!("failed to run ipconfig /all: {}", e))?;
let text = String::from_utf8_lossy(&output.stdout);
Ok(parse_ipconfig_interfaces(&text))
}
#[cfg(windows)]
fn windows_backup_path() -> std::path::PathBuf {
// Use ProgramData (not APPDATA) since install requires admin elevation
// and APPDATA differs between user and admin contexts.
std::path::PathBuf::from(
std::env::var("PROGRAMDATA").unwrap_or_else(|_| "C:\\ProgramData".into()),
)
.join("numa")
.join("original-dns.json")
}
#[cfg(windows)]
fn disable_dnscache() -> Result<bool, String> {
// Check if Dnscache is running (it holds port 53 at kernel level)
let output = std::process::Command::new("sc")
.args(["query", "Dnscache"])
.output()
.map_err(|e| format!("failed to query Dnscache: {}", e))?;
let text = String::from_utf8_lossy(&output.stdout);
if !text.contains("RUNNING") {
return Ok(false);
}
eprintln!(" Disabling DNS Client (Dnscache) to free port 53...");
// Dnscache can't be stopped via sc/net stop — must disable via registry
let status = std::process::Command::new("reg")
.args([
"add",
"HKLM\\SYSTEM\\CurrentControlSet\\Services\\Dnscache",
"/v",
"Start",
"/t",
"REG_DWORD",
"/d",
"4",
"/f",
])
.status()
.map_err(|e| format!("failed to disable Dnscache: {}", e))?;
if !status.success() {
return Err("failed to disable Dnscache via registry (run as Administrator?)".into());
}
eprintln!(" Dnscache disabled. A reboot is required to free port 53.");
Ok(true)
}
#[cfg(windows)]
fn enable_dnscache() {
let _ = std::process::Command::new("reg")
.args([
"add",
"HKLM\\SYSTEM\\CurrentControlSet\\Services\\Dnscache",
"/v",
"Start",
"/t",
"REG_DWORD",
"/d",
"2",
"/f",
])
.status();
}
#[cfg(windows)]
fn install_windows() -> Result<(), String> {
let interfaces = get_windows_interfaces()?;
if interfaces.is_empty() {
return Err("no active network interfaces found".to_string());
}
let path = windows_backup_path();
if let Some(parent) = path.parent() {
std::fs::create_dir_all(parent)
.map_err(|e| format!("failed to create {}: {}", parent.display(), e))?;
}
let json = serde_json::to_string_pretty(&interfaces)
.map_err(|e| format!("failed to serialize backup: {}", e))?;
std::fs::write(&path, json).map_err(|e| format!("failed to write backup: {}", e))?;
for name in interfaces.keys() {
let status = std::process::Command::new("netsh")
.args([
"interface",
"ipv4",
"set",
"dnsservers",
name,
"static",
"127.0.0.1",
"primary",
])
.status()
.map_err(|e| format!("failed to set DNS for {}: {}", name, e))?;
if status.success() {
eprintln!(" set DNS for \"{}\" -> 127.0.0.1", name);
} else {
eprintln!(
" warning: failed to set DNS for \"{}\" (run as Administrator?)",
name
);
}
}
let needs_reboot = disable_dnscache()?;
register_autostart();
eprintln!("\n Original DNS saved to {}", path.display());
eprintln!(" Run 'numa uninstall' to restore.\n");
if needs_reboot {
eprintln!(" *** Reboot required. Numa will start automatically. ***\n");
} else {
eprintln!(" Numa will start automatically on next boot.\n");
}
eprintln!(" Want full DNS sovereignty? Add to numa.toml:");
eprintln!(" [upstream]");
eprintln!(" mode = \"recursive\"\n");
Ok(())
}
/// Register numa to auto-start on boot via registry Run key.
#[cfg(windows)]
fn register_autostart() {
let exe = std::env::current_exe()
.map(|p| p.to_string_lossy().to_string())
.unwrap_or_else(|_| "numa".into());
let _ = std::process::Command::new("reg")
.args([
"add",
"HKLM\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Run",
"/v",
"Numa",
"/t",
"REG_SZ",
"/d",
&exe,
"/f",
])
.status();
eprintln!(" Registered auto-start on boot.");
}
/// Remove numa auto-start registry key.
#[cfg(windows)]
fn remove_autostart() {
let _ = std::process::Command::new("reg")
.args([
"delete",
"HKLM\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Run",
"/v",
"Numa",
"/f",
])
.status();
}
#[cfg(windows)]
fn uninstall_windows() -> Result<(), String> {
remove_autostart();
let path = windows_backup_path();
let json = std::fs::read_to_string(&path)
.map_err(|e| format!("no backup found at {}: {}", path.display(), e))?;
let original: std::collections::HashMap<String, WindowsInterfaceDns> =
serde_json::from_str(&json).map_err(|e| format!("invalid backup file: {}", e))?;
for (name, dns_info) in &original {
if dns_info.dhcp || dns_info.servers.is_empty() {
let status = std::process::Command::new("netsh")
.args(["interface", "ipv4", "set", "dnsservers", name, "dhcp"])
.status()
.map_err(|e| format!("failed to restore DNS for {}: {}", name, e))?;
if status.success() {
eprintln!(" restored DNS for \"{}\" -> DHCP", name);
} else {
eprintln!(" warning: failed to restore DNS for \"{}\"", name);
}
} else {
let status = std::process::Command::new("netsh")
.args([
"interface",
"ipv4",
"set",
"dnsservers",
name,
"static",
&dns_info.servers[0],
"primary",
])
.status()
.map_err(|e| format!("failed to restore DNS for {}: {}", name, e))?;
if !status.success() {
eprintln!(" warning: failed to restore primary DNS for \"{}\"", name);
continue;
}
for (i, server) in dns_info.servers.iter().skip(1).enumerate() {
let _ = std::process::Command::new("netsh")
.args([
"interface",
"ipv4",
"add",
"dnsservers",
name,
server,
&format!("index={}", i + 2),
])
.status();
}
eprintln!(
" restored DNS for \"{}\" -> {}",
name,
dns_info.servers.join(", ")
);
}
}
std::fs::remove_file(&path).ok();
// Re-enable Dnscache
enable_dnscache();
eprintln!("\n System DNS restored. DNS Client re-enabled.");
eprintln!(" Reboot to fully restore the DNS Client service.\n");
Ok(())
}
/// Find the upstream for a domain by checking forwarding rules.
/// Returns None if no rule matches (use default upstream).
/// Zero-allocation on the hot path — dot_suffix is pre-computed.
@@ -522,7 +855,9 @@ pub fn install_service() -> Result<(), String> {
let result = install_service_macos();
#[cfg(target_os = "linux")]
let result = install_service_linux();
#[cfg(not(any(target_os = "macos", target_os = "linux")))]
#[cfg(windows)]
let result = install_windows();
#[cfg(not(any(target_os = "macos", target_os = "linux", windows)))]
let result = Err::<(), String>("service installation not supported on this OS".to_string());
if result.is_ok() {
@@ -546,7 +881,11 @@ pub fn uninstall_service() -> Result<(), String> {
{
uninstall_service_linux()
}
#[cfg(not(any(target_os = "macos", target_os = "linux")))]
#[cfg(windows)]
{
uninstall_windows()
}
#[cfg(not(any(target_os = "macos", target_os = "linux", windows)))]
{
Err("service uninstallation not supported on this OS".to_string())
}
@@ -1027,3 +1366,57 @@ fn untrust_ca() -> Result<(), String> {
let _ = ca_path; // suppress unused warning on other platforms
Ok(())
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn parse_ipconfig_dhcp_and_static() {
let sample = "\
Ethernet adapter Ethernet:
DHCP Enabled. . . . . . . . . . . : Yes
DNS Servers . . . . . . . . . . . : 8.8.8.8
8.8.4.4
Wireless LAN adapter Wi-Fi:
DHCP Enabled. . . . . . . . . . . : No
DNS Servers . . . . . . . . . . . : 1.1.1.1
";
let result = parse_ipconfig_interfaces(sample);
assert_eq!(result.len(), 2);
assert_eq!(
result["Ethernet"],
WindowsInterfaceDns {
dhcp: true,
servers: vec!["8.8.8.8".into(), "8.8.4.4".into()],
}
);
assert_eq!(
result["Wi-Fi"],
WindowsInterfaceDns {
dhcp: false,
servers: vec!["1.1.1.1".into()],
}
);
}
#[test]
fn parse_ipconfig_skips_disconnected() {
let sample = "\
Ethernet adapter Ethernet 2:
Media State . . . . . . . . . . . : Media disconnected
Wireless LAN adapter Wi-Fi:
DHCP Enabled. . . . . . . . . . . : Yes
DNS Servers . . . . . . . . . . . : 192.168.1.1
";
let result = parse_ipconfig_interfaces(sample);
assert_eq!(result.len(), 1);
assert!(result.contains_key("Wi-Fi"));
}
}