diff --git a/README.md b/README.md index b8fc7ef..bbb84b2 100644 --- a/README.md +++ b/README.md @@ -1,33 +1,70 @@ # rtnetmon -Real-time network monitoring dashboard for Linux systems with dual-interface support. +Real-time network monitoring dashboard for Linux and macOS, with one- or +two-interface support. ## Overview rtnetmon is a terminal-based network monitoring tool that provides real-time -visibility into network health, packet loss, and latency across two network -interfaces simultaneously. It's designed for Linux systems and uses ncurses -for a clean, real-time dashboard interface. +visibility into network health, packet loss, and latency across one or two +network interfaces simultaneously. It runs on Linux and macOS and uses a +terminal dashboard interface. ## Features -- **Dual Interface Monitoring**: Monitor two network interfaces simultaneously +- **Interface Monitoring**: Monitor one or two network interfaces simultaneously - **Real-time Updates**: Live dashboard with sub-second updates - **Comprehensive Metrics**: - - ICMP reachability tests - - Packet loss percentage - - TCP connection latency - - Interface health status -- **Visual Indicators**: Color-coded status, spinners, and meters for quick status assessment - - Packet loss meter uses reverse coloring (empty/green = good, full/red = bad) + - ICMP reachability tests + - Packet loss percentage + - TCP connection latency + - Interface health status +- **Visual Indicators**: Color-coded status, spinners, and meters for quick + status assessment + - Packet loss meter uses reverse coloring (empty/green = good, full/red = + bad) - **Detailed Logging**: Optional logging to file for debugging and analysis ## Requirements -- Linux operating system +- Linux or macOS - Go 1.21 or later - Root/sudo access (for raw ICMP packets) - `ping` command available in PATH +- On Linux: `ip` (with `/proc/net/route` as a fallback) +- On macOS: `netstat` + +## Platform support and interface detection + +rtnetmon monitors either one or two interfaces, chosen automatically for the +platform it runs on. When only one interface is detected, the dashboard shows a +single pane. + +**Linux.** The two named interfaces (`--ifaceA`/`--ifaceB`, default +`gu0`/`backhaul0`) are used when both exist — this is the original dual-bridge +setup, unchanged. When neither exists, the single default-route interface is +monitored instead. + +**macOS.** The physical internet interface is found from the default route. When +a VPN client is running (Mullvad and similar clients create a `utun` tunnel that +carries a default route or holds a routable address), that tunnel is monitored +as the primary pane alongside the physical interface. With no VPN running, only +the physical interface is monitored. Interface names are detected on macOS; the +`--ifaceA`/`--ifaceB` flags are not used there, but `--labelA`/`--labelB` still +set the pane labels. + +### Supported matrix + +| OS | Interfaces monitored | +| ----- | ----------------------------------------------------------- | +| Linux | `gu0` + `backhaul0` when both exist (two panes) | +| Linux | the single default-route interface otherwise (one pane) | +| macOS | VPN tunnel + physical default-route interface (two panes) | +| macOS | the physical default-route interface with no VPN (one pane) | + +Anything outside this matrix — on Linux, only one of the named pair present, or +no/multiple default routes when neither is present; on macOS, no default route +or more than one physical default route — exits with a clear error. ## Installation @@ -65,11 +102,17 @@ rtnetmon/ ├── internal/ │ ├── cli/ # Command-line interface using Cobra │ │ └── root.go +│ ├── netdetect/ # Per-platform interface/route detection and selection +│ │ ├── netdetect.go # Selection logic and route parsers (pure) +│ │ ├── routes_linux.go # Linux default-route query (build-tagged) +│ │ └── routes_darwin.go # macOS default-route query (build-tagged) │ └── monitor/ # Core monitoring functionality -│ ├── monitor.go # Main monitoring types and functions -│ ├── loops.go # Monitoring loops (reachability, loss, TCP) -│ ├── styles.go # Terminal color styles -│ └── ui.go # User interface rendering +│ ├── monitor.go # Main monitoring types and functions +│ ├── loops.go # Monitoring loops (reachability, loss, TCP) +│ ├── styles.go # Terminal color styles +│ ├── ui.go # User interface rendering +│ ├── dial_linux.go # TCP source binding (build-tagged) +│ └── dial_darwin.go # TCP IP_BOUND_IF binding (build-tagged) ├── go.mod ├── go.sum ├── Makefile @@ -103,8 +146,11 @@ The monitor package provides an object-oriented API for programmatic use: ```go import "git.eeqj.de/sneak/rtnetmon/internal/monitor" -// Create a new monitor -mon := monitor.NewMonitor("eth0", "Primary", "wlan0", "Backup", "/tmp/monitor.log") +// Create a new monitor for one or two interfaces +mon := monitor.NewMonitor([]monitor.IfaceSpec{ + {Name: "eth0", Label: "Primary"}, + {Name: "wlan0", Label: "Backup"}, +}, "/tmp/monitor.log") // Configure timing parameters (optional - defaults are sensible) mon.ICMPTimeout = 1 * time.Second diff --git a/cmd/rtnetmon/main.go b/cmd/rtnetmon/main.go index 3334586..676e535 100644 --- a/cmd/rtnetmon/main.go +++ b/cmd/rtnetmon/main.go @@ -1,7 +1,4 @@ -//go:build linux -// +build linux - -// netmon – dual-interface network dashboard (curses) +// netmon – network dashboard (curses) for Linux and macOS // WTFPL – 2025-05-16 sneak@sneak.berlin package main diff --git a/go.mod b/go.mod index 88cbd4c..135c5bb 100644 --- a/go.mod +++ b/go.mod @@ -6,6 +6,7 @@ require ( github.com/gdamore/tcell/v2 v2.8.1 github.com/spf13/cobra v1.8.0 github.com/spf13/viper v1.18.2 + golang.org/x/sys v0.29.0 ) require ( @@ -29,7 +30,6 @@ require ( go.uber.org/atomic v1.9.0 // indirect go.uber.org/multierr v1.9.0 // indirect golang.org/x/exp v0.0.0-20230905200255-921286631fa9 // indirect - golang.org/x/sys v0.29.0 // indirect golang.org/x/term v0.28.0 // indirect golang.org/x/text v0.21.0 // indirect gopkg.in/ini.v1 v1.67.0 // indirect diff --git a/internal/cli/root.go b/internal/cli/root.go index bd45ef9..ad674d2 100644 --- a/internal/cli/root.go +++ b/internal/cli/root.go @@ -1,18 +1,17 @@ -//go:build linux -// +build linux - package cli import ( "context" "os" "os/signal" + "runtime" "syscall" "github.com/spf13/cobra" "github.com/spf13/viper" "git.eeqj.de/sneak/rtnetmon/internal/monitor" + "git.eeqj.de/sneak/rtnetmon/internal/netdetect" ) // Config holds the application configuration @@ -73,12 +72,17 @@ func init() { _ = viper.BindPFlag("logfile", rootCmd.Flags().Lookup("logfile")) } -func runMonitor(cmd *cobra.Command, args []string) error { +func runMonitor(cmd *cobra.Command, _ []string) error { monitor.Logf(cfg.LogFile, "Starting rtnetmon") - monitor.Logf(cfg.LogFile, "Monitoring interfaces %s and %s", cfg.IfaceA, cfg.IfaceB) + + // Detect which interfaces to monitor for this platform. + specs, err := detectInterfaces(cmd) + if err != nil { + return err + } // Create the monitor - mon := monitor.NewMonitor(cfg.IfaceA, cfg.LabelA, cfg.IfaceB, cfg.LabelB, cfg.LogFile) + mon := monitor.NewMonitor(specs, cfg.LogFile) // Add reachability hosts for _, host := range cfg.Hosts { @@ -112,6 +116,43 @@ func runMonitor(cmd *cobra.Command, args []string) error { return mon.Run(ctx) } +// detectInterfaces enumerates the host, reads its default routes, and applies +// the platform selection rules to decide which interfaces to monitor. +func detectInterfaces(cmd *cobra.Command) ([]monitor.IfaceSpec, error) { + ifaces, err := netdetect.Interfaces() + if err != nil { + return nil, err + } + + routes, err := netdetect.DefaultRoutes() + if err != nil { + return nil, err + } + + flags := netdetect.Flags{ + IfaceA: cfg.IfaceA, + LabelA: cfg.LabelA, + IfaceB: cfg.IfaceB, + LabelB: cfg.LabelB, + LabelASet: cmd.Flags().Changed("labelA"), + LabelBSet: cmd.Flags().Changed("labelB"), + } + + panes, err := netdetect.Select(runtime.GOOS, ifaces, routes, flags) + if err != nil { + return nil, err + } + + specs := make([]monitor.IfaceSpec, len(panes)) + for i, p := range panes { + specs[i] = monitor.IfaceSpec{Name: p.Name, Label: p.Label} + } + + monitor.Logf(cfg.LogFile, "Monitoring %d interface(s)", len(specs)) + + return specs, nil +} + // Execute runs the root command func Execute() error { return rootCmd.Execute() diff --git a/internal/cli/root_test.go b/internal/cli/root_test.go index 6f0d373..d590780 100644 --- a/internal/cli/root_test.go +++ b/internal/cli/root_test.go @@ -1,6 +1,3 @@ -//go:build linux -// +build linux - package cli import ( diff --git a/internal/monitor/dial_darwin.go b/internal/monitor/dial_darwin.go new file mode 100644 index 0000000..e290e0b --- /dev/null +++ b/internal/monitor/dial_darwin.go @@ -0,0 +1,36 @@ +//go:build darwin + +package monitor + +import ( + "net" + "syscall" + + "golang.org/x/sys/unix" +) + +// bindControl returns a socket control hook that pins the connection to the +// given interface with IP_BOUND_IF. On macOS a bound source address is not +// enough: without this the kernel still routes the packets over the VPN's +// default route, so traffic would not leave the interface we are measuring. +func bindControl(iface string) func(network, address string, c syscall.RawConn) error { + ifi, err := net.InterfaceByName(iface) + if err != nil { + return nil + } + + idx := ifi.Index + + return func(_, _ string, c syscall.RawConn) error { + var setErr error + + ctrlErr := c.Control(func(fd uintptr) { + setErr = unix.SetsockoptInt(int(fd), unix.IPPROTO_IP, unix.IP_BOUND_IF, idx) + }) + if ctrlErr != nil { + return ctrlErr + } + + return setErr + } +} diff --git a/internal/monitor/dial_linux.go b/internal/monitor/dial_linux.go new file mode 100644 index 0000000..fc47b93 --- /dev/null +++ b/internal/monitor/dial_linux.go @@ -0,0 +1,12 @@ +//go:build linux + +package monitor + +import "syscall" + +// bindControl returns no socket control hook on Linux: binding the dialer's +// local source address (as tcpDuration already does) is enough to send +// traffic out of the chosen interface. +func bindControl(_ string) func(network, address string, c syscall.RawConn) error { + return nil +} diff --git a/internal/monitor/loops.go b/internal/monitor/loops.go index d624c11..94dc00f 100644 --- a/internal/monitor/loops.go +++ b/internal/monitor/loops.go @@ -1,6 +1,3 @@ -//go:build linux -// +build linux - package monitor import ( diff --git a/internal/monitor/monitor.go b/internal/monitor/monitor.go index 2f97fff..4ca9c31 100644 --- a/internal/monitor/monitor.go +++ b/internal/monitor/monitor.go @@ -1,6 +1,3 @@ -//go:build linux -// +build linux - package monitor import ( @@ -11,6 +8,7 @@ import ( "net" "os" "os/exec" + "runtime" "strconv" "strings" "sync" @@ -53,9 +51,8 @@ type Monitor struct { packetLossHosts []string tcpHosts []string - // Interfaces - interfaceA *InterfaceStatus - interfaceB *InterfaceStatus + // Interfaces to monitor (one or two) + interfaces []*InterfaceStatus // Logging logFile string @@ -68,9 +65,16 @@ type Monitor struct { mu sync.RWMutex } -// NewMonitor creates a new Monitor instance with default settings -func NewMonitor(ifaceA, labelA, ifaceB, labelB, logFile string) *Monitor { - return &Monitor{ +// IfaceSpec names one interface to monitor and its display label. +type IfaceSpec struct { + Name string + Label string +} + +// NewMonitor creates a new Monitor instance with default settings, monitoring +// the given interfaces (one or two). +func NewMonitor(ifaces []IfaceSpec, logFile string) *Monitor { + m := &Monitor{ // Default timing configuration ICMPTimeout: 500 * time.Millisecond, TCPTimeout: 500 * time.Millisecond, @@ -94,15 +98,17 @@ func NewMonitor(ifaceA, labelA, ifaceB, labelB, logFile string) *Monitor { packetLossHosts: []string{}, tcpHosts: []string{}, - // Initialize interfaces - interfaceA: NewInterfaceStatus(ifaceA, labelA), - interfaceB: NewInterfaceStatus(ifaceB, labelB), - // Logging logFile: logFile, startTime: time.Now(), } + + for _, spec := range ifaces { + m.interfaces = append(m.interfaces, NewInterfaceStatus(spec.Name, spec.Label)) + } + + return m } // AddReachabilityHost adds a host for reachability monitoring @@ -159,12 +165,11 @@ func (m *Monitor) Run(ctx context.Context) error { tcpHosts := append([]string{}, m.tcpHosts...) m.mu.RUnlock() - go m.reachLoop(ctx, m.interfaceA, reachHosts) - go m.reachLoop(ctx, m.interfaceB, reachHosts) - go m.lossLoop(ctx, m.interfaceA, lossHosts) - go m.lossLoop(ctx, m.interfaceB, lossHosts) - go m.tcpLoop(ctx, m.interfaceA, tcpHosts) - go m.tcpLoop(ctx, m.interfaceB, tcpHosts) + for _, st := range m.interfaces { + go m.reachLoop(ctx, st, reachHosts) + go m.lossLoop(ctx, st, lossHosts) + go m.tcpLoop(ctx, st, tcpHosts) + } // Run UI loop m.logf("Starting UI loop") @@ -252,19 +257,45 @@ func fetchIPInfo(iface string) string { return fmt.Sprintf("%s [%s] %s", r.IP, r.Hostname, r.Org) } +// pingArgs builds the arguments for a single reachability ping on the given +// OS. Linux binds the interface with -I and takes -W in seconds; macOS binds +// with -b and takes -W in milliseconds. +func pingArgs(goos, iface, host string) []string { + if goos == "darwin" { + return []string{"-b", iface, "-c1", "-W1000", host} + } + + return []string{"-I", iface, "-c1", "-W1", host} +} + +// lossArgs builds the arguments for a packet-loss ping burst of count pings. +func lossArgs(goos, iface, host string, count int) []string { + c := strconv.Itoa(count) + if goos == "darwin" { + return []string{"-q", "-i", "0.05", "-c", c, "-W1000", "-b", iface, host} + } + + return []string{"-q", "-i", "0.05", "-c", c, "-W1", "-I", iface, host} +} + // pingOnce performs a single ping func (m *Monitor) pingOnce(iface, host string) bool { ctx, cancel := context.WithTimeout(context.Background(), m.ICMPTimeout) defer cancel() - return exec.CommandContext(ctx, "ping", "-I", iface, "-c1", "-W1", host).Run() == nil + + args := pingArgs(runtime.GOOS, iface, host) + + return exec.CommandContext(ctx, "ping", args...).Run() == nil } // lossPercent calculates packet loss percentage func (m *Monitor) lossPercent(iface, host string) float64 { ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second) defer cancel() - out, err := exec.CommandContext(ctx, "ping", "-q", "-i", "0.05", - "-c", fmt.Sprint(m.PacketLossPings), "-W1", "-I", iface, host).CombinedOutput() + + args := lossArgs(runtime.GOOS, iface, host, m.PacketLossPings) + + out, err := exec.CommandContext(ctx, "ping", args...).CombinedOutput() if err != nil { return 1.0 } @@ -302,7 +333,7 @@ func (m *Monitor) tcpDuration(iface, hp string) time.Duration { if err != nil { return m.TCPTimeout } - d := net.Dialer{Timeout: m.TCPTimeout, LocalAddr: la} + d := net.Dialer{Timeout: m.TCPTimeout, LocalAddr: la, Control: bindControl(iface)} st := time.Now() c, err := d.Dial("tcp", hp) if err != nil { diff --git a/internal/monitor/monitor_test.go b/internal/monitor/monitor_test.go index 0c6cc8f..9dc4907 100644 --- a/internal/monitor/monitor_test.go +++ b/internal/monitor/monitor_test.go @@ -1,6 +1,3 @@ -//go:build linux -// +build linux - package monitor import ( @@ -10,27 +7,26 @@ import ( // TestNewMonitor tests the creation of a new Monitor func TestNewMonitor(t *testing.T) { // Test that we can create a monitor without errors - mon := NewMonitor("test0", "Test Interface A", "test1", "Test Interface B", "/tmp/test.log") + mon := NewMonitor([]IfaceSpec{ + {Name: "test0", Label: "Test Interface A"}, + {Name: "test1", Label: "Test Interface B"}, + }, "/tmp/test.log") if mon == nil { t.Fatal("NewMonitor returned nil") } // Check interfaces - if mon.interfaceA == nil { - t.Fatal("interfaceA is nil") + if len(mon.interfaces) != 2 { + t.Fatalf("Expected 2 interfaces, got %d", len(mon.interfaces)) } - if mon.interfaceB == nil { - t.Fatal("interfaceB is nil") + if mon.interfaces[0].Name != "test0" { + t.Errorf("Expected interfaces[0].Name to be 'test0', got '%s'", mon.interfaces[0].Name) } - if mon.interfaceA.Name != "test0" { - t.Errorf("Expected interfaceA.Name to be 'test0', got '%s'", mon.interfaceA.Name) - } - - if mon.interfaceB.Name != "test1" { - t.Errorf("Expected interfaceB.Name to be 'test1', got '%s'", mon.interfaceB.Name) + if mon.interfaces[1].Name != "test1" { + t.Errorf("Expected interfaces[1].Name to be 'test1', got '%s'", mon.interfaces[1].Name) } // Check default configuration @@ -56,9 +52,25 @@ func TestNewMonitor(t *testing.T) { } } +// TestNewMonitorSingle verifies a monitor can be built with one interface. +func TestNewMonitorSingle(t *testing.T) { + mon := NewMonitor([]IfaceSpec{{Name: "eth0", Label: "default route"}}, "") + + if len(mon.interfaces) != 1 { + t.Fatalf("Expected 1 interface, got %d", len(mon.interfaces)) + } + + if mon.interfaces[0].Name != "eth0" { + t.Errorf("Expected interfaces[0].Name to be 'eth0', got '%s'", mon.interfaces[0].Name) + } +} + // TestAddHosts tests adding hosts to the monitor func TestAddHosts(t *testing.T) { - mon := NewMonitor("test0", "Test A", "test1", "Test B", "") + mon := NewMonitor([]IfaceSpec{ + {Name: "test0", Label: "Test A"}, + {Name: "test1", Label: "Test B"}, + }, "") // Test adding reachability hosts mon.AddReachabilityHost("8.8.8.8") diff --git a/internal/monitor/ping_test.go b/internal/monitor/ping_test.go new file mode 100644 index 0000000..9be0e18 --- /dev/null +++ b/internal/monitor/ping_test.go @@ -0,0 +1,48 @@ +package monitor + +import ( + "reflect" + "testing" +) + +func TestPingArgs(t *testing.T) { + tests := []struct { + goos string + want []string + }{ + {"linux", []string{"-I", "eth0", "-c1", "-W1", "8.8.8.8"}}, + {"darwin", []string{"-b", "eth0", "-c1", "-W1000", "8.8.8.8"}}, + } + + for _, tt := range tests { + t.Run(tt.goos, func(t *testing.T) { + got := pingArgs(tt.goos, "eth0", "8.8.8.8") + if !reflect.DeepEqual(got, tt.want) { + t.Errorf("pingArgs(%q) = %v, want %v", tt.goos, got, tt.want) + } + }) + } +} + +func TestLossArgs(t *testing.T) { + tests := []struct { + goos string + want []string + }{ + {"linux", []string{ + "-q", "-i", "0.05", "-c", "20", "-W1", "-I", "eth0", "8.8.8.8", + }}, + {"darwin", []string{ + "-q", "-i", "0.05", "-c", "20", "-W1000", "-b", "eth0", "8.8.8.8", + }}, + } + + for _, tt := range tests { + t.Run(tt.goos, func(t *testing.T) { + got := lossArgs(tt.goos, "eth0", "8.8.8.8", 20) + if !reflect.DeepEqual(got, tt.want) { + t.Errorf("lossArgs(%q) = %v, want %v", tt.goos, got, tt.want) + } + }) + } +} diff --git a/internal/monitor/styles.go b/internal/monitor/styles.go index 6417cf9..deb5811 100644 --- a/internal/monitor/styles.go +++ b/internal/monitor/styles.go @@ -1,6 +1,3 @@ -//go:build linux -// +build linux - package monitor import tcell "github.com/gdamore/tcell/v2" diff --git a/internal/monitor/styles_test.go b/internal/monitor/styles_test.go index 325082a..f16e4e3 100644 --- a/internal/monitor/styles_test.go +++ b/internal/monitor/styles_test.go @@ -1,6 +1,3 @@ -//go:build linux -// +build linux - package monitor import ( diff --git a/internal/monitor/ui.go b/internal/monitor/ui.go index 2734f8b..5500b17 100644 --- a/internal/monitor/ui.go +++ b/internal/monitor/ui.go @@ -1,6 +1,3 @@ -//go:build linux -// +build linux - package monitor import ( @@ -345,10 +342,11 @@ func (m *Monitor) uiLoop(ctx context.Context) { // Draw the runtime Put(m.screen, 0, 3, "Runtime: "+time.Since(m.startTime).Round(time.Second).String(), CDefault) - // Draw interfaces + // Draw interfaces (one pane each; a single interface draws one pane) y := 5 - y = m.DrawInterface(m.screen, y, w, m.interfaceA) - _ = m.DrawInterface(m.screen, y, w, m.interfaceB) + for _, st := range m.interfaces { + y = m.DrawInterface(m.screen, y, w, st) + } // Show the screen m.screen.Show() diff --git a/internal/netdetect/netdetect.go b/internal/netdetect/netdetect.go new file mode 100644 index 0000000..e8d1f35 --- /dev/null +++ b/internal/netdetect/netdetect.go @@ -0,0 +1,359 @@ +// Package netdetect chooses which network interfaces rtnetmon should monitor. +// +// The host-specific queries (enumerating interfaces, reading the routing +// table) live behind small data types so the selection logic and the route +// parsers are pure functions that can be unit-tested on any OS with fake +// data. Only the real routing-table query is build-tagged per platform. +package netdetect + +import ( + "fmt" + "net" + "sort" + "strconv" + "strings" +) + +// Interface is a network interface reduced to what detection needs. +type Interface struct { + Name string + Up bool + IPv4 []string +} + +// Route is one routing-table entry reduced to what detection needs. +type Route struct { + Iface string + Gateway string + Default bool +} + +// Pane names one interface to display, with its label. +type Pane struct { + Name string + Label string +} + +// Flags carries the user's --iface/--label choices and whether each label was +// set explicitly on the command line. +type Flags struct { + IfaceA string + LabelA string + IfaceB string + LabelB string + LabelASet bool + LabelBSet bool +} + +// Interfaces enumerates the host's interfaces and their IPv4 addresses. This +// uses the standard library and is the same on every platform. +func Interfaces() ([]Interface, error) { + ifs, err := net.Interfaces() + if err != nil { + return nil, fmt.Errorf("listing interfaces: %w", err) + } + + out := make([]Interface, 0, len(ifs)) + for _, ifi := range ifs { + var v4 []string + + addrs, _ := ifi.Addrs() + for _, a := range addrs { + if n, ok := a.(*net.IPNet); ok && n.IP.To4() != nil { + v4 = append(v4, n.IP.String()) + } + } + + out = append(out, Interface{ + Name: ifi.Name, + Up: ifi.Flags&net.FlagUp != 0, + IPv4: v4, + }) + } + + return out, nil +} + +// Select decides which one or two interfaces to monitor for the given OS. +// See the README's supported matrix for the exact rules. +func Select(goos string, ifaces []Interface, routes []Route, f Flags) ([]Pane, error) { + switch goos { + case "linux": + return selectLinux(ifaces, routes, f) + case "darwin": + return selectDarwin(ifaces, routes, f) + default: + return nil, fmt.Errorf("unsupported operating system %q", goos) + } +} + +// selectLinux keeps today's behavior: if both configured interfaces exist, +// monitor them as two panes; if neither exists, monitor the single +// default-route interface; anything else is an error. +func selectLinux(ifaces []Interface, routes []Route, f Flags) ([]Pane, error) { + haveA := hasInterface(ifaces, f.IfaceA) + haveB := hasInterface(ifaces, f.IfaceB) + + switch { + case haveA && haveB: + return []Pane{ + {Name: f.IfaceA, Label: f.LabelA}, + {Name: f.IfaceB, Label: f.LabelB}, + }, nil + case !haveA && !haveB: + name, err := onlyDefaultRoute(routes) + if err != nil { + return nil, err + } + + return []Pane{{Name: name, Label: singleLabel(f)}}, nil + default: + return nil, fmt.Errorf( + "found only one of the configured interfaces (%q, %q); "+ + "rtnetmon needs both, or neither (default route only)", + f.IfaceA, f.IfaceB) + } +} + +// selectDarwin monitors the physical default-route interface, plus a VPN +// tunnel as the primary pane when one is running. +func selectDarwin(ifaces []Interface, routes []Route, f Flags) ([]Pane, error) { + vpn := findVPN(ifaces, routes) + + phys, err := onlyPhysicalDefaultRoute(routes, vpn) + if err != nil { + return nil, err + } + + if vpn == "" { + return []Pane{{Name: phys, Label: singleLabel(f)}}, nil + } + + return []Pane{ + {Name: vpn, Label: labelOr(f.LabelA, f.LabelASet, "VPN")}, + {Name: phys, Label: labelOr(f.LabelB, f.LabelBSet, "default route")}, + }, nil +} + +// findVPN returns the name of a VPN tunnel interface, or "" if none is +// running. A tunnel counts as a running VPN when it carries a default route, +// or when it is up with a routable (non-link-local) IPv4 address. Idle system +// tunnels have only a link-local IPv6 address and are skipped. +func findVPN(ifaces []Interface, routes []Route) string { + routeIfaces := map[string]bool{} + for _, r := range routes { + if r.Default { + routeIfaces[r.Iface] = true + } + } + + sorted := append([]Interface(nil), ifaces...) + sort.Slice(sorted, func(i, j int) bool { return sorted[i].Name < sorted[j].Name }) + + for _, ifi := range sorted { + if !isTunnel(ifi.Name) { + continue + } + if routeIfaces[ifi.Name] { + return ifi.Name + } + if ifi.Up && hasRoutableIPv4(ifi) { + return ifi.Name + } + } + + return "" +} + +// onlyDefaultRoute returns the single default-route interface, or an error if +// there is not exactly one. +func onlyDefaultRoute(routes []Route) (string, error) { + names := defaultRouteIfaces(routes, "") + + switch len(names) { + case 1: + return names[0], nil + case 0: + return "", fmt.Errorf( + "no default route found; rtnetmon needs one internet interface") + default: + return "", fmt.Errorf( + "multiple default-route interfaces found (%s); rtnetmon supports only one", + strings.Join(names, ", ")) + } +} + +// onlyPhysicalDefaultRoute returns the single non-tunnel default-route +// interface (ignoring the VPN), or an error if there is not exactly one. +func onlyPhysicalDefaultRoute(routes []Route, vpn string) (string, error) { + names := defaultRouteIfaces(routes, vpn) + + switch len(names) { + case 1: + return names[0], nil + case 0: + return "", fmt.Errorf( + "no physical default-route interface found; " + + "rtnetmon needs one internet interface") + default: + return "", fmt.Errorf( + "multiple physical default-route interfaces found (%s); "+ + "rtnetmon supports only one", + strings.Join(names, ", ")) + } +} + +// defaultRouteIfaces returns the sorted, unique interface names that carry a +// default route, excluding the named VPN interface and any other tunnel. +func defaultRouteIfaces(routes []Route, vpn string) []string { + seen := map[string]bool{} + + var names []string + + for _, r := range routes { + if !r.Default || r.Iface == vpn || isTunnel(r.Iface) || seen[r.Iface] { + continue + } + + seen[r.Iface] = true + names = append(names, r.Iface) + } + + sort.Strings(names) + + return names +} + +// hasInterface reports whether an interface with the given name exists. +func hasInterface(ifaces []Interface, name string) bool { + for _, ifi := range ifaces { + if ifi.Name == name { + return true + } + } + + return false +} + +// isTunnel reports whether the interface name is a macOS userspace tunnel +// (utunN), which is what Mullvad and other WireGuard/OpenVPN clients use. +func isTunnel(name string) bool { + return strings.HasPrefix(name, "utun") +} + +// hasRoutableIPv4 reports whether the interface has an IPv4 address that is +// neither loopback nor link-local. +func hasRoutableIPv4(ifi Interface) bool { + for _, s := range ifi.IPv4 { + ip := net.ParseIP(s) + if ip == nil || ip.IsLoopback() || ip.IsLinkLocalUnicast() { + continue + } + + return true + } + + return false +} + +// singleLabel is the label for a lone pane: the explicit --labelA if given, +// otherwise a plain description. +func singleLabel(f Flags) string { + return labelOr(f.LabelA, f.LabelASet, "default route") +} + +// labelOr returns value when it was set explicitly, otherwise fallback. +func labelOr(value string, set bool, fallback string) string { + if set { + return value + } + + return fallback +} + +// parseIPRoute reads `ip -4 route show default` output. Every printed line is +// a default route. +func parseIPRoute(out string) []Route { + var routes []Route + + for _, line := range strings.Split(out, "\n") { + fields := strings.Fields(line) + if len(fields) == 0 || fields[0] != "default" { + continue + } + + r := Route{Default: true} + for i := 0; i < len(fields)-1; i++ { + switch fields[i] { + case "dev": + r.Iface = fields[i+1] + case "via": + r.Gateway = fields[i+1] + } + } + + if r.Iface != "" { + routes = append(routes, r) + } + } + + return routes +} + +// parseProcNetRoute reads /proc/net/route. A default route has destination +// 00000000; the gateway is a little-endian hex IPv4 address. +func parseProcNetRoute(out string) []Route { + var routes []Route + + for i, line := range strings.Split(out, "\n") { + if i == 0 { // column header + continue + } + + fields := strings.Fields(line) + if len(fields) < 3 || fields[1] != "00000000" { + continue + } + + routes = append(routes, Route{ + Iface: fields[0], + Gateway: hexToIP(fields[2]), + Default: true, + }) + } + + return routes +} + +// parseNetstat reads `netstat -rn -f inet` output (macOS). Rows whose +// destination is "default" are default routes; the Netif column (field 4) +// names the interface. +func parseNetstat(out string) []Route { + var routes []Route + + for _, line := range strings.Split(out, "\n") { + fields := strings.Fields(line) + if len(fields) < 4 || fields[0] != "default" { + continue + } + + routes = append(routes, Route{ + Iface: fields[3], + Gateway: fields[1], + Default: true, + }) + } + + return routes +} + +// hexToIP converts a little-endian hex IPv4 address (as found in +// /proc/net/route) to dotted-quad form. +func hexToIP(h string) string { + v, err := strconv.ParseUint(h, 16, 32) + if err != nil { + return "" + } + + return fmt.Sprintf("%d.%d.%d.%d", v&0xff, (v>>8)&0xff, (v>>16)&0xff, (v>>24)&0xff) +} diff --git a/internal/netdetect/netdetect_test.go b/internal/netdetect/netdetect_test.go new file mode 100644 index 0000000..260b0b3 --- /dev/null +++ b/internal/netdetect/netdetect_test.go @@ -0,0 +1,238 @@ +package netdetect + +import ( + "reflect" + "testing" +) + +// gu and backhaul are the Linux bridge interfaces rtnetmon was built for. +func linuxFlags() Flags { + return Flags{ + IfaceA: "gu0", LabelA: "gu LAN - VPN outbound", + IfaceB: "backhaul0", LabelB: "Cox cable direct", + } +} + +func TestSelect(t *testing.T) { + tests := []struct { + name string + goos string + ifaces []Interface + routes []Route + flags Flags + want []Pane + wantErr bool + }{ + { + name: "linux both bridge interfaces present", + goos: "linux", + ifaces: []Interface{ + {Name: "gu0", Up: true}, + {Name: "backhaul0", Up: true}, + {Name: "eth0", Up: true}, + }, + routes: []Route{{Iface: "eth0", Default: true}}, + flags: linuxFlags(), + want: []Pane{ + {Name: "gu0", Label: "gu LAN - VPN outbound"}, + {Name: "backhaul0", Label: "Cox cable direct"}, + }, + }, + { + name: "linux no bridge interfaces, single default route", + goos: "linux", + ifaces: []Interface{{Name: "eth0", Up: true}, {Name: "lo", Up: true}}, + routes: []Route{{Iface: "eth0", Default: true}}, + flags: linuxFlags(), + want: []Pane{{Name: "eth0", Label: "default route"}}, + }, + { + name: "linux only one bridge interface present is an error", + goos: "linux", + ifaces: []Interface{{Name: "gu0", Up: true}, {Name: "eth0", Up: true}}, + routes: []Route{{Iface: "eth0", Default: true}}, + flags: linuxFlags(), + wantErr: true, + }, + { + name: "linux no bridge, no default route is an error", + goos: "linux", + ifaces: []Interface{{Name: "eth0", Up: true}}, + routes: nil, + flags: linuxFlags(), + wantErr: true, + }, + { + name: "linux no bridge, multiple default routes is an error", + goos: "linux", + ifaces: []Interface{{Name: "eth0", Up: true}, {Name: "eth1", Up: true}}, + routes: []Route{{Iface: "eth0", Default: true}, {Iface: "eth1", Default: true}}, + flags: linuxFlags(), + wantErr: true, + }, + { + name: "linux single default route keeps explicit label", + goos: "linux", + ifaces: []Interface{ + {Name: "wlan0", Up: true}, + }, + routes: []Route{{Iface: "wlan0", Default: true}}, + flags: Flags{ + IfaceA: "gu0", LabelA: "Home WiFi", LabelASet: true, + IfaceB: "backhaul0", LabelB: "Cox cable direct", + }, + want: []Pane{{Name: "wlan0", Label: "Home WiFi"}}, + }, + { + name: "macos vpn tunnel plus physical default route", + goos: "darwin", + ifaces: []Interface{ + {Name: "en0", Up: true, IPv4: []string{"192.168.1.20"}}, + {Name: "utun4", Up: true, IPv4: []string{"10.64.0.2"}}, + {Name: "utun0", Up: true, IPv4: nil}, + }, + routes: []Route{ + {Iface: "utun4", Default: true}, + {Iface: "en0", Default: true}, + }, + flags: linuxFlags(), + want: []Pane{ + {Name: "utun4", Label: "VPN"}, + {Name: "en0", Label: "default route"}, + }, + }, + { + name: "macos vpn detected by routable address without its own route", + goos: "darwin", + ifaces: []Interface{ + {Name: "en0", Up: true, IPv4: []string{"192.168.1.20"}}, + {Name: "utun6", Up: true, IPv4: []string{"10.2.0.2"}}, + }, + routes: []Route{{Iface: "en0", Default: true}}, + flags: linuxFlags(), + want: []Pane{ + {Name: "utun6", Label: "VPN"}, + {Name: "en0", Label: "default route"}, + }, + }, + { + name: "macos no vpn, single physical default route", + goos: "darwin", + ifaces: []Interface{ + {Name: "en0", Up: true, IPv4: []string{"192.168.1.20"}}, + {Name: "utun0", Up: true, IPv4: nil}, + {Name: "utun1", Up: true, IPv4: []string{"169.254.1.1"}}, + }, + routes: []Route{{Iface: "en0", Default: true}}, + flags: linuxFlags(), + want: []Pane{{Name: "en0", Label: "default route"}}, + }, + { + name: "macos vpn pane honors explicit labels", + goos: "darwin", + ifaces: []Interface{ + {Name: "en0", Up: true, IPv4: []string{"192.168.1.20"}}, + {Name: "utun4", Up: true, IPv4: []string{"10.64.0.2"}}, + }, + routes: []Route{ + {Iface: "utun4", Default: true}, + {Iface: "en0", Default: true}, + }, + flags: Flags{ + LabelA: "Mullvad", LabelASet: true, + LabelB: "Fiber", LabelBSet: true, + }, + want: []Pane{ + {Name: "utun4", Label: "Mullvad"}, + {Name: "en0", Label: "Fiber"}, + }, + }, + { + name: "macos no default route is an error", + goos: "darwin", + ifaces: []Interface{{Name: "en0", Up: true, IPv4: []string{"192.168.1.20"}}}, + routes: nil, + flags: linuxFlags(), + wantErr: true, + }, + { + name: "macos two physical default routes is an error", + goos: "darwin", + ifaces: []Interface{ + {Name: "en0", Up: true, IPv4: []string{"192.168.1.20"}}, + {Name: "en1", Up: true, IPv4: []string{"192.168.2.20"}}, + }, + routes: []Route{ + {Iface: "en0", Default: true}, + {Iface: "en1", Default: true}, + }, + flags: linuxFlags(), + wantErr: true, + }, + { + name: "unsupported operating system is an error", + goos: "windows", + wantErr: true, + }, + } + + for _, tt := range tests { + t.Run(tt.name, func(t *testing.T) { + got, err := Select(tt.goos, tt.ifaces, tt.routes, tt.flags) + if tt.wantErr { + if err == nil { + t.Fatalf("Select() expected error, got panes %v", got) + } + + return + } + + if err != nil { + t.Fatalf("Select() unexpected error: %v", err) + } + + if !reflect.DeepEqual(got, tt.want) { + t.Errorf("Select() = %v, want %v", got, tt.want) + } + }) + } +} + +func TestParseIPRoute(t *testing.T) { + out := "default via 192.168.1.1 dev eth0 proto dhcp metric 100\n" + got := parseIPRoute(out) + want := []Route{{Iface: "eth0", Gateway: "192.168.1.1", Default: true}} + + if !reflect.DeepEqual(got, want) { + t.Errorf("parseIPRoute() = %v, want %v", got, want) + } +} + +func TestParseProcNetRoute(t *testing.T) { + out := "Iface\tDestination\tGateway\tFlags\tRefCnt\tUse\tMetric\tMask\n" + + "eth0\t00000000\t0102A8C0\t0003\t0\t0\t100\t00000000\n" + + "eth0\t0002A8C0\t00000000\t0001\t0\t0\t0\t00FFFFFF\n" + got := parseProcNetRoute(out) + want := []Route{{Iface: "eth0", Gateway: "192.168.2.1", Default: true}} + + if !reflect.DeepEqual(got, want) { + t.Errorf("parseProcNetRoute() = %v, want %v", got, want) + } +} + +func TestParseNetstat(t *testing.T) { + out := "Routing tables\n\nInternet:\n" + + "Destination Gateway Flags Netif Expire\n" + + "default 10.0.0.1 UGScg en0\n" + + "default link#15 UCSg utun4\n" + + "127.0.0.1 127.0.0.1 UH lo0\n" + got := parseNetstat(out) + want := []Route{ + {Iface: "en0", Gateway: "10.0.0.1", Default: true}, + {Iface: "utun4", Gateway: "link#15", Default: true}, + } + + if !reflect.DeepEqual(got, want) { + t.Errorf("parseNetstat() = %v, want %v", got, want) + } +} diff --git a/internal/netdetect/routes_darwin.go b/internal/netdetect/routes_darwin.go new file mode 100644 index 0000000..5902f34 --- /dev/null +++ b/internal/netdetect/routes_darwin.go @@ -0,0 +1,16 @@ +//go:build darwin + +package netdetect + +import "os/exec" + +// DefaultRoutes returns the host's IPv4 default routes, read from the macOS +// routing table. +func DefaultRoutes() ([]Route, error) { + out, err := exec.Command("netstat", "-rn", "-f", "inet").Output() + if err != nil { + return nil, err + } + + return parseNetstat(string(out)), nil +} diff --git a/internal/netdetect/routes_linux.go b/internal/netdetect/routes_linux.go new file mode 100644 index 0000000..9517e3d --- /dev/null +++ b/internal/netdetect/routes_linux.go @@ -0,0 +1,26 @@ +//go:build linux + +package netdetect + +import ( + "os" + "os/exec" +) + +// DefaultRoutes returns the host's IPv4 default routes. It prefers the `ip` +// command and falls back to reading /proc/net/route. +func DefaultRoutes() ([]Route, error) { + out, err := exec.Command("ip", "-4", "route", "show", "default").Output() + if err == nil { + if routes := parseIPRoute(string(out)); len(routes) > 0 { + return routes, nil + } + } + + data, err := os.ReadFile("/proc/net/route") + if err != nil { + return nil, err + } + + return parseProcNetRoute(string(data)), nil +}