Split net packages

9 files changed, 107 insertions, 51 deletions

diff --git a/go.mod b/go.mod
index b775451..0cc7e2a 100644
--- a/go.mod
+++ b/go.mod
@@ -2,7 +2,4 @@ module go.sudomsg.com/kit
 
 go 1.26.0
 
-require (
-	github.com/coreos/go-systemd/v22 v22.7.0
-	golang.org/x/sync v0.19.0
-)
+require golang.org/x/sync v0.19.0
diff --git a/go.sum b/go.sum
index 30ce3a9..159532a 100644
--- a/go.sum
+++ b/go.sum
@@ -1,4 +1,2 @@
-github.com/coreos/go-systemd/v22 v22.7.0 h1:LAEzFkke61DFROc7zNLX/WA2i5J8gYqe0rSj9KI28KA=
-github.com/coreos/go-systemd/v22 v22.7.0/go.mod h1:xNUYtjHu2EDXbsxz1i41wouACIwT7Ybq9o0BQhMwD0w=
 golang.org/x/sync v0.19.0 h1:vV+1eWNmZ5geRlYjzm2adRgW2/mcpevXNg50YZtPCE4=
 golang.org/x/sync v0.19.0/go.mod h1:9KTHXmSnoGruLpwFjVSX0lNNA75CykiMECbovNTZqGI=
diff --git a/http/http.go b/http/http.go
index 71075a7..42d8f4f 100644
--- a/http/http.go
+++ b/http/http.go
@@ -10,6 +10,7 @@ import (
 	"time"
 
 	"go.sudomsg.com/kit/logging"
+	netkit "go.sudomsg.com/kit/net"
 	"golang.org/x/sync/errgroup"
 )
 
@@ -22,7 +23,7 @@ import (
 // Each server logs startup, shutdown, and errors.
 //
 // This function blocks until all servers have stopped or an error occurs.
-func RunHTTPServers(ctx context.Context, lns Listeners, handler http.Handler) error {
+func RunHTTPServers(ctx context.Context, lns netkit.Listeners, handler http.Handler) error {
 	g, ctx := errgroup.WithContext(ctx)
 
 	for _, ln := range lns {
diff --git a/http/http_test.go b/http/http_test.go
index d7eb3c4..dce9092 100644
--- a/http/http_test.go
+++ b/http/http_test.go
@@ -2,14 +2,28 @@ package http_test
 
 import (
 	"context"
-	httpServer "go.sudomsg.com/kit/http"
 	"io"
+	"net"
 	"net/http"
 	"strings"
 	"testing"
 	"time"
+
+	httpServer "go.sudomsg.com/kit/http"
+	netkit "go.sudomsg.com/kit/net"
 )
 
+func newListener(tb testing.TB) net.Listener {
+	tb.Helper()
+
+	ln, err := net.Listen("tcp", "localhost:0")
+	if err != nil {
+		tb.Fatalf("failed to open listener: %v", err)
+	}
+	return ln
+}
+
+
 func TestRunHTTPServers(t *testing.T) {
 	t.Parallel()
 	t.Run("basic serve and shutdown", func(t *testing.T) {
@@ -45,7 +59,7 @@ func TestRunHTTPServers(t *testing.T) {
 			cancel() // shutdown the server
 		}()
 
-		err := httpServer.RunHTTPServers(ctx, httpServer.Listeners{ln}, handler)
+		err := httpServer.RunHTTPServers(ctx, netkit.Listeners{ln}, handler)
 		if err != nil {
 			t.Fatalf("RunHTTPServers failed: %v", err)
 		}
diff --git a/http/systemd_linux.go b/http/systemd_linux.go
deleted file mode 100644
index bf1e6a1..0000000
--- a/http/systemd_linux.go
+++ /dev/null
@@ -1,16 +0,0 @@
-//go:build linux
-
-package http
-
-import (
-	"github.com/coreos/go-systemd/v22/activation"
-)
-
-func getSystemdListeners() (Listeners, error) {
-	lns, err := activation.Listeners()
-	if err != nil {
-		return nil, err
-	}
-
-	return lns, nil
-}
diff --git a/http/server.go b/net/server.go
index b74e39b..22448b3 100644
--- a/http/server.go
+++ b/net/server.go
@@ -6,7 +6,7 @@
 //
 // This package is designed to be used with context cancellation for concurrency control.
 
-package http
+package net
 
 import (
 	"context"
@@ -47,7 +47,11 @@ const (
 	NetTCP NetType = iota
 	NetTCP4
 	NetTCP6
+	NetUDP
+	NetUDP4
+	NetUDP6
 	NetUnix
+	NetUnixDatagram
 	NetUnixPacket
 )
 
diff --git a/http/server_test.go b/net/server_test.go
index 0f49f01..ca4836c 100644
--- a/http/server_test.go
+++ b/net/server_test.go
@@ -1,11 +1,11 @@
-package http_test
+package net_test
 
 import (
 	"net"
 	"strings"
 	"testing"
 
-	"go.sudomsg.com/kit/http"
+	netkit "go.sudomsg.com/kit/net"
 )
 
 // helper to find free TCP ports
@@ -25,12 +25,12 @@ func TestOpenConfigListeners(t *testing.T) {
 		t.Parallel()
 		ctx := t.Context()
 
-		cfg := []http.ServerConfig{
-			{Network: http.NetTCP, Address: "localhost:0"},
-			{Network: http.NetTCP, Address: "localhost:0"},
+		cfg := []netkit.ServerConfig{
+			{Network: netkit.NetTCP, Address: "localhost:0"},
+			{Network: netkit.NetTCP, Address: "localhost:0"},
 		}
 
-		lns, err := http.OpenConfigListners(ctx, cfg)
+		lns, err := netkit.OpenConfigListners(ctx, cfg)
 		if err != nil {
 			t.Fatalf("unexpected error: %v", err)
 		}
@@ -48,12 +48,12 @@ func TestOpenConfigListeners(t *testing.T) {
 		conflict := newListener(t)
 		defer conflict.Close()
 
-		cfg := []http.ServerConfig{
-			{Network: http.NetTCP, Address: "localhost:0"},
-			{Network: http.NetTCP, Address: conflict.Addr().String()}, // will fail
+		cfg := []netkit.ServerConfig{
+			{Network: netkit.NetTCP, Address: "localhost:0"},
+			{Network: netkit.NetTCP, Address: conflict.Addr().String()}, // will fail
 		}
 
-		lns, err := http.OpenConfigListners(ctx, cfg)
+		lns, err := netkit.OpenConfigListners(ctx, cfg)
 		if err == nil {
 			defer lns.CloseAll()
 			t.Fatal("expected error due to conflict, got nil")
@@ -67,7 +67,7 @@ func TestCloseAll(t *testing.T) {
 		ln1 := newListener(t)
 		ln2 := newListener(t)
 
-		ls := http.Listeners{ln1, ln2}
+		ls := netkit.Listeners{ln1, ln2}
 		err := ls.CloseAll()
 		if err != nil {
 			t.Errorf("unexpected error from CloseAll: %v", err)
@@ -86,15 +86,15 @@ func TestInvalidConfig(t *testing.T) {
 
 	tests := []struct {
 		name   string
-		config http.ServerConfig
+		config netkit.ServerConfig
 	}{
 		{
 			name:   "invalid network",
-			config: http.ServerConfig{Network: -1, Address: "localhost:0"},
+			config: netkit.ServerConfig{Network: -1, Address: "localhost:0"},
 		},
 		{
 			name:   "invalid address",
-			config: http.ServerConfig{Network: http.NetTCP, Address: "::::"},
+			config: netkit.ServerConfig{Network: netkit.NetTCP, Address: "::::"},
 		},
 	}
 
@@ -104,7 +104,7 @@ func TestInvalidConfig(t *testing.T) {
 
 			ctx := t.Context()
 
-			_, err := http.OpenConfigListners(ctx, []http.ServerConfig{tt.config})
+			_, err := netkit.OpenConfigListners(ctx, []netkit.ServerConfig{tt.config})
 			if err == nil {
 				t.Fatal("OpenConfigListners() expected error, got nil")
 			}
@@ -118,12 +118,12 @@ func TestNetType(t *testing.T) {
 	t.Run("RoundTrip", func(t *testing.T) {
 		t.Parallel()
 
-		testCases := []http.NetType{
-			http.NetTCP,
-			http.NetTCP4,
-			http.NetTCP6,
-			http.NetUnix,
-			http.NetUnixPacket,
+		testCases := []netkit.NetType{
+			netkit.NetTCP,
+			netkit.NetTCP4,
+			netkit.NetTCP6,
+			netkit.NetUnix,
+			netkit.NetUnixPacket,
 		}
 
 		for _, original := range testCases {
@@ -135,7 +135,7 @@ func TestNetType(t *testing.T) {
 							t.Fatalf("MarshalText failed: %v", err)
 						}
 
-						var decoded http.NetType
+						var decoded netkit.NetType
 						if err := decoded.UnmarshalText(text); err != nil {
 							t.Fatalf("UnmarshalText failed: %v", err)
 						}
@@ -152,7 +152,7 @@ func TestNetType(t *testing.T) {
 							t.Fatalf("MarshalText failed: %v", err)
 						}
 
-						var decoded http.NetType
+						var decoded netkit.NetType
 						if err := decoded.UnmarshalText([]byte(strings.ToUpper(string(text)))); err != nil {
 							t.Fatalf("UnmarshalText failed: %v", err)
 						}
@@ -171,7 +171,7 @@ func TestNetType(t *testing.T) {
 		t.Parallel()
 
 		input := "invalid"
-		var decoded http.NetType
+		var decoded netkit.NetType
 
 		if err := decoded.UnmarshalText([]byte(input)); err == nil {
 			t.Errorf("expected error for input %q, got none", input)
diff --git a/net/systemd_linux.go b/net/systemd_linux.go
new file mode 100644
index 0000000..efccd27
--- /dev/null
+++ b/net/systemd_linux.go
@@ -0,0 +1,58 @@
+//go:build linux
+
+package net
+
+import (
+	"fmt"
+	"net"
+	"os"
+	"strconv"
+)
+
+func getSystemdListeners() (Listeners, error) {
+	pidStr := os.Getenv("LISTEN_PID")
+	fdStr := os.Getenv("LISTEN_FDS")
+
+	if pidStr == "" || fdStr == "" {
+		return nil, nil // Not running under systemd
+	}
+
+	pid, err := strconv.Atoi(pidStr)
+	if err != nil {
+		// Not our activation — another process might have inherited the env.
+		return nil, nil
+	}
+	if pid != os.Getpid() {
+		return nil, fmt.Errorf("LISTEN_PID %d does not match current PID %d", pid, os.Getpid())
+	}
+
+	defer func() {
+		_ = os.Unsetenv("LISTEN_PID")
+		_ = os.Unsetenv("LISTEN_FDS")
+	}()
+
+	nfds, err := strconv.ParseUint(fdStr, 10, 64)
+	if err != nil {
+		return nil, fmt.Errorf("invalid LISTEN_FDS: %w", err)
+	}
+	if nfds == 0 {
+		return nil, nil // Nothing to do
+	}
+
+	lns := make(Listeners, 0, nfds)
+	for i := range nfds {
+		fd := i + 3
+		file := os.NewFile(uintptr(fd), fmt.Sprintf("fd_%d", fd))
+		if file == nil {
+			return nil, fmt.Errorf("fd %d was nil", fd)
+		}
+		ln, err := net.FileListener(file)
+		if err != nil {
+			file.Close()
+			return nil, fmt.Errorf("failed to create listener from fd %d: %w", fd, err)
+		}
+		lns = append(lns, ln)
+	}
+
+	return lns, nil
+}
diff --git a/http/systemd_stub.go b/net/systemd_stub.go
index 00699f3..502cf4b 100644
--- a/http/systemd_stub.go
+++ b/net/systemd_stub.go
@@ -1,6 +1,6 @@
 //go:build !linux
 
-package http
+package net
 
 func getSystemdListeners() (Listeners, error) {
 	return nil, nil // No-op on non-Linux