Initial commit

internal/kcpolicy/socketmap.go

@@ -0,0 +1,85 @@
+package kcpolicy
+
+import (
+	"bufio"
+	"context"
+	"fmt"
+	"net"
+	"os"
+	"strings"
+)
+
+func RunSocketmap(ctx context.Context, cfg *Config, db *AliasDB) error {
+	sock := cfg.Sockets.SocketmapSocket
+	_ = os.Remove(sock)
+
+	l, err := net.Listen("unix", sock)
+	if err != nil {
+		return err
+	}
+	defer l.Close()
+
+	if err := ChownChmodSocket(sock, cfg); err != nil {
+		return err
+	}
+
+	for {
+		conn, err := l.Accept()
+		if err != nil {
+			select {
+			case <-ctx.Done():
+				return nil
+			default:
+				return err
+			}
+		}
+		go handleSocketmapConn(conn, cfg, db)
+	}
+}
+
+// Socketmap protocol: "mapname key\n" -> "OK value\n" or "NOTFOUND\n" or "TEMP\n"
+func handleSocketmapConn(conn net.Conn, cfg *Config, db *AliasDB) {
+	defer conn.Close()
+	r := bufio.NewReader(conn)
+
+	for {
+		line, err := r.ReadString('\n')
+		if err != nil {
+			return
+		}
+		line = strings.TrimSpace(line)
+		if line == "" {
+			continue
+		}
+		parts := strings.SplitN(line, " ", 2)
+		if len(parts) != 2 {
+			fmt.Fprint(conn, "TEMP\n")
+			continue
+		}
+		mapName := parts[0]
+		key := strings.ToLower(strings.TrimSpace(parts[1]))
+
+		if mapName != "alias" {
+			fmt.Fprint(conn, "NOTFOUND\n")
+			continue
+		}
+
+		// Only handle our domain
+		if !strings.HasSuffix(key, "@"+strings.ToLower(cfg.Policy.Domain)) {
+			fmt.Fprint(conn, "NOTFOUND\n")
+			continue
+		}
+
+		username, ok, err := db.AliasOwner(key)
+		if err != nil {
+			fmt.Fprint(conn, "TEMP\n")
+			continue
+		}
+		if !ok {
+			fmt.Fprint(conn, "NOTFOUND\n")
+			continue
+		}
+		// rewrite alias -> primary rcpt (username@domain)
+		fmt.Fprintf(conn, "OK %s@%s\n", username, strings.ToLower(cfg.Policy.Domain))
+	}
+}