first commit

internal/managesieve/server.go

@@ -0,0 +1,90 @@
+// Package managesieve implements a RFC 5804 ManageSieve server — the
+// protocol mail clients (Thunderbird's Sieve plugin, etc.) use to upload and
+// manage server-side filtering scripts. Every uploaded script is validated
+// with internal/sieve's parser before being stored, so a syntactically
+// invalid script is rejected at PUTSCRIPT time rather than silently failing
+// at delivery time.
+package managesieve
+
+import (
+	"context"
+	"crypto/tls"
+	"fmt"
+	"log/slog"
+	"net"
+	"sync"
+	"time"
+
+	"gomail/internal/db"
+)
+
+const idleTimeout = 10 * time.Minute
+
+type Server struct {
+	database *db.DB
+	tlsConf  *tls.Config
+	hostname string
+
+	listener  net.Listener
+	wg        sync.WaitGroup
+	sessionWG sync.WaitGroup
+}
+
+func NewServer(database *db.DB, tlsConf *tls.Config, hostname string) *Server {
+	return &Server{database: database, tlsConf: tlsConf, hostname: hostname}
+}
+
+func (s *Server) ListenAndServe(ctx context.Context, addr string) error {
+	ln, err := net.Listen("tcp", addr)
+	if err != nil {
+		return fmt.Errorf("listen %s: %w", addr, err)
+	}
+	s.listener = ln
+	slog.Info("ManageSieve listener started", "addr", addr)
+
+	s.wg.Add(1)
+	go func() {
+		defer s.wg.Done()
+		s.acceptLoop(ctx, ln)
+	}()
+
+	<-ctx.Done()
+	return ctx.Err()
+}
+
+func (s *Server) acceptLoop(ctx context.Context, ln net.Listener) {
+	for {
+		conn, err := ln.Accept()
+		if err != nil {
+			select {
+			case <-ctx.Done():
+				return
+			default:
+				slog.Error("ManageSieve accept error", "err", err)
+				return
+			}
+		}
+		s.sessionWG.Add(1)
+		go func() {
+			defer s.sessionWG.Done()
+			newSession(conn, s).run(ctx)
+		}()
+	}
+}
+
+func (s *Server) Shutdown(gracePeriod time.Duration) {
+	if s.listener != nil {
+		s.listener.Close()
+	}
+	s.wg.Wait()
+	done := make(chan struct{})
+	go func() {
+		s.sessionWG.Wait()
+		close(done)
+	}()
+	select {
+	case <-done:
+	case <-time.After(gracePeriod):
+		slog.Warn("ManageSieve shutdown grace period expired")
+	}
+}