一阶段ok

2026-06-01 18:59:55 +08:00
commit 9e50d05e71
52 changed files with 6155 additions and 0 deletions
@@ -0,0 +1,465 @@
+package pop3_server
+
+import (
+	"bufio"
+	"fmt"
+	"log"
+	"net"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+
+	"mail_go/config"
+	"mail_go/internal/db"
+	"mail_go/internal/store"
+)
+
+// POP3Server implements a simple POP3 mail server over TCP.
+type POP3Server struct {
+	listener net.Listener
+	stores   *store.Stores
+	cfg      config.POP3Config
+	wg       sync.WaitGroup
+}
+
+// NewPOP3Server creates a new POP3 server instance.
+func NewPOP3Server(cfg config.POP3Config, stores *store.Stores) *POP3Server {
+	return &POP3Server{
+		stores: stores,
+		cfg:    cfg,
+	}
+}
+
+// Start starts the POP3 server on the configured plain-text port.
+func (s *POP3Server) Start() error {
+	var err error
+	s.listener, err = net.Listen("tcp", s.cfg.Addr)
+	if err != nil {
+		return fmt.Errorf("POP3 listen failed: %w", err)
+	}
+
+	log.Printf("POP3 server listening on %s", s.cfg.Addr)
+
+	s.wg.Add(1)
+	go func() {
+		defer s.wg.Done()
+		for {
+			conn, err := s.listener.Accept()
+			if err != nil {
+				// Listener closed
+				return
+			}
+			s.wg.Add(1)
+			go func() {
+				defer s.wg.Done()
+				s.handleConn(conn)
+			}()
+		}
+	}()
+
+	return nil
+}
+
+// StartTLS starts the POP3 server on the configured TLS port.
+func (s *POP3Server) StartTLS() error {
+	if s.cfg.TLSCert == "" || s.cfg.TLSKey == "" {
+		return fmt.Errorf("POP3 TLS certificate or key not configured")
+	}
+	return fmt.Errorf("POP3 TLS not yet implemented")
+}
+
+// handleConn handles a single POP3 client connection.
+func (s *POP3Server) handleConn(conn net.Conn) {
+	defer conn.Close()
+
+	// Set read/write deadlines
+	conn.SetDeadline(time.Now().Add(10 * time.Minute))
+
+	reader := bufio.NewReader(conn)
+
+	// Session state
+	var user *db.User
+	var messages []pop3Message
+	var deleted map[int]bool
+
+	// Send greeting
+	sendResponse(conn, "+OK MailGo POP3 server ready")
+
+	// Main command loop
+	for {
+		line, err := reader.ReadString('\n')
+		if err != nil {
+			return // connection closed or error
+		}
+
+		line = strings.TrimSpace(line)
+		if line == "" {
+			continue
+		}
+
+		// Parse command
+		parts := strings.SplitN(line, " ", 2)
+		cmd := strings.ToUpper(parts[0])
+		arg := ""
+		if len(parts) > 1 {
+			arg = strings.TrimSpace(parts[1])
+		}
+
+		switch cmd {
+		case "USER":
+			user, messages, deleted = s.handleUSER(conn, arg, user)
+		case "PASS":
+			user, messages, deleted = s.handlePASS(conn, arg, user)
+		case "STAT":
+			s.handleSTAT(conn, messages, deleted)
+		case "LIST":
+			s.handleLIST(conn, arg, messages, deleted)
+		case "RETR":
+			s.handleRETR(conn, arg, messages, deleted)
+		case "DELE":
+			s.handleDELE(conn, arg, deleted)
+		case "NOOP":
+			sendResponse(conn, "+OK")
+		case "RSET":
+			deleted = make(map[int]bool)
+			sendResponse(conn, "+OK")
+		case "QUIT":
+			// In UPDATE state, actually delete marked messages
+			s.expungeDeleted(messages, deleted, user)
+			sendResponse(conn, "+OK MailGo POP3 server signing off")
+			return
+		case "CAPA":
+			sendResponse(conn, "+OK Capability list follows")
+			sendResponse(conn, "USER")
+			sendResponse(conn, ".")
+		case "TOP":
+			s.handleTOP(conn, arg, messages, deleted)
+		case "UIDL":
+			s.handleUIDL(conn, arg, messages, deleted)
+		default:
+			sendResponse(conn, "-ERR unknown command")
+		}
+	}
+}
+
+// pop3Message holds a message and its computed size for POP3.
+type pop3Message struct {
+	id      uint
+	raw     string
+	size    int
+	message *db.Message
+}
+
+// loadMessages loads all INBOX messages for a user.
+func (s *POP3Server) loadMessages(user *db.User) []pop3Message {
+	if user == nil {
+		return nil
+	}
+
+	dbMsgs, err := s.stores.Mails.ListAllByUserAndFolder(user.ID, "INBOX")
+	if err != nil {
+		return nil
+	}
+
+	msgs := make([]pop3Message, 0, len(dbMsgs))
+	for i := range dbMsgs {
+		raw := string(buildRawMessage(&dbMsgs[i]))
+		msgs = append(msgs, pop3Message{
+			id:      dbMsgs[i].ID,
+			raw:     raw,
+			size:    len(raw),
+			message: &dbMsgs[i],
+		})
+	}
+	return msgs
+}
+
+// handleUSER processes the USER command.
+func (s *POP3Server) handleUSER(conn net.Conn, username string, currentUser *db.User) (*db.User, []pop3Message, map[int]bool) {
+	if username == "" {
+		sendResponse(conn, "-ERR missing username")
+		return currentUser, nil, nil
+	}
+
+	// Look up the user by email
+	user, err := s.stores.Users.GetByEmail(username)
+	if err != nil {
+		// Don't reveal whether user exists yet (standard POP3 behavior)
+		sendResponse(conn, "+OK")
+		// Store the attempted username for PASS to use
+		return &db.User{Username: username}, nil, nil
+	}
+
+	sendResponse(conn, "+OK")
+	return user, nil, nil
+}
+
+// handlePASS processes the PASS command.
+func (s *POP3Server) handlePASS(conn net.Conn, password string, user *db.User) (*db.User, []pop3Message, map[int]bool) {
+	if user == nil {
+		sendResponse(conn, "-ERR no username given")
+		return nil, nil, nil
+	}
+
+	// Authenticate
+	authUser, err := s.stores.Users.Authenticate(user.Username, password)
+	if err != nil {
+		// If username was an email, try using it directly
+		if strings.Contains(user.Username, "@") {
+			authUser, err = s.stores.Users.Authenticate(user.Username, password)
+		}
+		if err != nil {
+			sendResponse(conn, "-ERR authentication failed")
+			return nil, nil, nil
+		}
+	}
+
+	// Load messages
+	messages := s.loadMessages(authUser)
+	deleted := make(map[int]bool)
+
+	sendResponse(conn, fmt.Sprintf("+OK authenticated, %d messages", len(messages)))
+	return authUser, messages, deleted
+}
+
+// handleSTAT processes the STAT command.
+func (s *POP3Server) handleSTAT(conn net.Conn, messages []pop3Message, deleted map[int]bool) {
+	count := 0
+	totalSize := 0
+	for i, msg := range messages {
+		if !deleted[i+1] {
+			count++
+			totalSize += msg.size
+		}
+	}
+	sendResponse(conn, fmt.Sprintf("+OK %d %d", count, totalSize))
+}
+
+// handleLIST processes the LIST command (with optional message number).
+func (s *POP3Server) handleLIST(conn net.Conn, arg string, messages []pop3Message, deleted map[int]bool) {
+	if arg == "" {
+		// List all messages
+		sendResponse(conn, "+OK message list follows")
+		for i, msg := range messages {
+			if !deleted[i+1] {
+				sendResponse(conn, fmt.Sprintf("%d %d", i+1, msg.size))
+			}
+		}
+		sendResponse(conn, ".")
+	} else {
+		// List specific message
+		num, err := strconv.Atoi(arg)
+		if err != nil || num < 1 || num > len(messages) {
+			sendResponse(conn, "-ERR no such message")
+			return
+		}
+		if deleted[num] {
+			sendResponse(conn, "-ERR message deleted")
+			return
+		}
+		sendResponse(conn, fmt.Sprintf("+OK %d %d", num, messages[num-1].size))
+	}
+}
+
+// handleRETR processes the RETR command.
+func (s *POP3Server) handleRETR(conn net.Conn, arg string, messages []pop3Message, deleted map[int]bool) {
+	num, err := strconv.Atoi(arg)
+	if err != nil || num < 1 || num > len(messages) {
+		sendResponse(conn, "-ERR no such message")
+		return
+	}
+	if deleted[num] {
+		sendResponse(conn, "-ERR message deleted")
+		return
+	}
+
+	msg := messages[num-1]
+	sendResponse(conn, fmt.Sprintf("+OK %d octets", msg.size))
+
+	// Send the raw message, dot-stuffing any lines that start with "."
+	scanner := bufio.NewScanner(strings.NewReader(msg.raw))
+	for scanner.Scan() {
+		line := scanner.Text()
+		if strings.HasPrefix(line, ".") {
+			conn.Write([]byte("."))
+		}
+		conn.Write([]byte(line + "\r\n"))
+	}
+	conn.Write([]byte(".\r\n"))
+}
+
+// handleDELE processes the DELE command.
+func (s *POP3Server) handleDELE(conn net.Conn, arg string, deleted map[int]bool) {
+	num, err := strconv.Atoi(arg)
+	if err != nil || num < 1 {
+		sendResponse(conn, "-ERR invalid message number")
+		return
+	}
+	if deleted == nil {
+		deleted = make(map[int]bool)
+	}
+	if deleted[num] {
+		sendResponse(conn, "-ERR message already deleted")
+		return
+	}
+	deleted[num] = true
+	sendResponse(conn, "+OK message marked for deletion")
+}
+
+// handleTOP processes the TOP command (headers + first N lines of body).
+func (s *POP3Server) handleTOP(conn net.Conn, arg string, messages []pop3Message, deleted map[int]bool) {
+	// Format: TOP msgNum [n]
+	parts := strings.Fields(arg)
+	if len(parts) < 1 {
+		sendResponse(conn, "-ERR syntax error")
+		return
+	}
+
+	num, err := strconv.Atoi(parts[0])
+	if err != nil || num < 1 || num > len(messages) {
+		sendResponse(conn, "-ERR no such message")
+		return
+	}
+	if deleted != nil && deleted[num] {
+		sendResponse(conn, "-ERR message deleted")
+		return
+	}
+
+	nLines := 0
+	if len(parts) > 1 {
+		nLines, _ = strconv.Atoi(parts[1])
+	}
+
+	msg := messages[num-1]
+	sendResponse(conn, "+OK top of message follows")
+
+	// Find blank line separating headers from body
+	headerEnd := strings.Index(msg.raw, "\r\n\r\n")
+	if headerEnd == -1 {
+		headerEnd = strings.Index(msg.raw, "\n\n")
+		if headerEnd == -1 {
+			// No body, just send everything
+			sendResponse(conn, msg.raw)
+			sendResponse(conn, ".")
+			return
+		}
+	}
+
+	// Send headers
+	header := msg.raw[:headerEnd]
+	scanner := bufio.NewScanner(strings.NewReader(header))
+	for scanner.Scan() {
+		line := scanner.Text()
+		if strings.HasPrefix(line, ".") {
+			conn.Write([]byte("."))
+		}
+		conn.Write([]byte(line + "\r\n"))
+	}
+	conn.Write([]byte("\r\n"))
+
+	// Send up to N lines of body
+	if nLines > 0 {
+		body := msg.raw[headerEnd:]
+		scanner := bufio.NewScanner(strings.NewReader(body))
+		lineCount := 0
+		for scanner.Scan() && lineCount < nLines {
+			line := scanner.Text()
+			if strings.HasPrefix(line, ".") {
+				conn.Write([]byte("."))
+			}
+			conn.Write([]byte(line + "\r\n"))
+			lineCount++
+		}
+	}
+
+	conn.Write([]byte(".\r\n"))
+}
+
+// handleUIDL processes the UIDL command.
+func (s *POP3Server) handleUIDL(conn net.Conn, arg string, messages []pop3Message, deleted map[int]bool) {
+	if arg == "" {
+		// List all UIDs
+		sendResponse(conn, "+OK UIDL list follows")
+		for i, msg := range messages {
+			if deleted == nil || !deleted[i+1] {
+				sendResponse(conn, fmt.Sprintf("%d %d", i+1, msg.id))
+			}
+		}
+		sendResponse(conn, ".")
+	} else {
+		// Specific message UID
+		num, err := strconv.Atoi(arg)
+		if err != nil || num < 1 || num > len(messages) {
+			sendResponse(conn, "-ERR no such message")
+			return
+		}
+		if deleted != nil && deleted[num] {
+			sendResponse(conn, "-ERR message deleted")
+			return
+		}
+		sendResponse(conn, fmt.Sprintf("+OK %d %d", num, messages[num-1].id))
+	}
+}
+
+// expungeDeleted actually deletes messages that were marked for deletion.
+func (s *POP3Server) expungeDeleted(messages []pop3Message, deleted map[int]bool, user *db.User) {
+	if deleted == nil || user == nil {
+		return
+	}
+	for seqNum, msgDeleted := range deleted {
+		if msgDeleted && seqNum >= 1 && seqNum <= len(messages) {
+			if err := s.stores.Mails.Delete(messages[seqNum-1].id); err != nil {
+				log.Printf("POP3: failed to delete message %d: %v", messages[seqNum-1].id, err)
+			}
+		}
+	}
+}
+
+// sendResponse writes a POP3 response line to the connection.
+func sendResponse(conn net.Conn, line string) {
+	conn.Write([]byte(line + "\r\n"))
+}
+
+// buildRawMessage reconstructs a raw RFC822 message from a db.Message.
+// This is a local copy to avoid importing from the imap_server package.
+func buildRawMessage(msg *db.Message) []byte {
+	var buf strings.Builder
+
+	buf.WriteString(fmt.Sprintf("From: %s\r\n", msg.FromAddr))
+	buf.WriteString(fmt.Sprintf("To: %s\r\n", msg.ToAddr))
+	if msg.CcAddr != "" {
+		buf.WriteString(fmt.Sprintf("Cc: %s\r\n", msg.CcAddr))
+	}
+	buf.WriteString(fmt.Sprintf("Subject: %s\r\n", msg.Subject))
+	buf.WriteString(fmt.Sprintf("Date: %s\r\n", msg.Date.Format("Mon, 02 Jan 2006 15:04:05 -0700")))
+	if msg.MessageID != "" {
+		buf.WriteString(fmt.Sprintf("Message-ID: %s\r\n", msg.MessageID))
+	}
+	buf.WriteString("MIME-Version: 1.0\r\n")
+
+	if msg.HtmlBody != "" && msg.TextBody != "" {
+		boundary := fmt.Sprintf("mailgo_%d", msg.ID)
+		buf.WriteString(fmt.Sprintf("Content-Type: multipart/alternative; boundary=\"%s\"\r\n", boundary))
+		buf.WriteString("\r\n")
+		buf.WriteString(fmt.Sprintf("--%s\r\n", boundary))
+		buf.WriteString("Content-Type: text/plain; charset=utf-8\r\n\r\n")
+		buf.WriteString(msg.TextBody)
+		buf.WriteString("\r\n")
+		buf.WriteString(fmt.Sprintf("--%s\r\n", boundary))
+		buf.WriteString("Content-Type: text/html; charset=utf-8\r\n\r\n")
+		buf.WriteString(msg.HtmlBody)
+		buf.WriteString("\r\n")
+		buf.WriteString(fmt.Sprintf("--%s--\r\n", boundary))
+	} else if msg.TextBody != "" {
+		buf.WriteString("Content-Type: text/plain; charset=utf-8\r\n\r\n")
+		buf.WriteString(msg.TextBody)
+	} else if msg.HtmlBody != "" {
+		buf.WriteString("Content-Type: text/html; charset=utf-8\r\n\r\n")
+		buf.WriteString(msg.HtmlBody)
+	} else {
+		buf.WriteString("Content-Type: text/plain; charset=utf-8\r\n\r\n")
+	}
+
+	return []byte(buf.String())
+}