package main import ( "crypto/tls" "errors" "fmt" "io" "io/ioutil" "net" "os" "path" "github.com/uber-go/zap" "src.bluestatic.org/mailpopbox/pop3" ) func runPOP3Server(config Config, log zap.Logger) <-chan error { server := pop3Server{ config: config, rc: make(chan error), log: log.With(zap.String("server", "pop3")), } go server.run() return server.rc } type pop3Server struct { config Config rc chan error log zap.Logger } func (server *pop3Server) run() { for _, s := range server.config.Servers { if err := os.Mkdir(s.MaildropPath, 0700); err != nil && !os.IsExist(err) { server.log.Error("failed to open maildrop", zap.Error(err)) server.rc <- err } } tlsConfig, err := server.config.GetTLSConfig() if err != nil { server.log.Error("failed to configure TLS", zap.Error(err)) server.rc <- err return } addr := fmt.Sprintf(":%d", server.config.POP3Port) server.log.Info("starting server", zap.String("address", addr)) var l net.Listener if tlsConfig == nil { l, err = net.Listen("tcp", addr) } else { l, err = tls.Listen("tcp", addr, tlsConfig) } if err != nil { server.log.Error("listen", zap.Error(err)) server.rc <- err return } for { conn, err := l.Accept() if err != nil { server.log.Error("accept", zap.Error(err)) server.rc <- err break } go pop3.AcceptConnection(conn, server, server.log) } } func (server *pop3Server) Name() string { return server.config.Hostname } func (server *pop3Server) OpenMailbox(user, pass string) (pop3.Mailbox, error) { for _, s := range server.config.Servers { if user == "mailbox@"+s.Domain && pass == s.MailboxPassword { return server.openMailbox(s.MaildropPath) } } return nil, errors.New("permission denied") } func (server *pop3Server) openMailbox(maildrop string) (*mailbox, error) { files, err := ioutil.ReadDir(maildrop) if err != nil { // TODO: hide error, log instead return nil, err } mb := &mailbox{ messages: make([]message, 0, len(files)), } i := 0 for _, file := range files { if file.IsDir() { continue } msg := message{ filename: path.Join(maildrop, file.Name()), index: i, size: file.Size(), } mb.messages = append(mb.messages, msg) i++ } return mb, nil } type mailbox struct { messages []message } type message struct { filename string index int size int64 deleted bool } func (m message) ID() int { return m.index + 1 } func (m message) Size() int { return int(m.size) } func (m message) Deleted() bool { return m.deleted } func (mb *mailbox) ListMessages() ([]pop3.Message, error) { msgs := make([]pop3.Message, len(mb.messages)) for i := 0; i < len(mb.messages); i++ { msgs[i] = &mb.messages[i] } return msgs, nil } func (mb *mailbox) GetMessage(id int) pop3.Message { if id > len(mb.messages) { return nil } return &mb.messages[id-1] } func (mb *mailbox) Retrieve(msg pop3.Message) (io.ReadCloser, error) { filename := msg.(*message).filename return os.Open(filename) } func (mb *mailbox) Delete(msg pop3.Message) error { msg.(*message).deleted = true return nil } func (mb *mailbox) Close() error { for _, message := range mb.messages { if message.deleted { os.Remove(message.filename) } } return nil } func (mb *mailbox) Reset() { for _, message := range mb.messages { message.deleted = false } }