pop3/conn.go

   1 package pop3
   2
   3 import (
   4         "fmt"
   5         "io"
   6         "net"
   7         "net/textproto"
   8         "strings"
   9
  10         "github.com/uber-go/zap"
  11 )
  12
  13 type state int
  14
  15 const (
  16         stateAuth state = iota
  17         stateTxn
  18         stateUpdate
  19 )
  20
  21 const (
  22         errStateAuth  = "not in AUTHORIZATION"
  23         errStateTxn   = "not in TRANSACTION"
  24         errSyntax     = "syntax error"
  25         errDeletedMsg = "no such message - deleted"
  26 )
  27
  28 type connection struct {
  29         po PostOffice
  30         mb Mailbox
  31
  32         tp         *textproto.Conn
  33         remoteAddr net.Addr
  34
  35         log zap.Logger
  36
  37         state
  38         line string
  39
  40         user string
  41 }
  42
  43 func AcceptConnection(netConn net.Conn, po PostOffice, log zap.Logger) {
  44         log = log.With(zap.Stringer("client", netConn.RemoteAddr()))
  45         conn := connection{
  46                 po:    po,
  47                 tp:    textproto.NewConn(netConn),
  48                 state: stateAuth,
  49                 log:   log,
  50         }
  51
  52         conn.log.Info("accepted connection")
  53         conn.ok(fmt.Sprintf("POP3 (mailpopbox) server %s", po.Name()))
  54
  55         var err error
  56
  57         for {
  58                 conn.line, err = conn.tp.ReadLine()
  59                 if err != nil {
  60                         conn.log.Error("ReadLine()", zap.Error(err))
  61                         conn.tp.Close()
  62                         return
  63                 }
  64
  65                 var cmd string
  66                 if _, err := fmt.Sscanf(conn.line, "%s", &cmd); err != nil {
  67                         conn.err("invalid command")
  68                         continue
  69                 }
  70
  71                 conn.log = log.With(zap.String("command", cmd))
  72
  73                 switch strings.ToUpper(cmd) {
  74                 case "QUIT":
  75                         conn.doQUIT()
  76                         return
  77                 case "USER":
  78                         conn.doUSER()
  79                 case "PASS":
  80                         conn.doPASS()
  81                 case "STAT":
  82                         conn.doSTAT()
  83                 case "LIST":
  84                         conn.doLIST()
  85                 case "RETR":
  86                         conn.doRETR()
  87                 case "DELE":
  88                         conn.doDELE()
  89                 case "NOOP":
  90                         conn.ok("")
  91                 case "RSET":
  92                         conn.doRSET()
  93                 case "UIDL":
  94                         conn.doUIDL()
  95                 default:
  96                         conn.log.Error("unknown command")
  97                         conn.err("unknown command")
  98                 }
  99         }
 100 }
 101
 102 func (conn *connection) ok(msg string) {
 103         if len(msg) > 0 {
 104                 msg = " " + msg
 105         }
 106         conn.tp.PrintfLine("+OK%s", msg)
 107 }
 108
 109 func (conn *connection) err(msg string) {
 110         conn.log.Error("error", zap.String("message", msg))
 111         if len(msg) > 0 {
 112                 msg = " " + msg
 113                 conn.tp.PrintfLine("-ERR%s", msg)
 114         }
 115 }
 116
 117 func (conn *connection) doQUIT() {
 118         defer conn.tp.Close()
 119
 120         if conn.mb != nil {
 121                 err := conn.mb.Close()
 122                 if err != nil {
 123                         conn.err("failed to remove some messages")
 124                         return
 125                 }
 126         }
 127         conn.ok("goodbye")
 128 }
 129
 130 func (conn *connection) doUSER() {
 131         if conn.state != stateAuth {
 132                 conn.err(errStateAuth)
 133                 return
 134         }
 135
 136         cmd := len("USER ")
 137         if len(conn.line) < cmd {
 138                 conn.err("invalid user")
 139                 return
 140         }
 141
 142         conn.user = conn.line[cmd:]
 143         conn.ok("")
 144 }
 145
 146 func (conn *connection) doPASS() {
 147         if conn.state != stateAuth {
 148                 conn.err(errStateAuth)
 149                 return
 150         }
 151
 152         if len(conn.user) == 0 {
 153                 conn.err("no USER")
 154                 return
 155         }
 156
 157         cmd := len("PASS ")
 158         if len(conn.line) < cmd {
 159                 conn.err("invalid pass")
 160                 return
 161         }
 162
 163         pass := conn.line[cmd:]
 164         if mbox, err := conn.po.OpenMailbox(conn.user, pass); err == nil {
 165                 conn.log.Info("authenticated", zap.String("user", conn.user))
 166                 conn.state = stateTxn
 167                 conn.mb = mbox
 168                 conn.ok("")
 169         } else {
 170                 conn.log.Error("failed to open mailbox", zap.Error(err))
 171                 conn.err(err.Error())
 172         }
 173 }
 174
 175 func (conn *connection) doSTAT() {
 176         if conn.state != stateTxn {
 177                 conn.err(errStateTxn)
 178                 return
 179         }
 180
 181         msgs, err := conn.mb.ListMessages()
 182         if err != nil {
 183                 conn.log.Error("failed to list messages", zap.Error(err))
 184                 conn.err(err.Error())
 185                 return
 186         }
 187
 188         size := 0
 189         num := 0
 190         for _, msg := range msgs {
 191                 if msg.Deleted() {
 192                         continue
 193                 }
 194                 size += msg.Size()
 195                 num++
 196         }
 197
 198         conn.ok(fmt.Sprintf("%d %d", num, size))
 199 }
 200
 201 func (conn *connection) doLIST() {
 202         if conn.state != stateTxn {
 203                 conn.err(errStateTxn)
 204                 return
 205         }
 206
 207         msgs, err := conn.mb.ListMessages()
 208         if err != nil {
 209                 conn.log.Error("failed to list messages", zap.Error(err))
 210                 conn.err(err.Error())
 211                 return
 212         }
 213
 214         conn.ok("scan listing")
 215         for _, msg := range msgs {
 216                 conn.tp.PrintfLine("%d %d", msg.ID(), msg.Size())
 217         }
 218         conn.tp.PrintfLine(".")
 219 }
 220
 221 func (conn *connection) doRETR() {
 222         if conn.state != stateTxn {
 223                 conn.err(errStateTxn)
 224                 return
 225         }
 226
 227         msg := conn.getRequestedMessage()
 228         if msg == nil {
 229                 return
 230         }
 231
 232         if msg.Deleted() {
 233                 conn.err(errDeletedMsg)
 234                 return
 235         }
 236
 237         rc, err := conn.mb.Retrieve(msg)
 238         if err != nil {
 239                 conn.log.Error("failed to retrieve messages", zap.Error(err))
 240                 conn.err(err.Error())
 241                 return
 242         }
 243
 244         conn.ok(fmt.Sprintf("%d", msg.Size()))
 245
 246         w := conn.tp.DotWriter()
 247         io.Copy(w, rc)
 248         w.Close()
 249 }
 250
 251 func (conn *connection) doDELE() {
 252         if conn.state != stateTxn {
 253                 conn.err(errStateTxn)
 254                 return
 255         }
 256
 257         msg := conn.getRequestedMessage()
 258         if msg == nil {
 259                 return
 260         }
 261
 262         if msg.Deleted() {
 263                 conn.err(errDeletedMsg)
 264                 return
 265         }
 266
 267         if err := conn.mb.Delete(msg); err != nil {
 268                 conn.log.Error("failed to delete message", zap.Error(err))
 269                 conn.err(err.Error())
 270         } else {
 271                 conn.ok("")
 272         }
 273 }
 274
 275 func (conn *connection) doRSET() {
 276         if conn.state != stateTxn {
 277                 conn.err(errStateTxn)
 278                 return
 279         }
 280         conn.mb.Reset()
 281         conn.ok("")
 282 }
 283
 284 func (conn *connection) doUIDL() {
 285         if conn.state != stateTxn {
 286                 conn.err(errStateTxn)
 287                 return
 288         }
 289
 290         msgs, err := conn.mb.ListMessages()
 291         if err != nil {
 292                 conn.log.Error("failed to list messages", zap.Error(err))
 293                 conn.err(err.Error())
 294                 return
 295         }
 296
 297         conn.ok("unique-id listing")
 298         for _, msg := range msgs {
 299                 if msg.Deleted() {
 300                         continue
 301                 }
 302                 conn.tp.PrintfLine("%d %s", msg.ID(), msg.UniqueID())
 303         }
 304         conn.tp.PrintfLine(".")
 305 }
 306
 307 func (conn *connection) getRequestedMessage() Message {
 308         var cmd string
 309         var idx int
 310         if _, err := fmt.Sscanf(conn.line, "%s %d", &cmd, &idx); err != nil {
 311                 conn.err(errSyntax)
 312                 return nil
 313         }
 314
 315         if idx < 1 {
 316                 conn.err("invalid message-number")
 317                 return nil
 318         }
 319
 320         msg := conn.mb.GetMessage(idx)
 321         if msg == nil {
 322                 conn.err("no such message")
 323                 return nil
 324         }
 325         return msg
 326 }