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.err("unknown command")
  97                 }
  98         }
  99 }
 100
 101 func (conn *connection) ok(msg string) {
 102         if len(msg) > 0 {
 103                 msg = " " + msg
 104         }
 105         conn.tp.PrintfLine("+OK%s", msg)
 106 }
 107
 108 func (conn *connection) err(msg string) {
 109         conn.log.Error("error", zap.String("message", msg))
 110         if len(msg) > 0 {
 111                 msg = " " + msg
 112                 conn.tp.PrintfLine("-ERR%s", msg)
 113         }
 114 }
 115
 116 func (conn *connection) doQUIT() {
 117         defer conn.tp.Close()
 118
 119         if conn.mb != nil {
 120                 err := conn.mb.Close()
 121                 if err != nil {
 122                         conn.err("failed to remove some messages")
 123                         return
 124                 }
 125         }
 126         conn.ok("goodbye")
 127 }
 128
 129 func (conn *connection) doUSER() {
 130         if conn.state != stateAuth {
 131                 conn.err(errStateAuth)
 132                 return
 133         }
 134
 135         cmd := len("USER ")
 136         if len(conn.line) < cmd {
 137                 conn.err("invalid user")
 138                 return
 139         }
 140
 141         conn.user = conn.line[cmd:]
 142         conn.ok("")
 143 }
 144
 145 func (conn *connection) doPASS() {
 146         if conn.state != stateAuth {
 147                 conn.err(errStateAuth)
 148                 return
 149         }
 150
 151         if len(conn.user) == 0 {
 152                 conn.err("no USER")
 153                 return
 154         }
 155
 156         cmd := len("PASS ")
 157         if len(conn.line) < cmd {
 158                 conn.err("invalid pass")
 159                 return
 160         }
 161
 162         pass := conn.line[cmd:]
 163         if mbox, err := conn.po.OpenMailbox(conn.user, pass); err == nil {
 164                 conn.log.Info("authenticated", zap.String("user", conn.user))
 165                 conn.state = stateTxn
 166                 conn.mb = mbox
 167                 conn.ok("")
 168         } else {
 169                 conn.log.Error("failed to open mailbox", zap.Error(err))
 170                 conn.err(err.Error())
 171         }
 172 }
 173
 174 func (conn *connection) doSTAT() {
 175         if conn.state != stateTxn {
 176                 conn.err(errStateTxn)
 177                 return
 178         }
 179
 180         msgs, err := conn.mb.ListMessages()
 181         if err != nil {
 182                 conn.log.Error("failed to list messages", zap.Error(err))
 183                 conn.err(err.Error())
 184                 return
 185         }
 186
 187         size := 0
 188         num := 0
 189         for _, msg := range msgs {
 190                 if msg.Deleted() {
 191                         continue
 192                 }
 193                 size += msg.Size()
 194                 num++
 195         }
 196
 197         conn.ok(fmt.Sprintf("%d %d", num, size))
 198 }
 199
 200 func (conn *connection) doLIST() {
 201         if conn.state != stateTxn {
 202                 conn.err(errStateTxn)
 203                 return
 204         }
 205
 206         msgs, err := conn.mb.ListMessages()
 207         if err != nil {
 208                 conn.log.Error("failed to list messages", zap.Error(err))
 209                 conn.err(err.Error())
 210                 return
 211         }
 212
 213         conn.ok("scan listing")
 214         for _, msg := range msgs {
 215                 conn.tp.PrintfLine("%d %d", msg.ID(), msg.Size())
 216         }
 217         conn.tp.PrintfLine(".")
 218 }
 219
 220 func (conn *connection) doRETR() {
 221         if conn.state != stateTxn {
 222                 conn.err(errStateTxn)
 223                 return
 224         }
 225
 226         msg := conn.getRequestedMessage()
 227         if msg == nil {
 228                 return
 229         }
 230
 231         if msg.Deleted() {
 232                 conn.err(errDeletedMsg)
 233                 return
 234         }
 235
 236         rc, err := conn.mb.Retrieve(msg)
 237         if err != nil {
 238                 conn.log.Error("failed to retrieve messages", zap.Error(err))
 239                 conn.err(err.Error())
 240                 return
 241         }
 242
 243         conn.log.Info("retreive message", zap.String("unique-id", msg.UniqueID()))
 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.log.Info("delete message", zap.String("unique-id", msg.UniqueID()))
 272                 conn.ok("")
 273         }
 274 }
 275
 276 func (conn *connection) doRSET() {
 277         if conn.state != stateTxn {
 278                 conn.err(errStateTxn)
 279                 return
 280         }
 281         conn.mb.Reset()
 282         conn.log.Info("reset")
 283         conn.ok("")
 284 }
 285
 286 func (conn *connection) doUIDL() {
 287         if conn.state != stateTxn {
 288                 conn.err(errStateTxn)
 289                 return
 290         }
 291
 292         msgs, err := conn.mb.ListMessages()
 293         if err != nil {
 294                 conn.log.Error("failed to list messages", zap.Error(err))
 295                 conn.err(err.Error())
 296                 return
 297         }
 298
 299         conn.ok("unique-id listing")
 300         for _, msg := range msgs {
 301                 if msg.Deleted() {
 302                         continue
 303                 }
 304                 conn.tp.PrintfLine("%d %s", msg.ID(), msg.UniqueID())
 305         }
 306         conn.tp.PrintfLine(".")
 307 }
 308
 309 func (conn *connection) getRequestedMessage() Message {
 310         var cmd string
 311         var idx int
 312         if _, err := fmt.Sscanf(conn.line, "%s %d", &cmd, &idx); err != nil {
 313                 conn.err(errSyntax)
 314                 return nil
 315         }
 316
 317         if idx < 1 {
 318                 conn.err("invalid message-number")
 319                 return nil
 320         }
 321
 322         msg := conn.mb.GetMessage(idx)
 323         if msg == nil {
 324                 conn.err("no such message")
 325                 return nil
 326         }
 327         return msg
 328 }