pop3/conn.go

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