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mailpit/server/pop3/pop3.go

318 lines
7.3 KiB
Go

// Package pop3 is a simple POP3 server for Mailpit.
// By default it is disabled unless password credentials have been loaded.
//
// References: https://github.com/r0stig/golang-pop3 | https://github.com/inbucket/inbucket
// See RFC: https://datatracker.ietf.org/doc/html/rfc1939
package pop3
import (
"bufio"
"crypto/tls"
"fmt"
"net"
"strconv"
"strings"
"time"
"github.com/axllent/mailpit/config"
"github.com/axllent/mailpit/internal/auth"
"github.com/axllent/mailpit/internal/logger"
"github.com/axllent/mailpit/internal/storage"
"github.com/axllent/mailpit/server/websockets"
)
const (
// UNAUTHORIZED state
UNAUTHORIZED = 1
// TRANSACTION state
TRANSACTION = 2
// UPDATE state
UPDATE = 3
)
// Run will start the pop3 server if enabled
func Run() {
if auth.POP3Credentials == nil || config.POP3Listen == "" {
// POP3 server is disabled without authentication
return
}
var listener net.Listener
var err error
if config.POP3TLSCert != "" {
cer, err2 := tls.LoadX509KeyPair(config.POP3TLSCert, config.POP3TLSKey)
if err2 != nil {
logger.Log().Errorf("[pop3] %s", err2.Error())
return
}
tlsConfig := &tls.Config{
Certificates: []tls.Certificate{cer},
MinVersion: tls.VersionTLS12,
}
listener, err = tls.Listen("tcp", config.POP3Listen, tlsConfig)
} else {
// unencrypted
listener, err = net.Listen("tcp", config.POP3Listen)
}
if err != nil {
logger.Log().Errorf("[pop3] %s", err.Error())
return
}
logger.Log().Infof("[pop3] starting on %s", config.POP3Listen)
for {
conn, err := listener.Accept()
if err != nil {
continue
}
// run as goroutine
go handleClient(conn)
}
}
type message struct {
ID string
Size float64
}
func handleClient(conn net.Conn) {
var (
user = ""
state = 1
toDelete = []string{}
)
defer func() {
if state == UPDATE {
for _, id := range toDelete {
_ = storage.DeleteMessages([]string{id})
}
if len(toDelete) > 0 {
// update web UI to remove deleted messages
websockets.Broadcast("prune", nil)
}
}
if err := conn.Close(); err != nil {
logger.Log().Errorf("[pop3] %s", err.Error())
}
}()
reader := bufio.NewReader(conn)
messages := []message{}
// State
// 1 = Unauthorized
// 2 = Transaction mode
// 3 = update mode
logger.Log().Debugf("[pop3] connection opened by %s", conn.RemoteAddr().String())
// First welcome the new connection
sendResponse(conn, "+OK Mailpit POP3 server")
timeoutDuration := 30 * time.Second
for {
// POP3 server enforced a timeout of 30 seconds
if err := conn.SetDeadline(time.Now().Add(timeoutDuration)); err != nil {
logger.Log().Errorf("[pop3] %s", err.Error())
return
}
// Reads a line from the client
rawLine, err := reader.ReadString('\n')
if err != nil {
logger.Log().Errorf("[pop3] %s", err.Error())
return
}
// Parses the command
cmd, args := getCommand(rawLine)
logger.Log().Debugf("[pop3] received: %s (%s)", strings.TrimSpace(rawLine), conn.RemoteAddr().String())
if cmd == "CAPA" {
// List our capabilities per RFC2449
sendResponse(conn, "+OK Capability list follows")
sendResponse(conn, "TOP")
sendResponse(conn, "USER")
sendResponse(conn, "UIDL")
sendResponse(conn, "IMPLEMENTATION Mailpit")
sendResponse(conn, ".")
continue
} else if cmd == "USER" && state == UNAUTHORIZED {
if len(args) != 1 {
sendResponse(conn, "-ERR must supply a user")
return
}
// always true - stash for PASS
sendResponse(conn, "+OK")
user = args[0]
} else if cmd == "PASS" && state == UNAUTHORIZED {
if len(args) != 1 {
sendResponse(conn, "-ERR must supply a password")
return
}
pass := args[0]
if authUser(user, pass) {
sendResponse(conn, "+OK signed in")
messages, err = getMessages()
if err != nil {
logger.Log().Errorf("[pop3] %s", err.Error())
}
state = 2
} else {
sendResponse(conn, "-ERR invalid password")
logger.Log().Warnf("[pop3] failed login: %s", user)
}
} else if cmd == "STAT" && state == TRANSACTION {
totalSize := float64(0)
for _, m := range messages {
totalSize = totalSize + m.Size
}
sendResponse(conn, fmt.Sprintf("+OK %d %d", len(messages), int64(totalSize)))
} else if cmd == "LIST" && state == TRANSACTION {
totalSize := float64(0)
for _, m := range messages {
totalSize = totalSize + m.Size
}
sendData(conn, fmt.Sprintf("+OK %d messages (%d octets)", len(messages), int64(totalSize)))
// print all sizes
for row, m := range messages {
sendData(conn, fmt.Sprintf("%d %d", row+1, m.Size))
}
// end
sendData(conn, ".")
} else if cmd == "UIDL" && state == TRANSACTION {
totalSize := float64(0)
for _, m := range messages {
totalSize = totalSize + m.Size
}
sendData(conn, "+OK unique-id listing follows")
// print all message IDS
for row, m := range messages {
sendData(conn, fmt.Sprintf("%d %s", row+1, m.ID))
}
// end
sendData(conn, ".")
} else if cmd == "RETR" && state == TRANSACTION {
if len(args) != 1 {
sendResponse(conn, "-ERR no such message")
return
}
nr, err := strconv.Atoi(args[0])
if err != nil {
sendResponse(conn, "-ERR no such message")
return
}
if nr < 1 || nr > len(messages) {
sendResponse(conn, "-ERR no such message")
return
}
m := messages[nr-1]
raw, err := storage.GetMessageRaw(m.ID)
if err != nil {
sendResponse(conn, "-ERR no such message")
return
}
size := len(raw)
sendData(conn, fmt.Sprintf("+OK %d octets", size))
sendData(conn, string(raw))
sendData(conn, ".")
} else if cmd == "TOP" && state == TRANSACTION {
arg, err := getSafeArg(args, 0)
if err != nil {
sendResponse(conn, "-ERR TOP requires two arguments")
return
}
nr, err := strconv.Atoi(arg)
if err != nil {
sendResponse(conn, "-ERR TOP requires two arguments")
return
}
if nr < 1 || nr > len(messages) {
sendResponse(conn, "-ERR no such message")
return
}
arg2, err := getSafeArg(args, 1)
if err != nil {
sendResponse(conn, "-ERR TOP requires two arguments")
return
}
lines, err := strconv.Atoi(arg2)
if err != nil {
sendResponse(conn, "-ERR TOP requires two arguments")
return
}
m := messages[nr-1]
headers, body, err := getTop(m.ID, lines)
if err != nil {
sendResponse(conn, err.Error())
return
}
sendData(conn, "+OK Top of message follows")
sendData(conn, headers+"\r\n")
sendData(conn, body)
sendData(conn, ".")
} else if cmd == "NOOP" && state == TRANSACTION {
sendData(conn, "+OK")
} else if cmd == "DELE" && state == TRANSACTION {
arg, _ := getSafeArg(args, 0)
nr, err := strconv.Atoi(arg)
if err != nil {
logger.Log().Warnf("[pop3] -ERR invalid DELETE integer: %s", arg)
sendResponse(conn, "-ERR invalid integer")
return
}
if nr < 1 || nr > len(messages) {
logger.Log().Warnf("[pop3] -ERR no such message")
sendResponse(conn, "-ERR no such message")
return
}
toDelete = append(toDelete, messages[nr-1].ID)
sendResponse(conn, "+OK")
} else if cmd == "RSET" && state == TRANSACTION {
toDelete = []string{}
sendData(conn, "+OK")
} else if cmd == "QUIT" {
state = UPDATE
return
} else {
logger.Log().Warnf("[pop3] -ERR %s not implemented", cmd)
sendResponse(conn, fmt.Sprintf("-ERR %s not implemented", cmd))
}
}
}