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go-autoresponder/cmd/autoresponder.go

657 lines
22 KiB
Go

package main
// This is postfix autoresponder, which is rewrite of the autoresponder bash script V1.6.3, written by Charles Hamilton - musashi@nefaria.com
//
// How to make it work on a server with postfix installed:
// =======================================================
// Create autoresponder username:
// useradd -d /var/spool/autoresponder -s $(which nologin) autoresponder
//
// Copy autoresponder binary to /usr/local/sbin
// cp autoresponder /usr/local/sbin/
// chown autoresponder:autoresponder /usr/local/sbin/autoresponder
// chmod 6755 /usr/local/sbin/autoresponder
//
// RESPONSE_DIR, RATE_LOG_DIR must be created:
// mkdir -p /var/spool/autoresponder/log /var/spool/autoresponder/responses
// chown -R autoresponder:autoresponder /var/spool/autoresponder
// chmod -R 0770 /var/spool/autoresponder
//
// Edit /etc/postfix/master.cf:
// Replace line:
// smtp inet n - - - - smtpd
// with these two lines (second must begin with at least one space or tab):
// smtp inet n - - - - smtpd
// -o content_filter=autoresponder:dummy
// At the end of file append the following two lines:
// autoresponder unix - n n - - pipe
// flags=Fq user=autoresponder argv=/usr/local/sbin/autoresponder -s ${sender} -r ${recipient} -S ${sasl_username} -C ${client_address}
//
// Set additional postfix parameter:
// postconf -e 'autoresponder_destination_recipient_limit = 1'
// service postfix restart
//
//
// Written by Uros Juvan <asmpro@gmail.com> 2017
import (
"fmt"
"flag"
"time"
"os"
"os/exec"
"io"
"io/ioutil"
"bufio"
"path/filepath"
"strings"
"log/syslog"
)
const VERSION = "1.0.0006"
const DEBUG = true
const RESPONSE_DIR = "/var/spool/autoresponder/responses"
const RATE_LOG_DIR = "/var/spool/autoresponder/log"
const SENDMAIL_BIN = "/usr/sbin/sendmail"
var syslg *syslog.Writer = nil
// Function using fmt.Printf for debug printing, but only if DEBUG is true
func DebugFmtPrintf(format string, v ...interface{}) {
if DEBUG {
fmt.Printf("DEBUG: " + format, v...)
}
}
func DebugSyslogFmt(format string, v ...interface{}) {
if syslg == nil {
return
}
if DEBUG {
syslg.Debug(fmt.Sprintf("DEBUG: " + format, v...))
}
}
// Return true if file exists and is regular file
func fileExists(name string) bool {
st, err := os.Lstat(name)
if err != nil || (st.Mode() & os.ModeType) != os.FileMode(0) {
return false
}
return true
}
// Send mail from address to address with given mail content being passed as function pointer
func sendMail(from, to string, populateStdin func(io.WriteCloser)) error {
cmd := exec.Command(SENDMAIL_BIN, "-i", "-f", from, to)
stdin, err := cmd.StdinPipe()
if err != nil {
return err
}
err = cmd.Start()
if err != nil {
return err
}
go func() {
populateStdin(stdin)
}()
err = cmd.Wait()
if err != nil {
return err
}
return nil
}
// Set autoresponse using supplied arguments and stdin (email body)
func setAutoresponseViaEmail(recipient, sender, saslUser, clientIp string) error {
senderResponsePath := filepath.Join(RESPONSE_DIR, sender)
if fileExists(senderResponsePath) {
err := deleteAutoresponse(sender, true)
if err != nil {
return err
}
if ! fileExists(senderResponsePath) {
syslg.Info(fmt.Sprintf("Autoresponse disabled for address %v by SASL authenticated user: %v from: %v",
sender, saslUser, clientIp))
// Send mail via sendmail
sendMail(recipient, sender, func(sink io.WriteCloser) {
defer sink.Close()
sink.Write([]byte(fmt.Sprintf("From: %v\nTo: %v\nSubject: Autoresponder\n\n"+
"Autoresponse disabled for %v by SASL authenticated user: %v from: %v\n",
recipient, sender, sender, saslUser, clientIp)))
})
} else {
return fmt.Errorf("Autoresponse could not be disabled for address %v", sender)
}
} else {
// Cat stdin to response file for the user, removing unneeded headers in the process
// Only From:, To: and Subject: are needed.
// To: ... is replaced with To: THIS GETS REPLACED
// Subject: ... is replaced with Subject: Autoresponder
fl, err := os.OpenFile(senderResponsePath, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0660)
if err != nil {
return fmt.Errorf("Autoresponse could not be enabled for address %v: %v", sender, err)
}
fl.Chmod(0660)
reader := bufio.NewReader(os.Stdin)
writer := bufio.NewWriter(fl)
defer func() {
writer.Flush()
fl.Close()
}()
state := 0
for {
line, err := reader.ReadString('\n')
if err != nil {
if err == io.EOF {
break
}
return err
}
//fmt.Printf("Read line: '%v'\n", line)
switch state {
// state 0 (mail header)
case 0:
if line == "\n" || line == "\r\n" || line == "\r" {
_, err = writer.WriteString(line)
state = 1
continue
}
switch true {
case strings.Index(strings.ToLower(line), "from: ") == 0 ||
strings.Index(strings.ToLower(line), "content-type: ") == 0 ||
strings.Index(strings.ToLower(line), "content-transfer-encoding: ") == 0 ||
strings.Index(strings.ToLower(line), "mime-version: ") == 0:
_, err = writer.WriteString(line)
case strings.Index(strings.ToLower(line), "to: ") == 0:
_, err = writer.WriteString("To: THIS GETS REPLACED\n")
case strings.Index(strings.ToLower(line), "subject: ") == 0:
_, err = writer.WriteString("Subject: Autoresponder\n")
}
case 1:
_, err = writer.WriteString(line)
}
if err != nil {
return err
}
}
if fileExists(senderResponsePath) {
syslg.Info(fmt.Sprintf("Autoresponse enabled for address %v by SASL authenticated user: %v from: %v",
sender, saslUser, clientIp))
// Send mail via sendmail
sendMail(recipient, sender, func(sink io.WriteCloser) {
defer sink.Close()
sink.Write([]byte(fmt.Sprintf("From: %v\nTo: %v\nSubject: Autoresponder\n\n"+
"Autoresponse enabled for %v by SASL authenticated user: %v from: %v\n",
recipient, sender, sender, saslUser, clientIp)))
})
} else {
return fmt.Errorf("Autoresponse could not be enabled for address %v", sender)
}
}
return nil
}
// Forward email using supplied arguments and stdin (email body)
func forwardEmailAndAutoresponse(recipient, sender, saslUser, clientIp string, responseRate uint) error {
recipientResponsePath := filepath.Join(RESPONSE_DIR, recipient)
recipientRateLog := filepath.Join(RATE_LOG_DIR, recipient)
recipientSenderRateLog := filepath.Join(RATE_LOG_DIR, recipient, sender)
if fileExists(recipientResponsePath) {
// Check rate log
sendResponse := true
if fileExists(recipientSenderRateLog) {
curTime := time.Now()
st, err := os.Stat(recipientSenderRateLog)
if err != nil {
return err
}
modTime := st.ModTime()
if int64(curTime.Sub(modTime)) / int64(time.Second) < int64(responseRate) {
sendResponse = false
syslg.Info(fmt.Sprintf("Autoresponse has already been sent from %v to %v within last %v seconds",
recipient, sender, responseRate))
}
}
// If sendResponse is true and sender and recipiend differ, then send response and touch rate log file
if sendResponse && strings.ToLower(recipient) != strings.ToLower(sender) {
//fmt.Println("Sending response")
fl, err := os.Open(recipientResponsePath)
if err != nil {
return err
}
defer fl.Close()
sendMail(recipient, sender, func(sink io.WriteCloser) {
defer sink.Close()
// Open recipientResponsePath file and do some replacements on the fly
reader := bufio.NewReader(fl)
state := 0
for {
line, err := reader.ReadString('\n')
if err != nil {
if err == io.EOF {
break
}
syslg.Err(err.Error())
return
}
switch state {
case 0:
switch true {
case line == "\n" || line == "\r\n" || line == "\r":
state = 1
case strings.Index(strings.ToLower(line), "from: ") == 0:
line = fmt.Sprintf("From: %v\n", recipient)
case strings.Index(strings.ToLower(line), "to: ") == 0:
line = fmt.Sprintf("To: %v\n", sender)
}
fallthrough
default:
sink.Write([]byte(line))
}
}
})
err = os.MkdirAll(recipientRateLog, 0770)
if err != nil {
return err
}
// Touch rate log file
fl, err = os.Create(recipientSenderRateLog)
if err != nil {
return err
}
fl.Close()
syslg.Info(fmt.Sprintf("Autoresponse sent from %v to %v", recipient, sender))
}
}
// Now resend original mail
sendMail(sender, recipient, func(sink io.WriteCloser) {
defer sink.Close()
io.Copy(sink, os.Stdin)
})
return nil
}
// Get text editor
func getTextEditor() string {
editor := os.Getenv("EDITOR")
if editor == "" {
editor = "vi"
}
return editor
}
// Get file modification time
func getFileModTime(name string) (t time.Time, err error) {
st, err := os.Stat(name)
if err != nil {
return t, err
}
t = st.ModTime()
return
}
// Enable autoresponse for email
func enableAutoresponse(email string) error {
emailResponsePath := filepath.Join(RESPONSE_DIR, email)
editFilePath := emailResponsePath
// If editFilePath does not exist, also try to enable previosly disabled autoresponse
if ! fileExists(editFilePath) {
enableExAutoresponse(email, true)
}
// If file does not exist yet, create template file as tmp file
var oldModTime, newModTime time.Time
if ! fileExists(editFilePath) {
editFile, err := ioutil.TempFile("", "autoresponder")
if err != nil {
return err
}
editFilePath = editFile.Name()
defer os.Remove(editFilePath)
writer := bufio.NewWriter(editFile)
// Write template to file
writer.WriteString(fmt.Sprintf(`From: %v
To: THIS GETS REPLACED
Content-Type: text/plain; charset=UTF-8
Subject: Autoresponder
mail body`, email))
writer.Flush()
editFile.Close()
}
oldModTime, err := getFileModTime(editFilePath)
if err != nil {
return err
}
// Invoke either EDITOR environment or vi command
cmd := exec.Command(getTextEditor(), editFilePath)
cmd.Stdin = os.Stdin
cmd.Stdout = os.Stdout
cmd.Stderr = os.Stderr
err = cmd.Run()
if err != nil {
return err
}
newModTime, err = getFileModTime(editFilePath)
if err != nil {
return err
}
if oldModTime != newModTime {
if emailResponsePath != editFilePath {
// Open editFilePath for reading and emailResponsePath for writing and Copy content over
tmpFl, err := os.Open(editFilePath)
if err != nil {
return err
}
defer tmpFl.Close()
resFl, err := os.OpenFile(emailResponsePath, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0660)
if err != nil {
return err
}
resFl.Chmod(0660)
defer resFl.Close()
_, err = io.Copy(resFl, tmpFl)
if err != nil {
return err
}
}
msg := fmt.Sprintf("Edited %v", emailResponsePath)
syslg.Info(msg)
fmt.Println(msg)
} else {
msg := fmt.Sprintf("Editing %v aborted!", emailResponsePath)
fmt.Println(msg)
return fmt.Errorf("%v", msg)
}
return nil
}
// Disable autoresponse for email
func disableAutoresponse(email string) error {
emailResponsePath := filepath.Join(RESPONSE_DIR, email)
if fileExists(emailResponsePath) {
disableEmailResponsePath := emailResponsePath + "_DISABLED"
os.Remove(disableEmailResponsePath)
err := os.Rename(emailResponsePath, disableEmailResponsePath)
if err != nil {
return err
}
msg := fmt.Sprintf("Disabled %v", emailResponsePath)
syslg.Info(msg)
fmt.Println(msg)
} else {
msg := fmt.Sprintf("%v does not exist, thus it cannot be disabled!", emailResponsePath)
fmt.Println(msg)
return fmt.Errorf("%v", msg)
}
return nil
}
// Enable existing autoresponse for email
func enableExAutoresponse(email string, nostdout bool) error {
emailResponsePath := filepath.Join(RESPONSE_DIR, email)
disableEmailResponsePath := emailResponsePath + "_DISABLED"
if fileExists(disableEmailResponsePath) {
os.Remove(emailResponsePath)
err := os.Rename(disableEmailResponsePath, emailResponsePath)
if err != nil {
return err
}
msg := fmt.Sprintf("Enabled %v", emailResponsePath)
syslg.Info(msg)
fmt.Println(msg)
} else {
msg := fmt.Sprintf("%v does not exist, thus it cannot be enabled!", disableEmailResponsePath)
if ! nostdout {
fmt.Println(msg)
}
return fmt.Errorf("%v", msg)
}
return nil
}
// Delete autoresponse for email
func deleteAutoresponse(email string, nostdout bool) error {
deleteResponsePath := filepath.Join(RESPONSE_DIR, email)
disabledDeleteResponsePath := deleteResponsePath + "_DISABLED"
recipientRateLog := filepath.Join(RATE_LOG_DIR, email)
if fileExists(deleteResponsePath) {
os.Remove(disabledDeleteResponsePath)
os.RemoveAll(recipientRateLog)
err := os.Remove(deleteResponsePath)
if err != nil {
msg := fmt.Sprintf("%v cannot be deleted: %v", deleteResponsePath, err)
if ! nostdout {
fmt.Println(msg)
}
return fmt.Errorf("%v", msg)
}
msg := fmt.Sprintf("Delete %v done", deleteResponsePath)
if ! nostdout {
fmt.Println(msg)
}
syslg.Info(msg)
} else {
msg := fmt.Sprintf("%v does not exist, thus it cannot be deleted!", deleteResponsePath)
if ! nostdout {
fmt.Println(msg)
}
return fmt.Errorf("%v", msg)
}
return nil
}
func main() {
// Connect to syslog
var err error
syslg, err = syslog.New(syslog.LOG_MAIL, "autoresponder")
if err != nil {
fmt.Println(err.Error())
os.Exit(1)
}
defer syslg.Close()
// Parse command line arguments
recipientPtr := flag.String("r", "", "Recipient e-mail")
senderPtr := flag.String("s", "", "Sender e-mail")
saslUserPtr := flag.String("S", "", "SASL authenticated username")
clientIpPtr := flag.String("C", "", "Client IP address")
enableAutoResponsePtr := flag.String("e", "", "Enable autoresponse")
disableAutoResponsePtr := flag.String("d", "", "Disable autoresponse")
enableExAutoResponsePtr := flag.String("E", "", "Enable existing autoresponse")
deleteAutoResponsePtr := flag.String("D", "", "Delete autoresponse")
instructionsPtr := flag.Bool("i", false, "Setup instructions")
responseRatePtr := flag.Uint("t", 86400, "Response rate in seconds (0 - send each time)")
showVersion := flag.Bool("V", false, "Show version and exit")
flag.Parse()
if *showVersion {
fmt.Printf("autoresponder %v, written by Uros Juvan <asmpro@gmail.com> 2017\n", VERSION)
os.Exit(0)
}
DebugSyslogFmt("Flags: Recipient: %v, Sender: %v, SASL authenticated username: %v, Client IP: %v, Enable autoresponse: %v, Disable autoresponse: %v, Enable existing autoresponse: %v, Delete autoresponse: %v, Setup instructions: %v, Response rate: %v",
*recipientPtr,
*senderPtr,
*saslUserPtr,
*clientIpPtr,
*enableAutoResponsePtr,
*disableAutoResponsePtr,
*enableExAutoResponsePtr,
*deleteAutoResponsePtr,
*instructionsPtr,
*responseRatePtr)
// If setup instructions are requested, just print them to stdout and exit
if *instructionsPtr {
fmt.Print(`
How to make it work on a server with postfix installed:
=======================================================
Create autoresponder username:
useradd -d /var/spool/autoresponder -s $(which nologin) autoresponder
Copy autoresponder binary to /usr/local/sbin
cp autoresponder /usr/local/sbin/
chown autoresponder:autoresponder /usr/local/sbin/autoresponder
chmod 6755 /usr/local/sbin/autoresponder
RESPONSE_DIR, RATE_LOG_DIR must be created:
mkdir -p /var/spool/autoresponder/log /var/spool/autoresponder/responses
chown -R autoresponder:autoresponder /var/spool/autoresponder
chmod -R 0770 /var/spool/autoresponder
Edit /etc/postfix/master.cf:
Replace line:
smtp inet n - - - - smtpd
with these two lines (second must begin with at least one space or tab):
smtp inet n - - - - smtpd
-o content_filter=autoresponder:dummy
At the end of file append the following two lines:
autoresponder unix - n n - - pipe
flags=Fq user=autoresponder argv=/usr/local/sbin/autoresponder -s ${sender} -r ${recipient} -S ${sasl_username} -C ${client_address}
Set additional postfix parameter:
postconf -e 'autoresponder_destination_recipient_limit = 1'
service postfix restart
`)
os.Exit(0)
}
// Do some logic on command line arguments
// Mode
// There are two different modes of operation:
// mode=0 represents the actions that can not be executed from the command line
// mode=1 represents the actions that can be executed from the command line
mode := 0
authenticated := false
if *saslUserPtr != "" {
authenticated = true
}
if *enableAutoResponsePtr != "" || *disableAutoResponsePtr != "" || *enableExAutoResponsePtr != "" || *deleteAutoResponsePtr != "" {
mode = 1
}
DebugSyslogFmt("mode=%v, authenticated=%v\n", mode, authenticated)
// Little more validation of recipient and sender
// Remove path ('/') from both recipient and sender
*recipientPtr = strings.Replace(*recipientPtr, "/", "", -1)
*senderPtr = strings.Replace(*senderPtr, "/", "", -1)
recipientParts := strings.Split(*recipientPtr, "@")
senderParts := strings.Split(*senderPtr, "@")
// And now descision making
DebugSyslogFmt("recipientUser=%v =? senderUser=%v\n", recipientParts[0], senderParts[0] + "+autoresponse")
switch true {
// - (un)set autoresponse via email
case mode == 0 && recipientParts[0] == senderParts[0] + "+autoresponse":
syslg.Info(fmt.Sprintf("Requested autoresponse (un)set via email for email %v", *senderPtr))
// Do not allow unauthenticated changes
if ! authenticated {
syslg.Warning(fmt.Sprintf("Unauthenticated attempt to set autoresponse message for %v from %v !",
*senderPtr, *clientIpPtr))
os.Exit(0)
}
err := setAutoresponseViaEmail(*recipientPtr, *senderPtr, *saslUserPtr, *clientIpPtr)
if err != nil {
syslg.Err(err.Error())
os.Exit(1)
}
// - forward mail and either send response if set and enough time has passed
case mode == 0 && strings.Index(*recipientPtr, "+autoresponse") == -1:
syslg.Info(fmt.Sprintf("Requested email forward from %v, to %v", *senderPtr, *recipientPtr))
err := forwardEmailAndAutoresponse(*recipientPtr, *senderPtr, *saslUserPtr, *clientIpPtr, *responseRatePtr)
if err != nil {
syslg.Err(err.Error())
os.Exit(1)
}
// - set autoresponse via cli
case mode == 1 && *enableAutoResponsePtr != "":
syslg.Info(fmt.Sprintf("Requested enable autoresponse for %v", *enableAutoResponsePtr))
err := enableAutoresponse(*enableAutoResponsePtr)
if err != nil {
syslg.Err(err.Error())
os.Exit(1)
}
// - disable autoresponse via cli
case mode == 1 && *disableAutoResponsePtr != "":
syslg.Info(fmt.Sprintf("Requested disable autoresponse for %v", *disableAutoResponsePtr))
err := disableAutoresponse(*disableAutoResponsePtr)
if err != nil {
syslg.Err(err.Error())
os.Exit(1)
}
// - enable existing autoresponse via cli
case mode == 1 && *enableExAutoResponsePtr != "":
syslg.Info(fmt.Sprintf("Requested enable existing autoresponse for %v", *enableExAutoResponsePtr))
err := enableExAutoresponse(*enableExAutoResponsePtr, false)
if err != nil {
syslg.Err(err.Error())
os.Exit(1)
}
// - delete existing autoresponse via cli
case mode == 1 && *deleteAutoResponsePtr != "":
syslg.Info(fmt.Sprintf("Requested delete autoresponse for %v", *deleteAutoResponsePtr))
err := deleteAutoresponse(*deleteAutoResponsePtr, false)
if err != nil {
syslg.Err(err.Error())
os.Exit(1)
}
}
}