Towards first version.

cmd/autoresponder.go

@@ -2,24 +2,75 @@ 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 autoresponse username:
+// useradd -d /var/spool/autoresponse -s `which nologin` autoresponse
+//
+// Copy autoresponse binary to /usr/local/sbin
+// cp autoresponse /usr/local/sbin/
+//
+// RESPONSE_DIR, RATE_LOG_DIR must be created:
+// mkdir -p /var/spool/autoresponse/log /var/spool/autoresponse/responses
+// chown -R autoresponse:autoresponse /var/spool/autoresponse
+// chmod -R 0770 /var/spool/autoresponse
+//
+// 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=autoresponse argv=/usr/local/sbin/autoresponse -s ${sender} -r ${recipient} -S ${sasl_username} -C ${client_address}
+//
+//
 // Written by Uros Juvan <asmpro@gmail.com> 2017
 
 import (
     "fmt"
     "flag"
     "os"
+    "strings"
+    "log/syslog"
 )
 
 const VERSION = "1.0.0001"
 const DEBUG = true
 
+const RESPONSE_DIR = "/var/spool/autoresponse/responses"
+const RATE_LOG_DIR = "/var/spool/autoresponse/log"
+const SENDMAIL_BIN = "/usr/sbin/sendmail"
+
+
+// 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(syslg *syslog.Writer, format string, v ...interface{})  {
+        if DEBUG {
+                syslg.Debug(fmt.Sprintf("DEBUG: " + format, v...))
+        }
+}
+
+// Set autoresponse using supplied arguments and stdin (email body)
+func setAutoresponseViaEmail(recipient, sender, saslUser, clientIp string) error {
+    //!!!
+
+    return nil
+}
 
 func main() {
+    // Connect to syslog
+    syslg, err := syslog.New(syslog.LOG_MAIL, "autoresponder")
+    if err != nil {
+        os.Exit(1)
+    }
+    defer syslg.Close()
+
     // Parse command line arguments
     recipientPtr := flag.String("r", "", "Recipient e-mail")
     senderPtr := flag.String("s", "", "Sender e-mail")
@@ -29,27 +80,47 @@ func main() {
     disableAutoResponsePtr := flag.String("d", "", "Disable autoresponse")
     enableExAutoResponsePtr := flag.String("E", "", "Enable existing autoresponse")
     deleteAutoResponsePtr := flag.String("D", "", "Delete autoresponse")
+    instructions := flag.Bool("i", false, "Setup instructions")
     flag.Parse()
 
-    if DEBUG {
-        DebugFmtPrintf(`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
-`,
-            *recipientPtr,
-            *senderPtr,
-            *saslUserPtr,
-            *clientIpPtr,
-            *enableAutoResponsePtr,
-            *disableAutoResponsePtr,
-            *enableExAutoResponsePtr,
-            *deleteAutoResponsePtr)
+    DebugSyslogFmt(syslg, "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",
+        *recipientPtr,
+        *senderPtr,
+        *saslUserPtr,
+        *clientIpPtr,
+        *enableAutoResponsePtr,
+        *disableAutoResponsePtr,
+        *enableExAutoResponsePtr,
+        *deleteAutoResponsePtr,
+        *instructions)
+
+    // If setup instructions are requested, just print them to stdout and exit
+    if *instructions {
+        fmt.Print(`
+ How to make it work on a server with postfix installed:
+ =======================================================
+ Create autoresponse username:
+ useradd -d /var/spool/autoresponse -s $(which nologin) autoresponse
+
+ Copy autoresponse binary to /usr/local/sbin
+ cp autoresponse /usr/local/sbin/
+
+ RESPONSE_DIR, RATE_LOG_DIR must be created:
+ mkdir -p /var/spool/autoresponse/log /var/spool/autoresponse/responses
+ chown -R autoresponse:autoresponse /var/spool/autoresponse
+ chmod -R 0770 /var/spool/autoresponse
+
+ 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=autoresponse argv=/usr/local/sbin/autoresponse -s ${sender} -r ${recipient} -S ${sasl_username} -C ${client_address}
+`)
+        os.Exit(0)
     }
 
     // Do some logic on command line arguments
@@ -63,11 +134,35 @@ func main() {
     if *recipientPtr != "" && *senderPtr != "" {
         sendResponse = true
     }
-    if *saslUserPtr != "" && os.Getenv("SASL_USERNAME") != "" {
+    if *saslUserPtr != "" {
         authenticated = true
     }
     if *enableAutoResponsePtr != "" || *disableAutoResponsePtr != "" || *enableExAutoResponsePtr != "" || *deleteAutoResponsePtr != "" {
         mode = 1
     }
-    DebugFmtPrintf("mode=%v, sendResponse=%v, authenticated=%v\n", mode, sendResponse, authenticated)
+    DebugSyslogFmt(syslg, "mode=%v, sendResponse=%v, authenticated=%v\n", mode, sendResponse, authenticated)
+
+    recipientParts := strings.Split(*recipientPtr, "@")
+    senderParts := strings.Split(*senderPtr, "@")
+    // Little more validation of recipient and sender
+    if len(recipientParts) < 2 {
+        syslg.Err(fmt.Sprintf("Invalid recipient %v", *recipientPtr))
+        os.Exit(1)
+    }
+    if len(senderParts) < 2 {
+        syslg.Err(fmt.Sprintf("Invalid sender %v", *senderPtr))
+        os.Exit(1)
+    }
+
+    // And now descision making
+    DebugSyslogFmt(syslg, "recipientUser=%v =? senderUser=%v\n", recipientParts[0], senderParts[0] + "+autoresponse")
+    if mode == 0 && authenticated && recipientParts[0] == senderParts[0] + "+autoresponse" {
+        syslg.Info(fmt.Sprintf("Requested autoresponse (un)set via email for email %v", *senderPtr))
+        err := setAutoresponseViaEmail(*recipientPtr, *senderPtr, *saslUserPtr, *clientIpPtr)
+        if err != nil {
+            syslg.Err(err.Error())
+            os.Exit(1)
+        }
+    }
+    //!!!
 }