maxrcpt patch for qmail-smtpd

    To: djb-qmail@xxxxxxxxxxxxxxxxxxxx
    Subject: maxrcpt patch for qmail-smtpd
    From: Michael Samuel <michael@xxxxxxxxxxxxxxxxxx>
    Date: Wed, 12 Nov 1997 15:18:38 +1100 (EST)
    Mailing-list: contact djb-qmail-help@xxxxxxxxxxxxxxxxxxxx; run by ezmlm

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Here is a patch for qmail-smtpd to read a control file to limit the number
of rcpt to commands.

In the patch I have a thank-you to Sam, this is referring to
mrsam@xxxxxxxxxxxxx who gave me the ideas on how to start off.

Anyway, it is a "Do what you like with it, but don't blame me" license,
but if it doesn't work, tell me what went wrong if you like and I will
try to figure it out.



Michael Samuel,

Surf-Net City - Internet Cafe and Internet Service Providers

                                Phone: +61 3 9593-9977
                                E-Mail: michael@xxxxxxxxxxxxxxxxxx

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Here is a patch I rigged up limit the number of RCPT TO: commands per E-Mail
messages.

It reads the file control/maxrcpt relative to your qmail directory stucture
(usually /var/qmail/control/maxrcpt).

In that file you should have a integer, which represents the maximum number
of recipients per E-Mail Messages.

Apparently one of the SMTP rfcs recommends a minimum of 100 recipients per
message be allowed.  Just something to keep in mind anyway.

If /var/qmail/control/maxrcpt doesn't exist, it does not impose a limit and
skips the rcpt part of the code, so unless I missed something in the source, 
you could even have more than MAXINT.

I would like to thank Sam from the qmail list for giving me a good start to
this patch, and anyone else who offered me suggestions from the qmail list.
(When I refer to qmail list, I'm referring to djb-qmail@xxxxxxxxxxxxxxxxxxxx)

To apply the patch, enter the qmail source directory and type:

patch -p1 < ~/qmail-1.01-maxrcpt.patch

Assuming that the patch is in your home directory.


diff -C 4 -c qmail-1.01/qmail-smtpd.c qmail-1.01-maxrcpt/qmail-smtpd.c
*** qmail-1.01/qmail-smtpd.c	Tue Apr 15 15:05:23 1997
--- qmail-1.01-maxrcpt/qmail-smtpd.c	Tue Nov 11 22:44:19 1997
***************
*** 21,28 ****
--- 21,30 ----
  #include "exit.h"
  
  #define MAXHOPS 100
  int timeout = 1200;
+ int rcptcounter = 0;
+ int maxrcpt = -1;
  
  char ssoutbuf[512];
  substdio ssout = SUBSTDIO_FDBUF(write,1,ssoutbuf,sizeof(ssoutbuf));
  
***************
*** 277,293 ****
--- 279,298 ----
   seenmail = 0;
   out("250 flushed\r\n"); }
  void smtp_mail(arg) char *arg; {
   if (seenmail) { err_seenmail(); return; }
+  rcptcounter = 0;
   if (!arg) { err_syntax(); return; }
   if (!addrparse(arg)) { err_syntax(); return; }
   bmfcheck();
   seenmail = 1; out("250 ok\r\n");
   if (!stralloc_copys(&rcptto,"")) outofmem();
   if (!stralloc_copys(&mailfrom,addr.s)) outofmem();
   if (!stralloc_0(&mailfrom)) outofmem(); }
  void smtp_rcpt(arg) char *arg; {
+  rcptcounter++;
   if (!seenmail) { err_wantmail(); return; }
+  if (checkrcptcount() == 1) {err_syntax(); return; }
   if (!arg) { err_syntax(); return; }
   if (!addrparse(arg)) { err_syntax(); return; }
   if (flagbarf) { err_bmf(); return; }
   if (relayclient)
***************
*** 401,408 ****
--- 406,414 ----
   switch(control_rldef(&liphost,"control/localiphost",1,(char *) 0))
    { case -1: die(); case 1: liphostok = 1; }
   if (control_readint(&timeout,"control/timeoutsmtpd") == -1) die();
   if (timeout <= 0) timeout = 1;
+  if (control_readint(&maxrcpt,"control/maxrcpt") == -1) die();
   switch(control_readfile(&rcpthosts,"control/rcpthosts",0))
    {
     case -1: die();
     case 1:
***************
*** 446,449 ****
--- 452,462 ----
     cmd.s[cmd.len++] = 0;
     doit(cmd.s);
    }
  }
+ 
+ int checkrcptcount() {
+   if (maxrcpt == -1) {return 0;}
+   else if (rcptcounter > maxrcpt) {return 1;}
+   else {return 0;}
+ }
+