nightmaremail

commit 0ed82f58cd3869b3d0196b692c65685b8d1faf8b
parent 17dc89aeebb0dc3bdcab9a34da6d44c40fd337dc
Author: Leah Neukirchen <leah@vuxu.org>
Date:   Wed,  8 Apr 2020 23:30:59 +0200

qmail-remote: remove flagcname, deprecated feature

qmail-remote used to rewrite the RCPT TO: domain when it was a CNAME,
as it was common before 2001.

RFC 5321 (from 2008), Section 5.1 clearly specifies what MTA should do
today:

  The lookup first attempts to locate an MX record associated with the
  name. If a CNAME record is found, the resulting name is processed as
  if it were the initial name.

djb wrote in https://cr.yp.to/im/cname.html:

  Most implementors agree that this feature is not worth the
  implementation costs. I recommend that, before January 2001, sites stop
  relying on client-side CNAME translation, so that implementors can
  safely remove the feature at that time.

Fixes #120.

Diffstat:
M
CHANGES.md
 | 
1
+
M
qmail-remote.c
 | 
16
++++------------

2 files changed, 5 insertions(+), 12 deletions(-)
diff --git a/CHANGES.md b/CHANGES.md
@@ -1,3 +1,4 @@
+- 20200614 stop rewriting RCPT TO: domains when they are a CNAME (RFC 5321 5.1)
 - 20200523 doc: give text files .md extensions.
 - 20200523 cleanup: remove qsmhook, replaced by preline.
 - 20200520 remove wrappers for obsolete mail clients without maildir support
diff --git a/qmail-remote.c b/qmail-remote.c
@@ -275,15 +275,14 @@ void smtp()
 stralloc canonhost = {0};
 stralloc canonbox = {0};
 
-void addrmangle(saout,s,flagalias,flagcname)
+void addrmangle(saout,s,flagalias)
 stralloc *saout; /* host has to be canonical, box has to be quoted */
 char *s;
 int *flagalias;
-int flagcname;
 {
   int j;
  
-  *flagalias = flagcname;
+  *flagalias = 0;
  
   j = str_rchr(s,'@');
   if (!s[j]) {
@@ -296,13 +295,6 @@ int flagcname;
   if (!stralloc_cats(saout,"@")) temp_nomem();
  
   if (!stralloc_copys(&canonhost,s + j + 1)) temp_nomem();
-  if (flagcname)
-    switch(dns_cname(&canonhost)) {
-      case 0: *flagalias = 0; break;
-      case DNS_MEM: temp_nomem();
-      case DNS_SOFT: temp_dnscanon();
-      case DNS_HARD: ; /* alias loop, not our problem */
-    }
 
   if (!stralloc_cat(saout,&canonhost)) temp_nomem();
 }
@@ -361,7 +353,7 @@ int main(int argc, char **argv)
   }
 
 
-  addrmangle(&sender,argv[2],&flagalias,0);
+  addrmangle(&sender,argv[2],&flagalias);
  
   if (!saa_readyplus(&reciplist,0)) temp_nomem();
   if (ipme_init() != 1) temp_oserr();
@@ -371,7 +363,7 @@ int main(int argc, char **argv)
   while (*recips) {
     if (!saa_readyplus(&reciplist,1)) temp_nomem();
     reciplist.sa[reciplist.len] = sauninit;
-    addrmangle(reciplist.sa + reciplist.len,*recips,&flagalias,!relayhost);
+    addrmangle(reciplist.sa + reciplist.len,*recips,&flagalias);
     if (!flagalias) flagallaliases = 0;
     ++reciplist.len;
     ++recips;