This patch makes two unrelated but useful changes to rblsmtpd, the
altreply patch and a new detour patch.

The altreply patch handles DNSBLs with A records but no TXT records.
You say:

 -r some.dnsbl.org:The rejection message

The string %IP% is replaced by the current IP in the rejection message.

The detour patch adds a -d flag that changes the interpretation of
DNSBLs.  Rather than running the rejection server, it sets an
environemnt variable, given as the argument to the -d flag and runs
the usual smtp daemon.

Normally you set RELAYCLIENT to make qmail-smtpd detour the mail into
a locally handled virtual domain, e.g.:

     /usr/local/bin/rblsmtpd -b \
        -d 'RELAYCLIENT=@detour'" \
	-r'sbl.spamhaus.org' \
	-d ""
	-r'relays.visi.com' \
	/var/qmail/bin/qmail-smtpd 2>&1

A -d flag with a null argument turns off -d, so in this case, mail
from hosts in the SBL is detoured, mail in the visi list is rejected.

John Levine, johnl@taugh.com, 4/04



diff ucspi-tcp-0.88-dist/rblsmtpd.c ucspi-tcp-0.88/rblsmtpd.c
58a59,61
> static char *dflag;
> static char *detour;
> 
62a66,67
>   int i;
>   char *altreply = 0;
64a70,74
>   i = str_chr(base, ':');
>   if (base[i]) {
>     base[i] = 0;
>     altreply = base+i+1;
>   }
66,70c76,112
<   if (dns_txt(&text,&tmp) == -1) {
<     flagmustnotbounce = 1;
<     if (flagfailclosed) {
<       if (!stralloc_copys(&text,"temporary RBL lookup error")) nomem();
<       decision = 2;
---
>   if (altreply) {
>     if (dns_ip4(&text,&tmp) == -1) {
>       flagmustnotbounce = 1;
>       if (flagfailclosed) {
>         if (!stralloc_copys(&text,"temporary RBL lookup error")) nomem();
>         decision = 2;
>       }
>       return;
>     }
>     if (text.len) {
>       if(!stralloc_copys(&text, "")) nomem();
>       while(*altreply) {
>         char *x;
>         i = str_chr(altreply, '%');
>         if(!stralloc_catb(&text, altreply, i)) nomem();
>         if(altreply[i] &&
>            altreply[i+1]=='I' &&
>            altreply[i+2]=='P' &&
>            altreply[i+3]=='%') {
>           if(!stralloc_catb(&text, ip_env, str_len(ip_env))) nomem();
>           altreply+=i+4;
>         } else if(altreply[i]) {
>           if(!stralloc_cats(&text, "%")) nomem();
>           altreply+=i+1;
>         } else {
>           altreply+=i;
>         }
>       }
>     }
>   } else {
>     if (dns_txt(&text,&tmp) == -1) {
>       flagmustnotbounce = 1;
>       if (flagfailclosed) {
>         if (!stralloc_copys(&text,"temporary RBL lookup error")) nomem();
>         decision = 2;
>       }
>       return;
72d113
<     return;
75c116,118
<     if (flagrblbounce)
---
>     if(dflag && *dflag) {
>       detour = dflag; decision = 1;
>     } else if (flagrblbounce)
178c221
<   while ((opt = getopt(argc,argv,"bBcCt:r:a:")) != opteof)
---
>   while ((opt = getopt(argc,argv,"bBcCt:r:a:d:")) != opteof)
186a230
>       case 'd': dflag = optarg; break;
196c240,242
<   pathexec_run(*argv,argv,envp);
---
>   if (detour) if (!pathexec_env(detour, 0)) nomem();
> 
>   pathexec(argv);